Preparación y caracterización de compuestos poliméricos a base de aceite de linaza epoxidado y nanotubos de carbono

Establecer las condiciones de preparación de compuestos poliméricos a base de aceite de linaza y nanotubos de carbono no modificados y modificados químicamente, y llevar a cabo su caracterización por FT-IR, SEM, propiedades eléctricasSe alcanzó el objetivo del proyecto. Se analizó el efecto de la funcionalización de nanotubos de carbono de pared múltiple (NTCPM) en la dispersión en una matriz polimérica. Esa dispersión se evaluó indirectamente mediante la medición de la resistencia eléctrica y posterior cálculo de la resistividad de películas de los compuestos poliméricos a base de Aceite de linaza epoxidado (ALE) y NTCPM sin modificar y modificados superficialmente por oxidación química, a diferentes composiciones de NTCPM. El método de dispersión y la observación cualitativa de ésta, se realizó como se estableció en la metodología, observando cada hora, en diferentes disolventes, un concentración dada de NTCPM , en un microscopio óptico. Se determinó como el tiempo de dispersión adecuado, aquel en donde se observaron en mayoría, NTCPM individuales, siendo el mejor disolvente la Dimetil Formamida (DMF). El tiempo varió acorde al tipo de NTC empleados. Con los datos de resistividad, se construyeron las curvas de percolación de las tres series de compuestos generadas y se modeló la concentración crítica

Formation of b-Bi2O3 and d-Bi2O3 during laser irradiation of Bi films studied in-situ by spatially resolved Raman spectroscopy

The formation of different phases of Bi2O3 induced by laser irradiation of Bi films has been assessed in situ by micro-Raman spectroscopy as a function of laser wavelength, power density and irradiation time. Raman mapping of the irradiated samples enabled a spatially-resolved study of the distribution of the formed Bi2O3 phases. Red laser (633 nm) irradiation was found to induce the appearance of b-Bi2O3, within a certain range of power densities, by diffusion-controlled processes. In contrast, ultraviolet (UV, 325 nm) laser irradiation, above a certain power density threshold, initially induces the formation of both b and d-Bi2O3 phases. The amount of the produced d-Bi2O3 phase increases by increasing the irradiation time, while that of the b phase follows the opposite trend. UV laser irradiation seems to be a suitable method to produce room temperature stable d-Bi2O3 patterns on Bi film

Femtosecond laser-induced periodic surface structures formation on bismuth thin films upon irradiation in ambient air

ARTICULO DE INVESTIGACIÓNARTICULO DE INVESTIGACIÓ

Temas selectos en ciencia de materiales i (pdf)

Se presentan una selección de 12 capítulos de diferentes investigadores , los temas de esta obra se encuentran relacionados con polímeros y sus compuestos, nanoestructuras metálicas y óxidos metálicos.El presente libro de investigación tiene como objetivo difundir a la comunidad estudiantil de nivel licenciatura y posgrado, principalmente, algunos temas de actualidad en el campo de Ciencia de Materiales, para motivarla e interesarla en esa área tan importante. Se espera también que el libro sea de utilidad para estudiantes de posgrado en Ciencias e Ingeniería de Materiales o áreas afines

Effect of thermal treatment on Zn nanodisks

Artículo asociado a tesis de Doctorado del estudiante Pedro Estanislao Acuña AvilaMetallic Zn nanodisks with hexagonal morphology were obtained onto glass sub- strate under vacuum thermal evaporation. A thermal characterization of Zn nanodiks showed a lower oxidation temperature than source powder Zn. Different thermal treatment on Zn nanodisks played an important role on the morphology, crystal size and surface vibrational modes of ZnO. The growth of ZnO nanoneedles started at the edge of metallic zinc hexagonal structures according with SEM images, the higher temperature the longer needles were grown. XRD diffractogram confirmed the wurtzite structure of ZnO with metallic nuclei. A wide band between 530 and 580 cm−1 of Raman scattering corresponded at surface vibrational modes not observed at higher temperatur

Ether gas-sensor based on Au nanoparticles-decorated ZnO microstructures

Trabajo de Investigación derivado de la estancia Posdoctoral del Dr. Roberto LópezAn ether gas-sensor was fabricated based on gold nanoparticles (Au-NPs) decorated zinc oxide microstructures (ZnO-MS). Scanning electron microscope (SEM) and high-resolution transmission elec- tron microscope (HRTEM) measurements were performed to study morphological and structural proper- ties, respectively, of the ZnO-MS. The gas sensing response was evaluated in a relatively low temperature regime, which ranged between 150 and 250 C. Compared with a sensor fabricated from pure ZnO-MS, the sensor based on Au-NPs decorated ZnO-MS showed much better ether gas response at the highest working temperature. In fact, pure ZnO-MS based sensor only showed a weak sensitivity of about 25%. The improvement of the ether gas response for sensor fabricated with Au-NPs decorated ZnO-MS was attributed to the catalytic activity of the Au-NPs.Investigación realizada bajo proyecto UAEM 1025/2014RIF

Aquatic ecosystems in Byers Peninsula, Livingston Island. An Antarctic Noah’s Ark in a changing world

第6回極域科学シンポジウム[OB] 極域生物圏11月17日（火）　統計数理研究所 セミナー室1（D305

¡El pueblo no se rinde en la pandemia!

El 2020 estuvo marcado por el número de medidas restrictivas emitidas para enfrentar la pandemia del Covid-19[1], fortalecer y preparar el sistema de salud nacional y proteger la salud de los colombianos. Además de la evidente crisis en el sistema de salud, dada su incapacidad para atender un número significativo de ciudadanos, las medidas de confinamiento adoptadas por las autoridades nacionales, regionales y municipales produjeron una crisis social y económica nunca antes vista. Amplios sectores de la sociedad colombiana se quedaron sin empleo o fuente de ingresos. En este sentido, la privación de recursos para el sostenimiento de las familias fue extendida a varios estratos del país. Las carencias económicas para cubrir las necesidades básicas de los hogares colombianos se sintieron tanto en los sectores populares, como en las clases medias y profesionales del país

Enhanced hydrogen production from thermochemical processes

To alleviate the pressing problem of greenhouse gas emissions, the development and deployment of sustainable energy technologies is necessary. One potentially viable approach for replacing fossil fuels is the development of a H2 economy. Not only can H2 be used to produce heat and electricity, it is also utilised in ammonia synthesis and hydrocracking. H2 is traditionally generated from thermochemical processes such as steam reforming of hydrocarbons and the water-gas-shift (WGS) reaction. However, these processes suffer from low H2 yields owing to their reversible nature. Removing H2 with membranes and/or extracting CO2 with solid sorbents in situ can overcome these issues by shifting the component equilibrium towards enhanced H2 production via Le Chatelier's principle. This can potentially result in reduced energy consumption, smaller reactor sizes and, therefore, lower capital costs. In light of this, a significant amount of work has been conducted over the past few decades to refine these processes through the development of novel materials and complex models. Here, we critically review the most recent developments in these studies, identify possible research gaps, and offer recommendations for future research

Association between convalescent plasma treatment and mortality in COVID-19: a collaborative systematic review and meta-analysis of randomized clinical trials.

Funder: laura and john arnold foundationBACKGROUND: Convalescent plasma has been widely used to treat COVID-19 and is under investigation in numerous randomized clinical trials, but results are publicly available only for a small number of trials. The objective of this study was to assess the benefits of convalescent plasma treatment compared to placebo or no treatment and all-cause mortality in patients with COVID-19, using data from all available randomized clinical trials, including unpublished and ongoing trials (Open Science Framework, https://doi.org/10.17605/OSF.IO/GEHFX ). METHODS: In this collaborative systematic review and meta-analysis, clinical trial registries (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform), the Cochrane COVID-19 register, the LOVE database, and PubMed were searched until April 8, 2021. Investigators of trials registered by March 1, 2021, without published results were contacted via email. Eligible were ongoing, discontinued and completed randomized clinical trials that compared convalescent plasma with placebo or no treatment in COVID-19 patients, regardless of setting or treatment schedule. Aggregated mortality data were extracted from publications or provided by investigators of unpublished trials and combined using the Hartung-Knapp-Sidik-Jonkman random effects model. We investigated the contribution of unpublished trials to the overall evidence. RESULTS: A total of 16,477 patients were included in 33 trials (20 unpublished with 3190 patients, 13 published with 13,287 patients). 32 trials enrolled only hospitalized patients (including 3 with only intensive care unit patients). Risk of bias was low for 29/33 trials. Of 8495 patients who received convalescent plasma, 1997 died (23%), and of 7982 control patients, 1952 died (24%). The combined risk ratio for all-cause mortality was 0.97 (95% confidence interval: 0.92; 1.02) with between-study heterogeneity not beyond chance (I2 = 0%). The RECOVERY trial had 69.8% and the unpublished evidence 25.3% of the weight in the meta-analysis. CONCLUSIONS: Convalescent plasma treatment of patients with COVID-19 did not reduce all-cause mortality. These results provide strong evidence that convalescent plasma treatment for patients with COVID-19 should not be used outside of randomized trials. Evidence synthesis from collaborations among trial investigators can inform both evidence generation and evidence application in patient care