Effect of grain refinement on hydrogen embrittlement behaviors of high-Mn TWIP steel

Hydrogen embrittlement behaviors of a high-Mn TWIP (twinning induced plasticity) steel with various grain sizes from coarse grains to ultra-fine grains were studied by hydrogen pre-charging and subsequent slow stain rate tensile tests. The results of the tensile tests showed that the yield strength and tensile strength were not influenced by hydrogen-charging, whereas the total elongation reduced with hydrogen-charging in coarse-grained specimen but no change in the ultrafine-grained specimen. Fracture surfaces showed dimple patterns in all specimens. The present results suggested that the grain refinement suppressed hydrogen embrittlement in the high-Mn TWIP steel, even though the diffusible hydrogen content increased by grain refinement

Propylthiouracil Is Teratogenic in Murine Embryos

Background: Hyperthyroidism during pregnancy is treated with the antithyroid drugs (ATD) propylthiouracil (PTU) and methimazole (MMI). PTU currently is recommended as the drug of choice during early pregnancy. Yet, despite widespread ATD use in pregnancy, formal studies of ATD teratogenic effects have not been performed. Methods: We examined the teratogenic effects of PTU and MMI during embryogenesis in mice. To span different periods of embryogenesis, dams were treated with compounds or vehicle daily from embryonic day (E) 7.5 to 9.5 or from E3.5 to E7.5. Embryos were examined for gross malformations at E10.5 or E18.5 followed by histological and micro-CT analysis. Influences of PTU on gene expression levels were examined by RNA microarray analysis. Results: When dams were treated from E7.5 to E9.5 with PTU, neural tube and cardiac abnormalities were observed at E10.5. Cranial neural tube defects were significantly more common among the PTU-exposed embryos than those exposed to MMI or vehicle. Blood in the pericardial sac, which is a feature indicative of abnormal cardiac function and/or abnormal vasculature, was observed more frequently in PTU-treated than MMI-treated or vehicle-treated embryos. Following PTU treatment, a total of 134 differentially expressed genes were identified. Disrupted genetic pathways were those associated with cytoskeleton remodeling and keratin filaments. At E 18.5, no gross malformations were evident in either ATD group, but the number of viable PTU embryos per dam at E18.5 was significantly lower from those at E10.5, indicating loss o