Photo-Fenton and TiO2 Photocatalytic Inactivation of Model Microorganisms under UV-A; Comparative Efficacy and Optimization.

Photocatalytic inactivation of pathogens in aqueous waste is gaining increasing attention. Several homogeneous and heterogeneous photocatalytic protocols exist using the Fenton's reagent and TiO2, respectively. A comprehensive study of homogeneous and heterogeneous photocatalysis on a range of microorganisms will significantly establish the most efficient method. Here, we report a comparative study of TiO2- and Fe+3-based photocatalytic inactivation under UV-A of diverse microorganisms, including Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, bacterial spores (Bacillus stearothermophilus spores) and viruses (MS2). We also present data on the optimization of TiO2 photocatalysis, including optimal catalyst concentration and H2O2 supplementation. Our results indicate that both photo-Fenton and TiO2 could be successfully applied for the management of microbial loads in liquids. Efficient microorganism inactivation is achieved with homogeneous photocatalysis (7 mg/L Fe+3, 100 mg/L H2O2, UV-A) in a shorter processing time compared to heterogeneous photocatalysis (0.5 g/L TiO2, UV-A), whereas similar or shorter processing is required when heterogenous photocatalysis is performed using microorganism-specific optimized TiO2 concentrations and H2O2 supplementation (100 mg/L); higher H2O2 concentrations further enhance the heterogenous photocatalytic inactivation efficiency. Our study provides a template protocol for the design and further application for large-scale photocatalytic approaches to inactivate pathogens in liquid biomedical waste.

Age-related differences in peak handgrip strength between wrestlers and nonathletes during the developmental years.

This study examined the development of peak handgrip strength from childhood to adulthood in wrestlers (n = 122) and nonathlete controls (n = 122). The effect of hand preference on handgrip strength and the relationship of anthropometrical characteristics with handgrip strength in wrestlers and controls were also evaluated. Participants were assigned into age groups: children, young adolescents, late adolescents, and adults. Body height and mass, hand dimensions (length, span, and width), and absolute handgrip (in kilograms) were measured. Handgrip strength was similar in wrestlers and controls in the younger age groups (i.e., in children and young adolescents), whereas late adolescent and adult wrestlers exhibited significantly greater peak handgrip strength (p < 0.05) than their control peers. Nonathletes older than 15 years demonstrated an approximately 10% greater peak handgrip strength (p < 0.05) with their preferred hand compared with the nonpreferred hand. In contrast, late adolescent and adult wrestlers exhibited similar handgrip strength with both hands. Peak handgrip strength exhibited a significant linear correlation with all the anthropometric measures examined; however, a higher percentage in the variation in peak handgrip strength was explained by body height and hand length than the other anthropometric variables in both groups. In conclusion, wrestlers exhibit a sport-specific pattern of handgrip strength changes during the developmental years. Body height and hand length exhibited the strongest correlations with handgrip strength during the developmental years in wrestlers and in controls. The training adaptations of wrestling resulted in symmetrical handgrip strength development in both hands at late adolescence and adulthood. These data serve to provide a descriptive profile of handgrip strength in wrestlers, to assist both coaches and health professionals for talent selection and/or development of training programs for performance enhancement and rehabilitation.