Fine-silt luminescence dating and mineral composition of sediments from the Arctic Ocean

New geochronometers are needed for sediments of the Arctic Ocean spanning at least the last half million years, largely because oxygen-isotope stratigraphy is relatively ineffective in this ocean, and because other dating techniques require significant assumptions about sedimentation rates. Multi-aliquot luminescence sediment-dating procedures were applied to polymineral, fine-silt samples from 9 core-top and 37 deeper samples from 20 cores representing 19 sites across the Arctic Ocean. Most samples have independent age assignments and other known properties (e.g., % coarse fraction, % carbonate, U-Th isotopes). Thick-source alpha-particle counting indicates that for most regions the contribution of measured unsupported 230Th and 231Pa to calculated dose rates is

Microstructural characterization of rapidly solidified and heat-treated Ti(92)B(8) eutectic alloy

In this work, Ti(92)B(8) alloy was processed via rapid solidification (splat-cooling) and then heat-treated at 700 degrees C and 1000 degrees C. A careful microstructural characterization indicated that, after rapid solidification, a very fine two-phase microstructure was produced with no significant saturation of B in alpha/beta Ti. There was no indication of amorphous formation in the rapidly solidified splats. Both alpha Ti and TiB were observed in the microstructures of the splats after heat-treatment at 700 degrees C and 1000 degrees C, confirming the stability of the alpha Ti+TiB two-phase region in this temperature range. (C) 2008 Elsevier Inc. All rights reserved.

Investigation of electrical conductivity as a function of dopant-ion radius in the systems Zr0.75Ce0.08M0.17O1.92 (M=Nd, Sm, Gd, Dy, Ho, Y, Er, Yb, Sc)

Electrical conductivity versus dopant ionic radius studies in zirconia- and ceria-based, solid oxide fuel cell (SOFC) electrolyte systems have shown that oxygen-ion conductivity is highest when the host and dopant ions are similar in size [J. Am. Ceram. Soc. 48 (1965) 286; Solid State Ionics 37 (1989) 67; Solid State Ionics 5 (1981) 547]. Under these conditions, it is thought that the conduction paths within the crystal lattice become less distorted [Solid State Ionics 8 (1983) 201]. In this study, binary ZrO2-M2O3 unit cells were expanded, via the partial substitution of Ce+4 for Zr+4 into the lattice, in an attempt to identify new, ternary, zirconia/ceria-based electrolyte systems with enhanced electrical conductivity. The compositions Zr0.75Ce0.08M0.17O1.92 (M = Nd, Sm, Gd, Dy, Ho, Y, Yb, Sc) were prepared using traditional solid state techniques. Bulk phase characterisation and precise lattice parameter measurements were performed with X-ray diffraction techniques. Four-probe DC conductivity measurements between 400 and 900 degreesC showed that the dopant-ion radius influenced electrical conductivity. The conductivity versus dopant-ion radius trends previously observed in zirconia-based, binary systems are clearly apparent in the ternary systems investigated in this study. The addition of ceria was found to have a negative influence on the electrical conductivity over the temperature range 400-900 degreesC. It is suggested that distortion of the oxygen-ion conduction path by the presence of the larger M+3 and Ce+4 species (relative to Zr+4) is the reason for the decreasing electrical conductivity as a function of increasing dopant size and ceria addition, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.

Conductivity/microstructure study of a pyrochlore-type ordered phase in the compound Zr0.75Ce0.08Nd0.17O1.92

The compound Zr0.75Ce0.08Nd0.17O1.92 was investigated as part of a much larger electrical conductivity/microstructure study of the systems ZrO2-CeO2-M2O3 (where M=Nd, Sm, ..., Yb) [Solid State Ionics (2002)]. Electrical conductivity measurements performed in air at 800 degreesC showed significant conductivity degradation over a period of 200 h. Investigation of the annealed and as-fired specimens by ATEM revealed the presence of an emerging, ordered pyrochlore-type phase within the Zr0.75Ce0.08Nd0.17O1.92 defect-fluorite solid solution at much lower dopant levels than observed previously for zirconia binary systems. (C) 2002 Elsevier Science B.V. All rights reserved.

Avaliação da proteção conferida pela vacina antimeningocócica BC no Estado de Santa Catarina, Brazil, 1990/92

São apresentados os resultados da avaliação da vacina antimeningocócica BC de procedência cubana realizada com dados da vigilância epidemiológica de meningites do Estado de Santa Catarina, Brasil, dos anos de 1990-92. A eficácia para os casos confirmados por exames bacteriológicos foi de 59% (IC de 95%: 23 a 78%) para os menores de 4 anos e de 78% (IC de 95%: 54 a 90%) para as crianças de 4 a 7 anos. Com os casos confirmados como causados por sorogrupo B, as eficácias estimadas foram maiores, mas se ampliaram os intervalos de confiança. O efeito protetor da vacina em relação à mortalidade em crianças menores de 4 anos foi estimado em 76% (IC 95%: 41 a 91%). Outros dados apresentados sugerem que as mais baixas eficácias encontradas, quando se analisam os menores de 4 anos, decorrem da seletividade da confirmação diagnóstica que exclui os casos mais graves que morrem a poucas horas do início dos sintomas, associada à modificação do curso da doença (atenuação) em vacinados. Por isso, indica-se a vacinação, inclusive em menores de 4 anos, nas situações epidêmicas.

Ostracoda, bearbeitet von G. W. Müller ... Mit 92 abbildungen.

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La Història del projecte olímpic: [Barcelona'92]

Classe impartida per l'historiador Alfred Bosch sobre l'evolució de la candidatura de Barcelona'92 i del Comitè Organitzador en el curs universitari sobre Olimpisme organitzat pel CEO-UAB al febrer de 1992.

La Historia del proyecto olímpico: [Barcelona 92']

Clase impartida por el historiador Alfred Bosch sobre la evolución de la candidatura de Barcelona'92 y del Comité Organizador de los Juegos en el curso universitario sobre Olimpismo organizado por el CEO-UAB en febrero de 1992.

Operacions de premsa: [Barcelona'92]

Classe impartida pel director de la Divisió d'Operacions de Premsa del COOB'92 en el curs universitari sobre Olimpisme organitzat pel CEO-UAB al febrer de 1992 sobre la planificació de les operacions de premsa per als Jocs Olímpics de Barcelona'92.