Hadron production near threshold

Final state interaction effects inpp→ pΛK ⁺ andpd →³Heη reactions are explored near threshold to study the sensitivity of the cross-sections to thepΛ potential and theηN scattering matrix. The final state scattering wave functions between Λ andp andη and³He are described rigorously. The Λ production is described by the exchange of one pion and aK-meson between two protons in the incident channel. Theη production is described by a two-step model, where in the first step a pion is produced. This pion then produces anη by interacting with another nucleon     

Rapid shear viscosity calculation by momentum impulse relaxation molecular dynamics

Recently, Arya et al. [J. Chem. Phys. 113, 2079 (2000)] introduced a new molecular dynamics method to rapidly compute the viscosity of fluids. The technique, termed momentum impulse relaxation (MIR), involves the imposition of a Gaussian velocity profile on an equilibrated system, after which the decay in the profile is monitored as a function of time. The shear viscosity is computed by matching the rate of decay of the velocity profile to the corresponding solution of the Navier-Stokes equation. The method was originally applied to simple systems (argon and n-butane) and found to give a comparable accuracy to conventional equilibrium and nonequilibrium methods with more than an order of magnitude reduction in computing time. In this work, we extend and generalize the method to examine larger molecules with higher viscosities than have been examined previously. A detailed analysis of the method is given, including the effect the velocity boundary conditions have on the viscosity, the sensitivity of the results to the velocity profile fitting procedure, the effect of preequilibration of the Gaussian profile, and the effect the system size and box shape have on the accuracy and speed of the method. It is shown that the MIR method can be extended to treat multiatom systems without loss of accuracy or computational efficiency.     

Light-mediated transformations of olefins into alcohols: reactions of hydroxyl radicals with cycloalkenes

Reactions of hydroxyl radicals, generated by photodecomposition of hydrogen peroxide in acetonitrile, with a wide variety of cycloalkenes have been examined. The results show that the major reaction is the addition of hydroxyl radicals to the less substituted end of the double bond, furnishing the secondary alcohols. The reactivity pattern and the observed regio- and stereoselectivity clearly reveal that the steric parameters associated with the substrates play a dominant role in directing the addition reactions. More importantly, this study led to the development of a new methodology for the facile conversions of olefins essentially into secondary alcohols, and includes a few examples which demonstrate the potential of the method.     

DC Electrical Study of Modified PMMA,PVC and their Blend

Summary: Thin films of high molecular weight PMMA, PVC and their blend were prepared with solution cast method. Further they were modified by adding Camphor Sulphonic Acid (CSA) to them. DSC studies indicate single glass transition temperature (Tg) for unmodified as well as modified blends indicating the miscibility of polymers. FTIR studies show the interaction between CSA-PVC, CSA-PMMA, CSA-(PVC+PMMA) blend. The D.C. electrical study was carried out at various temperatures from room temperature (307 K) to 373 K. After modification the variation of DC conductivity (σ) is found to decrease in PVC and the PVC-PMMA blend whereas it is found to increase in PMMA with rise in temperature.     

Chain Ordering in the Nematic Phase of 40ba

From the intensity profile of the X-ray diffraction pattern in the nematic phase of 40BA it is inferred that the alkoxy chains have an orientational order.     

Ultrasound promoted asymmetric transfer hydrogenation of ketones using Ru(II)arene/amino alcohol catalyst system

Asymmetric transfer hydrogenation of ketones using Ru(II)arene/amino alcohol catalyst system proceeds with significant rate enhancement by ultrasound promotion. Comparison of the silent reactions carried out at 25 degrees C with reactions under sonochemical activation at 25 degrees C clearly showed enhancement in catalytic activity by 5-10 times without significantly affecting the enantioselectivity.     

Determination of trace amounts of uranium in plutonium oxide by wavelength dispersive X-ray fluorescence spectrometry

Journal of Radioanalytical and Nuclear Chemistry - 149Tb, 152Tb, 155Tb and 161Tb can cover all the modalities of diagnostic and therapeutic purposes of nuclear medicine. The production cross...     

Process intensification using cavitation: optimization of oxidation conditions for synthesis of sulfone

Cavitation can be effectively used for intensification of chemical reactions due to the production of free radicals and conditions of high temperatures and pressures locally. In the present work, use of cavitation for the intensification of the synthesis of sulfone has been explored. The oxidation of thioether or sulfide to synthesize corresponding sulfone with 30% H₂O₂ as an oxidant was studied under acoustic cavitation and the results have been compared with the conventional approach based on the use of mechanical agitation. The aim has been also to optimize the different operating conditions viz. molar ratio of reactants to the oxidizing agent, type of the catalyst as well as its concentration, type of the solvent and the reactant concentration, so as to maximize the degree of intensification. It was observed that under the optimized conditions of sonication, the yield of sulfone was about five to six times higher as compared to the conventional approach of using mechanical agitation only.