Mohammed Yusuff, K K; Sridevi, Nadimpall; Jelaja, Padmavathy(Kluwer Academic Publishers, July 20, 2000)
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Abstract:
The nature of the diperiodatocuprate(III) (DPC) species present in aqueous alkaline medium has been investigated
by a kinetic and mechanistic study on the oxidation of iodide by DPC. The reaction kinetics were studied over the
1.0 ´ 10)3±0.1 mol dm)3 alkali range. The reaction order with respect to DPC, as well as iodide, was found to be
unity when [DPC] [I)]. In the 1.0 ´ 10)3±1.0 ´ 10)2 mol dm)3 alkali region, the rate decreased with increase in
the alkali concentration and a plot of the pseudo-®rst order rate constant, k versus 1/[OH)] was linear. Above
5.0 ´ 10)2 mol dm)3, a plot of k versus [OH)] was also linear with a non-zero intercept. An increase in ionic
strength of the reaction mixtures showed no e ect on k at low alkali concentrations, whereas at high concentrations
an increase in ionic strength leads to an increase in k. A plot of 1/k versus [periodate] was linear with an intercept in
both alkali ranges. Iodine was found to accelerate the reaction at the three di erent alkali concentrations employed.
The observed results indicated the following equilibria for DPC.
Biju,Kumar; Raveendranath,U; Mohanan,P; Mathew,K T; Hajian,M; Ligthart,L P(Microwave and Optical Technology Letters, July 20, 2000)
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Abstract:
A simple and efficient method for determining the complex
permittivity of dielectric materials from both reflected and transmitted signals is presented. It is also novel because the technique is implemented using two pyramidal horns without any focusing mechanisms. The dielectric constant of a noninteractive and distributive (NID) mixture of dielectrics is also determined
Binoy,G S; Aanandan,C K; Mohanan,P; Vasudevan,K(Microwave and Optical Technology Letters, June 20, 2000)
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Abstract:
A novel dual frequency dual-polarized square microstrip
patch antenna embedded with a slot is presented. The proposed
antenna offers tunability of the frequency ratio between the two
frequencies by adjusting the slot dimensions. This configuration
also provides a size reduction up to -51 and 35% for the two modes
as compared to a square micro strip patch antenna
Zheng,Qinhong; Xie,Fuyao; Liang,Li; Wang,Ruili; Ou,Jiaming(Microwave and Optical Technology Letters, June 20, 2000)
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Abstract:
A new approach, the multipole theory (MT) method, is
presented for the computation of cutoff wavenumbers of waveguides
partially filled with dielectric. The MT formulation of the eigenvalue
problem of an inhomogeneous waveguide is derived. Representative
computational examples, including dielectric-rod-loaded rectangular and
double-ridged waveguides, are given to validate the theory, and to
demonstrate the degree of its efficiency
Sona,Kundukulam O; Manju,Paulson; Aanandan,C K; Mohanan,P; Vasudevan,K(Microwave and Optical Technology Letters, June 5, 2000)
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Abstract:
Experimental studies on a compact dual frequency microstrip
antenna are presented. This antenna configuration provides an
area reduction of 40% compared to a standard rectangular antenna
operating at the same frequency without much degradation of the gain.
The antenna structure can be modified to achieve the desired ratio
between the two resonant frequencies
Manju,Paulson; Mohanan,P; Sona,Kundukulam O(Microwave and Optical Technology Letters, September 5, 2000)
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Abstract:
A compact microstrip antenna with circular polarization radiation is demonstrated.A reducation in the required parameters for achieving CP radiation makes the present antenna design simpler
Sugunan, S; Nisha, K; Rekha, R; Rahna, K S; Suja, H; Deepa, C S(Indian Journal of Chemistry, July , 2000)
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Abstract:
The pillared montmorillonite has been prepared by exchanging
Na+ in the interlayer of montmorillonite with Al hydroxy cation followed
by calcination. Pillared clays are also prepared after exchanging
Na' ions with Ce, La, Sm-ions and then pillarcd with aluminium
oxides, The surface characterisation of the prepared catalysts has been
done using XRD and surface area measurements. To probe the acidic
property of the system, temperature programmed desorption (TPD)
of NH, has been done. Toluene alkylation by benzyl chloride has
been carried out for the evaluation of catalytic activity. The most
active system is found to be mixed Al/Zr pillarcd montrnorillonite.
Girijavallabhan, C P; Radhakrishnan, P; V P N Nampoori; Nibu, A George; George, A K(Journal of Physics D : Applied Physics, October 13, 2000)
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Abstract:
We report on a laser induced photoacoustic study of the nematic-to-isotropic
transition in certain commercial nematic liquid crystal mixtures, namely BL001, BL002,
BL032 and BL035. A simple analysis of the experimental data using the
Rosencwaig–Gersho theory shows that the heat capacities of all these compounds exhibit a
sharp peak as the temperature of the sample is varied across the transition region. Also,
substantial differences in the photoacoustic signal amplitudes in nematic and isotropic phases
have been noticed for all the mixtures. The increased light scattering property of the nematic
phase may be the reason for the enhanced photoacoustic signal amplitude in this phase.