Identification of reconstruction in Pt films deposited on Pd(110) at room temperature

We have studied the properties of Pt films on Pd(110), grown by deposition at 300 K and annealed up to 900 K, using low-energy electron diffraction and Auger-electron spectroscopy. We observe (1×2) and (1×3) superstructures, depending upon Pt coverage and annealing temperature. At one monolayer, the (1×1) periodicity is unperturbed. Between one and three monolayers, a broad and streaky (1×2) develops upon annealing, then fades to (1×1) as the film dissolves. At three monolayers and above, the broad and streaky (1×2) splits to a (1×3), then fades again to (1×1) at high temperature. Adsorption of CO causes (1×3)→(1×1) reversion at relatively low temperature, 430 K. Based upon the known behavior of Pt(110) reconstructions, this is strong evidence that the (1×3) structure of the Pt film is a surface reconstruction

Comportamento fisiológico da cultura da soja em terras baixas.

Dissertação (Mestrado em Fisiologia Vegetal) ? Programa de Pós-Graduação em Fisiologia Vegetal, Instituto de Biologia, Universidade Federal de Pelotas, Pelotas. Orientador: Dr. Sidnei Deuner; Coorientador: Dr. Germani Concenço

The effect of different types of hepatic injury on the estrogen and androgen receptor activity of liver

Mammalian liver contains receptors for both estrogens and androgens. Hepatic regeneration after partial hepatectomy in male rats is associated with a loss of certain male-specific hepatic characteristics. In this study we investigated the effects of lesser forms of hepatic injury on the levels of estrogen and androgen receptor activity in the liver. Adult male rats were subjected to portacaval shunt, partial portal vein ligation, hepatic artery ligation, or two-thirds partial hepatectomy. Another group of animals was treated with cyclosporine. At the time of sacrifice the livers were removed and used to determine the estrogen and androgen receptor activity in the hepatic cytosol. A significant reduction (p < 0.05) in the hepatic cytosolic androgen receptor activity and a slight increase in the estrogen receptor activity occurred following total portosystemic shunting. Partial ligation of the portal vein, which produces a lesser degree of portosystemic shunting, had no effect on the levels of the estrogen and androgen receptor activity present within hepatic cytosol. Cyclosporine-treated animals had significantly greater (p < 0.01) levels of estrogen receptor activity in the hepatic cytosol compared to vehicle-treated control animals. Levels of estrogen and androgen receptor activity within the hepatic cytosol remained unchanged after ligation of the hepatic artery. The reduction in the cytosolic estrogen and androgen receptor activity in the liver after partial hepatectomy was confirmed. In summary, certain types of hepatic injury are associated with profound changes in the estrogen and androgen receptor content within the liver. © 1989 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

Geometric and dynamic perspectives on phase-coherent and noncoherent chaos

Statistically distinguishing between phase-coherent and noncoherent chaotic dynamics from time series is a contemporary problem in nonlinear sciences. In this work, we propose different measures based on recurrence properties of recorded trajectories, which characterize the underlying systems from both geometric and dynamic viewpoints. The potentials of the individual measures for discriminating phase-coherent and noncoherent chaotic oscillations are discussed. A detailed numerical analysis is performed for the chaotic R\"ossler system, which displays both types of chaos as one control parameter is varied, and the Mackey-Glass system as an example of a time-delay system with noncoherent chaos. Our results demonstrate that especially geometric measures from recurrence network analysis are well suited for tracing transitions between spiral- and screw-type chaos, a common route from phase-coherent to noncoherent chaos also found in other nonlinear oscillators. A detailed explanation of the observed behavior in terms of attractor geometry is given.Comment: 12 pages, 13 figure

Coleção de culturas de microrganismos multifuncionais de clima temperado: manutenção, recuperação e viabilidade de fungos preservados em solo.

Resumo:228-1