Thermal decomposition of ammonium monochloroacetate and ammonium monochloroacetate silicomolybdate

Journal of Thermal Analysis and Calorimetry - Les anomalies que nous avons observées, dans le cas de l'oxydation de fils de nickel, peuvent s'interpréter en faisant appel à...     

Investigation of the 40Ar + 197Au, 238U systems at 44 MeV/u

We have measured the angular correlation between two fragments emitted in the reactions Ar + Au and Ar + U at 44 MeV/u at GANIL. The aim was to investigate the amount of initial linear momentum transferred from the projectile to a fissioning nucleus. It turned out that this amount is much smaller than can be extrapolated from previous experiments. Furthermore, the probability of forming a fissioning nucleus is very small.     

Dependence of the steepness of the exponential absorption tail on the chemical composition of materials

The quantity characterizing the steepness of the exponential tail of the fundamental absorption edge is studied. It is shown, that the magnitude of of binary compounds can be roughly estimated from their chemical composition in a way described in this paper.Boní II, Praha 4, Czechoslovakia.The author thanks Ing. D. Leal, CSc for his valuable discussions concerning this work.     

The non-isothermal rheological behaviour of molten polymers: Shear and elongational stress growth of polyisobutylene under heating

Summary Data of stress growth under both shear and elongational kinematics have been taken in presence of heating temperature ramps on a commerical polyisobutylene.The experimental results have been analysed on the basis of a generalized Maxwell model already proved to be very accurate in predicting the isothermal behaviour. A good agreement is observed between the theoretical predictions and the experimental results.Also the features usually observed in volume-temperature curves by effect of cooling acrossT _g are qualitatively reproduced by the model.With 6 figures     

Monitoring Alfvén cascades with interferometry on the JET Tokamak

A microwave interferometry technique is applied for the first time for detecting a discrete spectrum of Alfvén cascade (AC) eigenmodes excited with fast ions in reversed magnetic shear plasmas of the Joint European Torus. The interferometry measurements of plasma density perturbations associated with ACs show an unprecedented frequency and time resolution superior to that obtained with external magnetic coils. The measurements of ACs are used for monitoring the evolution of the safety factor and density of rational magnetic surfaces in the region of maximum plasma current.     

Direct observation of large electronic domains with memory effect in doped manganites

We use a spatially resolved, direct spectroscopic probe for electronic structure with an additional sensitivity to chemical compositions to investigate high-quality single crystal samples of La(1/4)Pr(3/8)Ca(3/8)MnO3, establishing the formation of distinct insulating domains embedded in the metallic host at low temperatures. These domains are found to be at least an order of magnitude larger in size compared to previous estimates and exhibit memory effects on temperature cycling in the absence of any perceptible chemical inhomogeneity, suggesting long-range strains as the probable origin.     

Planar photonic crystal polarization splitter

The differential dispersion relation for the E and H modes (TM-like and TE-like, respectively) in planar photonic crystals is used to control the polarization-dependent propagation of light. E- and H-polarized beams were separated by 10 degrees after propagating through a 20-microm-long planar photonic crystal in the wavelength range from 1250 to 1300 nm. The plane-wave expansion calculation matches well with the experimental results. This result represents the first demonstration, to our knowledge, of a polarization splitter realized in a planar photonic crystal configuration in the near-infrared wavelength range operating solely in transmission mode.     

Mixed 2-phenylpyridine and 5-substitued-8-hydroxyquinolines palladium(II) complexes: new emitters in solutions at room temperature

The newly synthesized complexes formed by cyclopalladated 2-phenylpyridine co-ordinated to 5-substituted-8-hydroxyquinolines, are at room temperature and in fluid solution, luminescent with an absolute photoluminescent quantum yield which depends on the nature of the substituent in position 5.     

Asymmetric intermolecular Pauson-Khand reactions of unstrained olefins: the (o-dimethylamino)phenylsulfinyl group as an efficient chiral auxiliary

The first asymmetric version of intermolecular Pauson-Khand reactions of unstrained alkenes is described. Generally simple acyclic alkenes exhibit low reactivity and regioselectivity in intermolecular Pauson-Khand reactions; however, o-(dimethylamino)phenyl vinyl sulfoxide reacts under very mild conditions with a wide variety of terminal alkynes in a completely regioselective and highly stereoselective manner. The utility of the resulting 5-sulfinyl-2-cyclopentenones in asymmetric synthesis is illustrated by a very short enantioselective synthesis of the antibiotic (-)-pentenomycin I.