186 research outputs found
Formulation and evaluation of timed delayed capsule device for Chronotherapeutic Delivery of Terbutaline Sulphate.
The aim of the present study was to develop timed delayed capsule device of terbutaline sulphate intended for chronotherapy. A time delayed capsule was prepared by sealing the drug tablet and the expulsion excipient inside the insoluble hard gelatin capsule body with erodible tablet plug. The erodible tablets were prepared by direct compression. Influence of formulation factors such as type of plug material, different plug composition, erodible tablet weight and hardness was investigated to characterize the lag time (t10). The results indicated that drug release from the time delayed capsule exhibited an initial lag period, followed by a stage of rapid drug release. Erodible tablet plugs prepared using higher molecular weight of polyethylene oxide resulted in longer lag times. A good correlation was observed between erodible tablet weight and lag time. In accordance with the chronomodulated therapy of asthma the lag time criterion of 5hrs was satisfied by formulation containing 90mg of WSR N-10 (low molecular weight polyethylene oxide) in the erodible tablet plug
Protonated chiral prolinamide catalyzed enantioselective direct aldol reaction in water
Protonated chiral prolinamide organocatalysts have been shown to catalyze an enantioselective direct aldol process in water to provide the aldol product in high yield and good enantioselectivity. The two diastereomeric catalysts (S,R)-4b and (S,S)-4c show different reactivity. © 2005 Elsevier Ltd. All rights reserved
Synthesis of Nanostructured Tin Oxide (SnO2) Powders and Thin Films Prepared by Sol-Gel Method
Nanocrystalline SnO2 powder was successfully prepared by using simple sol-gel technique. The sol-gel
obtained was washed and calcinated at 400 C to obtain the SnO2 nano-powder. The structural property of
(SnO2) nanocrystalline powder was investigated by using X-ray diffraction (XRD) technique. The optical
properties were studied using Uv-Vis Spectroscopy, by recording the absorbance and transmittance spectra.
The XRD pattern of the as-prepared sample demonstrated the formation of a rutile structure of SnO2
nanocrystallites. The Scanning Electron Microscopic (SEM) analysis showed a homogeneous distribution of
quite small grains over scanned area. The Uv-Vis absorbance spectra also showed a characteristic peak of
absorbance at 312 nm corresponding to SnO2. The energy band gap measurement for nanocrystalline
SnO2 thin film was done from the graph of variation of (hν)2 versus hν. The measured value of optical
bandgap energies for SnO2 thin film is 3.78 eV. The results show that the transmittance of the synthesized
SnO2 film is 78 % in the spectral range 350 nm to 800 nm
Synthesis of Nanostructured Tin Oxide (SnO2) Powders and Thin Films Prepared by Sol-Gel Method
Nanocrystalline SnO2 powder was successfully prepared by using simple sol-gel technique. The sol-gel
obtained was washed and calcinated at 400 C to obtain the SnO2 nano-powder. The structural property of
(SnO2) nanocrystalline powder was investigated by using X-ray diffraction (XRD) technique. The optical
properties were studied using Uv-Vis Spectroscopy, by recording the absorbance and transmittance spectra.
The XRD pattern of the as-prepared sample demonstrated the formation of a rutile structure of SnO2
nanocrystallites. The Scanning Electron Microscopic (SEM) analysis showed a homogeneous distribution of
quite small grains over scanned area. The Uv-Vis absorbance spectra also showed a characteristic peak of
absorbance at 312 nm corresponding to SnO2. The energy band gap measurement for nanocrystalline
SnO2 thin film was done from the graph of variation of (hν)2 versus hν. The measured value of optical
bandgap energies for SnO2 thin film is 3.78 eV. The results show that the transmittance of the synthesized
SnO2 film is 78 % in the spectral range 350 nm to 800 nm
Spray Deposited Nanocrystalline ZnO Transparent Electrodes: Role of Precursor Solvent
Nanocrystalline ZnO thin films were deposited by intermittent spray pyrolysis using different alcoholic and aqua-alcoholic precursor solvents. The XRD analysis reveals the polycrystallinity of hexagonal wurtzite type ZnO films with preferred c-axis orientation along [002] direction. The polycrystallinity increased due to use of aqua-alcoholic precursor solvent. The crystallite size was found to vary from 41.7 nm to 59.4 nm and blue shift in band-gap energy (3.225 eV to 3.255 eV) was observed due to aqua-alcoholic to alcoholic precursor solvent transition. The films deposited using alcoholic precursor solvent exhibited high transmittance (> 92 %) with low dark resistivity (10 – 3 Ω·cm) as compared to aqua-alcoholic precursor solvent. The effect of precursor solvent on resistivity, carrier concentration (η – /cm3), carrier mobility (μ – cm2V – 1s – 1), sheet resistance (Ω/) and figure of merit (ΦTC) is also reported. We recommend ethanol or methanol as a superior precursor solvent over aqua-alcoholic precursor solvent for deposition of device quality ZnO thin films
EFFECT OF DIFFERENT VANE ANGLE ON COMPRESSION RATIO AND SHAFT OUTPUT OF A ROTARY VANE ENGINE
Mostly in all automobiles reciprocating I.C. engines are used in spite of having some lacunas i.e. incomplete combustion of fuel, due to which lower thermal efficiency obtained. It having more nos. of moving parts due to which balancing of engine becomes a tedicious task. Also weight to power ratio of engine becomes excessively high. This paper describes a new concept of rotary vane type engine. An alternative approach to reciprocating engine. In this article author has chosen stator, rotor and different vanes i.e. 4, 6, & 8 for optimizing compression ratio, cubic capacity and brake horse power at 6000 rpm
The Dependence of the Superconducting Transition Temperature of Organic Molecular Crystals on Intrinsically Non-Magnetic Disorder: a Signature of either Unconventional Superconductivity or Novel Local Magnetic Moment Formation
We give a theoretical analysis of published experimental studies of the
effects of impurities and disorder on the superconducting transition
temperature, T_c, of the organic molecular crystals kappa-ET_2X and beta-ET_2X
(where ET is bis(ethylenedithio)tetrathiafulvalene and X is an anion eg I_3).
The Abrikosov-Gorkov (AG) formula describes the suppression of T_c both by
magnetic impurities in singlet superconductors, including s-wave
superconductors and by non-magnetic impurities in a non-s-wave superconductor.
We show that various sources of disorder lead to the suppression of T_c as
described by the AG formula. This is confirmed by the excellent fit to the
data, the fact that these materials are in the clean limit and the excellent
agreement between the value of the interlayer hopping integral, t_perp,
calculated from this fit and the value of t_perp found from angular-dependant
magnetoresistance and quantum oscillation experiments. If the disorder is, as
seems most likely, non-magnetic then the pairing state cannot be s-wave. We
show that the cooling rate dependence of the magnetisation is inconsistent with
paramagnetic impurities. Triplet pairing is ruled out by several experiments.
If the disorder is non-magnetic then this implies that l>=2, in which case
Occam's razor suggests that d-wave pairing is realised. Given the proximity of
these materials to an antiferromagnetic Mott transition, it is possible that
the disorder leads to the formation of local magnetic moments via some novel
mechanism. Thus we conclude that either kappa-ET_2X and beta-ET_2X are d-wave
superconductors or else they display a novel mechanism for the formation of
localised moments. We suggest systematic experiments to differentiate between
these scenarios.Comment: 18 pages, 5 figure
Azimuthal anisotropy and correlations in p+p, d+Au and Au+Au collisions at 200 GeV
We present the first measurement of directed flow () at RHIC. is
found to be consistent with zero at pseudorapidities from -1.2 to 1.2,
then rises to the level of a couple of percent over the range . The latter observation is similar to data from NA49 if the SPS rapidities
are shifted by the difference in beam rapidity between RHIC and SPS.
Back-to-back jets emitted out-of-plane are found to be suppressed more if
compared to those emitted in-plane, which is consistent with {\it jet
quenching}. Using the scalar product method, we systematically compared
azimuthal correlations from p+p, d+Au and Au+Au collisions. Flow and non-flow
from these three different collision systems are discussed.Comment: Quark Matter 2004 proceeding, 4 pages, 3 figure
Azimuthal anisotropy: the higher harmonics
We report the first observations of the fourth harmonic (v_4) in the
azimuthal distribution of particles at RHIC. The measurement was done taking
advantage of the large elliptic flow generated at RHIC. The integrated v_4 is
about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8)
harmonics upper limits on the magnitudes are reported.Comment: 4 pages, 6 figures, contribution to the Quark Matter 2004 proceeding
All-optical switching and strong coupling using tunable whispering-gallery-mode microresonators
We review our recent work on tunable, ultrahigh quality factor
whispering-gallery-mode bottle microresonators and highlight their applications
in nonlinear optics and in quantum optics experiments. Our resonators combine
ultra-high quality factors of up to Q = 3.6 \times 10^8, a small mode volume,
and near-lossless fiber coupling, with a simple and customizable mode structure
enabling full tunability. We study, theoretically and experimentally, nonlinear
all-optical switching via the Kerr effect when the resonator is operated in an
add-drop configuration. This allows us to optically route a single-wavelength
cw optical signal between two fiber ports with high efficiency. Finally, we
report on progress towards strong coupling of single rubidium atoms to an
ultra-high Q mode of an actively stabilized bottle microresonator.Comment: 20 pages, 24 figures. Accepted for publication in Applied Physics B.
Changes according to referee suggestions: minor corrections to some figures
and captions, clarification of some points in the text, added references,
added new paragraph with results on atom-resonator interactio
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