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排序方式: 共有1216条查询结果,搜索用时 15 毫秒
981.
Kaveh Delfanazari Hidehiro Asai Manabu Tsujimoto Takanari Kashiwagi Takeo Kitamura Kazuya Ishida Chiharu Watanabe Shunsuke Sekimoto Takashi Yamamoto Hidetoshi Minami Masashi Tachiki Richard A. Klemm Toshiaki Hattori Kazuo Kadowaki 《Journal of Infrared, Millimeter and Terahertz Waves》2014,35(1):131-146
Recent developments of coherent terahertz (THz) oscillators based on the intrinsic Josephson junctions (IJJs) in mesas of the high temperature superconductor Bi2Sr2CaCu2O8+δ are reviewed. Experimental and theoretical studies of the emission from equilateral, right-angled isosceles, and acute isosceles triangular mesas are compared with those obtained from rectangular, square, and disk mesas, in order to determine the role of the mesa geometry. The superconducting properties and emission frequency f spectra are presented for a variety of triangular mesa geometries. Analytic and finite difference time domain numerical calculations of the emissions from the internal electromagnetic (EM) cavity modes of triangular mesas are compared with experiment. The experimental f always satisfies the ac Josephson relation, and its narrow linewidth arises from the synchronized emissions from many IJJs. For some mesa geometries, f also strongly locks onto an EM cavity mode frequency, enhancing the emission’s stability and output power. For other geometries, such cavity mode locking is weak, and f is highly tunable. 相似文献
982.
983.
984.
Takahiro Kunimine Toshiyuki Fujii Susumu Onaka Nobuhiro Tsuji Masaharu Kato 《Journal of Materials Science》2011,46(12):4290-4295
Effects of Si addition on mechanical properties of severely deformed copper by accumulative roll-bonding (ARB) have been investigated.
Tensile tests and strain-rate jump tests have been carried out at room temperature. For annealed coarse-grained polycrystals,
the difference in yield stress σ
0.2 between pure copper and a Cu–1.64at.%Si alloy was only about 15 MPa while the difference became 170 MPa after the ARB process
by six cycles. The strain-rate sensitivity m of pure copper increased with increasing the number N of the ARB cycles for N ≥ 5. However, the increase in m becomes less significant for Cu–Si alloys. These findings have been discussed in terms of thermally activated dislocation
processes. 相似文献
985.
Mandelonitrile benzoate, a minor defense component produced by polydesmoid millipedes, is produced in large amounts together
with hydrogen cyanide following shake-disturbances administered to individuals of Nedyopus tambanus tambanus, Parafontaria tonominea, Epanerchodus sp., and Epanerchodus fulvus. These species commonly produce mandelonitrile and benzoyl cyanide (the oxidized product after discharge). The newly generated
mandelonitrile benzoate was identified as a product of post secretion Schotten-Baumann reaction under basic conditions of
bled bodily fluids (pH ca. 9.0), and was not an enzymatic reaction product. The reaction occurred in vitro even under less basic conditions [1M Tris-HCl buffer (pH 8.0)], and could be defined as a new mechanism of hydrogen cyanide release occurring in roughly half
of polydesmoid millipedes. Species possessing no benzoyl cyanide, such as Oxidus gracilis and Cryptocorypha sp., could also produce mandelonitrile benzoate under conditions in which benzoyl cyanide was exogenously provided. 相似文献
986.
The increasing importance of nanotechnology in the biomedical field and the recent progress of nanomedicines into clinical testing have spurred the development of even more sophisticated nanoscale drug carriers. Current nanocarriers can successfully target cells, release their cargo in response to stimuli, and selectively deliver drugs. More sophisticated nanoscale carriers should evolve into fully integrated vehicles with more complex capabilities. First, they should be able to sense targets inside the body and adapt their functions based on these targets. Such devices will also have processing capabilities, modulating their properties and functions in response to internal or external stimuli. Finally, they will direct their function to the aimed site through both subcellular targeting and delivery of loaded drugs. These nanoscale, multifunctional drug carriers are defined here as nanodevices. Through the integration of various imaging elements into their design, the nanodevices can be made visible, which is an essential feature for the validation. The visualization of nanodevices also facilitates their use in the clinic: clinicians can observe the effectiveness of the devices and gain insights into both the disease progression and the therapeutic response. Nanodevices with this dual diagnostic and therapeutic function are called theranostic nanodevices. In this Account, we describe various challenges to be overcome in the development of smart nanodevices based on supramolecular assemblies of engineered block copolymers. In particular, we focus on polymeric micelles. Polymeric micelles have recently received considerable attention as a promising vehicle for drug delivery, and researchers are currently investigating several micellar formulations in preclinical and clinical studies. By engineering the constituent block copolymers to produce polymeric micelles that integrate multiple smart functionalities, we and other researchers are developing nanodevices with favorable clinical properties. 相似文献
987.
Nokeun Park Lijia Zhao Akinobu Shibata Nobuhiro Tsuji 《JOM Journal of the Minerals, Metals and Materials Society》2014,66(5):765-773
Phase transformation from austenite to ferrite is an important process to control the microstructures of steels. To obtain finer ferrite grains for enhancing its mechanical property, various thermomechanical processes followed by static ferrite transformation have been carried out for austenite phase. This article reviews the dynamic transformation (DT), in which ferrite transforms during deformation of austenite, in a 6Ni-0.1C steel recently studied by the authors. Softening of flow stress was caused by DT, and it was interpreted through a true stress–true strain curve analysis. This analysis predicted the formation of ferrite grains even above the Ae3 temperature (ortho-equilibrium transformation temperature between austenite and ferrite), where austenite is stable thermodynamically, under some deformation conditions, and the occurrence of DT above Ae3 was experimentally confirmed. Moreover, the change in ferrite grain size in DT was determined by deformation condition, i.e., deformation temperature and strain rate at a certain strain, and ultrafine ferrite grains with a mean grain size of 1 μm were obtained through DT with subsequent dynamic recrystallization of ferrite. 相似文献
988.
Oily constituents were obtained from sapwood and knots of Abies balsamea and A. alba using steam-distillation, and the chemical compositions were determined by gas chromatography and gas chromatography–mass spectrometry. The oily constituents of sapwood and knots of A. balsamea were mainly oxygenated diterpenes with manoyl oxide (1), epi-13-manoyl oxide (2), manool (3), and epi-13-manool (4). Moreover, 2 and 3 were found to be components in A. alba. The constituents of sound knots were dominated by oxygenated diterpenes, together with 2 and 3. Comparison of the content of oxygenated diterpenes from the material revealed that dead knots of A. balsamea contained a large quantity of 4, which was higher than in sapwood. Knots of both Abies spp. contained large quantities of oxygenated diterpenes that were also higher than in sapwood. 相似文献
989.
Nobuhiro Shinohara Shigemi Katori Masataro Okumiya Tadashi Hotta Kenji Nakahira Makio Naito Yong-Ick Cho Keizo Uematsu 《Journal of the European Ceramic Society》2002,22(16):2841-2848
The effects of the heat treatment of Al2O3 granules on the fracture behavior and compressibility of the granules, as well as on the properties of the green and sintered bodies, were examined. Heat treatment contributed to increasing the strength of granules, resulting in poor deformability. However, the hard and brittle characteristics of the heat-treated granules did not hinder the promotion of uniform powder packing and the formation of a nearly cohesive compact under high compaction pressure. Although as-spray-dried granules were more deformable during compaction, they left clear interfaces between granules in the green bodies, resulting in the preservation of large pores in the samples after sintering. The high density and small pore size in green compacts formed with heat-treated granules contributed to reducing the pore-defect size in the sintered bodies, resulting in high fracture strength. 相似文献
990.
We have measured the hole spectra in YSZ:Pr3+ and YSZ:Eu3+ with various Y2O3 concentrations at low temperature. The temperature dependence of the hole width which obtained from the hole spectra in YSZ:Pr3+ and YSZ:Eu3+ was similar to that for disordered materials.However, the Y2O3 concentration dependence of the hole width in YSZ:Pr3+ was contrary to that for YSZ:Eu3+ at low temperature. The hole width was the widest in the case of YSZ:Pr3+ at 10 mol% Y2O3. On the contrary, it was the narrowest in the case of YSZ:Eu3+ at the same concentration of Y2O3. It was found that there are two states in YSZ, in which the degree of ordered differs from each other. Additionally, the Y2O3 concentration dependence of the hole width at low temperature has reflected the ionic conductivity of YSZ at high temperature. It is suggested that the ordering of local structure is responsible for the ionic conduction in YSZ.© 2003 Elsevier Science Ltd. All rights reserved. 相似文献