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排序方式: 共有5273条查询结果,搜索用时 187 毫秒
211.
Yuan Gao Takashi Kodama Yoonjin Won Senyo Dogbe Lawrence Pan Kenneth E. Goodson 《Carbon》2012,50(10):3789-3798
The mechanical compliance of vertically aligned carbon nanotube (VACNT) films renders them promising as interface materials that can accommodate thermal expansion mismatch. Here we study the relationship between the detailed morphology and elastic modulus of multi-walled VACNT films with thicknesses ranging from 98 to 1300 μm. A systematic analysis of scanning electron micrographs reveals variations in nanotube alignment and density among samples and within different regions of a given film. Nanoindentation of both top and bottom film surfaces using an atomic force microscope with spherical indenters with radii between 15 and 25 μm provides evidence of the modulus differences. The top surface is shown to have a higher modulus than the base, with out-of-plane modulus values of 1.0–2.8 MPa (top) and 0.2–1.4 MPa (base). The indentation data and microstructural information obtained from electron microscopy are interpreted together using an open cell foam model to account for differences in nanotube alignment and density, which are generally lower at the base and yield predictions that are consistent with the modulus data trends. This work shows that microstructure analysis complements property measurements to improve our understanding of nanostructured materials. 相似文献
212.
Abstract The dynamic properties of doubly-scattered speckles produced at the image plane have been investigated using a scattering model that consists of a coherent Gaussian beam, a cascade of two moving diffusers and a single imaging lens. Dependence of the fluctuation speed of time-varying image speckles on the velocities of the diffusers is found to change with the size of illuminating speckles and the width of the point-spread function of the imaging lens. When the point-spread function and the focal position satisfy certain conditions, three kinds of velocity information—the velocity of each diffuser, the average velocity of the diffusers and the velocity difference between the diffusers—can be obtained by measuring a temporal correlation length of the time-varying speckle intensity. Experimental results confirm the theoretical predictions. 相似文献
213.
Xiaojun Wang Takashi Takeda Naoto Hirosaki Shiro Funahashi Rong-Jun Xie 《中国稀土学报(英文版)》2018,36(1):42-48
Discovery of novel phosphors is extremely important to target the ever change of the solid state lighting technology. In this paper, we present a high-speed way to discover new phosphors, namely single-particle-diagnosis approach. This approach is based on investigating the crystal structure and luminescence of a tiny single crystal, without the necessity of the growth of large-size single crystals or the preparation of single phase powder samples. The concept of the approach and some new nitride phosphors explored by this approach are shown in this paper. 相似文献
214.
Yoshimitsu Sagara Toru Komatsu Tasuku Ueno Kenjiro Hanaoka Takashi Kato Tetsuo Nagano 《Advanced functional materials》2013,23(42):5277-5284
Switching of the luminescence properties of molecular materials in response to mechanical stimulation is of fundamental interest and also has a range of potential applications. Herein, a water‐soluble mechanochromic luminescent pyrene derivative having two hydrophilic dendrons is reported. This pyrene derivative is the first example of a mechanochromic luminescent organic compound that responds to relative humidity. Mechanical stimulation (grinding) of this pyrene derivative in the solid state results in a change of the photoluminescence from yellow to green. Subsequent exposure to water vapor induces recovery of the initial yellow photoluminescence. The color change is reversible through at least ten cycles. It is also demonstrated that this compound can be applied as a mechano‐sensing material in frictional wear testing for grease, owing to its immiscibility in non‐polar solvents and its non‐crystalline behavior. Transmission electron microscope and atomic force microscope observations of samples prepared from dilute aqueous solutions of the pyrene derivative on suitable substrates, together with dynamic light scattering measurements for the compound in aqueous solution, indicate that this amphiphilic dumbbell‐shaped molecule forms micelles in water. 相似文献
215.
Kotaro Matsushita Shun Koshikawa Taito Endoh Jong G. Park Takashi Yamaguchi Kennth J. Mackin Eiji Nunohiro 《Artificial Life and Robotics》2014,19(3):258-261
It is important for environment protection to monitor changes in the environment by natural and human causes. It is also important to educate the next generation on the importance of the global environment issues. Recently, it has become possible to continually monitor the global environment using various satellite sensor data. But these satellite data are used for highly specialized analysis by experts in such fields, and the data cannot easily be used by non-experts. In this paper, we propose a satellite data visualization system for educational use. In the proposed system, a gray-scale 2-dimensional image is created from the satellite data. Next, a pseudo-color image is created from the gray-scale image to assist the comprehension of the data. A 3-dimensional data representation of the image is also created, to assist the comparison of the individual data. The aim of the created image is for educational use, and the image is created with emphasis on comprehension of the data, rather than presentation of data details. The aim of the proposed system is presenting the satellite data visually so that non-experts can easily understand. The target of this research is to apply the proposed system for natural science education and to improve the awareness of global environmental issues. 相似文献
216.
ABSTRACT: Forming electrodes on opposite sides of an individual bismuth nanowire was attempted to prepare for Hall measurements. Although a 1-mm-long bismuth nanowire which is completely covered with a quartz template has been successfully fabricated to prevent oxidation, it is very difficult to attach Hall electrodes on the opposite sides of the nanowire due to the quartz covering. One side of the cylindrical quartz template was removed by polishing without exposure of the nanowire to the atmosphere; the thickness between the polished template surface and the nanowire was estimated to be several micrometers. Focused ion beam processing was successfully employed to expose both surfaces of the nanowire under high vacuum by removing part of the quartz template. A carbon thin film was then deposited in situ on the wire surface to fabricate an electrical contact on the bismuth nanowire sample. Furthermore, the energy dispersive X-ray analysis was performed to the area processed by focused ion beam, and the bismuth component of the nanowire was successfully detected. It was confirmed that the focused ion beam processing was applicable to attach electrodes to bismuth nanowire for Hall measurement. 相似文献
217.
Yoshimune Nonomura Taku Miura Takaaki Miyashita Yuka Asao Hirokazu Shirado Yasutoshi Makino Takashi Maeno 《Journal of the Royal Society Interface》2012,9(71):1216-1223
Water detection is one of the most crucial psychological processes for many animals. However, nobody knows the perception mechanism of water through our tactile sense. In the present study, we found that a characteristic frictional stimulus with large acceleration is one of the cues to differentiate water from water contaminated with thickener. When subjects applied small amounts of water to a glass plate, strong stick-slip phenomena with a friction force of 0.46 ± 0.30 N and a vertical force of 0.57 ± 0.36 N were observed at the skin surface, as shown in previous studies. Surprisingly, periodic shears with acceleration seven times greater than gravitational acceleration occurred during the application process. Finite-element analyses predicted that these strong stimuli could activate tactile receptors: Meissner''s corpuscle and Pacinians. When such stimuli were applied to the fingertips by an ultrasonic vibrator, a water-like tactile texture was perceived by some subjects, even though no liquid was present between the fingertip and the vibrator surface. These findings could potentially be applied in the following areas: materials science, information technology, medical treatment and entertainment. 相似文献
218.
Yasuhiro Yogo Michiaki Kamiyama Takamichi Iwata Noritoshi Iwata Takashi Ishikawa 《Metallurgical and Materials Transactions A》2012,43(3):893-899
In this article, the isothermal flow stress in supercooled austenite was measured for a high hardenability steel. Supercooled
austenite forms at the nonequilibrium phase and changes into other phases within a short time. It was confirmed that conventional
tensile tests, which require maintaining a constant temperature before stretching, cannot accurately measure the flow stress
in supercooled austenite. Therefore, a new tensile test named “the continuous cooling tensile test” was developed. In this
test, stretching is conducted during continuous cooling. In the continuous cooling tensile test, the flow stress between 673 K
and 973 K (400 °C and 700 °C) was measured. Microscopic observations of the continuous cooling test results verified that
the microstructures were supercooled austenite. 相似文献
219.
Ikuko Kakizaki Ayako Miura Takashi Mineta Jinseo Hong Yoji Kato 《Journal of Applied Glycoscience》2017,64(4):83
Salmon cartilage proteoglycan fractions have recently gained favor as ingredients of functional food and cosmetics. An optimal hot water method to extract proteoglycan from salmon cartilage has recently been developed. The extracted cartilage includes hyaluronan and collagen in addition to proteoglycan as counterparts that interact with each other. In this study, biochemical analyses and atomic force microscopical analysis revealed global molecular images of proteoglycan in the hot water extract. More than seventy percent of proteoglycans in this extract maintained their whole native structures. Hyaluronan purified from the hot water extract showed a distribution with high molecular weight similar to hyaluronan considered to be native hyaluronan in cartilage. The current data is evidence of the quality of this hot water cartilage extract. 相似文献
220.