Single wall carbon nanotubes loaded with Pd and NiPd nanoparticles for H2 sensing at room temperature

Pd and bimetallic Ni50Pd50 nanoparticles protected by polyvinylpyrrolidone (PVP) have been synthesized by the reduction-by-solvent method and deposited on single wall carbon nanotubes (SWCNTs) to be tested as H2 sensors. The SWCNTs were deposited by drop casting from different suspensions. The Pd nanoparticles-based sensors show a very reproducible performance with good sensitivity and very low response times (few seconds) for different H2 concentrations, ranging from 0.2% to 5% vol. H2 in air at atmospheric pressure. The influence of the metal nanoparticle composition, the quality of SWCNTs suspension and the metal loading have been studied, observing that all these parameters play an important role in the H2 sensor performance. Evidence for water formation during the H2 detection on Pd nanoparticles has been found, and its repercussion on the behaviour of the assembled sensors is discussed. The sensor preparation procedure detailed in this work has proven to be simple and reproducible to prepare cost-effective and highly efficient H2 sensors that perform very well under real application conditions.We thank the MINECO, Generalitat Valenciana and FEDER (Projects CTQ2012-31762 and PROMETEO/2009/047) for financial support. A.B.M. thanks the Spanish Ministry Science and Innovation for a Ramón y Cajal fellowship (RyC 2009-03913). Jaime Garcia Aguilar and Izaskun Miguel García also thank the University of Alicante for their fellowships

Capillary microreactors based on hierarchical SiO2 monoliths incorporating noble metal nanoparticles for the Preferential Oxidation of CO

Novel hierarchical SiO2 monolithic microreactors loaded with either Pd or Pt nanoparticles have been prepared in fused silica capillaries and tested in the Preferential Oxidation of CO (PrOx) reaction. Pd and Pt nanoparticles were prepared by the reduction by solvent method and the support used was a mesoporous SiO2 monolith prepared by a well-established sol–gel methodology. Comparison of the activity with an equivalent powder catalyst indicated that the microreactors show an enhanced catalytic behavior (both in terms of CO conversion and selectivity) due to the superior mass and heat transfer processes that take place inside the microchannel. TOF values at low CO conversions have been found to be ∼2.5 times higher in the microreactors than in the powder catalyst and the residence time seems to have a noticeable influence over the selectivity of the catalysts designed for this reaction. The Pd and Pt flexible microreactors developed in this work have proven to be effective for the CO oxidation reaction both in the presence and absence of H2, standing out as a very interesting and suitable option for the development of CO purification systems of small dimensions for portable and on-board applications.This research was supported financially by MINECO, Generalitat Valenciana and FEDER (Projects CTQ2012-31762 and PROMETEOII/2014/010). J.G.A. and A.B.M. thank the Spanish Ministry of Economy and Competitiveness (MINECO) for their fellowships (BES-2013-063678 and RyC 2009-03913, respectively). I.M.G. and M.N.G. also thank the University of Alicante for their PhD fellowships

Enhanced ammonia-borane decomposition by synergistic catalysis using CoPd nanoparticles supported on titano-silicates

Pd and CoxPd1−x nanoparticles (NPs), synthesized using the reduction by solvent method, were loaded on SiO2 and Ti–SiO2 supports. The resulting catalysts were tested in the ammonia-borane decomposition reaction under dark and UV-vis conditions. The synergistic promotion by Co (in the NPs) and Ti (in the support), combined with the UV-vis light irradiation, enhanced the catalytic activity showing very promising TOFs values for this kind of catalysis, from 1.53 to 49.5 mol H2 per mol Pd per min.We thank the Spanish Ministry of Economy and Competitiveness (MINECO), Generalitat Valenciana and FEDER (Projects CTQ2015-66080-R MINECO/FEDER and PROMETEOII/2014/010) for financial support. J. G. A. thanks the MINECO for his fellowship (BES-2013-063678), with special thanks for the mobility grant of MINECO (EEBB-I-15-10219) at Osaka University

Análisis del programa de restitución de tierras frente al estado de cosas inconstitucional declarado por la Corte Constitucional mediante Sentencia T-025 de 2004

La presente tesis tiene como objetivo principal realizar una descripción sobre el fenómeno de desplazamiento forzado en Colombia, así como de los avances que el Estado ha implementado en la política de prevención y atención de la población afectada por este fenómeno, en especial de los mecanismos de reparación establecidos para lograr el restablecimiento de derechos a través de la restitución de tierras. El Trabajo inicia por determinar las causas que originaron el desplazamiento forzado en Colombia hasta el año 2004, así como el análisis de los instrumentos institucionales, legales y presupuestales con los que contaba el Estado hasta este año para frenar el desplazamiento forzado por la violencia y revertir el proceso mediante la restitución de tierras. Posteriormente procede a realizar un estudio de las causas y fallas de los instrumentos con los que contaba el Estado para atender esta política y los motivos que llevaron a la Corte Constitucional para declarar el Estado de Cosas Inconstitucional mediante la sentencia T-025 de 2004. Finalmente se determina la suficiencia y adecuación de los instrumentos legales, institucionales y presupuestales que el Estado adopta para superar el Estado de Cosas Inconstitucional para concluir si estas medidas han cumplido con los objetivos propuestos.The main objective of this thesis is to describe the forced displacement in Colombia and how the Colombian state has implemented a prevention policy to all the affected population by giving them restitution of lands. This present document begins with the causes that originated forced displacement throughout the years up until 2004, then is analyses the state`s main policies to prevent this phenomena. I later tend to determine wether this state`s policies are worth to implement and how the country`s constitutional court gave sentence T025 2004. Finally legal and institutional suficiency and adequacy are determined in order for the state to determine if this state`s measurements have fulfilled the expectations.Magíster en Derecho EconómicoMaestrí

Acute caffeine supplementation enhances several aspects of shot put performance in trained athletes.

The aim of this investigation was to determine the effect of a moderate dose of caffeine (3 mg/kg/b.m.) on muscular power and strength and shot put performance in trained athletes. Methods. Thirteen shot putters (eight men and five women) participated in a double-blind, placebo-controlled, randomized experiment. In two different trials, participants ingested either 3 mg/kg/b.m. of caffeine or a placebo. Forty-five min after substance ingestion, athletes performed a handgrip dynamometry test, a countermovement jump (CMJ), a squat jump (SJ), and a maximum-velocity push-up. The athletes also performed three types of throws: a backwards throw, a standing shot put and a complete shot put. Results. In comparison with the placebo, caffeine ingestion increased CMJ height (32.25 ± 7.26 vs. 33.83 ± 7.72 cm, respectively; effect size (ES) = 0.82, p = 0.012; +5.0%;) and SJ height (29.93 ± 7.88 vs. 31.40 ± 7.16 cm; ES = 0.63, p = 0.042; +6.4%) and distance in the standing shot put (10.27 ± 1.77 m vs. 10.55 ± 1.94 m; ES = 0.87, p = 0.009; +2.6%). However, caffeine ingestion did not increase strength in the handgrip test, power in the ballistic push-up, or distance in the backwards throw (all p > 0.05). Shot put performance changed from 11.24 ± 2.54 to 11.35 ± . 2.57 m (ES = 0.33, p = 0.26; +1.0%), although the difference did not reach statistically significant differences. Caffeine ingestion did not increase the prevalence of side effects (nervousness, gastrointestinal problems, activeness, irritability, muscular pain, headache, and diuresis) in comparison with the placebo (p > 0.05). Conclusion. In summary, caffeine ingestion with a dose equivalent to 3 mg/kg/b.m. elicited moderate improvements in several aspects of physical performance in trained shot putters but with a small effect on distance in a complete shot put.post-print838 K

K- and Ca-promoted ferrosilicates for the gas-phase epoxidation of propylene with O2

In the propylene epoxidation reaction with Fe-SiO2 catalysts the presence of iron oxide particles has a detrimental effect due to the total combustion of propylene on these iron species. Thus, the complete elimination of the iron oxide particles is presented as a preliminary strategy in order to increase the selectivity towards propylene oxide in iron-based catalysts. In this sense, a simple post-treatment of the catalysts with alkali or alkaline-earth elements (such as K or Ca, respectively) has proven effective in the total elimination of these iron oxide particles. Furthermore, the addition of K and Ca has modified the physico-chemical properties of the catalysts, decreasing their superficial acidity and (for higher K or Ca loadings) masking/blocking the active sites responsible for the catalytic reaction. With all this, it is shown that K has a higher efficiency removing the iron oxide particles compared with Ca (for the same molar ratios) and that a higher amount of K (compared to Fe) is required for the complete elimination of the iron oxide particles. A considerable propylene oxide selectivity enhancement (up to 65%) has been obtained for the K-promoted Fe0.005SiO2 and Fe0.01SiO2 catalysts using O2 as sole oxidant.We thank the Spanish Ministry of Economy and Competitiveness (MINECO), Generalitat Valenciana and FEDER (CTQ2015-66080-R MINECO/FEDER and PROMETEOII/2014/010) for financial support. J.G.A. thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for his fellowship (BES-2013-063678)

One step-synthesis of highly dispersed iron species into silica for propylene epoxidation with dioxygen

Well dispersed iron catalysts were synthesized in silica (Fe0.0XSiO2) by a one-step synthesis procedure. These materials were tested in the propylene epoxidation reaction with gaseous O2. The influence of the iron metal loading on the iron incorporation and distribution in the support (both influenced by the synthetic procedure) were thoroughly studied (conversion, generation and selectivity). Electron Microscopy and UltraViolet–Visible (UV–VIS), Raman and Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy techniques were used to analyze the iron distribution in the catalysts and to probe its incorporation into the silica framework. In situ FTIR was also used to analyze the interaction between propylene and iron-based catalysts. Computational calculations considering a single-site iron catalyst incorporated into the silica structure show a possible interaction between O2 and the incorporated iron atom and the olefin bond and the acidic proton neighboring the iron species which favor the reaction between the two molecules near the iron atom.We thank the MINECO, Generalitat Valenciana and FEDER (Projects CTQ2012-31762, CTQ2015-66080-R and PROMETEOII/2014/010) for financial support. A.B.M. and J.G.A. thank the Spanish Ministry of Economy and Competitiveness (MINECO) for their fellowships (RyC 2009-03913 and BES-2013-063678, respectively)

Structural and textural features of TiO2/SAPO-34 nanocomposite prepared by the sol–gel method

This paper focuses on the synthesis of nanocomposite materials, TiO2/SAPO-34, using the sol–gel method, which involves preparing a mixture between as-synthesized or calcined SAPO-34 zeolite and TiO2 gel under hydrothermal crystallization and then calcining it at 400 °C for the formation of the TiO2 anatase phase. The structural and textural features of the obtained materials were determined by various physico-chemical techniques such as thermogravimetric analysis, X-ray diffraction, scanning electronic microscopy, nitrogen sorption at 77 K, energy dispersive X-ray analysis and ultraviolet–visible spectrometry. The DRX results showed that calcination at 400 °C of the mixture between the calcined SAPO-34 and TiO2 gel led to the collapse of the original framework of zeolite, but formed the anatase TiO2 in a nano-spherical morphology; however, the use of as-synthesized SAPO-34 supports provides a mixture phase between SAPO-34 and TiO2 anatase after calcination. The photocatalytic properties of the SAPO-34/TiO2 and TiO2-type materials were tested for the removal of methylene blue (MB) dye. The MB degradation proved to increase as a function of contact time, catalyst mass and the initial concentration of MB.The authors thank Generalitat Valenciana (PROMETEOII/2014/010) for financial support

Consideration of the non-linear behavior materials in the structural analysis of the church of Santa Ana in Sevilla by finit elements method

The purpose of this paper is to bring the numerical models' structural behavior closer to the real behavior of the Church of Santa Ana in Seville, in Triana, through the development of high-definition geometric models that incorporate the non-linear materials' behavior. This church is presented as a unique case study due to the geometric complexity of its vaults and the influence on the structural behavior of the constructive solution of its passable roof. A geometrical model has been developed “as i”t, adapting the various constructive solutions to the real building. The result is a ”high definition geometrical model”. To define the materials a dynamic identification campaign has been carried out using OMA (Operational Modal Analysis) that has allowed us to adjust the mechanical properties of these materials in the numerical models. Modal shapes and frequencies of vibration similar to those obtained in the environmental vibration campaign has been obtained. A first linear analysis give us an approximation and a magnitude order of the displacement levels and the stress state, and let us to locate areas that exceed the admissible level stresses of the defined materials. With these results and analyzing in situ the displacement levels using photogrammetry, we decide to implement in the numerical analysis a constitutive model that contemplates the nonlinear behavior of these materials with Concrete Damage Plasticity model in Abaqus Cae. A non-linear analysis has been performed increasin the gravity factor until the structural collapse to determinate the structural safety factor

La fauna nativa de México en riesgo y la NOM-059: ¿Están todos los que son y son todos los que están?

The Norma Oficial Mexicana 059 (NOM-059) is the Mexican legal instrument that identifies species or populations at risk throug the use of the Método de Evaluación de Riesgo de Extinción de Especies Silvestres de México (MER). From its first promulgation in 1994, the NOM-059 has been used as a reference to assess the conservation status, and as a tool on national environmental policies; however, it has been questioned for the lack of scientific criteria. We assess the relevance of the NOM-059 as a tool to assess the conservation status of Mexican native species by utilizing the mammals as a case study. More than 40% of native mammals are included in the list, though only 10% of the listed species had been evaluated with the MER, and have technical support to justify their inclusion. In most cases, criteria used to determine the species inclusion are unknown, in the other cases the criteria are contradictory with the objectives and methods stablished in the NOM-059. Non-endemic mammals are overrepresented in the list, while the extinction risk of the endemic mammals is underestimated.The evidence shows that in its current form the NOM-059 it is not an adequate tool to assess the species conservation status. Finally, we list a series of recommendations that would improve NOM-059 and strengthen conservation efforts in Mexico. Resumen. La Norma Oficial Mexicana 059 (NOM-059) es el instrumento normativo que identifica las especies o poblaciones de México en riesgo mediante la aplicación del Método de Evaluación de Riesgo de Extinción de Especies Silvestres de México (MER). Desde su primera publicación en 1994 la Norma ha sido usada como referencia para evaluar el estado de conservación y como herramienta en las políticas ambientales nacionales; sin embargo, ha sido fuertemente cuestionada por la aparente falta de criterios científicos. El objetivo de este trabajo fue evaluar la pertinencia del uso de la NOM-059 como referencia del estado de conservación de las especies nativas de México utilizando a los mamíferos como caso de estudio. Más del 40% de los mamíferos nativos de México están incluidos, pero solo el 10% del total de especies listadas se han evaluado con el MER; solo estas especies cuentan con soporte técnico que justifique su inclusión. En la mayoría de los casos los criterios empleados para determinar la inclusión se desconocen, pero en algunos casos son incluso contradictorios a los objetivos y metodología establecidos en la misma Norma. Los resultados sugieren que los mamíferos no endémicos están sobrerrepresentados en la NOM-059, mientras que el riesgo de extinción de los mamíferos endémicos está subestimado. La evidencia pone de manifiesto que en su forma actual la NOM-059 no es la herramienta adecuada para evaluar el estado de conservación. Finalmente, presentamos una serie de  recomendaciones que consideramos contribuyen a mejorar la NOM-059 y así fortalecer los esfuerzos de conservación del país.