An Experimental Study on the Interaction Law of the Pore Gas Pressure and Stress in Gassy Coals

Understanding the principle underlying the coupling between coal seam stress and gas pressure will help prevent the occurrence of dynamic coal and gas disasters. However, previous studies have mainly focused on the macroscopic qualitative analyses of the coupling between coal seam stress and gas pressure. In fact, laboratory quantitative tests, which investigate gas pressure in sealed sample tanks, fail to represent the essential relationship between stress and gas pressure in real time. In this study, a model of the stress–porosity–gas pressure relationship was established based on the pore characteristics of gassy coals and gas adsorption theory to quantify the coupling between coal seam stress and gas pressure. In addition, a method for determining the law governing stress and gas pressure coupling was proposed based on stress–strain curves obtained through triaxial loading tests. Results show that the porosity and gas pressure of gassy coals first decrease and then increase as loading stress increases. Under various confining pressures and initial gas pressures, porosity declines at a lower rate with the increase in the initial gas pressure. Specifically, gas pressure increases with stress before the value of stress reaches that of the compressive strength of the coal. This behaviour demonstrates that gas pressure and stress are positively correlated. High initial gas pressures are associated with small increments (i.e., from 136% to 30%) in pore gas pressure under stress. When stress exceeds the compressive strength of the coal, gas pressure begins to decrease with stress. Thus, stress and gas pressure are negatively correlated. Finally, the validity of the research method was verified through afield experiment. The proposed method provides new concepts for the study of the mechanism, prevention, and control technology of dynamic coal and gas disasters

Isotemporal substitution effect of 24-hour movement behavior on the mental health of Chinese preschool children

The 24-h movement behavior of preschoolers comprises a spectrum of activities, including moderate-to-vigorous intensity physical activity (MVPA), light-intensity physical activity (LPA), screen-based sedentary behavior (SCSB), non-screen-based sedentary behavior (NSCSB), and sleep. While previous research has shed light on the link between movement behaviors and children’s mental health, the specific impacts on the unique demographic of Chinese preschoolers remain underexplored. This study significantly contributes to the literature by exploring how 24-h movement behavior affects the mental health of preschoolers in a Chinese context. The study involved205 Chinese preschool children (117 boys and 88 girls) between the ages of 3 and 6 years wore accelerometers to measure their LPA, MVPA, and sedentary behavior (SB), while their parents reported the time spent on sleep and SCSB. The parents also completed the Strength and Difficulties Questionnaire to assess their children’s mental health. The study used compositional regression and isotemporal substitution models to examine the relationship between the various components of 24-h movement behavior and mental health. The results showed that greater NCSSB compared to MVPA, LPA, sleep, and SCSB was associated with good prosocial behavior and lower scores on externalizing problems. This highlights the potential of NSCSB as a beneficial component in the daily routine of preschoolers for fostering mental well-being. Replacing 15 min of sleep and SCSB with 15 min of NSCSB was associated with a decrease of 0.24 and 0.15 units, respectively, in externalizing problems. Reallocating 15 min of sleep to NSCSB was linked to an increase of 0.11 units in prosocial behavior. There were no significant substitution effects between LPA and MVPA time with any other movement behavior on prosocial behavior and externalizing problems. Given the positive associations observed, further longitudinal studies are necessary to explore the link between 24-h movement behavior and mental health in preschool children

An experimental study on the interaction law of the pore gas pressure and stress in gassy coals

Understanding the principle underlying the coupling between coal seam stress and gas pressure will help prevent the occurrence of dynamic coal and gas disasters. However, previous studies have mainly focused on the macroscopic qualitative analyses of the coupling between coal seam stress and gas pressure. In fact, laboratory quantitative tests, which investigate gas pressure in sealed sample tanks, fail to represent the essential relationship between stress and gas pressure in real time. In this study, a model of the stress-porosity-gas pressure relationship was established based on the pore characteristics of gassy coals and gas adsorption theory to quantify the coupling between coal seam stress and gas pressure. In addition, a method for determining the law governing stress and gas pressure coupling was proposed based on stress-strain curves obtained through triaxial loading tests. Results show that the porosity and gas pressure of gassy coals first decrease and then increase as loading stress increases. Under various confining pressures and initial gas pressures, porosity declines at a lower rate with the increase in the initial gas pressure. Specifically, gas pressure increases with stress before the value of stress reaches that of the compressive strength of the coal. This behaviour demonstrates that gas pressure and stress are positively correlated. High initial gas pressures are associated with small increments (i.e., from 136% to 30%) in pore gas pressure under stress. When stress exceeds the compressive strength of the coal, gas pressure begins to decrease with stress. Thus, stress and gas pressure are negatively correlated. Finally, the validity of the research method was verified through afield experiment. The proposed method provides new concepts for the study of the mechanism, prevention, and control technology of dynamic coal and gas disasters

Examining Relationships among Chinese Preschool Children’s Meeting 24-Hour Movement Guidelines and Fundamental Movement Skills

Background: Few studies have investigated associations between meeting 24-Hour Movement Guidelines and preschool children’s fundamental movement skills (FMS). This study aimed to investigate the associations between Chinese preschoolers meeting various combinations of the Guidelines and FMS, as well as examining gender differences across those outcomes. Methods: A total of 322 preschool children (181 boys and 141 girls) aged 3–6 years old were recruited from five early-childhood education and care services in China. Children’s 7-day physical activity (PA) was assessed using accelerometry, and screen time (ST) and sleep duration were reported by their parents. FMS were assessed by Test of Gross Motor Development 3. Descriptive statistics and gender differences in children’s meeting the Guidelines and FMS were calculated using t-tests for continuous variables and Chi-square tests for categorical variables. Results: Most preschoolers met the sleep and ST guidelines, but only 22.3% met the PA guidelines; 4% of preschoolers did not meet any of the recommendations, while 9.3% met all three recommendations. Boys reported significantly higher compliance with all combined recommendations. There were positive associations between meeting the PA guidelines and both locomotor (β = 0.49; p p p = 0.02). A significantly negative association was observed between preschoolers’ meeting sleep + ST guidelines and locomotor skills (β = 0.31; p = 0.001). Conclusion: Few preschoolers met all three movement behavior guidelines. The findings suggest that PA levels, especially MVPA, are important for the promotion of FMS. Meanwhile, the impacts of ST and sleep on motor development cannot be neglected

The Association between Leisure-Time Physical Activity Intensity and Duration with the Risk of Mortality in Patients with Chronic Kidney Disease with or without Cardiovascular Diseases

Introduction: For chronic kidney disease (CKD) patients with or without cardiovascular diseases, the associations between leisure-time physical activity intensity (LTPA) and daily exercise time with mortality risk remain unclear. Method: This study enrolled 3279 CKD patients from National Health and Nutrition Examination Survey (NHANES) 2007–2014 survey. Patients were grouped into different groups according to LTPA intensity (none, moderate, vigorous) and duration (0 min, 0–30 min, 30–60 min, >60 min). We selected the confounders based on their connections with the outcomes of interest or a change in effect estimate of more than 10%. Multivariable-adjusted Cox proportional hazards models were used to examine the associations between LTPA and mortality. The three-knot cubic spline (10, 50, and 90%) was employed to investigate the relationship between the dose of LTPA duration and all-cause death. Patients were divided into different groups according to cardiovascular diseases (CVD). Results: A total of 564 all-cause death were recorded in this study. Multivariable Cox regression showed that moderate LTPA was associated with a reduced risk of mortality by 38% (hazard ratio (HR): 0.62, 95% confidence interval (CI): 0.44–0.88) in CKD patients, while vigorous LTPA did not have evident survival benefits (HR: 0.91, 95% CI: 0.46–2.64). Subgroups analysis demonstrated that those who engaged in moderate LTPA have a significantly lower risk of mortality (HR: 0.67, 95% CI: 0.47–0.95) in patients without CVD, while patients complicated with CVD did not benefit from the practice (HR: 0.61, 95% CI: 0.37–1.02). Physical exercise for more than 30 minutes was associated with a lower risk of mortality in general CKD patients (30–60 min: HR: 0.23, 95% CI: 0.09–0.58, >60 min: HR: 0.23, 95% CI: 0.08–0.63) and those without CVD (30–60 min/d: HR: 0.32, 95% CI: 0.12–0.83, >60 min/d: HR: 0.20, 95% CI: 0.06–0.71); however, this positive outcome was not seen in patients complicated with CVD (30–60 min/d: HR: 0.67, 95% CI: 0.11–4.04, >60 min/d: HR: 1.14, 95% CI: 0.14–9.11). Conclusions: Moderate LTPA for more than 30 minutes is associated with a reduced risk of mortality in general CKD patients and those without CVD. However, LTPA did not reduce the risk of mortality in CKD patients complicated with CVD

Characterizing Drug–Target Residence Time with Metadynamics: How To Achieve Dissociation Rate Efficiently without Losing Accuracy against Time-Consuming Approaches

Drug–target residence time plays a vital role in drug efficacy. However, there is still no effective strategy to predict drug residence time. Here, we propose to use the optimized (or minimized) structures derived from <i>holo</i>-state proteins to calculate drug residence time, which could give a comparable or even better prediction accuracy compared with those calculated utilizing a large number of molecular dynamics (MD) structures based on the Poisson process. Besides, in addition to the Poisson process, one may use fewer samples for predicting residence time due to the reason that, in a large extent, the calculated drug residence time is stable and independent of the number of samples used for the prediction. With remarkably reduced computational load, the proposed strategy may be promising for large-scale drug residence time prediction, such as post-processing in virtual screening (VS) and lead compound optimization