Electrochemical Reduction of CO2: Influence of Pre-treating the Carbon Support

The production of useful chemicals by electroreducing CO2 it is a promising approach to reduce the levels of this greenhouse gas in the atmosphere. This is not a straightforward process due to the high stability of the CO2 molecule and low selectivity however, these barriers can be overcome by using an appropriate catalyst. This research focus on the effect of pre-treating the carbon supports before incorporating the catalyst on the electroreduction of CO2. We found that the electrochemical behaviour of the carbon supports is modified by the nature of the pre-treatment used. From the structure perspective, the results showed partial destruction of the carbon structure mainly after the oxidative treatments nevertheless, the introduction of defect sites in the carbon structure contributed to catalyst performance. This improvement was proved by the LSV data that showed the reduction of the current associated with the hydrogen reduction reaction

H - T phase diagram of YbCo2Si2 with H // [100]

We report on the first high-resolution dc-magnetisation ($M$) measurements on a single crystal of \ycs. $M$ was measured down to 0.05 K and in fields up to 12 T, with the magnetic field $H$ parallel to the crystallographic direction [100]. Two antiferromagnetic (AFM) phase transitions have been detected in a field $\mu_{0}H = 0.1$ T at $T_{N} = 1.75$ K and $T_{L} = 0.9$ K, in form of a sharp cusp and a sudden drop in $\chi = M/H$, respectively. These signatures suggest that the phase transitions are $2^{nd}$ order at $T_{N}$ and $1^{st}$ order at $T_{L}$. The upper transition is suppressed by a critical field $\mu_{0}H_{N} = 1.9$ T. The field-dependent magnetisation shows two hysteretic metamagnetic-like steps at the lowest temperature, followed by a sharp kink, which separates the AFM region from the paramagnetic one. The magnetic $H - T$ phase diagram of \ycs has been deduced from the isothermal and isofield curves. Four AFM regions were identified which are separated by $1^{st}$ and $2^{nd}$ order phase-transition lines.Comment: 5 Pages, 3 figure

Propiedades acústicas de los paneles de carrizo

Reed is a plant species very similar to common cane which is widespread all over the Earth. It is an ecological and sustainable material which is low-cost, aesthetically attractive, easy to obtain and install, and can be used in different construction systems.
 
 This work analyses the acoustic properties of reed panels from the point of view of sound absorption and sound insulation against airborne noise, according to the corresponding EN ISO standards. The experimental results obtained point to the conclusion that reed panels are suitable construction systems for controlling reverberant sound within a space, and that the sound reduction index values for different thicknesses of reed panels, or reed panels used in combination with wood particle boards, demonstrate the possibility of using them in construction as an element on the facades and roofs of buildings and for interior partitions.<br><br>El carrizo es una especie vegetal, parecida a la caña común, que se encuentra ampliamente distribuida en la superficie terrestre. Es un material ecológico y sostenible de bajo coste, estéticamente aceptable, fácil de obtener y colocar, que permite generar diferentes sistemas constructivos.
 
 En este trabajo se analizan las propiedades acústicas de los paneles de carrizo en lo referente a la absorción acústica y al aislamiento acústico a ruido aéreo, para ello se han aplicado los procedimientos de las normas EN ISO correspondientes. De los resultados experimentales obtenidos se concluye que los paneles de carrizo son unos sistemas constructivos adecuados para el control del sonido reverberante en un recinto y que los valores del índice de reducción acústica de paneles de diferentes espesores o en combinación con tableros de partículas de madera muestran la posibilidad de utilizarlos en la edificación como elemento de fachada, en cubiertas de edificios y particiones interiores

El trabajo doméstico no remunerado en México. Una estimación de su valor económico a través de la Encuesta Nacional sobre Uso del Tiempo 2002

Presentación El trabajo no remunerado como elemento importante en la economía El trabajo doméstico según el perfil sociodemográfico de la población Anexo Bibliografí

Numerical model of the inhomogeneous scattering by the human lens

We present in this work a numerical model for characterizing the scattering properties of the human lens. After analyzing the scattering properties of two main scattering particles actually described in the literature through FEM (finite element method) simulations, we have modified a Monte Carlo''s bulk scattering algorithm for computing ray scattering in non-sequential ray tracing. We have implemented this ray scattering algorithm in a layered model of the human lens in order to calculate the scattering properties of the whole lens. We have tested our algorithm by simulating the classic experiment carried out by Van der Berg et al for measuring "in vitro" the angular distribution of forward scattered light by the human lens. The results show the ability of our model to simulate accurately the scattering properties of the human lens. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

Youth screening depression: Validation of the Patient Health Questionnaire-9 (PHQ-9) in a representative sample of adolescents

BACKGROUND: Depression symptoms and mood disorders constitute one of the major public health challenges among youths. Thus, early prevention and intervention for depression should be a priority. The main goal of the present study was to validate the Patient Health Questionnaire-9 (PHQ-9) scores in a school-based sample of non-clinical adolescents. METHOD: Stratified random sampling was conducted. Participants were 2235 students (M = 14.49, SD =1.76, range= 12–18 years), 52.9 % were female, from 34 secondary schools in Spain. Several previously validated self-reported questionnaires of mental health and psychopathology were administrated. RESULTS: The unidimensional factorial model of the PHQ-9 items showed adequate goodness of fit indices. Strong measurement invariance across gender was found. Omega for the PHQ-9 total score was 0.87. The PHQ-9 total score was positively associated with anxiety symptoms and emotional and behavioral problems, and negatively associated with prosocial behavior and quality of life. CONCLUSIONS: The PHQ-9 is a brief, easy, and reliable tool for assessing self-reported depressive symptoms in both clinical and school settings. PHQ-9 may be used as a screening tool for universal early detection and monitorization of depression symptoms during adolescence

Low temperature thermodynamic properties near the field-induced quantum critical point in DTN

We present a comprehensive experimental and theoretical investigation of the thermodynamic properties: specific heat, magnetization and thermal expansion in the vicinity of the field-induced quantum critical point (QCP) around the lower critical field $H_{c1} \approx 2$\,T in DTN . A $T^{3/2}$ behavior in the specific heat and magnetization is observed at very low temperatures at $H=H_{c1}$ that is consistent with the universality class of Bose-Einstein condensation of magnons. The temperature dependence of the thermal expansion coefficient at $H_{c1}$ shows minor deviations from the expected $T^{1/2}$ behavior. Our experimental study is complemented by analytical calculations and Quantum Monte Carlo simulations, which reproduce nicely the measured quantities. We analyze the thermal and the magnetic Gr\"{u}neisen parameters that are ideal quantities to identify QCPs. Both parameters diverge at $H_{c1}$ with the expected $T^{-1}$ power law. By using the Ehrenfest relations at the second order phase transition, we are able to estimate the pressure dependencies of the characteristic temperature and field scales.Comment: 11 paged, 10 figures, submitted to PR

Absorción acústica de espumas de aluminio

The article discusses normal incidence sound absorption by aluminium foam manufactured with powder metallurgy technology. Aluminium foams with different surface morphologies were obtained by varying the type of precursor and adding filler materials during the foaming process. The sound absorption coefficients found for these aluminium foams were compared to the coefficient for commercial foams marketed under the name ALPORAS. The effect of foam thickness on the absorption coefficient was studied for each sample prepared. The combination of good acoustic and mechanical properties makes aluminium foams particularly attractive products. The study included an analysis of the effect of 2-, 5- and 10-cm air gaps on the sound absorption coefficient. The results showed that such gaps, which are routinely used in construction to reduce the reverberation period in indoor premises, raised the low frequency absorption coefficient significantly. This increase was found to depend on aluminium foam density and thickness and the depth of the air gap. In this same line, we have investigated the absorption coefficient of the aluminium foams combined with a mineral fiber panel.Se presenta un estudio del coeficiente de absorción acústica a incidencia normal de espumas de aluminio fabricadas mediante la técnica pulvimetalúrgica. Se fabricaron espumas de aluminio de distinta morfología superficial variando el tipo de precursor y usando materiales de relleno durante el proceso de espumación. Se muestra un estudio comparativo del coeficiente de absorción acústica de las espumas de aluminio fabricadas y las espumas comerciales conocidas como ALPORAS. Para cada muestra fabricada se estudió la influencia del espesor sobre el valor del coeficiente de absorción.El atractivo de las espumas de aluminio radica en que en ellas se combinan interesantes propiedades acústicas y mecánicas. Se analizó el efecto de una cámara de aire de 2, 5 y 10 cm de anchura sobre el coeficiente de absorción acústica, solución constructiva habitual para reducir el tiempo de reverberación en un recinto. Los resultados muestran que se consigue un aumento significativo del valor del coeficiente de absorción a bajas frecuencias. Este aumento depende de la densidad y espesor de la espuma de aluminio y de la anchura de la cámara de aire. En esta misma línea, y dado el uso habitual de lanas minerales como absorbentes acústicos también se investigó el coeficiente de absorción a incidencia normal de la espuma de aluminio con una lana mineral

Dimensiones factoriales del cuestionario de Millon (MCMI-II) en adictos a sustancias.

El Inventario Clinico Multiaxial de Millon (MCMI-II) es un cuestionario ampliamente utilizado en la clínica, especialmente en drogodependencias, para la evaluación de la personalidad. El objetivo del presente estudio es conocer la estructura factorial subyacente del MCMI-II en una muestra de 1.106 adictos a sustancias psicoactivas que inician tratamiento. Los participantes cumplimentaron el MCMI-II y el TCI-R. Se realizó análisis factorial exploratorio multivariado. Los resultados muestran que en el MCMI-II hay un factor principal que evalúa sintomatología de aparición reciente relacionada con el Eje I, una escala de ideación autolítica, dos escalas que exploran problemas relacionados con alcohol y otras drogas, dos de rasgos de personalidad normal y siete de rasgos de personalidad disfuncional. Aunque el objetivo del MCMI-II es evaluar la personalidad, los resultados indican que la mayor parte del mismo evalúa condiciones no necesariamente estables que han aparecido recientemente. Las escalas que miden rasgos disfuncionales de personalidad se combinan entre sí para configurar los trastornos, sin ajuste claro a la teoría de referencia. Se concluye que el uso del MCMI-II con fines diagnósticos debe considerar la presencia de condiciones inestables que pueden incrementar artefactualmente las cifras de prevalencia y de coexistencia de trastornos de personalidad y comportamientos adictivos. Factorial dimensions of the Millon’s MCMI-II in substance addicts. The Millon Clinical Multiaxial Inventory II is a widely used questionnaire for the assessment of personality in clinical settings, especially in addictive behaviors. The aim of this study is to determine the underlying factorial structure of the MCMI-II in a sample of 1,106 drug-dependents who seek treatment. All participants completed the MCMI-II and the TCI-R. Multivariate exploratory factor analysis was performed. The results show that, in the MCMI-II, there is a main part that assesses symptoms of recent onset associated with the Axis I disorders, a scale that explores autolytic ideation, two scales that explore issues related to the use of alcohol and other drugs, two scales that assess normal personality traits, and seven scales that explore dysfunctional personality traits. Although the objective of the MCMI-II is the assessment of personality, the results indicate that the largest part of the questionnaire assesses not necessarily stable conditions and which have appeared recently. The scales measuring dysfunctional personality traits are combined to account for disorders without a clear match to the theory of reference. We conclude that, when using the MCMI-II with diagnostic purposes, one should consider the presence of unstable conditions that could artifactually increase the prevalence rates and the coexistence of personality disorders and addictive behaviors

Dynamic Structure and Subsurface Oxygen Formation of a Working Copper Catalyst under Methanol Steam Reforming Conditions: An in Situ Time-Resolved Spectroscopic Study

"This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Catalysis, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acscatal.8b05042."[EN] The dynamic behavior of a CuO/ZnO/Ga2O3 catalyst under methanol steam reforming (MSR) reaction conditions promoted by a high dispersion of the copper nanoparticles and defect sites of a nonstoichiometric ZnGa2O4 spinel phase has been observed, where structural changes taking place in the initial state of the reaction determine the final state of the catalyst in stationary reaction conditions. Mass spectrometry (MS) studies under transient conditions coupled to X-ray photoelectron spectroscopy (XPS) have shown copper oxidation to Cu+ in the initial state of the reaction (TOS = 4 min), followed by a fast reduction of the outer shell to Cu-0, while keeping dissolved oxygen species in the inner layers of the nanoparticle. The presence of this subsurface oxygen impairs a positive charge to the uppermost surface copper species, that is, Cu delta+, which undoubtedly plays an important role on the MSR catalytic activity. The detection of these features, unperceived by conventional spectroscopic and catalytic studies, has only been possible by combining synchrotron NAP-XPS studies with transient studies performed in a low volume catalytic reactor connected to MS and linked with Raman and laboratory scale XPS studies.The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under Grant Agreement No. [303476]. Part of this work was financially supported by the following projects: (i) Project POCI-01-0145-FEDER-006939 (Laboratory for Process Engineering, Environment, Biotechnology and Energy UID/EQU/00511/2013) funded by the European Regional Development Fund (ERDF), through COMPETE2020 - Programa Operacional Competitividade e Internacionalizacao (POCI) and by national funds, through FCT - Fundacao para a Ciencia e a Tecnologia; (ii) NORTE-01-0145-FEDER-000005 - LEPABE-2-ECO-INNOVATION, supported by North Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF); and (iii) the Spanish Government-MINECO through "Severo Ochoa" Excellence Programme (SEV-2016-0683). D.R. thanks European Research Council project SYNCATMATCH (671093). J.C. thanks the Spanish Government (MINECO) for a "Severo Ochoa" grant (BES-2015-075748). The NAP-XPS experiments were performed at the NAPP branch of the CIRCE beamline at the ALBA Synchrotron with the collaboration of ALBA staff.Ruano-Sánchez, D.; Cored-Bandrés, J.; Azenha, C.; Pérez-Dieste, V.; Mendes, A.; Mateos-Pedrero, C.; Concepción Heydorn, P. (2019). Dynamic Structure and Subsurface Oxygen Formation of a Working Copper Catalyst under Methanol Steam Reforming Conditions: An in Situ Time-Resolved Spectroscopic Study. ACS Catalysis. 9(4):2922-2930. https://doi.org/10.1021/acscatal.8b05042S292229309