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  • Bifunctional atomically dispersed ruthenium electrocatalysts for efficient bipolar membrane water electrolysis
    Publication . Yu, Zhipeng; Si, Chaowei; Escobar-Bedia, Francisco Javier; LaGrow, Alec P.; Xu, Junyuan; Sabater, Maria J.; Amorim, Isilda; Araujo, Ana; Sousa, Juliana P. S.; Meng, Lijian; Faria, Joaquim Luis; Concepcion, Patricia; Li, Bo; Liu, Lifeng
    Atomically dispersed catalysts (ADCs) have recently drawn considerable interest for use in water electrolysis to produce hydrogen, because they allow for maximal utilization of metal species, particularly the expensive and scarce platinum group metals. Herein, we report the electrocatalytic performance of atomically dispersed ruthenium catalysts (Ru ADCs) with ultralow Ru loading (0.2 wt%). The as-obtained Ru ADCs (Ru (0.2)-NC) are active for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which only require a low overpotential (η) of 47.1 and 72.8 mV to deliver 10 mA cm−2 for HER in 0.5 M H2SO4 and 1.0 M KOH, respectively, and of 300 mV for OER in 1.0 M KOH, showing favorable bifunctionality. Density functional theory (DFT) calculations reveal that the Ru–N bonding plays an important role in lowering the energy barrier of the reactions, boosting the HER and OER activities. Furthermore, the bipolar membrane (BPM) water electrolysis using the bifunctional Ru (0.2)-NC as both HER and OER catalysts can afford 10 mA cm−2 under a low cell voltage of only 0.89 V, and does not show any performance decay upon 100 h continuous operation, showing great potential for energy-saving hydrogen production.
    2022-06-24Journal article Restricted access Show more
  • Sex-related differences in muscular factors previously identified in the literature as potentially associated with hamstring strain injury in professional football players
    Publication . Rodrigues, Lívia Gonçalves ; Vianna, Karoline Baptista ; de Oliveira, Nathalia Trevisol ; Chaves, Alisson de Carvalho; Severo‑Silveira, Lucas ; Ribeiro‑Alvares, João Breno ; Carvalho, Paulo; Baroni, Bruno Manfredini 
    The purpose of this study was to assess if differences in hamstring strength, hamstring-to-quadriceps (H:Q) strength ratio, and biceps femoris long head (BFLH) fascicle length exist between male and female professional football (soccer) players. One-hundred professional footballers participated in this cross-sectional study: 50 men and 50 women. Ultrasound images of BFLH muscle and isokinetic dynamometry tests were performed. Men were stronger than women for hamstring concentric (2.01 ± 0.21 Nm/kg vs. 1.55 ± 0.23 Nm/kg; p < 0.001; large effect size, 2.08) and eccentric (2.87 ± 0.45 Nm/kg vs. 2.39 ± 0.32 Nm/kg; p < 0.001; large effect size, 1.23) peak torques. There was no sex-related difference for H:Q conventional ratio (concentric/concentric; 0.55 ± 0.06 vs. 0.55 ± 0.07); but women presented greater H:Q functional ratio (eccentric/concentric; 0.78 ± 0.12 vs. 0.85 ± 0.09; p = 0.003; moderate effect size, 0.66). Men and women presented similar BFLH fascicle length: 0.24 ± 0.05 vs. 0.23 ± 0.05 (values normalized by muscle length). Among the muscular factors assessed in this study, men presented stronger hamstring muscles, women presented greater H:Q functional ratio, and there was no sex-related differences for H:Q conventional ratio or BFLH fascicle length.
    2022-06-24Journal article Restricted access Show more