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排序方式: 共有165条查询结果,搜索用时 31 毫秒
61.
Shaver J Kono J Portugall O Krstić V Rikken GL Miyauchi Y Maruyama S Perebeinos V 《Nano letters》2007,7(7):1851-1855
We report that symmetry breaking by a magnetic field can drastically increase the photoluminescence quantum yield of single-walled carbon nanotubes, by as much as a factor of 6, at low temperatures. To explain this we have developed a theoretical model based on field-dependent exciton band structure and the interplay of Coulomb interactions and the Aharonov-Bohm effect. This conclusively explains our data as the first experimental observation of dark excitons 5-10 meV below the bright excitons. 相似文献
62.
Xi Xiong Yonglin Xiong Takashi Tsunemoto Shogo Okino Xiaoyue Qiu Yuhei Kurimoto Feng Zhang 《Soils and Foundations》2019,59(2):253-270
Generally speaking, most of the geomaterials in the surface ground are in an unsaturated state. The mechanical and hydraulic properties of unsaturated soil are much more complicated than those of saturated soil. To rationally describe these properties, it is important to couple the stress-strain relation of the unsaturated soil with its water retention characteristics using rational state variables. In this paper, oedometer and triaxial compression tests on decomposed granite under constant-suction and constant degree of saturation conditions were conducted. Based on the test results, a modified constitutive model was proposed to build an incremental relation between the degree of saturation and suction that considers the influence of finite deformation. The modified model was utilized to simulate the corresponding laboratory tests. It is found that the modified constitutive model has satisfactory accuracy to describe the mechanical and hydraulic properties of unsaturated decomposed granite, which verified the reasonability of the assumption adopted in this paper. The test results are also helpful for the understanding of the moisture characteristics of the decomposed granite under constant degree of saturation condition. 相似文献
63.
针对离心式压缩机转子系统振动小,振动信号具有非平稳、非线性和伴随噪声干扰的特点,提出一种总体平均经验模式分解(Ensemble Empirical mode decomposition, EEMD)联合主分量分析(Principal component analysis, PCA)的故障识别方法。该方法以相关分析结合傅立叶变换选择基本模式分量(intrinsic mode function, IMF)为基础,构造了波动变化性指标以定量识别EEMD的噪声幅值参数;进一步获取各运行状态的14种时域振动评价指标并构造标准化特征数据集后,采用PCA降维法得出不同类型故障的振动模式类别。通过对离心式压缩机转子典型故障的振动信号分析,其结果表明该方法能够在解除信号非平稳非线性干扰的基础上,快速独立地提取信号中的主要振动模式,制定表征不同故障类别的特征数据区域,从而有效提高了离心式压缩机的故障识别能力。 相似文献
64.
Chun-Feng Chu Yoshitaka Ebie Kai-Qin Xu Yu-You Li Yuhei Inamori 《International Journal of Hydrogen Energy》2010
The structure of a microbial community in the two-stage process for H2 and CH4 production from food waste was investigated by a molecular biological approach. The process was a continuous combined thermophilic acidogenic hydrogenesis and mesophilic (RUN1) or thermophilic (RUN2) methanogenesis with recirculation of the digested sludge. A two-phase process suggested in this study effectively separate H2-producing bacteria from methanogenic archaea by optimization of design parameters such as pH, hydraulic retention time (HRT) and temperature. Galore microbial diversity was found in the thermophilic acidogenic hydrogenesis, Clostridium sp. strain Z6 and Thermoanaerobacterium thermosaccharolyticum were considered to be the dominant thermophilic H2-producing bacteria. The hydrogenotrophic methanogens were inhibited in thermophilic methanogenesis, whereas archaeal rDNAs were higher in the thermophilic methanogenesis than those in mesophilic methanogenesis. The yields of H2 and CH4 were in equal range depending on the characteristics of food waste, whereas effluent water quality indicators were different obviously in RUN1 and RUN2. The results indicated that hydrolysis and removal of food waste were higher in RUN2 than RUN1. 相似文献
65.
Junko Takahashi Shinsuke Nagasawa Motomichi Doi Masamichi Takahashi Yoshitaka Narita Junkoh Yamamoto Mitsushi J. Ikemoto Hitoshi Iwahashi 《International journal of molecular sciences》2021,22(18)
To treat malignant glioma, standard fractionated radiotherapy (RT; 60 Gy/30 fractions over 6 weeks) was performed post-surgery in combination with temozolomide to improve overall survival. Malignant glioblastoma recurrence rate is extremely high, and most recurrent tumors originate from the excision cavity in the high-dose irradiation region. In our previous study, protoporphyrin IX physicochemically enhanced reactive oxygen species generation by ionizing radiation and combined treatment with 5-aminolevulinic acid (5-ALA) and ionizing radiation, while radiodynamic therapy (RDT) improved tumor growth suppression in vivo in a melanoma mouse model. We examined the effect of 5-ALA RDT on the standard fractionated RT protocol using U251MG- or U87MG-bearing mice. 5-ALA was orally administered at 60 or 120 mg/kg, 4 h prior to irradiation. In both models, combined treatment with 5-ALA slowed tumor progression and promoted regression compared to treatment with ionizing radiation alone. The standard fractionated RT protocol of 60 Gy in 30 fractions with oral administration of 120 and 240 mg/kg 5-ALA, the human equivalent dose of photodynamic diagnosis, revealed no significant increase in toxicity to normal skin or brain tissue compared to ionizing radiation alone. Thus, RDT is expected to enhance RT treatment of glioblastoma without severe toxicity under clinically feasible conditions. 相似文献
66.
Yuhei Oi Tomohisa Nagoshi Haruka Kimura Yoshiro Tanaka Akira Yoshii Rei Yasutake Hirotake Takahashi Yusuke Kashiwagi Toshikazu D. Tanaka Toshiaki Tachibana Michihiro Yoshimura 《International journal of molecular sciences》2022,23(15)
Increasing evidence suggests natriuretic peptides (NPs) coordinate interorgan metabolic crosstalk. We recently reported exogenous ANP treatment ameliorated systemic insulin resistance by inducing adipose tissue browning and attenuating hepatic steatosis in diet-induced obesity (DIO). We herein investigated whether ANP treatment also ameliorates myocardial insulin resistance, leading to cardioprotection during ischemia–reperfusion injury (IRI) in DIO. Mice fed a high-fat diet (HFD) or normal-fat diet for 13 weeks were treated with or without ANP infusion subcutaneously for another 3 weeks. Left ventricular BNP expression was substantially reduced in HFD hearts. Intraperitoneal-insulin-administration-induced Akt phosphorylation was impaired in HFD hearts, which was restored by ANP treatment, suggesting that ANP treatment ameliorated myocardial insulin resistance. After ischemia–reperfusion using the Langendorff model, HFD impaired cardiac functional recovery with a corresponding increased infarct size. However, ANP treatment improved functional recovery and reduced injury while restoring impaired IRI-induced Akt phosphorylation in HFD hearts. Myocardial ultrastructural analyses showed increased peri-mitochondrial lipid droplets with concomitantly decreased ATGL and HSL phosphorylation levels in ANP-treated HFD, suggesting that ANP protects mitochondria from lipid overload by trapping lipids. Accordingly, ANP treatment attenuated mitochondria cristae disruption after IRI in HFD hearts. In summary, exogenous ANP treatment ameliorates myocardial insulin resistance and protects against IRI associated with mitochondrial ultrastructure modifications in DIO. Replenishing biologically active NPs substantially affects HFD hearts in which endogenous NP production is impaired. 相似文献
67.
Yuki Suzuki Takeshi Kikuchi Hisashi Goto Yuhei Takayanagi Shotaro Kawamura Noritaka Sawada Yoshikazu Naiki Hisataka Kondo Jun-ichiro Hayashi Yoshiaki Hasegawa Akio Mitani 《International journal of molecular sciences》2022,23(23)
The effect of Mfa1 fimbriae of Porphyromonas gingivalis on the progression of bone resorption remains unclear, especially compared with another fimbriae, FimA. We investigated the effect of Mfa1 on osteoclastogenesis together with FimA. We also investigated the role of Toll-like receptors (TLRs) in Mfa1 recognition during osteoclast differentiation. Receptor activator of nuclear factor κβ ligand (RANKL)-prestimulated RAW264 cells were used to examine the effects of purified Mfa1 fimbriae. The number of osteoclasts was examined by tartrate-resistant acid phosphate (TRAP) staining, osteoclast activation was investigated by bone resorption assays, and gene expression of differentiation markers was examined by quantitative real-time PCR. Transfection of Tlr2 and Tlr4 siRNAs into RAW264 cells was also employed and their role in Mfa1 recognition was investigated. Mfa1 effectively induced the formation of TRAP-positive multinucleated cells and activated osteoclasts. Mfa1 also increased gene expression of Acp5, Mmp9, and Ctsk in RANKL-prestimulated RAW264 cells compared with the control. The osteoclastogenesis induced by Mfa1 was significantly decreased in cells transfected with Tlr2 or Tlr4 siRNAs compared with control siRNA. Our results revealed the role of Mfa1 fimbriae in osteoclastogenesis that may contribute to the partial elucidation of the mechanisms of periodontal disease progression and the development of new therapeutic strategies. 相似文献
68.
Efficient Photocarrier Transfer and Effective Photoluminescence Enhancement in Type I Monolayer MoTe2/WSe2 Heterostructure
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Takao Yamaoka Hong En Lim Sandhaya Koirala Xiaofan Wang Keisuke Shinokita Mina Maruyama Susumu Okada Yuhei Miyauchi Kazunari Matsuda 《Advanced functional materials》2018,28(35)
Artificial van der Waals heterostructures of 2D layered materials are attractive from the viewpoint of the possible discovery of new physics together with improved functionalities. Stacking various combinations of atomically thin semiconducting transition metal dichalcogenides, MX2 (M = Mo, W; X = S, Se, Te) with a hexagonal crystal structure, typically leads to the formation of a staggered Type II band alignment in the heterostructure, where electrons and holes are confined in different layers. Here, the comprehensive studies are performed on heterostructures prepared from monolayers of WSe2 and MoTe2 using differential reflectance, photoluminescence (PL), and PL excitation spectroscopy. The MoTe2/WSe2 heterostructure shows strong PL from the MoTe2 layer at ≈1.1 eV, which is different from the quenched PL from the WSe2 layer. Moreover, enhancement of PL intensity from the MoTe2 layer is observed because of the near‐unity highly efficient photocarrier transfer from WSe2 to MoTe2. These experimental results suggest that the MoTe2/WSe2 heterostructure has a Type I band alignment where electrons and holes are confined in the MoTe2 layer. The findings extend the diversity and usefulness of ultrathin layered heterostructures based on transition metal dichalcogenides, leading to possibilities toward future optoelectronic applications. 相似文献
69.
N Tsuboyama-Kasaoka N Tsunoda K Maruyama M Takahashi H Kim S Ikemoto O Ezaki 《Canadian Metallurgical Quarterly》1998,247(2):498-503
In skeletal muscles, increased utilization of lipids and carbohydrates accompanied with increased energy expenditure has been observed during and after exercise. UCP3, mitochondrial uncoupling protein, is expressed in skeletal muscles. We investigated UCP3 mRNA levels in exercise training mice which increased energy expenditure and in sciatic nerve-denervated mice which decreased energy expenditure. Mice exercised by 2 wk swimming had 14- to 18-fold increases of UCP3 mRNA in skeletal muscles 3 h after the last swimming, but no increases of UCP1 mRNA in BAT and of UCP2 mRNA in WAT. However, 22 h after exercise, UCP3 mRNA increases observed in skeletal muscles 3 h after exercise returned to sedentary levels. Similar transient increases of UCP3 mRNA were observed in 1 wk treadmill running training or a single exercise bout. In denerved gastrocnemius, GLUT4 and UCP3 mRNA decreased by 58 and 45%, respectively. These data indicate that UCP3 may have a role for fine adjustments of energy expenditure and that up-regulation of UCP3 mRNA may be a defense mechanism against extra energy supply to consume extra energy in skeletal muscles. 相似文献
70.