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21.
The two-color photorefractive response of near stoichiometric lithium niobate (SLN) doped with Mg above a critical threshold has been investigated. Striking differences as compared with non Mg-doped material were observed: The intermediate level in the two-color writing process has approximately a two orders of magnitude longer lifetime in SLN:Mg than in nominally undoped SLN, the grating is written in a shallower level but can be fixed via a simple thermal process and complementary electron-hole gratings are formed. It is proposed that the Fe impurity level moves from below the small-polaron level in nonMgO-doped material to above it, resulting in the increased lifetime of the small polaron. These changes are associated with a shift of the Fe from a Li site to a Nb site. The two-color sensitivity is higher than in the absence of MgO but the dynamic range is much lower. 相似文献
22.
In view of the increasing incidence and mortality rate of prostate cancer in Japan, the management of elderly patients with prostate cancer is an important issue now. We therefore analyzed the clinicopathological features and long-term outcomes of 182 patients with prostate cancer, aged 75 or older, in order to establish the treatment strategy for this age group of patients. There were more patients with advanced disease (stage C-D) than those with localized disease (stage A2-B), and the patients with moderate to poorly differentiated tumors were more numerous than those with well-differentiated tumors. The overall survival curve of the patients with localized prostate cancer was in line with the age-matched expected survival curve, while that with advanced prostate cancer was far below the expected survival curve. These results demonstrated that advanced prostate cancer in elderly patients is as harmful as in younger patients, indicating the necessity for early detection and treatment of prostate cancer among the younger generation. On the other hand, localized prostate cancer in elderly patients should be treated less invasively to maintain their quality of life. 相似文献
23.
This paper presents a finite strip analysis of curved composite girders with incomplete interaction. In the present analysis curved composite girder bridges are modelled by curved strip elements for the concrete slab and steel girder and spring elements for the shear connectors. The shear connectors are assumed as a two-dimensional spring element along the nodal line. The proposed method is applied to the analysis of curved box girders, curved plates and curved composite girder bridges with complete and incomplete interaction. Some analytical results obtained by this method are compared with the test results and theoretical values obtained by other methods, and they are in good agreement. Slip behavior of curved composite box girders is also discussed based on the results by the proposed method. 相似文献
24.
Shimizu T Miyahayashi Y Yokoo M Hoshino Y Sasada H Sato E 《Reproduction (Cambridge, England)》2004,128(5):537-543
Growth differentiation factor-9 (GDF-9) is a growth factor secreted by oocytes in growing ovarian follicles. To investigate the ovarian function of GDF-9 in pigs, we first cloned porcine GDF-9 complementary DNA (cDNA), and then injected its gene fragments into the ovary in gilts. Porcine GDF-9 has open reading frame (ORF) homologies of 81.4%, 84.6%, 84.2%, 72.7% and 72.6% with its human, bovine, ovine, rat and mouse counterparts respectively. Regarding the deduced amino-acid sequence of the mature protein, the corresponding homologies reach 92.1%, 97.8%, 97.0%, 89.6% and 88.1% respectively. To investigate the role of GDF-9 in early folliculogenesis, the ovaries of 2-month-old prepubertal gilts were injected with GDF-9 gene fragments. The injection of porcine GDF-9 gene fragments resulted in an increase in the number of primary, secondary and tertiary follicles, concomitant with a decrease in the number of primordial follicles. These results indicated that exogenous GDF-9 can promote early folliculogenesis in the porcine ovary, and that a technique for direct ovarian injection of GFD-9 gene fragments may contribute to a novel therapy for prevention and treatment of infertility associated with ovarian dysfunction. 相似文献
25.
Kenji M. Kojima Shin-ichi Uchida Yasunori Fudamoto Setsuko Tajima 《Journal of Low Temperature Physics》2003,131(5-6):775-779
Josephson plasma reflectivity edge in YBa2Cu3O6.6 (T
c=59 K) was measured in parallel magnetic fields HCuO2 up to 7 T. Upon application of the field, the Josephson plasma edge splits to two reflectivity edges, forming a new peak at finite frequency. Optical conductivity obtained by Kramers–Kronig analysis indicates that a new transverse Josephson plasma mode appears under parallel fields. We propose that the new mode originates from the modulation of the insulating layers with and without Josephson vortices, as has been suggested by free-energy calculations of Josephson vortices with moderate densities. 相似文献
26.
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28.
Bong Mo Park Kenji Kitamura Yasunori Furukawa Yangyang Ji 《Journal of the American Ceramic Society》1997,80(10):2689-2692
The relationships between cracking and mechanical twinning, and between ferroelectric polarization and mechanical twinning, in stoichiometric LiNbO3 were investigated in the present study. Three sets of mechanical twins crossed one another, and the crossed points of those twins provided preferred sites for the nucleation of cracks. Mechanical twins of LiNbO3 revealed a head-to-tail arrangement of ferroelectric polarization, and complicated polarization states were observed at the crossed points. Some possible mechanisms of crack nucleation and propagation are proposed in this paper. 相似文献
29.
CdS/CuInSe2 (CIS) heterojunctions were investigated by XPS analysis. An In-excess layer which may form an ordered vacancy compound (OVC) was present at the as-deposited CIS surface and it remained after chemical bath deposition of a CdS layer. The In-excess layer was removed by preferential etching with NH3 aqueous solution. This result implies that the surface of the as-deposited CIS film was converted from the OVC with n-type conductivity into the CIS with p-type by NH3 treatment. The conduction band offsets at the CdS/p-CIS and CdS/n-OVC were determined to be 1.0 and 0.3 eV, respectively. The CIS solar cells fabricated with n-OVC surface layer exhibited higher cell efficiencies than those fabricated with p-CIS surface layer. 相似文献
30.
Yasunori Imada Takafumi Shido Ryuichiro Ohnishi Kiyoshi Isobe Masaru Ichikawa 《Catalysis Letters》1996,38(1-2):101-108
SiO2-impregnated complete and incomplete cubane-type molybdenum oxide clusters such as [(RhCp*)4Mo4O16] (I) and [(RhCp*)2Mo3O9(OMe)4] (II) were photoreduced with a UHP-Hg lamp (> 365 nm) in CO, resulting in the formation of catalytically active species for propene metathesis at 300 K. The CO-photoreduced Mo oxide clusters were characterized by EXAFS, IR, XPS and TPD technique. The results suggest that the Mo-O4c (four-centered bridging oxygens) in I were specifically reduced with CO under the illumination to produce two sets of subcarbonyl species, e.g., those characteristic of the IR bands at 2061 and 2021 cm–1, which were thermally inactive for the13CO exchange reaction but very active under illumination at 300 K, possibly assignable to Mo(CO)x (x = 2, 3), whereas those at 2092 and 2035 cm–1 due to Rh(CO)2, which were readily exchangeable with13CO at 300 K in dark. Removal of both carbonyls attached on Rh and Mo in photoreduced I and II by evacuation at 375–440 K led to the formation of oxygen-deficient Mo4+/Mo5+ sites, which exhibited high catalytic activities in propene metathesis at 300 K to produce an equimolar mixture of ethene and 2-butenes. The CO-photoreduced incomplete cubane Mo oxide cluster (II) exhibited higher activities and higher trans/cis ratios of 2-butenes in the reaction, compared with those on the photoreduced I. 相似文献