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排序方式: 共有1310条查询结果,搜索用时 15 毫秒
51.
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
52.
We evaluated the effects of seven mushroom extracts (Grifola frondosa, Pholiota nameko, Panellus serotinus, Hypsizygus marmoreus, Pleurotus cornucopiae, Armillaria mellea, and Flammulina velutipes) on cytotoxic activity and cytokine production of lamina propria leukocytes (LPLs) isolated from rat small (S) and large (L) intestinal mucosa. Boiling water extracts from seven species of mushrooms showed no direct cytotoxicity against the YAC-1 target cells. However, prominent increases of cytotoxicity were observed in S- and L-LPLs co-cultured with P. serotinus extract. Cytokine production (TNFα, IFNγ, IL-12 p70, and IL-4) of S- and L-LPLs was stimulated in response to P. cornucopiae extract. Mushroom extracts contributed to target cell adhesion and/or cytokine production in the effector cells. The promotion of cytotoxic activity in S- and L-LPLs was not necessarily related to β-glucan content of the mushroom. 相似文献
53.
Bulky End‐Capped [1]Benzothieno[3,2‐b]benzothiophenes: Reaching High‐Mobility Organic Semiconductors by Fine Tuning of the Crystalline Solid‐State Order 下载免费PDF全文
Guillaume Schweicher Vincent Lemaur Claude Niebel Christian Ruzié Ying Diao Osamu Goto Wen‐Ya Lee Yeongin Kim Jean‐Baptiste Arlin Jolanta Karpinska Alan R. Kennedy Sean R. Parkin Yoann Olivier Stefan C. B. Mannsfeld Jérôme Cornil Yves H. Geerts Zhenan Bao 《Advanced materials (Deerfield Beach, Fla.)》2015,27(19):3066-3072
54.
This study re-visits the effects of loading rate on sand behavior in view of seismic design of pile foundation. Based on an extensive literature review covering both element testing and model testing, the paper summarizes the current understanding of the loading rate effects. The paper then describes the development of test apparatus used in this study and presents the data obtained from a series of monotonically increasing triaxial compression tests on Toyoura sand, varying the strain rate in the range of 0.005%/s to 250%/s. A total of 36 tests were conducted on dry and saturated sand, both under drained and undrained conditions with two confining pressures. The experimental results confirm that the soil strength and the soil stiffness increase as the strain rate increase. This paper also concludes that the internal friction angle and deformation modulus increase when the strain rate is high. The implications of the loading rate effect on pile foundation design are then presented. 相似文献
55.
Poly(3-hexylthiophene-2,5-diyl) is among the most widely used conjugated polymers for opto-electronic applications. To enhance its properties, researchers have attempted to nanostructure this polymer using various processes including breath figure arrays, nanolithography and elaborated organic synthesis. We here demonstrate a simple process to nanostructure the conjugated polymer using self-assembly with polystyrene and selective removal of one of the phases. The influence of the molecular weight of each polymer on the thin film morphology was systematically studied by atomic force microscopy. Using this approach, we observe two types of nanostructure, namely, nanoporous and nanoisland structures, of which the dimensions can be tuned by modifying the molecular weight of each polymer in the blend. This simple process introduces a cost-effective alternative to produce thin films of conjugated polymer with average nano-features from 100 nm up to 500 nm which could be used in a wide range of applications. 相似文献
56.
Osamu?YamashitaEmail author Hirotaka?Odahara Kouji?Satou 《Journal of Materials Science》2005,40(5):1071-1077
The resultant thermoelectric power factors P of M/T/N and M/Bi/M/Bi/M (M and N = Cu or Ni) devices welded with T = Bi or Bi0.88Sb0.12 alloy were measured at 298 K and compared with P values calculated as a function of x by treating these devices as an electrical and thermal circuit, where x is the ratio of thickness of Bi or Bi-Sb alloy to the interval between two thermocouples. Consequently, the Seebeck coefficients of M/T/N devices were enhanced significantly in the middle range from x = 0.3 to 0.8, and the observed P values have a local maximum at small x below x = 0.35. The x-dependence of P values of M/T/N devices was found to be explained well by the simple model proposed here when an enhancement factor in and some reduction in thermal conductivity of pure metal were taken into the calculation. As a whole, however, the observed P values of double-layered M/Bi/M/Bi/M devices are lower than those of single-layered M/Bi/M, so that the macroscopic multi-layering of thermoelectric materials has no effect on the enhancement in P. The maximum P (= 22.1 mW/K2m) of Cu/Bi-Sb/Cu is 1.5 times larger than that of Cu/Bi/Cu and reached 3.6 times as large as the mean value of 5.7 and 6.6 mW/K2m of the high-performance bulk p- and n-type bismuth-telluride compounds. 相似文献
57.
Maehara Fumiaki Nakamura Osamu Takanashi Hitoshi 《Wireless Personal Communications》2000,15(3):181-197
We propose a novel SIR weighting postdetection combining diversity scheme with a new accurate SIR estimation method. The SIR is estimated and used as the weighting factor to compensate severe cochannel interference, one of the most important issues for PCS in terms of frequency utilization. Theimprovement offered by the proposal depends on SIR estimation accuracy.The SIR is, in this paper, estimated by a matched filter where theauto-correlation between received signal and unique word is calculated. Computer simulationsconfirm that the SIR of each diversity branch can be estimated easily andaccuratelyby the proposed SIR estimation method. The proposed diversity scheme achievesaperformance very close to that of ideal SINR weighting diversity underRayleighfading with severe cochannel interference. When average SIR = 10 dB and thenumber of branches(L)=4, the proposed diversity scheme lowers the requiredEb/N0 by 5 dB at BER = 1×10-3compared to conventional maximal ratio combining diversity. This paper alsopresentsthe unique word length required to realize adequate performance, i.e.,robustnessagainst high-pitch Rayleigh fading. 相似文献
58.
Profile structure of magnetic flux lines in type-II superconductor from a rectangular electron hologram 总被引:1,自引:0,他引:1
Harada K Beleggia M Endo J Kasai H Togawa Y Matsuda T Tonomura A 《Journal of electron microscopy》2003,52(4):369-373
Profile magnetic configuration of a quantized flux line and flux-line lattice penetrating a type-II superconductor thin foil, niobium, was observed by electron holography and Lorentz microscopy using a 300 kV field-emission electron microscope. Each single flux line was distributed periodically as lattice structure in the mixed state just below its critical temperature of 8.5 K, while at low temperature of 5 K the flux lines were weakly bound as bundles. In order to observe the flux-line distribution over a wide area, discrete Fourier transform reconstruction in the holography was extended for a rectangular area without loss of information and data precision. 相似文献
59.
Barium titanium trioxide (BaTiO3) thin films were deposited on fused silica or silicon wafer substrate from barium dipivaloylmethanate (II) (Ba(dpm)2) and titanium tetraisopropoxide (IV) (TTIP) used as precursors in an oxygen microwave plasma. The substrates were dielectrically heated and the substrate temperatures were around 900 K during the film deposition. The deposition was performed for 15 min and the deposits were identified as BaTiO3 by means of X-ray diffraction, X-ray photoelectron spectroscopy, infrared spectroscopy, and ellipsometry. Oxygen and barium atoms and TiO and CO molecules were identified in the plasma. These species would produce higher deposition rates at lower substrate temperatures than those did in the usual thermal metalorganic chemical vapor deposition (MOCVD). The dielectric constant of the BaTiO3 thin film that was directly deposited on the silicon wafer substrate was as low as 101 order of magnitude. Because the deposit reacted with the substrate and an interdiffusional layer was formed, the platinum layer was coated on the silicon wafer substrate in order to prevent the formation of an interdiffusional layer. The dielectric constant then increased to 103 order of magnitude. 相似文献
60.
Tadashi Kusumoto Osamu Ishikawa Takao Mizusaki Akira Hirai 《Journal of Low Temperature Physics》1985,59(3-4):269-289
The nuclear spin dynamics in nuclear spin ordered solid3He in low magnetic fields on the melting curve has been studied by pulsed NMR down to 0.6 mK. The free induction decay signals (FID) were measured in single crystals of solid3He at three operating frequencies of 920, 1380, and 1840 kHz. The FIDs were nonexponential and dependent on the rf pulse strength
p
H
1
t
w
, where is the gyromagnetic ratio,H
1 is the rf field strength, andt
w
is the pulse width. At small
p
they decayed almost linearly in time with a small exponential tail at the end. When
p
was further increased they became shorter and neither exponential nor linear in time. At large
p
they decayed very rapidly and sometimes could not be observed at all because of the dead time of the NMR detection system. Such behavior of the FID was observed in many different single crystals in the given temperature range at 920 kHz. Tsubota and Tsuneto have shown by solving the nonlinear equations of motion numerically that the motion of the nuclear spin becomes chaotic when the tipping angle exceeds a critical value. Comparing their result with our experimental results, we concluded that some of the results of the rapid decay of the FID at large
p
might be attributed to the onset of the chaotic motion. At 1840 kHz it is expected that the nonlinear effects in the equations of motion become less effective than that at 920 kHz. In fact, at this operating frequency the FIDs even at large
p
and the tipping angle-dependent frequency shift could be observed. These frequency shifts were in rather good agreement with Namaizawa's theory provided an effective tipping angle was taken into account. 相似文献