Studies conducted on butadiene-acrylonitrile copolymer (NBR)/poly(vinyl chloride) (PVC)
blends at different temperatures indicate that an optimum temperature exists for the formation
of a particular blend. The mechanical properties of the blends confirm this observation.
PVC stabilizer based on, magnesium oxide , zinc oxide, and stearic acid was found to be very
useful in NBR/PVC blends.
Paulose,C S; Dakshinamurti,K; Subah,Packer; Newman,L Stephens(Department of Biotechnology, 1986)
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Abstract:
Pyridoxal phosphate (PLP) is the coenzyme of various decarboxylases involved in the
formation of monoamine urotransmitters such as y-aminobulyric acid (GAE3A),
serotonin (5-HT) and dopamine. 1-lowever; in the pyridoxine-deficient rats GABA and
5-HT are decreased in various brain areas including the hypothalamus, with no change
in the catecholamine levels. Serotonin and GABA are known to be involved in blood
pressure control mechanisms. In this study adult Sprague-Dawley rats placed on a
pyridoxine-deficient diet for 8 weeks showed significant hypertension compared with
pyridoxine-supplemented controls. This was associated with a general sympathetic
stimulation. Treatment of deficient rats with a single dose of pyridoxine (10 mg/kg body
weight) reversed the blood pressure to normal levels within 24 h, with concomitant
restoration of hypothalamic 5-HT and GABA, as well as the return of plasma
norepinephrine to nornr;l levels. The results indicate that there is a cause-and-effect
relationship between pyridoxine deficiency and hypertension.
Rani, Joseph(Huthig & Wepf Verlag, Basel, April 29, 1986)
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Abstract:
Tribasic lead sulphate is tried as a practical curing agent for polychloroprene. The
cure characteristics of the compounds as well as the technical properties of the
vulcanizates show that it can act as a potential curative.
Rani, Joseph(Hitthig & Wepf Verlag, Basel, October 13, 1986)
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Abstract:
A carbon black filled 50/50 natural rubber (NR)/styrene-butadiene rubber (SBR)
blend is vulcanized using several conventional curing systems designed by varying the
amounts of sulphur and accelerator. The cure characteristics and the properties of the
vulcanizates are compared. The quantity and quality of crosslinks in each case are
evaluated by chemical probes to correlate them with the properties.
Rani, Joseph(Gordon and Breach Science Publishers, Inc., November 13, 1986)
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Abstract:
A carbon black filled 50/50 Natural Rubber (NR)/Polybutadiene Rubber (BR) blend
is vulcanized using several conventional systems designed by varying the amounts of
sulphur and accelerator . The cure characteristics and the vulcanizate properties are
compared. The quality and quantity of crosslinks in each case are deciphered by
chemical probes to correlate them with the vulcanizate properties.
Rani, Joseph(Gordon and Breach Science Publishers, Inc., November 28, 1986)
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Abstract:
Polymer-solvent interaction parameters for the blends of natural rubber (NR) with
styrene-butadiene rubber (SBR) and polybutadiene rubber ( BR) are calculated using
the Flory-Rehner equation by equating the network density of the vulcanizates in
two solvents.
Rani, Joseph(HUthig & Wepf Verlag Basel, December 12, 1986)
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Abstract:
Blends of polychloroprene rubber and plasticized polyvinylchloride have been prepared
in various compositions and their properties evaluated. The properties of the
blends show that they can be used to replace polychloroprene in many applications
Abdul Rasheed, T M; Moosad, K P B; Nampoori, V P N; Sathianandan, K(American Chemical Society, 1987)
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Abstract:
Vibrational overtone spectra of acetophenone and benzaldehyde in the visible and near-infrared regions are studied by the
dual beam thermal lens and the conventional near-infrared absorption techniques. The observed increase in the mechanical
frequency of the aryl CH bond from that of benzene is attributed to the decrease in the aryl CH bond length caused by
the electron-withdrawing property of the substituents. Overtone spectra also demonstrate that acetophenone contains two
types of methyl CH bonds arising from the anisotropic environments created by oxygen lone pair and carbonyl P electrons.
The local-mode parameters of the two types of CH bonds are compared with those of acetone and acetaldehyde. The possible
factors influencing the methyl CH bonds in acetophenone are discussed.
Paulose,C S; Dakshinamurti,K(Department of Biotechnology, June 12, 1987)
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Abstract:
Chronic catheterization is illustrated using vascular-access-port model SLA where the port is surgically placed subcutaneously on
the back of the rat. The catheter is tunnelled to the neck and inserted into the jugular vein . Within 24 h rats showed normal blood
pressure and blood samples were collected at intervals with minimal stress to the animals . A comparison of the plasma catecholamine
of blood collected from vascular-access-ports with that obtained from decapitation indicates that there was minimal stress to the rats
when blood was drawn through the vascular-access-port.
The role of acoustic plasmons in the recently discovered high Tc superconductors
is discussed. It is shown that the exchange of acoustic plasmons together with the
usual phonon exchange between electrons can give rise to a Tc - 100 K.
Natural rubber, styrene-butadiene rubber, and polybutadiene
rubber were used to replace part of the butadieneacrylonitrile
rubber in a 70/30 butadiene-acrylonitrile rubber/
poly(vinyl chloride) blend. Such replacement up to 15%
of the total weight of the blend improved the mechanical
properties, while decreasing the cost of the blend. Styrenebutadiene
rubber could replace butadiene-acrylonitrile
rubber up to 30% of the total weight of the blend without
deterioration in the mechanical properties.
Rani, Joseph(Hutig & Wepf Verlag,Basel, October 5, 1987)
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Abstract:
Compounding of styrene-butadiene copolymer/polybutadiene , natural rubber/
ethylene-propylene-diene terpolymer and natural rubber/butadiene-acrylonitrile copolymer
blends was done in three different ways and their curing behaviour and the
tensile properties of the es are compared.
Lalaja, Varghese; Nampoori, V P N; Pratap, R(Current Science, October 20, 1987)
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Abstract:
A mathematical analysis of an electroencephalogram of a human Brain during an epileptic
seizure shows that the K2 entropy decreases as compared to a clinically normal brain while the
dimension of the attractor does not show significant deviation.
Reghunath, A T; Nampoori, V P N(Springer, November , 1987)
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Abstract:
Using laser transmission, the characteristics of hydrodynamic turbulence is studied following one of the recently developed technique in nonlinear dynamics. The existence of deterministic chaos in turbulence is proved by evaluating two invariants viz. dimension of attractor and Kolmogorov entropy. The behaviour of these invariants indicates that above a certain strength of turbulence the system tends to more ordered states.
Harikrishnan, K P; Nandakumaran, V M(Pramana, December , 1987)
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Abstract:
We have studied the bifurcation structure of the logistic map with a time dependant control parameter. By introducing a specific nonlinear variation for the parameter, we show that the bifurcation structure is modified qualitatively as well as quantitatively from the first bifurcation onwards. We have also computed the two Lyapunov exponents of the system and find that the modulated logistic map is less chaotic compared to the logistic map.
Harikrishnan, K P; Nandakumaran, V M(Elsevier, December 7, 1987)
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Abstract:
We study the period-doubling bifurcations to chaos in a logistic map with a nonlinearly modulated parameter and show that the bifurcation structure is modified significantly. Using the renormalisation method due to Derrida et al. we establish the universal behaviour of the system at the onset of chaos.
Paulose,C S; Dakshinamurti,K; Subah,Packer; Newman,L Stephens(Department of Biotechnology, December 8, 1987)
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Abstract:
Pyridoxal phosphate is the coenzyme of various decarboxylases involved in the formation
of monoamine neurotransmitters such as y-aminobutyric acid , serotonin , dopamine, and norepinephrine
. Adult male Sprague-Dawley rats placed on a pyridoxine -deficient diet for 8 weeks showed
significant hypertension compared with pyridoxine -supplemented controls . Hypothalamic contents of
pyridoxal phosphate , y-aminobutyric acid, and serotonin in the pyridoxine - deficient rats were significantly
lower than those in pyridoxine -supplemented controls . Hypertension was associated with
sympathetic stimulation . Treatment of pyridoxine-deficient rats with a single dose of pyridoxine (10
mg/kg body weight) reversed the blood pressure to normal levels within 24 hours, with concomitant
restorations of hypothalamic serotonin and y-aminobutyric acid as well as the return of plasma
norepinephrine and epinephrine to normal levels . Also, pyridoxine treatment reversed the hypothalamic
hypothyroidism observed in pyridoxine -deficient rats . These results indicate an association
between pyridoxine deficiency and sympathetic stimulation leading to hypertension.
Pratap, R; Nampoori, V P N; Lalaja, Varghese(International Journal of Neuroscience, 1988)
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Abstract:
It is shown that the invariant integral, viz., the Kolmogorov second entropy, is eminently suited to characterize EEG quantitatively. The estimation obtained for a "clinically normal" brain is compared with a previous result obtained from the EEG of a person under epileptic seizure.
Blends of 50/50 natural rubber (NR) and styrene-butadiene rubber (SBR) are vulcanized using
several conventional and semi-EV systems. The cure characteristics and vulcanizate properties
are compared. The quantity and quality of crosslinks in each case are deciphered by chemical
probes to correlate them with the vulcanizate properties.