Altitudinal patterns of alpine soil ammonia-oxidizing community structure and potential nitrification rate

Nitrogen availability limits the net primary productivity in alpine meadows on the Qinghai-Tibetan Plateau, which is regulated by ammonia-oxidizing microorganisms. However, little is known about the elevational patterns of soil ammonia oxidizers in alpine meadows. Here, we investigated the potential nitrification rate (PNR), abundance, and community diversity of soil ammonia-oxidizing microorganisms along the altitudinal gradient between 3,200 and 4,200 m in Qinghai-Tibetan alpine meadows. We found that both PNR and amoA gene abundance declined from 3,400 to 4,200 m but lowered at 3,200 m, possibly due to intense substrate competition and biological nitrification inhibition from grasses. The primary contributors to soil nitrification were ammonia-oxidizing archaea (AOA), and their proportionate share of soil nitrification increased with altitude in comparison to ammonia-oxidizing bacteria (AOB). The alpha diversity of AOA increased by higher temperature and plant richness at low elevations, while decreased by higher moisture and low legume biomass at middle elevations. In contrast, the alpha diversity of AOB increased along elevation. The elevational patterns of AOA and AOB communities were primarily driven by temperature, soil moisture, and vegetation. These findings suggest that elevation-induced climate changes, such as shifts in temperature and water conditions, could potentially alter the soil nitrification process in alpine meadows through changes in vegetation and soil properties, which provide new insights into how soil ammonia oxidizers respond to climate change in alpine meadows.IMPORTANCEThe importance of this study is revealing that elevational patterns and nitrification contributions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) communities were primarily driven by temperature, soil moisture, and vegetation. Compared to AOB, the relative contribution of AOA to soil nitrification increased at higher elevations. The research highlights the potential impact of elevation-induced climate change on nitrification processes in alpine meadows, mediated by alterations in vegetation and soil properties. By providing new insights into how ammonia oxidizers respond to climate change, this study contributes valuable knowledge to the field of microbial ecology and helps predict ecological responses to environmental changes in alpine meadows.

Triboelectrification-Induced Electricity in Self-Healing Hydrogel for Mechanical Energy Harvesting and Ultra-sensitive Pressure Monitoring

Triboelectric nanogenerators (TENGs) have shown huge application potential in the fields of micro-nano energy harvesting and multifunctional sensing. However, the damage of triboelectric material is one of the challenges for their practical applications. Herein, we fabricated a flexible TENG employing self-healing hydrogel and fluorinated ethylene propylene film as triboelectric materials for mechanical energy harvesting and pressure monitoring. The prepared hydrogel not only has excellent flexibility, transparency, and self-healing property but also exhibits good mechanical property without plastic deformation and damage under a large stretchable strain of 200%. The output electric signals of TENGs are as high as 33.0 V and 3 μA under a contact frequency of 0.40 Hz and a pressure of 2.9 N, respectively, which can charge a capacitor of 0.22 μF to 24.3 V within 300 s. Note that the voltage retention rate of TENGs after self-healing is up to 88.0%. Moreover, hydrogel-based TENGs can act as a wearable pressure sensor for monitoring human motion, exhibiting a high sensitivity of 105.9 mV/N or 1.73 nA/N under a contact frequency of 0.40 Hz. This research provides a reference roadmap for designing TENGs and self-powered pressure sensors with flexibility, self-healing, and robustness.