This is the first Canadian study to report on the duration of physical activity and duration and bouts of sedentary behaviour among both toddlers and preschoolers attending child care centres. These findings suggest child care interventions are needed to increase MVPA and decrease total sedentary behaviour while continuing to promote short sedentary bouts.
Background Child care centers are important for children’s behaviors. Aims To examine the cross-sectional associations between child care environmental characteristics and physical activity and sedentary time in children. Methods Participants were 124 toddlers and 118 preschoolers from 19 centers in Alberta and Ontario, Canada, in the supporting Healthy physical AcTive CHildcare setting (HATCH) study. In-care physical activity and sedentary time were assessed using Actigraph accelerometers. Child care environments, including structure (e.g., resources) and process (e.g., activities) quality, were measured using three instruments: (1) the Environment and Policy Assessment and Observation and (2) the Children’s Physical Environments Rating Scale, and (iii) the Movement Environment Rating Scale. Mixed models were performed to examine the associations between environmental characteristics and children’s sedentary time, light physical activity, and moderate-to-vigorous physical activity. Results A few structure quality characteristics related to child care policy and indoor environment were associated with higher physical activity and lower sedentary time in toddlers. The overall structure quality ( B = 0.04; 95% CI [0.003, 0.08]) and process quality ( B = 0.08; 95% CI [0.02, 0.15]) of the child care environment were associated with log moderate-to-vigorous physical activity in preschoolers. Specifically, structure quality characteristics of the outdoor environment and physical activity time, and process quality characteristics relevant to curriculum and pedagogy, were associated with higher physical activity and lower sedentary time in preschoolers. Discussion and Conclusion The child care structure quality characteristics that are important for children’ physical activity and sedentary behavior may vary by age group. Improving the overall process quality, in particular curriculum and pedagogy, of the child care environment, may promote more physical activity in preschoolers.
Zinc sulfide clusters were synthesized and characterized at low micromolar concentrations to assess the effect of metal-sulfide ligands on metal toxicity to aquatic organisms in oxic environments. Recommended preparation times are greater than 2 h initial reaction of equimolar sodium sulfide and zinc nitrate, followed by oxic aeration for 3 d. Ionic strength, pH, and anoxic stabilization time were found to be relatively unimportant in controlling the final yield. Adsorptive losses of zinc sulfide (ZnS) clusters to surfaces, however, were significant for a variety of vessel materials and membrane filters. Ionic strength and pH were found to be important factors controlling the extent of adsorptive losses with minimal loss for pHs greater than 9 and for soft waters. The Ag(I), Cu(II), and Hg(II) as metal sulfides completely suppress the analysis of sulfide, whereas Pb(II), Mn(II), and Co(II) partially suppress the analysis of sulfide by the methylene blue technique. Ultraviolet and fluorescence spectra are shown for synthesized ZnS clusters.
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