Laser excited luminescence of coronene in a shpolskii matrix

The luminescence spectrum of coronene in n-heptane at 77°K has been studied using both xenon lamp and argon ion laser excitation. The results illustrate the Shpolskii theory of different emitting sites. With xenon excitation the emission spectrum consists of two similar slightly shifted subspectra. With laser excitation at 3511 Å only the longer wavelength subspectrum is observed. Fluorescence and phosphorescence excitation spectra show that this laser line is absorbed by the longwave component of the S₂←S₀ doublet.     

Existence results and iterative method for a fully fourth-order nonlinear integral boundary value problem

Numerical Algorithms - Recently, the condition numbers of the total least squares (TLS) problems having a unique solution have been studied at length in Zheng et al. (SIAM J. Matrix Anal. Appl. 38:...     

Two Meromorphic Functions Share Some Pairs of Small Functions

In this article, we prove that two meromorphic functions $f$ and $g$ must be linked by a quasi-Möbius transformation if they share two pairs of small functions ignoring multiplicities and share other four small functions with multiplicities truncated by 2. We also show that two meromorphic functions which share seven pairs of small functions ignoring multiplicities are linked by a quasi-Möbius transformation.     

New indications of potential rat intestinal α-glucosidase inhibition by Syzygium zeylanicum (L.) and its hypoglycemic effect in mice

Research on Chemical Intermediates - Natural α-glucosidase inhibitors (aGIs) have been considered effective agents for type 2 diabetes management. In this study, Syzygium zeylanicum (L.)...     

Synthesis and Magnetic Characteristics of Neodymium Ferrite Powders with Perovskite Structure

Russian Journal of Applied Chemistry - Nanopowders of neodymium ferrite with perovskite structure were synthesized by co-precipitation precipitation via hydrolysis of iron(III) and neodymium(III)...     

Theory and experiment of large numerical aperture objective Raman microscopy: application to the stress‐tensor determination in strained cubic materials

We present the theory underlying the large numerical aperture objective micro‐Raman backscattering experiment and apply it to the elaboration of a characterization methodology for the determination of the stress tensor in strained cubic semiconductor structures. The presented stress characterization technique consists in monitoring the variations of the stress‐sensitive optical phonon peak position and linewidth while rotating stepwise the sample about its normal. The practical application of the technique is illustrated on a silicon‐on‐insulator (SOI) microelectronic structure demonstrating a plane stress‐tensor determination. Copyright © 2008 John Wiley & Sons, Ltd.     

Molecular structure and conformation of 2,3-dichloro-1-propene as determined by gas-phase electron diffraction

The molecular structure and conformation of 2,3-dichloro-1-propene have been determined by gas-phase electron diffraction at nozzle temperatures of 24, 90 and 273°C. The molecules exist as a mixture of two conformers with the chlorine atoms anti (torsion angle ∠φ = 0°) or gauche (∠φ = 109°) to each other and with the anti form the more stable. The composition (mole fraction) of the vapor with uncertainties estimated at 2σ was found to be 0.55 (0.08), 0.49 (0.08) and 0.41 (0.10) at 24, 90 and 273°, respectively. These values correspond to an energy difference with estimated standard deviation ΔE° = E°_g-E°_a = 0.7 ± 0.3 kcal mol^?1 and an entropy difference ΔS° = S°_g-S°_a = 0.6 ± 0.9 cal mol^?1 K^?1. Some of the diffraction results, together with spectroscopic observations, permit the evaluation of an approximate torsional potential function of the form 2V = V₁ (1 - cos φ) + V₂ (1 - cos 2φ) + V₃ (1 - cos 3φ); the results are V₁ = 4.4 ± 0.5, V₂ = ?2.9 ± 0.5 and V₃ = 4.8 ± 0.2, all in kcal mol^?1. The results at 24°C for the distance (r_a) and angle (∠_α) parameters, with estimated uncertainties of 2σ, are: r(C_sp²-H) = 1.098(0.020)Å, r(C_sp³-H) = 1.103(0.020)Å, r(CC) = 1.334(0.009)Å, r(C-C) = 1.504(0.013)Å, r(C_sp²-Cl) = 1.752(0.021)Å, r(C_sp³-Cl) = 1.776(0.020)Å, ∠C-CC = 127.6(1.1)°, ∠C_sp³-C_sp²-Cl = 110.2(1.0), ∠C_sp²-C_sp³-Cl = 113.1(1.2)°, ∠H-C_sp³-H = 109.5° (assumed), ∠CC-H = 120.0° (assumed) and ∠φ = 108.9(3.4)°.     

Size- and shape-dependent effective conductivity of porous media with spheroidal gas-filled inclusions

Porous media containing gas-filled inclusions embedded in a solid phase constitute an important class of natural or artificial materials of both theoretical and practical interest. In these materials, thermal conductivity is one of the most important properties. In a variety of situations of practical interest, when the characteristic size of gas-filled inclusions is comparable with the mean free path of gas molecules and when the slip flow regime is considered, the behavior of gas near solid surfaces cannot be described by classical thermal conductivity equations. In fact, the boundary conditions at the solid surfaces must be modified by considering that the temperature and normal heat flux simultaneously suffer a discontinuity. The first purpose of the present work is to develop an efficient and accurate micromechanical model capable of estimating the effective conductivity of porous materials while taking into account the discontinuities of the temperature and normal heat flux across solid surfaces and the non-spherical form of gas-filled inclusions. The second purpose of the present work is to study the dependencies of the effective conductivity on the size and shape of gas-filled inclusions. By applying the micromechanical model based on the differential scheme and by using the solution results obtained for auxiliary dilute problem accounting for modified boundary conditions on surface solids, the closed-form expression for the effective conductivity is obtained. Numerical results are provided to illustrate the dependence of the effective conductivity on the size and shape of gas-filled inclusions in the case of randomly oriented inclusions.