13,171 research outputs found
Method of using photovoltaic cell using poly-N-vinylcarbazole complex Patent
Method of producing output voltage from photovoltaic cell using poly-N-vinyl carbazole complexed with iodin
Static electricity of polymers reduced by treatment with iodine
Treating organic polymers with iodine improves the electrical conductivity. Diffusion enables products of desired properties to be custom formulated. This eliminates a buildup of static electricity and the need for fillers or bound metal salts
Quantum cost for sending entanglement
Establishing quantum entanglement between two distant parties is an essential
step of many protocols in quantum information processing. One possibility for
providing long-distance entanglement is to create an entangled composite state
within a lab and then physically send one subsystem to a distant lab. However,
is this the "cheapest" way? Here, we investigate the minimal "cost" that is
necessary for establishing a certain amount of entanglement between two distant
parties. We prove that this cost is intrinsically quantum, and is specified by
quantum correlations. Our results provide an optimal protocol for entanglement
distribution and show that quantum correlations are the essential resource for
this task.Comment: Added a reference to the related article arXiv:1203.1268 by T. K.
Chuan et a
Pattern Selection in the Complex Ginzburg-Landau Equation with Multi-Resonant Forcing
We study the excitation of spatial patterns by resonant, multi-frequency
forcing in systems undergoing a Hopf bifurcation to spatially homogeneous
oscillations. Using weakly nonlinear analysis we show that for small amplitudes
only stripe or hexagon patterns are linearly stable, whereas square patterns
and patterns involving more than three modes are unstable. In the case of
hexagon patterns up- and down-hexagons can be simultaneously stable. The
third-order, weakly nonlinear analysis predicts stable square patterns and
super-hexagons for larger amplitudes. Direct simulations show, however, that in
this regime the third-order weakly nonlinear analysis is insufficient, and
these patterns are, in fact unstable
Exploiting the synergy between carboplatin and ABT-737 in the treatment of ovarian carcinomas
Platinum drug-resistance in ovarian cancers is a major factor contributing to chemotherapeutic resistance of recurrent disease. Members of the Bcl-2 family such as the anti-apoptotic protein Bcl-XL have been shown to play a role in this resistance. Consequently, concurrent inhibition of Bcl-XL in combination with standard chemotherapy may improve treatment outcomes for ovarian cancer patients. Here, we develop a mathematical model to investigate the potential of combination therapy with ABT-737, a small molecule inhibitor of Bcl-XL, and carboplatin, a platinum-based drug, on a simulated tumor xenograft. The model is calibrated against in vivo\ud
experimental data, wherein tumor xenografts were established in mice and treated with ABT-737 and carboplatin on a fixed periodic schedule, alone or in combination, and tumor sizes recorded regularly. We show that the validated model can be used to predict the minimum drug load that will achieve a predetermined level of tumor growth inhibition, thereby maximizing the synergy between the two drugs. Our simulations suggest that the time of infusion of each carboplatin dose is a critical parameter, with an 8-hour infusion of carboplatin administered each week combined with a daily bolus dose of ABT-737 predicted to minimize residual disease. We also investigate the potential of ABT-737 co-therapy with carboplatin to prevent or delay the onset of carboplatin-resistance under two scenarios. When resistance is acquired as a result of aberrant DNA-damage repair in cells treated with carboplatin, the model is used to identify drug delivery schedules that induce tumor remission with even low doses of combination therapy. When resistance is intrinsic, due to a pre-existing cohort of resistant cells, tumor remission is no longer feasible, but our model can be used to identify dosing strategies that extend disease-free survival periods. These results underscore the potential of our model to accelerate the development of novel therapeutics such as ABT-737, by predicting optimal treatment strategies when these drugs are given in combination with currently approved cancer medications
Three water sites in upper mantle olivine and the role of titanium in the water weakening mechanism
Infrared spectroscopy on synthetic olivines has established that there are at least
four different mechanisms by which hydrogen is incorporated into the crystal structure.
Two mechanisms occur in the system MgO-SiO2-H2O associated with silicon and
magnesium vacancies, respectively. A third mechanism is associated with trivalent cation
substitution, commonly Fe3+ in natural olivine, while the fourth mechanism, which is
the one most prevalent in natural olivines from the spinel-peridotite facies of the Earth’s
upper mantle, is associated with Ti4+ [Berry et al., 2005]. Here first principles calculations
based on density functional theory are used to derive the structure and relative energies
of the two defects in the pure MgO-SiO2-H2O system, and possible hydrogen-bearing
and hydrogen-free point defects in Ti4+-doped forsterite. Calculated structures are used to
compare the predicted orientation of the O-H bonds with the experimentally determined
polarization. The energies are used to discuss how different regimes of chemical
environment, temperature (T), pressure (P), and both water content and water fugacity
( fH2O), impact on which of the different hydroxyl substitution mechanisms are
thermodynamically stable. We find that given the presence of Ti impurities, the most
stable mechanism involves the formation of silicon vacancies containing two protons
charge balanced by a Ti4+ cation occupying an adjacent octahedral site. This mechanism
leads to the water-mediated formation of silicon vacancies. As silicon is known to be the
most slowly diffusing species in olivine, this provides a credible explanation of the
observed water weakening effect in olivine
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