Effect of Texture of AZ31 Magnesium Alloy Sheet on Mechanical Properties and Formability at High Strain Rate

The mechanical properties and formability of AZ31 magnesium alloy strips having different textures were investigated at a high strain rate based on that occuring in mass production by press forming. Forming at a high strain rate on the order of 10 0 s À1 requires a high temperature of over 473 K. To obtain accurate stress-strain curves, a high-speed testing machine that can maintain a constant true strain rate was used, and the change in gauge length on a test piece in a furnace was measured during the testing time of about 0.5 s. For the specimens, rolled strips consisting of fine grains (about 10 mm) and an extruded strip consisting of coarse grains (about 40 mm) were used. The {0001} textures of the extruded strip and one of the rolled strips were strongly oriented parallel to the rolled surface, but the texture of another rolling strip had two peaks that were inclined at 5 $15 deg in front of and behind the rolling direction. At the high strain rate of 10 0 s À1 , elongation decreased for every specimen. Nevertheless, a limiting drawing ratio (LDR) of 2:1$ 2:2 was obtained under uniform heating above 503 K in all the specimens except for the extruded strip. The high LDR of the rolled strip having a two-peak texture was maintained in forming at temperatures down to 473 K, in contrast to the LDR of the strongly oriented rolled strip, which reduced rapidly when formed at temperatures less than 503 K

Tensile Properties and Press Formability of a Mg-9Li-1Y Alloy Sheet *

The formability of an experimentally produced Mg-9%Li-1%Y alloy sheet with a thickness of 0.6 mm is investigated. Uniaxial tension tests and some fundamental press-forming tests, such as stretching, deep-drawing, and bore-expanding tests, are carried out at room temperature. The sheet has sufficiently high ductility under uniaxial tension. However, ductility decreases with an increase in strain rate. Even at room temperature, the flow stress is also sensitive to the strain rate. The stress and the work-hardening rate increase with the strain rate. The strain rate sensitivity affects the formability in press forming. The critical punch stroke in the stretching test decreases with an increase in punch speed. However, the limit drawing ratio increases with the punch speed due to the increase in the work-hardening rate. The Erichsen value is estimated to be 9 mm, and the limit drawing ratio is 2.15. It may be concluded that the sheet has sufficiently high formability

Malignant Potential of Gastrointestinal Cancers Assessed by Structural Equation Modeling

<div><p>Background</p><p>Parameters reported in pathologic reviews have been failing to assess exactly the malignant potential of gastrointestinal cancers. We hypothesized that malignant potential could be defined by common latent variables (hypothesis I), but there are substantial differences in the associations between malignant potential and pathologic parameters according to the origin of gastrointestinal cancers (hypothesis II). We shed light on these issues by structural equation modeling.</p><p>Materials and Methods</p><p>We conducted a cross-sectional survey of 217 esophageal, 192 gastric, and 175 colorectal cancer patients who consecutively underwent curative surgery for their pathologic stage I cancers at Keiyukai Sapporo Hospital. Latent variables identified by factor analysis and seven conventional pathologic parameters were introduced in the structural equation modeling analysis.</p><p>Results</p><p>Because latent variables were disparate except for their number, 'three' in the examined gastrointestinal cancers, the first hypothesis was rejected. Because configural invariance across gastrointestinal cancers was not approved, the second hypothesis was verified. We could trace the three significant paths on the causal graph from latent variables to lymph node metastasis, which were mediated through depth, lymphatic invasion, and matrilysin expression in esophageal cancer, whereas only one significant path could be traced in both gastric and colorectal cancer. Two of the three latent variables were exogenous in esophageal cancer, whereas one factor was exogenous in the other gastrointestinal cancers. Cancer stemness promoted viability in esophageal cancer, but it was suppressed in others.</p><p>Conclusion</p><p>These results reflect the malignant potential of esophageal cancer is higher than that of the other gastrointestinal cancers. Such information might contribute to refining clinical treatments for gastrointestinal cancers.</p></div

Characteristics of the study population.

<p>Characteristics of the study population.</p

SEM of gastric cancer.

<p>Circles indicate unobserved latent variables, while rectangles represent observed variables. Yellow indicates a dependent endogenous variable and grey indicates an independent exogenous variable. Significant paths with their estimated parameter are shown by solid lines, while insignificant paths are shown by broken lines (Fig 2). Rred arrows represent either a negative causal effect or measurement errors within the model. The blue triangle in the center suggests that the malignant potential includes three latent variables. Coefficient of determination is written as R². Abbreviations: v, vascular invasion; ly, lymphatic invasion; n, lymph node metastasis; hist, histological grade.</p

SEM of colorectal cancer.

<p>Circles indicate unobserved latent variables, while rectangles represent observed variables. Yellow indicates a dependent endogenous variable and grey indicates an independent exogenous variable. Significant paths with their estimated parameter are shown by solid lines, while insignificant paths are shown by broken lines (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0149327#pone.0149327.g002" target="_blank">Fig 2</a>). Red arrows represent either a negative causal effect or measurement errors within the model. The blue triangle in the center suggests that the malignant potential includes three latent variables. Coefficient of determination is written as R². Abbreviations: v, vascular invasion; ly, lymphatic invasion; n, lymph node metastasis; hist, histological grade.</p

Malignant potential of each GI cancer type.

<p>Malignant potential of each GI cancer type.</p

SEM of esophageal cancer.

<p>Circles indicate unobserved latent variables, while rectangles represent observed variables. Yellow indicates a dependent endogenous variable and grey indicates an independent exogenous variable. Significant paths with their estimated parameter are shown by solid lines, while insignificant paths are shown by broken lines (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0149327#pone.0149327.g002" target="_blank">Fig 2</a>). Rred arrows represent either a negative causal effect or measurement errors within the model. The blue triangle in the center suggests that the malignant potential includes three latent variables. Coefficient of determination is written as R². Abbreviations: v, vascular invasion; ly, lymphatic invasion; n, lymph node metastasis; hist, histological grade.</p