Plastic Deformation of Bicrystals composed of <100>, <111>, and Single Glide Oriented Aluminum Crystals

When two crystal grains having large different deformation-modes are adjacent to each other, their compatibility at the boundary plane becomes extremely confused. Therefore, it is thought that such a grain boundary condition plays an important role on several phenomena of the materials containing it. In this study, three kinds of bicrystals composed of two crystals within three kinds of single crystals (a common single crystal for single glide, a single crystal with tensile orientation and a single crystal with tensile orientation), are prepared and tested by tension. The additional slips on {110} are activated, and the boundary strength is positive in the bicrystals composed of a crystal for single glide and a crystal with tensile orientation. In the bicrystals composed of a crystal for single glide and a crystal with tensile orientation, a few clustered slips occur from the grain boundary in the grain with tensile orientation. The boundary strength is negative. Some micro-cracks are observed along the grain boundary of bicrystals composed of a crystal with tensile orientation and a crystal with tensile orientation. The boundary strength is found to be zero

Plastic Deformation of <111> Oriented Aluminum Single Crystals

It is known that an aluminum single crystal having tensile orientation shows an initial rapid hardening, and that its flow stress increases gradually until failure. However, many problems pertaining to the deformation mechanism of the oriented single crystal remain unsolved. In the present study, to clarify the deformation mode of aluminum single crystals having multiple slip orientations, tensile test were performed at various temperatures on oriented single crystals. At room temperature, the oriented single crystal deformed only by fine multiple slips, and the flow stress increased with an increase of strain until failure. On the other hand, the coarse wavy slips composed of {111} and {100} slips occurred at high temperatures, such as 473K. In the single crystal having a tensile orientation deviated from by a few degrees, the clustered slips were observed in addition to the fine multiple slips. It is concluded that the deformation mode and flow stress of the single crystal are very sensitive to the tensile oriention in the vicinity of

Effect of Deformation Temperature on the Stage IV Deformation in <100> Oriented Aluminum Single Crystal

It is known that at room temperature the tensile stress-strain curve of an aluminum single having tensile orientation becomes flat after about a two percent elongation. (This flat region of the stress-strain curve is named Stage IV). In the previous paper, the propagation of a clustered slip accompanied by a prominent cross slip was observed in the Stage IV region of curve. In the present study, oriented aluminum single crystals were tested in tension at various temperatures so as to clarify the influence of temperature on the deformation mechanisms in Stage IV. At 203K, a few clustered slip lines accompanied by a prominent cross slip occurred, but they did not propagate in the entire region of the specimen. The stress-strain curve became flat only from about a ten percent elongation. In the crystal stretched at 77K, the cluster did not propagate at all from either end of the specimen, and so the stress-strain curve did not become flat. On the other hand, a wavy coarse slip was observed and the curve became flat from about a 0.5 percent elongation at 473K. It was suggested that these wavy slip lines were produced by a frequent repetition of the cross slip on two {111} planes and also possidly on a {110} plane having the same slip direction. It was confirmed that the occurrence of Stage IV is caused by the of the clustered slip accompanied by a prominent cross slip, and is much influenced by the temperature of deformation due to the easiness of the cross slip

Effect of Grain Boundary on Pseudo-elastic Deformation of Cu-Zn-Si Bicrystal of Shape Memory Alloy

Two sorts of Cu-Zn-Si pseudo-elastic bicrystals of shape memory alloy were tested in tension to know the effects of the grain boundary. The remaining martensites were observed in the vicinity of the grain boundary, and the propriety of analyses through use of m/m。 and Nᵢj values and of the compatibility of the plastic strain were studied. The variant of martensite occurring primarily in each grain during deformation, can be predicted with use of them value (shear factor of the variant) in general. The analyses through use of m/mᵢ and Nᵢj values and the equations of the plastic strain compatibility are sufficiently useful to know the variant of martensite nucleated additionally in the vicinity of the grain boundary. However, the possibility of activation of slip must be considered in this case. The reversible strain of the isoaxial bicrystal is larger than that of the non-isoaxial bicrystal. However, the relation between the reversible strain and the misorientation of bicrystal is not yet sufficiently known

Carbon- and nitrogen-centered radicals produced from l-lysine by radiation-induced oxidation: A pulse radiolysis study

Radical species generated from the reactions of a basic amino acid, l-lysine (Lys), with hydroxyl radicals (OH) and sulfate radical anion (SO4-) have been detected by the method of pulse radiolysis. On the basis of electron transfer reactivities toward tetranitromethane (TNM), it was demonstrated that reducing carbon-centered radicals are generated as a result of hydrogen abstraction from CH2 of Lys with a G-value of 1.9 × 10−7 mol J−1. On the other hand, direct oxidation of l-Lys by SO4- formed a transient species with different spectroscopic properties, most likely, the ε-N-centered Lys radical

Severe Impairment in Early Host Defense against Candida albicans in Mice Deficient in Myeloperoxidase

Myeloperoxidase (MPO) catalyzes the reaction of hydrogen peroxide with chloride ion to produce hypochlorous acid (HOCl), which is used for microbial killing by phagocytic cells. Despite the important role of MPO in host defense, however, MPO deficiency is relatively common in humans, and most of these individuals are in good health. To define the in vivo role of MPO, we have generated by gene targeting mice having no MPO activity in their neutrophils and monocytes. The mice without MPO developed normally, were fertile, and showed normal clearance of intraperitoneal Staphylococcus aureus. However, they showed increased susceptibility to pneumonia and death following intratracheal infection with Candida albicans. Furthermore, the lack of MPO significantly enhanced the dissemination of intraperitoneally injected C. albicans into various organs during the first 7 days. Thus, MPO is important for early host defense against fungal infection, and the inability to generate HOCl cannot be compensated for by other oxygen-dependent systems in vivo in mice. The mutant mice serve as a model for studying pulmonary and systemic candidiasis

Dietary Patterns and Their Associations with Intermediate Age-Related Macular Degeneration in a Japanese Population

This population-based cross-sectional study investigated the influence of dietary patterns on age-related macular degeneration (AMD) in a Japanese population. The Tsuruoka Metabolomics Cohort Study enrolled a general population aged 35&ndash;74 years from among participants in annual health check-up programs in Tsuruoka City, Japan. Eating habits were assessed using a food frequency questionnaire. Principal component analysis was used to identify dietary patterns among food items. The association between quartiles of scores for each dietary pattern and intermediate AMD was assessed using multivariate logistic regression models. Of 3433 participants, 415 had intermediate AMD. We identified four principal components comprising the Vegetable-rich pattern, Varied staple food pattern, Animal-rich pattern, and Seafood-rich pattern. After adjusting for potential confounders, higher Varied staple food diet scores were associated with a lower prevalence of intermediate AMD (fourth vs. first quartile) (OR, 0.63; 95% confidence interval [CI], 0.46&ndash;0.86). A significant trend of decreasing ORs for intermediate AMD associated with increasing Varied staple food diet scores was noted (p for trend = 0.002). There was no significant association between the other dietary patterns and intermediate AMD. In a Japanese population, individuals with a dietary pattern score high in the Varied staple food pattern had a lower prevalence of intermediate AMD