HYDRODYNAMIC ASPECTS OF THE AMORPHOUS ALLOY RIBBON FABRICATION

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MECHANICAL AND CURRENT OSCILLATIONS IN CORRODING ELECTRODES

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GREENS FUNCTION THEORY OF ANISOTROPIC HEISENBERG-FERROMAGNET

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The quartz crystal microbalance: a tool for probing viscous/viscoelastic properties of thin films

Techniques based upon the electrical response of the quartz crystal microbalance (QCM) have been widely used in laboratories as routine tools. In this article we present and discuss applications of the QCM (or its variant, the electrochemical quartz crystal microbalance, EQCM) to the viscoelastic characterization of films. It is pointed out that correlations between the motion of quartz crystal and contacting films and overlayers as well as the influence of the electronic circuit on the electric state of the whole system are of fundamental importance in interpreting the results.28440541

Sodium dodecyl sulfate adsorbed monolayers on gold electrodes

Self-assembled aggregates of amphiphilic surfactant molecules formed on solid surfaces are similar to biological membranes. To understand the formation mechanism of these aggregates, we have studied the formation of self-organized monolayers from low-concentration sodium dodecyl sulfate (SDS) aqueous solutions (concentration below the critical micelle concentration) on gold surfaces. The study has been carried out by using simultaneously quartz crystal microbalance (QCM) and open circuit potential measurements in situ. We have developed a model which explains the variation of the QCM frequency and open circuit potential following SDS additions to water. The dominant growth mechanism during the major part of film formation was demonstrated to be surface diffusion of surfactant molecules.2384383438

A HYDRODYNAMIC APPROACH TO THE OSMOSEDIMENTATION PROCESS

In this work, an analysis of the osmosedimentation process is presented. The purpose is to study the influence of the characteristic parameters of the system on the sedimentation rate. The interplay between diffusion and macroscopic fluid motion is taken into account by using the equations relating the respective fluxes and forces. Based on the mass and momentum equations with the appropriate boundary and initial conditions a model for the osmosedimentation process is proposed for a viscous binary mixture. By solving the differential equations with the help of a finite difference numerical method it is possible to obtain (1) a hydrodynamic description of the fluid circulation in each half-cell and (2) some useful information on the influence of the diffusion coefficient, membrane permeability and cell width on the solute sedimentation process.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.19215716

The transient regime in Frohlich's condensation phenomenon in biosystems

We consider the emergence of the so-called Frohlich's effect in a biosystem, a phenomenon consisting of the condensation of excitations in the polar vibrational modes lying at the bottom of these modes' frequency spectrum. This complex behavior of the system, which seems to have relevance in bioenergetics, may arise in open biomaterial, which is governed by nonlinear kinetic equations, and when under the action of a pumping source of metabolic energy. We analyze here in detail the dynamics of (i) the transient stage before the establishment of a steady state and (ii) the relaxation to the original thermodynamic equilibrium state after the pumping source is turned off. (C) 1997 John Wiley & Sons, Inc.62436337

Statistical-mechanical foundations for a generalized thermodynamics of dissipative processes

A statistical-mechanical formalism for nonequilibrium systems, namely the nonequilibrium statistical operator method, provides microscopic foundations for a generalized thermodynamics of dissipative processes. This formalism is based on a unifying variational approach that is considered to be encompassed in Jaynes' Predictive Statistical Mechanics and principle of maximization of the statistical-informational entropy. Within the framework of the statistical thermodynamics that follows from the method, we demonstrate the existence of generalized forms of the theorem of minimum (informational) entropy production, the criterion for evolution, and the thermodynamic (in)stability criterion. The formalism is not restricted to local equilibrium but, in principle, to general conditions (its complete domain of validity is not yet fully determined). A H-theorem associated to the formalism is presented in the form of an increase of the informational entropy along the evolution of the system. Some of the results are illustrated in an application to the study of a model for a photoexcited direct-gap semiconductor.45113

LO - PHONON INSTABILITY IN THE FREE-CARRIER ABSORPTION IN SEMICONDUCTORS UNDER STRONG MAGNETIC-FIELDS

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