Action de O- et N-nucléophiles sur les sels de phényl-3 benzopyrylium-1

3-Phenyl-1-benzopyrylium percholorates 1a, 1i react exculusively at C-2 with ethanol and isopropyl alcohol, affording mixed acetals 2a, 3a, 3i . Aqueous ammonia gives symmetrical secondary amines 4a, 4b or bis(3-phenyl-2H-1-benzopyran-2-yl)amines, while with aqueous aliphatic amines (40%) bis-acetals 5a, 5b or 2,2′-oxy-bis(3-phenyl-2H-1-benzopyrans) are characterized. In some other acidic conditions, 5a and 5b are also obtained.     

α Emission in proton induced reactions

The continuous spectra of theα particles emitted in reactions induced by protons on⁹³Nb,¹⁰⁷Ag,¹¹⁸Sn,¹⁶⁵Ho,¹⁶⁹Tm have been measured at several energies ranging from 20 to 45 MeV. The spectra have been analysed in the framework of the Exciton model assuming that the emittedα's pre-existed in the target nucleus and evaluating their energy distribution on the basis of nucleon-α scattering dynamics in nuclear matter. Nuclear Reactions⁹³Nb,¹⁰⁷Ag,¹¹⁸Sn,¹⁶⁵Ho,¹⁶⁹Tm(p,α...).E=20–45MeV; Measured \(\frac{{d\sigma (E_\alpha )}}{{dE_\alpha }}\) ; calculated \(\frac{{d\sigma (E_\alpha )}}{{dE_\alpha }}\) .     

Mechanical properties of epoxy resins and glass/epoxy composites at cryogenic temperatures

The mechanical properties of four modified-epoxy resin systems were investigated. Tensile properties (including strength, modulus, and elongation), notch toughness, impact strength, the coefficient of linear thermal contraction, and thermal-shock resistance were determined for cast-resin specimens at 75, ?320, and ?423°F. Inter-laminar shear strengths (Naval Ordnance Laboratory horizontal shear and short-span shear) were obtained for glass-filament-wound-composite specimens at the three temperatures.

The two systems with the best cryogenic properties were a hybridepoxy/polyurethane (resin 4A) and a highly modified bisphenol-A epoxy (resin 2). In choosing the optimum system, the same tests (except for notch toughness, impact strength, and short-span shear) were performed on filament-wound-composite specimens at the three temperatures. In these tests the performance of resin 4A was better than, or at least comparable to, that of resin 2.     

A Mountain Pass-type Theorem for Vector-valued Functions

The mountain pass theorem for scalar functionals is a fundamental result of the minimax methods in variational analysis. In this work we extend this theorem to the class of \(\mathcal{C}^{1}\) functions \(f:\mathbb{R}^{n}\rightarrow\mathbb{R}^{m}\), where the image space is ordered by the nonnegative orthant \(\mathbb{R}_{+}^{m}\). Under suitable geometrical assumptions, we prove the existence of a critical point of f and we localize this point as a solution of a minimax problem. We remark that the considered minimax problem consists of an inner vector maximization problem and of an outer set-valued minimization problem. To deal with the outer set-valued problem we use an ordering relation among subsets of \(\mathbb{R}^{m}\) introduced by Kuroiwa. In order to prove our result, we develop an Ekeland-type principle for set-valued maps and we extensively use the notion of vector pseudogradient.     

Photobleached-fluorescence imaging of microflows

A photobleached-fluorescence imaging technique for visualizing microscale flow fields and obtaining molecular diffusion and advection information has been developed. The technique tracks fluorophores in the region of a photobleached line in a planar microdevice and yields quantitative diffusive and advective transport data. Visualizations of two- and weakly three-dimensional electroosmotically and pressure-driven fluid flow fields are demonstrated using the photobleaching of fluorescein and fluorescein-dextran conjugates. Photobleached-fluorescence imaging tracks undisturbed fluorophores, functions in polymer and glass microfluidic devices, can take advantage of fluorescent conjugates present in biochemical assays, and has a photobleached region that is flow independent.     

Intestinal absorption of tellurium studied with stable tracers

An investigation on tellurium metabolism by administration of stable tellurium isotopes¹²⁴Te and¹²⁶Te has been performed. Fractional intestinal absorption was determined in rabbits by the double tracer technique. The investigated subjects were given an enriched solution of one tellurium isotope orally and a few minutes later an enriched solution of the other isotope intravenously. The¹²⁴Te and¹²⁶Te contents in plasma samples were determined by proton nuclear activation. The methodology described offers a means to study tellurium metabolism in humans without radiation risk.     

Stable and radioactive tracers in Ru biokinetic studies

The feasibility of ruthenium metabolism studies by stable tracer administration, with a methodology based on proton nuclear activation, is presented. In order to test that the amount of stable tracer administered does not perturb significantly the mechanism investigated, a series of comparative experiments with administration of both radioactive and stable tracers has been performed on animals. As the most critical pathway seems to be the intravenous injection, four male rabbits were given an intravenous injection of radioactive¹⁰⁶Ru. Successively, the rabbits were given either a further injection of radioactive¹⁰⁶Ru or injection of different quantities of natural Ru. The activity of¹⁰⁶Ru and the concentration of natural Ru were measured in plasma samples withdrawn at different time intervals from the injections and the results were compared. Some biokinetic parameters and tissue distribution of Ru in rabbits were determined.Died on February 21, 1993.