Anomalous thermal expansion in a CuAl2-type superconductor CoZr2

In this work, we show that the CuAl2-type superconductor CoZr2 and alloyed systems exhibit anomalous thermal expansion in a wide temperature range. We performed neutron powder diffraction and X-ray powder diffraction on CoZr2 and observed remarkably anisotropic thermal expansion with a c-axis negative thermal expansion constant of {\alpha}c < -15 {\mu}K-1 in a wide temperature range of T = 50-573 K. With decreasing temperature, the lattice constant a decreases, while the lattice constant c continuously increases in CoZr2. The origin of the anisotropic shrinkage/expansion of the a-axis/c-axis by cooling is explained by the small change in the Co-Zr bond and the systematic decrease in the Zr-Co-Zr angle. Similar thermal expansion was observed in alloyed systems, (Fe,Co,Ni)Zr2 and (Fe,Co,Ni,Rh,Ir)Zr2, which suggests that the phenomenon is common feature in the TrZr2 system. We propose that zero-thermal expansion metals would be achieved by optimizing the contrasting thermal expansion of a-axis and c-axis in TrZr2.Comment: 17 pages, 5 figures, supplementary dat

Usefulness of a Flexible Port for Natural Orifice Transluminal Endoscopic Surgery by the Transrectal and Transvaginal Routes

We developed a flexible port for NOTES which allows the use of conventional forceps for laparoscope-assisted surgery without change. The port is not affected by the location of the through hole in the gastrointestinal tract or vagina which elicits a problem in conventional NOTES, and its length can be adjusted during surgery by cutting the port itself. The port is made of polymer resin with a low friction coefficient. Furthermore, the port walls have a square wave structure which contributes to (1) the prevention of devices, for example, endoscope, from getting stuck at the time of insertion and retrieval, (2) the prevention of port slippage in the surgical opening for port insertion, (3) the prevention of unexpected port removal, (4) the prevention of port bore deformation, and (5) the improvement of port flexibility in the longitudinal direction. We validated the insertion and retrieval capacities of commercially available forceps for laparoscope-assisted surgery and power devices. Furthermore, we used the flexible port to conduct cholecystectomy and partial gastrectomy. We could confirm that the selection of the flexible port diameter according to the device type allowed the smooth insertion and retrieval of the device and that the port produced no air leakage. We affirmed that it is possible to conduct surgery by the cross or parallel method similarly to single port surgery. We considered that the flexible port has a potential of becoming a revolutionary port in NOTES

Dependency of tensile strength of ductile cast iron on strain rate and temperature

The dependency of the tensile strength σ smooth B and the notch strength σ notch B on strain rate and temperature were investigated for conventional ferrite-pearlite type ductile cast iron (JIS-FCD500) to make clear the applicability of ductile cast iron to components for welded steel structures. High speed tensile tests were conducted on notched and smooth specimens with varying strain rate and temperature. Charpy absorbed energy was also evaluated on notched specimen with varying temperature. It is found that the tensile strength is in a good relationship with strain rate-temperature parameter R for the wide range of strain rate and temperature. With decreasing R parameter, both σ smooth B and σ notch B increase even when Charpy absorbed energy starts decreasing. It should be noted that the notch strength σ notch B is always larger than the tensile strength at room temperature σ smooth B, RT in the range of R parameter required for the welded structures. Therefore, the tensile strength σ smooth B, RT is confirmed to be useful for the structural design.12th International Conference on Damage Assessment of Structures, 10–12 July 2017, Kitakyushu, Japa

Conditions for notch strength to be higher than static tensile strength in high–strength ductile cast iron

In this study, notch strength σ B notch was studied for a wide range of testing speed and temperature in comparison with the static tensile strength at room temperature σ B, RT smooth. High–speed tensile tests were conducted on high–Si ductile cast iron, conventional ferrite–pearlite ductile cast iron, and fully pearlitic ductile cast iron at a stroke speed ranging between 8.5 × 10−3–2.7 × 102 mm/s (strain rate of 2.1 × 10−4–1.8 × 101 s−1) and temperature ranging between −180°C–22°C. Then, σ B notch and σ B,RT smooth were compared in terms of the strain rate–temperature parameter R = T ln (A/ ) to evaluate the combined influence of the strain rate and temperature T. It was found that the notch strength σ B notch can be expressed as a unique master curve in terms of R parameter for each material. Then, a notch–strengthening threshold criterion R ≧ Rth was proposed to describe the lowest service temperature and highest strain rate that can be applied to the structural components. Under the condition R ≧ Rth, σ B notch is always larger than σ B,RT smooth , and therefore, notched components can be used safely. In other words, if R ≧ Rth, σ B,RT smooth can be used to evaluate the notched components in machine design to prevent instantaneous fractures

Potential role of group X secretory phospholipase A2 in cyclooxygenase-2-dependent PGE2 formation during colon tumorigenesis

AbstractAlthough the cyclooxygenase-2 (COX-2) pathway of the arachidonic acid cascade has been suggested to play an important role in colon carcinogenesis, there is little information concerning the identity of phospholipase A2 (PLA2) involved in the arachidonic acid release in colon tumors. Here, we compared the potencies of three types of secretory PLA2s (group IB, IIA and X sPLA2s) for the arachidonic acid release from cultured human colon adenocarcinoma cells, and found that group X sPLA2 has the most powerful potency in the release of arachidonic acid leading to COX-2-dependent prostaglandin E2 (PGE2) formation. Furthermore, immunohistological analysis revealed the elevated expression of group X sPLA2 in human colon adenocarcinoma neoplastic cells in concert with augmented expression of COX-2. These findings suggest a critical role of group X sPLA2 in the PGE2 biosynthesis during colon tumorigenesis

Plexiform neurofibroma in the hepatic hilum associated with neurofibromatosis type 1: a case report

We present an extremely rare case of plexiform neurofibroma involving the hepatic hilum. A 24-year old woman who had been diagnosed with neurofibromatosis type 1 was referred to our hospital for evaluation of an abdominal mass found on computed tomography and progressive aggravation of intermittent abdominal pain. Abdominal computed tomography revealed a multilobulated non-enhancing mass involving the celiac trunk and hepatic artery, that extended to the hepatic hilum through the hepatoduodenal ligament. Magnetic resonance imaging showed the lesion extending along the intrahepatic Glisson's sheath. Based on the imaging findings, the patient was diagnosed to have a neu-rofibroma, although sarcomatous differentiation could not be excluded. The tumor was resected, leaving behind the intrahepatic extension, with the aim of alleviating the abdominal pain and preventing obstructive jaundice. Histopathological examination revealed the diagnosis of plexiform neurofibroma. At present, three years after the surgery, the patient remains symptom-free, without any evidence of recurrence

Malignant Triton tumor in the retroperitoneal space associated with neurofibromatosis type 1: a case study

We report an extremely rare case of malignant Triton tumor developing in the retroperitoneal space in a patient with neurofibromatosis type 1. A 21-year old man who had been diagnosed with neurofibromatosis type 1 was admitted to our hospital with the chief complaint of a palpable abdominal mass. Abdominal computed tomography revealed a huge heterogeneous tumor measuring approximately 17 cm in diameter occupying the left retroperitoneal space, and numerous metastatic lesions between the left psoas muscle and the left thigh with dissolution of the left hip joint. After the diagnosis of a retroperitoneal malignant neurogenic tumor, resection of the tumor with reconstruction of the abdominal aorta was conducted, followed by postoperative transarterial infusion chemotherapy. The histopathological diagnosis was malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation, namely malignant Triton tumor. Postoperative chemotherapy was in vain and the patient died 14 months after the surgery as a result of lung metastasis