The luminescence of Eu2+ in mixed phase system

The dependence of the structure of the hosts on the M ion radius in MMgAl10O17 (M = Be, Mg, Ca, Sr, Ba, Pb, Eu, Mn, Fe, Co, Ni, Zn, Cd, Sn) system was studied and the luminescence of Eu2+ the mixed phase system was discussed. When M ion radius is less than 0.10 nm, the system MMgAl10O17 constructs by the mixed phases consisting of manegtoplumbite and spinel, alpha-alumina or spinel and alpha-alumina. In the mixed phase of manegtoplumbite and spinel and alpha-alumina, Eu2+ ion preferentially occupies lattice site of the cations in manegtoplumbite well matched with the radius and charge of Eu2+. There exists only d-->f transition emission of Eu2+ and no characteristic emission of Eu3+ occurs in those hosts. In the mixed phase of spinel and alpha-alumina, Eu2+ can enter the lattice site of Mg2+ ion or Al3+ ion and the d-->f and f-->f transition of Eu2+ can been observed respectively. Meanwhile, since the radius and charge of matrix lattice ions substituted by Eu2+ do not match with those of Eu2+, the valence state of Eu2+ is unstable. Eu2+ is partly changed into Eu3+ and the emission of Eu3+ is obviously observed even under the condition of reduction atmosphere. If reaction temperature is more than 1 150 degrees C, Al2O3 forms alpha-Al2O3 structure, the f-->f transition of Eu2+ appears. If reaction temperature is less than 1 150 degrees C, a mixed phase of alpha-Al2O3 and gamma-Al2O3 is formed, the f-->f transition of Eu2+ disappears and a new band emission from d-->f transition of Eu2+ occurs.

Multiplex Solid-Phase PCR for Rapid Detection and Identification of Salmonella spp. at Sub-species

This study presents a solid-phase PCR (SP-PCR) for rapid detection, identification, and sub-typing of various Salmonella species, the major food-borne cause of salmonellosis. The target DNA is firstly amplified with PCR primers (one primer is labeled with fluorophores) in the liquid phase. Simultaneously on the solid phase, the amplified PCR amplicons interact with the nested DNA probes immobilized on the solid substrate as an array. If the immobilized probes match the sequence of the DNA templates they are extended by the polymerase and serve as template for the second strand elongation primed by the liquid phase primer thus generating new templates for the SP-PCR. After the reaction, PCR products labeled with fluorophores remain attached to the substrate and can be visualized directly by fluorescence readout devices. Using this method, S. enteritidis, S. typhimurium and S. dublin can be detected at the same time. The method offers several advantages over conventional multiplex PCR: less competition between different primer pairs thus increasing multiplexing capability, only single wavelength optical readout needed for the multiplexing detection, and less time-consuming owing to reduction of the post-PCR gel electrophoresis. The method will be useful for development of point-of-care devices for rapid detection and identification of Salmonella spp. A solid-phase PCR for rapid detection and identification of S. enteritidis, S. typhimurium and S. dublin is developed. The method offers advantages such as better multiplexing capability, only single wavelength optical readout needed, and less time-consuming.

Intervention précoce dans la phase initiale des troubles psychotiques à Lausanne: quels problèmes et quelles solutions [Early intervention for the initial phase of psychotic disorders in Lausanne: what problems and what solutions?]

Schizophrenia has long been considered with pessimism, but the recent interest in the early phase of psychotic disorders has modified this often unjustified perception. Literature has demonstrated the benefit of the development of programs specialised in the treatment of early psychosis, which tend to be developed in many countries. It is however important to match them to local needs as well as to the structure of local health services. This paper reviews elements that justify such a development in Lausanne, Switzerland, and describe its various elements.

Strong and fast phase modulation for quantitative analysis of photorefractive gratings

A new approach for studying photorefractive gratings in two-wave mixing experiments by a phase modulation technique is presented. The introduction of a large-amplitude, high-frequency sinusoidal phase modulation in one of the input beams blurs the interference pattern and provides powerful harmonic signals for accurate measurements of the grating diffraction efficiency eta and the output phase shift rho between the transmitted and diffracted waves. The blurring of the light fringes can be used to suppress the higher spatial harmonics of the grating, allowing a space-charge field with sinusoidal profile to be recorded. Although the presence of such a strong phase modulation affects the beam coupling in a rather complicated way, it is shown that for the special case of equal intensity input beams, the effect of the phase modulation on eta and rho is reduced to a weakening of the coupling strength. The potentialities of the technique are illustrated in a study of refractive-index waves excited by running interference patterns in a Bi12TiO20 crystal. Expressions for the diffraction efficiency and the output phase shift are derived and used to match numerically calculated curves to the experimental data. The theoretical model is supported by the very good data fitting and allows the computation of important material parameters.

Acute Phase Responses of Different Positions of High-Goal (Elite) Polo Ponies

The aim of this study was to investigate the acute phase response (APR) in 15 horses by quantifying physiological venous blood variables and serum acute phase proteins (APP) at 5 minutes and 6 and 12 hours after a training match of high-goal polo. The horses were divided into three experimental groups based on their team positions, including defense (n = 6), midfield (n = 5), and attack (n = 4). Serum proteinograms were obtained by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Data were evaluated using analysis of variance for repeated measures. The match represented a high-intensity stimulus for all positions. Defenders appeared to use the anaerobic pathway more than the other positions, as shown by their lower pH and greater lactatemia. Alterations in muscle membrane permeability were observed in all horses, as seen by the increase in serum creatine kinase activity without a correlation with APR. Significant elevations in total serum protein, albumin, ceruloplasmin, haptoglobin, alpha-1 antitrypsin, and 23-kDa protein were seen only during the course of the physical exertion of the match, although there were no differences in these values among positions of the team. After 6 hours of the match, the concentration of transferrin declined, whereas that of alpha-1 acid glycoprotein remained unaltered at all assessed times. These results demonstrated that the defenders required the most use of the anaerobic pathway during the match, and that equestrian polo exercise triggers an acute phase response of relatively short duration; this APR is characterized as noninflammatory, as APR appears to be a physiological alteration related to the stress inherent in physical exercise. © 2013 Elsevier Inc. All rights reserved.

Gametic phase disequilibrium between the syntenic multiallelic HTG4 and HMS3 markers widely used for parentage testing in Thoroughbred horses

Validation of parentage and horse breed registries through DNA typing relies on estimates of random match probabilities with DNA profiles generated from multiple polymorphic loci. Of the twenty-seven microsatellite loci recommended by the International Society for Animal Genetics for parentage testing in Thoroughbred horses, eleven are located on five chromosomes. An important aspect in determining combined exclusion probabilities is the ascertainment of the genetic linkage status of syntenic markers, which may affect reliable use of the product rule in estimating random match probabilities. In principle, linked markers can be in gametic phase disequilibrium (GD). We aimed at determining the extent, by frequency and strength, of GD between the HTG4 and HMS3 multiallelic loci, syntenic on chromosome 9. We typed the qualified offspring (n (1) = 27; n (2) = 14) of two Quarter Bred stallions (registered by the Brazilian Association of Quarter Horse Breeders) and 121 unrelated horses from the same breed. In the 41 informative meioses analyzed, the frequency of recombination between the HTG4 and HMS3 loci was 0.27. Consistent with genetic map distances, this recombination rate does not fit to the theoretical distribution for independently segregated markers. We estimated sign-based D' coefficients as a measure of GD, and showed that the HTG4 and HMS3 loci are in significant, yet partial and weak, disequilibrium, with two allele pairs involved (HTG4*M/HMS3*P, D'(+) = 0.6274; and HTG4*K/HMS3*P, D'(-) = -0.6096). These results warn against the inadequate inclusion of genetically linked markers in the calculation of combined power of discrimination for Thoroughbred parentage validation.

Phase transition in the countdown problem

We present a combinatorial decision problem, inspired by the celebrated quiz show called Countdown, that involves the computation of a given target number T from a set of k randomly chosen integers along with a set of arithmetic operations. We find that the probability of winning the game evidences a threshold phenomenon that can be understood in the terms of an algorithmic phase transition as a function of the set size k. Numerical simulations show that such probability sharply transitions from zero to one at some critical value of the control parameter, hence separating the algorithm's parameter space in different phases. We also find that the system is maximally efficient close to the critical point. We derive analytical expressions that match the numerical results for finite size and permit us to extrapolate the behavior in the thermodynamic limit.

Interleaved multi-cell isolated three-phase PWM rectifier system for aircraft applications

Recently there has been an important increase in electric equipment, as well as, electric power demand in aircrafts applications. This prompts to the necessity of efficient, reliable, and low-weight converters, especially rectifiers from 115VAC to 270VDC because these voltages are used in power distribution. In order to obtain a high efficiency, in aircraft application where the derating in semiconductors is high, normally several semiconductors are used in parallel to decrease the conduction losses. However, this is in conflict with high reliability. To match both goals of high efficiency and reliability, this work proposes an interleaved multi-cell rectifier system, employing several converter cells in parallel instead of parallel-connected semiconductors. In this work a 10kW multi-cell isolated rectifier system has been designed where each cell is composed of a buck type rectifier and a full bridge DC-DC converter. The implemented system exhibits 91% of efficiency, high power density (10kW/10kg), low THD (2.5%), and n−1 fault tolerance which complies, with military aircraft standards.

Atomistic modeling of Ge damage accumulation, amorphization and solid phase epitaxial regrowth

En los últimos años, el Ge ha ganado de nuevo atención con la finalidad de ser integrado en el seno de las existentes tecnologías de microelectrónica. Aunque no se le considera como un canddato capaz de reemplazar completamente al Si en el futuro próximo, probalemente servirá como un excelente complemento para aumentar las propiedades eléctricas en dispositivos futuros, especialmente debido a su alta movilidad de portadores. Esta integración requiere de un avance significativo del estado del arte en los procesos de fabricado. Técnicas de simulación, como los algoritmos de Monte Carlo cinético (KMC), proporcionan un ambiente atractivo para llevar a cabo investigación y desarrollo en este campo, especialmente en términos de costes en tiempo y financiación. En este estudio se han usado, por primera vez, técnicas de KMC con el fin entender el procesado “front-end” de Ge en su fabricación, específicamente la acumulación de dañado y amorfización producidas por implantación iónica y el crecimiento epitaxial en fase sólida (SPER) de las capas amorfizadas. Primero, simulaciones de aproximación de clisiones binarias (BCA) son usadas para calcular el dañado causado por cada ión. La evolución de este dañado en el tiempo se simula usando KMC sin red, o de objetos (OKMC) en el que sólamente se consideran los defectos. El SPER se simula a través de una aproximación KMC de red (LKMC), siendo capaz de seguir la evolución de los átomos de la red que forman la intercara amorfo/cristalina. Con el modelo de amorfización desarrollado a lo largo de este trabajo, implementado en un simulador multi-material, se pueden simular todos estos procesos. Ha sido posible entender la acumulación de dañado, desde la generación de defectos puntuales hasta la formación completa de capas amorfas. Esta acumulación ocurre en tres regímenes bien diferenciados, empezando con un ritmo lento de formación de regiones de dañado, seguido por una rápida relajación local de ciertas áreas en la fase amorfa donde ambas fases, amorfa y cristalina, coexisten, para terminar en la amorfización completa de capas extensas, donde satura el ritmo de acumulación. Dicha transición ocurre cuando la concentración de dañado supera cierto valor límite, el cual es independiente de las condiciones de implantación. Cuando se implantan los iones a temperaturas relativamente altas, el recocido dinámico cura el dañado previamente introducido y se establece una competición entre la generación de dañado y su disolución. Estos efectos se vuelven especialmente importantes para iones ligeros, como el B, el cual crea dañado más diluido, pequeño y distribuido de manera diferente que el causado por la implantación de iones más pesados, como el Ge. Esta descripción reproduce satisfactoriamente la cantidad de dañado y la extensión de las capas amorfas causadas por implantación iónica reportadas en la bibliografía. La velocidad de recristalización de la muestra previamente amorfizada depende fuertemente de la orientación del sustrato. El modelo LKMC presentado ha sido capaz de explicar estas diferencias entre orientaciones a través de un simple modelo, dominado por una única energía de activación y diferentes prefactores en las frecuencias de SPER dependiendo de las configuraciones de vecinos de los átomos que recristalizan. La formación de maclas aparece como una consecuencia de esta descripción, y es predominante en sustratos crecidos en la orientación (111)Ge. Este modelo es capaz de reproducir resultados experimentales para diferentes orientaciones, temperaturas y tiempos de evolución de la intercara amorfo/cristalina reportados por diferentes autores. Las parametrizaciones preliminares realizadas de los tensores de activación de tensiones son también capaces de proveer una buena correlación entre las simulaciones y los resultados experimentales de velocidad de SPER a diferentes temperaturas bajo una presión hidrostática aplicada. Los estudios presentados en esta tesis han ayudado a alcanzar un mejor entendimiento de los mecanismos de producción de dañado, su evolución, amorfización y SPER para Ge, además de servir como una útil herramienta para continuar el trabajo en este campo. In the recent years, Ge has regained attention to be integrated into existing microelectronic technologies. Even though it is not thought to be a feasible full replacement to Si in the near future, it will likely serve as an excellent complement to enhance electrical properties in future devices, specially due to its high carrier mobilities. This integration requires a significant upgrade of the state-of-the-art of regular manufacturing processes. Simulation techniques, such as kinetic Monte Carlo (KMC) algorithms, provide an appealing environment to research and innovation in the field, specially in terms of time and funding costs. In the present study, KMC techniques are used, for the first time, to understand Ge front-end processing, specifically damage accumulation and amorphization produced by ion implantation and Solid Phase Epitaxial Regrowth (SPER) of the amorphized layers. First, Binary Collision Approximation (BCA) simulations are used to calculate the damage caused by every ion. The evolution of this damage over time is simulated using non-lattice, or Object, KMC (OKMC) in which only defects are considered. SPER is simulated through a Lattice KMC (LKMC) approach, being able to follow the evolution of the lattice atoms forming the amorphous/crystalline interface. With the amorphization model developed in this work, implemented into a multi-material process simulator, all these processes can be simulated. It has been possible to understand damage accumulation, from point defect generation up to full amorphous layers formation. This accumulation occurs in three differentiated regimes, starting at a slow formation rate of the damage regions, followed by a fast local relaxation of areas into the amorphous phase where both crystalline and amorphous phases coexist, ending in full amorphization of extended layers, where the accumulation rate saturates. This transition occurs when the damage concentration overcomes a certain threshold value, which is independent of the implantation conditions. When implanting ions at relatively high temperatures, dynamic annealing takes place, healing the previously induced damage and establishing a competition between damage generation and its dissolution. These effects become specially important for light ions, as B, for which the created damage is more diluted, smaller and differently distributed than that caused by implanting heavier ions, as Ge. This description successfully reproduces damage quantity and extension of amorphous layers caused by means of ion implantation reported in the literature. Recrystallization velocity of the previously amorphized sample strongly depends on the substrate orientation. The presented LKMC model has been able to explain these differences between orientations through a simple model, dominated by one only activation energy and different prefactors for the SPER rates depending on the neighboring configuration of the recrystallizing atoms. Twin defects formation appears as a consequence of this description, and are predominant for (111)Ge oriented grown substrates. This model is able to reproduce experimental results for different orientations, temperatures and times of evolution of the amorphous/crystalline interface reported by different authors. Preliminary parameterizations for the activation strain tensors are able to also provide a good match between simulations and reported experimental results for SPER velocities at different temperatures under the appliance of hydrostatic pressure. The studies presented in this thesis have helped to achieve a greater understanding of damage generation, evolution, amorphization and SPER mechanisms in Ge, and also provide a useful tool to continue research in this field.

Towards a unified understanding of event-related changes in the EEG:the Firefly model of synchronization through cross-frequency phase modulation

Although event-related potentials (ERPs) are widely used to study sensory, perceptual and cognitive processes, it remains unknown whether they are phase-locked signals superimposed upon the ongoing electroencephalogram (EEG) or result from phase-alignment of the EEG. Previous attempts to discriminate between these hypotheses have been unsuccessful but here a new test is presented based on the prediction that ERPs generated by phase-alignment will be associated with event-related changes in frequency whereas evoked-ERPs will not. Using empirical mode decomposition (EMD), which allows measurement of narrow-band changes in the EEG without predefining frequency bands, evidence was found for transient frequency slowing in recognition memory ERPs but not in simulated data derived from the evoked model. Furthermore, the timing of phase-alignment was frequency dependent with the earliest alignment occurring at high frequencies. Based on these findings, the Firefly model was developed, which proposes that both evoked and induced power changes derive from frequency-dependent phase-alignment of the ongoing EEG. Simulated data derived from the Firefly model provided a close match with empirical data and the model was able to account for i) the shape and timing of ERPs at different scalp sites, ii) the event-related desynchronization in alpha and synchronization in theta, and iii) changes in the power density spectrum from the pre-stimulus baseline to the post-stimulus period. The Firefly Model, therefore, provides not only a unifying account of event-related changes in the EEG but also a possible mechanism for cross-frequency information processing.

Lipid-Based Liquid Crystals As Carriers for Antimicrobial Peptides: Phase Behavior and Antimicrobial Effect

International audience

Condensed phase combustion travelling waves with sequential exothermic or endothermic reactions

The one-dimensional propagation of a combustion wave through a premixed solid fuel for two-stage kinetics is studied. We re-examine the analysis of a single reaction travelling-wave and extend it to the case of two-stage reactions. We derive an expression for the travelling wave speed in the limit of large activation energy for both reactions. The analysis shows that when both reactions are exothermic, the wave structure is similar to the single reaction case. However, when the second reaction is endothermic, the wave structure can be significantly different from single reaction case. In particular, as might be expected, a travelling wave does not necessarily exist in this case. We establish conditions in the limiting large activation energy limit for the non-existence, and for monotonicity of the temperature profile in the travelling wave.