Catalytic conversion of 5-hydroxymethylfurfural (5-HMF) over Pd-Ru/FAU zeolite catalysts.

We present this study on FAU-type zeolites were prepared varying the Si/Al ratio (4, 5 and 6) and crystallization time (4, 6 and 8 h) to produce a highly pure and homogeneous material with enhanced surface area values. Bimetallic Pd-Ru and Pt-Ru (0.5 wt.% of each metal) were impregnated onto the zeolites matrix by the incipient wetness impregnation method. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption, Fourier Transform Infrared spectroscopy (FT-IR), Scattering Electronic Microscopy (SEM), Scattering and Transmission Microscopy (STEM), temperature-programmed desorption (TPD), temperature-programmed desorption (TPR) and Inductively Couples Plasma- Mass Spectrometer (ICP-MS). Results indicated that using lower Si/Al ratios favored the catalytic activity. Also, the longest crystallization time had a positive effect on surface area, homogeneous particle size distribution and crystallinity. The catalytic performance in the esterification of 5-hydroxymethylfurfural (5-HMF) to produce 5-acetoxymethylfurfural (AcMF) was investigated. The maximum 5-HMF conversion of 87.28 % was achieved using pure zeolite with relation Si/Al = 5, and 8 h of crystallization. Pd-Ru supported onto same zeolite showed a conversion of 84.22 %. The highest selectivity towards AcMF of 71.29 % with pure zeolite Si/Al = 5 and 8 h of crystallization was achieved, followed by Pd-Ru/FAU with Si/Al = 5 and 8 h of crystallization, achieving 60.42 %. Finally, results shown that the interaction between the properties of zeolitic support and the metallic species, specifically Pd, had a positive effect in the catalytic process the pristine zeolite showed improved catalytic characteristics related to its acid strength

Desorption of furfural from bimetallic Pt-Fe oxides/alumina catalysts

In this work, the desorption of furfural, which is a competitive intermediate during the production of biofuel and valuable aromatic compounds, was studied using pure alumina, as well as alumina impregnated with iron and platinum oxides both individually and in combination, using thermogravimetric analysis (TGA). The bimetallic sample exhibited the lowest desorption percentage for furfural. High-resolution transmission electron microscopy (HRTEM) imaging revealed the intimate connection between the iron and platinum oxide species on the alumina support. The mechanism of furfural desorption from the Pt-Fe/Al2O3 0.5%-0.5% sample was determined using physisorbed furfural instead of chemisorbed furfural; this mechanism involved the oxidation of the C=O group on furfural by the catalyst. The oxide nanoparticles on γ-Al2O3 support helped to stabilize the furfural molecule on the surface

An 8-mm diameter fibre robot positioner for massive spectroscopy surveys

This article has been accepted for publication in Monthly Notices of Royal Astronomical Society © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reservedMassive spectroscopic survey are becoming trendy in astrophysics and cosmology, as they can address new fundamental knowledge such as understanding the formation of the Milky Way and probing the nature of the mysterious dark energy. To enable massive spectroscopic surveys, new technology has been developed to place thousands of optical fibres at a given position on a focal plane. This technology needs to be: (1) accurate, with micrometer positional accuracy; (2) fast to minimize overhead; (3) robust to minimize failure; and (4) low cost. In this paper, we present the development, properties, and performance of a new single 8-mm in diameter fibre positioner robot, using two 4-mm DC-brushless gearmotors, that allows us to achieve accuracies up to 0.07 arcsec (5 μm). This device has been developed in the context of the Dark Energy Spectroscopic InstrumentWe acknowledge support from the Spanish MICINNs Consolider-Ingenio 2010 Program me under grant MultiDark CSD2009-00064, HEPHACOS S2009/ESP-1473, and MINECO Centro de Excelencia Severo Ochoa Programme under grant SEV-2012-0249. We also thank the support from a CSIC-AVS contract through MICINN grant AYA2010-21231-C02- 01, and CDTI grant IDC-20101033; and support from the Spanish MINECO research grants AYA2012-31101 and FPA2012-34694. JPK, PH and LM acknowledge support from the ERC advanced grant LIDA and from an SNF Interdisciplinary grant

All-particle cosmic ray energy spectrum measured by the HAWC experiment from 10 to 500 TeV

We report on the measurement of the all-particle cosmic ray energy spectrum with the High Altitude Water Cherenkov (HAWC) Observatory in the energy range 10 to 500 TeV. HAWC is a ground based air-shower array deployed on the slopes of Volcan Sierra Negra in the state of Puebla, Mexico, and is sensitive to gamma rays and cosmic rays at TeV energies. The data used in this work were taken from 234 days between June 2016 to February 2017. The primary cosmic-ray energy is determined with a maximum likelihood approach using the particle density as a function of distance to the shower core. Introducing quality cuts to isolate events with shower cores landing on the array, the reconstructed energy distribution is unfolded iteratively. The measured all-particle spectrum is consistent with a broken power law with an index of $-2.49\pm0.01$ prior to a break at $(45.7\pm0.1$) TeV, followed by an index of $-2.71\pm0.01$. The spectrum also respresents a single measurement that spans the energy range between direct detection and ground based experiments. As a verification of the detector response, the energy scale and angular resolution are validated by observation of the cosmic ray Moon shadow's dependence on energy.Comment: 16 pages, 11 figures, 4 tables, submission to Physical Review

Sistema de enfoque basado en dos espejos elípticos y un espejo plano rotatorio para un radar a 300 GHz

A focusing system for a 300 GHz radar with two target distances (5m and 10m) is proposed, having 1cm resolution in both cases. The focusing system is based on a gaussian telescope scheme and it has been designed using gaussian beam quasi-optical propagation theory with a homemade Matlab analysis tool. It has been translated into a real focusing system based on two elliptical mirrors and a plane mirror in order to have scanning capabilities and validated using the commercial antenna software GRAS

Constraining the pˉ/p\bar{p}/p Ratio in TeV Cosmic Rays with Observations of the Moon Shadow by HAWC

An indirect measurement of the antiproton flux in cosmic rays is possible as the particles undergo deflection by the geomagnetic field. This effect can be measured by studying the deficit in the flux, or shadow, created by the Moon as it absorbs cosmic rays that are headed towards the Earth. The shadow is displaced from the actual position of the Moon due to geomagnetic deflection, which is a function of the energy and charge of the cosmic rays. The displacement provides a natural tool for momentum/charge discrimination that can be used to study the composition of cosmic rays. Using 33 months of data comprising more than 80 billion cosmic rays measured by the High Altitude Water Cherenkov (HAWC) observatory, we have analyzed the Moon shadow to search for TeV antiprotons in cosmic rays. We present our first upper limits on the $\bar{p}/p$ fraction, which in the absence of any direct measurements, provide the tightest available constraints of $\sim1\%$ on the antiproton fraction for energies between 1 and 10 TeV.Comment: 10 pages, 5 figures. Accepted by Physical Review

Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

The unexpectedly high flux of cosmic ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the HighAltitude Water Cherenkov Observatory (HAWC), of extended tera-electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera-electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.Comment: 16 pages (including supplementary material), 5 figure

Emotional intelligence in students in the 1st and 5th semesters of a nursing degree.

Introducción. La inteligencia emocional [IE], se relaciona con el éxito académico y quienes la poseen tienen reacciones favorables al control de las emociones, y son conscientes de como éstas pueden afectarles (Quiliano & Quiliano, 2020). Es deseable que los estudiantes de ciencias de la salud aprendan a manejar sus emociones, por las repercusiones durante la interacción con las personas de su entorno personal y laboral (Liébana-Presa, 2017).  Objetivo general: Analizar las diferencias de las dimensiones de Inteligencia emocional, en estudiantes de 1ero y 5to semestres por cada variable sociodemográfica. Metodología: Estudio descriptivo-transversal comparativo, la muestra 175 estudiantes. Instrumento: Autopercepción de inteligencia emocional (Treit Meta-Mood Scale) de Fernández-Berrocal et al. (2004). Se utilizó Shapiro-Wilks y U de Mann-Whitney y Kruskal-Wallis, y la prueba de Ji cuadrada para determinar asociación de la IE. Resultados: Se identificaron diferencias en las dimensiones de inteligencia emocional y los datos sociodemográficos. Conclusiones: Los estudiantes de primer semestre presentan, mayor desarrollo en las dimensiones de atención, claridad y reparación emocional, comparativamente con los estudiantes de quinto semestre.Introduction. Emotional intelligence [EI] is related to academic success and those who possess it have favorable reactions to the control of emotions, and are aware of how these can affect them (Quiliano & Quiliano, 2020). It is desirable that health sciences students learn to manage their emotions, due to the repercussions during interaction with people in their personal and work environment (Liébana-Presa, 2017). General objective: Analyze the differences in the dimensions of emotional intelligence in 1st and 5th semester students for each sociodemographic variable. Methodology: Comparative descriptive-cross-sectional study, sample 175 students. Instrument: Self-perception of emotional intelligence (Treit Meta-Mood Scale) by Fernández-Berrocal et al. (2004). Shapiro-Wilks and Mann-Whitney U and Kruskal-Wallis, and the Chi-square test were used to determine the association of EI. Results: Differences were identified in the dimensions of emotional intelligence and sociodemographic data. Conclusions: First semester students present greater development in the dimensions of attention, clarity and emotional repair, compared to fifth semester students