14,688 research outputs found
Formation of rectifier with gold nanoclusters
Gold nanoclusters encapsulated with organic molecules are of great interest
for its possible applications in the fields of molecular electronics, catalysis
and medical science. Here we demonstrate that monolayer and bilayer films of
thiol-capped gold nanoclusters can exhibit diode-like properties provided
controlled spatial asymmetry exist between two tunnel junctions used to connect
a thiol capped gold nanoclusters. Current-voltage characteristics of this
rectifier were obtained from conducting probe atomic force microscopy
measurements and also from conventional two probe resistance measurements.
Systematic x-ray reflectivity and atomic force microscopy measurements were
carried out to characterize the spatial asymmetry introduced by a monolayer of
fatty acid salt gadolinium stearate used to deposit thiol-capped gold
nanocluster molecules on hydrophilic SiO2-Si(001) substrate by Langmuir
Blodgett technique. This information was used to explain prominent
rectification observed in these nano-structured films.Comment: 13 pages, 3 figure
Amorphization of Vortex Matter and Reentrant Peak Effect in YBaCuO
The peak effect (PE) has been observed in a twinned crystal of
YBaCuO for Hc in the low field range, close to
the zero field superconducting transition temperature (T(0)) . A sharp
depinning transition succeeds the peak temperature T of the PE. The PE
phenomenon broadens and its internal structure smoothens out as the field is
increased or decreased beyond the interval between 250 Oe and 1000 Oe.
Moreover, the PE could not be observed above 10 kOe and below 20 Oe. The locus
of the T(H) values shows a reentrant characteristic with a nose like
feature located at T(H)/T(0)0.99 and H100 Oe (where
the FLL constant apenetration depth ). The upper part of
the PE curve (0.5 kOeH10 kOe) can be fitted to a melting scenario with
the Lindemann number c0.25. The vortex phase diagram near T(0)
determined from the characteristic features of the PE in
YBaCuO(Hc) bears close resemblance to that in
the 2H-NbSe system, in which a reentrant PE had been observed earlier.Comment: 15 pages and 7 figure
QPO Evolution in 2005 Outburst of the Galactic Nano Quasar GRO J1655-40
GRO J1655-40 showed significant X-ray activity in the last week of February,
2005 and remained active for the next 260 days. The rising and the decline
phases of this particular outburst show evidence for systematic movements of
the Comptonizing region, assumed to be a CENBOL, which causes the
Quasi-periodic Oscillations or QPOs. We present both the spectral and the
timing results of the RXTE/PCA data taken from these two hard spectral states.
Assuming that the QPOs originate from an oscillating shock CENBOL, we show how
the shock slowly moves in through the accretion flow during the rising phase at
a constant velocity and accelerate away outward during the later part of the
decline phase. By fitting the observed frequencies with our solution, we
extract time variation of various disk parameters such as the shock locations,
velocity etc.Comment: 5 Pages, 2 Figures, Proceeding of the 2nd Kolkata Conference on
"Observational Evidence for the Black Holes in the Universe", Published in
AIP, 200
Phase transitions in LuIrSi
We report the results of our investigations on a polycrystalline sample of
LuIrSi which crystallizes in the UCoSi type structure
(Ibam). These investigations comprise powder X-ray diffraction, magnetic
susceptibility, electrical resistivity and high temperature (120-300 K) heat
capacity studies. Our results reveal that the sample undergoes a
superconducting transition below 3.5 K. It also undergoes a first order phase
transition between 150-250 K as revealed by an upturn in the resistivity, a
diasmagnetic drop in the magnetic susceptibility and a large anomaly (20-30
J/mol K) in the specific heat data. We observe a huge thermal hysteresis of
almost 45 K between the cooling and warming data across this high temperature
transition in all our measurements. Low temperature X-ray diffraction
measurements at 87 K reveals that the compound undergoes a structural change at
the high temperature transition. Resistivity data taken in repeated cooling and
warming cycles indicate that at the high temperature transition, the system
goes into a highly metastable state and successive heating/cooling curves are
found to lie above the previous one and the resistance keeps increasing with
every thermal cycle. The room temperature resistance of a thermaly cycled piece
of the sample decays exponentialy with time with a decay time constant
estimated to be about 10 secs. The anomaly (upturn) in the resistivity and
the large drop (almost 45%) in the susceptibility across the high temperature
transition suggest that the observed structural change is accompanied or
induced by an electronic transition.Comment: 7 figures, 1 table and 18 reference
Feasibility of a Carbon Consumption Tax for Sustainable Development β a Case Study of India
Global climate change is a major issue confronting policymakers worldwide, and there is widespread scientific acceptance of the reality of climate change and its adverse consequences In terms of economic analysis, greenhouse gas emissions (GHG), which cause planetary climate changes, represent both an environmental externality and the overuse of a common property resource. The paper is premised around the hypothesis that tax policy can be used to address climate concerns by making less Green House Gas intensive purchases and investments more financially attractive. However, in the absence of an International framework capping GHG emissions, countries adopting mitigation policies incur costs that would not exist under global cooperation such as the loss of competitiveness and emissions leakage. A consumption tax based on the carbon footprint of a product levied on all products at the point of purchase by the final end-user, regardless of where the goods are produced using a Credit-method would be capable of addressing these concerns of emissions leakage and loss of competitiveness, while being WTO compliant. The author intends to test the feasibility and effectiveness of such a carbon consumption tax in the Indian Context. The author shall test the feasibility of levy of such a consumption tax in the context of India and evaluate the effectiveness in mitigating climate change and catering to the goal of sustainable development
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