O Instituto de Pesquisa Científica e Técnica para a Defesa (CITEDEF): história e presente

El Instituto de Investigaciones Científicas y Técnicas para la Defensa (CITEDEF) es un organismo que tiene un rol esencial en el desarrollo de tecnologías críticas para la Argentina. Desde su creación en 1954, se ha dedicado principalmente a atender los requerimientos de las Fuerzas Armadas, pero también ha generado numerosos proyectos dirigidos al conjunto de la sociedad, con beneficios que alcanzan a toda la población. En este artículo, se realiza un recorrido histórico desde su creación hasta su situación actual, en el que se repasan los principales logros de la institución, su desempeño en contextos de emergencia nacional como la Guerra de Malvinas y la pandemia por COVID-19, sus principales proyectos en ejecución y las proyecciones a futuro.The Institute of Scientific and Technical Research for Defense (CITEDEF) is an organization with an essential role in the development of critical technologies for Argentina. Since its creation in 1954, it has been mainly dedicated to meet the requirements of the Armed Forces, but it has also generated many projects aimed at society as a whole, with benefits reaching the entire population. This article presents an historic overview of the Institute since its beginnings to its current situation, highlighting its most important accomplishments, its performance in contexts of national emergency (such as the Malvinas War or the COVID-19 pandemic), its main active projects, and its projections into the future.O Instituto de Pesquisa Científica e Técnica em Defesa (CITEDEF) é uma organização que desempenha um papel essencial no desenvolvimento de tecnologias críticas para a Argentina. Desde sua criação em 1954, tem se dedicado principalmente a atender as exigências das Forças Armadas, mas também tem gerado inúmeros projetos voltados para a sociedade como um todo, com benefícios que atingem toda a população. Neste artigo, retomamos a história do instituto desde sua criação até sua situação atual, revisando as principais realizações da instituição, seu desempenho em contextos de emergência nacional como a Guerra das Malvinas e a pandemia da COVID-19, seus principais projetos em andamento e projeções futuras.Cátedra Libre Ciencia, Política y Socieda

Reactivity indexes for different geometries of palladium leads

Electronic transport through metallic break junctions or molecules is clearly dependent not only on the electronic structure of the central nanodevice connecting the leads, but also the shape and crystalline orientation of the contacts which can define the possible conduction channels. In this work we examine different geometries of contacts of palladium characterizing them through global and local reactivity indexes as electrophilicity, chemical hardness and Fukui functions. In molecules, these indicators are essentially defined by the energies of the frontier molecular orbitals and in solids they are related with the local and partial density of states. We use for this purpose an ab-initio based code (FIREBALL), applied to plane contacts with (001) fcc faces and also pyramidal tips grown following a (001) and (111) packaging. The results allow us to have an insight about the chemical features of this type of nanojunctions.Fil: Gómez Carrillo, Sandra Carolina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Departamento de Física; ArgentinaFil: Ortega, J.. Universidad Autónoma de Madrid; EspañaFil: Bolcatto, Pablo Guillermo. Universidad Nacional del Litoral; Argentin

O Instituto de Pesquisa Científica e Técnica para a Defesa (CITEDEF): história e presente

El Instituto de Investigaciones Científicas y Técnicas para la Defensa (CITEDEF) es un organismo que tiene un rol esencial en el desarrollo de tecnologías críticas para la Argentina. Desde su creación en 1954, se ha dedicado principalmente a atender los requerimientos de las Fuerzas Armadas, pero también ha generado numerosos proyectos dirigidos al conjunto de la sociedad, con beneficios que alcanzan a toda la población. En este artículo, se realiza un recorrido histórico desde su creación hasta su situación actual, en el que se repasan los principales logros de la institución, su desempeño en contextos de emergencia nacional como la Guerra de Malvinas y la pandemia por COVID-19, sus principales proyectos en ejecución y las proyecciones a futuro.The Institute of Scientific and Technical Research for Defense (CITEDEF) is an organization with an essential role in the development of critical technologies for Argentina. Since its creation in 1954, it has been mainly dedicated to meet the requirements of the Armed Forces, but it has also generated many projects aimed at society as a whole, with benefits reaching the entire population. This article presents an historic overview of the Institute since its beginnings to its current situation, highlighting its most important accomplishments, its performance in contexts of national emergency (such as the Malvinas War or the COVID-19 pandemic), its main active projects, and its projections into the future.O Instituto de Pesquisa Científica e Técnica em Defesa (CITEDEF) é uma organização que desempenha um papel essencial no desenvolvimento de tecnologias críticas para a Argentina. Desde sua criação em 1954, tem se dedicado principalmente a atender as exigências das Forças Armadas, mas também tem gerado inúmeros projetos voltados para a sociedade como um todo, com benefícios que atingem toda a população. Neste artigo, retomamos a história do instituto desde sua criação até sua situação atual, revisando as principais realizações da instituição, seu desempenho em contextos de emergência nacional como a Guerra das Malvinas e a pandemia da COVID-19, seus principais projetos em andamento e projeções futuras.Cátedra Libre Ciencia, Política y Socieda

Universal model for the skin colouration patterns of neotropical catfishes of the genus Pseudoplatystoma

Fish skin colouration has been widely studied because it involves a variety of processes that are important to the broad field of the developmental biology. Mathematical modelling of fish skin patterning first predicted the existence of morphogens and helped to elucidate the mechanisms of pattern formation. The catfishes of the genus Pseudoplatystoma offer a good biological study model, since its species exhibit the most spectacular and amazing variations of colour patterns on the skin. They present labyrinths, closed loops (or cells), alternate spots and stripes, only spots and combinations of these. We have extended a well known mathematical model to study the skin of Pseudoplatystoma. The basic model is a two component, non-linear reaction diffusion system that presents a richness of bifurcations. The extended model assumes that there are two interacting cell/tissue layers in which morphogens diffuse and interact giving rise to the skin colouration pattern. We have found that by varying only two parameters we are able to accurately reproduce the distinct patterns found in all species of Pseudoplatystoma. The histological analysis of skin samples of two species of this genus, with different patterns, revealed differences on the disposition of the colouration cells that are consistent with our theoretical predictions.Fil: Scarabotti, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Govezensky, Tzipe. Universidad Nacional Autónoma de México; MéxicoFil: Bolcatto, Pablo Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; ArgentinaFil: Barrio, Rafael Ángel. Universidad Nacional Autónoma de México; Méxic

Modelización y estudio de la adsorción de tolueno en mordenitas dopadas con sodio

En este trabajo se presentan resultados de cálculos teóricos tendientes a analizar las geometrías y las energías de interacción en el problema de adsorción de tolueno sobre un tipo de zeolita modificada, la mordenita dopada con sodio. Los cálculos se realizaron utilizando el código fireball, que es una implementación tight-binding de la teoría de la funcional de la densidad. Los resultados, en un muy buen acuerdo con la evidencia experimental, indican que el grupo metilo del tolueno interactúa más fuertemente con sitios de oxígenos cercanos a cationes. También se encuentra una adsorción estable cuando la interacción se da entre los electrones π del anillo aromático con los propios cationes de sodio.Fil: Cabana García, Nancy Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; ArgentinaFil: Boix, Alicia Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Bolcatto, Pablo Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; Argentin

Strategies for COVID-19 vaccination under a shortage scenario: a geo-stochastic modelling approach

In a world being hit by waves of COVID-19, vaccination is a light on the horizon. However, the roll-out of vaccination strategies and their influence on the pandemic are still open questions. In order to compare the effect of various strategies proposed by the World Health Organization and other authorities, a previously developed SEIRS stochastic model of geographical spreading of the virus is extended by adding a compartment for vaccinated people. The parameters of the model were fitted to describe the pandemic evolution in Argentina, Mexico and Spain to analyze the effect of the proposed vaccination strategies. The mobility parameters allow to simulate different social behaviors (e.g. lock-down interventions). Schemes in which vaccines are applied homogeneously in all the country, or limited to the most densely-populated areas, are simulated and compared. The second strategy is found to be more effective. Moreover, under the current global shortage of vaccines, it should be remarked that immunization is enhanced when mobility is reduced. Additionally, repetition of vaccination campaigns should be timed considering the immunity lapse of the vaccinated (and recovered) people. Finally, the model is extended to include the effect of isolation of detected positive cases, shown to be important to reduce infections.Fil: Barreiro, Nadia Luisina. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa; ArgentinaFil: Ventura, Cecilia Ileana. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia de Física (Centro Atómico Bariloche); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Govezensky, T.. Universidad Nacional Autónoma de México; MéxicoFil: Nuñez, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Bolcatto, Pablo Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Matemática Aplicada del Litoral. Universidad Nacional del Litoral. Instituto de Matemática Aplicada del Litoral; Argentina. Ministerio de Defensa. Instituto de Investigaciones Científicas y Técnicas para la Defensa; ArgentinaFil: Barrio, R. A.. Universidad Nacional Autónoma de México; Méxic

Puntos cuánticos semiconductores : efectos de forma y confinamiento dieléctrico

En la actualidad, y gracias al avance de las técnicas experimentales, es posible construir puntos cuánticos semiconductores (PCs) con diversas geometrías (esférica, cúbica, piramidal) que en general están inmersos en una matriz con propiedades dieléctricas diferentes a las del propio PC. En este trabajo hemos estudiado el efecto combinado que tanto la forma como el confinamiento dieléctrico producen sobre las propiedades electrónicas de estos sistemas. Todas las propiedades fueron analizadas utilizando la aproximación de masa efectiva, suponiendo que el electrón y el hueco se encuentran confinados en el punto cuántico por barreras de potencial infinitas haciendo uso de la aproximación de confinamiento fuerte, que permite el cálculo de las interacciones a partir de un enfoque perturbativo. Encontramos que a pesar de que la densidad de cargas polarizadas sobre la superficie del PC cúbico es altamente inhomogénea, las propiedades electrónicas son prácticamente independientes de la forma para todo el rango de contraste dieléctrico consideradoThe combined effect of shape and dielectric mismatch between dot and matrix on several electronic properties of semiconductor quantum dots have been studied. In particular, the electronic properties that have been analyzed are the polarization self-energy corrections to single-particle energies, excitonic Coulomb energies, and Coulomb blockade energies. It has been found that, in spite of the highly non-homogeneous polarized charge density induced at the boundaries of the cubic quantum dot, the electronic properties are essentially independent on the dot shape for all the range of dielectric mismatchFil: Bolcatto, Pablo Guillermo. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche. Instituto Balseiro (CNEA-CAB). Río Negro. ArgentinaFil: Proetto, César Ramón. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche. Instituto Balseiro (CNEA-CAB). Río Negro. Argentin

Exploring the T–Θ phase diagram of S adsorbed on Au(111) substrate on the Θ = 0.5 ML line

Theoretical results for the adsorption of half of a monolayer of S on Au(111) are presented. The simulations were made using a density functional theory (DFT) tight binding approach combined with classical molecular dynamics at 800, 500, 300, 150 and 1 K. By considering a minimal $(2\times \sqrt{3})$ unit cell, two stable adsorbed phases are found: a dimeric one and another forming a rhomboidal structure depending on the preparation of the sample at high temperatures. Optimized calculations at T = 0 K indicate that the stability of the dimeric phase is due to the increase of the binding energies between sulfur atoms. Enforcing previous results (Gómez-Carrillo et al 2011 Phys. Chem. Chem. Phys. 13 461) it is verified that at high temperatures (T > 300 K) sulfur atoms have a high mobility which allows migration among different adsorption sites. The mobility decreases with the temperature and, as in the previous work, a thermal barrier of 25–30 meV is found. On enlarging the unit cell new agglomerates are found, in good agreement with experimental data.Fil: Gómez Carrillo, Sandra Carolina. Universidad Nacional del Litoral. Facultad de Ingenieria Quimica. Departamento de Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; ArgentinaFil: Bolcatto, Pablo Guillermo. Universidad Nacional del Litoral. Facultad de Ingenieria Quimica. Departamento de Fisica; Argentina. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; Argentin

Sulfur adsorbed (Q = 1=2) on gold (111) substrate

The adsorption of Q = 1=2 monolayer (ML) of S on Au(111) is calculated. The evolution of the positions of adatoms for 800 K, 500 K, 300 K, 150 K and 1 K is evaluated by using a density functional theory (DFT)-tight binding approach combined with classical molecular dynamics. For this coverage there is a controversy about the existence of superficial composite AuS or molecular aggregates. We find a configuration in which sulfur atoms form quasi-S2 superficial molecules with total energy very close to the monoatomic phase suggesting the coexistence of both configurations at room temperature. We find that the stability of the dimeric phase is due to the increase of the binding energies between sulfurs. In the other phase, the stabilization occur due to a formation of AuS dimers. At high temperatures (T> 300 K) sulfurs have high mobility which allows the migration among different adsorption sites. At low temperatures the mobility decreases and a thermal activation barrier of 25 30 meV can be estimated.Fil: Bolcatto, Pablo Guillermo. Universidad Nacional del Litoral. Facultad de Ingenieria Quimica. Departamento de Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; ArgentinaFil: Gómez Carrillo, Sandra Carolina. Universidad Nacional del Litoral. Facultad de Ingenieria Quimica. Departamento de Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; Argentin

Coexistence of sqrt(3)xsqrt(3) and quasi-linear phases of sulfur adsorbed Θ=1/3 on gold (111) substrate

We analyze with the aid of density functional theory and molecular dynamics simulations the adsorption of sulfur (S) on a Au(111) surface at different temperatures with a variety of geometries. We have found a new superficial phase in which sulfur atoms form a quasi-linear chain with energies very close to the expected. The results suggest the coexistence of both configurations at T 300 K) it was shown that the sulfur atoms have high mobility which allows their migration among different adsorption sites. At low temperatures, the mobility decreases and a thermal activation barrier of 25-30 meV can be estimated.Fil: Gómez Carrillo, Sandra Carolina. Universidad Nacional del Litoral. Facultad de Ingenieria Quimica. Departamento de Fisica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bolcatto, Pablo Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Física del Litoral; Argentina. Universidad Nacional del Litoral. Facultad de Ingenieria Quimica. Departamento de Fisica; Argentin