Evidences of persisting thermal structures in Couette flows

[EN] DNS of passive thermal turbulent Couette flow at several friction Reynolds numbers (180, 250, and 500), and the Prandtl number of air are presented. The time averaged thermal flow shows the existence of long and wide thermal structures never described before in Couette flows. These thermal structures, named CTFS (Couette Thermal Flow Superstructures), are defined as coherent regions of hot and cold temperature fluctuations. They are intrinsically linked to the velocity structures present in Couette flows. Two different 2D symmetries can be recognized, which get stronger with the Reynolds number. These structures do not affect the mean flow or mean quantities as the Nusselt number. However, turbulent intensities and thermal fluxes depend on the width of the structures, mainly far from the walls. Since the width of the structures is related to the channel width, the statistics of thermal Couette flow are to some point box-dependent.This work was supported by the MINECO/FEDER, under project ENE2015-71333-R. The computations of the new simulations were made possible by a generous grant of computing time from the Barcelona Supercomputing Centre, reference FI-2018-1-0037. FAA is partially funded by GVA/FEDER project ACIF2018. We are very grateful for the advices and revision provided by one of the referees of the article, as it has helped to enrich its content.Alcántara-Ávila, F.; Gandía-Barberá, S.; Hoyas, S. (2019). Evidences of persisting thermal structures in Couette flows. International Journal of Heat and Fluid Flow. 76:287-295. https://doi.org/10.1016/j.ijheatfluidflow.2019.03.001S2872957

Letter: The link between the Reynolds shear stress and the large structures of turbulent Couette-Poiseuille flow

[EN] The length and width of the long and wide structures appearing in turbulent Couette flows are studied by means of a new dataset of direct numerical simulation covering a stepped transition from pure Couette flow to pure Poiseuille one, at Re-tau approximate to 130, based on the stationary wall. The existence of these structures is linked to the averaged Reynolds stress, (uv) over bar : as soon as in any part of the channel (uv) over bar changes its sign, the structures disappear. The length and width of the rolls are found to be, approximately, 50h and 2.5h, respectively. For this Reynolds number, simulations with a domain shorter than 100h cannot properly describe the behaviour of the longest structures of the flow.This work was supported by MINECO, under Project No. ENE2015-71333-R. The work of M. Oberlack was supported by the German Research Foundation (DFG) under the Grant No. OB96/39-1. The computations of the new simulations were made possible by a generous grant of computing time from the Supercomputing centre of the Universitat Politecnica de Valencia. We are grateful to Mr. Simon Hoyas for fruitful conversations about the paper.Gandía-Barberá, S.; Hoyas, S.; Oberlack, M.; Kraheberger, S. (2018). Letter: The link between the Reynolds shear stress and the large structures of turbulent Couette-Poiseuille flow. Physics of Fluids. 30(4):1-4. https://doi.org/10.1063/1.5028324S1430

Analysis of the feeding system in the injection process of peek in fixed partial dentures

[EN] In dental sector, PEEK is a new material used in the injection process of fixed partial dentures (FPD). The design of the feeding system is one of the most important stages in the injection process. This study simulates different locations of the feeding system in fixed partial dentures of PEEK, varying number of the injection points, using the software Moldflow. Variables used to compare simulations are the complete filling of the FPD mould cavity, the filling time, the minimum amount of rejected material of the feeding system, defects due to air traps, welding lines, etc. As results, depending on the geometric complexity, and the number and position of the injection points, it is possible to reduce the rejected material and to improve the filling time of the FPD.Gutiérrez, SC.; Meseguer, MD.; Gandía Barberá, A. (2015). Analysis of the feeding system in the injection process of peek in fixed partial dentures. Procedia Engineering. 132:1021-1028. doi:10.1016/j.proeng.2015.12.591S1021102813

Stratification effect on extreme-scale rolls in plane Couette flows

[EN] The existence of the large-scale structures appearing in turbulent Couette flows is studied by means of a direct numerical simulation data set of active thermal Couette flows for different friction Richardson numbers, at the Prandtl number of air. The existence of these structures is linked to the nonexistence of an active thermal flow. As soon as the Richardson number is greater than 1.5, the structures are less energetic, and for a value of only 3, the structures have vanished. This is due to the reorganization of the intense Reynolds stress events. Thus, large-scale structures will hardly appear in real-life Couette flows of air with a stable wall-normal gradient of temperature.This work was supported by Grant No. RTI2018-102256-B-I00 of MINECO/FEDER. The computations of the new simulations were made possible by a generous grant of computing time from the Barcelona Supercomputing Centre, Grant No. AECT-2020-2-0005. F.A.A. is partially funded by Generalitat Valenciana, GVA/FEDER project ACIF2018.Gandía-Barberá, S.; Alcántara-Ávila, F.; Hoyas, S.; Avsarkisov, V. (2021). Stratification effect on extreme-scale rolls in plane Couette flows. Physical Review Fluids. 6(3):1-18. https://doi.org/10.1103/PhysRevFluids.6.0346051186

Oligomerización de receptores acoplados a proteína G y enfermedad de Parkinson

La enfermedad de Parkinson es una condición neurodegenerativa del sistema nervioso central que puede aparecer en la madurez pero cuya incidencia aumenta dramáticamente en la tercera edad. Por este motivo, en las sociedades industrializadas, donde la esperanza de vida es alta, la enfermedad tiene un elevado coste socio-económico. El origen de la patología radica en la pérdida selectiva de neuronas dopaminérgicas de una región concreta de los ganglios basales. En consecuencia, se produce un desequilibrio neuroquímico (ej.; glutama to/dopamina/adenosina) que afecta en última instancia a los procesos controlados por los ganglios basales (ej.; el control motor, la cognición, las emociones y el aprendizaje). Recientemente, se ha demostrado que los receptores acoplados a proteína G pueden expresarse en la membrana plasmática como homodímeros y heterómeros. Estos complejos oligoméricos pueden funcionar como procesadores computacionales dinámicos, modulando la señalización celular y por tanto el flujo de información a través de los circuitos neuronales. Así, desde un punto de vista cuantitativo y/o cualitativo la señal generada por la estimulación de un receptor concreto del heterómero puede ser diferente de aquella obtenida mediante la coestimulación de los diferentes integrantes del complejo. Este nuevo concepto, además de exhortar la reinterpretación de la farmacodinámica clásica de receptores acoplados a proteína G, impulsará el diseño de nuevas terapias basadas en la combinación de fármacos cuya diana sean los oligómeros de receptores, por ejemplo, el oligómero formado por los receptores de glutamato, dopamina y adenosina en el tratamiento de la enfermedad de Parkinson

Postoperative endometrial cancer treatments with electronic brachytherapy source

Purpose This study is a dosimetric and acute toxicity comparison of endometrial cancer patients treated with either Axxent (Xoft, Inc., San José, CA, USA) electronic and interstitial brachytherapy versus interstitial high dose rate brachytherapy (HDRBT). Materials and Methods Between 2015 and 2017, 94 patients with postoperative endometrial cancer were treated in our centre with the Axxent electronic brachytherapy (eBT) system. The V 150 and V 200 are evaluated prospectively for each plan. The mean age of patients was 65.9 years (age range 33-84 years), with different tumour staging. Of the 94 patients, 37 received exclusive adjuvant brachytherapy (25 Gy in five sessions); the remaining patients received external beam radiotherapy (EBRT) with a regimen of 23 sessions of 2 Gy each to the entire pelvis, followed by eBT (15 Gy in three sessions). Additionally, the absorbed doses received by the organs at risk (OAR), urinary bladder, rectum and sigmoid colon were compared with HDRBT plans, evaluating D 2cc, V 50% and V 35%. Median follow-up was done for each of the 94 patients to assess the toxicity of the treatment: vaginal mucosa toxicity, rectal and urinary toxicity; and results are presented for acute toxicity, toxicity at 1 month after the end of treatment and follow-up after 12 months for a portion of patients according to the Radiation Therapy Oncology Group (RTOG) toxicity criteria. Results The doses in OAR for eBT plans were lower than that for HDRBT plans, both Ir-192 and Co-60 plans, whose doses were similar. The dose in bladder with eBT was 63.8% of the prescribed dose for D 2cc versus 70.1% for HDRBT Ir-192, for V 50% was 7.2% versus 12.7% and for V 35% was 15.2% versus 28.2%. In rectum the D 2cc was 61.2% versus 68.4%, for V 50% was 7.9% versus 14.3% and for V 35% was 16.7% versus 32%. Results demonstrated lower doses to OAR in all eBT plans. Acute toxicity in eBT was very low in cases of mucositis, with only one case of toxicity greater than grade 1, rectal toxicity and urinary toxicity; results at 1 month are equally good, toxicity symptoms disappeared and no relapses have occurred to date. Conclusions The results of treatment with the Axxent eBT unit for 94 patients are very good, as no recurrence has been observed and the toxicity of the treatment is very low. The increase in V 150 and V 200 has not produced an increase in vaginal mucosa toxicity, and the doses in the OAR are lower than in the plans implemented for HDRBT with Ir-192 or Co-60. eBT is a good alternative to treat endometrial cancer in centres without conventional HDR availability. To date, there are limited published studies reporting on outcomes from patients treated with eBT

A techno-economic and life cycle assessment for the production of green methanol from CO2: catalyst and process bottlenecks

The success of catalytic schemes for the large-scale valorization of CO2 does not only depend on the development of active, selective and stable catalytic materials but also on the overall process design. Here we present a multidisciplinary study (from catalyst to plant and techno-economic/lifecycle analysis) for the production of green methanol from renewable H2 and CO2. We combine an in-depth kinetic analysis of one of the most promising recently reported methanol-synthesis catalysts (InCo) with a thorough process simulation and techno-economic assessment. We then perform a life cycle assessment of the simulated process to gauge the real environmental impact of green methanol production from CO2. Our results indicate that up to 1.75 ton of CO2 can be abated per ton of produced methanol only if renewable energy is used to run the process, while the sensitivity analysis suggest that either rock-bottom H2 prices (1.5 $kg−1) or severe CO2 taxation (300$ per ton) are needed for a profitable methanol plant. Besides, we herein highlight and analyze some critical bottlenecks of the process. Especial attention has been paid to the contribution of H2 to the overall plant costs, CH4 trace formation, and purity and costs of raw gases. In addition to providing important information for policy makers and industrialists, directions for catalyst (and therefore process) improvements are outlined.The authors gratefully acknowledge financial support from the King Abdullah University of Science and Technology (KAUST). T. Cordero-Lanzac and A.T. Aguayo acknowledge the financial support received from the Spanish Ministry of Science and Innovation with some ERDF funds (CTQ2016-77812-R) and the Basque Government (IT1218-19). T. Cordero-Lanzac also acknowledges the Spanish Ministry of Education, Culture and Sport for the award of his FPU grant (FPU15-01666). A. Navajas and L.M. Gandía gratefully acknowledge the financial support from Spanish Ministerio de Ciencia, Innovación y Universidades, and the European Regional Development Fund (ERDF/FEDER) (grant RTI2018-096294-B-C31). L.M. Gandía also thanks Banco de Santander and Universidad Pública de Navarra for their financial support under ‘’Programa de Intensificación de la Investigación 2018’ initiative

Laser-Induced Crystallization of Sputtered Unhydrogenated Silicon at Low Temperatures

10-um-thick non-hydrogenated amorphous-silicon (a-Si) films were deposited at relatively high rates (_>10 Å/s) by radio-frequency magnetron sputtering (RFMS) on different large-area buffer-layer-coated glass substrates at deposition temperatures ranging from room temperature (RT) to 300oC. These amorphous samples were subsequently crystallized by means of a continuous-wave diode laser, looking for conditions to reach liquid-phase crystallization. The influence of deposition conditions on the quality of the final micro-crystalline silicon films has been studied

Preferential oxidation of CO (CO-PROX) over CuOx/CeO2 coated microchannel reactor

The general aspects of the synthesis and characterization results of a CuOx/CeO2 catalyst were presented. In addition the principal steps for manufacturing a microchannel reactor and for the coating of the CuOx/CeO2 catalyst onto the microchannels walls, were also summarized. The catalytic activity of this microchannel reactor during the preferential oxidation of CO (CO-PROX) was evaluated employing a feed-stream that simulates a reformate off-gas after the WGS unit. Two activation atmospheres were studied (H2/N2 and O2/N 2). The reducing pretreatment improved the resistance to deactivation by formation of carbonaceous species over the catalyst surface at high temperatures. The presence of H2O and CO2 in the feed-stream was also analyzed indicating that the adsorption of CO2 inhibited the conversion of CO at lower temperatures because these compounds modified the active sites through the formation of carbonaceous species on the catalyst surface. Finally, the experimental results of the microreactor performance were compared with CFD simulations that were carried out using a kinetic for the CuOx/CeO2 powder catalyst. The experimental results were reasonably well described by the model, thus confirming its validity.Peer Reviewe

N-benzylpiperidine derivatives as α7 nicotinic receptor antagonists

This document is the accepted manuscript version of a Published Work that appeared in final form in ACS Chemical Neuroscience 7.8, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see DOI: 10.1021/acschemneuro.6b00122.A series of multitarget directed propargylamines, as well as other differently susbstituted piperidines have been screened as potential modulators of neuronal nicotinic acetylcholine receptors (nAChRs). Most of them showed antagonist actions on α7 nAChRs. Especially, compounds 13, 26, and 38 displayed submicromolar IC50 values on homomeric α7 nAChRs, whereas they were less effective on heteromeric α3β4 and α4β2 nAChRs (up to 20-fold higher IC50 values in the case of 13). Antagonism was concentration dependent and noncompetitive, suggesting that these compounds behave as negative allosteric modulators of nAChRs. Upon the study of a series of less complex derivatives, the N-benzylpiperidine motif, common to these compounds, was found to be the main pharmacophoric group. Thus, 2-(1-benzylpiperidin-4-yl)-ethylamine (48) showed an inhibitory potency comparable to the one of the previous compounds and also a clear preference for α7 nAChRs. In a neuroblastoma cell line, representative compounds 13 and 48 also inhibited, in a concentration-dependent manner, cytosolic Ca2+ signals mediated by nAChRs. Finally, compounds 38 and 13 inhibited 5-HT3A serotonin receptors whereas they had no effect on α1 glycine receptors. Given the multifactorial nature of many pathologies in which nAChRs are involved, these piperidine antagonists could have a therapeutic potential in cases where cholinergic activity has to be negatively modulated.This work was supported by grants SAF2011-22802 to S.S., SAF2012-33304 to J.M.-C., CSD2008-00005 (the Spanish Ion Channel Initiative-CONSOLIDER INGENIO 2010) to M.C. from the Spanish Ministry of Science and Innovation (Ministerio de Economía y Competitividad)