Detailed Insight into the Interaction of Bicyclic Somatostatin Analogue with Cu(II) Ions

Somatostatin analogues are useful pharmaceuticals in peptide receptor radionuclide therapy. In previous studies, we analyzed a new bicyclic somatostatin analogue (BCS) in connection with Cu(II) ions. Two characteristic sites were present in the peptide chain: the receptor- and the metal-binding site. We have already shown that this ligand can form very stable imidazole complexes with the metal ion. In this work, our aim was to characterize the intramolecular interaction that occurs in the peptide molecule. Therefore, we analyzed the coordination abilities of two cyclic ligands, i.e., P1 only with the metal binding site and P2 with both sites, but without the disulfide bond. Furthermore, we used magnetic circular dichroism (MCD) spectroscopy to better understand the coordination process. We applied this method to analyze spectra of P1, P2, and BCS, which we have described previously. Additionally, we analyzed the MCD spectra of P3 ligand, which has only the receptor binding site in its structure. We have unequivocally shown that the presence of the Phe-Trp-Lys-Thr motif and the disulfide bond significantly increases the metal binding efficiency.     

酸碱理论在现代有机反应的应用

酸碱理论是一个重要无机化学理论,在无机化学中有着重要的作用,同时在有机化学中也有着广泛的应用。本文简单介绍了现代酸碱理论的发展,简单概述了几个在有机化学中常用的酸碱理论:酸碱质子理论、酸碱电子子理论、软硬酸碱理论。同时简要讲述酸碱质子理论、酸碱电子子理论在有机反应中的应用,以及在某些有机合成方面的应用实例。     

维生素C含量测量不确定度评定

用已知浓度的碘（1/2I2）液滴定维生素C溶液来求其含量。得出用碘滴定维生素C含量的测量不确定的主要影响因素有称样量、含量重现性、滴定过程,维生素的扩展不确定度U=0.28%,k=2。     

滴定法测定丙森锌的含量

采用滴定法测定丙森锌的含量。该方法的标准偏差为0.162,变异系数为0.23,平均回收率为96.7%～102.4%,方法线性关系良好,其相关系数为0.999 6。     

烧碱中控分析中氯化钠含量测定方法的探讨

对汞量法、银量法和改进的银量法对烧碱中控分析中氯化钠含量的测定方法的优缺点进行了对比实验,并进行了讨论。实验结果表明,汞量法和改进的银量法能够降低大量材料成本(年节约10～18万元)、灵敏度高、终点变色敏锐,更适合中控分析。     

水相电位滴定法测定木质素的酚羟基和羧酸基含量

引言木质素是自然界中仅次于纤维素的第二大可再生资源,是人类未来的主要资源来源[1]。以木质素为原料制备新材料和化工原料,逐步替代化石等日趋枯竭的不可再生资源,正成为一种新的发展趋     

EDTA络合滴定法测定赤泥盐酸浸出液中的铝

考察了EDTA络合滴定法中各影响因素。结果表明,加入1＋1乳酸2mL即可掩蔽溶液中的Ti4＋离子;EDTA的加入量以相对于铝过50％为宜;选用二甲酚橙作指示剂,通过控制溶液pH值可使滴定终点敏锐而准确;加热煮沸2rain～2．5min可使络合反应完全。采用本法测定盐酸浸出液中的铝,RSD（n=6）仅为0．625％-1．266％,加标回收率100．1％～102．3％,测定结果比较稳定。     

混酸（氢氟酸、硫酸）分析

在氟化工行业中,需快速、准确地分析混酸（硫酸、氢氟酸）各组分含量,为生产工艺提供可靠数据,及时调整工艺。本文介绍了几种分析方法,着重介绍了电位滴定分析法。     

3,4,5-三甲氧基苯甲酸含量测定方法的研究

比较了采用高效液相色谱法和化学滴定法2种方法测定3,4,5-三甲氧基苯甲酸的含量,提出了测定操作的实验条件,并对测定结果进行统计分析,以判断和评价2种方法的准确性和实用性。经过Grubbs检验表明2种方法的测定数据均无异常值;通过偏态系数和峰态系数来检验方法的正态性分布,统计结果表明2种方法均遵从正态分布;同时进行了2种方法测定值的均数检验（t检验）,结果表明二者的测定值无显著性差异。高效液相色谱法的测定值有更高的准确度和精密度,可以作为首选,在不具备色谱仪的情况下也可使用化学滴定法。     

On the Predominant Electron-Donicity of Polar Solid Surfaces

The reasons for the predominant electron-donicity of almost all solid polar surfaces and its implications are discussed in this paper. By contact angle or interfacial tension measurements, the electron-accepting as well as the electron-donating properties of polar liquids can be ascertained, through the interplay between their energies of adhesion and cohesion. For the solid-liquid interface, direct interfacial tension measurements are not possible, but indirectly, solid/liquid interfacial tensions of polar systems can be obtained by contact angle measurement. However, as the energy of cohesion of a solid does not influence the contact angle formed by a liquid drop placed upon its surface, one can only measure the solid surface'ks residual polar property, manifested by the energy of adhesion between solid and liquid. This residual polar property is of necessity the dominant component; in most cases this turns out to be its electron donicity. When, by means of contact angle measurements with polar liquids, both electron-accepting and electron-donating potentials are found on a polar solid, it is most likely still partly covered with a polar liquid: usually water. The amount of residual water of hydration of a polar solid follows from its polar (Lewis acid-base) surface tension component (γ^AB). The degree of orientation of the residual water of hydration on a polar solid can be expressed by the ratio of the electron-donating to electron-accepting potentials (γ^⊖/γ^⊕), measured on the hydrated surface.