The local grain boundary curvature in a model Ni-based superalloy was measured experimentally using Dehoff s tangent count method. The results show that the curvature parameter, K, which relates the grain size to the ...
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ISBN:
(纸本)9780873396868
The local grain boundary curvature in a model Ni-based superalloy was measured experimentally using Dehoff s tangent count method. The results show that the curvature parameter, K, which relates the grain size to the mean boundary curvature, varies both with the volume fraction of the second-phase particles and the holding time during high-temperature annealing. The values of K obtained from the specimens with high particle volume fractions (up to 24% by volume) are much lower than those reported previously for pure or dilute alloy systems. In addition, K decreases gradually as a result of Zener's pinning when grain growth stagnates. Since the local boundary curvature constitutes the driving force for grain growth, these observations could help to explain grain growth phenomena in heavily pinned systems.
According to the new method of preparing core-shell nanospheres developed by our group,by using two monomers,2-hydroxypropyl methacrylate(HPMA) and vinyl acetate(VAc),two kinds of core-shell nanospheres with poly(ε-c...
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According to the new method of preparing core-shell nanospheres developed by our group,by using two monomers,2-hydroxypropyl methacrylate(HPMA) and vinyl acetate(VAc),two kinds of core-shell nanospheres with poly(ε-caprolactone) (PCL) as the core and crosslinked poly(2-hydroxypropyl methacrylate) (PHPMA) or poly(vinyl acetate) (PVAc) as the shell were successfully prepared under similar *** degrading the PCL cores of the two kinds of nanospheres by lipase,the corresponding crosslinked poly(methyl acrylic acid) hollow spheres and crosslinked poly(vinyl alcohol) hollow spheres were *** indicate that the new method we proposed for preparing core-shell polymeric nanospheres via in-situ polymerization can be generalized to a certain extent,and it is suitable for many systems provided the monomer used is soluble in water,while its corresponding polymer is insoluble in water.
Recently, Supercritical fluids have been used in material synthesis and processing because of their special properties such as high diffusivity, low viscosity, and low surface tension. Supercritical carbon dioxide is ...
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ISBN:
(纸本)1420061836
Recently, Supercritical fluids have been used in material synthesis and processing because of their special properties such as high diffusivity, low viscosity, and low surface tension. Supercritical carbon dioxide is the most attractive because it is non-toxic, non-flammable, and has moderate critical temperature and critical pressure. Moreover, and can also swell most polymers. In this study, we prepared the polymer/clay nanocomposites using supercritical fluids. Cloisites 10A,15A,25A,30B used in this study are natural montmorillonites modified with a quaternary ammonium salt. The nanocomposites of polymer/clay were characterized by XRD,TGA and DSC.
A new bioimmobilization technology was developed using nanometer-sized, glass nanobottles made by using polymer nanostructures as template, to capture and contain biomolecules in their free state on surfaces. The poly...
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ISBN:
(纸本)1420061828
A new bioimmobilization technology was developed using nanometer-sized, glass nanobottles made by using polymer nanostructures as template, to capture and contain biomolecules in their free state on surfaces. The polymer nanostructures were formed by film symmetry break-up during microwave irradiation under liquid environment.
Poly (sodium 4-styrenesulfonate) (PSS) was grafted onto carbon black surface by ambient surface-initiated atom radical transfer polymerization. And the sensors of screen printed carbon electrode based on CB-g-PSS immo...
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In attempts to develop new process modifiers for thermoplastics, two ionic liquids with long chain hydrophobic cations and different anions were introduced in a biodegradable polymer. Methods of incorporation included...
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In attempts to develop new process modifiers for thermoplastics, two ionic liquids with long chain hydrophobic cations and different anions were introduced in a biodegradable polymer. Methods of incorporation included melt blending, solvent casting and microencapsulation from w/o/w systems at concentrations up to 10 wt%. The modified polymers were characterized Theologically and by TGA to determine process and thermal stability, respectively, and by DSC to determine miscibility and types of the polymer-ionic liquid interactions. Potential applications in plasticization, lubrication and emulsification are discussed for selected polymer-ionic liquid combinations.
The wetting behavior of poly(dimethylsiloxane) (PDMS) ionomers on a silica surface was investigated. Spin-cast films of Li-salts of a carboxylated PDMS (Li-CPDMS) on silica resisted dewetting even after annealing at 1...
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The wetting behavior of poly(dimethylsiloxane) (PDMS) ionomers on a silica surface was investigated. Spin-cast films of Li-salts of a carboxylated PDMS (Li-CPDMS) on silica resisted dewetting even after annealing at 120°C for 144 h, while the unmodified PDMS did not even form a homogeneous film.
The effects of various processing parameters of electro spinning such as concentration, applied voltage, distance from needle to collector on the morphology(especially fiber diameter) of nanofiber matrix was investiga...
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The effects of various processing parameters of electro spinning such as concentration, applied voltage, distance from needle to collector on the morphology(especially fiber diameter) of nanofiber matrix was investigated in this study. We found out the concentration of polymer solution was the key parameter to control the fiber diameter. Such a difference on surface morphology of electro spun nanofiber matrix under various processing parameters will show the different behaviors on protein adsorption on the surface contacting with body fluid. Consequently, this results different cell motions on the matrix used on tissue engineering. To evaluate the adsorption of proteins on the surface of sheet type nanofiber matrix, matrix obtained by electro spinning were immersed in FITC labeled proteins solutions. And then, we confirmed adsorption of proteins using laser scanning confocal microscopy (LSCM). The quantitative analysis of adsorbed proteins was also investigated by UV spectroscopy.
In this study, the flow injection analysis was applied to the enzyme-entrapped electrode on a chip for sensing glucose. The on-chip microelectrode was fabricated by the standard photolithography in clean-room environm...
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ISBN:
(纸本)1420061836
In this study, the flow injection analysis was applied to the enzyme-entrapped electrode on a chip for sensing glucose. The on-chip microelectrode was fabricated by the standard photolithography in clean-room environment and the microfluidic channel height of 100 μm on the chip was formed by poly(dimethylsiloxane). The conducting polymer, poly(3,4- ethylenedioxythiophene), PEDOT, was electropolymerized to entrap enzyme by cyclic voltammetry. At 10 ml/hr, the enzyme electrode was set at 0.7 V (vs. Ag) and sensing of H2O2 was done by injecting various concentrations of glucose (Glu) samples. The linear relationship between the sensing current and the glucose concentration, ranging from 0.1 to 20 mM, was obtained with a sensitivity of 8 nA mm-2 mM-1. Besides, the response time and the recovery time were about 30 and 230 s, respectively. For a single-potential test, both 0.08 mM AA and a blend of 0.08 mM AA plus 10 mM Glu samples reached 31.3 % and 145.5 % of the current for 10 mM Glu, respectively. In contrast, the current for the blend sample reached 99.6 % that of 10 mM Glu in a bi-potential test.
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