Abdul Khalam,L; Sreemoolanadhan,H; Ratheesh,R; Mohanan,P; Sebastian,M T(ELSEVIER, 2003)
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Abstract:
Microwave dielectric resonators (DRs) based on Ba(B1,2Nbi/2)03 [B' = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Yb, and In] complex
perovskites have been prepared by conventional solid state ceramic route. The dielectric properties (relative permittivity, Er; quality factor, Q;
and resonant frequency, rr) of the ceramics have been measured in the frequency range 4-6 GHz using resonance methods. The resonators
have relatively high dielectric constant in the range 36-45, high quality factor and small temperature variation of resonant frequency. The
dielectric properties are found to depend on the tolerance factor (t), ionic radius (r), and lattice parameter (ap)
Mailadil,Sebastian T; Sam,Solomon; Ravindran,Ratheesh(Regional Research Laboratory, April , 1999)
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Abstract:
Microwave ceramic dielectric resonators (DRs) based on RETiNbO6
(RE = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Y, and Yb)
have been prepared using the conventional solid -state ceramic
route. The DR samples are characterized using XRD and SEM
methods. The microwave dielectric properties are measured
using resonant methods and a net work analyzer . The ceramics
based on Ce, Pr, Nd, and Sin have dielectric constants in the
range 32-54 and positive coefficient of thermal variation of
resonant frequency (r,). The ceramics based on Gd, Tb, Dy, Y.
and Yb have dielectric constants in the range 19-22 and
negative Tf
Mohammed Yusuff,K K; Ahmed Yasir,Vakayil; Mohandas,P N(Elsevier, International Journal of Inorganic Materials, August 12, 2001)
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Abstract:
Highly crystalline, ultra fine TiO (anatase) having high surface area has been prepared by thermal hydrolysis of titanyl sulphate 2
solution and characterized using B.E.T surface area measurements, XRD and chemical analysis. The dependence of surface area on
concentration of staffing solution, temperature of hydrolysis, duration of boiling and calcination temperature were also studied. As the
boiling temperature, duration of boiling and calcination temperature increased, the surface area of TiO formed decreased significantly. 2
On increasing calcination temperature, the crystallite size of TiO also increased and gradually the phase transformation to rutile took 2
place. The onset and completion temperatures of rutilation were 700 and 10008C, respectively
Low-protein content natural rubber latex
was produced by using a nonionic surfactant-polyethylene
glycol (PEG). Extractable protein content of natural rubber
latex was found to decrease with PEG treatment and
reduction increased with increase in the molecular weight
of PEG. The low-protein latex samples were characterized
by tensile testing, Fourier transform infrared and thermogravimetric
analysis. The results have shown 35% reduction in the extractable protein content, without any compromise
on the mechanical properties of the latex; however,
thermal stability of low-protein latex was found to be
reduced marginally with PEG treatment.
The morphological and biochemical response of calli and seedlings of different
rice cultivars were compared under acid saline conditions. Calli of
both tolerant and sensitive varieties showed severe stress symptoms like
browning and necrosis, but the onset of stress symptoms was delayed in
Pokkali. Seedlings of Pokkali showed minimal stress symptoms in lower
salinities, and curling and senescence of older leaves in higher salinities
although plants revived on amelioration of stress. Seedlings of the other
varieties showed severe stress symptoms even at low salinities and plant
death at higher salinities. Salt stress induced accumulation of the putative
osmoprotectant proline in calli and seedlings of all varieties. Proline accumulation
was higher in sensitive varieties than in Pokkali. These results
indicate that proline accumulation is not directly correlated with salt
tolerance in rice.
Issac, R C; Varier, G K; Gopinath, P; Harilal, S S; Nampoori, V P N; Vallabhan, C P G(Springer Berlin / Heidelberg, 1998)
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Abstract:
A silver target kept under partial vacuum conditions
was irradiated with focused nanosecond pulses at
1:06 mm from a Nd:YAG laser. The electron emission monitored
with a Langmuir probe shows a clear twin-peak distribution.
The first peak which is very sharp has only a small delay
and it indicates prompt electron emission with energy as
much as 60 5 eV. Also the prompt electron emission shows
a temporal profile with a width that is same as that for the
laser pulse whereas the second peak is broader, covers several
microseconds, and represents the low-energy electrons
(2 0:5 eV) associated with the laser-induced silver plasma
as revealed by time-of-flight measurements. It has been found
that prompt electrons ejected from the target collisionally
excite and ionize ambient gas molecules. Clearly resolved
rotational structure is observed in the emission spectra of
ambient nitrogen molecules. Combined with time-resolved
spectroscopy, the prompt electrons can be used as excitation
sources for various collisional excitation–relaxation experiments.
The electron density corresponding to the first peak is
estimated to be of the order of 1017 cm?--3 and it is found that
the density increases as a function of distance away from the
target. Dependence of probe current on laser intensity shows
plasma shielding at high laser intensities.
Geetha, K; Rajesh, M; Nampoori, V P N; Vallabhan, C P G; Radhakrishnan, P(Optical Society of America, 2006)
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Abstract:
The propagation characteristics of amplified spontaneous emission (ASE) through a rhodamine 6 G-doped polymethyl methacrylate freestanding film waveguide were studied. This was done by shifting the excitation stripe horizontally along a transversely pumped waveguide. By this method, we could tune the ASE wavelength. The maximum tunability thus obtained was ~18 nm with a pump stripe length of 6 mm.
Sugunan, S; Bindhu, Jacob; Binoy, Jose(Indian Journal of Chemistry, October , 1999)
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Abstract:
The results of a detailed study of the propionylation of anisole over various medium and large pore zeolites such as H-ZSM-5, H-beta, H-Na-beta. H-mordenite. H-Y and H-RE- Y are presented and discussed. In addition, homogenous catalysts and amorphous Si02-Al2O3 are also included for comparison, The catalyst and process parameters are optimised to enhance the conversion of propionyl chloride(PC) and selectivity to 4-methoxypropiophenone(4-MOPP).
Bindhu, C V; Harilal, S S; Riju C, Issac; Nampoori, V P N; Vallabhan, C P G(World Scientific Puhlishing Company, 1996)
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Abstract:
Pulsed photoacoustic technique which is found to be a very convenient and accurate method, is used for the determination of absolute fluorescence quantum yield of laser dye rhodamine B. Concentration and power dependence of quantum yield of rhodamine B in methanol for excitation at 532 nm is reported here. Results show that a rapid decrease in quantum yield as the concentration is increased and finally it reaches the limit corresponding to fluorescence quenching.
Bindhu, C V; Harilal, S S; Issac, Riju C; Geetha K, Varier; Nampoori, V P N; Vallabhan, C P G(Pramana, March , 1995)
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Abstract:
Pulsed photoacoustic measurements have been carried out in toluene at 532 nm
wavelength using a Q-switched frequency doubled Nd:YAG laser. The variation of photoacoustic
signal amplitude with incident laser power indicates that at lower laser powers one
photon absorption takes place at this wavelength while a clear two photon absorption occurs in
this liquid at higher laser powers. The studies made here demonstrate that pulsed photoacoustic
technique is simple and effective for the investigation of multiphoton processes in
liquids.
The propagation of pulse waves in coplanar waveguides
(CPWs) is investigated, and these CPWs are assumed to be fabricated
on a single -layer low- temperature co-fired ceramic (LTCC) substrate.
The input pulse wave can be a Gaussian pulse or a sinusoldally modulated
Gaussian pulse. Based on the standard Galerkin 's method in the
spectral domain, combined with fast Fourier transform (FFT), the pulse
waveform and delay in CPWs are demonstrated and compared for a second plate, oriented orthogonally to the primary planar element,
thus producing a crossed planar monopole (CPM), which is
simpler to produce and has lower cost than a conical monopole. In
this paper, further measurements have been made on this element
Girish Kumar,K; Remalakshmy,Poduval; Sareena,John; Pearl,Augustine(Departmenrt of Applied Chemistry, May 11, 2006)
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Abstract:
A new PVC membrane sensor, which is
highly selective towards Ni (II) ions, has been developed
using a thiophene-derivative Schiff base as the
ionophore. The best performance was exhibited by the
membrane having the composition percentage ratio of
5:3:61:31 (ionophore:NaTPB:DBP:PVC) (w=w), where
NaTPB is the anion excluder, sodium tetraphenylborate
and DBP is the plasticizing agent (dibutyl phthalate).
The membrane exhibited a good Nernstian response for
nickel ions over the concentration range of 1.0 10 1–
5.0 10 6M (limit of detection is 1.8 10 6 M) with a
slope of 29.5 1.0mV per decade of activity. It has a
fast response time of<20 s and can be used for a period
of 4 months with good reproducibility. The sensor is
suitable for use in aqueous solutions of a wide pH range
of 3.2–7.9. The sensor shows high selectivity to nickel
ions over a large number of mono-, bi- and trivalent
cations. It has been successfully used as an indicator
electrode in the potentiometric titration of nickel ions
against EDTA and also for direct determination of
nickel content in real samples – wastewater samples
from electroplating industries and Indian chocolates.
Girish Kumar,K; Remalakshmy,Poduval; Sareena,John; Pearl,Augustine(Department of Applied Chemistry, May 11, 2006)
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Abstract:
A new PVC membrane sensor, which is
highly selective towards Ni (II) ions, has been developed
using a thiophene-derivative Schiff base as the
ionophore. The best performance was exhibited by the
membrane having the composition percentage ratio of
5:3:61:31 (ionophore:NaTPB:DBP:PVC) (w=w), where
NaTPB is the anion excluder, sodium tetraphenylborate
and DBP is the plasticizing agent (dibutyl phthalate).
The membrane exhibited a good Nernstian response for
nickel ions over the concentration range of 1.0 10 1–
5.0 10 6M (limit of detection is 1.8 10 6 M) with a
slope of 29.5 1.0mV per decade of activity. It has a
fast response time of<20 s and can be used for a period
of 4 months with good reproducibility. The sensor is
suitable for use in aqueous solutions of a wide pH range
of 3.2–7.9. The sensor shows high selectivity to nickel
ions over a large number of mono-, bi- and trivalent
cations. It has been successfully used as an indicator
electrode in the potentiometric titration of nickel ions
against EDTA and also for direct determination of
nickel content in real samples – wastewater samples
from electroplating industries and Indian chocolates.
Girish Kumar,K; Pearl,Augustine; Sareena,John; Beena,Saraswathyamma(Department of Applied Chemistry, June 12, 2006)
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Abstract:
new PVC membrane ion selective electrode which is highly selective towards Ni(II) ions was constructed using a
Schiff base containing a binaphthyl moiety as the ionophore. The sensor exhibited a good Nernstian response for nickel
ions over the concentration range 1.0 × 10–1 – 5.0 × 10–6 M with a lower limit of detection of 1.3 × 10–6 M. It has a fast
response time and can be used for a period of 4 months with a good reproducibility. The sensor is suitable for use in
aqueous solutions in a wide pH range of 3.6 – 7.4 and works satisfactorily in the presence of 25% (v/v) methanol or
ethanol. The sensor shows high selectivity to nickel ions over a wide variety of cations. It has been successfully used as
an indicator electrode in the potentiometric titration of nickel ions against EDTA and also for the direct determination of
nickel content in real samples: effluent samples, chocolates and hydrogenated oils.
PVC supported liquid membrane and carbon paste potentiometric sensors incorporating an Mn(III)-porphyrin
complex as a neutral host molecule were developed for the determination of paracetamol. The measurements were
carried out in solution at pH 5.5. Under such conditions paracetamol exists as a neutral molecule. The mechanism of
molecular recognition between the Mn(III)-porphyrin and paracetamol, leading to potentiometric signal generation,
is discussed.The sensitivity and selectivity toward paracetamol of carbon paste and polymeric liquid membrane electrodes
incorporating an Mn(III)-porphyrin host were compared. The applicability of these sensors to the direct
determination of paracetamol was checked by performing a recovery test in human plasma.