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11.
12.
Yttria partially stabilized zirconia (Y-PSZ) and Co1−xO powders in 4:1 molar ratio were sintered and then annealed at 1300 and 1600°C to investigate the orientation change of Co1−xO particles within Y-PSZ grains. Transmission electron microscopic observations indicated the Co1−xO particles remained nonepitaxy in Y-PSZ grains after annealing at 1300°C for 300 h. When fired at 1600°C for 1–100 h, submicro-sized Co1−xO particles (denoted as C) reached parallel epitaxy relationship, i.e. [100]C//[100]Z, [010]C//[010]Z and another relationship, i.e. [111]C//[100]Z,
//[011]Z with respect to the host zirconia grain (denoted as Z) nearly free of tetragonal precipitates. On the other hand, larger intragranular Co1−xO particles (>1 μm in diameter) failed to reach epitaxial orientations even subject to prolonged annealing (100 h) at 1600°C. The temperature and size dependence of orientation change of the intragranular particle is in accordance with theoretical consideration of Brownian type rotation of the particle above a critical temperature for anchorage release at interface. 相似文献
13.
William Rosehart David Westwick Pouyan Jazayeri José Aguado Sebastian Martin 《Electric Power Systems Research》2009
An identification algorithm for a power system load model is proposed in this paper. The overall non-convex identification problem is separated into convex and non-convex subproblems, allowing for a global optimum to be found. 相似文献
14.
Tzu-Jung ChenJer-Han Lu Hui-Di LuI-Lung Liu Pouyan Shen 《Journal of the European Ceramic Society》2012,32(4):795-805
Specific surface area change of ZrO2 (predominant tetragonal - (t) symmetry, 30-50 nm) and less refractory TiO2 anatase nanoparticles (20-50 nm) upon isothermal firing at 700-1000 °C in air was determined by N2 adsorption-desorption hysteresis isotherm. The nanoparticles underwent onset coarsening-coalescence within minutes without appreciable phase transformation for TiO2, but with extensive transformation into monoclinic (m-) symmetry for ZrO2. The apparent activation energy of such a process being not much higher for ZrO2 (77 ± 23 kJ/mol) than TiO2 (56 ± 3 kJ/mol) nanoparticles can be attributed to transformation plasticity. The minimum temperature for coarsening/coalescence of the present ZrO2 and TiO2 nanoparticles was estimated as 710 and 641 °C, respectively. 相似文献
15.
Nanochannel electroporation delivers precise amounts of biomolecules into living cells 总被引:1,自引:0,他引:1
Boukany PE Morss A Liao WC Henslee B Jung H Zhang X Yu B Wang X Wu Y Li L Gao K Hu X Zhao X Hemminger O Lu W Lafyatis GP Lee LJ 《Nature nanotechnology》2011,6(11):747-754
Many transfection techniques can deliver biomolecules into cells, but the dose cannot be controlled precisely. Delivering well-defined amounts of materials into cells is important for various biological studies and therapeutic applications. Here, we show that nanochannel electroporation can deliver precise amounts of a variety of transfection agents into living cells. The device consists of two microchannels connected by a nanochannel. The cell to be transfected is positioned in one microchannel using optical tweezers, and the transfection agent is located in the second microchannel. Delivering a voltage pulse between the microchannels produces an intense electric field over a very small area on the cell membrane, allowing a precise amount of transfection agent to be electrophoretically driven through the nanochannel, the cell membrane and into the cell cytoplasm, without affecting cell viability. Dose control is achieved by adjusting the duration and number of pulses. The nanochannel electroporation device is expected to have high-throughput delivery applications. 相似文献
16.
An onset sintering–coarsening–coalescence-polymerization (SCCP) event of amorphous SiO2 nanoparticles (ca. 40–100 nm in size) by isothermal firing in the 1150–1300 °C range in air was characterized by an N2 adsorption–desorption hysteresis isotherm coupled with X-ray diffraction and vibrational spectroscopy. The apparent activation energy of such a rapid SCCP process was estimated as 177±32 kJ/mol, based on 30% reduction of a specific surface area with an accompanied change of medium range orders, i.e. forming Si2O5 while retaining the Si–2ndO yet losing the Si–2ndSi without appreciable crystallization. The minimum temperature of the SCCP process, as of concern to industrial silica applications and sedimentary/metamorphosed sandstone formation, is 1120 °C based on the extrapolation of steady specific surface area reduction rates to null. 相似文献
17.
Investigation of the nanostructure and mechanical properties of polypropylene/polyamide 6/layered silicate ternary nanocomposites 总被引:1,自引:0,他引:1
This work aims to investigate the structure–property relationship in ternary nanocomposites consisting of polypropylene as the matrix, nanoclay as the reinforcement and polyamide 6 as the intermediate phase. In this regard, composites of polypropylene/organoclay, polyamide/organoclay, blends of polypropylene/polyamide, and ternary nanocomposites of polypropylene/polyamide/layered silicate with and without compatibilizer were produced via melt compounding. Nanostructure was investigated by wide-angle X-ray diffraction and transmission electron microscopy. Scanning electron microscopy was employed to study the microstructure. Modulus of elasticity and yield strength were measured by uniaxial tensile test. Results show that silicate layers can only be observed inside polyamide particles. Moreover, polypropylene was unable to intercalate the grade of organoclay used in this study. While polyamide/organoclay system exhibited an exfoliated structure, the nanostructure of ternary nanocomposites was chiefly intercalated, due to the high concentration of silicate layers inside polyamide particles. Incorporation of organoclay into the polypropylene/polyamide system was seen to have a noticeable effect on the shape and size of polyamide particles. In addition, elastic modulus and yield strength were observed to be directly affected by incorporation of nanoclay and compatibilizer into the polypropylene matrix, respectively. The simultaneous presence of the two constituents in the system resulted in samples with superior mechanical properties in the elastic as well as the plastic deformation regime. 相似文献
18.
The average degree of consolidation of soft rock mass in the immediate vicinity of the base of drilled shaft or plate load tests was evaluated using the Biot Three-Dimensional Consolidation Theory. The compressibility parameters of soft rock mass were estimated using the contact pressure and displacement relationships obtained from the in situ drilled shaft and plate load tests. It was found that typical drilled shaft and plate load tests on soft rocks are drained to partially drained, with the average degree of consolidation dependent on the rock type and weathering condition, foundation diameter, and the loading stage. It was also determined that drained behavior is observed under service conditions due to the low compressibility of soft rocks in the early stages of loading. 相似文献
19.
A new magnetic cellulose hybrids anchored with quaternary amine moieties were fabricated and used in recovering Pt(IV) ions from acidic solutions. Kinetic and thermodynamic parameters of adsorption process were reported through using batch experiments. An equilibrium uptake capacity of 178 mg g?1 was achieved within 55 min. The adsorption process was found to follow the pseudo-second-order kinetics and fitted well Langmuir and D-R adsorption isotherms revealing monolayer surface coverage and physisorption mechanism, respectively. At low pH values and high chloride concentration ranges, ion exchange was proposed as the predominant mechanism for the adsorption of Pt(IV) ions on the sorbent. The obtained sorbent showed good durability, easy separation, and regeneration from the adsorption medium. 相似文献
20.
The change of specific surface area and pore size distribution coupled with N2 adsorption–desorption hysteresis isotherm, in particular that typical to cylindrical pores, were used to determine the onset coarsening/coalescence in the temperature range of 500–800 °C for Co(OH)2 derived Co3O4 nanoplates and 700–1000 °C for CoO-derived Co3O4 powders (backtransformed to CoO above 900 °C) which are equi-axed in shape and microns in size. The vigorous onset coarsening/coalescence of the nanoplates and equi-axed micron particles was found to occur within minutes having apparent activation energy of 37 ± 7 kJ/mol (based on t0.7, i.e. time for 70% surface area reduction) and 113 ± 8 kJ/mol (based on t0.3), respectively. The surface area reduction process of the nanoplates was found to be controlled by (1 1 1)-specific coalescence besides a coarsening–repacking process more common to the equi-axed particles. The present static experimental results of coarsening–coalescence of the Co3O4 (below 900 °C) or CoO particles (above 900 °C) supports our previous supposition that CoO and Co3O4 nanocondensates could readily assemble as nanochain aggregates and further coalesce into a close packed manner below 1000 °C by the radiant heating effect in a dynamic laser ablation process. 相似文献