Isomeric ratios in photonuclear reactions of molybdenum isotopes induced by bremsstrahlung in the giant dipole resonance region

We have determined the isomeric ratios of isomeric pairs ^97m,gNb, ^95m,gNb and ^91m,gMo produced in ⁹⁸Mo(γ, p)^97m,gNb, ⁹⁶Mo(γ, p)^95m,gNb and ⁹²Mo(γ, n)^91m,gMo photonuclear reactions in the giant dipole resonance (GDR) region by the activation method. The results were analyzed, discussed and compared with the similar data from literature to examine the role of excitation energy, neutron configuration, channel effect and direct and pre-equilibrium processes in (γ, p) photonuclear reactions. In this work the isomeric ratios for ^97m,gNb from 14 to 19 MeV, for ^195m,gNb from14 to 24 MeV except 20 and 23.5 MeV and for ^91m,gMo at 14 and 15 MeV are the first time measurements.     

A control volume technique based on integrated RBFNs for the convection–diffusion equation

This article reports a new high‐order control‐volume discretization for the convection–diffusion equation in one and two dimensions. Diffusive fluxes at the faces of a control volume and other terms embracing the unknown field variable are all approximated using one‐dimensional integrated radial‐basis‐function networks; line integrals involving these fluxes and other integrals are evaluated using a high‐order numerical integration scheme. The accuracy of the proposed technique is investigated numerically through the solution of several linear and nonlinear test problems, including a benchmark thermally driven cavity flow. High‐order convergence solutions are obtained. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010     

Acousto-optical tweezers for stretch of DNA molecule

The appearance of microlenses in the amorphous crystal Ge₃₃As₁₂Se₃₃ modulated by the acoustic waves with intensity of 10⁷ W/m² and frequency of (200–400) MHz is presented. The flexibility of microlens, i.e. the dependence of its focal point in 3D space on the parameters of acoustic wave is studied. Basing on flexibility of microlens, a model of acousto-optical tweezers to stretch the λ-phage WLC DNA molecule is proposed. And then the control process of stretched length of DNA molecule in 3D space of the water (fluid) by calibration of the acoustic frequency is numerically observed and discussed. The obtained results show the possibility to use the acousto-optical tweezers to control the stretched length of WLC DNA molecule with high fineness.     

Round-robin measurements of two candidate materials for a Seebeck coefficient Standard Reference Material™

A Standard Reference Material (SRM^™) for the Seebeck coefficient is critical for inter-laboratory data comparison and for instrument calibration. To develop this SRM^™, we have conducted an international round-robin measurement survey of two candidate materials—undoped Bi₂Te₃ and constantan (55% Cu and 45% Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active thermoelectric research using a number of commercial and custom-built measurement systems and techniques. We report the results of these measurements and the statistical analysis performed. Based on this extensive study, we have selected Bi₂Te₃ as the prototype standard material.     

Observation of a spin gap in the normal state of superconducting Mo3Sb7

Magnetization, specific heat, and electrical resistivity measurements have been performed on the superconductor Mo(3)Sb(7). Two kinds of transitions are observed at 2.3 and 50 K, respectively. The former is superconducting transition, while the latter is attributed to spin-gap formation. From the analysis of the experimental data, excitation gap, intra- and interdimer interactions are estimated as Delta/k(b) approximately 120 K, J(0)/k(B) approximately 150 K, and J(1)/k(B) approximately 55 K. The electronic structure calculations using the LSDA approximation show nesting property in the Fermi surface, favoring the superconductivity.     

A high‐order upwind control‐volume method based on integrated RBFs for fluid‐flow problems

This paper is concerned with the development of a high‐order upwind conservative discretization method for the simulation of flows of a Newtonian fluid in two dimensions. The fluid‐flow domain is discretized using a Cartesian grid from which non‐overlapping rectangular control volumes are formed. Line integrals arising from the integration of the diffusion and convection terms over control volumes are evaluated using the middle‐point rule. One‐dimensional integrated radial basis function schemes using the multiquadric basis function are employed to represent the variations of the field variables along the grid lines. The convection term is effectively treated using an upwind scheme with the deferred‐correction strategy. Several highly non‐linear test problems governed by the Burgers and the Navier–Stokes equations are simulated, which show that the proposed technique is stable, accurate and converges well. Copyright © 2010 John Wiley & Sons, Ltd.     

Some Inverse Problems in Periodic Homogenization of Hamilton-Jacobi Equations

We look at the effective Hamiltonian \({\overline{H}}\) associated with the Hamiltonian \({H(p,x)=H(p)+V(x)}\) in the periodic homogenization theory. Our central goal is to understand the relation between \({V}\) and \({\overline{H}}\). We formulate some inverse problems concerning this relation. Such types of inverse problems are, in general, very challenging. In this paper, we discuss several special cases in both convex and nonconvex settings.     

Local rules for quasiperiodic tilings of quadratic 2-planes inR 4

We prove that quasiperiodic tilings of the plane, appearing in the strip projection method always admit local rules, when the linear embedding ofR ² inR ⁴ has quadratic coefficients. These local rules are constructed and studied. The connection between Novikov quasicrystallographic groups and the quasiperiodic tilings of Euclidean space is explained. All the point groups in Novikov's sense, compatible with these local rules, are enlisted. The two-dimensional quasicrystals with infinite-fold rotational symmetry are constructed and studied.Address after September 1, 1992: Dept. of Physics, Harvard University, Cambridge, MA 02138, USA     

Caracterisation du comportement polymorphique du fluoro-2 naphtalene

The use of various techniques such as X-ray and neutron diffraction, Raman scattering, diffusion and calorimetry has allowed us to characterize the polymorphic behaviour of 2-fluoronaphthalene. Under atmospheric pressure, three crystalline forms can be detected between 80 K and the melting temperature. The high temperature one, F_I, which is stable from 272 K to the melting point, is isomorphous with naphthalene (space group P2₁/a,Z = 2); by cooling it can be preserved as a metastable form down to 154 K, the 272-154 K range being the stability domain of the form F_III. Below 154 K, a new form, called F_III appears. The kinetics of the transformation F_I → F_III seem to be dependent upon the size of the crystals. The Raman spectra of f_I and F_III are identical, which suggests similar structural disorder in both phases. This is also supported by the low value of the entropy associated with the transition F_III → F_I (0.55 J K^?1 mole^?1). The unit cell parameters of the F_III and F_III forms have been determined from data using automatic indexing methods. The two solid-solid transitions are first order, the F_III–F_III' one being “explosive”.     

A method to obtain kinematic intensities from low-energy electron diffraction data

In order to use low-energy electron diffraction as a tool for surface crystallography, it would be useful to extract the single scattering, or kinematic part, from the intensity data. Details of a method to do this by taking data with different diffraction geometry but at fixed momentum transfer are presented. The method is illustrated by data from Ni and Ag. The temperature dependence of the averaged intensity is presented. The multiple scattering contributions to the averaged intensity can be accounted for by an effective atomic scattering factor. Conditions for the applicability of the method are discussed. From the resulting kinematic intensities, the surface atomic arrangements can be determined by simple modifications of conventional crystallographic analysis.