Crystal field model for the resistivity minimum and its evolution with hydrogen concentration in PrH2+x

The spin-disorder resistivity _m (T) of PrH_2+x shows for the pure dihydride (x=0) a minimum in its temperature dependence above the magnetic ordering temperatureT _N . This minimum can be explained qualitatively and quantitatively by a crystal-field effect if the ground state is ₁ = ₅ (a magnetic state) while the first excited state is ₂ = ₁ (a non-magnetic state). Forx=0.08, the magnetic ordering and the resistivity minimum tend to disappear which can be explained by the change of the crystalfield symmetry induced by the supplementary H-ions, leading to a splitting of the ground state.     

Masses of S and P wave mesons and pseudoscalar decay constants using a confinement scheme

In the framework of relativistic harmonic confinement model for quarks and antiquarks, the masses of S- and P-wave mesons and pseudoscalar decay constants from light flavour to heavy flavour sectors are computed. The residual two-body Coulomb interaction and the spin-dependent interaction of the confined one gluon exchange effects (COGEP) such as spin-spin and spin-orbit interactions are perturbatively incorporated with the confinement energy to get the respective vector-pseudoscalar meson mass differences. Here we employ the same parametrization and model parameters as used in a recent study of low-lying hadron masses and leptonic decay widths. The results are being compared with the values obtained from other theoretical models and the experimental values.     

Evidence for a relation between interstitial long-range migration in h.c.p. metals and their c/a-ratio

The temperature for the long-range migration of an interstitial atom in h.c.p. metals is - when normalized to the melting temperature - observed to be a linear function of the c/a-ratio. This can be understood in terms of the relative size of open atomic lenses in the lattice. The special cases of Zn and Cd (extremal c/a-values) are tentatively explained by a crowdion mechanism for the creation and annealing of Frenkel defects.     

Pollution control and depollution processes by plasma techniques

The European Union is creating strict standards for air and water pollution and waste treatment and implementing aggressive regulations. Compliance with these regulations is impossible without the development of new depollution processes involving plasma or laser technology. Time is one of the major problems in monitoring pollutants with the use of the time-resolution laser-induced breakdown spectroscopy technique, which can perform online analysis without sampling with a high level sensitivity for all the species of the Periodic Table. Plasma-enhanced desorption from fly ashes or polluted soils associated with a mass spectrometer or an optical emission spectrometer allows the monitoring of volatile organic compounds (VOCs) and organochlorine species in a few seconds. In the last DBD point, we present the treatment of VOCs in air by the plasma technique in order to destroy or trap PAH molecules.     

Electrical resistivity of the α-phase lutetium-hydrogen at low temperature

The resistivity of the solid solutions LuH_x for 0 ? x ? 0.235 is measured between 4.2 and 300 K. The maximum α-phase solubility is found for x = 0.2 in the whole temperature range investigated. A resistivity anomaly is observed in hydrogen containing specimens and its possible origin of anomalous behavior is discussed.     

Régiospécificité de la cycloaddition des diarylnitrilimines sur quelques dérivés indoliques

In this paper, we describe the results of a study of the reaction of diaryl nitrilimines with N-ethylindole ( 1 ) and 2-methoxycarbonyl-N-ethylindole ( 2 ). The regioselectiivity of the reaction is reversed when going from 1 to 2 as it has been spectroscopically and chemically demonstrated.