In this paper, a multiband antenna using a novel
fractal design is presented. The antenna structure is formed
by inscribing a hexagonal slot within a circle. This base
structure is then scaled and arranged within the hexagon
along its sides without touching the outer structure. The
proposed CPW fed, low profile antenna offers good
performance in the 1.65 – 2.59 GHz, 4.16 – 4.52 GHz and
5.54 – 6.42 GHz bands and is suitable for GSM 1800/1900,
Bluetooth, IMT advanced systems and upper WLAN
applications. The antenna has been fabricated on a substrate
of height 1.6 mm and εr = 4.4 and simulation and
experimental results are found to be in good agreement
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.
Girish Kumar,K; Pearl, Augustine; Sareena, John(Springer, August 29, 2009)
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Abstract:
The fabrication and electrochemical response
characteristics of two novel potentiometric sensors for the
selective determination of domperidone (DOM) are described.
The two fabricated sensors incorporate DOM–PTA
(phosphotungstic acid) ion pair as the electroactive material.
The sensors include a PVC membrane sensor and a carbon
paste sensor. The sensors showed a linear, stable, and near
Nernstian slope of 56.5 and 57.8 mV/decade for PVC
membrane and carbon paste sensors, respectively over a
relatively wide range of DOM concentration (1.0 9
10-1–1.0 9 10-5 and 1.0 9 10-1–3.55 9 10-6 M). The
response time of DOM–PTA membrane sensor was less than
25 s and that in the case of carbon paste sensor was less than
20 s.Auseful pH range of 4–6 was obtained for both types of
sensors. A detection limit of 7.36 9 10-5 M was obtained
for PVC membrane sensor and 1.0 9 10-6 M was obtained
for carbon paste sensor. The proposed sensors showed very
good selectivity toDOMin the presence of a large number of
other interfering ions. The analytical application of the
developed sensors in the determination of the drug in pharmaceutical
formulations such as tablets was investigated.
The results obtained are in good agreement with the values
obtained by the standard method. The sensors were also
applied for the determination ofDOMin real samples such as
urine by the standard addition method.
Description:
J Appl Electrochem (2010) 40:65–71
DOI 10.1007/s10800-009-9975-2
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
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
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.
Poulose Jacob,K; Shahana, T K; Babita, Jose R; Sreela Sasi(Taylor & Francis, May 1, 2009)
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Abstract:
Animportant step in the residue number system(RNS) based signal processing is the
conversion of signal into residue domain. Many implementations of this conversion
have been proposed for various goals, and one of the implementations is by a direct
conversion from an analogue input. A novel approach for analogue-to-residue
conversion is proposed in this research using the most popular Sigma–Delta
analogue-to-digital converter (SD-ADC). In this approach, the front end is the same
as in traditional SD-ADC that uses Sigma–Delta (SD) modulator with appropriate
dynamic range, but the filtering is doneby a filter implemented usingRNSarithmetic.
Hence, the natural output of the filter is an RNS representation of the input signal.
The resolution, conversion speed, hardware complexity and cost of implementation
of the proposed SD based analogue-to-residue converter are compared with the
existing analogue-to-residue converters based on Nyquist rate ADCs
Description:
International Journal of Electronics
Vol. 96, No. 6, June 2009, 571–583
Jagathy Raj, V P; Praveen, R P; Ravichandran, M H; Sadasivan Achari, V T; Madhu, G; Bindu, G R(IEEE, September , 2012)
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Abstract:
This paper presents the design and analysis of a novel
machine family—the enclosed-rotor Halbach-array permanentmagnet
brushless dcmotors for spacecraft applications. The initial
design, selection of major parameters, and air-gap magnetic flux
density are estimated using the analytical model of the machine.
The proportion of the Halbach array in the machine is optimized
using finite element analysis to obtain a near-trapezoidal flux
pattern. The machine is found to provide uniform air-gap flux
density along the radius, thus avoiding circulating currents in stator
conductors and thereby reducing torque ripple. Furthermore,
the design is validated with experimental results on a fabricated
machine and is found to suit the design requirements of critical
spacecraft applications
Description:
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 59, NO. 9, SEPTEMBER 2012
Jagathy Raj, V P; Praveen, R P; Ravichandran, M H; Sadasivan Achari, V T; Madhu, G; Bindu, G R(IEEE, October 7, 2010)
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Abstract:
This paper presents the design and analysis of a novel
machine family of Siotiess Permanent Magnet Brushless DC
motors (PMBLDC) for precise positioning applications of
spacecrafts. Initial design, selection of major parameters and air
gap magnetic flux density are estimated using the analytical
model of the machine. The proportion of the halbach array in the
machine was optimized using FE to obtain near trapezoidal flux
pattern. The novel machine topology is found to deliver high
torque density, high efficiency, zero cogging torque, better
positional stability, high torque to inertia ratio and zero magnetic
stiction suiting space requirements. The machine provides
uniform air gap flux density along the radius thus avoiding
circulating currents in stator conductors and hence reducing
torque ripple
Description:
Communication Control and Computing Technologies (ICCCCT), 2010 IEEE International Conference on
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.
Anu Jose; G. Vijay Nair(Cochin University of Science and Technology, August 21, 2014)
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Abstract:
Carbon-carbon and carbon-heteroatom bond formations constitute the
central events in organic synthesis. In view of this, much of the research in
organic synthesis has been focused on devising novel and efficient methods for
such bond constructions. In general, polar, pericyclic and radical methodologies
are employed for this purpose. The polar and radical reactions proceed via
reactive intermediates such as carbanions, enols/enolates, enamines, carbocations,
radical cations, radical anions, carbenes, zwitterions etc. In recent years, there has
been enormous interest in the chemistry of zwitterionic species largely from the
standpoint of their applications in multicomponent reactions (MCRs) and
organocatalytic reactions. Zwitterions formed by the addition of nucleophiles to
electrophilic π-systems such as acetylenic esters and azoesters have been the
subject of extensive investigations; their synthetic utility, however, remained
largely unexplored. Investigations in a number of laboratories, including our own,
have shown that zwitterions of the type mentioned above on reaction with
electrophiles give rise to carbo- and heterocyclic products by 1,3- or 1,4-dipolar
cycloadditions. Recently, allenoates, another class of active π-systems were
introduced to this field. Against this background, a systematic investigation of the
reactions of various zwitterions derived from allenoates with different
electrophiles especially 1,2-diones, were carried out. The results of these studies
are embodied in the thesis entitled “Novel Synthesis of Carbocycles and
Heterocycles Employing Zwitterions Derived from Allenic Esters”.
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.
Rakesh N.; Dr. Prathapan S.(Cochin University of Science and Technology, December 13, 2015)
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Abstract:
Nitrones or azomethine-N-oxides are important precursors for the synthesis of several heterocyclic systems. They belong to the allyl anion type 1,3-dipoles and possess unique structural features which make them extraordinarily useful synthons. They behave as 1,3-dipoles in 1,3-dipolar cycloaddition reactions and as electrophiles in reactions with organometallic reagents. These are the two basic reactions given by nitrones. Nitrones also act as ‘spin traps’ in which they react with short-lived radicals to furnish stable nitroxide radicals which can be detected and identified by electron paramagnetic resonance (EPR) spectroscopy. Recently SmI2 catalysed reductive cross-coupling reactions of nitrones have gained significant interest in which the reactions are initiated by single electron transfer (SET) to nitrones. Apart from these reactions, nitrones are also known to participate in reactions which are initiated by the nucleophilic attack of nitrone-oxygen. In our group, we have also explored the nucleophilic character of nitrones through various reactions. The results obtained enabled us to develop a novel two-step one-pot strategy for quinolines and indoles - the heterocycles renowned for their pharmacological applications, from nitrones and electron deficient acetylenes. Using dibenzoylacetylene and phenylbenzoylacetylene as dipolarophiles, we could introduce a desired functional group at a predetermined position of the quinolines or indoles to be synthesised. In this context, the thesis entitled “NUCLEOPHILIC ADDITION OF NITRONES TO ELECTRON DEFICIENT ACETYLENES AND RELATED STUDIES” portrays our attempt to expand the scope of our
x
novel synthetic protocol using ester functionalised acetylenes: dimethyl acetylenedicarboxylate (DMAD) and methyl propiolate.
The thesis is organised in to five chapters. The first chapter briefly describes the different classes of reactions that nitrone functionality can tolerate. The research problem is defined at the end of this chapter. The second chapter describes the synthesis of different nitrones used for the present study. The optimisation and expansion of scope of the novel strategy towards quinoline synthesis is discussed in the third chapter. The fourth chapter portrays the synthesis of indole-3-carboxylates using the novel strategy. In the fifth chapter, the reaction of N-(2,6-dimethylphenyl) and N-(2,4,6-trimethylphenyl)nitrones are discussed. Here we also discuss the mechanistic reinvestigation of Baldwin’s proposal in the isoxazoline-oxazoline rearrangement. The major outcome of the work is given at the end of the thesis.
The structural formulae, schemes, tables and figures are numbered chapter-wise since each chapter of the thesis is organized as an independent unit. All new compounds (except two compounds reported in fourth chapter) are fully characterised on the basis of spectral and analytical data and single crystal X-ray analysis on representative examples. Relevant references are included at the end of individual chapters.