Pillai, S M; Vallabhan, C P G(Solid State Communications, 1983)
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Abstract:
ZnS: Cu: Cl phosphor prepared under a vacuum firing process is found to
give blue electroluminescence with emission peak at 460 nm which remams
unaltered with the frequency of the excitation voltage. Addition of excess
chlorine in the phosphor gives blue, green and red emission at 460, 520
and 640 run. The intensity of the blue band decreases and It fmally
disappears as chlorine concentration is increased. A scheme involving
three energy levels attributed to Cu2+, Cu+ and Cl- centres in Zns
explains the experimental results completely.
The effect of chromium doping on methylene
blue sensitized Poly (vinyl alcohol)/Acrylamide was carried
out by varying the ratios of Ammonium dichromate
and methylene blue. In the case of films without ammonium
dichromate, the diffraction efficiency was found to
decrease on storage. On chromium doping the storage life
was improved. Interestingly, a self-enhancement in efficiency
was observed for a particular ratio of methylene
blue and ammonium dichromate.
Anantharaman, M R; Swapna, Nair S; Mercy, Mathews; Joy, P A; Kulkarni, S D(Elsevier, July 26, 2004)
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Abstract:
Superparamagnetic nanocomposites based on g-Fe2O3 and sulphonated polystyrene have been synthesized by ion
exchange process and the preparation conditions were optimized. Samples were subjected to cycling to study the effect
of cycling on the magnetic properties of these composites. The structural and magnetization studies have been carried
out. Magnetization studies show the dependence of magnetization on the number of ion exchange cycles. Doping of
cobalt at the range in to the g-Fe2O3 lattice was effected in situ and the doping was varied in the atomic percentage
range 1–10. The exact amount of cobalt dopant as well as the iron content was estimated by Atomic Absorption
Spectroscopy. The effect of cobalt in modifying the properties of the composites was then studied and the results
indicate that the coercivity can be tuned by the amount of cobalt in the composites. The tuning of both the
magnetization and the coercivity can be achieved by a combination of cycling of ion exchange and the incorporation of
cobalt
Description:
Journal of Magnetism and Magnetic Materials 283 (2004) 344–352
Sudha Kartha, C; Nimmi, K P; Sreekumar, K; Rani, Joseph; Pramitha, V(Wiley Online Library, January 7, 2012)
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Abstract:
Holographic grating with good storage
life in poly(vinyl alcohol) based photopolymer film, prepared
by gravity settling method, with reduced concentration
of the dye was found to give good diffraction
efficiency without crosslinking. The material was found
to show good diffraction efficiency and sensitivity (75%
diffraction efficiency at exposure energy of 80 mJ/cm2).
The shelf life of the photopolymer solution could be
improved by storage at a temperature 4 C in refrigerator
Description:
Journal of Applied Polymer Science, Vol. 125, 1238–1243 (2012)
Isora fibre-reinforced natural rubber (NR) composites were cured at 80, 100, 120 and
150°C using a low temperature curing accelerator system. Composites were also prepared using a
conventional accelerator system and cured at 150°C. The swelling behavior of these composites at
varying fibre loadings was studied in toluene and hexane. Results show that the uptake of solvent
and volume fraction of rubber due to swelling was lower for the low temperature cured vulcanizates
which is an indication of the better fibre/rubber adhesion. The uptake of aromatic solvent was higher
than that of aliphatic solvent, for all the composites. As the fibre content increased, the solvent
uptake decreased, due to the superior solvent resistance of the fibre and good fibre-rubber interactions.
The bonding agent improved the swelling resistance of the composites due to the strong interfacial
adhesion. Due to the improved adhesion between the fibre and rubber, the ratio of the change in
volume fraction of rubber due to swelling to the volume fraction of rubber in the dry sample (V,) was
found to decrease in the presence of bonding agent. At a fixed fibre loading, the alkali treated fibre
composite showed a lower percentage swelling than untreated one for both systems showing superior
rubber-fibre interactions.
Anantharaman, M R; Malini, K A; Sindhu, S; Chinnasamy, C N; Ponpadian, N; Narayanasamy, A; Balachandran, M; Sivasankara Pillai,V N(Kluwer Academic Publishers, February 1, 2001)
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Abstract:
Magnetic nanocomposites containing iron oxide particles embedded in a polymer matrix
have been synthesized using the method of ion exchange. They have been characterized by
using low temperature and room temperature magnetic measurements and Mo¨ ssbauer
spectroscopy. The iron content in these samples has also been determined. The results
have been analysed and explained. The physical and chemical properties of these
nanocomposite materials are different from those of the bulk. Some of the unique
properties of these materials find application in information storage, color imaging,
ferrofluids and magnetic refrigeration
Ramachandran, A; Rajendra, Badonia; Viswanathan Nair, P G(Society of fisheries Technologists (India), 1990)
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Abstract:
Effect of delayed icing on the microbial quality and shelf-life of Hilsa toll was studied
. Fish iced in rigor condition had a shelf-life of 11 days irrespective of the state
of rigor . Fish procured from the landing centre had a shelf-life of only 8 days . It
showed the presence of coagulase positive staphylococci, faecal streptococci and E. coli.
Total bacterial count was low in all the samples and it increased after spoilage
Measurements of dc conductivity and dielectric constant show that deuteration causes an upward shift of the high temperature phase transition point from 186.5 to 191°C and a downward shift of the low temperature transition point from 10 to -1.5°C in LiNH4SO4. Mechanisms of phase transitions and of electrical transport in the crystal are discussed.
Rani, Joseph(Wiley InterScience, February 18, 2006)
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Abstract:
In this paper we report the preparation and
dielectric properties of poly o-toluidine:poly vinyl chloride
composites in pellet and film forms. The composites were
prepared using ammonium persulfate initiator and HCl
dopant. The characterization is done by TGA and DSC. The
dielectric properties including dielectric loss, conductivity,
dielectric constant, dielectric heating coefficient, absorption
coefficient, and penetration depth were studied in the
microwave field. An HP8510 vector network analyzer with
rectangular cavity resonator was used for the study. Sbands (2-4 GHz), C band (5-8 GHz), and X band (8-12
GHz) frequencies were used in the microwave field. Comparisons
between the pellet and film forms of composites
were also included. The result shows that the dielectric
properties in the microwave field are dependent on the frequency
and on the method of preparation.
Rani, Joseph(Wiley lnterScience, September 4, 2006)
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Abstract:
The latex industry has expanded over the
years to meet the world demands for gloves, condoms,
latex thread etc. Because of the strict specifications for
the products and the unstable nature of the latex, as
high as 15%, of the final latex products are rejected.
Since waste latex rubber (WLR) represents a source of
high quality rubber hydrocarbon, it is a potential candidate
for generating reclaimed rubber of superior quality.
Two types of WLR with different amounts of polysulfidic
bridges are used in these experiments, which are
reclaimed with variation of the concentration of the
reclaiming agents, the reclamation temperature and time,
Di phenyldisultide, 2-aminophenyldisulfide and 2,2'-dibenzamidodiphenyldisulfide
(DBADPDS) are used as reclaiming
agents, and the effect of diphenyldisulfides (DPDS)
with different substituents, on the reclamation efficiency of WLR is investigated. A kinetic study of the reclamation
reaction with the three reclaiming agents is done.
The reaction rates and activation energies are calculated
and compared with literature values. The comparative
study of the three different reclaiming agents shows that
(DBADPDS) is able to break the crosslinks at temperature
levels 20'C below the temperature levels normally
used with DPDS. Another advantage of this reclaiming
agent is the reduced smell during the reclamation process
and of the final reclaims, one of the most important
shortcomings of other disulfides used for this purpose.
Ravisankar, M; Reghunath, A T; Sathianandan, K; Nampoori, V P N(Optical Society of America, September 15, 1988)
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Abstract:
The split-pulse laser method is used to reinvestigate the optical attenuation of distilled water in the region from 430 to 630 nm. The studies are then extended to ionic solutions of NaCl, MgCl2, and Na2SO4, these salts forming the major constituents of seawater. The effect of the concentration of these constituents on optical attenuation is investigated. Further, optical attenuation studies are carried out for the region from 430 to 630 nm for an aqueous solution prepared with all the major constituents in the same proportions as in natural seawater. These values are then compared with values obtained for natural seawater. The relative role of dissolved salts and suspended particles on optical attenuation in seawater is discussed. The lowest attenuation is observed at ~450 nm for all solutions and is found to coincide with that for distilled water.
Mohanan, T(American Institute of Physics, August 22, 2005)
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Abstract:
The effect of dopants with different valencies and ionic radii on the densification, structural
ordering, and microwave dielectric properties of Ba(Mg1/3Ta2/3)O3 (BMT) is investigated. It is
found that dopants such as Sb2O5, MnO, ZrO2, WO3, and ZnO improve the microwave dielectric
properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric
properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic
radii of the dopant has been established. The variation of the dielectric properties of pure and doped
BMT at cryogenic temperatures is also discussed.
Surendran,K P; Sebastian,M T; Mohanan, P; Mohanan,Jacob V(American Institute of Physics, 2005)
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Abstract:
The effect of dopants with different valencies and ionic radii on the densification, structural
ordering, and microwave dielectric properties of Ba(Mg1t3Tazt3)O3 (BMT) is investigated. It is
found that dopants such as Sb,05, MnO, ZrO,, WO1, and ZnO improve the microwave dielectric
properties of BMT. Addition of trivalent dopants is detrimental to the cation ordering and dielectric
properties of BMT. A correlation between the microwave dielectric properties of BMT and ionic
radii of the dopant has been established. The variation of the dielectric properties of pure and doped
BMT at cryogenic temperatures is also discussed
Rani, Joseph(John Wiley & Sons, Inc., June 21, 2001)
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Abstract:
ABSTRACT: Polyaniline was synthesized by using ammonium persulfate initiator in the
presence of 1M HC1. It was dried under different drying conditions like room temperature
drying (for 48 h), oven drying (at 50-60°C for 8 h under a vacuum), and vacuum
drying (at room temperature for 16 h). The conductivities of these samples were
measured at microwave frequencies. These samples were also pelletized and the
measurements were repeated. The cavity perturbation technique was used for the
study.
Joseph Francis,P J; Dr.Rani,Joseph(Cochin University of Science And Technology, April 20, 1998)
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Abstract:
Starve feeding of single screw extruder was described as an
important means of improving the performance characteristics of the
extruder. In addition to such improvement with versatility, the starve
feeding technique also may affect the mechanical properties of the
extrudate since the heat transfer an(l mixing characteristics in the starve
fed and Hood fed extruders are not the same. Since the material is more
loosely packed in the channels of the starve fed extruder, there may be
greater bed mobility and uniformity. Further, the. thermal an(l shear
induced degradation are also less since possibilities of developing local
high temperatures are less compared to a densely compacted extruder
bed. This study has been undertaken mainly to explore the effect of
feeding rate on the mechanical properties of rubber and plastic extrudates
since the effect of feeding rate has not been analysed from this angle so
far.
Description:
Department of Polymer
Science and Rubber Technology
Cochin University of
Science and Technology
Rani, Joseph(OPA (Overseas Publishers Association) N.V., July 23, 1997)
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Abstract:
Selected grades of low density polyethylene (LDPE) polystyrene (PS) were extruded in a
laboratory extruder by varying the feeding rate at different revolutions per minute and
temperatures. The mechanical properties of the extruded plastic sheets were determined.
LDPE shows a marked variation in mechanical properties with feeding rate while PS
shows a marginal change in mechanical properties with feeding rate. However, for both
plastics there is a particular feeding rate in the starved region which results in maximum
mechanical properties.
Vincent, Varghese; Dr. Sebastian Rupert, Mampilly(Cochin University of Science and Technology, 2007)
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Abstract:
Biosocial profile can produce variations in Gender-role Orientation of executives.
Biosocial variables are not responsible for the development of Communication
Style except in cases of number of children, dual career family and fathers
occupation. Gender-role orientation is a function of Communication Style.
Executive performance is a function of Communication Style.Gender- role orientation can have a decisive influence on executive performance.
The cumulative effect of Communication Style and gender role orientation can
produce variations in executive performance. Open Communication Style is
predominantly responsible for the creation of a higher level executive
performance than other Communication Styles.
Description:
School of Management Studies,
Cochin University of Science & Technology
The effect of glass additives on the densification , phase evolution, microstructure and microwave dielectric properties of Ba(Mg1;3
Ta2i3)03 (BMT) was investigated . Different weight percentages of quenched glass such as B203 , Si02, B203-SiO2, ZnO-B203,
5ZnO-2B2O3, Al203-SiO2, Na20-2B203.10H20, BaO-B203-SiO2, MgO-B203-SiO2, PbO-B203-SiO2 , ZnO-B203-SiO2 and
2MgO-Al203-5SiO2 were added to calcined BMT precursor . The sintering temperature of the glass -added BMT samples were
lowered down to 1300 °C compared to solid-state sintering where the temperature was 1650 °C. The formation of high temperature
satellite phases such as Ba5Ta4O15 and Ba7Ta6O22 were found to be suppressed by the glass addition . Addition of glass systems such
as B203, ZnO-B203, 5ZnO-2B203 and ZnO-B203-SiO2 improved the densification and microwave dielectric properties. Other
glasses were found to react with BMT to form low-Q phases which prevented densification . The microwave dielectric properties of
undoped BMT with a densification of 93 . 1 % of the theoretical density were Cr = 24 . 8, Tr = 8 ppm/°C and Q„ x f= 80,000 GHz. The
BMT doped with 1.0 wt% of B203 has Q„ x f = 124,700GHz, Cr = 24.2, and T f = -1.3 ppm /°C. The unloaded Q factor of 0.2 wt%
ZnO-B203-doped BMT was 136,500 GHz while that of 1.0 wt% of 5ZnO-2B203 added ceramic was Q„ x f= 141,800 GHz . The best
microwave quality factor was observed for ZnO -B203-SiO2 (ZBS) glass-added ceramics which can act as a perfect liquid-phase
medium for the sintering of BMT. The microwave dielectric properties of 0.2wt% ZBS-added BMT dielectric was
Q„ x f= 152,800 GHz, F,= 25.5, and Tr = - 1.5 ppm/°C