Modelo matemático bidimensional para el estudio del flujo de agua a través de un decantador rectangular con lamelas

[ES] El presente artículo describe un modelo matemático bidimensional elaborado para el estudio del flujo de agua en el interior de un decantador rectangular con lamelas. Este modelo matemático integra la ecuación de Laplace por el método de los elementos finitos, obteniéndose el campo de valores de la función potencial en el interior del decantador, del cual se deducen las componentes de velocidad en todos los puntos de estudio. Este modelo matemático se ha utilizado para estudiar el flujo en el interior de un decantador destinado a la potabilización de agua, que la empresa Aguas de Valencia, S.A. está desarrollando de cara a su construcción en futuras instalaciones. A partir de diferentes diseños básicos sugeridos por dicha empresa, se pretende estudiar el efecto de recirculación forzada del agua de entrada originado por un agitador instalado en la zona de floculación. Además, en la zona de decantación se busca que el flujo ascensional se distribuya lo más uniformemente posible en toda la zona de lamelas, a fin de conseguir un mayor aprovechamiento de éstas y por tanto, un mejor rendimiento del decantador. Para ello se ha estudiado el tipo de dispositivo de recogida del agua decantada a instalar, así como su distribución sobre la superficie del decantador, resultando como más favorable la instalación de tres canaletas almenadas que forman vertederos rectangulares en la superficie libre del agua en la zona de decantación, y un vertedero transversal al final de dicha zona.El presente artículo está basado en el Contrato para Proyecto de Investigación y Desarrollo firmado en Septiembre de 1994 entre la Universidad Politécnica de Valencia y la empresa Aguas de Valencia, S.A. con el título “Elaboración y puesta a punto de un modelo matemático bidimensional para el estudio del flujo de agua a través de un decantador rectangular con lamelas”. Agradecemos a .la empresa Aguas de Valencia, S.A. las facilidades ofrecidas para el desarrollo de este Estudio, así como la autorización concedida para la publicación de los resultados del mismo.Espert Alemany, V.; García, M.; Sancho, H.; López Jiménez, AP. (1996). Modelo matemático bidimensional para el estudio del flujo de agua a través de un decantador rectangular con lamelas. Ingeniería del Agua. 3(3):15-28. https://doi.org/10.4995/ia.1996.2701SWORD152833Andrés, M. (1994). Diseño de una Planta Potabilizadora. Las de Picassent y Manises. Curso de Abastecimiento de Agua Potable: Calidad y Tratamientos. Valencia, 22 al 25 de Marzo de 1994. U.D. Mecánica de Fluidos (Universidad Politécnica de Valencia) y EGEVASA (Excma. Diputación de Valencia). 52 pág.Chung, TJ. (977). Finite Element Analvsis in Fluid Dynamics. Ed. McGraw Hill. New York.Degremont (1979). Manual Técnico del Agua (4a ed.). S.A.E. de Depuración de Aguas Degremont.Hinton, E. y Owen, D.R.J. (1977). Finite Element Programming. Ed. Academic Press. Londres.McGhee, T.J. (1991). Water Supply and Sewerage (6th ed.). Ed. McGraw Hill. New York.Salvato, J.A. (1992). Environmental Engineering and Sanitation (4th ed.). Ed. John Wiley and Sons. New York.Sanks, R.L. (1978). Water Tratment Plant Design for the Practicing Engineer. Ed. Ann Arbor Science. Michigan.U.D. Mecánica de Fluidos (1995). Curso de Ingeniería Hidráulica Aplicada a los Sistemas de Distribución de Agua (Tomo I). U.D. Mecánica de Fluidos (Universidad Politécnica de Valencia) y Aguas de Valencia, S.A

Electrochemical oxidation of dibenzothiophene compounds on BDD electrode in acetonitrile-water medium

The electrochemical oxidation of dibenzothiophene and two derivatives, namely 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene, was investigated either separately or as a mixture, on a BDD anode in a miscible acetonitrile (87.5% v/v)-water (12.5% v/v, 0.01 M NaNO3) solution. Linear sweep voltammetry, cyclic voltammetry, chronoamperometry and bulk electrolysis under potentiostatic conditions suggested the probable occurrence of two pathways: direct electrochemical oxidation and indirect reaction with hydroxyl radicals and other reactive oxygen species formed at the BDD anode surface during water discharge. The products extracted upon electrolysis at 1.5 and 2.0 V vs. SCE were analyzed by Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry and ultra-high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS). The main molecules identified were the corresponding sulfoxides or sulfones, depending on the applied anodic potential. Possible oxidation routes for the dibenzothiophene compounds are proposed

Benchmarking Density Functionals on Structural Parameters of Small-/Medium-Sized Organic Molecules

In this Letter we report the error analysis of 59 exchange-correlation functionals in evaluating the structural parameters of small- and medium-sized organic molecules. From this analysis, recently developed double hybrids, such as xDH-PBE0, emerge as the most reliable methods, while global hybrids confirm their robustness in reproducing molecular structures. Notably the M06-L density functional is the only semilocal method reaching an accuracy comparable to hybrids’. A comparison with errors obtained on energetic databases (including thermochemistry, reaction barriers, and interaction energies) indicate that most of the functionals have a coherent behavior, showing low (or high) deviations on both energy and structure data sets. Only a few of them are more prone toward one of these two properties.A.J.P.-J. and J.C.S.-G. thank the “Ministerio de Economía y Competitividad” of Spain and the “European Regional Development Fund” through Project CTQ2014-55073-P for financial and computational support. X.X. thanks the National Natural Science Foundation of China (Grants 91427301 and 21133004) and the Ministry of Science and Technology (Grant 2013CB834606)

A first-principles approach to electrical transport in atomic-scale nanostructures

We present a first-principles numerical implementation of Landauer formalism for electrical transport in nanostructures characterized down to the atomic level. The novelty and interest of our method lies essentially on two facts. First of all, it makes use of the versatile Gaussian98 code, which is widely used within the quantum chemistry community. Secondly, it incorporates the semi-infinite electrodes in a very generic and efficient way by means of Bethe lattices. We name this method the Gaussian Embedded Cluster Method (GECM). In order to make contact with other proposed implementations, we illustrate our technique by calculating the conductance in some well-studied systems such as metallic (Al and Au) nanocontacts and C-atom chains connected to metallic (Al and Au) electrodes. In the case of Al nanocontacts the conductance turns out to be quite dependent on the detailed atomic arrangement. On the contrary, the conductance in Au nanocontacts presents quite universal features. In the case of C chains, where the self-consistency guarantees the local charge transfer and the correct alignment of the molecular and electrode levels, we find that the conductance oscillates with the number of atoms in the chain regardless of the type of electrode. However, for short chains and Al electrodes the even-odd periodicity is reversed at equilibrium bond distances.Comment: 14 pages, two-column format, submitted to PR

Predicting understory maximum shrubs cover using altitude and overstory basal area in different Mediterranean forests

In some areas of the Mediterranean basin where the understory stratum represents a critical fire hazard, managing the canopy cover to control the understory shrubby vegetation is an ecological alternative to the current mechanical management techniques. In this study, we determine the relationship between the overstory basal area and the cover of the understory shrubby vegetation for different dominant canopy species (Pinaceae and Fagaceae species) along a wide altitudinal gradient in the province of Catalonia (Spain). Analyses were conducted using data from the Spanish National Forest Inventory. At the regional scale, when all stands are analysed together, a strong negative relationship between mean shrub cover and site elevation was found. Among the Pinaceae species, we found fairly good relationships between stand basal area and the maximum development of the shrub stratum for species located at intermediate elevations (Pinus nigra, Pinus sylvestris). However, at the extremes of the elevationclimatic gradient (Pinus halepensis and Pinus uncinata stands), stand basal area explained very little of the shrub cover variation probably because microsite and topographic factors override its effect. Among the Fagaceae species, a negative relationship between basal area and the maximum development of the shrub stratum was found in Quercus humilis and Fagus sylvatica dominated stands but not in Quercus ilex. This can be due to the particular canopy structure and management history of Q. ilex stands. In conclusion, our study revealed a marked effect of the tree layer composition and the environment on the relationship between the development of the understory and overstory tree structure. More fine-grained studies are needed to provide forest managers with more detailed information about the relationship between these two forest strata

2013. Documento Sevilla de Consenso sobre Alternativas a la Transfusión de Sangre Alogénica. Actualización del Documento Sevilla

La transfusión de sangre alogénica (TSA) no es inocua, y como consecuencia han surgido múltiples alternativas a la misma (ATSA). Existe variabilidad respecto a las indicaciones y buen uso de las ATSA. Dependiendo de la especialidad de los médicos que tratan a los pacientes, el grado de anemia, la política transfusional, la disponibilidad de las ATSA y el criterio personal, estas se usan de forma variable. Puesto que las ATSA tampoco son inocuas y pueden no cumplir criterios de coste-efectividad, la variabilidad en su uso es inaceptable. Las sociedades españolas de Anestesiología y Reanimación (SEDAR), Hematología y Hemoterapia (SEHH), Farmacia Hospitalaria (SEFH), Medicina Intensiva y Unidades Coronarias (SEMICYUC), Trombosis y Hemostasia (SETH) y Transfusiones Sanguíneas (SETS) han elaborado un documento de consenso para el buen uso de la ATSA. Un panel de expertos de las 6 sociedades ha llevado a cabo una revisión sistemática de la literatura médica y elaborado el 2013. Documento Sevilla de Consenso sobre Alternativas a la Transfusión de Sangre Alogénica. Solo se contempla las ATSA dirigidas a disminuir la transfusión de concentrado de hematíes. Se definen las ATSA como toda medida farmacológica y no farmacológica encaminada a disminuir la transfusión de concentrado de hematíes, preservando siempre la seguridad del paciente. La cuestión principal que se plantea en cada ítem se formula, en forma positiva o negativa, como: «La ATSA en cuestión reduce/no reduce la tasa transfusional». Para formular el grado de recomendación se ha usado la metodología Grades of Recommendation Assessment, Development and Evaluation (GRADE)

Complement component C4 structural variation and quantitative traits contribute to sex-biased vulnerability in systemic sclerosis

Altres ajuts: Fondo Europeo de Desarrollo Regional (FEDER), "A way of making Europe".Copy number (CN) polymorphisms of complement C4 play distinct roles in many conditions, including immune-mediated diseases. We investigated the association of C4 CN with systemic sclerosis (SSc) risk. Imputed total C4, C4A, C4B, and HERV-K CN were analyzed in 26,633 individuals and validated in an independent cohort. Our results showed that higher C4 CN confers protection to SSc, and deviations from CN parity of C4A and C4B augmented risk. The protection contributed per copy of C4A and C4B differed by sex. Stronger protection was afforded by C4A in men and by C4B in women. C4 CN correlated well with its gene expression and serum protein levels, and less C4 was detected for both in SSc patients. Conditioned analysis suggests that C4 genetics strongly contributes to the SSc association within the major histocompatibility complex locus and highlights classical alleles and amino acid variants of HLA-DRB1 and HLA-DPB1 as C4-independent signals

Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality