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排序方式: 共有1336条查询结果,搜索用时 15 毫秒
181.
Hiroya Nishikawa Kazuya Shiroshita Hiroki Higuchi Yasushi Okumura Yasuhiro Haseba Shin‐ichi Yamamoto Koki Sago Hirotsugu Kikuchi 《Advanced materials (Deerfield Beach, Fla.)》2017,29(43)
An anomalously large dielectric permittivity of ≈104 is found in the mesophase temperature range (MP phase) wherein high fluidity is observed for a liquid‐crystal compound having a 1,3‐dioxane unit in the mesogenic core (DIO). In this temperature range, no sharp X‐ray diffraction peak is observed at both small and wide Bragg angles, similar to that for a nematic phase; however, an inhomogeneous sandy texture or broken Schlieren one is observed via polarizing optical microscopy, unlike that for a conventional nematic phase. DIO exhibits polarization switching with a large polarization value, i.e., P = 4.4 µC cm?2, and a parallelogram‐shaped polarization–electric field hysteresis loop in the MP phase. The inhomogeneously aligned DIO in the absence of an electric field adopts a uniform orientation along an applied electric field when field‐induced polarization switching occurs. Furthermore, sufficiently larger second‐harmonic generation is observed for DIO in the MP phase. Second‐harmonic‐generation interferometry clearly shows that the sense of polarization is inverted when the +/? sign of the applied electric field in MP is reversed. These results suggest that a unidirectional, ferroelectric‐like parallel polar arrangement of the molecules is generated along the director in the MP phase. 相似文献
182.
Takuma Fujii Chiaki Kon Yosuke Motoyama Kan Shimizu Tsutomu Shimayama Takashi Yamazaki Takayoshi Kato Seigou Sakai Koichi Hashikaki Koji Tanaka Yasuhiro Nakano 《Journal of the Society for Information Display》2018,26(3):178-186
A 0.5‐inch Ultra Extended Graphics Array (UXGA) organic light‐emitting diodes microdisplay has been developed with 6.3 μm pixel pitch. Not only 4032 ppi high resolution but high frame rate, low power consumption, wide viewing angle, and high luminance have been achieved. This newly developed organic light‐emitting diodes microdisplay is suitable for Near‐to‐Eye display applications, especially electronic viewfinders. 相似文献
183.
Relationship between structure and physical strength of silk fibroin nanofiber sheet depending on insolubilization treatment 下载免费PDF全文
Yasuhiro Fukuda Derya Aytemiz Akira Higuchi Yuya Ichida Tetsuo Asakura Tsunenori Kameda Yasumoto Nakazawa 《应用聚合物科学杂志》2017,134(48)
Materials such as expanded polytetrafluoroethylene and glutaraldehyde‐fixed bovine pericardium are currently used for cardiac tissue regeneration. However, patches made from these materials remain permanently without being absorbed by the body and must be replaced overtime because of degeneration or lack of growth. To improve the long‐term outcomes for cardiac tissue regeneration, biocompatible and biodegradable materials must be used. In this study, we used two biocompatible polymers, silk fibroin (SF), which is biodegradable and segmented polyurethane, to prepare nonwoven sheets that were then insolubilized by water vapor or methanol treatment. The tensile stress increased significantly on adding segmented polyurethane to pure SF and the water vapor processed sheets showed higher extension on strain than the methanol‐processed sheets. The different insolubilization treatments also resulted in different SF structures. Our results show that it is possible to obtain the physical properties required for cardiac tissue repair patch by varying the insolubilization treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45560. 相似文献
184.
Warner JH Ito Y Zaka M Ge L Akachi T Okimoto H Porfyrakis K Watt AA Shinohara H Briggs GA 《Nano letters》2008,8(8):2328-2335
The rotation of fullerene chains in SWNT peapods is studied using low-voltage high resolution transmission electron microscopy. Anisotropic fullerene chain structures (i.e., C300) are formed in situ in carbon nanopeapods via electron beam induced coalescence of individual fullerenes (i.e., C60). A low electron accelerating voltage of 80 kV is used to prevent damage to the SWNT. The large asymmetric C300 fullerene structure exhibits translational motion inside the SWNT and unique corkscrew like rotation motion. Another asymmetric fullerene chain containing mixed fullerene species is prepared by fusing smaller C60 fullerenes to a larger Sc@C82 fullerene, and this also exhibits corkscrew rotational motion. Chains of Sc3C2@C80 in SWNT peapods adopt a zigzag packing structure, and the entire zigzag chain rotates inside the SWNT to induce structural modifications to the SWNT diameter and cross-sectional shape of the SWNT. The expansion and contraction of the diameter of the SWNT is measured as 17%, demonstrating nanoactuation behavior in carbon nanopeapods. 相似文献
185.
Hisatsune K Shiraishi T Takuma Y Tanaka Y Luciano RH 《Journal of materials science. Materials in medicine》2007,18(4):577-581
Age-hardening behavior during continuous heating in commercial dental casting gold alloys was investigated by means of electrical
resistivity measurements, hardness tests and X-ray diffraction. Two distinguishable behaviors were detected. It is considered
that the difference was attributed to the amount of platinum, and the atomic ratio of gold and copper in each alloy. The phase
transformations during continuous heating progressed into two steps (stages I and II). Increase of the platinum addition in
gold-based alloys retards the rate of the reaction and decreases remarkably the amount of stage I. 相似文献
186.
A new calixarene-based donor-acceptor system, cone conformer 1, was prepared for the first time. In this compound, the calix[4]arene serves to juxtapose a tri-chloroquinone acceptor near the porphyrin photo-donor plane. As to the conformational control, the cone conformer 1 gave two peaks of phenolic OH groups at 8.40 and 8.43 ppm. This shows that cone conformer 1 is stabilized by intramolecular hydrogen bonds. The fluorescence intensity of 1 was 35% of that for the control compound 2. This means the tri-chloroquinone group in 1 efficiently quenched the fluorescence of ZnP*. The shortest edge-to-edge separation of the chromophores of 1 is ca. 8 A (as judged by CPK models). This provides a new calixarene-based supramolecular system in which through-space donor-to-acceptor electron transfer is observed upon photoexcitation. 相似文献
187.
Structures of Rh/1 AL (atomic layer) GeO2/SiO2 were studied during reduction and oxidation processes by means of in situ XAFS (X-ray absorption fine structure). It was found that RhGe bimetallic particles with Rh--Rh and Rh--Ge distances at 0.266 and 0.242 nm were formed after reduction at 723 K, respectively. Subsequent oxidation at 673 K regenerated 1 AL GeO2 structure on the SiO2 surface. This reversible structure transformation is discussed in relation to reactivity and volatility of Ge oxide species. 相似文献
188.
In recent years, attention has been paid to the concept of FACTS (Flexible AC Transmission Systems), along with significant progress in power electronic technology. A high‐speed phase shifter, which is one of the most promising devices in the FACTS concept, has the potential of power flow control and/or voltage stability in power transmission systems. In this paper, theory and experiment reveal that conventional high‐speed phase shifters may cause power swings in a transient state as a result of coupling between instantaneous active and reactive power control loops. Thus, two new control schemes for a high‐speed phase shifter are proposed to achieve both power flow control and power swing damping. The second proposed control scheme is based on the control scheme of an already proposed series active filter. Simulated and experimental results agree well with analytical results, not only in steady states but also in transient states. © 1999 Scripta Technica, Electr Eng Jpn, 128(2): 74–82, 1999 相似文献
189.
Masao Iwai Hiroshi Majima Yasuhiro Awakura 《Metallurgical and Materials Transactions B》1982,13(3):311-318
The oxidation of Fe(II) with dissolved molecular oxygen was studied in sulfuric acid solutions containing 0.2 mol · dm−3 FeSO4 at temperatures ranging from 343 to 363 K. In solutions of sulfuric acid above 0.4 mol · dm−3, the oxidation of Fe (II) was found to proceed through two parallel paths. In one path the reaction rate was proportional
to both [Fe−2+]2 andp
o
2 exhibiting an activation energy of 51.6 · kJ mol−1. In another path the reaction rate was proportional to [Fe2+]2, [SO
4
2
−], andp
o
2 with an activation energy of 144.6 kJ · mol−1. A reaction mechanism in which the SO
4
2
− ions play an important role was proposed for the oxidation of Fe(II). In dilute solutions of sulfuric acid below 0.4 mol
· dm−3, the rate of the oxidation reaction was found to be proportional to both [Fe(II)]2 andp
o
2, and was also affected by [H+] and [SO
4
2
−]. The decrease in [H+] resulted in the increase of reaction rate. The discussion was further extended to the effect of Fe (III) on the oxidation
reaction of Fe (II). 相似文献
190.
Hiroshi Majima Yasuhiro Awakura Takumi Mishima 《Metallurgical and Materials Transactions B》1985,16(1):23-30
The reactions of hematite in aqueous hydrochloric acid, perchloric acid, and sulfuric acid solutions with or without the addition
of common or uncommon salts were studied using monosized particulates in a well-stirred reactor and dilute solid concentration
to obtain fundamental details of the reaction kinetics. The experimental rate data suggest that the entire leaching reaction
is controlled by a chemical process. The leaching rate of hematite was seen to be first order with respect to hydrogen ion
activity, a(H+), in hydrochloric acid or perchloric acid solutions, with or without the addition of common salts, while the rate was of
a half order in sulfuric acid solutions with or without the addition of sodium sulfate. A theoretical analysis showed that
the anions next to the surface in the double layer were chloride ion and perchlorate ion in hydrochloric acid and perchloric
acid solutions, respectively, and sulfate ion in sulfuric acid solutions, with or without the addition of sodium sulfate.
The fact that the leaching rates of hematite were quite different in various acids having identical α(H+ values indicates the importance of anion adsorption. The dependency of the leaching rate upon α(H+) appeared to be controlled by adsorbed anions next to the surface in the double layer.
TAKUMI MISHIMA, formerly Graduate Student, Kyoto University 相似文献