Laser-induced breakdown spectroscopy of trisilane using infrared C O2 laser pulses

The plasma produced in trisilane (Si3 H8) at room temperature and pressures ranging from 50 to 103 Pa by laser-induced breakdown (LIB) has been investigated. The ultraviolet-visible-near infrared emission generated by high-power IR C O2 laser pulses in Si3 H8 has been studied by means of optical emission spectroscopy. Optical breakdown threshold intensities in trisilane at 10.591 μm for laser pulse lengths of 100 ns have been measured as a function of gas pressure. The strong emission observed in the plasma region is mainly due to electronic relaxation of excited atomic H and Si and ionic fragments Si+, Si2+, and Si3+. An excitation temperature Texc =5600±300 K was calculated by means of H atomic lines assuming local thermodynamic equilibrium. The physical processes leading to LIB of trisilane in the power density range 0.28 GW cm-2 <J<3.99 GW cm-2 have been analyzed. From our experimental observations we can propose that, although the first electrons must appear via multiphoton ionization, electron cascade is the main mechanism responsible for the breakdown in trisilane. © 2007 American Institute of Physics.This work was partially supported by the Spanish MEC Project No. CTQ2007-60177/BQU. It is a pleasure to acknowledge the excellent technical support of A. Magro. This work is dedicated in memory of Professor Antonio Pardo Martinez.Peer Reviewe

Optical Breakdown in Gases Induced by High-power IR CO2 Laser Pulses

This chapter reviews some fundamentals of laser-induced breakdown spectroscopy (LIBS) and describes some experimental studies developed in our laboratory on gases such as nitrogen, oxygen and air. LIBS of these gases at different pressures, in the spectral range ultraviolet-visible-near infrared (UV-Vis-NIR), was excited by using a high-power transverse excitation atmospheric (TEA) CO2 laser (¿=9.621 or 10.591 ¿m; tFWHM=64 ns; and different laser power densities). The spectra of the generated plasmas are dominated by emission of strong atomic, ionic species and molecular bands. Excitation temperatures are estimated from the intensities of atomic and ionic lines. Electron number densities are deduced from the Stark broadening of several ionic lines. The characteristics of the spectral emission intensities from different species have been investigated as functions of the gas pressure and laser irradiance. Optical breakdown threshold intensities in different gases have been experimentally measured. The physical processes leading to laser-induced breakdown of gases have been analyzed. Plasma characteristics of LIBS in air are examined in detail on the emission lines of N+, O+ and C by using time-resolved optical-emission spectroscopy (OES) technique. The results show a faster decay of continuum and ionic spectral species than of neutral atomic and molecular ones. The velocity and kinetic energy distributions for the different species are obtained from time-of-flight (TOF) OES measurements. Excitation temperatures and electron densities in the laser-induced plasma are estimated from the analysis of spectral data at various times from the laser pulse incidence. Temporal evolution of electron density has been used for the estimation of the three-body recombination rate constant.Peer Reviewe

Temporal evolution of the laser-induced plasma generated by IR CO 2 pulsed laser on carbon targets

Time-resolved optical emission analysis was carried out for the plasma plume, produced by high-power tunable IR CO2 pulsed laser ablation of graphite, at λ=10.591 μm and in a regime of relatively high laser fluences (123-402 J/ cm2). Wavelength-dispersed spectra of the plasma plume, at medium-vacuum conditions (4 Pa) and at 9.0 mm from the target, show ionized species (C+, C2+, C3+, C4+, N2 +, N+, and O+), neutral atoms (C, H, N, and O), and neutral diatomic molecules (C2, CN, OH, CH, and N2). In this work, we focus our attention on the temporal evolution of different atomic/ionic and molecular species over a broad spectral range from 190 to 1000 nm. The results show a faster decay for ionic fragments than for neutral atomic and molecular species. The velocity and kinetic energy distributions for different species were obtained from time-of-flight measurements using time-resolved optical emission spectroscopy. Possible mechanisms for the production of these distributions are discussed. Excitation temperature, electron density, and vibrational temperature in the laser-induced plasma were estimated from the analysis of spectral data at various times from the laser pulse incidence. © 2009 American Institute of Physics.Peer Reviewe

Decreased circulating Fas ligand in patients with familial combined hyperlipidemia or carotid atherosclerosis Normalization by atorvastatin

AbstractObjectivesWe sought to study whether patients with familial combined hyperlipidemia (FCH) or carotid atherosclerosis have modified circulating solubilized Fas ligand (sFasL) levels, as well as the potential modifications by atorvastatin. We also examined the effect of atorvastatin on FasL expression and sFasL release in cytokine-stimulated cultured human endothelial cells (ECs).BackgroundIn normal situations, FasL is expressed in most cells, including ECs. Proinflammatory stimuli can downregulate its expression in ECs and facilitate the vascular infiltration of inflammatory cells.MethodsWe have measured sFasL plasma levels (by ELISA) in 58 patients with FCH, 14 normocholesterolemic patients with carotid atherosclerosis, and 15 healthy volunteers. We analyzed FasL expression (by Western blot analysis) and sFasL release in cultured ECs stimulated with tumor necrosis factor (TNF)-alpha.ResultsSolubilized FasL levels were decreased in hyperlipidemic patients (49 pg/ml), as compared with healthy volunteers (123 pg/ml, p < 0.0001). Patients were randomized to atorvastatin (n = 28) or bezafibrate (n = 30) during 12 months. Atorvastatin treatment increased sFasL concentrations (111 pg/ml, p < 0.0001), reaching normal values. However, treatment with bezafibrate only marginally affected sFasL (85 pg/ml, p < 0.05). Solubilized FasL was also diminished in patients with carotid atherosclerosis (39 pg/ml), and intensive treatment with atorvastatin normalized sFasL levels (90 pg/ml, p = 0.02). Finally, atorvastatin prevented the diminution of FasL expression and sFasL release elicited by TNF-alpha in cultured ECs.ConclusionsPatients with FCH or carotid atherosclerosis have decreased circulating sFasL levels, probably indicating endothelial dysfunction, but treatment with atorvastatin restored normal blood levels. These data provide a novel effect of atorvastatin and add support for the well-known anti-inflammatory properties of statins

In situ chemical modification of C–S–H induced by CO2 laser irradiation

The final publication is available at Springer via http://dx.doi.org/10.1617/s11527-018-1150-yFire-induced compositional changes lead to strength loss and even failure in cement and concrete. Calcium silicate hydrate (C–S–H) gel, the main product of cement hydration, dehydrates at 25–200 °C, while temperatures of 850–900 °C alter its structure. A Raman spectroscopic study of the amorphous and crystalline phases forming after CO2 laser radiation of cement mortar showed that C–S–H dehydration yielded tricalcium silicate at higher, and dicalcium silicate at lower, temperatures. Post-radiation variations were identified in the position of the band generated by Si–O bond stretching vibrations.Peer ReviewedPostprint (author's final draft

From nuclear track characterization to machine learning based image classification in neutron autoradiography for boron neutron capture therapy

Knowledge of the 10B microdistribution is of great relevance in BNCT studies. Since 10B concentration assesment through neutron autoradiography depends on the correct quantification of tracks in a nuclear track detector, image acquisition and processing conditions should be controlled and verified, in order to obtain accurate results to be applied in the frame of BNCT. With this aim, an image verification process was proposed, based on parameters extracted from the quantified nuclear tracks. Track characterization was performed by selecting a set of morphological and pixel-intensity uniformity parameters from the quantified objects (area, diameter, roundness, aspect ratio, heterogeneity and clumpiness). Their distributions were studied, leading to the observation of varying behaviours in images generated by different samples and acquisition conditions. The distributions corresponding to samples coming from the BNC reaction showed similar attributes in each analyzed parameter, proving to be robust to the experimental process, but sensitive to light and focus conditions. Considering those observations, a manual feature extraction was performed as a pre-processing step. A Support Vector Machine (SVM) and a fully dense Neural Network (NN) were optimized, trained, and tested. The final performance metrics were similar for both models: 93%-93% for the SVM, vs 94%-95% for the NN in accuracy and precision respectively. Based on the distribution of the predicted class probabilities, the latter had a better capacity to reject inadequate images, so the NN was selected to perform the image verification step prior to quantification. The trained NN was able to correctly classify the images regardless of their track density. The exhaustive characterization of the nuclear tracks provided new knowledge related to the autoradiographic images generation. The inclusion of machine learning in the analysis workflow proves to optimize the boron determination process and paves the way for further applications in the field of boron imaging.Fil: Viglietti, Julia S.. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; ArgentinaFil: Espain, Maria Sol. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; ArgentinaFil: Díaz, Rodrigo Fernando. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología. Centro Internacional de Estudios Avanzados; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias Fisicas. - Universidad Nacional de San Martin. Instituto de Ciencias Fisicas.; ArgentinaFil: Nieto, Luis Agustin. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología. Centro Internacional de Estudios Avanzados; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Ciencias Fisicas. - Universidad Nacional de San Martin. Instituto de Ciencias Fisicas.; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Szewc, Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Cincinnati; Estados UnidosFil: Bernardi, Guillermo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Rodríguez, Luis M.. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fregenal, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Saint Martin, María Laura Gisela. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; ArgentinaFil: Portu, Agustina Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; Argentin

Patient safety walkrounds with hospital managers: a tool for improving the care of critical patients

Introducción y Objetivos: 1) Describir el proceso de implantación de las Rondas de Seguridad (RS) con Directivos en el área de Cuidados Intensivos de un hospital de tercer nivel; 2) Analizar si hubo diferencias entre las RS en la Unidad de Cuidados Intensivos de adultos (UCI) y la Unidad de Cuidados Intensivos pediátrica (UCIp); 3) Conocer las opiniones de los participantes sobre la herramienta utilizada. Metodología: Estudio analítico longitudinal realizado entre 2009 y 2011. Se utilizó una hoja de registro compuesta por 6 ítems: 1) Presencia de pulsera identificativa; 2) Apósitos de las vías en buen estado; 3) Cabecera de la cama elevada a 30º; 4) Colchón adaptado a paciente con úlcera por presión; 5) Hoja de tratamiento médico sin dudas para enfermería y 6) Hoja de Objetivos Diarios cubierta. Se empleó el estadístico U-Mann Whitney para muestras no paramétricas. Resultados: Se observaron un total de 167 pacientes en 7 RS. La inicial de la UCI los ítems “colchón para paciente con úlceras por presión” y “hoja de objetivos diarios cubierta” registraban un cumplimiento inferior al 60%. En el caso de la UCIp se encontró el 0% de cumplimiento para la pulsera identificativa. Hubo diferencias estadísticamente significativas entre la UCI y la UCIp para los ítems anteriormente citados. Conclusión: Las RS con Directivos aplicadas a las UCI del Hospital Universitario Central de Asturias mejoraron aspectos importantes de Seguridad del Paciente. La implicación de los Directivos fue lo mejor valorado por parte de los profesionales y garantizó el éxito en la implantación de la herramienta.Objectives: 1) To describe the process of implementation of walkrounds with hospital managers in the Intensive Care Unit (ICU) at a tertiary hospital ; 2) To examine whether there were differences between the WR in the Adult Intensive Care Unit (AICU) and the Pediatric Intensive Care Unit (PICU ); 3) To know the opinion of the participants about the tool. Methodology: It is an analytic and longitudinal study done between 2009 and 2011. It was used a sheet with 6 items: 1) Presence of wristband ; 2) Dressings roads in good condition; 3) Headboard at 30º; 4) Special mattress adapted to patients with pressure ulcers ; 5 ) Sheet for medical treatments without any doubts for nurses and 6) Daily goal sheet fulfilled. It was used Statistical U Mann – Whitney for nonparametric samples. Results: A total of 167 patients were seen in 7. walkrounds At the beginning, items “mattress for patients with pressure ulcers” and “daily goal sheet fulfilled” had less than 60% of compliance in AICU. For the PICU, we found 0 % of compliance in the presence of wristband. There were statistically significant differences between the AICU and the PICU for those items. Conclusion: Walkrounds with hospital managers applied to ICUs at our hospital improved important aspects of patient safety. The involvement of hospital managers was the most important thing for the rest of health care workers and it ensured the successful implementation of the tool

The use of interactive response systems as a tool to favor proactive learning in Engineering

El desarrollo de las tecnologías de la información y la comunicación (TIC) ha permitido el surgimiento de herramientas didácticas en el campo de la educación, proporcionando herramientas prácticas para apoyar a las clases presenciales. En este contexto, los sistemas electrónicos de respuesta estudiantil pueden ser útiles para introducir un elemento tecnológico motivador en las lecciones, así como una nueva metodología. En este estudio, además del uso de los sistemas de respuesta interactiva o clickers, se ha introducido la tecnología de aprendizaje móvil mediante la elaboración de una metodología de uso de las herramientas Kahoot y Telegram en la asignatura "Fundamentos Físicos en la Ingeniería II" del Grado en Ingeniería Electrónica Industrial. El Departamento de Física Aplicada de la Universidad de Córdoba tiene una amplia experiencia en el uso de Clickers en clases teóricas con grupos grandes para diferentes grados universitarios, pero ahora el uso de tecnologías móviles de aprendizaje se ha introducido en grupos de tamaño medio para clases prácticas. Usando esta nueva metodología, los estudiantes de grupos medianos realizan un cuestionario durante la lección de resolución de problemas, donde utilizaron sus conocimientos adquiridos durante la clase. La realización del cuestionario permite a los profesores evaluar en tiempo real el nivel del estudiante y utilizar la retroalimentación para abordar los problemas iniciales y los malentendidos. Los resultados muestran que los sistemas de respuesta interactiva son altamente valorados por los estudiantes, que lo perciben como una herramienta para mejorar el aprendizaje y aumentar la competencia en el aula.The development of information and communication technologies (ICT) has enabled the emergence of teaching tools in the education field, providing practical tools to support face-to-face classes. In this context, electronic student response systems can be useful for introducing a motivating technological element into the lessons, as well as a new methodology. In this study, in addition to the use of interactive response systems or clickers, mobile learning technology has been introduced by developing a methodology for using the Kahoot and Telegram tools in the subject “Physical Foundations of Engineering II” of Electronic Engineering Degree. Department of Applied Physics of University of Cordoba has a broad experience using Clickers in theory classes with large groups for different university degrees, but now the use of mobile learning technologies has been introduced in medium-sized groups for practical classes. Using this new methodology, students of medium-sized groups perform a quiz during the problem solving lesson, where they utilized their knowledge gained during the class. The completion of the quiz allows teachers to assess the student’s level in real time, and to use the feedback to address initial problems and misunderstandings. Results show the interactive response systems are highly valued by students, who perceive it as a tool to improve learning and increase competition in the classroom

Can the intake of antiparasitic secondary metabolites explain the low prevalence of hemoparasites among wild Psittaciformes?

Background: Parasites can exert selection pressure on their hosts through effects on survival, on reproductive success, on sexually selected ornament, with important ecological and evolutionary consequences, such as changes in population viability. Consequently, hemoparasites have become the focus of recent avian studies. Infection varies significantly among taxa. Various factors might explain the differences in infection among taxa, including habitat, climate, host density, the presence of vectors, life history and immune defence. Feeding behaviour can also be relevant both through increased exposure to vectors and consumption of secondary metabolites with preventative or therapeutic effects that can reduce parasite load. However, the latter has been little investigated. Psittaciformes (parrots and cockatoos) are a good model to investigate these topics, as they are known to use biological control against ectoparasites and to feed on toxic food. We investigated the presence of avian malaria parasites (Plasmodium), intracellular haemosporidians (Haemoproteus, Leucocytozoon), unicellular flagellate protozoans (Trypanosoma) and microfilariae in 19 Psittaciformes species from a range of habitats in the Indo-Malayan, Australasian and Neotropical regions. We gathered additional data on hemoparasites in wild Psittaciformes from the literature. We considered factors that may control the presence of hemoparasites in the Psittaciformes, compiling information on diet, habitat, and climate. Furthermore, we investigated the role of diet in providing antiparasitic secondary metabolites that could be used as self-medication to reduce parasite load. Results: We found hemoparasites in only two of 19 species sampled. Among them, all species that consume at least one food item known for its secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, were free from hemoparasites. In contrast, the infected parrots do not consume food items with antimalarial or even general antiparasitic properties. We found that the two infected species in this study consumed omnivorous diets. When we combined our data with data from studies previously investigating blood parasites in wild parrots, the positive relationship between omnivorous diets and hemoparasite infestation was confirmed. Individuals from open habitats were less infected than those from forests. Conclusions: The consumption of food items known for their secondary metabolites with antimalarial, trypanocidal or general antiparasitic properties, as well as the higher proportion of infected species among omnivorous parrots, could explain the low prevalence of hemoparasites reported in many vertebrates

Combined dark matter searches towards dwarf spheroidal galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS

Cosmological and astrophysical observations suggest that 85% of the total matter of the Universe is made of Dark Matter (DM). However, its nature remains one of the most challenging and fundamental open questions of particle physics. Assuming particle DM, this exotic form of matter cannot consist of Standard Model (SM) particles. Many models have been developed to attempt unraveling the nature of DM such as Weakly Interacting Massive Particles (WIMPs), the most favored particle candidates. WIMP annihilations and decay could produce SM particles which in turn hadronize and decay to give SM secondaries such as high energy \u1d6fe rays. In the framework of indirect DM search, observations of promising targets are used to search for signatures of DM annihilation. Among these, the dwarf spheroidal galaxies (dSphs) are commonly favored owing to their expected high DM content and negligible astrophysical background. In this work, we present the very first combination of 20 dSph observations, performed by the Fermi-LAT, HAWC, H.E.S.S., MAGIC, and VERITAS collaborations in order to maximize the sensitivity of DM searches and improve the current results. We use a joint maximum likelihood approach combining each experiment’s individual analysis to derive more constraining upper limits on the WIMP DM self-annihilation cross-section as a function of DM particle mass. We present new DM constraints over the widest mass range ever reported, extending from 5 GeV to 100 TeV thanks to the combination of these five different \u1d6fe-ray instruments