Fragmentations observed in the reactions of α-methoxy-γ-alkoxyalkyl iodide substrates with super-electron-donors derived from 4-DMAP and N-methylbenzimidazole

Reactions of super-electron-donors (SEDs) derived from 4-dimethylaminopyridine and from N-methylbenzimidazole with α-methoxy-γ-alkoxyalkyl iodides lead to liberation of the γ-alkoxy groups as their alcohols. This is consistent with generation of alkyl radicals from the alkyl halide precursors, and trapping of these radicals by the radical-cation of the SED, followed by a heterolytic fragmentation.     

Comparison of iodinated [Nle15]- and [Met15]-gastrin17 prepared by reversed-phase HPLC

125I-[Nle15]-gastrin17 prepared by the iodogen method can be separated by reversed-phase high performance liquid chromatography into two peaks, both of which elute after [Nle15]-gastrin17. Direct determination of the specific activities of the two derivatives by microbore reversed-phase HPLC indicated that they were the mono- and di-iodinated species. In contrast the two peaks obtained with [Met15]-gastrin17 iodinated under the same conditions eluted earlier, relative to the appropriate gastrin17 standard, than the [Nle15]-gastrin derivatives. Treatment of either peak with 0.75 M dithiothreitol at 56 degrees C or 95 degrees C resulted in progressive conversion to compounds migrating in relative positions similar to the 125I-[Nle15]-gastrin17 derivatives. Direct determination of the specific activity of the earlier eluting [Met15]-gastrin17 derivative before reduction indicated that it was the mono-iodinated species. It thus appears likely that iodination of [Met15]-gastrin17 by the iodogen method results predominantly in the formation of mono- and di-125I-[Met sulphoxide15]-gastrin17. To avoid problems arising from oxidation of the methionine residue of gastrin during iodination, the use of 125I-[Nle15]-gastrin17 in binding studies is therefore recommended.     

Infrared multiphoton chemistry: Comparison of theory and experiment,solution of the master equation

An energy-grained master equation has been used to model the multiphoton pumping process in SF₆. It was found that an energy-dependent absorption cross section that was approximately inversely dependent on the level of excitation was needed to reproductive experimental data on the fraction decomposed per pulse.     

Determination of sub-nanogram quantities of ruthenium by flameless atomic absorption spectrometry

Flameless atomic absorption spectrometry has been applied to the determination of subnanogram quantities of ruthenium in a variety of matrices encountered in the solidification of nuclear waste. Detection limits ranged to below 10^?10 g, depending on the sample matrix. Most matrix effects could be eliminated by proper selection of atomizer temperature program, allowing the use of a single set of standards in 0.1 N HCl. The one exception was the calcined solid matrix, where a fusion and extraction were used to dissolve the ruthenium and separate it from matrix constituents.     

Charge localization by molecular orbital calculations. II. Formamide,thioformamide and N-methylated analogues

Ab initio molecular orbital calculations have been used to determine the degree of charge localization associated with the formation of radical cations on electron impact of formamide, thioformamide and their N-methyl and N, N-dimethyl analogues. The charge favours the nitrogen of formamides and the sulphur of thioformamides, but the degree of localization is calculated to be lower than in the radical cations of urea and thiourea.     

Influence of deformation upon domain wall pinning defect spectrum in 50-50 NiFe

A measurement of the distribution function of magnetically active defects in 50-50% Ni-Fe was made before and after mild mechanical deformation (? ? 10^?3). After deformation, the distribution function has two maxima instead of the usual one. The results are interpreted in terms of interactions of magnetic domain walls with grain boundaries which, as a result of the deformation, apparently provide more effective pinning sites.     

Conjugate addition of organolithium reagents to acrylanilide anions

Phenyllithium, $\text{n}$-butyllithium, and $\text{t}$-butyllithium were found to add to substituted acrylanilide anions to give the 1,4-addition products in fair to good yields.     

Comparison of fuzzy sets on the same decision space

Some methods of making fuzzy decisions include a comparison of fuzzy sets on the same space. Methods have been published which suffer from lack of discrimination between alternatives and occasional conflict with intuitive choice. These methods are reviewed in this paper and then a new approach is described which overcomes their drawbacks. Methods of evaluating the parameter used in decision-making are given which can be varied to incorporate different utility functions.