Soft Gel Filler Embedded Elastomer with Surfactant Improved Interface for Dielectric Elastomer Actuators.

Stretchable materials are the foundation of dielectric actuators (DEAs) for artificial muscle. However, the inadequate dielectric constant of stretchable materials has always greatly limited the performance of artificial muscle. Recently, soft fillers have been proposed to improve the dielectric property and preserve the stretchability for softness, aiming to avoid the stiffening effect of traditional rigid fillers. As composites, an amount of interfacial region is generated, which remarkably affects composites' performance from dielectrics to mechanics. Herein, we demonstrate that the size effect, interfacial binding, and compatibility have a great impact on soft filler doped composites. Particularly, according to the liquid characteristics of soft fillers, we explore an interfacial modification method using surfactants. Composite breakdown strength is thus enhanced 2.2-fold from that in the control group due to the reduction of mismatch between fillers and matrix. Moreover, surfactants alleviate the well-known stiffening effect in small fillers. The area strain of the composites reaches 10.3 ± 0.4% at a low electric field of 7 MV/m, and a soft micropump is successfully assembled. These findings demonstrate a unique and combined interfacial influence of soft filler doped elastomer, which promotes the advancements of the dielectric elastomer artificial muscle.

Novel Route for Enhancing Piezoelectricity of Ferroelectric Films: Controlling Nontrivial Polarization States in Pb(Zr, Ti)O3 Monodomain Superlattice Structure.

Artificial superlattice films made of Pb(Zr0.4Ti0.6)O3 and Pb(Zr0.6Ti0.4)O3 were investigated for their polarization states and piezoelectric properties theoretically and experimentally in this study. The developed theory predicts nontrivial polarization along neither [001] nor [111] directions in (111)-epitaxial monodomain superlattice films with uniform compressive strain. Such films were achieved via pulsed laser deposition. When the layer thickness is reduced to 3 nm, d33 becomes 128 ± 3.8 pm/V at 100 kV/cm and 71.3 ± 2.83 pm/V at 600 kV/cm, comparable to that of (111)-oriented Pb(Zr0.4Ti0.6)O3 or Pb(Zr0.6Ti0.4)O3 bulks and clearly exceeding that of the typical clamped films. The measurement agrees with the theoretical analysis, which reveals that the enhanced piezoelectricity is due to rotation of the nontrivial polarization. Furthermore, the theoretical study predicts an even larger d33 exceeding 300 pm/V for specific parameters in superlattice films with uniform tensile strain, which is promising for applications of microelectromechanical systems.

Effects of self-monitoring using an accelerometer on physical activity of older people with long-term care insurance in Japan: a randomized controlled trial.

PURPOSE: This study aimed to investigate the effects of a self-monitoring intervention to promote an increase in physical activity, as measured by step count, and reduce sedentary behavior in older people covered by the long-term care insurance system (LTCI) in Japan. METHODS: This was a randomized controlled trial conducted at a daycare center from October 2022 to January 2023. Fifty-two older adults with LTCI who were able to walk with or without aids were assigned to an intervention (n = 26) group and control (n = 26) group. During the 5-week follow-up period, the intervention group received education on physical activity and self-monitoring such as goal setting, self-management and feedback. The primary outcome was step count, and the secondary outcome was sedentary behavior. RESULTS: Participants who completed the study to the end of the 5-week follow-up and drop-out participants for whom outcome data were available were included in the final analysis of 57 participants, n = 24 (79.8 ± 8.8 years, male 25.5%) in the intervention group and n = 23 (82.5 ± 8.5 years, male 39.1%) in the control group. Comparisons between the two groups at baseline showed no significant differences. In the results of a two-way mixed analysis of variance (ANOVA) including 2 (group: control, intervention) × 2 (term: baseline, 5-week follow-up) factors, an interaction was observed in the number of steps, sedentary behavior, and light physical activity (p < 0.05). CONCLUSION: Self-monitoring of physical activity using an accelerometer may be effective in increasing the number of steps and light physical activity and in reducing sedentary behavior in older people with LTCI. CLINICAL TRIAL REGISTRATION: UMIN000052044, registered on 2023/08/29.

Differences in Health-Related Quality of Life in Older People with and without Sarcopenia Covered by Long-Term Care Insurance.

Background: As a result of the increase in older people covered by long-term care insurance (LTCI), prevention of sarcopenia and maintenance and improvement of health-related quality of life (HRQOL) have become important themes. This study aimed to clarify both the differences in HRQOL in older people with and without sarcopenia covered by LTCI and the correlation between HRQOL and physical function. Methods: Participants were 101 older people with LTCI at a daycare center in Japan. We investigated clinical factors using the EuroQol five-dimension three-level questionnaire (EQ-5D-3L). Analysis was by unpaired t-test, Mann−Whitney U test, chi-square test, analysis of covariance, Pearson's correlation coefficient, and Spearman's rank correlation coefficient. Results: Compared to the no sarcopenia group (n = 40), the sarcopenia group (n = 24) had significantly lower body mass index, skeletal muscle mass index, gait speed, EQ-5D-3L, and adjusted EQ-5D-3L (p < 0.05). The EQ-5D-3L showed a significant correlation with handgrip strength in the sarcopenia group (p = 0.02) and significant correlations with gait speed and one-leg standing time (both, p = 0.01) in the no sarcopenia group. Conclusion: We clarified differences in HRQOL in older people with and without sarcopenia covered by LTCI. This information on the interrelationship between HRQOL and physical function may help maintain and improve HRQOL in these people.

Physical Activity and Sarcopenia in Community-Dwelling Older Adults with Long-Term Care Insurance.

The present study aimed to clarify the difference in physical activity (PA) due to sarcopenia in community-dwelling older adults with long-term care insurance (LTCI). This was a cross-sectional study that investigated data of 97 consecutive community-dwelling older Japanese adults with LTCI who underwent rehabilitation at one day care center in Japan from November 2018 to May 2019. Sarcopenia was determined according to criteria of the Asian Working Group for Sarcopenia. Unpaired t-test, Mann-Whitney U test, chi-square test and analysis of covariance were used to compare participant characteristics and clinical parameters between the older adults with and without sarcopenia. A receiver operating characteristic (ROC) curve was constructed to determine the cut-off value of PA for sarcopenia. The sarcopenia group (n = 20) had significantly lower body mass index (BMI), skeletal muscle mass index, gait speed, and PA than those in the no sarcopenia group (n = 28) (p < 0.05). After adjustment for BMI and sex, the sarcopenia group showed significantly lower PA than the no sarcopenia group. Findings showed that the cut-off value of PA indicating sarcopenia by ROC curve analysis was 1494.4 steps/day (p < 0.05); this value may aid in identifying sarcopenia in older adults with LTCI.

Prevalence and Related Factors of Sarcopenia in Community-dwelling Elderly with Long-term Care Insurance.

BACKGROUND AND OBJECTIVE: The purpose of this investigation was to examine the prevalence, related factors, and cut-off value of body mass index for sarcopenia in community-dwelling elderly covered by long-term care insurance. METHODS: Design was a cross-sectional study, in which113 consecutive community-dwelling elderly with long-term care insurance who underwent rehabilitation at a daycare center in Japan from January 2016 to January 2018, those who were aged ≥65 years old and could walk were included. Those in whom skeletal muscle mass index could not be measured were excluded. The determination of sarcopenia was made according to the criteria of the Asian Working Group for Sarcopenia. We analyzed the data with the unpaired t-test, χ2 test, logistic regression analysis, and receiver operating characteristic curves. RESULTS: The 99 elderly meeting the criteria were included and divided into the sarcopenia group (n=36) and no sarcopenia group (n=63). The prevalence was 36.4%. The sarcopenia group was significantly older and had lower body mass index, skeletal muscle mass index, and grip strength than the group without sarcopenia (p <0.05). Age and body mass index were extracted as significant sarcopenia- related factors (p <0.05). The cut-off value of body mass index for sarcopenia was 22.6 kg/m2. CONCLUSION: The prevalence of sarcopenia in the elderly in the long-term care insurance region was 36.4%, and age and body mass index were extracted as sarcopenia-related factors. The cut-off value of body mass index for sarcopenia was 22.6 kg/m2.

Singular-value decomposition using quantum annealing.

In the present study, we demonstrate how to perform, using quantum annealing, the singular value decomposition and the principal component analysis. Quantum annealing gives a way to find a ground state of a system, while the singular value decomposition requires the maximum eigenstate. The key idea is to transform the sign of the final Hamiltonian, and the maximum eigenstate is obtained by quantum annealing. Furthermore, the adiabatic time scale is obtained by the approximation focusing on the maximum eigenvalue.

100-nm-sized magnetic domain reversal by the magneto-electric effect in self-assembled BiFeO3/CoFe2O4 bilayer films.

A (001)-epitaxial-BiFeO3/CoFe2O4 bilayer was grown by self-assembly on SrTiO3 (100) substrates by just coating a mixture precursor solution. The thickness ratio of the bilayer could be controlled by adjusting the composition ratio. For example, a BiFeOx:CoFe2Ox = 4:1 (namely Bi4CoFe6Ox) mixture solution could make a total thickness of 110 nm divided into 85-nm-thick BiFeO3 and 25-nm-thick CoFe2O4. Self-assembly of the bilayer occurred because the perovskite BiFeO3 better matched the lattice constant (misfit approximately 1%) and crystal symmetry of the perovskite SrTiO3 than the spinel CoFe2O4 (misfit approximately 7%). The magnetic domains of the hard magnet CoFe2O4 were switched by the polarization change of BiFeO3 due to an applied vertical voltage, and the switched magnetic domain size was approximately 100 nm in diameter. These results suggest that self-assembled BiFeO3/CoFe2O4 bilayers are interesting in voltage driven nonvolatile memory with a low manufacturing cost.

Effect of disorder potential on domain switching behavior in polymer ferroelectric films.

Nanoscale switching dynamics in spin-coated ferroelectric copolymer films of polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE 75/25) has been investigated via high-resolution real-space imaging of electrically induced domain structure evolution using resonance-enhanced piezoresponse force microscopy. It has been shown that in strongly imprinted films application of switching pulses of opposite polarity results in qualitatively different domain switching dynamics. A distinct feature of domain dynamics is roughening of the domains walls during switching to the preferred polarization state as opposed to smooth domain boundaries during switching to the opposite direction. The observed switching behavior is explained by a combined effect of the spatially uniform built-in electric field and local disorder potential. Application of the external potential changes the balance between the two and creates conditions under which domain growth is dominated either by the average built-in electric field or local random-bond disorder potential.

Influence of Pb and La contents on the lattice configuration of La-substituted Pb(Zr,Ti)O3 films fabricated by CSD method.

The influence of Pb and La contents on the lattice configuration in La-substituted Pb(Zr0(.65),Ti0(.35))O3 (La- PZT) films was systematically investigated. La-PZT films with various La and Pb contents were fabricated on Pt/Ti/SiO(2)/Si substrates by chemical solution deposition (CSD). In the La- PZT films with a Pb content ratio of 125% relative to a stoichiometric value, La ions were substituted for not only A-site ions but also B-site ions at La contents greater than 3 mol%. La substitution for B-site seems to cause larger reduction of the unit cell size. In addition, we found that in the La-PZT films with a La content of 3 mol%, the Pb content of 116 mol% (120% relative to a stoichiometric value) was optimum from the viewpoint of site occupancy. This indicates that excess Pb prevented the A-site substitution of La ions.