The Madras Triple Helix:Origins and Current Status

Madras triple helix’ was the name assigned by the scientific community in the West, to the molecular model proposed for the fibrous protein collagen, by G N Ramachandran’s group at the University of Madras. As mentioned jocularly in a recent retrospective of this work by Sasisekharan and Yathindra [1], the term was possibly coined due to the difficulty of Western scientists in pronouncing the Indian names of Ramachandran and his associates. The unravelling of the precise nature of collagen structure indeed makes for a fascinating story and as succinctly put by Dickerson [2]: “... to trace the evolution of the structure of collagen is to trace the evolution of fibrous protein crystallography in miniature”. This article is a brief review highlighting the pioneering contributions made by G N Ramachandran in elucidating the correct structure of this important molecule and is a sincere tribute by the author to her mentor, doctoral thesis supervisor and major source of inspiration for embarking on a career in biophysics

Behavior of Ca(OH)2/CaO pellet under dehydration and hydration

With construction of a thermochemical energy conversion prototype system to store solar heat, thermal dissociation of pellets of Ca(OH)2 and hydration of CaO have been investigated in some detail for its application to the system. The inorganic substance is very attractive as a material for long term heat storage, but molar density changes associated with the reaction are fairly large. Therefore, this factor has been taken into account in the kinetic equation. The importance of additives and pellet size has been discussed considering reactivity and strength of pellets. An analysis has been attempted when chemical reaction is important. The deformation of pellets was observed during hydration.

Contraceptive vaccines: current status and problems in mass application

Progress in the development of contraceptive vaccines for males and females is reviewed. Based on the criteria which need to be met with, none of the proposed candidate antigens meets the requirements for use as a contraceptive vaccine for human application. One of the major problems is the need for periodic injections to maintain required titre and use of an alternate method until effective titres are obtained. Some of the problems associated with active immunization approach can be overcome by the use of preformed, highly specific, potent antibodies. Some progress has been achieved in this direction by the use of humanized single chain monoclonal antibodies to human chorionic gonadotropin.

Status Survey of the Malabar Pied Hornbill in the Dandeli Region, Northern Western Ghats, India

The Malabar Pied Hornbill, Anthracoceros coronatus, is a near threatened species, endemic to the tropical deciduous forests of central and southern India and Sri Lanka. The Dandeli region in Karnataka (India) is believed to be the last stronghold of this species in the Western Ghats biodiversity hotspot. Being a rapidly developing area with a growing human population, the threats to this species and their habitat are mounting, especially due to a large number of hydroelectric projects and habitat fragmentation caused by paper and plywood industries. This study evaluated the change in population status of the Malabar Pied Hornbill over a 23 year period and defined priorities for the long term conservation and monitoring of hornbills in Dandeli. Encounter rates of hornbills were also analysed in relation to the density and species richness of trees and fruiting trees, basal area, canopy cover and distance from river. Hornbill encounters were not significantly different compared to the earlier study carried out by Reddy in 1988, but were significantly different across the five sites in the current study. Higher numbers of hornbills were encountered closer to the river, but these results were only marginally significant. The mean numbers of hornbills recorded at the two roost sites identified in Dandeli were 26 +/- 4.47 (n=16 counts) and 31.78 +/- 3.53 (n=14 counts) respectively. The study also helped build local awareness about the species, train local Forest Department staff in monitoring hornbills and develop a management plan for its conservation.

Space vector pulsewidth modulation — A status review

The technique of space vector pulsewidth modulation (SVM) is reviewed. The basic principle of SVM is derived and is compared with sine-triangle PWM. Operation in the overmodulation range is explained. Extension of SVM to other inverter-motor combinations such as three level inverters and split phase motors are discussed.

Biological water: Femtosecond dynamics of macromolecular hydration

The unique features of a macromolecule and water as a solvent make the issue of solvation unconventional, with questions about the static versus dynamic nature of hydration and the, physics of orientational and translational diffusion at the boundary. For proteins, the hydration shell that covers the surface is critical to the stability of its structure and function. Dynamically speaking, the residence time of water at the surface is a signature of its mobility and binding. With femtosecond time resolution it is possible to unravel the shortest residence times which are key for the description of the hydration layer, static or dynamic. In this article we review these issues guided by experimental studies, from this laboratory, of polar hydration dynamics at the surfaces of two proteins (Subtilisin Carlsberg (SC) and Monellin). The natural probe tryptophan amino acid was used for the interrogation of the dynamics, and for direct comparison we also studied the behavior in bulk water - a complete hydration in 1 ps. We develop a theoretical description of solvation and relate the theory to the experimental observations. In this - theoretical approach, we consider the dynamical equilibrium in the hydration shell, defining the rate processes for breaking and making the transient hydrogen bonds, and the effective friction in the layer which is defined by the translational and orientational motions of water molecules. The relationship between the residence time of water molecules and the observed slow component in solvation dynamics is a direct one. For the two proteins studied, we observed a "bimodal decay" for the hydration correlation function, with two primary relaxation times: ultrafast, typically 1 ps or less, and longer, typically 15-40 ps, and both are related to the residence time at the protein surface, depending on the binding energies. We end by making extensions to studies of the denatured state of the protein, random coils, and the biomimetic micelles, and conclude with our thoughts on the relevance of the dynamics of native structures to their functions.

Manipulation of the Hydration Levels in Minerals of Sodium Cadmium Bisulfate toward the Design of Functional Materials

Several variants of hydrated sodium cadmium bisulfate, Na(2)Cd(2)(SO(4))(3) center dot 3H(2)O, Na(2)Cd(SO(4))(2) center dot 2H(2)O, and Na(2)Cd(SO(4))(2) center dot 4H(2)O have been synthesized, and their thermal properties followed by phase transitions have been invesigated. The formation of these phases depends on the stochiometry and the time taken for crystallization from water. Na(2)Cd(2)(SO(4))(3)center dot 3H(2)O, which crystallizes in the trigonal system, space group P3c, is grown from the aqueous solution in about four weeks. The krohnkite type mineral Na(2)Cd(SO(4))(2) center dot 2H(2)O and the mineral astrakhanite, also known as blodite, Na(2)Cd (SO(4))(2)center dot 4H(2)O, crystallize concomittantly in about 24 weeks. Both these minerals belong to the monoclinic system(space group P2(1)/c). Na(2)Cd(2)(SO(4))(3)center dot 3H(2)O loses water completely when heated to 250 degrees C and transforms to a dehydrated phase (cubic system, space group I (4) over bar 3d) whose structure has been established using ab initio powder diffration techniques. Na(2)Cd(SO(4))(2)center dot 2H(2)O transforms to alpha-Na(2)Cd(SO(4))(2) (space group C2/c) on heating to 150 degrees C which is a known high ionic conductor and remains intact over prolonged periods of exposure to moisture (over six months). However, when alpha-Na(2)Cd(SO(4))(2) is heated to 570 degrees C followed by sudden quenching in liquid nitrogen beta-Na(2)Cd(SO(4))(2) (P2(1)/c) is formed. beta-Na(2)Cd(SO(4))(2) takes up water from the atmosphere and gets converted completely to the krohnkite type mineral in about four weeks. Further, beta-Na(2)Cd(SO(4))(2) has a conductivity behavior comparable to the a-form up to 280 degrees C, the temperature required for the transformation of the beta- to alpha-form. These experiments demonstrate the possibility of utilizing the abundantly available mineral sources as precursors to design materials with special properties.

The Asian elephants Elephas maximus of Cat Tien National Park, Vietnam: status and conservation of a vanishing population

This study updates the status and conservation of the Endangered Asian elephant Elephas maximus in Cat Tien National Park, Vietnam. Line transect indirect surveys, block surveys for elephant signs, village surveys of elephant-human conflict incidents, guard-post surveys for records of sightings, and surveys of elephant food plants were undertaken during the dry and wet seasons of 2001. A minimum of 11 elephants and a maximum of 15-17 elephants was estimated for c. 500 km2 of the Park and its vicinity. The elephants are largely confined to the southern boundary of the Park and make extensive use of the adjoining La Nga State Forest Enterprises. During the dry season the elephants depend on at least 26 species of wild and cultivated plants, chiefly the fruits of cashew. Most of the villages surveyed reported some elephant-human conflict. Two adult male elephants seem to cover a large area to raid crops, whereas the family groups restrict themselves to a few villages; overall, the conflict is not serious. Since 2001 there have been no reports of any deaths or births of elephants in the Park. We make recommendations for habitat protection and management, increasing the viability of the small population, reducing elephant-human conflicts, and improving the chances of survival of the declining elephants of this Park. The Government has now approved an Action Plan for Urgent Conservation Areas in Vietnam that calls for the establishment of three elephant conservation areas in the country, including Cat Tien National Park.