Kriashnan Nair, P R; Nandakumaran, V M; Ambika, G(Pramana, December , 1994)
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Abstract:
We establish numerically the validity of Huberman-Rudnick scaling relation for
Lyapunov exponents during the period doubling route to chaos in one dimensional maps. We
extend our studies to the context of a combination map. where the scaling index is found to
be different.
Sunil,K Narayanankutty(Gordon and Breach Science Publishers, December 10, 1991)
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Abstract:
Tear and wear properties of short kevlar fiber, thermoplastic polcurethane (TPU) composite with
respect to fiber loading-and fiber onentation has been studied and the fracture surfaces were examined
under scanning electron microscope (SEM). Tear strength first decreased up to 20 phr fiber loading
and then gradually increased with increasing fiber loading. Anisotropy in tear strength was evident
beyond a fiber loading of 20 phr. Tear fracture surface of unfilled TPU showed sinusoidal folding
characteristics of high strength matrix. At low fiber loading the tear failure was mainly due to fibermatrix failure whereas at higher fiber loading the failure occurred by fiber breakage. Abrasion loss
shows a continuous rise with increasing fiber loading, the loss in the transverse orientation of fibers
being higher than that in the longitudinal orientation. The abraded surface showed lone cracks and
ridges parallel to the direction of abrasion indicating an abrasive wear mechanism. In the presence of
fber the abrasion loss was mainly due to fiber low.
Chandran,A R; Gopikrishna, M; Aanandan,C K; Mohanan, P; Vasudevan, K(Progress In Electromagnetics Research, 2007)
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Abstract:
The scattering behaviour of fractal based metallodielectric structures loaded over metallic targets of different shapes such as flat plate, cylinder and dihedral corner reflector are investigated for both TE and TM polarizations of the incident wave. Out of the various fractal structures studied,square Sierpinski carpet structure is found to give backscattering reduction for an appreciable range of frequencies. The frequency of minimum backscattering depends on the geometry of the structure as well as on the thickness of the substrate. This structure when loaded over a dihedral corner reflector is showing an enhancement in RCS for corner angles other than 90◦.
A comprehensive overview of reclamation of cured rubber with special emphasis on latex reclamation is depicted in this
paper. The latex industry has expanded over the years to meet the world demands for gloves, condoms, latex thread, etc.
Due to the strict specifications for the products and the unstable nature of the latex as high as 15% of the final latex
products are rejected. As waste latex rubber (WLR) represents a source of high-quality rubber hydrocarbon, it is a
potential candidate for generating reclaimed rubber of superior quality. The role of the different components in the
reclamation recipe is explained and the reaction mechanism and chemistry during reclamation are discussed in detail.
Different types of reclaiming processes are described with special reference to processes, which selectively cleave the cross
links in the vulcanized rubber. The state-of-the-art techniques of reclamation with special attention on latex treatment are
reviewed. An overview of the latest development concerning the fundamental studies in the field of rubber recycling by
means of low-molecular weight compounds is described. A mathematical model description of main-chain and crosslink
scission during devulcanization of a rubber vulcanizate is also given.
Bindu, Krishnan; Nampoori, V P N(Indian Academy of Sciences, June , 2005)
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Abstract:
Nanosized ZnO was prepared by polyol synthesis. Fluorescence spectrum of the ZnO colloid at varying pump intensities was studied. The powder was extracted and characterized by XRD and BET. The extracted powder was screen printed on glass substrates using ethyl cellulose as binder and turpinol as solvent. Coherent back scattering studies were performed on the screen printed sample which showed evidence of weak localization. The screen printed pattern showed strong UV emission.
The mangroves of Kerala are fast disappearing due to developmental activities.There are very few
studies conducted in the chemical aspects of these ecosystems.The main objective of this study is to
assess the spatial and seasonal variation of hydrographical as well as nutrients in mangrove
ecosystems along Kerala coast. Five sampling sites least intervened by industries were selected for
the study. Sampling was done for a period of six months in monthly intervals. A monsoonal hike of
dissolved nutrients was observed in all ecosystems except in the constructed mangrove wetland. The
constructed wetland exhibited a different hydrography and nutrient level in all seasons. The mangrove
forest in this area consists of the species Bruguiera gymnorrhiza which has been planted since forty
years.
Description:
Journal of Wetlands Ecology, (2009) Vol. 3, pp 32-42
Sugunan, S; Anantaraman, R(Indian Journal of Chemistry, December , 1982)
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Abstract:
Kinetics of mercuric chloride catalysed solvolysis of l-butyl
chloride, benzyl chloride. p-methylbenzyl chloride, l-phenylethyl
chloride and triethylcarbinyl chloride have been studied in aq.
DMSO, aq. acetonitrile and aq. ethanol. The kinetic data fit a second
order rate equation in aq. DMSO. The calculated values of the
second order rate coefficients increase in the case of aq. acetonitrile
and aq. ethanol. The order in catalyst in 95%(v/v) aq. DMSO is less
than unity.
Jagathy Raj, V P; Suresh Kumar, B(IJWCNT, August , 2012)
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Abstract:
Now a days, email has become the most widely
communication way in daily life. The main reason for using
email is probably because of the convenience and speed in
which it can be transmitted irrespective of geographical
distances. To improve security and efficiency of email system,
most of the email system adopt PKI and IBE encryption
schemes. However, both PKI and IBE encryption schemes
have their own shortcomings and consequently bring security
issues to email systems. This paper proposes a new secure
email system based on IBE which combines finger print
authentication and proxy service for encryption and
decryption
Description:
International Journal of Wireless Communications and Networking Technologies,Volume 1, No.1, August- September 2012
Marine yeasts (33 strains) were isolated from the
coastal and offshore waters off Cochin. The isolates
were identified and then characterized for the utilization
of starch, gelatin, lipid, cellulose, urea, pectin,
lignin, chitin and prawn-shell waste. Most of the
isolates were Candida species. Based on the
biochemical characterization, four potential strains
were selected and their optimum pH and NaCI
concentration for growth were determined. These
strains were then inoculated into prawn-shell waste
and SCP (single cell protein) generation was noted in
terms of the increase in protein content of the final
product.
Nishamol, K; Rahna, K S; Sugunan, S(Elsevier, 2004)
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Abstract:
Various compositions of chromium manganese ferrospinels were tested as catalysts for the vapour phase alkylation of aniline with methanol. The samples were prepared by room temperature co-precipitation technique and characterized by various physico-chemical methods. The acidity–basicity determination revealed that the samples possess greater amount of basic sites than acidic sites. All the ferrite samples proved to be selective and active for N-monoalkylation of aniline leading to N-methyl aniline; Cr0.6Mn0.4Fe2O4, Cr0.8Mn0.2Fe2O4 and CrFe2O4 exhibited cent percent selectivity for N-methyl aniline. Neither C-alkylated products nor any other side products were detected for all catalyst samples. The catalytic activity of the samples studied in this reaction is related to their acid–base properties and also on the cation distribution. Under the optimized reaction conditions all the systems showed constant activity for a long duration.
Iron and mixed iron aluminium pillared montmorillonites prepared by partial hydrolysis method was subjected to room temperature exchange with transition metals of the first series. The materials exhibit good structural as well as thermal stability. Exchanged metals were found to be present inside the porous network, in the environs of the pillars. Mixed pillaring resulted in the intercalation of Al 13 like polymers in which Al is partially substituted by Fe. The acidic structure was followed by temperature programmed desorption of ammonia and cumene cracking test reaction. Weak and medium sites overshadow the strong sites in all systems. However, exchange with metals increases the number of strong sites. The prepared materials are efficient catalysts for gas phase MTBE synthesis. The catalytic activity can be well correlated with the total amount of weak and medium acid sites.
Nithyaja, Balan; Misha, Hari; Nampoori, Vadakkedathu P N(Optical Society of America, July 1, 2009)
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Abstract:
A solid-state laser based on a dye-doped deoxyribonucleic acid (DNA) matrix is described. A thin solid film of DNA has been fabricated by treating with polyvinyl alcohol (PVA) and used as a host for the laser dye Rhodamine 6G. The edge emitted spectrum clearly indicated the existence of laser modes and amplified spontaneous emission. Lasing was obtained by pumping with a frequency-doubled Nd:YAG laser at 532 nm. For a pump energy of 10 mJ/pulse, an intense line with FWHM ≈0.2 nm was observed at 566 nm due to selective mode excitation.
Sreekumar, K; Raja, T; Kiran, B P; Sugunan, S; Rao, B S(Elsevier, 1999)
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Abstract:
The reaction of aniline with methanol was carried out over Zn1-xNixFe2O4 (x= 0, 0.2, 0.5, 0.8 and 1) type systems in a
fixed-bed down-flow reactor. It was observed that systems possessing low ``x'' values are highly selective and active for mono
N-alkylation of aniline leading to N-methyl aniline. Selectivity for N-methyl aniline over ZnFe2O4 was more than 99% under
the optimized reaction conditions. Even at methanol to aniline molar ratio of 2, the yield of N-methyl aniline was nearly
55.5%, whereas its yield exceeded 67% at the molar ratio of 7. The Lewis acid sites of the catalysts are mainly responsible for
the good catalytic performance. Cation distribution in the spinel lattice influences their acido-basic properties, and hence,
these factors have been considered as helpful to evaluate the activity and stability of the systems.
Sreekumar, K; Jyothi, T M; Talawar, M B; Kiran, B P; Rao, B S(Elsevier, 2000)
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Abstract:
A series of ferrites having the general formula Zn1-xCoxFe2O4 (x=0, 0.2, 0.5, 0.8 and 1.0)were prepared by soft
chemical route. The materials were characterized by adopting various physico-chemical methods. The reaction of aniline
with methanol was studied in a fixed-bed reactor system as a potential source for the production of various methyl anilines.
It was observed that systems possessing low ‘ x’ values are highly selective and active for N-monoalkylation of aniline
leading to N-methylaniline. Reaction parameters were properly varied to optimize the reaction conditions for obtaining
N-methylaniline selectively and in better yield. Among the systems Zn0.8Co0.2Fe2O4 is remarkable due to its very high
activity and excellent stability. Under the optimized conditions N-methylaniline selectivity exceeded 98%. Even at a
methanol to aniline molar ratio of 2, the yield of N-methylaniline was nearly 50%, whereas its yield exceeded 71% at the
molar ratio of 5. ZnFe2O4, though executed better conversion than Zn0.8Co0.2Fe2O4 in the initial period of the run,
deactivates quickly as the reaction proceeds. The Lewis acidity of the catalysts is mainly responsible for the good
performance. Cation distribution in the spinel lattice influences their acido-basic properties and, hence, these factors have
been considered as helpful parameters to evaluate the activity of the systems.
The self adhesion behaviour of thermoplastic polyurethane (TPU) in itself and its
composite with short Kevlar fibre with respect to contact time, temperature, pressure, and fibre
loading has been studied. The adhesion strength showed two linear increments of different slopes
with respect to the square root of time: with temperature and pressure of contact, the adhesion
strength was improved. The maximum strength was obtained with 20 phr of short fibre in only one of
the mating substrates in the peel test sample. The duration for wetting and diffusion was shifted to
longer time intervals with fibres loaded in both the substrates.
Tessamma, Thomas; Ananda Resmi, S(Scientific Research Publishing, July 28, 2012)
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Abstract:
This work presents an efficient method for volume rendering of glioma tumors from segmented 2D MRI Datasets with user interactive control, by replacing manual segmentation required in the state of art methods. The most common primary brain tumors are gliomas, evolving from the cerebral supportive cells. For clinical follow-up, the evaluation of the pre- operative tumor volume is essential. Tumor portions were automatically segmented from 2D MR images using morphological filtering techniques. These seg- mented tumor slices were propagated and modeled with the software package. The 3D modeled tumor consists of gray level values of the original image with exact tumor boundary. Axial slices of FLAIR and T2 weighted images were used for extracting tumors. Volumetric assessment of tumor volume with manual segmentation of its outlines is a time-consuming proc- ess and is prone to error. These defects are overcome in this method. Authors verified the performance of our method on several sets of MRI scans. The 3D modeling was also done using segmented 2D slices with the help of a medical software package called 3D DOCTOR for verification purposes. The results were validated with the ground truth models by the Radi- ologist.
Description:
J. Biomedical Science and Engineering, 2012, 5, 378-383