RESUMO

The performance of local correlation methods is examined for the interactions present in clusters of bromine with water where the combined effect of hydrogen bonding (HB), halogen bonding (XB), and hydrogen-halogen (HX) interactions lead to many interesting properties. Local methods reproduce all the subtleties involved such as many-body effects and dispersion contributions provided that specific methodological steps are followed. Additionally, they predict optimized geometries that are nearly free of basis set superposition error that lead to improved estimates of spectroscopic properties. Taking advantage of the local correlation energy partitioning scheme, we compare the different interaction environments present in small clusters and those inside the 5(12)6(2) clathrate cage. This analysis allows a clear identification of the reasons supporting the use of local methods for large systems where non-covalent interactions play a key role.

RESUMO

A new ab initio potential energy surface for the ground state of the NO-NO system has been calculated within a reduced dimensionality model. We find an unusually large vibrational dependence of the interaction potential which explains previous spectroscopic observations. The potential can be used to model vibrational energy transfer, and here we perform quantum scattering calculations of the vibrational relaxation of NO(v). We show that the vibrational relaxation for v = 1 is 4 orders of magnitude larger than that for the related O(2)(v) + O(2) system without having to invoke nonadiabatic mechanisms as had been suggested in the past. For highly vibrationally excited states, we predict a strong dependence of the rates on the vibrational quantum number as has been observed experimentally, although there remain important quantitative differences. The importance of a chemically bound isomer on the relaxation mechanism is analyzed, and we conclude it does not play a role for the values of v considered in the experiment. Finally, the intriguing negative temperature dependence of the vibrational relaxation rate constants observed in experiments was studied using an statistical model to include the presence of many asymptotically degenerate spin-orbit states.

RESUMO

The local relaxation of solid neon subsequent to the impulsive excitation of the NO chromophore to its A(3s sigma) Ryberg state is investigated using molecular dynamics simulations. This study makes use of empirical NO(X,A)-Ne isotropic pair potentials as well as a recently developed ab initio triatomic potential energy surface for the excited state. The role of these interaction potentials is analyzed, including many-body effects. In particular, empirical potentials, designed to reproduce correctly both the NO X-A steady-state absorption and emission bands, are shown to lead to a good description of the subpicosecond relaxation dynamics. The 600 fs expansion of the electronic bubble fairly agrees with experimental data. This relatively long time scale with respect to solid Argon, which was previously attributed to the range of the NO(A)-Ne interaction, is presumably related to the quantum nature of the medium. The time-resolved local relaxation of the Ne solid is understandably intermediate between that of classical solids (e.g., Ar) and that of quantum solids (e.g., H(2)).

Assuntos

RESUMO

Se realizó un estudio de desarrollo tecnológico que permitió la elaboración de una estrategia de intervención para disminuir la prevalencia de la gingivitis crónica, principal problema de salud detectado en una previa investigación realizada en escolares de primaria entre 5 -10 años de edad pertenecientes a la zona urbana del municipio Bejucal entre los meses de abril y diciembre del 2006. Una vez identificado dicho problema de salud se construyó una matriz DAFO, precisando las fuerzas internas del sector de la salud fuerzas y debilidades y las fuerzas externas al sector oportunidades y amenazas; se confeccionó además un plan de acción y se propuso un sistema de evaluación para el despliegue de acciones de salud que susciten mejorar el estado de salud bucal y por tanto general de esta población (AU)

It was performed a study of technological development that enabled the development of an intervention strategy to reduce the prevalence of chronic gingivitis, which was the main health problem identified in a previous research conducted in primary schoolers aged 5 -10, belonging to the urban area of Bejucal municipality between April and December 2006. Once the health problem was identified a SWOT matrix was built, specifying the internal forces in the health sector strengths and weaknesses and the external forces of the sector opportunities and threats it was also prepared an action plan and an evaluation system was proposed for the deployment of health actions that give rise to improve the buccal health status and therefore general of this population (AU)

Assuntos

RESUMO

Se estudió la efectividad terapéutica del Tisuacryl en el tratamiento de los Traumatismos de la Mucosa Bucal y la Hiperestesia Dentinaria. Se realizó un ensayo clínico fase III controlado, abierto, aleatorisado y unicéntrico, donde el universo estuvo constituido por todos los pacientes que asistieron a la consulta de urgencia en la Clínica Estomatológica del municipio Bejucal y la muestra estuvo conformada por 10 sujetos que presentaron Traumas de la Mucosa Bucal y 30 con Hiperestesia Dentinaria en el período comprendido desde octubre del 2005 hasta septiembre del 2006. Se evaluó el efecto hemostático a los 5-15 minutos y el comportamiento de la cicatrización a los 30 días en los Traumatismos de la Mucosa Bucal, la inhibición del dolor en la Hiperestesia Dentinaria, la conformidad de los pacientes e investigadora con el tratamiento recibido, así como la presentación o no de eventos adversos. La aplicación del adhesivo fue satisfactoria en ambas entidades, constituyendo este una alternativa más de tratamiento(AU)

Assuntos