Search results for "Meri"

De la performance musicale dans la Guyane traditionnelle : expression cognitive singulière d?une musique-verbe

2021

Guianese culture and traditional music, here evoked, are various. It is more a transcultural process that, along centuries, gave an original result born in the Americas, in Guiana in this case. It is a form of refoundation, of recreation of cultures and new human beings generally called Creoles. The musical performance, that I study here, is the echo of social and cultural space of this reformulation of thought, life, and conception of the world. It is, as well, a mean of transposition and transformation of the values issued of diverse sources and categories. It is in no way a second-rate cultural practice, as it is the place where were born philosophies and actions for common life as well …

Initial strain effects in multilayer composite laminates

2001

A boundary integral formulation for the analysis of stress fields induced in composite laminates by initial strains, such as may be due to temperature changes and moisture absorption is presented. The study is formulated on the basis of the theory of generalized orthotropic thermo-elasticity and the governing integral equations are directly deduced through the generalized reciprocity theorem. A suitable expression of the problem fundamental solutions is given for use in computations. The resulting linear system of algebraic equations is obtained by the boundary element method and stress interlaminar distributions in the boundary-layer are calculated by using a boundary only discretization. …

Numerical analysis of masonry structures via interface models

2001

The present paper is devoted to the theoretical formulation and numerical implementation of an interface model suitable to simulate the behavior of mortar joints in masonry structures. The interface laws are formulated in the framework of elasto-plasticity for non-standard materials in order to simulate the softening response which occurs along the decohesion process in presence of shear and tension tractions. A variable material dilatancy parameter is introduced together with a further geometrical dilatancy related to the roughness of contact surfaces after joint fracture. An asperity model is adopted with the aim to describe the evolution of the contact surface shape during the loss of co…

ISomerization of xylene: MINDO/3 study of the cyclization of benzenium cation into bicyclo[3.1.0]hexenyl cation

1989

Abstract A MINDO/3 study of thermal electrocyclic closing of the benzenium cation to form a bicyclo[3.1.0]hexenyl cation is presented. The calculated mechanism discusses the possibility of cyclization of xylenium cations on a silica catalyst or in superacid media. The structure and energy of the transition state, the enthalpies of isomerization and barriers of activation were calculated for the following processes: isomerization of 2,6-dimethylbenzenium cation into 2,6-dimethylbicyclo[3.1.0]hexenyl cation, isomerization of 2,4-dimethylbenzenium cation into 2,4-dimethylbicyclo[3.1.0]-hexenyl cation, and isomerization of benzenium cation into bicyclo[3.1.0]-hexenyl cation. Equilibrium and kin…

1984

Alkaline hydrolyses of anionic phenyl esters such as 4-acetoxy-3-nitrobenzoic acid and 4-butyryloxy-3-nitrobenzoic acid were examined in the presence of cationic and polymeric liposomes, liposomes of low molecular weight compounds, and micelles. All the additives accelerate the reaction due to the hydrophobic interaction between substrates and additives and the electrostatic interaction both between substrates and additives and between OH− and additives. In the Arrhenius plots of the reactions catalyzed by the liposomes, discontinuous regions were observed due to the phase transition of liposomes from the gel state to the liquid crystal state. Activation parameters ΔH≠, ΔS≠ and ΔV≠ for thes…

1D coordination polymer based on copper(II)-containing tetrameric 1,2,3-triazole ligand from click chemistry: Magnetic and catalytic properties

2019

Abstract A novel tetrameric tetra[O-((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)]-pentaerythritol (TBTP) has been synthesized using click chemistry strategy. TBTP was characterized and used as ligand to form new Cu(II) complexes, forming 1-D coordination polymers. Two square planar complexes were characterized by single-crystal X-ray diffraction, presenting formula [Cu(TBTP)][Cu(NO3)4] (1) and [Cu(TBTP)](NO3)2 (2). In both structures, a cationic 1-D coordination polymer (CP) has been formed. The CP contain a 1:1 Cu(II)/TBTP ratio with four neutral triazole groups coordinating the Cu(II) center, forming a Cu N bonds ranging 1.988(2)–2.001(2) A. The study of the magnetic properties of compounds 1…

A Property on Singularities of NURBS Curves

2002

We prove that if a.n open Non Uniform Rational B-Spline curve of order k has a singular point, then it belongs to both curves of order k - 1 defined in the k - 2 step of the de Boor algorithm. Moreover, both curves are tangent at the singular point.

Intermolecular interactions in dictating the self-assembly of halogen derivatives of bis-(N-substituted oxamato)palladate(ii) complexes

2016

Three palladium(II) complexes of formula (n-Bu4N)2[Pd(4-Fpma)2] (1), (n-Bu4N)2[Pd(4-Clpma)2]·4H2O (2) and (n-Bu4N)2[Pd(4-Brpma)2]·4H2O (3) [n-Bu4N+ = tetra-n-butylammonium cation, 4-Fpma = N-4-fluorophenyloxamate, 4-Clpma = N-4-chlorophenyloxamate and 4-Brpma = N-4-bromophenyloxamate] have been prepared and their structures determined by single crystal X-ray diffraction. Each palladium(II) ion in 1–3 is four-coordinate with two oxygen and two nitrogen atoms from two fully deprotonated oxamate ligands building PdO2N2 square planar surroundings, the oxamate ligands exhibiting trans (1 and 2) and cis (3) dispositions. The fluoro substituent and the organic counterion in 1 are involved in C–H⋯F…

Simulations of Array Configurations for the Square Kilometre Array (SKA)

2010

The Square Kilometre Array (SKA) is a new generation radio telescope for the next decades, working at metre to centimetre wavelengths. The SKA will be operational at the same time than other new optical, X-ray and Gamma-ray telescopes. It is of extreme importance that the SKA becomes competitive and complementary to those instruments. An extensive study of technologies and possible configurations involved is needed to ensure the SKA will reach the design specifications. To compare imaging capabilities between different SKA configurations or between the SKA and other instruments, we have implemented figures of merit based on several characteristics of these instruments. In this work we are p…

Synthesis of hyperbranched poly(tert-butyl acrylate) by self-condensing atom transfer radical polymerization of a macroinimer

2000

Using 2-hydroxyethyl α-bromoisobuty-rate as initiator, atom transfer radical polymerization (ATRP) of tert-butyl acrylate leads to poly(tert-butyl acrylate) (PtBA) with a hydroxyl group at one and a bromine atom at the other end. Esterification of the hydroxyl group of these heterotelechelic polymers with acryloyl chloride yields PtBA (M n = 3060) with a polymerizable double bond at one end and a bromine atom at the other end which can act as an initiator in ATRP (macroinimer). Self-condensing ATRP of such a macroinimer leads to hyperbranched or highly branched PtBA. The polymer was characterized by GPC viscosity measurements. Even at M w = 78800, a rather low polydispersity index of M w M …