Poly(6-tert-butyl-3,4-dihydro-2H-1,3-benzoxazine) was synthesized by
thermally activated cationic ring opening polymerization. The structure of the
polymer was confirmed by spectral and thermal studies. The highest occupied
molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were
estimated using cyclic voltammetry and optical absorption. Modulated photocurrent
measurement technique was employed to study the spectral and field dependence of
photocurrent. Photocurrent of the order of 1.5 micro A/m2 was obtained for polymer at a
biasing electric field of 40 V/mico m.
Annieta, Philip K; Lyjo, Joseph K; Litty, Irimpan; Radhakrishnan, P; Nampoori, V P N(Department of Photonics, 2004)
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Abstract:
Laser induced photoacoustic (PA) technique is used in the study of photostability of polymethyl
methacrylate (PMMA) films doped with Rhodamine 6G -Rhodamine B dye system. Energy transfer from a donor
molecule to an acceptor molecule in a dye mixture affects the output of the dye system. Details of investigations on
the role of laser power, modulation frequency and the irradiation wavelength on the photosensitivity of the dye
mixture doped PMMA films are presented.
We have performed thermal diffusion measurements
of nanofluid containing gold and rhodamine 6G dye
in various ratios. At certain concentrations, gold is nearly
four times more efficient than water in dissipating small
temperature fluctuations in a medium, and therefore it will
find applications as heat transfer fluids. We have employed
dual-beam mode-matched thermal lens technique for the
present investigation. It is a sensitive technique in measuring
photothermal parameters because of the use of a lowpower,
stabilized laser source as the probe. We also present
the results of fluorescence measurements of the dye in the
nanogold environment.
Girijavallabhan, C P; Radhakrishnan, P; Nampoori, V P N; Sajan, D George(Physical Review, American Physical Society, October 16, 2003)
[+]
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Abstract:
In this paper, we report the in-plane and cross-plane measurements of the thermal diffusivity of double
epitaxial layers of n-type GaAs doped with various concentrations of Si and a p-type Be-doped GaAs layer
grown on a GaAs substrate by the molecular beam epitaxial method, using the laser-induced nondestructive
photothermal deflection technique. The thermal diffusivity value is evaluated from the slope of the graph of the
phase of the photothermal deflection signal as a function of pump-probe offset. Analysis of the data shows that
the cross-plane thermal diffusivity is less than that of the in-plane thermal diffusivity. It is also seen that the
doping concentration has a great influence on the thermal diffusivity value. Measurement of p-type Be-doped
samples shows that the nature of the dopant also influences the effective thermal diffusivity value. The results
are interpreted in terms of a phonon-assisted heat transfer mechanism and the various scattering process
involved in the propagation of phonons.
Radhakrishnan, P; V P N Nampoori; Girijavallabhan, C P; Sajan, D George(Physical Review, American Physical Society, 2003)
[+]
[-]
Abstract:
In this paper, we report the in-plane and cross-plane measurements of the thermal diffusivity of double
epitaxial layers of n-type GaAs doped with various concentrations of Si and a p-type Be-doped GaAs layer
grown on a GaAs substrate by the molecular beam epitaxial method, using the laser-induced nondestructive
photothermal deflection technique. The thermal diffusivity value is evaluated from the slope of the graph of the
phase of the photothermal deflection signal as a function of pump-probe offset. Analysis of the data shows that
the cross-plane thermal diffusivity is less than that of the in-plane thermal diffusivity. It is also seen that the
doping concentration has a great influence on the thermal diffusivity value. Measurement of p-type Be-doped
samples shows that the nature of the dopant also influences the effective thermal diffusivity value. The results
are interpreted in terms of a phonon-assisted heat transfer mechanism and the various scattering process
involved in the propagation of phonons
V P N Nampoori; Radhakrishnan, P; Girijavallabhan, C P; Sajan, D George(Physical Review, American Physical Society, 2003)
[+]
[-]
Abstract:
In this paper, we report the in-plane and cross-plane measurements of the thermal diffusivity of double
epitaxial layers of n-type GaAs doped with various concentrations of Si and a p-type Be-doped GaAs layer
grown on a GaAs substrate by the molecular beam epitaxial method, using the laser-induced nondestructive
photothermal deflection technique. The thermal diffusivity value is evaluated from the slope of the graph of the
phase of the photothermal deflection signal as a function of pump-probe offset. Analysis of the data shows that
the cross-plane thermal diffusivity is less than that of the in-plane thermal diffusivity. It is also seen that the
doping concentration has a great influence on the thermal diffusivity value. Measurement of p-type Be-doped
samples shows that the nature of the dopant also influences the effective thermal diffusivity value. The results
are interpreted in terms of a phonon-assisted heat transfer mechanism and the various scattering process
involved in the propagation of phonons
Nibu, A George; Vallabhan, C P G; Nampoori, V P N; Radhakrishnan, P(Optical Society of America, August , 2002)
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Abstract:
Photothermal beam deflection studies were carried out with GaAs epitaxial double layers grown on semi-insulating GaAs substrates. The impurity densities in thin epitaxial layers were found to influence the effective thermal diffusivity of the entire structure.
George, S D; Radhakrishnan, P; Nampoori, V P N; Vallabhan, C P G(Springer-Verlag, 2003)
[+]
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Abstract:
Laser induced transverse photothermal deflection
technique has been employed to determine the thermal parameters
of InP doped with Sn, S and Fe as well as intrinsic
InP. The thermal diffusivity values of these various samples
are evaluated from the slope of the curve plotted between the
phase of photothermal deflection signal and pump-probe offset.
Analysis of the data shows that heat transport and hence
the thermal diffusivity value, is greatly affected by the introduction
of dopant. It is also seen that the direction of heat flow with
respect to the plane of cleavage of semiconductor wafers influences
the thermal diffusivity value. The results are explained in
terms of dominating phonon assisted heat transfer mechanism in semiconductors.
Girijavallabhan, C P; Radhakrishnan, P; V P N Nampoori; Kumar, G A; Thomas, J; Unnikrishnan, N V; George, N(Journal of Materials Science ,Kluwer Academic Publishers, 2000)
[+]
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Abstract:
Physical and optical properties of various free base and metallic phthalocyanine (Pc) doped
glass matrix are reported for the first time. Absorption spectral measurements of H2Pc,
MnPc, NiPc, CoPc, CuPc, MoOPc, ZnPc and FePc doped borate glass matrix have been
made in the 200–1100 nm region and the spectra obtained are analyzed in the 2.1–6.2 eV
region to obtain the optical band gap (Eg) and the width of the band tail (Et). Other
important optical and physical parameters viz. refractive index (n), molar extinction
coefficient ("), density (½), glass transition temperature (Tg), molecular concentration (N ),
polaron radius (rp), intermolecular separation (R), molar refractivity (Rm) are also reported
Radhakrishnan, P; Nampoori, V P N; Girijavallabhan, C P; Kumar, G A; Thomas, J; Unnikrishnan, N V; George, N(Journal of Materials Science ,Kluwer Academic Publishers, 2000)
[+]
[-]
Abstract:
Physical and optical properties of various free base and metallic phthalocyanine (Pc) doped
glass matrix are reported for the first time. Absorption spectral measurements of H2Pc,
MnPc, NiPc, CoPc, CuPc, MoOPc, ZnPc and FePc doped borate glass matrix have been
made in the 200–1100 nm region and the spectra obtained are analyzed in the 2.1–6.2 eV
region to obtain the optical band gap (Eg) and the width of the band tail (Et). Other
important optical and physical parameters viz. refractive index (n), molar extinction
coefficient ("), density (½), glass transition temperature (Tg), molecular concentration (N ),
polaron radius (rp), intermolecular separation (R), molar refractivity (Rm) are also reported.
Nampoori, V P N; Radhakrishnan, P; Girijavallabhan, C P; Kumar, G A; Thomas, J; Unnikrishnan, N V; George, N(Journal of Materials Science ,Kluwer Academic Publishers, 2000)
[+]
[-]
Abstract:
Physical and optical properties of various free base and metallic phthalocyanine (Pc) doped
glass matrix are reported for the first time. Absorption spectral measurements of H2Pc,
MnPc, NiPc, CoPc, CuPc, MoOPc, ZnPc and FePc doped borate glass matrix have been
made in the 200–1100 nm region and the spectra obtained are analyzed in the 2.1–6.2 eV
region to obtain the optical band gap (Eg) and the width of the band tail (Et). Other
important optical and physical parameters viz. refractive index (n), molar extinction
coefficient ("), density (½), glass transition temperature (Tg), molecular concentration (N ),
polaron radius (rp), intermolecular separation (R), molar refractivity (Rm) are also reported.
Santhosh Kumar, G(Cochin University of Science And Technology, September 29, 2013)
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Abstract:
Science is search for the laws of underlying phenomena of the nature. Engineering
constructs the nature as we wish. Interestingly the huge engineering infrastructure like world
wide web has grown in such a complex structure such that we need to see the fundamental
science behind the structure and behaviour of these networks. This talk covers the science
behind the complex networks like web, biological, social etc. The talk aim to discuss the
basic theories that govern the static as well as the dynamics of such interesting networks
In the current study, the duckweed aquatic macrophyte Spirodela polyrrhiza was employed for assessing the toxicity of two wetlands in the Eloor industrial estate, Ernakulam district, Kerala, South India. The assessments were made according to OECD guidelines for testing (2006). The studies involve study of growth parameters, Growth Index, Biomass and changes in productivity. The water samples were collected from two different wetland sites at the same time. The spirodela plants were introduced into several dilutions of wetland water samples. The parameters were measured after 7 days of exposure. All samples except control affected all parameters. The results of this study emphasize the significance of duckweeds as standard and reliable testing material for biological parameters in polluted aquatic ecosystem
Description:
IOSR Journal Of Environmental Science, Toxicology And Food Technology (IOSR-JESTFT),Volume 1, Issue 6 (Nov. - Dec. 2012), PP 44-49
Viswanathan,M; Siow,Y L; Paulose,C S; Dakshinamurti,K(Department of Biotechnology, May 24, 1988)
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Abstract:
Pvridoxine deficiency causes physiologically significant decrease in brain serotonin (5-HT) due to decreased decarboxylation of 5-
hvdroxvtrvptophan (5-HTP). We have examined the effect of pyridoxine deficiency on indoleamine metabolism in the pineal gland, a
tissue with high indoleamine turnover. Adult male Sprague-Dawley rats were fed either a pyridoxine-supplemented or pyridoxinedeficient
diet for 8 weeks. Pyridoxine deficiency did not alter the pattern of circadian rhythm of pineal 5-HT. 5-hvdroxvindoleacetic
acid (5-HIAA), V-acetvlserotonin (NAS). and melatonin. However the levels of these compounds were significantly lower in the
pineal glands of pyridoxine-deficient animals. Pineal 5-HTP levels were consistently higher in the pyridoxine-deficient animals and a
conspicuous increase was noticed at 22.00 h. Increase in pineal NAS and melatonin levels caused by isoproterenol (5 mg kg at 17.00 h)
were significantly lower (P < 0.05) in the pyridoxine-deficient animals. Treatment of pyridoxine-deficient rats with pvridoxine restored
the levels of pineal 5-HT, 5-HIAA. NAS. and melatonin to values seen in pyridoxine-supplemented control animals. These results
suggest that 5-HT availability could be an important factor in the regulation of the synthesis of pineal NAS and melatonin.
Mridula, S; Anila, P V; Indhu, K K; Nijas, C M; Sujith, R; Mohanan, P(Wiley Subscription Services, Inc., A Wiley Company, March 1, 2014)
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Abstract:
An electrically small, broadband-modified, truncated
ground metamaterial EZ antenna is presented. This, a modified EZ
antenna system, achieves a larger bandwidth of the order of 650 MHz
by adjusting the metamaterial-inspired meandered ground element fed
by a top loaded monopole. The design is devoid of the large ground
planes and the external parasitic elements used in conventional
designs for achieving proper impedance matching characteristics. The
antenna requires a small foot print of kg/5 3 kg/10, where kg is the
guided wavelength corresponding to the lowest frequency of operation,
when printed on a substrate of dielectric constant 4.4 and thickness
1.6 mm. The antenna offers a 2:1 VSWR bandwidth from 750
MHz to 1.4 GHz, which covers CDMA, GSM, and ISM bands
Description:
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS / Vol. 56, No. 3, March 2014
Mridula, S; Sreedevi, Menon K; Lethakumary,B; Binu, Paul; Aanandan,C K; Mohanan, P(Microwave and Optical Technology Letters, July 20, 2002)
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Abstract:
A broadband rectangular tnicrostrip antenna utilizing
an electromagnetically coupled L-strip feed is presented. Experimental
study shows a 2:1 VSWR bandwidth of a 10% and excellent
cross-polarization performance with a radiation coverage almost as
same as that of the rectangular microstrip antenna fed by conventional
methods. The variation of bandwidth for different feed parameters is also studied. The proposed antenna is suitable for broadband
communications
Mridula, S; Sarah, Jacob; Aanandan,C K; Shameena, V A; Mohanan, P; Vasudevan, K(Wiley Periodicals, December 2, 2011)
[+]
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Abstract:
A compact coplanar waveguide-fed (CPW) monopole antenna for ultra-wideband
wireless communication is presented. The proposed antenna comprises of a CPW-fed
beveled rectangular patch with a modified slotted ground. The overall size of the antenna is
30 mm 27 mm 1.6 mm. The lower edge of the band is attained by properly decoupling
the resonant frequencies due to the extended ground plane and the beveled rectangular
patch of the antenna. The upper edge of the radiating band is enhanced by beveling the
ground plane corners near the feed point. Experimental results show that the designed
antenna operates in the 2.7–12 GHz band, for S11 10 dB with a gain of 2.7–5 dBi. Both
the frequency domain and time domain characteristics of the antenna are investigated using
antenna transfer function. It is observed that the antenna exhibits identical radiation patterns
and reasonable transient characteristics over the entire operating band
Description:
International Journal of RF and Microwave Computer‐Aided Engineering,VOL 22,issue 5,pp 594-602