Search

Tests on (NixFeyO4 - Ni1?xFexO)/(CuxNiyFez) cermets, considered as promising anode for the aluminium production, were performed under electrolysis at 0.8 A·cm-2 in molten mixture of cryolite at 960°C. In order to predict phase compositions, a thermodynamic study was performed and experimentally verified by SEM-EDS analysis. The metallic phase oxidation leads to the formation of different phases such as FeF2, Ni0.90Fe0.10O, NiF2 and Cu2O phases, while NixFe3-xO4 spinel is continuously enriched up to x = 0.90, the thermodynamically stable nickel composition. When the cermet material is fully oxidized, metallic and oxide phases are converted into soluble or non-conductive phases, leading to the end of anode service life.

Functional brain alterations induced by lindane were examined in Rat chronically exposed to low doses of lindane (1 and 2 μg L −1 in drinking water) from conception. Histological and electrophysiological investigations were conducted at 14 weeks of age. Lindane did not induce histological changes. It did not significantly modify the sleep–wakefulness cycle and EEG did not show major alterations. The spectral EEG analysis, by recording cortical variations in both energy spectrum and energy levels of different frequency bands, showed an increase in the 11–15 Hz activity in both groups exposed to lindane. This activity was characterised by spindles well-depicted during slow wave sleep or associated with fast activity during wakefulness and theta activity in paradoxical sleep. These data suggest that chronic exposure to lindane doses as low as 1 μg L −1 in drinking water could lead to central electrophysiological effects possibly involving GABA-benzodiazepine mechanisms.

The electrochemical reduction of hafnium tetrachloride has been studied in molten equimolar NaCl-hCl from 700 to 900 o C. Using voltammetry on a tungsten electrode, only the +IV and 0 oxidation states of Hf have been shown to exist in the electrolyte. Convolution analysis has permitted calculation of the diffusion coefficients, and shown that the exchange was quasi-reversible at 700 and 800 o C, but reversible at 900 o C. Fluoride additions led to a more stable fluoro-complex HfF 6 2- , which was reduced in a single step to metallic hafnium. The exchange was shown to be reversible, and the diffusion coefficients were determined, in the 700 to 900 o C temperature range

The electrochemical reduction of hafnium tetrachloride has been studied in molten equimolar NaCl-hCl from 700 to 900 o C. Using voltammetry on a tungsten electrode, only the +IV and 0 oxidation states of Hf have been shown to exist in the electrolyte. Convolution analysis has permitted calculation of the diffusion coefficients, and shown that the exchange was quasi-reversible at 700 and 800 o C, but reversible at 900 o C. Fluoride additions led to a more stable fluoro-complex HfF 6 2- , which was reduced in a single step to metallic hafnium. The exchange was shown to be reversible, and the diffusion coefficients were determined, in the 700 to 900 o C temperature range