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Effects of loading conditions on the fatigue failure characteristics in a polycarbonate
Okayasu, Mitsuhiro,Yano, Kei,Shiraishi, Tetsuro Techno-Press 2014 Advances in materials research Vol.3 No.3
In this study, fatigue properties and crack growth characteristics of a polycarbonate (PC) were examined during cyclic loading at various mean stress (${\sigma}_{amp}$) and stress amplitude (${\sigma}_{mean}$) conditions. Different S vs. N and da/dN vs. ${\Delta}K$ relations were obtained depending on the loading condition. The higher fatigue strength and the higher resistance of crack growth are seen for the PC samples cyclically loaded at the higher mean stress and lower stress amplitude due to the low crack driving force. Non-linear S - N relationship was detected in the examination of the fatigue properties with changing the mean stress. This is attributed to the different crack growth rate (longer fatigue life): the sample loaded at the high mean stress with lower stress amplitude. Even if the higher stress amplitude, the low fatigue properties are obtained for the sample loaded at the higher mean stress. This was due to the accumulated strain energy to the sample, where severe plastic deformation occurs instead of crack growth (plasticity-induced crack closure). Shear bands and discontinuous crack growth band (DGB) are observed clearly on the fracture surfaces of the sample cyclically loaded at the high stress amplitude, where the lower the ${\sigma}_{mean}$, the narrower the shear band and DGB. On the other hand, final fracture occurred instantly immediately after the short crack growth occurs in the PC sample loaded at the high mean with the low ${\sigma}_{amp}$, i.e., tear fracture, in which the shear bands and DGB are not seen clearly.
Iori Kisu,Kouji Banno,Asahi Tokuoka,Keigo Yamaguchi,Kunio Tanaka,Tetsuro Shiraishi,Kanako Nakamura,Hiroshi Senba,Kiyoko Matsuda,Nobumaru Hirao 대한산부인과학회 2022 Obstetrics & Gynecology Science Vol.65 No.3
ObjectiveTransvaginal removal of large specimens during laparoscopic hysterectomy can be a complex surgical procedure thatposes a risk of organ injury and tissue spillage into the abdominal cavity and is associated with extraction of thespecimen and manual morcellation. Our objective was to demonstrate a technique for transvaginal removal of largespecimens using the Alexis Contained Extraction System (CES) in laparoscopic hysterectomy. MethodsThe technique used for transvaginal removal of large specimens using the Alexis CES was presented in this video. Surgery was performed at a tertiary hospital. ResultsFollowing resection of the specimen during laparoscopic hysterectomy, the Alexis CES was inserted into the abdominalcavity through the umbilical trocar wound. The specimen was placed in a bag to prevent tissue spillage. The ringretractor was guided to the vagina and pulled out transvaginally. By repeatedly turning the ring retractor, tensionwas applied to the specimen bag, and the vaginal wall was unfolded all around to enable a secure surgical field. During manual morcellation of the specimen in the bag, the retractor was pulled and additionally turned to roll andre-tension the specimen bag when the bag was loosened. The specimen was pushed out of the vagina and safely andeffectively extracted without concerns about tissue spillage in the abdominal cavity or related organ injuries. ConclusionThe technique for transvaginal removal of large specimens using the Alexis CES enables simple, effective, and safetissue extraction with contained manual morcellation during laparoscopic hysterectomy. 영어
Microstructural characteristics in tough pitch copper for revealing the work hardening region
Okayasu, Mitsuhiro,Taki, Tatsuya,Takasu, Satoshi,Takeuchi, Shuhei,Shiraishi, Tetsuro Techno-Press 2012 Advances in materials research Vol.1 No.4
To reveal localized plastic deformation zones in a tough pitch copper, the etching characteristics of a copper sample have been examined. The etching was carried out on a sample surface using an etchant consisting of 25 ml nitric acid solution and 75 ml water. To clarify the plastic deformation zone, the sample deformed plastically was heated to between $250^{\circ}C$ and $300^{\circ}C$ before the etching process. This is due to a change of the microstructure and crystal orientation in the plastic deformation zone producing recrystallized small grains. In this case, the plastically deformed zone is severely etched, whereas the undeformed zone is only slightly etched. Identification of the details of the deformation zone from the etching is further discussed.
Mechanical and wear properties of Cu-Al-Ni-Fe-Sn-based alloy
Okayasu, Mitsuhiro,Izuka, Daiki,Ninomiya, Yushi,Manabe, Yuki,Shiraishi, Tetsuro Techno-Press 2013 Advances in materials research Vol.2 No.4
To obtain bronze with good mechanical properties and high wear resistance, a new bronze (CADZ) is proposed on the basis of various fundamental information. The CADZ consists of the elements Al10.5, Fe4.2, Sn3.7 and Ni3.1, and its design is based on Cu-Al10.5 alloy. The Cu-10.5%Al is very hard and brittle. To obtain the high material ductility of the Cu-10.5%Al alloy, an attempt was made to add a few percent of Sn. Moreover, to make high strength of the Cu alloy, microstructure with small grains was created by the proper amount of Fe and Ni (Fe/Ni = 0.89). The mechanical properties of the CADZ sample have been examined experimentally, and those were compared with commercial bronzes. The tensile strength and wear resistance of CADZ are higher than those for commercial bronzes. Although the ductility of CADZ is the lower level, the strain to failure of CADZ is about 2.0~5.0% higher than that for the Cu-Al10.5 alloy. Details of the microstructural effects on the mechanical properties in the CADZ sample were further discussed using various experimental results.
( Iori Kisu ),( Hidetaka Nomura ),( Miho Iida ),( Kouji Banno ),( Tetsuro Shiraishi ),( Moito Iijima ),( Kayoko Nakamura ),( Kiyoko Matsuda ),( Nobumaru Hirao ) 대한산부인과학회 2021 Obstetrics & Gynecology Science Vol.64 No.6
Objective The pelvic lymphatic drainage system comprises the upper and lower paracervical pathways (LPPs). Lymph node dissection of the LPP, including the cardinal ligament, internal iliac, internal common iliac, and presacral lymph nodes, requires higher surgical skills because of the anatomical limitations of the pelvic cavity and the dissection of vessels while preserving the nerves in the pelvic floor. In this video, we demonstrate rectal mobilization for laparoscopic complete pelvic lymph node dissection of the LPP in patients with uterine cancer. Methods Rectal mobilization was performed before complete pelvic lymph node dissection of the LPP. The pararectal space was opened widely and the connective tissue between the presacral fascia and prehypogastric nerve fascia was dissected bilaterally, allowing the rectum to be pulled. Results This procedure created a wide-open space in the pelvic floor, allowing clear visualization of the nerves and lymph nodes of the LPP. Laparoscopic complete lymph node dissection of the LPP was performed in the open space while preserving the hypogastric and pelvic splanchnic nerves and isolating the extensive network of blood vessels in the pelvic cavity. Conclusion Rectal mobilization enabled the safe execution of laparoscopic complete pelvic lymph node dissection of the LPP in patients with uterine cancer.