Mapping the composite nature of clay matrix in mudstones: integrated micromechanics profiling by high-throughput nanoindentation and data analysis.

Mudstones and shales serve as natural barrier rocks in various geoenergy applications. Although many studies have investigated their mechanical properties, characterizing these parameters at the microscale remains challenging due to their fine-grained nature and susceptibility to microstructural damage introduced during sample preparation. This study aims to investigate the micromechanical properties of clay matrix composite in mudstones by combining high-speed nanoindentation mapping and machine learning data analysis. The nanoindentation approach effectively captured the heterogeneity in high-resolution mechanical property maps. Utilizing machine learning-based k-means clustering, the mechanical characteristics of matrix clay, brittle minerals, as well as measurements on grain boundaries and structural discontinuities (e.g., cracks) were successfully distinguished. The classification results were validated through correlation with broad ion beam-scanning electron microscopy images. The resulting average reduced elastic modulus (E r ) and hardness (H) values for the clay matrix were determined to be 16.2 ± 6.2 and 0.5 ± 0.5 GPa, respectively, showing consistency across different test settings and indenter tips. Furthermore, the sensitivity of indentation measurements to various factors was investigated, revealing limited sensitivity to indentation depth and tip geometry (when comparing Cube corner and Berkovich tip in a small range of indentation depth variations), but decreased stability at lower loading rates. Box counting and bootstrapping methods were applied to assess the representativeness of parameters determined for the clay matrix. A relatively small dataset (indentation number = 60) is needed to achieve representativeness, while the main challenges is to cover a representative mapping area for clay matrix characterization. Overall, this study demonstrates the feasibility of high-speed nanoindentation mapping combined with data analysis for micromechanical characterization of the clay matrix in mudstones, paving the way for efficient analysis of similar fine-grained sedimentary rocks. Supplementary Information: The online version contains supplementary material available at 10.1007/s40948-024-00864-9.

Exploring the mediating roles of physical literacy and mindfulness on psychological distress and life satisfaction among college students.

Background: Psychological distress has been a growing challenge to healthy living worldwide. Special attention has been concentrated on examining the cost of psychological distress on the life satisfaction of college students who are vulnerable groups coping with the challenge. The purpose of this study is to explore the roles of physical literacy (PL) and mindfulness in mediating the impact of psychological distress on life satisfaction among college students in China. Methods: A sample of 653 students from six universities across three cities in China participated in an online survey, which included measures of PL, mindfulness, life satisfaction, as well as stress, anxiety, and depression levels. Structural equation modeling (SEM) was implemented to analyze the survey data. Results: The findings of the SEM analysis demonstrated an acceptable model fit (X2/df = 3.63, CFI = 0.951, TLI = 0.940, RMSEA = 0.068, 90% CI = [0.060, 0.075], SRMR = 0.051) with a large effect size (R 2 = 0.36) for life satisfaction, indicating that 36% of the variation in life satisfaction could be explained by the model. In addition, significant partial-mediation effects of PL and mindfulness were observed in the relationship between psychological distress and life satisfaction. These findings provide empirical support for the notion that interventions targeting PL and mindfulness practices may effectively enhance well-being and alleviate psychological distress among college students. Furthermore, this study suggests that integrating PL and mindfulness components into physical education and activity programs could be beneficial in meeting individuals' holistic health needs.

Mediation Impact of Physical Literacy and Activity Between Psychological Distress and Life Satisfaction Among College Students During COVID-19 Pandemic.

The study aims to examine the mediation effects of physical literacy and physical activity behavior in a relationship between psychological distress and life satisfaction among Chinese college students during the real-life Coronavirus disease pandemic (COVID-19) circumstance. This study implemented a cross-sectional design, and 1,516 participants from 12 universities participated in this study. Structural equation modeling was used to examine a hypothesized model. The findings indicated an acceptable model fit (X 2[61] = 508.2, Comparative Fit Index [CFI] = 0.958, Tucker Lewis Index [TLI] = 0.946, Root Mean Square Error of Approximation [RMSEA] = 0.076, 90% CI [0.070, 0.082], Standardized Root Mean Square Residual [SRMR] = 0.047). The results indicated that college students with low participation in physical activity could experience less than healthy living conditions. The findings offered empirical support to the theory that physical literacy could advance individuals' healthy living by promoting physical activity participation. The study suggested that educational institutions and physical activity programs should cultivate individuals' physical literacy in order to promote lifelong healthy living.

Impact of urbanization on the food-water-land-ecosystem nexus: A study of Shenzhen, China.

The food-water-land-ecosystem (FWLE) nexus is fundamental for achieving sustainable development. This study examines the influence of urbanization on the FWLE nexus. Toward this end, land was deemed as an entry point. Therefore, the impact of urbanization on the nexus was explored based on changes in land use. We selected Shenzhen, a city in China, as the study area. First, a land change modeler was employed to analyze historical land-use changes from 2000 to 2010, to build transition potential submodels, and to project future land-use patterns for 2030 under a business-as-usual scenario. Second, based on land-use maps, we assessed habitat quality, water yield, and water supply from 2000 to 2030 using Integrated Valuation of Ecosystem Services and Tradeoffs. Moreover, crop production was estimated according to statistical materials. Finally, the study presents the analyses and discussion of the impacts of urbanization on ecosystem services related to the FWLE nexus. The results of land-use changes indicated that a significant expansion of artificial surfaces occurred in Shenzhen with varying degrees of decrease in cultivated land, forest, and grassland. Furthermore, habitat quality, water supply, and crop production decreased evidently due to rapid urbanization. In contrast, the total water yield indicated an upward trend owing to the increased water yield from increasing artificial surfaces, whereas water yield from other land-use areas declined, such as the forest and grassland. The results demonstrated a significant positive correlation between artificial surfaces and total water yield. However, negative correlations were observed in the interaction among habitat quality, water supply, and crop production. The study presented temporal and spatial assessments to provide an effective and convenient means of exploring the interactions and tradeoffs within the FWLE nexus, which, thus, contributed to the sustainable transformation of urbanization.

Bifurcations in a fractional-order neural network with multiple leakage delays.

This paper expatiates the stability and bifurcation for a fractional-order neural network (FONN) with double leakage delays. Firstly, the characteristic equation of the developed FONN is circumspectly researched by employing inequable delays as bifurcation parameters. Simultaneously the bifurcation criteria are correspondingly extrapolated. Then, unequal delays-spurred-bifurcation diagrams are primarily delineated to confirm the precision and correctness for the values of bifurcation points. Furthermore, it lavishly illustrates from the evidence that the stability performance of the proposed FONN can be demolished with the presence of leakage delays in accordance with comparative studies. Eventually, two numerical examples are exploited to underpin the feasibility of the developed theory. The results derived in this paper have perfected the retrievable outcomes on bifurcations of FONNs embodying unique leakage delay, which can nicely serve a benchmark deliberation and provide a comparatively credible guidance for the influence of multiple leakage delays on bifurcations of FONNs.

Oscillatory dynamics of an intravenous glucose tolerance test model with delay interval.

Type 2 diabetes mellitus (T2DM) has become prevalent pandemic disease in view of the modern life style. Both diabetic population and health expenses grow rapidly according to American Diabetes Association. Detecting the potential onset of T2DM is an essential focal point in the research of diabetes mellitus. The intravenous glucose tolerance test (IVGTT) is an effective protocol to determine the insulin sensitivity, glucose effectiveness, and pancreatic ß-cell functionality, through the analysis and parameter estimation of a proper differential equation model. Delay differential equations have been used to study the complex physiological phenomena including the glucose and insulin regulations. In this paper, we propose a novel approach to model the time delay in IVGTT modeling. This novel approach uses two parameters to simulate not only both discrete time delay and distributed time delay in the past interval, but also the time delay distributed in a past sub-interval. Normally, larger time delay, either a discrete or a distributed delay, will destabilize the system. However, we find that time delay over a sub-interval might not. We present analytically some basic model properties, which are desirable biologically and mathematically. We show that this relatively simple model provides good fit to fluctuating patient data sets and reveals some intriguing dynamics. Moreover, our numerical simulation results indicate that our model may remove the defect in well known Minimal Model, which often overestimates the glucose effectiveness index.

A mathematical model with pulse effect for three populations of the giant panda and two kinds of bamboo.

A mathematical model for the relationship between the populations of giant pandas and two kinds of bamboo is established. We use the impulsive perturbations to take into account the effect of a sudden collapse of bamboo as a food source. We show that this system is uniformly bounded. Using the Floquet theory and comparison techniques of impulsive equations, we find conditions for the local and global stabilities of the giant panda-free periodic solution. Moreover, we obtain sufficient conditions for the system to be permanent. The results provide a theoretical basis for giant panda habitat protection.

Efficacy of domestic bisoprolol,enalapril and nifedipine retard in mild to moderate hypertension: a randomized double-blind multicenter clinical trial in China.

OBJECTIVE: To compare the efficacy and tolerability of bisoprolol, enalapril and nifedipine retard in the treatment of mild to moderate essential hypertension. METHODS: This is a randomized, double-blind, multicenter clinical trial. 331 patients with mild to moderate hypertension in the army troop were randomly allocated to receive domestic bisoprolol ( n =110,5 mg/d),enalapril ( n =111,10 mg/d) and nifedipine retard ( n =110,20 mg/day). Total duration of active drug treatment was 4 weeks. RESULTS: The total efficacy rates of domestic bisoprolol, enalapril and nifedipine retard were 80.0%, 82.0% and 81.8% respectively P > 0.05 . The incidences of adverse events were 4.5%, 8.1% and 19.1% (P < 0.01 ) in patients of bisoloprol, enalapril and nifedipine retard groups respectively. The adverse effects were mild in all the three groups. CONCLUSIONS: Domestic bisoprolol, enalapril and nifedipine retard are effective and well-tolerated in patients with mild to moderate essential hypertension. The occurrence of adverse effects were least in the bisoprolol group and most in the nifedipine retard group.

[The plasma levels of proinsulin and true insulin and the effects of ramipril in hypertension].

OBJECTIVE: To explore the dynamic changes of plasma proinsulin (PI) and true insulin (TI) and their relation with essential hypertension (EH) as well as to evaluate the therapeutic effect of ramipril. METHODS: PI, TI and immunoreactive insulin (IRI) were measured in 44 cases of EH, 24 normal subjects and 21 cases of EH before and after treatment with ramipril. RESULTS: The mean plasma level of PI and IRI in EH was significantly higher than that in the control group (P < 0.01); there was no significant difference in the level of TI (P > 0.05). PI was positively related to TI, There was no significant relation between PI with SBP and DBP. Plasma concentration of IRI and PI (P < 0.05), decreased remarkably, but the level of TI remained unchanged after therapy with ramipril (n = 21). CONCLUSION: The plasma concentration of PI is elevated in patients with EH due probably to impaired function of beta-cells of the pancreatic islets. Ramipril can decrease the level of PI and improve pancreatic beta cell function.