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Abstract Algae have been considered as a promising biodiesel feedstock. One of the major factors affecting large-scale algae technology application is poor wintering cultivation performance. In this study, an integrated approach is investigated combining freshwater microalgae Chlorella zofingiensis wintering cultivation in pilot-scale photobioreactors with artificial wastewater treatment. Mixotrophic culture with the addition of acetic acid (pH-regulation group) and autotrophic culture (control group) were designed, and the characteristics of algal growth, lipid and biodiesel production, and nitrogen and phosphate removal were examined. The results showed that, by using acetic acid three times per day to regulate pH at between 6.8 and 7.2, the total nitrogen (TN) and total phosphate (TP) removal could be increased from 45.2% to 73.5% and from 92.2% to 100%, respectively. Higher biomass productivity of 66.94 mg L−1 day−1 with specific growth rate of 0.260 day−1 was achieved in the pH-regulation group. The lipid content was much higher when using acetic acid to regulate pH, and the relative lipid productivity reached 37.48 mg L−1 day−1. The biodiesel yield in the pH-regulated group was 19.44% of dry weight, with 16–18 carbons as the most abundant composition for fatty acid methyl esters. The findings of the study prove that pH adjustment using acetic acid is efficient in cultivating C. zofingiensis in wastewater in winter for biodiesel production and nutrient reduction.

Abstract Algae have been considered as a promising biodiesel feedstock. One of the major factors affecting large-scale algae technology application is poor wintering cultivation performance. In this study, an integrated approach is investigated combining freshwater microalgae Chlorella zofingiensis wintering cultivation in pilot-scale photobioreactors with artificial wastewater treatment. Mixotrophic culture with the addition of acetic acid (pH-regulation group) and autotrophic culture (control group) were designed, and the characteristics of algal growth, lipid and biodiesel production, and nitrogen and phosphate removal were examined. The results showed that, by using acetic acid three times per day to regulate pH at between 6.8 and 7.2, the total nitrogen (TN) and total phosphate (TP) removal could be increased from 45.2% to 73.5% and from 92.2% to 100%, respectively. Higher biomass productivity of 66.94 mg L−1 day−1 with specific growth rate of 0.260 day−1 was achieved in the pH-regulation group. The lipid content was much higher when using acetic acid to regulate pH, and the relative lipid productivity reached 37.48 mg L−1 day−1. The biodiesel yield in the pH-regulated group was 19.44% of dry weight, with 16–18 carbons as the most abundant composition for fatty acid methyl esters. The findings of the study prove that pH adjustment using acetic acid is efficient in cultivating C. zofingiensis in wastewater in winter for biodiesel production and nutrient reduction.

AbstractClimate change globally affects soil microbial community assembly across ecosystems. However, little is known about the impact of warming on the structure of soil microbial communities or underlying mechanisms that shape microbial community composition in subtropical forest ecosystems. To address this gap, we utilized natural variation in temperature via an altitudinal gradient to simulate ecosystem warming. After 6 years, microbial co‐occurrence network complexity increased with warming, and changes in their taxonomic composition were asynchronous, likely due to contrasting community assembly processes. We found that while stochastic processes were drivers of bacterial community composition, warming led to a shift from stochastic to deterministic drivers in dry season. Structural equation modelling highlighted that soil temperature and water content positively influenced soil microbial communities during dry season and negatively during wet season. These results facilitate our understanding of the response of soil microbial communities to climate warming and may improve predictions of ecosystem function of soil microbes in subtropical forests.

AbstractClimate change globally affects soil microbial community assembly across ecosystems. However, little is known about the impact of warming on the structure of soil microbial communities or underlying mechanisms that shape microbial community composition in subtropical forest ecosystems. To address this gap, we utilized natural variation in temperature via an altitudinal gradient to simulate ecosystem warming. After 6 years, microbial co‐occurrence network complexity increased with warming, and changes in their taxonomic composition were asynchronous, likely due to contrasting community assembly processes. We found that while stochastic processes were drivers of bacterial community composition, warming led to a shift from stochastic to deterministic drivers in dry season. Structural equation modelling highlighted that soil temperature and water content positively influenced soil microbial communities during dry season and negatively during wet season. These results facilitate our understanding of the response of soil microbial communities to climate warming and may improve predictions of ecosystem function of soil microbes in subtropical forests.

Abstract The interfaces between n-type silicon (n-Si) and metal electrode contact have enormous influences on the performance and stability of silicon solar cells. Recently, it has been proven that the carrier-selective contact (CSC) is an effective strategy to improve the device efficiency. Herein, a solution-processed and annealing-free zirconium acetylacetonate (ZrAcac) layer is used as an electron-selective contact for fabricating efficient crystalline silicon solar cell. This contact scheme enabled a reduction in both the contact resistivity and the work function at the interface between n-Si and Al, which can be attributed to the dipole formation at the contact interface induced by charge transfer. The application of this ZrAcac based contact was shown to consistently improve all device parameters reaching a maximum power conversion efficiency of 17.8% with a high fill factor of 81.1%, and greatly improve the device stability. This work demonstrated that the ZrAcac layer can provide sufficient energy alignment and enhanced carrier selectivity for efficient and stable photovoltaic devices.

Abstract The interfaces between n-type silicon (n-Si) and metal electrode contact have enormous influences on the performance and stability of silicon solar cells. Recently, it has been proven that the carrier-selective contact (CSC) is an effective strategy to improve the device efficiency. Herein, a solution-processed and annealing-free zirconium acetylacetonate (ZrAcac) layer is used as an electron-selective contact for fabricating efficient crystalline silicon solar cell. This contact scheme enabled a reduction in both the contact resistivity and the work function at the interface between n-Si and Al, which can be attributed to the dipole formation at the contact interface induced by charge transfer. The application of this ZrAcac based contact was shown to consistently improve all device parameters reaching a maximum power conversion efficiency of 17.8% with a high fill factor of 81.1%, and greatly improve the device stability. This work demonstrated that the ZrAcac layer can provide sufficient energy alignment and enhanced carrier selectivity for efficient and stable photovoltaic devices.

AbstractThe timing of phenological events is highly sensitive to climate change, and may influence ecosystem structure and function. Although changes in flowering phenology among species under climate change have been reported widely, how species‐specific shifts will affect phenological synchrony and community‐level phenology patterns remains unclear. We conducted a manipulative experiment of warming and precipitation addition and reduction to explore how climate change affected flowering phenology at the species and community levels in an alpine meadow on the eastern Tibetan Plateau. We found that warming advanced the first and last flowering times differently and with no consistent shifts in flowering duration among species, resulting in the entire flowering period of species emerging earlier in the growing season. Early‐flowering species were more sensitive to warming than mid‐ and late‐flowering species, thereby reducing flowering synchrony among species and extending the community‐level flowering season. However, precipitation and its interactions with warming had no significant effects on flowering phenology. Our results suggest that temperature regulates flowering phenology from the species to community levels in this alpine meadow community, yet how species shifted their flowering timing and duration in response to warming varied. This species‐level divergence may reshape flowering phenology in this alpine plant community. Decreasing flowering synchrony among species and the extension of community‐level flowering seasons under warming may alter future trophic interactions, with cascading consequences to community and ecosystem function.