Junaid, Bushiri M; Jayasree, R S; Annamma, John; Nayar, V U(Elsevier, July 27, 2005)
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Abstract:
Polarized Raman spectral changes with respect to temperature were investigated for Pr(BrO3)3·9H2O single crystals. FTIR spectra of
hydrated and deuterated analogues were also recorded and analysed. Temperature dependent Raman spectral variation have been explained
with the help of the thermograms recorded for the crystal. Factor group analysis could propose the appearance ofBrO3 ions at sites corresponding
to C3v (4) and D3h (2). Analysis of the vibrational bands at room temperature confirms a distorted C3v symmetry for the BrO3 ion in the crystal.
From the vibrations of water molecules, hydrogen bonds of varying strengths have also been identified in the crystal. The appearance υ1 mode
of BrO3− anion at lower wavenumber region is attributed to the attachment of hydrogen atoms to the BrO3− anion. At high temperatures,
structural rearrangement is taking place for bothH2Omolecule and BrO3 ions leading to the loss ofwater molecules and structural reorientation
of bromate ions causing phase transition of the crystal at the temperature of 447 K.
The microwave dielectric properties of ZnAl2O4 spinels were investigated and their properties
were tailored by adding different mole fractions of Ti02. The samples were synthesized using the mixed
oxide rout.e. The phase purity and crystal structure were identified using X-ray diffraction technique.
The sintered specimens were characterized in the microwave frequency range (3-13 GHz). The ZnA12O4
ceramics exhibited interesting dielectric properties (dielectric constant (e,.) = 8.5, unloaded quality factor
(Q.) = 4590 at 12.27 GHz and temperature coefficient of resonant frequency (Tf) = -79 ppm/°C).
Addition of Ti02 into the spinel improved its properties and the Tf approached zero for 0.83ZnAl2O4-
0.17TiO2• This temperature compensated composition has excellent microwave dielectric properties (Cr _
12.67, Q, = 9950 at 10.075 GHz) which can be exploited for microwave substrate applications
Anantharaman, M R; Veena Gopalan, E; Malini, K A; Santhosh Kumar, G; Narayanan, T N; Joy, P A; Al-Omari, I A; Yasuhiko, Yoshida; Sakthi Kumar, D(Springer, April 2, 2010)
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Abstract:
Potential applications of nickel nanoparticles
demand the synthesis of self-protected nickel nanoparticles
by different synthesis techniques. A novel and simple
technique for the synthesis of self-protected nickel nanoparticles
is realized by the inter-matrix synthesis of nickel
nanoparticles by cation exchange reduction in two types of
resins. Two different polymer templates namely strongly
acidic cation exchange resins and weakly acidic cation
exchange resins provided with cation exchange sites which
can anchor metal cations by the ion exchange process are
used. The nickel ions which are held at the cation exchange
sites by ion fixation can be subsequently reduced to metal
nanoparticles by using sodium borohydride as the reducing
agent. The composites are cycled repeating the loading
reduction cycle involved in the synthesis procedure. X-Ray
Diffraction, Scanning Electron Microscopy, Transmission
Electron microscopy, Energy Dispersive Spectrum, and
Inductively Coupled Plasma Analysis are effectively
utilized to investigate the different structural characteristics
of the nanocomposites. The hysteresis loop parameters
namely saturation magnetization and coercivity are measured
using Vibrating Sample Magnetometer. The thermomagnetization
study is also conducted to evaluate the
Curie temperature values of the composites. The effect of
cycling on the structural and magnetic characteristics of the
two composites are dealt in detail. A comparison between
the different characteristics of the two nanocomposites is
also provided
Harilal, S S; Bindhu, C V; Nampoori, V P N; Vallabhan, C P G(Applied Spectroscopy, 1998)
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Abstract:
Spectroscopic studies of laser -induced plasma from a high-temperature
superconducting material, viz., YBa2Cu3O7 (YBCO), have
been carried out. Electron temperature and electron density measurements
were made from spectral data. The Stark broad ening of
emission lines was used to determine the electron density, and the
ratio of line in tensities was exploited for the determination of electron
temperature. An initial electron temperature of 2.35 eV and
electron density of 2.5 3 1017 cm2 3 were observed. The dependence
on electron temperature and density on different experimental parameters
such as distance from the target, delay time after the in itiation
of the plasm a, and laser irradiance is also discussed in detail.
Index Headings: Laser -plasma spectroscopy; Plasma diagnostics;
Emission spectroscop y; YBa2Cu3O7.
Harilal, S S; Issac, Riju C; Bindhu, C V; Nampoori, V P N; Vallabhan, C P G(American Institute of Physics, September 15, 1996)
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Abstract:
Laser ablation of graphite has been carried out using 1.06mm radiation from a Q-switched Nd:YAG
laser and the time of flight distribution of molecular C2 present in the resultant plasma is
investigated in terms of distance from the target as well as laser fluences employing time resolved
spectroscopic technique. At low laser fluences the intensities of the emission lines from C2 exhibit
only single peak structure while beyond a threshold laser fluence, emission from C2 shows a twin
peak distribution in time. The occurrence of the faster velocity component at higher laser fluences
is explained as due to species generated from recombination processes while the delayed peak is
attributed to dissociation of higher carbon clusters resulting in the generation of C2 molecule.
Analysis of measured data provides a fairly complete picture of the evolution and dynamics of
C2 species in the laser induced plasma from graphite.
Harilal, S S; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(American Institute of Physics, June , 1994)
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Abstract:
YBa2Cu307 target was laser ablated, and the time-of-flight (TOF) distributions of Y, Y+., and YO in
the resultant plasma were investigated as functions of distance from the target and laser energy
density using emission spectroscopy. Up to a short distance from the target (-1.5 cm), TOF
distributions show twin peaks for Y and YO, while only single-peak distribution is observed for Y+.
At greater distances (>1.5 cm) all of them exhibit single-peak distribution. The twin peaks are
assigned to species corresponding to those generated directly/m the vicinity of target surface and to
those generated from collisional/recombination process.
Bijoy, Nandan S; Jayachandran, P R; Sreedevi, O K(2012)
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Abstract:
The status of fisheries and seasonal variation in fish diversity in the Kodungallur-Azhikode Estuary (KAE) were investigated.
Total annual average fish production in the estuary declined significantly to 908.6 t with average yield of 5.4 kg ha-1 day-1,
when compared to earlier study; where 2747 t was reported. During the present study, 60 species of finfishes (belonging to
34 finfish families), 6 species of penaeid shrimps, 2 species of palaemonid prawns, 2 species of crabs (4 crustacean families),
6 species of bivalves and 2 species of edible oysters (3 molluscan families) were noticed. Finfishes were the major group that
contributed 69.62% of total fishery in the estuary and crustaceans (23.47%), bivalves (6.84%) and oysters (0.07%) also
formed good fishery. Many of the fish species in the estuary were observed as threatened (Horabagrus brachysoma, Channa
striatus, Channa marulius, Clarias batrachus, Heteropneustes fossilis and Wallago attu). The major fishing gears employed
in the estuary were gillnets, cast nets, stake nets, scoop nets, ring nets, traps and Chinese dip nets. Gillnets contributed 45%
of the total fish catch. Gillnets also showed highest catch per unit effort (CPUE) of 6.91 kg h -1 followed by cast nets
(1.85 kg h -1), Chinese dip nets (3.20 kg h -1), stake nets (3.05 kg h -1), ring nets (1.27 kg h -1), hooks and lines (1.35 kg h -1)
and scoop nets (0.92 kg h -1). The study implies that temporal changes in fish landing pattern of the KAE was mainly due to
environmental variability, habitat modification and fish migration; under the influence of south-west monsoon and
anthropogenic activities in the KAE. Results of the study suggest that spatio-temporal variations in the fish community
structure could be an indicator for anthropogenic stress and it should be considered for restoration programmes.
Paulose,C S; Thliveris,J A; Dakshinamurti,K; Viswanathan,M(Department of Biotechnology, 1989)
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Abstract:
We have studied testicular function in the biotin-
deficient rat biochemically and morphologically.
Serum testosterone and luteinizing hormone (LH) levels
were decreased significantly in the deficient rats. Administration
of biotin or gonadotropins to the deficient rats
reversed this decrease in serum testosterone. There was no
difference in the serum cholesterol level between the control
and biotin-deficient rats. A significant degree of sloughing
of seminiferous tubule germinal epithelium was noticed
in the biotin-deficient rat testes. Biotin treatment of biotindeficient
rats reversed this condition whereas testosterone
treatment was without any effect. The development and
maintenance of morphological and functional integrity of
the seminiferous tubules appears to require a biotin-mediated
step in addition to testosterone.
One comes across directions as the observations in a number of situations. The first inferential question that one should answer when dealing with such data is, “Are they isotropic or uniformly distributed?” The answer to this question goes back in history which we shall retrace a bit and provide an exact and approximate solution to this so-called “Pearson’s Random Walk” problem.
Ramachandran,K K; Dr.Seralathan, P(cusat, April 10, 1992)
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Abstract:
The continental shelf of southwest coast of India (Kerala) is broader and . flatter compared to that of the east coast. The unique characteristic feature of the study area (innershelf between Narakkal and Purakkad) is the intermittent appearance of 'mud banks' at certain locations during southwest monsoon. The strong seasonality manifests significant changes in the wind, waves, currents, rainfall, drainage etc., along this area. Peculiar geomorphological variation with high, mid and lowlands in the narrow strip of the hinterland, the geological formations mainly consisting of rocks of metamorphic origin and the humid tropical weathering conditions play significant role in regulating the shelf sedimentation.
A complementary pattern of distri bution is observed for clay that shows an abundance in the nearshore. Silt, to a major extent, depicts semblance with clay distribution . Summation of the total asymmetry of grain size distribution are inferred from the variation of skewness and kurtosis.Factor I implies a low energy regime where the transportation and deposition phases are controlled mostly by pelagic suspension process as the factor loadings are dominant on finer phi sizes. The second Factor is inferred to be the result of a high energy regime which gives higher loadings on coarser size fractions. The third Factor which might be a transition phase (medium energy regime) representing the resultant flux of coastal circulation of the re-suspension/deposition and an onshoreoffshore advection by reworking and co-deposition of relict and modern sediments. The spatial variations of the energy regime based on the three end-member factor model exhibits high energy zone in the seaward portion transcending to a low energy one towards the coast.From the combined analysis of granulometry and SEM studies, it is concluded that the sandy patches beyond 20 m depth are of relict nature. They are the resultant responses of beach activity during the lower stand of sea level in the Holocene. Re-crystallisation features on the quartz grains indicate that they were exposed to subaerial weathering process subsequent to thei r deposition
Description:
Marine Science Division, Centre for Earth Science Studies,
Thiruvananthapuram