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Separation of atropisomers by chiral liquid chromatography and thermodynamic analysis of separation mechanism

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Journal of Pharmaceutical Analysis 2017年第3期7卷 156-162页

作者： Ling Zhang Yue Hu Elizabeth Galella Frank P. Tomasella William P. fish Chemical and Synthetic Development Bristol-Myers Squibb Co.New BrunswickNJ 08903USA Drug Product Science and Technology Bristol-Myers Squibb Co.New BrunswickNJ 08903USA

In the pharmaceutical industry, the analysis of atropisomers is of considerable interest from both scientific and regulatory perspectives. The compound of interest contains two stereogenic axes due to the hindered rotation around the single bonds connecting the aryl groups, which results in four potential configurational isomers(atropisomers). The separation of the four atropisomers was achieved on a derivatized β-cyclodextrin bonded stationary phase. Further investigation showed that low temperature conditions, including sample preparation(-70 °C), sample storage(-70 °C), and chromatographic separation(6 °C), were critical to preventing interconversion. LC-UV-laser polarimetric analysis identified peaks 1 and 2 as a pair of enantiomers and peaks3 and 4 as another. Thermodynamic analysis of the retention data indicated that the separation of the pairs of enantiomers is primarily enthalpy controlled as indicated by the positive slope of the van't Huff plot. The difference in absolute Δ(Δ H), ranged from 2.20 k J/mol to 2.42 k J/mol.

关键词： Atropisomer separation Chiral HPLC Thermodynamic parameters β-cyclodextrin stationary phase Chiral separation mechanism

Investigation of Ergosterol in situ Circular Dichroic Spectroelectrochemistry

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Chinese Chemical Letters 1998年第1期9卷 103-106页

作者： Lu, YJ Zhu, YC Cheng, gj Dong, SJ Chinese Acad Sci Changchun Inst Appl Chem Electroanalyt Chem Lab Changchun 130022 Peoples R China

In the present paper, the electrochemical behavior of ergosterol has been investigated by in situ circular dichroism (CD) spectroelectrochemistry with long path-length thin layer cell. E-0 (1.02V), alpha n(alpha) (0.302) of the electroxidation process of ergosterol were obtained from the CD spectroelectrochemical data. The mechanism of the electroxidation process of ergosterol is suggested.

关键词： ergosterol circular dichroism spectroelectrochemistry electroxidation

Increased expression of the nitric oxide synthase gene and protein in corpus cavernosum by repeated dosing of udenafil in a rat model of chemical diabetogenesis

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Asian Journal of Andrology 2009年第4期11卷 435-442页

作者： gj Ahn HK Chung CH Lee KK Kang BO Ahn Research Laboratory Dong-A Pharmaceutical Company Kiheung Yongin Kyunggi 446-905 Korea

Erectile dysfunction （ED） is a major complication of diabetes mellitus （DM）. This study investigates the relationship between ED and the downregulation of constitutive nitric oxide synthase （cNOS） in the corpus cavernosum （CC） of diabetic rats. It also examines the effects of udenafil, a phosphodiesterase type 5 （PDE5） inhibitor, on ED and cNOS expression levels. After 16 weeks of daily oral treatment with udenafil in diabetic rats, the intracavernous pressure/mean arterial pressure （ICP/MAP） ratio was recorded to measure erectile function, and cNOS expression was measured using reverse transcriptase （RT）-PCR and immunoblots. Although the ICP/ MAP ratio and the expression levels of endothelial NOS （eNOS） and neuronal NOS （nNOS） in the CC were markedly decreased in diabetic rats, long-term udenafil treatment improved the erectile function and increased cNOS expression compared with diabetic controls. These findings suggest that ED in DM is closely related to decreased cNOS expression in the CC and that udenafil has the ability to compensate for this pathological change by modulating cNOS expression. Udenafil also has an inhibitory role in cyclic guanosine monophosphate （cGMP） degradation.

关键词： cNOS diabetes mellitus erectile dysfunction udenafil

SYNTHESIS　AND　CHARACTERIZATION　OF　C_（60）NAr，THE　FIRST　AZIRIDINE　FULLERENE　DERIVATIVE

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Chinese Chemical Letters 1995年第7期6卷 569-572页

作者： Feng, J Li, JS Dong, GX Ji, gj Acad Sinica Inst Chem Beijing 100080 Peoples R China

Fullerene deriwtives C60NAr 2 were opthesized by the reaction of fullerene C60 with pstituted Pbenyl andes in refluxing chlorobenzene. The structure of each product was elucidated on the basis of FD-MS. UV-Vis. IR. H... 详细信息

关键词： FIRST AZIRIDINE DERIVATIVE AND FULLERENE NAr OF SYNTHESIS THE

System-level Pareto frontiers for on-chip thermoelectric coolers

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Frontiers in Energy 2018年第1期12卷 109-120页

作者： Sevket U. YURUKER Michael C. fish.Zhi YANG Nicholas BALDASARO Philip BARLETTA Avram BAR-COHEN Bao YANG Department of Mechanical Engineering University of MarylandCollege Park MD 20742 USA Research Triangle Institute Research Triangle Park NC 27709 USA Micross Components Research Triangle Park NC 27709 USA

The continuous rise in heat dissipation of integrated circuits necessitates advanced thermal solutions to ensure system reliability and efficiency. Thermoelectric coolers are among the most promising techniques for dealing with localized on-chip hot spots. This study focuses on establishing a holistic optimization methodol- ogy for such thermoelectric coolers, in which a thermo- electric element＇s thickness and the electrical current are optimized to minimize source temperature with respect to ambient, when the thermal and electrical parasitic effects are considered. It is found that when element thickness and electrical current are optimized for a given system architecture, a ＂heat flux vs. temperature difference＂ Pareto frontier curve is obtained, indicating that there is an optimum thickness and a corresponding optimum current that maximize the achievable temperature reduc- tion while removing a particular heat flux. This methodol- ogy also provides the possible system level AT＇s that can be achieved for a range of heat fluxes, defining the upper limits of thermoelectric cooling for that architecture. In this study, use was made of an extensive analytical model, which was verified using commercially available finite element analysis software. Through the optimization process, 3 pairs of master curves were generated, which were then used to compose the Pareto frontier for any given system architecture. Finally, a case study wasperformed to provide an in-depth demonstration of the optimization procedure for an example application.

关键词： thermoelectric cooling thermal management,optimization high flux electronics

Cyclopropanation Versus Deoxygenation in the Reactions of Halocarbenes with pre-Aromatic Ketones

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Chinese Chemical Letters 1999年第4期10卷 271-272页

作者： Wang, HX Zhang, gj Gu, WX Huan, ZW Cheng, JP Nankai Univ Dept Chem Tianjin 300071 Peoples R China

The reactions of halocarbenes with pre-aromatic ketones 1, 2 resulted in cyclopropanation and deoxygenation products. The varying product ratio could be accounted for by a mechanism involving the carbonyl ylide interm... 详细信息

关键词： halocarbene deoxygenation cyclopropanation mechanism

SLOW PELLETING COAGULATION OF POLYMER LATEX EMULSION

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Chinese Chemical Letters 1996年第3期7卷 297-298页

作者： Li, YM Chen, MW Xu, gj Ou, SH Wang, K ZHEJIANG UNIV DEPT POLYMER SCI & ENGNHANGZHOU 310027PEOPLES R CHINA

In this paper, slow pelleting flocculation of polymer latex consisting of butadiene, styrene and methyl methacrylate(MBS) were investigated, using aqueous H2SO4 as coagulant. It is found that spherical particles with uniform particle size and high bulk density were produced in the narrow range of pH. In order to obtain good particle morphology, well-distributed concentration, temperature and shear field in the coagulating system were required. Polymer latex made from emulsion polymerization often needs to be converted into dry powders. Usually, we simply add excessive coagulant, such as inorganic acid, salt, etc., into latex emulsion to make it coagulate. The particles formed with such method always have irregular shape and high fines content. In recent years, more attention has been paid to the method of getting coagulated particles with satisfactory particle morphology(1-3)].

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Development of a laser capture microscope-based single-cell-type proteomics tool for studying proteomes of individual cell layers of plant roots

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Horticulture Research 2016年第1期3卷 190-197页

作者： Yingde Zhu Hui Li Sarabjit Bhatti Suping Zhou Yong Yang Tara fish.Theodore W Thannhauser Department of Agricultural and Environmental Sciences College of AgricultureHuman and Natural SciencesTennessee State UniversityNashville37209TNUSA R.W.Holley Center for Agriculture and Health USDA-ARS538 Tower RoadNew YorkNY 14853IthacaNew YorkUSA

Single-cell-type proteomics provides the capability to revealing the genomic and proteomics information at cell-level ***,the methodology for this type of research has not been *** paper reports developing a workflow of laser capture microdissection(LCM)followed by gel-liquid chromatography-tandem mass spectrometry(GeLC-MS/MS)-based proteomics analysis for the identification of proteomes contained in individual cell layers of tomato ***-sections(~10-μm thick,10 sections per root tip)were prepared for root tips of tomato germinating *** and cortical cells(5000–7000 cells per tissue type)were isolated under a LCM *** were isolated and then separated by SDS–polyacrylamide gel electrophoresis followed by in-gel-tryptic *** MS and MS/MS spectra generated using nanoLC-MS/MS analysis of the tryptic peptides were searched against ITAG2.4 tomato protein database to identify proteins contained in each single-cell-type *** on the biological functions,proteins with proven functions in root hair development were identified in epidermal cells but not in the cortical *** of these proteins were found in Al-treated roots *** results demonstrated that the cell-type-specific proteome is relevant for tissue-specific functions in tomato *** the coverage of proteomes and reducing the inevitable cross-contamination from adjacent cell layers,in both vertical and cross directions when cells are isolated from slides prepared using intact root tips,are the major challenges using the technology in proteomics analysis of plant roots.

关键词： roots laser directions

EFFECT　OF　ANNEALING　TEMPERATURE　ON　TEXTURE　OF　COLD－ROLLED　Ni₄₇Ti₄₄Nb₉　SHEET

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中国有色金属学会会刊：英文版 1995年第1期5卷 88-93页

作者： YANG, gj XIE, LY HU, WY DENG, J HAO, SM NW INST NONFERROUS MET RES BAOJI 721014PEOPLES R CHINA NORTHEASTERN UNIV SHENYANG 110006PEOPLES R CHINA

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关键词： annealing temperature Ni47Ti44Nb9 texture ODF