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61.
Sodium-dicyclohexyl- 18-crown-6 complex cation was used as carrier for the uphill transport of zinc as Zn(SCN)42? complex anion. By using L-cysteine as a metal ion acceptor in the receiving phase at the optimized pH of 7.6, the amount of zinc transport through the liquid membrane after 90 min was 97.2 ± 1.0%. The selectivity and efficiency of zinc transport from aqueous solutions containing equimolar mixtures of Ag+, Cd2+ Co2+, Cu2+, Fe2+, Ni2+, Pb2+, Pd2+, Sr2+, Bi3+, Cr3+ and Fe3+ ions was investigated. In the presence of NH2OH.HCl as a suitable masking agent in the source phase, the interfering effect of Cu2+ and Pb2+ ions was diminished drastically. 相似文献
62.
从两二酸二乙酯、氯乙酸乙酯和氯苄出发,经LiAlH4还原,合成新的二元醇,进而合成新的螺环化合物:3,9-二羟乙基-3',9'-二苯甲基-1,5,7,11-四氧杂螺[5,5]十一烷.该化合物的结构由它的氢和碳-13核磁共振谱、红外光谱和元素分析得到证明.该单体在三氟化硼乙醚络合物的作用下进行开环聚合反应.由于环上四个取代基的稳定作用,聚合物的收率比较低(产率10%左右).通过对聚合物的结构分析,提出了这一单体的阳离子开环聚合反应机理.对随聚合温度升高,聚合物中酯基/苯基的克分子比降低,以及本体聚合时得到交联聚合物等一系列现象作了探讨. 相似文献
63.
A comparison is made between the distribution of residue preferences, three dimensional nearest neighbour contacts, preferred rotamers, helix-helix crossover angles and peptide bond angles in three sets of proteins: a non-redundant set of accurately determined globular protein structures, a set of four-helix bundle structures and a set of membrane protein structures. Residue preferences for the latter two sets may reflect overall helix stabilising propensities but may also highlight differences arising out of the contrasting nature of the solvent environments in these two cases. The results bear out the expectation that there may be differences between residue type preferences in membrane proteins and in water soluble globular proteins. For example, the -branched residue types valine and isoleucine are considerably more frequently encountered in membrane helices. Likewise, glycine and proline, residue types normally associated with `helix-breaking' propensity are found to be relatively more common in membrane helices. Three dimensional nearest neighbour contacts along the helix, preferred rotamers, and peptide bond angles are very similar in the three sets of proteins as far as can be ascertained within the limits of the relatively low resolution of the membrane proteins dataset. Crossing angles for helices in the membrane protein set resemble the four helix bundle set more than the general non-redundant set, but in contrast to both sets they have smaller crossing angles consistent with the dual requirements for the helices to form a compact structure while having to span the membrane. In addition to the pairwise packing of helices we investigate their global packing and consider the question of helix supercoiling in helix bundle proteins. 相似文献
64.
In this work, the gold nanoparticle self-assembly behavior of mica-surface-confined polyelectrolyte/surfactant complex films was investigated. First, modified partially hydrated polyacrylamide (MHPAM)/hexadecyltrimethylammonium bromide (CTAB) complex films were deposited on the mica surface using Langmuir–Blodgett technique. Then, the preadsorbed MHPAM/CTAB complex film mica plate was dipped into the gold aqueous solution and the interesting fractal nanostructured gold network was formed. In addition, the effect of dipping time on gold nanoparticle self-assembly morphology was studied. The mechanism of formation process is briefly proposed. 相似文献
65.
用电纺法制备了TiO2/P(VdF-HFP)(聚偏氟乙烯-六氟丙烯共聚物)杂化纤维微孔膜, 用SEM观察了杂化纤维微孔膜的形貌, 并测算了这类由超细纤维相互搭接而形成的微孔膜的孔隙率. 这种微孔膜吸附LiPF6/EC-DMC-EMC(碳酸乙烯酯-二甲基碳酸酯-碳酸甲乙酯)电解质溶液后得到凝胶聚合物电解质膜. 用电化学方法测试了聚合物电解质膜的离子电导率、锂离子迁移数等参数, 并研究了TiO2纳米晶的掺入对聚合物电解质电化学性能的影响. 结果表明, TiO2的掺入降低了P(VdF-HFP)聚合物基体的结晶度, 改善了凝胶聚合物电解质的低温电化学性能. 相似文献
66.
基于芘的荧光熄灭的单质碘荧光敏感膜的研究 总被引:8,自引:0,他引:8
单质碘熄灭固定于增塑的PVC膜中的芘的荧光,且这种熄灭作用可逆。本据此研制了用于测定单质碘浓度的荧光敏感膜,最佳膜组成为2~4mg芘、50mgPVC粉、100mg邻苯二甲酸二异辛酯,测定碘的浓度范围为2.26×10^-5~1.04×10^-3mol/L。此膜测定单质碘的重现性好,响应时间小于40s。除Fe^3+、Bi^3+外,其它常见离子均无干扰。将此膜用于食盐中碘的测定,结果令人满意。 相似文献
67.
Jingye Li Fumihiro Muto Akihiro Oshima Masakazu Washio Shigetoshi Ikeda Yoneho Tabata Chihiro Matsuura 《European Polymer Journal》2006,42(6):1222-1228
New proton exchange membranes (PEMs) were prepared by pre-irradiation induced grafting of α-methylstyrene (AMS)/styrene (STY)/divinylbenzene (DVB) into the crosslinked polytetrafluoroethylene (RX-PTFE) films and successively sulfonated. The new PEMs showed the improved glass transition temperature and chemical stability as compared with the PEMs prepared by pre-irradiation induced grafting of STY/DVB. The balance of the cost, grafting kinetic, thermal properties and the properties of the resulted proton exchange membrane is the key point of this work. 相似文献
68.
建立了处理双原子分子-表面相互作用的推广的LEPS势.借助推广的LEPS势,系统研究了一氧化碳分子在铂低指数表面吸附的动力学特性,重现了低指数表面的分子吸附热、吸附几何及本征振动等实验数据;鉴定了某些不合理的文献信息,预测了实验尚未探测到的重要信息:预测到Pt(100)表面四重洞位的C-O伸缩振动频率为1 962.60 cm-1;预测到Pt(110)表面吸附态的C-O及C-Pt键长分别为115.1、147 pm. 相似文献
69.
We propose a numerical procedure for the calculation of the electrostatic repulsion force between two identical, parallel surfaces immersed in anab electrolyte solution. These surfaces are coated with an ion-penetrable membrane carrying fixed charges. The amount of fixed charges is governed by the dissociation of the functional groups in the membrane phase. The effect of pH on the degree of dissociation of these functional groups is taken into account. The difficulty of extensive use of Jacobi elliptic function in the numerical treatment of Poisson-Boltzmann equation can be circumvented by resorting to the present algorithm. 相似文献
70.