Investigations concerning oxygen deficiency will increase our understanding of those factors that govern the overall material properties. Various studies have examined the relationship between oxygen deficiency and the phase transformation from a nonpolar phase to a polar phase in HfO2 thin films. However, there are few reports on the effects of oxygen deficiencies on the switching dynamics of the ferroelectric phase itself. Herein, we report the oxygen- deficiency induced enhancement of ferroelectric switching properties of Si-doped HfO2 thin films. By controlling the annealing conditions, we controlled the oxygen deficiency concentration in the ferroelectric orthorhombic HfO2 phase. Rapid high-temperature (800 °C) annealing of the HfO2 film accelerated the characteristic switching speed compared to low-temperature (600 °C) annealing. Scanning transmission electron microscopy and electron energy-loss spectroscopy (EELS) revealed that thermal annealing increased oxygen deficiencies, and first-principles calculations demonstrated a reduction of the energy barrier of the polarization flip with increased oxygen deficiency. A Monte Carlo simulation for the variation in the energy barrier of the polarization flipping confirmed the increase of characteristic switching speed.

Microtia reconstructive surgery is usually a multi-stage repair procedure that involves the use of cartilage and skin grafts. Complications can arise at both ear reconstruction sites and cartilage donor sites. In particular, pneumothorax, atelectasis, chest scars, and chest deformities are known to be associated with the harvesting of costal cartilage. However, delayed pleural effusion can also develop. Our patient complained of a cough and chest pain at 5 days postoperatively, and pleural effusion was detected by chest radiography. However, thoracentesis was not performed and the effusion resolved spontaneously and completely.

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We report the effect of 60Co gamma-ray irradiation on the ferroelectric properties of metal–ferroelectric Hf0.5Zr0.5O2–metal thin film structures. The pristine Hf0.5Zr0.5O2 films showed strong radiation tolerance against gamma-rays with stable remanant polarization values. When Hf0.5Zr0.5O2 films were exposed to electric field cycling, or “wake-up” process, prior to irradiation, however, their ferroelectricity demonstrated a clear degradation of remanant polarization and coercive voltage shift of the hysteresis curves. The analysis of ferroelectric switching dynamics revealed faster polarization switching with broadening of Lorentzian distribution of characteristic switching time for higher radiation doses, which is contrary to the wake-up behavior. The relationship between the wake-up process and gamma-ray irradiation on the stability of ferroelectric Hf0.5Zr0.5O2 films was discussed in light of domain alignment and defect mechanisms, considering both the redistribution and trapping of defect charges.

The purpose of this study was to investigate the relationship between resistance training and bone mineral density of the elderly by using meta-analytic approach. A comprehensive literature review was conducted using such databases as EBSCOhost, Embase, and PubMed. A total of 12 articles were finally selected using the PRISMA procedure and analyzed using Comprehensive Meta-Analysis (CMA) 2.0. The results were as follows. Resistance training had a significant positive relationship on bone mineral density in lumbar, total hip and femoral neck. However, resistance training did not have a significant relationship on bone mineral density in trochanter.