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91.
桑蚕丝素蛋白初始结构对其矿化作用的影响 总被引:4,自引:0,他引:4
以碱金属离子诱导桑蚕丝素蛋白溶液发生构象转变, 研究了蛋白质初始结构对其矿化作用的影响. FT-IR, XRD和SEM等测试结果显示, 未经任何处理的桑蚕丝素蛋白溶液矿化后形成片状复合物, 其无机相以二水磷酸氢钙(DCPD)为主; 而经过K+和Na+金属离子处理后, 桑蚕丝素溶液的结构由无规线团/螺旋构象向β-折叠发生转变, 矿化后成纤维状, 并相互结合呈现纳米级的三维多孔结构, 其无机相以热力学稳定的羟基磷灰石(HA)为主. 可以认为, 丝素蛋白结构转化为较伸展的β-折叠后, 使得更多的亲水基团暴露在外面, 在丝素蛋白分子不断凝聚成纤过程中, HA结晶快速生长并附着在这些微纤上, 最终形成纤维状的丝素蛋白/HA复合物. 该结果为阐明蛋白质的生物矿化过程及其调控机理提供了理论依据, 同时可以从矿化复合物的形成来反映这些微量元素可能对骨组织形成的影响, 为临床骨组织的修复提供一定的参考. 相似文献
92.
Stability constant for mercury binding by commercial and natural humic acids (HA) were determined using a new potentiometric mercury(II) sensor based on dithiosalicylic acid modified carbon paste electrode. The sensor present a high selective and sensitive response to mercury(II) ions, and a low detection limit of 1.8×10?8 M. The potentiometric titrations curves of humic acids against mercury(II) ions were modeled. For 1.00×10?7 to 3.00×10?4 M mercury(II) ion concentration levels the results are consistent with the presence of two different binding sites in the humic acid macromolecule. The strongest binding sites (log K1 ranging from 10.1 to 6.8) are probably due to interaction with carboxylic acid and amine groups in the molecule, whereas weakest binding sites (log K2 ranging from 8.8 to 4.5) can be associated to phenolic groups. 相似文献
93.
The effect of low-energy ion bombardment on CD4/O2 and CF3X (X=F, Cl, Br) plasma etching has been assessed by applying controlled rf bias voltages on polystyrene (PS) and polymethylmethacrylate (PMMA) samples. In both cases ion bombardment has been found to have a chemical effect. In the case of CF4/O2 discharges, ion bombardment has been found to change the relative etching efficiency of different mixtures. In the case of CF3X plasmas, ion bombardment has been found to alter PMMA and PS etch rates in a different way. In particular, the ratios between CF4 and CF3X (X=Cl, Br) etch rates of PS have been found to decrease with increasing bias voltage. This effect has been tentatively attributed to an ion bombardment-induced enhancement of the reaction between the aromatic ring and halogen molecules formed in CF3Cl and CF3Br discharges. 相似文献
94.
95.
以铜离子为模板的褐藻酸凝胶对铜离子的选择性富集研究 总被引:2,自引:0,他引:2
以铜离子为模板,制备了褐藻酸凝胶(Cu-alginate),通过吸附实验及过柱渗滤实验,试验了该吸附剂对铜离子的选择性吸附性能,并且采用该吸附剂富集了自来水中微量的Cu^2 ,结合原子吸收法测定了水样中Cu^2 的含量。结果表明:该吸附剂对Cu^2 有较高的选择性吸附性能,显著优于一些化学合成铜离子模板缩聚物及非铜模板褐藻酸凝胶(如Ca-alginate),非重金属离子(如K^ 、Na^ 、Ca^2 )及某些重金属离子(如Ni^2 、Cd^2 )等对Cu^2 的吸附均不产生明显干扰。用该吸附剂富集水中的微量铜离子,回收率可达97.7%。 相似文献
96.
《中国化学快报》2019,30(9):1659-1662
The development of efficient methods for the detection of hazardous and toxic elements is extremely important for environmental security and public health. In this work, we developed a facile colorimetric assaying system for Ag+ detection in aqueous solution. Chitosan-stabilized platinum nanoparticles (Ch-PtNPs) were synthesized and severed as an artificial oxidase to catalyze the oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) and generate color signal. In the presence of Ag+, due to the strong metallophilic interactions between Ag+ and Pt2+ on the surface of Ch-PtNPs, Ag+ can weaken the affinity to the substrates and inactivate the catalytic activity of Ch-PtNPs, leading to decreased absorbance signal to varying degrees depending on Ag+ amount. Combing the specific binding between Ch-PtNPs and Ag+ with signal amplification procedure based on the Ch-PtNPs-catalyzed TMB oxidation, a sensitive, selective, simple, cost-effective, and rapid detection method for Ag+ can be realized. Ag+ ions in tap and lake waters have been successfully detected. We ensured that the proposed method can be a potential alternative for Ag+ determination in environmental samples. 相似文献
97.
A total synthesis of d-(+)-biotin is described starting from d-(+)-glucosamine using acyliminium chemistry. 相似文献
98.
99.
W. Kunz J. Barthel L. Klein T. Cartailler P. Turq B. Reindl 《Journal of solution chemistry》1991,20(9):875-891
A variety of methods has been used for the study of lithium bromide solutions in acetonitrile yielding by their combination reliable information on different levels of approximation. Osmotic coefficients based on precise vapor pressure measurements are reproduced by CM (chemical model) and HNC (hypernetted chain) calculations and by BD (brownian dynamics) simulations. The results of neutron scattering experiments are treated with the help of HNC and BD methods. Hartree-Fock calculations on isolated LiBr pairs and solvated lithium ions yield reliable particle distances and reveal the geometry of the lithium solvation sphere. 相似文献
100.