Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

Intramolecular Valence and Spin Interaction in meso and rac Diastereomers of a p-Quinonoid-Bridged Diruthenium Complex

Abstract: The complexes meso- and rac-[(acac)2Ru(μ-L)Ru(acac)2]n, 1 and 2, where L2− = 1,4-dioxido-2,3-bis(3,5-dimethylpyrazol-1′-yl)benzene and acac− = 2,4-pentanedionato, were characterized structurally, magnetically, electrochemically, and spectroscopically as well as spectroelectrochemically (UV−vis−NIR, EPR) in the accessible redox states (n = 0, +, −, 2−) Due to steric interference, the neutral compounds contain a severely twisted L2− bridging ligand with 43−48° dihedral angles between the planes of the hydroquinone dianion and those of the ortho positioned pyrazolyl substituents The difference between meso and rac isomers is rather pronounced in terms of the redox potentials (easier oxidation and reduction of the rac form 2) and with respect to the absorption spectra of the oxidized states Susceptibility and EPR measurements confirm the {RuIII(μ-L2−)RuIII} configuration of the neutral species, showing J values of −37 and −21 cm−1 for the spin−spin interaction between the ca 775 A separated metal centers

Binding of naproxen and amitriptyline to bovine serum albumin: biophysical aspects.

Abstract: Binding of the drugs naproxen (which is an anti-inflammatory) and amitriptyline (which is an anti-depressant) to bovine serum albumin (BSA) has been studied using isothermal titration calorimetry (ITC), in combination with fluorescence and circular dichroism spectroscopies. Naproxen is observed to bind more strongly to BSA than amitriptyline. The temperature-dependent ITC results indicate the interaction of one molecule of naproxen with more than one protein molecule. On the other hand, amitriptyline binds to BSA with a reaction stoichiometry that varies from 1:1.2 to 1:2.9. The van't Hoff enthalpy, which is calculated from the temperature dependence of the binding constant, agrees well with the calorimetric enthalpy in the case of naproxen binding to BSA, indicating adherence to a two-state binding process. However, their disagreement in the case of amitriptyline indicates conformational changes in the protein upon ligand binding, as well as with the rise in temperature. The spectroscopic results did not suggest appreciable conformational changes as a result of binding; hence, the discrepancy could be attributed to the temperature-induced conformational changes. With increases in the ionic strength, a reduction in the binding affinity of naproxen to BSA is observed. This suggests the prevailing electrostatic interactions in the complexation process. The preponderance of the hydrophobic interactions in the binding of amitriptyline to BSA is indicated by the absence of any dependence of the ionic strength. A predominance of electrostatic interactions in the case of naproxen binding to BSA and that of hydrophobic interactions in the case of amitriptyline binding to BSA is further strengthened by the results of the binding experiments performed in the presence of ionic and nonionic surfactants. The binding parameters indicate that Triton X-100 blocks the hydrophobic binding sites on BSA, thereby altering the binding affinity of amitriptyline toward BSA. A partial overlap of the binding sites for these drugs is indicated by the binding parameters obtained in the titration of naproxen to the amitriptyline-BSA complex and vice versa. Thus, the results provide a quantitative understanding of the binding of naproxen and amitriptyline to BSA, which is important in understanding their effect as therapeutic agents individually and in combination therapy.

Feature specific sentiment analysis for product reviews

Abstract: In this paper, we present a novel approach to identify feature specific expressions of opinion in product reviews with different features and mixed emotions The objective is realized by identifying a set of potential features in the review and extracting opinion expressions about those features by exploiting their associations Capitalizing on the view that more closely associated words come together to express an opinion about a certain feature, dependency parsing is used to identify relations between the opinion expressions The system learns the set of significant relations to be used by dependency parsing and a threshold parameter which allows us to merge closely associated opinion expressions The data requirement is minimal as this is a one time learning of the domain independent parameters The associations are represented in the form of a graph which is partitioned to finally retrieve the opinion expression describing the user specified feature We show that the system achieves a high accuracy across all domains and performs at par with state-of-the-art systems despite its data limitations

Simulation of rotary cement kilns using a one-dimensional model

Abstract: Rotary kilns are used to convert calcineous raw meal into cement clinkers. In this paper we present a one-dimensional model to simulate key processes occurring in solid bed of cement kilns. Solid-solid reactions occurring in cement kilns were modelled with a pseudo-homogeneous approximation. Variation of bed height and melt formation in burner zone within the kiln was accounted for. Energy balance (including conductive, convective and radiative heat transfer) was solved based on a quasi-steady state approximation. The mathematical model was first applied to a rotary calciner. The model predictions were verified by comparing them with the published experimental data. The model was then used to simulate performance of three industrial kilns. Numerical experiments were carried out to investigate influence of key operating and design parameters on energy consumption of kilns. The model was also used to explore the possibility of manipulating temperature profile within the kiln to reduce energy consumption in kiln per ton of clinker. Apart from providing a computationally efficient tool to simulate kiln performance, the model and the results discussed here will provide a useful basis for the development of comprehensive three-dimensional models of rotary cement kilns.