Crystal structure of 6-oxa-3,9-dithiabicyclo[9.2.2]pentadeca-1(15),11,13-triene.

The structure of an S2O mixed-donor macrocycle incorporating para-substituted xylyl subunit was characterized by a single crystal X-ray analysis. The crystal structure shows an exo-dentate orientation of sulfur and oxygen donor atoms due to the fully stretched aliphatic ring conformation. Thus all of torsional angles between donor atoms are arranged anti and S...S distance in a ring is 6.764(1)A, which is larger than those values of ortho- and meta-type analogs. The observed high rigidity of the ring conformation may induce the extraordinary behaviors in chelation.     

Heat transfer in non-Newtonian falling liquid film on a horizontal circular cylinder

 This study aims to investigate numerically the laminar flow and heat transfer in a pseudoplastic non-Newtonian falling liquid film on a horizontal cylinder for the constant heat flux and isothermal boundary conditions. The inertia terms are taken into account. An implicit finite difference method is carried out to solve the governing boundary layer equations. The effects of operational parameters on the hydrodynamic and heat transfer characteristics are examined and discussed in detail. The results presented show that the local and average Nusselt numbers varies significantly as a function of the concentration of aqueous carboxymethylcellulose (CMC) solutions and the cylinder diameter. Higher concentration of aqueous CMC solutions generate larger heat transfer coefficients. Finally, a comparison with the experimental and numerical results available in the literature for Newtonian fluids shows clearly that the present analysis is reasonably accurate. Received on 29 March 2001 / Published online: 29 November 2001     

Improved photoluminescence of pulsed-laser-ablated Y<Subscript>1-x</Subscript>Gd<Subscript>x</Subscript>VO<Subscript>4</Subscript>:Eu<Superscript>3+</Superscript> thin film phosphors by Gd substitution

Gd-substituted Y_1-xGd_xVO₄:Eu³⁺ luminescent thin films have been grown on Al₂O₃(0001) substrates using pulsed-laser deposition. The films grown under different deposition conditions have been characterized using microstructural and luminescent measurements. The crystallinity, surface morphology, and photoluminescence (PL) of the films are highly dependent on the amount of Gd. The photoluminescence (PL) brightness data obtained from Y_1-xGd_xVO₄:Eu³⁺ films grown under optimized conditions have indicated that the PL brightness is more dependent on the surface roughness than the crystallinity of the films. In particular, the incorporation of Gd into the YVO₄ lattice could induce a remarkable increase of PL. The highest emission intensity was observed with Y_0.57Gd_0.40Eu_0.03VO₄ thin film whose brightness was increased by a factor of 2.5 and 1.9 in comparison with that of YVO₄:Eu³⁺ and GdVO₄:Eu³⁺ films, respectively. This phosphor have application to flat panel displays. PACS 78.20.-e; 78.55.-m; 78.66.-w     

Noninvasive mitochondrial imaging in live cell culture

The observed distribution of mitochondria in a cell can vary with environmental influence, degree of differentiation and disease. Differences in the distribution of mitochondrial autofluorescence may be used to distinguish these different cellular states.     

X-ray Fluorescence Determination of Carbon,Nitrogen, and Oxygen in Fish and Plant Samples

The potentials of X-ray fluorescence analysis in the determination of carbon, nitrogen, and oxygen in materials of plant and animal origin were studied. The contribution of photoelectron excitation to the analytical signal and the effect of uncertainties in the attenuation coefficient on the calculation of element concentrations by the absorption correction method were estimated. Methods for calculating analyte concentrations using simple linear regression with absorption correction and multiple regression were compared. The results were also compared with those of pyrolysis-gas-chromatography. The error of the method was 1–2% for element concentrations between 10 and 50% and 25% in the range of nitrogen concentration 1–2%.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 5, 2005, pp. 485–489.Original Russian Text Copyright © 2005 by Farkov, Ilicheva, Finkelshtein.     

Quasi-potential approach to the three-quark nucleon wave function

The structure of the nucleon wave function as a coupled system of valence quarks is examined by the quasi-potential method used to describe coupled states with a fixed number of particles. In the momentum approximation, the wave function is reduced to a three-particle state vector component in the Fock space. The spin structure of the wave function is examined by the method of representing a product of irreducible representations of the Lorentz inhomogeneous group in terms of states with fixed momenta. The physical uniqueness of the SU(6) symmetrical solution is its unambiguity in the nonrelativistic limit. The effective mass approximation of relativistic theory with large average quark momentum and small momentum variance is numerically investigated. A relativistic generalization of the nonrelativistic three-particle problem with oscillator forces is suggested.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 27–32, December, 2004.