Llibres / Capítols de llibre (Ciència dels Materials i Química Física)

URI permanent per a aquesta col·leccióhttps://diposit.ub.edu/handle/2445/21587

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    Magnetical Response and Mechanical Properties of High Temperature Superconductors, YBaCu3O7-X Materials
    (IntechOpen, 2012-04-20) Roa Rovira, Joan Josep; Dias, F. T.; Segarra Rubí, Mercè
    Since the discovery of the second generation High Superconductor Materials (2G-HTSC) in 1986, their magnetic properties have been widely studied by different research groups around the world. During the last years, the mechanical properties at micro-/ and nanometric scale are starting to be studied in order to know and improve the durability of conventional devices. In this book chapter, we would like to focus our attention on the magnetical response and also the mechanical properties of 2G-HTSC. In relation to the magnetic response, the Meissner effect is one important signature of the superconductivity. In this case, a diamagnetic response is observed due to exclusion of the magnetic flux of the interior of the superconducting material when the temperature is below the critical temperature. This important property allows to distinguish a superconducting material from a conducting one. But in several cases the superconducting materials exhibit a paramagnetic response instead of the conventional diamagnetism. This effect is frequently called paramagnetic Meissner effect (PME). In this case, the magnetic flux is not expelled, and a paramagnetic state can be originated. This effect is observed in several magnetic field regimes, and in some cases the paramagnetic response increases with the applied magnetic field, but in others the paramagnetic response decreases when the magnetic field increases...
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    Química Quàntica
    (Llibres de l'Índex, 2017-04) Paniagua, Juan Carlos; Alemany i Cahner, Pere
    Introducció a la mecànica quàntica i aplicació d'aquesta a l'estudi de l'estructura molecular i l'espectroscòpia. L'exposició té un enfocament pedagògic i fa especial èmfasi en la interpretació física de la teoria sense defugir la discussió dels aspectes més difícils.
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    Cryptosporidium sp. in public swimming pools in Barcelona
    (Transworld Research Network, 2011) Gómez López, María Soledad; Gracenea Zugarramurdi, Mercedes; Ángel Ripoll, Laia; Beneyto, Vicenç
    The presence of Cryptosporidium oocysts in swimming pools in Barcelona was studied. The possible influence of the different parameters related to water conditions, pool structure and users has also been analyzed. Cryptosporidium oocysts were detected in 54% of the swimming pools analyzed and in 85% of the sport centers checked. Oocysts concentrations ranged from 0 to 30 oocysts/L. Among parameters related to water conditions, there was no relationship between oocyst presence and water pH, but the influence of temperature was statistically significant (p"MENOR QUE"0.05) (¿2=0.024). Among parameters related to pool structure, the filter backwash water samples revealed a higher percentage of parasitation (58.8%) than the prefilter ones (42.9%). With the medium volume pools (100-500 m3), the percentage was higher (80%). Covered and uncovered pools presented similar prevalences for Cryptosporidium oocysts. Looking at two of the user related parameters, swimming pools with more users and children's swimming pools showed