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61.
H. Sabet K. Ishii S. Matsuyama Y. Kikuchi K. Nakazawa A. Esmaili Torshabi H. Yamazaki 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2009,600(3):678-682
A new method to modify coordinates of detectors in any positron emission tomography (PET) system using a radioactive point source is developed. This method is based on selecting a centered detector in each detector block of PET and measuring coincidence counts between the two centered detectors in opposite detector blocks to find the coordinates of their LOR (Line of Response). Due to slight misalignment of detector positions, measured LORs may not intersect at a single point. Based on the proposed method, the coordinates of detectors can be measured with very high accuracy and the coordinate of the center of the gantry (which is normally the same as the center of field of view) can be defined correctly. The results of the application of our method to a small animal PET system (FinePET), which was recently developed at Tohoku University, Japan, are shown here. The method is expected to contribute to the design and development of PET systems which can realize a very high spatial resolution of less than 1 mm FWHM. 相似文献
62.
Koh Matsumoto Kazutada Ikenaga Jun Yamamoto Kazuki Naito Yoshiki Yano Akinori Ubukata Hiroki Tokunaga Tadanobu Arimura Katsuaki Cho Toshiya Tabuchi Akira Yamaguchi Yasuhiro Harada Yuzaburo Ban Kousuke Uchiyama 《半导体学报》2011,32(1):21-23
Growth rate has a direct impact on the productivity of nitride LED production.Atmospheric pressure growth of GaN with a growth rate as high as 10μm/h and also Al0.1Ga0.9N growth of 1μm/h by using 4 inch by 11 production scale MOVPE are described.XRD of(002) and(102) direction was 200 arcsec and 250 arcsec, respectively.Impact of the growth rate on productivity is discussed. 相似文献
63.
Noriya Izu Haruo Kishimoto Takahisa Omata Kousuke One 《Science and Technology of Advanced Materials》2013,14(2):397-404
Tetragonal CaF2-related-type t′-/Ce0.5Zr0.5)O2 phase was reduced at 773 K ≤ Tred. ≤ 1073 K to prepare precursors with various oxygen compositions: Ce2Zr2O712d /0.111 < δ < 0.379). Metastable tetragonal t′meta-(Ce0.5Zr0.5)O2 phases were prepared by oxidizing in O2 at 873 K the precursors, and subjected to evolved oxygen gas analysis by heating the samples at a constant rate. When the precursor was prepared at Tred: ? 773 K; i.e. δ ? 0:379; the oxygen release behavior of the tetragonal phase agreed approximately with that of the t′. For δ < 0.29, distinct features of the t′meta-(Ce0.5Zr0.5)O2 appeared in the XRD results and Raman spectra. The temperature exhibiting the maximum release rate of oxygen from the t′meta became lower with decreasing the d value. It could be concluded that the thermodynamic behavior of the t′meta is related closely to the precursor composition and becomes more unstable with decrease in the δ value. The t′ and t′meta phases with disordered arrangement of Ce and Zr ions may belong to the same space group; nevertheless, difference in the random arrays of the Ce and Zr ions was suggested on the basis of the present experimental results. 相似文献
64.
The block copolymers consisting of 2,7-dimethoxycarbazole- and oxadiazole-containing segments as hole and electron transporting units, respectively, were synthesized by NMRP manner. OLED devices were fabricated using block copolymer, random copolymer, and polymer blend for matrix of the emitting layer with Ir(ppy)3 as a phosphorescent dopant in order to investigate morphological effect on the performance. From the finding that the block copolymer system overwhelmed the others in EQE, we assumed that a morphology with dimethoxycarbazole units assembled to the surface of PEDOT:PSS played a considerable role for effective recombination of charges as well as sufficient charge injection into the emitting layer. 相似文献
65.
Kenichi Kikuchi Yasunori Fujii 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(10):1205-1211
Performances of 640-GHz Superconductor–Insulator–Superconductor (SIS) mixers developed for the Superconducting Submillimeter-Wave
Limb-Emission Sounder (SMILES) mission are described. SMILES, launched in September 2009, is the first mission to observe
atmosphere from space using superconducting mixers. Ground test performances of the SIS mixers show very flat gain and noise
characteristics in their observation bands in compliance with the specifications required for SMILES. 相似文献
66.
Yasushi Sekine Haruka Takamatsu Sho Aramaki Kazuki Ichishima Mitsuko Takada Masahiko Matsukata Eiichi Kikuchi 《Applied Catalysis A: General》2009,352(1-2):214-222
The water gas shift (WGS) reaction over Pt and Pd catalysts supported on various perovskite oxides has been investigated at 573 K without catalyst pretreatment. The Pt and Pd catalysts on LaCoO3 support showed high catalytic activity. Interaction between Pt or Pd and the support is considered to promote the WGS reaction: Pt/LaCoO3 had high initial activity but deactivated immediately; Pd/LaCoO3 was less active than Pt/LaCoO3, but had superior stability. Catalysts were characterized using XRD, STEM, XPS, and H2-temperature programmed reduction (TPR). Results of this study showed that reduction of the support decreased the CO conversion on Pt/LaCoO3. On the other hand, Pd/LaCoO3 showed stable activity for the WGS reaction. Therefore, Pd was added to Pt/LaCoO3 for stabilizing the catalyst activity, and 0.5 wt.% Pd/1 wt.% Pt/LaCoO3 catalyst showed higher activity and stability. 相似文献
67.
Yoshiaki Kikuchi Takeshi Nagatome Taka-aki Mizutani Hiroyuki Yoshino 《Soils and Foundations》2011,51(1):151-165
Cement-treated clay with air foam, which is called Super Geo-Material (SGM), was developed to utilize dredged clay in an effective way. As SGM is mainly used at levels below the ground water table, water permeability and absorption properties of SGM will affect the durability of the material. In this research, the changes in SGM permeability and absorption as functions of the air foam fraction were investigated. First, permeability tests with triaxial apparatus and constant rate of consolidation tests were conducted on samples containing less than 10% of air foam by volume. From the results, air foam was found to be an impermeable medium in SGM. Secondly, a series of permeability tests and absorption tests were conducted for the SGM with different fractions of air foam while observing the specimen with a micro focus X-ray Computed Tomography (CT) scanner. The results showed that the permeability of SGM increased dramatically due to the appearance of interior water channels when the air foam fraction exceeded 30% by volume. The density distribution change and water absorbed zones of the specimens during absorption tests were estimated using the X-ray CT data. From these results, the air in the SGM was found to be progressively substituted with water from the surface to the inside of the specimen and the substituted zone expanded as it made its way to the specimen interior. The expansion velocity of the substituted zone was not affected by the coefficient of permeability but by the fraction of the air in the specimen. 相似文献
68.
Matsui T Matsumura K Hagisawa K Ishihara M Ishizuka T Suzuki M Kurita A Kikuchi M 《IEEE transactions on bio-medical engineering》2002,49(6):621-623
The purpose of this study is to investigate the vascular wall with a thermally self-regulating, cylindrical stent made of a low Curie temperature ferromagnetic alloy. Physiologic saline was circulated in the silicone model vessel implanted with the stent. The stent-temperature remained nearly constant for variable saline flows, saline temperatures, and magnetic flux densities. Stent implants of this type in human blood vessels could potentially enable thermotherapy and temperature determination without catheterization. 相似文献
69.
Steroid cyclophanes, each having a macrocyclic ring attached to four bile acid moieties via chiral lysine connectors, were synthesized, and the binding of the 2-naphthylphenylketone (guest) to the steroid cyclophanes in water was investigated. The circular dichroism spectra of the steroid cyclophane with cholic acid and L-lysine were significantly affected by the binding of the guest, and the induced circular dichroism based on the absorption of the achiral guest was also observed. The binding of the guest to the steroid cyclophane with cholic acids and D-lysines induced changes in the circular dichroism spectra with the opposite sign of the molecular ellipticities. An induced circular dichroism spectral change was not observed upon binding of the guest to the analogous host without OH sites. These results strongly suggest that the guest is conformationally fixed through hydrogen bonding between the carbonyl group of the guest and the steroidal hydroxyl group of the host. The assembly of only four steroid residues on the macrocyclic ring probably provided a hydrophobic nanocavity for hydrogen bonding. 相似文献
70.
The effect of the dispersing procedure on the aggregate size, membrane fluidity and the pharmacokinetics were evaluated for the lipid A analog E5531. The size of the aggregates prepared by the pH-jump method (pH 11.0 → 7.3) was decreased, reaching 20 nm with increasing dispersing time in 0.003 N NaOH (pH 11.0). The membrane fluidity of the aggregates increased with increasing dispersing time. When prepared by the normal dilution method (pH 7.3 → 7.3), the size of the aggregates remained constant at 150 nm and the membrane fluidity was smaller compared to samples prepared by the pH-jump method. Using samples with different degrees of hydration and different membrane fluidities prepared by the pH-jump method, the pharmacokinetics after intravenous administration into rats were evaluated, and the data obtained confirmed that the membrane fluidity was correlated with the pharmacokinetics in rat. In addition, E5531 vials were stable for 24 months at room temperature when used within 24 hr after reconstitution. 相似文献