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- Author or Editor: S. Thomas x
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The montane (shola) grasslands of Western Ghats, South India are a component of a landscape mosaic including the better-studied shola forests. The conservation of the grasslands depends upon understanding their ecology. This review compiles available information and aims to evaluate the conservation potential of these grasslands. Most studies on these grasslands are descriptive in nature. There is little information regarding habitat heterogeneity, landscape configuration, natural disturbance, grazing and productivity in maintaining the grasslands. Succession is poorly understood because of the short-term nature of most studies. Human activities have historically influenced these grasslands and will continue to do so in more intensive manner. Threats to these grasslands include habitat loss, fragmentation, fires, and invasive species.
The thermal behaviour of pineapple leaf fibre (PALF) reinforced polyethylene composites was studied by thermogravimetric and dynamic mechanical thermal analysis. Fibre treatment was carried out using isocyanate, silane and peroxide to improve the interfacial adhesion between fibre and matrix. The effects of fibre loading and surface modification on the thermal properties were evaluated. It was found that at high temperature PALF degrades before the polyethylene matrix. The storage modulus increased with increase of fibre loading and decreased with increase of temperature. The treated fibre composites impart better properties compared to untreated system. Tan δ showed a distinct peak at low temperature ascribed to the glass transition temperature of polyethylene but no peak was observed for PALF fibre. The relative damping increased with fibre loading. Cole-Cole analysis was made to understand the phase behaviour of the composite samples.
Abstract
Bone provides an important source of forensic evidence. The storage conditions of bone have been recognised as a factor in maintaining the integrity of such evidence. Thermogravimetric analysis (TG) has been employed to examine the effects of storage environments and preparation methods on the structural properties of pig bones. A comparison of oven and freeze drying has been made to study the effect of storage conditions. A comparison has also been made of ground bone specimens with cut specimens. Freeze-dried hand ground specimens provided the most consistent results and, thus, this is the recommended method of preparation of bone specimens for TG analysis.
Abstract
Using the pulse radiolysis competition kinetic technique, OH radical rate constants with 12 metal DTPA complexes were determined in neutral aerated aqueous solutions. They are in the range of /1.3–5.9/×109 dm3 mol–1s–1. To a first approximation, the rate constant was found to decrease linearly with an increase in the field strength of the metal ion (q/r2).
Thermal decomposition of ethyl and isopropyl amine perchlorates has been studied by methods such as DTA, TG, isothermal weight loss measurements and the decomposition products have been analyzed in a mass spectrometer. Activation energy values for thermal decomposition have been calculated fromα-t plots. The proton transfer dissociation mechanism proposed for the thermal decomposition of ammonium perchlorate (AP) has been extended to explain the decomposition products of these twosubstituted amine perchlorates.
Abstract
The inorganic sorbent potassium cobalt(II) hexacyanoferrate(II) was tested for removal of radiocesium from alkaline salt solutions that are typical of intermediate level radioactive wastes generated at spent fuel reprocessing plants in India. Excellent results were obtained both in batch equilibration and column operation.
Summary
Galantamine hydrobromide was subjected to oxidative stress degradation using hydrogen peroxide and analyzed as per the chromatographic conditions described in European Pharmacopoeia. The drug showed considerable degradation at ambient temperature resulting in the formation of two degradation products at relative retention times (RRTs) 0.63 and 2.52. The minor degradant at RRT 0.63 was identified as galantamine N-oxide. The principal degradant formed at RRT 2.52 was found to be unknown and has not been reported previously. The unknown impurity was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by isolation using semi-preparative high-performance liquid chromatography (HPLC). The isolated impurity was characterized using one-dimensional, two-dimensional nuclear magnetic resonance spectroscopy (1D and 2D NMR) and elemental analysis (EA). The principal degradant was found to be formed due to the generation of bromine and subsequent attack on the aromatic ring via in situ reaction between hydrogen bromide and hydrogen peroxide. The unknown impurity was characterized as (4aS,6R,8aS)-5,6,9,10,11,12-hexahydro-1-bromo-3-methoxy-11-methyl-4aH-[1]benzofuro [3a,3,2-ef] [2] benzazepin-6-ol.
Abstract
Heat capacity measurements have been made to investigate the formation of two solid monolayers each of n-pentane, n-heptane and n-dodecane adsorbed on graphite, one at submonolayer coverages and the other coexisting with the liquid. At submonolayer coverages the monolayers are found to melt respectively at 99.8, 151.6, and 217.3 K, well below the bulk melting points. The monolayers coexisting with the liquid melted at 205.6 for heptane and at 287.8 K for dodecane, whereas no evidence was obtained for pentane on the formation of such solid monolayer above the bulk melting point. The order persisting in the liquid near the interface depends upon the length of the molecules. The dodecane monolayers showed another transitions below the melting points both at submonolayer and multilayer coverages.
Abstract
40% w/w sucrose/water solutions were analyzed by Modulated Differential Scanning Calorimetry [1] in the sub-ambient temperature region. At these temperatures, the solutions exhibit a complex, two-step thermal event. The lower-temperature event is believed to be the glass transition of the amorphous sucrose phase. The nature of the higher-temperature event is the subject of controversy. This event has been shown to have distinct second-order characteristics, and as such is believed to be a second T g. Others feel that this event is the onset of melting. The temperature region between these events contains a devitrification exotherm. Through the use of MDSC, both in scanning and stepwise quasi-isothermal modes, improved sensitivity and resolution of MDSC provides new insight into the nature of these transitions.