Inflationary Brans-Dicke universe andG

In a recent paper, Mathiazhagan and Johri reduced the field equations for an isotropic, homogeneous, and almost flat universe with a constant vacuum-energy density by Brans-Dicke theory to a pair of coupled differential equations. They also obtained a particular solution of these equations. Further, they used this particular solution of the equations to estimate the value of the gravitational constant. Here we obtain the complete set of solutions of the above-mentioned coupled differential equations and improved the estimate of Mathiazhagan and Johri of the gravitational constant.     

Diffusion-annihilation and the kinetics of the Ising model in one dimension

The relationship between the one-dimensional kinetic Ising model at zero temperature and diffusion-annihilation in one dimension is studied. Explicit asymptotic results for the average domain size, average magnetization squared, and pair-correlation function are derived for the Ising model, for arbitrary initial magnetization. For the case of zero initial magnetization (m ₀=0, a number of recent exact results for diffusion-annihilation with random initial conditions are obtained. However, for the casem ₀ not equal to zero, the asymptotic behavior turns out to be different from diffusion-annihilation with random initial conditions and at a finite density. In addition, in contrast to the case of diffusion-annihilation, the domain-size distribution scaling functionh(x) is found to depend nontrivially on the initial magnetization. The origin of these differences is clarified and the existence of nontrivial correlations in the initial wall distribution for finite initial magnetization is found to be responsible for these differences. Results of Monte Carlo simulations for the domain size distribution function for different initial magnetizations are also presented.This paper is dedicated to George Weiss on the occasion of his 60th birthday.     

Thermopower anisotropy in magnetic films of Co and Ni plated in presence of an external magnetic induction

Electroplated films of cobalt and nickel were grown on copper substrate both in absence and presence of external magnetic induction ranging from 25 to 72 gauss. The latter films showed a magnetic behaviour and an anisotropy in thermopower with respect to the direction of magnetisation.     

A counter-example for the Bezout equation in the Hardy classH p

Leff ₁,f ₂ be bounded holomorphic functions in the unit disc of the complex plane ℂ. Using a recent result of S. Treil about estimates in the corona theorem, we strengthen a counterexample given by Amar, Bruna and Nicolau to the existence of functionsg ₁,g ₂ in the Hardy spaceH ^p ( ) verifying the Bezout equationf ₁ g ₁+f ₂ g ₂=1.     

Extraction and transport of chromium(VI) through a bulk liquid membrane containing triphenylphosphine

The solvent extraction of chromium(VI) in chloroform, dichloromethane, dichloroethane and its transport through a chloroformic bulk liquid membrane from sulphuric acid solutions with the neutral extractant triphenylphosphine (TPP) were studied. It was highlighted that the TPP extractant is an interesting complexing and efficient carrier for transport of chromium(VI) as [(HTPP)HCr2O7] complex from a 2M sulphuric acid solutions. It has a high ability to concentrate the chromium(VI) in the receiving phase according to the Donnan equilibrium. The co-extraction and the co-transport of sulphuric acid is very low and has no effect on the transport efficiency. The transport rate depends mainly on the initial concentration of the extractant.     

Visualizing flow vortices inside a single levitated drop

The internal flow dynamics in single liquid drops, kept in place through levitation by a counterflowing continuous fluid phase in a suitably designed glass cell, is investigated by PFG NMR techniques. The positional stability of the drops was confirmed from series of one-dimensional profiles and was found to be below the spatial resolution of the experiment. Velocity distribution functions (propagators) along all three coordinates were obtained and demonstrated the long-time stability of the internal dynamics in terms of the velocity magnitudes occurring in the systems. Finally, velocity imaging was applied to visualize the internal vortex patterns in the drops either as projections onto different planes or within thin slices of selected orientations. Two different fluid systems were investigated in order to cover the principal cases of rigid and mobile interfaces. Different fast velocity imaging techniques were employed for monitoring the vastly differing velocity ranges of both cases, and the high sensitivity of the internal three-dimensional motion to the cell geometry is demonstrated.     

Sugar-cellulose composites V. The mechanism of fiber strengthening by cell wall incorporation of sugars

The incorporation of sucrose or some other disaccharides (cellobiose, -lactose or trehalose) into the cell wall of pulp fibers increases the tearing resistance of the resultant sugar-containing paper relative to that of its sugar-free counterpart, but only when the fiber is well-refined. Maltose and -lactose do not exhibit this effect. By the use of a high cellulose pulp the increase is shown not to be due to the presence of hemicelluloses. Differential scanning calorimetry indicates that the interaction between the sucrose molecules and the cellulosic fibers changes and becomes more uniform as the fibers are refined. Although the azo dye Congo red bonds strongly with cellulose the analogous reaction with disaccharides and cyclodextrins, established spectrophotometrically, could not be used to predict the physical outcome of the interactions with added disaccharides or cyclodextrins. From a consideration of the stereochemistry of the impregnant disaccharides the augmentation of the fiber strength is attributed to the interlamellar hydrogen bonding of impregnant molecules having hydroxy endgroups in the cis conformation and separated by about 10Å. The incorporation of cyclodextrins further demonstrates that the conformation and the separation distance between the OH groups located in the interlamellar sugar molecule play an important role in strengthening the sugar-impregnated fiber and in augmenting the tearing resistance of sugar-containing papers.     

On a hierarchy of models for electrical conduction in biological tissues

In this paper we derive a hierarchy of models for electrical conduction in a biological tissue, which is represented by a periodic array of period ε of conducting phases surrounded by dielectric shells of thickness εη included in a conductive matrix. Such a hierarchy will be obtained from the Maxwell equations by means of a concentration process η → 0, followed by a homogenization limit with respect to ε. These models are then compared with regard to their physical meaning and mathematical issues. Copyright © 2005 John Wiley & Sons, Ltd.