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51.
Sameena Ashraf Keith D. Bartle Anthony A. Clifford Robert Moulder 《Journal of separation science》1992,15(8):535-538
Lubricating oil additives have been analyzed by supercritical fluid chromatography on open tubular and packed capillary columns. Carbon dioxide and modified carbon dioxide were used as mobile phases and detection was accomplished by flame ionization and micro UV. Rapid and efficient analysis of the lubricating oil additives was demonstrated. 相似文献
52.
L. -M. Yuan R. -N. Fu S. -H. Gui X. -T. Xie R. -J. Dai X. -X. Chen Q. -H. Xu 《Chromatographia》1997,46(5-6):291-294
Summary The gas chromatographic separation of xylene isomers using special mixed stationary phases consisting of heptakis(2.3.6-tri-O-pentyl)-β-CD-AgNO3, heptakis (2.3.6-tri-O-pentyl)-β-CD-TINO3 or bentone-34-AgNO3 is investigated. The first two have positive synergistic effects for the separation of m, and p-xylene isomers, but negative
synergistic effects for the m, and oisomers. The separation effects depend on temperature, mixing ratio and how mixing is
accomplished. 相似文献
53.
O. N. Litvinenko A. N. Kuznetsov A. V. Olenev B. A. Popovkin 《Russian Chemical Bulletin》2007,56(10):1945-1947
Three new mixed tellurides of nickel and group 13–14 metals Ni3−δMTe2 (M = Sn, In, Ga) were prepared by high-temperature ampoule synthesis and studied by powder X-ray diffraction analysis. The
compound Ni3−δSnTe2 was also studied by single crystal X-ray diffraction analysis. The structural model of this phase and two analogs was described
as consisting of layers with nickel-main group metal bonds confined from the above by tellurium atoms. The van der Waals gap
formed through contacts between the tellurium atoms of neighboring layers is partially occupied by nickel atoms.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1879–1881, October, 2007. 相似文献
54.
Masao Matsuoka Tsuyoshi Matsuda June Tamaki Yoshifumi Yamamoto Chiaki Iwakura 《Research on Chemical Intermediates》2006,32(5):389-402
Laves-phase hydrogen storage alloy has a high potential for use as negative electrode material as alternative for the misch-metal-based
material. In order to improve the energy density and the rate capability of negative electrode, chemical and mechanical modification
of Lavesphase alloy with different stoichiometric ratios was carried out. Discharge capacity and high-rate dischargeabilty
was evaluated by electrochemical methods and the characterization of Laves-phase alloy was made by X-ray diffraction, SEM
observation and PCT measurement. The best result in discharge capacity could be obtained for stoichiometric Laves-phase alloy
with a composition of Zr0.9Ti0.1Ni1.1Co0.1Mn0.5V0.2Cr0.1 by boiling in 10 M KOH solution. On the other hand, the high-rate dischargeability was increased remarkably by introducing
mechanical grinding before alkali treatment. The cause for improved performance was discussed on the basis of thermodynamic
stability of metal hydride and changes in crystal structure and surface morphology influencing on diffusion coefficient and
diffusion path length of hydrogen. 相似文献
55.
T.?GrygarEmail author T.?Rojka P.?Bezdi?ka E.?Ve?erníková F.?Kovanda 《Journal of Solid State Electrochemistry》2004,8(4):252-259
Mixed Cu,Mn, Cu,Mn,Al, Cu,Mg,Mn, and Cu,Mg,Mn,Al oxides were obtained by calcination of amorphous basic carbonate (Cu,Mn oxides) or hydrotalcite-like precursors at 300–800 °C. The product composition was characterized by chemical analysis, XRD, and voltammetry of the microparticles. The XRD amorphous portion was detected indirectly by XRD and directly by voltammetry. Tenorite (CuO) and spinels were the main crystalline components of the oxide mixtures. The presence of Al shifted the onset of the crystallization of XRD-detectable tenorite and spinel to temperatures higher by 100–200 °C, and the presence of Mg shifted tenorite crystallization by 100 °C, but voltammetry was able to detect these phases even in XRD-amorphous or nanocrystalline calcines. Voltammetry is hence suitable for analysis of poorly crystalline oxides that can be used in heterogeneous catalysis. 相似文献
56.
R. V. Golovnya 《Chromatographia》1979,12(8):533-538
Summary Equations modifying Rohrschneider's relationship between I and thermodynamical characteristics values are derived. Polarity in chromatography is discussed as a possibility of stationary phases or absorbents to enter into intermolecular interactions and is determined on the basis of the partial molar free energies of solution (G) of six test substances. A simple method for the calculation of stationary phase polarity in terms of G from retention indices and McReynolds constants is given. Equations are presented for the calculation of stationary phase selectivity utilizing G data tabulated for selected test substances. The thermodynamical basis of selecting a reference phase for a unified system expressing the selectivity of stationary phases which can also be applied for adsorbents is suggested. The energy equivalent to an index unit, Gi.u., is discussed. 相似文献
57.
Summary The retention of 9 nonylphenyl ethylene oxide oligomers was determined in 15 reversed-phase chromatographic systems using silicone oils of various molecular mass as impregnating agents and silica, cellulose and alumina supports. The data were evaluated with principal component analysis carried out on the covariance and the correlation matrices. The RM values did not follow the additivity rule and they did not change linearly with increasing length of the ethylene oxide chain. This is probably due to the folded state of the chain in the eluent. The molecular mass of the silicone oils had a negligible effect on the retention whereas the retention increased with increasing level of impregnation. The support considerably influenced the lipophilicity values of these nonionic surfactants and cellulose seemed to be the most appropriate support. Calculations proved that the application of a correlation matrix may cause data distortion; therefore, the use of a covariance matrix is strongly proposed. 相似文献
58.
Due to their high polarity and unique selectivity, cyanopropyl silicones are basic stationary phases for high resolution capillary gas chromatography. Different OH-terminated cyanopropyl silicones, containing a high cyanopropyl content, were synthesized and chromatographically evaluated. Special attention was paid to the degree of immobilization of the phases in FSOT columns. Depending on the problem at hand, a choice has to be made between immobilization and maximum selectivity. 相似文献
59.
Huifang Xu Wei Wei Chengliang Zhang Shujiang Ding Xiaozhong Qu Dr. Jiguang Liu Dr. Yunfeng Lu Prof. Zhenzhong Yang Prof. 《化学:亚洲杂志》2007,2(7):828-836
This report presents a facile approach for the low‐temperature synthesis of crystalline inorganic‐oxide composite hollow spheres by employing the bulk controlled synthesis of inorganic‐oxide nanocrystals with polymer spheres as templates. The sulfonated polystyrene gel layer can adsorb the target precursor and induce inorganic nanocrystals to grow on the template in situ. The crystalline phase and morphology of the composite shell is tunable. By simply adjusting the acidity of the titania sol, crystalline titania composite hollow spheres with tunable crystalline phases of anatase, rutile, or a mixture of both were achieved. The approach is general and has been extended to synthesize the representative perovskite oxide (barium and strontium titanate) composite hollow spheres. The traditional thermal treatment for crystallite transformation is not required, thus intact shells can be guaranteed. The combination of oxide properties such as high refractive index, high dielectric constant, and catalytic ability with the cavity of the hollow spheres is promising for applications such as opacifiers, photonic crystals, high‐κ‐gate dielectrics, and photocatalysis. 相似文献
60.
本文通过XRD、SEM、EDS研究了Ti0.4Zr0.1V1.1Mn0.5Cr0.1Nix(x=0,0.2,0.4,0.6,0.8)合金的相结构和电化学性能。该合金系由BCC结构的V基固溶体主相和六方结构的C14 Laves第二相组成,Ni能够促进第二相的生成,Ni含量的增加导致了各相中的化学组成和晶格参数的变化,并通过电化学方法研究了Ni含量对0.4Zr0.1V1.1Mn0.5Cr0.1合金电极的最大放电容量、自放电性能、高倍率放电性能、循环稳定性能等的影响。 相似文献