Desarrollo y aplicación de métodos quimiométricos para el estudio de muestras mediante Espectroscopia de Ablación Láser (LIBS)

La espectroscopía de ablación láser (LIBS) es una técnica analítica que se basa en la formación y estudio de un plasma inducido por un pulso láser focalizado sobre la superficie de un material. La emisión producida por dicho plasma, debido a la recombinación electrónica, es colectada generando un espectro que permite el estudio cualitativo y/o cuantitativo del material. LIBS se ha convertido en una técnica espectroscópica establecida con un enorme valor analítico debido al conjunto de ventajas que presenta y sus particulares características técnicas. Es destacable su rapidez, versatilidad y capacidad de producir información analítica para prácticamente cualquier tipo de muestra de forma escasamente destructiva y con mínima o incluso nula preparación de muestra. Su instrumentación es sencilla, robusta y compacta, permitiendo incluso llevar análisis in situ, así como realizar análisis remotos. El principal objetivo de esta tesis es el estudio de la técnica LIBS en combinación con métodos quimiométricos de análisis, especialmente redes neuronales artificiales, para llevar a cabo estudios cualitativos (identificación y discriminación) usando espectros LIBS como huellas espectrales digitales características de muestras de origen alimenticio (aceites de oliva y vinos), con interés forense (huesos y dientes humanos) y por último especies animales, moluscos y corales, con interés paleoclimático..

Plume dynamics of laser-produced swine muscle tissue plasma

11 págs. 8 figs.; 2 tabs.We report on the plume dynamics of the plasma induced by laser ablation of a swine skeletal muscle tissue sample in different vacuum conditions. Pulses from a transversely excited atmospheric CO2 laser were focused onto a target sample and the induced plasma was allowed to expand in different air pressures. The expansion features were studied using fast photography of the overall visible emission by using a gated intensified charged coupled device. Free expansion and plume splitting were observed at different pressure levels. The expansion of the plasma plume front was analyzed using various expansion models and the velocity of the plume front was estimated. The effect of the number of accumulated laser shots on the crater volume at different ambient air pressures and an elemental analysis of the sample were performed using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy analysis. The surface morphology of the irradiated surface showed that increasing the pressure of the ambient gas decreased the ablated mass, or in other words it reduced significantly the laser-target coupling.The authors gratefully acknowledge the support received in part by the DGICYT (Spain) Project MICINN: CTQ2013-43086 for this research.Peer reviewe

Megapixel multi-elemental imaging by Laser-Induced Breakdown Spectroscopy, a technology with considerable potential for paleoclimate studies

Paleoclimate studies play a crucial role in understanding past and future climates and their environmental impacts. Current methodologies for performing highly sensitive elemental analysis at micrometre spatial resolutions are restricted to the use of complex and/or not easily applied techniques, such as synchrotron radiation X-ray fluorescence micro-analysis (μ-SRXRF), nano secondary ion mass spectrometry (nano-SIMS) or laser ablation inductively coupled plasma mass spectrometry (LAICP-MS). Moreover, the analysis of large samples (>few cm²) with any of these methods remains very challenging due to their relatively low acquisition speed (~1–10 Hz), and because they must be operated in vacuum or controlled atmosphere. In this work, we proposed an imaging methodology based on laser-induced breakdown spectroscopy, to perform fast multi-elemental scanning of large geological samples with high performance in terms of sensitivity (ppm-level), lateral resolution (up to 10 μm) and operating speed (100 Hz). This method was successfully applied to obtain the first megapixel images of large geological samples and yielded new information, not accessible using other techniques. These results open a new perspective into the use of laser spectroscopy in a variety of geochemical applications

2 nd Brazilian Consensus on Chagas Disease, 2015

Abstract Chagas disease is a neglected chronic condition with a high burden of morbidity and mortality. It has considerable psychological, social, and economic impacts. The disease represents a significant public health issue in Brazil, with different regional patterns. This document presents the evidence that resulted in the Brazilian Consensus on Chagas Disease. The objective was to review and standardize strategies for diagnosis, treatment, prevention, and control of Chagas disease in the country, based on the available scientific evidence. The consensus is based on the articulation and strategic contribution of renowned Brazilian experts with knowledge and experience on various aspects of the disease. It is the result of a close collaboration between the Brazilian Society of Tropical Medicine and the Ministry of Health. It is hoped that this document will strengthen the development of integrated actions against Chagas disease in the country, focusing on epidemiology, management, comprehensive care (including families and communities), communication, information, education, and research

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Calculation of catalyst crust thickness from full elemental laser-induced breakdown spectroscopy images

International audienceWe propose a methodology to compute the crust thickness of an element in an egg-shell catalyst from a two-dimensional elemental map. The methodology handles two important catalyst shapes: infinite extrudates of arbitrary section and spheres. The methodology is validated with synthetic analytical profiles on simple shapes (cylinder and sphere). Its relative accuracy is shown close to few percent with a decrease inversely proportional to the square root of the number of sampled pixels. The crust thickness obtained by this method from quantitative Pd maps acquired by laser-induced breakdown spectroscopy are comparable with values obtained from electron-probe microanalysis profiles. Some discrepancies are found and are explained by the heterogeneity of the crust thickness within a grain. As a full map is more representative than a single profile, fast mapping and the methodology exposed in this paper are expected to become valuable tools for the development of new generations of egg-shell deposited catalysts

Proyecto de tecnología

Proyecto de tecnología que propone posibilitar al alumnado la adopción de técnicas de trabajo para mejorar el análisis de la realidad y la adquisición de capacidades y destrezas de aplicación práctica. El proyecto presentado no guarda ninguna relación con la experiencia que se realiza según la memoria presentada. Los objetivos son: potenciar el proceso tecnológico como instrumento para la resolución de problemas; desarrollar la creatividad, el razonamiento lógico, la capacidad de síntesis, la reflexión, el espíritu crítico, y la expresión y comunicación; fomentar hábitos de auto-aprendizaje y de trabajo en equipo; favorecer la integración escolar; descubrir a través de la observación y experimentación con aparatos tecnológicos de uso cotidiano los problemas de diseño y las soluciones aportadas; y conocer y manejar materiales, herramientas y operadores tecnológicos. La experiencia, que se lleva a cabo en sesiones semanales de una hora en el taller de tecnología, consiste en la presentación o explicación por parte del profesor del uso y manejo de materiales y recursos tecnológicos, para que luego los alumnos diseñen y fabriquen máquinas o estructuras utilizando dichos elementos. El esquema de trabajo para cada diseño consta de la representación gráfica de la máquina, explicación de su funcionamiento, material necesario y división y organización del trabajo. Así, las propuestas de trabajo para los tres niveles del Ciclo Superior son: carrera de canicas con rampas, polea reductora, dibujos animados, vehículos con motor, etc. Se realizan además una serie de visitas a fábricas y centros escolares para observar y analizar diferentes opciones profesionales como actividades de apoyo al programa de información y orientación escolar. Se incluyen en la memoria: el guión de trabajo de una visita a una fábrica, el esquema del proceso de trabajo a seguir en los diseños y una selección de proyectos elaborados por los alumnos.Madrid (Comunidad Autónoma). Consejería de Educación y CulturaMadridMadrid (Comunidad Autónoma). Subdirección General de Formación del Profesorado. CRIF Las Acacias; General Ricardos 179 - 28025 Madrid; Tel. + 34915250893ES

Proyecto de Tecnología

Se trata de impartir clases muy activas en las que el alumno participe en la resolución de problemas tecnológicos de forma creativa, además de que desarrolle su razonamiento lógico, su capacidad de observación y sus habilidades manuales de pricomotricidad. Asimismo, se pretende que se habitúe al trabajo en grupo y a la planificación de proyectos tecnológicos. En cuanto a las actividades, destacan: el diseño y construcción de carreras de canicas, construcción de una máquina con una polea reductora, etc. El proyecto resultó un éxito: los alumnos acudieron al taller de Tecnología com más interés e ilusión y allí desarrollaron su creatividad, razonamiento lógico, destrezas técnicas, y hábitos de orden y cooperación. Igualmente, se contribuyó al impulso de la educación no sexista y a la integración de los chicos más problemáticos..Madrid (Comunidad Autónoma). Consejería de Educación y CulturaMadridMadrid (Comunidad Autónoma). Subdirección General de Formación del Profesorado. CRIF Las Acacias; General Ricardos 179 - 28025 Madrid; Tel. + 34915250893ES