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81.
Yoshihiko Hangai Hiroto Kamada Takao Utsunomiya Soichiro Kitahara Osamu Kuwazuru Nobuhiro Yoshikawa 《Materials》2014,7(3):2382-2394
Al foam has been used in a wide range of applications owing to its light weight, high energy absorption and high sound insulation. One of the promising processes for fabricating Al foam involves the use of a foamable precursor. In this study, ADC12 Al foams with porosities of 67%–78% were fabricated from Al alloy die castings without using a blowing agent by the friction stir processing route. The pore structure and tensile properties of the ADC12 foams were investigated and compared with those of commercially available ALPORAS. From X-ray computed tomography (X-ray CT) observations of the pore structure of ADC12 foams, it was found that they have smaller pores with a narrower distribution than those in ALPORAS. Tensile tests on the ADC12 foams indicated that as their porosity increased, the tensile strength and tensile strain decreased, with strong relation between the porosity, tensile strength, and tensile strain. ADC12 foams exhibited brittle fracture, whereas ALPORAS exhibited ductile fracture, which is due to the nature of the Al alloy used as the base material of the foams. By image-based finite element (FE) analysis using X-ray CT images corresponding to the tensile tests on ADC12 foams, it was shown that the fracture path of ADC12 foams observed in tensile tests and the regions of high stress obtained from FE analysis correspond to each other. Therefore, it is considered that the fracture behavior of ADC12 foams in relation to their pore structure distribution can be investigated by image-based FE analysis. 相似文献
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Kato T Kamata A Nakagawa S Fujisawa R Machida T Ikari S Sasaki K Yamada H Kagaya H Nakamura H Meguro T Horita S 《Nihon Shokakibyo Gakkai zasshi》2012,109(4):615-623
Computed tomography colonography (CTC) was performed in 5 patients with pneumatosis cystoides intestinalis (PCI). The virtual colonoscopy view of CTC as well as total colonoscopy (TCS) findings showed polypoid lesions in the colon, and multiplanar reconstruction images of the colon revealed in the polypoid lesions of the colon. We confirmed the diagnosis of PCI in all cases. CTC also detected the PCI lesions in the subserosa of the colonic wall which were not detected by TCS. Accurate evaluation of the extent of PCI involvement was obtained by CT air-contrast enema images. CTC is useful for detection of PCI lesions, assessment of the exact site and final diagnosis for PCI. 相似文献
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Keiko Tanaka Ryoichi Matsuse Yoshihiro Miyake Takashi Hanioka Masashi Arakawa 《Journal of periodontology》2013,84(12):1724-1729
Background: The authors investigated the relationship between objectively assessed tobacco smoke exposure and periodontal disease. Methods: This cross‐sectional study included 1,103 women with a mean age of 31.5 years. Information on potential confounding factors was obtained through a self‐administered questionnaire. Periodontal disease was defined as positive if a woman had at least one tooth with a probing depth of ≥3.5 mm. Exposure to tobacco smoke was determined based on salivary cotinine concentration. Adjustment was made for age, region of residence, household income, education, toothbrushing frequency, and use of an interdental brush. Results: The prevalence of periodontal disease was 11.3%. Salivary cotinine concentration was independently positively associated with the prevalence of periodontal disease: the adjusted odds ratio for every 1‐unit (ng/mL) increase in salivary cotinine was 1.004 (95% confidence interval: 1.000 to 1.007). Conclusion: Salivary cotinine concentrations were positively associated with the prevalence of periodontal disease among young women. 相似文献
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