Dielectric Barrier Discharge Plasma Jet (DBDjet) Processed Reduced Graphene Oxide/Polypyrrole/Chitosan Nanocomposite Supercapacitors.

Reduced graphene oxide (rGO) and/or polypyrrole (PPy) are mixed with chitosan (CS) binder materials for screen-printing supercapacitors (SCs) on arc atmospheric-pressure plasma jet (APPJ)-treated carbon cloth. The performance of gel-electrolyte rGO/CS, PPy/CS, and rGO/PPy/CS SCs processed by a dielectric barrier discharge plasma jet (DBDjet) was assessed and compared. DBDjet processing improved the hydrophilicity of these three nanocomposite electrode materials. Electrochemical measurements including electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charging-discharging (GCD) were used to evaluate the performance of the three types of SCs. The Trasatti method was used to evaluate the electric-double layer capacitance (EDLC) and pseudocapacitance (PC) of the capacitance. The energy and power density of the three types of SCs were illustrated and compared using Ragone plots. Our experiments verify that, with the same weight of active materials, the combined use of rGO and PPy in SCs can significantly increase the capacitance and improve the operation stability.

Electropolymerized Poly(3,4-ethylenedioxythiophene)/Screen-Printed Reduced Graphene Oxide-Chitosan Bilayer Electrodes for Flexible Supercapacitors.

An electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT)/screen-printed reduced graphene oxide (rGO)-chitosan (CS) bilayer material was coated on carbon cloth to form electrodes for gel-electrolyte flexible supercapacitors. The conductive polymer and carbon-based materials mainly contribute pseudocapacitance (PC) and electrical double-layer capacitance (EDLC), respectively. The high porosity and hydrophilicity of the PEDOT/rGO-CS bilayer material offers a large contact area and improves the contact quality for the gel electrolyte, thereby enhancing the capacitive performance. Cyclic voltammetry (CV) under a potential scan rate of 2 mV/s revealed that a maximum areal capacitance of 1073.67 mF/cm2 was achieved. The capacitance contribution ratio PC/EDLC was evaluated to be ∼67/33 by the Trasatti method. A 10,000-cycle CV test showed a capacitance retention rate of 99.3% under a potential scan rate of 200 mV/s, indicating good stability. The areal capacitance remains similar under bending with a bending curvature of up to 1.5 cm-1.

Structural and Dynamic Characterization of Mutated Keap1 for Varied Affinity toward Nrf2: A Molecular Dynamics Simulation Study.

Keap1 is an adaptor protein that regulates Nrf2 in response to oxidative stress. Under basal conditions, Nrf2 is negatively regulated through ubiquitination by Keap1. However, upon exposure to oxidative stress, the ubiquitination of Nrf2 is inhibited, resulting in an increased steady-state level of Nrf2 in the nucleus and increased transcription of cytoprotective genes. A gene variant G364C and somatic mutation G430C on Keap1 have recently been reported to substantially impair the Keap1-Nrf2 interaction and to be associated with lung cancer. By contrast, alanine scanning experiments have shown that the mutations S363A, S508A, S555A, and S602A do not affect the ability of Keap1 to bind to Nrf2, regardless of the fact that G364 and G430 are not in contact with Nrf2 whereas the four serine residues are involved in the accommodation of Nrf2 with their hydroxy groups. In this study, molecular dynamics simulations were performed to investigate the structural and dynamic variances among wild-type (WT) Keap1 and the six mutants in unbound form. Principal component analysis of the collected MD trajectories was performed to provide dynamic diversity. Our dynamic and structural observations suggest that the G364C and G430C mutants possess a mobile D385 that moves toward R380, an anchor residue to accommodate an acidic residue in Nrf2, thereby hampering the Keap1-Nrf2 recognition of an electrostatic nature. By contrast, none of the four serine-to-alanine mutants alters the H-bond network formed by the serine backbone to its partner; accordingly, these mutants are almost as intact as the WT structurally and dynamically.

Can sit-to-stand lower limb muscle power predict fall status?

Sit-to-stand (STS) movements are essential for daily activities. Failure to perform STS movements efficiently and smoothly may lead to falls. In this study, we developed a forceplate to analyze vertical ground reaction force (VGRF), STS duration and generated muscle power to investigate which parameters were fall status predictors. A total of 105 participants were included in this study and were grouped into those (1) aged between 20 and 30 years (Young), (2) aged above 65 years without a history of falling (Non-fallers) and (3) aged above 65 with a history of falling in the past 12 months (Fallers). The results indicated a significantly higher maximal lower limb muscle power (MP) for the Young (9.05 ± 3.66 W/kg), followed by Non-fallers (5.50 ± 2.02W/kg) and Fallers (3.66 ± 1.45 W/kg) as well as higher modified falls efficacy scale (MFES) scores for the Young (Young: 9.88 ± 0.10; Non-fallers: 6.27 ± 1.40; Fallers: 4.83 ± 0.89) and shorter times for the five times sit-to-stand test (FSTST) for the young (Young: 6.09 ± 2.20 s; Non-fallers: 15.65 ± 3.30s; Fallers: 19.82 ± 4.46 s). There was a significant difference between the Young group and the Non-fallers in the maximal vertical ground reaction force (VGRF) (138.79 ± 24.20 N/BW in Young, 117.51 ± 8.57 N/BW in old Non-fallers, p < 0.01), and there was a significant difference between the Non-fallers and the Fallers in the duration of the STS movement (2.74 ± 0.87 s for the Non-fallers, 4.27 ± 2.56 s for the Fallers, p < 0.01). The regression analysis results further indicated that only MP and the STS stabilization phase could differentiate individuals who had past fall events. Therefore, the equipment we developed could potentially be useful in the assessment and monitoring of balance and the risk of falling in older people.