Kumar,K G; Augustine,P; John,S(Department of Applied Chemistry, June 21, 2007)
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Abstract:
A novel electrochemical sensor has been developed for the determination of nimesulide.
The sensor is based on the NIM- molybdophosphoric acid (MPA) as the electroactive
material in PVC matrix in presence of bis(2-ethyl hexyl) phthalate (BEP) as a
plasticizer. The sensor showed a fast, stable, near Nernstian response for 1 × 10-2 –1 ×
10-6 M NIM over the pH range 5 – 8 with a slope 55.6 ±0.5m V/decade and the response
time is < 45 s. Selectivity coefficient data for some common ions show negligible
interferences. The sensor was successfully applied for the determination of NIM in
tablet and the results obtained are in good agreement with those obtained by the official
method.
Qiang,Gao; Yan,Yin; Dun-Bao,Yan; Nai,Chang Yuan(Microwave and Optical Technology Letters, November 5, 2005)
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Abstract:
A navel ultra-thin radar-absorbing material (RAM) using
metanwterials is presented and the absorption performance is examined.
Due to the high-impedance property of the metamalerials. the thickness
of the RAM is about several tenths of the center wavelength of the absorption
band, which is considerably thinner than conventional absorbers.
The absorption bandwidth of the RAM is about several hundred
megahertz
Gijo,Augustin; Shynu,S V; Aanandan,C K; Mohanan,P; Vasudevan,K(Microwave and Optical Technology Letters, April 20, 2005)
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Abstract:
An innovative phaseshifterless, wideband, micrustrip
leaky-wave antenna with an electronically steerable dual-pencil-beam
pattern in the H-plane is presented. The log-periodic geometry of the
leaky slots of the antenna results in a wide bandwidth of 25.19%. The
Jan beam can he steered up to 14° over the wide resonating band of the
anteww. The beam is also steerable at a fixed frequency. by reactivelty
loading the slots and a maximum steering angle of about 14° is ohserved.
for different capacitor values with an improved bandwidth of
33 _i%. This concept is studied using passive components but it can be extended to varactors
Siji,Thomas; Vijay Nair,G(ORGANIC CHEMISTRY DIVISION REGIONAL RESEARCH LABORATORY (CSIR), December , 2004)
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Abstract:
A systematic investigation of the reactivity and functionalization of two
heterocyclic analogs of triphenylmethane , namely tris(2-thienyl)methane and
tris(2-furyl)methane have been carried out and the results are presented in this
thesis entitled "NOVEL REACTIONS OF TRIS(2-THIENYL)METHANE AND
TRIS(2-FURYL)METHANE.". The history of organic free radicals dates back to Gomberg's monumental discovery of the triphenylmethyl radical in 1900. The heterocyclic analogs of triarylmethane are also interesting from the vantage point of their transformation to the corresponding radicals akin to Gomberg ' s triphenylmethyl radical and also they are prone to further transformation leading to three dimensionally elongated molecules such as dendrimers. Dendritic architectures are one of the most pervasive topologies observed in nature at the macro- and microdimensional length devices. Because of their ability to combine both organic and inorganic compounds and their propensity to either encapsulate or be engineered into unimolecular functional devices , dendrimers are versatile amongst existing nanoscale building blocks and materials.
Sreekanth,A R; Vijay Nair,G(ORGANIC CHEMISTRY DIVISION REGIONAL RESEARCH LABORATORY (CSIR), November , 2002)
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Abstract:
In the thesis entitled " Novel Strategies for Heterocyclic Constructions via 1 ,4-Dipolar Intermediates"Synthesis of a complex organic molecules essentially involves the formation of carbon-carbon and carbon-heteroatom bonds. Various synthetic methods are available for these processes involving ionic, pericyclic and
radical reactions. Among the pericyclic reactions, dipolar cycloaddition reactions, introduced by Huisgen, have emerged as a very powerful tool for heterocyclic construction. Heterocyclic compounds remain an important class of organic molecules due to their natural abundance and remarkable biological activity, thus constituting an intergral part of pharmaceutical industry. In this respect, developing newer synthetic methodology for heterocyclic construction has been an area of immense interest. In recent years, 1,3-dipolar cycloaddition reactions proved to be efficient routes to a wide variety of five membered heterocycles, as attested by their application in the total synthesis of various complex organic molecules. However, the potential application of similar 1,4- dipolar cycloaddition reactions for the construction of six memebered heterocycles remained underexploited. In this context, a systematic investigation of the reactivity of 1,4-dipoles generated from nitrogen heterocycles (pyridine and its analogues) and dimethyl acetylenedicarboxy!ate (DMAD) towards various dipolarophiles has been carried out and the results are embodied.
Supriyo,Dey; Aanandan,C K; Mohanan,P; K G Nair(IETE Technical Review, 1993)
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Abstract:
Design, development and experimental observations of a L: band printed dipole antenna is presented.Bandwidth
enhancement is achieved by end-loading or the dipole arms. Using the present technique Impedance bandwidth van be
enhanced up to 50% without degrading the efficiency of the antenna.
Deepa, Balakrishnan S; Dr. Nandakumar, C G(Cochin University of Science and Technology, January , 2008)
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Abstract:
Frames are the most widely used structural system for multistorey
buildings. A building frame is a three dimensional discrete structure consisting of
a number of high rise bays in two directions at right angles to each other in the
vertical plane. Multistorey frames are a three dimensional lattice structure which
are statically indeterminate. Frames sustain gravity loads and resist lateral forces
acting on it.
India lies at the north westem end of the Indo-Australian tectonic plate and
is identified as an active tectonic area. Under horizontal shaking of the ground,
horizontal inertial forces are generated at the floor levels of a multistorey frame.
These lateral inertia forces are transferred by the floor slab to the beams,
subsequently to the columns and finally to the soil through the foundation system.
There are many parameters that affect the response of a structure to ground
excitations such as, shape, size and geometry of the structure, type of foundation,
soil characteristics etc. The Soil Structure Interaction (SS1) effects refer to the
influence of the supporting soil medium on the behavior of the structure when it
is subjected to different types of loads.
Interaction between the structure and its supporting foundation and soil,
which is a complete system, has been modeled with finite elements. Numerical
investigations have been carried out on a four bay, twelve storeyed regular
multistorey frame considering depth of fixity at ground level, at characteristic
depth of pile and at full depth. Soil structure interaction effects have been studied
by considering two models for soil viz., discrete and continuum. Linear static
analysis has been conducted to study the interaction effects under static load.
Free vibration analysis and further shock spectrum analysis has been conducted to
study the interaction effects under time dependent loads. The study has been
extended to four types of soil viz., laterite, sand, alluvium and layered.The structural responses evaluated in the finite element analysis are
bending moment, shear force and axial force for columns, and bending moment
and shear force for beams. These responses increase with increase in the founding
depth; however these responses show minimal increase beyond the characteristic
length of pile. When the soil structure interaction effects are incorporated in the
analysis, the aforesaid responses of the frame increases upto the characteristic
depth and decreases when the frame has been analysed for the full depth. It has
been observed that shock spectrum analysis gives wide variation of responses in
the frame compared to linear elastic analysis. Both increase and decrease in
responses have been observed in the interior storeys. The good congruence shown
by the two finite element models viz., discrete and continuum in linear static
analysis has been absent in shock spectrum analysis.
Description:
Department of Ship Technology,
Cochin University of Science &
Technology
Bindu, V; Nandakumaran, V M(Elsevier, December 11, 2000)
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Abstract:
Results of a numerical study of synchronisation of two directly modulated semiconductor lasers, using bi-directional coupling, are presented. The effect of stepwise increase in the coupling strength (C) on the synchronisation of the chaotic outputs of two such lasers is studied, with the help of parameter space plots, synchronisation error plots, phase diagrams and time series outputs. Numerical results indicate that as C increases, the system achieves synchronisation as well as stability together with an increase in the output power. The stability of the synchronised states is checked by applying a perturbation to the system after it becomes synchronised and then noting the time it takes to regain synchronisation. For lower values of C the system does not regain synchronisation. But, with higher values synchronisation is regained within a very short time.
Thomas, Kuruvilla; Nandakumaran, V M(American Institute of Physics, March , 1999)
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Abstract:
We have numerically studied the behavior of a two-mode Nd-YAG laser with an intracavity KTP crystal. It is found that when the parameter, which is a measure of the relative orientations of the KTP crystal with respect to the Nd-YAG crystal, is varied continuously, the output intensity fluctuations change from chaotic to stable behavior through a sequence of reverse period doubling bifurcations. The graph of the intensity in the X-polarized mode against that in the Y-polarized mode shows a complex pattern in the chaotic regime. The Lyapunov exponent is calculated for the chaotic and periodic regions.
Vijay,John Gerson; Jacob,Chacko; K K C Nair(National Institute of Oceanography & CUSAT, August , 2005)
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Abstract:
The present work aims at deciphering the processes that control the nutrient distribution along the EEZ (Exclusive Economic Zone of India) of the west coast of India and to bring out its linkage with primary and secondary productivity. This work assume utmost importance as very few studies have hitherto focused entirely on the EEZ of the west coast of India to address the biochemical responses brought about by monsoons. The present study examines the seasonal variations in physicochemical parameters and associated primary biological responses along the west coast of India. This study targets to measure and understand the shelf ocean exchange in a typical coastal upwelling region of the southeast Arabian Sea, and the influence of convective mixing along the northern part of the west coast of India. The study focuses more directly on coastal upwelling along the southwest coast of India, within the EEZ. The effects of coastal upwelling, eddy formation and the offshore advection are apparent in the present investigation. This has consequences to fisheries and climate, in energy transfer to the food chain and the increased sequestering of carbon in the ocean. The study also focuses on the Oxygen Minimum Zone (OMZ) and dentrification observed along the EEZ of the west coast of India on a seasonal scale. In the study, an attempt is also made to demarcate the geographical boundaries of the denitrification zone in the EEZ of India and on the nature and magnitude of these variations, on a seasonal and inter annual scales
Padma, P; Dr. Muraleedharan Nair, S(Cochin University of Science & Technology, October , 2008)
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Abstract:
This study was aimed at to characterize the spatio-temporal trends in
the distributional characteristics of various species of nitrogen and phosphorus as
well as to elucidate the factors and processes aflecting these nutrients in the
dissolved, particulate and sedimentary phases of a river estuarine system. The
main area of study is Chalakudy river in Kerala, which is a fresh water system
originating from Anamalai hills and ending at Arabian Sea. Its basin is between
I00 05 ’ to I00 35’ North latitude and 76” 15 ’ to 760 55’ East longitude. Being a
riparian bufler zone, the dynamics of nutrient mobility tend to be more complex
and variable in this river-estuarine system.The diflerent species of nitrogen estimated from the filtrate were nitrite-N, nitrateN,
ammonia-N, urea-N, total nitrogen and residual nitrogen. The diflerent forms
of phosphorus estimated from the filtrate were phosphate-P, total-P and residualP.
Pre weighed sediments as well as particulate matter were analysed for
quantijying nitrite-N, nitrate-N, ammonia-N and urea-N. Total nitrogen was estimated after digestion with potassium persulfate. Fractionation of phosphorus
in sediment/particulate matter was performed by applying sequential extraction
procedure. The dijferent forms of phosphorus thus estimated were loosely bound
(exchangeable) P, Fe/Al bound P, polyphosphates, Ca bound P and refractory P.
Sedimental total P was also measured directly by applying digestion method.The analyses carried out in this bimonthly annual survey have revealed specific
information on the latent factors influencing the water quality pattern ofthe river.
There was dependence among the chemical components of the river sediment and
suspended matter, reflecting the water quality. A period of profound
environmental change occurred and changes in various species had been noted in
association with seasonal variations in the waterway, especially following
enhanced river runoff during the monsoon. The results also successfully
represented the distribution trend of nutrients during the rainy as well as dry
season. Thus, the information gathered in this work will also be beneficial for
those interested or involved in river management, conservation, regulation and
policy making in regional and national levels.
Description:
Dept.of Chemical Oceanography,Cochin University of Science and Technology.