Cross section for the resonant charge exchange Cs++Cs at thermal energies

A remeasurement of the cross section for the resonant charge exchange Cs⁺ ?Cs at thermal energies is presented which reduces some of the ambiguities left open in previous studies.     

Teaching reference material preparation: the PHARE-country experience

The paper presents an overview about the outcome of two hands-on courses on environmental reference material production organised by the European Commissions Environment Institute within the context of its PHARE-AQUACON activities. Two plant reference materials, i.e. TP-28 (black tea) and TP-29 (mallow) were prepared and characterised by the course participants. Data on homogeneity and information values about the contents of inorganic and organic pollutants are presented. Furthermore, information about the AQUACON-Project are given, too.BERM-9—Ninth International Symposium on Biological and Environmental Reference Materials, June 15–19, 2003, Berlin, Germany.     

Observation of the electric hexadecapole moment of free Na atoms in a forward scattering experiment

We report the observation of an electric hexadecapole moment in the ground state of free sodium atoms. The Δm_F = 4 coherence, which corresponds to this moment, is created by the light field of a cw dye laser. The forward scattered light was used for detection, because of the higher sensitivity compared to lateral fluorescence.     

The long-time reactor irradiation of biological material at reduced temperature

When biological material in closed quartz ampoules is irradiated gaseous reaction products are formed as a result of radiation damage and thermal decomposition. The pressure thus created in the ampoules puts a limit to the time of irradiation or the sample mass and thereby to the detection limit of neutron activation analysis. The investigation will show how the internal pressure of the ampoules is reduced by cooling the sample containers in a nitrogen bath during irradiation so that a number of trace elements also in fresh biological material can be detected by means of neutron activation analysis with long-time irradiation. It will further contain a methodical study of the mechanical strength of quartz ampoules used as sample containers and the change in sample temperature using different sample containers and cooling through different media. The results of two irradiation studies of biological material in the low temperature irradiation unit of the reactor Melusine of the CENG Grenoble will be discussed.     

Novel cephalosporins synthesized by amination of 2,5-dihydroxybenzoic acid derivatives using fungal laccases II

Sixteen novel cephalosporins were synthesized by amination of 2,5-dihydroxybenzoic acid derivatives with the aminocephalosporins cefadroxil, cefalexin, cefaclor, and the structurally related carbacephem loracarbef using laccases from Trametes sp. or Myceliophthora thermophila. All products inhibited the growth of several Gram positive bacterial strains in the agar diffusion assay, among them methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci. The products protected mice against an infection with Staphylococcus aureus lethal to the control animals. Cytotoxicity and acute toxicity of the new compounds were negligible. The results show the usefulness of laccase for the synthesis of potential new antibiotics. The biological activity of the new compounds stimulates intensified pharmacological tests.     

The effect of magnetic field on the electrodeposition of CoFe alloys

The superimposition of a homogenous magnetic field during an electrodeposition of CoFe alloy was investigated. A magnetic field superimposed parallel to the electrode surface increases the limiting current density and the deposition rate due to the magnetohydrodynamic (MHD) effect. The deposits obtained in this field configuration appear smoother and more homogenous than the ones obtained without the magnetic field. On the contrary, a magnetic field superimposed perpendicular to the electrode surface does not influence significantly the electrochemical reaction but the morphology of the deposited layers is strongly affected. The roughness is strongly increased in this field configuration and grains grow as separated columns aligned perpendicular to the electrode surface, in the field direction. A magnetic field applied during the deposition affects the magnetic properties of the deposited layers as well. These changes are discussed with respect to the surface roughness and the internal stress state of the layer.     

Novel penicillins synthesized by biotransformation using laccase from Trametes spec

Eight novel penicillins were synthesized by heteromolecular reaction of ampicillin or amoxicillin with 2,5-dihydroxybenzoic acid derivatives using a laccase from Trametes spec. All products inhibited the growth of several gram positive bacterial strains in the agar diffusion assay, among them methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococci. The products protected mice against an infection with Staphylococcus aureus lethal to the untreated animals. Cytotoxicity and acute toxicity of the new compounds were neglectable. The results show the usefulness of laccase for the synthesis of potential new antibiotics. The biological activity of the new compounds stimulates intensified pharmacological tests.