Electronic properties of SnO2-based ceramics with double function of varistor and humidity sensor

This is the post-print version of the article. The official published version can be obtained from the link below - Copyright @ 2010 AD-Tech.Tin dioxide based varistor ceramics SnO2-Co3O4-Nb2O5-Cr2O3-xCuO (x=0; 0.05; 0.1 and 0.5) were made and their electrical properties were studied. The highest nonlinearity coefficient and electric field (at current density 10-3 A cm-2) were obtained for 0.1 mol.% CuO addition. It was observed that low-field electrical conductivity is increased with relative humidity, therefore, materials obtained exhibit double function of varistor and humidity sensor. The highest humidity sensitivity coefficient is found for SnO2-Co3O4-Nb2O5-Cr2O3 ceramics (without CuO). Observed varistor and humidity-sensitive properties are explained in the frames of grain-boundary double Schottky barrier concept as a decrease of the barrier height with electric field or relative humidity. Using suggested simple theory and data obtained on isothermal capacitance relaxation, the energy of the grain-boundary monoenergetic trapping states were estimated. These values are less than found for activation energy of electrical conduction (as a measure of the barrier height). These observations confirm the barrier concept.This work is funded by the Royal Society, United Kingdom (2007R1/R26999)

Structure and Dynamics of the Globular Cluster Palomar 13

We present Keck/DEIMOS spectroscopy and Canada-France-Hawaii Telescope/MegaCam photometry for the Milky Way globular cluster Palomar 13. We triple the number of spectroscopically confirmed members, including many repeat velocity measurements. Palomar 13 is the only known globular cluster with possible evidence for dark matter, based on a Keck/High Resolution Echelle Spectrometer 21 star velocity dispersion of σ = 2.2 ± 0.4 km s^(–1). We reproduce this measurement, but demonstrate that it is inflated by unresolved binary stars. For our sample of 61 stars, the velocity dispersion is σ = 0.7^(+0.6)_(–0.5) km s^(–1). Combining our DEIMOS data with literature values, our final velocity dispersion is σ = 0.4^(+0.4)_( –0.3) km s^(–1). We determine a spectroscopic metallicity of [Fe/H] = –1.6 ± 0.1 dex, placing a 1σ upper limit of σ_([Fe/H]) ~ 0.2 dex on any internal metallicity spread. We determine Palomar 13's total luminosity to be M_V = –2.8 ± 0.4, making it among the least luminous known globular clusters. The photometric isophotes are regular out to the half-light radius and mildly irregular outside this radius. The outer surface brightness profile slope is shallower than typical globular clusters (Σ α r^η, η = –2.8 ± 0.3). Thus at large radius, tidal debris is likely affecting the appearance of Palomar 13. Combining our luminosity with the intrinsic velocity dispersion, we find a dynamical mass of M_(1/2) = 1.3^(+2:7)_(–1.3) × 10^3 M_☉ and a mass-to-light ratio of M/L_V = 2.4^(+5.0)_(–2.4) M_☉/L_☉. Within our measurement errors, the mass-to-light ratio agrees with the theoretical predictions for a single stellar population. We conclude that, while there is some evidence for tidal stripping at large radius, the dynamical mass of Palomar 13 is consistent with its stellar mass and neither significant dark matter, nor extreme tidal heating, is required to explain the cluster dynamics

Fundamentos, relações e implicações dos Embargos de Declaração prequestionadores no novo Código de Processo Civil

Esta dissertação trata dos embargos de declaração e da sua utilização, no direito brasileiro, como forma de fazer aflorar o requisito de prequestionamento das matérias constitucional ou infraconstitucional inerente, segundo entendimento jurisprudencial (acórdãos e Súmulas 282 e 356 do STF e 211 do STJ) e doutrinário, à interposição de recurso extraordinário ao STF ou de recurso especial ao STJ. A partir da ideia de justiça por meio do processo, busca-se a compreensão conceitual básica dos recursos, discorre-se sobre os embargos de declaração e sobre os recursos extraordinário e especial, tendo o prequestionamento como fio condutor do que se expõe. Após algumas breves considerações sobre a origem e o papel de cada um dos recursos supracitados e sobre o entendimento doutrinário e jurisprudencial acerca do prequestionamento, busca-se analisar a inteligência acerca dos embargos de declaração como elementos aptos a consubstanciar esse requisito, mormente a posição esposada pelo STF e pelo STJ diante da omissão do juízo a quo em analisar o ponto suscitado pela parte embargante. Vistos esses pontos, o próximo passo foi verificar a disciplina dos embargos de declaração no texto do projeto do novo Código de Processo Civil, já aprovado pelo Senado da República e em tramitação na Câmara dos Deputados. Nesse ponto, o que importa é verificar o que o novo Código traz a lume, principalmente no que tange ao artigo 979, que vem positivar o chamado prequestionamento ficto, e ao espírito que permeia a Exposição de Motivos do novo CPC, levando-se em conta seus principais objetivos. A seguir, buscou-se verificar a relação entre o artigo 979 e as duas mais importantes concepções metodológicas de processo civil no Brasil contemporâneo: o instrumentalismo e o formalismo-valorativo. Depois disso, o objetivo foi verificar as dimensões ontológica, deontológica, axiológica, principiológica e constitucional do prequestionamento ficto, levandose em consideração sua positivação no novo CPC, no artigo 979, e as implicações dessa positivação. Finalmente, chega-se à conclusão de que não haverá mais procedência a Súmula 211 do STJ, louvando-se a iniciativa de o legislador pôr fim, a uma dissensão entre o STF e o STJ que já durava anos e parecia interminável, garantindo, dessa forma, o conhecimento dos recursos extraordinário e especial e, consequentemente, justiça, segurança jurídica e efetividade do processo

Noncommutative Thermofield Dynamics

The real-time operator formalism for thermal quantum field theories, thermofield dynamics, is formulated in terms of a path-integral approach in non-commutative spaces. As an application, the two-point function for a thermal non-commutative $\lambda \phi^4$ theory is derived at the one-loop level. The effect of temperature and the non-commutative parameter, competing with one another, is analyzed.Comment: 13 pages; to be published in IJMP-A

Integrating The Five Practices of Exemplary Leadership Model into Entrepreneurship Education

Entrepreneurship educators can assess their students by focusing on leadership self-efficacy dimensions that align with desirable entrepreneurship behaviors. To support this claim, we used the Student Leadership Practices Inventory (S-LPI) to survey a group of 46 undergraduate students in Mexico and 49 undergraduate students in Spain that were involved in entrepreneurship education programs. Independent samples t-tests show statistically significant differences between the two groups. We also compared the whole sample in terms of gender and found no differences. We propose that educators integrate Five Practices of Exemplary Leadership model into de design and assessment of their curricular and co-curricular entrepreneurship development programs. Specifically, the model serves educators from different countries, in this case Mexico and Spain, by identifying the leadership behaviors that their students enact. By integrating the five practices of exemplary leadership model, educators can account for variables like nation of origin and gender, and identify differences between groups

Determination of the liquid pool surfactant and protein concentration for semi-batch foam fractionation columns

A model is derived for the change with time of the concentration of a surface-active component in the liquid pool of a semi-batch foam fractionation process. The transport of surface-active material to the gas-liquid interface was assumed to be limited by the mass transfer rates, and the concentration of the adsorbed material at the interface was assumed to be in equilibrium with the concentration of liquid adjacent to the bubble gas surface. This model was compared to experimental data obtained for semi-batch foam fractionation of aqueous solutions of bovine serum albumin and cetyltrimetylammonium bromide.114Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Oxygen transfer in the solid-state cultivation of D. Monoceras on polyurethane foam as an inert support

In recent years, there has been a resurgence of interest concerning solid-state cultivation processes due to a number of advantages over submerged cultivation. However, studies on oxygen transfer and the performance of bioreactors are lacking. Processes that use inert supports loaded with chemically-defined liquid media have several potential applications and offer numerous advantages, such as improved process control and monitoring and enhanced process consistency compared with cultivation on natural solid substrates. The aim of this research was to study the oxygen transfer for the production of allergenic proteins from a biomass of Drechslera (Helminthosporium) monoceras cultured in a packed-bed reactor filled with polyurethane foam. The results show that a high protein concentration can be produced on an inert support with a high overall oxygen transfer coefficient (KLa) during cultivation334793799CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESsem informaçã