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.

Insights into the formation of hydroxyl ions in calcium carbonate:temperature dependent FTIR and molecular modelling studies

Abstract: This paper describes the use of temperature dependent FTIR spectroscopy and molecular modelling studies to establish the origin and the nature of surface hydroxyl ions on calcium carbonate. It has been demonstrated that two types (Type I, corresponding to a band at 3690 cm−1 and Type II, corresponding to a band at 3640 cm−1) of hydroxyl ions exist on calcium carbonate surfaces prepared by the carbonation method. Type I hydroxyl ions are ascribed to those of the unreacted calcium hydroxide (portlandite) present due to incomplete carbonation and Type II hydroxyl ions are ascribed to interstitial defects which are strongly associated with the calcium carbonate lattice framework. Interestingly, the calcium carbonate samples prepared by the solution method do not possess Type I/Type II hydroxyl ions. A molecular modelling exercise was carried out to generate the calcite 104 plane, and the different modes of adsorption of water on the calcite 104 plane were derived based on energy minimisation calculations. The possibility of replacement of a carbonate ion either by (i) two hydroxyl ions or (ii) a hydroxyl and a bicarbonate ion has been considered. The replacement of a carbonate ion by one hydroxyl and one bicarbonate ion is indicative of the presence of surface/interstitial defects on calcite (corresponding to Type II hydroxyl ions assigned by FTIR studies). A molecular description of hydroxylating calcite surfaces is discussed in detail and the results from the energy of formation at zero water coverage corroborate the above findings. The calculations also predict the formation of a maximum of two pairs of hydroxyl and bicarbonate ions over a surface area of 1.0 nm2, during chemisorption at low surface coverages.

Highly sensitive and selective LPG sensor based on α-Fe2O3 nanorods

Abstract: The α-Fe2O3 nanorods were successfully synthesized without any templates by calcining the α-FeOOH precursor in air at 300 °C for 2 h and their LPG sensing characteristics were investigated. The α-FeOOH precursor was prepared through a simple and low cost wet chemical route at low temperature (40 °C) using FeSO4·7H2O and CH3COONa as starting materials. The formation of α-FeOOH precursor and its topotactic transformation to α-Fe2O3 upon calcination was confirmed by X-ray diffraction measurement (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis. The α-Fe2O3 nanorods exhibited outstanding gas sensing characteristics such as, higher gas response (∼1746–50 ppm LPG at 300 °C), extremely rapid response (∼3–4 s), relatively slow recovery (∼8–9 min), excellent repeatability, good selectivity and lower operating temperature (∼300 °C). Furthermore, the α-Fe2O3 nanorods are able to detect up to 5 ppm for LPG with reasonable response (∼15) at the operating temperature of 300 °C and they can be reliably used to monitor the concentration of LPG over the range (5–60 ppm). The experimental results clearly demonstrate the potential of using the α-Fe2O3 nanorods as sensing material in the fabrication of LPG sensors. Plausible LP G sensing mechanism of the α-Fe2O3 nanorods is also discussed.

A support vector machine-based method for predicting the propensity of a protein to be soluble or to form inclusion body on overexpression in Escherichia coli

Abstract: Motivation: Inclusion body formation has been a major deterrent for overexpression studies since a large number of proteins form insoluble inclusion bodies when overexpressed in Escherichia coli. The formation of inclusion bodies is known to be an outcome of improper protein folding; thus the composition and arrangement of amino acids in the proteins would be a major influencing factor in deciding its aggregation propensity. There is a significant need for a prediction algorithm that would enable the rational identification of both mutants and also the ideal protein candidates for mutations that would confer higher solubility-on-overexpression instead of the presently used trial-and-error procedures. Results: Six physicochemical properties together with residue and dipeptide-compositions have been used to develop a support vector machine-based classifier to predict the overexpression status in E.coli. The prediction accuracy is ∼72% suggesting that it performs reasonably well in predicting the propensity of a protein to be soluble or to form inclusion bodies. The algorithm could also correctly predict the change in solubility for most of the point mutations reported in literature. This algorithm can be a useful tool in screening protein libraries to identify soluble variants of proteins. Avalibility: Software is available on request from the authors. Contact:balaji@iitcb.ac.in; vk.jayaraman@ncl.res.in Supplementary information: Supplementary data are available at Bioinformatics Online web site.