与环境友好的化学-生物法制备D-精氨酸和L-瓜氨酸

L-精氨酸在水溶液中利用自身所产生的碱性溶液,用n(水杨醛):n(1-精氨酸)=0.1:1的水杨醛为催化剂,L-精氨酸可以快速消旋为DL-精氨酸.后以DL-精氨酸为底物,利用粪链球菌(streptococcus faecalis)精氨酸脱亚胺酶对L-精氨酸的专一脱亚胺作用,同时制备D-精氨酸和L-瓜氨酸,分别以92.3%、94.2%产率获得光学纯的D-精氨酸和L-瓜氨酸.     

利用响应面分析法优化鸟苷发酵培养基

目的利用响应面分析法对鸟苷发酵培养基进行优化,提高鸟苷产量。方法采用响应面分析法对鸟苷发酵培养基的3种主要成分葡萄糖、酵母粉和豆饼水解液进行优化。用Design-Expert软件对实验数据进行多元回归分析,并建立3种因素与鸟苷产量之间的函数关系。用最终优化的配方进行3次验证试验。结果通过岭脊分析,获得培养基中3因素最佳浓度为:葡萄糖12.0%,酵母粉1.4%,豆饼水解液4.0%,发酵液鸟苷最高产量可达28.3g/L。3次验证试验所测得的鸟苷产量分别为28.14、28.32和27.86g/L,平均值为28.10g/L,与预测结果基本一致。结论利用响应面分析法可优化鸟苷发酵培养基,显著提高鸟苷的产量。     

Multilayer composite surfaces prepared by an electrostatic self‐assembly technique with quaternary ammonium salt and poly(acrylic acid) on poly(acrylonitrile‐co‐acrylic acid) membranes

An electrostatic self‐assembly technique was applied to prepare ion complex polymer layers on polyacrylonitrile with acrylic acid segments {poly(acrylonitrile‐co‐acrylic acid) [P(AN‐co‐AA)]}. For the ionic complex layers, quaternary ammonium salts, such as cetyl trimethyl ammonium chloride (CTAC) and tetramethyl ammonium chloride (TMAC), were used as cationic species, and also, poly(acrylic acid) (PAA) was used as an anionic species. These cationic and anionic species were self‐assembled alternately on the surface of the P(AN‐co‐AA) membrane. Fourier transform infrared spectroscopy, AFM, and water contact angle measurements of the membrane surface were used to confirm the formation of the multilayer composites on the P(AN‐co‐AA). The permeabilities of water and macromolecules of different molecular weights were evaluated by a membrane filtration technique. The values of permeability strongly depended on the formation layer by layer of these ion composites on the base P(AN‐co‐AA). Through the measurement of the values of the contact angle of water, it was clear that surface nature of the base membrane treated by CTAC or TMAC and PAA dramatically changed. We concluded that such an electrostatic self‐assembly technique is useful for the preparation of multicomposite layers to modify the surface of base P(AN‐co‐AA) membranes. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

驱油用聚丙烯酰胺溶液界面特性研究

使用 TRACKR全自动液滴界面张力仪测量了不同试验条件下十二烷 /聚丙烯酰胺溶液界面扩大、缩小时的流变特征及界面张力 ,开发出了用以表征液膜强度的界面黏弹性 E的测量方法。在十二烷 /聚丙烯酰胺界面形成稳定的过程中界面 (扩张 )黏弹模量不断增加 ,并逐渐达到恒定 ,其中弹性成分所占比例远大于黏性成分即 E′>E″。考察的聚合物浓度范围为 5 0～ 2 0 0 0 mg/ L ,界面黏弹模量从 1 7.6提高到 3 0 .6m N·m-1。放置 3 d后的聚合物溶液界面黏弹模量保留率为 82 .8%。实验结果表明聚合物浓度变化对界面张力影响不显著。     

固定化微生物技术处理废水研究进展

对固定化微生物技术及其所用载体进行了介绍。综述了固定化微生物技术在国内外处理氨氮废水、含酚废水、降解芳香族类化合物以及其他有机废水处理中的研究与应用现状。指出了固定化微生物技术存在的问题，并提出了今后的研究方向。     

由对二氯苯合成3,4-二氟氯苯的研究

报道了由对二氯苯一步直接氟化制备3,4 二氟氯苯的方法。将对二氯苯用硝硫混酸硝化获得2,5 二氯硝基苯,并以氟化钾为氟化剂,在四苯基溴化膦催化下于环丁砜等高沸点溶剂中直接进行氟化,经水蒸气蒸馏和分馏提纯获得产品。硝化收率95%以上,氟化精馏收率49 8%,产品纯度98%以上。     

成骨细胞玻璃化冷冻保护剂的研究

在超低温冷冻过程中,冷冻保护剂(CPA)抑制胞内冰晶形成和避免溶质效应.然而,在其导入和洗脱过程中,由于渗透压的急剧变化将导致细胞大量死亡.本文以成骨细胞为样本,通过测定冷冻保护剂的玻璃化温度、CPA导入和洗脱时渗透压变化及其对细胞活性的影响,研究冷冻保护剂浓度和不同种类保护剂的联合使用对成骨细胞玻璃化冷冻过程的影响.     

高级氧化技术处理煤化工废水研究进展

高级氧化技术是一种新型高效绿色的水处理技术,该技术可以克服传统物化法、生化法的技术缺点,提高废水的可生化性和降解效率。综述了臭氧与非均相催化臭氧氧化技术、催化湿式氧化技术、超声波氧化技术、电化学氧化技术、光催化氧化技术、超临界水氧化技术、芬顿(Fenton)氧化技术等高级氧化技术处理煤化工废水的研究现状,对这些技术做出了评价和比较,并对今后的研究方向提出了建议,即深入研究高级氧化技术的反应机理、优化反应设备、降低反应成本,以达到推进高级氧化技术工业化进程的目的。     

Effects of Four Different Drying Methods on the Quality Characteristics of Peeled Litchis (Litchi chinensis Sonn.)

Four different drying methods, namely, air drying (AD), microwave-assisted vacuum drying (MWVD), coupled microwave–hot air drying (MWAD), and freeze drying (FD), were studied, in terms of drying time, color, reducing sugar content, shrinkage, microstructure, and sensory evaluation. The drying rate of MWVD and MWAD were notably faster than that of AD and FD. The highest reducing sugar content was observed in MWAD, followed by MWVD. No significant differences were observed in reducing sugar between air-dried and freeze-dried products. FD had the best color and shrinkage among the other drying methods. The color and shrinkage of MWVD drying is close to the fresh litchis and much better than hot air and MWAD. Scanning electron microscopy (SEM) images showed that the MWVD and FD litchis have a porous structure, whereas AD and MWAD litchis have a compact structure. The sensory evaluation suggests that peeled litchis dried by the four studied drying methods are of a quality that is accepted by consumers.     

Different microstructure BaO–B2O3–SiO2 glass/ceramic composites depending on high-temperature wetting affinity

In this work, we propose a simple but effective method to fabricate BaO–B₂O₃–SiO₂ glass/ceramic composites with different microstructures that depend on the high-temperature wetting affinity. The experimental results showed that the wetting affinity between oxide ceramic and the BaO–B₂O₃–SiO₂ glass matrix could strongly affect the driving force of densification and crystallization and finally the microstructure of the glass/ceramic composites. It was found that suitable amounts of alumina powders could obviously increase the driving force for sintering of glass by increasing the capillary pressure. In this case, the contact angle between alumina and glass matrix is about 24° at high temperature and a densified and homogeneous microstructure of glass/alumina composite was obtained. On the contrary, rutile powders additive was found to result in higher phase separation and crystallization during the sintering of glass/rutile composites. In this case, the contact angle between rutile and glass matrix is about 124° at high temperature, and the sintered body has a lower dielectric loss than the sample with alumina additive. Therefore, the microstructure and dielectric property of glass/ceramic composites could be controlled by adjusting the ceramic composition and wetting affinity between ceramic additive and glass matrix in our study.