Coarse-graining for fast dynamics of order parameters in the phase-field model.

In standard descriptions, the master equation can be obtained by coarse-graining with the application of the hypothesis of full local thermalization that is equivalent to the local thermodynamic equilibrium. By contrast, fast transformations proceed in the absence of local equilibrium and the master equation must be obtained with the absence of thermalization. In the present work, a non-Markovian master equation leading, in specific cases of relaxation to local thermodynamic equilibrium, to hyperbolic evolution equations for a binary alloy, is derived for a system with two order parameters. One of them is a conserved order parameter related to the atomistic composition, and the other one is a non-conserved order parameter, which is related to phase field. A microscopic basis for phenomenological phase-field models of fast phase transitions, when the transition is so fast that there is not sufficient time to achieve local thermalization between two successive elementary processes in the system, is provided. In a particular case, when the relaxation to local thermalization proceeds by the exponential law, the obtained coarse-grained equations are related to the hyperbolic phase-field model. The solution of the model equations is obtained to demonstrate non-equilibrium phenomenon of solute trapping which appears in rapid growth of dendritic crystals.This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'.

Coarse graining for the phase-field model of fast phase transitions.

Fast phase transitions under lack of local thermalization between successive elementary steps of the physical process are treated analytically. Non-Markovian master equations are derived for fast processes, which do not have enough time to reach energy or momentum thermalization during rapid phase change or freezing of a highly nonequilibrium system. These master equations provide a further physical basis for evolution and transport equations of the phase-field model used previously in the analyses of fast phase transitions.

Solute trapping in rapid solidification of a binary dilute system: a phase-field study.

The phase-field model of Echebarria, Folch, Karma, and Plapp [Phys. Rev. E 70, 061604 (2004)] is extended to the case of rapid solidification in which local nonequilibrium phenomena occur in the bulk phases and within the diffuse solid-liquid interface. Such an extension leads to the fully hyperbolic system of equations given by the atomic diffusion equation and the phase-field equation of motion. This model is applied to the problem of solute trapping, which is accompanied by the entrapment of solute atoms beyond chemical equilibrium by a rapidly moving interface. The model predicts the beginning of complete solute trapping and diffusionless solidification at a finite solidification velocity equal to the diffusion speed in bulk liquid.

Variational principles for thermal transport in nanosystems with heat slip flow.

Some years ago, Prigogine minimum entropy production principle was generalized by Lebon and Dauby to account for the nonlocal heat transport equation derived by Guyer and Krumhansl. Here, this criterion is extended to incorporate the effects of heat slip flow along the walls. This formulation is shown to be useful for the description of steady heat flow in nanosystems, where the heat slip flow plays a decisive role.

Robustness of the nonequilibrium entropy related to the Maxwell-Cattaneo heat equation.

The connection between the Maxwell-Cattaneo heat transport equation and a nonequilibrium entropy is examined through four different thermodynamic approaches, and it is shown that all of them lead to the same form of the nonequilibrium entropy. Furthermore, it is seen that this form is also consistent with three microscopic formalisms. This robustness underlines the consistency and relevance of the entropy.

Shear-induced shift of spinodal line in entangled polymer blends.

We study the shear-flow effects on phase separation of entangled polymer blends by incorporating into the chemical potential a nonequilibrium contribution due to the flow. The results are compared with those of a previous analysis by other authors which did not modify the chemical potential but used a different assumption for the stress tensor of the blend.

Breaking of equipartition in one-dimensional heat-conducting systems.

Using information-theoretical methods, we studied how energy equipartition is broken in one-dimensional systems under a heat flow composed of alternating particles of two different masses. The average energy stored in particles of different masses is seen to be different in both ideal gases and harmonic lattices.

Legendre transform in the thermodynamics of flowing polymer solutions.

We propose a Legendre transform linking two different choices of nonequilibrium variables (viscous pressure tensor and configuration tensor) in the thermodynamics of flowing polymer solutions. This may avoid some current confusions in the analysis of thermodynamic effects in polymer solutions under flow.

In vitro fertilization, gamete intrafallopian transfer and combined IVF-GIFT results: three-year experience at Chang Gung Memorial Hospital.

A review is presented summarizing the IVF-ET, GIFT and combined IVF-ET-GIFT experienced at Chang Gung Memorial Hospital. Since the building of an aseptic dust free laboratory next to the operation room, the clinical pregnancy rate has been 12.2% per embryo transfer in IVF-ET, 16.7% in the GIFT program and 30.0% in the combined IVF-GIFT program. The overall clinical pregnancy rate was 14.9%. The overall pregnancy rate appeared to be independent of the causes of infertility, be it tubal factor, endometriosis or unexplained infertility. It was lower in couples with male factor or combined factors. The different regimens for follicular stimulation were hMG-hCG, clomiphene-hMG-hCG and FSH-hMG-hCG. No one regimen showed a better pregnancy rate than the others. The methods of oocyte retrieval were laparascopy, laparotomy, transbladder ultrasound-guided, and transvaginal ultrasound-guided retrieval. There were 4.53 oocytes retrieved pertreatment cycle. The transvaginal ultrasoundguided oocyte retrieval has greatly simplified the procedures in the IVF-ET program. The patient selection was important not only for the indications but also for the methods of IVF-ET, GIET and combined IVF-GIFT.

A simple nonequilibrium thermodynamic description of some inhibitors of oxidative phosphorylation.

We propose a macroscopic description of some inhibitors of oxidative phosphorylation based on a simple modification of the phenomenological coefficients appearing in the constitutive equations of linear irreversible thermodynamics. In this theoretical model, we consider protonophores, some ATPase inactivators and some electron-chain inhibitors, and we provide quantitative expressions for their consequences on the protonmotive force, oxidation flux and phosphorylation flux as well as on heat generation.

Non-local thermodynamic effects and efficiency of oxidative phosphorylation.

A non-equilibrium thermodynamic model of oxidative phosphorylation is formulated, which allows us to take into account some non-local effects. In this way, we compute the influence of the tangential resistivity of the inner mitochondrial membrane to proton current, as well as that of the distance between active sites, on the stoichiometry and efficiency of energy conversion.