Estimates for Dirichlet-to-Neumann Maps as Integro-differential Operators

Potential Analysis - Some linear integro-differential operators have old and classical representations as the Dirichlet-to-Neumann operators for linear elliptic equations, such as the 1/2-Laplacian...     

Oscillatory rise of bubbles in wormlike micellar fluids with different microstructures

Previous observations of the nontransient oscillations of rising bubbles and falling spheres in wormlike micellar fluids were limited to a single surfactant system. We present an extensive survey of rising bubbles in another system, an aqueous solution of cetylpyridinium chloride and sodium salicylate, with and without NaCl, across a range of concentrations and temperatures. Two different types of oscillations are seen in different concentration ranges, each with its own temperature dependence. Rheological data identify these different hydrodynamic states with different fluid microstructures.     

Influence de la teneur en halogene sur les proprietes cathodochromiques des sodalites

The influence of the preparative methods upon the number of vacancies in sodalites Na_4-x(AlSiO₄)₃Br_1-x (0.07 ? x ? 0.86) was investigated. A relation has been found between the bromine content and the number of optically erasable F centers induced by an electron beam. Conversely to some previous hypotheses it is possible to conclude that the halogen is the electron donor.     

Reaction of 3-nitro- and 3-diethylphosphonocoumarin with phenacyl bromide. X-ray molecular structure of 3-nitro-3,4-phenacylidenecoumarin

3-Nitro- and 3-diethylphosphonocoumarins 4a,b react with phenacyl bromide stereoselectively under phase-transfer conditions, in the presence of a base and of a transfer agent, to give the cyclopropyl derivatives 6 and 7 in good yields. A mechanistic explanation is given for the stereoselectivity of the reaction. The X-ray molecular structure of compound 6a is also presented.     

Fused v-triazolo-heterocycles. Part 2. Synthesis of 4H-v-triazolo[1,5-d] [1,3,4]oxadiazin-4-ones from the 1-aroylamino-v-triazole-5-carboxylic acids

The synthesis of some 4H-v-triazolo[1,5-d] [1,3,4]oxadiazin-4-ones is described. They are prepared by the reaction of the corresponding 1-aroylamino-v-triazole-5-carboxylic acids with thionyl chloride in the presence of pyridine. The spectroscopic data of these new compounds are also reported.     

The determination of thermal junction potential difference

A novel method has been designed and exploited to determine the thermal junction potential difference(TJPD) between two acids or alkalies of the same composition but with different temperature. The absolute value of measured TJPD between two strong acids(or alkalies) maintained at different temperatures increases with increasing of the temperature difference between the two electrolytes over the range from 0 to 40 °C. In strong acids, the hot end always has the lower potential while in strong alkalies, the cold end has the lower potential. This is because the ions of fast diffusion rate contribute most to the TJPD. Our results demonstrate the importance of the correction for TJPD in deriving the kinetic parameters when studying the temperature effect on reaction kinetics.     

13C NMR spectra of 1-(α-aroyloxyarylideneamino)-1,2,3-triazoles. Identification of 4,5-unsymmetrically substituted derivatives

The ¹³C nmr spectra of the title compounds are reported. Chemical shifts of C-4 and C-5 carbons of the triazole ring are used for structural assignment of the 4,5-unsymmetrically substituted 1-(α-aroyloxyarylideneamino)-v-triazoles (triazolylisoimides). A complete assignment of the shifts of the α-aroyloxyarylideneamino group is given. Some J_C-H values are also reported.     

Thecis-trans energy difference in bi-1-cyclopro-pen-1-yl and related compounds

Thecis-trans energy difference of bi-1-cyclopropen-1-yl and the fluorosubstituted derivatives are studied byab initio methods in order to establish the stability of the cis andtrans diene isomers.The results of theab initio method STO-3G points toward thetrans bi-1-cyclopropen-1-yl as the most stable isomer (0.2kcal/mol). The energy of the transition state is about 2.5 kcal/mol above that of thetrans isomer. The electronic transitions of the isomers are also reported.Senior Fullbright-Hays Scholar to Uruguay.