Pravinkumar,P A; Mohanan,P; K G Nair(Indian Journal of Radio & Space Physics, December , 1981)
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Abstract:
A technique for improving the coupling between a feed horn and reflector by using corrugated metallic flanges is presented.
Experimental data for flanges of varying parameters are given and theoretical explanation is supplemented
Virinder,Moudgil; Vera,Kruczak; Thomas,Eessalu; Paulose,C S; Michael,Taylor; Jeffrey,Hansen(Department of Biotechnology, May 14, 1981)
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Abstract:
Progesterone-receptor complex from freshly prepared hen oviduct cytosol acquired the ability to bind to
isolated nuclei, DNA-cellulose and ATP-Sepharose when incubated with 5-10 mM ATP at 4°C. The extent of
this ATP-dependent activation was higher when compared with heat-activation achieved by warming the progesterone-
receptor complex at 23 °C. The transformation of progesterone-receptor complex which occurred in a
time-dependent manner was only partially dependent on hormone presence. The ATP effect was selective in
causing this transformation whereas ADP, AMP and cAMP failed to show any such effect. The non-hydrolizable
analogs of ATP, adenosine 5'-[a,/3-methylene]triphosphate and adenosine 5-[/l,y-imido]triphosphate were also
found to be ineffective. Presence of 10 mM sodium molybdate blocked both the ATP and the heat-activation of
progesterone-receptor complex. Mn" or Mg` had no detectable effect on the receptor activation but the presence
of Ca" increased the extent of ATP-activation slightly. EDTA presence (> 5 mM) decreased the extent of
receptor activation by about 40 % and was, therefore, not included in the buffers used for activation studies.
Divalent cations were also ineffective when tested in the presence of 1- 5 mM EDTA. The
properties of progesterone-receptor complex remained intact under the above conditions when analyzed for
steroid-binding specificity and Scatchard analysis. However, the ATP-activated progesterone-receptor complex
lost the ability to aggregate when tested on low-salt sucrose gradients. ATP was equally effective in activating
the rat-uterine estradiol-receptor complex at 4 "C and influenced the transformation of 4-S receptor form into
a 5-S form when analyzed on sucrose gradients containing 0.3 M KCI. The presence of ATP also increased the
rate of activation of progesterone-receptor complex at 23 °C. These findings suggest a role for ATP in receptor
function and offer a convenient method of studying the process of receptor activation at low temperature and
mild assay conditions.
Syamaprasad, U; Vallabhan, C P G(Institute of Physics, 1981)
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Abstract:
Four distinct peaks are observed at 140, -26, -132 and -140°C in the sigma x* against T-1 plot between 200 and - 196°C for (NH4)3H(SO4)2, corresponding to four different phase
transitions of which the one at -26°C is reported here for the first time. Data on doped
samples reveal the charge transport mechanism in the crystal.
Indrapal Singh,N; Shrivastaw,K P; Paulose,C S; Subba Rao,K(Department of Biotechnology, November 13, 1981)
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Abstract:
Acid and alkaline DNase activities in partially purified preparations from young and old chick brain were measured. The
specific activity of acid DNase from old brain was lower by about 50% than that of enzyme from young brain , whereas alkaline
DNase exhibited only marginal difference in activity of the two preparations . Study of various properties, viz. heat-stability
and effect of exogenous compounds like Mg=', Hgl', Zn=', PHM B , on these enzymes revealed that while acid DNase in old
brain is more susceptible to heat and heavy metal ion inhibition , alkaline DNase is devoid of any age-dependent variation in
its properties.
Syamaprasad, U; Vallabhan, C P G(Elsevier, May , 1981)
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Abstract:
Anomalous variations of d.c. electrical conductivity with temperature are observed in ammonium sulphate single crystals, suggesting a possible phase transition at 150°C. Measurements of thermally stimulated current also support these results. The mechanism of electrical conduction is explained on the basis of studies made on doped and quenched crystals.