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Background: The aim was to assess the long-term radiographic outcomes of patients with Legg-Calvé-Perthes disease following an early proximal femoral osteotomy (PFO) performed in avascular necrosis stage or early fragmentation stage. Methods: In this retrospective study, we analyzed data of 65 patients aged above 6 years at the time of diagnosis with unilateral Legg-Calvé-Perthes disease, following early PFO performed at our institution between 1979 and 2013. We observed the presence of bypassing fragmentation stage, which was classified into complete and incomplete. We compared radiographic outcomes between patients with bypass of fragmentation stage (26 hips) and those without (31 hips). Regarding skeletal maturity, the hips were graded according to the femoral head shapes: spherical, ovoid, or flat. Results: The mean age at diagnosis was 7.9 years (range: 6.0 to 11.9 y). The average follow-up period was 11.8 years (range: 5.9 to 22.9 y). Fragmentation bypass occurred in 40.5% (26/65) of patients, with 8 (12.3%) "undetermined" cases. Patients who completely or partially bypassed fragmentation experienced significantly less severe lateral pillar collapse (P = 0.016). The femoral head was also significantly more spherical in patients with bypass (P = 0.024). Conclusions: Our results show that 40.5% of patients who underwent early PFO bypassed the fragmentation stage. The degree of lateral pillar collapse was lower in patients with bypass. In addition, there were significantly more patients with more spherical femoral head in the bypass group. Level of Evidence: Level IV-case series.

Piezoelectric nanogenerators (PNGs) are capable of converting energy from various mechanical sources into electric energy and have many attractive features such as continuous operation, replenishment and low cost. However, many researchers still have studied novel material synthesis and interfacial controls to improve the power production from PNGs. In this study, we report the energy conversion efficiency (ECE) of PNGs dependent on mechanical deformations such as bending and twisting. Since the output power of PNGs is caused by the mechanical strain of the piezoelectric material, the power production and their ECE is critically dependent on the types of external mechanical deformations. Thus, we examine the output power from PNGs according to bending and twisting. In order to clearly understand the ECE of PNGs in the presence of those external mechanical deformations, we determine the ECE of PNGs by the ratio of output electrical energy and input mechanical energy, where we suggest that the input energy is based only on the strain energy of the piezoelectric layer. We calculate the strain energy of the piezoelectric layer using numerical simulation of bending and twisting of the PNG. Finally, we demonstrate that the ECE of the PNG caused by twisting is much higher than that caused by bending due to the multiple effects of normal and lateral piezoelectric coefficients. Our results thus provide a design direction for PNG systems as high-performance power generators.

Background For health care workers, immune management plays an important role in the protection against infectious diseases. This study investigated the seroprevalence of measles, mumps, rubella, and varicella-zoster in newly employed female nurses. Methods We conducted a survey on the seroprevalence of measles, mumps, rubella, and varicella-zoster in newly employed female nurses at a university hospital from 2011 to 2019, before the nurses were given their department placements and duty start. Enzyme-linked immunosorbent and chemiluminescence immunoassays were used to detect immunoglobulin G antibodies. We analyzed whether there was a significant difference in seroprevalence depending on the age, birth year, birth season, and region of residence (metropolitan residency: yes or no). Results The arithmetic mean ages of the participants were 28.6 ± 4.8, 23.5 ± 3.2, 23.6 ± 3.0, and 26.1 ± 4.5 years for measles, mumps, rubella, and varicella-zoster, respectively. The seropositivity rates were 93.9% (551/587), 60.2% (50/83), 83.3% (3,093/3,711), and 89.5% (978/1,093) for measles, mumps, rubella, and varicella-zoster, respectively. Significant differences in the seroprevalence when assessed according to the age and birth year were noted with measles, while significant differences in the seroprevalence were only noted with rubella and varicella-zoster when assessed according to birth year and age, respectively. Conclusions In this study, we identified the levels of antibody prevalence in new female nurses. Considering the seropositivity levels, cost-effectiveness, and convenience for the participants, we recommend that the measles-mumps-rubella vaccination be provided without serologic testing for all new female nurses and the varicella-zoster vaccination only be performed for persons who are negative after serologic testing. And it would be useful if the vaccinations were combined with compulsory worker health examinations, such as the pre-placement health examinations.