Competition between electron and phonon excitations in the scattering of nitrogen atoms and molecules off tungsten and silver surfaces

We investigate the role played by electron-hole pair and phonon excitations in the interaction of reactive gas molecules and atoms with metal surfaces. We present a theoretical framework that allows us to evaluate within a full-dimensional dynamics the combined contribution of both excitation mechanisms while the gas particle-surface interaction is described by an ab-initio potential energy surface. The model is applied to study energy dissipation in the scattering of N$_2$ on W(110) and N on Ag(111). Our results show that phonon excitation is the dominant energy loss channel whereas electron-hole pair excitations represent a minor contribution. We substantiate that, even when the energy dissipated is quantitatively significant, important aspects of the scattering dynamics are well captured by the adiabatic approximation.Comment: 4pages and 3 figure

Profile and reproductive roles of seminal plasma melatonin of boar ejaculates used in artificial insemination programs

Melatonin (MLT) is present in seminal plasma (SP) of mammalian species, including pigs, and it is credited with antioxidant properties. This study aims to identify the sources of variation and the role of boar SP MLT on sperm quality and functionality and in vivo fertilizing ability of liquid-stored semen doses used in AI programs. The SP MLT was measured using an ELISA kit in a total of 219 ejaculates collected from 76 boars, and reproductive records of 5,318 AI sows were recorded. Sperm quality was assessed according to motility (computer-aided sperm analysis) and viability (cytometry evaluation). Sperm functionality was assessed according to the cytometric determination of intracellular H2O2 generation, total and mitochondrial O2- production, and lipid peroxidation in liquid AI semen samples stored at 17°C over 144 h. The concentration of SP MLT differed among seasons (P < 0.01) and day length periods (P < 0.001) of the year, demonstrating that the ejaculates collected during the increasing day length period (9.80 ± 1.38 pg/mL, range: 2.75–21.94) had lower SP MLT concentrations than those collected during the decreasing day length period (16.32 ± 1.67 pg/mL, range: 5.02–35.61). The SP MLT also differed (P < 0.001) among boars, among ejaculates within boar, and among portions within the ejaculate, demonstrating that SP from the first 10 mL of sperm-rich ejaculate fraction (SRF) exhibited lower MLT concentrations than post-SRF. The SP MLT was negatively related (P < 0.001) to mitochondrial O2- production in viable sperm. The SP MLT did not differ among AI boars (n = 14) hierarchically grouped according to high and low fertility outcomes. In conclusion, SP MLT concentration in AI boars varies depending on the season of ejaculate collection and differs among boars, ejaculates within boar, and portions within ejaculate. The SP MLT may act at the mitochondrial level of sperm by reducing the generation of O2-. However, this antioxidant role of SP MLT was not reflected in sperm quality or in vivo fertility outcomes of AI semen doses

Non-adiabatic effects during the dissociative adsorption of O2 at Ag(111)? A first-principles divide and conquer study

We study the gas-surface dynamics of O2 at Ag(111) with the particular objective to unravel whether electronic non-adiabatic effects are contributing to the experimentally established inertness of the surface with respect to oxygen uptake. We employ a first-principles divide and conquer approach based on an extensive density-functional theory mapping of the adiabatic potential energy surface (PES) along the six O2 molecular degrees of freedom. Neural networks are subsequently used to interpolate this grid data to a continuous representation. The low computational cost with which forces are available from this PES representation allows then for a sufficiently large number of molecular dynamics trajectories to quantitatively determine the very low initial dissociative sticking coefficient at this surface. Already these adiabatic calculations yield dissociation probabilities close to the scattered experimental data. Our analysis shows that this low reactivity is governed by large energy barriers in excess of 1.1 eV very close to the surface. Unfortunately, these adiabatic PES characteristics render the dissociative sticking a rather insensitive quantity with respect to a potential spin or charge non-adiabaticity in the O2-Ag(111) interaction. We correspondingly attribute the remaining deviations between the computed and measured dissociation probabilities primarily to unresolved experimental issues with respect to surface imperfections.Comment: 18 pages including 6 figure

Expresión inmunohistoquímica de p53 en individuos con liquen

Objetivo: Estimar el riesgo del potencial de malignización del liquen plano bucal analizando la expresión de la proteína p53. Materiales y metodos: Se realizó un diseño de cohorte de sujetos con diagnostico histopatológico de liquen. El desenlace fue el desarrollo de cáncer si/no. El total de individuos que cumplió con los criterios de inclusión/exclusión fue de 58. A los 58 sujetos se les realizó la determinación de p53. Resultados: Cuarenta y nueve individuos mostraron una expresión de p53 menor al 5% con una P>0,05% intrasujeto no transformado. En los 9 individuos transformados se observaron diferencias significativas entre la determinación pre y post de la proteína p53. El Riesgo Relativo fue de 188 con una significación estadística de P0.05 among subjects undergoing no transformation. In the 9 subjects undergoing malignant transformation, significant differences were observed between pre and post p53 expression. The relative risk was 188, with a statistical significance of p5% are associated with an increased risk of malignant transformation of this condition. Should our findings be proved in a larger series in the future, the clinical follow-up of these subjects could be modified. This would allow an early diagnosis of any disorder indicative of a potential malignant transformation.Fil: Muiño, A.. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Adler, I.. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Lence, A.. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Harada, L.. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Nieto, S.. Centro de Educaciones Médicas e Investigación Clínica "Norberto Quirno"; ArgentinaFil: Denninghoff, Valeria Cecilia. Centro de Educaciones Médicas e Investigación Clínica "Norberto Quirno"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Avagnina, A.. Centro de Educaciones Médicas e Investigación Clínica "Norberto Quirno"; ArgentinaFil: Keszler, A.. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Lanfranchi, H.. Universidad de Buenos Aires. Facultad de Odontología; ArgentinaFil: Aguas, S.. Universidad de Buenos Aires. Facultad de Odontología; Argentin

Bienestar animal de corderos ternascos durante su espera en matadero

El presente trabajo consistió en valorar la respuesta de estrés al que son sometidos los corderos desde que llegan al matadero hasta su sacrificio en distintas épocas del año, primavera y verano. Se tomaron muestras de sangre durante el sacrificio del animal para la valoración de diferentes parámetros sanguíneos de respuesta de estrés y tras el faenado se valoró la calidad de la canal y de la carne de los corderos. Se encontraron diferencias significativas con mayores valores para los corderos sacrificados en verano en el número de linfocitos, lactato deshidrogenasa (LDH), cortisol y pHs y menores en el número de leucocitos, neutrófilos, relación neutrófilos/linfocitos, volumen corpuscular medio, concentración de glucosa y rendimiento de la canal. Los corderos sacrificados en verano tuvieron más comprometido su nivel de bienestar por el mayor nivel de cortisol y LDH junto con unos pHs más elevados, lo que hace que la calidad de la carne sea inferior a los sacrificados en primavera

Arquitectura corporativa de web services

Este proyecto consiste en la realización de un sistema informático que se encargue de ampliar la red comercial de una compañía de seguros a través de Internet. Para ello se utiliza la tecnología de web services, que nos permite efectuar transacciones de datos de manera rápida, fiable y segura. El web service que se ha diseñado se encarga de resolver y dar respuesta tanto a peticiones de solicitud de precios como de emisión de pólizas en varios ramos. El objetivo es ofrecer al cliente final un método sencillo y próximo de cotización y emisión de seguros.Aquest projecte consisteix en la realització d'un sistema informàtic que s'encarregui d'ampliar la xarxa comercial d'una companyia d'assegurances mitjançant Internet. Per a això s'utilitza la tecnologia de web services, que ens permet efectuar transaccions de dades de manera ràpida, fiable i segura. El web service que s'ha dissenyat s'encarrega de resoldre i donar resposta tant a peticions de sol·licitud de preus com d'emissió de pòlisses en diversos rams. L'objectiu es oferir al client final un mètode senzill i pròxim de cotització i emissió d'assegurances.This project consists of a computer based system to be responsible for expanding the business network of an insurance company via the Internet. It uses web services technology, which allows us to make data transactions in a fast, reliable and secure way. The web service that has been designed handles to resolve and respond to requests for prices solicitation and insurance policies emission in several classes. The aim is to give customers an easy and near way of trading and issuance insurances