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301.
Jinshou Wang Nong Wang Hekun Lv Weiguo Shen 《The Journal of chemical thermodynamics》2008,40(12):1638-1644
The coexistence curves and light scattering data for a critical solution of (benzonitrile + octane) have been reported. The critical exponents relating to the difference in the density variables between two coexisting phases β, the osmotic compressibility γ, and the correlation length ν have been deduced and the values are consistent with the 3D-Ising value in the range close to the critical point. The experimental results of the coexistence curves have also been analyzed to examine the Wegner correction terms and the behavior of the diameter of the coexistence curves. The light scattering data are well described by the crossover model proposed by Anisimov and Sengers, and show a monotonic crossover of the critical exponents γ and ν from its 3D-Ising value to the mean-field value as the temperature departures from the critical point. Furthermore, the dependences of the critical amplitudes on the mass of n-alkane for the binary solutions of (benzonitrile + n-alkane) have been discussed. 相似文献
302.
We consider the problem of scheduling family jobs with release dates on a bounded batching machine to minimize the makespan. A polynomial-time approximation scheme for the identical job size model and an approximation algorithm with a worst-case ratio of for the non-identical job size model will be derived. 相似文献
303.
The analysis of phenols in environmental samples is of great importance because of theirwidespread occurrence in the environment. Especially it is hard to separate p-cresol andm--cresoll'2. In this paper, eight kinds of fi -cyclodextrin derivatives were studied forthe separation of phenol and cresol isomers. The result showed that the capillarycolumn coated with heptakis(2,6-di-O-pentyl-3-O-all -cyclodextrin was excellentfor separating these compounds. The method is simple, quick, accurate an… 相似文献
304.
为提高新建变电工程固定型阀控式铅酸蓄电池运行稳定性及寿命,本文采用大电流加速循环试验、拆解试验和阻燃试验分析蓄电池性能,结果表明:在50 ℃温度下,经过18次大电流充放电循环(耗时10 d),蓄电池容量由初始的701.93 A·h降为563.12 A·h,其容量持有率为80.22%,电池内部结构仍保持初步完整,且槽、盖阻燃能力强,说明高温大电流循环充放电试验能快速破坏内部细致构造以致使得容量下降。 该研究结果可作为一种新的快速评价分析铅酸蓄电池性能及寿命的试验测试方法。 相似文献
305.
Oxide‐Supported IrNiOx Core–Shell Particles as Efficient,Cost‐Effective,and Stable Catalysts for Electrochemical Water Splitting 下载免费PDF全文
Hong Nhan Nong Dr. Hyung‐Suk Oh Tobias Reier Dr. Elena Willinger Dr. Marc‐Georg Willinger Prof. Dr. Valeri Petkov Dr. Detre Teschner Prof. Dr. Peter Strasser 《Angewandte Chemie (International ed. in English)》2015,54(10):2975-2979
Active and highly stable oxide‐supported IrNiOx core–shell catalysts for electrochemical water splitting are presented. IrNix@IrOx nanoparticles supported on high‐surface‐area mesoporous antimony‐doped tin oxide (IrNiOx /Meso‐ATO) were synthesized from bimetallic IrNix precursor alloys (PA‐IrNix /Meso‐ATO) using electrochemical Ni leaching and concomitant Ir oxidation. Special emphasis was placed on Ni/NiO surface segregation under thermal treatment of the PA‐IrNix /Meso‐ATO as well as on the surface chemical state of the particle/oxide support interface. Combining a wide array of characterization methods, we uncovered the detrimental effect of segregated NiO phases on the water splitting activity of core–shell particles. The core–shell IrNiOx /Meso‐ATO catalyst displayed high water‐splitting activity and unprecedented stability in acidic electrolyte providing substantial progress in the development of PEM electrolyzer anode catalysts with drastically reduced Ir loading and significantly enhanced durability. 相似文献
306.
A Reusable Unsupported Rhenium Nanocrystalline Catalyst for Acceptorless Dehydrogenation of Alcohols through γ‐C–H Activation 下载免费PDF全文
Jing Yi Prof. Dr. Jeffrey T. Miller Dr. Dmitry Y. Zemlyanov Ruihong Zhang Dr. Paul J. Dietrich Prof. Dr. Fabio H. Ribeiro Dr. Sergey Suslov Prof. Dr. Mahdi M. Abu‐Omar 《Angewandte Chemie (International ed. in English)》2014,53(3):833-836
Rhenium nanocrystalline particles (Re NPs), of 2 nm size, were prepared from NH4ReO4 under mild conditions in neat alcohol. The unsupported Re NPs convert secondary and benzylic alcohols to ketones and aldehydes, respectively, through catalytic acceptorless dehydrogenation (AD). The oxidant‐ and acceptor‐free neat dehydrogenation of alcohols to obtain dihydrogen gas is a green and atom‐economical process for making carbonyl compounds. Secondary aliphatic alcohols give quantitative conversion and yield. Transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), Re K‐edge X‐ray absorption near‐edge structure (XANES), and X‐ray absorption fine structure (EXAFS) data confirmed the characterization of the Re NPs as metallic rhenium with surface oxidation to rhenium(IV) oxide (ReO2). Isotope labeling experiments revealed a novel γ‐CH activation mechanism for AD of alcohols. 相似文献
307.
Ya‐Li Pan Fang Chen Meng‐Yu Zhang Tian‐Qi Wang Zi‐Chun Xu Wei Zhang Qing‐Cui Chu Jian‐Nong Ye 《Electrophoresis》2013,34(8):1241-1248
A hollow fiber‐based liquid‐phase microextraction method has been developed for enrichment of trace chloroanilines in water samples. Target analytes including aniline, three mono‐chlorinated aniline isomers (o‐chloroaniline, m‐chloroaniline, and p‐chloroaniline) and four mono‐chlorinated methylaniline isomers (2‐chloro‐4‐methylaniline, 3‐chloro‐4‐methylaniline, 4‐chloro‐2‐methylaniline, and 5‐chloro‐2‐methylaniline) were determined by CE with amperometric detection after microextraction. Several factors that affect separation, detection, and extraction efficiency were investigated. Under the optimum conditions, eight aniline compounds could be well separated from other components coexisting in water samples within 25 min, exhibiting a linear calibration over three orders of magnitude (r > 0.998); the obtained enrichment factors were between 51 and 239, and the LODs were in the range of 0.01–0.1 ng/mL. The proposed method has been applied for the analyses of real environmental water and sewage samples with relative recoveries in the range of 83–108%. 相似文献
308.
Induction of Strong Long‐Lived Room‐Temperature Phosphorescence of N‐Phenyl‐2‐naphthylamine Molecules by Confinement in a Crystalline Dibromobiphenyl Matrix 下载免费PDF全文
Jinbei Wei Baoyan Liang Ruihong Duan Zong Cheng Chenglong Li Dr. Tianlei Zhou Prof. Dr. Yuanping Yi Prof. Dr. Yue Wang 《Angewandte Chemie (International ed. in English)》2016,55(50):15589-15593
The design and preparation of metal‐free organic materials that exhibit room‐temperature phosphorescence (RTP) is a very attractive topic owing to potential applications in organic optoelectronic devices. Herein, we present a facile approach to efficient and long‐lived organic RTP involving the doping of N‐phenylnaphthalen‐2‐amine (PNA) or its derivatives into a crystalline 4,4′‐dibromobiphenyl (DBBP) matrix. The resulting materials showed strong and persistent RTP emission with a quantum efficiency of approximately 20 % and a lifetime of a few to more than 100 milliseconds. Bright white dual emission containing blue fluorescence and yellowish‐green RTP from the PNA‐doped DBBP crystals was also confirmed by Commission Internationale de l'Eclairage (CIE) coordinates of (x=0.29–0.31, y=0.38–0.41). 相似文献
309.
MinMinLIANG MeiLingQI RuoNongFU 《中国化学快报》2005,16(5):659-662
We have investigated the use of flash evaporation, headspace solid-phase microextraction (HS-SPME) and steam distillation (SD) as sample concentration and preparation techniques for the analysis of volatile constituents present in Houttuynia cordata Thunb. The samples were analyzed by gas chromatography (GC) and identified by mass spectrometry (MS). Comparison studies were performed. It was found that the results obtained between Headspace solid-phase microextraction HS-SPME and SD techniques were in good agreement, Seventy-nine compounds in Houlluynia cordata Thunh were identified by MS. In flash evaporation, thirty-nine compounds were identified. Discrimination in the response for many constituents studied was not observed, which can be clearly observed in SD and HS-SPME techniques. As a conclusion, HS-SPME is a powerful tool for determining the volatile constitutes present in the Houttuynia cordata. 相似文献
310.
The authors study the Cauchy problem for the focusing nonlinear KunduEckhaus(KE for short) equation and construct the long time asymptotic expansion of its solution in fixed space-time cone with C(x1, x2, v1, v2) = {(x, t) ∈ R2: x = x0 + vt,x0 ∈ [x1, x2], v ∈ [v1, v2]}. By using the inverse scattering transform, Riemann-Hilbert approach and ■ steepest descent method, they obtain the lone... 相似文献