The addition of a surfactant

FEBRUARY 99COVERSTOCK WETBACK151.2-99 RECOMMENDED TEST METHOD: NONWOVENS COVERSTOCK WETBACK1SCOPEThe purpose of the test is to examine the ability of diaper coverstock to resist the transport back onto the skin of a liquid which has already penetrated the coverstock.The test has been designed for coverstock comparison purposes only and is not intended to simulate in-use conditions for finished products.2TESTING CONDITIONSCondition the samples of nonwoven, the filter papers to be used as the standard absorbent pad and the pick up paper for 24 hrs and test at 23ºC and 50 % relative humidity or, if not, at 20ºC and 65 % relative humidity; test conditions are to be mentioned in the report (see ERT 60 for tolerances and choice of conditions).3RECOMMENDED METHODThis is based on methods already used as internal methods by industry and which have been adapted by the Technical Committee of EDANA.4PRINCIPLEA coverstock is placed over a standard absorbent medium which is then loaded with a specificquantity of simulated urine. A standard weight is placed onto the coverstock and absorbent medium to ensure even spreading of the liquid.A pre-weighed pick up paper is then placed on the coverstock and the weight again put on top.The mass of liquid absorbed by the pick up paper is defined as wetback.5MATERIAL AND REAGENTS5.1Reference absorbent medium, consisting of five layers of reference filter paper (100 mmx 100 mm) with the smooth side uppermost and having a mean strike-through time, in 10 determinations without the nonwoven, of (3 ± 0,5) s as used in ERT 150 (liquid strike-through time) but with the additional requirement of the liquid absorbency capacity (LAC) measured using ERT 10 to be (480 ± 30) %.The reference filter paper ERT FF3 is supplied by HOLLINGSWORTH & VOSE COMPANY LTD.5.2Simulated urine, consisting of a 9 g/l solution of sodium chloride in distilled water with asurface tension of (70 ± 2) mN/m.This surface tension should be checked before each series of tests, as surface can alter tension during storage.151.2-99FEBRUARY 99 Note:The surface tension of adult human urine is published as 69 to 70 mN/m. There isa suggestion that some babies' urine could have a lower surface tension (e.g. 45mN/m). The surface tension of the simulated urine may be adjusted by the additionof a surfactant. In this case it should be reported as a deviation from standardprocedure and the surface tension should be stated in the test report.5.3Pick-up paper, ERT-MED white, 125 mm x 125 mm square (supplied byHOLLINGSWORTH & VOSE COMPANY LTD.).Paper characteristics:- mass per unit area: (90 ± 4) g/m²- air flow resistance: (1,9 ± 0,3) kPa.6APPARATUS6.1 Burette, of 50 ml capacity, with a supporting stand.6.2 Funnel, fitted with a magnetic valve, giving a rate of discharge of 25 ml in (3,5 ± 0,25) s.6.3 Ring stand to support the funnel.6.4Strike-through plate (see figures 1 and 2) constructed of 25 mm thick transparent acrylicsheet, of total mass (500 ± 5) g, fitted with corrosion-resistant electrodes consisting of 1,6 mm diameter platinum or stainless steel wire set in grooves of cross-section 4,0 mm x 7,0 mm cut in the base of the plate and fixed with quick-setting epoxy resin.The electrodes shall be positioned as shown in figures 1 and 2.6.5 Base plate, of transparent acrylic sheet, approximately 125 mm x 125 mm square and 5mm thick.6.6 Electronic timer measuring to the nearest 0,01 s.6.7 Simulated baby weight, consisting of:- a weight: stainless steel base 10 cm x 10 cm including a handle, of total mass (4000 ±20) g;- a polyurethane foam rubber, 10 cm x 10 cm x 2 cm height (code CMHR 50 supplied by VITA FOAM LTD., UK);- a polyethylene film (Mayaflex 90 (25µm) supplied by ACE SA Belgium).Wrap the P.E. film, female side out, to the foam, securing the film in place with tape then taping the film and foam to the weight (see diagram below).FEBRUARY 99151.2-99 7 PROCEDUREThis test is conducted in conjunction with the strike-through test (ERT 150) as follows:7.1 Set up the ring stand holding the funnel and position the burette with the tip inside thefunnel.7.2 Weigh 5 layers of filter paper ERT FF3 and place them with the smooth/test side upper-most on the strike-through baseplate (screen side against the nonwoven). The mass (W)of the filter paper ERT FF3 will be used as a parameter to determine the total quantity ofliquid (Q) required for the wetback test (see 9).7.3 Cut the required number of pieces of nonwoven, 125 mm x 125 mm, test pieces beingselected in accordance with ERT 130 if applicable.7.4 The quantity of liquid (Q) will be calculated by multiplying (W) by the loading factor (LF)of the filter paper (see 9).The recommended loading factor is 3,30.7.5 Place one nonwoven test piece over the set of 5 layers of filter paper. Place thestrike-through plate on top of the nonwoven with the centre of the plate over the centreof the test piece. Centre the burette and the funnel over the plate.7.6 Adjust the height of the funnel so that it is (5 ± 0,5) mm above the top of the cavity in theplate (i.e. 30 mm above the test piece).7.7 Ensure the electrodes are connected to the timer. Activate the timer and set the clock tozero.7.8 Fill the burette with simulated urine. Keep the discharge valve of the funnel closed andrun 5,0 ml of liquid from the burette into the funnel.7.9 Open the magnetic discharge valve of the funnel to discharge the 5,0 ml of liquid. Theinitial flow of liquid will complete the electrical circuit and start the timer. It will stop whenthe liquid has penetrated into the nonwoven and fallen below the level of the electrodesin the strike-through plate.7.10 Record the strike-through time.7.11 Add additional quantity of liquid in order to reach the specified quantity (Q).7.12 Remove the baseplate with the sample and filter paper from the strike-through apparatus.7.13 Gently put the 4 kg weight assembly onto the sample.7.14 The weight remains in place for 3 minutes to ensure even diffusion of the liquid.7.15 Remove the weight without disturbing the nonwoven test piece.151.2-99FEBRUARY 997.16 Weigh two layers of pick-up paper, record the mass (P1) and place them on the testpiece, with the smooth / test side against the sample.7.17 Wipe the contact surface of the weight before gently replacing it over the pick up paper.A loading speed should be applied in such a way that the last 5 cm displacement takes(5 ± 1) s (see 9.5).7.18 The weight remains in place for 2 minutes ± 2 s, during which time wetback has occurred.7.19 Remove the weight and reweigh the pick-up paper (P2).7.20 Calculate the wetback value (WB) = P2 - P1 (expressed in g).7.21 Repeat for the required number of test pieces. (A minimum of 3 tests on test pieces fromeach sample is recommended).8REPORTThe test report shall include the following information:a) Type of material.b) Number of test pieces tested.c) Testing conditions.d) Individual strike-through times, in seconds.e) Individual wetback (expressed in g).f) Average wetback (expressed in g).g) Standard deviation of results (expressed in g).h) Any deviation from the standard procedure.9REMARKS9.1The loading factor (LF) is dependent on the liquid absorbency capacity (LAC) and willchange as the LAC changes.A loading factor of 3,30 was found to be appropriate when using paper filters of a LAC of480 ± 30%.A knowledge of the wetback vs. loading factor curve for a coverstock is useful sometimes,as, close to the break point, wetback dispersion increases dramatically.FEBRUARY 99151.2-99 The use of control nonwoven samples is strongly recommended to monitor the correctfunctioning of the test. Good wetback samples, one with wetback 0,12 g or less and theother around 0,20 g, are sufficient to monitor the test.9.2If the LAC of the paper filter used differs from the above value or if a refined procedureis needed for research or for ranking purpose, different loading factors can be used.Modified LAC and LF should be mentioned in the report.Note : If the LAC differs from the specifications, the filter paper supplier will indicate therecommended LF corresponding to this different LAC.9.3 It is recommended that the same filter paper batches are used for wetback comparisonpurpose.9.4 The application of the weight in 7.17 is a critical step. The training of the operator can beprovided by practicing the placement of the weight on a balance without overcharging thebalance by more than a few grammes (5g).Alternately an automatic system with a pneumatic piston can be used to apply the weightassembly consistently.9.5 Maintenance.The repeatability of this test depends on the maintenance of the strike-through plate. Inorder especially to avoid the formation of sodium chloride crystals, the creation of a waterfilm or any other contamination on the walls that could modify the strike-through timemeasurement, see the maintenance instructions from the plate manufacturer. HOLLINGSWORTH & VOSE COMPANY LTD. Tel : +44/1242.602.2227Postlip Mills Fax : +44/1242-604.099 Winchcombe, CheltenhamUK - Glos. GL54 5BBUNITED KINGDOM151.2-99FEBRUARY 99Figure 1 - Strike-through plateFEBRUARY 99151.2-99Figure 2- Section across strike-through plate on centre line of 25mm dia. cavity。

Agricultural Sciences, 2014, 5, 625-633Published Online June 2014 in SciRes. /journal/as/10.4236/as.2014.57066The Impacts of Nonnative Japanese Eelgrass (Zostera japonica) on Commercial Shellfish Production in Willapa Bay, WAKim PattenLong Beach Research and Extension Unit, Washington State University, Long Beach, WA, USAEmail: pattenk@Received 12 April 2014; revised 19 May 2014; accepted 14 June 2014Copyright © 2014 by author and Scientific Research Publishing Inc.This work is licensed under the Creative Commons Attribution International License (CC BY)./licenses/by/4.0/AbstractEelgrass species worldwide are valued for the ecosystem service they provide to estuarine and marine habitats. One species, Zostera japonica, however, has some negative impacts outside its native range and is considered invasive. In Willapa Bay WA, USA, the nonnative eelgrass has ex-panded to the level where the shellfish industry is concerned about its potential impacts on its li-velihood. Studies were conducted using paired plots, Z. japonica controlled with the herbicide im-azamox vs. untreated controls, to assess the effects of Z. japonica on Manila clams (Ruditapes phi-lippinarum) and Pacific oysters (Crassostrea gigas). Recruitment of new Manila clams was not af-fected by Z. japonica. The growth of young clams, total commercial clam harvests, clam quality and clam harvest efficiency, however, were greater on plots where Z. japonica was chemically con-trolled than where it was not treated. The response of oysters to Z. japonica control varied by site;there was no effect at one site, while the other sites had a 15% increase in shucked meat with Z.japonica control. The potential economic impact of a Z. japonica infestation of a shellfish bed was ~$47,000 ha−1 for Manila clams and $4000 ha−1 for oysters for each crop harvest cycle.KeywordsShellfish Aquaculture, Invasive Eelgrass, Manila Clams, Pacific Oyster1. IntroductionWorldwide, there are over 60 species of seagrass which provide many ecosystem functions, including support-ing diverse benthic assemblages, providing carbon to the estuarine food web, structural support for other prima-ry producers and habitat for juvenile salmonids and other fish species [1]-[3]. A few seagrass species, however,are considered to be invasive outside their native range [3]. Zostera japonica, in particular, has been reported to have several negative ecological consequences [4]-[6]. In Willapa Bay, WA, USA, coverage of the upper inter-tidal zone by Z. japonica has increased to the level where it is affecting the livelihood of the shellfish industry [5] [7]. Studies to document the impact of Z. japonica on shellfish, however, have been limited and have not ad-dressed the economic impact to the industry [2]. Regulatory agencies’ biologists and environmental groups are reluctant to sanction an effort to control a nonnative plant that performs many of the same ecological functions as the native eelgrass, Z. marina,in order to culture the nonnative shellfish species, Pacific oysters (Crassostrea gigas) and Manila clams (Ruditapes philippinarum) [1] [2] [8]. These groups place a high value on the ecosys-tem services and are in conflict with stakeholders considering economic value [2] [7]. Without reliable data to validate the shellfish industry’s concern about the detrimental effects of Z. japonica, their need for on-farm management options to sustain their livelihoods has met with skepticism [2]. The purpose of this study is to document the impacts of Z. japonica on several different production parameters of shellfish farming in Willapa Bay, WA.2. Material and Methods2.1. Site Location and Shellfish Industry BackgroundResearch was conducted under tidal estuary conditions in Willapa Bay, Washington, between 2010 and 2013. The study sites were located along a 10 km by 0.15 km band, within the 0.5 m to 1.5 m tidal height range, be-tween 46.5114˚N, 124.0030˚W and 46.6089˚N, 124.0357˚W. Willapa Bay is a large, shallow bar-built estuarywith 347 km2in surface area at mean higher high water (MHHW) and 191 km2at mean lower low water (MLLW). The tidal range between MHHW and MLLW is 2.4 to 3.4 m. More than half of the estuary’s surface area and volume is drained at low tide [9]. Willapa Bay produces 17% of US commercial oysters (calculated from reported data for 2012 from / and WA Dept. Fish and Wildlife Data Service). Approximately 20% of the intertidal area is utilized for commercial aquaculture of Pacific oysters and Manila clams [10]. In Willapa Bay, these intertidal benthic grazers rely on oceanic phytoplankton as their main food source, with the majority of their growth occurring between May to September [11]. Clam and oyster farmers utilize natural recruitment and hatchery-set seed; it takes three to five years to reach commercial harvest size. Clams are then raked and removed by hand. Oysters are both dredged and picked by hand.2.2. Experimental DetailsExperiments were conducted using adjacent paired plots on tide flats completely infested with moderate to thick stands of Z. japonica. Sites for Manila clam experiments were privately owned commercial clam beds with a 4 - 6 cm layer of screened gravel, <2 cm, on the surface that was placed on site by growers to facilitate clam re-cruitment and protect against predation by crab. Sites for Pacific oysters had layers of existing oyster shell + se-diment. The size profile of the original surface sediment, 0 to 7.5 cm depth, was: 1% < 0.1 mm; 42% > 0.1 mm < 0.23 mm; 54% > 0.23 mm < 0.5 mm; 1% > 0.5 mm. Treatment comparisons were an uncontrolled Z. japonica plot vs. a plot where the Z. japonica was controlled with the herbicide imazamox. Imazamox was applied at 0.14 kg ai·ha−1in late spring after the majority of new seedlings had germinated. Applications were made with a backpack sprayer at 20 l·ha−1, using estuarine water as a carrier without the addition of a surfactant. Treatments were applied during low tide on a dry exposed canopy. Plot size and replicate number varied by experiment and are detailed within each experiment.2.2.1. Effects of Nonnative Eelgrass on Settlement of Manila Clam LarvaePaired plots were established at four locations 0.5 to 2 km north of Nahcotta WA. Site 1 had 3 by 4 m plots with 7 replicates, and was treated 5/24/12. Site 2 had 5 by 15 m plots with 3 replicates, and was treated 6/24/13. Site 3 had 3 by 4 m plots with 5 replicates, and was treated 6/24/13. Site 4 was 4 by 4 m plots with 7 replicates, and was treated on 6/24/13. To assess for clam settlement, sediment cores 5 cm deep × 11 cm diameter were taken. Sediment was collected in May 2013 for Site 1, and November 2013 for Sites 2 to 4. Sediment samples were immediately sieved after collection and everything between 2 mm and 0.5 mm was frozen. Rose Bengal dye was used to stain clams to enhance visibility [12]. Samples were evaluated under a dissecting scope for number of Manila clams <8 mm in length.2.2.2. Effects of Nonnative Eelgrass on Manila Clam GrowthGrowth of new clam seed. A site 6 km north of Nahcotta WA was established with 4 replications of 12 by 12 m plots that were treated on 5/4/09. Within each plot, 30 small Manila clam seeds 4 to 12 mm in size, mean 7.5 mm, were placed in 284 cm2 plastic mesh (12 mm) round screen cages that were buried 5 cm in the ground with 2 cm extending above the sediment and left open on the top. There were three cages per plot. Macroalgae that were collected over the tops of the cages were removed several times per month. On 10/19/10 clams were re-moved from the cages; shell length and width and fresh and dry weight were recorded for each clam. Mean shell area (A = πab) and weight were pooled for each cage and used for subsamples for statistical analysis.Growth by age class. A site was established 2 km north of Nahcotta WA with 10 replications of 4 by 5 m plots that were treated on 6/24/13. To assess for clam growth by age class, sediment cores 8 cm deep by 20 cm diameter were taken on 11/11/13. All Manila clams within the core were removed and segregated by age class based on growth rings [13]. If any plot from any replication did not have >5 clams per core for any age class, that replication was not used for statistical analysis. Because there were not enough 1 year-old clams to assess from the November sample, the site was resampled on 3/30/14 for 1-year-old age class clams. Shell length and width for each clam were recorded. Mean shell area for each age class for every replicate was used for statistical analysis2.2.3. Effects of Nonnative Eelgrass on Manila Clam Site ProductivityPaired plots were established at six locations distributed along a 10 km band north of Nahcotta WA. Plot size was 3 by 4 m. The number of replications for Sites 1, 2, 3, 4, 5 and 6 was 20, 8, 10, 11, 12 and 20, respectively. Treatments were applied 5/27/10 for Sites 1 to 5, and mid-May 2013 for Site 6. All sites were harvested in mid-November in the year of treatment. Sites were harvested by taking 0.09 m2 cores 20 cm deep and removing all Manila clams >30 mm length. The total weight of Manila clams >30 mm was recorded for each plot.2.2.4. Effects of Nonnative Eelgrass on Shellfish QualityOyster. Two commercial oyster beds with moderate infestations of Z. japonica 8 km north of Nahcotta WA were treated on 6/28/13. Site 1 had 2 year-old seed that was placed on the site on March 2012. There were three rep-lications of 15 by 15 m plots. Site 2 had 3 year-old oysters that were placed on the ground on June 2012. There were six replications of 15 by 15 m plots. Plots were harvested 11/14/13. Thirty single oysters per plots were harvested from Site 1 and 60 per plot from Site 2. Total oyster weight, shell + meat, and total meat weight were recorded for each batch. For Site 2, oyster condition index (CI) was determined for 25 oysters per rep on three replications using standard protocol [14]. Oysters were harvested on 11/15/13. Total weight, meat dry weight and shell dry weight were recorded for each oyster. The mean CI for each replication was calculated (CI = meat dry wt./(total oyster wt-shell dry wt)−1 × 100).Clams. A commercial clam bed 3 km north of Nahcotta WA was treated on 5/27 /2010. There were 12 repli-cated plots of 3 by 4 m. The plots were harvested 11/15/2010 taking 0.09 m2 cores 20 cm deep and removing all Manila clams >30 mm length. For each clam shell length and diameter, clam volume by displacement, clam to-tal fresh weight, meat fresh and dry weight, and shell dry weight were recorded. The mean clam CI and meat dry weight per clam volume for each replication was calculated.2.3. Effects of Nonnative Eelgrass on Manila Clam Harvest EfficiencyA commercial clam bed was treated on 6/24/2013. There were 5 by 7 m replicated plots. A 1 m2 quadrat from the middle of each plot was harvested on 11/1/13 for marketable clams by a commercial digger. The harvester was told to harvest at his normal pace, was paid per unit of clams obtained and was not made of aware of the expe-rimental objective. The total weight and the time to harvest each plot were recorded. After commercial digging, the plots were carefully re-dug and the number and weight of unharvested commercial clams were recorded. The percentage of unharvested clams by weight and number and the harvest speed in seconds/clam were calculated.2.4. Statistical AnalysisResults were analyzed from each experiment using plot mean in a paired T test, with a two-tailed P value. If data failed normality testing based on Shapiro-Wilk, then Kruskal-Wallis One Way Analysis of Variance on ranks was conducted.3. Results3.1. Effects of Nonnative Eelgrass on Recruitment of Manila Clam LarvaeAcross all sites, and two years of assessment there was no effect of Japanese eelgrass removal on the density of Manila clams that settled into the treated area within that season of treatment (Table 1).3.2. Effects of Nonnative Eelgrass on Manila Clam GrowthAfter 138 days of growth on site, juvenile clams were confined within screened cages in the treated areas. They had 12%, 16% and 9% greater fresh and dry weight and size, respectively, on plots where Z. japonica was re-moved than where it wasn’t (Table 2). Treatment comparison in clam size by age class was made after one sea-son of growth. One, 2, 3, 4 and 5 year-old clams on plots where Z. japonica was removed were 24%, 33%, 26%, 7% and 8% greater, respectively, than where it wasn’t (Table 3). The growth increase for the 4 and 5 year-old clams, however, was not significantly different.3.3. Effects of Nonnative Eelgrass on Manila Clam Site ProductivityThe yield of commercial clams after one growing season was greater in 5 out of 6 commercial clam farms where Japanese eelgrass was removed than where it was left untreated (Table 4). The mean increase in yield across all sites for just one season of Z. japonica control was 45%.Table 1. Effect of Z. japonica control with the herbicide imazamox on the settlement of Manila clams in Willapa Bay, WA.# of newly recruited manila clams a 1000 cm−3 of surface sediment TreatmentSite 1 Site 2 Site 3 Site 4 Z. japonica 23 61 27 375No Z. japonica19 48 24 442T test significance 0.18 0.17 0.48 0.62a clams < 8 mm in size.Table 2. Effect of one summer of Z. japonica control with the herbicide imazamox on the fresh and dry weight and size of seeded juvenile Manila clams in Willapa Bay, WA.Treatment Fresh wt (g·clam−1) Dry wt (g·clam−1) Clam size (cm2)aZ. japonica 0.88 0.027 0.61No Z. japonica 1.00 0.032 0.67T-test significance 0.009 0.002 0.001a(A = πab).Table 3. Effect of one summer of Z. japonica control with the herbicide imazamox on the size of different ages of Manila clams in Willapa Bay, WA.Clam shell area (cm2)aTreatment1 yr-old2 yr-old3 yr-old4 yr-old5 yr-oldZ. japonica 0.38 1.13 1.95 3.33 3.81No Z. japonica0.47 1.69 2.62 3.57 4.15T test significance 0.001 0.04 0.006 0.1 0.1a(A= πab).3.4. Effects of Nonnative Eelgrass on Shellfish QualityThe response of oysters to Z. japonica control is varied by site. At Site 1, with younger smaller oysters and less coverage of Japanese eelgrass, there was no treatment effect (Table 5). At Site 2, total oyster weight, meat weight per oyster and their condition index was increased by 12%, 15% and 15% respectively by controlling Z. japonica. The quality of commercial size clams at harvest was also improved by removing Z. japonica from the plot. Clams growing without Japanese eelgrass had 19%, 14% and 15% greater meat per clam, meat per clam volume, and clam condition, respectively, than those grown in untreated plots (Table 6).3.5. Effects of Nonnative Eelgrass on Manila Clam Harvest EfficiencyFor commercially hand harvested clams, removal of Z. japonica reduced the percent weight and percent number of clams missed by the digger by 5% and 8% respectively (Table 7). There was a non-significant trend for 30% increase in harvest efficiency, 1 second less per clam, when there was no Z. japonica hindering the picker (one-tailed P-value = 0.06).Table 4. Effect of one summer of Z. japonica control with the herbicide imazamox on the yield of commercial size Manila clams (>30 mm length) in Willapa Bay, WA.TreatmentYield of commercial clams (kg·m−2)Site 1 Site 2 Site 3 Site 4 Site 5Site 6Z. japonica 2.2 0.7 1.0 1.2 0.5 5.1No Z. japonica 3.9 1.3 1.5 2.6 1.2 7.6T-test significance 0.02 0.04 0.3 0.03 0.007 0.05Table 5.Effect of one summer of Z. japonica control with the herbicide imazamox on the quality of Pacific oysters in Willapa Bay, WA.TreatmentSite 1 Site 2Shell + meat(g fw·oyster−1)Meat(g fw·oyster−1)Shell + meat(g fw·oyster−1)Meat(g fw·oyster−1)Oyster conditionindex aZ. japonica 189 24 211 33 5.7No Z. japonica192 27 241 39 6.7 T test significance 0.9 0.2 0.05 0.04 0.02a meat fresh weight/(total shell + meat fresh weight shell dry wt.)−1 × 100.Table 6.Effect of one summer of Z. japonica control with the herbicide imazamox on the quality of Manila clams in Willapa Bay, WA.Treatment Meat yield (g dw·clam−1) Meat/clam volume (g dw·clam·cm−3) Clam condition index aZ. japonica 0.46 0.031 4.4No Z. japonica0.56 0.036 5.2T test significance 0.0001 0.001 0.007a meat fresh weight/(total shell+ meat fresh weight shell dry wt.)−1 × 100.Table 7. Effect of one summer of Z. japonica control with the herbicide imazamox on the commercial harvest efficiency of Manila clams.Treatment % of total # of commercialclams a harvested% of total wt of commercialclams harvestedHarvest efficiency(seconds clam−1)Z. japonica 88 87 3.4 No Z. japonica93 95 2.6 T-test significance 0.04 0.05 0.1 a clam length >30 cm length.4. DiscussionSubmerged aquatic vegetation dampens water currents, and is reported to enhance clam recruitment [15] [16]. Under the conditions of these studies, however, there was no observed effect of Z. japonica on Manila clam set-tlement. Two previous studies assessing the influence of Z. japonica on Manila clam settlement provide mixed results. Ruesink et al. [17] found no effect of Z. japonica on Manila clam recruitment, while Tsai et al.[6] showed the lowest recruitment numbers of Manila clams where Z. japonica was removed by hand; intermediate numbers were in Z. japonica plots, and highest numbers were where Z. japonica was removed by harrowing. They suggest that their finding could be an artifact of the process of physically removing Z. japonica.In contrast to recruitment, Z. japonica had a very marked impact on Manila clam growth, production and quality. The most significant effect associated with Z. japonica control was total site commercial productivity. An average increased yield of commercial clams across six sites was 45%. Based on the differential results in growth rates between age classes of Manila clams, this degree of influence on commercial yield from just one season of Z. japonica removal was much greater than expected. For young, fast-growing clams, the beneficial effect of one season of Z. japonica removal ranged from 9% to 33% depending on the growth parameters as-sessed. In contrast, no significant differences were noted for fully mature clams (>4 years old). For the short time these paired plot studies were conducted, the 45% increase in commercial yield appears disproportionate and is likely an artifact of the study design. Manila clams are mobile and to a limited degree seek more favorable locations [18]. Because the yield response that occurred was largely the result of an increase in the number of commercial size clams, not the increase in size of mature clams, it is suspected that Manila clams moved out of the thick Z. japonica sites, into the more favored adjacent plots without Z. japonica. This movement of clams likely exaggerated the yield response demonstrated in short-term paired plot studies. A long-term study follow-ing the impact of colonization of a similar narrow-bladed nonnative eelgrass, Z. notlii, in France found that Ma-nila clams all but disappeared from fully colonized sites after five years [19].Overall, across an array of sites, years and experiments, the annual response for young clams and clam quality to seasonal removal of Z. japonica from commercial clam farms in Willapa Bay ranged from 15% to 25%. A similar effect was found at one site for Pacific oysters. These results concur with the one study previously done on the interaction between Z. japonica and Manila clams [6], but contrast with findings from other studies ex-amining the relationship between eelgrass and other clam species. Mercenaria mercenaria,for example, had higher growth rates inside the seagrass environment than open sand [20]. This difference in clam growth re-sponse to eelgrass is less likely the result of species differences in either clams or eelgrass, but one of vegetation patch size. Eelgrass vegetation has a hydrodynamic baffling effect [6] [21] [22]. This can have either a positive or negative effect on the availability of particulate food for suspension feeding depending on patch size and site location [14]. In sites with large expansions of bare sediment and small patches of eelgrass, the slowing of water flow over the eelgrass would result in localized settling of food for suspension feeding and, consequently, great-er growth in eelgrass compared to bare sediment [14] [22]. On the other hand, our studies were conducted under exact opposite conditions, small patches of bare sediment where the Z. japonica was removed in the midst of 100+ ha patches of solid Z. japonica. Under these conditions, the dense mats of Z. japonica reduced the flow of rich nutrient water flow over the surface sediment by up to 40% compared to nonvegetated mudflats [18]. Simi-lar flow data was reported by Patten et al. [23] using a Sontek Argonaut Acoustic Doppler Velocimeter stationed 5 cm above the sediment floor. They reported a mean current over a 3-day period of 0.7 cm sec−1 ±7.7 std. dev. and 3.8 cm sec−1 ± 3.9 std. dev. in 2009 and 2010, respectively, on clam beds covered with thick Z. japonica, compared to 3.3 cm sec−1 ± 11.3 std. dev. and 6.8 cm sec−1 ± 4.4 std. dev. for immediately adjacent 0.1 ha beds where the Z. japonica was controlled in those years. Boundary flow is an important determinant of growth rate of benthic suspension feeders, with faster bottom flow velocities leading to greater growth [24]. Ruesch and Wil-liams [25] report that food resources and mussel growth over a 7 month period were lower 1 and 5 cm above the sea floor within eelgrass patches than open sand flat, and that the effect was linearly associated with patch size. The long-term economic impact of Z. japonica on Manila clam farming is difficult to project based on these studies alone. Nevertheless, it can be estimated based on data from clam growth and harvest efficiency. The an-nual reduction in clam growth resulting from Z. japonica varies by clam age. For age class 1 to 3 years the mean reduction in growth was 27% per growing season. A conservative estimate of 15% decrease per year for these three age classes would result in a cumulative net difference in yield of 45%. On good production ground, after 3 to 5 years of growth the commercial yield of Manila clams in Willapa Bay ranges from 30,000 to 50,000 kg·ha−1.For the average yield, a 45% crop reduction would be 18,000 kg·ha−1. At a wholesale price of $5.50 kg−1, less $1.45 kg−1picking cost and $1.45 kg−1for production, cleaning and marketing, there would be a net loss of $46,000 ha−1 per harvest cycle based just on growth reduction. Additional losses due to differences in harvest efficiency also need to be considered. The presence of Z. japonica resulted in an 8% increase in the amount of clams missed by a commercial harvester. Although these clams are not permanently lost, their entire $4576 in market value ($2.6 kg−1 × 1760 kg·ha−1 in unpicked clams) would not be captured until the next harvest cycle. For a three-year harvest cycle, there would be $721 in lost interest if that capital was invested with a 5% annual rate of return, and $686 in clams lost to natural attrition of ~5% yr−1. This would result in a cumulative total net loss of ~$47,407 ha−1 for each harvest cycle of Manila clams on a Z. japonica-infested bed compared to a matched bed where the eelgrass was controlled.The economic impact of Z. japonica on Pacific oyster production is more difficult to assess. The tidal zone for oyster production is normally deeper than the Z. japonica range, and thus potential for a negative impact is much less likely than for Manila clams. In the situations where this overlap occurs there could be up to a 15% loss in oyster meat harvested on that site. A typical oyster bed is seeded at ~ 2500 bushels ha−1. When ready for harvest each bushel of oyster yields ~1.9 l of shucked meat, which wholesales for ~ $6.35 l−1. For 15% loss in meat this would be $4222 ha−1 in net returns to the grower for a 2 - 3 year harvest cycle. This value is conservative, as it does not include losses of nonsalable oysters that do not make grade because of poor condition. The commercial shucker of these oysters noted that oysters from the plots with nonnative eelgrass were not fat enough to make grade (Jolly Roger Oysters, personnel communication).These studies indicate that, without some type of management, invasive eelgrass is economically disadvanta-geous to shellfish growers. Management of Z. japonica with the herbicide imazamox, however, is not without risks. Direct effects on shellfish, the inability to market shellfish from treated beds, or damage to non-target spe-cies, including native eelgrass and oceanic phytoplankton, which are the food sources for shellfish, are concerns. Imazamox is food tolerance-exempt and has no direct effect on shellfish growth, as has been noted [26] [27]. Conditions which result in damage to off-site native Z. marina have been studied [28], and treatment protocols have been put in place to minimize this risk [7]. Imazamox is in the water column that could potentially affect phytoplankton. The dose exposure duration that would result from a large-scale treatment of imazamox would be well below that required to have any lasting effect [7] [28].5. ConclusionThe negative economic impact of Z. japonica to the shellfish farmer can be dramatic, particularly for Manila clams. Management of Z. japonica on shellfish beds through the use of the herbicide imazamox can help miti-gate for the expected crop losses. The use of an herbicide in an estuary, however, is controversial. These results are not likely to moderate the conflict between stakeholders with divergent ecological or economic priorities, but they do provide the solid evidence that concerns by the shellfish industry are justified. Additional studies that assess large-scale economic and long-term environmental impacts of Z. japonica and its potential management are warranted.AcknowledgementsThe author wishes to thank the Washington Department of Fish and Wildlife-Oyster Reserve Program for their funding.References[1]Bulthuis, D.A. (2013) Padilla Bay National Estuarine Research Reserve Technical Report No. 36, Science PresentationAbstracts from the Workshop on the Science and Management of Zostera japonica in Washington: A Meeting for State Agencies. Padilla Bay National Estuarine Research Reserve./programs/sea/aquaculture/pdf/scienceAbstracts.pdf[2]Shafer, D.J., Kaldy, J.E. and Gaeckle, J.L. (2014) Science and Management of the Introduced Seagrass Zostera japo-nica in North America. Environmental Management, 53, 147-162. /10.1007/s00267-013-0172-z[3]Williams S.L. (2007) Introduced Species in Seagrass Ecosystems: Status and Concerns.Journal of Experimental Ma-rine Biology and Ecology, 350, 89-110. /10.1016/j.jembe.2007.05.032[4]Bando K.J. (2006) The Roles of Competition and Disturbance in a Marine Invasion. Biological Invasions, 8, 755-763./10.1007/s10530-005-3543-4[5]Fisher, J.P., Bradley, T. and Patten, K.D. (2011) Invasion of Japanese Eelgrass, Zostera japonica in the Pacific North-west: A Preliminary Analysis of Recognized Impacts, Ecological Functions, and Risks./wp-content/uploads/2011/07/Final-Japonica-White-Paper-051811[6]Tsai, C.C., Ruesink, J.L., Trimble, A.C. and Yang, S. (2010) Interactions between Two Introduced Species: Zosterajaponica (Dwarf Eelgrass) Facilitates Itself and Reduces Condition of Ruditapes philippinarum (Manila Clam) on In- tertidal Flats. Marine Biology, 157, 1929-1936. /10.1007/s00227-010-1462-0[7]WA State Department of Ecology (2014) General Permit and Final Environmental Impact Statement: Management ofZostera japonica on Commercial Clam Beds in Willapa Bay, Washington./programs/wq/pesticides/eelgrass.html[8]Mach, M.E., Wyllie-Echeverria, S. and Ward, J.R. (2010) Distribution and Potential Effects of a Non-Native Seagrassin Washington State Zostera japonica Workshop, Friday Harbor Laboratories, San Juan Island, 37./Publications/aqr_zostera_study.pdf[9]Hickey, B.M. and Banas, N.S. (2003) Oceanography of the US Pacific Northwest Coastal Ocean and Estuaries withApplication to Coastal Ecology. Estuaries, 26, 1010-1031./10.1007/BF02803360[10]Feldman, K.L., Armstrong, D.A., Dumbauld, B.R., DeWitt, T.H. and Doty, D.C. (2000) Oysters, Crabs, and BurrowingShrimp: Review of an Environmental Conflict over Aquatic Resources and Pesticide Use in Washington State’s (USA) Coastal Estuaries. Estuaries, 23, 141-176. /10.2307/1352824[11]Banas N.S., Hickey B.M., Newton J.A. and Ruesink J.L. (2007) Tidal Exchange, Bivalve Grazing, and Patterns ofPrimary Production in Willapa Bay, Washington, USA. Marine Ecology Progress Series, 341, 123-139./10.3354/meps341123[12]Ruesink, J.L., van Raay, K., Witt, A., Herrold, S., Freshley, N., Sarich, A. and Trimble, A.C. (2014) Spatio-TemporalRecruitment Variability of Naturalized Manila Clams (Ruditapes philippinarum) in Willapa Bay, Washington, USA.Fisheries Research, 151, 199-204. /10.1016/j.fishres.2013.11.011[13]Johannessen, O.H. (1973) Population Structure and Individual Growth of Venerupis pullastra(Montagu) (Lamelli-branchia). Sarsia, 52, 97-116.[14]Lucas, A. and Beninger, P.G. (1985) The Use of Physiological Condition Indices in Marine Bivalve Aquaculture. Aq-uaculture, 44, 187-200.[15]Boström, C., Jackson, E.L. and Simenstad, C.A. (2006) Seagrass Landscapes and Their Effects on Associated Fauna: aReview. Estuarine, Coastal and Shelf Science, 68, 383-403. /10.1016/j.ecss.2006.01.026[16]Gribben, P., Wright, J., O’Connor, W. and Steinberg, P. (2009) Larval Settlement Preference of a Native Bivalve: TheInfluence of an Invasive Alga versus Native Substrata. Aquatic Biology, 7, 217-227./10.3354/ab00196 [17]Ruesink, J., Freshley, N., Herrold, S, Trimble, A. and Patten, K. (2014) Influence of Substrate Type on Non-NativeClam Recruitment in Willapa Bay, Washington, USA. Journal of Experimental Marine Biology and Ecology, 459, 23-30.[18]Humphreys, J., Caldow, R.W., McGrorty, S., West, A.D. and Jensen, A.C. (2007) Population Dynamics of NaturalisedManila Clams Ruditapes Philippinarum in British Coastal Waters. Marine Biology, 151, 2255-2270./10.1007/s00227-007-0660-x[19]Tu Do, V., de Montaudouin, X., Lavesque, N., Blanchet, H. and Guyard, H. (2011) Seagrass Colonization: Knock-OnEffects on Zoobenthic Community, Populations and Individual Health. Estuarine. Coastal and Shelf Science, 95, 458- 469. /10.1016/j.ecss.2011.10.022[20]Irlandi, E. and Peterson, C. (1991) Modification of Animal Habitat by large Plants: Mechanisms by which SeagrassesInfluence Clam Growth. Oecologia, 87, 307-318. /10.1007/BF00634584[21]Allen, B.J. and Williams, S.L. (2003) Native Eelgrass Zostera Marina Controls Growth and Reproduction of an Inva-sive Mussel through Food Limitation.Marine Ecology Progress Series, 254, 57-67./10.3354/meps254057[22]Peterson, C.H., Summerson, H.C. and Duncan, P.B. (1984) The Influence of Seagrass Cover on Population Structureand Individual Growth Rate of a Suspension-Feeding Bivalve, Mercenaria mercenaria. Journal of Marine Research, 42, 123-138. /10.1357/002224084788506194[23]Patten, K., Norelius, S., Haldeman, N., Rasmussen, K., Booth, S., Suhrbier, A., Fisher, J., Meaders, M., Raub, G.,Dumbauld, B. and McCoy, L. (2012) Impact of Japanese Eelgrass and its Potential Control Tactic, Imazamox, to Estu- arine Resources and Bivalve Aquaculture in Willapa Bay, Washington. Final Report to Washington Department of Fish and Wildlife—Willapa Oyster Reserve./shellfish/documents/finaljapaneseeelgrassreporttowdfwjuly2012。

Effect of Surfactants on the Interfacial Tension and Emulsion Formation between Water and Carbon Dioxide Sandro R.P.da Rocha,Kristi L.Harrison,and Keith P.Johnston*Department of Chemical Engineering,University of Texas,Austin,Texas78712Received July8,1998.In Final Form:October7,1998 The lowering of the interfacial tension(γ)between water and carbon dioxide by various classes of surfactants is reported and used to interpret complementary measurements of the capacity,stability,and average drop size of water-in-CO2emulsions.γis lowered from∼20to∼2mN/m for the best poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(propylene oxide)(PPO-b-PEO-b-PPO)and PEO-b-PPO-b-PEO Pluronic triblock copolymers,1.4mN/m for a poly(butylene oxide)-b-PEO copolymer,0.8mN/m for a perfluoropolyether (PFPE)ammonium carboxylate and0.2mN/m for PDMS24-g-EO22.The hydrophilic-CO2-philic balance (HCB)of the triblock Pluronic and PDMS-g-PEO-PPO surfactants is characterized by the CO2-to-water distribution coefficient and“V-shaped”plots of logγvs wt%EO.A minimum inγis observed for the optimum HCB.As the CO2-philicity of the surfactant tail is increased,the molecular weight of the hydrophilic segment increases for an optimum HCB.The stronger interactions on both sides of the interface lead to a lowerγ.Consequently,more water was emulsified for the PDMS-based copolymers than either the PPO-or PBO-based copolymers.IntroductionSupercritical fluid(SCF)carbon dioxide(T c)31°C,P c )73.8bar)is an environmentally benign alternative to organic solvents for waste minimization.It is nontoxic, nonflammable,and inexpensive.However,because of its very low dielectric constant, ,and polarizability per volume,R/v,CO2is a poor solvent for most nonvolatile lipophilic and hydrophilic solutes.1It may be considered a third type of condensed phase,different from lipophilic and hydrophilic phases.Consequently,it is possible to disperse either lipophilic or hydrophilic phases into CO2, in the form of microemulsions,emulsions,and latexes, given an appropriate surfactant.Because of the low values of and R/v for CO2,the most CO2-philic types of functional groups have low cohesive energy densities,e.g.,fluoro-carbons,fluoroethers,and siloxanes.2-6The solvent strength of carbon dioxide may be understood by the fact that the solubility of a polymer in carbon dioxide is highly correlated with the surface tension of the pure polymer melt.7For example,poly(fluoroacrylates)with low surface tensions of10-15mN/m are highly soluble,whereas poly-(dimethylsiloxanes)with surface tensions of20mN/m are moderately soluble,and hydrocarbon polymers with higher surface tensions show very low solubility.For nonpolar or slightly polar polymers,the surface tension is a measure of the van der Waals forces and is related to the cohesive energy density.Because R/v is so small for CO2,polymers with low cohesive densities and surface tensions are the most soluble.The first generation of research involving surfactants in SCFs addressed reverse micelles and water-in-SCF microemulsions,for fluids such as ethane and propane8,9 as reviewed recently.10,11Microemulsions are thermody-namically stable and optically transparent,with typical droplet diameters of about2-10nm.The mechanistic insight gained from these studies of phase equilibria, interfacial curvature,and droplet interactions in a su-percritical fluid is directly applicable to carbon dioxide. Attempts to form water-in-CO2(w/c)microemulsions have been elusive.6,12,13For PFPE COO-NH4+w/c microemul-sions,FTIR,UV-visible absorbance,fluorescence,and electron paramagnetic resonance(EPR)experiments have demonstrated the existence of an aqueous domain in CO2 with a polarity approaching that of bulk water,14as has also been shown by small-angle neutron scattering (SANS).15Organic-in-CO2microemulsions have also been formed for600molecular weight poly(ethylene glycol) (PEG600)and for polystyrene oligomers.16,17In many previous studies,surfactant activity in CO2has been characterized in terms of water uptake into a CO2 microemulsion.Since the results were negative most of the time,it has been difficult to determine how to design surfactants to the water-CO2interface.A more direct property,such as the interfacial tension,is needed to understand the activity of surfactants at various interfaces containing carbon dioxide.In SCF systems,only a few studies have measured the interfacial tension(γ)even for simple binary systems(1)O’Shea,K.;Kirmse,K.;Fox,M.A.;Johnston,K.P.J.Phys.Chem. 1991,95,7863.(2)McHugh,M.A.;Krukonis,V.J.Supercritical Fluid Extraction: Priciples and Practice,2nd ed.;Butterworth:Stonham,MA,1994.(3)Hoefling,T.A.;Newman,D.A.;Enick,R.M.;Beckman,E.J.J. Supercrit.Fluids1993,6,165-171.(4)Newman,D.A.;Hoefling,T.A.;Beitle,R.R.;Beckman,E.J.; Enick,R.M.J.Supercrit.Fluids1993,6,205-210.(5)DeSimone,J.M.;Guan,Z.;Elsbernd,C.S.Science1992,257, 945.(6)Harrison,K.;Goveas,J.;Johnston,K.P.;O’Rear,ngmuir 1994,10,3536.(7)O’Neill,M.L.;Cao,Q.;Fang,M.;Johnston,K.P.;Wilkinson,S. P.;Smith,C.D.;Kerschner,J.;Jureller,S.Ind.Chem.Eng.Res.1998, 37,3067-3079.(8)Fulton,J.L.;Smith,R.D.J.Phys.Chem.1988,92,2903-2907.(9)Johnston,K.P.;McFann,G.;Lemert,R.M.Am.Chem.Soc.Symp. Ser.1989,406,140-164.(10)Bartscherer,K.A.;Minier,M.;Renon,H.Fluid Phase Equilib. 1995,107,93-150.(11)McFann,G.J.;Johnston,K.P.In Microemulsions:Fundamental and Applied Aspects;Kumar,P.,Ed.;Dekker:New York,1998;Vol.in press.(12)Iezzi,A.;Enick,R.;Brady,J.Am.Chem.Soc.Symp.Ser.1989, No.406,122-139.(13)Consani,K.A.;Smith,R.D.J.Supercrit.Fluids1990,3,51-65.(14)Johnston,K.P.;Harrison,K.L.;Clarke,M.J.;Howdle,S.M.; Heitz,M.P.;Bright,F.V.;Carlier,C.;Randolph,T.W.Science1996, 271,624-626.(15)Zielinski,R.G.;Kline,S.R.;Kaler,E.W.;Rosov,ngmuir 1997,13,3934-3937.419Langmuir1999,15,419-428including carbon dioxide and a liquid phase.18-20None of these studies included a surfactant.Surfactants have been studied for the generation of CO2foams in water21typically for water-soluble surfactants.The effects of various surfactants on theγbetween supercritical CO2and PEG (600MW)were reported recently.16At276bar,the addition of1%PFPE COO-NH4+reducesγfrom3.2to2.1mN/m, and the interfacial area of the surfactant is437Å2/ molecule.Interfacial tension measurements have also been made between poly(2-ethylhexyl acrylate)(PEHA)and CO222and styrene oligomers and CO2.23As is well-known for water-in-oil(w/o)emulsions and microemulsions,the phase behavior,γ,and curvature are interrelated,as shown in Figure1.24A minimum inγis observed at the phase inversion point where the system is balanced with respect to the partitioning of the surfactant between the phases.25,26Upon change of any of the formulation variables away from this point,for example,the temperature or the hydrophilicity/hydro-phobicity ratio(in our case the hydrophilic/CO2-philic ratio),the surfactant will migrate toward one of the phases. This phase usually becomes the external phase,according to the Bancroft rule.27Unlike the case for conventional solvents,a small change in pressure or temperature can have a large influence on the density and thus on the solvent strength of a supercritical fluid.By“tuning”the interactions between the surfactant tail and the solvent,it becomes possible to manipulate the phase behavior,and therefore the activity of the surfactant at the interface and curvature,and also the extension of the surfactant tails.As an example of pressure tuning,a water-in-propane microemulsion is inverted to a propane-in-water microemulsion by varying the pressure by50bar in the C12EO6/brine/propane system, at constant temperature.28This system undergoes a phase inversion density,by analogy with the phase inversion temperature,for conventional systems.If the density is changed so that the surfactant prefers either phase over the other,the surfactant is less interfacially active and γincreases.16,22,23The objective of this study is to achieve a fundamental understanding of the lowering of the water-CO2inter-facial tension by different classes of surfactants and to use this knowledge to explain the formation and stability of water-in-CO2(w/c)emulsions.The surfactants include PFPE COO-NH4+,Pluronic R(PPO-b-PEO-b-PPO)and Pluronic L(PEO-b-PPO-b-PEO)triblock copolymers,poly-(butylene oxide-b-ethylene oxide)(PBO-b-PEO),and poly-(dimethylsiloxane)(PDMS)copolymers with PEO-PPO grafts(PDMS-g-PEO-PPO).Fromγmeasurements ver-sus concentration,the adsorption is investigated for PFPE COO-NH4+and used to determine the critical micro-emulsion concentration.For the PPO-and PDMS-based surfactants,the concept of a hydrophilic-CO2-philic bal-ance(HCB)is introduced by relatingγand the distribution coefficient of the surfactant to the EO fraction(see Figure 1).To understand howγand the HCB influence colloid stability,we chose to study w/c emulsions in contrast to previous studies of microemulsions,since so few of these surfactants form microemulsions.Emulsions are ther-modynamically unstable,but may be kinetically stable, with droplets from100nm to several micrometers in diameter.The presence of the surfactant at the interface lowers theγand thus the Laplace pressure,reducing the energy necessary to deform the interface.29The emulsions may be stabilized against flocculation due to van der Waals forces by steric stabilization,as has been analyzed theoretically,30-33and/or Marangoni stresses,due to gradients in interfacial tension at the interface.To characterize emulsion capacity,stability,and the average droplet size of the emulsions,an in-situ turbidity technique has been applied in addition to visual observations.The ability to design surfactants for the interface between CO2 and an aqueous phase based upon knowledge of the relationship between colloid formation and stability,phase behavior,andγis of interest for a wide variety of heterogeneous reactions and separation processes in CO2. Examples include dry cleaning,extraction with micro-(16)Harrison,K.L.;Johnston,K.P.;Sanchez,ngmuir1996, 12,2637-2644.(17)McClain,J.B.;Betts,D.E.;Canelas,D.A.;Samulski,E.T.; DeSimone,J.M.;Londono,J.D.;Cochran,H.D.;Wignall,G.D.;Chillura-Martino,D.;Triolo,R.Science1996,274,2049.(18)Heurer,G.Ph.D.Thesis,The University of Texas at Austin, 1957.(19)Chun,B.-S.;Wilkinson,G.T.Ind.Eng.Chem.Res.1995,34, 4371-4377.(20)Schiemann,H.;Wiedner,E.;Peter,S.J.Supercrit.Fluids1993, 6,181-189.(21)Lee,H.O.;Heller,J.P.;Hoefer,A.M.W.SPE Reservoir Eng. 1991,11,421-428.(22)O’Neill,M.;Yates,M.Z.;Harrison,K.L.;Johnston,P.K.;Canelas,D.A.;Betts,D.E.;DeSimone,J.M.;Wilkinson,S.P.Macromolecules1997,30,5050-5059.(23)Harrison,K.L.;da Rocha,S.R.P.;Yates,M.Z.;Johnston,K. P.;Canelas,D.;DeSimone,ngmuir1998,14,6855-6863.(24)Aveyard,R.;Binks,B.P.;Clark,S.;Fletcher,P.D.I.J.Chem. Technol.Biotechnol.1990,48,161-171.(25)Bourrel,M.;Schechter,R.S.Microemulsions and Related Systems:Formulation,Solvency and Physical Properties;Marcel(27)Ruckentein,ngmuir1996,12,6351-6353.(28)McFann,G.J.;Johnston,ngmuir1993,9,2942.(29)Walstra,P.Chem.Eng.Sci.1993,48,333-349.(30)Peck,D.G.;Johnston,K.P.Macromolecules1993,26,1537.(31)Meredith,J.C.;Johnston,K.P.Macromolecules1998,31,5507-5555.(32)Meredith,J.C.;Sanchez,I.C.;Johnston,K.P.;Pablo,J.J.d.Figure1.Schematic representation of phase behavior andinterfacial tension for mixtures of water,CO2,and nonionicsurfactants as a function of formulation variables.420Langmuir,Vol.15,No.2,1999da Rocha et al.emulsions and emulsions,phase transfer reactions,34,35and emulsion polymerization.36Experimental SectionMaterials.All of the surfactants were used as received,unless indicated.The CF 3O(CF 2CF(CF 3)O)∼3CF 2COO -NH 4+(PFPE COO -NH 4+),a gift from A.Chittofrati,37was stored in a desiccator.The single tail Krytox-sulfate,R -COOCH 2CH 2OSO 3--Na +,where R )CF 3(CF 2CF(CF 3)O)n CF 2CF 2-,and the triple tail Krytox-sorbitol surfactants were synthesized by E.Singley and Dr.E.J.Beckman at the University of Pittsburgh.38Pluronic L,PEO-b -PPO-b -PEO (PEO -PPO -PEO),and Pluronic R,PPO-b -PEO-b -PPO (PPO -PEO -PPO),surfactants were a gift from BASF.The block copolymer PEO-b -PBO (EO 15-BO 12,SAM185)(where the subscripts indicate the number of repeat units of each moiety)was provided by Pittsburgh Paint and Glass.The surfactant (CH 3)3SiO[Si(CH 3)2O]20[Si(CH 3)(R)]2OSi(CH 3)3,with graft R )(CH 2)3O(C 2H 4O)∼11H,(PDMS 24-g -EO 22),M w ∼2600,was a gift synthesized by Unilever.7SILWET L-7500(M w )3000),(CH 3)3SiO(Si(CH 3)2O)x (Si(CH 3)(R))y OSi(CH 3)3,with R )(CH 2)3O-(C 3H 6O)n Bu (PDMS 11-g -PO 39),with n ,x ,and y not specified,and SILWET L-7622(M w )10000),with a similar backbone,but R )(CH 2)3O(C 2H 4O)m Me (PDMS 105-g -EO 68),were provided by OSi Specialties,Inc.ABIL B 8851(M w ∼6000),(CH 3)3SiO(Si-(CH 3)2O)22(Si(CH 3)(R)O)4Si(CH 3)3,with R )(CH 2)3O(C 2H 4O)∼17-(C 3H 6O)∼4H (PDMS 28-g -EO 67-PO 17),and ABIL B 88184(M w ∼13000),(CH 3)3SiO(Si(CH 3)2O)73(Si(CH 3)(R)O)4Si(CH 3)3,with R ∼(CH 2)3O(C 2H 4O)∼32(C 3H 6O)∼7H (PDMS 79-g -EO 126-PO 28)were obtained from Goldschmidt AG.PDMS homopolymer with a M w of 13000was synthesized by J.M.DeSimone at U.N.Carolina.Poly(ethylene glycol)with a molecular weight of 600was obtained from Polysciences,Inc.Poly(butylene glycol)monoether,composed of an ethylene oxide backbone with an ethyl side group (PBO,800g/mol)was supplied by Air Products.Poly(propylene glycol)(1025g/mol)was obtained from Polysciences,Inc.,and used as received.Deionized water (NANOpureII;Barnstead)and instrument grade carbon dioxide (99.99%)were used for all experiments.Phase Behavior.Phase boundaries were determined in the variable-volume view cell as described in further detail else-where.7For a given weight of surfactant and CO 2,the pressure of the system was increased until a single phase was observed in the view cell.The pressure was then decreased slowly until the solution became slightly turbid.The pressure was then increased again,and the process was repeated.The pressure where the system became turbid was classified as the cloud point pressure.The pressure and temperature were measured to (0.2bar and (0.1°C,respectively.Interfacial Tension Measurements.The tandem variable-volume pendant drop tensiometer described previously 16was used to measure the interfacial tension between CO and water (γ).The apparatus consisted of two variable volume view cells (the drop phase cell and the measurement cell (continuous phase cell)),an optical rail for proper alignment,a light source,a video camera,and a computer.The drop phase cell contained water saturated with an excess amount of pure CO 2,and the continuous phase cell contained CO 2and surfactant (if present).In this configuration,the surfactant only has to diffuse short distances in the small volume of the droplet phase.Pendant drops were formed on the end of a stainless steel or PEEK capillary tube with an inside diameter ranging from 0.01to 0.03in.Once a suitable drop was formed,the six-port switching valve connecting the two cells was closed and timing of the drop age was started.Several images were recorded as a function of drop age.Images of the drop were obtained in a tagged imagefile format (TIFF)and the edge of the drop was extracted from data at various global threshold values using a C ++program.From the shape of the interface,the γmay be obtained from the Laplace equationwhere ∆P is the pressure differential across the interface,R 0is the radius of curvature at the apex of the drop,and z is the vertical distance from the apex.A set of three first-order differential equations was used to express Laplace’s equation,and a computer program 39,40was used to solve for γ.The density difference between the two phases was calculated by using an equation of state for pure CO 241and steam tables for pure water.The aqueous phase density was assumed to change less than 0.0025g/cm 3for the concentrations of surfactant studied.Emulsion Formation,Stability,and Average Droplet Size Estimation.Figure 2shows a schematic representation of the experimental apparatus,similar to a previous version,for turbidimetric measurement and visual observation of emulsion formation and stability.22The system consists of a 28-mL variable-volume view cell,an optical cell (0.1cm path length)which was mounted in a spectrophotometer (Cary 3E UV -vis),a high-pressure reciprocating pump (minipump with a flow rate of 8-80mL/min),and a manual pressure generator (High-Pressure Equip.,model 87-6-5).A six-port switching valve (Valco Instru-ments Co.,Inc.)with an external sampling loop was used to add water to the system.The pressure was monitored to (0.2bar with a strain gauge pressure transducer (Sensotec),and the temperature was controlled to within (0.1°C.Surfactant was initially loaded into the view cell,and the desired amount of CO 2was added with the pressure generator.The pressure was increased,and the system equilibrated at the desired T ,for ∼2h,by using a magnetic stir bar.The cloud point of the surfactant was obtained as described above.The solution was then recirculated,and deionized water was injected into the system via the 150-µL sample loop in the switching valve.The solution was sheared through a 130µm i.d.×50mm long stainless steel capillary tube upstream of the optical cell.Emulsion formation and stability were characterized based upon turbidity measurements versus time (t )at a constant wavelength (λ)650nm)and also visual observation.The turbidity is a measure of the reduction in transmitted intensity,τ)(1/l )ln(I 0/I ),where l is the path length and I 0and I are the incident and transmitted intensities,respectively.After the injection of each increment of water,the emulsion was stirred and recirculated for ∼20min (approximate time required for the absorbance to reach a maximum value).Immediately after recirculation and stirring were stopped,τmeasurements started.The stability was assessed from τas a function of t ,while the(34)Jacobson,G.B.;Lee,C.T.;daRocha,S.R.P.;Johnston,.Chem.,in press.(35)Jacobson,G.B.;Lee,C.T.;Johnston,.Chem.,in press.(36)Adamsky,F.A.;Beckman,E.J.Macromolecules 1994,27,312-314.(37)Chittofrati,A.;Lenti,D.;Sanguineti,A.;Visca,M.;Gambi,C.M.C.;Senatra,D.;Zhou,Z.Prog.Colloid Polym.Sci.1989,79,218-(39)Jennings,J.W.;Pallas,ngmuir 1988,4,959-967.Figure 2.Apparatus for emulsion formation and turbidimetry measurement.∆P )2γ/R 0+(∆F )gz(1)Surfactant Effect on Interfacial Tension Langmuir,Vol.15,No.2,1999421effective average droplet size was determined fromτversusλ.For a monodisperse system of nonabsorbing spheres in theabsence of multiple scatteringτis given byτ)3K*φ/2D,42where φis the dispersed phase volume fraction,D is the droplet diameter, and K*is the scattering coefficient.According to Mie theory,Κ*is a complex function of R(R∼D/λ,whereλis the wavelengthof the incident light)and m the ratio of the refractive indices ofthe dispersed and continuous phases.The refractive indices wereapproximated by those of the pure components,water(1.333)and CO2.43By evaluation of turbidities at two wavelengths,theaverage droplet size can be determined by an iteration proce-dure.44Results and DiscussionInterfacial Tension of the CO2-Water Binary System.The interfacial tension between pure CO2and water is shown in Figure3for two temperatures as a function of pressure,along with the data of Heurer18and Chun and Wilkinson.19Our interfacial tensions were measured1h after drop formation.Theγvalues obtained by Chun and Wilkinson19were measured with the capillary rise technique.Whereas local equilibrium was achieved within the capillary tube,the entire system was not at equilibrium.Heurer used the pendant drop technique; however,the values reported were obtained from the drop profile within10s of drop formation.Therefore,the lower values ofγin the present study suggest a closer approach to true equilibrium.A simple physical picture may be used to explain the behavior for most of the pressure range studied.16At pressures below70bar,γdecreases with increasing pressure.The cohesive energy density or free energy density of CO2is well below that of water at all pressures. The density and free energy density of CO2change over a wide range with pressure,whereas the values for essentially incompressible water are constant.As the density of the CO2phase increases,its free energy density becomes closer to that of water,andγdecreases.At low pressures where the density and free energy density change a great deal with pressure,the decrease inγis pronounced.At high pressures,where CO2is more “liquidlike”,it is much less compressible and the decrease inγwith pressure is small.For the CO2-PEG600interface,γwas predicted quantitatively with a gradientmodel and the lattice fluid equation of state.16The latticefluid model is less applicable for water due to thecomplexities resulting from hydrogen bonding and car-bonic acid formation.A cusp in the curve ofγversus pressure is observed attemperatures and pressures near the critical point of CO2.The region of the cusp inγshifts to slightly higherpressures as the temperature is increased above the criticaltemperature of CO2.For supercritical temperatures,themagnitude of the cusp increases as the temperature isdecreased toward the critical temperature.At25,1935,and38°C,the cusp in the interfacial tension is verynoticeable,while it becomes small at45°C and is notvisible at71°C.18The following argument explains how the cusp is relatedto the large compressibility of CO2.An upward pointingcusp has been observed for the surface excess of ethyleneon graphitized carbon black.45The excess adsorption canbe defined in terms of the density of the bulk phase andthe density of the interfacial region46where F(z)is the molar density of the fluid at a distancez from the surface.At pressures below the critical pressureregion,F(z)can be much larger than F,due to attractionof solvent to the surface,leading to a largeΓex.At higherpressures,the bulk fluid is much denser,so that thedifference between F(z)and F is much smaller resultingin a smallerΓex.As temperature increases above thecritical temperature of the solvent,the tendency of thesurface to raise F(z)to“liquidlike”densities diminishesandΓex decreases.Similar arguments apply to theadsorption of CO2at the water-CO2interface.TheenhancedΓex is manifested as the downward cusp inγ.Inboth examples,the cusps become broader and shift tohigher pressures at higher temperatures.Similar behavioris observed for peaks in plots of the isothermal compress-ibility of pure CO2versus pressure at constant temper-ature.To put the above results in perspective,new interfacialtension data are shown for the PEG600-CO2interface tocomplement earlier data16only at45°C(Figure4).Thevalues ofγfor the water-CO2interface are considerablylarger than those for the PEG600-CO2,PS(M n)1850),23CO2-PEHA(M n)32k)interfaces.22This result is dueprimarily to the much larger surface tension of water,∼72mN/m,versus that of PEG,∼35mN/m,and PEHA, 30mN/m.However,it is interesting thatγbetween CO2and water at high pressures,20mN/m,is below that forwater-hydrocarbon interfaces.For heptane and octane,the hydrocarbon-waterγis about50mN/m.This lower γis consistent with the higher miscibility between CO2 and water47versus hydrocarbons and water.The stronger interactions between CO2and water versus hydrocarbons and water are due to the small size of CO2which causes a smaller penalty in hydrophobic hydration,CO2’s quad-rupole moment,and,finally,Lewis and Bronsted acid-base interactions.Over the entire pressure range for PEG600-CO2at25and45°C,the interfacial tension decreased monotonicallywith increasing pressure,unlike the case for CO2-water(42)Yang,K.C.;Hogg,R.Anal.Chem.1979,51,758-763.(43)Burns,R.C.;Graham,C.;Weller,A.R.M.Mol.Phys.1986,59,(45)Findenegg,G.H.In Fundamentals of Adsorption;Myers,A.L., Belfort,G.,Eds.;Engineering Foundation:New York,1983;p207.Figure3.Interfacial tension at the CO2-water interface asa function of pressure at various temperatures.Γex≡∫(F(z)-F bulk)d z(2) 422Langmuir,Vol.15,No.2,1999da Rocha et al.at 35°C.The lack of a dip near the critical pressure may be due to the much lower compressibility at 25and 45°C versus 35°C.This contrast in behavior may also be due to a difference in the density gradient and thickness in the interfacial region for the two systems,for example,greater miscibility for the CO 2-PEG600system.Interfacial Tension:PFPE Ammonium Carboxy-late.The addition of small amounts of PFPE COO -NH 4+decreases γsubstantially as shown at 45°C and 276bar in Figure 5.As the concentration is raised above 0.03%surfactant,a discontinuity is observed,and the magnitude of the slope becomes much smaller.Because it has been shown that w/c microemulsions are formed in this system,14the discontinuity can be attributed to a critical microemulsion concentration (c µc)for the PFPE COO --NH 4+surfactant,as has been done for oil -water inter-faces.24At concentrations above the c µc,the less negative slope is caused by the addition of surfactant primarily to adsorption at the pendant drop interface,the change in γis reduced.The adsorption obtained from the Gibbs’adsorption equationfor the PFPE COO -NH 4+surfactant was 1.77×10-10mol/cm 2,which corresponds to a surface coverage of ∼100Å2/molecule.Such a high surface coverage is sufficient for the formation of microemulsions.A comparable value of ∼140Å2/molecule was measured by Eastoe et al.48at 500bar and 25°C for the hybrid hydrocarbon -fluorocarbon C 7F 15CH(OSO 3-Na +)C 7H 15surfactant in CO 2.This value was determined by assuming that all the surfactant is adsorbed at the interface of spherical droplets of 25Å2radius,as measured by SANS,with a polydispersity of ∼0.2.The substantial reduction in γand relatively high surfactant adsorption explain why it was possible to form a w/c microemulsion with PFPE COO -NH 4+.The same surfactant had an absorption of 400Å2/molecule at the CO 2-PEG interface.16Phase behavior studies indicated that PEG-in-CO 2microemulsions are also formed with this surfactant,but the nature of the core has not been characterized.16Interfacial Tension:Fluoroether Sulfate and Sorbitol Surfactant.The phase behavior of fluoroether sulfates and fluoroether sorbitols was measured by Singley et al.38for various molecular weights of single-,twin-,and triple-tailed surfactants.The surfactants were soluble in CO 2at 33°C and moderate pressure (<300bar).The sorbitol surfactants were found to be more soluble in CO 2than the sulfate ones,as expected due to the low solubilities of ions in CO 2,because of its low dielectric constant.The results showed that branching depresses the cloud point curve of a surfactant until the solubility becomes domi-nated by the overall molecular weight.These surfactants were used to form CO 2-in-water and middle-phase emul-sions with excess CO 2and water.38The interfacial tension was measured at the water -CO 2interface for the single-tailed M w 2500sulfate and the triple-tailed (7500g/mol total)sorbitol surfactants.Our measured cloud point for the 1.4%(w/w)CO 2sorbitol surfactant was 215.6bar at 45°C.For 0.56%sulfate surfactant,it was 139.8bar at 45°C.The sulfate surfactant did not lower the interfacial tension significantly over the pressure range of 180-283bar 45°C at a concentration of 0.56%.The interfacial tension was difficult to determine accurately,because bubbles and possibly surfactant precipitate appeared on the surface of the pendant drop within 15min of drop formation.The interfacial tension was estimated to be ∼15mN/m by using manual edge detection of the pendant drop.For the sorbitol surfactant,the interfacial tension decreased to ∼5.5mN/m at 276bar and 45°C with a concentration of 1.4%.Relative to other surfactants reported in this study,these surfactants were less successful in lowering the interfacial tension.Interfacial Tension:PPO -PEO -PPO,PEO -PPO -PEO,and PBO -PEO Surfactants.Block co-polymers containing CO 2-philic and hydrophilic (CO 2-phobic)functional groups may be designed to be active at the CO 2-water interface.In this section,the CO 2-philic blocks are poly(propylene oxide)and poly(butylene oxide),while the CO 2-phobic block is poly(ethylene oxide).TheFigure 4.Interfacial tension for the PEG600-CO 2interface at varioustemperatures.Figure 5.Interfacial tension for the water -CO 2-PFPE COO -NH 4+system at 45°C and 276bar.The dotted line is used to determine the surfactant adsorption via the Gibbs adsorption equation.A discontinuity is present at the critical micromemulsion concentration.Γ2)-1RT (d γd ln c 2)T ,P(3)Surfactant Effect on Interfacial Tension Langmuir,Vol.15,No.2,1999423。

Dyeing, Printing & Finishing By Warren S. Perkins, Technical Editor Surfactants -A PrimerA n i n -d e p t h d i s c u s s i o n o ft h e b e h a v i o r o f c o m m o nt y p e s o f s u r f a c t a n t s.lT he term surfactant is derived from the words surfaceactive agent. Surfactants provide remarkable benefits inmany textile wet processes. A surface active chemical isone which tends to accumulate at a surface or interface. Aninterface is the area of contact between two substances.Where the interface is between two substances not in thesame phase, the interface is usually called a surface. Clearly,the chemical processes that take place at the solid/liquid sur-face between textile fibers and water often determine the suc-cess or failure of the process.Examples of important events in textile chemical processesthat involve interaction of surfaces include wetting, dispers-ing, emulsification, chemical or dye adsorption on fibers,adhesion, vaporization, sublimation, melting, heat transfer,catalysis, foaming and defoaming. Specific functions of sur-face active agents include removing soil (scouring), wetting,rewetting, softening, retarding dyeing rate, fixing dyes, mak-ing emulsions, stabilizing dispersions, coagulating suspendedsolids, making foams, preventing foam formation anddefoaming liquids.The surface tension of a liquid is an internal pressurecaused by the attraction of molecules below the surface forthose at the surface of a liquid. This molecular attraction cre-ates an inward pull, or internal pressure, which tends torestrict the tendency of the liquid to flow and form a largeinterface with another substance.The surface tension (or inter-facial tension if the interface isnot a surface) determines the tendency for surfaces to estab-lish contact with one another. Therefore, surface tension isresponsible for the shape of a droplet of liquid. If the surfacetension is high, the molecules in the liquid are greatly attract-ed to one another and not so much to the surrounding air.If the droplet of water is in contact with a solid such as a fabric, its shape will also be affected by the surface tension at the solid/liquid interface. If the surface tension in the liquid is lower, the droplet forms a more ellipsoidal shape.The following are the surface tensions for some liquid sub-stances:SUBSTANCE SURFACE TENSION water 73 dynes/cm m e r c u r y 480 dynes/cm benzene 28 dynes/cm ethanol 22 dynes/cm Because of its lower surface tension, ethanol will flow and form a larger area of contact (surface) with a solid than with water. Mercury, with its very high surface tension, does not flow but breaks into droplets if given the opportunity.Surface active agents interfere with the ability of the mole-cules of a substance to interact with one another and, thereby,lower the surface tension of the substance. Surfactants used in industrial applications usually cause a dramatic decrease in surface tension when used at low concentration.Chemically, surfactants are amphipathic molecules. That is, they have two distinctly different characteristics, polar and non polar, in different parts of the same molecule. Therefore,a surfactant molecule has both hydrophilic (water-loving) and hydrophobic (water-hating) characteristics. Symbolically, a surfactant molecule can be represented as having a polar “head” and a non polar "tail" as shown below.non polar “tail”polar “head”The hydrophobic group in a surfactant for use in aqueous medium is usually a hydrocarbon chain but may be a fluoro-carbon or siloxane chain of appropriate length. The hydrophilic group is polar and may be either ionic or nonionic.Since surfactant molecules have both hydrophilic and hydrophobic parts, the most attractive place for them in water is at the surface where the forces of both attraction and repul-sion to water can be satisfied. One other way that surfactants interact to satisfy natural forces of attraction and repulsion between molecules is by formation of micelles. Surfactant molecules aggregate in water forming micelles (see Figure I).Micelles consist of hydrophobic interior regions, where hydrophobic tails interact with one another. These hydropho-AT1 August 1998 51Figure I. Schematic representation of surfactant molecules at surface and surfactant micelle in hulk liquid.(From “Textile Coloration andFinishing,” Carolina Academic Press,Durham, N.C.)bic regions are surrounded by the hydrophilic regions where the heads of the surfactant molecules interact with water.At very low concentration in water,surfactant molecules are unassociated.At higher concentration of surfactant in water, micelles form, The concentration at which micelles form is called the critical micelle concentration (CMC).The surface tension of water undergoes a precipitous decrease, and the deter-gency of the mixture increases dramati-cally at the CMC.Types (Classes) Of Surfactants Surfactants fall in the following clas-sifications according to the nature of the hydrophilic group:• anionic: hydrophilic head is nega-tively charged;• cationic: hydrophilic head is posi-tively charged;• nonionic: hydrophilic head is polar but not fully charged; and• amphoteric: molecule has both potential positive and negative groups;charge depends on pH of the medium.CarboxylatesAnionic surfactants are the most widely used of the four classes.Important types of anionic surfactants are carboxylates, sulfonates, sulfates and phosphates.Most carboxylate surfactants are soaps. Soaps are alkali metal salts of fatty acids. Fatty acids are carboxylic acids derived from or contained in ani-mal or vegetable fats or oils. They con-tain linear hydrocarbon groups and may be either saturated of unsaturated. The 52 August 1998 ATI Those with less than 10 carbons are too soluble in water to have good sur-face activity. Those with more than 20carbons in a linear configuration are too insoluble in water to use in aqueous medium.Sodium is the most common cation in soap. But potassium and ammonium are also common. Soaps are effective as cleaning agents in aqueous medium.Since soaps are relatively weak acids,the free acid is liberated in acidic medi-um. The free acids are insoluble in water. Therefore, soaps are only effec-tive in alkaline medium.Soaps can be made by neutralization of free fatty acids by alkali metals hydroxides by alkaline hydrolysis (saponification) of fats and oils (see Figure 2). Fats and oils belong to the lipid family. The chemistry of oils as used in making soaps is identical to that alkyl, aryl, or alkylaryl hydrophobe.Since the sulfonate group is a strong acid, the sulfonate surfactants are solu-ble and effective in acidic as well as in alkaline medium.The calcium and magnesium salts are soluble in water, so sulfonate sur-factants are not greatly affected by hard water. The sodium salt sulfonate surfac-tants are soluble and effective even in the presence of electrolytes such as sodium chloride and sodium sulfate.Since the sulfonate surfactants are resistant to hydrolysis by both hot acid and alkali, they are very useful for tex-tile scouring formulations. Since sul-fonation is relatively inexpensive, sul-fonate surfactants are found in high-vol-ume products. Sulfonate surfactants include alkysulfonates, alkylbenzene-sulfonates, lignin sulfonates, naphthale-nesulfonates and petroleum sulfonates.Lignin is a byproduct of paper man-ufacture. Sulfonated lignin is a very good dispersing agent for solids in water and finds textile applications mainly as a dispersing agent in special-ty chemicals and dyes. Lignin sul-fonates are unsuitable for many applica-tions because of their dark color and because they do not produce much low-ering of the surface tension of water.Esters of sulfosuccinic acid, such asglycerol tristearate (a fat)glycerolFigure 2.of fats. Fats are solid. Oils are liquid.dioctyl (2-ethylhexyl) sulfosuccinate Generally, lipids with more saturated (DOSS), are excellent fast-wetting sur-hydrocarbon content are more firm and factants. Sulfosuccinate ester surfac-have higher melting temperatures than tants are very soluble in water. They do those with unsaturated hydrocarbon not emulsify oils so they are not good groups. Fats are esters of the trihydric scouring agents. They are soluble in alcohol, glycerol. Fatty acids are pro-organic solvents making them useful in duced by alkaline hydrolysis (saponiti-dry cleaning. They are not acceptable for cation) of fats. The soap (fatty acid some aqueous applications since they are solid) thus formed is separate from the hydrolyzed by hot acid or alkali.glycerol byproduct by neutralization of the alkali or addition of salt to precipi-Sulfates tate the soap.Various fatty alcohols can be reacted with chlorosulfonic acid or sulfur triox-Sulfonates ide to produce their sulfuric acid esters.The sulfonate group is an effective The properties of these surfactants solubilizing group when attached to an depend on the alcohol chain length as。

专业英语词汇accordion 手风琴activation 活化（作用）addition polymer 加成聚合物，加聚物aggravate 加重，恶化agitation 搅拌agrochemical 农药，化肥Alfin catalyst 醇（碱金属）烯催化剂align 排列成行aliphatic 脂肪（族）的alkali metal 碱金属allyl 烯丙基aluminum alkyl 烷基铝amidation 酰胺化（作用）amino 氨基，氨基的amorphous 无定型的，非晶体的anionic 阴（负）离子的antioxidant 抗氧剂antistatic agent 抗静电剂aromatic 芳香（族）的arrangement （空间）排布，排列atactic 无规立构的attraction 引力，吸引backbone 主链，骨干behavior 性能，行为biological 生物（学）的biomedical 生物医学的bond dissociation energy 键断裂能boundary 界限，范围brittle 脆的，易碎的butadiene 丁二烯butyllithium 丁基锂calendering 压延成型calendering 压延carboxyl 羧基carrier 载体catalyst 催化剂，触媒categorization 分类（法）category 种类，类型cation 正[阳]离子cationic 阳（正）离子的centrifuge 离心chain reaction 连锁反应chain termination 链终止char 炭characterize 表征成为…的特征chilled water 冷冻水chlorine 氯（气）coating 涂覆cocatalyst 助催化剂coil 线团coiling 线团状的colligative 依数性colloid 胶体commence 开始，着手common salt 食盐complex 络合物compliance 柔量condensation polymer 缩合聚合物，缩聚物conductive material 导电材料conformation 构象consistency 稠度，粘稠度contaminant 污物contour 外形，轮廓controlled release 控制释放controversy 争论，争议conversion 转化率conversion 转化copolymer 共聚物copolymerization 共聚（合）corrosion inhibitor 缓释剂countercurrent 逆流crosslinking 交联crystal 基体，结晶crystalline 晶体，晶态，结晶的，晶态的crystalline 结晶的crystallinity 结晶性，结晶度crystallite 微晶decomposition 分解defect 缺陷deformability 变形性，变形能力deformation 形变deformation 变形degree of polymerization 聚合度dehydrogenate 使脱氢density 密度depolymerization 解聚deposit 堆积物，沉积depropagation 降解dewater 脱水diacid 二（元）酸diamine 二（元）胺dibasic 二元的dieforming 口模成型diffraction 衍射diffuse 扩散dimension 尺寸dimensional stability 尺寸稳定性dimer 二聚物（体）diol 二（元）醇diolefin 二烯烃disintegrate 分解，分散，分离dislocation 错位，位错dispersant 分散剂dissociate 离解dissolution 溶解dissolve 使…溶解distort 使…变形，扭曲double bond 双键dough （生）面团，揉好的面drug 药品，药物elastic modulus 弹性模量elastomer 弹性体eliminate 消除，打开，除去elongation 伸长率，延伸率entanglement 缠结，纠缠entropy 熵equilibrium 平衡esterification 酯化（作用）evacuate 撤出extrusion 注射成型extrusion 挤出fiber 纤维flame retardant 阻燃剂flexible 柔软的flocculating agent 絮凝剂folded-chain lamella theory 折叠链片晶理论formulation 配方fractionation 分级fragment 碎屑，碎片fringed-micelle theory 缨状微束理论functional group 官能团functional polymer 功能聚合物functionalized polymer 功能聚合物gel 凝胶glass transition temperature 玻璃化温度glassy 玻璃（态）的glassy 玻璃态的glassy state 玻璃态globule 小球，液滴，颗粒growing chain 生长链，活性链gyration 旋转，回旋hardness 硬度heat transfer 热传递heterogeneous 不均匀的，非均匀的hydocy acid 羧基酸hydrogen 氢（气）hydrogen bonding 氢键hydrostatic 流体静力学hydroxyl 烃基hypothetical 假定的，理想的，有前提的ideal 理想的，概念的imagine 想象，推测imbed 嵌入，埋入，包埋imperfect 不完全的improve 增进，改善impurity 杂质indispensable 不了或缺的infrared spectroscopy 红外光谱法ingredient 成分initiation （链）引发initiator 引发剂inorganic polymer 无机聚合物interaction 相互作用interchain 链间的interlink 把…相互连接起来连接intermittent 间歇式的intermolecular (作用于)分子间的intrinsic 固有的ion 离子ion exchange resin 离子交换树脂ionic 离子的ionic polymerization 离子型聚合irradiation 照射，辐射irregularity 不规则性，不均匀的isobutylene 异丁烯isocyanate 异氰酸酯isopropylate 异丙醇金属，异丙氧化金属isotactic 等规立构的isotropic 各项同性的kinetic chain length 动力学链长kinetics 动力学latent 潜在的light scattering 光散射line 衬里，贴面liquid crystal 液晶macromelecule 大分子，高分子matrix 基体，母体，基质，矩阵mean-aquare end-to-end distance 均方末端距mechanical property 力学性能，机械性能mechanism 机理medium 介质中等的，中间的minimise 最小化minimum 最小值，最小的mo(u)lding 模型mobility 流动性mobilize 运动，流动model 模型modify 改性molecular weight 分子量molecular weight distribution 分子量分布molten 熔化的monofunctional 单官能度的monomer 单体morphology 形态（学）moulding 模塑成型neutral 中性的nonelastic 非弹性的nuclear magnetic resonance 核磁共振nuclear track detector 核径迹探测器number average molecular weight 数均分子量occluded 夹杂（带）的olefinic 烯烃的optimum 最佳的，最佳值[点，状态] orient 定向，取向orientation 定向oxonium 氧鎓羊packing 堆砌parameter 参数parison 型柸pattern 花纹，图样式样peculiarity 特性pendant group 侧基performance 性能，特征permeability 渗透性pharmaceutical 药品，药物，药物的，医药的phenyl sodium 苯基钠phenyllithium 苯基锂phosgene 光气，碳酰氯photosensitizer 光敏剂plastics 塑料platelet 片晶polyamide 聚酰胺polybutene 聚丁烯polycondensation 缩（合）聚（合）polydisperse 多分散的polydispersity 多分散性polyesterification 聚酯化（作用）polyethylene 聚乙烯polyfunctional 多官能度的polymer 聚合物【体】，高聚物polymeric 聚合（物）的polypropylene 聚苯烯polystyrene 聚苯乙烯polyvinyl alcohol 聚乙烯醇polyvinylchloride 聚氯乙烯porosity 多孔性，孔隙率positive 正的，阳（性）的powdery 粉状的processing 加工，成型purity 纯度pyrolysis 热解radical 自由基radical polymerization 自由基聚合radius 半径random coil 无规线团random decomposition 无规降解reactent 反应物，试剂reactive 反应性的，活性的reactivity 反应性，活性reactivity ratio 竞聚率real 真是的release 解除，松开repeating unit 重复单元retract 收缩rubber 橡胶rubbery 橡胶态的rupture 断裂saturation 饱和scalp 筛子，筛分seal 密封secondary shaping operation 二次成型sedimentation 沉降（法）segment 链段segment 链段semicrystalline 半晶settle 沉淀，澄清shaping 成型side reaction 副作用simultaneously 同时，同步single bond 单键slastic parameter 弹性指数slurry 淤浆solar energy 太阳能solubility 溶解度solvent 溶剂spacer group 隔离基团sprinkle 喷洒squeeze 挤压srereoregularity 立构规整性【度】stability 稳定性stabilizer 稳定剂statistical 统计的step-growth polymerization 逐步聚合stereoregular 有规立构的，立构规整性的stoichiometric 当量的，化学计算量的strength 强度stretch 拉直，拉长stripping tower 脱单塔subdivide 细分区分substitution 取代，代替surfactant 表面活性剂swell 溶胀swollen 溶胀的synthesis 合成synthesize 合成synthetic 合成的tacky （表面）发粘的,粘连性tanker 油轮，槽车tensile strength 抗张强度terminate （链）终止tertiary 三元的，叔（特）的tetrahydrofuran 四氢呋喃texture 结构，组织thermoforming 热成型thermondynamically 热力学地thermoplastic 热塑性的thermoset 热固性的three-dimensionally ordered 三维有序的titanium tetrachloride 四氯化钛titanium trichloride 三氯化铁torsion 转矩transfer （链）转移，（热）传递triethyloxonium-borofluoride 三乙基硼氟酸羊trimer 三聚物（体）triphenylenthyl potassium 三苯甲基钾ultracentrifugation 超速离心（分离）ultrasonic 超声波uncross-linked 非交联的uniaxial 单轴的unsaturated 不饱和的unzippering 开链urethane 氨基甲酸酯variation 变化，改变vinyl 乙烯基（的）vinyl chloride 氯乙烯vinyl ether 乙烯基醚viscoelastic 黏弹性的viscoelastic state 黏弹态viscofluid state 黏流态viscosity 黏度viscosity average molecular weight 黏均分子量viscous 粘稠的vulcanization 硫化weight average molecular weight 重均分子量X-ray x射线x光yield 产率Young's modulus 杨氏模量课文翻译第一单元什么是高聚物？什么是高聚物？首先，他们是合成物和大分子，而且不同于低分子化合物，譬如说普通的盐。

肺的重要性英语作文The Importance of the LungsThe lungs are a vital organ in the human body responsible for the exchange of gases essential for life. They play a crucial role in the respiratory system, allowing us to breathe and providing our cells with the oxygen they need to function properly. Without healthy and functioning lungs, our bodies would be unable to sustain life. In this essay, we will explore the importance of the lungs and the various ways in which they contribute to our overall health and well-being.Firstly, the primary function of the lungs is to facilitate the exchange of oxygen and carbon dioxide. As we inhale, air enters the lungs, and the alveoli, tiny air sacs within the lungs, absorb the oxygen. This oxygen-rich blood is then circulated throughout the body, providing our cells with the necessary fuel to carry out their essential processes. Conversely, when we exhale, the lungs expel the carbon dioxide produced by our cells as a waste product.This gas exchange process is crucial for maintaining a delicate balance within the body. Oxygen is necessary for cellular respiration, the process by which our cells convert nutrients into energy. Withouta sufficient supply of oxygen, our cells would be unable to function properly, leading to a variety of health issues. Conversely, the removal of carbon dioxide is equally important, as its buildup can be toxic and lead to respiratory distress and other complications.In addition to their role in gas exchange, the lungs also serve as a protective barrier against harmful substances and pathogens. The respiratory system is equipped with various mechanisms, such as the cilia and mucus, which work together to trap and expel foreign particles, bacteria, and viruses that may enter the body through the nose and mouth. This helps to prevent respiratory infections and other respiratory-related illnesses.Moreover, the lungs play a crucial role in maintaining the balance of fluids within the body. The alveoli in the lungs are responsible for the production of surfactant, a substance that helps to reduce the surface tension of the alveoli, allowing them to expand and contract more easily during the breathing process. This, in turn, helps to prevent the alveoli from collapsing and ensures that the lungs remain properly inflated.The importance of the lungs also extends to their involvement in the body's immune response. The lungs contain a variety of immune cells, such as macrophages and lymphocytes, which help to defend the body against respiratory infections and other respiratory-relateddiseases. These cells are responsible for identifying and eliminating harmful pathogens that may enter the respiratory system, helping to keep the body healthy and free from illness.Furthermore, the lungs are closely linked to the cardiovascular system. The pulmonary arteries carry deoxygenated blood from the heart to the lungs, where it is oxygenated, and the pulmonary veins then transport the oxygenated blood back to the heart. This constant exchange of blood and oxygen between the lungs and the heart is essential for maintaining a healthy circulatory system and ensuring that all the body's cells receive the oxygen they need to function properly.In addition to their physiological importance, the health of the lungs can also have a significant impact on our overall quality of life. Respiratory conditions such as asthma, chronic obstructive pulmonary disease (COPD), and lung cancer can severely impair lung function and lead to a variety of debilitating symptoms, including shortness of breath, coughing, and wheezing. These conditions can significantly reduce an individual's ability to engage in physical activity, perform daily tasks, and enjoy a high quality of life.To maintain the health of our lungs, it is essential to adopt a healthy lifestyle that includes regular exercise, a balanced diet, and the avoidance of harmful substances such as tobacco smoke. Regularcheck-ups with a healthcare provider can also help to identify and address any respiratory issues early on, before they become more severe.In conclusion, the lungs are a vital organ that play a crucial role in our overall health and well-being. From facilitating the exchange of gases to protecting the body against harmful substances and pathogens, the lungs are essential for sustaining life and ensuring that our bodies function properly. By understanding the importance of the lungs and taking steps to maintain their health, we can improve our quality of life and reduce the risk of respiratory-related illnesses.。

常用钻井液体系翻译1.聚合醇钻井液体系聚乙二醇和聚合醇是聚合醇钻井液体系的主要成分，在水基钻井液体系中有着优秀的润滑和稳定井壁的作用。

聚合醇的浊点是指：产品在浊点以下在水基体系任意互溶，当温度高于浊点时变成水不溶物以小微珠形式从水中析出。

聚合醇是一种非离子表面活性剂，白色类似牛奶的粘稠液体，低温与水互溶，升到一定温度后，一部分以小微珠形式从水中析出，使溶液变得混浊不透明。

浊点现象可逆，小微珠可以堵塞地层孔隙和缝隙，或沉积在井壁泥饼上，稳定井壁，提高钻井液本身和井壁的润滑性能，减轻油气层损害。

Polyglycol and polyalcohol are used as principal ingredients in polyglycol & ployacohol drilling fluid system and as excellent lubricants and borehole stabilizers in other water base drilling fluid systems.Cloud point of a polyacohol refers to the temperature below which the product is in dissolved state in a water base system in any proportion and above which it becomes water insoluble and comes out from the water phase of the fluid as small droplets.Polyalcohol is a kind of nonionic surfactant.It’s a white color viscous liquid similar to the milk.The cloud point phenomenon is reversible.The small droplets can plug fissures and give birth of tough and strengthened mud cake in the purpose of obtaining a stable borehole wall.It can improve the lubricity of the fluid system and the mud cake. Meanwhile the addition of polyalcohol can prevent formation damage.2.甲酸盐钻井液体系甲酸盐钻井液体系是不含膨润土的钻井液，溶解大量的甲酸盐，具有一定的密度，有很强的防止油气层损害的功能，常用做完井液。

纳米混悬剂（Nano suspension）Nanosuspension research progressAuthor: Wangyu source of scientific information: Literature hits: 531 update time: 2007-4-3[keyword]: nanosuspension, sirolimus, aprepitant, insulinReuters health:At present, more than 40% of the drugs in development of the problem of poor water solubility, which makes the potential varieties not listed or can not give full play to effect. It is difficult to solve the solution problem of low bioavailability of drugs is very urgent. The commonly used solvent solubilization, cyclodextrin and emulsion technology has some limitations, such as the co solvent of organic solvents in toxicity, and drug release; the inclusion of the size of the drug molecules with special requirements; requires high drug solubility emulsion in oil phase.Suspension mixed Muller in 1994 in the research and development of nano (nanosuspensions) can better solve the above problem. The stabilizing effect of the surfactant, the drug particles dispersed in water by grinding or crystallizing technology to form a stable dispersion of nano colloidal. Whether the drug is difficult to dissolve in water or insoluble drugs in water and insoluble in oil, can be prepared by this method to obtain the corresponding nanosuspension. As an intermediate form, nanosuspension can further prepare for oral administration, injection or other dosage forms, so as to improve the absorptionand bioavailability of drugs. And nanosuspension can improve the content of drug formulations, especially suitable for large dose, insoluble drug oral and injection. In addition, the prescription is not included in the carrier and co solvent injection toxicity is very low.Preparation characteristicsColloidal drug nanoparticle suspension is the "pure" dispersion system. Different from the matrix type nano system in the traditional sense, nanosuspension without carrier material, it is through the stabilizing effect of the surfactant, the drug particles of nano scale dispersion system formed in water.Because of the characteristics of nanosuspension, which reflects the unique advantages in various administration (Table 1): such as simple prescription and preparation, is conducive to the rapid screening of active compounds to reduce the cost and improve the drug dissolution and bioavailability, without additional ingredients caused by irritating and toxic effect and low dose volume etc..Table 1 Characteristics of drug nanosuspensions-- -- --Drug dosage form characteristics-- -- --Oral administration of small size increase the drug absorption rate and absorption rate, improve the bioavailabilityMucosal adhesion increased high drug content, prolong the retention time of the gastrointestinal tract, reduce the absorption of individual differencesTo avoid the first pass metabolism, and can be targeted to the treatment of lymphatic system diseasesNo carrier injection or co solvent to reduce the toxicity, reduce the volume of Administration (especially muscle, subcutaneous and intradermal injection)The high drug content of monocyte phagocytosis, reduce toxicity, increase effectivenessBy Twain -80 to apolipoprotein E deposition on the nanoparticles,.The brain endothelial cell receptors promote brain uptakeInhalation of small particle size on alveolar macrophage targeted drug delivery, increased respiratory drug absorption, reduce systemic absorption-- -- --PreparationNanosuspension preparation mainly has two aspects, namely theprescription and technology. The prescription is mainly the choice of type and amount of surfactant, in order to improve the long-term stability of the product; process optimization by adjusting the production process such as pressure and cycle number and other parameters of the high pressure homogenizer, the ideal particle size distribution.Screening of surfactantsIn order to prepare stable nano suspension, avoid agglomeration of nanoparticles and increase of surfactant must be screened properly. The general choice of ionic and nonionic surfactants, nonionic surfactant nanoparticles can be generated between the electrostatic repulsion; non ionic polymer is the steric repulsion between particles. Research shows that the long-term stability of combination of two types of surfactants can make better preparations.Preparing nanosuspension by direct homogenization method, the long-term stability of the type and amount of surfactant affects only the product, does not affect the product size. MUller was prepared by direct homogeneous buparvaquone nanosuspension, adding poloxamer formulation (poloxamer) and polyvinyl alcohol (PVA) 188, 3 months after the drug particle size did not change significantly. But when the drug content is up to 10%, 6 months after the drug has re dispersible difficult problem; prescription such as adding hydrogel or freeze drying products, the product can maintain stability in years.The trace precipitation or emulsifying preparation ofnanosuspension, surfactant type and dosage can affect the formation of crystals, choose different surfactants and their ratio can be obtained with different particle size distribution of the products. Kocbek by emulsification preparation of ibuprofen nanosuspension, prescription containing 0.25% Twain -80 product size of 158.1nm containing 0.5, twelve sodium dodecyl sulfate (SDS) when the particle size is 263.2nm, poloxamer188, PVA as the stabilizer or combination of several kinds of surfactant, the particle sizes of products are the difference.The preparation processPreparation method of nano suspension mainly milling method and ultrasonic method and high pressure homogenization method. The first two kinds of preparation methods are grinding medium or metal residue, and high pressure homogenization method for metal residue, and is easy for industrialized production.Direct homogenization method (direct homogenization)Direct homogenization method is cavitation and cavitation effect caused by high pressure homogenization, micronized drug particles will be further crushed for nano scale particles, while reducing drug particle size polydispersity (PI). To avoid the addition of organic solvent by direct homogenization method,Suitable for both insoluble drugs in water insoluble in oil, and the reproducibility of the process better. Research shows that the particle size is determined by the drug itself hardness,high pressure homogenization pressure and cycle number. By adjusting the pressure and cycle number of homogenizer can get proper particle size distribution of the product. With the increase of circulating pressure, the particle size is reduced, finally can reach a constant value, that is the optimal particle size; dispersion decreases with the increase of cycle number. But reduce the size increase of high pressure homogenization pressure and drug particle and no linear relationship, because the process of high pressure homogenization is the destruction of the drug particles is not perfect crystal, the smaller the particle size, drug crystal more perfect, crushing energy required is higher. The study showed that 1500bar pressure drugs can be crushed to smaller crystals, and the pressure is increased to 4000bar, and did not get finer crystals.Trace precipitation (microprecipitation)Trace precipitation is the first drug is dissolved in an organic solvent miscible with water, then the liquid is added to water, controlling the crystallization conditions to form nanoparticles. The initial crystallization of the crystallization involves the establishment and subsequent nuclear particle growth phase. The preparation of stable nano suspension to high nucleation rate but low growth rate and supersaturation and mechanical stirring speed rate is determined both in temperature and drug. So the trace organic solvent precipitation method to screening and appropriate proportion, and choose the appropriate crystallization temperature and stirring speed.The trace of precipitation is the drug from the dissolved stateinto the suspended state, so the mechanical consumption than the direct homogenization method, suitable for the poor stability of drugs. But due to the use of organic solvents in the preparation process, may lead to organic solvent residues, and may cause drug size change in removing organic solvent.Emulsification method (lipid emulsions)Emulsification method is the first drug prepared O/W nano emulsion, and then control the drug in the droplet precipitated in the prepared nanosuspensions. The drug is dissolved in an organic solvent and insoluble in water (such as ethyl acetate, three acetic acid esters of glycerol and chloroform); then the medicine liquid is added to an aqueous solution containing a surfactant, using high shear mixing to form colostrum, and then use the high pressure homogenizer will further homogenization for nano colostrum milk, finally nanoemulsion added to a large number of water, the organic solvent phase to aqueous phase diffusion, and the precipitation of drug nanoparticles. At the same time the drug precipitation combined with high pressure homogenizer can get better particle size distribution. This method is developed by using paclitaxel albumin nanosuspensions (Abraxane) has been listed in the United states.Physicochemical evaluationWhen the solid particle size less than 1 ~ 2 m, the solubility of particles by the influence of particle size, the solubility of small particles, and the solubility of small particles, which leads to small particles and large particles graduallydissolve gradually become larger, the phenomenon known as Ostwald ripening phenomenon (Ostwald ripening). In order to prevent the occurrence of this phenomenon, must select proper prescription to increase the physical stability of nanosuspension, while optimizing the preparation process to ensure that the final product has a narrow particle size distribution.In addition, in order to study the drug release performance of nano suspension agent, also need the crystal type, the drug release rate were investigated.The particle size and polydispersityResearch shows that in addition to the surfactant, the particle size distribution is an important factor affecting the stability of nanosuspension, therefore in the process of R & D nanosuspension, decided the success of prescription must first examine the grain size and its distribution, and the accelerated test, the influence of temperature and mechanical force on the particle size and distribution effect.According to the different characteristics of nanosuspension, various technique can be used to measure the particle size and polydispersity. Proton correlation spectroscopy (PCs) can detect 3nm ~ 3 m in the range of particles, is commonly used detection particle size and polydispersity (PI < 0.3 has better stability) instrument; laser diffraction (LD) fast detection speed, can detect larger particles or aggregation of nanoparticles (detection range is 0.02 ~ 2000 m), of which 99% of the data on particle sensitive, has important significancein injection detection. In addition, in the preparation of injectable nano suspension, can also use the Kurt particle counting method.Nonionic surfactant and Zeta potentialThe nanosuspension, repulsion between particles is also conducive to long-term stability of the colloidal dispersion. If a single use of ionic surfactants, then achieve the lowest Zeta potential for the stability of about + 30mV; but the combined use of ionic and nonionic surfactant, even if the Zeta potential is lower than the critical value, but also has good physical stability, because the nonionic surfactant with particle steric repulsion effect enough, the Zeta + 20mV can reach as long as the potential.Study on the preparation of crystal form and appearanceIf the drug exists polymorphs, so different crystal types will affect the rate of drug release and drug efficacy. At present, usually by differential scanning calorimetry and X-ray diffraction determination of crystalline state of the drug, can also be observed by nano suspension form.In the preparation of nanosuspensions can according to need to add appropriate suppression of grain, the control of the core drugs in the amorphous state. The general is adding a water soluble substance such as Miglyol is very low, it combined with drugs in reducing the interfacial tension of drug particles, while the formation of dense interface on the surface of the drug, reduce the internal diffusion of drug molecules to theaqueous phase, thereby inhibiting the Ostwald ripening phenomenon, the particle internal stability of amorphous.The solubility and dissolution rateRegardless of the route of administration, the nano suspension solid nanoparticle agent must dissolve into molecules form before they can play a role in treatment, the dissolution rate of drug molecules and the formation rate depends on the nano particles. In the dissolution medium, combined with dialysis and dissolution determination method can be used to determine the dissolution rate of mixed suspension of different nano. According to the Ostwald- Freundlich equation andNoyes-Whitney equation, improve the dissolution rate of the drug can increase the solubility of nanoparticles, so as to further improve the drug absorption and diffusion in the gastrointestinal tract. The determination method of dialysis and traditional saturated solubility (the drug solution under the condition of constant temperature stirring or shaking until the dissolution equilibrium with),The saturation solubility of nanoparticles in nano suspension can be measured. In addition, depending on the size of the drug, ultrafiltration or direct filtration can be used to determine the solubility of the drug.Application exampleIt often takes decades for a pharmaceutical technology to be transformed into an actual product, and a nano suspension is available in just a few years. The first nano crystal patentis at the beginning of 90s by Nanosysterms company (now Elan) application: by 2000 the first nanosuspension products of sirolimus (Rapamune) successfully listed, it is oral tablets, each containing 1mg or 2mg sirolimus, clinical results show its bioavailability than oral solution high 21%; then the first intravenous nanosuspensions by albumin bound paclitaxel nanoparticles injection suspension (Abraxane) is successful, it gets rid of the addition of surfactants Cremophor-EL, to avoid pre drug allergy treatment, improve the compliance of patients. At present, there are many other kinds of nano suspension in clinical research (Table 2).Table 2 formulations of solid particle suspensions listed and developed- - - - - - - - - - - - - - - - - - - --Drug name (trade name) certification research and development company- - - - - - - - - - - - - - - - - - - --Sirolimus (Rapamune) inhibits immune Elan NanosystemsArai Tan (Emend Elan Nanosystems) antiemeticPaclitaxel (Abraxane), metastatic breast cancer, American Life Sciences (AmericanBioscience)Cytokine inhibitors localized enteritis, Elan, NanosystemsDiagnostic agent, contrast medium, Elan, NanosystemsThymectacin anticancer Elan NanosystemsBai Xiaoan (Busulfan) anticancer SkyePharmaBudesonide (Budesonide), asthma, Elan, NanosystemsSilver eczema, atopic dermatitis, NUCRYSTCalcium phosphate herpes mucosal vaccine adjuvant BioSanteInsulin, diabetes mellitus, BioSanteNot publicly resistant to infection with Baxter NANOEDGENot publicly anti-cancer Baxter NANOEDGE- - - - - - - - - - - - - - - - - - - --Advances in drug delivery routes by collaborative pharmaceutical companies- - - - - - - - - - - - - - - - - - - --Wyeth (Wyeth) oral has been listedMerck (Merck) oral has been listedAmerican pharmaceutical partners (American venous phase III Pharmaceutical Partners)Cytokine PharmaSciences phase II clinical oralPhotogen I / II clinical veinNewBiotics./Ilex Oncology I / II clinical veinIntrathecal Supergen phase I clinicalSheffield Pharmaceuticals phase I clinical lungNo local phase I clinicalNo oral phase I clinicalNo oral phase I clinicalStudy on undisclosed pre clinical oral veinStudy on undisclosed pre clinical oral vein-- -- ---epilogueNanosuspension is a generally applicable to insoluble drug formulations, it was originally designed to improve drug bioavailability of insoluble through process and simpleprescription, while avoiding the side effects on patients with a large number of additional components. In recent years, researchers pay more attention to the surface modification agent nanosuspension, can change the objects within the drug pharmacokinetics; in addition, nano suspension of agent technology in peptide and protein drugs in the field is also highly anticipated. I believe, nanosuspension will have a more splendid future.。

2020年4月阶段性学情测试高三英语2020.4.25第一部分听力（共两节，满分20 分）做题时，先将答案标在试卷上。

录音内容结束后，你将有两分钟时间将试卷上的答案转涂到答题卡上。

第一节(共5小题；每小题1分，满分5分)听下面5段对话。

每段对话后有一个小题，从题中所给的A、B、C三个选项中选出最佳选项，并标在试卷的相应位置。

听完每段对话后，你都有10秒钟的时间来回答有关小题和阅读下一小题。

每段对话仅读一遍。

1. What is Bob most probably doing?A. Watching a game.B. Playing basketball.C. Fishing.2. When will the speakers meet?A. By 5：00.B. By 4：30.C. By 2：30.3. What color is the T-shirt the man likes?A. Green and white.B. Gray and black.C. Gray and white.4. Why was the woman annoyed?A. Because the film was too long.B. Because the seats were uncomfortable.C. Because the people behind were too noisy.5. How does Mary feel today?A. Nervous.B. Sad.C. Happy.第二节(共15小题；每小题1分，满分15分)听下面5段对话或独白。

每段对话或独白后有几个小题，从题中所给的A、B、C三个选项中选出最佳选项，并标在试卷的相应位置。

听每段对话或独白前，你将有时间阅读各个小题，每小题5秒钟；听完后，各小题将给出5秒钟的作答时间。

每段对话或独白读两遍。

听第6段材料，回答第6、7题。

6. What does the woman do?A. A chemist.B. A train driver.C. A nurse.7. What does the woman think of her work?A. Dangerous.B. Rewarding.C. Demanding.听第7段材料，回答第8、9题。

大 学 化 学Univ. Chem. 2022, 37 (2), 2105062 (1 of 8)收稿：2021-05-25；录用：2021-06-29；网络发表：2021-07-09*通讯作者，Email:***************.cn基金资助：山东省自然科学杰出青年基金(ZR2020JQ09)•化学实验• doi: 10.3866/PKU.DXHX202105062 纳米银、金溶胶的电化学合成及其基本胶体性质——物理化学综合实验设计马继臻，丁思雨，田亚冬，马厚义，张进涛*山东大学化学与化工学院，济南 250100摘要：电化学和胶体体系基础理论是大学本科物理化学学习的重要内容。

通过综合化学实验设计，以直接电化学还原方法制备纳米银、金溶胶，利用紫外-可见光谱分析溶胶粒子的特征吸收光谱，并运用循环伏安法探讨表面活性剂的稳定作用和纳米金属溶胶的形成机理，从而提高学生的基础知识综合运用能力与综合实验技能，适合在大学化学及其相关专业的综合化学实验中推广。

关键词：电化学；胶体化学；溶胶；纳米材料中图分类号：G64；O6Electrochemical Synthesis and Basic Properties of Nanostructured Gold and Silver Colloidal Sols: Comprehensive Experiment Design of Physical ChemistryJizhen Ma, Siyu Ding, Yadong Tian, Houyi Ma, Jintao Zhang *School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China.Abstract: The primary electrochemistry and colloid chemistry are the important components of physical chemistry for undergraduate students. On the basis of the nanostructured metal colloids system, a comprehensive chemistry experiment is proposed, which is about synthesis of nanostructured Ag/Au colloidal sols via the direct electrochemical reduction method with the assistance of a surfactant. In addition to the analysis of typical extinction via the UV-Visible spectroscopy, the cyclic voltammetry method is used to understand the effect of the surfactant and reveal the formation process of metal colloids. Such a comprehensive experiment is efficient to not only promote the understanding on the fundamental knowledge of electrochemistry and colloid chemistry, but also enhance the laboratory skill, which is adopted to the laboratory courses for the students majored in chemistry and related.Key Words: Electrochemistry; Colloid chemistry; Sol; Nanomaterial金属纳米材料作为一类非常重要的功能材料，由于其特殊的表界面特点表现出了与块体材料显著不同的物理化学性质，在催化、生物标识、导电浆料、电池储能等现代科学技术领域具有广泛的应用潜力[1,2]。

单质铝水解机理研究( Ⅱ)——结晶动力学分析刘建良1,2 ，孙加林2 ，徐茂2 ，施 安2， 胡 劲1,2 ，高勤琴2（1、昆明理工大学 冶金学院，云南 昆明650093；2. 昆明贵金属研究所，云南 昆明650221）现阶段高纯 Al O 的制备方法主要有溶胶－凝 摘 要: 对单质铝水解过程进行了全过程监测，在反应的不同时段取样并对其进行 XRD 分析，以分析结果为依据，作者提出单质铝水解法制备 高纯氧化铝工艺的实质为一反应结晶过程的观点。

随后，作者运用溶液 法结晶原理对检测数据进行了深入分析，分析后认为水解产物六方晶拜 耳体是形成推动结晶发生所需过饱和状态的溶质相，从而从根源上找到 了佐证上述观点成立的证据。

关键词: 单质铝； 水解； 过饱和； 结晶 2 3胶法、硫酸铝铵热解法、碳酸铝铵热解法、乙丙醇铝水解法等[1～4]，然而这些方法都不同程度的存在着 成本高、工艺过程复杂、污染环境的缺点。

本课题 组发明了一种全新的高纯氧化铝制备工艺——单质铝水解法制备高纯氧化铝工艺 ，该工艺工艺流程[5,6]中图分类号：O621.25+6.5文献标识码：A短、成本低、无污染，为清洁环保型工艺。

本文中 以水解反应为着眼点，用溶液法结晶原理[7]对Al － 文章编号：1008－ 5548(2005)02 －0018 －03H O 体系的结晶过程做出了解释。

Research on Theory of Pure AluminumHydrolyzatio （n Ⅱ）——An alysis ofCrystallizing Dynamics21 实 验实验用原料为中铝集团贵州分公司特级(T )精 0铝，其纯度见表 1。

水解用纯水为自来水经四级反渗透加树脂交换 后得到的去离子水，其电阻率≥ 12M Ω。

将铝单质用特殊活化工艺活化，之后让其与去 离子水在加热条件下反应。

反应过程中按一定时间 间隔取样，并对样品进行 SEM 、XRD 分析，分析设 备分别为 ESEM 测试仪和德国 Bruker 公司 D8 ad- vance X 衍射仪。

Stability of Decontamination Foam Containing Silica Nanoparticles and Viscosifier In-Ho Yoon , Chong-Hun Jung, Suk Bon Yoon, Chorong Kim, Jun-Young Jung, Sang Yoon Park,Jei-Kwon Moon, Wang-Kyu ChoiDecontamination and Decommissioning Research Division, Korea Atomic Energy Research Institute (KAERI) 1045 Daedeokdaero, Yuseong-gu, Daejeon 305-353, Republic of Korea*Correspondingauthor:***************.kr1. IntroductionA large amount of liquid waste is generated from the decontamination that occurs when dismantling nuclear facilities. A process is needed to decrease the amounts of chemical reagents and secondary waste produced during the decontamination process. Decontamination foam is a non-stable, two-phase fluid with aqueous and gas phases representing not more than 10% and 90% of the total volume, respectively. This formulation can significantly decrease the amounts of chemical reagents and secondary waste [1].The advantage of decontamination foam is its potentially wide application for metallic walls, overhead surfaces, and the elements of complex components and facilities. In addition, foam is a good material for in situ decontamination because it generates low final waste volumes owing to its volume expansion. The application of foam allows for remote decontamination processing using only an injection nozzle and the equipment to generate the decontamination foam, which reduces operator exposure to high radioactivity [2,3].The decontamination efficiency can be enhanced by improving the contact time between chemical reagents and a contaminated surface through the addition of surfactants and viscosifiers into the decontamination foam. The objective of this study is to investigate the effect of silica nanoparticles and a viscosifier on the foam stability and the dissolution behaviors of corroded specimens using a non-ionic surfactant.2. Materials and Methods2.1 Stability test for the decontamination foamElotant TM Milcoside 440N (EM 440N) is a decyl glucoside supplied by LG Household & Health Care. Xanthan gum (Sigma) and silica nanoparticles (M-5, Cabosil) were selected for testing as viscosifiers. The foaming properties (i.e., foam formation and foam stability) were determined using a Foamscan instrument (Teclis/IT Concept, Logessaigne, France). The foam is generated by blowing nitrogen gas at a flow rate of 200 ml/min through a porous glass filter at the bottom of a glass tube where 60 ml of the foaming aqueous solution (25 ± 1 °C) is placed.In all experiments, the foam was allowed to reach a volume of 200 ml. The bubbling was then stopped, and the evolution of the foam was analyzed using conductivity and optical measurements. The generated foam rose along a circular glass column, and the volume measurement was captured by an image analysis using a CCD camera. The amount of liquid incorporated in the foam, the foam homogeneity, and the liquid drainage from the foam were measured based on the conductivity in the glass column at the liquid sample and at different heights in the glass column using electrodes.2.2 Dissolution test using decontamination foamInconel specimens 20 mm × 20 mm × 2 mm in size were used for the dissolution test. They were polished with abrasive paper and washed with water and ethyl alcohol. The corroded layer of the specimens was grown in a semi-loop filled with a solution, simulating the primary water in light water reactors. Four types of decontamination foam were prepared. Nanoparticles of1 and 3 wt.% M-5 were added to 30 mL of a 1% EM 440N surfactant solution without or with 0.1 wt.% xanthan gum containing 1M HNO3 to prepare the decontamination foam. The specimen was immersed in decontamination foam contained in 100 ml test bottles after shaking the decontamination foam. The concentration of dissolved iron from the specimens was measured using Flame Atomic Absorption Spectroscopy.3. Results and Discussion3.1 Stability test for the decontamination foamThe graph for the foam volume and liquid volume in foam as a function of time for four different formulations of EM 440N, xanthan gum, and M-5 nanoparticles shows an identical initial liquid volume in foam, v0, but different foam stabilities. In Fig. 1, the addition of 0.1 % xanthan gum increases the liquid volume in the foam by delaying the drainage. Compared to the foam stabilized only with 1% EM 440N, the addition of 0.1% xanthan gum improves the half-life [τ(v1/2)] by a factor of 5.5. The addition of 1%M-5 nanoparticles to 1% EM 440N and 0.1% xanthan gum did not increase the liquid volume in the foam. Compared to the foam stabilized by 1% EM 440N and 0.1% xanthan gum, the addition of 3% M-5 improve the half-life [τ(v1/2)] by a factor of 1.27. These resultsindicate that the addition of a high concentration of nanoparticles improves the foam stability.20040060080010001200H a l f ‐l i f e l l i q u i d v o l u m e i n f o a m (s e c )Decontamination foam1%EM 440N1%EM 440N + 0.1% XG1%EM 440N +0.1% XG + 1% M ‐51%EM 440N + 0.1% XG + 3% M ‐5Fig. 1. Variation in the half-life liquid volume in foams that contain 1% EM 440N and 0.1% xanthan gum (XG) with 1% and 3% M-5 silica nanoparticles.3.2 Dissolution test using decontamination foamThe concentration of the dissolved iron was analyzed by Flame-AAS after the dissolution tests for the decontamination liquid and foams. The results showed that the EM 440N foam had approximately 56% of the level of dissolved iron compared with the decontamination liquid (Fig. 2). Approximately 59% and 66% of the control level of dissolved iron were found using 1% EM 440N and 0.1% xanthan gum without and with 1% M-5, respectively. However, the 1% EM 440N and 0.1% xanthan gum solution containing 3% M-5 improves to 94% of the value of dissolved iron compared with the decontamination liquid control (Fig. 2). These results indicate that an increase in the foam stability increases the concentration of dissolved iron, which suggests that enhancing the contact time between the chemical reagents and the specimen increases the iron dissolution.0.060.070.080.090.10.110.120.13T h e a m o u n t o f d i s s o l v e d i r o n (m g )Decontatmination foam1%EM 440N1%EM 440N + 0.1% XG1%EM 440N + 0.1% XG + 1% M ‐51%EM 440N + 0.1% XG + 3% M ‐5Decontaminationliquid onlyFig. 2. The concentration of dissolved iron using bottle tests of decontamination foam and liquid.4. ConclusionsThis study showed the effect of viscosifiers and nanoparticles on the foam stability when developing new formulations of decontamination foam. The addition of xanthan gum and the mixture of xanthan gum and silica nanoparticles (M-5) significantly increased the foam stability, compared to the surfactant solution alone. This result indicates that both the viscosifier and nanoparticles have a synergistic effect on the foam stability. As the contact time increased, the dissolution rate increased to become similar to the dissolution that contained decontamination liquid.REFERENCES[1] C. Dame, C. Fritz, O. Pitois, S. Faure, “Relations between physicochemical properties and instability of decontamination foams” Colloids and Surfaces A: Physicochemical and Engineering Aspects, 263 210-218 (2005).[2] L. Nunez, M. Kaminski, “Foam and gel methods for the decontamination of metallic surfaces” US Patent 7,166,758 B2 (2007).[3] J. Causse, J.-F. Valery, C. Roussignol, “Principles of a fission product storage tank decontamination using a foam process” Proceedings of Global, Paris, France (2009).。

气球装水为什么烧不破英语作文Why Can a Water-Filled Balloon Float Over a Flame Without Bursting?The sight of a water-filled balloon hovering above a flame without bursting is a captivating spectacle that has puzzled and fascinated onlookers for decades. Thisseemingly paradoxical phenomenon challenges ourconventional understanding of heat transfer and material properties, leading us to question how an object can withstand intense heat without sustaining damage.To unravel the mystery behind this scientific curiosity, we must delve into the intricate interplay of physical principles governing heat transfer and fluid dynamics.Heat Transfer: A Balancing Act.When an object is exposed to heat, thermal energy flows from the hotter object (in this case, the flame) to thecooler object (the balloon). This process of heat transfer occurs through three primary mechanisms: conduction, convection, and radiation.Conduction: Heat transfer through direct contact between objects.Convection: Heat transfer through the movement offluids (liquids or gases).Radiation: Heat transfer through electromagnetic waves.In the case of the water-filled balloon, heat transfer primarily occurs through conduction. As the flame heats the portion of the balloon closest to it, heat energy flows towards the water inside. However, the rate of heattransfer is significantly reduced due to the balloon's low thermal conductivity. Thermal conductivity measures a material's ability to conduct heat; rubber, the primary material of most balloons, is a poor conductor of heat.Consequently, the heat energy only gradually penetratesthe balloon's surface and into the water, preventing the balloon from rapidly heating up and bursting.The Insulating Effect of Water.Water, despite its high specific heat capacity (the amount of heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius), acts as an effective insulator in this scenario. The water's high specific heat capacity means that it requires a significant amount of heat energy to raise its temperature. This property, coupled with the low thermal conductivity of rubber, creates a protective barrier that shields the balloon's interior from the intense heat of the flame.As the heat energy slowly seeps through the balloon's surface, the water absorbs it, preventing the balloon from reaching its bursting point. Additionally, the water's thermal inertia (its resistance to temperature change) further contributes to the balloon's ability to withstand the heat.Fluid Dynamics: Shaping the Flow.While heat transfer plays a crucial role in preventing the balloon from bursting, fluid dynamics also contributes to its remarkable resilience. As the water inside the balloon heats up, it expands and rises due to its decreased density. This upward movement creates a convective flow within the balloon, carrying the heated water away from the flame and towards the cooler upper portion of the balloon.This convective flow helps distribute the heat more evenly throughout the balloon, preventing the formation of hot spots that could potentially weaken the balloon's structure and lead to its rupture.The Importance of Evaporative Cooling.In addition to the insulating effects of water and the convective flow within the balloon, evaporative cooling also plays a pivotal role in preventing the balloon from bursting. As the water in the balloon gradually heats up, it reaches its boiling point and begins to evaporate. Thisprocess absorbs heat energy from the environment, further reducing the temperature of the balloon.The evaporation of water creates a cooling effect that counteracts the heat transferred from the flame. This evaporative cooling mechanism helps regulate the balloon's temperature and prevents it from overheating.Conclusion: A Symphony of Physical Principles.The ability of a water-filled balloon to float over a flame without bursting is a testament to the intricate interplay of physical principles governing heat transferand fluid dynamics. The combined effects of low thermal conductivity, high specific heat capacity, convective flow, and evaporative cooling create a protective environmentthat shields the balloon from the intense heat of the flame.This phenomenon not only showcases the resilience of everyday materials but also highlights the fascinatingworld of physics that unfolds right before our eyes.。

勤洗手注意消毒英语作文Title: The Importance of Hand Hygiene and Disinfection。

In today's world, where infectious diseases pose a constant threat to public health, the significance of hand hygiene and disinfection cannot be overstated. Maintaining clean hands and ensuring the disinfection of surfaces are essential practices in preventing the spread of illnesses.In this essay, we will delve into why these practices are crucial and explore effective methods to incorporate them into our daily lives.First and foremost, hand hygiene serves as a fundamental measure in preventing the transmission of pathogens. Our hands come into contact with varioussurfaces throughout the day, accumulating bacteria, viruses, and other microorganisms. Without proper hygiene, these pathogens can easily transfer to our mucous membranes, such as the eyes, nose, and mouth, leading to infections.Regular handwashing with soap and water is one of the most effective ways to remove dirt, germs, and contaminants from the hands. The friction created during handwashing helps dislodge pathogens, while soap acts as a surfactant, breaking down the lipid membranes of viruses and bacteria, rendering them inactive. It is recommended to wash handsfor at least 20 seconds, covering all surfaces thoroughly, including the backs of hands, between fingers, and under nails.In situations where soap and water are not readily available, alcohol-based hand sanitizers offer a convenient alternative. These sanitizers contain alcohol, typically in the form of ethanol or isopropanol, which effectively kills a broad spectrum of microorganisms on the hands. However,it is essential to use sanitizers with an alcohol concentration of at least 60% to ensure efficacy.Furthermore, beyond personal hand hygiene, disinfecting frequently touched surfaces is paramount in preventing the spread of illnesses, especially in shared spaces such as homes, workplaces, schools, and healthcare facilities.Surfaces such as doorknobs, light switches, countertops, and electronic devices can harbor pathogens and serve as fomites, facilitating their transmission from one person to another.Disinfection involves the use of chemicals or physical agents to kill or deactivate microorganisms on surfaces. Commonly used disinfectants include bleach (sodium hypochlorite), hydrogen peroxide, quaternary ammonium compounds, and alcohol-based solutions. When using disinfectants, it is essential to follow the manufacturer's instructions regarding dilution, contact time, and proper ventilation to ensure effectiveness and safety.In addition to routine cleaning and disinfection, it is crucial to practice proper respiratory etiquette, such as covering coughs and sneezes with a tissue or the inside of the elbow, to reduce the spread of respiratory droplets containing infectious agents. Maintaining physical distance from individuals who are sick and avoiding close contact with others when feeling unwell also helps mitigate therisk of transmission.Moreover, promoting awareness and education about hand hygiene and disinfection within communities plays a vital role in fostering a culture of health and hygiene. Through public health campaigns, educational programs, and workplace initiatives, individuals can be empowered with the knowledge and resources to adopt these preventive measures effectively.In conclusion, hand hygiene and disinfection are indispensable practices in safeguarding public health and preventing the spread of infectious diseases. By incorporating these habits into our daily routines and promoting their importance within our communities, we can contribute to a healthier and safer environment for all. Let us remember that clean hands save lives, and together, we can make a significant impact in combating infectious illnesses.。

油酸钾溶于水粘稠的原理Potassium oleate, also known as potassium soap, is a type of soap that is formed when potassium hydroxide reacts with oleic acid. This reaction results in the formation of a thick, viscous solution that is commonly referred to as potassium oleate.油酸钾也被称为钾皂，它是一种当氢氧化钾与油酸反应后形成的肥皂。

这种反应会导致形成一种黏稠的溶液，通常被称为油酸钾。

The reason why potassium oleate dissolves in water to form a viscous solution lies in its molecular structure. Potassium oleate is made up of a long hydrophobic hydrocarbon chain (derived from oleic acid) and a hydrophilic potassium ion. When potassium oleate is mixed with water, the hydrophobic tails of the molecules aggregate together, while the hydrophilic heads orient themselves towards the water molecules. This aggregation of hydrophobic tails leads to the formation of a micelle structure, in which the hydrophobic tails are shielded from the water by the hydrophilic heads, resulting in a thick, viscous solution.油酸钾溶解在水中形成粘稠溶液的原因在于其分子结构。

不同溶出介质中辛伐他汀的平衡溶解度和表观油水分配系数测定王素珍;李荣荣;岳雪;董惠钧【摘要】目的：测定辛伐他汀在11种不同溶出介质中的平衡溶解度及在正辛醇－水／缓冲液体系中的表观油水分配系数，为辛伐他汀新剂型的研究开发提供参考。

方法采用高效液相色谱（HPLC）法测定辛伐他汀在11种不同溶出介质中的平衡溶解度；采用摇瓶法测定辛伐他汀的表观油水分配系数。

结果辛伐他汀在不同pH 缓冲液中平衡溶解度无显著性差异，表面活性剂十二烷基硫酸钠（SDS）的加入可使辛伐他汀的平衡溶解度增大约70倍，达到130 mg／L。

辛伐他汀在不同pH缓冲液中的表观油水分配系数P约为2.5（lg P=0.39），无显著性差异。

结论辛伐他汀水溶性差，属生物药剂学分类系统（BCS）Ⅱ类药物，表面活性剂如SDS能显著增加辛伐他汀在水中的溶解度。

辛伐他汀的油水分配系数不受pH的影响。

%Objective To determine the equilibrium solubility of simvastatin in 11 kinds of buffers and its partition coefficients for the n-octanol-water/buffer solution system,to provide reference for the research and development of new formulations of simvas-tatin. Methods The HPLC method was established and used to detect the concentration of simvastatin in 11 kinds of buffers;the parti-tion coefficients for the n-octanol-water/buffer solution systems of simvastatin were determined by shaking flask method. Results Simvastatin show no difference in solution of equilibrium solubility in different pH buffer. Addition of surfactant can increase the equi-librium solubility of simvastatin by 70 fold,reaching 130 mg/L. Simvastatin had similar oil - water partition coefficient of about 2. 5 in different pHbuffer(lg P=0. 39),with no significant difference. Conclusion Simvastatin is a hydrophobic drug and has poor solubili-ty in water,which belongs to BCSⅡ drugs. Surfactant such as SDS canincrease its solubility in water significantly. Oil-water partition coefficient of Simvastatin is not affected by pH.【期刊名称】《中国药业》【年(卷),期】2016(025)012【总页数】4页(P35-38)【关键词】辛伐他汀;平衡溶解度;表观油水分配系数;高效液相色谱法【作者】王素珍;李荣荣;岳雪;董惠钧【作者单位】聊城大学药学院，山东聊城 252000;聊城大学药学院，山东聊城252000;聊城大学药学院，山东聊城 252000;聊城大学药学院，山东聊城252000【正文语种】中文【中图分类】R927.1;R972+.6辛伐他汀是土曲霉代谢物洛伐他汀的全合成产物，为前体药物，口服后在体内代谢成为活性酸——辛伐他汀酸而发挥作用［1］。