Fast reduction of Cr(VI) from aqueous solutions using alumina

artículo ya publicadoHexavalent chromium is challenging to remove from industrial wastewater due the solubility and anionic nature of the chromates. Cr(VI) is typically removed by reduction to Cr(III), then precipitation or adsorption, which requires multiple steps and bulk reagents and generates sludge. In this project, we have evaluated a sintered alumina disk as a single step sorbent for Cr(VI). The disk was porous enough that 20 mL samples passed through in about 3 s using light suction. A single pass through the disk only reduced the [Cr(VI)] by 10–20%, but by passing the solution through the disk five times up to 80% was removed in samples up to 130 mg/L and up to around 50% for much higher concentrations. The five passes through the filter disk took less than a minute. On each pass through the disk the characteristic chromate UV–vis absorbance decreased, the Cr(VI) concentration (by the diphenylcarbazide method) decreased, and the pH rose slightly. The XRD pattern showed no change in the crystal structure of the alumina, but the SEM/EDS identified chromium on the surface. In addition to confirming chromium on the surface of the alumina, the XPS spectra showed a change in the binding energy of the aluminum, which is consistent with complexation. The system was fast and effective (in series), so should be applicable to industrial wastewater treatment.UAEMex, CONACy

Vertical zonation of bacterial assemblages attributed to physical stratification during the summer relaxation of the coastal upwelling off Galicia (NW Spain)

Research articleWe combined flow cytometry, CARD-FISH, and 16S rRNA gene tag pyrosequencing to investigate bacterioplankton dynamics along a transect in shelf waters off A Coruña (Galicia, NW Spain). Over five days (16-20th July 2012) we sampled during the relaxation of a summer upwelling pulse, providing an opportunity to examine the impact of pulses of cold nutrient-rich water into coastal microbial communities. The hydrographic conditions, characterized by intense density stratification of surface waters and the presence of a deep chlorophyll maximum (DCM) at 20–30 m, were relatively maintained over the sampling period. Indeed, bacterial abundance and composition displayed low day to day variation. Alpha diversity analysis suggested that species richness and diversity increased from coastal to shelf stations and from the surface down to the coastal DCM, which could be caused by the mixing of upwelled bacteria with the coastal surface waters. SAR11, SAR86, and Roseobacter were the most abundant bacteria detected in the samples by using CARD-FISH. The assemblages observed by pyrosequencing displayed a strong vertical zonation along the transect. Rhodobacteraceae (under class Alphaproteobacteria) and Bacteriodetes dominated the surface waters and decreased during the upwelling pulse, while SAR 86 (under class Gammaproteobacteria), Actinobacteria and SAR11 clade increased their relative abundance at the coastal DCM with upwelling relaxation, particularly at the shelf stations. Bacterial assemblages from surface waters were associated with higher temperature and light conditions, while coastal DCM assemblages were rather associated to salinity, inorganic nutrients and a diatom-bloom leading to high chlorophyll-a. Our findings suggest that the vertical variability in environmental conditions induced by the intense density stratification, the exportation of warmer and less saline surface water from the rias to the adjacent shelf, and the fertilizing effect of recently upwelled water at the deeper layer, determined the composition of distinct bacterial assemblages at the subsurface and DCM layers.XUNTA DE GALICIA (O9MMA 027604PR, 10MMA604024PR), IEO (PROYECTO RADIALES) y PLAN NACIONAL (MODUPLAN CTM2011-24008)Versión del editor2,24

Polymer waste materials as fillers in polymer mortars: experimental and finite elements simulation

Serious environmental problems are due to large amounts of polymer waste, which are mostly thrown into landfills. As we known, polymer composites has been used to produce a variety of products like acid tanks, manholes, drains, highway median barriers, and so forth. One option is to use waste polymers as aggregates in polymer composites. In this work, waste polymers (PET, polycarbonate and automotive tires), partially replaced silica sand in polyester based mortar. Waste particles (0.7–2.36 mm), in concentrations of 1, 2 and 3% by weight, were used. The polymer mortar specimens were subjected to compressive and flexural tests, and the elasticity modulus was calculated. In addition, mechanical values were calculated by Finite Element Method (FEM), and compared with experimental data. Surface morphology and degree of crystallinity of waste particles were analyzed by SEM and XRD techniques, respectively. The results show improvement on the mechanical strength (up to 20%) for polymer mortar with waste PET; but lower mechanical values when adding polycarbonate or tire particles, compared to control mortar. These mechanical results can be related to the crystallinity degree, because PET particles shown higher crystallinity than those for polycarbonate and tire particles. This work is an alternative to reduce environmental contamination through to use waste polymers as fillers in polymer mortars. Keywords: Polymer waste, Polymer mortar, Polyethylene terephthalate, Polycarbonate, Tire rubber, Mechanical propertie

Facile solventless synthesis of a nylon-6,6/silver nanoparticles composite and its XPS study

SINTESIS DE NANOPARTICULASSilver nanoparticles were synthesized and supported on thin nylon membranes by means of a simple method of impregnation and chemical reduction of Ag ions at ambient conditions. Particles of less than 10nm were obtained using this methodology, in which the nylon fibers behave as constrained nanoreactors. Pores on nylon fibres along with oxygen and nitrogen from amide moieties in nylon provide effective sites for in situ reduction of silver ions and for the formation and stabilization of Ag nanoparticles. Transmission electron microscopy (TEM) analysis showed that silver nanoparticles are well dispersed throughout the nylon fibers. Furthermore, an interaction betweenUAEME

Short term variability of bacterial communities in the shelf waters off Galicia (NW Iberian Peninsula): Patterns and drivers shaping the diversity

PósterEcological and biogeochemical processesEcological and biogeochemical processes in the ocean are dependent on a diverse assemblage of microbes, including members of Bacteria (Glöckner et al, 2012). These bacterial assemblages occurs in vast numbers and represent a huge genetic diversity, fulfilling a wide of ecological roles in the marine system such as carbon geochemical cycle and energy transfer into higher trophic levels.We combined flow cytometry, CARD-FISH and 16S rRNA gene tag pyrosequencing to investigate the short-term variability of the bacterial communities in samples collected along a transect in the shelf off NW Iberian Peninsula over one week

Optical properties of dissolved organic matter relate to different dept-specific patterns of archaeal and bacterial community structure in the North Atlantic Ocean

ArticleProkaryotic abundance, activity and community composition were studied in the euphotic, intermediate and deep waters off the Galician coast (NW Iberian margin) in relation to the optical characterization of dissolved organic matter (DOM). Microbial (archaeal and bacterial) community structure was vertically stratified. Among the Archaea, Euryarchaeota, especially Thermoplasmata, was dominant in the intermediate waters and decreased with depth, whereas marine Thaumarchaeota, especially Marine Group I, was the most abundant archaeal phylum in the deeper layers. The bacterial community was dominated by Proteobacteria through the whole water column. However, Cyanobacteria and Bacteroidetes ocurrence was considerable in the upper layer and SAR202 was dominant in deep waters. Microbial composition and abundande were not shaped by the quantity of dissolved organic carbon, but instead they revealed a strong connection with the DOM quality. Archaeal communities were mainly related to the fluorescence of DOM (which indicates respiration of labile DOM and generation of refractory subproducts), while bacterial communities were mainly linked to the aromaticity/age of the DOM produced along the water column. Taken together, our results indicate that the microbial community composition is associated with the DOM composition of the water masses, suggesting that distinct microbial taxa have the potential to use and/or produce specific DOM compounds.Versión del edito

Synthesis and characterization of a Bio-MOF based on mixed adeninate/tricarboxylate ligands and zinc ions

Artículo científicoIn this work, we present a new metal organic framework Zn7(Ad)4(BTC)4(DMF)O·4DMA·3DMF·4H2O which was synthesized under hydrothermal conditions with adenine and trimesic acid (BTC) linkers. The structure was determined by single-crystal (XRD) and the compound was further characterized by Scanning electron microscopy (SEM), infrared spectroscopy (IR), and thermogravimetric analysis. The 3D anionic framework includes adenine present in two-different coordination modes, with dimethylammonium balancing the framework charg

Clustering COVID-19 ARDS patients through the first days of ICU admission. An analysis of the CIBERESUCICOVID Cohort

Background Acute respiratory distress syndrome (ARDS) can be classified into sub-phenotypes according to different inflammatory/clinical status. Prognostic enrichment was achieved by grouping patients into hypoinflammatory or hyperinflammatory sub-phenotypes, even though the time of analysis may change the classification according to treatment response or disease evolution. We aimed to evaluate when patients can be clustered in more than 1 group, and how they may change the clustering of patients using data of baseline or day 3, and the prognosis of patients according to their evolution by changing or not the cluster.Methods Multicenter, observational prospective, and retrospective study of patients admitted due to ARDS related to COVID-19 infection in Spain. Patients were grouped according to a clustering mixed-type data algorithm (k-prototypes) using continuous and categorical readily available variables at baseline and day 3.Results Of 6205 patients, 3743 (60%) were included in the study. According to silhouette analysis, patients were grouped in two clusters. At baseline, 1402 (37%) patients were included in cluster 1 and 2341(63%) in cluster 2. On day 3, 1557(42%) patients were included in cluster 1 and 2086 (57%) in cluster 2. The patients included in cluster 2 were older and more frequently hypertensive and had a higher prevalence of shock, organ dysfunction, inflammatory biomarkers, and worst respiratory indexes at both time points. The 90-day mortality was higher in cluster 2 at both clustering processes (43.8% [n = 1025] versus 27.3% [n = 383] at baseline, and 49% [n = 1023] versus 20.6% [n = 321] on day 3). Four hundred and fifty-eight (33%) patients clustered in the first group were clustered in the second group on day 3. In contrast, 638 (27%) patients clustered in the second group were clustered in the first group on day 3.Conclusions During the first days, patients can be clustered into two groups and the process of clustering patients may change as they continue to evolve. This means that despite a vast majority of patients remaining in the same cluster, a minority reaching 33% of patients analyzed may be re-categorized into different clusters based on their progress. Such changes can significantly impact their prognosis

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Ecos de la academia: Revista de la Facultad de Educación, Ciencia y Tecnología - FECYT Nro 4

Ecos de la academia, Revista de la Facultad de Educación Ciencia y Tecnología es una publicación científica de la Universidad Técnica del Norte, con revisión por pares a doble ciego que publica artículos en idioma español, quichua, portugués e inglés. Se edita con una frecuencia semestral con dos números por año.En ella se divulgan trabajos originales e inéditos generados por los investigadores, docentes y estudiantes de la FECYT, y contribuciones de profesionales de instituciones docentes e investigativas dentro y fuera del país, con calidad, originalidad y relevancia en las áreas de ciencias sociales y tecnología aplicada.Los orígenes de la fotografía en la segunda ciudad de Cataluña: Reus, 1839-1903. Hábitos de consumo y uso de medios digitales en los estudiantes de la Universidad Técnica del Norte. Gastronomía, historia y cultura afrodescendiente de las comunidades Chota y Salinas en Imbabura, Ecuador. Los organizadores gráficos: elementos y procedimientos básicos para su diseño. Análisis del desempeño profesional del graduado de la carrera de Licenciatura en Inglés de la Universidad Técnica del Norte. Uso del software Aleks como complemento en la asignatura de Fundamentos de Matemáticas del curso de nivelación EPN-SENECYT. La educación de postgrado y la enseñanza de Redes Neuronales Artificiales como herramienta versátil para egresados. Home is an uneasty place: Afroperipheralism anda diasporic sensibilities in Wayde Compton’s “The Instrumental”. Respuesta de la carrera de Educación Básica a las necesidades sociales en la Zona 1 del Ecuador. Programa SaludArte: Salud, Alimentación y Movimiento entran a las escuelas para mejorar la calidad educativa. Tendencias de consumo turístico de los Millennials en la ciudad de Ibarra. Los Grupos de Investigación como estrategias para desarrollo de la investigación científica en las instituciones de educación superior ecuatorianas. Paradigmas y modelos pedagógicos de los postulados científicos en el espacio de aula en la Universidad Técnica de Ambato. Predicting academic performance in traditional environments at higher-education institutions using data mining: A review. El Proyecto de Investigación “Muros que hablan. Un recorrido por los graffitis de Imbabura”. Construcción de la marca ciudad. Normas de presentación de artículos científicos en la revista Ecos de la Academia