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The use of pressure-volume-temperature (PVT) studies in processing of a biodegradable plastic composition made from soy protein
isolate and corn starch is described. The ability of PVT measurements to predict the combined effects of pressure, volume,
and temperature effects is demonstrated. The results show that the PVT relations of the plastic can be predicted by using
a regression analysis similar to the Tait equations of state. A change in slope of the PVT curves was observed at around 80‡C,
which is ascribed to the glass-transition process of the plastic. Evidence of onset of thermal degradation of the plastic
was observed at ca. 160‡C under 0 to 200 MPa isobaric pressure. This thermal degradation precluded determination of the crystal
melting point of the plastic. 相似文献
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土著致病菌及其胞外物在生物防治斑马贝中的作用 总被引:5,自引:0,他引:5
无脊椎动物斑马贝(Dreissena polymorpha) 的生物污损造成了巨大的经济损失,而应用从斑马贝体内分离出的土著菌株及其体外代谢产物对它进行生物防治是一种经济效益显著且对环境友好的方法.本文主要报导从斑马贝体内分离的土著菌株中筛选出致病菌并研究该细菌及其代谢产物对它的控制作用.在三十多种土著菌株中,中间气单胞菌( Aeromonas media),维罗纳气单胞菌(A. veronii),杀鲑气单胞菌杀鲑亚种(A. salmonicida subsp. salmonicida)和腐败希瓦氏菌(Shewanella putrefaciens)是幼体斑马贝的致命致病菌.当接种量为每只斑马贝107 个细菌时,接种中间气单胞菌、杀鲑气单胞菌杀鲑亚种和腐败希瓦氏菌的5 d 死亡率为100%,而维罗纳气单胞菌为65%.通过扫描电镜(SEM)发现,垂死的斑马贝肌肉组织被破坏并含有大量的细菌.4种细菌代谢产物的不同组分表现出对斑马贝不同的致死效果,在所研究的3种不同Mr组分中(Mr<5×103,5×103~10×103及>10×103),>10 ×103组分具有最高致死率.这些结果为控制贝类无脊椎动物的生物污损提供了新方法. 图4 参24 相似文献
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Methyl ten-butyl ether (MTBE), a gasoline additive, possesses serious problems to the environmental health. In the present study, a bacterial culture named A-3 which could effectively degrade MTBE was isolated from the MTBE contaminated soil. The isolate was identified as Chryseobacterium sp., a new species capable of degrading MTBE. In order to enhance its degradation ability, selected environment factors were investigated. The results showed that the optimal temperature was in the range of 25-30℃, the pH was 7.0, the inoculum size was 2 × 10^8 CFU/ml and the optimal concentration of MTBE was from 50 to 100 mg/L. The maximum MTBE utilization rate (Vmax) was 102 nmol MTBE/(mg cell protein.h). Furthermore, it was found that the isolate could also degrade tert-butyl alcohol (TBA). The degradation rates of TBA were much faster than those of MTBE. The additional TBA would lead to the decrease of the initial MTBE degradation rate and the inhibitory effect of TBA increased with the increase of TBA concentration. Similar protein profiles at least seven peptides were demonstrated after SDS-PAGE analysis of crude extracts obtained from the cells growing in MTBE and TBA culture. 相似文献
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异养硝化/好氧反硝化菌的分离鉴定及其在不同培养条件下产N_2O研究 总被引:5,自引:1,他引:4
以乙酰胺为唯一碳氮源分离纯化出2株既能异养硝化又能好氧反硝化的菌株XM1和HX2,革兰氏阴性,分别为链状杆菌和球状菌.在富集培养基中,菌株HX2产N2O量为XM1的76倍;两菌株均能分别以葡萄糖、甘露醇、酒石酸钠为唯一碳源进行生长;也可分别以硝酸钠和硫酸铵为唯一氮源进行硝化和反硝化作用,但菌株XM1生长速率快于HX2,且有较多的NO2-积累.部分长度的16S rDNA序列分析表明,菌株XM1与HX2的序列与Pseudomonas sp.具有99%的相似性,定为假单胞菌属(Pseudomonas sp.).两菌株27d反接种培养实验结果表明,在添加外源N的条件下,HX2菌株更适合在30%的土壤水分(WFPS)条件下生长,N2O产生量为(36.01±2.48)ng/g,为60%WFPS条件下N2O产生量的1.9倍;而菌株HX1则适合在60%的水分条件下生长,在该条件下几乎不产生N2O. 相似文献
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《Journal of environmental science and health. Part. B》2013,48(1):199-207
Abstract The objective of the present study was to examine the combined effects of zinc compounds with different acidic pH levels on the aerobic growth of a S. typhimurium poultry isolate in either rich or minimal media. When overall main effects of pH levels of medium or concentrations of Zn compounds were compared, growth rates of the S. typhimurium poultry isolate were significantly ( p < 0.05) decreased by stepwise increase of pH levels of medium (pH 4, 5, 6, and 7) or concentrations (0.67, 3.35, and 6.03%) of Zn compounds (Zn acetate and Zn sulfate). In general growth rates of S. typhimurium poultry isolate appeared to be more reduced by Zn acetate than by Zn sulfate and more reduced in minimal media compared to rich media. 相似文献
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Wet Strength and Water Resistance of Modified Soy Protein Adhesives and Effects of Drying Treatment 总被引:7,自引:0,他引:7
Zhikai Zhong X. Susan Sun Donghai Wang Jo A. Ratto 《Journal of Polymers and the Environment》2003,11(4):137-144
Soy protein isolate (SPI) was modified using sodium dodecyl sulfate (SDS) and guanidine hydrochloride (GuHCl). Adhesion performance of the modified SPI on fiberboard was studied. The Water-soluble mass of the modified SPI adhesives was examined following modified ASTM D5570. The SDS-modified SPI containing 91% protein had a water-soluble mass of 1.7%. To be considered a water-resistant adhesive, the water-soluble mass of adhesive should be less than 2%. The wet shear strength test showed 100% cohesive failure within fiberboard, indicating that the modified SPI has good water resistance. The effect of drying treatment on adhesion performance of the SDS-modified SPI on fiberboard was then investigated. Drying treatment significantly affected the final adhesion performance. Shear strength did not change much, but the percentage of cohesive failure within fiberboard increased markedly as drying temperature increased. All the unsoaked, soaked, and wet specimens glued by the adhesives treated at 70° or 90°C had 100% cohesive failure within fiberboard. Viscosity also increased greatly with an increase in drying temperature. This information will be useful in developing low-cost adhesive processing system in the future. 相似文献
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辽东湾北岸滨海湿地降解苯甲酸类化合物的微生物研究 总被引:3,自引:0,他引:3
用富集培养法从辽东湾北岸滨海湿地土壤中分离到以苯甲酸为唯一碳源和能源的细菌9株。经鉴定BJI、BJ2属于不动杆菌属(Acinetobacter sp),BJ3,BJ9,BJ8属于假单胞菌属(Pseudomonas sp),BJ4,BJ5,BJ6,BJ7属于无色杆菌属(Achromobacter sp)。考察了菌株的底物特异性。通过比较单菌株和混合菌的降解效果,得出了优势混合菌。其最适降解条件为:pH8.0,温度25℃,时间48h。 相似文献
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阿特拉津降解菌株的分离、鉴定及降解特性研究 总被引:2,自引:0,他引:2
通过贫营养原水曝气培养法,以SBR方式驯化和稳定运行2个月,分离得到1株能够降解除草剂阿特拉津的降解菌株,命名为L-6.在以阿特拉津为唯一氮源(500 mg.L-1)的无机盐液体培养基中培养96 h后,降解率达到89.2%.扫描电镜观察发现该降解菌株细胞呈长杆状.提取菌株的DNA,进行16S rRNA基因序列分析,并构建系统进化树.结果表明该菌株与GenBank数据库中多株Pseudomonas菌株16S rRNA基因的同源性在99%以上.结合生理生化检测,判断该降解菌为假单胞菌属(Pseudomonas sp.).碳源利用实验发现,降解菌株L-6可以利用葡萄糖、果糖和柠檬酸钠生长,不能利用蔗糖、乳糖和淀粉.环境因素对降解效率的影响实验表明,温度在30℃,初始pH 7~9条件下,降解效率最佳. 相似文献
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