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31.
Extraction distribution of microamounts of strontium in the water-CsCl-15-crown-5 (15C5,L)-nitrobenzene-cesium dicarbollylcobaltate system has been investigated. The equilibrium data have been explained assuming that the CsL+, CsL2
+ and SrL2
2+ complexes are extracted into the organic phase. The values of extraction and stability constants of the species in nitrobenzene saturated with water have been determined. 相似文献
32.
The mechanism of palladium extraction by trilaurylamine and trilaurylmethylammonium nitrate from nitric acid solutions was studied. The composition of the extracted compounds was determined by the Job method as well as by organic phase saturation. Both reagents were found to extract palladium as Am2Pd/NO3/4 /Am=ammonium cation/. 相似文献
33.
Joseph Schwarz Detlef Schrder Helmut Schwarz Christoph Heinemann Jan Hruk 《Helvetica chimica acta》1996,79(4):1110-1120
State-of-the-art ab initio studies demonstrate that the reaction Pd+ + CH3I → PdCH2I+ + H. is endothermic by ca. 20 kcal/mol, which translates into a bond dissociation energy (BDE) of ca. 83 kcal/mol for the Pd+? CH2I bond. This figure is in agreement with an experimental bracket of 68 kcal/mol < BDE(Pd+? CH2I) < 92 kcal/mol. Based on these findings, the previously studied Pd+/CH3I system was re-investigated, and double-resonance experiments demonstrate that the formation of PdCH2I+ occurs stepwise via PdCH as a reactive intermediate. Further, ion/molecule reactions of PdCH2I+ with unsaturated hydrocarbons are studied, which reveal the formation of carbon–carbon bonds in the gas phase. 相似文献
34.
As long-term exposure to exhaled halothane can be a cause of hepatitis and/or damage to the liver, the determination of halothane in blood is important in clinical practice. Gas chromatographic headspace analysis appears to be the most successful method. In the present study, two methods of quantitative evaluation of the analysis were compared by statistical treatment and direct comparison. The absolute calibration method was found to be unsuitable since it yields entirely unreliable results. This is due to different contents of lipoid and other components in the blood of the normal population, and this influences the vapour phase concentration of halothane and results in different values for the slopes of calibration curves for different blood samples. The standard addition method gives reliable results. 相似文献
35.
Ampholytic membranes were synthesized by copolymerizing (2-hydroxyethyl)methacrylate as the hydrophilic component, methacrylic acid and (N,N-diethylaminoethyl)methacrylate as ionogenic components (both ionogenic monomers in amounts 2.5 mol% or 10 mol%), and ethylenedimethacrylate as the crosslinking agent (3,5 or 10 mol%). The effects of pH on the swelling and membrane potentials of the membranes were investigated. The dependence of the membrane potentials on pH is characterized by the position of the isoelectric point and by the slope of the straight part of the dependence. This slope reflects the attained degree of ideality of the membrane. By varying the degree of cross linking and the content of ionogenic components, it is possible to vary the pH-dependent response of the membranes. 相似文献
36.
A. Küçükönder Ö. Sö?üt F. Sümbül E. Büyükkasap 《Journal of Radioanalytical and Nuclear Chemistry》2006,270(3):695-698
Summary Kb/Ka X-ray intensity ratios of some K and Ca compounds were studied. The samples were excited with 59.5 keV g-rays emitted
from 75 mCi 241Am radioisotope source and characteristic K X-ray from the samples were counted by means of an Si(Li) detector which has a
resolution 155 eV at 5.9 keV. We found that Kb/Ka X-ray intensity ratios are changed by chemical effect for different K and
Ca compounds. The experimental values were compared with the calculated theoretical values for elemental K and Ca. 相似文献
37.
From extraction experiments with 133Ba as a tracer, the extraction constant corresponding to the equilibrium Ba2+(aq) + 2A-(aq) + 2L(nb) BaL2
2+(nb) + 2A-(nb) in the two-phase water-nitrobenzene system (A- = picrate, L = benzo-15-crown-5; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K
ex (BaL2
2+, 2A-) = 5.7. Furthermore, the stability constant of the benzo-15-crown-5 - barium complex in nitrobenzene saturated with water was calculated: log bnb (BaL2
2+) = 14.6. 相似文献
38.
Oxides Fe2–x
Cr
x
O3 (corundum-type) and Fe3–y
,Cr
y
O4 (spinel-type) were studied by transmission IR spectroscopy. The wavenumbers corresponding to characteristic absorption maxima depend linearly on the composition of both types of solid solutions, i.e. onx andy. The results show that IR spectroscopy can contribute to the analysis of solid solutions of iron and chromium oxides and of the oxidation products of Fe-Cr alloys.The authors are indebted to Ing. P. Holba for the preparation of synthetic oxide samples. The cooperation of Yu. Borodkin and I. Zuika (Riga) who made the measurements in the far IR region is gratefully acknowledged. 相似文献
39.
We propose a model for the production of extra (additional) lepton pairs in deep inelastic lepton-hadron scattering, e+e– annihilation and large pT processes. Extra lepton pairs are supposed to be originated by annihilations of quarks and antiquarks created during the space-time evolution of quark initiated jets. This mechanism yields predominantly dileptons with rather low masses. Predictions following from the model are compared with the recent data on trimuon production in neutrino-nucleon interactions. It is also suggested that internal hard processes can lead to dileptons with both small and large masses. The latter mechanism has rather small cross section but it is particularly interesting from the point of view of the simple quark-parton model.Dedicated to Academician Václav Votruba on the occasion of his seventieth birthday. 相似文献
40.
The induction period-supercooling dependence was measured in calcium nitrate-water system within the concentration range 1.5–23 mol% of Ca(II). It was found that the behaviour of the system may be described by the equations for transformation kinetics with the use of classical theory of homogeneous nucleation in glasses. From the experimental data values of interfacial tension of the liquid-solid interface were calculated and correlated qualitatively with the observed stability of the studied system with respect to crystallization. 相似文献