2,750 research outputs found

    Ruthenium molecular complexes immobilized on graphene as active catalysts for the synthesis of carboxylic acids from alcohol dehydrogenation

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    Ruthenium complexes containing N-heterocyclic carbene ligands functionalized with different polyaromatic groups (pentafluorophenyl, anthracene, and pyrene) are immobilized onto the surface of reduced graphene oxide. The hybrid materials composed of organometallic complexes and graphene are obtained in a single-step process. The hybrid materials are efficient catalysts for the synthesis of carboxylic acids from the dehydrogenation of alcohols in aqueous media. The catalytic materials can be recycled up to ten times without significant loss of activity. The catalytic activity of the pyrene derivative, Pyr-Ru (3) is enhanced when the ruthenium complex is anchored onto the surface of graphene. The carbonaceous material limits the degradation of the ruthenium complex resulting in increased activity and requiring lower catalyst loadings. The catalytic process of the pyrene hybrid material is heterogeneous in nature due to the strong interaction between the pyrene and graphene. The catalytic process of the anthracene and pentafluorophenyl hybrid materials is governed by the so-called ‘boomerang effect’. The ruthenium molecular complex is released from and returned to the graphene surface during the catalytic reaction. Mechanistic insight has been obtained experimentally and theoretically. The energy profile suggests that the rate-determining step is the water nucleophilic attack to a coordinated aldehyde complex to form a gem-diolate complex.The authors thank the financial support from MINECO (CTQ2015-69153-C2-2-R and CTQ2015- 67461-P), Generalitat Valenciana (AICO/2015/039), Universitat Jaume I (P1.1B2015-09) and Universidad de Zaragoza (UZ2014-CIE-01)

    Waste and Recycled Materials and their Impact on the Mechanical Properties of Construction Composite Materials

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    In a world increasingly fixated on the demands of sustainable development, too much attention has been focused on the widely used building materials, mainly on those tools and strategies for their reuse and those characteristics for considering them as environmental-friendly materials. Among the strategies are the following: (a) increased reliability on waste and recycled materials—such action will have to incorporate the substitution of recycled for virgin materials; (b) improved durability through reduction of materials needed for their replacement; and (c) improved mechanical properties, which reduces the use of raw materials. Extensive research and development activities in recycling composite materials have been conducted, and various technologies have been developed: (a) mechanical recycling, (b) thermal recycling, and (c) chemical recycling. However, gamma radiation is an innovative and clean technology, alternative to conventional recycling procedures. Gamma irradiation has proved to be an adequate tool for modifications of the physicochemical properties of polymers, through different effects: (a) scission, branching as well as cross-linking of polymer chains and (b) oxidative degradation. Moreover, the reuse and recycling of waste materials and the use of gamma radiation are useful tools for improving the mechanical properties of concrete. In this chapter, we show results of the effects of gamma irradiation on the physicochemical properties of waste and recycled materials and their reuse to enhance the properties of construction composite materials

    Changes in height growth patterns in the upper tree-line forests of Tierra del Fuego in relation to climate change

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    Los bosques de Nothofagus pumilio ocupan las laderas de montaña hasta alcanzar el limite altitudinal del bosque. Estos ambientes extremos, donde los bosques están bajo condiciones de estrés ambiental, son óptimos para estudiar patrones de cambio debidos a variaciones climáticas. El objetivo fue analizar cambios recientes en el crecimiento en altura en bosques localizados en el tree-line altitudinal en Tierra del Fuego (Argentina) y establecer posibles vinculaciones con cambios en la temperatura observados durante las últimas décadas. Se muestrearon nueve sitios, y se midieron cuatro parcelas en cada sitio. Se determinó la estructura forestal y se realizaron análisis fustales para evaluar los patrones de crecimiento en altura. Se realizaron ANOVA y análisis de clasificación usando como factores principales al sitio y al tiempo. El crecimiento en altura aumentó a lo largo del tiempo, e.g. 1,0 cm año-1 durante 1870-1959, 2,7 cm año-1 durante 1960-1979 y 5,0 cm año-1 durante 1980-2010. Esas diferencias fueron significativas entre períodos de tiempo y sitios, pudiendo estar relacionadas con la localización geográfica. El incremento en el crecimiento en altura observado está relacionado con los cambios en la temperatura de superficie experimentada en todo el mundo. Una declinación en el crecimiento en altura durante las últimas dos décadas, también puede estar relacionada con una disminución regional de la temperatura de aire. El análisis del crecimiento en altura es una herramienta de utilidad para evaluar la incidencia que tiene el cambio climático sobre el crecimiento de los árboles que crecen en ambientes extremos.Nothofagus pumilio occupy the mountain slopes reaching to the upper altitudinal limit of the forests. This extremely stressful environment represents the optimum conditions to study changes in growth patterns due to climate variations. Our goal was to analyze recent changes in stem height growth in forests located in the upper altitudinal tree-line along Tierra del Fuego (Argentina), and establish possible linkages to changes observed in surface temperature during the last decades. Nine locations were sampled, and four plots were measured in each location. Forest structure was characterized, and stem analyses were performed to assess height growth patterns. ANOVAs and classification analyses were conducted using location and time as main variables. Tree-growth height increased with time, e.g. 1.0 cm.year-1 during 1870-1959, 2.7 cm year-1 during 1960-1979, and 5.0 cm year-1 during 1980-2010. These differences were significant between periods and locations, and can be related to its geographical situation. Increment in stem height growth seems to be related with the worldwide surface air temperature. A decline in stem height growth registered during the last two decades can also be related with the regional decrease in the mean air temperature. The analysis of stem height growth is a useful tool to evaluate the incidence of climate change over trees growing under extreme environmental conditions.Facultad de Ciencias Agrarias y ForestalesLaboratorio de Investigación de Sistemas Ecológicos y Ambientale

    Changes in height growth patterns in the upper tree-line forests of Tierra del Fuego in relation to climate change

    Get PDF
    Los bosques de Nothofagus pumilio ocupan las laderas de montaña hasta alcanzar el limite altitudinal del bosque. Estos ambientes extremos, donde los bosques están bajo condiciones de estrés ambiental, son óptimos para estudiar patrones de cambio debidos a variaciones climáticas. El objetivo fue analizar cambios recientes en el crecimiento en altura en bosques localizados en el tree-line altitudinal en Tierra del Fuego (Argentina) y establecer posibles vinculaciones con cambios en la temperatura observados durante las últimas décadas. Se muestrearon nueve sitios, y se midieron cuatro parcelas en cada sitio. Se determinó la estructura forestal y se realizaron análisis fustales para evaluar los patrones de crecimiento en altura. Se realizaron ANOVA y análisis de clasificación usando como factores principales al sitio y al tiempo. El crecimiento en altura aumentó a lo largo del tiempo, e.g. 1,0 cm año-1 durante 1870-1959, 2,7 cm año-1 durante 1960-1979 y 5,0 cm año-1 durante 1980-2010. Esas diferencias fueron significativas entre períodos de tiempo y sitios, pudiendo estar relacionadas con la localización geográfica. El incremento en el crecimiento en altura observado está relacionado con los cambios en la temperatura de superficie experimentada en todo el mundo. Una declinación en el crecimiento en altura durante las últimas dos décadas, también puede estar relacionada con una disminución regional de la temperatura de aire. El análisis del crecimiento en altura es una herramienta de utilidad para evaluar la incidencia que tiene el cambio climático sobre el crecimiento de los árboles que crecen en ambientes extremos.Nothofagus pumilio occupy the mountain slopes reaching to the upper altitudinal limit of the forests. This extremely stressful environment represents the optimum conditions to study changes in growth patterns due to climate variations. Our goal was to analyze recent changes in stem height growth in forests located in the upper altitudinal tree-line along Tierra del Fuego (Argentina), and establish possible linkages to changes observed in surface temperature during the last decades. Nine locations were sampled, and four plots were measured in each location. Forest structure was characterized, and stem analyses were performed to assess height growth patterns. ANOVAs and classification analyses were conducted using location and time as main variables. Tree-growth height increased with time, e.g. 1.0 cm.year-1 during 1870-1959, 2.7 cm year-1 during 1960-1979, and 5.0 cm year-1 during 1980-2010. These differences were significant between periods and locations, and can be related to its geographical situation. Increment in stem height growth seems to be related with the worldwide surface air temperature. A decline in stem height growth registered during the last two decades can also be related with the regional decrease in the mean air temperature. The analysis of stem height growth is a useful tool to evaluate the incidence of climate change over trees growing under extreme environmental conditions.Facultad de Ciencias Agrarias y ForestalesLaboratorio de Investigación de Sistemas Ecológicos y Ambientale

    Smart sensing interoperability platforms in the scope of Atlantos

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    This paper aims to demonstrate the capabilities of a Smart Cable which aims to convert any commercial non-PUCK-enabled sensor in a Smart PUCK-enabled device. Through this development, it can be easily integrated on a sensor web platform in order to access the data in real time, and so there is no need to rely on each sensor manufacturer to comply with Sensor Web Enablement standards. The results presented in this paper were acquired during some real field experiments performed between the 24th and 28th of September at PLOCAN facilities in Gran Canaria. During these days three Turner Designs Cyclops sensors were successfully integrated and tested in a mission using an observing surface vehicle such as the Wave Glider SV-2.Peer Reviewe

    Personalized Medicine in Ovarian Cancer: A Perspective From Mexico

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    Ovarian cancer (OC) represents a serious health problem worldwide. In Mexico, most OC patients are detected at late stages, consequently making OC one of the leading causes of death in women after reaching puberty. Personalized medicine (PM) provides an individualized therapeutic opportunity for treating each patient relying on “omic” tools to match the correct drug with the specific pathogenic genomic signature. PM can help predict the best therapeutic option for each affected woman suffering from OC. In recent years, Mexico has made contributions to the PM of OC; however, it still has a long way to go for its full implementation in the country’s health system

    Estrategia de negocios para la empresa Baldwin

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    El presente trabajo de obtención de grado muestra los resultados logrados de la empresa Baldwin en el simulador de negocios CAPSTONE. El primer capítulo está compuesto por el marco teórico, mismo que se enfoca en la estrategia, planeación, modelos de negocio, liderazgo estratégico y diversos casos de estudio donde se realiza una validación de los conceptos aplicados en situaciones reales y el razonamiento de su éxito o fracaso. En el segundo capítulo, se encuentra el cómo opera el simulador de negocios CAPSTONE, los diversos módulos que lo integran, el mercado y sus preferencias. De igual forma, se aborda la estrategia que la empresa Baldwin sigue, las funciones de su equipo directivo, su estrategia, las tácticas por departamento y los objetivos de puntaje en los indicadores del Balanced Scorecard. Los cuatro capítulos siguientes incluyen el análisis de la operación de cada bienio a partir del 2021 al 2028. Cada capítulo de este apartado describe los resultados de las empresas que conforman la industria de sensores, su comparación con Baldwin y la ejecución de las tácticas por departamento de esta compañía. En el capítulo siete, concluye el trabajo con la reflexión de los integrantes del equipo directivo señalando sus aprendizajes en el simulador de negocios CAPSTONE.ITESO, A.C

    Visible light harvesting alkyne hydrosilylation mediated by pincer platinum complexe

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    In this manuscript we assess the catalytic properties of pincer platinum complexes in alkyne hydrosilylation either under photo or thermal conditions. The visible light-induced hydrosilylation proved to be more efficient. It can be performed at room temperature and required lower catalyst loadings than that operating under thermal conditions. The platinum complexes play a dual role in photohydrosilylation as serve as a photosensitizer and a catalyst enabling species in bond breaking/forming transformations. In addition, alkyne hydrosilylation is achieved with moderate regio- and stereoselectivity but is enhanced under photocatalytic conditions and in the case of terminal alkynes we have observed the formation of β(Z) products not observable under thermal conditions. Such differences in selectivity constitute an example of stereodivergent catalysis dictated under photochemical or thermal conditions. The selectivity differences are ascribed to a distinctive reaction mechanism for the light- vs thermally-induced process that involve radical or organometallic intermediates, respectively.MICIU/AEI/FEDER (PID2021-126071OB-C22 and PID2019-104121GB-I00). Universitat Jaume I (UJI-B2022-23). Generalitat Valenciana (PROMETEU/2020/028).Thanks to PID2021-126071OB-C22 and PID2019-104121GB-I00 funded by MICIN/AEI/10.13039/501100011033/ FEDER “Una manera de hacer Europa”. Generalitat Valenciana (PROMETEU/2020/028) and Universitat Jaume I (UJI-B2022-23). L. I-I. thanks MICIN for grant (FPU20/04385). The authors thank ‘Servei Central d’Instrumentació Científica (SCIC) de la Universitat Jaume I’

    The dawn of the liquid biopsy in the fight against cancer

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    ABSTRACT Cancer is a molecular disease associated with alterations in the genome, which, thanks to the highly improved sensitivity of mutation detection techniques, can be identified in cell-free DNA (cfDNA) circulating in blood, a method also called liquid biopsy. This is a non-invasive alternative to surgical biopsy and has the potential of revealing the molecular signature of tumors to aid in the individualization of treatments. In this review, we focus on cfDNA analysis, its advantages, and clinical applications employing genomic tools (NGS and dPCR) particularly in the field of oncology, and highlight its valuable contributions to early detection, prognosis, and prediction of treatment response

    El orientador escolar como agente interno de cambio

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    El presente trabajo resalta la función que los orientadores de los centros educativos pueden cumplir frente al desarrollo y consecución de programas de mejora en las escuelas. Se describe el papel del orientador escolar a partir del análisis de las tareas, tanto de las que puede asumir en los procesos de cambio como de las que, por su formación y trayectoria, articula durante los mismos. Se explicita, asimismo, el trabajo que este profesional aborda juntamente con el equipo directivo, con los profesores y con el alumnado del centro, destacando las potencialidades y características que lo convierten en un líder educativo comprometido con la mejora continua de la escuela
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