Conformation dependence of electronic structures of poly(ethylene oxide)

The electronic structure of pure poly(ethylene oxide) (PEO) for four different polymeric chain conformations has been studied by Hartree-Fock (HF) and density functional theory (DFT) through the analysis of their valence band photoelectron spectroscopy (VB-PES), X-ray emission spectroscopy (XES), and resonant inelastic X-ray scattering (RIXS). It is shown that the valence band of PEO presents specific conformation dependence, which can be used as a fingerprint of the polymeric structures. The calculated spectra have been compared with experimental results for PEO powder.     

Probing the local structure and mechanical response of nanostructures using force modulation and nanofabrication

Nanostructures of self-assembled monolayers (SAMs) are designed and produced using coadsorption and nanografting techniques. Because the structures of these artificially engineered domains are predesigned and well-characterized, a systematic investigation is possible to study the mechanical responses to force modulation under atomic force microscope tips. Force modulation imaging reveals characteristic contrast sensitivity to changes in molecular-level packing, molecule chain lengths, domain boundaries, and surface chemical functionalities in SAMs. By means of actively tuning the driving frequency, the resonances at the tip-surface contact are selectively activated. Therefore, specific surface features, such as the edges of the domains and nanostructures or desired chemical functionalities, can be selectively enhanced in the amplitude images. These observations provide a new and active approach in materials characterization and the study of nanotribology using atomic force microscopy.     

Raman spectroscopic analysis of supersaturated aqueous solution of MgO.B2O3-32%MgCl2-H2O during acidification and dilution

Raman spectra of supersaturated aqueous solution of MgO.B2O3-32%MgCl2-H2O during acidification/alkalization and dilution have been studied. The assignments of the recorded Raman shift are given. The main existing forms of polyborate anions and their interaction in borate aqueous solution have been proposed through spectroscopic analysis. The experimental results indicate that the higher concentration of cation are beneficial not only to the dissolution of boric acid but also to the polymerization of polyborate anions. The existing forms and interaction among them also depend on the concentration of boron and the pH value in solution.     

赖氨酸修饰壳聚糖磁性超微载体的制备和表征

本文设计并合成了良好水溶性的赖氨酸修饰壳聚糖,并对制备工艺进行了优化.产物通过红外(FTIR)和核磁(1H-NMR)进行了表征,并将其作为壳层材料制备了赖氨酸修饰壳聚糖磁性超微载体.通过光电能谱(XPS)、透射(TEM)、激光粒度仪、X射线衍射(XRD)、磁性能测试(VSM)对载体进行了表征.结果表明,制备的赖氨酸修饰壳聚糖磁性超微载体表面带有大量的氨基(-NH2),粒径分布较为均一(100nm左右),形貌较为规则,并具有良好的超顺磁性,因而该载体具有更加良好的性能.     

HPLC–MS Analysis of Isoniazid in Dog Plasma

A simple, rapid, and sensitive liquid chromatography–mass spectrometric (LC–MS) method was developed and validated for the determination of isoniazid in dog plasma. Plasma samples were deproteined with methanol and separated on a C₁₈ column interfaced with a single quadrupole mass spectrometer, using 0.1% formic acid–acetonitrile (91:9 v/v) as mobile phase. Detection was performed by positive electrospray ionization with selected ion monitoring at m/z 138 for isoniazid and 152 for entecavir maleate internal standard. Linearity was obtained over the range of 25–5,000 ng mL^?1, with a lower limit of quantification of 25 ng mL^?1. The intra- and inter-day precision was less than 2.7% in terms of relative standard deviation. Accuracy, expressed as relative error, ranged from ?2.0 to 8.0%. Plasma samples were analysed within 5 min. The method was successfully applied to the evaluation of the pharmacokinetics of isoniazid in dog plasma.     

同时测定食用植物油中抗氧剂叔丁基对羟基茴香醚和2，6－二叔丁基对甲酚的方法

报道了用高效液用色谱法同时测定食用植物油中的抗氧剂叔丁基对羟基茴香醚（ＢＨＡ）和２，６－二叔丁基对甲酚（ＢＨＴ）的实验方法。采用ＺｏｒｂａｘＯＤＳＣ_（１８）色谱住，甲醇：水（９０：１０，Ｖ／Ｖ）作流动相，检测波长为２４５ｎｍ，流速为１ｍＬ／ｍｉｎ。检测下限分别为１５ｎｇ（ＢＨＡ），９０ｎｇ（ＢＨＴ），回收率分别是９６．８％±９．８％（ＢＨＡ），９９．０％±３．２％（ＢＨＴ）。方法快速、准确，灵敏度高。     

Extraction of Americium(III) and Europium(III) with Two Open-Chain Crown Ethers of Amide Type

The extraction of Am³⁺ and Eu³⁺ from aqueous picric acid solution by N, N-dinaphthyl-N, N-diphenyl-3,6-dioxaoctanediamide (L^I) and 1, 1-(3, 6, 9-trioxaundecanedionyl)diphenothiazine (L^II) was investigated by a radioactive tracer technique. Extraction distribution ratios of Am³⁺ and Eu³⁺ have been measured as a function of pH, picric acid concentration, extractant concentration, diluent and temperature. The extraction of Am³⁺ is preferred to that of Eu³⁺ for both L^I and L^II, and the latter gives larger separation factor than the former. The equilibrium constants and thermodynamic parameters of extraction reactions were also calculated.     

磺化酞菁铜分子膜／SiO2／Si界面电荷转移机制的研究

在具有不同氧化层厚度的p型硅基片上修饰2层磺化酞菁铜分子膜.利用时间分辨表面光电压谱技术,对该膜系的界面电荷转移机制的光电开关特性进行了研究。结果表明,用时间分辨表面光电压谱技术研究界面电荷转移过程具有明显优越性.     

耐高温α-淀粉酶结合Ca2+的研究

测定了耐高温α-淀粉酶分子中含10个Ca2+,脱钙酶逐量补钙后的活力及稳定性研究表明:酶分子中前8个Ca2+参与酶的催化作用,后2个Ca2+抖对酶结构起稳定作用.脱钙酶加钙后室温下的荧光光谱和CD谱表明:酶的构象虽有变化,但不显著,说明酶的构象对ca2+的依赖性很小.脱钙酶结合不同数目的Ca2+,于90℃加热15 min后,测其荧光光谱,结果表明,结合10个Ca2+时,酶保持最大的稳定构象;CD谱表明脱钙酶加热时仍具有一定的螺旋结构.这再次说明,酶的构象对ca2+依赖性较低.     

酞菁锰-表面活性剂薄膜电极的电化学表征及其对三氯乙酸的电化学催化作用的研究

将酞菁锰（ＭｎＰｃ）掺入阳离子表面活性剂双十二烷基二甲基溴化铵（ＤＤＡＢ）的氯仿溶液，并涂布于热解石墨电极表面，待氯仿挥发后即制得ＭｎＰｃ－ＤＤＡＢ薄膜电极。循环伏安实验表明，在ＫＢｒ溶液中，该薄膜电极有两对还原氧化峰，第一对峰的Ｅｐｃ１＝－０．２７Ｖ，Ｅｐａ１＝０．０１Ｖ；第二对峰的Ｅｐｃ２＝－０．７６Ｖ，Ｅｐａ２＝－０．６２Ｖ（ｖｓ．ＳＣＥ）。本文着重探讨了第二对峰的电化学行为，估计了该体系的电荷传递扩散系数Ｄｃｔ和表观非均相电极反应速率常数Ｋ０′等电化学参数，并可将该薄膜电极用于催化三氯乙酸的电化学还原。