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Dynamic material constants obtained by wave-based methods are different from their static counterparts. Constraining rock's elastic constants' dynamic-to-static ratios (Rij) are important for understanding the geomechanical properties of earth's materials, particularly in the context of hydraulic fracturing that requires the knowledge of shale's static elastic constants. Conducting experiments with dynamic and elastic constants' anisotropy, on top of their pressure dependency, properly accounted for is challenging. Here, we measure suites of dynamic and static elastic constants, with anisotropy fully accounted for, on the shale samples extracted from the Duvernay unconventional reservoir; a comprehensive set of geochemical/petrophysical measurements are obtained too. We observe that the dynamic-to-static ratios are generally not sensitive to the increasing pressures at σ  > 50 MPa; we do not find a correlation with the samples' mineral contents either. However, we find that Rij strongly correlates to the dynamic elastic constants except for the R 11. The correlation between Rij , particularly Ri3, and the dynamic elastic constants can be explained by the sedimentary rocks' compactness and the horizontal void spaces parallel to the rock's laminated bedding planes. [ABSTRACT FROM AUTHOR]

The precise relocation of seismic events is critical for many engineering projects. Swarms of minor or micro earthquakes typically reveal stress concentration and spots of greater seismic hazards. Particularly in the context of deep underground mining, advanced techniques that can accurately relocate microseismicities are urgently in demand. Here, we developed a neural network-based modeling training method that can precisely relocate seismicities and invert for velocities at the same time, with preconfigured receiver network locations. Our model can be iteratively improved with field recorded data. We showed that, with roughly eight iterations, we can reasonably resolve for the earthquake locations for both clusters of events, namely spatially distributed with linear pattern or randomly scattered. Our initially trained model, which only focused on events that had a linear distribution pattern, was used as the base for the training of the subsequent models which could better resolve for randomly scattered event locations. Although we stopped at the eighth iteration, the process reported here can be continued, as the model will have a better performance with more iterations. [ABSTRACT FROM AUTHOR]

With more companies entering the realm of electric vertical take-off and landing (eVTOL) and governments enacting policies to support the development of low-altitude economies, the commercial potential of eVTOL is being recognized by the public. However, true commercialization is still a long way off. This article analyzes the technologies, product features, potential markets, and government policies related to eVTOL and constructs a four-stage, four-layer Policy–Technology Roadmap (P-TRM) model to guide the R&D process of eVTOL. Then, it is transformed into a system structural model, and the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method is used to identify several key nodes in the R&D process. Utilizing the Technology Adoption Life Cycle (TALC) theory for interpretation and analysis, the article concludes by proposing strategies in product, technology, and policy support for how eVTOL can successfully cross the chasm. This preliminary analysis of the development path, key nodes, and necessary measures for crossing the chasm provides insights for the R&D and commercialization of eVTOL. [ABSTRACT FROM AUTHOR]

Rhubarb is a significant medicinal herb in China. Its adulteration or fabrication is common in the market. Consequently, it is necessary to establish a comprehensive identification method to accurately identify genuine rhubarb and its adulterants. In this study, the sequences of chloroplast genes rps3-rpl22 and rpl16 from three genuine rhubarbs (Rheum tanguticum, Rh. palmatum and Rh. officinale) and their adulterants (Rumex japonicus and Rumex spp.) were amplified, sequenced and subjected to genetic analyses. The genetic distances for rps3-rpl22 and rpl16 between genuine rhubarbs and their adulterants showed that there was an evident barcoding gap, which allowed the adulterants to be distinguished from the genuine rhubarbs, as demonstrated by a neighbor joining tree. Additionally, Rh. officinale could be distinguished from the other two genuine rhubarbs. The anthraquinone, sennoside, polysaccharide and protein contents were analyzed in seven rhubarbs using high-performance liquid chromatography and ultraviolet spectrophotometry. Cluster and principal component analyses results showed that Rh. tanguticum and Rh. palmatum could be effectively distinguished. The study suggests that DNA barcoding based on rps3-rpl22 and rpl16 sequences coupled with multiple-indicator quantification can be successfully applied to identify rhubarb species and distinguish among the three genuine rhubarbs, and this can provide a scientific foundation for rhubarb quality assurance. [ABSTRACT FROM AUTHOR]

Introduction: Rhubarb is a frequently used and beneficial traditional Chinese medicine. Wild resources of these plants are constantly being depleted, meaning that rhubarb products have been subjected to an unparalleled level of adulteration. Consequentially, reliable technology is urgently required to verify the authenticity of rhubarb raw materials and commercial botanical drugs. Methods: In this study, the barcode-DNA high-resolution melting (Bar-HRM) method was applied to characterize 63 rhubarb samples (five Polygonaceae species: Rheum tanguticum , Rh. palmatum , Rh. officinale , Rumex japonicus and Ru. sp.) and distinguish the rhubarb contents of 24 traditional Chinese patent medicine (TCPM) samples. Three markers, namely ITS2, rbcL and psbA-trnH , were tested to assess the candidate DNA barcodes for their effectiveness in distinguishing rhubarb from its adulterants. A segment from ITS2 was selected as the most suitable mini-barcode to identify the botanical drug rhubarb in TCPMs. Then, rhubarbs and TCPM samples were subjected to HRM analysis based on the ITS2 barcode. Results: Among the tested barcoding loci, ITS2 displayed abundant sites of variation and was effective in identifying Polygonaceae species and their botanical origins. HRM analysis based on the ITS2 mini-barcode region successfully distinguished the authenticity of five Polygonaceae species and eight batches of TCPMs. Of the 18 TCPM samples, 66.7 % (12 samples) were identified as containing Rh. tanguticum or Rh. officinale . However, 33.3 % were shown to consist of adulterants. Conclusions: These results demonstrated that DNA barcoding combined with HRM is a specific, suitable and powerful approach for identifying rhubarb species and TCPMs, which is crucial to guaranteeing the security of medicinal plants being traded internationally., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Shen, Zhang, Qiu, Yang, Lu, Li, Zhang, Tang, Wang, Zhu, Bao and Ding.)