The electrostatic self-assembly of polymer on proton exchange membrane was studied by calorimetric tech-nique. The titration of poly diallyldimethylammonium chloride (PDDA) into Nation membrane was designed and perfor...
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The electrostatic self-assembly of polymer on proton exchange membrane was studied by calorimetric tech-nique. The titration of poly diallyldimethylammonium chloride (PDDA) into Nation membrane was designed and performed to determine the thermodynamic parameters. The enthalpy change △rH(○)m and binding constant K in the process of self-assembly were obtained from data analysis with the help of Origin. According to the calculated thermodynamic parameters, the electrostatic self-assembly of PDDA on the proton exchange membrane is an 'en-thalpy-driven' reaction. The released heat indicates decrease of energy, which is helpful for the occurrence of the self-assembly process, and the degree of disorder is reduced, which went against the adsorption process. As to everyion bond, the value of △rH(○)m of DDA is beyond PDDA because a small molecule can bind itself to the membranewithout steric hindrance.
To reuse roller waste as a raw material of high performance green ceramic balls,three kinds of white alumina ceramic balls whose wear resistance were 2-3 times of the best high alumina ceramic ball with90% Al2O3 were ...
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To reuse roller waste as a raw material of high performance green ceramic balls,three kinds of white alumina ceramic balls whose wear resistance were 2-3 times of the best high alumina ceramic ball with90% Al2O3 were prepared,and the Al2O3 content of the prepared balls was 75%.It is found that the effect of calcia and magnesia on the wear resistance of ceramic balls is contrast to the accepted one: the wear rate of the ceramic balls prepared in CaO-Al2O3-SiO2 system is the lowest and the wear rate of the ceramic balls prepared in MgO-Al2O3-SiO2 is the *** main crystal phase of the ceramic ball is mullite and *** ceramic ball granular is uniform and fine with 4-5 um average *** pore diameter is about 2 *** wear way of the ceramic balls is mainly transcrystalline fracture.
This paper discusses the present status of, and future perspectives on nano Traditional Chinese medicine (TCM) by describing the concept, its methodologies, preservation, drug effect and pharmacological study. The exp...
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Magnetization measurements on a single crystal of the high-Tc cuprate HgBa2CuO4 (Hg-1201) are performed for the two field orientations B||c and B||(a,b). Besides zero-field-cooling (zfc) – field-cooling (fc) and magn...
Magnetization measurements on a single crystal of the high-Tc cuprate HgBa2CuO4 (Hg-1201) are performed for the two field orientations B||c and B||(a,b). Besides zero-field-cooling (zfc) – field-cooling (fc) and magnetization studies, the flux creep relaxation is determined. The zfc curves exhibit pronounced step-like anomalies in the mixed state above the lower critical field Bc1. They are interpreted as those points in the phase diagram where the penetrating flux fronts meet at the center of the sample. In order to obtain more information about the flux pinning mechanism flux creep relaxation experiments are performed at different temperatures in magnetic fields of 0.15 and 2 T. The resulting supercurrent dependence on the mean activation energy is analysed according to the collective pinning theory which predicts U ∝ ((j/jc)−μ −1). The μ-values for B||c are 0.5 at higher temperatures and 2 at 5 K, and they vary between 1.1 and 1.5 for B||(a,b). The observed behaviour is quite different from that found for powder samples.
The transition-metal carbide cemented by metal has excellent combined properties. In this study, cermets were prepared by vacuum sintering from carbide-metal composite powders. The transition- metal oxides (Cr 2O3, Mo...
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The transition-metal carbide cemented by metal has excellent combined properties. In this study, cermets were prepared by vacuum sintering from carbide-metal composite powders. The transition- metal oxides (Cr 2O3, MoO3, V2O5, Nb 2O5 and TiO2), cementing-metal oxides (Co 3O4 and NiO), and carbon black were used as raw materials to pre-synthesize composite powders such as Cr3C2-Co, Mo2C-Co, VC-Co, NbC-Co and TiC-Ni, by a direct reduction and carburization process in vacuum. Results show that the participation of Co 3O4 and NiO as well as the vacuum circumstance were greatly propitious to the carburization of transition-metal oxides into carbides. The carbothermal condition was greatly improved by the direct reduction and carburization process.
A series of samples of hexagonal boron nitride-aluminum nitride (10-90, 15-85, 20-80, 25-75, 30-70wt.%) ceramic composites were prepared by spark plasma sintering in a nitrogen atmosphere at 1650°C-1800°C fo...
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A series of samples of hexagonal boron nitride-aluminum nitride (10-90, 15-85, 20-80, 25-75, 30-70wt.%) ceramic composites were prepared by spark plasma sintering in a nitrogen atmosphere at 1650°C-1800°C for 5min. Different amounts of CaF2 were added as sintering aids. The effects of CaF2 and sintering temperature on densification and dielectric properties were discussed. The addition of CaF2 enhances relative dielectric constant and loss tangent of the samples. The increase in sintering temperature promotes the densification and decreases the dielectric loss tangent. When being sintered at 1700°C, the relative density, dielectric constant and dielectric loss tangent of the sample with 15wt.%BN are 98.04%, 7.15 and 6.31×10-4 respectively.
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