1,637 research outputs found

    Compact forms of reduced density matrices

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    10 págs.; 3 tabs.; PACS number~s!: 31.15.Hz, 31.10.1zThe necessary and sufficient minimum information carried by reduced density matrices (RDM) are discussed. A method is reported for obtaining the same information as a p-RDM although in compact form, from which all the redundant information is omitted. The algebra operations and basic properties of these compact-form matrices are obtained. ©2003 The American Physical SocietyWe are greatly indebted to the Spanish Ministerio de Educación, Cultura y Deporte for its support under Project No. BQU2000-1158Peer Reviewe

    Síntesis y aplicación de los ortofosfatos de magnesio en procesos orgánicos

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    La memoria, se enmarca dentro de un amplio plan de investigación, que se viene desarrollando en el Dpto. de Química Orgánica de la Universidad de Córdoba, sobre empleo de ortofosfatos metálicos y sistemas relacionados, utilizables como catalizadores en procesos orgánicos. Consta de tres partes, bien diferenciadas, pero relacionadas entre si: a) obtención de los ortofosfatos, siguiendo diferentes procedimientos. b) caracterización de los mismos, tanto desde el punto de vista estructural (xrd, tga-dta, sem- edax, etc.), como textural (drift, xps, porosimetria, etc.) y de propiedades ácido-básicas. c) utilización de los materiales, como catalizadores de una serie de procesos orgánicos "test" en fase gaseosa (transformación de alcoholes, alquilación de anilina con metanol, transferencia de hidrogeno, condensación entre acetofenona y metanol

    Dynamic response of periodic infinite structure to arbitrary moving load based on the Finite Element Method

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    [EN] A common problem in railway engineering is the dynamic of repetitive structures subject to moving loads. Bridges, rails or catenaries are the most representative periodic structures, over which the train acts as a moving exciter. Usually, these structures are long enough to consider that their dynamic response is in permanent regime. To assume the steady-state regime some features have to be considered: infinite length structure, perfect periodicity and constant velocity of the moving load. This paper adopts these assumptions and provides the steady-state solution of a generic periodic structure subject to an arbitrary and also periodic moving load. The structure is divided into repetitive blocks modelled by the Finite Element Method. By applying the periodicity condition it is possible to consider the entire structure dynamics with only one block. The problem is stated in the frequency domain and moved back to time domain by means of Discrete Fourier Transform.The authors would like to acknowledge the financial support received from the Spanish Ministry of Economy, Industry and Competitiveness (TRA2017-84736-R).Gil-Romero, J.; Gregori, S.; Tur, M.; Fuenmayor, F. (2022). Dynamic response of periodic infinite structure to arbitrary moving load based on the Finite Element Method. En Proceedings of the YIC 2021 - VI ECCOMAS Young Investigators Conference. Editorial Universitat Politècnica de València. 326-333. https://doi.org/10.4995/YIC2021.2021.12606OCS32633

    Modified surfatron device to improve microwave-plasma-assisted generation of RONS and methylene blue degradation in water

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    Microwave-induced plasmas generated at atmospheric pressure are very attractive for a great variety of applications since they have a relatively high electron density and can generate large amounts of reactive species. Argon plasmas can be sustained inside dielectric tubes but are radially contracted and exhibit filamentationeffects when the diameter of the tube is not narrow enough (over 1.5 mm). In this work, we describe a newapproach for creating microwave (2.45 GHz) plasmas under atmospheric pressure conditions by using a surfatron device and power from 10 W. This modified design of the reactor enables the sustenance of non-filamented argon plasmas. These new plasmas have a higher gas temperature and electron density than the plasma generated in the original surfatron configuration. The new design also allows for the maintenance of plasmas with relatively high proportions of water, resulting in the generation of larger quantities of excited hydroxyl radicals (⋅OH*). Thus, this novel configuration extends the applicability of microwave-induced plasmas by enabling operation under new conditions. Finally, the degradation of methylene blue (MB) in aqueous solutions has been assessed under different initial dye concentrations and argon flow conditions. The new plasma produces a substantial increase in hydrogen peroxide and nitrate concentrations in water and leads to a noteworthy enhancement in MB degradation efficiency. The introduction of water into the plasma produces a minor additional improvement

    Practical considerations for clinical use of mesenchymal stem cells: From the laboratory to the horse

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    Since the clinical use of mesenchymal stem cells (MSCs) for treating musculoskeletal injuries is gaining popularity, practitioners should be aware of the factors that may affect MSCs from tissue harvesting for MSC isolation to cell delivery into the injury site. This review provides equine practitioners with up-to-date, practical knowledge for the treatment of equine patients using MSCs. A brief overview of laboratory procedures affecting MSCs is provided, but the main focus is on shipping conditions, routes of administration, injection methods, and which commonly used products can be combined with MSCs and which products should be avoided as they have deleterious effects on cells. There are still several knowledge gaps regarding MSC-based therapies in horses. Therefore, it is important to properly manage the factors which are currently known to affect MSCs, to further strengthen the evidence basis of this treatment

    Transformation of light paraffins in a microwave-induced plasma-based reactor at reduced pressure

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    In this work, the effects of the plasma chemistry of an argon microwave (2.45 GHz) discharge at reduced pressure on the conversion of three different alkanes (n-pentane, n-hexane and n-heptane) have been studied. Optical emission spectroscopy has been used for identifying the species generated in the plasma and for estimating its gas temperature. Gas chromatography, mass spectrometry, X-ray diffraction and FTIR spectroscopy have been employed for identifying and analyzing all the compounds present as reaction products. Microwave power and hydrocarbon flow rate have been found critically to affect both conversion and selectivity. The main gas products have been hydrogen and ethylene. At low powers (100–150 W) the conversion to hydrogen has been quite selective. However, at high powers (>300 W) or slow hydrocarbon flow rate ethylene has resulted to be the major product. In most cases, an important fraction of a carbon deposit has been obtained which has been characterized as an amorphous hydrogenated carbon film. Some plausible mechanisms explaining the formation of the main reaction products have been discussed

    Differentiation of equine bone marrow derived mesenchymal stem cells increases the expression of immunogenic genes

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    Mesenchymal stem cells (MSCs) are a promising treatment for equine musculoskeletal injuries because of their ability to regulate the inflammation and to differentiate into other cell types. Since interest in allogeneic therapy is rising, concerns about MSC immunogenicity need to be addressed. Differentiated MSCs from several species increase their expression of immunogenic molecules and induce alloresponses, but equine MSC immunogenic profile after differentiation has not been reported. Therefore, the aim of this study was to assess the gene expression of immunogenic markers in tri-lineage differentiated equine bone marrow derived MSCs (eBM-MSCs). For this purpose, eBM-MSCs (n = 4) were differentiated into osteoblasts, adipocytes and chondrocytes. Differentiation was confirmed by specific staining and gene expression of lineage-related markers. Subsequently, gene expression of MHC-I, MHC-II, CD40 and CD80 was analyzed in undifferentiated (control) and tri-lineage differentiated eBM-MSCs. Osteogenesis and adipogenesis, but not chondrogenesis, significantly upregulated MHC-I; MHC-II expression significantly increased in the three lineages, while CD40 and CD80 expression did not change. Despite this, MHC-I and MHC-II upregulation after differentiation might lead to increased immunogenicity and risk of allorecognition, either eBM-MSCs differentiate in vivo after administration or they are differentiated prior to administration, with potential negative consequences for effectiveness and safety of allogeneic therapy

    Efficient Removal of Nonylphenol Isomers from Water by Use of Organo-Hydrotalcites

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    The presence of potent organic endocrine-disrupting chemicals (EDCs) in natural aquifers can have adverse impacts on public health and the environment. 4-nonylphenol, one such EDC, can be efficiently removed from water by adsorption onto a clayey material. In this work, we created an effective sorbent for this purpose by using co-precipitation and subsequent ion-exchange to intercalate the organic anion deoxycholate into a Mg/Al hydrotalcite. Intercalating deoxycholate ions increased the organophilicity of the hydrotalcite surface. The solid was used to adsorb 4-nonylphenol at different pollutant concentrations and temperatures. The adsorption process was subjected to a kinetic study. Based on the results, the EDC was adsorbed by chemisorption. In addition, based on the equilibrium isotherms used for the process, the Freundlich model was the most accurate in reproducing the adsorption of 4-nonylphenol onto deoxycholate-intercalated hydrotalcite
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