Precisely introducing two similar functional groups into bulk chemical alkenes represents a formidable route to complex molecules. Especially, the selective activation of two electrophiles is in crucial demand, yet challenging for cross-electrophile-coupling. Herein, we demonstrate a redox-mediated electrolysis, in which aryl nitriles are both aryl radical precursors and redoxmediators, enables an intermolecular alkene 1,2-diarylation with a remarkable regioselectivity, thereby avoiding the involvement of transition-metal catalysts. This transformation utilizes cyanoarene radical anions for activating various aryl halides (including iodides, bromides, and even chlorides) and affords 1,2-diarylation adducts in up to 83 % yield and > 20 : 1 regioselectivity with more than 80 examples, providing a feasible approach to complex bibenzyl derivatives.
Wind-induced sediment suspension and nutrient release is an important source for shallow eutrophic lakes. This work studies the quantitative relationship between wind speed and sediment release rate in Meiliang Bay of Lake Taihu, China, using field observations and indoor simulations. Natural wind, water flow, and water quality conditions were synchronously monitored to establish the relationship between wind speed and sediment release rate. Sediment suspension processes under different wind speeds were also simulated in a specially designed reactor. We then established the relationship between natural wind speed and indoor-simulated sediment release rate through hydrodynamic conditions (expressed using water shear stress). The indoor experiment was a supplement to the field observations. The results showed that (1) the critical wind speeds at which sediment became suspended and demonstrated maximum suspension were approximately 3-4 and 8 m s(-1), respectively; (2) the relationship between wind speed and suspended sediment (SS), total nitrogen (TN), and total phosphorous (TP) release rate could be expressed by exponential functions (SS release rate: y = 1.287e(0.177x) , R (2) = 0.981; TN release rate: y = 7.55e(0.363x), R (2) = 0.981; TP release rate: y = 0.381e(0.186x), R (2) = 0.945); and (3) the critical (wind speed, 8 m s(-1)) release rates of SS, TN, and TP were 1000, 5.8, and 2.2 g m(-2) day(-1), while the maximum (wind speed, 16 m s(-1)) rates were 5000, 24.7, and 5.4 g m(-2) day(-1), respectively.
It is of great significance to understand the extent and distribution of bamboo for its valuable ecological services and economic benefits. However, it is challenging to map bamboo using remote sensing images over a large area because of the similarity between bamboo and other vegetation types, the availability of clear optical images, huge workload of image processing, and sample collection. In this study, we use the Landsat 8 times series images archive to map bamboo forests in China via the Google Earth engine. Several spectral indices were calculated and used as classification features, including the normalized difference vegetation index (NDVI), the normalized difference moisture index (NDMI) and textural features of the gray-level co-occurrence matrix (GLCM). We found that the bamboo forest covered an area of 709.92 × 104 hectares, with the provinces of Fujian, Jiangxi, and Zhejiang containing the largest area concentrations. The bamboo forest map was accurate and reliable with an average producer’s accuracy of 89.97%, user’s accuracy of 78.45% and kappa coefficient of 0.7789. In addition, bamboo was mainly distributed in forests with an elevation of 300–1200 m above sea level, average annual precipitation of 1200–1500 mm and average day land surface temperature of 19–25 °C. The NDMI is particularly useful in differentiating bamboo from other vegetation because of the clear difference in canopy moisture content, whilst NDVI and elevation are also helpful to improve the bamboo classification accuracy. The bamboo forest map will be helpful for bamboo forest industry planning and could be used for evaluating the ecological service of the bamboo forest.
Precisely introducing two similar functional groups into bulk chemical alkenes represents a formidable route to complex molecules. Especially, the selective activation of two electrophiles is in crucial demand, yet challenging for cross‐electrophile‐coupling. Herein, we demonstrate a redox‐mediated electrolysis, in which aryl nitriles are both aryl radical precursors and redox‐mediators, enables an intermolecular alkene 1,2‐diarylation with a remarkable regioselectivity, thereby avoiding the involvement of transition‐metal catalysts. This transformation utilizes cyanoarene radical anions for activating various aryl halides (including iodides, bromides, and even chlorides) and affords 1,2‐diarylation adducts in up to 83 % yield and >20 : 1 regioselectivity with more than 80 examples, providing a feasible approach to complex bibenzyl derivatives.
Contributing to the United Nations 2030 Sustainable Development Goals (SDGs) within Target 11.4 “Strengthen efforts to protect and safeguard the world’s cultural and natural heritage”, it is critical to monitor the spatial and temporal stabilities of cultural heritages. The study of the interactive relationship between earthquakes and the protection of cultural heritages needs to be strengthened. On 27 September 2021, the destructive Mw 5.9 Arkalochori earthquake occurred ~25 km away from the city of Heraklion (Greece) where the Heraklion City Wall (HCW), a representative cultural heritage of Greece and Europe, was located. This offered a proper case to investigate the shortcomings aforementioned. Here, we intend to set up and answer the following three questions (Whether, Where and What, 3Ws): Whether there were impacts on the HCW caused by the Arkalochori earthquake? Where did the maximum deformation occur? What was the relationship between seismic deformation between the epicenter and the HCW over time? We performed two-dimensional (2D) InSAR measurements for both co-seismic and post-seismic deformations using the ascending and descending Sentinel-1A SAR images. The spatial-temporal characteristics of Up–Down (UD) and East–West (EW) were revealed. The 2D co-seismic deformation field showed that the near-filed deformations were dominating compared with the deformations at the HCW, the UD deformation was mainly featured with subsidence with a maximum value of ~21 cm, the EW deformation was ~9 cm westward and ~10 cm eastward. The time-series measurements showed that: (1) temporally, the HCW responded quickly to the Arkalochori earthquake, and the accumulative deformations at the seven different bastions of the HCW showed the same trend as the near-field area over time. (2) Spatially, the closer to the Mw 5.9 epicenter, the larger the deformations that occurred. (3) The EW and UD deformation trends of the HCW that were consistent with the Mw 5.9 epicenter were interrupted at the middle time spot (22 January 2022), indicating the influence of another earthquake sequence consisting of eight earthquakes with magnitudes larger than 3.5 that happened on 16–18 January 2022. Respectively, to summarize and address the aforementioned 3Ws based on the post-seismic analysis accomplished by the MSBAS method, the Arkalochori earthquake did affect the HCW; besides, the influences of the ~13 km earthquake sequence were also detected; the nearest part to the epicenter suffered the most; the deformation trends of the HCW were approximately the same with the epicenter area of the Arkalochori earthquake both in the UD and EW directions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.