Alkaline Stable Anion Exchange Membranes Based on Cross-Linked Poly(arylene ether sulfone) Bearing Dual Quaternary Piperidines for Enhanced Anion Conductivity at Low Water Uptake

Alkaline stable anion exchange membranes based on the cross-linked poly(arylene ether sulfone) grafted with dual quaternary piperidine (XPAES-DP) units were synthesized. The chemical structure of the synthesized PAES-DP was validated using ¹H-NMR and FT-IR spectroscopy. The physicochemical, thermal, and mechanical properties of XPAES-DP membranes were compared with those of two linear PAES based membranes grafted with single piperidine (PAES-P) unit and conventional trimethyl amine (PAES-TM). XPAES-DP membrane showed the ionic conductivity of 0.021 S cm⁻¹ at 40 °C which was much higher than that of PAES-P and PAES-TM because of the possession of more quaternary ammonium groups in the cross-linked structure. This cross-linked structure of the XPAES-DP membrane resulted in a higher tensile strength of 18.11 MPa than that of PAES-P, 17.09 MPa. In addition, as the XPAES-DP membrane shows consistency in the ionic conductivity even after 96 h in 3 M KOH solution with a minor change, its chemical stability was assured for the application of anion exchange membrane fuel cell. The single-cell assembled with XPAES-DP membrane displayed a power density of 109 mWcm⁻² at 80 °C under 100% relative humidity.     

HIV蛋白酶抑制剂——利迪链菌素的分子对接研究

用分子对接的方法, 对利迪链菌素的抗HIV蛋白酶活性进行了研究. 为了更准确地反映利迪链菌素分子与酶蛋白结合的情况, 充分考虑受体活性部位的柔性, 采用了FlexX(初步对接)和Flexidock(精确对接)分两步将配体与受体进行对接. 在初步对接中, 设计了不同的受体活性部位来考察是否有结合水分子参与抑制剂与酶的结合. 对一种作用方式已知的非肽类HIV蛋白酶抑制剂Aha006进行的对接研究显示, 分子模拟的结果与实际情况吻合得较好, 证明了本文所采用的方法的可靠性. 利迪链菌素与蛋白酶活性部位的对接结果显示, 配体分子与受体之间的结合没有结合水分子的参与, 两者通过5对氢键作用结合成为稳定的复合物. 利迪链菌素占据结合腔, 覆盖了蛋白酶的活性三联体Asp25-Thr26-Gly27, 从而起到抑制其生物活性的作用.     

丙烯酸盐喷膜防水材料在酸碱浸润和冻融循环条件下的耐久性试验分析

丙烯酸盐喷膜防水材料在酸碱溶液浸润和冻融条件下的耐久性能是该类材料在工程应用中较难回避的实际问题,论文采用酸性介质(0.2%的H2SO4溶液)和碱性介质(0.1%NaOH+饱和Ca(OH)2溶液)对该材料进行饱和浸泡并进行冻融循环后,研究了该材料的吸水性、断裂拉伸强度和拉断伸长率的变化规律。试验结果表明:喷膜防水材料在侵蚀-冻融循环作用下,其拉断伸长率和断裂拉伸强度显著降低,且酸性介质对材料拉伸性能的影响较大;材料耐低温冰冻能力较强,耐高温能力较差。反映出丙烯酸盐喷膜防水材料在低温冰冻和碱性介质中耐久性较好,不建议在高温和酸性介质条件下使用。     

天然蚕丝与丝素蛋白多孔膜的生物降解性研究

较为详细地研究了经不同条件处理的丝素蛋白多孔膜材料和天然蚕丝在蛋白酶作用下的降解性能以及降解前后材料的微观形貌和结构的变化. 结果表明, 丝素蛋白材料中不同结构(构象)的含量是影响其降解速度的一个重要因素. 对于由再生丝素溶液所制备的材料, 调控其中Silk II结构(β-折叠构象)的比例可能是控制丝素蛋白材料降解速度的有效途径.     

荧光各向异性法均相检测酸性、中性和碱性介质中的蛋白酶

荧光各向异性;罗丹明;蛋白酶;胰蛋白酶;胃蛋白酶;菠萝蛋白酶;蛋白酶抑制剂     

Optimization of alkaline protease production by Bacillus sp. using taguchi methodology

Optimization of alkaline protease production parameters by Bacillus sp. was investigated using Taguchi methodology. The pH of the medium was observed to be the most significant factor among all selected optimization parameters at an individual level. The combinatorial influence of least significant factors, inoculum level and salt solution concentration (at the individual level), resulted in an interacting severity index of 76%, suggesting their interactive role in the regulation of protease production in this microbial species. Protease production could be improved more than 100% with Taguchi’s optimized conditions of the medium composition by this microorganism.     

纳米Bi-Ni氧化物改性碱性MnO2电极

电化学行为;纳米Bi-Ni氧化物改性碱性MnO2电极     

Thermal behavior of glutamic acid and its sodium,lithium and ammonium salts

Glutamic acid (H2_glu) and its lithium, sodium and ammonium monosalts were submitted to thermal analysis using thermogravimetry (TG) and differential thermal analysis (DTA). The main goal of these studies was to compare the relative thermal stability and to evaluate the effect of the counter ion in the thermal decomposition pathways. Salts were obtained by direct neutralization of the purified acid with LiOH, NaOH or NH₄OH and were characterized by elemental analysis (C, H and N) and IR spectroscopy. Decomposition occurred after conversion to the pyroglutamic acid or the respective pyroglutamates and ammonium salt loosing NH₃ being converted to H₂glu before decomposition.     

分子动力学研究V82A和L90M变异对HIV PR-IDV复合物的影响

为了说明V82A和L90M变异对蛋白酶(PR)和茚地那韦(IDV)复合物的影响,进行了5.5ns的MD模拟.用MM-PBSA方法计算了体系的结合自由能,计算和实验结果一致.分解自由能为不同能量项说明,这两个变异引起熵的贡献变化大于焓的贡献变化.分解自由能到每个残基说明Wild,V82A和L90M具有相似的结合模式,结合能的贡献主要来源于A28/A28',I50/I50'和I84/I84'这六个残基组,详细分析了Wild和IDV的结合模式,对比分析了V82A和L90M变异引起结合模式的细小变化.V82A变异引起结合模式的变化是由于变异后位阻减小导致的.L90M变异引起D25和L90间的作用增强并引起结合模式的细小变化.研究结果有助于更好地理解变异对抑制剂和HIV-1PR结合模式的影响,并可以用来帮助设计更高效的PR抑制剂.     

微波促进碱性离子液体催化合成查尔酮

以4-氯-1-丁醇,N-甲基咪唑和苯甲酸钠为原料,用微波法制得碱性离子液体{[OHBMIM]Ph COO(AIL)},其结构经FT-IR表征;以苯甲醛和苯乙酮为原料,AIL为催化剂,经微波促进的缩合反应合成了查尔酮(1),其结构经1H NMR和FT-IR确证。考察了AIL用量、微波功率、物料比和反应时间对1产率的影响。合成1的最佳反应条件为:AIL 1 mmol,苯甲醛5 mmol,n(苯甲醛)∶n(苯乙酮)=1.1,于微波功率140 W反应5 min,产率95.8%。AIL具有较好的循环使用性,循环使用6次,1产率没有明显降低。