University of Madras

About: University of Madras is a education organization based out in Chennai, Tamil Nadu, India. It is known for research contribution in the topics: Ring (chemistry) & Lipid peroxidation. The organization has 8496 authors who have published 11369 publications receiving 211152 citations. The organization is also known as: Madras University & University of Chennai.

Solution of the linearized equations of multicomponent mass transfer: I

Abstract: The linearized equations of diffusion in a multicomponent system with flow and chemical reaction are shown to reduce to a set of equivalent binary diffusion equations. The concentrations and fluxes in a multicomponent system are described by linear combinations of appropriate solutions to the binary diffusion equation for steady and unsteady diffusion and convective mass transfer, laminar or turbulent. The rate of transfer of each component in a nonreacting n component system is a linear combination of the n-1 independent driving forces with proportionality constants which depend upon the multicomponent diffusion coefficients and appropriate binary mass transfer coefficients, while the concentration profile of each component is a linear combination of appropriate binary concentration profiles with proportionality constants which depend upon the multicomponent diffusion coefficients and the characteristic displacement from equilibrium of each component. The linearized theory is exact for small changes in concentration but needs further testing when the concentration changes and fluxes are large.

Study of hydrogen bonds in amino acids and peptides.

Abstract: An analysis of the various parameters associated with N-H… O type of hydrogen bonds has been made using data from reported crystal structures of amino acids and simple peptides. The different parameters at the donor and the acceptor ends have been suitably defined and evaluated. In some cases the analysis is done depending upon the chargedness or other characteristics of the donor and acceptor groups. Histograms giving the distribution of these parameters have been drawn and possible conclusions arrived at: 1. The distribution shows a maximum between 2.8 A and 2.9 A for the charged donor group and 2.9 A and 3.0 A for the uncharged donor group and is probably not dependent upon the charge on the acceptor group. 2. The angle between the directions CO and O. N tends to lie between two cones about C O with semi-vertical angles 40 and 70°. The orientation of the directions O. N and O. H with respect to the lone pair orbital directions on the acceptor oxygen atoms are analysed in detail using spherical polar coordinates. The analysis indicates that the group NH has a very strong tendency to point towards the acceptor oxygen atom. A general feature has been found in that the direction N-H tends to be closer to an orbital if the oxygen is an acceptor of two hydrogen bonds, while the direction tends to lie in between the orbitals when the acceptor oxygen is the receipient of only one hydrogen bond. The possible explanation of this on the basis of lone pair interaction is briefly discussed.