Luces y sombras de los estudios de casos y controles. Impacto sobre el conocimiento de las malformaciones congénitas

TeratologíaN

Combined grazing incidence RBS and TEM analysis of luminescent nano-SiGe/SiO2 multilayers.

Multilayer structures with five periods of amorphous SiGe nanoparticles/SiO2 layers with different thickness were deposited by Low Pressure Chemical Vapor Deposition and annealed to crystallize the SiGe nanoparticles. The use of grazing incidence RBS was necessary to obtain sufficient depth resolution to separate the signals arising from the individual layers only a few nm thick. The average size and areal density of the embedded SiGe nanoparticles as well as the oxide interlayer thickness were determined from the RBS spectra. Details of eventual composition changes and diffusion processes caused by the annealing processes were also studied. Transmission Electron Microscopy was used to obtain complementary information on the structural parameters of the samples in order to check the information yielded by RBS. The study revealed that annealing at 900 °C for 60 s, enough to crystallize the SiGe nanoparticles, leaves the structure unaltered if the interlayer thickness is around 15 nm or higher

Growth of InP on GaAs (001) by hydrogen-assisted low-temperature solid-source molecular beam epitaxy

Direct heteroepitaxial growth of InP layers on GaAs (001) wafers has been performed by solid-source molecular beam epitaxy assisted by monoatomic hydrogen (H∗). The epitaxial growth has been carried out using a two-step method: for the initial stage of growth the temperature was as low as 200 °C and different doses of H∗ were used; after this, the growth proceeded without H∗ while the temperature was increased slowly with time. The incorporation of H∗ drastically increased the critical layer thickness observed by reflection high-energy electron diffraction; it also caused a slight increase in the luminescence at room temperature, while it also drastically changed the low-temperature luminescence related to the presence of stoichiometric defects. The samples were processed by rapid thermal annealing. The annealing improved the crystalline quality of the InP layers measured by high-resolution x-ray diffraction, but did not affect their luminescent behavior significantly

Raman spectrum of group IV nanowires: influence of temperature

Group IV semiconductor nanowires are characterized by Raman spectroscopy. The results are analyzed in terms of the heating induced by the laser beam on the nanowires. By solving the heat transport equation one can simulate the temperature reached by the NWs under the exposure to a laser beam. The results are illustrated with Si and Si1-xGex nanowires. Both bundles of nanowires and individual nanowires are studied. The main experimental conditions contributing to the nanowire heating are discusse

Structural stability of SiGe nanoparticles under "in situ" electron beam irradiation in TEM

The structure of amorphous and crystalline SiGe nanoparticles, embedded in a dielectric medium, SiO2, and its stability under “in situ” electron beam irradiation is reported. High-resolution transmission electron microscopy and electron-diffraction pattern simulation by fast Fourier transform was used to analyze the crystal structure of the SiGe nanoparticles. Electron beam irradiation induces structural alternate order-disorder transitions in the nanoparticles for irradiation effects are mainly associated to the density of current. For irradiation with current densities < 7 A·cm-2 no effects are observed in the as-deposited amorphous samples, whereas in the crystallized samples, SiGe nanocrystals show higher stability and no effects are observed for irradiation densities of current < 50 A·cm-2. Irradiation with densities of current greater than these thresholds cause consecutive amorphous-crystalline or crystalline-amorphous structure transitions respectively for both amorphous and crystallized nanoparticles. A hexagonal structure is proposed for those nanocrystals obtained after irradiation in the as deposited amorphous samples

Influence of the crystallization process on the luminescence of multilayers of SiGe nanocrystals embedded in SiO2

Multilayers of SiGe nanocrystals embedded in an oxide matrix have been fabricated by low-pressure chemical vapor deposition SiO2 onto Si wafers (in a single run at 390 ◦C and 50mTorr, using GeH4, Si2 H6 and O2) followed by a rapid thermal annealing crystallize the SiGe nanoparticles. The main emission band is located at 400 nm in both cathodoluminescence and photoluminescence at 80K and also at room temperature. The annealing conditions (temperatures ranging from 700 to 1000 ◦C and for times of 30 investigated in samples with different diameter of the nanoparticles (from ≈3 to ≥5 nm) and oxide interlayer thickness (15 and establish a correlation between the crystallization of the nanoparticles, the degradation of their composition by Ge diffusion the luminescence emission band. Structures with small nanoparticles (3–4.5 nm) separated by thick oxide barriers (≈35 nm) annealed 60 s yield the maximum intensity of the luminescence. An additional treatment at 450 ◦C in forming gas for dangling-bond the intensity of the luminescence band by 25–30%

Manual GO annotation of predictive protein signatures: the InterPro approach to GO curation

InterPro amalgamates predictive protein signatures from a number of well-known partner databases into a single resource. To aid with interpretation of results, InterPro entries are manually annotated with terms from the Gene Ontology (GO). The InterPro2GO mappings are comprised of the cross-references between these two resources and are the largest source of GO annotation predictions for proteins. Here, we describe the protocol by which InterPro curators integrate GO terms into the InterPro database. We discuss the unique challenges involved in integrating specific GO terms with entries that may describe a diverse set of proteins, and we illustrate, with examples, how InterPro hierarchies reflect GO terms of increasing specificity. We describe a revised protocol for GO mapping that enables us to assign GO terms to domains based on the function of the individual domain, rather than the function of the families in which the domain is found. We also discuss how taxonomic constraints are dealt with and those cases where we are unable to add any appropriate GO terms. Expert manual annotation of InterPro entries with GO terms enables users to infer function, process or subcellular information for uncharacterized sequences based on sequence matches to predictive models

Binding Potassium to Improve Treatment With Renin-Angiotensin-Aldosterone System Inhibitors: Results From Multiple One-Stage Pairwise and Network Meta-Analyses of Clinical Trials.

This manuscript presents findings from the first dichotomous data pooling analysis on clinical trials (CT) regarding the effectiveness of binding potassium. The results emanated from pairwise and network meta-analyses aiming evaluation of response to commercial potassium-binding polymers, that is, to achieve and maintain normal serum potassium (n = 1,722), and the association between this response and an optimal dosing of renin-angiotensin-aldosterone system inhibitors (RAASi) needing individuals affected by heart failure (HF) or resistant hypertension, who may be consuming other hyperkalemia-inducing drugs (HKID) (e.g., β-blockers, heparin, etc.), and frequently are affected by chronic kidney disease (CKD) (n = 1,044): According to the surface under the cumulative ranking area (SUCRA), sodium zirconium cyclosilicate (SZC) (SUCRA &gt;0.78), patiromer (SUCRA &gt;0.58) and sodium polystyrene sulfonate (SPS) (SUCRA &lt;0.39) were different concerning their capacity to achieve normokalemia (serum potassium level (sK+) 3.5-5.0 mEq/L) or acceptable kalemia (sK+ ≤ 5.1 mEq/L) in individuals with hyperkalemia (sK+ &gt;5.1 mEq/L), and, when normokalemia is achieved, patiromer 16.8-25.2 g/day (SUCRA = 0.94) and patiromer 8.4-16.8 g/day (SUCRA = 0.41) can allow to increase the dose of spironolactone up to 50 mg/day in subjects affected by heart failure (HF) or with resistant hypertension needing treatment with other RAASi. The potential of zirconium cyclosilicate should be explored further, as no data exists to assess properly its capacity to optimize dosing of RAASi, contrarily as it occurs with patiromer. More research is also necessary to discern between benefits of binding potassium among all type of hyperkalemic patients, for example, patients with DM who may need treatment for proteinuria, patients with early hypertension, etc. Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42020185614, CRD42020185558, CRD42020191430

Etiología de las infecciones del tracto urinario y sensibilidad de los uropatógenos a los antimicrobianos

El tratamiento antibiótico de la infección urinaria en el adulto se realiza habitualmente de forma empírica, siendo excepcional la realización de urocultivo. La elección del antibiótico se sustenta en los resultados de las series de casos publicadas (urocultivos positivos), de las que se extrae el perfil etiológico más probable y la sensibilidad esperada. Presentamos los resultados de los estudios publicados en los últimos años, detallando las diferencias en función de la procedencia y características de los pacientes, y su tendencia temporal. En las infecciones urinarias de vías bajas sin factores de riesgo el tratamiento debe cubrir fundamentalmenteEscherichia coli. Sin embargo, en las infecciones urinarias complicadas o con factores de riesgo la información clínico-epidemiológica disponible no permite la elección empírica segura en ausencia de urocultivo. Asimismo, llama la atención el descenso de la sensibilidad deE. coli a diversos antibióticos, con grandes variaciones geográficas; el descenso de actividad de las fluoroquinolonas podría comprometer en un futuro su uso empírico

The InterPro protein families database: the classification resource after 15 years.

The InterPro database (http://www.ebi.ac.uk/interpro/) is a freely available resource that can be used to classify sequences into protein families and to predict the presence of important domains and sites. Central to the InterPro database are predictive models, known as signatures, from a range of different protein family databases that have different biological focuses and use different methodological approaches to classify protein families and domains. InterPro integrates these signatures, capitalizing on the respective strengths of the individual databases, to produce a powerful protein classification resource. Here, we report on the status of InterPro as it enters its 15th year of operation, and give an overview of new developments with the database and its associated Web interfaces and software. In particular, the new domain architecture search tool is described and the process of mapping of Gene Ontology terms to InterPro is outlined. We also discuss the challenges faced by the resource given the explosive growth in sequence data in recent years. InterPro (version 48.0) contains 36 766 member database signatures integrated into 26 238 InterPro entries, an increase of over 3993 entries (5081 signatures), since 2012