Anwar Hasmy

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Shola Adenekan

Universiteit Gent

Mauro Grondona

University of Genova

Krzysztof Nawratek

The University of Sheffield

Cosmin Sebastian Cercel

Ghent University

Rafael Domingo Osle

University of Navarra

Rodrigo G de Azevedo

Pontifícia Universidade Católica do Rio Grande do Sul

Aderivaldo Ramos de Santana

University of Zurich, Switzerland

Scott Stafne

Nomad University

Andres del Rio

UFF - Universidade Federal Fluminense

Ivan Poli

University of Sao Paulo

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Papers by Anwar Hasmy

On the Formation of Monatomic Metal Wires

Bulletin of the American Physical Society, 2006

The formation of monatomic metal wires under stress has been observed with HRTEM. It has been rev... more The formation of monatomic metal wires under stress has been observed with HRTEM. It has been revealed that gold chains can be obtained if the stress is applied on the (111) and (100) orientations, while not on the (110) orientation. Other experiments have evidenced that some metals are unable to exhibit this monatomic wire formation. Theoretical efforts addressed to determine

Formación y divulgación de la nanotecnología en Venezuela: situación y perspectiva

Cluster–cluster aggregation with mobile impurities

Journal of Sol-Gel Science and Technology

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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Extended H�ckel tight-binding approach to electronic excitations

Chem Phys, 2008

In this work, we propose the application of a self-consistent extended Hückel tight-binding (EHTB... more In this work, we propose the application of a self-consistent extended Hückel tight-binding (EHTB) method in the computation of the absorption optical spectrum of molecules within the linear response time dependent density functional formalism. The EHTB approach is presented as an approximation to the Kohn-Sham energy functional. The method is applied to the computation of excitation energies and oscillator strengths of benzene, pyridine, naphthalene, diazines, and the fullerenes: C60(Ih), C70(D5h), and C80(D2). The very good agreement with experimental data is very encouraging and suggests the possibility of using the EHTB as a computational efficient and reliable tool to study optical properties of a wide variety of molecular systems.

Monte Carlo simulation of critical behavior of isotropic-nematic phase transition in aerogel pores

AIP Conference Proceedings, 2001

Monte Carlo study of critical behavior of 3D XY model in aerogel pores

AIP Conference Proceedings, 2001

Les activités de modélisation au Laboratoires des Verres

$Research paper thumbnail of Diffusivity and pore distribution in fractal and random media$

Diffusivity and pore distribution in fractal and random media

Physical Review E, 1999

Nonlinear modeling technique for the analysis of DNA chains

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 2000

Using a simple computational procedure, we examine DNA chains from different species in order to ... more Using a simple computational procedure, we examine DNA chains from different species in order to prove their nonlinear deterministic structures. This procedure applies a nonlinear modeling technique based upon quantitative comparison of the neighborhoods from similar DNA subsegments of size d. Our results reveal that noncoding regions exhibit a deterministic signature at sizes larger than a characteristic dimension d(c). Applications to evolutionary categories and recognition of different DNA regions are discussed.

$Research paper thumbnail of Small-angle scattering by fractal aggregates: A numerical investigation of the crossover between the fractal regime and the Porod regime$

Small-angle scattering by fractal aggregates: A numerical investigation of the crossover between the fractal regime and the Porod regime

Physical review. B, Condensed matter, 1994

Fractal aggregates are built on a computer using off-lattice cluster-cluster aggregation models. ... more Fractal aggregates are built on a computer using off-lattice cluster-cluster aggregation models. The aggregates are made of spherical particles of different sizes distributed according to a Gaussianlike distribution characterised by a mean a0 and a standard deviation σ. The wave vector dependent scattered intensity I(q) is computed in order to study the influence of the particle polydispersity on the crossover between the fractal regime and the Porod regime. It is shown that, given a0, the location qc of the crossover decreases as σ increases. The dependence of qc on σ can be understood from the evolution of the shape of the center-to-center interparticle-distance distribution function.

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Percolation in cluster-cluster aggregation processes

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1996

Numerical simulations of Diffusion-Limited and Reaction-Limited Cluster-Cluster Aggregation proce... more Numerical simulations of Diffusion-Limited and Reaction-Limited Cluster-Cluster Aggregation processes of identical particles are performed in a twodimensional box. It is shown that, for concentrations larger than a characteristic gel concentration, the morphology of the resulting spanning cluster at the gel time t g exhibits a crossover length L c between percolation (l > L c) and aggregation (l < L c). L c vanishes when increasing c, and, at a critical concentration value c p (where L c → 0) the entire spanning cluster scales as the percolating cluster obtained by standard percolation. Even if for c > c p the long-range correlations are similar to that of percolation, the vanishing links in the structure suggest that an homogeneous regime appears at small scales.

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Local reactivity limited aggregation

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1996

ABSTRACT

Gas Transport in Porous Media

Theory and Applications of Transport in Porous Media, 2006

Gas-phase momentum transport in porous media consists of advective and diffusive components. In t... more Gas-phase momentum transport in porous media consists of advective and diffusive components. In this chapter, the individual advective and diffusive components will be presented separately first, followed by a discussion of the combined mechanisms. Gas-only situations will be discussed for all the mechanisms. Two-phase, or unsaturated, flow effects are included in Chapter 5. The conservation equations presented below are given in a simplified form. For a complete derivation of the various conservation equations, including underlying assumptions, see Whitaker (Chapter 6 of this book). Energy transport is not discussed in this chapter. Gas-phase energy transport in porous media is treated by Plumb (Chapter 27 of this book). Energy transport is also discussed in Nield and Bejan (1999) and Kaviany (1995). 2.1 GAS-PHASE ADVECTION 2.1.1 Darcy's Law Gas-phase advection in porous media is generally analyzed using Darcy's law (Darcy, 1856), which simply states that the gas Darcy velocity, u g , is directly proportional to the gas-phase pressure gradient, ∇P g , and the gas-phase permeability, k g. Darcy's law can be written as u g = − k g µ g ∇P g − ρ g g where µ g is the gas-phase viscosity and g is the gravitational constant. In terms of mass flux, the equation is F g = ρ g u g = − k g µ g ρ g (∇P g − ρ g g) 6 Webb Neglecting gravity and rearranging ∇P g = − µ g k g u g Note that the Darcy velocity, u g , is not a physical velocity. Rather, it is a superficial velocity based on the entire cross section of the flow, not just the fluid flow cross-section. The Darcy velocity is related to the pore velocity, V g , through the porosity, φ, or V g = u g φ The gas-phase permeability, k g , is a proportionality constant that is usually experimentally determined with units of length 2. The gas-phase permeability may be slightly different than the liquid-phase permeability due to the effects of the fluids. Values of the liquid-phase permeability vary widely, from 10 −7 to 10 −9 m 2 for clean gravel down to 10 −18 to 10 −20 m 2 for granite (Bear, 1979, pg. 68). The unit Darcy is often used, which is equal to 0.987 × 10 −12 m 2. Darcy's law is applicable to low velocity flow, which is generally the case in porous media flow, and to regions without boundary shear flow, such as away from walls. When wall shear is important, the Brinkman extension can be used as discussed below. For turbulent flow conditions, the Forchheimer equation is appropriate. In some situations (e.g., Vafai and Tien, 1981), the Brinkman and Forchheimer equations are both employed for a more complete momentum equation. For a more detailed discussion of the various flow laws, see Nield and Bejan (1999), Kaviany (1995), or Lage (1998).

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Surfactant Limited Aggregation of Hydrophobic Molecules in Water

Journal de Physique II, 1997

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Molecular dynamics simulations of breaking metallic nanowires

International Journal of Nanotechnology, 2004

... Venezuela PA Serena* Instituto de Ciencias de Materiales de Madrid, Consejo Superior de Inves... more

Nanotechnology in Latin America and the Caribbean: Current Situation and perspective

Pasado, presente y futuro de la Red Venezolana de Nanotecnología

Red Venezolana de Nanotecnología: Metas y Perspectivas

Untitled-Preface

2nd Workshop of Electronic Transport in Mesocopic Systems-Facultad de Ciencias-Universidad de Los Andes-Merida, Venezuela-September 27-October 1, 1999-Preface

On the Formation of Monatomic Metal Wires

Bulletin of the American Physical Society, 2006

Formación y divulgación de la nanotecnología en Venezuela: situación y perspectiva

Cluster–cluster aggregation with mobile impurities

Journal of Sol-Gel Science and Technology

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Extended H�ckel tight-binding approach to electronic excitations

Chem Phys, 2008

Monte Carlo simulation of critical behavior of isotropic-nematic phase transition in aerogel pores

AIP Conference Proceedings, 2001

Monte Carlo study of critical behavior of 3D XY model in aerogel pores

AIP Conference Proceedings, 2001

Les activités de modélisation au Laboratoires des Verres

$Research paper thumbnail of Diffusivity and pore distribution in fractal and random media$

Diffusivity and pore distribution in fractal and random media

Physical Review E, 1999

Nonlinear modeling technique for the analysis of DNA chains

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 2000

$Research paper thumbnail of Small-angle scattering by fractal aggregates: A numerical investigation of the crossover between the fractal regime and the Porod regime$

Small-angle scattering by fractal aggregates: A numerical investigation of the crossover between the fractal regime and the Porod regime

Physical review. B, Condensed matter, 1994

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Percolation in cluster-cluster aggregation processes

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1996

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Local reactivity limited aggregation

Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 1996

ABSTRACT

Gas Transport in Porous Media

Theory and Applications of Transport in Porous Media, 2006

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