The fatigue crack propagation behavior of pure magnesium single crystals has been investigated in laboratory air at room temperature. Two types of CT specimens with different notch orientations were prepared from the magnesium single crystal made by the Bridgeman technique. Fatigue crack propagation behaviors of each specimen were different related to notch orientation. In the case of C specimen with (10˜10)[0001] notch, a crack was inclined to (0001) gradually at low DK. To investigate crack propagation behavior along [0001], a tri crystal specimen in which has (10˜10)[0001] notch was prepared. A crack propagated to [0001] in this specimen and the fatigue surface shows striation like pattern. In the case of E specimen with (0001) [10˜10] notch, a crack propagates parallel to basal plane. {10˜12} twin occurred in front the crack at higher DK level. A fatigue surface of the E specimen was changed by {10˜12} twin formation.

Fatigue properties of commercial purity titanium sheets severely deformed by the accumulative roll bonding (ARB) process were investigated. The ARB process was carried out up to 6 cycles (equivalent strain, " eq. ¼ 4:8). The sheets ARB processed by 2-, 4-and 6-cycle consist of fine equiaxed grains and elongated lamellar grains. In the sheet ARB processed by 6-cycle, the mean size of fine equiaxed grain was 89 nm, and the mean thickness of the lamellar grains were 67 nm. The tensile strength increased with increasing the number of the ARB cycle. Fatigue crack growth tests were performed to clarify the fatigue properties such as the crack growth rate and threshold stress intensity factor range for crack growth (ÁK th ). The ÁK th of the ARB processed specimens were smaller than that of the starting sheet. The ÁK th decreased with increasing the number of the ARB cycle until 4-cycle. However, the ÁK th of 6-cycle specimen was larger than that of the 4-cycle specimen. Fracture surface of the 6-cycle specimen was different from that of the 2-and 4-cycle specimens. Fatigue crack propagation behavior changes between 4-and 6-cycle specimens. On the other hand, the crack growth rate decreases with increasing the number of the ARB cycle.

Background: Childhood cancer survivors (CCSs) entering adulthood experience different problems, including late therapy-related complications. Long-term follow up (LTFU) is important for early intervention and psychosocial support for CCSs with late complications but it is frequently discontinued. This study aimed (i) to identify clearly the factors responsible for LTFU discontinuation, and (ii) to define the support needs of CCSs. Methods: From July, 2017 to March, 2019 we conducted a questionnaire survey of 121 CCSs aged ≥ 18 years at the time of the survey to investigate people who have experienced childhood cancer and identify their support needs. This was conducted in cooperation with patient associations throughout Japan. The LTFU levels were determined by CCSs themselves based on their treatment history. Long-term follow-up rates and LTFU discontinuation factors were assessed using the Kaplan-Meier method and the Cox proportional-hazards model. Results: Late complications were the most common problem encountered by CCSs (80%). The most common support need was "explanation of late complications by a physician," reported by 86.9% of respondents. The rate of LTFU continuation decreased over time. The LTFU was discontinued both for physicians' reasons (35.6%) and patients' reasons (64.4%). Not knowing the extent or level of one's LTFU was reported to be an independent factor (P < 0.05) preventing LTFU continuation. As necessary support to continue LTFU, 67.9% of respondents stated the need for "explanation of LTFU by a doctor" and 60.7% stated "convenience of outpatient visit". Conclusions: Childhood cancer survivors require support, especially for late complications. It is necessary to continue LTFU, raising LTFU awareness among physicians and CCSs.

Magnesium alloys are very attractive, because they are extremely light, and possessing excellent specific tensile strength. It is important to understand fatigue crack growth mechanism in magnesium. The fatigue tests have been performed using two types of CT specimens with different notch orientations in laboratory air at ambient temperature. The notch plane and direction in the C-specimens were (10 -,10) and [0001], E-specimens were ( 0001) and [10 -,10] respectively.Fatigue fracture surfaces and da/dN-∆K (stress intensity factor range) curves showed strongly dependence of notch orientations in magnesium. In the C-specimens, basal slip bands were observed near the crack and the fatigue crack growth rate was faster than the other specimens. There were many twins near the crack of the E-specimen. Fracture surface in E-specimens and higher ∆K were similar to C-specimens. da/dN of the E-specimen was lower than the E-specimen.