Ceramic porous structures are specially indicated for filters for molten metals, hot gases, thermal protection systems and heat exchangers, due their high permeability, good retention capacity, low density and high th...
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ISBN:
(纸本)9788880800842
Ceramic porous structures are specially indicated for filters for molten metals, hot gases, thermal protection systems and heat exchangers, due their high permeability, good retention capacity, low density and high thermal insulation. This work describes the research carried out on mechanical properties of two different types of a commercial porous ceramic material (10 and 40 ppi). The ceramic material was characterized in terms of microstructural aspects, crystalline phases, density, porosity, strength and thermal shock behaviour. The results have indicated that the strength of the material remain practically constant, regardless of the temperature. The fracture analyses indicated that the fracture is normally caused by the presence of microcracks and also by the presence of a large amount of pores in the ceramic filaments.
The reduction of Cu2O islands on Cu(100) surfaces under vacuum annealing leads to the formation of surface craters on the substrate surface surrounding the reducing oxide islands. These craters exhibit growth instabil...
The reduction of Cu2O islands on Cu(100) surfaces under vacuum annealing leads to the formation of surface craters on the substrate surface surrounding the reducing oxide islands. These craters exhibit growth instability characterized by increased slope of both the inner and outer facets of the crater rims. We suggest that the crater formation and the growth instability are related to the homoepitaxial growth of Cu adatoms dislodged from the reducing Cu2O islands. Incorporation of such atomic processes in kinetic Monte Carlo simulations reproduces the morphological features of the experimentally observed craters.
This study presents a novel process to batch-fabricated carbon nanotube devices on flexible substrate. In short, the pre-made carbon nanotube (CNT) arrays on Si-wafer are firstly blended with polymer and are then tran...
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This study presents a novel process to batch-fabricated carbon nanotube devices on flexible substrate. In short, the pre-made carbon nanotube (CNT) arrays on Si-wafer are firstly blended with polymer and are then transferred onto a polymer film using chemical-vapor-deposition (CVD) of parylene. This yields CNT arrays on flexible substrates. Electrical measurements reveal that nanotube arrays behave as ohmic conductors and their current-voltage profile is linear. Nanotubes embedded in polymer are then exposed by O 2 plasma etching and field emission measurements indicate that exposed nanotube arrays exhibit a low threshold field emission at 0.58 V/mum and field enhancement factor appears to be 5500. Thus, the present devices offer a novel route to flexible FED applcation.
Compositional lipid domains (“lipid rafts”) in plasma membranes are believed to be important components of many cellular processes. The mechanisms by which cells regulate the sizes and lifetimes of these spatially e...
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Compositional lipid domains (“lipid rafts”) in plasma membranes are believed to be important components of many cellular processes. The mechanisms by which cells regulate the sizes and lifetimes of these spatially extended domains are poorly understood at the moment. Here we show that the competition between phase separation in an immiscible lipid system and active cellular lipid transport processes naturally leads to the formation of such domains. Furthermore, we demonstrate that local interactions with immobile membrane proteins can spatially localize the rafts and lead to further clustering.
In this work we demonstrate that a compositionally stratified Ba 1-x Sr x TiO 3 (BST) thin film design (BST60/40-BST75/25-BST90/10) combined with optimized metal-organic solution deposition (MOSD) film fabrication an...
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In this work we demonstrate that a compositionally stratified Ba 1-x Sr x TiO 3 (BST) thin film design (BST60/40-BST75/25-BST90/10) combined with optimized metal-organic solution deposition (MOSD) film fabrication and post-deposition annealing process protocols results in low loss, highly tunable and temperature stable thin film heterostructures. The experimental data demonstrates that the compositionally stratified BST thin film heterostructure has a small-signal dielectric permittivity of 360 with a dissipation factor of 0.012 and a dielectric tunability of 65% at 444 kV/cm. These material properties exhibited minimal dispersion as a function of temperature ranging from 90 to -10 °C. Thus, our results suggest that this compositionally stratified material design is an excellent candidate for tunable devices which require both enhanced dielectric response and performance consistency in harsh operational temperature regimes.
Magnetic and magnetocaloric properties of polycrystalline (Er1−xGdx)5Si4 with x=0.1 and 0.25 have been studied. The temperature dependencies of the dc magnetization and ac susceptibility indicate two magnetic transiti...
Magnetic and magnetocaloric properties of polycrystalline (Er1−xGdx)5Si4 with x=0.1 and 0.25 have been studied. The temperature dependencies of the dc magnetization and ac susceptibility indicate two magnetic transitions: the high temperature transitions are antiferromagnetic in character, whereas the low temperature ones are of ferromagnetic nature. The isothermal magnetization of these compounds shows metamagneticlike transitions at 5K and no saturation in fields up to 70kOe. Time dependencies of the magnetization data below the Néel temperature exhibit unusually strong relaxation effects with logarithmic time dependence. The ac susceptibility data reveal that magnetic state of these compounds is distinctly different from spin glasses and the relaxation behavior seen in the magnetization data is a consequence of complex magnetic interactions. The existence of complex magnetic interactions leads to an easy formation of field induced short range ferromagnetic correlations in the paramagnetic state and greatly affects both the magnetic and magnetocaloric properties of these compounds.
It was hypothesized that the hydroxyapatite(HAP)/GEMOSIL biomaterial could promote osteoblast (MC3T3) self-organization. This study using MC3T3 cell line demonstrated formation of trabecular bone-like extracellular ma...
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ISBN:
(纸本)9781615670802
It was hypothesized that the hydroxyapatite(HAP)/GEMOSIL biomaterial could promote osteoblast (MC3T3) self-organization. This study using MC3T3 cell line demonstrated formation of trabecular bone-like extracellular matrix (ECM) on the material compared to unorganized ECM on the control (no-material). The study also initiated exploratory tests for the underlying mechanisms via gene analysis and proliferation assay.
A spotting technique using the magnetorheological finishing (MRF) process s applied to measurements of drag force for optical glasses. In situ measurement results are reported as a function of substrate surface roughn...
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BiFeO3 and PbTiO3 were introduced to a Sc-modified Pb(Fe2/3W1/3)O3 compound with strong cation order to improve the multiferroic properties. It is found that the degree of cation order decreases as the amount of BiFeO...
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BiFeO3 and PbTiO3 were introduced to a Sc-modified Pb(Fe2/3W1/3)O3 compound with strong cation order to improve the multiferroic properties. It is found that the degree of cation order decreases as the amount of BiFeO3 or PbTiO3 increases. As a result, the saturation magnetization deteriorates. Solid solutions with BiFeO3 show an increase in both ferroelectric and magnetic transition temperatures. However, the ferroelectric remanent polarization is dramatically suppressed. In contrast, solid solution with PbTiO3 leads to an increase in the ferroelectric transition temperature, a decrease in the magnetic transition temperature, and a significant enhancement of remanent polarization.
The hardnesses of secondary cell wall laminae (SCWL) and compound corner middle lamellae (CCML) in wood were measured at indentation strain rates between approximately 7X10-4 s-1 and 20 s-1, using a new method called ...
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