Mathew, K T; Robin, Augustine; Ullas, Kalappura G(Wiley InterScience, November , 2008)
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Abstract:
Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) bioceramic and
chitosan (poly [( -1-4) D-glucosamine]) biopolymer show good biocompatibility
in vivo. They have biological origin and show excellent interactions
with microwave. Microwave study of HAp made using different
drying techniques and their composites with chitosan in the ISM band is
presented. Pastes are made using HAp and chitosan with different ratios
of mixing. The dielectric properties of this composites match with that of
human fat, collagen tissues. Some of the compositions exhibit dielectric
property close to that of natural bone. This makes them more
biocompatible and better substitutes for natural bone. Thus composite
bioceramics can be considered as phantom model constituents for
imaging purposes. Their dielectric properties prove that they are
biocompatible.
Prema, K H; Dr. Philip, Kurian(Cochin University of Science and Technology, September , 2007)
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Abstract:
In the present study the preparation and characterisation of rubber ferrite
composites containing nickel ferrite and gamma ferric oxide have been dealt with.Synthetic rubbers viz. ethylene propylene diene rubber and neoprene rubber were used
for the incorporation of nickel ferrite and gamma ferric oxide for the synthesis of
RFCs. Incorporation of ferrites were carried out according to a specific recipe for
various loadings of the magnetic fillers. The ferrites used for the preparation of RFCs
were synthesised using sol-gel method and structural characterisation was carried out.
Experimental techniques like X-ray diffraction, Transmission electron microscopy and
other analytical techniques were used for this. Precharaterised ferrites were then
incorporated at different loading into rubber according to conventional mixing
methods. The cure characteristics, mechanical, dielectric, magnetic and microwave
properties of these composites were evaluated. The effect of carbon black on these
properties of RFCs were carried out.
Description:
Department of Polymer Science and Rubber Technology,
Cochin University of Science & Technology
Monz, Cabrera J; Diaz, Morcillo A; Pedreno, Molina L; Sanchez, Hermandez D(Microwave and Optical Technology Letters, February 4, 2004)
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Abstract:
Usage of a dielectric multilayer around a dielectric Sample
is studied as a means for improving the efficiency in multimode microwave-
heating cavities. The results show that by using additional dielectric
constant layers the appearance of undesired reflections at the
sample-air interface is avoided and higher power -absorption rates
within the sample and high -efficiency designs are obtained
HIV/AIDS is one of the most destructive epidemics in
ever recorded history claims an estimated 2.4 –3.3 million lives every
year. Even though there is no treatment for this pandemic Elisa and
Western Blot tests are the only tests currently available for detecting
HIV/AIDS. This article proposes a new method of detecting HIV/AIDS
based on the measurement of the dielectric properties of blood at the
microwave frequencies. The measurements were made at the S-band of
microwave frequency using rectangular cavity perturbation technique
with the samples of blood from healthy donors as well as from HIV/AIDS patients. An appreciable change is observed in the dielectric properties
of patient samples than with the normal healthy samples and these
measurements were in good agreement with clinical results. This measurement
is an alternative in vitro method of diagnosing HIV/AIDS using microwaves.
Anantharaman, M R; Muhammad, Abdul Jamal E; Joy, P A; Philip, Kurian(Elsevier, January 3, 2010)
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Abstract:
Nickel nanocomposites were prepared by incorporating nickel nanoparticles in a neoprene matrix according
to a specific recipe for various loadings of nickel particles. The dielectric properties of these composites
were evaluated for different frequencies ranging from 100 kHz to 8MHz at different temperatures from
30 ◦C to 120 ◦C. The dielectric permittivity increases with increase of nickel concentration. Increase in
temperature enhances the permittivity initially, till 40 ◦C and thereafter the permittivity decreases. The
dielectric loss exhibits relaxation peaks and the peaks shift to lower frequencies with increase in volume
fraction of the nickel nanoparticles in the matrix. The evaluation of magnetic and dielectric properties
of these composites suggests that the dielectric permittivity can be tailored by an appropriate loading of
the filler using semi-empirical equations and the magnetic properties vary according to simple mixture
equations
Description:
Materials Chemistry and Physics 121 (2010) 154–160
Sindhu, S; Dr.Anantharaman, M R(Cochin University of Science and Technology, April , 2001)
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Abstract:
The objectives of the proposed work are preparation of ceramic nickel zinc ferrite belonging to the series Ni1-XZnXFe2O4 with x varying from 0 to 1in steps of 0.2, structrural, magnetic and electrical characterization of Ni1-XZnXFe2O4, preparation and evaluation of Cure characteristics of Rubber Ferrite Composites (RFCs), magnetic characterization of RFCs using vibrating sample magnetometer (VSM), electrical characterization of RFCs and estimation of magnetostriction constant form HL parameters. The study deals with the structural and magnetic properties of ceramic fillers, variation of coercivity with composition and the variation of magnetization for different filler loadings are compared and correlated. The dielectric properties of ceramic Ni1-XZnXFe2O4 and rubber ferrite composites containing Ni1-XZnXFe2O4 were evaluated and the ac electrical conductivity (ac) of ceramic as well as composite samples can be calculated by using a simple relationship of the form ac = 2f tan 0r, with the data available from dielectric measurements. The results suggest that the ac electrical conductivity is directly proportional to the frequency
Microwave dielectric ceramics based on GdTiNb,-,.Ta,O6 and Sml _.,Y,TiTa06 have been prepared by conventional solid state
method . The GdTiTaO6 and SmTiTaO6 have aeschenite structure with positive rr and GdTiNbO6 and YTiTaO6 have euxenite
structure with negative rr. The rr of the ceramics has been tuned by preparing solid solution phases between the aeschynites and
euxenites for a possible zero rr material . It is observed that GdTiNbt_YTa.,O6 undergoes a phase transition from aeschynite to
euxenite when x=0.75 and in Sml-,YxTiTa06 for x= 0.73. The microwave dielectric properties change abruptly near the transition
region . The rr value approaches zero near the phase transition region while the samples have poor sinterability and poor quality
factor . The unloaded quality factor, dielectric constant and the sign of rr of the solid solution phases are found to depend on the
average ionic radius of the rare earth ion in RE ,-5RE',TiTaO6. The boundary of the euxenite-aeschynite phase transition occurs at
an average ( RE) ionic radius of 0.915 A in Sm,_, Y,.TiTaO6 solid solution phases