1,952 research outputs found

    The LIL for UU-statistics in Hilbert spaces

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    We give necessary and sufficient conditions for the (bounded) law of the iterated logarithm for UU-statistics in Hilbert spaces. As a tool we also develop moment and tail estimates for canonical Hilbert-space valued UU-statistics of arbitrary order, which are of independent interest

    Contour Temperature Programmed Desorption for Monitoring Multiple Chemical Reaction Products

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    A simple method for obtaining a comprehensive overview of major compounds desorbing from the surface during temperature programmed desorption (TPD) experiments is outlined. Standard commercially available equipment is used to perform the experiment. The method is particularly valuable when high molecular mass compounds are being studied. The acquisition of contour temperature programmed desorption (CTPD) spectra, sampling 50-dalton mass ranges at a time in the thermal desorption experiments, is described and demonstrated for the interaction of benzotriazole adsorbed on a Ni(111) surface. Conventional two-dimensional TPD spectra can be extracted from the CTPD by taking vertical slices of the contour

    Procedimiento de preparación y materiales conformados basados en compuestos eutécticos binarios o ternarios de circonia

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    Referencia OEPM: P9600891.-- Fecha de solicitud: 19/04/1996.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC).Procedimiento de preparación y materiales conformados basados en compuestos eutécticos binarios o ternarios de circonia. La presente invención está relacionada con la preparación de materiales con estructuras eutécticas micrométricas basados en mezclas de óxidos, conformados con dimensiones mili y submilimétricas mediante fusión zonal por láser con diferentes sistemas ópticos de focalización y control de los haces de los láseres. Su utilización es en el sector de la producción y conservación de energía, como elementos calefactores, refractarios, cátodos para plasmas de aire, electrodos, en componentes para celdas de combustión, microsensores de gas oxígeno, etc.Peer reviewe

    Exponential and moment inequalities for U-statistics

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    A Bernstein-type exponential inequality for (generalized) canonical U-statistics of order 2 is obtained and the Rosenthal and Hoffmann-J{\o}rgensen inequalities for sums of independent random variables are extended to (generalized) U-statistics of any order whose kernels are either nonnegative or canonicalComment: 22 page

    Photocatalytic hydrogen production using ethanol as sacrificial agent from gas and liquid phases on reduced graphene oxide-TiO2- Pt nanocomposites

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    ABSTRACT: Various strategies such as heterostructuring, crystal/textural modifications and band gap engineering, have been applied to the improvement of the photocatalytic activity of Titania for hydrogen production from water splitting. In this work deposited Pt on TiO2 is used as electron trap to suppress charge recombination. To reinforce this effect, composites with graphene oxide (GO) have been prepared, exhibiting promising photocatalytic performance for both hydrogen generation and the degradation of ethanol added as hole scavenger. Photocatalytic reactions were conducted in gas and liquid phases.N/

    Magnetic characterization of Fe, Ni, Co nanoparticles dispersed in phyllosilicate type silicon oxide

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    International audienceWe present the magnetic properties of silica-supported metal (Fe,catalyst) nanoparticles synthesized by precipitation of metal nitrate in ammonia-based medium. Our goal is the study of possible metal-support interactions in the nanoporous catalyst. The temperature dependence of the magnetization for all samples display spin-glass like behavior below c.a. 11-12 K, with clear Curie-Weiss dependence in the high-temperature regime. Spin-glass-like behavior was inferred from dynamic AC susceptibility data after analyzing the frequency-dependence of the in-phase component χ'(f) by the expression W = ΔTf/[Tf Δlog(f)] = 3.0 × 10−3. We found that the magnetic behavior of the catalyst is drastically affected by the existence of interactions between the metal and the support

    An Aza-Fused pi-Conjugated Microporous Framework Catalyzes the Production of Hydrogen Peroxide

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    "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 http://pubs.acs.org/page/policy/articlesonrequest/index.html"[EN] In order to produce hydrogen peroxide in small-scale electrochemical plants, selective catalysts for the oxygen reduction reaction (ORR) toward the desired species are required. Here, we report about the synthesis, characterization, ORR electrochemical behavior, and reaction mechanism of an aza-fused pi-conjugated microporous polymer, which presents high selectivity toward hydrogen peroxide. It was synthesized by polycondensation of 1,2,4,5-benzenetetramine tetrahydrochloride and triquinoyl octahydrate. A cobalt-modified version of the material was also prepared by a simple postsynthesis treatment with a Co(II) salt. The characterization of the material is consistent with the formation of a conductive robust porous covalent laminar polyaza structure. The ORR properties of these catalysts were investigated using rotating disk and rotating disk ring arrangements. The results indicate that hydrogen peroxide is almost exclusively produced at very low overpotentials on these materials. Density functional theory calculations provide key elements to understand the reaction mechanism. It is found that, at the relevant potential for the reaction, half of the nitrogen atoms of the material would be hydrogenated. This hydrogenation process would destabilize some carbon atoms in the lattice and would provide segregated charge. On the destabilized carbon atoms, molecular oxygen would be chemisorbed with the aid of charge transferred from the hydrogenated nitrogen atoms and solvation effects. Due to the low destabilization of the carbon sites, the resulting molecular oxygen chemisorbed state, which would have the characteristics of a superoxide species, would be only slightly stable, promoting the formation of hydrogen peroxide.This work has been financially supported by the MCINN-FEDER (projects CTQ2016-76221-P, MAT2013-46753-C2-1-P, and MAT2014-52305-P) and Generalitat Valenciana (project PROMETEO/2014/013).Briega-Martos, V.; Ferre Vilaplana, A.; De La Peña, A.; Segura, J.; Zamora, F.; Feliu, J.; Herrero, E. (2017). An Aza-Fused pi-Conjugated Microporous Framework Catalyzes the Production of Hydrogen Peroxide. ACS Catalysis. 7(2):1015-1024. https://doi.org/10.1021/acscatal.6b03043S101510247

    Productive evaluations of Aberdeen Angus and Argentina Criollo beef in two feeding systems in the northeast of The Pampa. Argentina

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    The objective of the study is to evaluate the productivity of two winter pastures under a rotational grazing system with and without energetic concentrates in the diet; in order to evaluate the productive behavior in Aberdeen Angus and Argentine Criollo beef. Sixty steer, castrated males of the breed Aberdeen Angus, of 6-7 months of age and 175 kg, and Argentine Criollo, at 8-9 months of age and 199 kg. The steer study were divided into four groups of 15 steer each. The study was conducted for 13 months in the first five months they grazed on oat farming (Avena sativa); and the following seven months on cebadilla (Bromus uniloides) and Lucerne (Medicago sativa) sown grassland, and the final month on oat. As a supplement they received ground grain sorghum (33 percent of the diet). The weight increment during the 13 months of the study went from 294,23 kg; 239,20 kg; 214,00 kg and 203,19 kg; an average weight gain of 0,754 kg/d; 0,613 kg/d; 0,549 kg/d and 0,520 kg/ d; a production per hectare of 374 kg/ha; 304 kg/ ha; 272 kg/ha and 258 kg/ha; and a stock efficiency of 77 percent, 67 percent, 59 percent, and 61 percent in the groups ACS, ASS, CCS and CSS, respectively.El objetivo del estudio es evaluar la productividad de dos invernadas pastoriles, bajo un sistema de pastoreo rotativo con y sin complemento de concentrados energéticos en la dieta; así como evaluar el comportamiento productivo de terneros Aberdeen Angus (AA) y Criollo Argentino (CA). Se cuenta con 60 terneros, machos castrados, de las razas Aberdeen Angus, con 6-7 meses de edad y 175 kg de peso, y Criollo Argentino, 8-9 meses de edad y 199 kg de peso. Se forman cuatro lotes de 15 terneros (ASS= Aberdeen sin complemento, ACS= Aberdeen con complemento, CSS= Criollo sin complemento y CCS= Criollo con complemento). El ensayo se realiza durante 13 meses: en los 5 primeros pastan en un cultivo de avena (Avena sativa) los siete meses siguientes en una pradera de alfalfa (Medicago sativa) y de cebadilla (Bromus uniloides) y en el último mes en un cultivo de avena. Como suplemento reciben grano de sorgo molido (33 p.100 de la dieta). El incremento medio de peso de los terneros, en los 13 meses de ensayo, fue 294,23 kg; 239,20 kg; 214,00 kg y 203,19 kg; la ganancia media de peso de 0,754 kg/d; 0,613 kg/d; 0,549 kg/d y 0,520 kg/d; la producción por hectárea de 374 kg/ ha, 304 kg/ha, 272kg/ha y 258 kg/ha; y la eficiencia en los lotes ACS, ASS, CCS y CSS, fue del 77, 67, 59 y 61 p.100, respectivamente

    Análisis de gestión de las explotaciones caprinas extensivas de la sierra norte y este de Jaén

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    Se analizan 63 explotaciones caprinas extensivas de la Sierra Norte y Este de Jaén (Sierra Morena, Mágina, Segura, Cazorla y Las Villas). Se utilizan las razas: Blanca Andaluza, Blanca Celtibérica y Castiza, con una dimensión media por explotación de 1015 ha, 213 cabras, 169 derechos a prima y 204 chivos comerciales. El prinicipal problema de las explotaciones analizadas es la deficiente gestión, por ello se estructuran en función de su precio umbral. Los costes unitarios presentan una relación inversa a la dimensión y proporcional a la intensificación productiva y a las variables económicas: alimentación, mano de obra y amortizaciones. Se pueden diferenciar dos sistemas caprinos extensivos: El primero responde al modelo tradicional de producción de carne y presenta costes superiores a 7500 pta1/chivo, que sobrepasan el precio medio percibido de 7361 pta/chivo. Se caracteriza una superficie media pastoreada de 876 ha, 225 cabras, baja carga ganadera (0,06 UGM/ha), bajo índice de chivos comerciales por cabra (1,04). El segundo modelo presenta cierto grado de intensificación productiva, con costes (<5000 pta/ chivo) inferiores al precio medio percibido 7361 pta/chivo. Este sistema se caracteriza por una dimensión de 191 cabras y un área pastoreada de 940 ha con índices de carga de 0,33 UGM/ha y de 1,24 chivos comerciales por cabra

    Jaw biodynamic data for 24 patients with chronic unilateral temporomandibular disorder

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    This study assessed 24 adult patients, suffering from severe chronic unilateral pain diagnosed as temporomandibular joint (TMJ) disorder (TMD). The full dentate patients had normal occlusion and had never received an occlusal therapy, i.e., were with natural dental evolution/maturation. The following functional and dynamic factors were assessed: (1) chewing function; (2) TMJ remodeling or the condylar path (CP); and (3) lateral jaw motion or lateral guidance (LG). CPs were assessed using conventional axiography, and LG was assessed by K7 jaw tracking. Seventeen (71%) of the 24 (100%) patients consistently showed a habitual chewing side. The mean (standard deviation [SD]) of the CP angles was 47.90 (9.24) degrees. The mean (SD) of the LG angles was 42.95 (11.78) degrees. Data collection emerged from the conception of a new TMD paradigm where the affected side could be the habitual chewing side, the side with flatter lateral jaw motion or the side with an increased CP angle. These data may lead to improved diagnosis, therapy plans and evolution in TMD patients
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