REGULAR ARTICLE
Nitrogen dynamics at undisturbed and burned Mediterranean shrublands of Salento Peninsula, Southern Italy
Michael Dannenmann&Georg Willibald&
Sebastian Sippel&Klaus Butterbach-Bahl
Received:13May2010/Accepted:16August2010/Published online:10September2010
#Springer Science+Business Media B.V.2010
Abstract Fire is a major disturbance in shrubland ecosystems of the Mediterranean basin,with high potential to alter ecosystem nitrogen(N)stocks and N cycling.However,postfire effects on gross rates of soil N turnover(ammonification,nitrification,micro-bial immobilization,denitrification)have rarely been investigated.We determined gross rates of N turnover including nitrous oxide fluxes and dinitrogen emissions in the mineral soil of unburned and burned shrublands of Southern Italy6months after a natural fire.In soil of burned plots,both gross ammonification and gross nitrification were significantly higher than in soil of unburned plots(2.2±0.3versus0.6±0.1mg N kg?1sdw day?1for ammonification and1.1±0.1versus0.5±0.1mg N kg?1sdw day?1for nitrification).Microbial immobilization,in particular of nitrate,could not compensate for the increase in inorganic N production, therefore soil nitrate concentrations were considerably higher at the burned plots.Soil microbial biomass carbon and nitrogen concentrations were significantly lower in soils of burned plots than in soils of unburned plots.Dinitrogen was the dominant end product of denitrification and emitted at higher rates from the unburned plots than from the burned plots(0.094±0.003versus0.004±0.002mg N kg?1sdw day?1, while there was no net nitrous oxide flux(burned plots)or slight net nitrous oxide uptake(control plots). These results show that postfire patterns of gross N turnover in soil can exhibit a significant reduction of both microbial N retention and N gas losses via denitrification.
Keywords Maquis.Fire.N cycling. Ammonification.Nitrification.Denitrification. Nitrous oxide.Dinitrogen.Microbial biomass.
He flow soil core technique
Introduction
Fire is a major disturbance in Mediterranean ecosys-tems,with high potential to alter ecosystem N stocks and N cycling(Moreno and Oechel1995;Certini 2005;Castaldi and Aragosa2002;Knicker2007). Fire frequency may increase under future environ-mental conditions,since available regional predictions assume that air temperatures and drought event probability are significantly increasing due to climate change(Lavorel et al.1998;Pi?ol et al.1998).
Plant Soil(2011)343:5–15
DOI10.1007/s11104-010-0541-9
Responsible Editor:Per Ambus.
M.Dannenmann(*)
Institute of Forest Botany and Tree Physiology, Chair of Tree Physiology,University of Freiburg, Georges-Koehler-Allee53/54,
79110Freiburg,Germany
e-mail:michael.dannenmann@https://www.doczj.com/doc/0b12459681.html,
M.Dannenmann
:G.Willibald:S.Sippel:
K.Butterbach-Bahl
Karlsruhe Institute of Technology(KIT),Institute for Meteorology and Climate Research(IMK-IFU), Kreuzeckbahnstrasse19,
82467Garmisch-Partenkirchen,Germany
However,our understanding how fire may affect soil microbial N cycling in Mediterranean ecosystems is still limited.
Soil microbial nitrogen(N)cycling in terrestrial ecosystems is of high ecological significance,as it regulates ecosystem N retention;N loss along gaseous and hydrological pathways which can affect atmospheric chemistry,climate change and water quality;and plant nutrient availability (Schimel and Bennett2004;Rennenberg et al. 2009).Gross N ammonification,i.e.the microbial production of ammonium(NH4+)from organic N compounds,is a key processes of soil N cycling, since free NH4+in plant-free soil is subject to two competing microbial processes and fates,i.e.nitrifi-cation to nitrate(NO3-)and immobilization into microbial biomass.After nitrification,NO3--N may also either be immobilized by soil microorganisms, undergo dissimilatory nitrate reduction to ammonium (Silver et al.2001),or may be denitrified.Via denitrification,NO3-is reduced stepwise to nitrite, the secondary greenhouse gas nitric oxide(NO),the potent primary greenhouse gas and most important destruent of stratospheric ozone(Ravishankara et al. 2009)nitrous oxide(N2O)as intermediates,and to molecular dinitrogen(N2)as the dominant end-product.Production of these N gases by denitrifica-tion leads to N loss from the ecosystem.The last step of denitrification,i.e.the reduction of N2O to N2 catalyzed by the enzyme nitrous oxide reductase,is converting reactive nitrogen back into its inert form, and hence,significantly contributes to closing the global nitrogen cycle(Galloway et al.2003). Furthermore it reduces soil N2O losses(Chapuis-Lardy et al.2007;Dannenmann et al.2008). However,the conversion of reactive N back to N2 by denitrification is thought to represent the largest uncertainty of the N cycle at all scales(Galloway et al.2004;Groffman et al.2006).Due to methodo-logical difficulties(Butterbach-Bahl et al.2002; Groffman et al.2006)reliable measurements of N2 emissions from terrestrial ecosystems are scarce which limits our understanding of the significance of the single permanent sink for reactive nitrogen, but also impedes the quantification and comprehen-sion of the denitrification process as a whole (Davidson and Seitzinger2006;Groffman et al. 2006).The latter also feedbacks on our understand-ing of microbial NO3-immobilization,as this is often calculated from the consumption of15NO3-, assuming that gaseous N losses via denitrification are not significant for the NO3-mass balance (Davidson et al.1992;Stark2000).Hence,underes-timation of denitrification probably lead to frequent overestimation of microbial NO3-immobilization in 15N pool dilution experiments.
Our understanding of N ammonification,nitrifi-cation and microbial immobilization of inorganic N has significantly improved in the last decades for a wide range of ecosystems.In particular,the devel-opment and application of15N isotope pool dilution and—tracing techniques(Kirkham and Bartholomew 1954;Davidson et al.1991,1992,Stark2000; Murphy et al.2003;Booth et al.2005)facilitated a more holistic view of actual N turnover and its environmental controls compared to the more widely used determination of net rates of N turnover(Eno 1960),which confound simultaneously occurring production and consumption of inorganic N,as e.g. net nitrification is the balance of actual microbial nitrate production(gross nitrification)and microbial nitrate consumption via e.g.microbial nitrate immobilization and denitrification(Davidson et al. 1991).
However,Mediterranean shrubland ecosystems are still being severely understudied with respect to gross rates of N turnover and denitrification activity and the importance of fire as a potential driver for soil N cycling has largely been ignored.It is well known that fire increases mineral N concentrations in the uppermost mineral soil(Marion et al.1991), but,as there is still extremely little knowledge on postfire effects on gross rates of ammonification, nitrification,microbial immobilization and denitrifi-cation,it remains unknown to what extent postfire increases of inorganic N concentrations are caused by direct ash input or altered inorganic N production rates.
The goal of the present study was to investigate gross rates of soil N turnover(ammonification, nitrification,microbial immobilization of ammonium and nitrate as well as denitrification)at unburned and burned Mediterranean macchia shrublands. Furthermore,we aimed at the clarification of the importance of denitrification versus the other N turnover processes in the investigated ecosystem, i.e.if denitrification is insignificant as an N sink or not.
Material and methods
Site characteristics
The study site is located in Salento Penninsula, Southern Italy(18°23′17.34″E,40°18′5.70″N)at a distance of1km to the sea.The whole site area is completely flat and characterized by homogenous typical Mediterranean Macchia vegetation cover of 0.3–0.8m height.The dominating plant species are Erica australis,Rosmarinus officinalis,Pistacia lentis-cus and Myrtus communis.Mid of August2007, approximately half of the site was burned by a natural fire.
The soil is a shallow Rendzic Leptosol on sandy carbonatic bedrock.The height of the densely rooted,organic matter-rich Ah layer was 4.6±0.8cm across the site.At the bottom of the Ah layer there was either a direct transition to the weathered bedrock or a scarcely rooted B layer above the bedrock.The weathered but still compact bedrock was always found at a depth of20cm.The gravel content of both the A and B horizons was moderate (ca.10%).
Sampling design
End of January2008,three unburned and three burned plots of100m2across an area of approx. 2ha were randomly selected and sampled.The distance between burned and unburned plots was 30–50m.The litter layer amounted to663±58g dry mass m?2while the ash layer at the burned plots amounted to72±6g dry mass m?2.At the sampling time,there was a herbal layer covering approximately 30%of the soil at the burned parts of the site. Furthermore,resprouting of burned shrubs had begun at the sampling date.Sampling took place at every plot at seven40*40cm spots randomly selected across the plot.
First,the organic(unburned plots)or ash(burned plots)layer was quantitatively sampled and trans-ferred to plastic bags until weight determination and drying(24h at100°C)of subsamples.Subsequently, in the centre of every sampling spot,the Ah layer was sampled with three adjacent soil cores(4cm depth, 100cm3volume).Soil cores were sealed with pin-holed parafilm to facilitate gas exchange but to avoid water loss.
Soil cores were stored in cooling boxes and transferred to the laboratories of IMK-IFU in Garmisch-Partenkirchen,Germany,within48h after sampling.After arrival at IMK-IFU they were stored at4°C until further processing and analysis.All samples were processed within two weeks after sampling.One intact soil core of every sampling spot was used for the simultaneous measurement of N2O and N2fluxes.The second soil core was used for the determination of gross rates of microbial N turnover after compositing and sieving samples for single plots.Also the third soil core was composited at the plot level and sieved for analysis of extractable concentrations of inorganic N,dis-solved organic nitrogen(DON),dissolved organic carbon(DOC),microbial biomass C and N,and pH values.
Gross rates of ammonification,nitrification
and microbial N immobilization
Gross rates of ammonification,nitrification and microbial immobilization were determined using a 15N pool dilution technique described in more detail by Dannenmann et al.(2009).We decided to use a sieved soil technique,as the stone content of the soil hampered sufficient homogenous15N injection into intact soil cores.Three days before the start of the experiment,the still intact soil samples were pre-incubated at the in situ during sampling deter-mined soil temperature(10°C).Immediately before 15N application,soil was removed out of the cores and roots,gravel and other coarse materials were removed by carefully breaking the intact soil sample portions by hand prior to sieving(5mm mesh width).Soil samples were composited for single plots.Mechanical disruption of the soil was mini-mized as far as possible.Two subsamples(230g sieved soil each)were labelled with7ml30%15N-enriched KNO3solution(for determination of gross nitrification rates)or7ml30%15N-enriched (NH4)2SO4solution(for determination of gross ammonification rates),respectively(time t0).The subsamples were spread in a thin layer and then the 15N label solution was sprayed homogenously on the samples.The amount of added N corresponded to1μg N g?1sdw.While aliquots of180g of the subsamples were transferred into six250ml plastic bottles(Carl Roth GmbH,Karlsruhe,Germany)
(30g each),the residual soil was used for determi-nation of the gravimetric water content.The plastic bottles were incubated in the dark at10°C.At time t1(=t0+24h)and time t2(=t0+48h)soil in three of the bottles was extracted with1M KCl,respectively (Dannenmann et al.2006).Subsamples of the filtrate were passed through0.45μm syringe-filters and immediately frozen until colorimetrical measurement of NH4+and NO3-concentrations by a commercial laboratory(Dr.Janssen,Gillersheim,Germany).The diffusion method was used for trapping NH4+or NO3-as NH3on acid traps made of ashless paper filters(Brooks et al.1989).The14/15N-ratio of the N captured on the dried filter papers was analyzed using an elemental analyzer(EA1110, Carlo Erba Instruments,Milan,Italy)coupled to a mass spectrometer(MAT Delta Plus,Thermo Finnigan,Bremen,Germany).Gross ammonification and gross nitrification rates were calculated using the equations given by Kirkham and Bartholomew (1954).Microbial immobilization of NH4+was calculated by subtracting nitrification rates from NH4+consumption rates(Davidson et al.1992). This approach underestimates NH4+immobilization when there is heterotrophic nitrification(direct oxidation of organic substrate to NO3-).Overestima-tion of NH4+immobilization can occur by substrate-stimulation of NH4+consumption in the15NH4+ treatment,while the subtracted nitrification rate calculated from15NO3-pool dilution is not affected by substrate stimulation.Here,we tried to minimize experiment-inherent substrate stimulation by mini-mizing NH4+https://www.doczj.com/doc/0b12459681.html,bel application increased ambient NH4+pools by only36%and56%in soils of burned and unburned plots,respectively.Nitrate immobilization was calculated by subtracting deni-trification rates(see below)from NO3-consumption rates.
Physical and chemical soil parameters
For the determination of mineral N concentrations, 30g of unlabelled soil free of limestone and roots was extracted with1M KCl solution and analyzed for NH4+and NO3-concentrations as described above (see Dannenmann et al.2006).Soil pH values (0.01M CaCl)were measured with three subsamples of every plot by use of a combined electrode as described by Dannenmann et al.(2007).Denitrification:simultaneous measurement of N2 and N2O emissions from seven intact soil cores Dinitrogen and N2O emissions from intact soil cores were measured by use of the helium gas flow soil core method as described by Butterbach-Bahl et al. (2002)and Dannenmann et al.(2008).This method is based on the exchange of the soil and headspace atmospheres by a helium-oxygen atmosphere con-taining only25PPM N2and the subsequent simultaneous automated detection of N2O and N2 concentration changes in the headspace above the cores by use of an electron capture detector(ECD) for N2O and a pulse discharge helium ionization detector(PDHID)for N2(Fig.1).In order to facilitate the application of the method to shallow soils and in order to improve the spatial resolution of the measurements,we designed a new system for simultaneous measurement of N2and N2O from seven small soil cores.While the general setup of the system including the steering unit,automated flushing of soil cores and headspace,automated sampling and the detection technique and conditions for N2and N2O(see Fig.1)were the same as described by Butterbach-Bahl et al.(2002),two new incubation cuvettes were designed.The new incuba-tion cuvette facilitated the simultaneous flushing of seven soil cores(height4cm,100cm3volume each) via the porous porcellaine plates at the bottom of the soil cores,while the cuvette described by Butterbach-Bahl et al.(2002)contained only one soil core of20cm height and12.5cm diameter)(Fig.2). The soil cores are automatically pressed into the fittings sealed via O rings when closing the cuvette to ensure that He purge gas flow is taking place from bottom to top in the soil cores(Fig.2).Also with the new cuvette,the same huge constructive efforts were made to facilitate an extremely gastight system and hence avoid diffusion of atmospheric N2into the system(Butterbach-Bahl et al.2002), e.g.the cuvette had double sealings which were additionally purged with He(Fig.2),and He leakage tests were performed.The smaller size of the new cuvette compared to the version described by Butterbach-Bahl et al.(2002)allowed to further improve the gastightness of the system by placing the whole incubation cuvette including fittings of the gas tubings under water in a water bath.The water surrounding the cuvette is also used for the regula-
tion of the incubation temperature.Based on this setup,no significant increase in N 2concentrations in the cuvettes was found during 8h when the system was run with an empty cuvette.
Here,the soil cores (soil moisture 19or 21.4%sdw for burned or unburned soil samples;incuba-tion temperature:10°C for both treatments)were flushed for 72h to quantitatively remove N 2from the soil and headspace atmospheres.Subsequently,an artificial headspace atmosphere was created (80%He,20%O 2,25PPM N 2,400PPB N 2O)and the concentration change of N 2and N 2O in the two cuvettes was monitored automatically for 8h on hourly basis according to Butterbach-Bahl et al.(2002).Every sample air analysis was accompanied by 6automated calibration gas measurements at the gas chromatographs.For each treatment (burned/unburned),3measurements with 7soil cores were performed.Flux rates were calculated from the linear change in N 2and N 2O concentrations in the
headspace as described by Butterbach-Bahl et al.(2002).
After every measurement,soil water content and soil dry weight of the incubated soil were deter-mined.Denitrification was calculated as the sum of N 2O plus N 2fluxes and related to a soil dry weight basis.
Microbial biomass C and N
Microbial biomass C and N was determined by use of the chloroform fumigation-extraction technique (Brookes et al.1985).For this purpose,soil from seven soil cores was pooled at the plot level and sieved.Subsequently three subsamples of 30g were immediately extracted with 60ml 0.5M K 2SO 4,while three subsamples were fumigated with Chloroform vapour for 24h.Fumigated samples were extracted in a similar way like control samples.Total chemically bound nitrogen (TNb)and
total
Fig.1Schematic representation of the measuring system used to simultaneously quantify N 2and N 2O emissions from seven intact soil cores.PDHID:Pulse Discharge Helium Ionization Detector;ECD:Electron Capture Detector
organic Carbon (TOC)were analyzed by use of a chemoluminescence detector for TNb analysis coupled to the TOC analyzer (Dannenmann et al.2006).Correction factors (0.54for microbial biomass N and 0.379for microbial biomass C,(Brookes et al.1985;Vance et al.1987)were applied to the difference in TNb and TOC between paired untreated and fumigated subsamples to estimate microbial biomass C and N.TOC values of the extracts of unfumigated control samples are referred to as extractable DOC concentrations.
Statistics
Test for significant differences of the determined parameters between control and burning treatment were made by means of the Mann Whitney u-test using plots as statistical units (N =3).Also corre-lation analysis was performed using plot means from both burned and unburned treatments.All statistical analyses were performed with SPSS 10.0(SPSS Inc.,Chicago,USA)and Microcal Origin
7.0.
Fig.2Newly designed incubation vessel for simultaneous measurements of N 2and N 2O emissions from seven small intact soil cores (4cm height,100cm 3volume each)after purging with He/O.All soil cores are purged from bottom to top with He/O mixture.Double outside sealings are used which are additionally purged with He.Furthermore,the whole
incubation vessel is placed for purging and measuring under water in a water bath to finally reach gas tightness.After three days of purging,fully automated hourly measurements of N 2and N 2O concentrations in the headspace were conducted over 8h.The system contains two vessels
Results Soil parameters
Half a year after burning,the remaining ash and charcoal layer at the burned plots was one order magnitude smaller compared to the organic layer at the control plots (Table 1).Mineral soil pH was 7.5and slightly (7.53versus 7.45)but significantly higher at the burned plots (Table 1).Soil moisture content in the mineral soil was significantly lower at the burned plots as compared to the control plots.Both microbial biomass C (Table 1)and N (Fig.3)were significantly lower in the Ah horizon of the burned plots.However,no difference in the microbial C:N ratio was found between burned and unburned plots.In contrast to microbial biomass,extractable DOC was found to be significantly higher at the burned plots (Table 1).
Gross rates of N turnover
Gross ammonification was nearly four times higher at burned plots than at unburned plots (Fig.3).However,extractable soil NH 4+concentrations were approximately only 50%higher.Microbial NH 4+immobilization was threefold higher at the burned plots than at the control plots (Fig.3).Gross nitrification was more than twofold larger at burned plots than at control plots (Fig.3).Extractable soil NO 3-concentrations in the mineral soil of the burned plots were thirteen times the concentrations of soil NO 3-in the mineral soil horizon of the control plots (Fig.3).At burned plots,the amounts of extracted soil NO 3--N equaled the amounts of extracted soil NH 4+-N concentrations.In contrast,soil NO 3-con-centrations were considerably lower than soil NH 4+concentrations at unburned control plots.Microbial NO 3-immobilization was not significantly
different
Fig.3N turnover [mg N kg ?1sdw day ?1]and N pools [mg N kg ?1sdw]in the Ah layer of unburned and burned plots.SON:soil organic nitrogen.A:gross ammonification;B:gross nitrification;C:microbial NH 4+immobilization;D:microbial NO 3-immobilization;E:N 2O flux;F:N 2flux.Different indices indicate significant differences between control and burned plots.Errors represent standard errors of the mean
Table 1Soil parameters litter/ash mass parameters are given for the Ah layer.Errors represent standard errors of the mean calculated from N =3plots.DOC:dissolved organic carbon.MBC:microbial biomass carbon;MBN:microbial biomass nitrogen.Different indices indicate significant differences between burned and unburned plots litter/ash mass
[g m ?2]
soil moisture [%sdw)pH
DOC
[mg C kg ?1sdw]MBC
[mg C kg ?1sdw]MBC/MBN [ratio]control 617±86a 21.4±0.5a 7.45±0.02a 134±3a 1844±112a 15.3±0.2burned
72±6b
19.0±0.4b
7.53±0.03b
160±14b
1380±143b
15.9±1.3
1Soil parameters for control and burned plots.Except for litter/ash mass parameters are given for the Ah layer.Errors represent standard errors of the mean calculated from N =3plots.DOC:dissolved organic carbon.MBC:microbial
biomass carbon;MBN:microbial biomass nitrogen.Different indices indicate significant differences between burned and unburned plots
between control and burned plots and overall several fold lower than microbial NH 4+immobilization.Relative N retention,i. e.(microbial NH 4+immobilization +microbial NO 3-immobilization)/(gross ammonification +gross nitrification),was significantly lower at the burned plots than at the control plots (Table 2).This was caused in particular by an increase in gross nitrification which was not outbalanced by a concomitant increase in microbial NO 3-immobilization.
Soil N 2O and N 2measurements revealed that dinitrogen was the dominant end product of denitri-fication both at control and burned plots (Fig.3).However,N 2emissions were more than one magni-tude larger at unburned control plots (94±2μg N kg -1sdw day ?1)than at burned plots (4±2μg N kg ?1sdw day ?1).At the control plots,there was significant net uptake of N 2O of approx.1μg N kg ?1sdw day ?1,while at the burned plots N 2O fluxes were not significantly different from zero.At control plots,N 2O uptake was approximately two orders of magni-tude smaller than N 2emission.Due to the dominance of N 2as the end product,denitrification rates equalled N 2emissions.For burned plots,denitrification amounted to less than 1%compared to the other processes of N turnover.However,for the unburned plot denitrification was a significant sink process for microbial N cycling.Here,denitrification was on average 16%of ammonification,20%of nitrification and 98%of microbial NO 3-immobilization at the unburned control plots (Table 2).Correlation analyses
Soil microbial biomass N was negatively correlated with gross ammonification (R =?0.91,p =0.01)and gross nitrification (R =?0.83,p =0.04)and net soil-atmosphere N 2O flux (R =?0.84,p =0.04)(i.e.positively correlated with net N 2O uptake rate)but positively correlated with soil water content (R =0.93,
p =0.006),and N 2emission rate (R =0.94,p =0.005).
Gross ammonification was positively correlated with independently determined soil NH 4+concentrations of unlabelled soil (R =0.885,p =0.02)as well as gross nitrification with soil NO 3-concentrations (R =0.98,p <0.001).
Discussion
Fire effects on gross rates of N turnover
Fire has been shown to potentially alter a wide range of physical,biological and chemical soil parameters like soil organic matter quanity and quality (variable effects of fire across soil horizons),pH values (increase),nutrient availability (increase),and soil microbial biomass (decrease)(Marion et al.1991;Castaldi and Aragosa 2002;Certini 2005;Knicker 2007).The recovery of these effects is mainly depend-ing on plant recolonization (Certini 2005).However,little information is available on postfire effects on actual gross rates of N turnover in Mediterranean soils.In this study we show that 6months after burning,when vegetation re-growth already had started,gross ammonification and gross nitrification were considerably larger in the Ah horizon soil of the burned plots than in soil of unburned plots.As microbial immobilization,in particular of NO 3-,could not compensate for the increase in inorganic N production,inorganic N concentrations were higher and relative microbial nitrogen retention were smaller at burned plots.Since soil moisture values at burned plots were significantly lower as compared to un-burned plots (Table 1),the stimulation of microbial N turnover must have been due to the increased availability of organic substrates and mineral N due to burning of the vegetation (Andersson et al.2004a ,b ;Knicker 2007).This interpretation is supported by our measurements on higher DOC concentrations in
retention:(microbial NH 4+
immobilization +microbial NO 3-immobilization)/(gross ammonification +gross nitrification).Errors represent standard errors of the mean Relative N retention
Denitrification/ammonification Denitrification/nitrification Denitrification/NO 3-immobilization control 0.96±0.11a 0.16±0.02a 0.20±0.02a 0.98±0.65a burned
0.66±0.12b
0.002±0.001b
0.003±0.002b
0.002±0.001b
Table 2Relative importance of microbial immobilization and denitrification versus inorganic N production.Relative N
retention:(microbial NH 4
+immobilization +microbial NO 3-immobilization)/(gross ammonification +gross nitrification).Errors represent standard errors of the mean
the mineral soils at burned plots(Table1).Our findings on higher inorganic N concentrations in the uppermost mineral soil horizon are in agreement with earlier fire studies in Mediterranean shrublands (Marion et al.1991;Castaldi and Aragosa2002). Besides increased N turnover and reduced microbial immobilization also lower plant competition for mineral N at burned plots may have additionally contributed to the increase in mineral N.
It has been assumed that net N ammonification and nitrification rates in Mediterranean shrublands are low because of the quality of the typical sclerophyllus leaf and because of leaching of allelopathic compounds from plants(Scalbert1991;Gallardo and Merino 1992;Castaldi et al.2009).As fire may destroy allelopathic compounds,the increased gross rates of N turnover at the burned plots observed here,could also be caused by a release of inhibiting plant effects on microbial N turnover(Castaldi and Aragosa2002).
Only little studies investigated fire effects on gross rates of soil N turnover while,to our knowledge,there is no study conducted in a comparable ecosystem like investigated here.Bastias et al.(2006)reported minor but significant reduction of gross ammonification by 16%and gross nitrification by12%three weeks after a fire in the soil of a wet sclerophyll forest of Australia,subjected to high frequencies of prescribed burning.LeDuc and Rothstein(2007)did not observe significant effects of wildfire neither on gross pro-duction nor on immobilization of both ammonium and nitrate3–6years after burning of a jack pine forest in Michigan,USA.Anderson and Poth(1998) explained increased NH4+concentrations in Brazilian cerrado soils within the first2months after experi-mental fires by a stimulation of gross ammonification while gross nitrification was suppressed by burning. In contrast,addition of wildfire-produced charcoal to soil sampled in ponderosa pine forests of Montana, USA,strongly promoted gross nitrification,probably due to absorption of phenolic compounds which inhibited gross nitrification(DeLuca et al.2006).It remains unclear whether such variable responses of gross N turnover to fire are caused by variable responses of N cycling across ecosystems,different fire intensities or-frequencies and time elapsed between the burning and sampling events,or simply result from limited temporal resolution,which is characterizing almost all studies on gross rates of N turnover.In our study,the microbial biomass C and N pools were positively correlated with denitrification, i.e.smaller at burned plots but negatively correlated with gross rates of ammonification and nitrification. Microbial biomass is responsible for both production and consumption of inorganic N.Furthermore,it can serve as a substrate for N ammonification itself following microbial dieback due to drought events (Borken and Matzner2008).Therefore,the relation-ships between microbial biomass and rates of N turnover may be variable in time.The observed reduction in soil microbial biomass at the burned plots may be explained by generally more extreme environmental conditions at the burned plots,as the missing shadowing effect of vegetation as well as the dark ash may have lead to higher temperature fluctuations and quicker drying of the soil at the burned plots.
However,lower microbial biomass may also be interpreted by retarded long-term recovery of soil microbes after fire(Castaldi and Aragosa2002),e.g. in association with a decreased rhizodeposition of labile C compounds by roots.However,larger DOC concentrations at the burned plots(Table1)do not support the latter hypothesis.Furthermore,the similar microbial C:N ratios in burned and unburned soil (Table1)do not indicate a fire-induced shift in microbial community composition,i.e.a promotion of fungi with a higher C:N ratio at the expense of bacteria with a lower C:N ratio.Still,there could have been an altered abundance of functional microbial groups which was not reflected in the microbial C:N ratio.
Despite both gross rates of ammonification and nitrification as well as soil NO3-concentrations were higher in soil of burned plots,denitrification rates were considerably larger at unburned control plots(Fig.3).This may—analoguously like fire effects on microbial biomass—be explained by significantly decreased soil water content at burned plots(Table1),given that denitrification is a predominantly anaerobic process(Conrad1996). However,these differences in soil moisture were low,i.e.soil moisture was approximately10%lower at burned burned plots than at control plots only (Table1).Furthermore,soil moisture was at compa-rably low level both at control and burned plots (21.4and19.0%of soil dry mass).Lower denitrifi-cation at burned plots could be also a consequence of reduced rhizodeposition of labile C compounds,
however this was not reflected in extractable DOC concentrations,which were higher in soil of burned plots(Table1).One may speculate that either oxygen-depleted microsites,probably in the rhizosphere,and thus less pronounced at burned plots,or aerobic pathways of denitrification,e.g.by heterotrophic nitrifiers(Robertson et al.1989,1995; Wrage et al.2001)may have contributed to the significant N2emissions observed here under com-parably dry soil conditions.In dry sandy soil of a coastal Mediterranean pine forest,Rosenkranz et al. (2006)observed continuous and significant N2O uptake rates under field conditions and also consid-ered aerobic denitrification to be the cause for N2O consumption.Castaldi and Aragosa(2002)observed lower denitrification enzyme activity in Mediterra-nean shrubland in Italy exposed to high fire intensity than in shrublands exposed to low fire intensity and untreated control plots during four sampling dates in the first year after the burning event.The observed reduction in denitrification activity at our burned sites affected by high intensity natural fire is thus in agreement with Castaldi and Aragosa(2002)and our observation of a reduction in microbial biomass may further support this interpretation.
It is worthwhile to note that despite comparably low soil moisture,at unburned plots denitrification accounted for significant proportions of soil NO3-produced by gross nitrification(Table2).Hence, microbial NO3-immobilization as calculated by 15NO
3
-consumption under the assumption that gaseous N loss via denitrification is negligible (Davidson et al.1992),would have severely over-estimated microbial NO3-immobilization by approx. 50%for the unburned plots(Fig.3,Table2).The assumption of zero denitrification is widely used in 15N pool dilution studies(Stark2000;Murphy et al. 2003;Booth et al.2005)and our results on the importance of denitrification as a sink for nitrate implies that denitrification should be accounted for when calculating NO3-immobilization from15NO3-consumption.
This study represents one of the scarce snapshots on postfire gross N turnover currently available.In view of the potentially high temporal dynamics of all determined rates of N turnover,it does not allow to generalize how fire alters gross rates of N turnover.In view of the significant findings on alterations of microbial N cycling by fire,it emphasizes the necessity for comprehensive,high resolution studies on fire effects on gross N turnover,soil N retention and N loss along gaseous and hydrological pathways in fire-prone Mediterranean ecosystems.
Acknowledgements Funding of this work by the European Union(NitroEurope IP)and the German Research Foundation (DFG,contract number DA1217/2-1)is gratefully acknowl-edged.We are indebted to Francesa Cotrufo,Simona Castaldi and Andrea Venturi for logistic support,help in the site identification and soil sampling.Furthermore we wish to thank Elisabeth Zumbusch for help with the laboratory work and Rudi Meyer for technical support during IRMS analyses. References
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随着国家政府对环境保护的重视以及近几年连续出台的大气污染防治攻坚战文件来看，各地环保局对当地企业强制要求并执行燃煤锅炉更换为低氮燃气锅炉，普通的燃气锅炉实施低氮改造。普通的燃气锅炉尾气排放的有害颗粒物，例如氮氧化物、一氧化碳等，成为大气污染的罪魁祸首，因此锅炉的低氮改造将会是一些生产企业及供暖单位迫切面临的任务。那么，大家只知道锅炉需要改造，但是，燃气锅炉超低氮排放改造的原理是什么，需要什么技术能实现超低氮排放呢？下面，由中鼎锅炉专业技术人员给大家简单介绍一下。 1、氮氧化物危害 氮氧化物即一氧化氮、二氧化氮等气体，为高温条件下，空气中的氮气和氧气化合反应生成。氮氧化物与空气中的水结合最终会转化成硝酸和硝酸盐，硝酸是酸雨的成因之一;它与其他污染物在一定条件下能产生光化学烟雾污染。酸雨危害是多方面的，包括对人体健康、生态系统和建筑设施都有直接和潜在的危害。酸雨可使儿童免疫功能下降，慢性咽炎、支气管哮喘发病率增加，同时可使老人眼部、呼吸道患病率增加。酸雨还可使农作物大幅度减产，特别是小麦，在酸雨影响下，可减产13%至34%。大豆、蔬菜也容易受酸雨危害，导致蛋白质含量和产量下降。酸雨对森林和其他植物危害也较大，常使森林和其他植物叶子枯黄、病虫害加重，最终造成大面积死亡。 2、氮氧化物排放标准 我们知道用燃气锅炉替代燃煤锅炉能够大大降低污染，普通的燃气锅炉氮氧化物排放高于30毫克，这意味着大部分普通的燃气锅炉都达不到30mg以下，除非配有低氮燃烧机，但是使用低氮燃烧机的锅炉本身也是需要有特殊的要求的，那就是对锅炉炉膛尺寸需要加大，中鼎锅炉最新生产的低氮燃气锅炉专门针对环保政策要求的NOX排放30mg以下，且配置超低氮燃烧器，能安全、稳定、高效地运行，每一台出厂的低氮锅炉均能达到低氮排放达标。
燃气锅炉低氮改造方案 燃气锅炉低氮排放成为了新时代的新要求，为了保护环境，保证国人健康，燃气锅炉低氮排放势在必行，使命必达。 远大锅炉紧跟时代步伐，积极响应国家政策，时刻不忘研发新产品，不忘为用户谋福利。 远大低氮燃气锅炉：FGR烟气再循环低氮燃烧技术；国外原装进口低氮燃烧器； 压力、水位多重安全防护；PLC触摸屏智能化控制技术。 远大锅炉低氮技术研发历程： 保护环境，节能减排，绿色生产，可持续发展是每一个企业的使命，远大锅炉每年按销售额的5%提取新产品研发费用，专注低氮、节能锅炉技术的研发。 2015年，远大锅炉与芬兰奥林、德国欧科、意大利利雅路、意科法兰等积极合作，通过使用超低NOx燃烧器，增加烟气外循环设计，实现氮氧化物＜30mg/m 3排放标准。 NOx成分分析及产生机理： 在燃烧过程中所产生的氮的氧化物主要为NO和NO2，通常把这两种氮氧化物通称为氮氧化物NOx。大量实验结果表明，燃烧装置排放的氮氧化物主要为NO，平均约占95%，而NO2仅占5%左右。
燃料燃烧过程生成的NOx，按其形成分类，可分为三种： 1、热力型NOx （Thermal NOx），它是空气中的氮气在高温下氧化而生成的NOx； 2、快速型NOx（Prompt NOx），它是燃烧时空气中的氮和燃料中的碳氢离子团如CH等反应生成的NOx； 3、燃料型NOx（Fuel NOx），它是燃料中含有的氮化合物在燃烧过程中热分解而又接着氧化而生成的NOx； 燃烧时所形成NO可以与含氮原子中间产物反应使NO还原成NO2。实际上除了这些反应外，NO 还可以与各种含氮化合物生成NO2。在实际燃烧装置中反应达到化学平衡时，[NO2]/[NO]比例很小，即NO转变为NO2很少，可以忽略。 降低NOx的燃烧技术： NOx是由燃烧产生的，而燃烧方法和燃烧条件对NOx的生成有较大影响，因此可以通过改进燃烧技术来降低NOx，其主要途径如下： 1选用N含量较低的燃料，包括燃料脱氮和转变成低氮燃料； 2降低空气过剩系数，组织过浓燃烧，来降低燃料周围氧的浓度； 3在过剩空气少的情况下，降低温度峰值以减少“热反应NO”； 4在氧浓度较低情况下，增加可燃物在火焰前峰和反应区中停留的时间。 减少NOx的形成和排放通常运用的具体方法为：分级燃烧、再燃烧法、低氧燃烧、浓淡偏差燃烧和烟气再循环等。 目前低氮改造方案 1、FGR技术： 即自身再循环燃烧器，对于天燃气锅炉来说目前主流成熟低氮排放技术就是分级燃烧加烟气再循环法即FGR技术，
1.重度胃食管反流病的治疗应采用 A A．质子泵抑制剂与促动力药联用 B．H2受体拮抗剂与促动力药联用 C．质子泵抑制剂与粘膜保护药联用 D．促动力药与H2受体拮抗剂联用 E．促动力药、H2受体拮抗剂及粘膜保护药联用2.胃食管反流病治疗至少应维持用药B A．3个月 B．6个月 C．1年 D．1年半 E．2年 3．有关非甾体抗炎药哪项是正确的C A．诱发消化性溃疡与剂量和疗程无关 B．长期服用者约50％有消化性溃疡 C．可穿透上皮细胞而破坏粘膜屏障 D．为弱酸性水溶性药物 E．可促进促胃液素分泌致消化性溃疡 4．抗幽门螺杆菌的根除方案哪项不正确E A．质子泵抑制剂＋克拉霉素＋阿莫西林 B．质子泵抑制剂＋克拉霉素＋甲硝唑 C．质子泵抑制剂＋阿莫西林＋甲硝唑 D．胶体铋＋阿莫西林＋甲硝唑 E．胶体铋＋质子泵抑制剂＋甲硝唑
5．消化性溃疡治疗中不属于抑制胃酸分泌的药物是A A．氢氧化铝 B．普鲁本辛（澳丙胺太林) C．丙谷胺 D．雷尼替丁 E．奥美拉唑 6．降低胃酸最有效的药物是D A．H2受体拮抗剂 B．抗胆碱药物 C．促胃液素受体拮抗剂 D．质子泵抑制剂 E．抗酸剂 7．轻、中型溃疡性结肠炎治疗的首选是B A．肾上腺皮质激素 B．水杨酸偶氮磺胺吡啶 C．免疫抑制剂 D．抗生素 E．双歧杆菌制剂 8．治疗重型溃疡性结肠炎应首选C A．水杨酸偶氮磺胺吡啶 B．免疫抑制剂 C．大剂量肾上腺糖皮质激素 D．手术治疗
E．大剂量抗生素 9．治疗轻中度溃疡性结肠炎的主要口服药物有C A．泼尼松 B．环磷酰胺 C．SASP D．甲硝唑 E．抗生素 10．下列哪项不是SASP的副作用E A．恶心、呕吐 B．食欲不振 C．自身免疫性溶血 D．粒细胞减少 E．不可逆性男性不育 11．柳氮磺胺吡啶治疗溃疡性结肠炎的机制是B A．降低肠腔酸度，促进溃疡愈合 B．抑制炎症反应 C．促进肠上皮细胞再生 D．抑制细菌生长 E．免疫抑制作用 12．服用硫酸镁导致的腹泻从发病机制上分类应属于D A．胃肠运动功能异常性腹泻 B．分泌性腹泻 C．渗出性腹泻
燃气锅炉低氮改造施工方案 项目名称：xxx燃气锅炉低氮改造工程编制单位： 编制时间：2016年10月13日
第一章工程概况 1.1工程简介 1.1.1本工程为xxx燃气锅炉低氮改造工程。首先需采购新锅炉，拆除原有锅炉、烟囱、电气设备、部分水暖和燃气管道等；然后安装新锅炉，管道、烟囱重新布置。 1.1.2本项目施工范围 1.锅炉房内原有锅炉、采暖及燃气管线、电气设备、烟囱的拆除； 2.锅炉房设备管道安装，其中有锅炉、管道等安装； 3.电气工程，包括电气动力和电气照明； 4.烟囱安装； 5.燃气工程。 第二章施工准备 在工程正式开工前，需现场勘查，确认实际施工条件和工程量，以利于施工的计划的安排和顺利进行。另一方面应该积极设备供货厂家，了解设备技术参数、基础做法、安装尺寸等，为施工做好充足准备。 2.1临时设施 根据现场实际情况，由甲方指定地点作为临时设施存放和现场预制场地。 2.2临时用电 临时用电由甲方指定的地点挂表接入，现场用电包括生产用电和生活用电，施工用电主要为电焊机、切割机、磨光机、照明设施等。临时用电采用三级配电，两级保护，保证用电安全。 2.3临时用水 临时用水从甲方指定地点接入。主要用于生活用水和施工用水，施工用水主要为土建砌筑用水和混凝土基础养护、打压和冲洗用水等。 2.4生产准备
重点完成工作场地布置、临时水源、临时电源、人员组织及进场、机械设备组织及进场计划、工程材料准备及进场计划、图纸会审及设计交底、现场纵横基准线与标高基准点复核等。 2.5技术准备 施工前要认真研究和熟悉本工程设计文件并进行现场核实，组织有关人员学习设计文件，图纸及其它有关资料，使施工人员明确设计者的设计意图，熟悉设计图纸的细节，对设计文件和图纸进行现场校对。 2.6材料准备 针对本工程的施工内容，在开工之前对工程所需锅炉设备、电气、管道、烟囱等制定采购计划，积极联系资质优良的材料厂家并提出详细的进场计划，严格执行验收与检测程序，确保原材料的质量。 第三章施工进度安排 3.1施工部署 本工程为低氮改造工程，首先得安排设备采购订货，尤其是锅炉的采购，预计需要四十天； 其次，组织施工进场，在甲方指定位置引入水电，安排临时生活设施和现场预制加工场地； 第三，拆除需改造设备，锅炉、管路、线路、烟囱等； 第四，根据设计文件和设备参数复核设备基础位置标高，规划管线安装路由、力求布局科学合理； 第五，锅炉、烟囱、电气等新购设备的进场验收； 第六，锅炉、烟囱、管道、仪器仪表、燃气管道设备及电气管线设备安装； 第七，管道系统水压试验、冲洗、防腐保温； 第八，系统冷态调试； 第九，锅炉点火试运行；
柳氮磺吡啶使用注意事项 本品口服后，少部分药物在胃和上部肠道吸收。大部分药物进入远端小肠和结肠，在肠微生物作用下分解成5-氨基水杨酸和磺胺吡啶。磺胺吡啶在药物分子中主要起载体作用，在肠道碱性条件下，微生物使重氮键破裂而释出有作用的药物。5-氨基水杨酸有抗炎和免疫抑制作用，能抑制溃疡性结肠炎的急性发作并延长其缓解期。治疗溃疡性结肠炎用肠溶片，口服，成人常用量：初剂量为一日2-3g（8-12片），分3-4次口服，无明显不适，可渐增至一日4-6g（6-24片），待肠病症状缓解后逐渐减量至维持量，一日1.5g-2g（6-8片）。 不良反应：血清磺胺吡啶及其代谢产物的浓度（20-40μg/ml）与毒性有关。浓度超过50μg/ml时具毒性，故应减少剂量，避免毒性反应。 1.过敏反应较为常见，可表现为药疹，严重者可发生渗出性多形红斑、剥脱性 皮炎和大疱表皮松解萎缩性皮炎等；也有表现为光敏反应、药物热、关节及肌肉疼痛、发热等血清病样反应。 2.中性粒细胞减少或缺乏症、血小板减少症及再生障碍性贫血。患者可表现为 咽痛、发热、苍白和出血倾向。 3.溶血性贫血及血红蛋白尿。缺乏葡萄糖6-磷酸脱氢酶患者使用后易发生，在 新生儿和小儿中较成人为多见。 4.高胆红素血症和新生儿核黄疸。由于可与胆红素竞争蛋白结合部位，致游离 胆红素增高。新生儿肝功能不完善，故较易发生高胆红素血症和新生儿黄疸。 偶见发生核黄疸。 5.肝脏损害，可发生黄疸、肝功能减退，严重者可发生急性肝坏死。 6.肾脏损害，可发生结晶尿、血尿和管型尿。偶有患者发生间质性肾炎或肾管 坏死的严重不良反应。 7.恶心、呕吐、胃纳减退、腹泻、头痛、乏力等。一般症状轻微，不影响继续 用药。偶有患者发生艰难梭菌肠炎，此时需停药。 8.甲状腺肿大及功能减退偶有发生。 9.中枢神经系统毒性反应偶可发生，表现为精神错乱、定向力障碍、幻觉、欣 快感或抑郁感。一旦出现均需立即停药。 10.罕见有胰腺炎、男性精子减少或不育症。 注意事项： 1.缺乏葡萄糖-6-磷酸脱氢酶、肝功能损害、肾功能损害患者、血卟啉症、血小 板、粒细胞减少、血紫质症、肠道或尿路阻塞患者应慎用。 2.应用磺胺药期间多饮水，保持高尿流量，以防结晶尿的发生，必要时亦可服 碱化尿液的药物。如应用本品疗程长，剂量大时宜同服碳酸氢钠并多饮水，以防止此不良反应。治疗中至少每周检查尿常规2-3次，如发现结晶尿或血尿时给予碳酸氢钠及饮用大量水，直至结晶尿和血药消失。失水、休克和老年患者应用本品易致肾损害，应慎用或避免应用本品。 3.对呋塞米、砜类、噻嗪类利尿药、磺脲类、碳酸酐酶抑制药及其他磺胺类药 物呈过敏的患者，对本品亦会过敏。 4.治疗中须注意检查以下几项： （1）全血象检查，对接受较长疗程的患者尤为重要。 （2）直肠镜与乙状结肠镜检查，观察用药效果及调整剂量。 （3）治疗中定期尿液检查（每2-3日查尿常规一次）以发现长疗程或高剂量治
燃气锅炉低氮改造施工方案
项目名称：xxx燃气锅炉低氮改造工程 编制单位： 编制时间：2016年10月13日 第一章工程概况 1.1工程简介 1.1.1本工程为xxx燃气锅炉低氮改造工程。首先需采购新锅炉，拆除原有锅炉、烟囱、电气设备、部分水暖和燃气管道等；然后安装新锅炉，管道、烟囱重新布置。 1.1.2本项目施工范围 1.锅炉房内原有锅炉、采暖及燃气管线、电气设备、烟囱的拆除； 2.锅炉房设备管道安装，其中有锅炉、管道等安装； 3.电气工程，包括电气动力和电气照明； 4.烟囱安装； 5.燃气工程。 第二章施工准备 在工程正式开工前，需现场勘查，确认实际施工条件和工程量，以利于施工的计划的安排和顺利进行。另一方面应该积极设备供货厂家，了解设备技术参数、基础做法、安装尺寸等，为施工做好充足准备。 2.1临时设施 根据现场实际情况，由甲方指定地点作为临时设施存放和现场预制场地。
2.2临时用电 临时用电由甲方指定的地点挂表接入，现场用电包括生产用电和生活用电，施工用电主要为电焊机、切割机、磨光机、照明设施等。临时用电采用三级配电，两级保护，保证用电安全。 2.3临时用水 临时用水从甲方指定地点接入。主要用于生活用水和施工用水，施工用水主要为土建砌筑用水和混凝土基础养护、打压和冲洗用水等。 2.4生产准备 重点完成工作场地布置、临时水源、临时电源、人员组织及进场、机械设备组织及进场计划、工程材料准备及进场计划、图纸会审及设计交底、现场纵横基准线与标高基准点复核等。 2.5技术准备 施工前要认真研究和熟悉本工程设计文件并进行现场核实，组织有关人员学习设计文件，图纸及其它有关资料，使施工人员明确设计者的设计意图，熟悉设计图纸的细节，对设计文件和图纸进行现场校对。 2.6材料准备 针对本工程的施工内容，在开工之前对工程所需锅炉设备、电气、管道、烟囱等制定采购计划，积极联系资质优良的材料厂家并提出详细的进场计划，严格执行验收与检测程序，确保原材料的质量。 第三章施工进度安排 3.1施工部署 本工程为低氮改造工程，首先得安排设备采购订货，尤其是锅炉的采购，预计需要四十天； 其次，组织施工进场，在甲方指定位置引入水电，安排临时生活设施和现场预制加工场地；
化学预防在AOM/DSS模型基础研究中的启示 虽然利用AOM/DSS模型进行化学预防研究的报道数量是十分有限，但是最近和刚出现的研究表明：炎症相关的结肠癌被认为是一种可预防的疾病。到目前为止的基础研究支持用AOM/DSS诱导的小鼠模型作为一个高度相关的系统，而且这种模型在体内化学预防性干预研究中是有意义的。 下面几个部分是概述各种合成和天然膳食成分抑制AOM/DSS诱导肿瘤形成的能力。 环氧合酶（COX-2）抑制剂 在基础研究和临床研究中COX-2对散发性大肠肿瘤发展过程中的明显促进作用已经非常明确，但是抗炎物质如5-氨基水杨酸（5-ASA）对炎症相关性大肠癌的影响仍然存在争议。5-ASA及其衍生物对大肠肿瘤形成的影响已经在AOM/DSS小鼠模型中得到评估。Grimm et al利用低剂量（100mg/kg）和高剂量（300mg/kg）的5-ASA作用于AOM/DSS小鼠模型，研究其化学预防的效果。在这项研究中，小鼠经单次腹腔注射AOM（8mg/kg）后予以2个循环的DSS处理。 同样，给予另一种5-ASA衍生物，即用水杨酸偶氮磺胺吡啶处理AOM/DSS 小鼠，并与与对照组相比，高度异常增生区域的数量减少了20%。在这项研究中仅评估单剂量注射水杨酸偶氮磺胺吡啶后的效果，但是没有评估这种剂量对病变和炎症的形态学亚型的影响。Kohno et al研究报道称在该疾病发生过程中的发展阶段给予水杨酸偶氮磺胺吡啶烟处理，药物对大肠癌抑制效果相对弱些。这种不一致可能是因为实验计划和小鼠品系方面存在着差异。 Kohno et al也报道了用胆烷酸（UDCA）进行处理小鼠，结果抑制AOM/DSS诱导的大肠癌,也没有引起任何有害的影响。 Clapper et al做了一项研究关于评估5-ASA在模型中抑制炎症相关性大肠肿瘤的能力。研究结果表明长期暴露于5-ASA能够减轻炎症相关性大肠癌的损伤。尽管5-ASA大部分有利的影响都归因于它对抑制环氧合酶和前列素H合酶的能力，但是在这项研究中用AOM/DSS诱导的结肠癌模型对照组小鼠与给予5-ASA 处理该模型的小鼠相进行比较，两组的COX-2（基质细胞、上皮细胞）表达水平没有明显差异，该研究结果提示5-ASA的化学预防活性与COX-2表达水平没有关系。实际上，在先前研究中已经表明5-ASA能抑制缺乏COX-2的DLD1结肠癌细胞增值。 Weber等人研究表明5-ASA具有抑制NF-KB活性的能力。NF-KB与靶基因结合力下降会减少一些因子的表达，如促炎性因子、粘附分子、生长因子、炎症介质及抗凋亡基因。5-ASA 衍生物2-14，即一种新的5-ASA衍生物，该衍生物抑制结肠癌细胞增殖的作用是5-ASA的10倍。增殖的细胞核抗原（PCNA）染色证实2-14抗增殖的效果。通过对比，用2-14处理的正常小鼠的结肠黏膜在PCNA染色下并没有明显的变化，从而证实这种化合物基本上不会影响正常结肠
龙源期刊网 https://www.doczj.com/doc/0b12459681.html, 思维导图在元素化合物复习中的应用 作者：曾维彭 来源：《年轻人·中旬刊》2019年第09期 摘要：元素化合物知识较多，且物质之间联系较复杂，容量很大，是高三复习的难点之一。笔者通过引入思维导图，研究如何把元素化合物知识显得直观形象，把学生的学习误区变成学习兴趣，解决高三复习的难点。 关键词：思维导图;元素化合物;复习 中圖分类号：G633.8 文献标志码：A 文章编号：1672-3872（2019）20-0212-01 元素化合物知识是高考中必考的知识点之一，题目的设置一般会以元素化合物知识作为载体来考试学生对其掌握程度。但是学生在这一章节的掌握存在很多误区。（1）对知识点掌握不牢固;（2）对元素化合物间的物质变化不是很熟悉;（3）对知识的迁移不是很到位。元素化合物知识太多，学生在记忆的时候只是独立的把这些知识机械地记忆，没有找出他们之间的联系。 1 思维导图概述 思维导图又叫心智导图，是表达发散性思维的有效图形思维工具，简单却又很有效，是一种革命性的思维工具。思维导图自20世纪80年代思维导图传入中国。最初是用来帮助“学习困难学生”克服学习障碍的，但后来主要被工商界（特别是企业培训领域）用来提升个人及组织的学习效能及创新思维能力。它的优点是给你一个支撑点让你凭着想象力和现有的知识去发散，把用不同的符号不同的颜色的线条去把想到的知识以及知识间的联系画在纸上，更直观的让学生了解自己的知识缺陷，弥补不足，也能让教师去发现该学生在思维上不足，给予必要的指导。笔者尝试着利用思维导图作为工具，引导学生将元素化合物的知识建构起来。 2 元素化合物的复习 思维导图呈现一个放射性的思维表达过程，学生可以凭借思维导图发散思维，理清思维脉络。在绘制思维导图的过程中能帮助学生反思学习过程和认知结构，巩固复习知识。 2.1 课前准备 知识储备是画思维导图的基础，要是学生连最基本的化学知识也不记得，那么在建构学习中遇到的障碍会比较大。为了突破这个障碍，笔者会预先几天布置学生将有关的内容利用课余时间进行复习，然后将复习的内容画成思维导图。
知识脉络图 走 进 化 学 世 畀第一单元走进化学世界 组戚■（物质都是由元素组成的）?…一…一' ------- ..结构（分子、原子、离子及其内部结构）畅赏觥诡「娄花:谨＜性质（物理性质，化学性质〉 化学研究的对 研究化学的重要逸径是科学探究*而其重要手段是化学实验 化学实验 基本操作 变化规律 化学学习的特点是关注 化的过程及其现象“ 物理变化 化学变化T匕合、分解、置换、复分解 f提出间题 诜计实验方案，确定起歩骤 分析与讨论? 结论 I问题及建议 观察 描述和记录 「交徹 I体验 第二单元我们周围的空气 知识脉络图 ｝本质区别 C认识常用的九种仪器（名称、实物、示盍图，用途及其注育專项）药品 的取用规则（三不匱则、节约原则、剩余药品处理O） r块状固触锻子》 氮气詡）」约占空气总体积的73%。无色、无味、气体。化学性质不活徴，一般巩F他J ［不可燃，也不助燃?用作保护气焊接\灯泡、食品等〉° 稀有气体（He Nev Ar等〉;占6 9毬。狼不活激作保护气,通电发不同颜色光。 二氧化碳（CO?）:占0.03% o详见第六单元* 其他气体和杂匮：占0.03% ■, f物理性质：无色、 化学性质 （比较活』 泼，具有、氧 化性，是常 用的氧化剂） 无味、气体，宪度比空气略大，不易溶于水。 严、墮匹（白光、放热、澄清石灰水变浑浊）占燃Z、 2C + 02 = 2 CO 占姝 S +°2 =恥藍紫色火焰、放热、刺激性气味气体〉占墩 4P + 5屯=2P￡05（^＜放热、浓厚白烟、白色固体） 皎---- 3氏+2% = Fe304（火星四射、放热、黑色固体〕〔蔚可2Mg + 02 =刖耀眼白光、放热、白色固体） 4A1+3O￡= 2A1E03＜耀眼白光、放热、白色固休） 占懈 2H2+ 0 2= 2H2O 勺 占妒 2C0 + 02= 2C0￡ VCH4+202=C02 +-2H20. G炎蓝色或蓝色火焰，放熟 厂工业制法：分离液态空气* （发生物理变化〉 （f 2H2O22H20 + 02f 原理f 2KMnO4= K2HnO4 + MnO￡ + O￡f I 2KC1O3警 2KC1 + 3O￡f 片年奘詈J固体加恐制駿气体（棉花人或反王六直 ［固体与鮫氏影温下制取气体 妝第皱詈I排水法〔氧气不易溶于水〉 叹耒衣直丫向上排空气法盪气密度比空气大）固慷，耕末状固体（药匙） I定量（托盘天平：精确到0.1Q 「多童-倾倒（标签、容器口） 少堡T用胶头滴管（垂直、悬空*不能横放或倒置） L定壘T壘筒（平稳、平视）（注意规格的选#）（0. lnL） 使用方法（火柴点燃’外焰加热） 注意事项（使用前，使用时、使用后〉 仪器（试管、蒸发皿、烧杯，烧瓶） ?（l/3x短柄、移动、管口〉 固体（管口〉 物质的加热彳 I注意事项（都要预热、外壁擦干等等） r■方法（水淋刷洗、酸洗或洙涤剂〉 洗涤仪器彳注意事项（热的玻璃仪器不能用冷水恋不能用力刷洗等） I玻璃仪器洗涤干净的标准：不聚水滴、不成股流下 实验步骤：查、装、定、点、收、离、熄4 津賁重 丽j 加热固体制氧就并用排半法收集完汪息事坝 ［毕.应先播导管.后停住加热等。验满方法；将带 火星木条伸至瓶口、木条复燃。 l检验方法：将带火星木条伸至瓶中，木条复燃。田 抹J供给呼吸：潜水、/tJ H Jct.LhLJMe- Xi-Jknt 1毕?应先撤导管*后停止加热等。 支持側：炼钢、 I 测定空气中氧气的含量; 、医疗、航空等* 、化工生产、宇航等。 .JW足量红磷在盛有空气的巒闭容器中燃烧。 注竜貝体的实验方法、扌桑作注宣事项等。
煤粉燃烧器的分析 摘要：本文分析了几种有代表性的预燃室型煤粉稳燃装置的原理及其特性，并根据其原理提出了几种改进的方案。 关键词：回流区；煤粉锅炉燃烧器；钝体 前言：我国电力行业以劣质媒为主要燃料，这是我国能源政策的要求，同时也是我国煤碳资源分布状况、开采运输条件等所决定的。从经济性和发展趋势看，燃油锅炉和燃用优质煤锅炉所占比重将越来越少，燃用劣质煤锅炉，特别是大容量劣质煤锅炉将越来越多。锅炉燃用劣质煤时普遍存在着火困难、燃烧稳定性差、燃尽率低等问题。对于有些煤种，还存在着炉膛水冷壁结焦、尾部受热面磨损腐蚀、排放物严重污染环境等问题。另一方面，要求越来越多的锅炉机组参加电网调峰。锅炉参加电网调峰时，需要改变负荷和调整运行方式，这就进一步加剧了劣质煤锅炉己存在的问题的严重性。这些问题急需解决，而解决这些问题的重要手段就是研制和开发新燃烧设备。 我们小组从《燃烧学》课本上介绍的两种传统煤粉燃烧稳燃装置出发： 旋流稳燃器： 稳燃原理： 旋流射流的一个最大特点就是射流内部有一个反向回流区，旋转的射流不但从射流外侧卷吸周围的介质，而且还从内部回流区内卷吸介质，而内部回流区的烟气温度很高，能有效助燃和稳燃。 存在的问题： 1.预燃筒壁的积粉和结渣： 不能作为主燃烧器在锅炉运行中长期使用，甚至在短期的锅炉点火启动和低负荷稳燃运行使用时也成问题，因预燃室简壁结焦严重或出现局部温度过高而烧毁预燃室. 2.旋流叶片的磨损： 在长期多变负荷运行过程中，旋流叶片受到高速煤粉流的冲刷，容易磨损变形，造成煤粉流的堵塞，影响旋流效果 3.低负荷条件下工作不稳定，容易熄火，需要喷油助燃。 4.对无烟煤等低挥发分含量煤种的效果不好。 钝体直流稳燃器： 稳燃原理： 钝体是不良流线型体，在大雷诺数下流体流经钝体时在钝体的某个位置会是
溃疡性结肠炎常用药物 …… (1)磺胺类： 40年代开始用磺胺药治疗本病，其中以水杨酸偶氮磺胺吡啶(SASP)效果最佳。口服后易在肠内分解为磺胺吡啶及5-氨基水杨酸，对结肠壁组织有亲合力，起到消炎作用。常用于轻、中型病人。始量为0.5g，每日4次，口服。每隔2～3天增加1g，直到获得疗效。每日总量3～6g，个别可达8g。病情稳定，维持量为1.5～2g/日，持续4周以上，后隔3～5 日减量1次，直到每天服用1～2g为止，至少持续1年。然后考虑停药，以降低复发率。对停药后易复发者，可选最小剂量长期维持治疗。有效率在80%以上。其副作用常有恶心呕吐、头痛、全身不适。或引起白细胞减少、关节痛、皮疹、蛋白尿等。尤其是服用每日超过4g 以上者，副作用明显。其他如琥珀酰磺胺噻唑、肽酰磺胺噻唑及复方新诺明等也可选用。 (2)抗生素： 尤对急性暴发型及中毒作结肠扩张者采用抗生素治疗，用前应做细菌培养。如青霉素类、氯霉素、可林达要素、妥布霉素、新型头孢霉素和先锋霉素均可酌情选用。不宜口服以避免胃肠道刺激症状。 (3)灭滴灵：
每日1200mg，分3～4次口服，3～6个月为一疗程，目前尚未有严重副作用的报道。病程越短疗效越佳，病程在一年以上者，有效率在60%～70%。 (4)激素治疗： 包括糖皮质和促肾上腺皮质激素。本类药物能抑制炎症和免疫反应，缓解毒性症状，近期疗效较好，有效率达90%。另外激素可增加食欲，改善病人情绪。如小剂量强的松15mg，可明显减少复发率。并发腹膜炎或腹腔内脓肿形成者不宜应用。 ①口服皮质激素：病情活动期且病变广泛者，强的松每日40～60mg，分3～4次口服。病情稳定逐渐减量，每日10～15mg，持续半年后停药。在减量过程中或停药后，给以柳酸偶氮磺胺吡啶，以防停药后或减量过程中病情复发。 ②局部给药：病变只限于乙状结肠直肠者，可选：含氢化可的松10mg的肛门栓剂，每日2～ 3次；琥珀酸氢化可的松50～100mg 或强的松龙20～40mg溶于50～100ml液体中，每日1～2次，保留灌肠，同时加用SASP及适量的普鲁卡因或中药煎剂，10～15天为一疗程。灌肠后嘱病人平卧位或俯卧位，左、右、侧位等各15～20分钟，以利药后均匀分布粘膜面上。 ③静脉用药：如暴发型、严重活动型及口服无效者多采用。氢化可的松200～300mg或半琥珀酸钠氢化可的松200～300mg，或α-1-磷酸强的松龙40～60mg，10～14天为一疗程。病情稳定后改口服剂，强的松60mg/日口服。
LHX-高效节能型锅炉煤粉燃烧器 产 品 说 明 书 西安路航机电工程有限公司
一、工作原理： ①燃烧器是锅炉的主要燃烧设备，他通过各种形式，将燃料和燃烧所需要的空气送入炉膛使燃料按照一定的气流结构迅速、稳定的着火：连续分层次供应空气，使燃料和空气充分混合，提高燃烧强度。 煤粉燃烧器就是利用二次风旋转射流形成有利于着火的回流区，以及旋转射流内和旋转射流与周围介质之间的强烈混合来加强煤粉气流的着火特性。旋转射流的工质除了二次风外，还可以有一次风。在二次风蜗壳的入口处装有舌形挡板，用以调节气流的旋流强度，蜗壳煤粉燃烧器的结构简单，对于燃烧烟煤和褐煤有良好的效果，也能用于燃烧贫煤 运行参数:一次风率r1，一、二次风量比，一、二次风速w1和w2及风速比w1 /w2有关。。锅炉燃烧器使用的是气化原理，能使燃油完全 气化，整个燃烧器采用三级点火方式，先用高能点火器点燃轻柴油，再用轻柴油点燃浓煤粉，最后点燃淡煤粉，实现煤粉全部燃烧。 ②为避免工业锅炉积灰过多，本产品采取炉外排渣系统.进入锅炉体内的烟气灰渣尘只占燃料燃烧总的渣量的15%，其中只有小部分沉于锅炉体内,绝大部分烟气尘随烟气流入炉外的收尘系统.工业锅炉本体只需采用压缩空气吹灰系统即可避免锅炉本体人工掏渣。本产品的使用效果与燃油燃气的工业锅炉效果基本一致。
③本产品燃烧煤种与水煤浆燃烧煤种大大放宽，而不需要特优烟煤，而对于一般烟煤、无烟煤、褐煤等甚至劣质杂煤均可.使用其煤粉燃烬率可达到99%,炉渣含碳量为1%左右.炉渣为黄白色是农业化肥和建材的良好的混合材,以达到循环利用的目的.其耗煤量与一般链条锅炉可节省煤耗为25-30%以上。 二.环保技术指标： 由于燃烧系统的彻底改进，相对于链条式的工业锅炉，由燃煤层燃燃烧方式改为煤粉燃烧方式，同时又采用炉外排渣技术。其中燃烧筒（立式、卧式）的捕渣率能达到85%以上，进入工业炉的炉渣量几乎小于15%以上，只有极小部分烟尘沉于炉内,大部分随烟气流进炉后收尘系统.这样极大的减轻了炉尾部的收尘器的收尘量，进入锅炉内的细微烟尘只需要设置采用压缩空气吹灰孔即可，锅炉必须设置专用检查炉门。本公司依据水膜旋风除尘器的基本原理研发成功:文氏管双级脱硫水雾除尘器（不锈钢等钢结构见另外产品说明书），进而彻底淘汰多年普遍使用的水膜麻石除尘器，使锅炉后的除尘系统简单化，而除尘效果更优。经测算：除尘效率可达到99%，粉尘含量≤100mg/m3,SO2≤250～ 300mg/m3, NO2≤400mg/m3,总体排放指标，可达到国家城市二类地区的环保指标。 三.全线实现PLC全自动热工仪表控制系统
为有效解决当前大气污染防治工作进入瓶颈期、氮氧化物浓度持续高位、夏季O 3反弹的问题，按照环保要求，各相关单位按照文件精神开展燃气锅炉及锅炉的氮氧化物改造工作。 持续开展大气污染防治行动，坚决打赢蓝天保卫战，实现环境效益、经济效益和社会效益多赢。至2020年经过3年努力，大幅减少主要大气污染物排放总量，协同减少温室气体排放，燃气锅炉及锅炉均完成低氮改造，进一步明显降低细颗粒物(PM ) 2.5浓度，明显减少重污染天数，明显改善环境空气质量，明显增强人民的蓝天幸福感。 专业从事燃气锅炉低氮改造工作，以下为改造具体方案，可供参考： 改造施工现场 一、改造施工前准备工作如下： 做好施工人员进场准备，办理各项有关手续，按规定搭设临时设施，如现场布置、工地办公室、仓库、材料堆放场地、临时水、电到位，以及生活、卫生设施的落实。 1.对施工图纸进行全面会审，技术复核，熟悉图纸，了解各种工艺技术、材料性能及施工方法。 2.进一步深化施工组织设计，确定施工方案，认真做好对各工种施工前的技术交底。了解消防配套、弱电综合布线以及土建施工单位的工程实施计划，制定相应的配合施工计划。 3.按材料种类分类，做好垃圾清运工作。 4.根据燃烧器厂家提供的锅炉燃烧器图纸和辅机资料对燃烧器及辅机进行检验。对技术资料、图纸进行检查、清点。
5.仔细阅读燃烧器安装使用说明书，查看厂家对燃烧器安装有无特别要求。 6.带施工图纸到安装现场查看，锅炉基础及附件基础是否与图纸相符，施工现场是否与图纸一致。 7.在施工改造前，锅炉房内先进行断水、断电、断气后，确认无安全隐患，再进行原有燃烧器拆除，必要时采用专用工具。 8.在拆除后对燃烧器法兰接口尺寸进行校核，否则重新加工处理。 9.按照安装图纸施工现场配料，材料包括附件、阀门、仪表、管道、和保温材料等。所用的主要材料、设备及半成品应符合国家或相关部门标准，燃烧器厂家应提供国家特检院出具的燃烧器形式试验报告及证书。 10.之后到现场查看是否具备安装条件，包括锅炉运输道路是否畅通，是否具备锅炉就位的条件，现场是否干净，基础硬化情况，以及水电、工人施工居住条件等。 11.落实技术交底工作：组织各班组长及各工种技术业务骨干进行技术交底、质量交底、安全交底及文明施工交底，并逐级下达全体施工人员进行实施。 已改造完毕20t/h燃气锅炉 二、改造施工工艺及步骤： 1、打开锅炉前盖板，拆除旧燃烧机。 2、拆除后，测量盖板上固定燃烧机的螺栓孔。若孔距和低氮燃烧机的孔距相同，就可以直接安装新的燃烧机。若孔距不同，就要采取相应措施把新燃烧机固定在盖板上。
消化系统疾病病人护理测试题及答案 姓名分数 一、单选题(每题2.5分,共100分) 1、消化性溃疡并发大出血急救的中心环节是： A．补液输血 B．禁食输液 C．止血抗休克 D．手术治疗 E．以上均不是 答案：C 2、对消化性溃疡出血不适用的是 A．口服去甲肾上腺素 B．双气囊三腔管压迫 C．冰盐水洗胃 D．甲氰咪胍静脉注射 E．纤维胃镜下高频电灼 答案：B 3、在西方国家急性胰炎的主要病因除因胆道疾病外是 A．大量饮酒 B．暴饮暴食 C．手术创伤 D．药物刺激 E．钙离子 答案：A 4、肝昏迷病人经治疗神志恢复后可逐渐给予蛋白质饮食，最适宜的选择是 A．动物蛋白质
B．蔬菜、水果 C．碳水化合物 D．植物蛋白质 E．每日蛋白质在40g以上 答案：D 5、哪些药物不引起消化性溃疡 A.阿斯匹林 B.消炎痛 C.强的松 D.碳酸氢钠 E.保泰松 答案：D 6、肝硬化腹水病人为何发生呼吸困难A．合并肺瘀血 B．腹水抬高膈肌 C.引起右心衰竭 D．腹水压迫支气管 E．合并呼吸 答案：B 7、下列消化系统疾病的护理哪项不妥A．呕吐后应漱口 B．便秘时可多吃蔬菜水果 C．腹泻时可多吃高蛋白、高脂饮食D．腹胀时可用肛管排气 E．消化道出血后不宜立即灌肠 答案：C 8、肝昏迷昏迷前驱期最突出的表现是 A.表情欣快，定向力减退 B.精神错乱 C.运动失调
D.肌张力，腱反射亢进 E.意识错乱，行为失常 答案：E 9、结核性腹膜炎最多见的病理分型是 A．粘连型 B．渗出型 C．干酪型 D．混合型 E．坏死型 答案：B 10、关于胃窦炎的治疗，最正确的是 A．维生素B12治疗 B．稀盐酸口服 C．铁剂 D．杀灭HP E．肾上腺皮质激素 答案：D 11、急性胰腺炎产生休克的主要原因是：A．低血容量休克 B．心源性休克 C．疼痛引起神经性休克 D．失血性休克 E．过敏性休克 答案：A 12、轻、中度溃性疡性结肠炎治疗首选药物是A．肾上腺皮质激素 B．水杨酸偶氮磺胺吡啶 C．抗生素 D．手术治疗 E．免疫抑制剂
燃气锅炉低氮改造完成河北艺能锅炉有限责任公司
近年来，北京作为国家的首都，为响应国家的号召节能减排，绿色环保，北京在全国率先开展燃气锅炉低氮改造，从氮氧化物产生源头进行控制。从北京市环保局了解到，截至目前，今年北京市已完成锅炉低氮改造约7000台、2.3万蒸吨，年减排氮氧化物4800吨。 北京市环保局介绍，研究表明，燃气锅炉所排放的氮氧化物，在一定条件下，可成为PM2.5的原料。“燃气锅炉低氮改造”可实现氮氧化物的深度减排。 艺能锅炉有限责任公司是“清煤降氮”的主力企业。该企业技术管理部说，2017年企业的清煤降氮工作，改造共涉及锅炉房330座、锅炉1569台、8777.15蒸吨，建设新供热管线12.47公里，共计投资10多亿元。锅炉企业的此番改造，在单个采暖季可直接减少烟气及氮氧化物排放约1844吨。 据锅炉企业介绍，锅炉清煤降氮、实现达标排放，首先是“超净排放”，在北京市的方庄、科丰等供热厂的大型锅炉，采取“超低氮燃烧器+烟气再循环+尾部SCR”等多种组合脱硝方式，燃气锅炉氮氧化物排放低于15毫克/立方米。 艺能锅炉有限责任公司还推广非化石能源供热，燃煤、燃油锅炉实现清洁能源替代，宜气则气、宜电则电，推广空气源热泵、电蓄热等技术应用。 “十三五”期间，将致力于扩大清洁电蓄热、污水源、地热源、光伏等可再生能源利用。 为确保按期完成国家下达的节能目标任务，河北省政府办公厅日前印发《河北省节能“十三五”规划》。“十三五”期间，河北省将本着“强化双控、倒逼转型，严控增量、优化存量，培育市场、创新机制，突出重点、全面推进”原则，着力推进重点领域、重点区域、重点用能单位节能。 根据规划，河北省节能约束性目标是：到2020年，全省能源消费总量控制在32785万吨标准煤以内，万元国内生产总值能耗下降17%；2017年比2012年削减煤炭消费4000万吨，“十三五”期间煤炭消费总量下降10%左右。
喹诺酮类、磺胺类及其他合成抗菌药 一、喹诺酮类 第一代：奈啶酸（1962） 第二代：吡哌酸（1974），仅适用于泌尿道和肠道感染 疗效差、耐药性发展迅速、应用日趋减少 第三代：氟喹诺酮类（1979） 诺氟沙星（氟哌酸）、氧氟沙星、 环丙沙星、左氧氟沙星、依诺沙星、培氟沙星 口服有效、副作用小、耐药性还未大量产生、发展迅速、临床广泛使用 第四代：新氟喹诺酮类 格帕沙星、加替沙星、莫西沙星、克林沙星 【喹诺酮类药物抗菌作用机制】 DNA回旋酶→干扰DNA复制 ◇对细菌选择性高，不良反应少。 （真核细胞不含有DNA回旋酶） 【喹诺酮类共同特点】 1.抗菌谱广、杀菌 ①尤其对革兰阴性杆菌作用强，包括铜绿假单胞菌在内有强大的杀菌作用（环丙沙星最强）； ②对部分革兰阳性菌，如金葡菌及产酶金葡菌也有良好抗菌作用（左氧氟沙星最强）； ③某些品种（环丙、左氧氟）对结核杆菌、支原体、衣原体及厌氧菌也有作用； ④新喹诺酮类抗革兰阳性菌作用增强，特别是对肺炎球菌和葡萄球菌；莫西沙星还具有其他氟喹诺酮类所缺乏的抗厌氧菌活性。 阳盛阴不衰 霸气抗厌氧 2.口服吸收良好，体内分布广 可进入骨、关节； 氧氟沙星、环丙沙星、培氟沙星可进入脑脊液； 血浆蛋白结合率低； t1/2较长； 多数以原形经肾排泄，尿药浓度高； 部分经肝脏代谢后，由肾排出； 3.不良反应少，耐受性良好 （1）消化道反应：常见恶心、呕吐、食欲减退。氧氟沙星可致伪膜性肠炎。 （2）过敏：皮疹、血管神经性水肿、光敏性皮炎（洛美沙星多见）等。 （3）中枢神经系统：头痛、眩晕等。 不宜用于中枢神经系统病史者，尤其癫痫病史者。 （4）关节软骨损害：所有氟喹诺酮类在在儿童可引起关节痛及肿胀 故不应用于青春期前儿童或妊娠期妇女。
利用思维导图进行高中元素及其化合物教学 徐野在中学化学教学中有许多教学方法，若得到合理使用就能极大的提高学生的学习效率和教师的教学效率。其中一种较为有效的手段——“思维导图"，对学生逻辑思维能力的提升以及知识整理能力有很大帮助。化学这门学科的知识点较琐碎，并且涉及许多的化学元素及化合物间的反应方程式。基于此，要想将此门学科讲授的生动形象且内容丰富是非常难的，尤其是在学生学习了化学元素及化合物的性质及各种反应等内容后，在记忆方面也是非常大的考验。因此，在化学元素及化合物的教学中，“思维导图”的运用可以帮助学生理清思路，通过制作思维导图明确每一种元素及化合物之间的转化关系，将多种物质之间的关系串联起来，在头脑中形成知识网，理解性记忆，不再是死记硬背，生搬硬套。比如需要讲解一个化学的反应方程式，就必须要让学生理解物质的性质及反应原理，而物质性质可以从元素的原子结构、物质组成上入手，在关系上就可以表现为将这个元素作为一个主题，然后将它的单质、化合物作为二级内容，接着再根据其性质进行延伸，这样接连的延展过程最终就形成“思维导图”。学生按照自己的思维方式制作出各种形式的思维导图，可以是图画、也可以是流程图，让学生理解每一级、每一个分支的由来，有助于记忆枯燥乏味的化学反应方程式。 1.“思维导图”的制作方法 “思维导图”能够建构出更加有条理的知识框架体系，对所要建构
的内容能够形成知识体系网状结构，有更加清晰明了的认知，这样不仅有利于提高学习的效率，也能为之后的复习打好基础，极大地方便了知识的提取。思维导图的制作步骤如下:首先要选取好一个“主题”，然后对这个主题关联的内容、对象向外进行二级、三级等延展，进行思维的发散。就像是一颗大树干上接了很多的小树杈分支。注意每个级别的“树杈”上都要标注关键词,这样就能形成一个知识点的通路，思维导图也就制作完成了。 2.“思维导图”的课堂应用 在教学过程中，教师可以对某个知识点进行“思维导图”的制作，方便教学，也能够让学生加深对此知识点的理解。也可以做为复习的手段之一，以小组为单位分配制作“思维导图”任务，给学生布置一个相同或者不同的知识点，让他们自己动手去制作“思维导图”，当成课堂作业来完成达到复习的目的。这样他们就能够自己去展开某个知识点的生成以及被生成过程，或者对元素的分类等内容进行展开。也可以做为学生课前自主预习的工具，上课时结合自己的思维导图找到知识疏漏并及时得到补充。同时，在学生制作完成之后上台对自己的作品进行说明，以小组为单位由学生进行作品评选，得选率最高的作品主人就可以得到相应的奖品。这样不仅锻炼了他们的动手能力，又活跃了课堂氛围，在轻松愉悦的环境下对知识进行主动的学习。3.“思维导图”应用的意义 思维导图的利用可以对新知识进行有效的预习，也可以对之前学过的旧知识进行复习。有利于加深之前所学内容的印象,并形成系统
2018年河南省燃气锅炉低氮改造奖补方案 河南远大锅炉是国内最早建立起来的工业锅炉生产单位，我公司主要从事燃气锅炉，生物质锅炉，燃煤锅炉等环保锅炉的研发与生产，燃煤锅炉改造以及低氮锅炉改造等。 很多用户对我省的煤改气，燃气锅炉低氮改造项目不是很清晰，下面简答介绍一下。 为落实国家财政部、环保部《大气污染防治专项资金管理办法》，省财政厅、省环保厅《河南省省级大气污染防治专项资金管理办法》，推动我市大气污染防治工作，进一步改善环境空气质量，市政府决定对2018年度大气污染防治治理项目实施资金奖励或补助，现结合我市实际，制定本方案。 一、奖补原则和范围 （一）奖补原则 “早完成、严标准、多减排、多奖励”原则。 （二）奖补范围 1．严于国家或地方污染物排放标准实施的大气污染工程 治理示范工程改造项目； 2．严于国家、省要求的结构调整项目； 3．在工程治理、节能改造等领域严于国家、省有关要求 的、具有前瞻意义的试点工程项目或科研攻关项目； 4．严于国家、省有关要求的，鼓励类清洁能源结构改造 项目。 （三）资金来源 奖补资金来源中央及省财政拨给本市可用于大气污染防治项目的资金，不足部门由市级财政承担。 二、奖补标准 （一）燃煤锅炉拆改。10蒸吨以上燃煤锅炉拆改实施逐年递减的资金奖补方式，对2018年10月底前（含2016年、2017
年）完成拆改的燃煤锅炉，给予不低于6万元/蒸吨奖补；对2019 年10 月底前完成拆改的燃煤锅炉，给予不低于4 万元/蒸吨奖补。 2016 年、2017 年按期完成拆除任务的10 蒸吨以下（含10 蒸吨）燃煤锅炉给予不低于2万元/蒸吨奖补。 （二）煤气发生炉拆改。2018年10月底前煤气发生炉（含2016 年、2017 年）完成实施拆除或改用清洁能源的，给予拆除单位每台10万元奖补。 （三）生物质锅炉拆改。2018年10月底前（含2016年、2017 年）生物质锅炉实施拆改的，给予不低于2 万元/蒸吨资金奖补。 （四）重点行业示范工程建设。 1．2018 年9 月底前，完成烟气超低排放示范工程建设，污染物排放浓度颗粒物≤10毫克/立方米、二氧化硫≤50毫克/立方米、氮氧化物≤100毫克/立方米的熟料生产水泥企业，市级财政按照设备投资额的15%进行奖补，最高不超过500万/家。 2．2018 年9 月底前，完成烟气超低排放改造示范工程建设，煅烧、焙烧工序烟尘、二氧化硫、氮氧化物排放浓度要分别不高于10毫克/立方米、35毫克/立方米、50毫克/立方米的碳素企业，市级财政按照设备投资额的15%进行奖补，最高不超过500万/家。 3．2018 年9 月底前，完成烟气超低排放改造示范工程建设，烟尘、二氧化硫、氮氧化物排放浓度要分别不高于10毫 克/立方米、35毫克/立方米、50毫克/立方米的生活垃圾焚烧发电、医疗废物、危险废物焚烧处置等设施，市级财政按照设备投资额的15%进行奖补，最高不超过500万/家。 （五）天然气锅炉低氮改造项目。2018年6月底前，完成低氮改造示范工程建设，氮氧化物排放浓度要不高于30毫克/立 方米的天然气锅炉，市级财政按照设备投资额的40%进行奖补； 2018 年9 月底前，完成低氮改造示范工程建设，氮氧化物排放浓度要不高于30毫克/立方米的天然气锅炉，市级财政按照设备投资额的30%进行奖补；2019年4月底前，完成低氮改造工程建设，氮氧化物排放浓度要不高于30毫克/立方米的天然气锅炉，市级财政按照设备投资额的15%进行奖补。