Influence of VOF technique, turbulence model and discretization scheme on the numerical simulation of the non-aerated, skimming flow in stepped spillways

[EN] An accurate description of the hydrodynamics in the non-aerated region of the skimming flow on stepped spillways is of outmost importance, particularly in small structures at large discharges. In addition, the flow features upstream of the inception point of air entrainment determine the flow behavior in the downstream self aerated region. In this work, numerical models of the flow in the non-aerated region of stepped spillways have been developed using diverse turbulence closures and discretization schemes implemented in two CFD codes: OpenFOAM and FLOW-3D (R). Partial VOF (Volume of Fluid) and "True" VOF (TruVOF) approaches are employed to capture the position of the free surface. The Standard, RNG and Realizable k-epsilon, in addition to the SST k-omega model, are used for turbulence closure. Numerical results are compared against reference experimental results obtained from a physical model of constant slope of 0.75H:1V. Models with turbulence closures of the k-epsilon family provide nearly the same predictions for the mean flow velocity with maximum differences on average smaller than 1%. Regarding discretization schemes, the first-order upwind method provides predictions for the mean flow velocity which are not significantly different (within 6%) than those obtained with second-order counterparts. However, these differences can be larger when maximum values of turbulent kinetic energy (TKE) and dissipation rate of TKE at the step edges are compared. In spite of the fact that the TruVOF (FLOW-3D (R)) method does not account for the tangential stresses at the air-water interface, differences in the tracking of the free surface position among this method and the Partial VOF method (OpenFOAM) were found to be smaller than 3% along the stepped spillway. In this work, we also provide a physical interpretation of the flow results.This study was made possible due to the financial support of the PhD program "VALi + D", funded by Generalitat Valenciana (Spain). The second author acknowledges the support of the National Commission for Scientific and Technological Research (CONICYT), through a "Becas Chile" fellowship.Bayón Barrachina, A.; Toro, J.; Bombardelli, F.; Matos, J.; López Jiménez, PA. (2017). Influence of VOF technique, turbulence model and discretization scheme on the numerical simulation of the non-aerated, skimming flow in stepped spillways. Journal of Hydro-Environment Research (Online). 19:137-149. doi:10.1016/j.jher.2017.10.002S1371491

A study on the internal convection in small turbochargers. Proposal of heat transfer convective coefficients

Nowadays turbochargers play an important role in improving internal combustion engines (ICE) performance. Usually, engine manufacturers use computer codes to predict the behaviour of both engine and turbocharger, the later by means of measured look-up maps. Using look-up maps different problems arise, being one of the most important the difference in heat transfer between the current operating condition and the conditions at which maps were measured. These effects are very important at low to medium turbocharger speeds (typical condition of urban driving conditions) where heat transfer can even be higher than mechanical power. In this work, the different convective heat transfer phenomena inside these kind of machines have been measured and analysed. Besides, general correlations for these flows, based on dimensionless numbers, are fitted and validated in three different turbochargers. The applicability of the model is shown by comparison the main results obtained when the model is used and not, improving up to 20 C the predicted turbine outlet temperature. The main advantages of applying these correlations rely on predicting fluids outlet temperatures (compressor, turbine, oil and coolant). The former is needed to feed accurately ICE model, turbine outlet temperature is important for aftertreatment device modelling while oil and coolant temperatures are important in order to design optimum cooling systems.This work has been partially supported by the Spanish Ministerio de Economa y Competitividad through grant no. TRA2012-36954. The equipment used in this work has been partially supported by FEDER project funds "Dotacion de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT), (FEDER-ICTS-2012-06)", framed in the operational program of unique scientific and technical infrastructure of the Ministry of Science and Innovation of Spain.Serrano Cruz, JR.; Olmeda González, PC.; Arnau Martínez, FJ.; Reyes Belmonte, MÁ.; Tartoussi, H. (2015). A study on the internal convection in small turbochargers. Proposal of heat transfer convective coefficients. Applied Thermal Engineering. 89:587-599. https://doi.org/10.1016/j.applthermaleng.2015.06.053S5875998

Biospas proyecto 2 : micorrizas, patógenos, meso-macro-fauna y biocontrol (Pae- pid-2007-0054)

El actual sistema agrícola de Argentina basa la mayor parte de su producción en la siembra directa y una limitada rotación de cultivos. En base a el paradigma de la sustentabilidad se pueden evaluar cambios en la asociación de Hongos Micorrícicos (HM) con raíces de diversos cultivos y las poblaciones presentes en el suelo; la incidencia de enfermedades en el cultivo y los niveles de inóculo presentes en los rastrojos y asimismo la supresividad de los suelos y por consiguiente la presencia de enfermedad de los cultivos y el efecto de control que pudieran proveer las Micorrizas Arbusculares (MA). El planteo de SD versus LT también plantea modificaciones tanto de la estructura del suelo como en el sistema y las comunidades de Meso y Macrofauna (MMF) que en él habitan. La hipótesis de trabajo plantea que la incidencia y severidad de las fitoenfermedades puede disminuirse por la rotación de cultivos y que las poblaciones de hongos micorrícicos se modifican según la secuencia de rotación. Esto a su vez implica que, incidencia y/o severidad de una enfermedad pueden ser modificadas por HM presentes en el suelo. Por otro lado, abundancia y atributos estructurales de la comunidad de MMF del suelo son afectados por los sistemas de manejo. En este proyecto se determinaran morfológica y molecularmente las especies integrantes de las poblaciones de HM en diferentes secuencias de cultivo. Se compararán las poblaciones de HM presentes en el suelo y las poblaciones en simbiosis activa con raíces de los diferentes cultivos. Se caracterizará y comparará cultivo, suelo y rastrojo desde el punto de vista fitopatológico en diferentes esquemas de rotación. Como resultado de esto se determinará la existencia de interacciones entre la incidencia de enfermedades y la presencia de determinadas micorrizas y evaluar el efecto de cada sistema de manejo sobre la abundancia y los atributos estructurales de la comunidad de MMF del suelo.Fil: Ducasse, Daniel Adrián. Universidad Católica de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Plazas, María Cristina. Universidad Católica de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: De Rossi, Roberto Luis. Universidad Católica de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Guerra, Gustavo Darío. Universidad Católica de Córdoba. Facultad de Ciencias Agropecuarias; Argentin

Solid Organ Transplantation During COVID-19 Pandemic: An International Web-based Survey on Resources’ Allocation

Background. Solid organ transplants (SOTs) are life-saving interventions, recently challenged by coronavirus disease 2019 (COVID-19). SOTs require a multistep process, which can be affected by COVID-19 at several phases. Methods. SOT-specialists, COVID-19-specialists, and medical ethicists designed an international survey according to CHERRIES guidelines. Personal opinions about continuing SOTs, safe managing of donors and recipients, as well as equity of resources' allocation were investigated. The survey was sent by e-mail. Multiple approaches were used (corresponding authors from Scopus, websites of scientific societies, COVID-19 webinars). After the descriptive analysis, univariate and multivariate ordinal regression analysis was performed. Results. There were 1819 complete answers from 71 countries. The response rate was 49%. Data were stratified according to region, macrospecialty, and organ of interest. Answers were analyzed using univariate- multivariate ordinal regression analysis and thematic analysis. Overall, 20% of the responders thought SOTs should not stop (continue transplant without restriction); over 70% suggested SOTs should selectively stop, and almost 10% indicated they should completely stop. Furthermore, 82% agreed to shift resources from transplant to COVID-19 temporarily. Briefly, main reason for not stopping was that if the transplant will not proceed, the organ will be wasted. Focusing on SOT from living donors, 61% stated that activity should be restricted only to "urgent"cases. At the multivariate analysis, factors identified in favor of continuing transplant were Italy, ethicist, partially disagreeing on the equity question, a high number of COVID-19- related deaths on the day of the answer, a high IHDI country. Factors predicting to stop SOTs were Europe except-Italy, public university hospital, and strongly agreeing on the equity question. Conclusions. In conclusion, the majority of responders suggested that transplant activity should be continued through the implementation of isolation measures and the adoption of the COVID-19-free pathways. Differences between professional categories are less strong than supposed

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

CD8 T Cell Memory Recall Is Enhanced by Novel Direct Interactions with CD4 T Cells Enabled by MHC Class II Transferred from APCs

<div><p>Protection against many intracellular pathogens is provided by CD8 T cells, which are thought to need CD4 T cell help to develop into effective memory CD8 T cells. Because murine CD8 T cells do not transcribe MHC class II (MHC-II) genes, several models have proposed antigen presenting cells (APCs) as intermediaries required for CD4 T cells to deliver their help to CD8 T cells. Here, we demonstrate the presence of MHC-II molecules on activated murine CD8 T cells in vitro as well as in vivo. These MHC-II molecules are acquired via trogocytosis by CD8 T cells from their activating APCs, particularly CD11c positive dendritic cells (DCs). Transferred MHC-II molecules on activated murine CD8 T cells were functionally competent in stimulating specific indicator CD4 T cells. CD8 T cells that were “helped” in vitro and subsequently allowed to rest in vivo showed enhanced recall responses upon challenge compared to “helpless” CD8 T cells; in contrast, no differences were seen upon immediate challenge. These data indicate that direct CD8∶CD4 T cell interactions may significantly contribute to help for CD8 T cells. Furthermore, this mechanism may enable CD8 T cells to communicate with different subsets of interacting CD4 T cells that could modulate immune responses.</p> </div

Association between cardiovascular disease risk scores and subclinical atherosclerosis prevalence in non-elderly adult patients from Argentina

The goal of our study was to use statistical analysis to try to associate cardiovascular disease (CVD) risk scores and the observed prevalence of subclinical atherosclerosis (SA) in a non-elderly adult local population. An observational cross-sectional study was carried out (143 male and 131 female) on non-elderly adults (20?59 years). CVD risk scores included Framingham Risk Scores for 10-year hard (FRS 10 H), 30-year lipid hard or CVD (FRS 30 L H or FRS 30 L CVD), 30 year-body mass index hard or CVD (FRS 30 BMI H or FRS 30 BMI CVD) and Pooled Cohort Risk Equations for either 10 years (PCE 10) or lifetime (PCE LT). The Carotid Ultrasound (CU) study was performed and the Coronary Artery Calcium (CAC) score were obtained to assess SA. The Receiving Operating Characteristic (ROC) curve analysis followed by Youden?s index was used to evaluate and adjust the stratification of CVD risk scores. SA was detected in 32.4% of individuals. The risk scores that showed the biggest areas under the ROC curve were FRS 30 L (H and CVD). When the cut-off values for these CVD risk scores were adjusted, the FRS 30 L H increased the negative predictive value for the low risk group from 87.7 to 97.0% and the FRS 30 L CVD increased the positive predictive values for the high risk group from 69.7 to 85.7%. The CVD risk stratification of non-elderly adults using FRS 30 L H and FRS 30 L CVD may be a useful tool for selecting candidate patients for diagnostic imaging studies that assess their SA prevalence.Fil: Albertini, Ricardo A.. Instituto Universitario de Ciencias Biomédicas de Córdoba; Argentina. Hospital Privado Centro Medico de Córdoba; ArgentinaFil: Ferrer, Dario German. Hospital Privado Centro Medico de Córdoba; ArgentinaFil: Romagnoli, Pablo A.. Instituto Universitario de Ciencias Biomédicas de Córdoba; ArgentinaFil: Tinti, María E.. Hospital Privado Centro Medico de Córdoba; ArgentinaFil: Amigone, José L.. Hospital Privado Centro Medico de Córdoba; ArgentinaFil: Capra, Raúl. Hospital Privado Centro Medico de Córdoba; ArgentinaFil: Chiabrando, Gustavo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentin

In vitro interactions improve the in vivo recall response of CD8 T cells.

<p>P14 cells were specifically activated in vitro using gp33-41 peptide in the presence of either ova323-339 (OTII) or gp61-81 (SMARTA) peptide for 24 hrs. Activated CD8 T cells were then magnetically isolated and cultured with experienced CD4 T cells for another 24 hrs. Activated CD8 T cells were again magnetically isolated and adoptively transferred into WT mice. Animals were challenged with 5×10⁴ c.f.u. of Lmgp33 i.v. at <b>a</b>) 1 day (day +1) or <b>b</b>) 30 days (day +30) after transfer. Stimulation for ICS and flow cytometry analysis was performed on spleens taken 4 days after Lmgp33 challenge. Events were gated on live CD19−Thy1.1+CD8+. **p = 0.0079. Plots are representative from one of at least two independent experiments.</p