硫酸镓催化法合成环己酮乙二醇缩酮

以环己酮和乙二醇为原料,硫酸镓为催化剂,在微波辐射和无溶剂条件下,合成了环己酮乙二醇缩酮．探讨了酮醇物质的量比、催化剂用量、微波功率和辐射时间对产品收率的影响．结果表明,环己酮乙二醇缩酮的最佳合成条件为：n（环己酮）：n（乙二醇）=1：3,催化剂用量为反应物总质量的2．0％,微波功率为375W,辐射时间为20min．在此条件下,缩酮收率可达96．3％,说明硫酸镓是一种合成环己酮乙二醇缩酮的优良催化剂．     

氯化铯催化羧酸钠(钾)与α-氯代乙酸酯及溴(氯)代烃反应

以DMF为溶剂,在催化量氯化铯存在下,羧酸钠(钾)与α-氯代乙酸酯在室温下反应及其与溴(氯)代烃在60℃反应,分别形成对应的羧酸(α-烷氧甲酰)甲酯与羧酸酯,产率90%以上,讨论了催化机理.     

Prediction of melatonin excretion patterns in the rat exposed to ELF magnetic fields based on support vector machine and linear discriminant analysis

Bioeffects of magnetic field exposure have been motivated accomplishing various studies. However, no consensus or guideline is available for experimental designs relating exposure conditions as yet. In the present work, in order to analyze and predict the melatonin excretion patterns in the rat exposed to extremely low frequency magnetic fields (ELF-MF), linear discriminate analysis (LDA) and support vector machines (SVMs) were utilized. Subsequently, performances of LDA and SVMs were compared through resubstitution and jackknife tests on a database containing 33 experiments. Predictor variables were more effective parameters including frequency, polarization, exposure duration and strength of magnetic fields. Also, five performance measures including accuracy, sensitivity, specificity, matthew's correlation coefficient (MCC) and normalized percentage better than random (S) were used to evaluate the performance of models. The LDA as a conventional model obtained poor prediction performance. On the other hand, SVMs as a more powerful model, which has not been introduced in predicting melatonin excretion patterns in the rat exposed to ELF-MF, showed 0.38 value of MCC through jackknife test that confirms the higher reliability of the SVMs.     

Thermochemical study of [Sm(C7H5O3)2·(C4H6NO2S)]·2H2O

The product from reaction of samarium chloride hexahydrate with salicylic acid and Thioproline, [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O, was synthesized and characterized by IR, elemental analysis, molar conductance, and thermogravimetric analysis. The standard molar enthalpies of solution of [SmCl₃·6H₂O(s)], [2C₇H₆O₃(s)], [C₄H₇NO₂S(s)] and [Sm(C₇H₅O₃)₂·(C₄H₇NO₂S)·H₂O(s)] in a mixed solvent of absolute ethyl alcohol, dimethyl sulfoxide(DMSO) and 3 mol L^?1 HCl were determined by calorimetry to be Δ_s H _m ^Φ [SmCl₃ δ6H₂O (s), 298.15 K]= ?46.68±0.15 kJ mol^?1 Δ_s H _m ^Φ [2C₇H₆O₃ (s), 298.15 K]= 25.19±0.02 kJ mol^?1, Δ_s H _m ^Φ [C₄H₇NO₂S (s), 298.15 K]=16.20±0.17 kJ mol^?1 and Δ_s H _m ^Φ [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O (s), 298.15 K]= ?81.24±0.67 kJ mol^?1. The enthalpy change of the reaction (1) $$ SmCl_3 \cdot 6H_2 O(s) + 2C_7 H_6 O_3 (s) + C_4 H_7 NO_2 S(s) = Sm(C_7 H_5 O_3 )_2 \cdot (C_4 H_6 NO_2 S) \cdot 2H_2 O(s) + 3HCl(g) + 4H_2 O(1) $$ was determined to be Δ_s H _m ^Φ =123.45±0.71 kJ mol^?1. From date in the literature, through Hess’ law, the standard molar enthalpy of formation of Sm(C₇H₅O₃)₂(C₄H₆NO₂S)δ2H₂O(s) was estimated to be Δ_s H _m ^Φ [Sm(C₇H₅O₃)₂·(C₄H₆NO₂S)]·2H₂O(s), 298.15 K]= ?2912.03±3.10 kJ mol^?1.     

A label-free electrochemical immunoassay for IgG detection based on the electron transfer

In this study, a highly selective, label-free electrochemical immunoassay strategy based on the charge transport through the multilayer films associated with the electrocatalytic reduction of [Fe(CN)₆]³⁻ is proposed using human immunoglobulin G (human IgG) as the model analyte. The antibody-antigen complex formed on the sensing interface can efficiently induce change of the surface charge characteristics, the conductivity of multilayer film and/or electron transfer distance, resulting in an immunoreaction signal. The current reduction is proportional to the amount of analyte. Under the optimized experimental conditions, the proposed sensing strategy provides a linear dynamic range from 10 to 10⁴ ng mL⁻¹ and a detection limit of 3 ng mL⁻¹, indicating an improved analytical performance. This possibly makes it a potential alternative in bioanalysis of proteins and other molecules.     

铈和硫代脯氨酸、水杨酸三元配合物的热化学性质

用七水合氯化铈与硫代脯氨酸(C4H7NO2S)和水杨酸(C7H6O3)合成了三元固体配合物[Ce(C7H5O3)2(C4H6NO2S)]·2H2O。根据盖斯定律设计一个热化学循环,用恒温环境的溶解―反应量热法研究得到合成反应的标准反应焓为263.12±0.95 kJ/mol,进而算出配合物298.15 K时的标准摩尔生成焓为-2785.7±3.2 kJ/mol。     

Global attractivity for nonlinear fractional differential equations

We present some results for the global attractivity of solutions for fractional differential equations involving Riemann-Liouville fractional calculus. The results are obtained by employing Krasnoselskii’s fixed point theorem. Similar results for fractional differential equations involving Caputo fractional derivative are also obtained by using the classical Schauder’s fixed point theorem. Several examples are given to illustrate our main results.     

Positive solutions for multipoint boundary value problem of fractional differential equations

In this paper, we study the existence of positive solutions for a multi-point boundary value problem of nonlinear fractional differential equations. By applying a monotone iterative method, some existence results of positive solutions are obtained. In addition, an example is included to demonstrate the main result.     

一维p-拉普拉斯四点边值问题拟对称正解的多重性

应用凸锥上的一个不动点定理,讨论了一类一维p-拉普拉斯四点边值问题在非线性项f依赖于未知函数的一阶导数的情况下拟对称正解的多重性,得到了这类边值问题存在多个拟对称正解的充分条件.     

The dielectric and dynamical properties of zinc-blende BN, AlN and GaN from first-principle calculation

The ab initio calculations of the electronic structural, dielectric and lattice-dynamical properties of zinc-blende BN, AlN and GaN were presented. The ground-state properties, i.e., the lattice constant, the bulk modulus and band gap, were calculated using a plane-wave-pseudopotential method within the density-function theory. A linear-response approach to the density-function perturb theory was used to derive the Born effective charge, the high-frequency dielectric constants and interatomic force constants for these materials. The interatomic force contants (IFCs) are useful for interpolating the dynamical matrices through the whole Brillouin zone. Phonon frequencies along high-symmetry lines were also obtained by interpolating the dynamical matrices using the interatomic force constants. In this paper, we discussed the difference of dielectric and dynamical properties among zinc-blende BN, AlN and GaN, and meanwhile, also compared these properties with other experimental data available and theoretical values. Generally, the calculations were in good agreement with the other existing experimental data and theoretical values. Supported by the Hunan Provincial Natural Science Foundation of China (Grant No. 05JJ40135) and Xiangnan University Important Science Foundation (Grant No. 2007Z010)