719 research outputs found
Reduction of the contact resistance by doping in pentacene few monolayers thin film transistors and self-assembled nanocrystals
The authors study the contact resistance of gold-pentacene interface by applying the transmission-line method to a few monolayers thick pentacene films in thin film transistor geometry. It was found that tetrafluorotetracyanoquinodimethane (F(4)TCNQ) doping reduces the contact resistance by more than a factor of 20. In addition, a significant improvement of the conductance of pentacene nanocrystals self-assembled on 10 nm gap Au nanojunction devices by F(4)TCNQ doping is observed. The result demonstrates the importance of doping on the performance of organic electronic devices from 10 nm scale up to 100 mu m scale. (C) 2007 American Institute of Physics
Temperature dependent charge-injection at the metal-organic semiconductor interface and density of states in pristine and doped pentacene
The authors study temperature dependent electrical transport in pristine and tetrafluorotetracyanoquinodimethane (F(4)TCNQ)-doped pentacene to explore the physical mechanism of the doping-induced reduction in the contact resistance at the metal-organic semiconductor interface. It was found that the F(4)TCNQ-doping induces an apparent lowering of the hole injection barrier at gold-pentacene interfaces. In addition, characteristic changes in the density of states (DOS) induced by the F(4)TCNQ-doping in a thin-film transistor geometry have been observed. The correlation between the doping-induced DOS and the carrier injection process is discussed
Generating a Schr\"odinger-cat-like state via a coherent superposition of photonic operations
We propose an optical scheme to generate a superposition of coherent states
with enhanced size adopting an interferometric setting at the single-photon
level currently available in the laboratory. Our scheme employs a nondegenerate
optical parametric amplifier together with two beam splitters so that the
detection of single photons at the output conditionally implements the desired
superposition of second-order photonic operations. We analyze our proposed
scheme by considering realistic on-off photodetectors with nonideal efficiency
in heralding the success of conditional events. A high-quality performance of
our scheme is demonstrated in view of various criteria such as quantum
fidelity, mean output energy, and measure of quantum interference
Contribution of L-type Ca2+ channels to early afterdepolarizations induced by I-Kr and I-Ks channel suppression in guinea pig ventricular myocytes
ArticleJOURNAL OF MEMBRANE BIOLOGY. 222(3): 151-166(2008)journal articl
Total Angular Momentum Conservation During Tunnelling through Semiconductor Barriers
We have investigated the electrical transport through strained
p-Si/Si_{1-x}Ge_x double-barrier resonant tunnelling diodes. The confinement
shift for diodes with different well width, the shift due to a central
potential spike in a well, and magnetotunnelling spectroscopy demonstrate that
the first two resonances are due to tunnelling through heavy hole levels,
whereas there is no sign of tunnelling through the first light hole state. This
demonstrates for the first time the conservation of the total angular momentum
in valence band resonant tunnelling. It is also shown that conduction through
light hole states is possible in many structures due to tunnelling of carriers
from bulk emitter states.Comment: 4 pages, 4 figure
Empirical comparison of high gradient achievement for different metals in DC and pulsed mode
For the SwissFEL project, an advanced high gradient low emittance gun is
under development. Reliable operation with an electric field, preferably above
125 MV/m at a 4 mm gap, in the presence of an UV laser beam, has to be achieved
in a diode configuration in order to minimize the emittance dilution due to
space charge effects. In the first phase, a DC breakdown test stand was used to
test different metals with different preparation methods at voltages up to 100
kV. In addition high gradient stability tests were also carried out over
several days in order to prove reliable spark-free operation with a minimum
dark current. In the second phase, electrodes with selected materials were
installed in the 250 ns FWHM, 500 kV electron gun and tested for high gradient
breakdown and for quantum efficiency using an ultra-violet laser.Comment: 25 pages, 13 figures, 5 tables. Follow up from FEL 2008 conference
(Geyongju Korea 2008) New Title in JVST A (2010) : Vacuum breakdown limit and
quantum efficiency obtained for various technical metals using DC and pulsed
voltage source
Einstein-Podolsky-Rosen-like correlation on a coherent-state basis and inseparability of two-mode Gaussian states
The strange property of the Einstein-Podolsky-Rosen (EPR) correlation between
two remote physical systems is a primitive object on the study of quantum
entanglement. In order to understand the entanglement in canonical
continuous-variable systems, a pair of the EPR-like uncertainties is an
essential tool. Here, we consider a normalized pair of the EPR-like
uncertainties and introduce a state-overlap to a classically correlated mixture
of coherent states. The separable condition associated with this state-overlap
determines the strength of the EPR-like correlation on a coherent-state basis
in order that the state is entangled. We show that the coherent-state-based
condition is capable of detecting the class of two-mode Gaussian entangled
states. We also present an experimental measurement scheme for estimation of
the state-overlap by a heterodyne measurement and a photon detection with a
feedforward operation.Comment: 9 pages, 5 figures. A part of the materials in Sec. VI B of previous
versions was moved into another paper: Journal of Atomic, Molecular, and
Optical Physics, 2012, 854693 (2012).
http://www.hindawi.com/journals/jamop/2012/854693
Administration route-dependent vaccine efficiency of murine dendritic cells pulsed with antigens
Dendritic cells (DCs) loaded with tumour antigens have been successfully used to induce protective tumour immunity in murine models and human trials. However, it is still unclear which DC administration route elicits a superior therapeutic effect. Herein, we investigated the vaccine efficiency of DC2.4 cells, a murine dendritic cell line, pulsed with ovalbumin (OVA) in the murine E.G7-OVA tumour model after immunization via various routes. After a single vaccination using 1 × 106OVA-pulsed DC2.4 cells, tumour was completely rejected in the intradermally (i.d.; three of four mice), subcutaneously (s.c.; three of four mice), and intraperitoneally (i.p.; one of four mice) immunized groups. Double vaccinations enhanced the anti-tumour effect in all groups except the intravenous (i.v.) group, which failed to achieve complete rejection. The anti-tumour efficacy of each immunization route was correlated with the OVA-specific cytotoxic T lymphocyte (CTL) activity evaluated on day 7 post-vaccination. Furthermore, the accumulation of DC2.4 cells in the regional lymph nodes was detected only in the i.d.-and s.c.-injected groups. These results demonstrate that the administration route of antigen-loaded DCs affects the migration of DCs to lymphoid tissues and the magnitude of antigen-specific CTL response. Furthermore, the immunization route affects vaccine efficiency. © 2001 Cancer Research Campaign http://www.bjcancer.co
Density of States of Disordered Two-Dimensional Crystals with Half-Filled Band
A diagrammatic method is applied to study the effects of commensurability in
two-dimensional disordered crystalline metals by using the particle-hole
symmetry with respect to the nesting vector P_0={\pm{\pi}/a, {\pi}/a} for a
half-filled electronic band. The density of electronic states (DoS) is shown to
have nontrivial quantum corrections due to both nesting and elastic impurity
scattering processes, as a result the van Hove singularity is preserved in the
center of the band. However, the energy dependence of the DoS is strongly
changed. A small offset from the middle of the band gives rise to disappearence
of quantum corrections to the DoS .Comment: to be published in Physical Review Letter
- …