Extension of the Launder,Reece and Rodi model on compressible homogeneous shear flow

This article describes the second order closure progress that was made to calculate compressible homogeneous shear flow with significant compressibility. Several DNS results show that compressibility has an important effect on the pressure-strain correlation. The term recognized as the principal responsible for the change in the magnitude of Reynolds-stress anisotropies. Thus, the pressure-strain incompressible models do not correctly predict compressible turbulence at high-speed shear flow. A method of including compressibility effects in the pressure-strain correlation is the subject of the present study. The concept of the growth rate of turbulent kinetic energy can be used to construct a compressible correction to the Launder, Reece and Rodi model for the pressure-strain correlation. This correction concerns essentially the C ₁,C ₃ and C ₄ coefficients which become in a compressible turbulence situation a function of the turbulent Mach number. The application of the new model shows good agreement with DNS results of Sarkar for cases A ₁, A ₂ and A ₃. These cases correspond to a moderate mean shear rate, so that nonlinear effects are important. This revised version was published online in July 2005 with corrections to some characters in the abstract.     

Iridoid glucosides from the aerial parts of Globularia alypum L. (Globulariaceae)

From the hydromethanolic extract of the aerial parts of Globularia alypum grown in Morocco, a new chlorinated iridoid glucoside, globularioside has been isolated beside 5 known iridoid glycosides, globularin, globularicisin, globularidin, globularinin and globularimin. This is the first report of a chlorinated iridoid in G. alypum and in the Globulareaceae. Unlike all other known 7-chlorinated iridoid glucosides where the chlorine atom exhibits an alpha configuration, globularioside incorporate the chlorine atom as a 7beta substituent. The structures of the isolated compounds were established on the basis of ESI-MS, MS-MS, 1D and 2D NMR spectral analysis.     

Harnack Inequality for Quasilinear Elliptic Equations in Generalized Orlicz-Sobolev Spaces

Potential Analysis - In this paper we prove, by a new method, the Harnack inequality for positive solutions of quasilinear elliptic equations in the generalized Orlicz-Sobolev space setting. Our...     

Phenomenological modeling of magnetic and magnetocaloric properties in rare earth doped La0.8Ca0.2MnO3

La_0.8Ca_0.2MnO₃ manganese oxides have been prepared by the conventional solid-state reaction. The samples crystallize in the orthorhombic structure with Pnma space group. A first-order magnetic phase transition from ferromagnetic to paramagnetic state is observed at the Curie temperature that is found to be around 241?K. The magnetic and magnetocaloric properties have been simulated using a phenomenological model. The maximum of magnetic entropy change is of order 8.2?J/kg?K for an applied magnetic field of 5?T, and the adiabatic temperature change is found to be of 4?K under a same magnetic field; this high value gives the sample the possibility of technologic application in the magnetic refrigeration area. The simulated results of magnetization and magnetic entropy change are compared with the experimental measurements. Finely, we found a good agreement between experimental and theoretical results.     

Sliding Presentation of the Jeux de Taquin for Classical Lie Groups

The simple \(GL(n,\mathbb {C})\)-modules are described by using semistandard Young tableaux. Any semistandard skew tableau can be transformed into a well defined semistandard tableau by a combinatorial operation, the Schützenberger jeu de taquin. Associated to the classical Lie groups \(SP(2n,\mathbb {C})\), \(SO(2n+1,\mathbb {C})\), there are other notions of semistandard Young tableaux and jeux de taquin. In this paper, we study these various jeux de taquin, proving that each of them has a simple and explicit formulation as a step-by-step sliding. Any of these jeux de taquin is the restriction of the orthogonal one, associated to \(SO(2n+1,\mathbb {C})\).     

Global chemical composition and antioxidant and anti-tuberculosis activities of various extracts of Globularia alypum L. (Globulariaceae) leaves

In this work, an evaluation of the biological activities of Globularia alypum L. extracts and their global chemical composition was realized. Extracts from G. alypum were obtained by two extraction methods. The composition of polyphenols (8.5-139.95 g gallic acid equivalent/Kg of dry mass), tannins (1.39-18.65 g catechin equivalent/Kg of dry mass), anthocyanins (8.17-70.69 mg cyanidin equivalent/Kg of dry mass) and flavonoids (0.31-19.28 g quercetin equivalent/Kg of dry mass) was evaluated. The samples were subjected to a screening for their antioxidant activities using the DPPH* and ABTS*+ assays. For the first time, the anti-tuberculosis activity (H(37)Rv) for G. alypum was tested against Mycobacterium tuberculosis. The strongest antioxidant activity was obtained for the methanol extract (IC(50 ) = 15.58 ± 0.168 mg/L) and the best anti-tuberculosis activity was obtained for the petroleum ether extract (IC(50 )= 77 mg/L). We have found a positive correlation between the total phenolics content and the antioxidant activity R2 = 0.88 (DPPH*) and R2 = 0.97 (ABTS*+). We have found also a positive correlation between the flavonoid content and the antioxidant activity R2 = 0.91 (DPPH*) and R2 = 0.91 (ABTS*+).     

Reaction of N‐thioamido amidines with phosphoramide derivatives: Synthesis of 2‐substituted‐1,3,5,2‐triazaphosphorines

The reaction of N‐thioamido amidines 1 with tris(dimethylamino)phosphine or bis(diethylamino)phenylphosphine in refluxing toluene leads to the 1,3,5,2λ³‐triazaphosphorines 2 and 3 , respectively. The condensation results in the release of two molecules of dialkylamine. The sulfuration of the trivalent phosphorus atoms was achieved by the reaction with elemental sulfur, followed by heating in toluene. The structure of the triazaphosphorines 2 and 3 and their thione derivatives 4 and 5 were readily elucidated by means of ¹H, ¹³C, and ³¹P NMR spectroscopy and mass spectrometry. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:272–277, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20546     

Absolute Intensities of the Infrared Bands of Gaseous Acrylonitrile

Laboratory spectral data (peak positions and integrated band intensities) of the infrared bands of acrylonitrile (CH2CHCN) gas in the region 4000-220 cm-1 are presented. Even though CH2CHCN has not yet been identified in Titan's atmosphere, it is among the possible photochemical and cosmic irradiation products of CH4 + N2 chemistry in the atmosphere of Titan. Laboratory simulations of Titan's atmospheric chemistry also give CH2CHCN as a product species. The results of our evaluation of the infrared intensity data provide an upper limit of the stratospheric abundance of CH2CHCN. Copyright 1999 Academic Press.