3,096 research outputs found

    Mechanical magnetometry of Cobalt nanospheres deposited by focused electron beam at the tip of ultra-soft cantilevers

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    Using focused-electron-beam-induced deposition, Cobalt magnetic nanospheres with diameter ranging between 100 nm and 300 nm are grown at the tip of ultra-soft cantilevers. By monitoring the mechanical resonance frequency of the cantilever as a function of the applied magnetic field, the hysteresis curve of these individual nanospheres are measured. This enables to evaluate their saturation magnetization, found to be around 430 emu/cm^3 independently of the size of the particle, and to infer that the magnetic vortex state is the equilibrium configuration of these nanospheres at remanence

    Salt efflorescences in the iberian pyrite belt: occurrence and distribution

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    The evolution of sulfide wastes promotes acid mine drainage and phenomena of supergenic neoformation. These contribute to a secondary paragenesis, often dominated by salt efflorescences. These can be used as mineralogical indicators of reactivity conditions and of AMD potential. The present study shows the salt efflorescences that develop in the Spanish sector of the Iberian Pyrite Belt, as a result of the strong acid mine drainage observed in this region. The obtained results showed dominance of metallic sulfates. Depending on the proximity to the sulfide sources, there are different types of assemblages. Iron and cooper minerals dominate inside the mining areas, whereas magnesium sulfates occur more abundantly in the receiving river networkFinancial support was provided by the Andalusian Autonomous Government Excellence Project, code P06-RNM-02167. This work was also co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), project ICT (UID/GEO/04683/2013) with reference POCI-01-0145-FEDER- 007690 and national funds provided by Fundação para a Ciência e Tecnologia.info:eu-repo/semantics/publishedVersio

    Magnesium and aluminum sulfates in salt efflorescences from acid mine drainage in the Iberian Pyrite Belt (SW Spain)

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    Proceedings IMWA 2016, Freiberg/Germany | Drebenstedt, Carsten, Paul, Michael (eds.) | Mining Meets Water – Conflicts and Solutions.The current study is focused on AMD-precipitates that compose the typical magnesium and aluminum sulfate assemblages in the Spanish sector of the Iberian Pyrite Belt (SW Spain). The main objectives are identify and describe the composition, morphology and paragenetic relationships of these sulfate phases. From the methodological pint of view, sampling procedure covered the entire metallogenetic province, including five selected representative mines and eight river basins, which are the main receptors of the acid mine drainage discharges. The mineralogical analyses were performed by X-Ray diffraction and electron microscopy. The obtained results showed the extraordinary abundance of aluminum sulfates with acicular habit, from the series pickeringite-apjhonite-halotrichite. They form typical assemblages with other aluminum sulfates, such as alunogen and tamarugite, and with the Mg sulfates: epsomite and hexahydrite. Moreover, the paragenetic relationships indicate the late occurrence of acicular Alsulfates from the halotrichite group.Financial support for this research was provided by the Andalusian Autonomous Government Excellence Project, code P06-RNM-02167. This work was also co-funded by the European Union through the European Regional Development Fund, based on COMPETE 2020 (Programa Operacional da Competitividade e Internacionalização), project ICT (UID/GEO/04683/2013) with reference POCI-01-0145-FEDER-007690 and national funds provided by Fundação para a Ciência e Tecnologia.info:eu-repo/semantics/publishedVersio

    Estudio petrológico previo a la restauración de la fachada de la antigua Universidad de Alcalá de Henares

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    Las operaciones de conservación y restauración de las edificaciones monumentales que constituyen el Patrimonio Artístico de los diferentes países, se encuentran abandonando el nivel artesanal que las caracterizaba en el pasado. Ello ha sido consecuencia por una parte, de la posibilidad de utilizar un número continuamente creciente de nuevos productos que la industria pone a disposición del conservador y por otra, de la necesidad de: Evitar tratamientos irreversibles e inadecuados, ó inútiles, en el mejor de los casos. Reducir en lo posible los costes de operación, aplicando un tratamiento racional y estudiado con los medíos de que hoy día se dispon

    Impacto ambiental sobre patrimonio monumental en piedra

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    La rápida evolución industrial y los procesos de consumo en los últimos años, en los países desarrollados, están originando un acelerado proceso de deterioro del Patrimonio Monumental. Ello ha dado lugar a que estratos cada vez más amplios de la sociedad se sensibilicen ante el problema. Un monumento no debería ser considerado como algo aislado: a lo largo del tiempo se ha armonizado y equilibrado con su entorno. La polución temporal de ese entorno, desde los puntos de vista climático, físico-químico, político, social, etc., han provocado lentas modificaciones para restablecer el equilibrio, tanto en la propia edificación monumental, como en los materiales que lo componen. Estas modificaciones, han venido implicando, normalmente, un proceso de deterioro, eufemísticamente denominado "Mal de la Piedra"

    Study of monumental stone from Madrid district

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    It is described a study concerning the characteristics of the main types of monumental building stones used in the Madrid Community, made as a base for future interventions on this heritage

    El volcanismo hercínico y tardihercínico de la zona de Puertollano (Ciudad Real)

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    Se describe el volcanismo hercínico y tardihercínico de la región alcudiense, en la zona de Puertollano, inscribiendo dicho acontecimiento en el contexto de los fenómenos que se asocian al desarrollo de la cadena herclniana europea, durante el Carbonífero Superior y el Permian

    Acceso a jeringas estériles entre los jóvenes de Madrid y Barcelona que se inyectan drogas y su asociación con las prácticas de riesgo

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    [EN] To evaluate access to sterile syringes and its association with injection risk behaviour in Madrid and Barcelona. Cross-sectional community study by computer-assisted personal interview in 465 young heroin injectors between 2001 and 2003. Some 4.2% had not obtained any free sterile syringes in the previous 12 months. In Madrid 32.1% had obtained all their sterile syringes free of charge (ASSF), versus 44.6% in Barcelona (p<0.01). Not sharing (not using syringes used by someone else and not front/backloading) was associated with obtaining ASSF (OR=1.69) and with sporadic injection (OR=1.83). Not reusing one's own syringes was associated with the same two variables (OR=4.02 and OR=2.50, respectively). Access to sterile syringes is very high in Madrid and Barcelona, although the two cities have different approaches. The acquisition of all syringes free of charge should be facilitated, especially among frequent injectors. [ES] Evaluar el acceso a jeringas estériles y su asociación con prácticas de inyección de riesgo en Madrid y Barcelona. Material y método: Estudio transversal en la comunidad de 465 jóvenes que se inyectan heroína, realizado entre 2001 y 2003, mediante entrevista asistida por ordenador. Un 4,2% no obtuvo jeringas estériles gratuitas en los últimos 12 meses. En Madrid, el 32,1% obtuvo todas las jeringas estériles gratis (TJEG), frente al 44,6% de Barcelona (p < 0,01). No compartir (no utilizar jeringas ajenas usadas o droga diluida en las usadas por otros) se asoció con obtener TJEG (odds ratio [OR] = 1,69) e inyectarse esporádicamente (OR = 1,83). No reutilizar las jeringas propias se asoció con las mismas variables (OR = 4,02 y OR = 2,50, respectivamente). En Madrid y Barcelona el acceso a jeringas estériles es muy elevado, aunque con modelos diferentes. Debe facilitarse la obtención de todas las jeringas estériles gratis, especialmente entre los jóvenes que se inyectan con mayor frecuencia.This research was financed primarily by the Fundación para Investigación y la Prevención del Sida en España (FIPSE 3035/99 - Foundation for AIDS Research and Prevention in Spain); the analysis was possible thanks to the support of the Ciber de Epidemiología y Salud Pública.S

    Ressignificar o Ensino e a Aprendizagem a partir da Filosofia da Diferença

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    Apresentar possíveis aproximações entre a Filosofia da Diferença e a educação é o nosso objetivo com este texto. Ao pensarmos na necessidade da superação de práticas educacionais alicerçadas em bases que não condizem com as demandas da escola atual - inclusiva - apresentamos um possível olhar para os processos de ensino (ainda concebido como a transmissão de conteúdos) e de aprendizagem (ainda considerada como a capacidade de reprodução do que foi ensinado). Esta visão, própria da racionalidade filosófica e científica, prejudica aqueles que não têm o perfil desejado pela escola e que, por este motivo, são excluídos, impedidos de se desenvolverem segundo os seus interesses e capacidades. A ciência educacional moderna, sustentada em um pragmatismo que busca verificar a eficiência da ação pedagógica visando alcançar metas instituídas tendo como base um modelo idealizado de aluno, deve ser superada por um modo de planejar e desenvolver o ensino a partir de um novo entendimento do que é ensinar e aprender. Um pensamento que concebe o ensino como a emissão de signos e a aprendizagem como uma criação – subjetiva - favorece a construção colaborativa de uma escola coerente com as atuais demandas educacionais, advindas da necessidade de incluir todos os alunos, sem distinções.&nbsp

    The steel market in Mexico: 1980-2015

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    Mediante modelos econométricos de ecuaciones simultáneas, se estimó un modelo lineal multivariable para determinar el efecto de las variables en el mercado del acero en México, así como la estimación de las elasticidades
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