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排序方式: 共有2358条查询结果,搜索用时 31 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.
Noriyuki Wada Jyoji Hanai Mikiya Furukawa Kazuo Kojima 《Journal of the American Ceramic Society》2019,102(8):4621-4631
To make a Mn2+-doped red glass phosphor that can be excited with ultraviolet (UV) light of light-emitting diodes (LEDs), 60P2O5-35ZnO-5Al2O3-8MnO-xCu2O glasses (x = 0-1.00) were prepared by a melt-quenching method at 1200-1400°C for 30-180 minutes in atmospheric air, and the redox of Mn and Cu as well as fluorescence properties were investigated. The Mn2+ ion was not reduced and oxidized in the melting, quenching, and annealing processes. The valence of Cu in the glasses changed in the order of 0, 1+, and 2+ with the increase in the amount of Cu2O and in the melting temperature and time. In this study, a 60P2O5-35ZnO-5Al2O3-8MnO-0.10Cu2O glass melted at 1250°C for 90 minutes, having the highest Cu+ concentration, showed the strongest Mn2+ red fluorescence under the UV light at 275 nm. This strong Mn2+ red fluorescence has been caused by the energy transfer from excited Cu+ ions to Mn2+ ions. 相似文献
4.
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
5.
A multipath structure of a ring resonator is proposed to expand the free spectral range. Simulation work indicates that the multipath ring resonator has 25 GHz-adjacent-channel crosstalk of -41 dB, maximum interchannel crosstalk of -18 dB, and -1 dB bandwidth of 4 GHz for a typical expansion factor of 10. The results show the advantages of characteristics compared with a double-cavity ring resonator and a triple-coupler ring resonator. 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.
Ureteral obstruction enhances eicosanoid production in cortical and medullary tubules of rat kidneys
We examined prostaglandin (PG) E2, 6-keto PGF1alpha, and thromboxane B2 (TxB2) production in cortical and medullary tubules from sham-operated control (SOC) rats and rats with bilateral ureteral obstruction (BUO) of 24 h duration. In SOC rats medullary tubules produced significantly greater amounts of the three eicosanoids than cortical tubules. Again, the production of PGE2, 6-keto PGF1alpha, and TxB2 by cortical and medullary tubules was significantly greater in BUO rats than in SOC rats. To elucidate the mechanisms involved, we examined the activity of phospholipase A2 (PLA2) reactive against phosphatidylcholine or phosphatidylethanolamine (PE), the activity of phospholipase C (PLC), and the levels of cyclooxygenase (COX) in cortical and medullary tubules from SOC and BUO rats. In SOC rats the activity of phosphatidylcholine-PLA2 and PE-PLA2, the activity of PLC, and the mass of COX were significantly greater in medullary tubules than in cortical tubules. On the other hand, the activity of PLC in membranes of cortical tubules and the activity of PE-PLA2 and PLC in membranes of medullary tubules, which were in active location, were significantly greater in BUO rats than in SOC rats. COX levels were also significantly greater in cortical and medullary tubules of BUO rats than in those of SOC rats. Thus, we indicate that medullary tubules from SOC rats have greater production of eicosanoids through increased activity of the PLA2 and PLC-COX pathway than cortical tubules from the same group of rats. Again, in rats with BUO, the tubular eicosanoid production may be enhanced via activation of the PLC-COX pathway in cortical tubules or through activation of the PE-PLA2 and PLC-COX pathway in medullary tubules. The enhanced production of tubular eicosanoids observed in rats with BUO may affect tubular function, particularly sodium and water reabsorption. 相似文献
9.
10.
Masashi Morishita 《Journal of Low Temperature Physics》2007,148(5-6):761-765
Heat capacities of a submonolayer 3He solid film adsorbed on a graphite surface are measured in magnetic fields up to 400 Oe. The measured heat capacity shifts
to higher temperatures with an increasing magnetic field. The amplitudes of the shifts are twenty times larger than the magnitude
of the Zeeman energy, which is anomalously large. With regard to the origin of these large shifts, the reduction of frustrations
and the weakening of the competition between multiple spin exchange interactions are discussed. 相似文献