ISSN:0005-9021    

DOI:10.1002/bbpc.19850890502

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

年代:1985

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890503

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

年代:1985

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890504

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

年代:1985

数据来源: WILEY

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890505

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe electronic structure of crystalline Li12Si7has been studied by means of crystal orbital (CO) calculations based on the tight‐binding formalism. The computational basis for this investigation is a semiempirical INDO model derived in the framework of the SCF HF approximation. The Li12Si7system is divided into two substructures containing one‐dimensional infinite columns Li6Si5and Li12Si4, respectively, which are employed as stacking units in the tight‐binding calculations. The band structure properties, density of states profiles, charge distributions and the nature of the various diatomic interactions for both substructures are discussed. In order to understand the nature of Si‐Si, Li‐Si and Li‐Li interactions we have decomposed the various diatomic potentials into elements of physical significance, i.e. covalent resonance energies, exchange parameters as well as electrostatic potentials. The one‐dimensionality of the Li6Si5unit is partially the result of covalent Li‐Si interactions in the direction of the stacking axis. The nature and strength of the Li‐Si coupling depends strongly on the conformation of the 1D arrangement. The electronic structure (i.e. localization properties of the CO microstates) in the second fragment Li12Si4differs drastically from the one‐electron properties encountered in the Li6Si5system. The identity of the orbitals of the twelve Li and four Si atoms is significantly perturbed in the 1D fragments, CO microstates are predicted that contain nearly comparable admixtures from

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890506

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

年代:1985

数据来源: WILEY

摘要:

AbstractCondensation of nitrogen carried in helium was studied in expansion waves of a cryogenic shock tube operated at 77.4 K. Condensation onset was detected by laser light scattering in conjunction with piezoelectric pressure measurements. In contrast to most of the previous studies employing supersonic nozzles or free jet expansions, the shock tube experiments showed condensation at supersaturated states close to phase equilibrium having temperatures from 66 K to 57 K and nitrogen partial pressures from 230 torr to 45 torr. The differences in condensation onset presumably caused by the different experimental conditions such as carrier gas concentrations, cooling rates and supply temperatures cannot be explained on the basis of conventional nucleation theories. It is instead possible to relate these differences qualitatively to the molecular kinetics of nitrogen microcluster formation.

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890507

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

年代:1985

数据来源: WILEY

摘要:

AbstractVolumetric emission coefficients of pool fires are determined from photograms and infrared radiance distributions of fires. The volumetric emission coefficients have maximum values of 0.12W/(cm3sr) for an n‐hexane pool fire. A simplified model, based on the assumptions of the optically thin limit and non‐uniformities in temperature and species concentrations is used to compute the axisymmetric distribution of the volumetric emission coefficients from sampling probe measurements of stable species and temperatu

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890508

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

年代:1985

数据来源: WILEY

摘要:

AbstractA special resonance circuit technique is described which can be used to measure even very small changes of the dielectric constant of a poorly conducting liquid as they may be caused by a strong electric field. This is applied to an octanolic solution of trichotoxin A40, an antibiotic peptide which is known to form electrically sensitive pores in bilayer membranes. Experimental results at about 0.6 and 11 MHz, respectively, are reported and discussed in terms of a theoretical analysis based on the classical Debye‐Onsager approach. In particular, the frequency dependence of the normal dielectric saturation has been calculated in order to correct for the finite rate of dipolar orientation. It turns out that in addition to the normal dielectric field effect an anomalous effect occurs. The latter apparently arises from concentration changes of different dipolar species. These changes are attributed to a field induced displacement of the aggregational equilibrium which exists in the syste

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890509

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

年代:1985

数据来源: WILEY

摘要:

AbstractIntermolecular parts of thex→rFourier transform of the coherent scattering cross section of five isotopically different formic acids are presented and from these data four weighted sums of intermolecular atom‐atom pair distribution functions are determined. Very limited informations about the two (equal) hydrogen‐hydrogen correlation function is also given. From proton magnetic relaxation data available in the literature two possible pair configurations were proposed. From these pairs and one additional one the corresponding sets of intermolecular atomic distances were determined and examined whether these sets lead to agreement with the weighted sums of correlation functions. Agreement was found to be best for a pair with O=C vectors being close to but not exactly parallel, it was concluded that this is the correct molecular pair configuration of maximum occurrence probab

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890510

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

年代:1985

数据来源: WILEY

摘要:

AbstractLong‐ranged structural correlations develop within the random, transient hydrogen‐bonded network of liquid water at low temperatures and cause characteristic anomalies in the physical properties of supercooled water. Hydrostatic pressure suppresses these anomalies and turns liquid water into a normal viscous liquid. The addition of salt‐is considered another mean to suppress long‐ranged density‐density correlations, hence the pressure‐, temperature and composition dependence of deuterium (2H) spin‐lattice relaxation times (T1) is reported for supercooled LiCl‐D2O solutions over a large range of concentration (c≤ 11 molal), pressure (p≤ 226 MPa) and temperature (180 K ≤ T ≤ 283 K). The anomalous pressure dependence of the spin‐lattice relaxation times becomes weaker with inc

ISSN:0005-9021    

DOI:10.1002/bbpc.19850890511

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

年代:1985

数据来源: WILEY