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排序方式: 共有448条查询结果,搜索用时 140 毫秒
1.
Koji Kamagata Christina Andica Ayumi Kato Yuya Saito Wataru Uchida Taku Hatano Matthew Lukies Takashi Ogawa Haruka Takeshige-Amano Toshiaki Akashi Akifumi Hagiwara Shohei Fujita Shigeki Aoki 《International journal of molecular sciences》2021,22(10)
There has been an increasing prevalence of neurodegenerative diseases with the rapid increase in aging societies worldwide. Biomarkers that can be used to detect pathological changes before the development of severe neuronal loss and consequently facilitate early intervention with disease-modifying therapeutic modalities are therefore urgently needed. Diffusion magnetic resonance imaging (MRI) is a promising tool that can be used to infer microstructural characteristics of the brain, such as microstructural integrity and complexity, as well as axonal density, order, and myelination, through the utilization of water molecules that are diffused within the tissue, with displacement at the micron scale. Diffusion tensor imaging is the most commonly used diffusion MRI technique to assess the pathophysiology of neurodegenerative diseases. However, diffusion tensor imaging has several limitations, and new technologies, including neurite orientation dispersion and density imaging, diffusion kurtosis imaging, and free-water imaging, have been recently developed as approaches to overcome these constraints. This review provides an overview of these technologies and their potential as biomarkers for the early diagnosis and disease progression of major neurodegenerative diseases. 相似文献
2.
Effects of CuO Addition on Electrical Properties of 0.6BiFeO3–0.4(Bi0.5K0.5)TiO3 Lead‐Free Piezoelectric Ceramics 下载免费PDF全文
0.6BiFeO3–0.4(Bi0.5K0.5)TiO3 (0.6BF–0.4BKT) ceramic samples with 0.0–4.0 mol% CuO were prepared by the solid‐state reaction. The CuO addition aided the densification of the samples and slightly increased the lattice constant. The relaxor‐like defuse dielectric peak of 0.6BF–0.4BKT became sharper with increasing the CuO content. Polarization–electric field curve of the undoped 0.6BF–0.4BKT was a pinched loop in the as‐sintered state, while that was a square hysteresis with a large remanent polarization of 48 μC/cm2 after the thermal quenching, demonstrating a strong domain wall pinning due to defect dipoles. We found that the CuO addition up to 2.0 mol% facilitates the polarization switching in the as‐sintered samples to increase the remanent polarization and the piezoelectric d33 coefficient. The results of the structural and electrical investigations suggested that the copper ion acts as a donor in 0.6BF–0.4BKT by compensating the potassium vacancy created by the evaporation of K2O during the calcination and sintering processes. 相似文献
3.
4.
Huawei Chen Xiaopeng Shang Ichiro Hagiwara Deyuan Zhang 《Journal of Porous Materials》2012,19(4):511-518
Patterned micro- and nanostructure are of great significance in industrial applications such as electronics, optics and sensors. Microporous honeycomb film of polyhpenylene oxide (PPO) was fabricated as the template via evaporation of solution in carbon bisulfide under humid ambience. The effect of fabrication conditions on patterned microstructure was investigated by self-organization experiments to build quantitative relationship between ambient conditions such as humidity, concentration and honeycomb microstructure (diameter and height), through which the honeycomb film formation can be controlled to self-organize desirable PPO patterned microstructure. Especially, the height of honeycomb was derived from the diameter of honeycomb, and its validity was clarified by morphological comparison between PPO template and PDMS molded structure. Moreover, soft mold experiments were conducted to demonstrate its high efficiency and excellence as an alternative to construct regular micro-pattern. 相似文献
5.
Zhi-xue Tian Akifumi Uozumi Ikutaro Hamada Susumu Yanagisawa Hidetoshi Kizaki Kouji Inagaki Yoshitada Morikawa 《Nanoscale research letters》2013,8(1):203
First-principles calculations were performed to investigate the effect of Pd concentration and oxygen vacancies on the stability of Pd at LaFeO3 surfaces. We found a much stronger tendency of Pd to segregate by taking the aggregation of Pd at LaFe1-xPdxO3-y surfaces into consideration, resulting in a pair of Pd-Pd around a vacancy. Moreover, we predicted that one oxygen-vacancy-containing FeO2-terminated surfaces would be stable at high temperatures by comparing the stability of LaFe1-xPdxO3-y surfaces, which further supports our previous conclusion that a Pd-containing perovskite catalyst should be calcined at 1,073 K or higher temperatures in air to enhance the segregation of Pd in the vicinity of surfaces to rapidly transform the Pd catalyst from oxidized to reduced states on the perovskite support. 相似文献
6.
Masahiro Takahashi Yutaka Kimura Mitsuki Hagiwara Keiki Kishikawa Shigeo Kohmoto 《Synthetic Metals》2011,161(15-16):1557-1562
Improved synthesis and reinvestigation of the magnetic properties of triphenylamine bearing three nitronylnitroxide radicals (1) were carried out. Single crystal X-ray crystallographic analysis of 1 established that its molecular shape had a C3-symmetry. Our newly prepared 1 showed different physical properties from those of reported. SQUID measurements of 1 showed that each of the three spins of 1 behaved independently at room temperature. In contrast, the three spins coupled antiferromagnetically at lower temperature as low as ca. 1.8 K. These spin behaviors can be explained by a regular triangular antiferromagnetic model (J/kB = ?3.3 K) and interpreted as a spin frustration system. 相似文献
7.
Jiping Li Gang Tong Dianbo Shi Meng Geng Huawei Zhu Ichiro Hagiwara 《Engineering with Computers》2009,25(3):279-285
The recognition and suppression of small features from B-rep models play an important role in effectively generating the qualified
mesh for analysis. This paper presents a new algorithm for recognizing small blends automatically for the purpose of mesh
generation. The algorithm first transforms the input B-rep model into an aggregation of faces. Then, each face is judged to
be a blend or not based on matching conditions. At last, the blends with larger physical sizes than a threshold value are
excluded. The innovations lie in the recognition conditions and the unique calculating procedure of the blend physical size.
Several examples are given to demonstrate the validity and applicability of the algorithm. 相似文献
8.
A comparative study of the cell performance of CIGS thin-film solar cells fabricated using ZnO:Al and ZnO:B window layers has been carried out. ZnO:B films were deposited by RF magnetron sputtering using an undoped ZnO target in a B2H6–Ar gas mixture. The short-circuit current (Jsc) was found to improve upon the replacement of the ZnO:Al layer with ZnO:B layers. This improvement in Jsc is attributed to an increase in quantum efficiency due to the higher optical transmission of the ZnO:B layer in the near-infrared region. The best cell fabricated with a MgF2/ZnO:B/i-ZnO/CdS/CIGS/Mo structure yielded an active area efficiency of 18.0% with Voc=0.645 V, Jsc=36.8 mA/cm2, FF=0.76, and an active area of 0.2 cm2 under AM 1.5 illumination. 相似文献
9.
Yi-Xiong Feng He Hao Jian-Rong Tan Ichiro Hagiwara 《International Journal of Mechanics and Materials in Design》2010,6(2):123-134
A new variant design method of mechanical part is proposed based on extensible logic theory, to support design knowledge reuse
more efficiently in computer aided conceptual design. In this method, matter-element, event-element and relation-element are
used to characterize the feature information, connection constraint relations and topology variant operations of mechanical
conceptual structures respectively. Extensible composite-element model of product part is established sequentially based on
the above three basic-element models (matter-element, event-element and relation-element). Moreover, five types of variant
operations are defined in order to realize structure variations and shape design of mechanical parts. Finally, an example
of shaft housing part in grinder component is taken to explain the part variant design process in details, in which the efficiency
and effectiveness of this method are illustrated simultaneously. 相似文献
10.
Guo-Qing Zheng K. Katayama M. Kandatsu N. Nishihagi S. Kimura M. Hagiwara K. Kindo 《Journal of Low Temperature Physics》2010,159(1-2):280-283
We report the 59Co-NMR observation by spin-echo method at pulsed high magnetic fields up to 48 T. The 22 mm bore-resistive coil magnet with an inductance of 7.59 mH has a total time duration of 50 ms. After discharging the capacitor bank, NMR signals were observed near the maximum field. By repeatedly pulsing the RF sequence around the maximum field, spin echoes at different fields were recorded to give the NMR spectrum. 相似文献