18,556 research outputs found
In situ photogalvanic acceleration of optofluidic kinetics: a new paradigm for advanced photocatalytic technologies
A multiscale-designed optofluidic reactor is demonstrated in this work, featuring an overall reaction rate constant of 1.32 s¯¹ for photocatalytic decolourization of methylene blue, which is an order of magnitude higher as compared to literature records. A novel performance-enhancement mechanism of microscale in situ photogalvanic acceleration was found to be the main reason for the superior optofluidic performance in the photocatalytic degradation of dyes as a model reaction
Specific heat across the superconducting dome in the cuprates
The specific heat of the superconducting cuprates is calculated over the
entire phase diagram. A d-wave BCS approach based on the large Fermi surface of
Fermi liquid and band structure theory provides a good description of the
overdoped region. At underdoping it is essential to include the emergence of a
second energy scale, the pseudogap and its associated Gutzwiller factor, which
accounts for a reduction in the coherent piece of the electronic Green's
function due to increased correlations as the Mott insulating state is
approached. In agreement with experiment, we find that the slope of the linear
in T dependence of the low temperature specific heat rapidly increases above
optimum doping while it is nearly constant below optimum. Our theoretical
calculations also agree with recent data on BiSrLaCuO for which the normal state is accessed through the
application of a large magnetic field. A quantum critical point is located at a
doping slightly below optimum.Comment: submitted to PRB; 8 pages, 5 figure
A high specific capacity membraneless aluminum-air cell operated with an inorganic/organic hybrid electrolyte
Aluminum-air cells have attracted a lot of interests because they have the highest volumetric capacity density in theory among the different metal-air systems. To overcome the self-discharge issue of aluminum, a microfluidic aluminum-air cell working with KOH methanol-based anolyte was developed in this work. A specific capacity up to 2507 mAh g¯¹ (that is, 84.1% of the theoretical value) was achieved experimentally. The KOH concentration and water content in the methanol-based anolyte were found to have direct influence on the cell performance. A possible mechanism of the aluminum reactions in KOH methanol-based electrolyte was proposed to explain the observed phenomenon
Signatures of Fermi surface reconstruction in Raman spectra of underdoped cuprates
We have calculated the Raman B and B spectra as a function of
temperature, as well as doping, for the underdoped cuprates, using a model
based on the resonating valence-bond spin-liquid. We discuss changes in
intensity and peak position brought about by the presence of a pseudogap and
the implied Fermi surface reconstruction, which are elements of this model.
Signatures of Fermi surface reconstruction are evident as a sharp rise in the
doping dependence of the antinodal to nodal peak ratio which occurs below the
quantum critical point. The temperature dependence of the B polarization
can be used to determine if the superconducting gap is limited to the Fermi
pocket, as seen in angle resolved photoemission spectroscopy, or extends
beyond. We find that the slope of the linear low energy B spectrum
maintains its usual d-wave form, but with an effective gap which reflects the
gap amplitude projected on the Fermi pocket. Our calculations capture the main
qualitative features revealed in the extensive data set available on the
HgBaCuO (Hg-1201) cuprate.Comment: 13 pages, 14 figure
Microwave conductivity in the ferropnictides with specific application to BaKFeAs
We calculate the microwave conductivity of a two band superconductor with
gap symmetry. Inelastic scattering is included approximately in a BCS
model augmented by a temperature dependent quasiparticle scattering rate
assumed, however, to be frequency independent. The possibility that the s-wave
gap on one or the other of the electron or hole pockets is anisotropic is
explored including cases with and without gap nodes on the Fermi surface. A
comparison of our BCS results with those obtained in the Two Fluid Model (TFM)
is provided as well as with the case of the cuprates where the gap has d-wave
symmetry and with experimental results in BaKFeAs. The
presently available microwave conductivity data in this material provides
strong evidence for large anisotropies in the electron pocket s-wave gap. While
a best fit favors a gap with nodes on the Fermi surface this disagrees with
some but not all penetration depth measurements which would favor a node-less
gap as do also thermal conductivity and nuclear magnetic resonance data.Comment: 12 pages, 9 figures. Phys. Rev. B (submitted
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Unbearable wearables
As wearable devices play an increasing role in the management of health and disease, adverse skin reactions to wearables have become more common. However, the management of allergic contact dermatitis is challenging and new treatment options more compatible with wearable devices are needed. In a 40-year-old woman with contact dermatitis to a continuous glucose monitoring device, topical clobetasol propionate 0.05% spray proved to be an effective treatment that was compatible with the application of adhesive wearables. This case demonstrates that spray formulations of topical steroids are a good option for the treatment of dermatitis under wearable devices such as continuous glucose monitors or ostomy appliance
Self-normalized processes: exponential inequalities, moment bounds and iterated logarithm laws
Self-normalized processes arise naturally in statistical applications.
Being unit free, they are not affected by scale changes. Moreover,
self-normalization often eliminates or weakens moment assumptions. In this
paper we present several exponential and moment inequalities, particularly
those related to laws of the iterated logarithm, for self-normalized random
variables including martingales. Tail probability bounds are also derived. For
random variables B_t>0 and A_t, let Y_t(\lambda)=\exp{\lambda A_t-\lambda
^2B_t^2/2}. We develop inequalities for the moments of A_t/B_{t} or sup_{t\geq
0}A_t/{B_t(\log \log B_{t})^{1/2}} and variants thereof, when EY_t(\lambda
)\leq 1 or when Y_t(\lambda) is a supermartingale, for all \lambda belonging to
some interval. Our results are valid for a wide class of random processes
including continuous martingales with A_t=M_t and B_t=\sqrt _t, and sums of
conditionally symmetric variables d_i with A_t=\sum_{i=1}^td_i and
B_t=\sqrt\sum_{i=1}^td_i^2. A sharp maximal inequality for conditionally
symmetric random variables and for continuous local martingales with values in
R^m, m\ge 1, is also established. Another development in this paper is a
bounded law of the iterated logarithm for general adapted sequences that are
centered at certain truncated conditional expectations and self-normalized by
the square root of the sum of squares. The key ingredient in this development
is a new exponential supermartingale involving \sum_{i=1}^td_i and
\sum_{i=1}^td_i^2.Comment: Published by the Institute of Mathematical Statistics
(http://www.imstat.org) in the Annals of Probability
(http://www.imstat.org/aop/) at http://dx.doi.org/10.1214/00911790400000039
Quantum shape effects on Zeeman splittings in semiconductor nanostructures
We develop a general method to calculate Zeeman splittings of electrons and
holes in semiconductor nanostructures within the tight-binding framework. The
calculation is carried out in the electron-hole picture and is extensible to
the excitonic calculation by including the electron-hole Coulomb interaction.
The method is suitable for the investigation of quantum shape effects and the
anisotropy of the g-factors. Numerical results for CdSe and CdTe nanostructures
are presented
On the capacities of bipartite Hamiltonians and unitary gates
We consider interactions as bidirectional channels. We investigate the
capacities for interaction Hamiltonians and nonlocal unitary gates to generate
entanglement and transmit classical information. We give analytic expressions
for the entanglement generating capacity and entanglement-assisted one-way
classical communication capacity of interactions, and show that these
quantities are additive, so that the asymptotic capacities equal the
corresponding 1-shot capacities. We give general bounds on other capacities,
discuss some examples, and conclude with some open questions.Comment: V3: extensively rewritten. V4: a mistaken reference to a conjecture
by Kraus and Cirac [quant-ph/0011050] removed and a mistake in the order of
authors in Ref. [53] correcte
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