Hermite–Padé approximation approach to shapes of rotating drops

This paper is devoted to the equilibrium shapes of rotating liquid drops. Families of axisymmetric shapes are found using a perturbation technique for the governing nonlinear equation. Bifurcation and turning points are located by applying a special type of Hermite–Padé approximation.     

Marches aléatoires sur certains groupes unimodulaires p-adiques

We give central and off-diagonal estimates for the transition kernels corresponding to simple random walks on certain unimodular solvable p-adic groups. To cite this article: S. Mustapha, C. R. Acad. Sci. Paris, Ser. I 340 (2005).     

Two-dimensional dopant profiling of silicon with submicron resolution using near field optics on silicon/electrolyte contacts

We demonstrate the possibility to use near field optics to perform two-dimensional dopant profiling on silicon surface, with deep submicron spatial resolution. The sample surface is contacted by an aqueous electrolyte giving a reverse biased junction that is illuminated by a subwavelength optical source, in near filed conditions. A staircase calibration structure was used with several boron-doped layers with either 4 μm or 0.4 μm thickness and doping between 10¹⁷ and 10²⁰ at/cm³. Measurements were performed on the sample cross section. It is shown that photocurrent surface mapping shows up the doped areas with a lateral resolution better than 100 nm.     

Synthesis and Characterization of 2,2-Biimidazole Complexes of Oxocations of Molybdenum (VI,V) and Uranium(VI)

Abstract

2,2′-Biimidazole complexes of MoO₂ ⁺², MoO₂ ⁺ and UO₂ ⁺² have been prepared and characterized by elemental analysis, conductance; and ¹H NMR, IR and electronic spectra. Two types of complexes have been identified. Those obtained from slightly acidic solutions have the formulae MoO₂ (H₂bim)Cl₂.2H₂O 1, UO₂(H₂bim) (Ac)₂ 2 and UO₂(H₂bim)Cl₂.2H₂O 3; whereas those from alkaline solutions have the formulae Mo₂O₄(Hbim)₂.2H₂O 4, and MO₂(Hbim)₂ (M = Mo(VI) 5, U(VI) 6). The infrared spectra of these complexes show characteristic biimidazole frequencies in the 3200–2500, 1550–1000 and 750 cm^?1 regions as well as metal oxygen double bonds in the 900 cm^?1 region. The stoichiometries of the acetate complex has been confirmed from ¹H NMR signal ratios of bimidazole to acetate protons at 7.3 and 2.3 ppm, respectively. The electronic spectrum of molybdenum(V) complex showed d-d transition band at ?13,500 cm^?1 in accord with that reported for copper (d⁹) imidazole complexes; as well as peaks due to charge transfer bands at 30,000–26,000 cm^?1 Peaks assignable to BIM → U(VI) were located at ?26,600 cm^?1. The most probable structures of these complexes have been suggested.     

Unsteady Two-Dimensional Blood Flow in Porous Artery with Multi-Irregular Stenoses

The flow characteristics of an unsteady axisymmetric two-dimensional (2D) blood flow in a diseased porous arterial segment with flexible walls are investigated. The arterial walls mimic the irregular constrictions whereas the lumen containing the thrombus, cholesterol, and fatty plaques represents the porous medium. The governing equations with appropriate initial and boundary conditions are solved numerically using MAC method. The discretization is done on staggered grid with non-uniform grid size and pressure-poisson equation is solved following SOR method. The pressure and velocity corrections are made cyclically until the steady state is achieved. It is observed that for decreasing permeability, flow is highly decelerated while pressure drop and wall shear stress increases. The separation zones and re-circulation regions are found for severe stenoses. Flow separation and re-circulation diminishes for decreasing permeability of the porous medium. Comparisons are provided with published experimental and numerical results.     

Calculating hydrodynamics problems for a liquid film flowing radially on a flat horizontal surface

A mathematical hydrodynamic model of a thin liquid film flowing radially on a flat horizontal surface has been elaborated. The model consisted of continuity and momentum equations which were resolved by means of the integral method. In fact, several versions of the model were examined; they differed mainly in film velocity distribution. The predictions of the different versions were then compared with liquid film thicknesses obtained from experimental investigation. The best version was applied in further calculations.     

Thermodynamics of the extraction of Co2+ by htenoyltrifluoroacetone, 8-hydroxyquinoline and phenanthroline

The extraction of Co²⁺ from aqueous 0.1M acetate buffer by thenoyltrifluoroacetone (HTTA) and 8-hydroxyquinoline (HQ) and by a mixture of HTTA+phen and HQ+phen in benzene has been studied at various temperatures allowing for elucidation of the thermodynamics of extraction in the cases investigated.     

Dynamic thermal expansion and scanning calorimetry of mercury phases in dental amalgams

Thermomechanical analysis, TMA, was used to evaluate the linear thermal expansion coefficient,α, of four different types of dental amalgams: Conventional lathe-cut alloy, conventional spheralloy, high copper dispersalloy and high copper ternary alloy. Dynamic thermal expansion studies showed an interesting contraction behaviour around 85 °C for conventional amalgams and 105 °C for high copper amalgams which coincided with the endotherms produced by differential scanning calorimetry, DSC, and was attributed to the existence of theγ ₂ andγ ₁ phases, respectively. Pure single phases were prepared and characterized by DSC at 210 °C forγ ₂ and 120 °C forγ ₁. When theγ ₂ was enriched with mercury, the decomposition endotherm showed gradual shift to lower temperatures and reached 85 °C. The value of the linear coefficient of thermal expansion ranged between 15 and 35 ppm/°C for all the investigated brands. Thermomechanical analysis has confirmed previous results achieved by DSC in characterizing mercury-containing phases in dental amalgams.