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Five rolling contact fatigue tests, Tests {1}-{5} have been conducted. In Tests {1}{3}, when a fatigue crack was initiated on the surface of a follower, the test was halted. Then, in Test {1} the rotating direction was reversed. In Test {2} the follower and driver were interchanged, and in Test {3} the test was continued unchanged. In Test {3} the original crack grew to a pit. In Tests {1} and {2} the original crack immediately stopped propagating. In Tests {4} and {5}, mating with a harder roller, a softer roller was used as the follower in Test {4} and as the driver in Test {5}. A typical pit occurred in Test {4}. In Test {5}, surface damage substantially different from a typical pit was generated. Based on these experimental results, a 3-D crack analysis including the effect of frictional force on the contact surface and oil hydraulic pressure on crack surfaces, was conducted to elucidate the mechanisms of pit formation and surface damage in contact fatigue.

The fatigue limit diagram provides the critical condition of non-failure against fatigue under constant amplitude loading. The fatigue limit diagram is usually considered to give the allowable stress if every stress component is kept within the fatigue limit diagram. In the case of variable amplitude fretting fatigue, however, this study showed that fatigue failure could occur even when all stresses were within the fatigue limit diagram. An example of such a condition is a repeated two-step loading such as when the first step stress is R=−1 and the second step stress has a high mean value. The reason why such a phenomenon occurs was investigated. A non-propagating crack was formed by the first step stress even when well below the fatigue limit. The resultant non-propagating crack functioned as a pre-crack for the second step stress with a high mean value. Consequently, fatigue failure occurred even when every stress was within the fatigue limit diagram of constant amplitude loading. The fatigue limit diagram obtained in constant amplitude fatigue test does not necessarily guarantee safety in the case of variable amplitude loading in fretting fatigue. [ABSTRACT FROM AUTHOR]

ABSTRACT Fatigue tests on material containing small defects were performed under a wide range of mean stress for three grades of steels with different hardness. The ΔK th of small defects had a peculiar dependency on material hardness and mean stress, which was quite different from those of long cracks or plain specimens. The crack closure of short cracks was measured. It was shown that the formation of the crack closure was affected by the material hardness and mean stress. This behaviour of crack closure resulted in characteristic fatigue limit properties of materials containing small defects. [ABSTRACT FROM AUTHOR]

Presents information pertaining to the study of experimental and fracture mechanics regarding the pit formation mechanism under repeated lubricated rolling-sliding contact. Consideration of the mechanism of pit formation; Reference to five rolling contact tests.

Aim: This quality Improvement study evaluated the applicability of our protocol for early-onset severe pre-eclampsia, prepared in April 2013., Methods: We collected data from all women with early-onset severe pre-eclampsia treated at our hospital between March 2008 and August 2015. Neonatal and maternal outcomes were compared between protocol-based (n = 17) and non-protocol-based management groups (n = 28)., Results: The latency period was significantly longer in the protocol-based than in the non-protocol-based group (21.9 ± 3.7 vs 11.0 ± 2.9 days). Gestational age at delivery was significantly more advanced in the protocol-based than in the non-protocol-based group (31.4 ± 0.6 vs 29.8 ± 0.4 weeks). Serious neonatal complications were significantly less prevalent in the protocol-based than in the non-protocol-based group (26% vs 79%). Among the protocol components, magnesium sulfate use was the only independent factor contributing to the absence of serious neonatal complications. The percentages of women exhibiting persistent proteinuria or hypertension at one, two and three months post-partum were similar between the groups., Conclusions: Strict adherence to our protocol improved neonatal outcomes without affecting maternal prognosis. Routine use of magnesium sulfate could be the most important component of the protocol., (© 2017 Japan Society of Obstetrics and Gynecology.)

Objective: To assess the applicability of trial of labor in cases of low-lying placenta., Methods: In this observational cohort study, we collected data from the women with low-lying placenta delivered at our hospital between April 2012 and December 2015. Low-lying placenta was diagnosed when the length from the placental lowest edge to the internal cervical os (placenta-os distance) was 0-20 mm at 36 gestational weeks. Planned mode of delivery for each case was determined by patient's preference. Maternal and neonatal outcomes were compared between the planned vaginal delivery group (N = 11) and the planned cesarean delivery group (N = 7)., Results: All the women in the planned cesarean delivery group underwent scheduled cesarean section at 37-38 gestational weeks. Three cases in the planned vaginal delivery group required emergency cesarean section for uncontrollable antepartum bleeding. The intrapartum blood loss was significantly smaller in the planned vaginal delivery group than in the planned cesarean delivery group (946 ± 204 g vs. 1649 ± 256 g, p = 0.047). Umbilical arterial blood pH was similar between the two groups. All the women requiring emergency cesarean section were accompanied by marginal sinus., Conclusions: Trial of labor can be offered to all the women with low-lying placenta except for those accompanied by marginal sinus.

Objective: To identify suitable diagnostic tools and evaluate the efficacy of sentinel lymph node (SLN) biopsy for inguinal lymph node metastasis in vulvar cancer., Methods: Data from 41 patients with vulvar cancer were evaluated retrospectively, including magnetic resonance imaging (MRI) measurements, SLN biopsy status, groin lymph node metastasis, and prognosis., Results: SLN biopsy was conducted in 12 patients who had stage I to III disease. Groin lymphadenectomy was omitted in five of the nine patients with negative SLNs. All SLN-negative patients who did not undergo groin lymphadenectomy showed no evidence of disease after treatment. On MRI, the long and short diameters of the inguinal node were significantly longer in metastasis-positive cases, compared with negative cases, in 25 patients whose nodes were evaluated pathologically (long diameter, 12.8 mm vs. 8.8 mm, p=0.025; short diameter, 9.2 mm vs. 6.7 mm, p=0.041). The threshold of >10.0 mm for the long axis gave a sensitivity, specificity, positive predictive value, and negative predictive value of 87.5%, 70.6%, 58.3%, and 92.3%, respectively, using a binary classification test. Decision tree analysis revealed a sensitivity, specificity, and accuracy of 87.5%, 70.6%, and 76.0%, respectively, with the threshold of >10.0 mm for the long axis on MRI. The criteria of >10.0 mm for the long axis on MRI predicted an advanced stage and poorer prognosis using a validation set of 15 cases (p=0.028)., Conclusion: Minimally invasive surgery after preoperative evaluation on MRI and SLN biopsy is a feasible strategy for patients with vulvar cancer., Competing Interests: No potential conflict of interest relevant to this article was reported.