Molecular Geometry
Mostrando 37-48 de 193 artigos, teses e dissertações.
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37. NUMERICAL SIMULATION OF WAX DEPOSITION IN PETROLEUM LINES: ASSESSEMENT OF MOLECULAR DIFFUSION AND BROWNIAN DIFFUSION MECHANISMS / SIMULAÇÃO NUMÉRICA DA DEPOSIÇÃO DE PARAFINA EM DUTOS DE PETRÓLEO: AVALIAÇÃO DOS MECANISMOS DE DIFUSÃO MOLECULAR E DIFUSÃO BROWNIANA
Wax deposition is one of the major critical operational problems in crude oil pipelines operating in cold environments. Therefore, accurate prediction of the wax deposition is crucial for the efficient design of subsea lines. Unfortunately, wax deposition is a complex process for which the mechanisms are still not fully understood. Aiming at the identificati
Publicado em: 2007
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38. 1,2,4-oxadiazÃis: sÃntese, desenvolvimento de novas metodologias sintÃticas e avaliaÃÃo da atividade antiinflamatÃria
This work describes the obtainment of many novel 3,5-disubstituted 1,2,4-oxadiazoles. First, the synthesis of ten previously unknown 3-aryl-5-tridecyl- and 3-aryl-5-heptadecyl-1,2,4- oxadiazoles 40a-g, 40h-j, starting from arylamidoximes 12a-g and tetradecanoic as well as heptadecanoic acids 38a and 38b is reported. Second, seven new 3-aryl-5-(cis-heptadec-1
Publicado em: 2007
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39. SYNTHESIS AND CRYSTALCHEMISTRY OF 1-(4-CARBOXYPHENYL)-3-(4-ACETYLAMIDOPHENYL)TRIAZENE AND COMPLEXES OF COPPER(I), SILVER(I) AND GOLD(I) WITH 1-(4-ETHOXYCARBONYLPHENYL)-3-(4-NITROPHENYL)TRIAZENIDE LIGAND / SÍNTESE E CRISTALOQUÍMICA DO 1-(4-CARBOXIFENIL)-3-(4-ACETILAMIDOFENIL)TRIAZENO E COMPLEXOS DE COBRE(I), PRATA(I) E OURO(I) COM O LIGANTE 1-(4-NITROFENIL)-3-(4-ETOXICARBOXIFENIL)TRIAZENIDO
This work deals with the determination of the single crystal structure analysis of four triazenido complexes including gold(I), copper(I), silver(I), and the crystal structure of a free triazene molecule. Crystal data and refinement indices of 1-(4-carboxyphenyl)-3-(4- acetylamidophenyl)triazene (1) are: monoclinic system, space group P21/n, cell parameters
Publicado em: 2007
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40. Movimento bidirecional no transporte intracelular mediado por motores moleculares / Bidirectional movement in the intracellular transport mediated by molecular motors
In this work we present a theoretical model to describe aspects of the bidirectional movement performed by intracellular structures (vesicles, organelles, viruses etc, to which we refer here simply as "vesicles"), observed essentially at in vivo experiments. This nondifusive movement is characterized by rapid inversions in direction and is capable of creatin
Publicado em: 2007
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41. Analysis of nuclear relaxation in granular systems
The longitudinal nuclear magnetic relaxation time, T1, of powdered samples was analyzed following the theory proposed by Browstein and Tarr to explain the T1 reduction of water confined in biological cells and the proposed by Rabbani and Edmonds where the molecular diffusion in liquids is substituted by spin diffusion to interpret the T1 behavior in solid pa
Brazilian Journal of Physics. Publicado em: 2006-03
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42. Estudo da evolução dinamica de nanofios de cobre e ouro / Study of dynamical evolution of cooper and gold
Metallic nanowires have been a subject of study for at least ½fteen years. The interest in these new materials is increasing continuously due to the possibility of using them as metallic contacts in electronic nanodevices. For example, between two tips of very thin nanowires, it is possible to insert small structures, such as carbon buckyballs or small orga
Publicado em: 2006
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43. INVESTIGAÇÃO DE COMPLEXOS BINUCLEARES DE K+ E CU(II) COM LIGANTES 1,3-DIARILTRIAZENIDOS SIMÉTRICOS / COMPLEXES INVESTIGATION BINUCLEARES OF K+ And Copper(II) WITH 1,3-DIARYLTRIAZENES AS LIGANDS SYMMETRICAL
At work present it synthesized and determined itself the molecular structure of a copper complex (II) and another of potassium in which both involve triazenides ligands monocatenados previously deprotonated. The reaction between hydroxide of solid potassium and it pre-ligand 1,3-bis(4-nitrophenyl)triazene, in methanol, originated the triazenide complex [K(O2
Publicado em: 2006
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44. Método de Monte Carlo utilizando cálculos de energia total AB initio / Monte Carlo method using AB initio total energy calculation
Computer simulations are essential tools to the research of physical systems at finite temperatures. Monte Carlo (MC) and Molecular Dynamics (MD) methods are the major techniques used for this purpose, and empirical potentials are traditionally employed in these simulations. These potentials, however, are built to describe with precision the system near some
Publicado em: 2006
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45. La modelización molecular como herramienta para el diseño de nuevos polímeros conductores
The ability of molecular modeling techniques based on quantum chemical methods to predict the molecular and electronic structure of organic conducting polymers is examined. More specifically, we report on the applicability of these computational tools to study different aspects of polythiophene and its derivatives: molecular geometry and planarity, the struc
Polímeros. Publicado em: 2005-11
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46. Um paradigma da química medicinal: a flexibilidade dos ligantes e receptores
In general, molecular modeling techniques applied in medicinal chemistry have been static and drug based. However the active site geometry and the intrinsic flexibility of both receptor and ligand are fundamental properties for molecular recognition and drug action. As a consequence, the use of dynamic models to describe the ligand-receptor complex is becomi
Química Nova. Publicado em: 2005-02
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47. Synthesis and properties of supermolecular meso tetra(pyridyl)porphyrins and its layer-by-layer electrostatic assembled nanomaterials / Obtenção e propriedades de meso tetra(piridil)porfirinas supermoleculares e dos nanomateriais obtidos por montagem eletrostática camada por camada
A new series of nonplanar supermolecular metalloporphyrins have been obtained by coordenative self-assembly of meso-tetra(3-pyridyl)porphyrins and ruthenium complexes such as [Ru(bipy)2Cl]+ and [Ru(bipy)2(OH2)]2+. The electronic and structural properties have been investigated by electronic spectroscopy, mass spectrometry, cyclic voltammetry, and spectroelec
Publicado em: 2005
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48. Utilização de modelos moleculares no ensino de estequiometria para alunos do ensino médio.
The lack instructional materials for science teaching is a common problem in Brazil, and concerning to chemistry teaching in particular this problem can be observed even in more developed countries. Although molecular models are one of the few materials available for chemistry teaching, they have been hardly used, and this application has been restricted to
Publicado em: 2005