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31.
Theoretical and experimental voltammetric studies of copper reduction in chloride media show that electrodeposition on the hanging mercury drop electrode (HMDE) is controlled by competitive reduction between Cu(II) organic species and the Cu(I)Cl2? intermediate. For reversible Cu(II) species reduction, the change from organic ligand to chloride control of the final reduction step can be predicted by thermodynamic calculation. On the other hand in irreversible systems (e.g. estuarine waters) involvement of the CuCl2? intermedite in the electrodeposition is more complex and can occur both before and after amalgamation. 相似文献
32.
The compounds (η5-C5R5)2Fe2(CO)2(μ-CO)(μ-CH2) (R = H, CH3) have been prepared through the reaction of chloromethyl pivalate with the appropriate metal anions, η5-C5H5Fe(CO)2K and η5-C5Me5Fe(CO)2K. 相似文献
33.
The amine substituted phosphines (C6H5)2PN(H)CH2CH3 and (C6H5)2PN(H)CH2C6H5 react with C5H5Fe(CO)2CH(C6H5) (OCH3) photolytically to give moderate yields of the four-membered chelate ring complexes C5H5H (C6H5)] and C5H5H(C6H5)], respectively. Photolysis of C5H5Fe(CO)2CH(C6H5) (OCH3) in the presence of (S)-(?)-diphenyl(1-phenylethylamino)phosphine leads to the isolation of C5H5Fe(CO)[(C6H5)2PNC(CH3) (C6H5)]CH2C6H5 which is proposed to arise from a formally 1,3-hydrogen shift rearrangement of an intermediate four-membered chelate ring complex. 相似文献
34.
Two approaches for performing competitive binding immunoassays by HPLC and other flow-based systems are the simultaneous and sequential injection methods. Both these techniques make use of a column with a limited amount of antibody, onto which is injected a sample and a fixed amount of a labeled analyte analog. An indirect measure of the unlabeled analyte in the sample is then obtained by looking at the amount of analog in either the nonretained or retained peaks. In the simultaneous injection mode, the sample and labeled analog are applied at the same time to the column, while in the sequential mode the sample is injected first, followed by the analog. This results in a difference in the analytical characteristics of these two approaches. This study used chromatographic theory and previous data obtained for injections of human serum albumin (HSA) onto an anti-HSA antibody column to compare the response, detection limits, range, and sensitivity of these methods. Under equivalent conditions, it was found that the sequential method always provided the best lower limit of detection and sensitivity. However, the simultaneous mode had a broader dynamic range and higher upper limit of detection. From these observations, several guidelines were developed regarding the use and selection of such assays for new applications. 相似文献
35.
Brian F.G. Johnson Jack Lewis William J.H Nelson Maria D. Vargas Dario Braga Mary McPartlin 《Journal of organometallic chemistry》1983,246(2):c69-c73
The high nuclearity mixed metal cluster monoanions [Os10C(CO)24Cu(NCMe)]? (I) and [Os10C(CO)24AuPPh3]? (II) have been obtained by reaction of the carbido-dianion [Os10C(CO)24]2? (III) with one equivalent of [Cu(NCMe)4] [BF4] and Ph3PAuCl, respectively, in CH2Cl2. X-ray analysis of the [PPh3Me]+ salts of I and II show that the Cu and Au ligands have added to capping tetrahedra of the dianion III in μ3- and μ2-bridging positions, respectively. 相似文献
36.
Bond AD Derossi S Jensen F Larsen FB McKenzie CJ Nelson J 《Inorganic chemistry》2005,44(17):5987-5989
Treatment of cryptand L(1) with Cu(II) generates a H3O2(-)-bridged dicopper(II) cryptate, 2, where the guest anion has responded to steric constraint by a significant shortening of the O-O distance to 2.325(9) A; computational optimization at the B3LYP/6-31(d) level suggests that the bridging O-H...O H-bond is bent (approximately 157 degrees) but that the barrier to interchange of the bridging H atom is low (<4 kJ mol(-1)). This cryptate, rather than the [Cu2L(1)muCN]3+ species recently claimed to derive from cleavage of the C-C bond of the solvent, is the product of acetonitrile recrystallization of the initially formed reaction product, 1. 相似文献
37.
The high frequency acoustic response of liquids is measured in a manner directly analogous to conventional ultrasonic measurements. Two thin metal films act as acoustic transducer and receiver for a liquid layer between them. Pulsed optical excitation generates high bandwidth wave packets in the transducer, and these are detected in the receiver after damping and dispersion by the liquid. This initial measurement probes structural relaxation dynamics of glycerol in the frequency range 2-20 GHz, for temperatures between 235 and 291 K. The analysis presented here demonstrates the presence of excess relaxation, not accounted for by either the alpha or beta relaxation of the mode-coupling theory, and suggests the presence of constant loss in the susceptibility spectrum of supercooled glycerol. 相似文献
38.
Craviso GL Chatterjee I Publicover NG 《Bioelectrochemistry (Amsterdam, Netherlands)》2003,60(1-2):57-64
Effects of powerline frequency (50/60 Hz) electric and magnetic fields on the central nervous system may involve altered neurotransmitter release. This possibility was addressed by determining whether 60-Hz linearly polarized sinusoidal magnetic fields (MFs) alter the release of catecholamines from cultured bovine adrenal chromaffin cells, a well-characterized model of neural-type cells. Dishes of cells were placed in the center of each of two four-coil Merritt exposure systems that were enclosed within mu-metal chambers in matched incubators for simultaneous sham and MF exposure. Following 15-min MF exposure of the cells to flux densities of 0.01, 0.1, 1.0 or 2 mT, norepinephrine and epinephrine release were quantified by high-performance liquid chromatography (HPLC) coupled with electrochemical detection. No significant differences in the release of either norepinephrine or epinephrine were detected between sham-exposed cells and cells exposed to MFs in either the absence or presence of Bay K-8644 (2 microM) or dimethylphenylpiperazinium (DMPP, 10 microM). Consistent with these null findings is the lack of effect of MF exposure on calcium influx. We conclude that catecholamine release from chromaffin cells is not sensitive to 60-Hz MFs at magnetic flux densities in the 0.01-2 mT range. 相似文献
39.
Bell NS Sindel J Aldinger F Sigmund WM 《Journal of colloid and interface science》2002,254(2):296-305
Observations on the steric layers formed by the adsorption of low-molecular-weight polyacrylic acid (PAA) were taken using the colloidal probe method in an atomic force microscope. The effects of divalent barium ions and of monovalent potassium ions at varying concentrations were observed on the repulsive interaction profiles. High ionic concentrations screened double-layer forces to small distances, whereby the acting forces were reduced to steric interactions. De Gennes scaling theory was used to model the effect of electrolyte on an aqueous barium titanate system, which was stabilized with PAA. The brush model was found to represent the force curves better than the mushroom model. The collapse of PAA layers with increasing salt approximated a grafted polymer brush in monovalent electrolyte, but the addition of barium ions caused markedly less steric collapse. It is suggested that the formation of a Ba(2+)-PAA complex in the adsorbed layer increases its compressibility parameter. 相似文献
40.