作者：
Park, WounjhangDepartment of Electrical
Computer and Energy Engineering Materials Science and Engineering Program University of Colorado BoulderCO80309-0425 United States
We report the latest progress on plasmonic nanostructures for organic photovoltaic devices. Specifically, three aspects will be discussed: plasmon-exciton interaction, combined optical and electrical modeling and plas...
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Spin systems with frustration and disorder are notoriously difficult to study, both analytically and numerically. While the simulation of ferromagnetic statistical mechanical models benefits greatly from cluster algor...
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Spin systems with frustration and disorder are notoriously difficult to study, both analytically and numerically. While the simulation of ferromagnetic statistical mechanical models benefits greatly from cluster algorithms, these accelerated dynamics methods remain elusive for generic spin-glass-like systems. Here, we present a cluster algorithm for Ising spin glasses that works in any space dimension and speeds up thermalization by at least one order of magnitude at temperatures where thermalization is typically difficult. Our isoenergetic cluster moves are based on the Houdayer cluster algorithm for two-dimensional spin glasses and lead to a speedup over conventional state-of-the-art methods that increases with the system size. We illustrate the benefits of the isoenergetic cluster moves in two and three space dimensions, as well as the nonplanar chimera topology found in the D-Wave Inc. quantum annealing machine.
Surface patterning is very useful in biomaterial studies, yet it is not easy to prepare a micropattern with cell-adhesion contrast that is stable in a wet environment. Recently, a platform technique of transfer photol...
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Surface patterning is very useful in biomaterial studies, yet it is not easy to prepare a micropattern with cell-adhesion contrast that is stable in a wet environment. Recently, a platform technique of transfer photolithography was invented to fabricate stable metal microarrays on the surface of a cell-adhesion resistant and mechanically biomimetic poly（ethylene glycol） hydrogel; the linker is the key chemical in such a transfer strategy. This article reports the design and synthesis of a hetero-bifunctional macromonomer linker with a thiol group at one end and an acryloyl group at the other end. The bifunctional linker was char- acterized by GPC and ~H NMR, and the average number of thiol groups in the bifunctional linker was detected by Ellman＇s reagent. The regent stability under wet conditions was also confirmed by the model reactants. The resultant micropatterned surfaces are meaningful for future studies of cell behaviors on mechanically biomimetic matrixes.
Reinforced concrete structures such as bridges, roadways, buildings and dams can suffer serious degradation in harsh environments such as seawater, salt-laden air, and environments where deicing salts are used. Chlori...
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In this paper, the results of a study on microstructural influences on cyclic strain response, deformation and fracture behavior of an alloy steel is presented Cyclic strain resistance exhibited a linear trend for the...
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ISBN:
(纸本)9781119041481
In this paper, the results of a study on microstructural influences on cyclic strain response, deformation and fracture behavior of an alloy steel is presented Cyclic strain resistance exhibited a linear trend for the variation of both elastic strain amplitude with reversals-to-failure, and plastic strain amplitude with reversals-to-failure. Fracture morphology was observed to be the same at the macroscopic level over the entire range of cyclic strain amplitudes examined. However, at the fine microscopic level this alloy steel revealed fracture to be mixed-mode with features reminiscent of "locally" ductile and brittle failure mechanisms. The mechanisms governing strain response at the fine microscopic level, resultant fatigue life, and final fracture behavior are presented and discussed in light of the mutually interactive influences of intrinsic microstructural effects, deformation characteristics of the microstructural constituents during fully-reversed strain cycling, magnitude of cyclic strain amplitude, and resultant fatigue life.
Gradient sequence copolymers exhibit a gradual change in comonomer composition along the polymer chain. These novel materials are interesting because they exhibit unique properties compared to their random, alternatin...
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We describe formation of defect-colloidal superstructures induced by microspheres with normal surface anchoring dispersed in chiral nematic liquid crystals in confinement-unwound homeotropic cells. Using three-dimensi...
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We describe formation of defect-colloidal superstructures induced by microspheres with normal surface anchoring dispersed in chiral nematic liquid crystals in confinement-unwound homeotropic cells. Using three-dimensional nonlinear optical imaging of the director field, we demonstrate that some of the induced defects have nonsingular solitonic nature while others are singular point and line topological defects. The common director structures induced by individual microspheres have dipolar symmetry. These topological dipoles are formed by the particle and a hyperbolic point defect (or small disclination loop) of elementary hedgehog charge opposite to that of a sphere with perpendicular boundary conditions, which in cells with thickness over equilibrium cholesteric pitch ratio approaching unity are additionally interspaced by a looped double-twist cylinder of continuous director deformations. The long-range elastic interactions are probed by holographic optical tweezers and videomicroscopy, providing insights to the physical underpinnings behind self-assembled colloidal structures entangled by twisted solitons. Computer-simulated field and defect configurations induced by the colloidal particles and their assemblies, which are obtained by numerically minimizing the Landau–de Gennes free energy, are in agreement with the experimental findings.
A resonance Raman study of graphene samples with different C13 isotopic concentrations and using different laser excitation energies is presented. The main Raman peaks (D, G, G*, and 2D) of graphene were measured and ...
A resonance Raman study of graphene samples with different C13 isotopic concentrations and using different laser excitation energies is presented. The main Raman peaks (D, G, G*, and 2D) of graphene were measured and the dependence of their frequencies on the isotope atomic mass follows a simple harmonic oscillator relation. The G* and 2D double-resonance peak positions were measured as a function of the laser energy, and we observed that the slopes of the laser energy dependence are the same independently of isotope concentration. This result shows that isotopic substitution does not alter the electron and phonon dispersions near the K point of the graphene Brillouin zone. From the linewidth of G and 2D Raman peaks, we have also obtained a dependence of the phonon lifetime on the C13 isotope concentration.
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