Reverse engineering past craft technologies involves using the basics of materialsscience and engineering to a new end: their preservation and continuation. Examples are presented of the glazed tile technologies of S...
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The tribological performance of MoS2-Cr films in a pin-on-disk test sliding against an aluminum ball has been examined in this study. The MoS2-Cr films were deposited by pulsed laser deposition (MoS 2) and simultaneou...
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Controlled defects were created on DNA linked 2D colloidal photonic crystals using a Nd:YAG pulsed laser. The 2D photonic crystals were self-assembled using 1.8 μm polystyrene (PS) microspheres on functionalized glas...
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Gold colloid possessing both lipase and PEG tethered chains on the surface was prepared by the adsorption of lipase, followed by the immobilization of the PEG/polycation block copolymer on the colloid surface. The obt...
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Gold colloid possessing both lipase and PEG tethered chains on the surface was prepared by the adsorption of lipase, followed by the immobilization of the PEG/polycation block copolymer on the colloid surface. The obtained colloid showed a high dispersion stability at a high salt concentration. The enzymatic activity of the lipase on the colloid complex retained intact. Surprisingly, more than 95% of the initial enzymatic activity was retained after repeated thermal treatments (5 times) at 58°C for 10 min. The PEG condensed layer between the immobilized enzyme on the gold colloid may prevent the denaturation of the enzyme at high temperature.
Directional solidification studies have been conducted using Pb-Bi peritectic alloys over a wide range of compositions, temperature gradients, and growth velocities to characterize the primary α- to primary β-phase ...
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Directional solidification studies have been conducted using Pb-Bi peritectic alloys over a wide range of compositions, temperature gradients, and growth velocities to characterize the primary α- to primary β-phase transitions, which have been observed at both very low and very high velocities. The critical conditions for these transitions correspond to the simultaneous growth of the α and β phases at or close to a single isotherm. The low velocity transition occurs under very specific conditions of composition, temperature gradient, and growth velocity. Since the transition conditions are composition dependent, they change continuously under terrestrial conditions where rejected solute is convectively mixed into the liquid. Detailed experimental studies have been carried out to examine the phase selection in the immediate vicinity of the critical velocity for the α to β transition, and the effect of convection on this transition is examined experimentally in the Pb-Bi system. The dynamic condition, at which both phases are present at the same isotherm, was shown to depend not only on velocities, temperature gradients, and bulk (nominal) alloy compositions, but also on the volume fractions of solid. A quantitative expression for the α- to β-phase transition condition was obtained by using the boundary layer model of fluid flow, which showed good agreement with the experimental results. It is shown that the transition occurs at the volume fraction where the bulk composition reaches the critical composition value predicted by the diffusive model. The modification in the microstructure map for the trailing planar or nonplanar β phase is discussed.
AlMgB14 based composites have many potential applications in industry, but better understanding of the mechanisms responsible for high hardness and wear resistance is required for the implementation of this technology...
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ISBN:
(纸本)0976205726
AlMgB14 based composites have many potential applications in industry, but better understanding of the mechanisms responsible for high hardness and wear resistance is required for the implementation of this technology. This study was performed to determine if the results of electron probe microanalysis (EPMA) could be correlated with the observed variations in local hardness and toughness. The relationship between microstructure and hardness in AlMgB14 was investigated to improve the processing of this ultra-hard ceramic and its related composites. High-energy milling and subsequent hot-pressing of the powders produced dense composites with high hardness, but inconsistencies in powder processing and microstructure have led to variations in hardness. The morphology of the microstructure and distribution of O and Fe containing impurities were compared to the local hardness.
Composite membranes of sulfonated crosslinked polystyrene particles have been made by aligning the particles under an electric field in a crosslinked poly(dimethyl siloxane) matrix following a procedure described by O...
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Composite membranes of sulfonated crosslinked polystyrene particles have been made by aligning the particles under an electric field in a crosslinked poly(dimethyl siloxane) matrix following a procedure described by Oren et al. (2004). The purpose of this work, however, was to investigate the effects of electric field amplitude and frequency on alignment behavior. As expected, the particles aligned only by application of a certain minimum electric field for a given frequency. Impedance measurements indicated that the unaligned membranes showed capacitive behavior up to 8 wt % particles, which transformed to conductive behavior on alignment.
Heteroepitaxial growth of SiGe on thin Si membranes leads to the sharing of the epitaxial strain between the Si template layer and the deposited thin film. At high Ge concentrations, at which Ge forms dislocation-free...
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Heteroepitaxial growth of SiGe on thin Si membranes leads to the sharing of the epitaxial strain between the Si template layer and the deposited thin film. At high Ge concentrations, at which Ge forms dislocation-free hut nanostructures, there can be significant bending underneath self-assembled Ge huts. We have fabricated undercut mesas to approximate a freestanding Si membrane and produced Ge hut structures using molecular beam epitaxy. Using synchrotron x-ray microdiffraction to probe the strain and bending of the template layer directly, we compare strain sharing in conventional blanket film structures with the strain induced by Ge hut structures.
Electrostatic force microscopy (EFM) was used to measure the extent of dielectric damage from plasma processing of nanoporous, low k methyl silsesqioxane (MSQ) interconnect structures with approximately 50 run spatial...
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