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排序方式: 共有143条查询结果,搜索用时 46 毫秒
41.
Tetsuya Hosaka 《Topology and its Applications》2006,153(11):1860-1866
H.S.M. Coxeter showed that a group Γ is a finite reflection group of an Euclidean space if and only if Γ is a finite Coxeter group. In this paper, we define reflections of geodesic spaces in general, and we prove that Γ is a cocompact discrete reflection group of some geodesic space if and only if Γ is a Coxeter group. 相似文献
42.
We study the low-lying scalar mesons of light u, d, s flavors in the QCD sum rule. Having all possible combinations of tetraquark currents in the local form, QCD sum rule analysis has been carefully performed. We found that using the appropriate tetraquark currents, the masses of σ, κ, f0 and a0 mesons appear in the region of 0.6–1 GeV with the expected ordering. The results are compared with that of the conventional currents, where the masses are considerably larger. 相似文献
43.
Masafumi?IdeEmail author Akira?Suguro Yasushi?Hosaka Atsushi?Katsunuma Kouzou?Takahashi Atsushi?Shiraishi 《Optical Review》2004,11(2):132-139
We apply liquid crystal on silicon (LCOS) in 0.8-$mUm standard complementary metal-oxide semiconductor (CMOS) technology to demonstrate a low-cost, high-performance pixelized liquid crystal variable optical attenuator (VOA) with pulse width modulation. We then build a prototype tunable filter by using this VOA along with a grating in the Littrow configuration. With the application of 5-V pulse width modulation, the proposed VOA achieves a 5.6-dB insertion loss, a dynamic range of more than 20 dB, a 50-GHz channel spacing capability, and a polarization-dependent loss (PDL) of less than 0.6 dB at 15-dB attenuation. Our VOA is suitable for applications such as dynamic channel gain equalizers, channel-blocking filters, sub-components of re-configurable add-drop modules, and wavelength selectors. 相似文献
44.
45.
Nishida H Miyazaki Y Mukaihira T Saitoh F Fukui M Harada K Itoh M Muraoka A Matsusue T Okamoto A Hosaka Y Matsumoto M Ohnishi S Mochizuki H 《Chemical & pharmaceutical bulletin》2002,50(9):1187-1194
Intravascular clot formation is an important event in a number of cardiovascular diseases. The prevention of blood coagulation has become a major target for new therapeutic agents. Factor Xa (FXa) is a trypsin-like serine protease that plays a key role in the blood coagulation cascade and represents an attractive target for anticoagulant drug development. We have investigated substituents in the central part of a lead compound (3: M55113), and discovered that compound M55551 (34: (R)-4-[(6-Chloro-2-naphthalenyl)sulfonyl]-6-oxo-1-[[1-(4-pyridinyl)-4-piperidinyl]methyl]-2-piperazinecarboxylic acid) is a potent inhibitor of FXa (IC(50)=0.006 microM), with high selectivity for FXa over trypsin and thrombin. The activity of this compound is ten times more powerful than the lead compound. 相似文献
46.
Mirai Ohara A. Shahul Hameed Kei Kubota Akihiro Katogi Kuniko Chihara Tomooki Hosaka Shinichi Komaba 《Chemical science》2021,12(37):12383
K-ion batteries (KIBs) are promising for large-scale electrical energy storage owing to the abundant resources and the electrochemical specificity of potassium. Among the positive electrode materials for KIBs, vanadium-based polyanionic materials are interesting because of their high working voltage and good structural stability which dictates the cycle life. In this study, a potassium vanadium oxide phosphate, K6(VO)2(V2O3)2(PO4)4(P2O7), has been investigated as a 4 V class positive electrode material for non-aqueous KIBs. The material is synthesized through pyrolysis of a single metal–organic molecular precursor, K2[(VOHPO4)2(C2O4)] at 500 °C in air. The material demonstrates a reversible extraction/insertion of 2.7 mol of potassium from/into the structure at a discharge voltage of ∼4.03 V vs. K. Operando and ex situ powder X-ray diffraction analyses reveal that the material undergoes reversible K extraction/insertion during charge/discharge via a two-phase reaction mechanism. Despite the extraction/insertion of large potassium ions, the material demonstrates an insignificant volume change of ∼1.2% during charge/discharge resulting in excellent cycling stability without capacity degradation over 100 cycles in a highly concentrated electrolyte cell. Robustness of the polyanionic framework is proved from identical XRD patterns of the pristine and cycled electrodes (after 100 cycles).Highly pure K6(VO)2(V2O3)2(PO4)4(P2O7), synthesized from the oxalatophosphate precursor, demonstrates a reversible potassium extraction/insertion capacity of 59 mA h g−1 with a single discharge voltage plateau at 4.0 V at room temperature. 相似文献
47.
Controlled ring‐opening polymerization of l‐lactide and ε‐caprolactone catalyzed by aluminum‐based Lewis pairs or Lewis acid alone
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Yuushou Nakayama Shunsuke Kosaka Kentaro Yamaguchi Gentaro Yamazaki Ryo Tanaka Takeshi Shiono 《Journal of polymer science. Part A, Polymer chemistry》2017,55(2):297-303
Ring‐opening polymerization of cyclic esters was studied using catalysts composed of bulky Lewis acids (LA) and Lewis bases (LB). Controlled polymerization of l ‐lactide (l ‐Lac) was proceeded by Al(C6F5)3·THF in combination with trimesitylphosphine (Mes3P) or triphenylphosphine (Ph3P) using BnOH as an initiator to produce poly(l ‐Lac) with narrow molecular weight distribution (MWD; Mw/Mn = 1.1). Both the LA and the LB were indispensable to promote the polymerization. The molecular weights of the resulting poly(l ‐Lac)s were controlled by the feed monomer to initiator ratio. ε‐Caprolactone (CL) was rapidly polymerized by Al(C6F5)3·THF with or without Mes3P, although the resulting polymer had rather broad MWD (Mw/Mn = 1.7). The CL polymerization by Al(C6F5)3·THF alone at r.t. gave poly(CL) with relatively narrow MWD (Mw/Mn = 1.2). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 297–303 相似文献
48.
Silylation Improves the Photodynamic Activity of Tetraphenylporphyrin Derivatives In Vitro and In Vivo
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Prof. Hiroaki Horiuchi Prof. Masahiro Hosaka Hiroyuki Mashio Motoki Terata Prof. Shintaro Ishida Prof. Soichiro Kyushin Prof. Tetsuo Okutsu Prof. Toshiyuki Takeuchi Prof. Hiroshi Hiratsuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(20):6054-6060
The effects of silyl and hydrophilic groups on the photodynamic properties of tetraphenylporphyrin (TPP) derivatives have been studied in vitro and in vivo. Silylation led to an improvement in the quantum yield of singlet oxygen sensitization for both sulfo and carboxy derivatives, although the silylation did not affect other photophysical properties. Silylation also improved the cellular uptake efficiency for both sulfo and carboxy derivatives, enhancing the in vitro photodynamic activity of the photosensitizer in U251 human glioma cells. The carboxy derivative (SiTPPC4) was found to show higher cellular uptake efficiency and in vitro photodynamic activity than the corresponding sulfo derivative (SiTPPS4), which indicates that the carboxy group is a more promising hydrophilic group than the sulfo group in the silylated porphyrin. SiTPPC4 was found to show high selective accumulation efficiency in tumors, although almost no tumor selectivity was observed for the nonsilylated porphyrin. The concentration of SiTPPC4 in tumors was 13 times higher than that in muscle 12 h after drug administration. We also studied tumor response after treatment and found that silylation enhanced in vivo photodynamic activity significantly. SiTPPC4 shows higher photodynamic activity than NPe6 with white light irradiation. 相似文献
49.
We demonstrate high-resolution fluorescence imaging of single molecules using near-field scanning optical microscopy (NSOM)
with a tiny aperture probe for two different wavelengths in visible range in the illumination mode of operation. The spatial
resolutions obtained at both excitation wavelengths were almost the same and the highest resolution realized was about 10
nm. To discuss the achievable resolution in aperture NSOM, we also employed a computer simulation by the finite-difference
time-domain method for various aperture sizes and wavelengths. The resolution of 10 nm is predicted to be contributed by the
single peak of localized near-field light around the rim of the aperture. 相似文献
50.
Y. Kondo T. Chiba J. Ariake K. Taguchi M. Suzuki M. Takagaki N. Kawamura B.M. Zulfakri S. Hosaka N. Honda 《Journal of magnetism and magnetic materials》2008
We developed a micro-magnetometry with a 2.5 μm spatial resolution based on micro X-ray magnetic circular dichroism (XMCD) technique in order to study magnetic properties of dot arrays for bit-patterned media. This micro-magnetometer was applied to the magnetic characterization of Co–Pt dot arrays fabricated by ion beam etching. As the dot size became small, the intensity of XMCD drastically decreased for dots fabricated by Ga-focused ion beam. This suggested that the dot edges were damaged magnetically by implantation of Ga ions. The damaged width of the dot edge was estimated to be about 13 nm from the decrease in XMCD intensities. This damaged edge width agreed with the ion-implanted area estimated by Monte-Carlo simulation. The less-damaged effect of Ar ion etching was verified by the XMCD measurement of Co–Pt dots with diameter of 20 and 70 nm. It was concluded that ions with inertness, lower energy and smaller atomic number should be used to fabricate dot arrays with an areal density of 1 Tbit/in2. 相似文献