4,544 research outputs found
Screening-Limited Response of NanoBiosensors
Despite tremendous potential of highly sensitive electronic detection of
bio-molecules by nanoscale biosensors for genomics and proteomic applications,
many aspects of experimentally observed sensor response (S) are unexplained
within consistent theoretical frameworks of kinetic response or electrical
screening. In this paper, we combine analytic solutions of Poisson-Boltzmann
and reaction-diffusion equations to show that the electrical response of
nanobiosensor varies logarithmically with the concentration of target
molecules, time, the salt concentration, and inversely with the fractal
dimension of sensor surface. Our analysis provides a coherent theoretical
interpretation of wide variety of puzzling experimental data that have so far
defied intuitive explanation.Comment: 7 pages, 2 figure
Study of the generator/motor operation of induction machines in a high frequency link space power system
Static power conversion systems have traditionally utilized dc current or voltage source links for converting power from one ac or dc form to another since it readily achieves the temporary energy storage required to decouple the input from the output. Such links, however, result in bulky dc capacitors and/or inductors and lead to relatively high losses in the converters due to stresses on the semiconductor switches. The feasibility of utilizing a high frequency sinusoidal voltage link to accomplish the energy storage and decoupling function is examined. In particular, a type of resonant six pulse bridge interface converter is proposed which utilizes zero voltage switching principles to minimize switching losses and uses an easy to implement technique for pulse density modulation to control the amplitude, frequency, and the waveshape of the synthesized low frequency voltage or current. Adaptation of the proposed topology for power conversion to single-phase ac and dc voltage or current outputs is shown to be straight forward. The feasibility of the proposed power circuit and control technique for both active and passive loads are verified by means of simulation and experiment
Ultrafast photoinduced enhancement of nonlinear optical response in 15-atom gold clusters on indium tin oxide conducting film
We show that the third order optical nonlinearity of 15-atom gold clusters is
significantly enhanced when in contact with indium tin oxide (ITO) conducting
film. Open and close aperture z-scan experiments together with non-degenerate
pump-probe differential transmission experiments were done using 80 fs laser
pulses centered at 395 nm and 790 nm on gold clusters encased inside
cyclodextrin cavities. We show that two photon absorption coefficient is
enhanced by an order of magnitude as compared to that when the clusters are on
pristine glass plate. The enhancement for the nonlinear optical refraction
coefficient is ~3 times. The photo-induced excited state absorption using
pump-probe experiments at pump wavelength of 395 nm and probe at 790 nm also
show an enhancement by an order of magnitude. These results attributed to the
excited state energy transfer in the coupled gold cluster-ITO system are
different from the enhancement seen so far in charge donor-acceptor complexes
and nanoparticle-conjugate polymer composites.Comment: To appear in Optics Express (2013);
http://dx.doi.org/10.1364/OE.21.00848
Quantum Convolutional BCH Codes
Quantum convolutional codes can be used to protect a sequence of qubits of
arbitrary length against decoherence. We introduce two new families of quantum
convolutional codes. Our construction is based on an algebraic method which
allows to construct classical convolutional codes from block codes, in
particular BCH codes. These codes have the property that they contain their
Euclidean, respectively Hermitian, dual codes. Hence, they can be used to
define quantum convolutional codes by the stabilizer code construction. We
compute BCH-like bounds on the free distances which can be controlled as in the
case of block codes, and establish that the codes have non-catastrophic
encoders.Comment: 4 pages, minor changes, accepted for publication at the 10th Canadian
Workshop on Information Theory (CWIT'07
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