Arvind Kumar

Synthetic application of gold nanoparticles and auric chloride for the synthesis of 5-substituted 1H-tetrazoles

An effective one-pot, convenient gold catalyzed synthesis of 5-substituted 1H-tetrazoles has been discussed. The study demonstrated the comparative overview for utilization of gold(III) and gold nano-particles (spheres) as a catalyst. Detailed understandings of the mechanism, surface area effect (in reference to nanoparticles) of gold in the activation of nitriles for nucleophilic (3 + 2) cycloaddition of sodium azide to give the product have also been studied.

A comparative study between heterogeneous stannous chloride loaded silica nanoparticles and a homogeneous stannous chloride catalyst in the synthesis of 5-substituted 1H-tetrazole

Heterogeneous SnCl2–nano-SiO2 efficiently catalyzed 5-substituted 1H-tetrazole synthesis with excellent yield. The catalyst was characterized by using FT-IR, TGA, TEM, and EDX. It is widely applicable on aliphatic, aromatic, heteroaromatic and sterically hindered nitriles with five time recyclability. Being simple and an economically viable approach for the synthesis of SnCl2–nano-SiO2 are additional advantages.

An Escherichia coli Strain, PGB01, Isolated from Feral Pigeon Faeces, Thermally Fit to Survive in Pigeon, Shows High Level Resistance to Trimethoprim

In this study, of the hundred Escherichia coli strains isolated from feral Pigeon faeces, eighty five strains were resistant to one or more antibiotics and fifteen sensitive to all the antibiotics tested. The only strain (among all antibiotic-resistant E. coli isolates) that possessed class 1 integron was PGB01. The dihydrofolate reductase gene of the said integron was cloned, sequenced and expressed in E. coli JM109. Since PGB01 was native to pigeon’s gut, we have compared the growth of PGB01 at two different temperatures, 42°C (normal body temperature of pigeon) and 37°C (optimal growth temperature of E. coli; also the human body temperature), with E. coli K12. It was found that PGB01 grew better than the laboratory strain E. coli K12 at 37°C as well as at 42°C. In the thermal fitness assay, it was observed that the cells of PGB01 were better adapted to 42°C, resembling the average body temperature of pigeon. The strain PGB01 also sustained more microwave mediated thermal stress than E. coli K12 cells. The NMR spectra of the whole cells of PGB01 varied from E. coli K12 in several spectral peaks relating some metabolic adaptation to thermotolerance. On elevating the growth temperature from 37°C to 42°C, susceptibility to kanamycin (both strains were sensitive to it) of E. coli K12 was increased, but in case of PGB01 no change in susceptibility took place. We have also attempted to reveal the basis of trimethoprim resistance phenotype conferred by the dfrA7 gene homologue of PGB01. Molecular Dynamics (MD) simulation study of docked complexes, PGB01-DfrA7 and E. coli TMP-sensitive-Dfr with trimethoprim (TMP) showed loss of some of the hydrogen and hydrophobic interaction between TMP and mutated residues in PGB01-DfrA7-TMP complex compared to TMP-sensitive-Dfr-TMP complex. This loss of interaction entails decrease in affinity of TMP for PGB01-DfrA7 compared to TMP-sensitive-Dfr.

To measure the impacts on fault injection model in Component Based Software Development

Component based software engineering (CBSE) is gaining substantial interest in the software engineering community. A lot of research efforts have been devoted to the reliability, fault tolerance and complexity of components in CBSE. Testing the software component is an important approach which guarantees and enhances the reliability of components and as the reliability factor is directly related to the complexity of the components in CBSE. So automatically the complexity of the software will get improved. Merely selection of less complex and reliable components is not sufficient but we have to select the optimal components for the software system including the factor of fault tolerance. This paper proposes a testing strategy for finding the complexity of components and also a modified approach of fault injection model is proposed. Keywords—component testing;fault injection model;testing strategy

Polarographic study of mixed-ligand complex stability constants and kinetic parameters of reduction of Cr(III)-ethylenediamine-succinate system

Abstract Stability constants of the binary species Cr(III)-ethylenediamine, Cr(III)-succinate and mixed-ligand complex Cr(III)-ethylenediamine-succinate have been determined polarographically by the method of Sundaresan and Sundaram at 30±0.2°C at a constant ionic strength [μ = 0.6 M (NH 4 ClO 4 ]. The values of the stability constants obtained by this method are compared with those reported in the literature. The positive values of the mixing constants for the mixed-ligand complexes indicate that the mixed-ligand complexes are more stable than simple binary complexes. The reduction of the simple and mixed complexes is irreversible at a dropping mercury electrode: therefore, kinetic parameters like the standard rate constant, transfer coefficient and activation energy have also been calculated.