A Monte Carlo method for calculating strength functions in many-fermion systems

The calculation of moments is an essential first step in the calculation of strength functions for operators. A method for calculating approximate moments of a variety of operators in large vector spaces (dimension N_e) based on the use of sets of random multiparticle vectors (dimension N_d<N_e) is described and applied to the calculation of hamiltonian moments 〈Hⁿ〉 in two nuclear cases: ${}^{21}\text{Ne}\text{(n=1}\text{to}\text{10)}\text{and}{}^{28}\text{Si}\text{(nm=1}\text{to}\text{3)}$. The random vectors, which we call RRV's (random representative vectors), are constructed by statistically sampling a fraction f=N_d/N_e of the full space. Useful results are obtained with f?10^?6(case of ²⁸Si, N_e = 5.5 × 10⁷). For N_d=N_e case of ²¹Ne, N_e=1935) our results for the dispersions of the sets of the moments closely approximate the predictions of Porter.     

Etude des aldimines lithiees: II. Preparation d'aldehydes a groupement halogenovinylique. Application a la synthese d'oxo-3 cyclopentenes et d'aldehydes γ acetyleniques

The condensation of metallated aldimines, prepared from activated lithium dialkylamides, with different dihalogenoalkenes gives aldehydes with a halogenovinylic group. Acidic hydrolysis of these aldehydes leads directly to cyclopentenones. When treated with an excess of activated amide, halogenovinylic aldimines give γ-acetylenic aldehydes.     

Isothiazoles VIII: Isothiazolidin-3-one derivatives

Useful procedures for preparing novel 4-methyl-4,5,5-trichloroisothiazolidin-3-ones and 4,4,5,5-tetrachloroisothiazolidin-3-ones are reported.     

Isothiazoles IV: 4-isothiazolin-3-one i-oxide and 1,1-dioxides

Representative 4-isothiazolin-3-one I-oxides and I, I-dioxides have been prepared by the reaction of m-chloroperbenzoic acid with the respective 4-isothiazolin-3-ones. Chromic acid, dinitrogen tetroxide, and nitric acid have also been successfully employed in the oxidation of several 3-hydroxyisothiazoles to their respective I-oxides.     

Controlled chemical functionalization of multiwalled carbon nanotubes by kiloelectronvolt argon ion treatment and air exposure

The chemical and morphological modifications of multiwalled carbon nanotubes (MWCNTs), by 2 keV Ar(+) treatment, have been followed by field emission scanning (FESEM) and high-resolution transmission (HRTEM) electron microscopies and by X-ray photoelectron (XPS) and Raman spectroscopies. Morphological changes were followed, both in situ and on subsequent air exposure, and the data indicate that free radical defects, initially produced under low Ar(+) treatment doses ( approximately 10(13) ions/cm(2)), act as the nuclei for the formation of localized asperities that form along the walls of the CNTs. Continued treatment results in their stublike elongation that continues with further treatment, forming extensions under heavy treatment doses. The chemical changes that occur, on reaction with air, reveal that the defects initially created are secondary C atoms, formed when a single bond breaks; further treatment breaks an additional bond to form primary C atoms; free radical fragments, lost when the third bond breaks, condense on the free radical defects to form the asperities. The extent of primary and secondary C atoms, and thus their functionalization on air exposure, may be controlled by the extent of treatment, offering a method for the controlled surface functionalization of CNTs by low-energy Ar(+) treatment.     

Synthesis of possible metabolites of chlorpromazine. I. 7-hydroxy derivatives of chlorpromazine,nor1-chlorpromazine and nor2-chlorpromazine

The title compounds and various derivatives have been prepared as analytical standards for the identification of chlorpromazine metabolites in biological materials. Additional evidence is presented for the existence of a halogen-induced Smiles rearrangement in the phenothiazine series.     

17O solid-state NMR and first-principles calculations of sodium trimetaphosphate (Na3P3O9), tripolyphosphate (Na5P3O10), and pyrophosphate (Na4P2O7)

The assignment of high-field (18.8 T) (17)O MAS and 3QMAS spectra has been completed by use of first-principles calculations for three crystalline sodium phosphates, Na 3P 3O 9, Na 5P 3O 10, and Na 4P 2O 7. In Na 3P 3O 9, the calculated parameters, quadrupolar constant ( C Q), quadrupolar asymmetry (eta Q), and the isotropic chemical shift (delta cs) correspond to those deduced experimentally, and the calculation is mandatory to achieve a complete assignment. For the sodium tripolyphosphate Na 5P 3O 10, the situation is more complex because of the free rotation of the end-chain phosphate groups. The assignment obtained with ab initio calculations can however be confirmed by the (17)O{ (31)P} MAS-J-HMQC spectrum. Na 4P 2O 7 (17)O MAS and 3QMAS spectra show a complex pattern in agreement with the computed NMR parameters, which indicate that all of the oxygens exhibit very similar values. These results are related to structural data to better understand the influence of the oxygen environment on the NMR parameters. The findings are used to interpret those results observed on a binary sodium phosphate glass.