Biosorption of Toxic Zn(ll) Ion from Water Using Ion Imprinted Interpenetrating Polymer Networks

ENZYME CONCENTRATIONS AND ENZYME ACTIVITY: PLANNING SHEETPurpose∙To investigate how enzyme concentration can affect the initial rate of reaction.∙To develop practical skills.SAFETYWear eye protection, lab coats and disposable gloves.All enzymes are potential allergens and skin contact should be avoided. Any spillages ontothe skin should be washed off immediately. Asthma sufferers may be particularly sensitive,so alert your teacher.Hydrogen peroxide is corrosive. Use with great care avoiding contact with eyes, skin andclothing. Any spillages onto the skin should be washed off immediately.Use the knife with care, cutting on a secure surface.Reducing concentrationIf someone’s pancreatic duct becomes blocked it reduces or prevents the release of pancreatic enzymes into the small intestine. The aim of this activity is to investigate the effect of a reduction in enzyme concentration on the initial rate of reaction. The pancreas releases several enzymes, including proteases, which could be used to investigate the effect of enzyme concentration on initial rate of reaction. Other enzymes, including catalase, could be used to investigate the effect of enzyme concentration on initial rate of reaction. Catalase is not released by the pancreas: it occurs in most cells to break down toxic hydrogen peroxide, the by-product of various biochemical reactions.Why do we measure the initial rate of reaction?At the start of an enzyme experiment in the lab there will be a fixed amount of substrate in the test tube and no product. As the reaction proceeds, the amount of substrate decreases and the amount of product increases. Therefore the chance of a substrate molecule colliding with an enzyme goes down, so the rate of reaction is slower than at the start. For this reason, when carrying out enzyme catalysed reactions, it is the initial rate of the reaction that is the most valid measurement to take; it will give the rate of the reaction under the desired conditions.1 Scientific questions and information researchMilk powder contains a white protein called casein. A white suspension of milk powder clears on the addition of the enzyme trypsin. Hydrogen peroxide is broken down by the enzyme catalase, forming water and oxygen gas.Research relevant information and decide what you think the relationship will be between the enzyme concentration and the initial rate of reaction. Make sure that you understand and explain why we are only interested in the initial breakdown of the substrate. Write down your idea as a hypothesis that you can test. Use scientific ideas to support your prediction.2 Planning and experimental designYou are provided with the following equipment:●Standard acidified protease solution or a cylinder of potato tissue (a source of catalase).●Milk powder or hydrogen peroxide solution (the substrate).●Standard laboratory glassware and apparatus including a ruler, stopclock and thermometer.● A colorimeter and cuvette.NB: Casein will hydrolyse in acid conditions without addition of the enzyme.Plan an experiment that will test your hypothesis. Make sure your plan:∙includes a hypothesis about enzyme concentration and the breakdown of substrate, with a scientific explanation to support your ideas∙includes a procedure that uses suitable apparatus to produce measurements that will validly test your hypothesis∙includes a method that allows you to assess the initial rate of reaction∙identifies the dependent and independent variables and, where possible, controls or allows for other variables∙has a control and replicates, and that you have explained why these are necessary∙says exactly what measurements you will make and how they will be made∙says how you will make sure the results are valid, accurate, precise and repeatable∙identifies any possible sources of error∙includes a risk assessment with any safety precautions you will take.Refer to the Developing Practical Skills Framework in Practical Skills Support for guidance on planning an experiment.Have your plan checked by your teacher/lecturer before starting the experiment.On completion of the experiment make sure you have presented your results in the most appropriate way, and identified and explained any trends or patterns in your results, supporting your statements with evidence from your data. Also, using biological knowledge, you should have commented on any variation and possible errors within the data, and proposed changes to your procedure that would improve the experimental results.The effect of substrate concentrationHaving successfully completed the practical work to determine the effect of enzyme concentration, modify your experimental procedure to show how you would investigate the effect of substrate concentration on initial rate of enzyme reaction.ENZYME CONCENTRATIONS AND ENZYME ACTIVITYPurpose∙ To investigate how enzyme concentration can affect the initial rate of reaction.∙ To develop practical skills.SAFETYEnsure eye protection, lab coats and disposable gloves are worn throughout.All enzymes are potential allergens and skin contact should be avoided. Any spillages ontothe skin should be washed off immediately. If enzyme solutions are made up from solids thisshould not be done by students and precautions should be taken to avoid raising dust.Asthma sufferers may be particularly sensitive.Hydrogen peroxide is corrosive. Directly supervise its use ensuring it is handled with care,avoiding contact with the skin, eyes and clothing. Any spillages onto the skin should be washedoff immediately.Ensure knives are used with care on secure surfaces. Demonstrate a safe method for cutting materials.Notes on the procedureStudents should be given the opportunity to plan this experiment themselves. A planning sheet is provided. The experimental work is placed in the context of the reduced enzyme secretions from the pancreatic duct, which occurs with cystic fibrosis (CF). The use of a protease enzyme would strengthen this link, but there are different enzymes and methods that can be used in this experiment. Students will require some guidance before they start planning, regarding the type of enzyme and substrate to use and a method of assessing the initial rate of reaction. Students could be shown the type of equipment available and a class discussion about what should be included in the practical plan is appropriate. The Developing Practical Skills support provides a framework for the steps in completing an investigation. This can be used to guide students through the process. Once the investigation has been completed students could use the Developing Practical Skills Self-evaluation Sheet to reflect on what they have done in this practical.Two possible methods (A and B) are given below. The methods provided are not fully comprehensive, but provide a starting point if required. Students need to measure initial rate of reaction. This is done by measuring the slope of the time-course graph at each concentration and plotting a summary graph of initial rate against enzyme concentration.Either individually or in pairs students could complete an agreed procedure for one of the concentrations and then share results to complete the summary graph.Some centres have reported very good results for the dried milk experiment, while for others the dried milk powder did not break down. It is always best to check the enzyme activity in advance.In the ICT support there is a datalogging sheet on monitoring an enzyme-catalysed reaction.The Core Practical requires investigation of enzyme and substrate concentration. Having completed the practical investigating enzyme concentration, students can plan how to investigate substrate concentration, which would use a similar procedure with the enzyme concentration remaining the same but varying the substrate concentration. If time is available students could complete this in addition to completing the planning activity.You need:● Milk powder solution● Test tubes, flat-bottomed tubes or conical flasks● Test tube holder● Stopclock ● Standard protease solution 1% ● 5 cm 3 pipettes, syringe or measuring cylinder ● Glassware for diluting enzymesPurpose∙To investigate how enzyme concentration can affect the initial rate of reaction. ∙ To develop practical skills. What do you think will be the effect of reducing the concentration of the protease enzyme on theinitial rate of breakdown of the protein found in milk powder? Use scientific ideas to support your idea (hypothesis).SAFETYWear eye protection, lab coats and disposable gloves.All enzymes are potential allergens and skin contact should be avoided. Any spillages ontothe skin should be washed off immediately. Asthma sufferers may be particularly sensitive,so alert your teacher.Procedure1Pipette 2 cm 3 of protein solution into a cuvette. 2 Pipette 2 cm 3 of the protease solution into the cuvette. Mix thoroughly and immediately put thiscuvette into the colorimeter and start the stopclock.3 Measure absorbance at suitable time intervals for 5 minutes or until there is little change inreaction.4 Discard the content of the cuvette and rinse with distilled water.5 Plot a graph of absorbance against time. Use the graph to determine the initial rate of reaction.This is the initial gradient of the graph and should be the steepest part. Calculate the initial rate bydividing the change in they-axis by the change in the x -axis values and use the units you haveplotted on your y - and x -axes.6 Repeat steps 1 to 5 of the experiment using a range of different enzyme concentrations, ensuringthat other conditions are unchanged. Plot a separate absorbance against time graph for eachenzyme concentration and calculate an initial rate of reaction from each one.7 Present your results in the most appropriate way.8 Identify any trends in your results.9 Explain any trends or patterns, supporting your statements with evidence from your data andusing biological knowledge.10 State a clear conclusion to your work, summarising what you have found out and comment on thevalidity of your conclusion.Comment on the accuracy and precision of your results. Suggest any modifications to your procedure that would improve the experiment.The effect of substrate concentrationHaving successfully completed the practical work to determine the effect of enzyme concentration, modify your experimental procedure to show how you would investigate the effect of substrateconcentration on initial rate of enzyme reaction.You need● Cylinders of potato tissue● Hydrogen peroxide solution● Buffer solution pH 7.2● Distilled water● Boiling tube● Bung and delivery tube● 250 cm 3 beakers● Small beaker● 10 cm 3 syringe barrel● 2 ⨯ 10 cm 3 syringes or graduated pipettes● Short piece of rubber tubing ● Screw clip ● Cork borer ● Measuring cylinder ● Thermometer ● Stopclock ● Glass rod ● Sharp knife ● White tile ● Forceps ● Water bathPurpose∙To investigate how enzyme concentration can affect the initial rate of reaction. ∙ To develop practical skills.Catalase is an enzyme that occurs in most plant and animal cells. It catalyses the reaction:2H2O 2 → 2H 2O + O 2What do you think will be the effect of reducing the concentration of catalase on the initial rate ofbreakdown of the substrate, hydrogen peroxide? Use scientific ideas to support your idea (hypothesis). The initial rate of reaction can be measured by determining the volume of oxygen gas produced in a unit of time using the apparatus shown in Figure 1. Potato tissue provides a source of catalase.SAFETYWear eye protection, lab coats and disposable gloves.Hydrogen peroxide is corrosive. Use with great care avoiding contact with eyes, skin andclothing. Any spillages onto the skin should be washed off immediately.Use the knife with care, cutting on a secure surface. Demonstrate a safe method for cuttingmaterials.Procedure1Set up the apparatus as shown in Figure 1, with the collecting tube filled with water and the screw clip closed. 2Cut 10 discs of potato, each 0.2 mm thick. Place these in the boiling tube with 5 cm 3 of buffer solution. 3 Add 5 cm 3 of hydrogen peroxide solution to the potato discs. Immediately place the bung anddelivery tube firmly into the boiling tube. Place the other end of the delivery tube under thecollecting tube.4 Start a stopclock as soon as the first bubble of oxygen enters the collecting tube from the deliverytube. Collect any gas produced at suitable time intervals for 5 minutes or until there is littlechange in the volume. Shake the boiling tube gently throughout the reaction period to keep thecontents well mixed. Measure the volume of oxygen produced by raising the collecting tube sothat the water level in the tube is level with the surrounding water level in the beaker. Wash outthe boiling tube thoroughly.5Plot a graph of volume of gas produced against time. Use the graph to determine the initial rate ofreaction. This is the initial gradient of the graph and should be the steepest part. Calculate theinitial rate by dividing the change in the y -axis by the change in the x -axis values and use the unitsyou have plotted on your x - and y -axes.6 Repeat steps 1 to 5 of the experiment using a range of numbers of potato discs, ensuring that otherconditions are unchanged. Open the screw clip to refill the collecting tube and then tighten again.Plot a separate volume of gas produced against time graph for each enzyme concentration and calculate an initial rate of reaction from each one.7 Present your results in the most appropriate way.8 Identify any trends in your results.9 Explain any trends or patterns, supporting your statements with evidence from your data andusing biological knowledge.10 State a clear conclusion to your work, summarising what you have found out and comment on thevalidity of your conclusion.11 Comment on the accuracy and precision of your results. Suggest any modifications to yourprocedure that would improve the experiment.Figure 1 Apparatus for investigating catalase activity.The effect of substrate concentrationHaving successfully completed the practical work to determine the effect of enzyme concentration, modify your experimental procedure to show how you would investigate the effect of substrate concentration on initial rate of enzyme reaction.ENZYME CONCENTRATIONS AND ENZYME ACTIVITYPurpose∙To investigate how enzyme concentration can affect the rate of reaction.∙To develop practical skills.SAFETYWear eye protection, lab coats and disposable gloves.All enzymes are potential allergens and skin contact should be avoided. Enzyme powdersare irritants and potential allergens. If enzyme solutions are made up from solids this shouldnot be done by students and precautions should be taken to avoid raising dust. Avoid inhalation of powder and wear eye protection and gloves when handling powders. Rinsewith lots of water if you come in contact with the enzymes. All spills should be moistenedand wiped up immediately. Asthma sufferers may be particularly sensitive. Hydrogen peroxide is corrosive; use with great care and avoid contact with skin, eyes and clothing.The requirements for this practical will depend on whether the students undertake the planning themselves or are guided. Two basic experimental procedures are provided as a starting point and possible requirements are detailed below. Note that the requirements are given per student per concentration investigated. Students are likely to want to investigate five concentrations each. Procedure A: Using milk and trypsinRequirements per student orgroup of studentsNotesFor each concentration studentsinvestigate, they will need:5 cm3 casein or milk powder suspension (5%) To make milk suspension use 5 g milk powder in 100 cm3 water. Marvel® has been found to be the best milk powder to use: it is almost fat-free.5 ml trypsin solution Mix 0.5 g trypsin powder in 100 cm3 water. Add enough alkali (forexample, dilute sodium hydroxide) while mixing it up to produce a pHof 9. It is recommended to use a buffer solution to produce a morestable pH. If making up enzyme solutions do not heat to dissolve.Students will also need to dilute this standard solution to give 0.1%,0.2%, 0.3% and 0.4% solutions.Test tubes, flat-bottomed tubes, orconical flasksTest tube holderStopclockTwo 5 cm3 pipettes syringes ormeasuring cylinders50 cm3 beakerEye protectionProcedure B: Using catalase and hydrogen peroxideNotesRequirements per student orgroup of studentsCylinder of potato tissue Students can cut these for themselves using a cork borer and whitetile.Hydrogen peroxide solution 20 volume.Buffer solution pH 7.2Distilled waterBoiling tubeBung and delivery tube250 cm3 beakersSmall beaker10 cm3 syringe barrel To collect the oxygen evolved, a small measuring cylinder could beused as an alternative, but the syringe barrel with a rubber tube andscrew clip allows the collecting tube to be filled with water very easilyby loosening the screw clip.2 10 cm3 syringes or graduatedpipettesShort piece of rubber tubingScrew clipMeasuring cylinderThermometerStopclockGlass rodCork borer To cut cylinders of potato.Sharp knifeWhite tileForcepsWater bath Beaker of water to maintain the reaction tube at a constanttemperature would be adequate.。

The role of natural and synthetic zeolites as feed additives on the prevention and/or the treatment of certain farmanimal diseases:A reviewD.Papaioannou,P.D.Katsoulos,N.Panousis *,H.KaratziasClinic of Productive Animal Medicine,School of Veterinary Medicine,Aristotle University of Thessaloniki,54124Thessaloniki,GreeceReceived 4April 2005;received in revised form 12May 2005;accepted 12May 2005Available online 28June 2005AbstractThe present review comments on the role of the use of zeolites as feed additives on the prevention and/or the treatment of certain farm animal diseases.Both natural and synthetic zeolites have been used in animal nutrition mainly to improve performance traits and,based on their fundamental physicochemical properties,they were also tested and found to be efficacious in the prevention of ammonia and heavy metal toxicities,poisonings as well as radioactive elements uptake and metabolic skeletal defects.During the last decade,their utilization as mycotoxin-binding adsorbents has been a topic of considerable interest and many published research data indicate their potential efficacy against different types of mycotoxins either as a primary material or after specific modifications related to their surface properties.Ingested zeolites are involved in many biochemical processes through ion exchange,adsorption and catalysis.Recent findings support their role in the prevention of certain metabolic diseases in dairy cows,as well as their shifting effect on nitrogen excretion from urine to faeces in monogastric animals,which results in lower aerial ammonia concentration in the confinement facilities.Moreover,new evidence provide insights into potential mechanisms involved in zeolites supporting effect on animals suffered from gastrointestinal disturbances,including intestinal parasite infections.All the proposed mechanisms of zeolites Õeffects are summarized in the present review and possible focus topics for further research in selected areas are suggested.Ó2005Elsevier Inc.All rights reserved.Keywords:Zeolites;Animal health;Prevention;Treatment1.IntroductionZeolites are crystalline,hydrated aluminosilicates of alkali and alkaline earth cations,consisting of three-dimensional frameworks of SiO 4À4and AlO 5À4tetrahedra linked through the shared oxygen atoms.Both natural and synthetic zeolites are porous materials,character-ized by the ability to lose and gain water reversibly,to adsorb molecules of appropriate cross-sectional diame-ter (adsorption property,or acting as molecular sieves)and to exchange their constituent cations without majorchange of their structure (ion-exchange property)[1,2].The exploitation of these properties underlies the use of zeolites in a wide range of industrial and agricultural applications and particularly in animal nutrition since mid-1960s [3].Many researchers have proved that the dietary inclu-sion of zeolites improves average daily gain and/or feed conversion in pigs [1,4–13],calves [1,7],sheep [7,14–16],and broilers [17–19].Zeolites also enhance the reproduc-tive performance of sows [1,20,21],increase the milk yield of dairy cows [22,23]and the egg production of laying hens [24,25]and have beneficial effects on egg weight and the interior egg characteristics [24–26].How-ever,the extent of performance enhancement effects is related to the type of the used zeolite,its purity and1387-1811/$-see front matter Ó2005Elsevier Inc.All rights reserved.doi:10.1016/j.micromeso.2005.05.030*Corresponding author.Tel.:+302310994501;fax:+302310994550.E-mail address:panousis@vet.auth.gr (N.Panousis)./locate/micromesoMicroporous and Mesoporous Materials 84(2005)161–170physicochemical properties,as well as to the supplemen-tation level used in the diets.Besides,the particle size of the zeolitic material,crystallite size and the degree of aggregation,as well as the porosity of individual parti-cles determine the access of ingestafluids to the zeolitic surface during passage across gastrointestinal tract and strongly affect its ion exchange,adsorption and catalytic properties.Table1summarizes the possible mechanisms by which zeolites may exert their performance promot-ing properties in farm animals.Apart from the positive effects on animalsÕperfor-mance,dietary supplementation of zeolites appears to represent an efficacious,complementary,supportive strategy in the prevention of certain diseases and the improvement of animalsÕhealth status.The aim of the present review article is to address the data concerning the influence of the in-feed inclusion of natural and syn-thetic zeolites on certain diseases of farm animals,to summarize the proposed mechanisms of zeolitesÕeffects and to suggest possible focus topics for further research in selected areas.2.Ameliorative effect on the consequences of mycotoxicosesIn the recent years,high incidence rates of contami-nation of cereal grains and animal feed with mycotoxins are reported worldwide[38].One of the latest ap-proaches to this global concern has been the use of nutritionally inert adsorbents in the diet that sequester mycotoxins,thus reducing intestinal absorption and, additionally,avoiding toxic effects for livestock and the carry-over of toxin compounds to animal products. For this purpose,phyllosilicates such as hydrated sodium calcium aluminosilicates(HSCAS)and benton-ite––which consist of layered crystalline structures and possess similar physicochemical properties with zeo-lites––have beenfirst used successfully in poultry,pig, sheep,cattle and laboratory animals[33,34,39–47].Apart from phyllosilicates,the use of zeolites has shown,lately,very promising results as well.In general, adsorption process on binders is strongly related to charge distribution,pore dimensions and accessible sur-face area of the adsorbent,as well as to polarity,solubil-ity and molecular dimensions of the certain mycotoxin which is to be adsorbed[46].Molecular sizes of aflatox-ins range from5.18A˚(B1and B2)to6.50A˚(G1and G2) and only zeolites with entry channels wide enough to permit the diffusion of aflatoxin molecules to the intra-crystalline structure are capable of demonstrating a clear sequestering effect.Clinoptilolite,a natural zeolite,has high adsorption indexes in vitro,more than80%,for aflatoxins B1[48,49]and G2[48]and the adsorption pro-cess begins with a fast reaction whereby most of the toxin is adsorbed within thefirst few minutes[48].On the contrary,Lemke et al.[50]conducted a variety of in vitro adsorption studies and reported a limited degree of clinoptilolite ability to bind aflatoxin B1effectively. According to them,adsorbent materials should be checked through a multi-tiered system of in vitro tests in order potential interactive factors,such as intestinal physicochemical variables and feed components,to be precluded.Indeed,a previous in vitro study had demon-strated average aflatoxin retention in natural zeolites of 60%,but also a nitrogen compound-related adsorbent effectiveness,when liquid media quality parameters had been taken into account[51].The in vivo efficacy of zeolites to ameliorate the consequences of aflatoxico-sis,mainly in poultry,has also been verified in many cases(Table2).In the case of phyllosilicates,the results of in vitro mycotoxin–clay interaction tests suggest the existence of areas of heterogenous adsorption affinities onto sur-face,the presence of different adsorption mechanisms or both[57].Nevertheless,the formation of strong bonds by chemisorption and the interaction of b-car-bonyl group of aflatoxin B1with the uncoordinated edge site aluminum ions in these adsorbents have been suggested as the binding mechanism which interprets their well-established high affinity for aflatoxin B1 [39,58,59].Although the exact binding mechanisms of zeolites on aflatoxins have not been determined the pos-sibility to act through similar with phyllosilicates mech-anism cannot be precluded and should be investigated.As far as other mycotoxins are concerned,mineral adsorbents exert a lower efficacy against mycotoxins containing less polar functional groups,which are required for efficient chemisorption on hydrophilic negatively charged mineral surfaces to occur.This limi-tation can be overcome by the use of chemically modi-fied clays.Modifications consist of alterations ofTable1Proposed mechanisms involved in animalsÕperformance promoting properties of the dietary use of zeolitesMechanismsAmmonia binding effect Elimination of toxic effects of NHþ4produced by intestinal microbial activity[8,10]Fecal elimination of p-cresol Reduction of the absorption of toxic products of intestinal microbial degradation,such as p-cresol[27] Retarding effect on digesta transit Slower passage rate of digesta through the intestines and more efficient use of nutrients[1,25,28] Enhanced pancreatic enzymes activity Favorable effect on feed components hydrolysis over a wider range of pH,improved energy and protein retention[29,30]Aflatoxin sequestering effect Elimination of mycotoxin growth inhibitory effects[31–37]162 D.Papaioannou et al./Microporous and Mesoporous Materials84(2005)161–170surface properties resulting in an increased hydropho-bicity,by exchange of structural charge-balance cations with high molecular weight quaternary amines.In vitro results have verified the binding efficacy of modified montmorilonite and clinoptilolite against zearalenone and ochratoxin A[60,61].However,naturally occurring clays also exert a moderate binding efficacy against mycotoxins,other than aflatoxins,as evidenced for zearalenone and ochratoxin A by in vitro[57]andfield trials[62,63],as well as for cyclopiazonic acid in exper-iments with broilers[45].Remarkable conclusions related to zeolitesÕefficacy against zearalenone toxicosis have also been drawn by in vivo studies.Feeding zearalenone to rats,Smith[64] demonstrated that the dietary use of a synthetic anion exchange zeolite could alter the faecal and urinary excre-tory patterns of zearalenone due to the elimination of its intestinal absorption.Recently,the dietary use of a clin-optilolite-rich tuffwas also effective in decreasing zearal-enone and a-zearalenole excretion in pigs fed diets contaminated with500ppb zearalenone[65].Addition-ally,in afield-case of zearalenone toxicosis with mean concentrations of660ppb,Papaioannou et al.[20] reported that the supplementation of a clinoptilolite rich tuffat the rate of2%in the ration of pregnant sows im-plied a rather protective role against the consequences of zearalenone ingestion,as evidenced by the improvement of indicative performance traits.Similar results were also obtained in swine with the dietary use of a modified clinoptilolite–healandite rich tuffat0.2%and with zea-ralenone concentration exceeding3.5ppm[66].Apart from surface interactions,the in vivo efficacy of mineral adsorbents against zearalenone could also re-sult from other implicating mechanisms.The entero-he-patic circulation of zearalenone and its derivatives in pigs retards their elimination and enhances the duration of adverse effects[67].Whether certain types of zeolites are able to affect the entero-hepatic cycling of zearale-none,thus counteracting the toxic effects of its biological action,is a hypothesis that awaits further research, although there is evidence of Ca-enriched clinoptiloliteÕs high affinity to the bile acids in the intestinal tract[68].3.Supportive effect on diarrhoea syndromeThere is an abundance of published data which indi-cate that the dietary use of natural zeolites reduces the incidence and decreases the severity and the duration of diarrhoea in calves[1,69–72]and pigs[1,5,13,72–75]. The exact mechanism of zeolitesÕeffect is not quite clear so far,although there is evidence that the use of zeolites may eliminate various predisposing and/or causative fac-tors which are associated in the culmination of intestinal disturbances in an interactive way.Apart from zeolitesÕretarding effect on intestinal passage rate[1]and their water adsorption property,which leads to the appear-ance of drier and more compact faeces,as in the case of phillipsite[75]or clinoptilolite[76],Vrzgula et al.[71]also proposed that the ameliorative effect on diar-rhoea syndrome of calves might result from either the alteration of metabolic acidosis,through effects on os-motic pressure in the intestinal lumen,or the increased retention of the enteropathogenic Escherichia coli.As far as we know,there is no evidence in the available lit-erature for retention of enteropathogenic E.coli on the outer surface of zeolite particles.However,clinoptilolite and mordenite are capable to adsorb and partially inac-tivate the thermo-labile(LT)E.coli enterotoxin in vitro, thus constricting its attachment to the intestinalTable2In vivo studies concerning the effect of the dietary use of zeolites during aflatoxicosesType of zeolite Dietary inclusion rate(%)Animal model ObservationsClinoptilolite1Broilers Growth depression caused by2.5ppm aflatoxin(afl)was alleviated by15%[31] Clinoptilolite5Geese Prophylactic effect on growth rate and liver enzymatic activity[32]Mordenite0.5Broilers Reducing effect on toxicity of afl(3.5mg kgÀ1diet)as indicated byweight gain and changes in uric acid and albumin concentrations[33] Clinoptilolite0.5Weaned piglets Growth inhibitory effects and alterations of liver enzyme activity inducedby500ppb aflwere prevented[34]Synthetic zeolite0.5Broilers No significant effect on biochemical or haematological indexes whenadministered simultaneously with2.5mg aflkgÀ1diet[52]Clinoptilolite0.5Pregnant rats No effect on maternal and developmental toxicities of afl(2mg kgÀ1body weight)[53]Clinoptilolite5Quail chicks Growth inhibitory effects of2mg kgÀ1diet diminished by70%[35] Clinoptilolite 1.5Broilers Growth inhibitory effects of100ppb afldiminished over a studyperiod of42days[36]Clinoptilolite 1.5–2.5Broilers Adverse effects of2.5mg kgÀ1diet on biochemical and haematologicalprofiles were reduced[54]Zeolite NaA1Broilers Protection against growth inhibitory effects of2.5mg kgÀ1diet[37] Clinoptilolite 1.5–2.5Broilers Moderate to significant decrease of incidence and severity of certaintarget-organs degenerative changes induced by2.5mg aflkgÀ1diet[55] Clinoptilolite2Laying hens Significant decrease in liver mycotoxin concentration and liver weightduring aflatoxicosis caused by2.5mg kgÀ1diet[56]D.Papaioannou et al./Microporous and Mesoporous Materials84(2005)161–170163cell-membrane receptors[77].Furthermore,the adsorp-tion capacity of clinoptilolite and mordenite has been proved to be higher than94%for virions of bovine rota-virus and coronavirus,although infectivity level of zeolite–virus complex seems to remain unchanged[78]. Interactions among virions and the outer surface of adsorbent particles have been proposed,since the former have dimensions considerably larger(60–80nm and 60–220nm for rota-and coronavirus particles,respec-tively)than the entry channels of the aforementioned zeolites.In a more recent study of Rodrigues-Fuentes et al.[68],dealing with the development and the properties of an anti-diarrhoeic drug for humans based on clinop-tilolite,zeolite had no effect on rate of passage of inges-ta,neither acted as a water adsorbent.Instead,they proposed that the anti-diarrhoeic effect of clinoptilolite is due to the adsorption of(i)bile acids,‘‘one of the endogenic causes of diarrhoea’’,(ii)aflatoxin B1,‘‘a mycotoxin that produces severe toxicity in animals and humans’’and(iii)glucose,‘‘whose high content in intes-tinalfluid acts as an irritant factor and whose transport through the intestinal cells is reversed during diarrhoea’’.Concerning the newborn animals,the administration of zeolites appears to reduce the incidence of diarrhoea through the enhancement of passive immunity,as they increase the net absorption of colostrum immunoglobu-lins in calves[71,79,80]and pigs[81].Intestinal hypersensitivity to feed antigens or the mal-absorption syndrome,induced by a low enzyme activity, can both predispose to post-weaning infectious enteritis in pigs.According to Papaioannou et al.[13],clinoptil-olite has the ability to adsorb dietary substances,which may result in intestinal hypersensitivity phenomena[82], or to support the maintenance and even the restoration of the digestive enzyme activity in newly weaned piglets. This should also be evaluated in future studies as an additional explanation for clinoptilolitesÕminimising ef-fect on diarrhoea syndrome.4.Prevention of metabolic diseases in dairy cowsMilk fever and ketosis are of the most common metabolic diseases in high producing dairy cows.In the recent years,a number of experiments have been con-ducted in order to control these diseases using zeolites as feed additives.The results of these experiments are very promising but further investigation is required to define the exact mechanisms of zeolitesÕaction.k feverInitially,a series of experiments has been conducted in order to study the potential use of synthetic zeolite A for the prevention of milk fever in dairy cows.The objective of these experiments was to reduce the bio-availability of dietary Ca in the gastrointestinal tract by the administration of synthetic zeolite A,based on the evidence that one of the best ways to prevent milk fever is to feed cows with low calcium diets during the dry period[83–87].The results obtained were satisfac-tory as the administration of synthetic zeolite A,either as an oral drench or supplemented to the total mixed ra-tion,during the dry period reduced the bioavailability of dietary Ca and efficiently protected against milk fever, by stimulating Ca-homeostatic mechanisms prior to par-turition[88–93].Furthermore,Thilsing-Hansen et al.[92]proposed that the best ratio zeolite/Ca for the pre-vention of milk fever was10–20and that zeolite had the same efficiency either administrated for the last4 or2weeks of the dry period.More recently,Katsoulos et al.[94]showed that clin-optilolite was effective in the prevention of milk fever as well.The incidence of milk fever was significantly lower in cows that were receiving a concentrate supplemented with clinoptilolite at the level of2.5%(5.9%)during the last month of the dry period and the onset of lactation compared to the animals in the control group(38.9%), which were not receiving clinoptilolite,whereas was not significantly different than those that were receiving 1.25%clinoptilolite(17.6%)with the concentrates at the same period.The authors suggested that clinoptilolite might have had similar effect with zeolite A in activating Ca homeostatic mechanisms prior to parturition.As a consequence,the animals receiving2.5%clinoptilolite responded faster and more efficiently in the drop of serum Ca observed at the day of calving and did not show any clinical signs of milk fever the following days. However,the exact mechanism for this positive effect of clinoptilolite is currently unknown and should be fur-ther investigated.4.2.KetosisThe best strategy to prevent ketosis in dairy cows is to improve the energy uptake both in the dry period and the onset of lactation[95].According to Katsoulos et al.[23],the use of clinoptilolite has been shown to be effective in improving the energy balance at this critical period as they observed that feeding dairy cows on a diet supplemented with clinoptilolite at the level of2.5%of the concentrate feed,resulted in significantly lower incidence of ketosis(5.9%)during thefirst month after parturition,compared to the control group(38.9%) and the group of the animals receiving a concentrate supplemented with1.25%clinoptilolite(35.3%).These researchers suggested that clinoptilolite improved the energy status of the cows,either via prepartum enhance-ment of propionate production in rumen or through the improvement of the post-ruminal digestion of starch.164 D.Papaioannou et al./Microporous and Mesoporous Materials84(2005)161–1705.Protective role in intoxications and poisonings5.1.Ammonia toxicityWhite and Ohlrogge[96]first stated that ammonium ions formed by the enzyme decomposition of non-pro-tein nitrogen were immediately ion exchanged into the zeolite structure and held there for several hours until released by the regenerative action of Na+,entering the rumen in saliva during the after-feeding fermenta-tion period.From both in vitro and in vivo experimentsthey found that up to15%of the NHþ4in the rumencould be taken up by the zeolite.These observations were the causation for the conduction of many experi-ments in order to determine the influence of zeoliteson rumen NHþ4concentration and their potential usefor the counteraction of the toxic effects of urea inclu-sion in ruminantsÕrations.Hemken et al.[97]showed that supplementation of 6%clinoptilolite,in the ration of dairy cows containing urea,significantly reduced rumen NH3concentration. The same trend was observed by the dietary addition of5%clinoptilolite in steers[98]and lambs[99].Fur-thermore,clinoptilolite was effective in reducing rumen ammonia concentration even when no urea was present in the ration of steers receiving a high concentrate diet, and that this reduction was linearly associated to the percentage of clinoptilolite inclusion[100].Nestorov [101]referred that simultaneous administration of clin-optilolite and urea in sheep protects rumenflora from toxic effects of ammonia by inhibiting the reduction of microbiota population.In contrast to the former observations,Bergero et al.[102]and Bosi et al.[103]found that daily administration of250g or200g of clinoptilolite, respectively,in dairy cows did not affect rumen NHþ4 concentration.The same result had the dietary inclu-sion of2%synthetic zeolite A in dairy cows ration [104]and5%clinoptilolite in steers receiving a high roughage diet[98].The binding of NHþ4to zeolites has been noted in pigsas well,and many researchers suggested this action as the possible mechanism for the observed improved per-formance of the animals receiving zeolites.There are evi-dences that clinoptilolite elevates nitrogen excretion in feces[8,105]and reduces the ammonia concentration in blood serum[8,10,106],when supplemented to the basal diets of pigs.Furthermore,Pond et al.[10]and Yannakopoulos et al.[12]found that clinoptilolite reduced the weight of the organs involved in the metab-olism of ammonia(liver and kidneys),as the conse-quence of the reduced ammonia concentration in the gastrointestinal tract.Such observations result fromthe direct binding of NHþ4to zeolites,as clinoptilolitehas no adverse effect on the ureolytic bacteria of the large intestine and urease activity[107]anophosphate poisoningThe dietary use of clinoptilolite appears to be effective in the prevention of organophosphates poisoning. Experiments in sheep have shown that the oral adminis-tration of clinoptilolite at the dose of2g/kg of body weight,earlier or simultaneously with an organophos-phate(VX),partially protects from poisoning by inhib-iting the decrease in cholinesterase activity[108]and by protecting rumenflora[109].The protective effect of clinoptilolite on cholinesterase activity has been ob-served in mice receiving higher doses of organophos-phates as well[110,111].5.3.Heavy metal toxicity and adsorption of radioactive elementsZeolites,due to their high ion-exchange capacity, have been used effectively for the prevention of heavy metal toxicity in animals.Pond et al.[112]found that clinoptilolite protects growing mice from lead(Pb)tox-icity when added to their ration in such quantities that the ratio clinoptilolite/Pb to be10/1.According to Pond et al.[113],similar protection is provided in swine as well.The selectivity of clinoptilolite for cadmium(Cd) and Pb has been studied in vitro in order to be investi-gated whether its use reduces the levels of these elements in rumen and abomasalfluid.The experiments showed that clinoptilolite bent the91%of Pb and the99%of Cd in rumenfluid within24h,and in the abomasalfluid the94%of Pb within less than1h[114].The toxic effects of long-term ingestion of Cd(100ppm CdCl2)on female rats and their progeny were not diminished by the simul-taneous feeding of a clinoptilolite-rich tuffat5%in the diet[115].Adversely,the efficacy of clinoptilolite against Cd toxicity has been proved in pigs by the same authors who observed that3%clinoptilolite supplementation prevented the cadmium-induced iron deficient anemia in growing swine that were receiving150ppm CdCl2 [116].The results of these experiments suggest the feasi-bility of using zeolites and mainly clinoptilolite as a feed additive in the prevention of certain types of heavy metal intoxications in farm animals or in aquatic biolog-ical systems,as is the case in the study of Jain[117], where is ascertained the capacity of zeolite to enhance the removal of Pb from water,thus decreasing its avail-ability to the teleostfish Heteropneustes fossilis.Apart from heavy metals,zeolites can also bind radioactive elements,thus being suggested as a means of altering their uptake and excretion from the body. Zeolitic matrix exchanges radio-nuclides in the gastroin-testinal tract and is excreted by normal processes,there-by eliminating radioactive elementsÕassimilation into the body.Arnek and Forsberg[118]proved the selectiv-ity of some natural zeolites such as clinoptilolite, chabazite and modernite for cesium and GomonajD.Papaioannou et al./Microporous and Mesoporous Materials84(2005)161–170165et al.[119]the selectivity of clinoptilolite for strodium and zirconium.Phillippo et al.[120]showed that the dietary use of clinoptilolite may constitute a simple and cost-effective method for minimizing the adsorption of radioactive cesium by sheep grazing contaminated pastures,although there might be no effect on cesium already been built-up in the body due to a previous exposure.Furthermore,Forsberg et al.[121]observed that the administration of mordenite in sheep and goats increased the excretion of cesium with feces and reduced its accumulation in tissues.On the other hand,Rachu-bik and Kowalski[122]demonstrated that synthetic zeolite-enriched diets exerted an inconsistent pattern of radiostrontium assimilation in the bone tissue and liver or kidneys of rats intragastrically dosed with an aqueous solution of90SrCl2.5.4.Copper toxicityIvan et al.[123]observed that the inclusion of ben-tonite,a phyllosilicate,in the ration of sheep at the rate of0.5%significantly reduced the Cu concentration in liver and suggested the use of this material in order to prevent copper poisoning.In contrast,clinoptilolite does not seem to be effective,as Pond[124]found that the addition of2%clinoptilolite to the basal diet of sheep containing10or20ppm Cu did not protect against the toxic signs of Cu and increased the mortality in lambs fed the diet with20ppm Cu.A lack of any ef-fect on liver Cu accumulation was also found in growing pigs which were on diets supplemented with0.5%syn-thetic zeolite A and250ppm Cu[125].Clinoptilolite was expected to exchange Cu in the lumen of the intes-tine,thereby decreasing the toxicity of excess Cu for sheep,whose tolerance for Cu is low compared with that of other food animals.However,such action was not observed probably due to a shift in ion-exchange relativeto Cu and NHþ4or to some other complex interaction,which resulted in a net increase in Cu available for absorption from the intestinal tract[124].The optimum ratio of clinoptilolite to Cu in the diet for reducing the intestinal absorption of the latter has not been deter-mined,but such information,according to Pond[126], is needed in order to establish appropriate levels of die-tary clinoptilolite supplementation.6.Impact on parasite infectionsConsidering the potential efficacy of zeolites against parasite infections,the results of the experimentsfirst conducted in rats were encouraging for their use in other animal species as well.According to Wells and McHugh [127],the administration of clinoptilolite at the rate of 10%of a conventional diet facilitated the removal of parasites from the intestinal lumen of rats infected with the nematode Nippostrongylus brasiliensis.Furthermore, Wells and Kilduff[128]observed a more accelerated intestinal a-D-glucosidase and aminopeptidase activity restitution in rats fed a commercial diet supplemented with clinoptilolite(5%)and recovering from N.brasilien-sis infection.Confirming the observations in rats,Deli-giannis et al.[129]recently proved the efficacy of clinoptilolite against parasite infections in growing lambs.They showed that feeding lambs,primarily infected with a single dose of gastrointestinal(GI) nematodes,with a concentrate mixture containing3% clinoptilolite significantly decreased their total worm burden and faecal egg counts per capita fecundity and demonstrated that clinoptilolite supplementation re-duced the establishment of GI nematodes and resulted in a good performance of the animals.Interestingly,zeolites have also been tested as anthel-mintic loaded carriers,through retarding drug release and prolonging its therapeutic action.Sustained-release mechanism implies a slow desorption of the drug mole-cules from the external surface and the internal zeolitic cavities,as they are progressively replaced by host pro-teins and water molecules,respectively,during the intes-tinal transport of the drug-zeolite compound.Promising results were obtained,atfirst,as regards tetramisole-loaded synthetic zeolite Y[130]and recently,pyrantel-and fenbendazole-loaded synthetic zeolite Y in rats infested with N.brasiliensis and dichlorvos-loaded zeo-lite Y in pigs infected with Ascaris suum[131].In the case of tetramisole and dichlorvos,anthelmintic mole-cules are small enough tofit through the entry channels of zeolite Y(windows of7.4A˚),while fenbendazole loading requires an initial partial dealumination of the zeolitic carrier and large pyrantel molecules allow only outer surface loading to occur.7.Prevention of metabolic skeletal defectsThe dietary inclusion of synthetic zeolite A(at the rates of0.75%or1.5%)in broilers which are on a diet with inadequate or marginal levels of calcium results in an increase of bone ash content along with a reduc-tion of rachitic lesions[132].Accordingly,the incorpora-tion of zeolite A in the same diets at1%exerts a clear beneficial effect in reducing the incidence of tibial dys-chondroplasia[132–134].Although tibial dyschondro-plasia is a metabolic cartilage disease which represents the endpoint of several mechanisms,the incidence is in-creased when high dietary levels of phosphorus are used [135]or when dietary calcium is lower than0.85%[136]. Similarly,the beneficial effect of zeolite A is inconsistent and largely depends on the dietary level of calcium. According to Watkins and Southern[137],the dietary use of0.75%zeolite A in broilers is accompanied by alterations in mineral absorption and tissue distribution,166 D.Papaioannou et al./Microporous and Mesoporous Materials84(2005)161–170。

2024年外研版英语初二上学期复习试题及解答参考一、听力部分（本大题有20小题，每小题1分，共20分）1、Listen to the conversation and choose the best answer to the question you hear. Question: What is the weather like today?A. SunnyB. RainyC. CloudyD. WindyAnswer: AExplanation: The woman says, “It’s a sunny day today,” which indicates that the weather is sunny.2、Listen to the dialogue and complete the following sentence with the missing word you hear.Question: The man is planning to___________this weekend.A. go to the beachB. stay at homeC. visit a friendD. go shoppingAnswer: CExplanation: The man says, “I’m planning to visit a friend this weekend,”which is the missing word in the sentence.3、You are listening to a conversation between two students in the library.A. The man is borrowing a book.B. The woman is returning a book.C. They are discussing a book they recently read.D. The man is asking for help finding a book.Answer: DExplanation: In the conversation, the man says, “Excuse me, could you help me find the book on ancient civi lizations?” This indicates that he is asking for help finding a book, making option D the correct answer.4、You are listening to a short dialogue at a bookstore.A. The woman is looking for a novel.B. The man is recommending a non-fiction book.C. The woman is asking for help with a school project.D. The man is suggesting a book for a gift.Answer: BExplanation: The woman says, “I need a book on environmental issues for my science class.” The man responds by recommending, “How about ‘The Green Planet’? It’s a great overview of environmental science.” This shows that the man is suggesting a non-fiction book, making option B the correct answer.5.You are listening to a conversation between a student and a teacher.Student: Hello, Miss White. How was your weekend?Teacher: Oh, it was quite busy. I went hiking with my friends. How about you? Student: I stayed at home and watched some movies. I watched a comedy and a horror movie. Which one did you like more?Teacher: I preferred the comedy because it was funny and relaxing.Question: What did the teacher prefer to do during the weekend?A) Watch moviesB) Go hikingC) Stay at homeD) Visit a friendAnswer: B) Go hikingExplanation: The teacher mentioned that she went hiking with her friends, so the correct answer is B) Go hiking.6.You are listening to a radio program about healthy eating habits.Host: Today, we’re discussing the importance of eating a balanced diet. Dr. Smith, can you explain why it’s important to include fruits and vegetables in our daily meals?Dr. Smith: Absolutely. Fruits and vegetables are rich in vitamins, minerals, and antioxidants. They help boost our immune system, improve digestion, and reduce the risk of chronic diseases like heart disease and cancer.Question: What are the main benefits of eating fruits and vegetables according to Dr. Smith?A) Boosting the immune system and improving digestionB) Losing weight and reducing stressC) Increasing energy levels and improving memoryD) Enhancing physical appearance and reducing the risk of chronic diseasesAnswer: A) Boosting the immune system and improving digestionExplanation: Dr. Smith explained that fruits and vegetables help boost the immune system and improve digestion, so the correct answer is A) Boosting the immune system and improving digestion.7、Listen to the conversation and choose the best answer to complete the sentence.A) They are discussing the weather.B) They are planning a trip.C) They are talking about a book.Question: What are the speakers mainly talking about?Answer: BExplanation: The conversation is about planning a trip, which is indicated by the phrases like “We should go there in the summer” and “It’s a great place to visit.”8、Listen to the dialogue and answer the question.Question: Why does the man suggest visiting the museum?A)He thinks it’s a waste of time.B)He believes it will be an educational experience.C)He doesn’t want to go anywhere else.Answer: BExplanation: The man suggests visiting the museum because he mentions that it will be “a good opportunity to learn something new,” indicating that it’s an educational experience.9、You are listening to a conversation between two friends, Tom and Lily. They are talking about their weekend plans.Tom: Hey Lily, do you have any plans for this weekend?Lily: Well, actually, I’m planning to go hiking with a group of friends. How about you, Tom?Tom: That sounds fun! I was thinking of visiting the city museum. What do you think?Lily: That’s a great idea! Maybe we can go together after your visit to the museum.Question: What is Lily planning to do this weekend?A. Visit the city museum.B. Go hiking with friends.C. Go shopping.D. Watch a movie.Answer: BExplanation: In the conversation, Lily says, “Well, actually, I’m planning to go hiking with a group of friends.” This means that she is planning to go hiking this weekend.10、You are listening to a news report about a new research study.News Anchor: According to a recent research study, scientists have discovered a new way to treat cancer. This new treatment has shown promisingresults in early trials.Interviewer: That’s amazing! Can you tell us more about this new treatment?Scientist: Sure, this new treatment involves using a combination of natural substances to target and destroy cancer cells. It’s a non-toxic approach that has fewer side effects compared to traditional treatments.Question: What is the main topic of the news report?A. A new way to treat cancer.B. The benefits of natural substances.C. The history of cancer research.D. The side effects of traditional treatments.Answer: AExplanation: The news report starts with the statement, “According to a recent research study, scientists have di scovered a new way to treat cancer.” This clearly indicates that the main topic of the report is about a new way to treat cancer.11.W: Hi, John! Are you ready for the English test this week?M: Yeah, I’ve been studying hard for it. I think I’m prepared.Q: What does John think about the English test?A: He thinks he is prepared for the test.B: He is worried about the test.C: He doesn’t think he’s ready for the test.Answer: AExplanation: John says, “I’ve been studying hard for it. I think I’m prepared,”which means he believes he is ready for the test.12.M: Hi, Lily! Have you heard about the school trip next month?W: Yes, I have. We’re going to the countryside. It’s going to be so much fun! Q: Where is the school trip going to be?A: It’s going to be i n the city.B: It’s going to be in the countryside.C: It’s going to be at the beach.Answer: BExplanation: Lily answers, “We’re going to the countryside,” which indicates that the school trip is planned for the countryside.13.Listen to the dialogue and answer the question.W: Hi, John. How was your vacation in Beijing?M: It was great! I visited the Forbidden City and the Summer Palace. The scenery was beautiful, and the people were friendly.Question: What did John visit in Beijing?A) The Great WallB) The Forbidden City and the Summer PalaceC) Tiananmen SquareD) The Beijing ZooAnswer: B) The Forbidden City and the Summer PalaceExplanation: The question asks about the places John visited in Beijing.According to the dialogue, John visited the Forbidden City and the Summer Palace, so the correct answer is B) The Forbidden City and the Summer Palace.14.Listen to the passage and answer the question.The moon is Earth’s only natural satellite. It is about 384,400 kilometers away from Earth. The moon is about one-quarter the size of Earth and it takes about 27 days to complete one orbit around Earth.Question: How long does it take for the moon to complete one orbit around Earth?A) 24 hoursB) 27 daysC) 1 monthD) 365 daysAnswer: B) 27 daysExplanation: The question asks about the time it takes for the moon to complete one orbit around Earth. According to the passage, the moon takes about 27 days to complete one orbit around Earth, so the correct answer is B) 27 days.15.W: Hi, John. How was your science project?M: It was quite challenging, but I learned a lot about renewable energy sources.Q: What did John learn about in his science project?A: Renewable energy sources.B: Chemistry.C: Biology.D: Physics.Answer: AExplanation: The question asks what John learned about in his science project. In the dialogue, John mentions that he learned a lot about renewable energy sources, so the correct answer is A.16.M: Have you seen the new movie “Inception”? I heard it’s really amazing. W: Yes, I saw it last weekend. The story is so intriguing that I couldn’t stop thinking about it even after the movie ended.Q: What did the woman think about the movie “Inception”?A: It was boring.B. It was a waste of time.C. It was intriguing.D. It was predictable.Answer: CExplanation: The question asks what the woman thought about the movie “Inception”. In the dialogue, the woman says the story is so intriguing that she couldn’t stop thinking about it, which means she found it interesting and captivating. Therefore, the correct answer is C.17.You hear a conversation between two students, Alex and Sarah, about their weekend plans.A. Alex is going to visit his grandparents in the country.B. Sarah is planning to go hiking in the mountains.C. Both Alex and Sarah are going to a music festival.Answer: BExplanation: The conversation indicates that Sarah is excited about her hiking trip in the mountains, making option B the correct answer. Alex mentions that he will stay in town, implying that he has other plans.18.You hear a news report about a new eco-friendly initiative in your city.A. The city is implementing a new recycling program.B. The government is offering tax incentives for electric vehicle purchases.C. Local businesses are required to use solar energy.Answer: BExplanation: The news report specifically mentions the government’s tax incentives for electric vehicle purchases, which aligns with option B. The report does not mention a recycling program or the requirement for solar energy use, making options A and C incorrect.19.You are listening to a conversation between two students in a library.Student A: Hey, have you seen the new science book we need for our project? Student B: __________.A. Yes, i t’s right over there on the shelf.B. No, I haven’t, but I saw it on the list.C. I’ve read it, but I don’t think it’s available now.D. It’s not on the list, but I can help you find it.Answer: BExplanation: Student B responds that they haven’t seen the book but saw it on the list, indicating they are aware of the book but haven’t physically seen it in the library. The correct answer is B.20.You are listening to a radio announcement about a local event.Announcer: __________.A. The city park will host a free concert this weekend starting at 6 PM.B. All libraries will be closed next Monday for a staff training day.C. The local museum is offering free entry to students this month.D. The school sports day has been postponed due to the weather.Answer: AExplanation: The radio announcement is about a free concert happening at the city park this weekend. The correct answer is A. The other options refer to different events or announcements.二、阅读理解（30分）Reading ComprehensionPassage:In the small town of Willow Creek, there was a local library that had been a cornerstone of the community for over a century. The library was known for its quaint charm and the friendly atmosphere that made every visitor feel welcome. One of the most beloved features of the library was its old, wooden reading room where people could sit and enjoy a good book in peace.One sunny afternoon, a young girl named Emily entered the library for the first time. She was immediately drawn to the reading room, where she noticed an elderly woman sitting at a table, surrounded by stacks of books. Emily approached the woman, who was named Mrs. Thompson, and struck up a conversation.“Good afternoon, Mrs.Thompson,” Emily said with a smile. “I’ve never been in this room before. It’s so peaceful here.”Mrs. Thompson smiled warmly. “Yes, it is. This room has seen many generations of people come and go. I’ve been coming here since I was a child.”Emily was curious. “Do you have a favorite book from this room?”Mrs. Thompson paused for a moment, then re plied, “Oh, yes. It’s a book called ‘The Timeless Garden.’ It’s a story about a young girl who discovers a magical garden hidden behind her house. The book has taught me so much about life and friendship.”As Emily listened, she felt a sense of wonder. She knew she had to find this book and read it herself. She promised Mrs. Thompson she would return soon to discuss the story with her.Questions:1.What is the main feature of the reading room in the library?A. It has modern technology.B. It is surrounded by books.C. It is very quiet and peaceful.D. It is filled with children’s books.2.Who is the young girl that enters the library for the first time?A. Mrs. ThompsonB. The librarianC. EmilyD. The author3.What is the title of the book that Mrs. Thompson mentioned?A. ‘The Magical Library’B. ‘The Timeless Garden’C. ‘The Library’s Secret’D. ‘Emily’s Adventure’Answers:1.C2.C3.B三、完型填空（15分）Title: A Day in the Life of a TreeLast weekend, I went on a nature walk with my friends. It was a beautiful day, and we decided to go to the nearby forest to observe the plants and animals. While we were walking, one of our friends suggested that we should spend some time observing a single tree to understand how it lives through a day.The tree we chose was a big oak, its branches reaching out like open arms welcoming us. As we sat down at the base of the tree, we noticed that the leaves were rustling softly in the wind. The sun was shining brightly, and we could see how the tree was enjoying the warmth, as if it were drinking up the sunlight with every 1.After a while, we noticed tiny insects crawling up and down the trunk of the tree. They seemed to be collecting sap, which is the tree’s way of providing food for itself and its inhabitants. We realized that the tree is not just standing still; it’s very much alive and 2.As the day progressed, clouds started to gather in the sky, and soon it began to rain lightly. The raindrops fell gently onto the leaves and trickled down to the ground, soaking into the soil. This water would be absorbed by the roots and transported to all parts of the tree, helping it grow stronger and taller. The tree appeared to be drinking the rainwater greedily, as though it were 3 after a long period of drought.By late afternoon, the rain had stopped, and the sun came out again. The leaves glistened with water droplets that sparkled like little diamonds. Birds started to sing their evening songs from the branches, and the air was filled with a sense of peace and calm. Our friend remarked that just like the tree needs water and sunlight to live, we too need nourishment and warmth to grow and thrive. The tree serves as a reminder of the 4cycle of life and the importance of being connected to nature.As we got up to leave, we felt a deep sense of gratitude towards the tree for teaching us so much about itself and life in general. We left the forest feeling more connected to the natural world than ever before. The experience made us realize that even something seemingly static and silent as a tree hasa 5 story to tell.1.__________(A. leaf B. branch C. pore D. root)2.__________(A. dormant B. thriving C. stationary D. sleeping)3.__________(A. blooming B. wilting C. thirsting D. blossoming)4.__________(A. constant B. unchanging C. continuous D. ceaseless)5.__________(A. silent B. vivid C. motionless D. tranquil)Key:1.C. pore2.B. thriving3.C. thirsting4.C. continuous5.B. vividThis exercise aims to test the student s’ vocabulary knowledge, reading comprehension skills, and their ability to deduce contextually appropriate words based on the overall meaning of the passage.四、语法填空题（本大题有10小题，每小题1分，共10分）1、The students were asked to write a short story about their summervacation,_____________they had just experienced.A. whichB. whereC. whenD. what答案：C解析：此题考查定语从句的关系词。

ReviewRemoval of heavy metal ions from wastewater by chemicallymodified plant wastes as adsorbents:A reviewW.S.Wan Ngah *,M.A.K.M.HanafiahSchool of Chemical Sciences,Universiti Sains Malaysia,11800Penang,Malaysia Received 3April 2007;received in revised form 18June 2007;accepted 18June 2007Available online 27July 2007AbstractThe application of low-cost adsorbents obtained from plant wastes as a replacement for costly conventional methods of removing heavy metal ions from wastewater has been reviewed.It is well known that cellulosic waste materials can be obtained and employed as cheap adsorbents and their performance to remove heavy metal ions can be affected upon chemical treatment.In general,chemically modified plant wastes exhibit higher adsorption capacities than unmodified forms.Numerous chemicals have been used for modifications which include mineral and organic acids,bases,oxidizing agent,organic compounds,etc.In this review,an extensive list of plant wastes as adsorbents including rice husks,spent grain,sawdust,sugarcane bagasse,fruit wastes,weeds and others has been compiled.Some of the treated adsorbents show good adsorption capacities for Cd,Cu,Pb,Zn and Ni.Ó2007Elsevier Ltd.All rights reserved.Keywords:Adsorption;Plant wastes;Low-cost adsorbents;Heavy metals;Wastewater treatment1.IntroductionHeavy metals have been excessively released into the environment due to rapid industrialization and have cre-ated a major global concern.Cadmium,zinc,copper,nickel,lead,mercury and chromium are often detected in industrial wastewaters,which originate from metal plating,mining activities,smelting,battery manufacture,tanneries,petroleum refining,paint manufacture,pesticides,pigment manufacture,printing and photographic industries,etc.,(Kadirvelu et al.,2001a;Williams et al.,1998).Unlike organic wastes,heavy metals are non-biodegradable and they can be accumulated in living tissues,causing various diseases and disorders;therefore they must be removed before discharge.Research interest into the production of cheaper adsorbents to replace costly wastewater treatment methods such as chemical precipitation,ion-exchange,elec-troflotation,membrane separation,reverse osmosis,elec-trodialysis,solvent extraction,etc.(Namasivayam andRanganathan,1995)are attracting attention of scientists.Adsorption is one the physico-chemical treatment pro-cesses found to be effective in removing heavy metals from aqueous solutions.According to Bailey et al.(1999),an adsorbent can be considered as cheap or low-cost if it is abundant in nature,requires little processing and is a by-product of waste material from waste industry.Plant wastes are inexpensive as they have no or very low eco-nomic value.Most of the adsorption studies have been focused on untreated plant wastes such as papaya wood (Saeed et al.,2005),maize leaf (Babarinde et al.,2006),teak leaf powder (King et al.,2006),lalang (Imperata cylindrica )leaf powder (Hanafiah et al.,2007),rubber (Hevea brasili-ensis )leaf powder (Hanafiah et al.,2006b,c ),Coriandrum sativum (Karunasagar et al.,2005),peanut hull pellets (Johnson et al.,2002),sago waste (Quek et al.,1998),salt-bush (Atriplex canescens )leaves (Sawalha et al.,2007a,b ),tree fern (Ho and Wang,2004;Ho et al.,2004;Ho,2003),rice husk ash and neem bark (Bhattacharya et al.,2006),grape stalk wastes (Villaescusa et al.,2004),etc.Some of the advantages of using plant wastes for wastewa-ter treatment include simple technique,requires little pro-0960-8524/$-see front matter Ó2007Elsevier Ltd.All rights reserved.doi:10.1016/j.biortech.2007.06.011*Corresponding author.Tel.:+6046533888;fax:+6046574854.E-mail address:wsaime@usm.my (W.S.Wan Ngah).Available online at Bioresource Technology 99(2008)3935–3948cessing,good adsorption capacity,selective adsorption of heavy metal ions,low cost,free availability and easy regen-eration.However,the application of untreated plant wastes as adsorbents can also bring several problems such as low adsorption capacity,high chemical oxygen demand(COD) and biological chemical demand(BOD)as well as total organic carbon(TOC)due to release of soluble organic compounds contained in the plant materials(Gaballah et al.,1997;Nakajima and Sakaguchi,1990).The increase of the COD,BOD and TOC can cause depletion of oxygen content in water and can threaten the aquatic life.There-fore,plant wastes need to be modified or treated before being applied for the decontamination of heavy metals. In this review,an extensive list of adsorbents obtained from plant wastes has been compiled and their methods of mod-ification were discussed.A comparison of adsorption effi-ciency between chemically modified and unmodified adsorbents was also reported.2.Chemically modified plant wastesPretreatment of plant wastes can extract soluble organic compounds and enhance chelating efficiency(Gaballah et al.,1997).Pretreatment methods using different kinds of modifying agents such as base solutions(sodium hydroxide,calcium hydroxide,sodium carbonate)mineral and organic acid solutions(hydrochloric acid,nitric acid, sulfuric acid,tartaric acid,citric acid,thioglycollic acid), organic compounds(ethylenediamine,formaldehyde,epi-chlorohydrin,methanol),oxidizing agent(hydrogen perox-ide),dye(Reactive Orange13),etc.for the purpose of removing soluble organic compounds,eliminating colour-ation of the aqueous solutions and increasing efficiency of metal adsorption have been performed by many research-ers(Hanafiah et al.,2006a;Reddy et al.,1997;Taty-Cos-todes et al.,2003;Gupta et al.,2003;Namasivayam and Kadirvelu,1997;Sˇc´iban et al.,2006a;Min et al.,2004; Kumar and Bandyopadhyay,2006;Baral et al.,2006;Acar and Eren,2006;Rehman et al.,2006;Abia et al.,2006; Shukla and Pai,2005a,Low et al.,1995;Azab and Peter-son,1989;Lazlo,1987;Wankasi et al.,2006).The types of chemicals used for modifying plant wastes and their maximum adsorption capacities are shown in Table1. 2.1.Rice husks/rice hullsRice husk consists of cellulose(32.24%),hemicellulose (21.34%),lignin(21.44%)and mineral ash(15.05%)(Rah-man et al.,1997)as well as high percentage of silica in its mineral ash,which is approximately96.34%(Rahman and Ismail,1993).Rice husk is insoluble in water,has good chemical stability,has high mechanical strength and pos-sesses a granular structure,making it a good adsorbent material for treating heavy metals from wastewater.The removal of heavy metals by rice husk has been extensively reviewed by Chuah et al.(2005).Among the heavy metal ions studied include Cd,Pb,Zn,Cu,Co,Ni and Au.Rice husk can be used to treat heavy metals in the form of either untreated or modified using different modification methods.Hydrochloric acid(Kumar and Bandyopadhyay, 2006),sodium hydroxide(Guo et al.,2003;Kumar and Bandyopadhyay,2006),sodium carbonate(Kumar and Bandyopadhyay,2006),epichlorohydrin(Kumar and Ban-dyopadhyay,2006),and tartaric acid(Wong et al.,2003a; Wong et al.,2003b)are commonly used in the chemical treatment of rice husk.Pretreatment of rice husks can remove lignin,hemicellulose,reduce cellulose crystallinity and increase the porosity or surface area.In general,chem-ically modified or treated rice husk exhibited higher adsorption capacities on heavy metal ions than unmodified rice husk.For example,Kumar and Bandyopadhyay (2006)reported that rice husk treated with sodium hydrox-ide,sodium carbonate and epichlorohydrin enhanced the adsorption capacity of cadmium.The base treatment using NaOH for instance appeared to remove base soluble mate-rials on the rice husk surface that might interfere with its adsorption property.Tarley et al.(2004)found that adsorption of Cd increase by almost double when rice husk was treated with NaOH.The reported adsorption capaci-ties of Cd were7and4mg gÀ1for NaOH treated and unmodified rice husk,respectively.Meanwhile,most of the acids used for treatment of plant wastes were in dilute form such as sulfuric acid, hydrochloric acid and nitric acid.According to Esteghla-lian et al.(1997),dilute acid pretreatment using sulfuric acid can achieve high reaction rates and improve cellulose hydrolysis.Concentrated acids are powerful agents for cel-lulose hydrolysis but they are toxic,corrosive and must be recovered(Sivers and Zacchi,1995).However,in some cases,hydrochloric acid treated rice husk showed lower adsorption capacity of cadmium than the untreated rice husk(Kumar and Bandyopadhyay,2006).When rice husk is treated with hydrochloric acid,adsorption sites on the surface of rice husk will be protonated,leaving the heavy metal ions in the aqueous phase rather than being adsorbed on the adsorbent surface.Wong et al.(2003a)carried out an adsorption study of copper and lead on modified rice husk by various kinds of carboxylic acids(citric acid,sali-cylic acid,tartaric acid,oxalic acid,mandelic acid,malic and nitrilotriacetic acid)and it was reported that the high-est adsorption capacity was achieved by tartaric acid mod-ified rice husk.Esterified tartaric acid modified rice husk however significantly reduced the uptake of Cu and Pb. The maximum adsorption capacities for Pb and Cu were reported as108and29mg gÀ1,respectively.Effect of che-lators on the uptake of Pb by tartaric acid modified rice husk was also studied.It was reported that higher molar ratios of chelators such as nitrilotriacetic acid(NTA)and ethylenediamine tetraacetic acid(EDTA)caused significant suppressing effect on the uptake of Pb.Dyestufftreated rice hulls using Procion red and Procion yellow for the removal of Cr(VI),Ni(II),Cu(II),Zn(II),Cd(II),Hg(II)and Pb(II) were studied by Suemitsu et al.(1986).More than80%of3936W.S.Wan Ngah,M.A.K.M.Hanafiah/Bioresource Technology99(2008)3935–3948W.S.Wan Ngah,M.A.K.M.Hanafiah/Bioresource Technology99(2008)3935–39483937 Table1Summary of modified plant wastes as adsorbents for the removal of heavy metal ions from aqueous solutionAdsorbent Modifying agent(s)Heavy metal Q max(mg gÀ1)SourceRice husk Water washed Cd(II)8.58Kumar and Bandyopadhyay(2006) Sodium hydroxide20.24Sodium bicarbonate16.18Epichlorohydrin11.12Rice husk Tartaric acid Cu(II)31.85Wong et al.(2003b)Pb(II)120.48Sawdust(cedrus deodar wood)Sodium hydroxide Cd(II)73.62Memon et al.(2007)Sawdust(S.robusta)Formaldehyde Cr(VI) 3.6Baral et al.(2006)Sawdust(Poplar tree)Sulfuric acid Cu(II)13.95Acar and Eren(2006)Sawdust(Dalbergia sissoo)Sodium hydroxide Ni(II)10.47Rehman et al.(2006)Sawdust(Poplar tree)Sodium hydroxide Cu(II) 6.92Sˇc´iban et al.(2006a)Zn(II)15.8Sawdust(Fir tree)Cu(II)12.7Zn(II)13.4Sawdust(Oak tree)Hydrochloric acid Cu(II) 3.60Argun et al.(2007)Ni(II) 3.37Cr(VI) 1.74Sawdust(Pinus sylvestris)Formaldehyde in Sulfuric acid Pb(II)9.78Taty-Costodes et al.(2003)Cd(II)9.29Walnut sawdust Formaldehyde in sulfuric acid Cd(II) 4.51Bulut and Tez(2003)Ni(II) 6.43Pb(II) 4.48Sawdust Reactive Orange13Cu(II)8.07Shukla and Pai(2005b)Ni(II)9.87Zn(II)17.09Peanut husk Sulfuric acid Pb(II)29.14Li et al.(2006a)Cr(III)7.67Cu(II)10.15Cr(VI)11.4Dubey and Gopal(2006) Groundnut husk Sulfuric acid followed by silverimpregnationCassava waste Thioglycollic acid Cd(II)NA Abia et al.(2006)Cassava tuber bark waste Thioglycollic acid Cd(II)26.3Horsfall Jr.et al.(2006)Cu(II)90.9Zn(II)83.3Wheat bran Sulfuric acid Cu(II)51.5O¨zer et al.(2004)Wheat bran Sulfuric acid Cd(II)101O¨zer and Pirinc¸c¸i(2006)Juniperfibre Sodium hydroxide Cd(II)29.54Min et al.(2004)Indian barks Hydrochloric acid Cu(II)Reddy et al.(1997)–sal51.4–mango42.6–jackfruit17.4Jutefibres Reactive Orange13Cu(II)8.40Shukla and Pai(2005a)Ni(II) 5.26Zn(II) 5.95Hydrogen peroxide Cu(II)7.73Ni(II) 5.57Zn(II)8.02Unmodified Cu(II) 4.23Ni(II) 3.37Zn(II) 3.55Banana pith Nitric acid Cu(II)13.46Low et al.(1995)Banana stem Formaldehyde Pb(II)91.74Noeline et al.(2005)Spent grain Hydrochloric acid Cd(II)17.3Low et al.(2000)Sodium hydroxide Pb(II)35.5(continued on next page)Cd(II),Pb(II)and Hg(II)ions were able to be removed by the two types of treated adsorbents,while Cr(VI)recorded the lowest percentage removal(<40%).2.2.Spent grainSpent grain obtained from brewery can be used to treat Pb(II)and Cd(II)ions as demonstrated by Low et al.,2000.Treatment of spent grain with NaOH greatly enhanced adsorption of Cd(II)and Pb(II)ions,whereas HCl treated spent grain showed lower adsorption than the untreated spent grain.The increase in adsorption of heavy metal ions after base treatment could be explained by the increase in the amount of galactouronic acid groups after hydrolysis of O-methyl ester groups.The best pH range for metal adsorption was4–6.Kinetic study reveals that the equilib-Table1(continued)Adsorbent Modifying agent(s)Heavy metal Q max(mg gÀ1)SourceCork powder Calcium chloride Cu(II)15.6Chubar et al.(2004)Sodium chloride19.5Sodium hydroxide18.8Sodium hypochlorite18.0Sodium iodate19.0Corncorb Nitric acid Cd(II)19.3Leyva-Ramos et al.(2005)Citric acid55.2Imperata cylindrica leaf powder Sodium hydroxide Pb(II)13.50Hanafiah et al.(2006a) Alfalfa biomass Sodium hydroxide Pb(II)89.2Tiemann et al.(2002)Azollafiliculoides (aquatic fern)Hydrogen peroxide–MagnesiumchloridePb(II)228Ganji et al.(2005)Cd(II)86Cu(II)62Zn(II)48Carrot residues Hydrochloric acid Cr(III)45.09Nasernejad et al.(2005)Cu(II)32.74Zn(II)29.61Sugarcane bagasse Sodium bicarbonate Cu(II)114Junior et al.(2006)Pb(II)196Cd(II)189Ethylenediamine Cu(II)139Pb(II)164Cd(II)189Triethylenetetramine Cu(II)133Pb(II)313Cd(II)313Sugarbeet pulp Hydrochloric acid Cu(II)0.15Pehlivan et al.(2006)Zn(II)0.18Bagassefly ash Hydrogen peroxide Pb(II) 2.50Gupta and Ali(2004)Cr(III) 4.35Nipah palm shoot biomass Mercaptoacetic acid Pb(II)52.86Wankasi et al.(2006)Cu(II)66.71Groundnut shells Reactive Orange13Cu(II)7.60Shukla and Pai(2005b)Ni(II)7.49Zn(II)9.57Terminalia arjuna nuts ZnCl2Cr(VI)28.43Mohanty et al.(2005)Coirpith ZnCl2Cr(VI)NA Namasivayam and Sangeetha(2006)Ni(II)Hg(II)Cd(II)Kula et al.(2007)Sulfuric acid and ammonium persulphate Hg(II)154Namasivayam and Kadirvelu(1999) Cu(II)39.7Namasivayam and Kadirvelu(1997) Hg(II)NA Kadirvelu et al.(2001a)Pb(II)Cd(II)Ni(II)Cu(II)Ni(II)62.5Kadirvelu et al.(2001b)NA–not available.3938W.S.Wan Ngah,M.A.K.M.Hanafiah/Bioresource Technology99(2008)3935–3948rium time of adsorption was120min for both metal ions and adsorption followed pseudo-second-order model.The maximum adsorption capacity for lead was two times higher than cadmium.The effect of organic ligands (EDTA,nitrilotriacetic acid and salicylic acid)on adsorp-tion efficiency was assessed and adsorption was greatly reduced by EDTA and nitrilotriacetic acid at molar ratio of1:1(metal:ligand).EDTA and nitrilotriacetic acid could chelate the heavy metal ions,therefore more metal ions would remain in the solutions rather than being adsorbed (Jeon and Park,2005).Salicylic acid on the other hand slightly reduced the percentage of cadmium adsorption but did not affect adsorption of lead.2.3.Sugarcane bagasse/fly ashJunior et al.(2006)reported the use of succinic anhy-dride modified sugarcane bagasse for treatment of Cu, Cd and Pb from aqueous solutions.Sugarcane bagasse consists of cellulose(50%),polyoses(27%)and lignin (23%).The presence of these three biological polymers causes sugarcane bagasse rich in hydroxyl and phenolic groups and these groups can be modified chemically to pro-duce adsorbent materials with new properties.The authors reported that the hydroxyl groups in sugarcane bagasse could be converted to carboxylic groups by using succinic anhydride.The carboxylic groups were later reacted with three different chemicals mainly NaHCO3,ethylenediamine and triethylenetetramine to produce new properties of adsorbent materials which showed different adsorption capacities for metal ions.It was found that sugarcane bagasse treated with ethylenediamine and triethylenetetra-mine shows a remarkable increase in nitrogen content com-pared to untreated sample,and triethylenetetramine modified sugarcane bagasse has a higher increasing extent. The presence of amide group was also detected in ethylene-diamine and triethylenetetramine modified sugarcane bag-asses as a result of the reaction between–COOH and–NH2groups.Kinetic studies showed that equilibrium time for adsorption of Cu,Cd and Pb onto tethylenediamine and triethylenetetramine modified sugarcane bagasses were slower than that for adsorbent modified with NaHCO3. Triethylenetetramine modified sugarcane bagasse was the best adsorbent material for removal of Cd and Pb since the adsorption capacities for both metals are two times higher than unmodified sugarcane bagasse.This was prob-ably caused by the higher number of nucleophilic sites introduced in triethylenetetramine modified sugarcane bagasse.When sugarcane bagasse was modified with meth-anol,however,the resulting adsorbent did not show a good uptake of cadmium as the maximum adsorption capacity was6.79mg gÀ1(Ibrahim et al.,2006).The performance of hydrogen peroxide treated bagasse fly ash,a solid waste of sugar industry for removal of lead and chromium was explored by Gupta and Ali(2004). Hydrogen peroxide is a good oxidizing agent and used to remove the adhering organic matter on the adsorbent.It was found that hydrogen peroxide treated bagassefly ash was able to remove chromium in a shorter period of time (60min)compared to lead(80min).The isotherm study also revealed maximum adsorption capacity for chromium was higher than lead.However,the recorded values of maximum adsorption capacities for both metals were low (2.50and4.35mg gÀ1for Pb and Cr,respectively).The detail mechanism of adsorption by the treated bagassefly ash was not discussed,but it was thought that adsorption was controlled byfilm diffusion at lower metal concentra-tion and particle diffusion at higher concentration of metal ions.2.4.SawdustSawdust,obtained from wood industry is an abundant by-product which is easily available in the countryside at negligible price.It contains various organic compounds (lignin,cellulose and hemicellulose)with polyphenolic groups that could bind heavy metal ions through different mechanisms.An experiment on the efficiency of sawdust in the removal of Cu2+and Zn2+ions was conducted by Sˇc´i-ban et al.(2006a).Two kinds of sawdust,poplar andfir wood were treated with NaOH(fibre-swelling agent)and Na2CO3solutions and the adsorption capacities were com-pared with the untreated sawdusts.For unmodified saw-dust,both types of woods showed higher uptakes of Cu2+ions than Zn2+ions,and adsorption followed Lang-muir isotherm model.Equivalent amounts of adsorption capacities were recorded by both types of sawdust for Zn2+and Cu2+ions,although these two adsorbents have different anatomical structure and chemical composition. After treating with NaOH,a marked increase in adsorption capacity was observed for both heavy metal ions,especially for Zn2+ions(2.5times for Cu2+and15times for Zn2+). The adsorption capacities shown by Langmuir model were 6.92mg gÀ1(poplar sawdust)and12.70mg gÀ1(fir saw-dust)for Cu2+,and15.83mg gÀ1(poplar sawdust)and 13.41mg gÀ1for Zn2+(fir sawdust),respectively.In another experiment,Sˇc´iban et al.(2006b)found that the leaching of coloured organic matters during the adsorption can be eliminated by pretreatments with formaldehyde in acidic medium,with sodium hydroxide solution after form-aldehyde treatment,or with sodium hydroxide only. According to Sˇc´iban et al.(2006a),NaOH improved the adsorption process by causing the liberation of new adsorption sites on the sawdust surface.An increase in the concentration of NaOH for modification purpose how-ever did not cause a significant increase of the adsorption capacity.The authors suggest that no greater than1%of concentration of NaOH solution should be used for mod-ification.The temperature of modification was also not a significant factor for the main increase of adsorption capacities of modified sawdusts.It was observed that only a slight increase in Cu2+and Zn2+adsorption occurred when thefir sawdust was treated with NaOH at higher tem-perature(80°C).The study on adsorption capacity byW.S.Wan Ngah,M.A.K.M.Hanafiah/Bioresource Technology99(2008)3935–39483939treatment with Na2CO3revealed the modified sawdusts had two times higher adsorption for Cu2+ions and six times higher for Zn2+ions compared to unmodified saw-dusts.The application of Na2CO3for chemical modifica-tion is less efficient than the use of NaOH.This is due to higher number of Na+ions in1g of NaOH compared to 1g of Na2CO3.In general,three possible reasons for the increase in adsorption capacities of heavy metal ions were given by the authors:(i)Changes on wood surface-increase in surface area,average pore volume and pore diameter after alkaline treatment.The surface area and average pore diame-ter increased about1.5–2times after modification. (ii)Improvement in ion-exchange process especially with Na+ions.(iii)Microprecipitation of metal hydroxides–Cu(OH)2 and Zn(OH)2in the pores of sawdust.Although the work on adsorption of copper and zinc ions onto sawdust of poplar tree was reported by Sˇc´iban et al.(2006a),they did not carry out a detail experiment on the kinetic of adsorption.The effect of sulfuric acid treatment on sawdust of pop-lar tree was studied by Acar and Eren(2006).Sulfuric acid poplar sawdust possessed good removal of92.4%Cu2+at pH5,while untreated sawdust could only removed47%. The kinetic of copper binding indicated that it is a rapid process and about70–80%of copper ions removed from the solution in10min.The percent of copper removal how-ever decreases as the metal concentration increases.The increase in percent of adsorption with adsorbent dose could be due to the increase in surface area and availability of more active sites.The treated poplar sawdust showed maximum adsorption capacity of13.945mg gÀ1against 5.432mg gÀ1for untreated sawdust which followed Lang-muir isotherm model.The maximum adsorption capacity for sulfuric acid treated poplar sawdust is higher than to the value recorded by NaOH treated poplar sawdust reported by Sˇc´iban et al.(2006a).Concentrated sulfuric acid was also used to modify coconut tree sawdust for removing mercury and nickel(Kadirvelu et al.,2003).It was reported that100%removal of mercury was achieved compared to81%for nickel and adsorption occurred in 1h.Rehman et al.(2006)reported the removal of Ni2+ions by using sodium hydroxide treated sawdust of Dalbergia sissoo,a byproduct of sawmills.The treatment of sawdust with NaOH results in the conversion of methyl esters which are the major constituents in cellulose,hemicellulose and lignin to carboxylate ligands.The adsorption time study revealed that nickel ions were removed fast in thefirst 20min due to extra-cellular binding.The maximum adsorp-tion capacity of Ni2+ions was found to be10.47mg gÀ1at 50°C.Adsorption was more favourable at higher tempera-ture and adsorption followed both Langmuir and Freund-lich isotherm models.A comparative study on the adsorption efficiency of untreated and NaOH treated sawdust of cedrus deodar wood was conducted by Memon et al.(2007).They reported that cedrus deodar sawdust mainly consists of acid detergentfibre(cellulose and lignin),hydroxyl groups (tannins)and phenolic compounds.The acidimetric–alkali-metric titration study revealed that sawdust has four major groups responsible for cadmium binding which were car-boxylic,phosphoric,amines and phenolic.Cadmium removal was more favoured by NaOH treated sawdust as the value of adsorption capacity was four times greater than untreated sawdust.Maximum removal of cadmium occurred at pH above4for both types of adsorbents.When the pH of the solution is greater than4,carboxylic groups will be deprotonated and the adsorbent surface will be neg-atively charged resulting in higher adsorption of cadmium. However;at pH less than3,carboxylic groups become pro-tonated and adsorption sites are unable to attract Cd2+ ions.NaOH treated sawdust also shows good settling prop-erty,making it easy tofilter or separate the adsorbent from the solution.Ion-exchange was considered as the predom-inant mechanism of cadmium adsorption as the values of adsorption energy(E)determined from Dubinin–Radushk-evic plots are in the range of9–16kJ molÀ1.Maximum adsorption capacity recorded at temperature of20°C was73.62mg gÀ1.A detail analysis on the ideal concentration of NaOH for modifying juniperfibre for adsorption of cadmium ions was carried out by Min et al.(2004).Sodium hydroxide treatment of lignocellulosic materials can cause swelling which leads to an increase in internal surface area,a decrease in the degree of polymerization,a decrease in crys-tallinity,separation of structural linkages between lignin and carbohydrates and disruption of the lignin structure. Sodium hydroxide is a good reagent for saponification or the conversion of an ester group to carboxylate and alco-hol,as shown in the equation below:RCOOR0þH2O!OHÀRCOOÀþR0OHð1ÞBased on the FTIR analysis,it was found that as the con-centration of NaOH increases(from0to 1.0M),the amount of carboxylate was also increased.A maximum concentration of0.5M of NaOH was suitable to carry out saponification process.After base treatment,the max-imum adsorption capacity of cadmium increased by about three times(from9.18to29.54mg gÀ1)compared to un-treated juniperfibre despite a decrease in specific surface area for the treated adsorbent.Data obtained from pseu-do-second-order kinetic study also revealed that base trea-ted juniperfibre had higher values of adsorption capacity, q e(mg gÀ1)and initial adsorption rate constant,h (mg gÀ1minÀ1)when compared to untreated adsorbent.Hexavalent chromium adsorption by formaldehyde treated sawdust was studied by Baral et al.,2006.Formal-dehyde is a common compound used to immobilize colour and water soluble compounds from sawdust(Garg et al.,3940W.S.Wan Ngah,M.A.K.M.Hanafiah/Bioresource Technology99(2008)3935–39482004).The adsorption capacity of Cr(VI)determined from Langmuir isotherm was low(3.60mg gÀ1)and equilibrium adsorption time took about5h.Adsorption process was strongly affected by several physico-chemical parameters such as pH,adsorbent dose,temperature and initial con-centration of chromium solution.Maximum adsorption occurred at pH range3–6and reduced significantly beyond pH6.The percentage adsorption of Cr(VI)increased with increase in adsorbent dose,but decreased with increase in metal concentration and temperature.Adsorption rate tends to increase with increase in adsorbent dose due to higher number of available adsorption sites.As concentra-tion of Cr(VI)increases withfixed amount of adsorbent dose,more Cr(VI)ions will remain in the aqueous phase, thus percentage adsorption will be small.The decrease in adsorption rate with increase in temperature indicates exo-thermic nature of adsorption,in which adsorption is more favourable at lower temperatures.According to Taty-Costodes et al.(2003),treatment with formaldehyde induces a stabilization of the hydrosol-uble compounds of adsorbent by creating covalent bonds on the constitutive units.This could eliminate the problem associated with the release of polyphenolic compounds which could cause an increase in COD in wastewater.A research on the adsorption of Pb(II)and Cd(II)onto form-aldehyde treated sawdust of Pinus sylvestris shows that the two metal ions were successfully removed in less than 20min at low concentrations(<10mg lÀ1).It was reported that metal ions could form complexes with the oxygen atom on carbonyl and hydroxyl groups(acting as a Lewis base).The maximum adsorption capacities of Pb(II)and Cd(II)were9.78and9.29mg gÀ1,respectively.Adsorption kinetic indicates that pseudo-second-order model was bet-terfitted than pseudo-first-order and intraparticle diffusion is one of the rate determining steps.Nickel,cadmium and lead adsorption by walnut sawdust treated with formalde-hyde in sulfuric acid was studied and it was found that adsorption is dependent on contact time,metal concentra-tion and temperature(Bulut and Tez,2003).Equilibrium time was established in about60min for all heavy metals. The kinetic study reveals that adsorption followed pseudo-second-order model better than pseudo-first-order.The maximum adsorption capacities were 6.43, 4.51and 4.48mg gÀ1for Ni,Cd and Pb,respectively.Based on tem-perature study,adsorption was favaourable at higher tem-peratures as the values of D G°become more negative.Chubar et al.(2004)studied the performance of various kinds of chemically treated cork powder obtained from cork oak tree for the removal of Cu,Zn and Ni.Treatment of cork powder with salts such as NaCl and CaCl2causes the conversion of active binding sites from the H+form to Na+and Ca2+form.The salt modified cork powder shows greater adsorption capacity than the unmodified cork especially at higher heavy metal concentrations.It was also noted that the Na+form cork recorded a higher adsorption capacity value than the Ca2+form.This obser-vation can be explained in terms of the different charge of cations whereby the interaction of cork powder binding sites with divalent calcium ions is stronger than the mono-valent sodium ions.Hence,the biosorption reaction of cop-per will be hindered.Treatment of cork powder with an alkaline solution(NaOH)at high temperature increased the sorption capacity toward heavy metals by about33%.A high concentration of NaOH however causes a decrease in copper removal due to the destruction of the biomass. Besides NaCl,CaCl2and NaOH,modification of cork powder could be carried out using commercial laundry detergent and the amount of copper removed was found to increase,probably due to the exposure of new binding sites.The use of NaClO and NaIO3will increase the num-ber of active binding sites by oxidation of the some of func-tional groups of cork to carboxylic groups,hence more copper ions could be sorbed.An increase of70–80%in cork capacity for copper was achieved after treating cork powder with NaClO containing7%of active chlorine. 2.5.Wheat branWheat bran,a by-product of wheat milling industries proved to be a good adsorbent for removal of many types of heavy metal ions such as Pb(II),Cu(II)and Cd(II).The application of a strong dehydrating agent like sulfuric acid (H2SO4)can have a significant effect on the surface area of the adsorbent,which eventually results in better efficiency of adsorption of copper ions as reported by O¨zer et al. (2004).It was found that upon treatment with sulfuric acid, wheat bran had a much higher surface area.The authors suggested that acid treatment caused changes in surface area by increasing the conversion of macropores to microp-ores.Maximum adsorption capacity for Cu(II)ions was reported as51.5mg gÀ1(at pH5)and equilibrium time of adsorption was achieved in30min.O¨zer and Pirinc¸c¸i (2006)conducted a study on the removal of lead ions by sulfuric acid treated wheat bran.It was reported that max-imum lead removal(82.8%)occurred at pH6after2h of contact time.Three isotherm models were analyzed for determining the maximum adsorption capacity of wheat bran particularly Langmuir,Freundlich and Redlich-Peter-son.Based on the non-linear plots,it was found that adsorptionfitted well to the Redlich-Peterson than Lang-muir and Freundlich models.The Langmuir plots indicate that maximum adsorption capacities increased with an increase in temperature(79.37mg gÀ1at60°C and 55.56mg gÀ1at25°C).The decrease in the values of D G°suggests that adsorption was more favourable at higher temperatures and adsorption was endothermic in nature. The kinetic study showed that lead adsorption could be described well with n th-order kinetic model.O¨zer(2006) also examined the sulfuric acid treated wheat bran for cad-mium ion removal from aqueous solution.After4h of con-tact time,the maximum adsorption capacity that could be achieved for cadmium was101mg gÀ1at pH5.Therefore, in general the order of maximum removal of the above three metals follows:Cd(II)>Pb(II)>Cu(II).W.S.Wan Ngah,M.A.K.M.Hanafiah/Bioresource Technology99(2008)3935–39483941。

基于反奖赏系统探究药物成瘾的神经调控机制*邓雨钧， 庆宏， 全贞贞△（北京理工大学生命学院，北京 100081）Neural mechanism of drug addiction based on anti -reward systemDENG Yujun ， QING Hong ， QUAN Zhenzhen △（School of Life Science ， Beijing Institute of Technology ， Beijing 100081， China. E -mail ： qzzbit 2015@ ）［ABSTRACT ］ Drug addiction is a type of chronic recurrent brain disease with extremely complicated pathogene⁃sis ， which is often manifested as spontaneous and compulsive drug seeking and using behavior. The anti -reward system plays an extremely important role in the occurrence and development of drug addiction -related symptoms. This article pro⁃vides a brief overview of the formation process ， symptom representation ， neural mechanism and motivational/behavioralchanges of drug addiction and their adversarial process theory ， as well as the anatomical structure of the anti -reward sys⁃tem and evidence for its involvement in regulating the occurrence and development of drug addiction. This work helps bet⁃ter understand the neural mechanism of drug addiction through the view of anti -reward system and provides insights for thetreatment of related diseases and drug abuse.［关键词］ 药物成瘾；反奖赏系统；泛杏仁核；缰核［KEY WORDS ］ drug addiction ； anti -reward system ； extended amygdala ； habenula［中图分类号］ R338.2； R742； R363.2 ［文献标志码］ Adoi ： 10.3969/j.issn.1000-4718.2023.07.018药物成瘾是一类由大脑相关结构改变引起的，发病机制极为复杂的慢性、易复发性脑疾病，常表现为自发地、强迫性地寻求并使用药物，无法控制药物的使用量［1］，以及在不能满足药物需求时出现负面情绪［2］。

ReviewAgricultural waste material as potential adsorbent for sequesteringheavy metal ions from aqueous solutions –A reviewDhiraj Sud *,Garima Mahajan,M.P.KaurSant Longowal Institute of Engineering and Technology,Department of Chemistry,Longowal 148106,India Received 15October 2007;received in revised form 22November 2007;accepted 22November 2007Available online 14February 2008AbstractHeavy metal remediation of aqueous streams is of special concern due to recalcitrant and persistency of heavy metals in environment.Conventional treatment technologies for the removal of these toxic heavy metals are not economical and further generate huge quantity of toxic chemical sludge.Biosorption is emerging as a potential alternative to the existing conventional technologies for the removal and/or recovery of metal ions from aqueous solutions.The major advantages of biosorption over conventional treatment methods include:low cost,high efficiency,minimization of chemical or biological sludge,regeneration of biosorbents and possibility of metal recovery.Cellulosic agricultural waste materials are an abundant source for significant metal biosorption.The functional groups present in agri-cultural waste biomass viz.acetamido,alcoholic,carbonyl,phenolic,amido,amino,sulphydryl groups etc.have affinity for heavy metal ions to form metal complexes or chelates.The mechanism of biosorption process includes chemisorption,complexation,adsorption on surface,diffusion through pores and ion exchange etc.The purpose of this review article is to provide the scattered available information on various aspects of utilization of the agricultural waste materials for heavy metal removal.Agricultural waste material being highly efficient,low cost and renewable source of biomass can be exploited for heavy metal remediation.Further these biosorbents can be mod-ified for better efficiency and multiple reuses to enhance their applicability at industrial scale.Ó2007Elsevier Ltd.All rights reserved.Keywords:Agricultural wastes;Biosorption;Industrial effluents;Heavy metal remediation;Adsorbent1.IntroductionToxic heavy metal ions get introduced to the aquatic streams by means of various industrial activities viz.min-ing,refining ores,fertilizer industries,tanneries,batteries,paper industries,pesticides etc.and posses a serious threat to environment (Celik and Demirbas,2005;Friedman and Waiss,1972;Kjellstrom et al.,1977;Pastircakova,2004).The major toxic metal ions hazardous to humans as well as other forms of life are Cr,Fe,Se,V,Cu,Co,Ni,Cd,Hg,As,Pb,Zn etc.These heavy metals are of specific con-cern due to their toxicity,bio-accumulation tendency and persistency in nature (Friberg and Elinder,1985;Garget al.,2007;Randall et al.,1974).Several past disasters due to the contamination of heavy metals in aquatic streams are Minamata tragedy in Japan due to methyl mer-cury contamination and ‘‘Itai-Itai ”due to contamination of cadmium in Jintsu river of japan (Friberg and Elinder,1985;Kjellstrom et al.,1977).Various regulatory bodies have set the maximum prescribed limits for the discharge of toxic heavy metals in the aquatic systems.However the metal ions are being added to the water stream at a much higher concentration than the prescribed limits by industrial activities,thus leading to the health hazards and environmental degradation (Table 1).Conventional methods for removal of metal ions from aqueous solutions include chemical precipitation,ion exchangers,chemical oxidation/reduction,reverse osmosis,electro dialysis,ultra filtration etc (Gardea-Torresdey et al.,1998;Patterson,1985;Zhang et al.,1998).However these0960-8524/$-see front matter Ó2007Elsevier Ltd.All rights reserved.doi:10.1016/j.biortech.2007.11.064*Corresponding author.Tel.:+911672284698;fax:+911672284840.E-mail address:suddhiraj@ (D.Sud).Available online at Bioresource Technology 99(2008)6017–6027conventional techniques have their own inherent limita-tions such as less efficiency,sensitive operating conditions, production of secondary sludge and further the disposal is a costly affair(Ahluwalia and Goyal,2005a).Another powerful technology is adsorption of heavy metals by acti-vated carbon for treating domestic and industrial waste water.(Horikoshi et al.,1981;Hosea et al.,1986).However the high cost of activated carbon and its loss during the regeneration restricts its application.Since1990’s the adsorption of heavy metal ions by low cost renewable organic materials has gained momentum(Bailey et al., 1999;Orhan and Bujukgungor,1993;Rao and Parwate, 2002;Vieira and Volesky,2000).The utilization of sea-weeds,moulds,yeasts,and other dead microbial biomass and agricultural waste materials for removal of heavy met-als has been explored(Bailey et al.,1999;Haung and Haung,1996;Sudha and Abraham,2003;Zhou and Kiff, 1991).Recently attention has been diverted towards the biomaterials which are byproducts or the wastes from large scale industrial operations and agricultural waste materials. The major advantages of biosorption over conventional treatment methods include:low cost,high efficiency,mini-mization of chemical or biological sludge,no additional nutrient requirement,and regeneration of biosorbents and possibility of metal recovery.Agricultural materials particularly those containing cel-lulose shows potential metal biosorption capacity.The basic components of the agricultural waste materials bio-mass include hemicellulose,lignin,extractives,lipids, proteins,simple sugars,water hydrocarbons,starch con-taining variety of functional groups that facilitates metal complexation which helps for the sequestering of heavy metals(Bailey et al.,1999;Hashem et al.,2005a,b,2007). Agricultural waste materials being economic and eco-friendly due to their unique chemical composition,avail-ability in abundance,renewable,low in cost and more efficient are seem to be viable option for heavy metal reme-diation.Studies reveal that various agricultural waste materials such as rice bran,rice husk,wheat bran,wheat husk,saw dust of various plants,bark of the trees,ground-nut shells,coconut shells,black gram husk,hazelnut shells, walnut shells,cotton seed hulls,waste tea leaves,Cassiafis-tula leaves,maize corn cob,jatropa deoiled cakes,sugar-cane bagasse,apple,banana,orange peels,soybean hulls, grapes stalks,water hyacinth,sugar beet pulp,sunflower stalks,coffee beans,arjun nuts,cotton stalks etc has been tried(Annadurai et al.,2002;Cimino et al.,2000;Hashem et al.,2006a,b;Macchi et al.,1986;Maranon and Sastre, 1991;Mohanty et al.,2005;Orhan and Bujukgungor, 1993;Reddad et al.,2002;Tee and Khan,1988).These promising agricultural waste materials are used in the removal of metal ions either in their natural form or after some physical or chemical modification.The present review article deals with the utilization of agricultural waste mate-rials as biosorbents for removal of toxic heavy metal ions from aqueous streams.2.Mechanism of biosorptionThe removal of metal ions from aqueous streams using agricultural materials is based upon metal biosorption (Volesky and Holan,1995).The process of biosorptionTable1Permissible limits and health effects of various toxic heavy metalsMetal contaminant Permissible limits for industrial effluent discharge(in mg/l)Permissiblelimits byinternationalbodies(l g/l)Health hazardsInto inland surfacewaters IndianStandards:2490(1974)Into publicsewers IndianStandards:3306(1974)On land forirrigation IndianStandards:3307(1974)WHO USEPAArsenic0.200.200.201050Carcinogenic,producing liver tumors,skin andgastrointestinal effectsMercury0.010.01–0102Corrosive to skin,eyes and muscle membrane,dermatitis,anorexia,kidney damage and severemuscle painCadmium 2.00 1.00–0305Carcinogenic,cause lungfibrosis,dyspnea andweight lossLead0.10 1.00–1005Suspected carcinogen,loss of appetite,anemia,muscle and joint pains,diminishing IQ,causesterility,kidney problem and high blood pressure Chromium0.10 2.00–50100Suspected human carcinogen,producing lungtumors,allergic dermatitisNickel 3.0 3.0–––Causes chronic bronchitis,reduced lung function,cancer of lungs and nasal sinusZinc 5.0015.00–––Causes short-term illness called‘‘metal fume fever”and restlessnessCopper 3.00 3.00––1300Long term exposure causes irritation of nose,mouth,eyes,headache,stomachache,dizziness,diarrhea 6018 D.Sud et al./Bioresource Technology99(2008)6017–6027involves a solid phase(sorbent)and a liquid phase(solvent) containing a dissolved species to be sorbed.Due to high affinity of the sorbent for the metal ion species,the latter is attracted and bound by rather complex process affected by several mechanisms involving chemisorption,complexa-tion,adsorption on surface and pores,ion exchange,chela-tion,adsorption by physical forces,entrapment in inter and intrafibrillar capillaries and spaces of the structural poly-saccharides network as a result of the concentration gradi-ent and diffusion through cell wall and membrane(Basso et al.,2002;Sarkanen and Ludwig,1971;Qaiser et al., 2007)(Fig.1).Agricultural waste materials are usually composed of lignin and cellulose as the main constituents.Other compo-nents are hemicellulose,extractives,lipids,proteins,simple sugars,starches,water,hydrocarbons,ash and many more compounds that contain a variety of functional groups present in the binding process.Cellulose is a crystalline homo-polymer of glucose with b1?4glycosidic linkage and intra-molecular and intermolecular hydrogen bonds (Demirbas,2000a,b).Hemicellulose is a heteropolymer of mainly xylose with b1?4glycosidic linkage with other substances of acetyl feruoyl and glycouronyl groups(Garg et al.,in press).Lignin is three dimensional polymer of aro-matic compounds covalently linked with xylans in hard-woods and galactoglucomannans in softwoods(Garg et al.,2007;Sjo¨tro¨m,1981)The functional groups present in biomass molecules acetamido groups,carbonyl,pheno-lic,structural polysaccharides,amido,amino,sulphydryl carboxyl groups alcohols and esters(Beveridge and Mur-ray,1980;Gupta and Ali,2000).These groups have the affinity for metal complexation.Some biosorbents are non-selective and bind to a wide range of heavy metals with no specific priority,whereas others are specific for certain types of metals depending upon their chemical composi-tion.The presence of various functional groups and their complexation with heavy metals during biosorption pro-cess has been reported by different research workers usingD.Sud et al./Bioresource Technology99(2008)6017–60276019spectroscopic techniques(Ahluwalia and Goyal,2005a; Garg et al.,2007;Tarley and Arruda,2004).3.Absorption modelsPredicting the rate at which adsorption takes place for a given system is probably the most important factor in adsorption system design,with adsorbate residence time and the reactor dimensions controlled by the system’s kinet-ics.Numerous kinetic models have described the reaction order of adsorption systems based on solution concentra-tion.These includefirst-order and second-order reversible ones,andfirst-order and second-order irreversible ones, pseudo-first-order and pseudo-second-order.The sorption isotherms represent the relationship between the amount adsorbed by a unit weight of solid sorbent and the amount of solute remaining in the solution at equilibrium(Park et al.,2006).Both Langmuir and Freundlich isotherm mod-els have been shown to be suitable for describing short-term and mono component adsorption of metal ions by different biosorbents(Aksu et al.,1999;Ho et al.,2002).On the other hand,reaction orders based on the capacity of the adsor-bent have also been studied,such as Lagergren’sfirst-order equation,Redlich Peterson model and BET model(Ho and Mckay,1998).Langmuir and Freundlich isotherm models are frequently used isotherm models for describing short-term and mono component adsorption of metal ions by different materials(Aksu et al.,1999;Yu et al.,2001).4.Thermodynamic parametersThe free energy change of sorption can be calculated by Eq.(1).D G0¼ÀRT ln Kð1Þwhere D G0is standard free energy change,R is the univer-sal gas constant(8.314J/mol/K),T is the absolute temper-ature and K is equilibrium constant.The apparentequilibrium constant of the biosorption,K0C is obtainedfrom Eq.(2).K0C¼CðbiosorbentÞeq=CðsolutionÞð2Þwhere C(biosorbent)eq and C(solution)eq are the metal ion concentrations on the biosorbent and in the solution at equilibrium.5.Performance of agricultural waste materials as biosorbents for the removal of heavy metalsRemoval of heavy metal ions from the aqueous streams by agricultural waste materials is an innovative and prom-ising technology.The efficiency of the waste material depends upon the capacity,affinity,and specificity includ-ing physico-chemical nature of it.Scattered research has already been done on the variety of biosorbents for the removal of metal ions as Cr,Cu,Ni,Pb,Cd,As,Hg etc. The adsorbents are taken either in the natural form,or modified by chemical and thermal treatment for increasing their sorption capabilities.5.1.Removal of chromiumChromium is a toxic heavy metal being released in the environment by applications like tanning,wood preserva-tion and pigments,dyes for plastic,paints,and textiles. Chromium occurs in a number of oxidation states,but chromium(VI)and chromium(III)are of main environ-mental concern(Yu et al.,2000).Extensive work has been reported for the removal of chromium employing waste agricultural materials.A number of agricultural wastes like,hazelnut shells, orange peels,maize cobs,peanut shells,soyabean hulls, jack fruit,soyabean hulls in natural or modified forms has been explored and significant removal efficiency was reported(Kurniawan et al.,2006).Diverse plant parts such as coconutfiber pith,coconut shellfiber,plant bark(Aca-cia arabica,Eucalyptus),pine needles,cactus leaves,neem leave powder have also been tried for chromium removal showing efficiency more than90–100%at optimum pH (Dakiky et al.,2002;Manju and Anirudhan,1997;Mohan et al.,2006a;Sarin and Pant,2006;Venkateswarlu et al., 2007).The utilization of rice bran and wheat bran as an adsorbent are found to be less effective as only50% removal efficiency was reported(Farajzadeh and Monji, 2004;Oliveira et al.,2005).Gardea-Torresdey et al. (2000)reported Avena monida(whole plant biomass) showed90%removal efficiency of Cr VI at optimum pH 6.0.Rice husk in natural form as well as activated rice husk carbon was used for the removal of chromium(VI)and results were also compared with commercial activated car-bon and other adsorbents.(Bishnoi et al.,2004;Mehrotra and Dwivedi,1988;Srinivasan et al.,1988).Saw dust of Indian rose wood prepared by treatment with formaldehyde and sulphuric acid showed efficient removal of chromium(VI)(Garg et al.,2004).Beech saw dust and rubber wood saw dust was also tried for chro-mium removal(Acar and Malkoc,2004;Karthikeyan et al.,2005).Sugarcane bagasse was used in natural as well as modified form and efficiency for both the forms was compared for the removal of Cr.(Gupta and Ali,2004; Krishanani et al.,2004;Rao and Parwate,2002).Utiliza-tion of mustard oil cake has been reported with significant removal efficiency and the results of activated carbon of sugar industry waste and commercial granular activated carbon for sequestering of heavy metal ions from aqueous solutions were compared(Ajmal et al.,2005;Fahim et al., 2006).Recently sugar cane baggase,maize corn cob and jatropha oil cake as such were used for removal of chro-mium under optimized conditions(Garg et al.,2007).Most of the studies showed that the chromium biosorp-tion by agricultural waste materials is quite high and varies from50to100%.Mostly biosorption occurs in acidic range particularly at pH2.0.Thus chromium speciation plays the dominant role in deciding the removal efficiency as at pH26020 D.Sud et al./Bioresource Technology99(2008)6017–6027chromium is present as chromium(III).Table2summa-rizes the work reported in literature for the removal of chromium by using agricultural waste materials.5.2.Removal of leadThe major source of lead in the environment is from plastics,finishing tools,cathode ray tubes,ceramics,sol-ders,pieces of leadflashing and other minor product,steel and cable reclamation.Lead can result in the wide range of biological effects depending upon the level and duration of exposure(Friberg and Elinder,1985).In the environment lead binds strongly to particles such as oil,sediments and sewage sludge so its removal is of great concern.Different agricultural wastes viz.rice straw,soybean hulls,sugarcane bagasse,peanut shells and walnut shells in their natural form have been used for removal of lead has been reported98%(Johns et al.,1998).Bankar and Dara(1985)conducted studies on Febrifuga tree bark in its natural form.Petioler felt sheath palm(PFP),agro waste of black gram husk,flowers of Humulus lupulus, waste tea leaves and water hyacinth were studied for removal of lead and efficiency of these materials varies from70to98%(Ahluwalia and Goyal,2005a;Gardea-Torresdey et al.,2002;Iqbal et al.,2002,2005;Kamble and Patil,2001;Saeed et al.,2005b).Lee et al.(1999)investigated removal of lead and other metal ions by apple residues modified with phosphorous (V)oxychloride in both batch and column studies and com-pared the results.Rose petals pretreated with NaOH,cal-cium treated sargassum and sugarcane modified with succinic anhydride has also been utilized for significant removal of lead.(Karnitz et al.,2007;Nasir et al.,2007;Tsui et al.,2006).Activated carbon prepared from agricultural waste was also explored by different workers and high effi-ciency for removal of lead has been reported.(Gajghate et al.,1991;Kadirvelu et al.,2001;Vaughan et al.,2001;Wil-son et al.,2006).Gupta et al.(1999)used bagassefly ash for removal of lead with65%removal efficiency.Saw dust of maple(Zhang et al.,1998),Pinus sylvestries(Taty-Costodes et al.,2003)and rubber wood saw dust(Raji et al.,1997)has shown85–90%removal efficiency but results show that modification did not enhance the removal efficiency for lead. Literature studies revealed that optimized value for biosorp-tion of lead is found around pH5–6(Table3).5.3.Removal of cadmiumCadmium and Cadmium compounds as compared to other heavy metals are relatively water soluble therefore mobile in soil and tends to bioaccumulate.The long life time PVC-window frames,plastics and plating on steel are the basic sources of cadmium in the environment.Cad-mium accumulates in the human body especially in kid-neys,thus leading to disfunction of the kidney(Volesky and Holan,1995).Potential use of rice bran and wheat bran was tried for sequestering cadmium and significant removal efficiency was reported(Montanher et al.,2005;Farajzadeh and Monji,2004;Singh et al.,2005).Studies were also con-ducted on use of rice polish,rice husk and black gram husk in their natural as well as modified form for the removal of cadmium and their relative efficiency was reported(Iqbal et al.,2005;Kumar and Bandyopadhyay, 2006;Singh et al.,2005;Tarley and Arruda,2004).Bark of the plants such as Pecia glehnii and Abies sachalinensis and dried plant biomass of parthenium was tried for the removal of cadmium(Ajmal et al.,2006;Seki et al., 1997).Use of other parts of the plants such as peels of peas,fig leaves,broad beans,orange peels,medlar peels and jack fruits as adsorbents have been reported to show high removal efficiency at acidic pH(Benaissa,2006).Table2Summary of work done by various researchers using low cost agricultural waste materials for the removal of chromiumAgricultural waste Metal ion Results ReferenceOat biomass Cr(III),Cr(VI)>80%Gardea-Torresdey et al.(2000) Formaldehyde treated saw dust Indian rosewood Cr(VI)62–86%Garg et al.(2004)Beech saw dust Cr(VI)100%Acar and Malkoc(2004) Chemically treated bagasse Cr(VI)50–60%Krishanani et al.(2004) Formaldehyde treated rice husk Cr(VI)88.88%Bishnoi et al.(2004) Bagassefly ash Cr(VI)96–98%Gupta and Ali(2004)Wheat bran Cr(VI)>82%Farajzadeh and Monji(2004) Coconut shellfibers Cr(VI)>80%Mohan et al.(2006a) Commercial granular Cr(VI)93–98%Fahim et al.(2006)activated carbon(C2&C3)and AC of waste from sugar industry(C1)C1>C2>C3Eucalyptus bark Cr(VI)Almost100%Sarin and Pant(2006)Neem leaf powder Cr(VI)>96%Venkateswarlu et al.(2007) Rubber wood saw dust Cr(VI)60–70%Karthikeyan et al.(2005) Pretreated bagasse with NaOH and CH3COOH Cr(VI),Ni(II)90%,67%Rao et al.(2002)Modified bagassefly ash Cr(VI)67%Gupta et al.(1999)Activated carbon from bagasse(carbonization&gasification)Cr(VI)Significant metal uptake Valix et al.(2006) Sugarcane bagasse,maize corn cob,jatropha oil cake Cr(III)Upto97%Garg et al.(2007)Raw rice bran Cr(VI),Ni(II)40–50%Oliveira et al.(2005)D.Sud et al./Bioresource Technology99(2008)6017–60276021Adsorption experiments conducted on hazelnut shells, peanut hulls,walnut shells,and green coconut shells gave significant results for removal of cadmium(Johns et al., 1998;Kurniawan et al.,2006).Studies were conducted on activated carbon of bagasse pith,coir pith,peanut shells and dates and their removal efficiency varies from 50to98%(Kadirvelu et al.,2001;Kannan and Rengas-amy,2005;Krishnan and Anirudhan,2003;Mohan and Singh,2002;Srivastva et al.,1996;Wafwoy et al.,1999). Research has also been carried out by using chemically treated agricultural waste materials like base treated rice husk,treated juniperfibers,and corncob modified with citric acid,modified peanut shells,succinic anhydride trea-ted sugarcane etc.(Karnitz et al.,2007;Min et al.,2004; Vaughan et al.,2001).Most of the studies showed that agricultural waste either in natural form or modified form is highly efficient for the removal of cadmium metal ions.Summary of research work done has been compiled in Table4.5.4.Removal of nickelNickel and its compounds have no characteristic odor or taste.The sources of nickel to the environment are nickel plating,colored ceramics,batteries,furnaces used to make alloys or from power plants and trash incinerators.The most harmful health effect of nickel is the allergic reactions (Akhtar et al.,2004).Experiments on removal of nickel were conducted on Cassiafistula biomass in its natural form and results show99–100%removal efficiency(Hanif et al.,2007). Waste tea leaves were also tried for sequestering of nickel from aqueous solutions(Ahluwalia and Goyal, 2005a).Saw dust of maple,oak and black locust have been reported as promising biosorbent for removal of nickel(Sciban et al.,2006;Shukla et al.,2005).Agricul-tural wastes such as peanut,pecan,walnut,hazelnut and groundnut shells in natural or modified form were also utilized for biosorption(Demirbas et al.,2002;Johns et al.,1998;Kurniawan et al.,2006;Shukla and Pai, 2005).Other agricultural waste materials as modified coir fibers,cotton seeds,soyabeans and corncobs have also been explored for removal of nickel(Marshall and Johns, 1996;Shukla et al.,2005;Vaughan et al.,2001).Sugar cane bagasse in its natural form showed more than 80%removal efficiency(Garg et al.,2007).Table5is a compilation of research work done on the removal of nickel.Table3Summary of work done by various researchers using variety of agricultural waste materials for the removal of LeadAgricultural waste Metal ion Results ReferenceOriza sativa husk Pb(II)98%Zulkali et al.(2006) Agricultural by product Humulus lupulus Pb(II)75%Gardea-Torresdey et al.(2002) Chemical modified apple residue waste Pb(II)Upto80%Lee et al.(1999)Agro waste of black gram husk Pb(II)Upto93%Saeed et al.(2005b) Febrifuga bark Pb(II)100%Bankar and Dara(1985) Chemically modified saw dust of rubberwoodPb(II)85%Raji and Anirudhan(1998) Coconut char based activated carbon Pb(II)100%Gajghate et al.(1991)Rose biomass pretreated with NaOH Pb,Zn(II)75%Nasir et al.(2007)Rice bran Pb(II),Cd(II),Cu(II),Zn(II)>80.0%Montanher et al.(2005)Saw dust of Pinus sylvestris Pb(II),Cd(II)96%,98%Taty-Costodes et al.(2003) Maple saw dust Pb(II),Cu(II)80–90%Yu et al.(2001)60–90%Water hyacinth Pb(II),Cu(II),Co(II),Zn(II)70–80%Kamble and Patil(2001)Low cost sorbents(bark,dead biomass,chitin,sea weed,algae,peat moss,leafmould,moss,zeolite,modified cotton)etc.Pb(II),Cd(II),Cr(VI),Hg(II)Good results Bailey et al.(1999)Waste tea leaves Pb(II),Fe(II),Zn(II),Ni(II)92%,84%,73%Ahluwalia and Goyal(2005b) Activated carbon from coir pith Pb(II),Hg(II),Cd(II),Ni(II),Cu(II)Hg-100%Kadirvelu et al.(2001)Pb-100%Cu-73%Ni-92%Cd-!00%Rice straw,soybean hulls,sugarcane bagasse,peanut shells,pecan and walnut shells Pb(II),Cu(II),Cd(II),Zn(II),Ni(II)Pb>Cu>Cd>Zn>Ni Johns et al.(1998)PFP(petiolar felt sheath palm)-peelings from trunk of palm tree Pb(II),Cd(II),Cu(II),Zn(II),Ni(II),Cr(VI)>70%Pb>Cd>Cu>Zn>Ni>CrIqbal et al.(2002)Activated carbon of peanut shells Pb(II),Cd(II),Cu(II),Ni(II),Zn(II)Upto75%Wilson et al.(2006)6022 D.Sud et al./Bioresource Technology99(2008)6017–6027Table4Summary of work done by various researchers using variety of agricultural waste materials for the removal of cadmiumAgricultural waste Metal ion Results ReferencePeels of peas,fig leaves,broad beans,medlar peel Cd(II)70–80%Benaissa(2006)Wheat bran Cd(II)87.15%Singh et al.(2005)Three kinds treated rice husk Cd(II)80–97%Kumar and Bandyopadhyay(2006)Rice polish Cd(II)>90%Singh et al.(2005)Steam activated sulphurised carbon(SA–S–C) from bagasse pith Cd(II)98.8%Krishnan and Anirudhan(2003)Base treated juniperfiber Cd(II)High removal capacity Min et al.(2004)Husk of black gram Cd(II)99%Saeed and Iqbal(2003) Straw,saw dust,datesnut Cd(II)>70%Dried parthenium powder Cd(II)>99%Ajmal et al.(2006) Bagassefly ash Cd(II),Ni(II)65&42%Srivastava et al.(2007) Bagasse Cd(II),Zn(II)90–95%Mohan and Singh(2002) Bagassefly ash Cd(II),Ni(II)90.0%Gupta et al.(2003)Rice bran Cd(II),Cu(II),Pb(II),Zn(II)>80.0%Montanher et al.(2005) Wheat bran Cd(II),Hg(II),Pb(II),Cr(VI),Cu(II),Ni(II)>82%except Ni Farajzadeh and Monji(2004)Hazelnut shell,orange peel,maize cob,peanut hulls,soyabean hulls treated with NaOH&jack fruits Cd(II),Cr(VI),Cu(II),Ni(II),Zn(II)High metal adsorption Kurniawan et al.(2006)Papaya wood Cd(II),Cu(II),Zn(II)98,95,67%Saeed et al.(2005a)Rice straw,soybean hulls,sugarcane bagasse, peanut shells,pecan and walnut shells Cd(II),Pb(II),Cu(II),Zn(II),Ni(II)Pb>Cu>Cd>Zn>Ni Johns et al.(1998)Poplar wood saw dust Cd(II),Cu,Zn(II)Cu>Zn>Cd Sciban et al.(2007) Chemically modified sugarcane with succinicanhydrideCd(II),Cu(II),Pb(II)>80%Karnitz et al.(2007) Powder of green coconut shell Cd(II),Cr(II),As(II)98%Pino et al.(2006)Bark of Abies sachalinensis&Pecia glehnii Cd(II),Cu(II),Zn(II),Ag(II),Mn(II),Ni(II)Upto63%Seki et al.(1997)Table5Summary of work done by various researchers using variety of agricultural waste materials for the removal of nickelAgricultural waste Metal ion Results ReferenceHazelnut shell activated carbon Ni(II)Effective removal Demirbas et al.(2002)Casiafistula biomass Ni(II)100%Hanif et al.(2007)Maple saw dust Ni(II)75%Shukla et al.(2005) Sugarcane bagasse Ni(II)>80%Garg et al.(2007)Tea waste Ni(II)86%Malkoc and Nuhoglu(2005) Defatted rice bran,chemically treatedsoybean&cottonseed hullsNi(II),Zn(II),Cu(II)57%,87%Marshall and Johns(1996) Waste tea leaves Ni(II),Pb(II),Fe(II),Zn(II)92%,84%,73%Ahluwalia and Goyal(2005a) Saw dust of oak and black locust hardwood(modified&unmodified)Ni(II),Cu(II),Zn(II)70–90%Sciban et al.(2006)Hazelnut shell,orange peel,maize cob, peanut hulls,soyabean hulls treated with NaOH&jack fruits Ni(II),Cr(II),Cu(II),Cd(II),Zn(II)High metal adsorption Kurniawan et al.(2006)Mustard oil cake Ni(II),Cu(II),Zn(II),Cr(II),Mn(II),Cd(II),Pb(II)Upto94%Ajmal et al.(2005) Coirfiber chemically modified withhydrogen peroxideNi(II),Zn(II),Fe(II)>70%Shukla et al.(2005) Dye loaded groundnut shells and sawdustNi(II),Cu(II),Zn(II)Up to90%Shukla and Pai(2005)PFP(petiolar felt sheath palm)-peelings from trunk of palm tree Ni(II),Pb(II),Cd(II),Cu(II),Zn(II),Cr(VI)>70%Pb>Cd>Cu>Zn>Ni>CrIqbal et al.,2002Agro waste of black gram husk Ni(II),Pb(II),Cd(II),Cu(II),Zn(II)Upto93%Saeed et al.(2005b)Modified&unmodified kenaf core,kenaf bast,sugarcane bagasse,cotton,coconut coir,spruce Ni(II),Cu(II),Zn(II)Upto88%Sciban et al.(2007)D.Sud et al./Bioresource Technology99(2008)6017–60276023。

福岛核电站地下水受到放射污染High levels of a toxic radioactive isotope have been found in groundwater at Japan's Fukushima nu clear plant, its operator says.福岛核电站附近的地下水中发现高剂量有毒的放射性同位素。

Tokyo Electric Power Company (Tepco) said tests showed strontium-90 was present at 30 times the legal rate.The radioactive isotope tritium has also been detected at elevated levels.The plant, crippled by the 2011 earthquake and tsunami, has recent ly see n a series of water leaks and power failures.The tsunami knocked out cooling systems to the reactors, which melted down.Water is now being pumped in to the re actors to cool them but this has left Tepco with the problem of how to safely store the cont aminated water.There have been several reports of leaks from storage tanks or pipes.Sea samplesStrontium-90 is for med as a by-product of nuclear fission. Tests showed that levels of stront ium in grou ndwater at the Fukushima plant had increased 100-fold since the end of last year, Toshihiko Fukuda, a Tepco official, told media.Mr Fukuda said Tepco believed the elevated levels originated from a lea k of contaminated water in April 2011 from one of the reactors."As it's near where the leak from reactor number two happened and taking into account the situation at the time, we believe that water left over from that time is the highest possibility," he said.Tritium, used in glow-in-the-dark watc hes, was found at eight times the allowable level.Mr Fukuda said that samples from the sea showed no rise in either substance and the company believed the groundwater was being contained by concrete foun dations."When we look at the impact that is having on the ocean, the levels seem to be within past trends and so we don't believe it's having an effect."But the discovery is another set-back for Tepco's plan to pump groundwater from the plant into the sea, correspondents say.Nuclear chemist M ichiaki Furukawa told Reuters news agency that Tepco should not release contaminated water into the ocean."They have to keep it somewhere so that it can't escape outside the plant," he said. "Tepco needs to carry out more regular testing in specific areas and disclose everything they find."The Fukushima power plant has faced a series of problems this ye ar. Early this month, radioactive water was found leaking from a storage tank.The plant also suffered three power failures in five weeks earlier this year. A leak of radioactive water from one of the plant's underground storage pools was also detected in April.。

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第50卷第'期2021年'月应用化工Appeoed ChemocaeIndusteyVoe.50No.1Jan.2021利用潜在生物吸附剂从水体系中去除有毒重金属江澜，闵燕，叶便达，贾朝刚，李越，陈浩然，常海军(重庆工商大学环境与资源学院，重庆市特色农产品加工储运工程技术研究中心，重庆400067)摘要:探讨了使用死亡生物的微生物源和木质纤维素的残留去除重金属的水溶液,总结了去除重金属的生物吸附等温线和动力学模型特征，并通过不同的仪器表征技术和相关的机制,讨论金属和生物吸附剂之间的相互作用。

工业废水排放造成的重金属污染是近几十年来最严重的环境问题，虽然有关水溶液中重金属截留的方法有很多报道，但目前的研究主要集中在开发环保型和经济性工艺&生物吸附法是一种潜在的去除重金属的方法，即使在金属浓度较低的情况下也是如此。

此外，还综述了脱附剂在生物质能再生和各种生物吸附剂回收利用方面的意义。

关键词:重金属；生物质;分离;生物吸附中图分类号:TQ09；X703文献标识码:A文章编号：1671-3206(2021)01-0194-06Elimination of toxic heavy metais from aqueous systemsusing potentiai biosorbentsJIANG Lan，MIA Yan，YE Bian-da，JIA Chao-gang，LA Yue，CHEN Hao-ran，CHANG Hai-jun(ChongqongEngoneeeongReseaech CenteefoePeoce s ong，Stoeageand Teanspoetatoon ofChaeacteeozed Ageo-Peoducts，Colleye of Environment and Resources，Chongqing Technology and Business University，Chongqing400067，China)Abstract:The present review repo/s on the use of dead biomass of microbial source and Cgnoc/Umsic residues for removal of heavy metal from aqueous solution，summaczes the appCcabiCty of biosorp/on iso-themi and kinetic models io heavy metal removal and discusses on the chd/c/Cstic features of biosor-bent，onteeactoonsbetween metaeand boosoebent，and theasocoated mechanosmstheough doeeentonsteu-mentaechaeacteeozatoon technoques.Heaeymetaecontamonatoonsduetoeeuentdoschaege eom ondusteoes aeeseeoouseneoeonmentaepeobeem soncetheeastseeeeaedecades.Aethough seeeeaemethodsaeeeepoeted on thesequesteatoon oUheaeymetaeseom aqueoussoeutoons，stoeeeseaech os ocused on thedeeeeopment of aoW/endly and economic process.Biosorption is a potential process Sor removal of heavy metals even attheeowmetaeconcenteatoon.Moeeoeee，de4oebongagent4ognofocanceon thebooma4eegeneeatoon and ee-cyceepo4oboeotoe4ofeaeoou4boo4oebentaeecon4odeeed on thepee4enteeeoew.Key words:heavy metals;biomass;separation;biosorption环境污染及其相关毒性效应是当今世界面临的主要问题&重金属形式的无机物对水体的污染处置是研究人员面临的重要挑战之一⑴。

Vitamins ---- Translation1. Researchers found that the level of vitamin C stored in the body of the victim with a common cold fell drastically and was close to the level of people suffering from scurvy.2. Minor degrees of vitamin C deficiency are common, though outright scurvy only occur when the diet is markedly deficient in fresh fruits and vegetables.3. Vitamins are organic compounds that must be supplied in the diet or injected into the body to maintain health.4. Vitamins produce no energy but play an essential role in the transformation of energy and in the regulation of metabolism.5. Vitamins are classified/distinguished by the letters of the alphabet, such as vitamins A, C, D, E, K and the B-complex.6. Vitamins and minerals are found in small amounts and are needed in minute quantities, as compared with the other nutrients.7. The diseases which develop from the absence of vitamins are known as vitamin deficiency diseases. For example, a lack of vitamin A brings about night blindness; a deficiency of vitamin D results in rickets.8. Some vitamins are soluble in fats whereas others are soluble in water. They are, therefore, termed fat-soluble and water soluble vitamins respectively.9. In addition to the general nutrients, another two groups of nutrients, vitamins and inorganic, or mineral, salts are also required by the body.10. M ost nutrients contain more than one nutrient, but no single food contains all the nutrients in the amounts you need.食物抗癌1. O verwhelming statistical evidence shows that smokers are more likely to develop cancer of the lung, throat, and tongue than are non-smokers.2. F ruits and vegetables are chock-full of a variety of antioxidants which can snuff out oxygen free radicals, substances that are thought to make cells more susceptible to cancer.3. A well-balanced diet will give your body various nutrients of vitamins, minerals, proteins, starches, and sugars that it needs to operate smoothly.4. T he risk of lung cancer is directly related to the number of cigarettes smoked each day--the higher the number, the higher the risk.5. E ven smokers may be protected from developing lung cancer by a daily portion of carrots, spinach or any other vegetables and fruits.6. S ome studies of animals and humans have suggested that vitamin A offers some protection against lung cancer.7. F urther studies will be necessary before the link between lung cancer and carotene can be firmly established.8. A nimal studies show that garlic blocks carcinogens that have been linked to colon and stomach cancer.9. A diet of more fruits and vegetables will undoubtedly play a major role in reducing cancer incidence as well as the number of deaths caused by the disease.10.Beta-carotene not only has a direct toxic effect on tumor cells, but also reduces the growth of lung-cancer cells and altered the proteins needed for tumors to grow.化学与物质----Translation1. B riefly speaking, a scientist differs from an artist mainly in that a scientist not only interprets the outer world, but also tries to transform it into a better one.2. S cience begins with necessity, curiosity, and questions about the unexplained phenomena in nature.3. T he ways in which an element or a compound combines or reacts with other things are its chemical properties.4. T he chemist is interested in the composition and properties of substances and the transformations they undergo during a chemical reaction.5. I t is very easy to fall into the habit of taking some painkiller when there is any slight pain.6. T he delicate operations performed by surgeons today would not be possible without anesthetics.7. T oday it is generally recognised that the human body is a chemical factory in which countless complex chemical and physicalchanges are constantly taking place.8. T he substance salt is composed of the metal sodium and the corrosive gas chlorine, but its chemical properties are quite different from those of sodium and chlorine.9. C hemotherapy is the treatment of disease by the administration of chemical substances which kill or prevent the growth of pathogenic organisms within the body.10.Substances that lessen pain but do not affect other sensations are called pain relieving drugs.麻醉药Translation1. It is not many years since a man who had to have an operation felt all its pain.2. I t is attributable to the discovery of anesthetics that surgeons can now perform all kinds of operations without causing pain.3. S pinal anesthesia produces excellent anesthesia and relaxation for the performance of many operations on the lower parts of the body.4. T he exact mechanism in which the general anesthetic drugs exert their effect on the brain is still unknown, although many theories have been proposed.5. T he introduction of anesthetics to surgery has made possible much more delicate and lengthy operations, thus greatly extending the field of surgery.6. N arcotics are applied to those drugs which are sedative in their action upon the body but which also produce insensibility to pain.7. C ontrary to what one might think, it’s only 50 years or so since penicillin, the antibiotic once regarded as the wonder drug, came into being.8. S cientists point out that since the sedative action of a drug results from its effect on the nerves, it must possess solubility in the fluids of the body which surround the nerves.9. A n anesthetic must be volatile if it is to be administered through oral inhalation, while those which can be administered through the rectum or injected into the spine do not have to be volatile.10.In spite of the danger of a patient’s contracting pneumonia after the use of ether as an anesthetic, ether is still widely em ployed because the anesthesia it produces is one of deep relaxation.绿色药房-草药Translation1. T he plant kingdom was once man’s only pharmacy. Yet when you enter a modern chemist’s shop today, you can hardly find a sign of the use of plants in medicine.2. T oday the number of plants used in medicine has decreased, but hidden away in many pills, capsules, and medicine bottles are the active chemicals originally found in the plant kingdom.3. S ome chemicals which plants make may be poisonous, others may be chemicals that are extremely valuable to us as medicines.4. D uring the many thousands of years that man has been on the earth, he has been trying out various plants that grew around him.5. T here has existed for many years mistrust, suspicion or hostility between the orthodox and the herbal practitioner which threatens the possibility of a good working relationship.6. W hen one considers the therapeutic impact of quinine, it is evident how great is the debt of medicine to plant-derived drugs.7. H owever, the past few decades have witnessed an obvious diminution in the number of plant-derived drugs introduced into medicine.8. T he legacy of traditional Chinese medicine is a treasure house with an inexhaustible supply of new potential drugs which is to be explored with an introduction of new approaches.9. H ad pharmacological approaches not been introduced into the investigation of Vinca rosea, the discovery of vincalcukoblastine would have been postponed by many years.10.Western practitioners find it difficult to believe that someone who knows nothing of a disease mechanism could still be capable of curing it.Natural Products1. One of the oldest of human activities is the study of plants and animals, particularly as sources of food.2.From the earliest times man had to distinguish between those plants which were poisonous and those which were not and there graduall y developed a knowledge of natural drugs.3. As late as the beginning of the present century pharmacognosy had developed mainly on the botanical side, being particularly concerned with the description and identification of drugs.4.Undoubtedly the plant kingdom still holds many species of plants containing substances of medical value which have yet to be discover ed.5. As a result of modern isolation and pharmacological testing procedures, new plant drugs usually find their way into medicine as purified substances.6. Many of the botanical, chemical and physical techniques employed in pharmacognosy are also applicable to the analysis of other comm odities, such as foods, spices and cosmetics.7. While pharmacognosy has been generally studied for practical purposes and may thus be called an applied science it has played an imp ortant role in the development of the pure sciences.8. Recent phytochemical examination of plants which have a suitable history of use in folklore for the treatment of cancer has, indeed, oft en resulted in the isolation of principles with antitumour activity.9. The growth of knowledge of biochemistry and physiology, which led to the concept of the chemical control of biological processes, has been of particular importance for pharmacology.10. Primitive man depended on preventive use of nature’s stock of plants and herbs to avoid disease and to maintain health and vigor.有机化学Translation1. The remarkable advances made in modern medicine would not have been possible without the aid of chemistry.2. Since the body is essentially a chemical machine, a knowledge of the chemistry of bodily functions seems essential to the physician.3. The production of food by plants and animals involves the rearrangement of atoms in molecules.4. Fortunately, few kinds of work seem to urge people on to success more effectively than does the pursuit of chemistry.5. So far the motive behind the search for synthetics has been a wish to produce better things for less money, and for more people.6. Isolation of increasing numbers of purified materials from living forms and recognition of the fact that all contained carbon gave birth to organic chemistry.7. When coal is burned in a furnace it combines with oxygen to give carbon dioxide, a new substance with different composition and properties from coal and oxygen.8. Many specific chemical reactions are important because of the energy which they use or supply.9. In the study of organic chemistry, students are expected to use familiar symbols which are constructed into two- or three-dimensional molecular formulas.10.From the food we eat, the clothes we wear to the buildings we live in, all have been fashioned to a considerable extent by organic chemistry.新药研制1 Translation1. F ormerly, drugs were extracted from natural plants and animal sources, and therapeutic use was based on traditional experience.2. D rug development strategies involve serendipity, molecular roulette, programmed basic research with synthesis of specific chemical, etc..3. T hough it’s the most satisfying in the development of new drugs, the approach is expensive and there is no guarantee of succe ss.4. W hen a drug is used by millions, there are certain to be adverse reactions even though the risk to any individual is small.5. M ost drugs have a safe upper limit of dosage; beyond this toxic effects may be expected to occur.6. P enicillin, one of the most powerful killers of bacteria was discovered quite by accident by Alexander Fleming.7. P harmacological experiment on a new drug determines whether the drug has the desired profile of action in model system.8. T he increase in knowledge of biochemical mechanisms results in a more rational approach to the development of new drugs.9. E xtensive formal toxicological tests are required before a new drug can be used on patients.10.Chemists and biologists have now attached great importance to such fields of research as molecular biology and biochemicalpharmacology.新药研制2 Translation1. T he rationale for the development of new drugs should be provide better drugs; better in the sense of being either more effective, safer or cheaper.2. T he representative of the pharmaceutical manufacturer has been specially trained to promote his particular new product.3. O nly after animal studies have proved efficacy can clinical evaluation of new drugs be undertaken.4. N ew drug evaluation in man can be divided into four phases each of which should be conducted under strict supervision.5. A dose-ranging study should only be performed on volunteers who are informed about the implications of the tests, and who give their consent freely.6. D ose-ranging studies should only be performed under medical supervision, as there exist some possible risks during the test.7. L arge scale clinical trials in Phase 3 are to establish new drug’s profile of action and frequency of adverse effects.8. T he expensive cost in drug development is borne by the pharmaceutical manufacturer, which justifiably expects to recoup it when the product is finally marketed.9. I nformation about the new drug published in well-established journals is more reliable than that offered by the medical representative whose livelihood depends on the ability to promote the product.10.Heavy investment in promotion has not simply led to the use of undistinguished new drugs, but to a higher cost of the drugs as well.药理学范畴Translation1. T he science of the effects of drugs on the body is called pharmacology, and the scientists who study it are pharmacologists.2. P harmacology is not a science that can be studied on its own, but that closely related to other branches of science.3. P harmacologists should not only understand the normal processes that take place in the body, but know how the functions of the body are affected by disease.4. P roperly used, drugs are great blessing to mankind; improperly used, they could destroy the race.5. D uring the first part of the twentieth century there have been enormous strides in the field of pharmacology.6. M an continues to strive, not only for a longer life span, but for a healthier one as well.7. W ith the frequent use of more than one therapeutic agent by a patient, particularly the elderly, drug interactions that result in toxicity are likely events.8. T he clinician is interested primarily in drugs that are useful in the prevention, diagnosis, and treatment of human diseases.9. M ost of the natural drugs are now highly purified and differ little from synthetic chemicals, the interests of the clinician in pharmacognosy are correspondingly decreased.10.As a border science, pharmacodynamics borrows freely from both the theories and experimental techniques of physiology, biochemistry, immunology, pathology, etc..良药滥用-----Translation1. A lthough the development of antibiotics has been of incalculable benefit to mankind, it has also given rise to serious complications.2. T he widespread use of antibiotics has resulted in the natural evolution of strains of disease germs which are resistant to such medications.3. A new multidrug-resistant tuberculosis, now prevalent in the world, causes serious infections that may not respond to chemotherapy.4. S ome antibiotics are effective against a large range of microorganisms, they are, therefore, known as broad-spectrum antibiotics.5. S ome drugs may not cause physical dependence, or addiction, but many persons do become habituated to their use.6. D rug abuse is thought of as the misuse of drugs potentially harmful to the individual user or to society.7. M any persons, believing that antibiotics can cure any disease, press their doctors for a dose of penicillin for such virus ailment as influenza.8. A ddiction is the body’s continued need for drug s because of their physiological effects after they are first taken.9. I n comparison, the inadequacies and potential dangers of antibiotics are much less widely known.10.Antibiotics are used so carelessly around the world that they are creating a new health threat to mankind.抗癌的食物（全文翻译）现在饮食开始被考虑作为抵抗癌症的主要武器。

百草枯中毒的治疗进展陈桂喜（综述），李　昌，李金雨※（审校）（解放军第175医院，厦门大学附属东南医院急诊科，福建漳州363000）中图分类号：R459.4 文献标识码：A 文章编号：1006⁃2084（2013）11⁃2023⁃03　doi：10.3969/j.issn.1006⁃2084.2013.11.034 摘要：百草枯属剧毒除草剂，对人畜有较强的毒性。

20世纪50年代末，百草枯的除草作用被发现，1962年首次在市场上销售，每年均有很多人死于百草枯中毒。

百草枯对全身各个器官均有极强的毒性，病程进展快，病死率很高，临床表现各异，最终患者多因器官功能障碍综合征以及肺纤维化所致的低氧血症死亡。

国内外学者至今仍未发现百草枯的特效解毒药物，该文就近年来百草枯中毒治疗的进展予以综述。

关键词：百草枯；中毒；治疗进展Treatment Progress in Acute Paraquat Poisoning　CHEN Gui⁃xi，LI Chang，LI Jin⁃yu.（Department of Emergency，PLA NO.175Hospital/Southeast Hospital of Xiamen University，Zhangzhou363000，China）Abstract：Paraquat is a highly toxic herbicide，which has strong toxicity to humans and animalsThe her⁃bicide effect of paraquat was found at the end of1950s.Since its introduction in the market in1962，there were many people died of paraquat poisoning every year.Paraquat has very strong toxicity on various organs of the body with different clinical manifestations，and ultimately the patients died of organ dysfunction syndrome （multiple organ dysfunction syndrome，MODS），and hypoxemia caused by pulmonary fibrosis.The domestic and foreign scholars have not discovered the effective drugs for paraquat poisoning，and here is to make a review of the research on the treatment progress of paraquat poisoning in recent years.Key words：Paraquat；Poisoning；Treatment progress 百草枯化学名1，1′⁃二甲基⁃4，4′⁃联毗睫阳离子盐，以阳离子形式存在，比较容易溶于水中，微溶于乙醇，几乎不溶于大多数有机溶剂，在碱性介质中极易破坏，是全球广泛使用的除草剂。

R 22;6232F N N S f (33,33)D Z ,23@6TO XICITY O F BISPHEN OL A O N THE GROWTH OF ZEBRAFISHEMBRYOSDUAN Zheng 2Hua and ZHU Lin(College of Environmental Sc ienc e and Engi neering ,Nankai University ,T ianjin 300071,China)A bstr act :In order to evaluate the toxicity o f the bisph enol A (BPA)on th e grow th o f zebrafish embry os ,fertilized eggs were ex 2posed t o the concentration o f 2.00,4.00,6.00,8.00,10.00,15.00,18.00,22.00and 25.00mg/L BPA for 72h at 26±1℃.T he results revealed that the subleth al toxicolog ical end points induced by BPA were :delayed hatch >b lood balk >cys t >al 2tered axial curvature and tail malformation.T he median embryo lethal concen tration (LC50)after 24h was 16.36mg/L.W e con 2cluded that the BPA toxicity on zebrafish embry os were caused b efore 8h exposure and it was n ot the result o f lon g 2term accumula 2tion.Th erefore ,BPA mayb e cause altered g ene ex pression at the early stage o f zebrafish embry os.In the furth er stud ies ,w e will use the technology of genetic chips to look for th e toxic mechan ism of BP A.Key w or ds :Bis phen ol A;Z ebrafish embry os ;T ox icityCLC number :X 174 Document code :A Ar ticle ID :100023207(2006)0620638205 Bisphenol A (BPA)is a chemical estr ogen 2like sub 2stance w ith pr operties that are of environmental c oncern.I t is widely used in t he chemical industry to manufactureepoxy 2and polyester 2styrene resins.I t has been reportedthat BPA ranges betw een 0and 33μg in each plastic cup [1].A fter a tw o 2w eek exposure to 0.5%bisphenol A it has been reported that disattachments betw een sertoli cell sand spermatogonia were observed while spermatog onia w ere arranged in di s order and displacement of s permatogo 2nia a way fr om the basem ent membrance of seminfer ous tubules as well as flocculated chr omatins of nuclei in ser 2toli cells and spermatog onia occurred[2].At high exposurelevel (60.00mg/L ),BPA c ould retard the gr ow th andcardiac tube differentiation of visceral yolk sac (VY S),and induce various embry onic de fect s ,including an ab 2normal neural system ,arch ,optic ,flexion and small limb bud ,etc.[3].In pr ofessional production and in daily life ,absorp 2tion of large am ount s of bisphenol A thr ough the skin re 2sulted in extensive damages to kidney ,liver ,spleen ,pancrea and lung [4].Because of its w i de usage in plas 2tics ,BPA has caused great envir onmental pollution.S tudies have testified that BPA is potentially toxic to em 2bryos and causes genetic de fects.An exposure to humanestrogen 2sensitive MCF 27breast cancer cells produces an increase in cell pr oliferation and changes in the lever of pr ogester 2one receptors [5].BPA can al s o be c onverted to DN A bi nding metabolites in vitro [6].Zebrafish have merits as test s pecies because of sim 2ple breeding technology ,short gr ow th per iod ,high fecun 2dity and transparent eggs.Theref ore ,zebra fish i s a per 2fect m odel to study the developm ental growth of verte 2brates [7,8].Z ebra fish embryos have bec ome an ef fective test material to substitute adult fi sh i n bioassay testing.1　Materials and met hods1.1　Fish Zebra fish w ere purchased fr om a local orna 2mental fish supplier (T ianji n ,China ).A ll adult fish (fe 2male :m ale ratio =1∶2)were maintai ned indoors at an ambient tem perature of about 26℃w ith a natural dark/light cycle of 10/14hours in the zebra fi sh aquarium facility (80cm 3×40cm 3×50cm 3),and they w ere fed w ith fr ozen第30卷第6期水生生物学报Vol.30,No.62006年11月ACT A HY DROBIO LOGICA SINICANov.,2006　ec eive d da te :2004114A cc epte d da te :2009ounda tion ite m :ational at ural cie nce und 040091047019Corre sponding a uthor :ua n henghua E ma il :na chir onomid larvae fr om an uncontaminated sour ce,tw ice daily.Charcoal filtered tap w ater w as used for breeding the fish.The volume of the w ater in the tank was about100L, and the number of the fish i n t he tank w as about200.The oxygen saturation w as m aintained above80%.The tem per2 atur e of the water w as controlled by an autom atic heat stick and m easured by a t herm ometer.The fish w ere acclimated for about one m onth be fore being used.1.2　Chemicals　Bisphenol A(2,22di(42hydr ox2 yphenyl)pr opane)w as purchased from Fuchen Chemical C ompany(T i anjin,China;purity>98.0%).All oth2 er chemicals including ethanol w ere reagent grade and purchased fr om a comm ercial source.The w ater used in this experiment was MiliQ w ater (M iliport C or p.)or synt hetic w ater.The chemical com2 position of synthetic water included12.95mg/L NaH C O3, 1.15mg/L K Cl,24.65mg/L MgS O7H2O,and58.80 mg/L CaCl22H2O.Bisphenol A w as diss olved in the synthetic w ater to2 gether w ith a little et hanol as c os olvent.The concentration of ethanol i n the actual exposure sol ution shoul d be no m ore t han0.01%.The test c oncentrations of BPA w ere 0.00,2.00,4.00,6.00,8.00,10.00,5.00,18.00, 22.00and25.00mg/L.1.3　Equipment　The equipment needed f or the study included:(a)inverted m icr osc ope,(b)N U NC242well multiplates,(c)air and light c onditioned r oom, (d)tem perature and light c ontr olled aquari um,(e)pH2 meter,(f)oxygen meter,(g)automatic heat stick, (h)therm ometer,(i)self2adhesive foil to c over multi2 plates,(j)glass spaw n trap(L×W×H=30cm×18cm ×6cm),and(k)glass vessels.1.4　Exposure　The fertilized eggs were separated from the non2fertilized eggs under a stereo microscope and placed in w ell s of multiplates.There were totally24eggs in one242well plate for one test concentration.F or20 w ells,each w ell has one fertilized egg placed in respec2 tively with2m L test solution.The remaining4w ell s of each plate were filled wit h2m L dilution water and one egg per w ell as internal contrast.Then all the multiplates with eggs w ere sent to the air conditioned room.Water tem per26±℃T x2 y,developmental stage,and exposure duration induced spe2 cific teratogenic defects.There fore,exposure w as de2 signed w ith three ways:firstly,ear ly cleavage(immedi2 ately after fertilization,0hpf)exposure;secondly,gastru2 la(8h post2fertilization,8hpf)and segmentation(24hpf) exposure;finally,exposure started at0hpf for8hours and then the embry os w ere picked out and maintained them in t he dilution water(8h paused exposure).1.5　Stat istical analysis　D ata from microscopic exam2 inations of the embry os were categ orized according to types and severities of e ffects,and then the median em2 bryo lethal concentration and the median e ffect concentra2 tion were calculated fr om the statistics.All ex periments were repeated three times respectively.Student’s t2test was used f or m ean se paration analysis,and data w ere il2 lustrated by means of standard deviation(S.D.).T o evaluate d ose2response relationships,post hoc tests for linear trend used the Origin s oftware.C omparisons tests betw een groups w ere carried out by one2w ay A NO V A.A p value of<0.05w as c onsidered stati stically significant different.2　ResultsFirstly,at t he0hpf exposure,blisters w ere br ought a fter4h exposure,and the m edian e ffec t concentr ation (EC50)of it was13.00±0.60mg/L(T ab.1),and t he letha l c oncentration(LC50)after24h was16.36±0.40m g/L whereas all the embryos w ere dead when exposed at25.00 mg/L.Exposure of zebrafish embryos to sublethal con2 centrations of BPA consi stently caused several types of m orphological de fect s.The duration of the exposure,de2 velopmental stage,and c oncentrations,all a ffected t he frequency and severity of teratogenic defects.The primary e ffects w ere blood balk i n the circulatory system,cyst (Fig.1(C,D))and delayed hatch.The median effect c oncentrations(EC50)for adverse e ffects(mortality and developmental de fects)were observed(T ab.1).Mean2 w hile,high c oncentrationsof BP A treated embryos show ed altered axial curvature and tail malformations(Fig.1(E, F)).These results revealed that the sublethal toxic ologi2 cal endpoi nts induced by BPA were:delayed hatch> >y>x2 f6期DU AN Z heng2Hua et al.:T OXICITY OF BISPHE NO L A O N T HE G R OWTH OF ZE BRAFISH E MBRY OS639ature was m aintained at21in test chambers.o i cit tests were designed to determine which concentration blood balk c st altered a ial curvat ure and tail m al ormation.T ab.1　The obs erved m edi an e ffect concentrat ions (EC 50)for adver s e effect s (m ortality and developm ental de fects)of 0hpf expos ure T oxicol ogical endpoints 4h 2bli s ters brought 32h 2bl ood block 722delayed hatch72h 2cys tE C 5013.00±0.60mg/L15.00±0.80m g/L13.00±0.50mg/LN Aa NA a 2N one a pplied data.While the concentrati on of BPA w as 15.00m g L 21,the percent of cys t exhibited by zenra fish em bryos of 0hpf ex pos ure was 17.64%. b None abnorm al effect was shown in blank controlgroupsFig.1　Observed normal and abnorm al embryo and fish.(A)48h norm al em bryo ,i n contras t s oluti on ;(B)72h norm al fi s h a fter hatched out ,in contras t s ol ution ;(C)48h cyst in the em bryo ,8hpf expos ure ,15.00m g/L BP A ;(D)72h cys t after hatched out ,8hpf exposure ,15.00mg/L BPA ;(E )72h tail m alform ations in t he embryo ,8hpf expos ure ,20.00m g/LBP A ;(F )72h t ail m al form ations after hatched out ,8hpf exposure ,20.00m g/LBPA S ec ondly ,zebra fish embryos were incubated in the above 2m entioned concentr ations of BPA fr om 8hpf (8h post fertilization)and 24hpf c ontrast to 0hpf.Embryos exposed a fter an age of 32h ours sh ow ed that while at 0hpf various toxicity e ffects occurred ,n one w as noted at later startingpoints of exposure.A t 0h pf and 8hpf exposure ,the e ffects of delayed hatch and cyst at 48h and 72h w ere both much m or e pr on ounced than those starting at 24hpf ex posur e.There w as n o difference betw een 0h pf and 8hpf at lethal and sublethal toxicity ,while 24hpf had much low er ef fects (T ab.2).640　ACT A HY DRO B I O LOG ICA SINICA30卷T ab.2　Effect s of B PA on embr yonic devel opm ent and subsequent malfor m at ions after var ious postfertilization s tart i n g t im es to test concentrat ions :0hpf =imm edi atel y after fert i l i zat ion ,8hpf =8hours post 2fertilization and 24hpf =24hours post fert ilizat ionT oxicity endpoints0hpf exposure8hpf expos ure24hpf expos ure32hW hile at 0hpf various t oxicity effects occured ,none w as noted at lat er s t arting poi nts to exposure 48h Hatch rate C ys tNone Obs erved Obs ervedN one Observed N one ObservedE C 50=18.00±2.00m g/L bN one Observed72hDelayed hat ch rate 13.00±0.50mg/LS im ilar t o the 0hpf exposureaE C 50=25.00±1.50m g/L bC ys tW hile at 15.00m g/L ,17.64%observedW hi l e at 15.00m g/L ,5.26%obs erved Obs erved onl y a fter 25.00mg/L aW hile BP A concentrati on was 10.00m g/L ,hatch rate w as 22.00%;bS tri ctly ,it s houl d not be called EC 50here.We jus t m ean the BPA c oncent ration whil e t he rate was 50.00%for conversi on F inally ,zebrafish embryos w ere exposed at 0hpf but paused a fter 8h contrast to the 72h persistent incubation.The differences between the above tw o treatments w ere not obvious a fter 32h developm ent stage.The EC 50of the tw o sublet hal ef fect s (blood bal k ,and delayed hatch)at 8h paused exposure w ere 19.00±0.50and 19.00±1.60mg/L BP A (F ig.2).The difference between these treatments above was analyzed by one 2w ay A NO V A.The p value of 32h blood balk was 0.025while that of 72h delayed hatch rate ,was 0.016.There fore ,it w as found that the ef fect s of 8h paused exposure w as significantly different w ith 72h sustaining exposure ,w hich meant the toxicity of BPA w as greatly decreased at 8h pausedexposure.Fig.2　E ffects of BPA i n 8h paus ed exposure and 24h s us t aini ng exposure.(a)32h bl ood bal k ,p =0.025<0.05;(b)72h delayed ,=6<5,f ff f x f y ff x ,x y f B y x 3　DiscussionZebrafish embryos pr oved to be sensitive bioassay or 2ganisms f or assessing the toxicity of environmental pollu 2tants.The embry onic developm ent of zebra fish has been divided into six major stages (early cleavages ,blastula ,gastrula ,segmentation ,pharyngula ,and hatching )and each is defined by a variety of developm ental events.The test ex posures ,begi nning at different developmental stages and conti nuing f or various periods of time ,identified which stages were m ost vulnerable to chemical induced abnormalities.In this study ,we found bisphenol A has pr ofound e ffects on the developm ental stage of zebrafish embry os.The experiment of 82hour paused exposure re 2vealed that it had nearly no difference w ith the 722hour c ontinued exposure at let hal and sublethal toxicity level.W hile the embryos were exposed after 8hours ,the toxici 2ty of BPA w as nearly the same w ith 0hpf ex posure ,but it w ould decrease greatly at 24hpf exposure.There fore ,w e can c onclude that BP A m ay cause altered gene ex pression at the early stage of zebrafi sh embry os ,but it is n ot t he result of accumulation.H owever ,there are tw o shortc omings in this study.One is that BPA is a kind of sur factant.Because its sur 2face tension is much higher than that of the water ,when it is di ssolved in the w ater ,it w ill mainly act at the w ater 2substance inter 2sur face.That means the actual concentra 2tion of BP A at the w ater 2sur face interface is higher t han in f ,z f 2y y f T f ,f B 6期DU AN Z heng 2Hua et al.:T OXICITY OF BISPHE NO L A O N T HE G R OWTH OF ZE BRAFISH E MBRY OS 641　hatch rate p 0.010.0.Accordi ng to the p val ue s it w a s ound t hat the e ect s o 8h pause d e posure were si gni ic antl di e rent with 72h sustaining e posure whic h mea nt the t o icit o PA wa sgreatl decreased at 8h paused e posurethe bulk o the test w ater.H owever the ebra ish em br os are alwa s at the bottom o the multiplate wells.here ore the c oncentrations o PA c ould not reach t heentire sur face area of the eggs.Another aspect is that BP A is also a kind of organic substance;it is easily ad2 sorbed by the plate w alls and b ottoms as w ell as at the egg sur face.This rapid abs orption will reduce the real c on2 centration of BP A in the water,but abs or ption on t he egg sur face w ill al s o prevent s ome of the test substance to di2 rectly reach the embry o inside the egg.One w ay to study to true c oncentration acting at the test organism could be to use the G C2MS technology to calibrate the concentration of BPA in the water and embry os at each developmental stage to revise our results.In summary,our findings are significant because we dem onstrate that the envir onmental estrogen2like chemi2 cal,bi sphenol A,has ef fect on the zebrafish embryos at the ear ly gr ow th stage,but it is not the result of accumu2 lation(The parent generation has not been ex posed).Al2 though it is unsure that w hether bi sphenol A alters the gene expression,our results may al s o pr ovide markers for the further study on the development of the animals and humans in response of exposure to envir onmental estr ogen2 like chemicals.In the further studies,w e look forw ard to the technology of genetic chips to look for the toxic mech2anism of BP A.Re fer ences:[1]　Br otons J A,Olea2Serrano M F,Vilialobos M et al.X enoes t r ogensreleased from lacquer coatings in food cans[J].Environ H ealth P er2 spect,1995,103:608—612[1]　Deng M X,Wu D S,Zhan L.S tudy on mechani s m of reproductiontoxi city of to es t r ogic bi s phenol A rel ated to envi ronm ent[J].J Envi2ronment al Health,2001,18:134—150[3]　Li Y,P ei X R,Long D X,C heng X,G a o L F,Chen X G.Terato2genicity of bis phenol A on pos t2im planted rat and m ous e em bryos:anin vitro s tudy.J ournal of Hygi ene Re search,2003,32:89—92 [4]　S ax N I.Dangerous pr operties of industrial chem ical s[J].Bitton ed2ucational publishing,1975:458—1008[5]　Z hu Y,Shu W Q,Zhuo J B,Yu N,Liu B.E valuati on of the es tro2genic active of bi s phenol A in vitro and study on the M echanism s[J].Chongqi ng Envi ronmental Science,2003,25:20—22[6]　Atkins on A,R oy D.In vit r o conversi on of environm ent al estrogeni cchem ical bis p henol A to D NA binding m etabolite(s)[J].BiochemBi ophy s Res Commun,1995,210:424—433[7]　K at hryn A H.C ontri buti on of early cells t o t he fat e m ap of the ze2bra fish gas trula[J].Sci enc e,1994,265:517—520[8]　S chulte C,Nagel R.Tes ti ng acute toxicity i n the em bryo of ze2bra fish,Brachydani o reri o,as an alternative to the acute fish test[J].P re li minary Re sult s,1994,22:12—19642　ACT A HY DRO B I O LOG ICA SINICA30卷。

China &Foreign Medical Treatment中外医疗敌草快概述敌草快化学名为1,1’-亚乙基-2,2’-联吡啶,与百草枯同属联吡啶类除草剂[1],分子量344.05,纯品为无特征性气味黄色结晶,其水溶剂在中性和酸性条件下稳定,在高于pH 9的碱性溶液中容易降解,其半数致死量(LD50)为235mg/kg(大鼠),125mg/kg(小鼠),敌草快可被土壤中的粘土矿物和有机物如蒙脱石烈吸附[2]。

敌草快可通过消化道、皮肤黏膜、呼吸道或肌肉注射吸收,口服为主要摄入途径,通过眼、阴道等途径接触中毒亦有报道[2-3]。

敌草快经皮肤吸率仅为0.3%但随着皮肤受损其吸收率可升至3.8%,经消化道吸收率<10%[2],吸收后可迅速分布至全身大部分组织器官,动物实验发现大鼠敌草快灌胃染毒后0.9h 血浆浓度达到高峰,血浆平均滞留时间4.9h,清除半衰期为19.3h 并且敌草快不会选择性地聚集于肺组织中[4]。

动物实验发现敌草快染毒24h 后组织中浓度顺序为:肾脏>脾脏>肝脏>心脏>肠>肺脏[5]。

敌草快性质稳定,在体内仅少量在肝脏通过细胞色素P450酶氧化为毒性较低的单嘧酮和双嘧酮衍生物,口服摄入后24h 内约94%以原型经粪便排出,入血的敌草快及其代谢物主要以尿液在48h 内排出[2]。

1中毒机制目前机制未完全阐明,主流观点为敌草快(Diquat,DQ)进入细胞后,经过单电子加成形成不稳定的DQ +自由基,DQ +极不稳定,将电子转移到分子氧形成超氧阴离子自由基(·O 2-),而DQ +失去电子后转化为DQ 2+。

DQ 2+在细胞色素P450还原酶和NADPH 作为辅酶的氧化还原反应作用下再次转化为单价的DQ +,DQ +继续和分子氧结合,持续产生超氧阴离子产物·O 2-,由此形成持续的氧化还原循环。

此时细胞色素P450还原酶和NADPH 不断消耗,阻碍了谷胱甘肽循环,干扰了细胞内的能量代谢。

Removal of chromium (III) and cadmium (II) from aqueous solutionsAbstractChromium and cadmium are toxic heavy metals present in wastewaters from a variety of industries. A strong cation exchange resin, Amberlite IR 120, was used for the removal of chromium and cadmium. The resin was prepared in two different cationic forms, as Na + and H +. The optimum conditions were concentration, pH, stirring time and resin amount. The concentration range was between 2-50 rag/L, pH range between 2-10, stirring time between 5-60 min, and the amount of resin was from 50-1000 rag. Exchange capacities, moisture content and optimum conditions ofthis resin were determined in a batch system. The stirring speed was 2000 rpm during all ofthe batch experiments. The initial and final chromium and cadmium amounts were determined by atomic absorption spectrophotometry.The optimum conditions were found to be a concentration of 20 mg/L, pH of 5.5, stirring time of 20 min and 100 mg of resin. The results obtained show that the Amberlite IR 120 strong cation-exchange resin performed well for the removal and recovery of chromium and cadmium.Keywords:Chromium(III); Cadmium(II); Ion-exchange resins; Toxicity;Conservative technologies1. IntroductionBoth metals are common and important water pollutants. They are often discharged simultaneously from a variety of industrial sources includingelectroplating rinse waters. Due to their toxicity even at low concentrations, the maximum levels allowed of metals are regulated by legislation in each country.The release of large quantities of heavy metals into the natural environment has resulted in a number of environmental problems. Cadmium, which is widely used and extremely toxic at relatively low dosages, is one of the principal heavy metals responsible for causing these problems. The main anthropogenic pathway through which cadmium(II) and chromium(III) enter the environment is via wastes from industrial processes. As heavy metals cannot be destroyed in the natural environment,technologies that can remove and recovery heavy metals from wastewater are needed.Classical techniques of heavy metal removal from solutions include the following processes: precipitation, electrolytic methods, ion exchange, evaporation and adsorption. Chemical precipitation is currently the most widely used treatment technique for removal of heavy metals. Nevertheless, particularly frustrating aspects of this method are significant sludge production, the ever-increasing cost for landfill disposal of the resulting toxic sludge, and most importantly, the long-term environmentalconsequences .Therefore, alternative treatment processes for the removal and possibly the recovery of toxic metals have to be applied.Sorption, used here as a general term including several mechanisms such as ionexchange, surface complexation, etc., is considered as a common treatment method in many water and wastewater treatment schemes, regulating also the transport of chemical species in aquatic systems. Activated carbon, biomass and ion exchange are commonly used for removal of heavy metals. Chromium is used in a variety of industrial applications, including etectroplating and as a corrosion inhibitor in cooling towers. Chromium salts are used to tan a treated animal hide to produce leather.Ion exchange is one of the most effective techniques for the removal of chromium from tannerywastewaters. Chromium exists in two stable oxidation states, Cr(III) and Cr(VI). The Cr(VI) state is of particular concern because this form is hazardous to health. Chromium is introduced into natural bodies of water from industries such as electroplating, leather tanning, cement,steel and photography. It is found in solution in different chemical forms, for example, textileand tanning wastes may contain either the hexavalent or trivalent chromium species, while electroplating and metal finishing wastes contain primarily the trivalent chromium species.Cadmium is one of the most toxic heavy metals and is considerednon-essential for living organisms. This element is found at low concentrations in natural environments, but human activities have led to increased levels on all the continents. Cadmium is present in wastewaters from metallurgical alloying, ceramics, electroplating, photography, pigment works, textile printing, chemical industries and lead mine drainage. Cadmium is removed from wastewaters by precipitation, electrocoagulation, adsorption, biosorption, activated carbon filtration and ion exchange. Amberlite IR 120 is agel-type polystyrene, sulphonated strong cation-exchange resin. Rohm and Haas [24] showed that its principal characteristics have excellent physical, chemical and thermal stability, good ion-exchange kinetics and high exchange capacity.Conservative technologies for metal control have an increasing interest, as they are able to remove pollutants and reuse valuable by-products obtained from wastes and/or side streams from manufacturing processes. The present paper examines optimum conditions of a strong cation-exchange resin (Amberlite IR 120) for the removal and recovery of chromium and cadmium.2. Material and methods2:1. Reagents, solutions, resins and equipmentThe resin used in this work was Amberlite IR 120 (Rohm and Haas Company), a strong acidic cation-exchange resin based on a styrene matrix. Table 1 shows the main physicochemical properties of the resin investigated, and Table 2 shows suggested operational conditions of the resin. This resin was prepared in two different cationic forms as Na + and H +. Under these two conditions, exchange capacities, moisture content and other optimum conditions were determined in a batch system.The optimum conditions were concentration, pH, stirring time and resin amount. Chromium and cadmium amounts were determined by atomic absorption spectrophotometry (AAS) on a Model Spect. AA 20 (Varian) with an airacetylene flame used for determination of the chromium amounts in the aqueous phase with the following settings: wavelength, 357.9; lamp current, 7 mA; slit, 0.2 nm; air/acetylene ratio, 3.5/1.5; and for cadmium with the following settings: wavelength, 228.8; lamp current, 4 mA; slit, 0.5 nm;air/acetylene ratio, 3.5/1.5. All pH measurements were made with apH-meter (Metrohm) and a combination glass electrode.Analytical reagent-grade basic chromic sulphate [Cr4(SO4)5(OH)2],[Cd(NO3) 2. 4H20], HCI, NaCI NaOH, and chemicals (Merck, Germany) were used. Freshly prepared solutions were used throughout the experiments. Water was deionized and purified further with a Milli-Q water purification system (Millipore, USA).Table 1Physicochemical properties of the Amberlite IR 120 resinFunctional group SulphonicMatrix StyreneMoisture-holding capacity, %:Na + form 44-49H + form 41-56Total exchange capacity, eq/L:Na form ≥ 2.00H form ≥ 1.80Table 2Suggested operating conditions of Amberlite IR 120Operation temperature, C 120 max.Service flow rate, BV/h 5-40Regenerants HC1、H2SO4、NaCIFlow rate, bed volume/h 2-8 2-20 2-8Concentration, % 5-8 0.7-6 10Level, g/L 50-150 60-240 80-250Slow rinse, BV at 2regeneration flow rateFast rinse, BV at service 4-8flow rate2.2.Procedures2.2.1.Conditioning of resinAfter three preliminary recyclings of the resin in a column system with 1M HC1 and NaOH solutions to remove eventual chemical residues (solvents, functionalizing agents) trapped in the matrixes of the resins during their preparation, the samples were finally converted into sodium and hydrogen forms by 1 M NaCl or HCl.2.2.2. Determination of the resin moisture contentSamples of 1 g of ion exchangers in the Na and H + forms were dried at 110C for 1 h, cooled in a desiccator and weighed. This was continued until the attainment of a constant weight.2.2.3. Determination of ion-exchange capacityThe ion-exchange capacity was determined in reference to both Na and H forms by using column techniques. Accordingly, after loading the sample (3g) into a glass column, the resin was eluted with 20 mg L -1 concentration of chromium and cadmium solutions at a 2 BV/h flow rate. The results are given in Table 3 with determined moisture contents.Table 3Exchange capacities and moisture content of the resinResin (Amberlite IR 120) Na form H formCapacity (eq/L) (column) 1.12 0.97Capacity(eq/L) (titrimetric) 1.47 1.36Moisture content (%) 47.45 55.202.2.4.General study procedureThe conditioned resin samples (Na + and H forms) were used for removal of chromium and cadmium in the batch method. The effects of concentration, pH, stirring time and resin amount were investigated for determination of optimum conditions. An amount of 0.1 g resin samples was put into contact with 50 mL of solution containing chromium and cadmium for 20 min (pH 5). Stirring speed was 2000 rpm during the batch experiments. All the operations were conducted at room temperature. After filtration of thesolid phase, the content of chromium and cadmium in the liquid phase were determined by AAS.3.Results3.1. Operating conditions for the Amberlite IR 120 resin3.1.1. ConcentrationChromium(III) and cadmium(II) concentrations were selected in the range of 2 to 50 mg/L for two different ionic forms of resin (studied pH: 5.5). The effect of concentration on metal adsorption was investigated and the results are given in Figs.1 and 2. Experiments were done using 0.1 g of resin with different metal concentrations (2- 50 rag/L). It was found that the metal amounts retained were almost stable in this concentration range for both the metal and ionic forms of resin. Adsorption of cadmium was a bit higher than chromium for both forms of this resin. In the beginning values of concentration, the results show that there was higher adsorption of the Na + form. The maximum adsorption was obtained as 93.4% for cadmium and 90.27% for chromium (Na + form resin). An optimum concentration of 20 mg/L was chosen in these experiments.3.1.2. pHThe studied pH range was 2-10, Because of the precipitation of metals, high pH values were not preferable. The effect ofpH on metal adsorption as determined in batch experiments and the results are given in Figs. 3 and 4. Cadmium adsorption was much higher than chromium in the Na + form. After pH 6, because of precipitation of chromium, the optimum pH was chosen as pH 5.5 for both metals. In this pH adsorption values were 90.8% (cadmium) and 68.24% (chromium) for the Na + form. For the H + from the values were 81.1% (cadmium) and 72.41% (chromium).3.1.3. Stirring timeThe stirring time range was between 5- 60 min. The effect ofstirring time on metal adsorption was investigated, and the results are given in Figs. 5 and 6. It was found that metal amounts retained were almost stable in this stirring time range for both metals in Na + form.For the H + form resin, the adsorption values were increased with increasing stirring time for cadmium. It was almost stable for chromiumin this form. As the optimum stirring time, 20 min was chosen for both forms of resin.3.1.4. Resin amountThe effect of the amount of resin on adsorption of both metals was investigated. For this purpose, the resin amounts were taken between50-1000 mg. The results are given in Figs. 7 and 8. The results show that the retention of chromium is less than cadmium in the beginning resin amounts, but it was increased with increasing amounts of the Na + form resin; the results for cadmium adsorption were lower than chromium for the H + resin form.Exchange capacities and moisture contents of the resin were determined for two different ionic forms (see Table 3).4.ConclusionsAccording to these experimental results and all previous works with cationic resins for removal of chromium and cadmium, it was demonstrated that Amberlite IR 120 is a strong cationic resin with good capability and efficiency. The Amberlite IR 120 resin generally showed better performance in the Na + form.Optimum conditions were found at a concentration of 20 mg/L, pH 5.5, stiring time 20 min, and amount of resin 100 mg.The results obtained show that the Amberlite IR 120 strongcation-exchange resin performed well for the removal and recovery of chromium and cadmium.从水溶液中去除Cr 3+和 Cd2+摘要铬和镉是毒性重金属，当前广泛存在于各行各业所产生的污水中。

收稿:2007年10月,收修改稿:2007年12月*教育部国家大学生创新性实验计划(No.2007SR34),国家海洋局海洋溢油鉴别与损害评估技术重点实验室开放基金(No.200809)资助**通讯联系人 e -mail:shiningpup@过硫酸盐活化高级氧化新技术*杨世迎**陈友媛 胥慧真 王 萍 刘玉红 王茂东(中国海洋大学环境科学与工程学院海洋环境与生态教育部重点实验室 青岛266100)摘 要 过硫酸盐在热、光、过渡金属催化等条件激活下产生强氧化性的硫酸根自由基 SO -4。

基于 SO -4的过硫酸盐活化 高级氧化技术 在环境污染治理领域的应用,是刚刚发展起来的崭新的研究方向,具有广阔的应用前景。

本文在分析其基本原理的基础上,综述了过硫酸盐活化技术在国内外土壤地下水有机污染原位修复、难降解有机废水处理等环境污染治理方面的研究进展,并就存在问题进行了研究展望。

关键词 过硫酸盐活化 硫酸根自由基 高级氧化技术 土壤地下水修复 有机污染物中图分类号:X53;X52 文献标识码:A 文章编号:1005-281X(2008)09-1433-06A Novel Advanced Oxidation Technology Based on Activated PersulfateYang Shiying*Chen Youyuan Xu Huizhen Wang Ping Liu Yuhong Wang Maodong(The Key Laboratory of Marine Environment &Ecology,Ministry of Education,College of EnvironmentalScience and Engineering,Ocean University of China,Qingdao 266100,China)Abstract The ther mal,photochemical or metal ions activated decomposition of persulfate anions (S 2O 2-8)produces a powerful oxidant known as the sulfate free radical ( SO -4),which can potentially destroy organic compounds.Activated persulfate oxidation chemistry is an e merging advanced oxidation technology (AOT )for organic pollutants degradation.This paper,for the first time,provides an up -to -date overvie w of application of the novel technology in not only soil and groundwater re mediation,but also wastewater treatment.S 2O 2-8is a relatively new for m of in situ chemical oxidation (ISC O)oxidant that has mainly been investigated at bench -scale.However,the technology has developed rapidly due to the considerable research and applied use of this oxidant at an increasing number of field sites.As forwastewater treatment,S 2O 2-8is mostly used as an electron -trapping agent to suppress hole -electron recombination in the TiO 2photocatalytic system,and only a very few reports have discussed organic pollutants direc -t degradation by activated persulfate oxidation.The prospects of activated persulfate oxidation technology are also discussed.Key words activated persulfate;sulfate radical;advanced oxidation technology;soil and groundwater remediation;organic pollutants过硫酸盐包括过一硫酸盐(peroxymonosulfate 或oxone)和过二硫酸盐(peroxydisulfate 或persulfate),通常情况下(包括本文)是指后者。

Introduction to PhysiologyIntroductionPhysiology is the study of the functions of living matter. It is concerned with how an organism performs its varied activities: how it feeds, how it moves, how it adapts to changing circumstances, how it spawns new generations. The subject is vast and embraces the whole of life. The success of physiology in explaining how organisms perform their daily tasks is based on the notion that they are intricate and exquisite machines whose operation is governed by the laws of physics and chemistry.Although some processes are similar across the whole spectrum of biology—the replication of the genetic code for or example—many are specific to particular groups of organisms. For this reason it is necessary to divide the subject into various parts such as bacterial physiology, plant physiology, and animal physiology.To study how an animal works it is first necessary to know how it is built. A full appreciation of the physiology of an organism must therefore be based on a sound knowledge of its anatomy. Experiments can then be carried out to establish how particular parts perform their functions. Although there have been many important physiological investigations on human volunteers, the need for precise control over the experimental conditions has meant that much of our present physiological knowledge has been derived from studies on other animals such as frogs, rabbits, cats, and dogs. When it is clear that a specific physiological process has a common basis in a wide variety of animal species, it is reasonable to assume that the same principles will apply to humans. The knowledge gained from this approach has given us a great insight into human physiology and endowed us with a solid foundation for the effective treatment of many diseases.The building blocks of the body are the cells, which are grouped together to form tissues. The principal types of tissue are epithelial, connective, nervous, and muscular, each with its own characteristics. Many connective tissues have relatively few cells but have an extensive extracellular matrix. In contrast, smooth muscle consists of densely packed layers of muscle cells linked together via specific cell junctions. Organs such as the brain, the heart, the lungs, the intestines, and the liver are formed by the aggregation of different kinds of tissues. The organs are themselves parts of distinct physiological systems. The heart and blood vessels form the cardiovascular system; the lungs, trachea, and bronchi together with the chest wall and diaphragm form the respiratory system; the skeleton and skeletal muscles form the musculoskeletal system; the生理学简介介绍生理学是研究生物体功能的科学。