213 research outputs found

    Human activities accelerated the degradation of saline seepweed red beaches by amplifying top‐down and bottom‐up forces

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    Salt marshes dominated by saline seepweed (Suaeda heteroptera) provide important ecosystem services such as sequestering carbon (blue carbon), maintaining healthy fisheries, and protecting shorelines. These salt marshes also constitute stunning red beach landscapes, and the resulting tourism significantly contributes to the local economy. However, land use change and degradation have led to a substantial loss of the red beach area. It remains unclear how human activities influence the top‐down and bottom‐up forces that regulate the distribution and succession of these salt marshes and lead to the degradation of the red beaches. We examined how bottom‐up forces influenced the germination, emergence, and colonization of saline seepweed with field measurements and a laboratory experiment. We also examined whether top‐down forces affected the red beach distribution by conducting a field survey for crab burrows and density, laboratory feeding trials, and waterbird investigations. The higher sediment accretion rate induced by human activities limited the establishment of new red beaches. The construction of tourism facilities and the frequent presence of tourists reduced the density of waterbirds, which in turn increased the density of crabs, intensifying the top‐down forces such as predators and herbivores that drive the degradation of the coastal red beaches. Our results show that sediment accretion and plant–herbivory changes induced by human activities were likely the two primary ecological processes leading to the degradation of the red beaches. Human activities significantly shaped the abundance and distribution of the red beaches by altering both top‐down and bottom‐up ecological processes. Our findings can help us better understand the dynamics of salt marshes and have implications for the management and restoration of coastal wetlands

    MUBen: Benchmarking the Uncertainty of Pre-Trained Models for Molecular Property Prediction

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    Large Transformer models pre-trained on massive unlabeled molecular data have shown great success in predicting molecular properties. However, these models can be prone to overfitting during fine-tuning, resulting in over-confident predictions on test data that fall outside of the training distribution. To address this issue, uncertainty quantification (UQ) methods can be used to improve the models' calibration of predictions. Although many UQ approaches exist, not all of them lead to improved performance. While some studies have used UQ to improve molecular pre-trained models, the process of selecting suitable backbone and UQ methods for reliable molecular uncertainty estimation remains underexplored. To address this gap, we present MUBen, which evaluates different combinations of backbone and UQ models to quantify their performance for both property prediction and uncertainty estimation. By fine-tuning various backbone molecular representation models using different molecular descriptors as inputs with UQ methods from different categories, we critically assess the influence of architectural decisions and training strategies. Our study offers insights for selecting UQ and backbone models, which can facilitate research on uncertainty-critical applications in fields such as materials science and drug discovery

    Promotion of Au nanoparticles on carbon frameworks for alkali-free aerobic oxidation of benzyl alcohol

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    We synthesized a series of modified Co-ZIF-67 materials with tunable morphology to support fine Au nanoparticles for the alkali-free aerobic oxidation of benzyl alcohol. Structure promotion was performed using Stöber silica as a hard template, which was subsequently removed by NaOH etching before gold immobilization. The texture structure of Au/(Si)C was greatly improved with increasing surface area and volume. CoOx was simultaneously introduced into the carbon shell from the Co-ZIF-67 precursor, which consequently facilitated the specific Au-support interaction via bimetallic synergy. XRD, XPS, and TEM images demonstrated the redispersion of both Au and CoOx as well as the electronic delivery between metals. Analysis of the chemical and surface composition suggested a surface rich in AuΎ+ with abundant lattice oxygen contributed by CoOx in the final Au/(Si)C, which improved the transformation rate of benzyl alcohol even in an alkali-free condition. Au/(Si)C with finely dispersed Au particles showed excellent catalytic performance in the alkali-free environment, with 89.3% benzyl conversion and 74.5% benzaldehyde yield under very mild conditions

    Study on the influencing factors of digital transformation of construction enterprises from the perspective of dual effects—a hybrid approach based on PLS-SEM and fsQCA

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    The digital transformation of Chinese construction enterprises is crucial for achieving sustainable and high-quality development in the construction industry. However, there is still a lack of in-depth research on the impact mechanism of digital transformation in construction enterprises. The purpose of this study is to explore the multiple influencing factors and complex causal relationships of digital transformation in construction enterprises and promote the deep integration of digitalization and construction enterprises. To this end, based on the dual-effect perspective (net effect perspective of a single influencing factor and configuration effect perspective of multiple influencing factors), using the “technology–organization–environment” framework (TOE framework) to construct a research model of influencing factors for digital transformation in construction enterprises. A sample of 236 construction enterprise managers was surveyed, and partial least squares structural equation modeling (PLS-SEM) and fuzzy set qualitative comparative analysis (fsQCA) methods were used to empirically analyze the dual effects of influencing factors for digital transformation in construction enterprises. The results show that: (1) from the net effect perspective, there are seven factors that significantly impact digital transformation in construction enterprises; (2) from the configuration effect perspective, there are three paths that can achieve high-level digital transformation in construction enterprises, and one path that leads to low-level digital transformation; (3) from the dual-effect perspective, top management support and policy support are key factors for digital transformation in Chinese construction enterprises. The research results enrich the relevant research on digital transformation in construction enterprises and provide a reference basis for promoting digital transformation in construction enterprises

    circFBXW7 attenuates malignant progression in lung adenocarcinoma by sponging miR-942-5p

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    Background: As a type of non-coding RNA, circular RNAs (circRNAs) are considered to be functional molecules associated with human cancers. An increasing number of circRNAs have been verified in malignant progression in a number of cancers. The circRNA, circFBXW7, has been proven to play an important role in tumor proliferation and metastasis. However, whether circFBXW7 influences progression in lung adenocarcinoma (LUAD) remains unclear. Methods: Quantitative real-time reverse transcriptase PCR (qRT-PCR) was used to verify circFBXW7 in LUAD cell lines and LUAD tissues. Kaplan-Meier analysis was then used to compare the disease-free survival (DFS) and overall survival (OS) of these LUAD patients. The biological function of circFBXW7 was examined by overexpression and knockdown of circFBXW7 using MTT assay, EdU assay, wound-healing assay, and Transwell in vitro assays. To explore the mechanism of the circFBXW7, RNA pull-down assay, dual luciferase reporter assay, and RNA immunoprecipitation (RIP) assay were employed to examine the interaction between circFBXW7 and miR-942-5p. Western blot was used to study the fundamental proteins associated with the epithelial-mesenchymal transition (EMT) pathway. In vivo studies with BALB/c nude mice subcutaneously injected with cells stably overexpressing circFBXW7 were performed to further validate the in vitro results. Results: circFBXW7 was downregulated in LUAD cell lines and tissues, and LUAD patients with lower levels had shorter DFS and OS. The in vitro study showed that circFBXW7 overexpression inhibited proliferation and migration of A549 and HCC2279 cell lines. These results were confirmed by circFBXW7 knockdown, which showed the reverse effect. The in vivo model showed that the circRNA levels influenced the tumor growth. Finally, we determined that circFBXW7 target miRNA-942-5p which regulates the EMT gene BARX2. The modulation of circFBXW7 levels produced significant changes in EMT genes in vitro and in vivo. Conclusions: Our findings showed that circFBXW7 inhibits proliferation and migration by controlling the miR-942-5p/BARX2 axis in LUAD cell lines and its levels correlates with patient survival suggesting that regulating circFBXW7 could have therapeutic value in treating LUAD patients

    Active-Site Models of Streptococcus pyogenes Cas9 in DNA Cleavage State

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    CRISPR-Cas9 is a powerful tool for target genome editing in living cells. Significant advances have been made to understand how this system cleaves target DNA. However, due to difficulty in determining active CRISPR-Cas9 structure in DNA cleavage state by X-ray and cryo-EM, it remains uncertain how the HNH and RuvC nuclease domains in CRISPR-Cas9 split the DNA phosphodiester bonds with metal ions and water molecules. Therefore, based on one-and two-metal-ion mechanisms, homology modeling and molecular dynamics simulation (MD) are suitable tools for building an atomic model of Cas9 in the DNA cleavage state. Here, by modeling and MD, we presented an atomic model of SpCas9-sgRNA-DNA complex with the cleavage state. This model shows that the HNH and RuvC conformations resemble their DNA cleavage state where the active-sites in the complex coordinate with DNA, Mg2+ ions and water. Among them, residues D10, E762, H983 and D986 locate at the first shell of the RuvC active-site and interact with the ions directly, residues H982 or/and H985 are general (Lewis) bases, and the coordinated water is located at the positions for nucleophilic attack of the scissile phosphate. Meanwhile, this catalytic model led us to engineer new SpCas9 variant (SpCas9-H982A + H983D) with reduced off-target effects. Thus, our study provides new mechanistic insights into the CRISPR-Cas9 system in the DNA cleavage state, and offers useful guidance for engineering new CRISPR-Cas9 editing systems with improved specificity

    Long-lived charge separation following pump-wavelength-dependent ultrafast charge transfer in graphene/WS2 heterostructures

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    Van der Waals heterostructures consisting of graphene and transition metal dichalcogenides have shown great promise for optoelectronic applications. However, an in-depth understanding of the critical processes for device operation, namely, interfacial charge transfer (CT) and recombination, has so far remained elusive. Here, we investigate these processes in graphene-WS2 heterostructures by complementarily probing the ultrafast terahertz photoconductivity in graphene and the transient absorption dynamics in WS2 following photoexcitation. We observe that separated charges in the heterostructure following CT live extremely long: beyond 1 ns, in contrast to ~1 ps charge separation reported in previous studies. This leads to efficient photogating of graphene. Furthermore, for the CT process across graphene-WS2 interfaces, we find that it occurs via photo- thermionic emission for sub-A-exciton excitations and direct hole transfer from WS2 to the valence band of graphene for above-A-exciton excitations. These findings provide insights to further optimize the perform ance of optoelectronic devices, in particular photodetection
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