Physical activity is universally acknowledged for its benefits to mental health; however, the specific intensities and timings that best benefit adolescents’ mental health, crucial due to their significant influence on daily schedules, have not been thoroughly investigated. This study addresses the substantive research gap by exploring the varied effects of physical activity intensity (light versus moderate to vigorous) and timing (weekdays versus weekends and holidays) on adolescent mental health. Utilizing a large-scale longitudinal dataset (NT1 = 84,054; NT2 = 44,623) from 158 schools, this research describes the current state of adolescent physical activity and investigates the effects of physical activity on mental health outcomes, including positive (i.e., life satisfaction, positive mental health) and negative indicators (depression, anxiety), over a 6-month period. Participants were adolescents aged 9–19 years (mean age = 12.73 ± 2.43 years, 48.9% female), with the analysis adjusted for potential confounding factors. Results showed that as adolescents grow older, their engagement in moderate-to-vigorous physical activity during both weekdays and weekends/holidays tends to decrease, while light physical activity during weekdays increases. Multilevel regression analysis indicated that moderate-to-vigorous physical activity during weekends/holidays at Time 1 positively correlated with better mental health outcomes at Time 2 (six months later), featuring enhanced positive indicators and reduced negative ones. Moderate-to-vigorous physical activity on weekdays at Time 1 was positively linked to mental health at Time 2. Light physical activity during weekends/holidays at Time 1 positively predicted life satisfaction and positive mental health at Time 2. In contrast, light physical activity on weekdays at Time 1 negatively correlated with life satisfaction at Time 2. The study underscores the importance of promoting moderate-to-vigorous physical activity, particularly on weekends and holidays, to improve mental health outcomes among adolescents.
Teflon bag chambers have long been used for investigating atmospheric chemical processes, including secondary organic aerosol formation. The wall-loss process of gas-phase species in Teflon bag chambers has typically been investigated at around room temperature. Recent laboratory studies started employing Teflon bag chambers at sub-273 K conditions for simulating wintertime and upper-tropospheric environments. However, temperature dependence in vapor-wall-loss processes of semi-volatile organic compounds (SVOCs) in a Teflon bag chamber has not been well investigated. In this study, we experimentally investigated wall-loss processes of C14–C19 n-alkanes in a 1 m3 Teflon bag for the temperature range of 262 to 298 K. Enhanced wall losses of the tested n-alkanes were observed following the decrease in temperature. For instance, 65 % of C14 n-alkane was lost to the wall 15 h after injection at room temperature, while the corresponding value was 95 % at 262 K. The experimental data were analyzed using a two-layer kinetic model, which considers both absorption of gas-phase species to the surface layer of the Teflon wall and diffusion to the inner layer. The experimental data demonstrated that absorption of gas-phase species by the surface layer was enhanced at lower temperatures. The temperature dependence in absorption was well accounted for using the equilibrium-dissolution model of organic compounds to the Teflon surface by considering reduced saturation vapor pressure at lower temperatures. On the contrary, diffusion of n-alkanes from the surface to the inner layer slowed down at reduced temperatures. Mechanistic studies on these processes will need to be conducted in the future to quantitatively predict the influence of temperature-dependent wall-loss processes of SVOCs on laboratory experimental results.
The reactions between CO2 slugs and crude oil induce a substantial amount of asphaltene precipitation and adsorption on the rock surface during the CO2 alternative water flooding process. When the subsequent water slug passes through the core pores after asphaltene adsorption, it will displace the previous CO2 slug. The wettability of water and CO2 on the asphaltene-adsorbed rock surface will directly determine the magnitude and direction of the capillary force of the two media, which in turn affects their flow resistance and flow pattern analysis. In this paper, the systems of CO2/water/sandstone and CO2/water/asphaltene adsorption sandstone were established by molecular dynamics simulation technology. The effects of asphaltene adsorption, thickness of the asphaltene adsorption layer, CO2 density, mass fraction and type of salt in water on the wettability of water on sandstone surfaces were studied. The results reveal that asphaltene adsorption significantly reduces the wettability of water on the original powerful water-wetting sandstone surface, making it easier to see how CO2 density affects the wettability of water on the asphaltene-adsorbed sandstone surface. The increased CO2 density will continue to lower the wettability of water on the asphaltene-adsorbed sandstone surface, even causing it to become wet with CO2. The adsorption thickness of asphaltene does not affect the wettability of water and CO2 on the asphaltene-adsorbed sandstone surface, and just a layer of 5A-thick asphaltene adsorption can significantly reduce the wettability of water on sandstone surfaces. Furthermore, a rise in salinity in water has a detrimental impact on the wettability of water on the asphaltene-adsorbed sandstone surface, with divalent salts having a stronger negative effect than monovalent salts.
Rural households contend with numerous uninsured risks that hinder their ability to leverage profitable yet risky opportunities. We study whether the provision of insurance coverage for medical expenditure, one of the most substantial and unpredictable risk, can stimulate entrepreneurship and other risky financial decisions among rural households. We leverage the progressive nationwide rollout of a universal public health insurance program in rural China. We find that the introduction of health insurance led to a substantial increase in rural households engagement in entrepreneurship. This increase is mainly driven by the risk sharing of health insurance, rather than a reduction in realized medical expenses. The entrepreneurship-promoting effect is also evident at an aggregate level, fostering the growth of smallholder businesses in rural counties. Our findings shed light on the understudied, favorable impact of health insurance on household’s risk taking in rural markets of developing countries.