Toughening of Low-Alloy Steel by Ultrafine-Grained Structure (Development of Fracture Control from Microstructure Design)

Microstructural design for improving the strength–toughness balance was studied in low-alloy steel. Medium-carbon steel bars with microstructures of two types such as an ultrafine elongated grain (UFEG) structure and an ultrafine equiaxed grain (UFG) structure were fabricated by multi-pass warm caliber rolling and subsequent annealing. Conventionally, quenched and tempered steel with a martensitic structure and low-carbon steel with a ferrite–pearlite structure were also prepared. The tensile and three-point bending tests were conducted for all samples. In particular, the fracture behavior after the bending test was observed in detail and investigated, including the effect of microstructure features. As a result, the strength–toughness balance of the UFEG steel was excellent compared with that of all other steels. The present results provide useful guidelines for designing microstructure to improve the strength–toughness balance in metallic materials

Unawareness of a Prolonged Retained Capsule Endoscopy: The Importance of Careful Follow-Up and Cooperation between Medical Institutions

A 50-year-old man with anemia was referred to our hospital to undergo capsule endoscopy (CE), which revealed small intestinal ulcers. After 5 months of CE, he returned because of recurrent anemia without abdominal symptoms. Abdominal X-ray and computed tomography showed capsule retention in the small intestine at the pelvic cavity. The capsule remained at the same place for 7 days. We performed capsule retrieval by laparoscopy-assisted surgery with resection of the involved small intestine, including an ileal stricture. Resected specimen showed double ulcers with different morphologies, an ulcer scar with stricture, and a wide ulcer at the proximal side of the others. Each ulcer had different histopathological findings such as the degree of fibrosis and monocyte infiltration. These differences led us to consider that the proximal ulcer may have been secondarily induced by capsule retention. Our experience indicated that careful follow-up and the cooperation between medical institutions after CE examination should be undertaken for patients with incomplete examination, unknown excretion of the capsule, and/or ulcerative lesions despite the lack of abdominal symptoms. Additionally, a retained CE remaining over long periods and at the same place in the small intestine may lead to secondary ulceration