Synthesis of fullerene@gold core-shell nanostructures

A "direct encapsulation" method was developed for the synthesis of highly stable water-soluble fullerene@gold core-shell nanostructures, with gold nanoshells showing either closed or porous morphology. This gold nano-shell coating formed a "nano-oven", capable of decomposing encapsulated fullerene molecules rapidly when irradiated by laser. We envisaged this being a useful tool for chemical reactions as well as a novel scaffold for nano-material synthesis.     

The effect of the thickness of the porous material on the parallel plate channel flow when the walls are provided with non-erodible porous lining

Flow through a channel whose walls are lined with non-erodible porous material is investigated using Beavers and Joseph slip boundary condition. It is shown that the effect of porous lining is to increase the mass flow rate and to decrease the friction factor.     

Control strategies for laser separation of carbon isotopes

Laser isotope separation (LIS) by infrared laser chemistry of polyatomic molecules has come a long way since its discovery. The last decade has seen considerable efforts in scaling up of the process for light elements like carbon, oxygen and silicon. These efforts aim at ways to improve both the enrichment factor and the throughput. The achievement is quite significant especially for carbon isotope separation wherein macroscopic operating scales have been realized. We report our studies on the IR laser chemistry of two promising systems, viz. neat CF₂HCl and CF₃Br/Cl₂. We have investigated conditions for optimizing the dissociation yield and selectivity using natural samples containing l.l%C-13.Wealso highlight our current efforts for scaling up the process. These include the design aspects of a photochemical reactor with multipass refocusing Herriott optics for efficient photon utilization, development of a cryogenic distillation set up and a preparative gas chromatograph for large scale separation/collection of the isotopically enriched photoproduct in the post-irradiation stage.     

Exact Bianchi type V imperfect fluid solutions

It is shown that it is sufficient to solve a single first order differential equation to determine exact Bianchi type V imperfect fluid solutions of Einstein's field equations. Two exact solutions are presented in this paper. One of these two solutions corresponds to the case when the anisotropic pressure tensor is proportional to the shear tensor. This proportionality, it is shown, is a necessary but not a sufficient condition for the absence of heat flow in a Bianchi type V universe. It is also observed that the presence of heat flow necessarily introduces anisotropy in a Bianchi type V universe.     

A simple spectrophotometric method for the determination of nylidrin hydrochloride, isoxsuprine hydrochloride and salbutamol sulphate in pharmaceutical preparations

A simple spectrophotometric method for the determination of nylidrin hydrochloride, isoxsuprine hydrochloride and salbutamol sulphate is described, based on measurement of the orangeyellow species produced when the drugs are coupled with diazotized benzocaine (p-aminoethyl benzoate) in trimethylamine medium. The method is applicable over the range 1-12 mug ml for isoxsuprine hydrochloride and nylidrin hydrochloride and 1-8 mug ml for salbutamol sulphate. The method is a modification of the Bratton-Marshall reaction and is simple, reproducible, accurate and more sensitive than those cited in the literature.     

An extractive spectrophotometric method for the determination of tetramisole hydrochloride in pharmaceutical preparations

A simple extractive photometric method for the determination of tetramisole hydrochloride in pharmaceutical preparations is described. The method uses the formation of coloured complexes of the drug with reagents such as Solochrome Dark Blue, Solochrome Black T, Bromocresol Purple, Bromothymol Blue, Bromophenol Blue and Bromocresol Green in an acidic buffer. The ion-pair complexes formed are quantitatively extracted into chloroform under the experimental conditions.     

Kinetics of oxidation of aromatic ketones by peroxydisulphate catalysed by silver ions

The rates of peroxydisulphate oxidation of aromatic ketones have been found to be first order with respect to peroxydisulphate as well as of silver (I), but independent of the aromatic ketone. The effect of substituents on the rate of oxidation has been evaluated. The logk values have been plotted against the σ⁺ values, with ρ⁺=? 0.14. The reactivities of 1- and 2-acetyl naphthalene have been discussed. A mechanism of the oxidation of aromatic ketones based on reactive Ag⁺² species has been suggested.     

Kinetics of the thallic ion oxidation of olefins

The kinetics of oxidation of chalkone (phenyl styryl ketone) and cinnamaldehyde by T1 (III) acetate in aqueous acetic acid is of the first order in olefin and first order with respect to the oxidant. The parameters of the transition state theory have been computed. The rate of the reaction is strongly accelerated by increasing acid concentration. The reaction rate is also retarded by added sodium chloride and sodium acetate. The results have been interpreted in the light of the ionic mechanism considering T1 (OAc)₃ to be the active oxidant in aqueous acetic acid.