A Novel System for Growth of Single Crystals from the Melt with an Innovative New Pulling Mechanism

665-670This paper describes a crystal growth system employing novel concepts in fabrication of a high temperature furnace, thermocouples and a novel crystal pulling mechanism. This has reduced the costs substantially, without compromising the quality of grown crystals. The core of the furnace, a wooden cylindrical dummy had been prepared with equi-spaced helical groves with widths equaling the diameter of the heating wire on its outer surface machined by a lathe machine. The Kanthal heating wire was wound in the groves. It was covered with a thick layer of natural clay available locally. After the clay had dried up, an electric current was passed through the heating wire and the wooden frame was burnt out. A thick layer of the clay was applied on the inner and the outer surfaces. The furnace can operate at temperatures up to about 1000 °C. The temperature was measured with a chromel-alumel thermocouple prepared by an ingenious spot-welding technique established in the laboratory. The seed holder was hanged above the melt kept in the crucible with help of a float kept in a water container, which has a small tap at the bottom. When the tap is opened the float goes down and the seed assembly goes up. In this manner a quality pulling system, without any motor has been developed and reported here. It has been possible to grow good quality crystals of potassium chloride with excellent diameter control

A Novel System for Growth of Single Crystals from the Melt with an Innovative New Pulling Mechanism

This paper describes a crystal growth system employing novel concepts in fabrication of a high temperature furnace, thermocouples and a novel crystal pulling mechanism. This has reduced the costs substantially, without compromising the quality of grown crystals. The core of the furnace, a wooden cylindrical dummy had been prepared with equi-spaced helicalgroves with widths equaling the diameter of the heating wire on its outer surface machined by a lathe machine. The Kanthal heating wire was wound in the groves. It was covered with a thick layer of natural clay available locally. After the clay had dried up, an electric current was passed through the heating wire and the wooden frame was burnt out. A thick layer of theclay was applied on the inner and the outer surfaces. The furnace can operate at temperatures up to about 1000 °C. The temperature was measured with a chromel-alumel thermocouple prepared by an ingenious spot-welding technique established in the laboratory. The seed holder was hanged above the melt kept in the crucible with help of a float kept in awater container, which has a small tap at the bottom. When the tap is opened the float goes down and the seed assembly goes up. In this manner a quality pulling system, without any motor has been developed and reported here. It has been possible to grow good quality crystals of potassium chloride with excellent diameter control

Fertility and Mortality Differentials among the Tribal Population Groups of Bastar District, Madhya Pradesh, India

Selection potential based on differential fertility and mortality has been computed for Muria, Madia, Halba and Bhattra tribal population groups of Bastar District of Madhya Pradesh inhabiting similar geo-climatic and environmental conditions. It is evident that irrespective of the methodology, the total index of selection was found to be highest among Bhattras (0.637) followed by Madias (0.558), Murias (0.514) and Halbas (0.410). The relative contribution of the mortality component to the index of total selection is higher than the corresponding fertility component in all the tribal groups except Bhattras where the fertility component exceeds mortality component. Analysis of the post-natal mortality components indicates that childhood mortality constitutes the bulk of post-natal mortality, suggesting that children below 5 years need better health care among these tribal groups

EXPLOITING TEMPERATURE-DEPENDENCE TO IMPROVE SELECTIVITY IN MEMBRANE-BASED PLASMAPHERESIS

Temperature effects on cross-flow membrane plasmapheresis have been investigated with the help of hydrophillic polyvinylidene fluoride (PVDF) Durapore membranes of pore size 0.65 mu m and an effective filtration area 30 cm(2), using a thin-channel device (Minitan-S, Millipore Inc., U.S.A.) and goat's blood as the working fluid. The filtration and sieving properties have been characterized by evaluating normal saline (0.9 g%) flux and the sieving coefficients of albumin, immunoglobulins, and fibrinogen respectively. Runs were performed at 10 +/- 1, 20 +/- 1, 30 +/- 1 and 40 +/- 1 degrees C, the various filtration parameters were measured and samples of the feed and permeate were collected during steady state. It is seen that the ''effective'' pore size increases with temperature increase thereby increasing flux, sieving and fouling. Exploiting temperature effects can possibly help modify the sieving spectrum in membrane-based plasmapheresis

Anti-depressant-like activity of a novel serotonin type-3 (5-HT₃) receptor antagonist in rodent models of depression

619-626N-Cyclohexyl-3-methoxyquinoxalin-2-carboxamide (QCM-13), a novel 5-HT3 antagonist identified from a series of compounds with higher pA2 (7.6) and good log P (2.91) value was screened in rodent models of depression such as forced swim test (FST), tail suspension test (TST), interaction studies with standard anti-depressants and confirmatory studies such as reversal of parthenolide induced depression and reserpine induced hypothermia. In FST (2 and 4 mg/kg) and TST (2 and 4 mg/kg), QCM-13 significantly reduced the duration of immobility in mice without affecting the base line locomotion. QCM-13 (2 and 4 mg/kg) was also found to have significant interaction with standard anti-depressants (fluoxetine and bupropion in FST and TST respectively). Further, reversal of parthenolide induced depression in mice and reserpine induced hypothermia in rat models indicate the serotonergic influence of QCM-13 for anti-depressant potential