g-factors of the lowest 2+ and 4+ states in198, 200, 202Hg

Theg-factors of the 2 ₁ ⁺ and 4 ₁ ⁺ states in^198,200,202Hg were simultaneously measured by means of the transient-field perturbed angular correlation method in Coulomb excitation using multi-isotopic targets and thin polarized Gd foils as ferromagnetic host. Theg(2 ₁ ⁺ ) andg(4 ₁ ⁺ ) were found identical within errors in^{198, 200}Hg, while in²⁰⁰Hg lowerg-factor values have been determined. The experimentalg-factors were compared with the predictions of the pairing-plus-quadrupole, dynamical deformation and interacting boson models.     

Theg-factor of the 8+ isomer of142Eu

Theg-factor of the 8⁺ isomer of¹⁴²Eu with mean lifeτ=9 ns, has been measured by the time-differential perturbedγ ray angular distribution (TDPAD) method. The 8⁺ isomer was populated with the reaction¹¹⁴Cd(³²S,p3n)¹⁴²Eu at 155 MeV. The obtained valueg(8⁺)=0.51(3) agrees with shell model calculations using effective single-particle moments taken from neighbouring nuclei. A main configurationπh_11/2?(vh _11/2)^?1 has been confirmed for the 8⁺ isomer.     

On the use of sulfonated tolyl and xylyl stearic acids as polarographic maxima suppressors

Summary Sulfonated tolyl and xylyl steario acids were used as maxima suppressors in the reduction of simple and complex metal ions. It was found that these compounds can be employed as maxima suppressors for the cathodic waves of Pb²⁺, Co²⁺, Ni²⁺, copper glycine complex and copper biuret complex. In the case of difficulty suppressible maxima like those of iodide-cadmium complex and Ni²⁺-Co²⁺ mixture these were found to be more effective than other maxima suppressors. The P. M. P. and M. S. P. values were calculated in presence of these ions. The P.M.P. values of STSA were found to be greater than those for SXSA. This behaviour may be attributed to greater +I effect of xylyl group.     

On the chemical erosion of a carbon first wall proposed for Tokamak devices for controlled nuclear fusion

Preliminary results on the chemical attack of several carbon materials by hydrogen plasma are presented and compared with the literature data on the reaction of hydrogen atoms with carbon in an afterglow. The chemical erosion of silicon carbide and of pyrolytical graphite should not be dangerous for the ignition of fusion assuming that the reaction probability of hydrogen atoms with the particular material would not be increased due to radiation damage of the surface.     

A Novel and sensitive spot-test for m-dinitroaromatics and their derivatives with sodium sulphite and dimethylsulphoxide

Sodium sulphite has been used for a very sensitive characterization of m-dinitroaromatics and their derivatives, with dimethylsulphoxide as solvent.     

Effects of stress ratio on fatigue life of carbon-carbon composites

Cyclic loading causes cumulative damage and therefore degrades the inelastic properties of composite materials. Present work investigates the damage development under tension-tension fatique, and the effect of stress ratio on the fatigue life of carbon-carbon (C/C) composites at room temperature at a frequency of 3 Hz. The fatigue damage has been identified through ultrasonic non-destructive technique, optical microscopy and scanning electron microscopy.From the S-N curve it has been observed that the endurance strength of C/C composite is quite high; approximately 85% of the ultimate tensile strength. The fatigue life of C/C composites has also been observed to increase with the stress ratio. Matrix cracks, filament splitting within the yarns, complete delamination and the nucleation of the interfacial flaws have been identified as the failure mechanisms during the fatigue tests. On the other hand, the failure modes during the static test were found to be complete fiber fracture accompanied by partial delamination. A statistical fatigue life distribution for carbon-carbon composites has also been presented in this paper.     

Empirical model for electron impact ionization cross sections of neutral atoms

A simple empirical formula is proposed for the rapid calculation of electron impact total ionization cross sections both for the open- and closed-shell neutral atoms considered in the range 1≤ Z≤92 and the incident electron energies from threshold to about 10⁴ eV. The results of the present analysis are compared with the available experimental and theoretical data. The proposed model provides a fast method for calculating fairly accurate electron impact total ionization cross sections of atoms. This model may be a prudent choice, for the practitioners in the field of applied sciences e.g. in plasma modeling, due to its simple inherent structure.     

Asymmetric N-heterocyclic carbene benzimidazolium salts and their silver(I) complexes: potential as ionic liquid crystals

The synthesis and characterisation of a homologous series of monodentate benzimidazolium salts, 1–4 and their mononuclear silver(I)–NHC (where NHC = N-heterocyclic carbene) complexes, 5–8, are reported. The benzimidazolium salts were prepared from the N-alkylation of 1-methyl-benzimidazole with alkyl halides of varying carbon chain lengths. The mono silver(I)-NHC complexes, 5–8, were prepared by the reaction of the benzimidazolium salts with Ag₂O. All the synthesised compounds were fully characterised by ¹H-nuclear magnetic resonance (¹H-NMR), ¹³C-NMR and fourier-transform infrared (FTIR) spectroscopy. The molecular structures of compounds 3·PF₆, 4·PF₆, 7 and 8 were elucidated through single-crystal X-ray diffraction analyses. We postulate that the attachment of long alkyl chains to the heterocyclic core of 1-methyl benzimidazole could induce mesophase formation. The liquid crystalline behaviour of the benzimidazolium salts was investigated by polarised optical microscope and differential scanning calorimetry. Salts 3 and 4 were found to be thermotropic liquid crystals which exhibited a smectic A phase. However, upon complexation with silver(I) ions, all the Ag(I)–NHC complexes are found to be non-mesogenic.