National Chemical Laboratory

About: National Chemical Laboratory is a facility organization based out in Pune, Maharashtra, India. It is known for research contribution in the topics: Catalysis & Nanoparticle. The organization has 8891 authors who have published 14837 publications receiving 387600 citations.

Direct synthesis of hydrogen peroxide from hydrogen and oxygen: An overview of recent developments in the process

Abstract: Hydrogen peroxide (H2O2) is an important commodity chemical and its demand is growing significantly in the chemical synthesis due to its “green” character. Currently, H2O2 is produced almost exclusively by the anthraquinone auto-oxidation (AO) process. The AO process involves indirect oxidation of hydrogen and thus avoids potentially explosive H2/O2 mixture. However, this large-scale process presents significant safety issues associated with the transport of bulk H2O2. Moreover, the AO process can hardly be considered an environmentally friendly method. In view of this, more economical and environmentally cleaner routes have been explored for the production of H2O2. The liquid-phase catalytic direct synthesis of H2O2 from H2 and O2 offers an attractive green technology for small-scale/on-site production of H2O2. However, the direct synthesis process suffers from two major drawbacks: (i) potential hazards associated with H2/O2 mixtures and (ii) poor selectivity for H2O2 because the catalysts used for H2O2 synthesis are also active for its decomposition and hydrogenation to water as well as for H2 combustion. These serious issues and the recent developments in the direct H2O2 synthesis are discussed in this review. The roles of protons (H+) and halide ions in promoting the H2O2 selectivity are also examined in detail.

Putative polyadenylation signals in nuclear genes of higher plants: a compilation and analysis

Abstract: In animal and viral pre-mRNAS, the process of polyadenylation is mediated through several cis-acting poly (A) signals present upstream and downstream from poly (A) sites. The situation regarding polyadenylation of higher plant pre-mRNAS, however, has remained obscure so far. In this paper, a search for putative poly (A) signals is made by considering the published data from 46 plant genomic DNA sequences. Certain domains in the 3' untranslated regions from nuclear genes of higher plants were compiled and occurrence of sequence motifs such as AATAAA, CAYTG, YGTGTTYY and YAYTG was scored in relation to poly (A) sites. Moreover, consensus sequences for important regions in the 3' untranslated sequences and poly (A) signals were also deduced from the data. It was inferred that sequence motifs similar to poly (A) signals exist around poly (A) sites but some of them are in entirely different spatial relationship than observed in other eukaryotes. This indicates their probable non-involvement in the process of polyadenylation in higher plants necessitating a functional analysis approach to define the plant specific poly (A) signals.

Gold Nanotriangles Biologically Synthesized using Tamarind Leaf Extract and Potential Application in Vapor Sensing

Abstract: The size and shape dependent electronic and chemical properties of metal nanoparticles has drawn the attention of chemists, physicists, biologists, and engineers who wish to use them for the development of new generation nanodevices. In this article, we report the synthesis of gold nanotriangles using tamarind leaf extract as the reducing agent. On treating aqueous chloroauric acid solution with tamarind leaf extract, rapid reduction of the chloroaurate ions is observed leading to the formation of flat and thin single crystalline gold nanotriangles. Atomic force microscopy analysis of the gold nanotriangles indicated that they ranged in thickness from 20 to 40 nm. These gold nanotriangles with unique and highly anisotropic planer shapes might find application in photonics, optoelectronics, and optical sensing. We investigated the effect of different organic solvent vapors like methanol, benzene and acetone on the conductivity of tamarind leaf extract reduced gold nanotriangles. I‐V characteristics measure...

Requirement for mast cell growth factor for primordial germ cell survival in culture

Abstract: Mast-cell growth factor (MGF) is encoded by the murine steel (Sl) locus and is a ligand for the tyrosine kinase receptor protein encoded by the proto-oncogene c-kit at the murine dominant white spotting (W) locus. Mutations at both these loci affect mast cells, primordial germ cells (PGCs), haemopoietic stem cells and melanocytes. In many Sl and W mutants, the rapid proliferation of PGC that normally occurs between day 7 and 13.5 of embryonic development fails to occur. As c-kit is expressed in PGCs while MGF is expressed in the surrounding mesenchyme, MGF might promote the proliferation of PGCs. Here we report that MGF is essential for PGC survival in culture, but does not stimulate PGC proliferation. Moreover, whereas both the transmembrane and soluble proteolytic cleavage forms of MGF stimulate mast-cell proliferation, soluble MGF has a relatively limited ability to support survival of PGCs in culture, thus explaining the sterility in mice carrying the steel-dickie (Sld) mutation, which encodes only a soluble form of MGF, and providing a functional role for a transmembrane growth factor.