A convenient synthesis of 2-aminocyclohex-1-ene-1-carboxylic esters by FeCl3/SiO2 nanoparticles as robust and efficient catalyst

A simple and green method has been developed for the synthesis of 2-aminocyclohex-1-ene-1-carboxylic esters through a one-pot three-component condensation reaction of primary amines, ethyl acetoacetate and chalcones using FeCl3/SiO2 nanoparticles in ethanol. This method has several advantages such as high to excellent product yields in short time, using an inexpensive and reusable catalyst and available starting material.     

基于等效单元概念的梁结构损伤定位方法

研究目的是为梁结构提供一种基于等效单元概念的新损伤定位方法. 区分刚度损伤和质量损伤两种情况, 分别对连续梁和简支梁给出了具体的损伤定位方法. 利 用的具体指标是支座反力和跨中位移. 文中的新方法都可以得到以小区间表示的损伤位置结 果, 有效性得到了数值模拟算例和模型实验的验证.     

Adsorption of sarin and chlorosarin onto the Al12N12 and Al12P12 nanoclusters: DFT and TDDFT calculations

This study provides details of the electronic and optical structures and binding energies of sarin (SF) and chlorosarin (SC) with Al–N and Al–P surfaces of Al₁₂N₁₂ and Al₁₂P₁₂ nanoclusters in the gas phase. The adsorption mechanism of SF and SC on these nanoclusters containing the Al³⁺ central cation was studied. Optimized geometries and thermodynamic parameters of SF and SC adsorption complexes were calculated. SF and SC are chemisorbed on these nanoclusters because of the formation of PO···Al bonds. The chemical bond is formed between an oxygen atom of SF and SC and an aluminum atom of fullerene-likes (chemisorption). However, the binding energies of the complexes with the Al₁₂N₁₂ nanocluster are larger than these values for the Al₁₂P₁₂ nanocluster. The interaction enthalpy and Gibbs free energy of all studied systems were found to be negative. We can conclude that SF and SC will be adsorbed preferably on Al₁₂N₁₂ nanocluster.     

Synthesis of Long‐Circulating,Backbone Degradable HPMA Copolymer–Doxorubicin Conjugates and Evaluation of Molecular‐Weight‐Dependent Antitumor Efficacy

Backbone degradable, linear, multiblock N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymer–doxorubicin (DOX) conjugates are synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization followed by chain extension via thiol‐ene click reaction. The examination of molecular‐weight‐dependent antitumor activity toward human ovarian A2780/AD carcinoma in nude mice reveals enhanced activity of multiblock, second‐generation, higher molecular weight conjugates when compared with traditional HPMA copolymer–DOX conjugates. The examination of body weight changes during treatment indicates the absence of non‐specific adverse effects.

     

High-performance numerical algorithms and software for subspace-based linear multivariable system identification

Basic algorithmic and numerical issues involved in subspace-based linear multivariable discrete-time system identification are described. A new identification toolbox—SLIDENT—has been developed and incorporated in the freely available Subroutine Library in Control Theory (SLICOT). Reliability, efficiency, and ability to solve industrial identification problems received a special consideration. Two algorithmic subspace-based approaches (MOESP and N4SID) and their combination, and both standard and fast techniques for data compression are provided. Structure exploiting algorithms and dedicated linear algebra tools enhance the computational efficiency and reliability. Extensive comparisons with the available computational tools based on subspace techniques show the better efficiency of the SLIDENT toolbox, at comparable numerical accuracy, and its capabilities to solve identification problems with many thousands of samples and hundreds of parameters.     

Mathematical modeling of flow and kinetics in a reactor for dilute-acid hydrolysis of cellulose particles

Amathematical model to simulate the dilute-acid hydrolysis process of cellulose particles is presented. In this model, the mass is treated as a mixture of different components. A test case is considered for which transport equations for components are developed and solved together with the momentum equation for the fluid flow. To solve the model equations, a commercially available flow solver was used. All input data were taken from previously published works. For the small static mixer considered as test geometry, the result, in terms of the conversion of the cellulose particles, was reasonable. With input parameters that are relevant to a plant-size reactor, the model can be used to predict the conversion of both cellulose and hemicellulose particles.     

Thin‐layer chromatography—an image‐processing method for the determination of acidic catecholamine metabolites

A sensitive and convenient method for acidic catecholamine metabolites (including homovanillic acid, vanillylmandelic acid, 3,4‐dihydroxymandelic acid, and 3,4‐dihydroxyphenylacetic acid) determination was developed based on thin‐layer chromatography and image‐processing analysis. The metabolites were separated without a prederivatization step using reversed phase RP‐18W high‐performance plates. The mobile phase composition, detection, and quantification conditions were systematically investigated through several trials. The reaction with 2,2‐diphenyl‐1‐picrylhydrazyl radical allowed specific detection of acidic catecholamine metabolites with a high sensitivity and a wide linear range. The limit of detection and the limit of quantification were in the range of 13–103 and 18–120 ng/spot, respectively, in all cases. Mean recoveries determined were in the range 95–106% for all of the investigated compounds. The proposed method allowed rapid simultaneous determination of acidic catecholamine metabolites from spiked human urine sample.     

Copper‐Catalyzed Synthesis of Alkynyl Hydrazones from Alkynes and Hydrazonyl Chlorides

A novel ligand‐free synthesis of alkynyl hydrazones via coupling reaction of hydrazonyl chlorides and terminal alkynes, catalyzed by CuI led to excellent yields.     

基于改进的径向基函数神经网络的铁磁谐振系统混沌控制

面向中性点直接接地电力系统发生的铁磁谐振过电压所显现的混沌特性，在径向基函数神经网络的基础上，提出引进一种极大熵学习算法对该混沌系统进行控制.该方法通过最优化一个目标函数导出中心向量的学习规则，充分利用网络隐层的聚类功能，极大改善网络的回归和学习能力.对具体的铁磁谐振系统的数值实验证实了该方法在针对铁磁谐振过电压混沌控制中的有效性和可行性. 关键词： 中性点直接接地系统 混沌控制 径向基函数 极大熵原理     

Verteilung und Valenz der Kationen in Spinellsystemen mit Eisen und Chrom. III. Gitterkonstanten,Mößbauer-Spektren und Thermokraft der Mischkristalle ZnFeCrO4?Fe2CrO4

Distribution and Valence of the Cations in Spinel Systems with Iron and Chromium. III. Lattice Constants, Mössbauer Spectra, and Seebeck Coefficients of the Solid Solution ZnFeCrO₄? Fe₂CrO₄ For the spinel system Zn_1–x²⁺Fe_x–λ²⁺Fe_λ³⁺(Fe_λ²⁺ · Fe_1?λ³⁺ Cr³⁺)O₄ λ has been determined by lattice constants and ionic distances: λ = 0 in the region 0 ? x ? 0.3; in the region 0.3 < x ? 1 λ increases linearly to 0.44. Mössbauer spectra between x = 0 and x = 0.6 confirm this distribution. All spinels are n-type hopping conductors mainly conducting on the octahedral sites.