Prediction of quantitative calibration factors of some organic compounds in gas chromatography

A quantitative structure-property relationship (QSPR) methodology that involves multilinear (Hansch-type) and nonlinear (radial basis function neural network (RBFNN)) approaches was performed to correlate the quantitative molar calibration factors (f(M)) of 140 organic compounds against structural factors. The statistical characteristics provided by the multiple linear model (R(2) = 0.963; RMS = 0.089; AARD = 3.86% for test set) indicated satisfactory stability and predictive ability, while the predictive ability of the RBFNN model is somewhat superior (R(2) = 0.983; RMS = 0.075; AARD = 3.19% for test set). The multilinear model provided some insight into the main structure factors that modulate the quantitative calibration factor of the investigated compounds.     

Electron transfer activation of chromopyrrolic acid by cytochrome p450 en route to the formation of an antitumor indolocarbazole derivative: theory supports experiment

QM/MM calculations support experiment and show that StaP is a P450 that functions like a peroxidase: its active species is the one-electron-reduced Cpd II species with a radical on CPA, by analogy to cytochrome c peroxidase (CcP), and its reaction with the substrate proceeds by overall proton-coupled electron transfer (PCET), in analogy to the corresponding mechanism in horseradish peroxidase (HRP). The electron transfer is enabled by His250, the presence of carboxylate groups in CPA, and by the H-bonding network that tunes the energetic of the process. Theory supports experiment but reveals some novel aspects of this unusual P450.     

铁氰化钾高灵敏共振瑞利散射法测定青霉素类抗生素

在稀HCl介质中,K3[Fe(CN)6]与阿莫西林(AMO)、氨苄西林(AMP)、氯唑西林钠(CLO)、羧苄西林钠(CAR)和青霉素钠(BEN)等抗生素药物在加热条件下反应生成结合产物,会导致溶液的共振瑞利散射(RRS)强度急剧增强,并产生新的RRS光谱,5种反应产物的最大散射峰均位于330 nm附近。在一定的浓度范围内,不同的反应体系散射强度(∆I)与药物浓度成正比,反应具有很高的灵敏度,K3[Fe(CN)6]对5种药物的检出限分别在4.61至5.62 ng·mL-1之间。本文研究了RRS的光谱特征和适当的反应条件,并讨论了反应机理和散射增强的原因,还考察了共存物质的影响,表明方法具有较好的选择性,可用于胶囊、片剂和人血清及尿液中青霉素类药物的测定。     

一种基于纳米二氧化硅增强凝集反应的压电免疫传感器

本文提出了一种基于抗体包被纳米粒子的简单快速的压电免疫凝集法,用于蛋白质检测。该方法原理是利用羊抗人IgG（G-anti-hIgG）包被的二氧化硅（或金）纳米粒子和人IgG（hIgG）发生免疫凝集反应而使得压电晶体频率发生改变进行测定。当凝集反应发生时,修饰在探针表面的G-anti-hIgG通过hIgG与G-anti-hIgG包被的纳米粒子结合,将质量效应和粘弹性因素叠加作用于压电晶体。结果表明这使得背景值大幅减小而信号明显增强。另外,对修饰后了抗体及结合免疫复合物的探针表面进行了SEM表征,对使用聚乙二醇作为增敏剂和实验最佳离子强度、pH值进行了优化选择。该传感器检测hIgG线性范围是0.26-16.7 mg mL-1,最低检出限为84 ng mL-1。     

HILIC for separation of co-eluted flavonoids under RP-HPLC mode

Hydrophilic interaction chromatography (HILIC) was employed to separate the co-eluted flavonoids from licorice extract under RP-HPLC mode. HILIC separations were carried out with the Atalantis HILIC Silica column and the CD-based column. The co-eluted flavonoids were well retained and separated on the two HILIC columns under HILIC mode. Similar results were obtained in the separation of another isoflavones sample, from kudzu extract under HILIC mode.     

Enhancements of rate capability and cyclic performance of spinel LiNi0.5Mn1.5O4 by trace Ru-doping

The rate capability and cyclic performance of the LiNi_0.5Mn_1.5O₄ under high current density have been significantly improved by doping a small amount of ruthenium (Ru). Specifically, Li_1.1Ni_0.35Ru_0.05Mn_1.5O₄ and LiNi_0.4Ru_0.05Mn_1.5O₄ synthesized by solid state reaction can respectively deliver a discharge capacity of 108 and 117 mAh g^?1 at 10 C rate between 3 and 5 V. At 10 C charge/discharge rate, Li_1.1Ni_0.35Ru_0.05Mn_1.5O₄ and LiNi_0.4Ru_0.05Mn_1.5O₄ can respectively maintain 91% and 84% of their initial capacity after 500 cycles, demonstrating that Ru-doping could be a way to enhance the electrochemical performance of spinel LiNi_0.5Mn_1.5O₄.     

Dual activation in asymmetric allylsilane addition to chiral N-acylhydrazones: method development, mechanistic studies, and elaboration of homoallylic amine adducts

[reaction: see text] Chiral N-acylhydrazones derived from commercially available 4-benzyl-2-oxazolidinone provide a rigid, conformationally restricted template to impart facial selectivity in additions to C=N bonds. In the presence of indium(III) trifluoromethanesulfonate [In(OTf)3], N-acylhydrazones undergo highly diastereoselective fluoride-initiated additions of allylsilanes (aza-Sakurai reaction). Mechanistic studies including control experiments and comparisons with allyltributylstannane, allylmagnesium bromide, and allylindium species implicate a dual activation mechanism involving addition of an allylfluorosilicate species to a chelate formed from In(OTf)3 and the chiral N-acylhydrazone. The N-N bonds of the adducts are readily cleaved in a two-step protocol to provide synthetically useful homoallylic N-trifluoroacetamides. Further elaboration of the latter compounds through Wacker oxidation and olefin metathesis provides diversely functionalized building blocks and expands the potential applications of this C-C bond construction approach to asymmetric amine synthesis.     

Synthesis of graft copolymer of ethyl cellulose through living polymerization and its self-assembly

Copolymers of ethyl cellulose (EC) with polystyrene (PSt) were synthesized through atom transfer radical polymerization (ATRP). The molecular weight of graft copolymers increased without any trace of the EC macro-initiator, and the polydispersity of the side chains was low. The molecular weight of the side chains increased with the monomer conversion. Kinetic study indicated that the polymerization was first order. The micelle characteristics of the graft copolymer in acetone were investigated using dynamic light scattering (DLS), atom force microscopy (AFM) and transmission electron microscopy (TEM). With increasing the concentration, micelles were gradually formed from the solution. The TEM and AFM images indicated that the micelles had spherical shape and showed core-shell structure.     

1-[4-(二甲氨基)苯亚甲基氨基]-4-苯基硫脲的合成及手性晶体结构

对二甲氨基苯甲醛和苯基氨基硫脲缩合反应生成对二甲氨基苯甲醛缩氨基苯硫脲{1-[4-(dimethylamino)ben- zylidene]-4-phenylthiosemicarbazide}, 并从溶液中析出手性晶体. 元素分析、红外光谱、紫外光谱、核磁谱、质谱和X射线衍射测定其组成和结构. 晶体属正交晶系, P2₁2₁2₁空间群, a＝0.77038(14) nm, b＝1.1428(2) nm, c＝1.6726(3) nm, V＝1.4726(5) nm³, Z＝4, D_c＝1.346 g/cm³, F(000)＝632, μ＝0.219 mm^－1, 可观测点精修最终偏离因子: R＝0.0407, wR＝0.1157. 化合物的晶体结构和固态圆二色谱表明化合物在结晶过程中发生单一对映体的手性堆积.     

石英芯片电泳分离检测尿中蛋白的研究

通过对缓冲体系、缓冲液浓度、酸度、乳酸钙浓度、乙胺浓度、电泳电压和进样时间的优化选择，用石英芯片电泳一紫外检测法分离了纯人白蛋白和人运铁蛋白；在75mmol／L硼酸盐（pH10．55）（含0．8mmol／L乳酸钙、1％（φ）乙胺）运行缓冲液中，上述两组分在3min内完全分离；纯人白蛋白和人运铁蛋白的线性范围分别为1．0～15．0g/L和1．0～10．0g／L；检出限（S／N=3）均为0．5g／L，应用于临床尿蛋白分离测定，并与Helena琼脂糖凝胶电泳仪电泳结果进行比较，获得一致结果。