Study of the peak effect phenomenon in single crystals of 2H-NbSe2

The weakly pinned single crystals of the hexagonal 2H-NbSe₂ compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of the peak effect phenomenon in three crystals of 2H-NbSe₂, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability effects and pinning.     

Study of 19Na at SPIRAL

The excitation function for the elastic-scattering reaction p( ¹⁸Ne, p) ¹⁸Ne was measured with the first radioactive beam from the SPIRAL facility at the GANIL laboratory and with a solid cryogenic hydrogen target. Several broad resonances have been observed, corresponding to new excited states in the unbound nucleus ¹⁹Na. In addition, two-proton emission events have been identified and are discussed.     

Beta-decay of 71Co and 73Co

A decay spectroscopy study of the neutron-rich cobalt isotopes has been performed using fragmentation of a ⁸⁶Kr³⁶⁺ beam and the new LISE2000 spectrometer at GANIL. For ⁷¹Co and ⁷³Co, the -delayed radiation has been observed for the first time, and the half-lives were found to be 79(5) ms and 41(4) ms, respectively. Features of the decay are discussed qualitatively in terms of nuclear models.     

Protein kinase A type I activates a CRE-element more efficiently than protein kinase A type II regardless of C subunit isoform

Background  

Protein kinase A type I (PKAI) and PKAII are expressed in most of the eukaryotic cells examined. PKA is a major receptor for cAMP and specificity is achieved partly through tissue-dependent expression and subcellular localization of subunits with different biochemical properties. In addition posttranslational modifications help fine tune PKA activity, distribution and interaction in the cell. In spite of this the functional significance of two forms of PKA in one cell has not been fully determined. Here we have tested the ability of PKAI and PKAII formed by expression of the regulatory (R) subunits RIα or RIIα in conjunction with Cα1 or Cβ2 to activate a co-transfected luciferace reporter gene, controlled by the cyclic AMP responsive element-binding protein (CREB) in vivo.     

Investigation of semi-insulating oxygen-doped GaAs

We found Oxygen-doped GaAs crystals to be suitable materials for CO₂ laser optical component preparation, with application at 10.6 μm. An optical transmission of 55% in the IR spectrum range, between 2 and 15 μm has been reached for such a GaAs type material. The GaAs crystals that we have analysed were grown by two procedures: Horizontal Bridgman (HB) and Liquid Encapsulated Czochralski (LEC). The HB method has been used for obtaining pure (undoped) crystals, while the oxygen-doped GaAs ingots were grown by LEC technique. The two types of samples processed in the same manner as regards mechanical polishing and chemical etching, which were investigated by Hall measurements, optical transmission spectrometry and elastic recoil detection analysis (ERDA) technique. The GaAs:O (LEC) has near semi-insulating properties as can be observed from the results of the electrical resistivity and Hall effect measurements. The ERDA spectrum shows an intense signal of oxygen in the bulk of GaAs:O (LEC) crystals, while the oxygen signal is not present in the ERDA spectrum of the undoped GaAs (HB). We consider that these results could recommend the ERDA technique as a possible qualitative and quantitative analysis in an ion-beam accelerator for oxygen content in oxygen-doped GaAs crystals. The analysis is not sensitive to the native oxide, as could be seen by measuring GaAs (HB) undoped crystals.     

Process Intensification of Emulsion Polymerization in the Continuous Taylor Reactor

Summary: Process intensification is investigated by the emulsion polymerization of styrene in the continuous Taylor reactor. The result is an increase in space time yield up to a factor 200 in comparison to a semi-batch polymerization process. This is obtained by a fast emulsion polymerization with a mean residence time, which is reduced to 60 seconds. The article presented the results of the process and the economical aspects of the Taylor reactor plant.