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Calcium influx into cardiac myocytes via voltage-gated Ca channels is a key step in initiating the contractile response. During prolonged depolarizations, toxic Ca(2+) overload is prevented by channel inactivation occurring through two different processes identified by their primary trigger: voltage or intracellular Ca(2+). In physiological situations, cardiac L-type (Ca(V)1.2) Ca(2+) channels inactivate primarily via Ca(2+)-dependent inactivation (CDI), while neuronal P/Q (Ca(V)2.1) Ca(2+) channels use preferentially voltage-dependent inactivation (VDI). In certain situations however, these two types of channels have been shown to be able to inactivate by both processes. From a structural view point, the rearrangement occurring during CDI and VDI is not precisely known, but functional studies have underlined the role played by at least 2 channel sequences: a C-terminal binding site for the Ca(2+) sensor calmodulin, essential for CDI, and the loop connecting domains I and II, essential for VDI. The conserved regulation of VDI and CDI by the auxiliary channel beta subunit strongly suggests that these two mechanisms may use a set of common protein-protein interactions that are influenced by the auxiliary subunit. We will review our current knowledge of these interactions. New data are presented on L-P/Q (Ca(V)1.2/Ca(V)2.1) channel chimera that confirm the role of the I-II loop in VDI and CDI, and reveal some of the essential steps in Ca(2+) channel inactivation.

The start-up procedure of a laboratory fluidized-bed was monitored by an automatic control system. Twenty six days were necessary to increase the load from 1 to 35 kg COD/m3.d. The system took into account the pH of the liquid phase, the production of gas, and the concentration of hydrogen in the gas phase. These parameters were measured by on-line sensors. According to variations of these parameters, algorithm based on a principle very close to an expert system adjusted the flow-rate of the feeding pump. The automatic control system was tested in the following situations: perturbations in the process generated by large pH variations (± 0.2 to 0.7 pH unit) and organic overloads (from 50 to 100 kg COD/m3.d). After 44 hours of overloading, CH4 and CO2 concentrations in the gas phase were very useful to detect the deviation of the reactor.

A pilot fluidised bed reactor was subjected to shockloads using wine distillery wastewater. The parameters' response was recorded. Parameters analysed in the gaseous phase were : H2, CH4, CO2 and gas production; in the liquid phase : pH, temperature, TOC and VFA. Different shockloads were applied : short but intensive shockloading, long shockloadings; temperature variations; change of nature of substrate (wine distillery wastewater was replaced by glucose). Generally speaking, the parameters' response was short (less than one hour). The specific parameters of the gaseous phase and pH can be used for the optimal control of the fermentation process.

The green cathodoluminescence of natural and synthetic mercur sulphide (α-HgS) is investigated. It is interpreted in terms of an edge emission involving a phonon with an energy of ≈ 20 meV. The transitions are of the bound-to-bound type at liquid helium, and of the free-to-bound type for higher temperatures. The complexity of the emission makes it difficult to interpret it by a clearly-defined model. Donor states with bound energies of ED ≧ 8 meV and 20 meV < ED < < 30 meV and acceptor states with an energy of ≈ 40 meV are involved in the emission. Die grune Lumineszenz von naturlichem und synthetischem Quecksilbersulfid (α-HgS) wird untersucht. Sie wird mit einer Kantenemission interpretiert, die ein Phonon mit einer Energie von ≈ 20 meV einschliest. Die Ubergange sind bei der Temperatur des flussigen Heliums vom Typ „gebunden zu gebunden”, und bei hoheren Temperaturen vom Typ „frei zu gebunden”. Die Komplexitat macht es schwierig, die Emission mit einem klar definierten Modell zu interpretieren. Donatorzustande mit Bindungsenergien von ED ≧ 8 meV und 20 meV < ED < 30 mV und Akzeptorzustande mit einer Energie von ≈ 40 meV sind an der Emission beteiligt.

In this paper we analyse the cathodoluminescence of cinnabar powder which emission appears as a broad band peaked at 1.65 eV at liquid helium temperature. In a previous paper we showed by kinetics measurements that this luminescence was due to a donor-acceptor pair emission mechanism. However the donor-acceptor model was not sufficient to explain the Gaussian shape of the emission band as well as its important width. We show here the influence of a strong phonon coupling by measurements in terms of temperature. Application of both donor-acceptor and vibronic models allows us to interpret this luminescence satisfactorily. We calculate the fundamental parameters of the emission (Bohr half-radius R B , maximum radiative probability W MAX , emission energy of the pairs at infinite separation hv ∞ ). At the end a deconvolution method which takes into account the vibronic influence permits us to calculate the time-resolved spectra and to compare them with the experimental ones.

In a previous paper the authors (see J. Physique, vol.41, p.707, 1980) showed by kinetics measurements a donor-acceptor transition peaked at 1.59 eV in CuGaSe2. They confirm here the fundamental parameters of this emission by measurements in terms of temperature and excitation rate. They show the influence of weak phonon coupling on intra-pairs recombination. An original deconvolution method which takes account of this influence permits the authors to find the experimental spectra again.

Measurements are made of spectrum shift with excitation intensity by means of time resolved spectroscopy, over a broad emission band of mercuric sulphide peaked at 1·65 eV with a width of 320 meV. The behaviour of the decay is measured at 4 K for different emission band energies. It is shown that the experimental results are in agreement with a donor–acceptor type “t-shift”, “j-shift”, and the t−n law of the light decay. Since the band is very broad, the interaction of the lattice with the different pairs is considered. Messungen der Spektrenverschiebung mit der Anregungsintensitat werden mit zeitaufgeloster Spektroskopie in einer breiten Emissionsbande von Quecksilbersulfid bei 1,65 eV mit einer Breite von 320 meV untersucht. Das Abkling verhalten wird bei 4 K fur verschiedene Bandenergien der Emission gemessen. Es wird gezeigt, das die experimentellen Ergebnisse in Ubereinstimmung mit einer Donator–Akzeptor „t-Verschiebung”, „j-Verschiebung” und dem t−n-Gesetz des Lichtabklingens sind. Da die Bande sehr breit ist, mus die Wechselwirkung des Gitters mit den verschiedenen Paaren berucksichtigt werden.

The low temperature cathodoluminescence spectra of AgGaS2 are investigated in this work. In the purest single crystals (sample A1) at 4.2 K, the luminescence spectra are dominated by free excitons, by exciton bound to impurities, and by an edge emission peaked at 2.590 eV. Our study shows the presence of an acceptor level at 110 meV which should be responsible of the bound exciton at 2.689 eV as well as of the edge emission. In other samples, we only observe the free exciton at 2.700 eV and a green broad emission band at 2.470 eV.

Cathodoluminescence measurements on cinnabar (α-HgS) published in a previous paper show that the emission peaked at 1.9 eV obeys a vibronic mechanism. The purpose of the present paper is to complete this characterisation by photoluminescence and excitation measurements (shape of spectrum, kinetics, thermal quenching). These different results allow to calculate the configurational coordinate diagram and to determine its location in the gap. It is also pointed out the influence of the traps and the non-radiative centres revealed by measurements of photoconduction and thermal-stimulated current. Des mesures de cathodoluminescence sur le cinabre (α-HgS) publiees dans un article precedent nous ont montre que l'emission centree a 1,9 eV obeissait a un mecanisme vibronique. l'objet du present article est de completer cette caracterisation par des experiences de photoluminescence et d'excitation (forme des spectres, cinetique, extinction thermique). Ces differents resultats nous ont permis de calculer le diagramme de configuration et de le localiser dans la bande interdite. Nous signalons egalement l'influence des pieges et des centres non radiatifs mis en evidence par photoconduction et courant thermostimule.