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排序方式: 共有2741条查询结果,搜索用时 15 毫秒
1.
Tsuneaki Matsudaira Masashi Wada Naoki Kawashima Miyuki Takeuchi Daisaku Yokoe Takeharu Kato Masasuke Takata Satoshi Kitaoka 《Journal of the European Ceramic Society》2021,41(5):3150-3160
Mass transfer in polycrystalline Yb2SiO5 wafers with precise composition control was evaluated and analyzed by oxygen permeation experiments at high temperatures using an oxygen tracer. Oxygen permeation proceeded due to mutual grain boundary diffusion of oxide ions and Yb ions without synergistic effects such as acceleration or suppression. The oxygen shielding properties of Yb2SiO5 were compared with those of the other line compounds such as Yb2Si2O7 and Al2O3 based on the determined mass transfer parameters. It was found that the more preferentially an oxide ion diffuses in the grain boundary compared to the interior of the grain, the greater the effect of suppressing the movement of the oxide ion by applying an oxygen potential gradient becomes. 相似文献
2.
Hideaki Kaneto Tomohiko Kimura Atsushi Obata Masashi Shimoda Kohei Kaku 《International journal of molecular sciences》2021,22(5)
While there are various kinds of drugs for type 2 diabetes mellitus at present, in this review article, we focus on metformin which is an insulin sensitizer and is often used as a first-choice drug worldwide. Metformin mainly activates adenosine monophosphate-activated protein kinase (AMPK) in the liver which leads to suppression of fatty acid synthesis and gluconeogenesis. Metformin activates AMPK in skeletal muscle as well, which increases translocation of glucose transporter 4 to the cell membrane and thereby increases glucose uptake. Further, metformin suppresses glucagon signaling in the liver by suppressing adenylate cyclase which leads to suppression of gluconeogenesis. In addition, metformin reduces autophagy failure observed in pancreatic β-cells under diabetic conditions. Furthermore, it is known that metformin alters the gut microbiome and facilitates the transport of glucose from the circulation into excrement. It is also known that metformin reduces food intake and lowers body weight by increasing circulating levels of the peptide hormone growth/differentiation factor 15 (GDF15). Furthermore, much attention has been drawn to the fact that the frequency of various cancers is lower in subjects taking metformin. Metformin suppresses the mechanistic target of rapamycin (mTOR) by activating AMPK in pre-neoplastic cells, which leads to suppression of cell growth and an increase in apoptosis in pre-neoplastic cells. It has been shown recently that metformin consumption potentially influences the mortality in patients with type 2 diabetes mellitus and coronavirus infectious disease (COVID-19). Taken together, metformin is an old drug, but multifaceted mechanisms of action of metformin have been unraveled one after another in its long history. 相似文献
3.
Machine Learning - We consider the problem of learning a binary classifier from only positive and unlabeled observations (called PU learning). Recent studies in PU learning have shown superior... 相似文献
4.
Joon‐Young Jun Sosuke Nakajima Koji Yamazaki Yuji Kawai Hajime Yasui Yasuyuki Konishi 《International Journal of Food Science & Technology》2015,50(4):871-877
Cystoseira hakodatensis is an unutilised brown algae belonging to family Sargassaceae. A crude methanol extract from the algae showed inhibitory effects on the growths of Bacillus cereus and Bacillus licheniformis. To isolate the major antimicrobial agent, a sequential active‐guided isolation procedure was applied: liquid–liquid extraction, column chromatography and bio‐autography. A marked antimicrobial agent (active α) was isolated in hydrophobic fraction and was determined to phenolics without carbohydrates and proteins by phytochemical test. Regarding the antimicrobial potential, the isolated active α showed better inhibitory effects against B. cereus and B. licheniformis at 2 and 4 times of lower concentrations (62.5 and 31.3 μg mL?1) in comparison with epigallocatechin gallate. These results showed that C. hakodatensis is a potential source of antimicrobial agent capable of preventing the growth of the two bacteria. 相似文献
5.
Toshihiko Kujime Soong-Keun Hyun Hideo Nakajima 《Metallurgical and Materials Transactions A》2006,37(2):393-398
A lotus-type porous carbon steel with cylindrical pores was fabricated by the continuous zone melting method in a pressurized
mixture of hydrogen and helium gases. The porosity increases with increasing partial pressure of the hydrogen gas, while the
pore diameter remains almost constant, independent of the pressure. The ultimate tensile strength of the specimen with cylindrical
pores parallel to the tensile direction is lower than the estimated value, assuming that the strength is decreased in proportion
to the decrease of the cross-sectional area of the specimen, while the yield strength is higher than the estimated value.
The compressive yield strength is also higher than the estimated value. The increase in yield strength is considered to be
due to precipitation strengthening. The tensile strength is increased by quenching and tempering, while the elongation decreases.
Such mechanical properties are discussed in terms of the microstructural analysis. 相似文献
6.
Improved visible-light responsive photocatalytic activity of N and Si co-doped titanias 总被引:1,自引:0,他引:1
Thermal reaction of titanium tetraisopropoxide and tetraethyl orthosilicate in 1,4-butanediol afforded nanocrystalline silica-modified
titanias having large surface area and superior thermal stability. In this study, the thus-obtained silica-modified titanias
were treated in an NH3 flow at high temperatures, and their physical and photocatalytic properties were investigated. Compared with NH3-treated TiO2 without silica modification, the NH3-treated silica-modified titanias showed a stronger absorption in the visible region (400–500 nm) and had a larger peak at
396 eV in the N 1s XPS spectrum. These results indicate that a larger amount of nitrogen was stably doped in the silica-modified
titania. The obtained products exhibited a high photocatalytic activity for degradation of Rhodamine B and decomposition of
acetaldehyde under visible light irradiation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
7.
Hideo Sawada Hiroshi Kakehi Masashi Koizumi Yoshihiro Katoh Masashi Miura 《Journal of Materials Science》2007,42(17):7147-7153
Fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomer [RF-(DOBAA)
n
-RF] reacted with tetraethoxysilane (TEOS) and silica nanoparticles in the presence of low-molecular weight biocides such as
hibitane, hinokitiol, and hinokioil under alkaline conditions to afford RF-(DOBAA)
n
-RF/silica nanocomposites-encapsulated these biocides in excellent to moderate isolated yields. Fluoroalkyl end-capped N,N-dimethylacrylamide oligomer [RF-(DMAA)
n
-RF] and acrylic acid oligomer [RF-(ACA)
n
-RF]/silica nanocomposites-encapsulated hibitane were obtained under similar conditions. Dynamic light scattering measurements
showed that the size of these fluorinated nanocomposites-encapsulated biocides thus obtained is nanometer size-controlled.
Additionally, these fluorinated nanocomposites were shown to have a good dispersibility and stability in methanol and water.
Of particular interest, these fluorinated nanocomposites-encapsulated biocides were found to have a good antibacterial activity
against Staphylococcus aureus, and these nanocomposites were applied to the surface modification of traditional organic polymers such as poly(methyl methacrylate). 相似文献
8.
Dopaminergic blocking agents have been known to suppress intracranial self-stimulation, but whether the suppression results from a reduction in the rewarding value of stimulation or from motor deficits has remained controversial. We have resolved this controversy by developing an operant technique minimally dependent on motor activity; rats were trained to perform a bar-holding response for 3s or to produce hippocampal theta waves for 3s when the bar was retracted. Decamethonium bromide (a muscle relaxant) reduced bar holding without affecting theta production for brain stimulation. Pimozide (a dopaminergic blocking-agent) reduced both bar holding and theta production for stimulation, though rats were still capable of making the theta response at a rate comparable to the preinjection rate. Dopaminergic blocking at low doses reduces the rewarding value of brain stimulation at the level of the lateral hypothalamus. The method described in this report has wide applicability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Manabu Iguchi Tsuneo Kondoh Keiji Nakajima 《Metallurgical and Materials Transactions B》1997,28(4):605-612
The establishment time of gas-liquid two-phase flows in a cylindrical bath agitated by bottom gas injection through a central
single-hole bottom nozzle was investigated. Because the turbulence intensity in the bath was comparable to or larger than
the unity, the conventional definition of the flow establishment time based on the history of mean velocity was not suitable
for the present case. In fact, it was difficult to determine the flow establishment time based on the well-known 90 or 99
pct criterion for the mean velocity. Accordingly, two methods of determining the flow establishment time by focusing on the
turbulence components instead of the mean velocity components were proposed. Velocity measurements were made with a two-channel
laser Doppler velocimeter. The flow establishment time was correlated as a function of gas flow rate. Close agreement was
obtained by the two methods. 相似文献
10.
Noda K. Tatsumi T. Uchida T. Nakajima K. Miyamoto H. Chenming Hu 《Electron Devices, IEEE Transactions on》1998,45(4):809-814
A simple fabrication technology for delta-doped MOSFETs, named post-low-energy implanting selective epitaxy (PLISE) is presented. The PLISE technology needs no additional photo-lithography mask, deposition step or etching step even for CMOS devices. The only additional step is growing undoped epitaxial channel layers by UHV-CVD after the channel implantation. With this technology, delta-doped NMOSFETs with 0.1-μm gate length were successfully fabricated. By optimizing the epi-layer thickness and the channel doping level, short-channel effects are suppressed enough to achieve 0.1-μm gate length. Moreover, the junction capacitance at zero bias is reduced by 50% 相似文献