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81.
The enthalpy change on mixing solutions of methyl-substituted benzenesulfonic acids and their salts, with salts having a common
cation or anion, at constant ionic strength in mixtures of 1,4-dioxane with water, were measured at 25°C. The heat effects
of mixing solutions having a common anion increase almost linearly with the reciprocal value of the dielectric constant of
the solvent. The heat effects of mixing solutions having a common cation, which are all negative in water-rich solutions,
become endothermic after a certain value of the dielectric constant is passed. The results are discussed in terms of the solute-solvent
structural properties.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
82.
Electrodes containing glucose oxidase or xanthine oxidase adsorbed on modified glassy carbon electrodes or on conductive complexes, accumulate charge in the presence of substrates, the discharge of which gives the chronoamperometric stripping current. This current is 15 times higher than the stationary current after preconcentration for 8 min. A ten-fold increase in sensitivity of the determination of glucose or hypoxanthine is observed. The stripping current of electrodes based on cytochrome b2 adsorbed on a graphite electrode is 25 times higher than the stationary current. The electrode is useful for lactate determinations for more than 7 days. 相似文献
83.
84.
A new method has been developed for the determination of the isotope abundance ratios of deuterium, D, and oxygen-18, 18O, in water vapor (and water) using selected ion flow tube mass spectrometry (SIFT-MS). H3O+ ions are injected into the helium carrier gas where they associate with the H2O and HDO molecules in a sample of water introduced into the carrier gas. The D and 18O contents of the product cluster ions H8DO4+ and H9(18)OO3+ at m/e = 74 and 75, respectively, are determined by reference to the majority cluster ion H9O4+ at m/e = 73. Allowance is made for the contribution of the H8(17)OO3+ ions to the m/z = 74 ions. Absolute isotopic ratios are measured within seconds without the need for precalibration of the SIFT-MS instrument, currently to an accuracy of better than 2%. 相似文献
85.
G. Čík J. Lesný F. Šeršeň L. Szabo 《Journal of Radioanalytical and Nuclear Chemistry》1994,186(2):175-182
The influence of -radiation on the electric properties of Langmuir-Blodgett (LB) films of partially iodine-doped poly-(3-hexadecylthiophene) and stearic acid in interaction with selected environment-polluting gases has been studied. CO2, CO and NO2 increase the LB films conductivity and NO has a tendency to decrease the electric conductivity. The influence of -radiation was expressive onyl in the case of CO2, whereas NO2 brought about degradation of the conductive polymer. 相似文献
86.
Josef Šlapal 《Aequationes Mathematicae》1995,49(1):115-121
Summary For every ordinaln > 1 we define a categoryT
n
of topological spaces in ech's sense which is isomorphic to a category ofn-ary monorelational systems. We show that every categoryT
n
is an exponential supercategory of the categoryB of finitely generated topological spaces, which means that well-behaved function spacesG
H
can be defined inT
n
wheneverG B. 相似文献
87.
88.
An analysis is given of the behavior of an interface above a stepped substrate in the presence of an external pinning potential for the lattice solid-on-solid (SOS) interface model in 2D. Step-free energy including step-step interaction free energy is calculated, for large step separation. It is found it vanishes at temperatures lower thanT
w
(wetting transition temperature), which is different from the case having only one step on a substrate where, as it is well known, step-free energy vanishes at the wetting transition. 相似文献
89.
Summary The electrochemical reduction of the Fe(III) complexes with a series of substituted N,N-Ethylenebisacetonimines was investigated by cyclic voltammetry in acetonitrile solution at a platinum electrode. The substituent does not significantly influence the redox properties of the studied complexes. The symmetry of the redox orbital is responsible for the observed behaviour of the complexes.
Elektrochemisches Verhalten einer Reihe von Fe(III)-Komplexen mit vierzähnigen Schiffschen Basen als Liganden
Zusammenfassung Die elektrochemische Reduktion der Fe(III)-Komplexe einer Reihe von substituierten N,N-Ethylenbisacetoniminen wurde mittels cyclischer Voltammetrie in Acetonitril an einer Platinelektrode untersucht. Der Substituent beeinflußt die Redoxeigenschaften der untersuchten Komplexe nicht signifikant. Das beobachtete Verhalten der Komplexe wird von der Symmetrie des Redoxorbitals bestimmt.相似文献
90.
V. Hnatowicz J. Kvítek V. Švorčík V. Rybka V. Popok 《Czechoslovak Journal of Physics》1994,44(6):621-627
Samples of polyethylene (PE) loaded with carbon black up to 8 wt.% and implanted with 150 keV Sb+ ions to the doses from 2×1013–2×1015 cm–2 were studied using standard Rutherford Back Scattering (RBS) technique. On the PE samples implanted to the doses above 2×1014 cm–2, a considerable surface carbonization is observed. The measured parameters of the Sb depth profile are compared with theoretical TRIM estimations. The projected range is by 25% lower than the theoretical one and the range straggling is about twice of that predicted. The differences are explained by stepwise polymer degradation during the ion bombardment. Strong oxidation of the ion implanted polymers is also observed. The oxygen depth profiles from the sample surface up to the depth comparable with Sb+ ion range evolve from nearly uniform one for low ion doses to highly non-uniform one for doses above 1×1015 cm–2. The total oxygen content in the sample surface layer 300 nm thick reaches a maximum for the doses of (1–2)×1014 cm–2.On leave from Belorussian State University, 220050 Minsk, Belarus.The authors thank the member of electrostatic accelerator group at INP for help during RBS measurements. The work was partly (V.H. and J.K.) supported by the Internal Grant Agency of the Academy of Sciences of Czech Republic under the grant No. 14805 and by the Internal Grant Agency of the Ministry of Education of Czech Republic under the grant No. 1002 (V.., V.R., V.H. and J.K.). In the final stage, the work was also supported by the Grant Agency of Czech Republic under the grant No. 202/93/0121. 相似文献