Sunday, May 24, 2015

 

 



Soy un nuevo usuario

Olvidé mi contraseña

Entrada usuarios

Lógica Matemáticas Astronomía y Astrofísica Física Química Ciencias de la Vida
Ciencias de la Tierra y Espacio Ciencias Agrarias Ciencias Médicas Ciencias Tecnológicas Antropología Demografía
Ciencias Económicas Geografía Historia Ciencias Jurídicas y Derecho Lingüística Pedagogía
Ciencia Política Psicología Artes y Letras Sociología Ética Filosofía
 

rss_1.0 Clasificación por Disciplina

Nomenclatura Unesco > (22) Física > (2206) Física molecular
(2206.01) Radicales libres (2206.02) Moléculas inorgánicas
(2206.03) Macromoléculas (2206.04) Moléculas mesónicas y muónicas
(2206.05) Haces moleculares (2206.06) Iones Moleculares
(2206.07) Espectroscopia molecular (2206.08) Estructura molecular
(2206.09) Moléculas orgánicas (2206.10) Polímeros
(2206.99) Otras (especificar)

Mostrando recursos 1 - 20 de 181

1. Effects of site-occupation disorder on the low-temperature thermal conductivity of molecular crystals - Krivchikov, Alexander I; Vdovichenko, Georgii A.; Korolyuk, O. A.; Bermejo, F. Javier; Pardo Soto, Luis Carlos; Tamarit Mur, José Luis; Jezowski, Andrzej; Szewczyk, Daria
The thermal conductivity of CBrnCl4-n,(n = 0,1,2) and 2-adamantanone (C10H14O) crystals which exhibit substitutional disorder has been measured for temperatures between 2 K and 150 K. Such temperatures comprise signatures of dynamical processes involving the site occupancy of the chlorine and bromine atoms for CBrnCl4-n,(n = 0,1,2) and the oxygen atom for (C10H14O), as it has been revealed by both, calorimetry and spectroscopic techniques. The data analysis is carried out in terms of several phonon scattering channels contributing to a resistive relaxation rate which can be represented by two contributions due to propagating phonons whose mean-free path exceeds half the...

2. Multiple active zones in hybrid QM/MM molecular dynamics simulations for large biomolecular systems - Torras Costa, Juan
A new QM/MM molecular dynamics approach that can deal with the dynamics of large real systems involving several simultaneous active zones is presented. Multiple, unconnected but interacting quantum regions are treated independently in an ordinary QM/MM approach but in a manner which converges to a unique simulation. The multiple active zones in the hybrid QM/MM molecular dynamics methodology (maz-QM/MM MD) involve molecular dynamics that is driving the whole simulation with several parallel executions of energy gradients within the QM/MM approach that merge into each MD step. The Ewald-summation method is used to incorporate long-range electrostatic interactions among the active zones...

3. Caracterização físico-química e molecular de genótipos de maracujá azedo cultivados no Distrito Federal - Greco, Sther Maria Lenza
Tese (doutorado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Agronomia, 2014.

4. Nanopatterned Graphene on a Polymer Substrate by a Direct Peel-off Technique - Chen, T. L.; Ghosh, D. S.; Marchena, M.; Osmond, J.; Pruneri, Valerio
: A graphene (Gr) on a polyimide (PI) polymer film (Gr−PI film), obtained by a direct peel-off technique, is proposed and investigated. Thanks to its high transparency, electrical conductivity, mechanical strength, and chemical durability, the Gr−PI film is an ideal substrate for flexible electronic and optoelectronic devices, including transistors, lightemitting diodes, and plasmonic antennas. It is obtained using a straightforward method. After spin coating and curing a PI film on Gr previously grown on Cu, one can separate the Gr−PI film from the Cu foil thanks to the difference in the adhesive energy between the Gr−Cu and Gr−PI interfaces. The resulting Gr−PI film shows an average electrical sheet resistance ranging from...

5. La hipérbola como parábola del papel de la simetría en el entendimiento y la mejora de materiales altamente energéticos - Noheda Martín, Pedro
Conferencia presentada en el Seminario del Departamento de Física Atómica, Molecular y de Agregados (FAMA, IFF) del CSIC. Miércoles 12 de Febrero de 2014

6. Cinco aportaciones a la implantología oral: De la rotura de los dogmas a la frontera del conocimiento - Gil Mur, Francisco Javier
En este artículo pretendo mostrar cinco de las más destacadas aportaciones que nuestro centro de investigación ha realizado a la Implantología Oral. Nuestro centro está compuesto por 35 investigadores de diferentes disciplinas: ingenieros, físicos, químicos, biólogos celulares, biólogos moleculares, microbiólogos, histólogos, clínicos, estadísticos; este hecho singular nos permite abordar proyectos multidisciplinares, especialmente en materiales substitutivos de tejidos duros, y más concretamente en la Implantología Oral. Nuestro centro está abierto a los diferentes temas de investigación y siempre pensamos que el protagonista es el clínico ya que es él quién se enfrenta al problema que presenta el paciente. Nuestra función es...

7. Differentiation with Raman spectroscopy among several natural ultramarine blues and the synthetic ultramarine blue used by the Catalonian modernist painter Ramon Casas i Carbo - Ramos de Torres, Antonio; Ruiz Moreno, Sergio; Lopez Gil, A; Ferrer, Pere; Chillon, M.C
This paper investigates, using only Raman spectroscopy, the spectral differences among the synthetic ultramarine blue (J. B. Guimet) and three natural ultramarine blues (lazurites) corresponding to three lapis lazulis from different geographical sources (Chile, Afghanistan and Siberia). The synthetic ultramarine blue used as reference pigment is the identified in an artwork created around 1917 by the Catalonian modernist painter Ramon Casas i Carbo. This synthetic pigment is compared with the three natural ultramarine blues and, in his turn, the latter are also compared each other. In order to quantify the spectral differences, a rigorous methodology based on the Euclidean distance...

8. A continuous mixture of two different dimers in liquid water - Pardo Soto, Luis Carlos; Henao Aristizábal, Andrés; Busch, Sebastian; Guàrdia Manuel, Elvira; Tamarit Mur, José Luis
It is hitherto thought that liquid water is composed of tetrahedrally coordinated molecules with an asymmetric interaction of the central molecule with neighboring molecules. Kuhne et al., Nat. Commun., 2013, 4, 1450 suggested that this asymmetry, energetic rather than geometric, is the cornerstone to reconcile the homogeneous and inhomogeneous viewpoints of liquid water. In order to investigate the geometric origin of that asymmetry, we have scrutinized Molecular Dynamics (MD) simulations of water through a careful analysis of the five-dimensional probability distribution function of Euler angles in which the relative positions and orientations of water molecules are obtained. We demonstrate that,...

9. Influencia del medio en la reacción de oxidación del ioduro con peroxidisulfato - Carmona Guzmán, María del Carmen
Aunque los efectos del disolvente sobre la reactividad q uímica son conocidos desde el siglo pasado, no existen métodos exactos que den una descripción cuantitativa de tales efectos. Son numerosos los trabajos, entre los que citaremos el de Abraham, realizados en disolventes puros, distintos del agua, así como en mezclas de ésta con disolventes orgánicos, con el fin de elucidar alguna relación reactividad-medio. Intentando aportar luz al problema, hemos estudiado la oxidación del ión ioduro con peroxidisulfato en distintas mezclas agua-disolvente orgánico. Se ha elegido esta reacción porque en ella se produce una variación de la distribución de carga de los...

10. Herramientas mecano-cuánticas basadas en DFT para el estudio de moléculas y materiales en Materials Studio 7.0 - Ramos, Javier
Materials Studio 7.0 proporciona una serie de herramientas basadas en la mecánica cuántica para estudiar moléculas y estructuras periódicas. Entre ellas incluye herramientas basadas en DFT, QM/MM, escalado linear y método semiempíricos. Estas herramientas permiten calcular de forma precisa la estructura molecular así como propiedades termo-físicas, electrónicas y ópticas de materiales. En este “webinar”, se centrará en la teoría de los funcionales de la densidad (DFT) dando una muy breve introducción teórica de los métodos DFT junto con una revisión de las principales características implementadas en MS 7.0. En particular se revisaran los módulos DMOL3, CASTEP y ONETEP. Se usarán...

11. Hardware simulator for optical correlation spectroscopy with Gaussian statistics and arbitrary correlation functions - Molteni, Matteo; Weigel, Udo M.; Remiro, Francisco; Durduran, Turgut; Ferri, Fabio
We present a new hardware simulator (HS) for characterization, testing and benchmarking of digital correlators used in various optical correlation spectroscopy experiments where the photon statistics is Gaussian and the corresponding time correlation function can have any arbitrary shape. Starting from the HS developed in [Rev. Sci. Instrum. 74, 4273 (2003)], and using the same I/O board (PCI-6534 National Instrument) mounted on a modern PC (Intel Core i7-CPU, 3.07GHz, 12GB RAM), we have realized an instrument capable of delivering continuous streams of TTL pulses over two channels, with a time resolution of Δt = 50ns, up to a maximum count...

12. Sinergia y pertinencia en las ciencias básicas - Duque Escobar, Gonzalo

13. Interacciones entre plantas y microorganismos del suelo: Consecuencias para la dinámica de comunidades vegetales - Lozano Bernal, Yudi M.
En esta tesis doctoral pretendemos aclarar aspectos fundamentales relacionados con la interacción entre plantas y microorganismos del suelo y sus consecuencias para la dinámica de las comunidades vegetales. Pretendemos comprobar si las comunidades microbianas están determinando interacciones negativas y/o positivas entre plantas; si tras el abandono de tierras dedicadas al cultivo, las plantas y los microorganismos del suelo siguen patrones sucesionales, y si los microorganismos asociados a las especies vegetales son los que determinan su éxito competitivo en una comunidad vegetal. Para evaluar esto realizamos diferentes experimentos en campo y en invernadero apoyados por una serie de análisis físicos, químicos, biológicos y moleculares del suelo y de...

14. Scaling Dalton: a molecular electronic structure program - Aguilar, Xavier; Schliepake, Michael; Vahtras, Olav; Giménez Lucas, Judit; Laure, Erwin
Dalton is a molecular electronic structure program featuring common methods of computational chemistry that are based on pure quantum mechanics (QM) as well as hybrid quantum mechanics/molecular mechanics (QM/MM). It is specialized and has a leading position in calculation of molecular properties with a large world-wide user community (over 2000 licenses issued). In this paper, we present a characterization and performance optimization of Dalton that increases the scalability and parallel efficiency of the application. We also propose a solution that helps to avoid the master/worker design of Dalton to become a performance bottleneck for larger process numbers and increase the...

15. Complejidad física y química en la nube molecular orión KL - Bañó Esplugues, Gisela

16. Dynamical sectors for a spinning particle in AdS(3) - Batlle Arnau, Carles; Gomis, Jaoquim; Kamimura, kiyoshi; Zanelli, Jorge
We consider the dynamics of a particle of mass M and spin J in AdS(3). The study reveals the presence of different dynamical sectors depending on the relative values of M, J and the AdS(3) radius R. For the subcritical (MR2)-R-2 - J(2) > 0 and supercritical (MR2)-R-2 - J(2) < 0 cases, it is seen that the equations of motion give the geodesics of AdS(3). For the critical case (MR2)-R-2 = J(2) there exist extra gauge transformations which further reduce the physical degrees of freedom, and the motion corresponds to the geodesics of AdS(2). This result should be useful...

17. Introducing electron capture into the unitary-convolution-approximation energy-loss theory at low velocities - Schiwietz, Gregor; Grande, Pedro Luis
Recent developments in the theoretical treatment of electronic energy losses of bare and screened ions in gases are presented. Specifically, the unitary-convolution-approximation (UCA) stopping-power model has proven its strengths for the determination of nonequilibrium effects for light as well as heavy projectiles at intermediate to high projectile velocities. The focus of this contribution will be on the UCA and its extension to specific projectile energies far below 100 keV/u, by considering electron-capture contributions at charge-equilibrium conditions.

18. Experimental and theoretical study of the energy loss of C and O in Zn - Cantero, Esteban Daniel; Montanari, Claudia C.; Behar, Moni; Fadanelli Filho, Raul Carlos; Lantschner, G.H.; Miraglia, Jorge E.; Arista, Nestor
We present a combined experimental-theoretical study of the energy loss of C and O ions in Zn in the energy range 50–1000 keV/amu. This contribution has a double purpose, experimental and theoretical. On the experimental side, we present stopping power measurements that fill a gap in the literature for these projectiletarget combinations and cover an extended energy range, including the stopping maximum. On the theoretical side, we make a quantitative test on the applicability of various theoretical approaches to calculate the energy loss of heavy swift ions in solids. The description is performed using different models for valence and inner-shell...

19. Energy loss of proton, [alpha] particle, and electron beams in hafnium dioxide films - Behar, Moni; Fadanelli Filho, Raul Carlos; Abril Sanches, Isabel; García-Molina, Rafael; Denton, Cristian D.; Nagamine, Luiz Carlos Camargo Miranda; Arista, Nestor
The electronic stopping power, S, of HfO₂ films for proton and alpha particle beams has been measured and calculated. The experimental data have been obtained by the Rutherford backscattering technique and cover the range of 120–900 and 120–3000 keV for proton and alpha particle beams, respectively. Theoretical calculations of the energy loss for the same projectiles have been done by means of the dielectric formalism using the Mermin energy loss function—generalized oscillator strength (MELF-GOS) model for a proper description of the HfO₂ target on the whole momentum-energy excitation spectrum. At low projectile energies, a nonlinear theory based on the extended...

20. Experimental and theoretical study of the energy loss of Be and B ions in Zn - Cantero, Esteban Daniel; Fadanelli Filho, Raul Carlos; Montanari, Claudia C.; Behar, Moni; Eckardt, J. C.; Lantschner, G.H.; Miraglia, Jorge E.; Arista, Nestor
Energy-loss measurements and theoretical calculations for Be and B ions in Zn are presented. The experimental ion energies range from 40 keV/u to 1 MeV/u, which includes the energy-loss maximum and covers a lack of experimental data for these systems from intermediate to high energies. The measurements were performed using the Rutherford backscattering technique. The ab initio calculations are based on the extended Friedel sum rule–transport cross-section method for the valence electrons and the Shellwise local plasma approximation for the bound electrons. A comparison of these calculations to the present experimental data for Be and B and previous values for...

Página de resultados:
 

Busque un recurso