Empirical relation and establishment of shell effects in (<Emphasis Type="Italic">n</Emphasis>, 2<Emphasis Type="Italic">n</Emphasis>) reaction cross-sections at 14 MeV

The experimental data for (n, 2n) reaction cross-sections around 14 MeV neutron energy have been collected from the literature and analysed for the isotopes having 1 ≤ Z ≤ 82. The empirical relations for the reaction cross-sections have been obtained, which show fairly good fits with the experimental values. The shell effects have been established at magic nucleon numbers for (n, 2n) reaction cross-sections around 14 MeV neutron energy. The odd-even effects have also been observed as the cross-sections for odd-mass nuclei are higher than their neighbouring even-even nuclei.      

Electrochemical synthesis of multi-armed CuO nanoparticles and their remarkable bactericidal potential against waterborne bacteria

Copper (II) oxide multi-armed nanoparticles composed of 500–1000 nm long radiating nanospicules with 100–200 nm width near the base and 50–100 nm width at the tapered ends and ~25 nm thickness were synthesized by electrochemical deposition in the presence of an oxidant followed by calcination at 150 °C. The nanoparticles were characterized using SEM/EDX for morphology and composition, Raman spectroscopy for compound identification, and broth culture method for antibacterial efficacy. The CuO nanoparticles have shown remarkable bactericidal efficacy against Gram-positive and -negative waterborne disease causing bacteria like Escherichia coli, Salmonella typhi, staphylococcus aureus and Bacillus subtilis. E. coli has been chosen as representative species for waterborne disease causing bacteria. In antibacterial tests 500 μg/mL nano CuO killed 3 × 10⁸ CFU/mL E. coli bacteria within 4 h of exposure. Moreover, 8.3 × 10⁶ CFU/mL E. coli were killed by 100 and 10 μg/mL nano CuO within 15 min and 4 h of exposure, respectively. Antibacterial activity of nano CuO has been found many-fold compared with commercial bulk CuO. The fate of nanoparticles after antibacterial test has also been studied. The synthesized CuO nanoparticles are expected to have potential antibacterial applications in water purification and in paints and coatings used on frequently touched surfaces and fabrics in hospital settings.     

Aqua mediated indium(III) chloride catalyzed synthesis of fused pyrimidines and pyrazoles

The utilization of water as solvent and indium trichloride as promoter for the three-component combinatorial synthesis of a variety of bioactive pyrimidine and pyrazole derivatives (2–10) from aldehydes, 1,3-dicarbonyl compounds, and electron-rich amino heterocycles like 6-amino-1,3-dimethyl uracil and 3-methyl-1-phenyl-1H-pyrazol-5-amine catalyzed by indium trichloride under reflux has been studied. A new class of pyrimidine derivatives (2) has also been synthesized and the structure was confirmed by single crystal X-ray analysis. The reactions are environmentally benign, reaction product could be isolated easily and the catalyst could be recycled, which makes it an appealing synthetic protocol.     

Bulk Viscosity and Decaying Vacuum Density in Friedmann Universe

We present an isotropic and homogeneous flat cosmological model for bulk viscous fluid distribution. We consider the vacuum density proportional to Hubble expansion parameter and time dependent bulk viscosity related to the velocity and acceleration of universe. The behaviour of resulting solutions are in accordance with recent astronomical observations. The model obtained evolves with a decelerating expansion followed by late time acceleration. Cosmological term Λ being very large at initial epoch relaxes to a genuine cosmological constant asymptotically. Presence of bulk viscosity prevents the matter density to vanish asymptotically and the matter density continues to be of the order of vacuum density after a finite time. Thus, we obtain a universe having the possibility of cosmic coincidence.     

Asymmetric aldol additions: use of titanium tetrachloride and (-)-sparteine for the soft enolization of N-acyl oxazolidinones, oxazolidinethiones, and thiazolidinethiones.

Asymmetric aldol additions using chlorotitanium enolates of N-acyloxazolidinone, oxazolidinethione, and thiazolidinethione propionates proceed with high diastereoselectivity for the Evans or non-Evans syn product depending on the nature and amount of the base used. With 1 equiv of titanium tetrachloride and 2 equiv of (-)-sparteine as the base or 1 equiv of (-)-sparteine and 1 equiv of N-methyl-2-pyrrolidinone, selectivities of 97:3 to > 99:1 were obtained for the Evans syn aldol products using N-propionyl oxazolidinones, oxazolidinethiones, and thiazolidinethiones. The non-Evans syn aldol adducts are available with the oxazolidinethione and thiazolidinethiones by altering the Lewis acid/amine base ratios. The change in facial selectivity in the aldol additions is proposed to be a result of switching of mechanistic pathways between chelated and nonchelated transition states. The auxiliaries can be reductively removed or cleaved by nucleophilic acyl substitution. Iterative aldol sequences with high diastereoselectivity can also be accomplished.     

INAA of toxic elements in coal and their transfer into environments

An instrumental neutron activation analytical (INAA) technique is described for the determination of 26 toxic and other trace elements in Eastern Coal (NBS SRM-1632a), local coal and its ash. The coal ash was produced by heating coal at 750°C in a muffled furnace. The transfer of these elements to the environment on the complete compustion of coal is estimated from the difference between the elemental concentration of coal and its ash.     

Coordination Chemistry of N,N,N′,N′-Tetraethylpyridine-2,6-Dithiocarboxamide: Crystal and Molecular Structure of Chloro(N,N,N′,N′-Tetraethylpyridine-2,6-Dithiocarboxamide) Cobalt(II) Monocations and Di-μ-Chlorobis [Dichlorocobaltate(II)] Dianions, [{Co(DETP)Cl}+]2[Co2Cl4(μ 2-Cl2)]2−

Transition Metal Chemistry - The crystal and molecular structure of a 2:1 complex of CoCl2 with DETP (N,N,N′,N′-tetraethylpyridine-2,6-dithiocarboxamide), has been determined. The...     

Low-limit photo-acoustic detection of solid RDX and TNT explosives with carbon dioxide laser

We report the absorption spectra of RDX and TNT explosive samples in solid form at room temperature using a carbon dioxide laser-based photo-acoustic technique. A continuous wave ¹²C¹⁶O₂ laser, tunable between the 9.25–10.74 μm wavelength region, was used as an energy source. Interference-free limits of detection of solid RDX and TNT in simulated samples are estimated to be 10.0 and 16.5 ppbw, respectively. Published in Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 113–118, January–February, 2006.