Singular stress field near the edge of interface of bonded dissimilar materials with an interlayer

AbstractFor bonded dissimilar materials, the free-edge stress singularity usually prevails near the intersection of the free-surface and the interface. When two materials are bonded by using an adhesive, an interlayer develops between the two bonded materials. When a ceramic and a metal are bonded, the residual stress develops because of difference in the coefficient of thermal expansion. An interlayer may be inserted between the two materials to defuse the residual stress. Stress field near the intersection of the interface and free-surface in the presence of the interlayer is then very important for evaluating the strength of bonded dissimilar materials.In this study, stress distributions on the interface of bonded dissimilar materials with an interlayer were calculated by using the boundary element method to investigate the effect of the interlayer on the stress distribution. The relation between the free-edge singular stress fields of bonded dissimilar materials with and without an interlayer was investigated numerically. It was found that the influence of the interlayer on the stress distributions was confined within a small area of the order of interlayer thickness around the intersection of the interface and the free-surface when the interlayer was very thin. The stress distribution near the intersection of the interface and the free-surface was controlled by the free-edge stress singularity of the bonded dissimilar materials without the interlayer. In this case, the interlayer can be called free-edge singularity-controlled interlayer. If a stress distribution on the interface is known for one thickness of an interlayer h, stress distributions on the interface for other values of h can be estimated

Molecular carcinogenesis of squamous cell carcinomas of the skin

Squamous cell carcinomas (SCCs) of the skin were suggested to develop through a multistep process that involves activation of proto-oncogenes and/or inactivation of tumor suppressor genes in the human skin keratinocytes. Exposure to ultra-violet (UV), especially UV-B, radiation is the most common cause for these genetic abnormalities in cells. We review causation of SCCs and genetic abnormalities in human SCCs with the current work. To elucidate the multistep process, we developed a method for examining the combinatorial function in vivo of plural genes in human keratinocytes. Using high efficiency retroviral transductions, we could express plural genes serially in normal human primary keratinocytes and use these cells to regenerate human skin on SCID mice. A combinatorial transduction of H-RasV12 and cyclin dependent kinase 4 (CDK4) produced human epidermal neoplasia resembling SCC. These findings were consistent with our previous results of mutation analysis in SCCs, one of which had both mutations of H-Ras gene and the INK4a locus. Therefore, it is suggested that a combination of these genetic abnormalities might be crucial to the carcinogenesis at least in a subset of SCCs

コウレイシャ ノ ヒフ シュヨウ

Skin tumors in aged patients consist of benign tumors, precancerous lesions or carcinomas in situ, and skin cancers. We reviewed the clinical characteristic and treatment for each of them, and the molecular pathogenesis and protection for skin cancers. Exposure to ultra-violet (UV) radiation is the most common cause of skin cancers. In particular, UV-B radiation is mainly involved in the mutagenesis in the skin by two major photoproducts of a cyclobutane pyrimidine dimer and a (6-4) photoproduct. Recently, the ozone layer of the earth has been destroyed, and the increase in UV-B radiation on the earth surface can be expected in the next years. Therefore, we should add special attention to patients with skin cancers that are predicted to increase in number, and UV protection by sunscreens from childhood should be essential for the prevention against skin cancers in the 21st century

Comparison among Various Expressions of Complex Admittance for Quantum System in Contact with Heat Reservoir

Relation among various expressions of the complex admittance for quantum systems in contact with heat reservoir is studied. Exact expressions of the complex admittance are derived in various types of formulations of equations of motion under contact with heat reservoir. Namely, the complex admittance is studied in the relaxation method and the external-field method. In the former method, the admittance is calculated using the Kubo formula for quantum systems in contact with heat reservoir in no external driving fields, while in the latter method the admittance is directly calculated from equations of motion with external driving terms. In each method, two types of equation of motions are considered, i.e., the time-convolution (TC) equation and time-convolutionless (TCL) equation. That is, the full of the four cases are studied. It is turned out that the expression of the complex admittance obtained by using the relaxation method with the TC equation exactly coincides with that obtained by using the external-field method with the TC equation, while other two methods give different forms. It is also explicitly demonstrated that all the expressions of the complex admittance coincide with each other in the lowest Born approximation for the systemreservoir interaction. The formulae necessary for the higher order expansions in powers of the system-reservoir interaction are derived, and also the expressions of the admittance in the n-th order approximation are given. To characterize the TC and TCL methods, we study the expressions of the admittances of two exactly solvable models. Each exact form of admittance is compared with the results of the two methods in the lowest Born approximation. It is found that depending on the model, either of TC and TCL would be the better method.Comment: 34pages, no figur

Reduction of total E2F/DP activity induces senescence-like cell cycle arrest in cancer cells lacking functional pRB and p53

E2F/DP complexes were originally identified as potent transcriptional activators required for cell proliferation. However, recent studies revised this notion by showing that inactivation of total E2F/DP activity by dominant-negative forms of E2F or DP does not prevent cellular proliferation, but rather abolishes tumor suppression pathways, such as cellular senescence. These observations suggest that blockage of total E2F/DP activity may increase the risk of cancer. Here, we provide evidence that depletion of DP by RNA interference, but not overexpression of dominant-negative form of E2F, efficiently reduces endogenous E2F/DP activity in human primary cells. Reduction of total E2F/DP activity results in a dramatic decrease in expression of many E2F target genes and causes a senescence-like cell cycle arrest. Importantly, similar results were observed in human cancer cells lacking functional p53 and pRB family proteins. These findings reveal that E2F/DP activity is indeed essential for cell proliferation and its reduction immediately provokes a senescence-like cell cycle arrest

Contents of the Digital Natural History Museum of Hiroshima University, especially in the field of biology

広島大学デジタル自然史博物館は，広島大学の開学以来長年にわたって蓄積された教育・研究に関する知的資産を外部に公開し，生涯学習や学校教育のために活用することを目的として設置されている。デジタル自然史博物館には生物学や地学とそれに関係する資料が含まれる。特徴のあるコンテンツとしてはコケ植物や世界遺産宮島に関するものがあげられる。コンテンツの大部分は日本語であり，アクセス数は2015年度以降増加傾向にある。今後，現在進めているMediaWiki を使ったシステムへの移行を進めるとともに，コンテンツの充実やICT を使った学習への対応，運用母体の強化などを通じて，教育・研究のためだけでなく地域貢献のためのリソースとして発展させる計画である。The Digital Natural History Museum of Hiroshima University is a cluster of web sites for dissemination and practical use of educational and research resources for lifelong learning as well as school education in collaboration with laboratories and centers of Hiroshima University, Japan. The museum site includes contents on biological, environmental and earth sciences, mainly in Japanese with some English, especially bryophytes and the world heritage listed Itsukushima (Miyajima) Island, Hiroshima Prefecture, Japan. Online site access has increased since 2015. The museum site is now transferring the html based system to the MediaWiki system which is a free and open-source wiki software. For regional studies we plan to expand significantly the content of available resources to enable greater use and ease of access through information and communication technology (ICT)