Deterministic assembly of grassland soil microbial communities driven by climate warming amplifies soil carbon loss.

Perturbations in soil microbial communities caused by climate warming are expected to have a strong impact on biodiversity and future climate-carbon (C) feedback, especially in vulnerable habitats that are highly sensitive to environmental change. Here, we investigate the impact of four-year experimental warming on soil microbes and C cycling in the Loess Hilly Region of China. The results showed that warming led to soil C loss, mainly from labile C, and this C loss is associated with microbial response. Warming significantly decreased soil bacterial diversity and altered its community structure, especially increasing the abundance of heat-tolerant microorganisms, but had no effect on fungi. Warming also significantly increased the relative importance of homogeneous selection and decreased "drift" of bacterial and fungal communities. Moreover, warming decreased bacterial network stability but increased fungal network stability. Notably, the magnitude of soil C loss was significantly and positively correlated with differences in bacterial community characteristics under ambient and warming conditions, including diversity, composition, network stability, and community assembly. This result suggests that microbial responses to warming may amplify soil C loss. Combined, these results provide insights into soil microbial responses and C feedback in vulnerable ecosystems under climate warming scenarios.

Acid rain reduced soil carbon emissions and increased the temperature sensitivity of soil respiration: A comprehensive meta-analysis.

Soil respiration the second-largest carbon flux in terrestrial ecosystems, has been extensively studied across a wide range of biomes. Surprisingly, no consensus exist on how acid rain (AR) impacts the spatiotemporal pattern of soil respiration. Therefore, we conducted a meta-analysis using 318 soil respiration and 263 soil respiration temperature sensitivity (Q10) data points obtained from 48 studies to assess the impact of AR on soil respiration components and their Q10. The results showed that AR reduced soil total respiration (Rt) and soil autotrophic respiration (Ra) by 7.41 % and 20.75 %, respectively. As the H+ input increased, the response rates of Ra to AR (RR-Ra) and soil heterotrophic respiration (Rh) to AR (RR-Rh) decreased and increased, respectively. With increased AR duration, the RR-Ra increased, whereas the RR-Rh did not change. AR increased the Q10 of Rt (Rt-Q10) and Rh (Rh-Q10) by 1.92 % and 9.47 %, respectively, and decreased the Q10 of Ra (Ra-Q10) by 2.77 %. Increased mean annual temperature, mean annual precipitation, and initial soil organic carbon increased the response rate of Ra-Q10 to AR (RR-Ra-Q10) and decreased the response rate of Rh-Q10 to AR (RR-Rh-Q10). However, as the AR frequency and initial soil pH increased, both RR-Ra-Q10 and RR-Rh-Q10 also increased. In summary, AR decreased Rt but increased Q10, likely due to soil acidification (soil pH decreased by 7.84 %), reducing plant root biomass (decreased by 5.67 %) and soil microbial biomass (decreased by 5.67 %), changing microbial communities (increased fungi to bacteria ratio of 15.91 %), and regulated by climate, vegetation, soil and AR regimes. To the best of our knowledge, this is the first study to reveal the large-scale, varied response patterns of soil respiration components and their Q10 to AR. It highlights the importance of applying the reductionism theory in soil respiration research to enhance our understanding of soil carbon cycling processes with in the context of global climate change.

[Stoichiometric Imbalance of Abandoned Grassland Under Precipitation Changes Regulate Soil Respiration].

As a key factor of global climate change, precipitation can affect soil respiration. Microorganisms are the key drivers of soil respiration, but the relationship between microbial stoichiometry and respiration in vulnerable habitat areas under different precipitation gradients is unclear. In this study, five precipitation gradients were simulated on a typical abandoned grassland in the loess hilly region. Soil respiration, nutrients, microbial biomass, and extracellular enzymes were measured, and the microbial measurement characteristics were calculated. The results showed that:①soil respiration (SR) increased significantly under rainfed treatment but decreased significantly under D50 treatment. ②Precipitation changes affected the stoichiometric imbalance, and the N:P imbalance of the active resource pool presented a u-shaped trend, whereas the C:P imbalance changed significantly only in 2019, with a trend of P50>P25>CK>D25>D50. Additionally, the stoichiometric imbalance was caused by the soil stoichiometry. In 2019, the C:P imbalance of the active resource pool showed a trend of P50>P25>CK>D25>D50, whereas the N:P imbalance of the active resource pool showed a u-shaped trend, and the stoichiometric imbalance was caused by soil stoichiometry changes. ③Soil ß-1,4-glucosidase (BG) enzyme decreased with increasing precipitation, and the sum activities of ß-1,4-N-acetylglucosaminidase (NAG) and leucine aminopeptidase (LAP) significantly decreased during two years of rainfall reduction treatment. The activity of alkaline phosphatase (ALP) significantly increased under increasing rainfall but significantly decreased under decreasing rainfall. BG:(NAG+LAP) and BG:ALP were significantly decreased under increasing precipitation conditions but significantly increased under decreasing precipitation conditions. ④The partial least squares path model (PLS-PM) showed that precipitation had an impact on soil respiration through influencing C:P stoichiometric imbalance and soil enzyme stoichiometric ratio. These results highlight the importance of stoichiometric imbalances in regulating soil respiration and may help predict how they are caused by precipitation change control carbon cycling and nutrient flow in terrestrial ecosystems.

Significantly Affected Lubrication Behavior of Silicone Oil Lubricated Si3N4/Glass Contact after Cleaning with Different Solvents.

Conventional methyl silicone oils have poor lubricating properties in boundary lubrication regions, particularly for ceramic/oxide point contact lubrication. In this study, the residues of various organic solvents on the surfaces of Si3N4 spheres/glass disks were used to determine their effect on the lubricating properties of silicone oil 200. The minute ethanol residues significantly enhanced the antifriction and antiwear properties of silicone oil. Compared to the blank sample, the coefficient of friction (COF) and wear volume of silicone oil 200 with the residual ethanol friction pair were reduced by >40% and >98%, respectively. Being immiscible with silicone oil, the minute ethanol residues also removed impurities from the glass surface and maintained a clean interface, thus effectively blocking direct interactions between the friction pair interfaces. In addition, the residual ethanol reduced the atomic force microscope probe-to-glass surface adhesive force in the silicone oil 200 environment, thus allowing it to maintain low COF and wear rates over a broader range of speeds, loads, and times. In contrast to previous work, this study is the first to effectively regulate the lubrication properties of silicone oil using a residual organic solvent. The findings further verified that the adsorption of vapor molecules can significantly alter the surface forces between interfaces. Thus, adjusting the adhesion force through trace amounts of organic solvent residues may provide novel research inputs, thereby guiding the expansion and scope of silicone oil lubrication applications.

Social Support, Mindfulness, and Job Burnout of Social Workers in China.

In the last 20 years, amid extensive social and economic reforms, China's social structure and community life have changed considerably. A large number of social workers are needed to provide many more social services to community residents. The central government has issued many policies to rapidly develop human service organizations and increase the number of social workers. Thus, by the end of 2019, the number of social workers has reached more than 1.5 million in China. At the same time, local governments have issued many policies to promote an increase in the number of social workers. According to statistics from the Chengdu Civil Affairs Bureau, from 2010 to 2021, the number of social workers in Chengdu City increased, remarkably, from 553 to 17,622. Although the number of social workers has increased rapidly, some problems still exist. According to a survey by the Chengdu Social Workers Association, the turnover rate of social workers has reached approximately 20% in Chengdu City in 2018. Therefore, we aim to determine what influences social workers' job burnout. Through regression analysis and mediation effect tests, we found the following: First, when controlling for gender, age, education, and workday, social support of social workers had a significant negative impact on job burnout ( ß = - 0.376). Second, the mindfulness of social workers had a significant negative impact on job burnout ( ß = - 0.320). Third, the mindfulness of social workers played a mediating role between social support and job burnout. The mediating effect was -0.116 (p < 0.001). Fourth, among the three dimensions of social support, mindfulness played a partially mediating role in family support and other support. The mediating effect between other support, which is the support from leaders and colleagues, and job burnout was the strongest, with a mediating effect of -0.109 (p < 0.001). In other words, the support provided by agency leaders and colleagues can maximize the level of mindfulness of social workers, thereby reducing social workers' job burnout most effectively. We can thus reduce social workers' job burnout by improving their level of mindfulness and the social support for them in China.

Imaging dynamic three-dimensional traction stresses.

Traction stress between contact objects is ubiquitous and crucial for various physical, biological, and engineering processes such as momentum transfer, tactile perception, and mechanical reliability. Newly developed techniques including electronic skin or traction force microscopy enable traction stress measurement. However, measuring the three-dimensional distribution during a dynamic process remains challenging. Here, we demonstrated a method based on stereo vision to measure three-dimensional traction stress with high spatial and temporal resolution. It showed the ability to image the two-stage adhesion failure of bionic microarrays and display the contribution of elastic resistance and adhesive traction to rolling friction at different contact regions. It also revealed the distributed sucking and sealing effect of the concavity pedal waves that propelled a snail crawling in the horizontal, vertical, and upside-down directions. We expected that the method would advance the understanding of various interfacial phenomena and greatly benefit related applications across physics, biology, and robotics.

Job Demands and Resources, Burnout, and Psychological Distress of Social Workers in China: Moderation Effects of Gender and Age.

Social work is a fast-growing profession in China, with the workforce numbering approximately 1.2 million in 2018. Studies have shown, however, that social workers in China experience high burnout rates and significant psychological distress. Analyzing data collected from 897 social workers in Chengdu, China, we applied the job demands and resources (JD-R) theory to examine the effects of JD-R on burnout and psychological distress in social workers, as well as whether these relations are moderated by gender and age. Results supported a dual process by which JD-R affected both social workers' burnout and psychological distress through health impairment and motivation processes. Job demands (JD) were associated with high burnout and psychological distress. Meanwhile, job resources (JR) were associated with reduced burnout and psychological distress. Results indicated that JR had greater effects on burnout and distress than did JD. Women and younger professionals appeared to be affected most by JD and psychological distress. The findings support a need for interventions that buffer the effects of JD-R on burnout and psychological distress in social workers in China, focusing on women and younger professionals.

Effects of Abrasive Particles on Liquid Superlubricity and Mechanisms for Their Removal.

Liquid superlubricity results in a near-frictionless lubrication state, which can greatly reduce friction and wear under aqueous conditions. However, during the running-in process, a large number of abrasive particles are generated, and because these may lead to a breakdown in superlubricity performance, they should be effectively removed. In this paper, the morphology, size, and composition of abrasive particles were verified using scanning electron microscopy with energy-dispersive X-ray spectroscopy, and their influence on liquid superlubricity was explored through friction tests. Subsequently, different solvents were used to remove the abrasive particles, and the optimal cleaning process was determined by macroscopic tribo-tests and microscopic analysis. Finally, droplet-spreading experiments and a force-curve analysis were carried out to understand the abrasive-particle removal mechanism by different solvents. We found that SiO2 was the main component in the abrasive particles, and micron-sized SiO2 particles resulted in random "wave peaks" in the coefficient of friction and, thus, the superlubricity. Absolute ethanol + ultrapure water was determined to be the optimal solvent for effectively removing abrasive particles from friction-pair surfaces and helped the lubricant in exhibiting an ultralow friction coefficient for long periods of time. We proposed a "wedge" and "wrap" model to explain the abrasive-particle removal mechanism of different solvents. The SiO2 removal mechanism outlined in this study can be applied under aqueous conditions to improve the stability and durability of liquid superlubricity in practical engineering applications.