ISSN:0005-9021    

DOI:10.1002/bbpc.199500001

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.199500002

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractSmall colloidal particles *) and clusters *) of semiconductors and metals exhibit unusual properties and may be considered as a new physico‐chemical dimension between the molecules and the bulk materials. The surface to volume ratio is extremely large; small‐particle research therefore constitutes a combination of solid state and surface science. The electronic properties of the particles (light absorption, colour, fluorescence, catalytic and photocatalytic activity, electrochemistry etc.) depend on particle size. Chemical surface modification affects these properties and allows one to prepare new nano‐structures in solution, in layers, and in the crystalline state. No attempt is made in the present article to review the whole field, but to describe this new branch of colloid chemistry by focussing on a few selected t

ISSN:0005-9021    

DOI:10.1002/bbpc.199500003

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractIsothermal internal reactions of the type A + B = AB taking place in a crystal matrix C are studied experimentally. The matrix crystal C is NiO, A = CaO, B = TiO2(NiTiO3) and the reaction product AB is the perovskite CaTiO3. Both the morphology of the reaction product and the kinetics of its formation have been investigated and are discussed in the light of a previous theoretical study. In addition, chemical diffusivities of Ca‐ and Ti‐ions in the NiO‐matrix are deter

ISSN:0005-9021    

DOI:10.1002/bbpc.199500004

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe formal analysis of the coupling between diffusional matter and heat transport shows that diffusional matter fluxes are driven by both temperature and composition gradients, and that matter fluxes are always connected with heat fluxes. An important concept in the description of this coupling is the introduction of so‐called heats of transport. The heats of transport, being combinations of phenomenological transport coefficients, denote the relation between individual matter fluxes and related heat fluxes for isothermal systems. For the case of mixed ionic/electronic conducting binary compounds with narrow ranges of homogeneity, A1+δXV, a new experiment for the determination of the reduced heat of transport of metal A is proposed and discussed with respect to a possible realization. The experiment is based on the direct measurement of the flux of the metal component in a temperature gradient, under special boundary conditions for the composition of the sample, and gives direct access to the (reduced) heat of transport,Q*A. Alternative ways for the determination of the heat of transport are summarized and compared with the proposed experime

ISSN:0005-9021    

DOI:10.1002/bbpc.199500005

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe experimental determination of the (reduced) heat of transport of silver,Q*Ag, in β‐Ag2+δS by the direct measurement of the silver flux in a given temperature gradient, under the condition of equal composition at the ends of the crystalline sample, is reported. The measurement is based on the application of galvanic cells for the simultaneous control and measurement of both the silver flux and composition. A set of data for the heat of transport of silver is determined for 210°C

ISSN:0005-9021    

DOI:10.1002/bbpc.199500006

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractMixtures of carbon dioxide and krypton gases were codeposited from the gas phase. The resulting solids were studied by X‐ray powder diffraction and IR absorption. Molecular dynamics simulation was applied to the system.Under equilibrium conditions phase separation occurs. If diffusion is suppressed, solids with extremely short coherence lengths were found in the concentration range of 30–70 mol% Kr. The simulation allows to reproduce this disorder. It is due to internal distortions rather than to grain size effects. The addition of krypton reduces the quadrupole‐quadrupole interaction. This leads to orientational and to centre‐of‐gravity disorder. The properties of CO2: Kr are discussed in comparison with the well known quadrupole glass N2: Ar. For the molecular dynamics simulation a flexible model of the CO2was adopted. This allowed to reproduce the influence of the local environment on the band shape of the bendi

ISSN:0005-9021    

DOI:10.1002/bbpc.199500007

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractMonte Carlo modeling was utilized for determining the tracer and chemical surface diffusion coefficients of adsorbates. Simulations were carried out on a square array of 64×64 lattice sites applying periodic boundary conditions. In order to analyze the effects of steps on surface diffusion different atomistic models of steps were introduced. For the simplest model steps were assumed to affect the site energies of a single row of lattice sites located on the down‐side of the step. Another set of simulations was performed for steps affecting the site energies on the up‐side of the step as well. For attractive interactions between adsorbates and step sites surface diffusion is slowed down with respect to the noninteracting Langmuir gas on a plain surface. Steps cause diffusion to be anisotropic as crossing of steps costs an extra activation energy. Additional calculations are performed in order to analyze the effect of the saddle points of the periodic potential on surface diffu

ISSN:0005-9021    

DOI:10.1002/bbpc.199500008

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractA lipid bilayer of glycerolmonoleate is spanned over a microscopic shallow groove etched into the 110 surface of a silicon wafer and insulated by thermal oxidation. The conductance of the bimolecular membrane is modulated by gramicidin. The voltage profile in the groove is recorded by a set of Ag/AgCl electrodes which are integrated into the bottom of the groove. It is used to determine the distribution of ion channels along the membrane on the basis of Kelvin's cable equation.

ISSN:0005-9021    

DOI:10.1002/bbpc.199500009

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY

摘要:

AbstractThe relationship between the gel‐liquid ctystal phase transition temperature (tm) of dipalmitoylphosphatidylcholine (DPPC) liposomes and the protonation degree of the lecithin phosphodiester moiety, has been studied. A linear function is obtained when the phase transition temperatures of liposomes determined by 90° light scattering variation at different bulk pH values, are plotted against the corresponding protonation degrees calculated either as described previously from thepotentiality for tmelevationof DPPC liposomes using stearylamine as a probe [Ber. Bunsenges. Phys. Chem.95, 1669 (1991)] or from combination of Boltzmann, Henderson‐Hasselbach and Gouy‐Chapman equations, by assuming an interfacial intrinsic pKof 4 for the phosphodiester group and an average cross section molecular area of 45 or 65 Å2for the phospholipid. The approach described here, which supplements the above‐mentioned previous work, allows to predict that thetmof fully protonated DPPC in liposomes should be in the range from 59.2 to 62.9°C, the variation being dependent on the procedure used to calculate the protonat

ISSN:0005-9021    

DOI:10.1002/bbpc.199500010

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1995

数据来源: WILEY