Aluminum has been successfully incorporated within the frameworks of periodic mesoporous organosilicas (Al-PMO) by co-condensation of bis(triethoxysilyl)ethane and dibutoxyaluminotriethoxysilane. The Al-PMO materials ...
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Periodic mesoporous organosilicas (PMO) functionalized with sulfonic acid group have been successfully synthesized by co-condensation of bis(triethoxysily)ethane and 3- mercaptopropyltrimethoxysilane in the presence o...
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An on-chip spectrophotometer system, consisting of a CMOS focal-plane-array and polydimethylsiloxane (PDMS) microfluidic flow channels, is described. One of the potential applications of this prototype system is to pe...
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An on-chip spectrophotometer system, consisting of a CMOS focal-plane-array and polydimethylsiloxane (PDMS) microfluidic flow channels, is described. One of the potential applications of this prototype system is to perform the enzymatic analysis of glucose, cholesterol or uric acid contained in blood.
We study the self-organization of bidisperse mixtures of hard spheres in two dimensions by simulating random sequential adsorption (RSA) of tethered hard disks that undergo limited Monte Carlo surface diffusion. The t...
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We study the self-organization of bidisperse mixtures of hard spheres in two dimensions by simulating random sequential adsorption (RSA) of tethered hard disks that undergo limited Monte Carlo surface diffusion. The tethers place a control on the local entropy of the disks by constraining their movement within a specified distance from their original adsorption positions. By tuning the tether length, from zero (the pure RSA process) to infinity (near-equilibrium conditions), the kinetic pathway to monolayer formation can be varied. Previously [J. J. Gray et al., Phys. Rev. Lett. 85, 4430 (2000); Langmuir 17, 2317 (2001)], we generated nonequilibrium phase diagrams for size-monodisperse and size-polydisperse hard disks as a function of surface coverage, size distribution, and tether length to reveal the occurrence of hexagonal close-packed, hexatic, and disordered phases. Bidisperse hard disks potentially offer increasingly diverse phase diagrams, with the possible occurrence of spatially and compositionally organized superlattices. Geometric packing calculations anticipate the formation of close-packed lattices in two dimensions for particle size ratios σ=RS/RL=0.53, 0.414, and 0.155. The simulations of these systems presented here, however, reveal that RSA kinetics frustrate superlattice ordering, even for infinite tethers. The calculated jamming limits fall well below the minimum surface coverages necessary for stable ordering, as determined by melting simulations.
The microstructure of epitaxial InAs thin films grown by MOCVD on mask-patterned "LEO" (lateral epitaxial overgrowth) GaAs and on unpatterned GaAs substrates was studied using double-crystal x-ray diffractio...
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The microstructure of epitaxial InAs thin films grown by MOCVD on mask-patterned "LEO" (lateral epitaxial overgrowth) GaAs and on unpatterned GaAs substrates was studied using double-crystal x-ray diffraction, scanning electron microscopy and cross-sectional transmission electron microscopy. This paper describes the improvement in crystal quality (factor of 20 reduction in x-ray rocking curve width), the order of magnitude reduction in dislocation density, and the rearrangement of the remaining extended defects that were observed in the LEO material when compared to the film grown on the unpatterned wafer.
It is believed that azobenzene amphiphiles tend to be strongly H-aggregated during pure Langmuir-Blodgett (LB) film manipulation and therefore they are unable to photoisomerize. However, we present in this article the...
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