Study of structures, energies and vibrational frequencies of (O-2)(n)(+) (n=2-5) clusters by GGA and meta-GGA density functional methods

Using Generalized Gradient Approximation (GGA) and meta-GGA density functional methods, structures, binding energies and harmonic vibrational frequencies for the clusters O-4(+), O-6(+), O-8(+) and O-10(+) have been calculated. The stable structures of O-4(+), O-6(+), O-8(+) and O-10(+) have point groups D-2h, D-3h, D-4h, and D-5h optimized on the quartet, sextet, octet and dectet potential energy surfaces, respectively. Rectangular (D-2h) O-4(+) has been found to be more stable compared to trans-planar (C-2h) on the quartet potential energy surface. Cyclic structure (D-3h) of CA cluster ion has been calculated to be more stable than other structures. Binding energy (B.E.) of the cyclic O-6(+) is in good agreement with experimental measurement. The zero-point corrected B.E. of O-8(+) with D4h symmetry on the octet potential energy surface and zero-point corrected B.E. of O-10(+) with D-5h symmetry on the dectet potential energy surface are also in good agreement with experimental values. The B.E. value for O-4(+) is close to the experimental value when single point energy is calculated by Brueckner coupled-cluster method, BD(T). (C) 2014 Elsevier B.V. All rights reserved.

Excited electronic state decomposition mechanisms of clusters of dimethylnitramine and aluminum

In this report, electronically non-adiabatic decomposition pathways of clusters of dimethylnitramine and aluminum (DMNA-Al and DMNA-Al-2) are discussed in comparison to isolated dimethylnitramine (DMNA). Electronically excited state processes of DMNA-Al and DMNA-Al-2 are explored using the complete active space self-consistent field (CASSCF) and the restricted active space self-consistent field (RASSCF) theories, respectively. Similar to the nitro-nitrite isomerization reaction pathway of DMNA, DMNA-Al-n clusters also exhibit isomerization pathway. However, it involves several other steps, such as, first Al-O bond dissociation, then N-N bond dissociation followed by isomerization and finally NO elimination. Furthermore, DMNA-Al-n clusters exhibit overall exothermic decomposition reaction pathway and isolated DMNA shows overall endothermic reaction channel.

High indium non-polar InGaN clusters with infrared sensitivity grown by PAMBE

Studies on the optical properties of InGaN alloy of relatively higher indium content are of potential interest to understand the effect of indium content on the optical band gap of epitaxial InGaN. We report the growth of self assembled non-polar high indium clusters of In0.55Ga0.45N over non-polar (11-20) a-plane In0.17Ga0.83N epilayer grown on a-plane (11-20) GaN/(1-102) r-plane sapphire substrate using plasma assisted molecular beam epitaxy (PAMBE). Such structures are potential candidates for high brightness LEDs emitting in longer wavelengths. The high resolution X-ray diffraction studies revealed the formation of two distinct compositions of InxGa1-xN alloys, which were further confirmed by photoluminescence studies. A possible mechanism for the formation of such structure was postulated which was supported with the results obtained by energy dispersive X-ray analysis. The structure hence grown when investigated for photo-detecting properties, showed sensitivity to both infrared and ultraviolet radiations due to the different composition of InGaN region. (C) 2015 Author(s).

On the ultrafast charge migration and subsequent charge directed reactivity in Cl center dot center dot center dot N halogen-bonded clusters following vertical ionization

In this article, we have presented ultrafast charge transfer dynamics through halogen bonds following vertical ionization of representative halogen bonded clusters. Subsequent hole directed reactivity of the radical cations of halogen bonded clusters is also discussed. Furthermore, we have examined effect of the halogen bond strength on the electron-electron correlation-and relaxation-driven charge migration in halogen bonded complexes. For this study, we have selected A-Cl (A represents F, OH, CN, NH2, CF3, and COOH substituents) molecules paired with NH3 (referred as ACl:NH3 complex): these complexes exhibit halogen bonds. To the best of our knowledge, this is the first report on purely electron correlation-and relaxation-driven ultrafast (attosecond) charge migration dynamics through halogen bonds. Both density functional theory and complete active space self-consistent field theory with 6-31+G(d, p) basis set are employed for this work. Upon vertical ionization of NCCl center dot center dot center dot NH3 complex, the hole is predicted to migrate from the NH3-end to the ClCN-end of the NCCl center dot center dot center dot NH3 complex in approximately 0.5 fs on the D-0 cationic surface. This hole migration leads to structural rearrangement of the halogen bonded complex, yielding hydrogen bonding interaction stronger than the halogen bonding interaction on the same cationic surface. Other halogen bonded complexes, such as H2NCl:NH3, F3CCl:NH3, and HOOCCl:NH3, exhibit similar charge migration following vertical ionization. On the contrary, FCl:NH3 and HOCl:NH3 complexes do not exhibit any charge migration following vertical ionization to the D-0 cation state, pointing to interesting halogen bond strength-dependent charge migration. (C) 2015 AIP Publishing LLC.

Boron clusters in luminescent materials

In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed.

Stabilization of Cu-7 clusters in azide networks: syntheses, structures and magnetic behaviour

Two new azide bridged copper(II) coordination polymer compounds, Cu-7(N-3)(14)(C3H10N2)(C4H13N3)]n (I) and Cu-7(N-3)(14)(C3H10N2)(C5H15N3)(2)](n) (II) where C3H10N2 = 1,2-diaminopropane (1,2-DAP); C4H13N3 = di-ethylenetriamine (DETA); C5H15N3 = N-2-aminoethyl-1,3-propanediamine (AEDAP)] were prepared by employing a room temperature diffusion technique involving three layers. Single crystal studies reveal that both compounds I and II, have similar connectivity forming Cu7 clusters through end-on (EO) bonding of the azide. The Cu-7 clusters are connected through end-to-end (EE) connectivity of the azides forming three-dimensional structures. Magnetic studies confirmed the ferromagnetic interactions within the Cu-7 units and revealed the occurrence of concomitant ferro- and antiferro-magnetic interactions between these clusters. As a result I behaves as a weak-ferromagnet with T-C = 10 K.

Experimental Study on Dynamic Properties of High Strength Fiber Clusters

In this paper, the dynamic behaviors of several kinds of high strength fibers, including Kevlar, UHMPE, glass fibers, carbon fibers etc., are investigated experimentally, with a Split Hopkinson Tension Bar (SHTB). The effect of strain rate on the modulus, strength, failure strain and failure characteristics of fibers, under impact loading, is analyzed with the relative stress vs. strain curves. At the same time, the mechanism about the rate dependence of mechanical behaviors of various fibers is discussed based on the understanding on the microstructures and deformation models of materials. Some comments are also presented on the decentralization of experimental results, and a new method called traveling wave method is presented to increase the experimental accuracy. Research results obtained in this paper will benefit to understand the energy absorption and to build up the constitutive law of protective materials reinforced by high strength fibers.

Stability Of Adhesion Clusters And Cell Reorientation Under Lateral Cyclic Tension

This work is motivated by experimental observations that cells on stretched substrate exhibit different responses to static and dynamic loads. A model of focal adhesion that can consider the mechanics of stress fiber, adhesion bonds, and substrate was developed at the molecular level by treating the focal adhesion as an adhesion cluster. The stability of the cluster under dynamic load was studied by applying cyclic external strain on the substrate. We show that a threshold value of external strain amplitude exists beyond which the adhesion cluster disrupts quickly. In addition, our results show that the adhesion cluster is prone to losing stability under high-frequency loading, because the receptors and ligands cannot get enough contact time to form bonds due to the high-speed deformation of the substrate. At the same time, the viscoelastic stress fiber becomes rigid at high frequency, which leads to significant deformation of the bonds. Furthermore, we find that the stiffness and relaxation time of stress fibers play important roles in the stability of the adhesion cluster. The essence of this work is to connect the dynamics of the adhesion bonds (molecular level) with the cell's behavior during reorientation (cell level) through the mechanics of stress fiber. The predictions of the cluster model are consistent with experimental observations.

Vacancy clusters in ultrafine grained Al by severe plastic deformation

Bulk nanostructured metals are often formed via severe plastic deformation (SPD). The dislocations generated during SPD evolve into boundaries to decompose the grains. Vacancies are also produced in large numbers during SPD, but have received much less attention. Using transmission electron microscopy, here we demonstrate a high density of unusually large vacancy Frank loops in SPD-processed Al. They are shown to impede moving dislocations and should be a contributor to strength. (C) 2007 American Institute of Physics.

Los clusters como fuente de competitividad: el caso de la Comunidad Autónoma del País Vasco

Ponencia aceptada y defendida en la XIII Jornadas Hispano-Lusas de Gestión Científica celebradas en Lugo en febrero de 2003.

Marketing de los servicios sociales: el caso de los centros residenciales para personas mayores

En el ámbito de los Servicios Sociales, y más concretamente en el caso de los centros residenciales para personas mayores, se puede afirmar que,hasta hace poco tiempo, el marketing no ha tenido demasiada presencia. En este trabajo queremos señalar la conveniencia de utilizar diferentes herramientas de marketing, adaptándolas a las características de estas organizaciones, y destacar el papel que juega la opinión de los usuarios, sus percepciones y los juicios que realizan sobre los servicios recibidos a la hora de proponer acciones de mejora en la atención prestada. En este sentido, señalaremos la necesidad de que se implante en las residencias para personas mayores un procedimiento sencillo que permita la obtención de información relativa a la satisfacción de los usuarios y sus familiares con los servicios recibidos para, de esta manera, emprender acciones que posibiliten avanzar en una mejor calidad asistencial.

Gestión de la calidad y marketing en los centros residenciales para personas mayores

El sector residencial se está introduciendo en una cultura de gestión que en el pasado reciente no existía. Sin embargo, resulta curioso que muchas residencias hayan descubierto el enfoque de satisfacción del cliente a través de los modelos de gestión de la calidad mientras que la actividad de marketing no es considerada relevante. Al igual que otros autores, pensamos que el marketing y la gestión de la calidad son filosofías de gestión complementarias. En el presente trabajo de investigación nos hemos planteado como objetivo principal describir y explicar la relación existente entre la gestión de la calidad y la filosofía de marketing en los centros residenciales para personas mayores. La consecución de este objetivo principal se realiza a través del desarrollo, entre otros, de los siguientes objetivos subsidiarios: Evaluación de la incidencia de la adopción en el sector de los principales modelos, genéricos y específicos, de gestión de la calidad, examinando cuáles han sido las motivaciones para su implantación; Estudio del nivel de utilización de instrumentos de gestión y de actividades de marketing en el sector; Diseño y validación de escalas que permiten evaluar el grado en el que las residencias para personas mayores adoptan los principios de la gestión de la calidad y medir su nivel de orientación al mercado; Determinación de la relación existente entre los conceptos de gestión de la calidad y orientación al mercado, así como entre los diferentes componentes de la gestión de la calidad y la orientación al mercado, en el sector objeto de estudio.Por último, hemos generado una serie de propuestas integradoras e innovadoras que resultarán útiles para los gestores de residencias. Estas propuestas se concretan, por un lado, en una serie de recomendaciones relativas a la utilización de instrumentos de gestión y herramientas de marketing ajustados a las organizaciones del sector y, por otro lado, en el desarrollo de un modelo de gestión de la calidad que, tomando los aspectos que consideramos adecuados de los modelos estudiados, se adapta mejor a la realidad de las organizaciones estudiadas.

Situación de la salud materno-perinatal en 2 Centros de Salud de Bizkaia

Introducción: La salud reproductiva y, en concreto, todos los aspectos relacionados con los cuidados de salud durante el embarazo, son temas de especial relevancia, tanto para la sociedad como para los servicios sanitarios. De modo que es necesario asegurar una adecuada atención de la mujer durante el embarazo, parto y postparto. Objetivo: Analizar y determinar la satisfacción de las mujeres con el seguimiento de su embarazo (gestación, parto y postparto) y comparar las diferencias existentes entre los 2 Centros de Salud (C.S) en los que se ha realizado dicho seguimiento. Metodología: Se realizó un estudio a 32 mujeres atendidas en los C.S. de Bombero-Etxaniz y Arrigorriaga, en el periodo transcurrido entre el 15 de enero del 2013 y el 15 de marzo del 2013; las encuestas se llevaron a cabo en el primer trimestre postparto. Se desarrolló un análisis descriptivo de los datos y un estudio de asociación entre las diferentes variables. Resultados: La media de edad de las mujeres estudiadas se situó en 34,75; se encontró asociación entre la edad y los embarazos de riesgo. El 50% de los partos fueron eutócicos; se estableció relación con la edad y la paridad. A más del 50% de ellas se les realizó una episiotomía, buscando una relación con el hospital se halló que cuanto más grande era el hospital más episiotomías se realizaban. Así mismo las encuestadas mostraron una mayor satisfacción con la atención prestada por los centros hospitalarios privados; en referencia a los C.S. no se hallaron diferencias significativas, mostrando en ambos casos una satisfacción subjetiva percibida alta. Conclusiones: Los cambios sociales, culturales, económicos e ideológicos ocurridos han favorecido el aumento de la edad materna y consigo el aumento de embarazos de riesgo, además de la disminución de la media del número de hijos. Se aprecia una necesidad en materia de apoyo e información a las mujeres en el periodo postparto debido al gran cambio personal, físico, social y psicológico que puede suponer.