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61.
Detailed experimental and theoretical investigations, based on direct excite and probe experiments and on line-shape analysis, on the influence of many-body interaction, polar interaction, and transport effects on the energetic position and shape of the electron-hole plasma (EHP) emmission are reported. The comparison of optical EHP properties in an indirect (GaP) and a direct (CdTe) semiconductor of similar polarity offers the possibility of a separation of drift effects and polar effects with respect to band-gap renormalization. Direct evidence of a fast plasma drift in CdTe is obtained by thickness sensitive optical excite and probe experiments. 相似文献
62.
The nonlinear rheological version of our barrier hopping theory for particle-polymer suspensions and gels has been employed to study the effect of steady shear and constant stress on the alpha relaxation time, yielding process, viscosity, and non-Newtonian flow curves. The role of particle volume fraction, polymer-particle size asymmetry ratio, and polymer concentration have been systematically explored. The dynamic yield stress decreases in a polymer-concentration- and volume-fraction-dependent manner that can be described as apparent power laws with effective exponents that monotonically increase with observation time. Stress- or shear-induced thinning of the viscosity becomes more abrupt with increasing magnitude of the quiescent viscosity. Flow curves show an intermediate shear rate dependence of an effective power-law form, becoming more solidlike with increasing depletion attraction. The influence of polymer concentration, particle volume fraction, and polymer-particle size asymmetry ratio on all properties is controlled to a first approximation by how far the system is from the gelation boundary of ideal mode-coupling theory (MCT). This emphasizes the importance of the MCT nonergodicity transition despite its ultimate destruction by activated barrier hopping processes. Comparison of the theoretical results with limited experimental studies is encouraging. 相似文献
63.
Andreas Schweizer 《Transactions of the American Mathematical Society》2005,357(3):1047-1059
We study the extension generated by the -coordinates of the -torsion points of an elliptic curve over a function field of characteristic . If is a non-isotrivial elliptic surface in characteristic with a -torsion section, then for 11$"> our results imply restrictions on the genus, the gonality, and the -rank of the base curve , whereas for such a surface can be constructed over any base curve . We also describe explicitly all occurring in the cases where the surface is rational or or the base curve is rational, elliptic or hyperelliptic.
64.
65.
On the theory of collective motion in nuclei. III. From Hamiltonian dynamics to vortex-free fluidity
It is assumed that the Hamiltonian for collective motion in nuclei is invariant under the orthogonal group O(n, ). For degenerate orbits in phase space it is shown that the classical Hamiltonian equations reduce to the equations of a vortex-free fluid with a velocity field determined by independent equations of motion. 相似文献
66.
B. Barbara B. Dieny A. Liénard J.P. Rebouillat B. Boucher J. Schweizer 《Solid State Communications》1985,55(5):463-467
We provide a coherent interpretation of early small angle scattering experiments performed by some of us on amorphous ErCo2 [9]. At low temperature the zero field transverse spin-spin correlation function is found to fit a simple exponential for large length scales (l >lc), supporting the lower critical dimensionality dc=4. For shorter length scales (l<lc) the correlation function is of the Ornstein-Zernike type. These results are physically understood in terms of the breaking of ferromagnetism into Imry and Ma domains.A further physical interpretation leads us to consider the localization of ferromagnetic spin waves within Imry and Ma domains in zero field, and their delocalization by application of an external field. 相似文献
67.
Schweizer E Hoffmann-Röder A Olsen JA Seiler P Obst-Sander U Wagner B Kansy M Banner DW Diederich F 《Organic & biomolecular chemistry》2006,4(12):2364-2375
Two series of tricyclic inhibitors of the serine protease thrombin, imides (+/-)-1-(+/-)-8 and lactams (+/-)-9-(+/-)-13, were analysed to evaluate contributions of orthogonal multipolar interactions with the backbone C=O moiety of Asn98 to the free enthalpy of protein-ligand complexation. The lactam derivatives are much more potent and more selective inhibitors (K(i) values between 0.065 and 0.005 microM, selectivity for thrombin over trypsin between 361- and 1609-fold) than the imide compounds (Ki values between 0.057 and 23.7 microM, selectivity for thrombin over trypsin between 3- and 67-fold). The increase in potency and selectivity is explained by the favorable occupancy of the P-pocket of thrombin by the additional isopropyl substituent in the lactam derivatives. The nature of the substituent on the benzyl ring filling the D pocket strongly influences binding potency in the imide series, with Ki values increasing in the sequence: F < OCH2O < Cl < H < OMe < OH < N(pyr)< Br. This sequence can be explained by both steric fit and the occurrence of orthogonal multipolar interactions with the backbone C[double bond, length as m-dash]O moiety of Asn98. In contrast, the substituent on the benzyl ring hardly affects the ligand potency in the lactam series. This discrepancy was clarified by the comparison of X-ray structures solved for co-crystals of thrombin with imide and lactam ligands. Whereas the benzyl substituents in the imide inhibitors are sufficiently close (< or =3.5 Angstroms) to the C=O group of Asn98 to allow for attractive orthogonal multipolar interactions, the distances in the lactam series are too large (> or =4 Angstroms) for attractive dipolar contacts to be effective. 相似文献
68.
Weiss ME Fischer DF Xin ZQ Jautze S Schweizer WB Peters R 《Angewandte Chemie (International ed. in English)》2006,45(34):5694-5698
69.
The isothermal form of Reynolds fluid film equation is used to predict the pressure generation in hydrodynamic journal bearings if temperature effects are neglected. Often, however, temperature effects may be important and cannot be neglected, because oil viscosity significantly varies with temperature. Also, thermal expansion of journal shaft and bearing housing must be taken into account since the bearing clearance changes with increasing temperature. Hence, the Reynolds pressure field equation, the energy equation for the fluid film and the heat transfer equations for journal and bearing housing have to be solved simultaneously. The coupled thermo-hydrodynamic fluid flow problem is mathematically defined by a system of nonlinear integro-differential equations. The governing equations are discretized and solved by a finite element approach. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
70.
The catalyst layer in a fuel cell can be described with a system of reaction diffusion eq uations for the oxygen concentration and the protonic overpotential. The Tafel law gives an exponential expression for the reaction rate, and the Tafel slope is a coefficient in this law. We present a rigorous thin layer analysis for two reaction regimes. In the case of thin catalyst layers and bounded potentials, the original Tafel law enters as an effective boundary condition. Instead, in the case of large protonic overpotentials, we derive an exponential law that contains the doubled Tafel slope. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献