20 research outputs found

    Effects of local stress, strain, and hydrogen content on hydrogen-related fracture behavior in low-carbon martensitic steel

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    International audienceThe present study investigated the hydrogen-related fracture behavior of specimens with different stress concentration factors through microstructure observation, finite element (FE) simulation, and digital image correlation (DIC) analysis. The alloy studied was a simple model alloy (Fe-0.2C binary alloy) with fully martensite structure. When the hydrogen content was large (2.21 mass ppm (121 at ppm)), the crack initiation and propagation occurred along the prior austenite grain boundaries. Through the FE simulations, we found that the crack initiation sites corresponded to the region with high stress and high hydrogen content. Although the stress concentration factors were different, the stress level and the hydrogen content at the crack initiation sites were almost the same, indicating that the hydrogen-related intergranular fracture originated from stress-controlled decohesion at the prior austenite grain boundaries. For the specimen with small hydrogen content (0.41 mass ppm (22.5 at ppm)), the quasi-cleavage cracks formed at the surface of the notch root and propagated along the {011} planes. The FE simulations revealed that the plastic strains were maximum at the initiation sites of the quasi-cleavage cracks. Moreover, we confirmed that hydrogen enhanced the local plastic deformation by DIC analysis. As the local values of maximum principal stress, plastic strain, and hydrogen content at the initiation sites of the quasi-cleavage cracks were different depending on the stress concentration factor, the critical quantitative condition for the initiation of quasi-cleavage cracking was not simple compared to that of the case of intergranular cracking

    Guidelines for managing conscientious objection to blood transfusion

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    Parents sometimes deny their children blood transfusion because of their religious beliefs. The Japanese Joint Committee on the Refusal of Blood Transfusion on Religious Grounds asserts that the health and life of every child under 15 years of age should be guarded by the collective efforts of health, welfare and advocacy institutions when a parent or guardian seeks to withhold transfusion therapy. Patients 18 years or older should receive treatment without transfusion after signing and submitting a "Certificate of Refusal Blood Transfusion and Exemption from Liability". For a patient younger than 18, but 15 years or older, essential transfusion can be performed if the patient or at least one guardian consents. Without patient or guardians consent, guidelines for patients 18 years or older shall apply. Healthcare providers should offer the best possible care that is consistent with a patient’s age and competency
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