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1. The enantio-differentiating hydrogenation of methyl acetoacetate over tartaric acid modified Raney nickel catalysts with the in-situ modification | |||
LI Rong,CHEN Long,CAI Shunli | |||
Chemistry 26 April 2011 | |||
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Abstract:Tartaric acid modified Raney nickel catalyst has been prepared by the in-situ modification and applied in the enantio-differentiating hydrogenation of methyl acetoacetate. The effects of varying the reaction temperature and pressure, solvent type, the amount of tartaric acid, additive and the reaction time on the optical yield and, in part, on the hydrogenation activity were systematically investigated. Various different types of Raney nickel catalysts were used in this paper. In order to deeply understand the inherent problems of the factor effects, various physico-chemical methods were employed in this research, such as inductive coupled high frequency plasma source (ICP), X-ray diffractometry (XRD) and so on. The highest optical yield of 61.6% was achieved over the improved T-1 RNi catalyst with an addition of 0.05 ml acetic acid under the optimal conditions. | |||
TO cite this article:LI Rong,CHEN Long,CAI Shunli. The enantio-differentiating hydrogenation of methyl acetoacetate over tartaric acid modified Raney nickel catalysts with the in-situ modification[OL].[26 April 2011] http://en.paper.edu.cn/en_releasepaper/content/4423027 |
2. A Frist-principles Study of the Charge-transfer Parameters in Dithiophene-tetrathiafulvalene(DT-TTF) crystal | |||
Zhang Weiwei,Liang Wanzhen,Zhao Yi | |||
Chemistry 12 May 2010 | |||
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Abstract:The parameters controlling charge-transfer, reorganization energy and electronic coulping, in the Dithiophene-tetrathiafulvalene (DT-TTF) crystal have been inverstigated on the basis of a density functional theory (DFT). The results reveal that only several high-frequency intramolecular vibrational modes dominate the reorganization energy from the mode-specific analysis. The electronic couplings obtained from the reduced two-states model (TM) are differences obviously for different types of the dimers. Meanwhile, the electronic couplings of isolated DT-TTF dimers are affected by the surrounding molecules in crystal. Furthermore, the nulcear-coordinate dependence of electronic coupling prefers to perform an exponential or Gaussian property for most intermolecular modes rather than a linear one . | |||
TO cite this article:Zhang Weiwei,Liang Wanzhen,Zhao Yi. A Frist-principles Study of the Charge-transfer Parameters in Dithiophene-tetrathiafulvalene(DT-TTF) crystal[OL].[12 May 2010] http://en.paper.edu.cn/en_releasepaper/content/4371919 |
3. Interaction of BSA and long-chain imidazolium ionic liquid measured by fluorescence spectra and surface tension | |||
Fei Geng,Liqiang Zheng,Li Yu,Ganzuo Li,Chenho Tung | |||
Chemistry 23 July 2009 | |||
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Abstract:The binding of long-chain imidazolium ionic liquid (IL), 1-tetradecyl-3-methylimidazolium bromide (C14mimBr) to bovine serum albumin (BSA) were investigated by fluorescence spectra and surface tension. Fluorescence spectra show that tryptophan (Trp) residues, one of the intrinsic fluorophores in BSA, are buried to a hydrophobic microenvironment with the addition of C14mimBr. The addition of C14mimBr induces denaturation of BSA. Moreover, the fluorescence quenching mechanism was determined to be static quenching. The equilibrium constant (K) and the number of binding sites (n) were calculated based on the results of fluorescence measurement. According to the surface tension plots, the critical aggregation concentration (CAC) and critical micelle concentration (CMC) under different BSA concentrations at various temperatures were investigated. The surface tension indicates that C14mimBr binds to BSA through electrostatic attraction at low concentration of C14mimBr (below CMC) and through hydrophobic interaction at high concentration of C14mimBr (above CMC). Additionally, thermodynamic parameters of micelle formation were determined. This study provides an understanding of the binding of C14mimBr to BSA. | |||
TO cite this article:Fei Geng,Liqiang Zheng,Li Yu, et al. Interaction of BSA and long-chain imidazolium ionic liquid measured by fluorescence spectra and surface tension[OL].[23 July 2009] http://en.paper.edu.cn/en_releasepaper/content/34047 |
4. Size Effects for the Adsorption of Alkali Metal Atoms on the Si(001) Surface | |||
Cai Yaping,Li Yi,Zhang Yongfan | |||
Chemistry 06 July 2009 | |||
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Abstract:The adsorptions of a series of alkali metal (AM) atoms, Li, Na, K, Rb and Cs on a Si(001)-2x2 surface at 0.25 monolayer coverage have been investigated systematically by means of density functional theory calculations. The effects of the size of AM atoms on the Si(001) surface are focused in the present work by examining the most stable adsorption site, diffusion path, band structure, charge transfer, and the change of work function for different adsorbates. Our results suggest that, when the interactions among AM atoms are neglectable, these AM atoms can be divided into three classes. For Li and Na atoms, they show unique site preferences, and correspond to the strongest and weakest AM-Si interactions, respectively. In particular, the band structure calculation indicates that the nature of Li-Si interaction differs significantly from others. For the adsorptions of other AM atoms with larger size (namely, K, Rb and Cs), the similarities in the atomic and electronic structures are observed, implying that the atom size has little influence on the adsorption behavior for these large AM atoms on the Si(001) surface. | |||
TO cite this article:Cai Yaping,Li Yi,Zhang Yongfan. Size Effects for the Adsorption of Alkali Metal Atoms on the Si(001) Surface[OL].[ 6 July 2009] http://en.paper.edu.cn/en_releasepaper/content/33661 |
5. Interactions between a surface active imidazolium ionic liquid and BSA | |||
Fei Geng,Liqiang Zheng,Li Yu,Jie Liu,Zhen Li | |||
Chemistry 19 February 2009 | |||
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Abstract:The interactions between a surface active imidazolium ionic liquid (IL), 1-tetradecyl-3-methylimidazolium bromide (C14mimBr) and bovine serum albumin (BSA) were investigated by surface tension, isothermal titration microcalorimetry, far-UV circular dichroism (CD) and fluorescence spectra. The surface tension measurement shows the formation of C14mimBr/BSA complex and the effect of the complex on surface tension. The enthalpy change in the whole interaction process between C14mimBr and BSA was obtained by isothermal titration microcalorimetry, and the results show alteration of the BSA structure. The contents of α-helix and random coil were obtained by far-UV CD. Changes of these contents reveal that the secondary structure of BSA changes with addition of C14mimBr. Fluorescence spectra show that tryptophan (Trp) residues, one of the intrinsic fluorophores in BSA, are exposed to a hydrophobic microenvironment with the addition of C14mimBr. | |||
TO cite this article:Fei Geng,Liqiang Zheng,Li Yu, et al. Interactions between a surface active imidazolium ionic liquid and BSA[OL].[19 February 2009] http://en.paper.edu.cn/en_releasepaper/content/29320 |
6. Solubilities of L-Proline in Subcritical HFC-134a and Supercritical CO2 Fluid | |||
LIU Ling,LI Zhen,LIU Zhong-Wen,LIU Zhao-Tie | |||
Chemistry 02 February 2009 | |||
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Abstract:A static method coupled with gravimetric analysis was used to measure the solubility of L-proline in subcritical 1,1,1,2-tetrafluoroethane (HFC-134a) and supercritical CO2(scCO2). The solubility of L-proline is much higher in HFC-134a fluid than in scCO2. The solubilities of L-proline in HFC-134a and scCO2 are affected by temperature and pressure. The solubilities increase with increasing temperature and pressure for both scCO2 and HFC-134a solvents. The densities of scCO2 and subcritical HFC-134a were calculated using the Peng-Robinson (P-R) equation. Experimentally determined density data were used to assess the accuracy of the P-R equation. | |||
TO cite this article:LIU Ling,LI Zhen,LIU Zhong-Wen, et al. Solubilities of L-Proline in Subcritical HFC-134a and Supercritical CO2 Fluid[J].J. Chem. Eng. Data ,2009年,54卷,9期,2780 ~ 2784 |
7. Study on the Pyrolysis of methyl tert-butyl ether (MTBE) with Molecular-Beam Mass Spectrometry and Tunable Synchrotron VUV Photoionization | |||
Taichang Zhang,Wang jing,Yuan Tao,Hong Xin,Zhang Lidong,Fei Qi | |||
Chemistry 06 January 2009 | |||
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Abstract:An experimental study of MTBE pyrolysis (3.72% MTBE in argon) has been performed at low pressure (267 Pa) within the temperature range from 700 to 1420 K. The pyrolysis process was detected with the tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam mass spectrometry (MBMS). About thirty intermediates are identified from near-threshold measurements of photoionization mass spectrum and photoionization efficiency spectrum. Among them, H2, CO, CH4, CH3OH and C4H8 are the major pyrolysis products. The radicals such as methyl, methoxy, propargyl, allyl, C4H5 and C4H7 are detected. The isomers of pyrolysis products are identified as well, i.e., propyne and allene, 1,2,3-butatriene and vinylacetylene, isobutene and 1-butene, propanal and acetone. Furthermore, the mole fractions of the pyrolysis products have been evaluated under various temperatures. Meanwhile the initial formation temperatures of different pyrolysis products can be obtained. This work is anticipated to present a new experimental method for pyrolysis study, and help understand the pyrolysis and combustion chemistry of MTBE and other oxygenated fuels. | |||
TO cite this article:Taichang Zhang,Wang jing,Yuan Tao, et al. Study on the Pyrolysis of methyl tert-butyl ether (MTBE) with Molecular-Beam Mass Spectrometry and Tunable Synchrotron VUV Photoionization[OL].[ 6 January 2009] http://en.paper.edu.cn/en_releasepaper/content/27379 |
8. Synthesis and Thermotropic Liquid Crystalline Properties of Heterogemini Surfactants Containing a Quaternary Ammonium and a Hydroxyl Group | |||
Tianhua Zhou,Jianxi Zhao | |||
Chemistry 04 January 2009 | |||
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Abstract:A homologous series of novel heterogemini surfactants, (N, N-Dimethyl-N-[3-(alkyloxy)-2-hydroxypropyl]-alkylammonium bromide (referred to as CmOhpNCn; m, n = 10, 8; 12, 8; 14, 8; 16, 8; 14, 10; 12, 12 and 10, 14) has been synthesized. Their thermotropic phase behavior has been investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), infrared spectroscopy (IR) and X-ray diffraction (XRD). All the compounds showed high thermal stability and formed enantiotropic thermotropic smectic A liquid crystals. The mesophase region was sensitive to the overall length (m + n) of the two hydrophobic tails and was widened with increasing (m + n). When fixing the overall length of the two hydrophobic tails (m + n =24), the liquid crystal region was affected little by the dissymmetry of the two hydrophobic chains. The combination of IR and XRD results suggested the cis configuration of the alkyl chain and the alkoxy chain with respect to the extended N溏CH2溏CH(OH) skeleton in both crystal lattice and liquid crystal mesophase. The folding of the alkoxy chain at the carbon atom connecting the hydroxyl group led to the hydrogen bonding between the hydroxyl and the Br溏 counterion, which is beneficial to stabilizing the liquid crystal phase. | |||
TO cite this article:Tianhua Zhou,Jianxi Zhao. Synthesis and Thermotropic Liquid Crystalline Properties of Heterogemini Surfactants Containing a Quaternary Ammonium and a Hydroxyl Group[OL].[ 4 January 2009] http://en.paper.edu.cn/en_releasepaper/content/27261 |
9. Metal-Phosphorus Bonding in Complexes W@Au12PX3 (X = H, F, Cl, Br, I) - Relativistic DFT Investigations | |||
Jia Li,Yi-Xiang Qiu,Shu-Guang Wang | |||
Chemistry 04 January 2009 | |||
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Abstract:Relativistic density functional theory (DFT) calculations of the geometries and Au–P bonding of W@Au12PX3 (X = H, F, Cl, Br, I) have been carried out. There are some regular changes in geometry and binding of these two kinds of complexes with the variation of the phosphanes PX3. The energy decomposition analysis confirms that the PX3 ligands are σ donors. The donor tendency (ΔEσ/ΔEπ) decreases for different X with increasing electro negativity. | |||
TO cite this article:Jia Li,Yi-Xiang Qiu,Shu-Guang Wang. Metal-Phosphorus Bonding in Complexes W@Au12PX3 (X = H, F, Cl, Br, I) - Relativistic DFT Investigations[OL].[ 4 January 2009] http://en.paper.edu.cn/en_releasepaper/content/27242 |
10. Vanadia supported on H2O2-detemplated mesoporous SBA-15 as new effective catalysts for the oxidative dehydrogenation of propane | |||
Xu Jie,Fan Kangnian,Chen Miao,Cao Yong,Liu Yongmei,He Heyong | |||
Chemistry 04 July 2008 | |||
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Abstract:Mesoporous SBA-15(H2O2) material synthesized via a controlled H2O2-based detemplation at mild conditions has been employed as new type of support to load vanadia. The ordered mesostructure of the SBA-15 host is retained as indicated by XRD and nitrogen adsorption measurements, and the surface areas of the V-SBA-15(H2O2) materials are in the range of 464-667 m2g1 comparable to 772 m2g1 for the parent SBA-15(H2O2) material. The characterization results also indicate the presence of a high abundance of surface silanol groups inside the silica pores, which can allow controlled vanadium loading up to 4.5 wt % or V coverage up to 1.01 Vnm2. In contrast with conventional calcination-derived SBA-15(C) sample the high population of the surface hydroxyl groups as well as high structural stability of the SBA-15(H2O2) material allowed a very good dispersion of the vanadia on its surface leading to high productivities of propylene during the oxidative dehydrogenation of propane. | |||
TO cite this article:Xu Jie,Fan Kangnian,Chen Miao, et al. Vanadia supported on H2O2-detemplated mesoporous SBA-15 as new effective catalysts for the oxidative dehydrogenation of propane[OL].[ 4 July 2008] http://en.paper.edu.cn/en_releasepaper/content/22709 |
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