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Over the last few decades, the ecological quality of the Qinghai–Tibet Plateau (QTP) has significantly changed due to climate warming, humidification, and increasing human activities. Thus, evaluating this region's ecological quality and dominant factors is crucial for sustainable development. In this study, the changes in the ecological quality on the QTP from 2000 to 2020 were evaluated based on aggregated indices and Sen–MK trend analyses, and the dominant factors affecting the ecological quality of the QTP were quantitatively analyzed using decision tree classification. The results revealed that (1) the ecological quality of the QTP exhibited an overall high trend in the east and a low pattern in the west; (2) the ecological quality of the QTP significantly increased from 2000 to 2020, and human activities were the dominant factors causing this change; and (3) the changes in the ecological quality and dominant factors exhibited obvious spatiotemporal heterogeneity. The area with an improved ecological quality occurred mainly in the northern QTP region. It was governed by human activities and precipitation. In contrast, the area with a deteriorated ecological quality occurred largely in the southern QTP region and was dominated by human activities and temperature. The 2000–2010 period was the most significant period of heterogeneity regarding of ecological quality and its driving factors. (4) The change in the ecological quality was mainly affected by the synergistic relationship between human activities and climate change in this region, which encompassed multiple dominant factors. This study provides important information on the spatiotemporal heterogeneity of ecological quality change and its dominant factors on the QTP and offers systematic guidance for the planning and implementation of ecological protection projects.

Combined heterotrophic and autotrophic denitrification (HAD) is a sustainable and practical method for removing nitrate from organic-limited wastewater. However, the active microorganisms responsible for denitrification in wastewater treatment have not been clearly identified. In this study, a combined microelectrolysis, heterotrophic, and autotrophic denitrification (CEHAD) process was established. DNA-based stable isotope probing was employed to identify the active denitrifiers in reactors fed with either 13C-labeled inorganic or organic carbon sources. The total nitrogen removal efficiencies reached 87.2–92.8% at a low organic carbon concentration (20 mg/L COD). Real-time polymerase chain reaction of the nirSgene as a function of the DNA buoyant density following the ultracentrifugation of the total DNA indicated marked 13C-labeling of active denitrifiers. High-throughput sequencing of the fractionated DNA in H13CO3–/12CH312COO–-fed and H12CO3–/13CH313COO–-fed reactors revealed that Thermomonas-like phylotypes were labeled by 13C-bicarbonate, while Thauera-like and Comamonas-like phylotypes were labeled by 13C-acetate. Meanwhile, Arenimonas-like and Rubellimicrobium-like phylotypes were recovered in the “heavy” DNA fractions from both reactors. These results suggest that nitrate removal in CEHAD is catalyzed by various active microorganisms, including autotrophs, heterotrophs, and mixotrophs. Our findings provide a better understanding of the mechanism of nitrogen removal from organic-limited water and wastewater and can be applied to further optimize such processes.

Based on the self-similarity property of fractal, two types of fractal gratings are produced according to the production and addition operations of multiple periodic gratings. Fresnel diffractions of fractal grating are analyzed theoretically, and the general mathematic expressions of the diffraction intensity distributions of fractal grating are deduced. The gray-scale patterns of the 2D diffraction distributions of fractal grating are provided through numerical calculations. The diffraction patterns take on the periodicity along the longitude and transverse directions. The 1D diffraction distribution at some certain distances shows the same structure as the fractal grating. This indicates that the self-image of fractal grating is really formed in the Fresnel diffraction region. The experimental measurement of the diffraction intensity distribution of fractal grating with different fractal dimensions and different fractal levels is performed, and the self-images of fractal grating are obtained successfully in experiments. The conclusions of this paper are helpful for the development of the application of fractal grating.

MicroRNAs (miRNAs) are a class of small non-coding RNAs that play important regulatory roles in gene expression in plants and animals. The biogenesis of miRNAs involves the transcription of primary miRNAs (pri-miRNAs) by RNA polymerase II (RNAPII) and subsequent processing by Dicer or Dicer-like (DCL) proteins. Here we show that the Elongator complex is involved in miRNA biogenesis in Arabidopsis. Disruption of Elongator reduces RNAPII occupancy at miRNA loci and pri-miRNA transcription. We also show that Elongator interacts with the DCL1-containing Dicing complex and lack of Elongator impairs DCL1 localization in the nuclear Dicing body. Finally, we show that pri-miRNA transcripts as well as DCL1 associate with the chromatin of miRNA genes and the chromatin association of DCL1 is compromised in the absence of Elongator. Our results suggest that Elongator functions in both transcription and processing of pri-miRNAs and probably couples these two processes.