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排序方式: 共有160条查询结果,搜索用时 437 毫秒
1.
Genki Saito Yuji Kunisada Takumi Watanabe Xuemei Yi Takahiro Nomura Norihito Sakaguchi Tomohiro Akiyama 《Journal of the American Ceramic Society》2019,102(1):524-532
Carbon-and-oxygen-doped AlN specimens were prepared by combustion synthesis using Al, graphite, and AlN. Graphite addition changed the product color from white to blue. By XRD, the lattice constant increased slightly with increasing carbon content. Blue AlN powder was synthesized with a molar ratio of the diluent AlN of 0.2-0.5 with a fixed graphite content of 0.05. At an AlN molar ratio exceeding 0.6, carbon was not successfully incorporated due to the lower reaction temperature. Calcination at 800°C in air removed residual graphite without changing the crystal structure or product color. Oxygen, nitrogen, and carbon analyses revealed that blue AlN powders contained 0.45-0.54 mass% carbon and 1.4-1.6 mass% oxygen, while the undoped AlN contained 0.021 mass% carbon and 0.94 mass% oxygen. The origin of the white-to-blue color change was investigated via reflection measurements. Blue AlN exhibits an absorption peak at 634 nm (1.96 eV). From first-principles electronic structure calculations, the C-doped AlN and carbon-and-oxygen-doped AlN with a 1:1 ratio could be classified as p-type, whereas the O-doped AlN and 1:3 carbon-and-oxygen-doped AlN were n-type. One reason for the absorption peak at 634 nm may be a transition from the conduction band to an upper unoccupied state. These results suggest the possible control of optical and electronic properties of AlN via carbon-and-oxygen doping. 相似文献
2.
Gasification of polyethylene (PE) pellet was studied using atmospheric argon-steam plasma generated by microwave discharge and the feasibility of the process was examined. The experimental results showed that additional steam to argon plasma promoted the weight decrease of PE and enhanced the production of H2, CO, CO2 and CH4. The results confirmed that the treatment of plastics with the steam plasma was effective to obtain synthesis gas. 相似文献
3.
The kinetic parameters of the first stage of polystyrene degradation have been investigated to elucidate the reaction mechanisms using the flow reactor system. The decrease in molecular weight of polystyrene was recorded at minute intervals over the temperature range 310°–390°C. Generally, the first and second stages were observed by thermogravimetric analysis (t.g.a.), however in the early stage of the degradation volatile yields of at least 5% occurred. Therefore, using t.g.a. analysis it is difficult to detect this earlier stage. It became evident that the first stage in the earlier part of the reaction could be detected by g.p.c. analysis. We have observed the hidden kinetic parameters of the nature of the first stage of the polystyrene degradation. The results indicate that the main chains were degraded randomly with the small quantitative volatile groups in the first stage and the rates of decrease in molecular weight in the first stage against reaction temperatures were evaluated as log ks = 12.0 ? 41300/RT. 相似文献
4.
Taichi Sato 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1976,26(4):207-213
The thermal decomposition of uranium peroxide hydrates, UO4·4H2O and UO4·2H2O, has been investigated by thermal analyses, X-ray diffraction study and infrared spectroscopy. As a result, it is concluded that the thermal decomposition of uranium peroxide hydrates proceeds in the following sequence: where 3 ≤ x ≤ 3.5. 相似文献
5.
Hiroaki Sakamoto Rie Futamura Ikuya Fujiwara Taichi Meboso Ning Li Eiichiro Takamura Takenori Satomura Shin-ichiro Suye 《应用聚合物科学杂志》2021,138(37):50937
Biofuel cells (BFCs) that produce electrical energy from organic resources through enzymatic reactions have been attracting significant attention. Owing to the high electrical conductivity of carbon nanotubes (CNTs), their modification on the electrode surface of a BFC is expected to increase the current, and their high specific surface area may be useful in increasing the power output. Previously, we constructed a biocathode by immobilizing multicopper oxidase from Pyrobaculum aerophilum (McoP) with a carbon nanotube binding peptide (CBP) sequence on the CNTs. This resulted in higher current densities than when using enzymes without CBP sequences. However, owing to the randomly stacked CNTs on the surface of the electrodes, their conductive properties were impaired and performance as biocathodes was poor. Herein, we constructed a biocathode in which single-walled CNTs (SWCNTs) were oriented one-dimensionally and McoP is immobilized on the surface of an SWNCT via CBP. The current density was successfully increased by two-fold by orienting the CNTs and orienting and immobilizing McoP on their surfaces. This technology provides insights into the development of biodevices with controlled orientation of both the SWCNTs and enzymes immobilized on their surfaces. 相似文献
6.
固态直线变压器驱动源(LTD)是新型的脉冲功率电路方法之一.其工作原理基于大量功率半导体器件的同步控制,因此它在电路结构和工作特性方面与传统的脉冲功率电源有很大不同.在此通过实验,首先验证了LTD的基本工作原理,进而试制了一台采用650个功率MOSFET的LTD系统.实验结果分别给出了超过20 kV的最高输出电压和超过3.2 kA的最高输出电流,上升时间(10%~90%)小于20 ns.在此基础上还采用少量的模块验证了双极性LTD的可行性.实验结果同时也显示了开关的导通电阻对LTD输出参数的影响和由此带来的技术问题. 相似文献
7.
Artificial Life and Robotics - We propose a class of generalized multiplicative stochastic processes obtained by introducing an endo-perspective into one-dimensional maps with additive noise. We... 相似文献
8.
Computational Visual Media - The exact shape of intracranial aneurysms is critical in medical diagnosis and surgical planning. While voxel-based deep learning frameworks have been proposed for this... 相似文献
9.
Phase Relations and Volume Changes of Hafnia under High Pressure and High Temperature 总被引:1,自引:0,他引:1
Osamu Ohtaka Hiroshi Fukui Taichi Kunisada Tomoyuki Fujisawa Kenichi Funakoshi Wataru Utsumi Tetsuo Irifune Koji Kuroda Takumi Kikegawa 《Journal of the American Ceramic Society》2001,84(6):1369-1373
Using multi-anvil high-pressure devices and synchrotron radiation, X-ray in situ observations of HfO2 under high pressure and high temperature have been performed to investigate its phase relations and compression behavior. An orthorhombic phase (orthoI) is stable from 4 to 14.5 GPa below 1250°–1400°C and transforms to a tetragonal phase, which is one of the high-temperature forms of HfO2 , above these temperatures. Another orthorhombic phase (orthoII) with a cotunnite-type structure appears above 14.5 GPa. OrthoII is stable up to 1800°C at 21 GPa. OrthoII is quenchable to ambient conditions. The orthoI-to-orthoII transition is accompanied by ∼8 vol% decrease. The bulk moduli of orthoI and orthoII at room temperature are 220 and 312 GPa, respectively. This low compressibility of orthoII indicates that it is a potential candidate for very hard materials. 相似文献
10.
Numerical prediction of fraction of eutectic phase in Sn−Ag−Cu soldring using the phase-field method
Machiko Ode Minoru Ueshima Taichi Abe Hideyuki Murakami Hidehiro Onodera 《Journal of Electronic Materials》2006,35(11):1969-1974
A combination of macroscale solidification simulation and phase-field calculation is employed to predict the volume fraction
of the eutectic phase in Sn-4.0 mass% Ag-XCu solder alloys (X=0.5–1.1 mass%). The solidification simulation incorporates the
cooling rate in the phase-field simulation. We assume the residual liquid solidifies as eutectic phase when the driving force
for the nucleation of Cu6Sn5 amounts to a critical value, which is determined based on the experimental data. Though the calculation results depend on
the experimental data, the obtained fractions are about 40% for 0.5 mass% Cu and more than 90% for 1.1 mass% Cu alloy, which
shows good agreement with the experimental data. 相似文献