气体分离膜研究进展

全面综述了近几年气体分离膜研究的最新进展,主要包括气体分离膜材料、制膜方法、表征方法三个方面。     

工业废水中溶解态有机物分析方法研究

采用0．45μm玻璃纤维滤膜将工业废水分离为悬浮态和溶解态有机物质,以二氯甲烷为萃取剂,采用液液萃取一气质联用法对工业废水中溶解态有机物进行测定。优化的最佳萃取条件为：每个pH范围各萃取2次,静置时间5min,氯化钠加入量15g。方法的加标回收率为91．1％～103％,测定结果的相对标准偏差小于5％fH=6）。该法分析时间短,易于操作。     

Bioactives of Momordica charantia as Potential Anti-Diabetic/Hypoglycemic Agents

Momordica charantia L., a member of the Curcubitaceae family, has traditionally been used as herbal medicine and as a vegetable. Functional ingredients of M. charantia play important roles in body health and human nutrition, which can be used directly or indirectly in treating or preventing hyperglycemia-related chronic diseases in humans. The hypoglycemic effects of M. charantia have been known for years. In this paper, the research progress of M. charantia phytobioactives and their hypoglycemic effects and related mechanisms, especially relating to diabetes mellitus, has been reviewed. Moreover, the clinical application of M. charantia in treating diabetes mellitus is also discussed, hoping to broaden the application of M. charantia as functional food.     

一种海水中溶解无机碳的准确简易测定方法

海水中的溶解无机碳(DIC)可占海水中总碳的95％以上,其准确测量是研究海洋碳循环的基础。目前测量DIC所使用的仪器较为昂贵、复杂,不适于外海调查。实验设计了一套密封的气提一吸收装置,并通过大量的实验建立了一种简便、快速的DIC现场测定方法,即取大约100～150mL海水,加10％H2PO4将其中的CO2释放出来,用0．1mol／LNaOH进行二级吸收,以酚酞和溴甲酚绿．甲基红混合指示剂指示终点,用HCl标准溶液滴定所吸收的CO2,计算DIC含量。经检验该方法具有较高的精密度和准确度,相对标准偏差为0．76％。用该方法测定了2003年6月取自胶州湾的水样,结果表明：胶州湾内表层水DIC平均为2066μmol／L,底层水为2075μmol／L;湾外表层水平均为1949μmol／L,底层水为2147μmol／L。     

两亲分子结构对铜网表面生长的Cu2S纳米材料形貌的影响

观察到两亲分子的结构对铜网表面生长的Cu2S一维纳米材料的形貌有较大的影响,含羧酸的强亲水型两亲分子--N-硬脂酰-L-谷氨酸有助于形成纳米线,而把两个羧基全部转化为酯基后,则倾向于形成具有分形结构的纳米带.     

Pd-Cu-Clx/Al2O3催化剂对CO氧化的稳定性

CO催化氧化广泛应用于空气净化、机动车尾气治理和CO气体传感器中.在CO氧化催化剂设计与制备过程中,催化剂与使用环境密切相关.例如工业和机动车尾气净化需要在高温(200–600°C)下进行,而对于半密闭空间(隧道或者地下停车场)空气净化需要在室温和高相对湿度下进行.频繁冷启动导致半密闭空间CO浓度累积而超过排放控制标准,因此制备室温、高相对湿度下CO氧化催化剂是面临的重要问题之一.负载型Wacker催化剂对于CO低温催化氧化的研究一直受到广泛关注.环境中少量水的存在会促进负载型Wacker催化剂对CO的低温氧化性能,但随着水沉积量的增加,活性位点将被覆盖,并且Pd和Cu活性组分之间的紧密结构被破坏,从而导致催化剂的失活,即催化剂的稳定性变差.因此,为了提高催化剂在高相对湿度下的稳定性,利用二乙氧基二甲基硅烷对Al2O3载体进行硅烷化处理,以增加载体的疏水性,考察载体疏水改性对CO低温氧化过程中催化剂稳定性的影响.催化剂的稳定性测试结果表明,在0°C,100%相对湿度条件下,未改性催化剂在约20 h内CO转化率由81%下降到50%;载体硅烷化后制备的催化剂在反应进行150 h后,CO转化率仍保持在78%,即反应活性未见降低.由此表明催化剂载体经有机硅烷改性后,可显著增强催化剂在低温、高相对湿度下的稳定性.N2吸附/脱附和水吸附实验结果表明,载体硅烷化改性并未对催化剂的比表面积产生影响,但显著降低了催化剂上水沉积速度和沉积量,未改性催化剂的初始吸水速度是改性后催化剂的4倍,但改性后催化剂的饱和吸水率仅占未改性催化剂的1/3.X射线衍射结果表明,载体预处理后活性物种Cu2(OH)3Cl晶粒尺寸有所增加.氢气程序升温还原、X射线光电子能谱结果表明,载体硅烷化预处理改善了催化剂中Cu和Pd物种的化学分布及接触状态,增加了与Pd物种紧密接触的Cu物种的量,从而促进了Cu物种的还原.与此同时,载体硅烷化显著降低了催化剂表面Cl离子的浓度,从而影响到对CO吸附.为了进一步研究水与催化剂稳定性之间的关系,采用原位红外漫反射(In situ DRIFT)对催化剂进行表征.负载型Wacker催化剂对CO氧化反应机理为:Pd是CO氧化反应的活性中心,通过Pd和Cu物种之间的氧化还原循环来实现CO氧化,且Pd+比Pd2+具有更高的CO氧化性能.反应气氛中水的存在,有利于CO在Pd+上氧化、以及金属态Pd被Cu2+物种再氧化的过程,同时水也显著促进了催化剂表面碳酸盐的生成以及抑制了活性物种Pd+生成.与表面碳酸盐累积相比,水对于活性物种Pd+生成的抑制作用是导致催化剂活性降低的主要原因.     

A High Efficiency PDMS-Based Stabilizer for Dispersion Polymerization of L-lactide in Supercritical Carbon Dioxide

Dispersion polymerization of lactides and lactones has been studied and has received a great deal of attention used to prepare biodegradable polymers in supercritical carbon dioxide (ScCO₂). The triblock copolymers of poly(?-caprolactone) PCL-polydimethylsiloxane (PDMS)-poly(?-caprolactone) PCL by the feed ratio of 1:2:1 and 1:3:1, respectively were synthesized to be used as the stabilizers in the dispersion polymerization of L-lactide. The fine poly(L-lactide) (PLLA) powders were obtained at the concentrations of 3% to 5%w/w (stabilizer/monomer). The results demonstrated that the triblock copolymers were the effective stabilizers for the dispersion polymerization of L-lactide. It was also found that the cooling process had a significant effect on the particle size of the fine powders. In order to obtain the best PLLA powders, it would be necessary to use the cooling process with stirring.     

乙烯基Ia3d介孔硅分子筛的环氧化及其固定化青霉素酰化酶(英文)

采用直接共聚法合成表面含有乙烯基的具有立方相Ia3d结构的介孔硅分子筛(V-ClMS),然后对乙烯基团进行环氧化制备得到表面环氧基功能化的介孔硅分子筛(E-CIMS),采用X射线衍射、N2吸附-脱附、透射电镜、热重分析和13C固体核磁共振对制备的介孔硅分子筛进行了表征.结果表明,表面含有乙烯基的V-ClMS介孔硅分子筛能被一步成功合成,并易于发生环氧化而获得表面环氧基功能化的E-CIMS介孔硅分子筛.将E-CIMS介孔硅分子筛作为载体用于固定化青霉素G酰化酶(PGA),研究了表面环氧基团对固定化PGA初活性和操作稳定性的影响.结果表明,随着表面环氧基团数量的增加,介孔硅分子筛孔径减小,表面疏水性增加,导致载酶量和初活性减小.但介孔硅分子筛表面适量的环氧基团能增强E-CIMS介孔硅分子筛与PGA之间的相互作用,从而提高固定化PGA的操作稳定性.     

Coupled atomic-molecular condensates in a double-well potential: decaying molecular oscillations

We present a four-mode model that describes coherent photo-association (PA) in a double-well Bose-Einstein condensate, focusing on the average molecular populations in certain parameters. Our numerical results predict an interesting strong-damping effect of molecular oscillations by controlling the particle tunnellings and PA light strength, which may provide a promising way for creating a stable molecular condensate via coherent PA in a magnetic double-well potential.