Comparison of the effect of processing parameters and degradation on the DC and microwave properties of thin films and polycrystalline bulk high-Tc superconducting materials

The sharp increase in microwave power loss (the reverse of what has previously been reported) at the transition temperature in high-Tc superconducting systems such as YBaCu oxide (polycrystalline bulk and thin films obtained by the laser ablation technique) and BiPbSrCaCu oxide is reported. The differences between DC resistivity ( rho ) and the microwave power loss (related to microwave surface resistance) are analysed from the data obtained by a simultaneous measurement set-up. The influence of various parameters, such as preparation conditions, thickness and aging of the sample and the probing frequency (6-18 GHz), on the variation of microwave power loss with temperature is outlined.

Phase relations in the systems Cu–O–R2O3(R = Tm, Lu) and Gibbs energies of formation of Cu2R2O5 compounds

The phase relations in the systems Cu–O–R2O3(R = Tm, Lu) have been determined at 1273 K by X-ray diffraction, optical microscopy and electron probe microanalysis of samples equilibrated in evacuated quartz ampules and in pure oxygen. Only ternary compounds of the type Cu2R2O5 were found to be stable. The standard Gibbs energies of formation of the compounds have been measured using solid-state galvanic cells of the type, Pt|Cu2O + Cu2R2O5+ R2O3‖(Y2O3)ZrO2‖CuO + Cu2O‖Pt in the temperature range 950–1325 K. The standard Gibbs energy changes associated with the formation of Cu2R2O5 compounds from their binary component oxides are: 2CuO(s)+ Tm2O3(s)→Cu2Tm2O5(s), ΔG°=(10400 – 14.0 T/K)± 100 J mol–1, 2CuO(s)+ Lu2O3(s)→Cu2Lu2O5(s), ΔG°=(10210 – 14.4 T/K)± 100 J mol–1 Since the formation is endothermic, the compounds become thermodynamically unstable with respect to component oxides at low temperatures, Cu2Tm2O5 below 743 K and Cu2Lu2O5 below 709 K. When the chemical potential of oxygen over the Cu2R2O5 compounds is lowered, they decompose according to the reaction, 2Cu2R2O5(s)→2R2O3(s)+ 2Cu2O(s)+ O2(g) The equilibrium oxygen potential corresponding to this reaction is obtained from the emf. Oxygen potential diagrams for the Cu–O–R2O3 systems at 1273 K are presented.

Synthesis of Cuprates of Perovskite Structure in the Ba-Pb-Cu-O, Ba-Bi-Cu-O, and Ba-Pb-Tl-Cu-O Systems: Possible High Tc Superconductivity in a Perovskite-like Phase in the Ba-Pb-Tl-Cu-O System

Cubic cuprates (a not, vert, similar 18.6 Å) with a BaCuO2-type structure were obtained in the Ba-Pb-Cu-O and Ba-Bi-Cu-O systems by the reaction of the component oxides at a high temperature (1370-1420 K), followed by quenching. By annealing these phases in oxygen at 1070-1120 K, perovskite-like phase (a not, vert, similar 4.3 Å) of the formulae BaPb1-xCuxO3-y and BaBi1-xCuxO3-y (0 < x ? 0.5) were obtained. A perovskite of nominal composition BaPb0.25Tl0.25 Cu0.5O3-y, prepared by a similar procedure, was found to be superconducting with a Tc of not, vert, similar 70 K.

Normal state tunneling conductance of perovskite oxides: Implications for high-Tc superconductors

We have investigated tunneling conductances in disordered, normally conducting perovskite oxides close to the metal�insulator transition. We show that the normal state tunneling conductance of perovskite oxides can be cast in a general form G(V) = G0[1 + curly logical orV/V*curly logical orn] with 1?n?0.5 and where V* is an intrinsic energy scale. The exponent n graduall y increases from 0.5 to 1 as the metal-insulator (M-I) transition is approached. In the high-Tc Bi(2212) cuprates, the normally observed, linear G(V)(n=1) can be made sub-linear (n<1) by substitution of Ca with Y. From the similarity of the linear conductances, we suggest proximity to the M-I transition as a likely cause for this G(V)logical or, bar below V dependence. In systems showing linear conductances (nreverse similar, equals1), we find that ?G/?Vreverse similar, equalsG?0 with ?reverse similar, equals 1 and the intrinsic energy scale V*reverse similar, equals25�75 meV in the different oxides investigated.

Phenomenological aspects of phase fluctuation in high Tc superconductors: Cooper pair droplets

We point out how fluctuation of the phase of the superconducting order parameter can play a key role in our understanding of high Te superconductors. A simple universal criterion is given which illustrates why all oxide superconductors in contrast to classical superconductors ought to behave as a lattice of cooper pairs. T-c is to be thought of as the temperature of phase coherence or the temperature above which the lattice of Cooperpair 'melts' into a phase of Cooper-pair droplets that starts forming at T approximate to T-* . This is the pseudo-gap region. Quantum fluctuation of the phase predicts a superconductor to insulator phase transition for all underdoped materials.

Decomposition temperatures of Cu2Ln2O5 (Ln = Tb, Dy, Ho, Er, Tm, Yb, and Lu) compounds

The equilibrium decomposition temperatures of Cu2Ln2O5 (Ln = Tb, Dy, Ho, Er, Tm, Yb, and Lu) compounds have been measured using a combined DTA-TGA apparatus under a flowing Ar + O2 gas mixture, in which the partial pressure of oxygen was controlled at 5.0 × 103 Pa. The Cu2Ln2O5 compounds yield Ln2O3 and Cu2O on decomposition. The decomposition temperature increases monotonically with the atomic number of the lanthanide element. This suggests that the stability of the Cu2Ln2O5 compounds with respect to the component binary oxides increases with decreasing radius of the Ln3+ ion.

Thermodynamics of TmRhO3, Phase Equilibria, and Chemical Potentials in the System Tm-Rh-O

Phase equilibria in the system Tm-Rh-O at 1200 K is established by isothermal equilibration of selected compositions and phase identification after quenching to room temperature. Six intermetallic phases (Tm3Rh, Tm7Rh3, Tm5Rh3, Tm3Rh2, TmRh, TmRh2 +/-delta) and a ternary oxide TmRhO3 are identified. Based on experimentally determined phase relations, a solid-state electrochemical cell is devised to measure the standard free energy of formation of orthorhombic perovskite TmRhO3 from cubic Tm2O3 and beta-Rh2O3 in the temperature range from (900 to 1300) K. The results can be summarized as: Delta G(f,ox)(o) +/- 104/J.mol(-1) = -46474 + 3.925(T/K). Invoking the Neumann-Kopp rule, the standard enthalpy of formation of TmRhO3 from its constituent elements at 298.15 K is estimated as -1193.89 (+/- 2.86) kJ.mol(-1). The standard entropy of TmRhO3 at 298.15 K is evaluated as 103.8 (+/- 1.6) J.mol(-1).K-1. The oxygen potential-composition diagram and three-dimensional chemical potential diagram at 1200 K and temperature-composition diagrams at constant partial pressures of oxygen are computed from thermodynamic data. The compound TmRhO3 decomposes at 1688 (+/- 2) K in pure oxygen and at 1583 (+/- 2) K in air at standard pressure.

Real-time magnetic resonance imaging and electromagnetic articulography database for speech production research (TC)

USC-TIMIT is an extensive database of multimodal speech production data, developed to complement existing resources available to the speech research community and with the intention of being continuously refined and augmented. The database currently includes real-time magnetic resonance imaging data from five male and five female speakers of American English. Electromagnetic articulography data have also been presently collected from four of these speakers. The two modalities were recorded in two independent sessions while the subjects produced the same 460 sentence corpus used previously in the MOCHA-TIMIT database. In both cases the audio signal was recorded and synchronized with the articulatory data. The database and companion software are freely available to the research community. (C) 2014 Acoustical Society of America.

Funcionamento dos guardas municipais nas principais capitais do país, considerando : a. se atuam com poder de polícia; b. se substituem a polícia militar na falta de efetivo desta instituição; c. se auxiliam a polícia militar no combate ao crime; d. se têm porte de arma; e e. se contribuem para a segurança pública

Consultoria Legislativa - Área XVII - Segurança Pública e Defesa Nacional.

Manifestação solicitada pelo TCU à CONOF/CD acerca de relatório preliminar, relativo à consulta sobre a aplicação da Lei Complementar nº 141, de 2012, formulada pela Comissão de Seguridade Social e Família/CD : TC 046.061/2012‐6

Avalia o relatório elaborado pelo TCU acerca da consulta formulada pela CSSF/CD(TC 046.061/2012‐6). Procura a pacificação de entendimento no âmbito do Congresso Nacional.

Quando as mulheres têm voz: um estudo sobre raça, gênero e cidadania

A presente tese analisa as representações atuais nos discursos de mulheres negras das camadas pobres urbanas do Rio de Janeiro, assim como suas relações sociais entre o gênero masculino e feminino na atualidade. Focaliza esta discussão de gênero, em torno de temas como: família, relações de trabalho, participação social, emancipação da mulher e direitos. A partir de pesquisa empírica de histórias de vida buscamos analisar, comparativamente, as expectativas, os estereótipos, os problemas e as conquistas das mulheres de diferentes gerações. Verifica o que elas relatam ter mudado ou que permaneceu imutável na relação entre mulheres e homens: diferenças e semelhanças, conflitos e contradições e os seus anseios sociais presentes nas suas histórias e memória. Busca compreender como as mulheres negras estão lidando com as rápidas mudanças que afetam os papéis de gênero, analisando como se dá a convivência entre arquétipos considerados tradicionais e os modernos modelos de masculinidade e feminilidade. Destas diferenças trata esta tese. Especificamente, das relações sociais da mulher negra na religião, no trabalho, na família e na política, espaços que delimitado e que nos propomos debater. Quando as mulheres têm voz? É uma provocação para refletir sobre o tema a partir da memória de três mulheres nascidas entre a década de vinte e trinta que conquistaram espaços expressivos apesar das dificuldades postas às mulheres desta época. Á nossa pergunta é atribuído um significado de poder de participação e expressão que dialoga com mulheres no anonimato sem voz, que estão trabalhando para garantir a sobrevivência, são moradoras das periferias ou morros, estudantes de escolas públicas e mulheres donas-de-casa, mas que querem ter voz. A temática da mulher negra nos remete ao artifício da colonização, ao processo de dominação e sujeição, à memória de culto, a deuses, aos antepassados, à cultura, à história de vencedores e vencidos. As histórias das mulheres negras trazem em si a extensão da colonização. A memória individual existe sempre a partir de uma memória coletiva e a origem de várias idéias, reflexões, sentimentos e paixões que atribuímos a nós são, na verdade, inspiradas pelo grupo.