Lifetime study of high-spin states in 104,105In

In the neutron deficient isotopes _104,105In lifetimes of high spin states in the range from 0.5 ps to 600 ps have been measured in a coincidence recoil distance Doppler shift (RDDS) experiment. By combining the Doppler shift attenuation (DSA) and RDDS methods at few μm flight distances, the problem of delayed feeding has been avoided and very short lifetimes in the range 0.5–0.8 ps have been determined. Shell model calculations with strong restrictions for the neutron orbitals reveal good agreement with experimental level energies and still fair agreement for most measured B(M1) and B(E2) values. Received: 30 June 1998     

On the retrograde condensation of one or two liquids

This contribution discusses the phenomena of retrograde condensation of one or two liquids. It w1 be shown that both phenomena can be well understood. Also the relation of retrograde condensation of one liquid phase with the condensation behavior of natural gas will be discussed. Similarly that of two liquid phases with multiple phase behavior occurring in low temperature reservoir fluids will be pointed out.     

On the behaviour of rubberlike materials in compression and shear

Summary The mechanical behaviour of rubberlike materials is modelled in a phenomenological approach using a strain-energy formulation. Nonhomogeneous shear experiments on solid rubber specimens have been carried out as well as simple elongation tests on the same rubber compound. The elongation tests have been used to determine the model constants. By a comparison between experiment and numerical simulation of the nonhomogeneous shear test the predictive capabilities of the Mooney-Rivlin, the Ogden and the Besseling model have been assessed for compression-shear deformation paths. An analytical study explains the numerically observed behaviour.

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Über das Verhalten von Gummimaterialien unter Druck und Schubverformungen

Übersicht Das mechanische Verhalten von Gummimaterialien wird phänomenologisch modelliert unter Anwendung einer Formänderungsenergiefunktion. Es sind nicht-homogene Schubversuche auf dreidimensionale Versuchsproben aus Gummi so wie auch einfache Verlängerungsversuche auf Gummiproben der gleichen Zusammenstellung durchgeführt worden. Die Verlängerungsversuche sind durchgeführt worden um die Stoffkennwerte feststellen zu können. In einer Vergleichung zwischen dem Experiment und der numerischen Simulation von nicht-homogenen Schubversuchen ist die Genauigkeit des Mooney-Rivlinschen Modells, des Ogdenschen Modells und des Besselingschen Modells für kombinierte Druck-Schubverformungen festgestellt worden. In einem analytischen Studium wird das numerisch betrachtete Verhalten auseinandergesetzt.

     

Scaling probability, key to the equilibrium statistical volume distribution in foams

The equilibrium statistical volume distribution in foams, which has been previously demonstrated to be the so-called log-normal, is accounted on probability grounds by a scaling law on the bubble's volume time-evolution. This law states that the conditional probability for a given bubble to have the volume v(t + Δt), he assumption that it was v(t), to depend solely on the relationship v(t + Δt)/v(t), and in particular, to be independent of the time t. The theoretical results, however, allow to go further. Indeed, since the time dependece of its parameters (expectation and variance) are given functions of time, only two parameters are necessary to describe completely the foam.     

Thermal and chemical nanofractal relaxation

We studied shape relaxation of nano-fractal islands, during annealing, after their growth from antimony cluster deposition on graphite surface. Annealing at 180^°C shows evidence of an increase of the fractal branch width with time followed by branch fragmentation, without changing the fractal dimension. The time evolution of the width of the arm suggests the surface self-diffusion mechanism as the main relaxation process. With Monte Carlo simulations, we confirmed the observed behavior. Comparison is done with our previous results on fragmentation of nano-fractal silver islands when impurity added to the incident cluster promotes rapid fragmentation by surface self-diffusion enhancement [1].     

Gas solubility of carbon dioxide in poly(lactic acid) at high pressures: Thermal treatment effect

The sorption of carbon dioxide in glassy Poly(lactic acid) (PLA) films was studied by quartz crystal microbalance (QCM) at high pressures. Two thermal treatments, melted and quenched, were performed in PLA with two different L:D contents, 80:20 and 98:2, films and compared with a third thermal protocol, annealed, and used in a previous work. The results obtained show that for pressures higher than 2 MPa, the carbon dioxide solubility is larger in PLA 80:20 than in PLA 98:2, indicating that the L:D plays a dominant role on this property. The thermal treatments only affect the gas solubility in PLA 98:2. Sorption isotherms at temperatures 303, 313, and 323 K, below the glass transition temperature of the polymer, and pressures up to 5 MPa were measured and analyzed with three different models, the dual‐mode sorption model, the Flory–Huggins equation, and a modified dual‐mode sorption model where the Henry's law term was substituted by the Flory–Huggins equation. This last model performs especially well for CO₂ in PLA 80:20, due to the convex upward curvature of the solubility isotherms for that system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 616–625, 2007