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排序方式: 共有1270条查询结果,搜索用时 15 毫秒
51.
ZnO nanoparticles doped with up to 5 at% of Co and Mn were prepared using a co-precipitation method. The location of dopant
ions and the effect of doping on the photocatalytic activity were investigated. The crystal structure of nanoparticles and
local atomic arrangements around dopant ions were analyzed by X-ray absorption spectroscopy. The results showed that the Co
ions substituted the Zn ions in the ZnO wurtzite phase structure and induced lattice shrinkage, while Mn ions were not completely
incorporated in the crystal lattice. The photocatalytic activity under simulated sunlight was characterized by the decomposition
of Rhodamine B dye molecules. It was revealed that Co-doping strongly reduced the photocatalytic activity but Mn-doping showed
a weaker effect on the reduction of the photoactivity. 相似文献
52.
Hyun Soon Park Yasukazu Murakami Keiichi Yanagisawa Tsuyoshi Matsuda Ryosuke Kainuma Daisuke Shindo Akira Tonomura 《Advanced functional materials》2012,22(16):3434-3437
Peculiar magnetic domain walls produced in Heusler alloys, which have attracted renewed interest due to their potential application to actuators and spintronic devices, are studied here using electron holography. The observations reveal unexpectedly narrow magnetic domain walls, the width of which showed perfect agreement with that of the antiphase boundaries (APB, e.g., only 3 nm). While the results can be explained by the significant depression of ferromagnetism due to the local chemical disorder, the electron phase shift indicates that ferromagnetic correlation still remains in the APB region. 相似文献
53.
Daisuke Kawashima Yutaka Asako 《International Journal of Heat and Mass Transfer》2012,55(9-10):2244-2248
This paper focuses on temperature rise due to the viscous dissipation in liquids flowing through micro-channels. In the past, equations for the prediction of the temperature rise have been obtained as a function of the friction factor, Reynolds number and Eckert number or a similar form, starting from Navier–Stokes equation and energy equation under the assumption of fully developed laminar flow by researchers. The temperature rises calculated from the equations have been compared with experimental data and the equations have been validated. However, in this paper, a new equation for the prediction of the temperature rise is simply obtained from the first law of thermodynamics without restriction of fully developed laminar flow. 相似文献
54.
Daisuke Yamamoto Takeshi Ozaki Carlos A. R. Sá de Melo Ippei Danshita 《Journal of Low Temperature Physics》2014,175(1-2):258-264
We study a first-order phase transition between superfluid and Mott insulator phases in binary Bose mixtures loaded into a hypercubic optical lattice. The system is described by a two-component Bose-Hubbard model. Considering the difference between the two kinds of bosons in the intra-component interaction strength, we discuss the metastability of the system and the hysteresis associated with the first-order superfluid-Mott insulator transition. It is found that the sweeping of hopping amplitude induces a conventional hysteresis-loop behavior. We also find an anomalous hysteresis behavior when the chemical potential is varied. In the anomalous hysteresis, the phase transition occurs in a unidirectional way and a hysteresis loop does not form. 相似文献
55.
56.
Simulated annealing (SA) is an optimization technique that can process cost functions with degrees of nonlinearities, discontinuities and stochasticity. It can process arbitrary boundary conditions and constraints imposed on these cost functions. The SA technique is applied to the problem of robot path planning. Three situations are considered here: the path is represented as a polyline; as a Bézier curve; and as a spline interpolated curve. In the proposed SA algorithm, the sensitivity of each continuous parameter is evaluated at each iteration increasing the number of accepted solutions. The sensitivity of each parameter is associated to its probability distribution in the definition of the next candidate. 相似文献
57.
Discovery of a Novel Scaffold as an Indoleamine 2,3‐Dioxygenase 1 (IDO1) Inhibitor Based on the Pyrrolopiperazinone Alkaloid,Longamide B
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Zenyu Shiokawa Emi Kashiwabara Daisuke Yoshidome Prof. Dr. Koichi Fukase Dr. Shinsuke Inuki Prof. Dr. Yukari Fujimoto 《ChemMedChem》2016,11(24):2682-2689
Indoleamine 2,3‐dioxygenase 1 (IDO1) has emerged as a key target for cancer therapy, as IDO1 plays a critical role in the capacity of tumor cells to evade the immune system. The pyrrolopiperazinone alkaloid longamide B and its derivatives were identified as novel IDO1 inhibitors based on docking studies and small library synthesis. The thioamide derivative showed higher IDO1 inhibitory activity than longamide B, and displayed an activity similar to that of a representative IDO1 inhibitor, 1‐methyl‐tryptophan. These results suggest that the pyrrolopiperazinone scaffold of longamide B could be used in the development of IDO1 inhibitors. 相似文献
58.
Ari Hamdani Tomonori Ihara Nobuyoshi Tsuzuki Hiroshige Kikura 《Journal of Mechanical Science and Technology》2016,30(9):3897-3905
Two-phase air-water bubbly swirling flow through a pipe is a complex turbulent flow and its prediction is still challenging. The present paper describes the experimental investigation of the air-water bubbly swirling flow in vertical co-current flow. Swirling flow is induced by a twisted tape in a 20 mm inner diameter pipe. The flow is investigated using Ultrasonic velocity profiler (UVP), which allows the measurement of liquid and gas velocities simultaneously. Furthermore, simultaneous measurement of void fraction is performed using Wire mesh sensor (WMS). The experimental results reveal that swirling flow has significant impact on bubbles’ distribution. In low liquid flow rate, the average bubble velocity is fairly uniform along the radial position and void fraction increases in the near wall region. However, increasing liquid flow rate at constant gas flow rate leads to increase in void fraction in the core region, this is mainly due to drift velocity which is affected by centrifugal force. Experimental findings and parametric trends based on the effects of swirling flow are summarized and discussed. 相似文献
59.
Tsukaho Yahagi Daisuke Kawai Takuma Takahashi Motoyuki Iijima Junichi Tatami 《Journal of the American Ceramic Society》2022,105(3):2046-2057
Si3N4 ceramics with excellent mechanical properties are used for heat dissipation substrates and so on. In order to improve their reliability and expand their application fields, it is desirable to understand and control the electrical properties of Si3N4 ceramics. In this study, the electrical resistivity of Si3N4 ceramics with Yb2O3 additive was investigated by applying various voltages at temperatures ranging from 25°C to 300°C. When Yb2O3 was added as a sintering aid to Si3N4 ceramics, a crystalline J-phase (Yb4Si2O7N2) was formed and their electrical resistivity was significantly lower than that of Y2O3 additive. The electrical resistivity of the Yb2O3-added ceramics decreased with an increase in temperature and applied voltage. Yb existed in multiple valence states, Yb2+ and Yb3+, in the Si3N4 ceramics and the decrease in the electrical resistivity can be attributed hopping conduction through the J-phase. The J-phase in the Si3N4 ceramics was observed to be continuous, and percolation analysis suggested that the J-phase formed an infinite cluster. Therefore, the decrease in the electrical resistivity of the Yb2O3-added Si3N4 ceramics was found mainly to result from the formation of an infinite cluster of J-phase, which exhibits hopping conduction. 相似文献
60.
Highly monodisperse polystyrene nanoparticles with mean diameters of less than 100 nm are synthesized via aqueous emulsion polymerization using an amphoteric initiator (VA-057) in the presence of sub-millimolar concentrations of anionic surfactant. Since the net charge on the initiator is almost zero at neutral pH, the resultant latex particle size is mainly determined by surfactant adsorption. Polymerizations were performed in the presence of a range of anionic surfactants with differing critical micelle concentrations (CMC) by varying the concentrations of surfactant, initiator and monomer, and also the ionic strength. Sodium dodecyl benzene sulfonate (SDBS), sodium hexadecyl sulfate (SHS), and sodium octadecyl sulfate (SOS) have relatively low CMCs and so enable formation of highly monodisperse nanoparticles at relatively low (sub-millimolar) surfactant concentrations, CS (i.e. below the CMC in each case). Empirically, it was found that the particle number, Np, and coefficient of variation of the particle size, CV, were strongly dependent on the CS/CMC ratio: Np increased almost in proportion with the square of this ratio, while the CV exhibited a minimum at approximately CS/CMC = 0.20. Higher ionic strength reduced the particle size, which is consistent with the above relationship because the addition of salt lowers the CMCs of ionic surfactants. Polymer latex particles produced using such formulations form highly regular, close-packed colloidal arrays. 相似文献