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排序方式: 共有154条查询结果,搜索用时 46 毫秒
1.
F. P. Emmenegger 《无机化学与普通化学杂志》1987,545(2):56-68
The equilibrium constants of the reactions MBr2(s) + Al2Br6(sln) ? MAl2Br8(sln) M = Cr, Mn, Co, Ni, Zn, Cd have been measured at 298 K in toluene. Ni: 0.017 ± 0.0024, Co: 0.54 ± 0.07, Zn: 1.5 ± 0.2, Mn: 2.1 ± 0, 7, Cr: 2.2 ± 1, Cd: 7 ± 5. They are compared with literature values of the equilibrium constants of analogous reactions in the gas phase MX2(s) + Al2X6(g) ? MAl2X8(g), X = Cl, Br. For CoAl2Br8(sln) the temperature dependence of the equilibrium constant yielded ΔfH = ?9.4 ± 1 kJ mol?1 and ΔfS = ?39.5 ± 3 J mol?1 K?1 while literature values for CoAl2Br8(g) are ΔfH = 42.4 ± 2 kJ mol?1 and ΔfS = 42.9 ± 2 J mol?1 K?1. The solubility of Al2Br6 in toluene as well as its enthalpy of dissolution have been measured in order to evaluate ΔH° and ΔS° of the solvation of Al2Br6(g) and CoAl2Br8(g) in toluene by a thermodynamic cycle. Solvation of Al2Br6(g): ΔH = ?72.7 ± 1 kJ mol?1, ΔS = ?139.6 ± 4 J mol?1 K?1, solvation of CoAl2Br8(g): ΔH = ?124.5 ± 4kJ mol?1, ΔS = ?222 ± 9J mol?1 K?1. Thus, CoAl2Br8 interacts more strongly with the solvent toluene than Al2Br6 does. 相似文献
2.
Masson JF Battaglia TM Davidson MJ Kim YC Prakash AM Beaudoin S Booksh KS 《Talanta》2005,67(5):918-925
The elimination or minimization of non-specific protein adsorption from serum is critical for the use of surface plasmon resonance (SPR) sensors for in vitro and in vivo analysis of complex biological solutions. The ultimate goals in this application are to minimize non-specific adsorption of protein and to maximize analyte signal. A reduction of the non-specific protein adsorption from serum of up to 73% compared to carboxymethylated-dextran 500 kDa (CM-dextran) was achieved following a survey of eight biocompatible polymers and 10 molecular weights of CM-dextran. These coatings minimize non-specific adsorption on the sensor while also serving as immobilization matrices for antibody fixation to the probes. Polymers including polysaccharides: CM-dextrans, CM-hyaluronic acid, hyaluronic acid, and alginic acid were investigated. Humic acid, polylactic acid, polyacrylic acid, orthopyridyldisuldfide–polyethyleneglycol–N-hydroxysuccinimide (OPSS–PEG–NHS), and a synthesized polymer; polymethacrylic-acid-co-vinyl-acetate (PMAVA) were also used. The non-specific protein adsorption reduction was measured over a 14 day period at 0 °C for each polymer. Calibration curves using some of these polymers were constructed to show the performance and low detection limit possibilities of these new antibody supports. For many of the polymers, this is the first demonstration of employment as an antibody support for an optical or surface active sensor. CM-dextran is the polymer offering the largest signal for the antigen detection. However, the biocompatible polymers demonstrate a greater stability to non-specific binding in serum. These biocompatible polymers offer different alternatives for CM-dextran. 相似文献
3.
Jean-Claude Berthet Jean-Francois Le Mar chal Michel Ephritikhine 《Journal of organometallic chemistry》1994,480(1-2):155-161
The monocyclooctatetraene uranium complex [U(COT)(I)2(THF)2] (COT=η-C8H8; THF=tetrahydrofuran), isolated from the reaction of bis(cyclooctatetraene)uranium with iodine, is a precursor for the synthesis of the alkyl derivatives [U(COT)(CH2Ph)2i (HMPA) 2], [U(COT)(CH2SiMe3)2(HMPA)] (HMPA=hexamethyl phosphorous triamide) and [U(COT)CH2SiMe3)3] [Li(THF)3] and of the mixed-ring compounds [U(COT)(η-C5R5)(I)] (R=H or Me). The last were used to prepare the amide and alkyl complexes [U(COT)(η-C5H5)(N{SiMe3}2)] and [U(COT)(η-C5Me5)(CH2SiMe3)]. 相似文献
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5.
Charly Mayeux Peeter Burk Jean-Francois Gal Ivari Kaljurand Ilmar Koppel Ivo Leito Lauri Sikk 《Journal of the American Society for Mass Spectrometry》2014,25(11):1962-1973
According to high level calculations, the upper part of the previously published FT-ICR lithium cation basicity (LiCB at 373 K) scale appeared to be biased by a systematic downward shift. The purpose of this work was to determine the source of this systematic difference. New experimental LiCB values at 373 K have been measured for 31 ligands by proton-transfer equilibrium techniques, ranging from tetrahydrofuran (137.2 kJ mol?1) to 1,2-dimethoxyethane (202.7 kJ mol?1). The relative basicities (ΔLiCB) were included in a single self-consistent ladder anchored to the absolute LiCB value of pyridine (146.7 kJ mol?1). This new LiCB scale exhibits a good agreement with theoretical values obtained at G2(MP2) level. By means of kinetic modeling, it was also shown that equilibrium measurements can be performed in spite of the formation of Li+ bound dimers. The key feature for achieving accurate equilibrium measurements is the ion trapping time. The potential causes of discrepancies between the new data and previous experimental measurements were analyzed. It was concluded that the disagreement essentially finds its origin in the estimation of temperature and the calibration of Cook’s kinetic method. Graphical Abstract
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6.
Simon Eyer Nicholas P. Stadie Andreas Borgschulte Lukas Emmenegger Joachim Mohn 《Adsorption》2014,20(5-6):657-666
Methane (CH \(_4\) ) adsorption has been widely studied, mainly in the context of natural gas purification. A much less prominent, but highly relevant application is the preconcentration of CH \(_4\) from ambient air. In this study, we compare six different commercial adsorbent materials with respect to their effectiveness for methane preconcentration: a macroporous polymeric resin (HayeSep D), multi-walled carbon nanotubes, two microporous metal-organic frameworks (HKUST-1 and ZIF-8), and two zeolites (5A and 13X). The most relevant properties, such as isosteric enthalpy of adsorption, specific surface area and the selectivity for CH \(_4\) adsorption over N \(_2\) were characterized by analyzing adsorption/desorption isotherms. Using these parameters, we discuss the tested adsorbents with respect to the most important properties and identify the most promising candidates. Furthermore we identify the experimental conditions that are expected to give the best results with respect to practical applications. 相似文献
7.
We compute the 2-rank of the wild kernel WK2(F) of a number field by constructing a 2-class group ad hoc. The main result generalizes in the more intricate case the canonical isomorphism established for odd primes under the assumption in a previous article (cf. (Acta. Arith. 67 (1994) 335; Math. Z. 238 (2001) 335)). It involves a criterium of triviality for the 2-part of the wild kernel of Galois number fields and, in the particular case of quadratic fields, it leads to a logarithmic interpretation of the diophantine conditions obtained by other authors. 相似文献
8.
Ismaili L Truong TT André C Thomassin M Mozer JL Robert JF Xicluna A Refouvelet B Millet J Nicod L Guillaume YC 《Journal of AOAC International》2003,86(2):222-228
The mechanism of the binding of D,L dansyl amino acids to teicoplanin was investigated. Na+ was used as an indicator of the interactions between the solutes and teicoplanin. The number (n) of sodium ions, Na+, excluded from the solute-teicoplanin interface when analyte transfer occurred was determined. A thermodynamic study and enthalpy-entropy compensation were performed to further explore the interaction mechanism. From these results, it was shown that teicoplanin was balanced between 2 conformational states characterized by distinct enantioselective properties. This approach indicates that liquid chromatography (LC) is a useful tool to extract physicochemical and molecular information from retention data. Thus, LC can be used as a complementary technique with the conventional techniques of molecular interaction analysis. 相似文献
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