纤维素氨基甲酸酯膜的制备及性能

采用碱/尿素/水体系对实验室自制的纤维素氨基甲酸酯(N%-1.8)在双螺杆中进行低温溶解,过滤、脱泡,得到清亮的纤维素氨基甲酸酯溶液。探讨制膜液浓度、凝固浴浓度、凝固浴温度,凝固时间对再生膜力学性能的影响,并结合FT-IR、XRD、SEM对膜的结构和形貌进行表征。结果表明,制膜液浓度为4.5wt%,凝固浴为H2SO4-8%、HOAc-16%和H2SO4/Na2SO4-7%/9%,凝固温度20~30℃,凝固时间为5min时所得的膜具有较好的力学性能,抗拉强度达到60~70MPa,断裂伸长率为6~10%。     

Synthetic and Crystallographic Insight into Exploiting sp2 Hybridization in the Development of α-l-Fucosidase Inhibitors

The sugar fucose plays a myriad of roles in biological recognition. Enzymes hydrolyzing fucose from glycoconjugates, α-l -fucosidases, are important targets for inhibitor and probe development. Here we describe the synthesis and evaluation of novel α-l -fucosidase inhibitors, with X-ray crystallographic analysis using an α-l -fucosidase from Bacteroides thetaiotamicron helping to lay a foundation for future development of inhibitors for this important enzyme class.     

液相色谱-串联质谱法测定进出口人参、西洋参中蚜灭磷等6种农药

建立了人参、西洋参中凝胶色谱-固相萃取-液相色谱-串联质谱法测定蚜灭磷、吡虫啉、涕灭威、甲基内吸磷、甲硫威、辛硫磷6种农药的分析方法。样品经丙酮超声提取,凝胶色谱(GPC)净化后,固相萃取(SPE)净化,在HPLC/MS/MS多反应监测(MRM)模式下进行了定性和定量分析方法。在上述检测方法条件下,所测的6种农药的最低检出限为0.01 mg/kg,回收率范围为79.2%~107.3%,线性范围为0.01~0.2 mg/kg。     

Characteristics of CO2 Absorption into Aqueous Ammonia

Abstract

Aqueous ammonia was investigated as a new absorbent of the chemical absorption process for CO₂ capture from combustion flue gas. The effects of the temperature and concentration of aqueous ammonia on CO₂ absorption in a semi‐batch reactor were studied by interpreting breakthrough curves. Raman spectroscopy analysis of CO₂ loaded aqueous ammonia provided concentration changes of bicarbonate, carbonate, and carbamate as well as CO₂ sorption capacity at given time during the absorption with 13 wt% aqueous ammonia at 25°C. It was observed that carbamate formation was dominating at the early stage of absorption. Then, the bicarbonate formation took over the domination at the later stage while the carbonate remained unchanged.     

Selected Saccharomyces cerevisiae yeast strains and accurate separation of distillate fractions reduce the ethyl carbamate levels in alembic cachaças

Ethyl carbamate (EC) is a potentially toxic compound that may be present at concentrations above maximum limits established in alcoholic beverages, such as cachaça. Most traditional alembic cachaça is produced on a small scale using empirical knowledge. The fermentation step is conducted using yeasts that are endogenous to the sugar cane, and the distillation process is relatively uncontrolled. In this study, gas chromatography coupled with mass spectrometry was used to determine the EC levels in distillate musts and fractions produced by spontaneous or selected Saccharomyces cerevisiae strains. The aim was to verify the influence of selected strains as starters for fermentation compared with spontaneous fermentation on EC formation. The distillate fractions from these two production processes were also analysed. Our results demonstrated higher levels of EC (which surpass the limits defined by Brazilian law) in cachaças produced by spontaneous fermentation (50%) compared with the selected strains (30%); and the distillation step showed great contribution for the reduction of the compound. From must to distillate fractions we found an average decrease on EC levels of 62% using selected strains and 44% for the spontaneous fermentation. In addition, careful separation of the distillation fractions was crucial for producing high-quality and safe beverages.     

农药作为海洋防污剂的应用

纵观海洋防污剂发展史，我们可以发现它和农药之间有着不解之缘，也可以说农药的发展推动了防污剂的发展。文章对曾经用过、正在使用、有可能应用为海洋防污剂的农药品种逐一介绍。     

Nonthermal plasma for pesticide and microbial elimination on fruits and vegetables: an overview

Nonthermal plasma (NTP) is defined in terms of partly ionised gas which overall temperature is quite low because the stored energy is mostly in free electrons. Applications of NTP have been expanded to new areas of food applications such as the microbial inactivation and also the elimination of pesticide and toxic chemical residues in food such as fruits and vegetables while nutritional content and key characteristics are still preserved. Plasma treatment has successfully decreased the concentrations of pesticides by about 45‐71%. In this article, NTP technologies as well as investigations about applying of NTP for removing pesticide residues and improving microbial safety in fresh produce are described. Potential applications of NTP in food processing together with some of their challenges and limitations are also discussed.     

DYNAMICALLY VULCANIZED THERMOPLASTIC ELASTOMER BLENDS OF NATURAL RUBBER AND POLYPROPYLENE

Dynamic vulcanization of a soft grade of thermoplastic natural rubber (TPNR) was carried out using several concentrations of Hexamethylene N, N′ bis (tert-butyl peroxy carbamate) (HBTP). The blends were melt mixed in a Brabender plasticorder. The effectiveness of dynamic vulcanization was investigated using the Brabender plastograms, swelling index measurements, rheological behavior by means of a capillary rheometer, dynamic mechanical properties, and tensile testing. It was found that varying the HBTP concentration had a great influence on the rheological behavior as well as the dynamic and tensile properties of the material. The increase of HBTP dosage resulted in an increase of the extent of crosslinking and caused an increase of the elastic modulus and a reduction of the loss modulus. The ultimate tensile strength and elongation at break also increased with increasing HBTP loading. The rheograms indicated that the blends exhibit a pseudoplastic behavior.     

全球氨基甲酸酯类杀虫剂专利分析

从宏观分布、技术发展特点、技术生命周期特征3方面分析研究了全球氨基甲酸酯类杀虫剂新化合物、新工艺和新制剂发展态势,预测了其未来发展趋势.     

65%吡虫啉悬浮剂的研制

介绍了农药悬浮剂的加工方法及其优点,介绍了吡虫啉悬浮剂在同类杀虫剂中的优势,通过(50±2)℃热储对润湿分散剂,增稠剂,防冻剂进行了筛选,采用湿法研磨得出最佳配方:吡虫啉65%,改性磷酸酯盐(以AP表示)4%,木质素磺酸钠1%,黄原胶(1.5%黄原胶母液)1%,乙二醇3%,水余。经测定悬浮率95%以上,热储(50±2)℃,分解率<5%,产品各项指标符合悬浮剂要求。