Synthese et reactivite d'organomagnesiens perfluores. V.[1] Synthese et identification de nouveaux composes perfluoroalkyles du mercure a chaine longue.

The reaction of mercuric salts HgY₂ or organic mercuric compounds R_HHgX with long chain perfluorinated Grignard reagents R_FMgBr leads to a series of new perfluoroalkyl mercury derivatives with the general formula R_FHgZ (R_F=C₄F₉, C₆F₁₃, C₈F₁₇ ; Z=R_F,R_H,Y with Y = I,Br,Cl, NO₃,OCOCH₃,OCOCF₃).The synthesis of these organomercuric compounds is described, and their spectroscopic properties are reported.     

Soot oxidation kinetics from TG experiments

Thermogravimetric analysis (TG) has been used extensively for soot oxidation studies. Its known experimental and computational difficulties, however, have led to extended criticism concerning the reliability of the extracted kinetics and their potential for reliable reaction modelling. This study explores if TG kinetics could lead to successful simulation results notwithstanding the related disputes. For this, TG and mini-scale soot oxidation experiments with oxygen (O₂) were conducted. The TG kinetics reliability was controlled through comparison with the corresponding mini-scale results and by the satisfactory simulation of the mini-scale experiments.     

Synthese et reactivite d''organometalliques perfluores. VII [1] reactivite comparee de derives perfluoroalkyles satures et insatures de l''etain et du mercure vis-a-vis d''electrophiles.

The reactivity of some derivatives of perfluorooctenyl-tin, perfluorooctenyl-mercury and perfluorooctyl-mercury towards protic acids, especially hydrogen chloride, is studied.

The easy cleavage of the tin - sp² carbon bond is painted out, and used to study possibilities of transferring the perfluorooctenyl radical on mercury, upon reaction with mercuric salts.

The mercury-perfluoroalkyl radical bond is shown to be, on the contrary, very resistant to an electrophilic attack.

These results are compared to those concerning the hydrocarbon analogs, and an interpretation, relied to the electronic density on the carbon atom bound to the metallic atom, is given.     

Time Evolution of Optical Emission Spectrum of a Hg-HID Lamp Exposed to X-ray

Time variation of optical emission lines for Hg, and other elements detected in a mercury HID lamp before and during X-ray irradiation were analyzed. Various irradiation conditions are causing differences in time dependencies of all Hg spectral line intensities (including that of 253.73 nm resonance line not completely self-absorbed). The X-ray optical depths are smaller in the case of Hg gas compared with burner wall glass. The free electrons generated during X-ray exposure (photoelectrons, Auger electrons) contribute to changes in plasma characteristics (e.g. plasma temperature, density, etc.) in transitory regime. In quasi-stable regime there are practically no differences between electron temperatures for normal and irradiated lamp. A qualitative explanation in the framework of Beer-Lambert law is given.     

Simulation of an Ultrahigh-Pressure Short-Arc Xenon Discharge Plasma

Technical Physics - We have studied a high- (ultrahigh-) pressure short-arc discharge in xenon with thoriated tungsten cathodes. A system of equations formulated based on earlier experimental data...     

Chemometric analysis of high performance liquid chromatography-diode array detection-electrospray mass spectrometry of 2- and 3-hydroxypyridine

Triply coupled high performance liquid chromatography using diode array detection and positive ion electrospray mass spectrometry of 2- and 3-hydroxypyridine is presented. Considerations of the physical method for coupling the two detectors, the influence of pH on retention times, the cone voltage of the mass spectrometer and the linear concentration ranges are described. Data from both detectors are aligned and interpolated. The analyte mass spectra are reduced to 20 significant masses. Principal components plots on the raw, normalised and standardised data, derivatives to determine composition 1 regions, deconvolution and procrustes analysis to compare data from both detectors are discussed. Common trends in both mass spectral and diode array chromatograms are interpreted. This paper represents a new approach to common processing of chromatographic data from two detectors.     

Time-dependent behavior of a pulsed high power xenon flashlamp. Application to the Mega-Joule laser pumping

A numerical model has been developed for studying the time-dependent behavior of cylindrical high power xenon flashlamp. The equations of local energy conservation and mass conservation are solved using the finite volume method to give plasma parameters such as radial temperature profiles, instantaneous emission spectra, pressure, velocity, arc conductance, etc. In a first approximation the plasma is described under local thermodynamic equilibrium, LTE. The results are given as a function of time over the pulse and for several nodes in the cross section. Then the detailed spectral and temporal calculations of the output radiation from xenon flashlamp and radiation efficiencies are provided.     

Velocity of sound in two-phase mixtures

Velocity of sound is computed for water, ammonia, Freon-12 and isobutane in two-phase mixtures in thermodynamic equilibrium. A computational method is developed which yields the sound velocity in terms of the thermodynamic coordinates of the substance (T, x) without the use of diagrams. Corresponding velocities of sound for the four substances considered exhibit a certain similarity which is examined statistically. The relationship between the sound velocity and the critical mass flux is also investigated.