双冠醚研究(Ⅳ)——Schiff碱型和仲胺型双-(苯并15冠-5)对碱金属苦味酸盐的萃取行为

仲胺型双冠醚与四苯硼酸碱金属盐在丙酮溶液中。25℃下的电导说明它们与Na~+可能形成1∶1络合物(冠醚单元∶金属离子),而与K~+、Rb~+、Cs~+离子则形成2∶1络合物。用Schlff碱型和仲胺型双-(苯并15-冠-5)在水-氯仿体系中进行萃取,测量了分配比D和萃取平衡常数K,发现后者的K值均大于前者。双冠醚F_2对K~+的萃取能力最强,选择性最佳。     

一阶导数分光光度法测定血中一氧化碳含量的研究

本文通过理论推导及实验证明CO饱和血与正常血一阶导数的振幅高度比为一常数。将CO中毒检血氨稀释液取一半通CO至饱和,与另一半分别加入Na_2S_2O_4后在500～600nm测定一阶导数光谱在579nm处量出振幅值经计算可得CO在血中含量。     

Synthesis,characterization, and theoretical studies of group 4 amido hydrotris(pyrazolyl)borate complexes

Titanium and zirconium amido complexes containing a hydrotris(pyrazolyl)borate (Tp) or hydrotris(3,5-dimethylpyrazolyl)borate (Tp*) ligand TpM(NMe(2))(3) (M = Ti, 1; M = Zr, 2) and Tp*M(NMe(2))(3) (M = Ti, 3; M = Zr, 4) were prepared by the reactions of M(NMe(2))(3)Cl (M = Ti, Zr) with sodium hydridotris(pyrazol-1-yl)borate and potassium hydridotris(3,5-dimethylpyrazol-1-yl)borate, respectively. The structures of 1, 2, and 4.CH(2)Cl(2) were determined by X-ray diffraction and show octahedral coordination geometry around the metal centers. Density functional theory calculations at the B3PW91 level were performed to understand the orientations and the rotational behavior of amido ligands in these metal complexes.     

分子印迹技术在样品前处理中的应用

分子印迹聚合物具有选择性高、稳定性好及制备简单的特点,可用于生物、医药、环境样品等复杂基体中痕量分析物的高选择性分离与富集,因此在样品前处理中的应用特别引人关注.本文介绍了分子印迹技术的基本原理,综述了分子印迹技术在样品前处理中应用的研究进展.     

Fluorometric investigation of the interaction of bovine serum albumin with surfactants and 6-mercaptopurine

Fluorescence quenching in solutions of bovine serum albumin has been investigated in the presence of 6-mercaptopurine and ionic surfactants. Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of bovine serum albumin by 6-mercaptopurine was dynamic quenching mechanism. The Stern–Volmer quenching model has been successfully applied, and the activation energy of the interaction between 6-mercaptopurine and bovine serum albumin as much as 4.26 kJ mol⁻¹ was calculated. The distance r between donor (bovine serum albumin) and acceptor (6-mercaptopurine) was obtained according to fluorescence resonance energy transfer (FRET). The result of synchronous fluorescence spectra shows that the conformation of bovine serum albumin has been changed at the present of 6-mercaptopurine.     

Speciation of dissolved iron(II) and iron(III) in environmental water samples by gallic acid-modified nanometer-sized alumina micro-column separation and ICP-MS determination

A method has been developed for the speciation of trace dissolved Fe(II) and Fe(III) in water by coupling gallic acid (GA) modified nanometer-sized alumina micro-column separation with inductively coupled plasma mass spectrometry (ICP-MS). The separation of Fe(II) and Fe(III) was achieved based on the obvious difference in reaction kinetics between Fe(II) and Fe(III) with GA. Fe(III) was selectively retained on the micro-column at pH 5.5-6.5, while Fe(II) could not be retained by the micro-column at the whole tested pH range of 1.0-6.5, and passed through the micro-column. The Fe(II) can be determined by ICP-MS directly without preconcentration/separation procedure, while Fe(III) retained on the micro-column was then eluted with 1.0 mL of 1 mol L(-1) HCl and determined by ICP-MS. The parameters affecting the separation of Fe(II) and Fe(III) were investigated systematically and the optimum separation conditions were established. Under the optimized conditions, the detection limits of 0.48 microg L(-1) and 0.24 microg L(-1) with relative standard deviation of 5.6% and 4.3%(C= 5 microg L(-1), n= 7) for Fe(II) and Fe(III) were found, respectively. No obvious effect on the speciation of Fe(II) and Fe(III) was found with the change of the ratio of Fe(II) and Fe(III) from 0 ratio 10 to 10 ratio 0. The proposed method was applied for the determination of trace Fe(II) and Fe(III) in environmental water and the recoveries for spiked samples were found to be in the range of 97-105%.     

Binding of wogonin to human serum albumin: a common binding site of wogonin in subdomain IIA

The binding of wogonin to human serum albumin (HSA) has been studied by spectroscopic method including circular dichroism (CD), infrared spectra (IR) and fluorescence spectra. The fluorescence properties of HSA were examined in presence of wogonin and the fluorescence intensity of HSA was significantly decreased in the presence of wogonin. The binding parameters of wogonin were studied from the fluorescence decreasing of HSA by the fluoremetric titrations. The Stern-Volmer plots indicated that the binding of wogonin to HSA at 296, 303, 310 K is characterized by one binding site with the binding constant K(S-V) at 1.872 x 10(5), 1.561 x 10(5), 1.392 x 10(5), respectively, which are good agreement with the results from the Scatchard plots. The binding process was exothermic, enthalpy driven and spontaneous, as indicated by the thermodynamic analyses, and the major part of the binding energy is hydrophobic interaction, which were consistent with the result of molecule modelling study, and there are also a numbers of hydrogen bonds between wogonin and HSA. Furthermore, the displacement experiments indicate that wogonin can bind to the subdomain IIA, that is, the site I of HSA, which is also good agreement with the result of molecule modelling study.     

Preparation and rheological characterization of poly(n-butyl methacrylate)/montmorillonite composites

Intercalated nanocomposites constituted of poly(butyl methacrylate) (PBMA) as the matrix and an organically modified montmorillonite as the nanosize filler were prepared and rheologically characterized in detail. The rheological behavior of the composites showed dependence on both temperature and clay content. For composites of low clay contents, the steady shear viscosity showed a Newtonian plateau in the low shear rate region at low temperatures and the plateau was replaced by a shear-thinning curve when the temperature was raised. For composites of higher clay contents, strong shear-thinning behavior were observed at all shear rates and all temperatures. The viscoelastic data of the composites showed unusual terminal behavior of a decreasing terminal slope at low frequencies with increasing temperature and clay loading. X-ray diffraction spectra showed that annealing process at higher temperatures shifted the Bragg reflection peaks to a lower angle and broadened the peaks, which provided the evidence for the existence of a temperature-induced solid-like structure that was responsible for the shear thinning and the unusual terminal viscoelastic behavior.     

涂敷法制作质谱场电离发射丝的方法及性能研究

本文介绍一种新的质谱场电离发射丝的制备方法——涂敷法,并研究了其制备机理及影响发射丝灵敏度的因素。此外,还对涂敷法制作的发射丝及高温活化法制作的发射丝进行了各项性能对比试验。最后,介绍了涂敷发射丝的应用效果。     

RExOy.nH2O对氟离子的吸附性能

La、Ce等稀土水含氧化物对阴离子的吸附性早有研究「‘－‘1，但从混合轻稀土氯化物制得的水合氧化物吸附F一的研究报道较少．为探讨难溶金属水合氧化物的除氟性能，本文以混合轻稀土氯化物为原料，制得其水含氧化物（RExOy·nH。O），采用高聚物造粒，研究了粒状RExOy·nH。O对F一的吸附性能及吸附机理．所用混合轻稀土氯化物由包头钢铁稀土公司提供，其主要组成（以氧化物计）为：CeO。（50％）、Nd。O3（25％）、La。O。（15％）、P36Oll（8％）．聚丙烯睛分子量为（2．5～5）X10‘．其它试剂为分析纯．RExO．·nH。O参照文…