Classical solutions of some ℂP 1-like models

We present solutions to the classical equations of motion of a class of P ¹-like models. We calculate their action and study their stability properties.     

Monte-Carlo study of a model for the roughening transition of high-index crystal faces

A simple terrace-step-kink model is studied using Monte-Carlo techniques. In the nearly isotropic case where the energy to form a kink within a step,W ₀, is equal to the energy to shift a step by one interatomic spacing,w _n, the roughening transition is determined numerically in accordance with the Kosterlitz-Thouless theory. In the anisotropic case,w _nW ₀, results can be related to atomic beam-diffraction experiments on Cu(1,1,3). Additional evidence for a roughening transition of that face is given; the transition, however, seems to occur at a temperature somewhat higher than has been previously anticipated.     

Effective moment of inertia in132Ce,134Nd and136Nd

The effective moment of inertiaI _eff ⁽²⁾ of¹³²Ce,¹³⁴Nd and¹³⁶Nd produced in⁴⁰Ar induced reactions has been deduced from continuumγ-ray spectra measured by sum spectrometer methods. Results concerning the deformation of these nuclei are obtained by comparison of the experimental data and calculations in the frame of a cranking Nilsson — Strutinsky model.     

Influence of a continuous quenching procedure on the initial stages of spinodal decomposition

Instead of the standard assumption in the theory of phase separation where an instantaneous quench from an initial equilibrium state to the final state in the two-phase region is assumed, we consider the more realistic situation that the change of the external control parameter (e.g. temperature) can only be performed with finite rates. During the initial stages of spinodal decomposition the system then has some memory of the states intermediate between the initial and the final one. This influence of the finite quench rate in continuous quenching procedures is studied within the linearized theory of spinodal decomposition, with the Langer-Baron-Miller decoupling, and with Monte Carlo simulations. Both the case of thermally activated mobilities (applicable to solid metallic alloys) and the case of nearly temperature-independent mobilities (applicable to fluid polymer mixtures) are treated, and possible experimental applications are discussed. We find drastic deviations from the standard instantaneous quench situations in all cases of experimental interest.     

Two-photon four-level hologram recording in poly-(alkyl-α-cyanoacrylates)

We have investigated the suitability of poly-(alkyl--cyanoacrylates) (p-(alkyl-CAc)) for two-photon four-level holographic recording. It is shown that these materials follow indeed a two-photon four-level mechanism with the second absorption step in the near infrared. Light induces the polymerization of residual monomer in the matrix. The reaction is associated with positive density changes. The sensitivity ofp-(alkyl-CAc) depends strongly on composition and age of the sample. Maximum sensitivities achieved are comparable to the so far best-known two-photon four-level ir-sensitive systems.     

INAA determination of major and trace elements in loess,paleosol and precipitation layers in a pleistocene Loess Section,China

Instrumental neutron activation analysis was used for the determination of 31 major and trace elements in 32 samples from the Xinji Loess Section, Shaanxi Province, China. Interferences, including those from uranium fission products, were evaluated and corrections applied where necessary. The 39.7-meter deep section comprises of Lishi Loess of the middle Pleistocene (Q₂) and Malan Loess of the late Pleistocene (Q₃). The section is characterized by the presence of 5 layers of paleosol, and each paleosol is underlain by a precipitation layer. When the elemental abundances are converted to a carbonate-free basis, there is little compositional difference among the carbonate-free fractions of loess, paleosol and precipitation layers. This indicates that dissolution of carbonate minerals by downward-moving surface water was an important process in paleosol formation while other minerals were not severely weathered and elemental fractionation was minimal. The parent materials of the paleosol and precipitation layers closely resemble the loess layers in their elemental abundances, which suggests that all layers in the section have a compositionally similar source.     

2.6 Foods

Abstracts2 Particular products and fields of application

2.6 Foods     

An electrochemical investigation on (MoO<Subscript>3</Subscript>+PVP+PVA) nanobelts for lithium batteries

Molybdenum trioxide (MoO₃) xerogel films modified with poly(vinyl alcohol)+poly(vinyl pyrrolidone) (PVP+PVA) polyblends were obtained by ion-exchange method with sol-gel technique. Investigations were conducted using X-ray “diffractometry”, Fourier transform infrared spectroscopy, and cyclic voltammetry. The results show that the H atoms in polyblend are H-bonded with the O atoms in the Mo=O bonds of MoO₃ xerogel, which effectively shield the electrostatic interaction between MoO₃ interlayer and Li⁺ ions when MoO₃ xerogel is modified by the intercalation of (PVP+PVA). The reversibility of the insertion/extraction of Li⁺ ions is greatly improved by the modification with polyblend of MoO₃ nanocomposite films. MoO₃ and (PVP+PVA) _x MoO₃ (x = 0, 0.5) nanobelts were obtained by a simple hydrothermal process from MoO₃ sol. The electrochemical cells with configuration Li/(LiPF₆+EC+DMC)/MoO₃ modified by (PVP+PVA) were fabricated and their discharge profiles studied.     

Nonexponential Fluorescence Decay of 7-Azatryptophan Induced in a Peptide Environment

7-Azatryptophan is an alternative to tryptophan as an optical probe of protein structure and dynamics. 7-Azatryptophan is synthetically incorporated into an octapeptide (NAc-Lys-Ala-Cys-Pro-7-azatryptophan-Asn-Cys-Asp-NH₂) that mimics the active site of potato chymotrypsin inhibitor II, which is known to be a strong inhibitor of α-chymotrypsin. The synthetic octapeptide retains some of this inhibitory activity. This is the first compound containing the 7-azaindole chromophore to display a nonexponential fluorescence decay (well fit to two exponentials) in water when fluorescence is collected over the entire emission band. The effect of external quenchers on the fluorescence decay is monitored and seen to differ markedly for the two components. These results are discussed in terms of the solvation of the 7-azaindole chromophore itself, which promotes or impedes excited-state tautomerization. The fluorescence quenching of free indole and 7-azaindole are compared. The fluorescence quenching of octapeptides containing both chromophores is also compared. It is the thesis of this article that the nonexponential fluorescence decay of the 7-azatryptophan-containing octapeptide is a consequence of excited-state tautomerization of the 7-azaindole chromophore. This tautomerization is suggested to be promoted by solvent reorganization induced by the peptide backbone or by direct interactions of the 7-azaindole with neighboring amino acid side chains.