Møller’s Energy-Momentum Complex for a Spacetime Geometry on a Noncommutative Curved D3-Brane

Møller’s energy-momentum complex is employed in order to determine the energy and momentum distributions for a spacetime described by a “generalized Schwarzschild” geometry in (3+1)-dimensions on a noncommutative curved D3-brane in an effective, open bosonic string theory. The geometry considered is obtained by an effective theory of gravity coupled with a nonlinear electromagnetic field and depends only on the generalized (effective) mass and charge which incorporate corrections of first order in the noncommutativity parameter.     

New effective method for quantitative analysis of diffusion jumps, applied in molecular dynamics simulations of small molecules dispersed in short chain systems

Diffusion jumps of small molecules dispersed in chain molecules or other kinds of slow-moving matrices have already been observed in many previous simulations of such systems, and their treatment led to important qualitative conclusions. In the present work, a new, very simple yet effective method is described, allowing for both identification of individual penetrant jump events and their quantitative treatment in a statistical sense. The method is applied in equilibrium Molecular Dynamics simulations for systems of gaseous alkanes, methane through n-butane, including also a mixture of methane and n-butane, dispersed in n-decane or n-eicosane. Equilibration and attainment of a linear diffusion regime is confirmed by means of various criteria, and the jumps detection method is applied to all systems studied. The results obtained clearly show the existence of distinct jump events in all cases, although the average jump length is reduced with penetrant or liquid alkane molecular weight. The method allows one to determine the average jump length and the corresponding jumps frequency. On the basis of these results, it was possible to estimate a random walk type diffusion coefficient, D(s,jumps), of the penetrants, which was found to be substantially lower compared with the overall diffusion coefficient D(s,MSD) obtained by the mean square displacement method. This finding led us to assume that the overall penetrants' diffusion in the studied systems is a combination of longer jumps with a smoother and more gradual displacement, a result that confirms assumptions suggested in previous studies.     

Distribution of Energy-Momentum in a Schwarzschild-Quintessence Space-Time Geometry

An analysis of the energy-momentum localization for a four-dimensional Schwarzschild black hole surrounded by dark energy in the form of quintessence is presented in order to provide expressions for the distributions of energy and momentum. The calculations are performed by using the Landau–Lifshitz and the Weinberg energy-momentum complexes. It is shown that all the momenta vanish, while the expression for the energy depends on the mass M of the black hole, the state parameter w _q and the normalization factor c. The special case of $w_{q}=-\frac{2}{3}$ is studied and some limiting cases are examined.     

Methyl-jasmonat: Ein kurzer Weg zum Naturstoff und seinem unnatürlichen Enantiomer via Palladium(0)-induzierte,enantiodivergente Alkylierung von Cyclopent-2-en-1,3-diol-Derivaten

Methyl Jasmonate: A Short Synthesis of Naturally Occurring Methyl Jasmonate and its Unnatural Enantiomer via Enantiodivergent Alkylation of Cyclopent-2-ene-1,3-diol Derivatives by Palladium(0)-Induced Reactions Palladium-catalyzed alkylation of cyclopent-2-ene-1,2-diol derivatives like 2 is a useful method for enantiodivergent functionalization, resulting in both enantiomeric series of chiral building blocks. The chiral building blocks 3 and 13 can be transformed to methyl jasmonate ( 1 )and its unnatural enantiomer ent- 1 , recent statement [1b] that 1 has no odour at all and that ‘methyl jasmonate's’ fragrance is actually due to its cis-isomer ent-11 has been confirmed also for the enantiomeric series.     

Energy Distribution in a Schwarzschild-like Spacetime

In this paper, utilizing Møller’s energy-momentum complex, we explicitly evaluate the energy and momentum density associated with a metric describing a four-dimensional, Schwarzschild-like, spacetime derived from an effective gravity coupled with a U(1) gauge field in the context of a D3-brane dynamics in the classical regime, i.e., between the asymptotic and the Planck regime.     

Investigation of SDS, DTAB and CTAB micelle microviscosities by electron spin resonance

Electron spin resonance spectroscopy (ESR) of the nitroxide labelled fatty acid probes (5-, 16-doxyl stearic acid) was used to monitor the micelle microviscosity of three surfactants at various concentrations in aqueous solution: sodium dodecyl sulphate (SDS), dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB). At low surfactant concentration, there is no micelle, the ESR probe is dissolved in water/surfactant homogeneous phase and gives his microviscosity. At higher surfactant concentration, an abrupt increase in microviscosity indicates the apparition of micelles and, the solubilization of the probes in micelles. The microviscosity of the three surfactants, in a large surfactant range, was obtained as well as the critical micelle concentration (CMC). The microviscosity increased slightly with the increase in surfactant concentration. Phosphate buffer lowered the CMC value and generally increased the microviscosity.