Tailoring Low-field Strain Properties of [0.97Bi1/2(Na0.78K0.22)1/2TiO3-0.03LaFeO3]-Bi1/2(Na0.82K0.18)1/2TiO3 Lead-Free Relaxor/Ferroelectric Composites

We investigated the effect of Bi1/2(Na0.82K0.18)1/2TiO3 (BNKT) modification on the ferroelectric and electric-field-induced strain (EFIS) properties of lead-free 0.97Bi1/2(Na0.82K0.18)1/2TiO3-0.03LaFeO3 (BNKTLF) ceramics as a function of BNKT content (x= 0, 0.1, 0.2, 0.3, 0.5, and 1). BNKT-modified BNKTLF powders were synthesized using a conventional solid-state reaction method. As the BNKT content x increased from 0 to 1 the normalized electric-field-induced strain (Smax/Emax) was observed to increase at relatively low fields, i.e., below the poling field. Moreover, BNKTLF-30BNKT showed about 460 pm/V as low as at 3 kV/mm, which is a considerably high value among the lead-free systems reported so far. Consequently, it was confirmed that ceramic-ceramic composite, a mixture of an ergodic relaxor matrix and embedded ferroelectric seeds, is a salient way to make lead-free piezoelectrics practical with enhanced EFIS at low field as well as less hysterical.ope

Effects of Trunk Stabilization Exercise Using the Abdominal Expansion Maneuver on Postural Stability and Functional Movement in College Athletes

PURPOSE This study aimed to investigate the effects of trunk stabilization exercise (TSE) with abdominal expansion maneuver (AEM) that lasted for 8 weeks on postural stability and functional movement in college athletes. METHODS Twenty college athletes participated in the program (AEM=9, Control=11) and were subjected to 8-week TSE. The AEM group performed exercise by applying AEM techniques during TSE, and control group performed TSE without breathing-related instructions. Both groups measured postural stability with lower-quarter Y-balance test (LQYBT) and functional movement with functional movement screen (FMS) before and after applying TSE to verify the interaction before and after this study with the two groups. Two-way repeated analysis of variance was performed to evaluate the differences between groups and time for an absolute value of LQYBT and FMS, followed by Bonferroni’s multiple comparison tests for post-hoc analysis. RESULTS As a result of the left and right LQYBT, there was a significant difference between the time x group (p=.041, p=.033), and post-hoc analysis indicated that there was a significant difference between the AEM and control groups (p=.000, p=,000). Furthermore, the FMS total score indicated that there was a significant difference between the time × group (p=.039), and the post-hoc analysis showed the AEM group had significant results (p=.001), while there were no significant results in the control group (p=.255). CONCLUSIONS Application of AEM during TSE seems to be effective with regard to postural stability and functional movement in college athletes

Inaccuracy of intraocular pressure measurement in congenital corneal opacity: three case reports

Background To report three cases of congenital corneal opacity where intraocular pressure (IOP) readings were high despite the use of multiple anti-glaucoma eye drops and normalized after corneal transplantation. Case presentation Three Korean infants presented with bilateral dense stromal opacification which had been present since birth. IOPs measured by rebound tonometer were high despite administration of multiple anti-glaucoma medications. One eye of each patient underwent penetrating keratoplasty (PK) because corneal opacity impaired visual development. Immediately after PK, IOPs were normalized and maintained normal without medication, whereas they remained high in the contralateral unoperated eye. On histology, stromal fibrosis was observed in the removed corneal button, and molecular assays revealed increased levels of type 1 and 5 collagens. Conclusion The IOP measurement using the conventional applanation-based tonometry can be inaccurate in congenital corneal opacity which is marked by corneal fibrosis. Therefore, IOP values should be interpreted with caution in these patients, and the possibility of false-positive diagnosis of glaucoma considered.This study was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and future Planning (NRF-2018R1A2B2004108). The funder supported funding for molecular assay for corneal collagens in this study