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β-Nucleosides and their analogs are dominant clinically-used antiviral and antitumor drugs. α-Nucleosides, the anomers of β-nucleosides, exist in nature and have significant potential as drugs or drug carriers. Currently, the most widely used methods for synthesizing β- and α-nucleosides are via N-glycosylation and pentose aminooxazoline, respectively. However, the stereoselectivities of both methods highly depend on the assisting group at the C2' position. Herein, we report an additive-controlled stereodivergent iodocyclization method for the selective synthesis of α- or β-nucleosides. The stereoselectivity at the anomeric carbon is controlled by the additive (NaI for β-nucleosides; PPh 3 S for α-nucleosides). A series of β- and α-nucleosides are prepared in high yields (up to 95%) and stereoselectivities (β:α up to 66:1, α:β up to 70:1). Notably, the introduced iodine at the C2' position of the nucleoside is readily functionalized, leading to multiple structurally diverse nucleoside analogs, including stavudine, an FDA-approved anti-HIV agent, and molnupiravir, an FDA-approved anti-SARS-CoV-2 agent., (© 2023. The Author(s).)

Since China's reform and opening up, the social economy has achieved rapid development, followed by a sharp increase in carbon dioxide (CO 2 ) emissions. Therefore, at the 75th United Nations General Assembly, China proposed to achieve carbon peaking by 2030 and carbon neutrality by 2060. The research work on advance forecasting of CO 2 emissions is essential to achieve the above-mentioned carbon peaking and carbon neutrality goals in China. In order to achieve accurate prediction of CO 2 emissions, this study establishes a hybrid intelligent algorithm model suitable for CO 2 emissions prediction based on China's CO 2 emissions and related socioeconomic indicator data from 1971 to 2017. The hyperparameters of Least Squares Support Vector Regression (LSSVR) are optimized by the Adaptive Artificial Bee Colony (AABC) algorithm to build a high-performance hybrid intelligence model. The research results show that the hybrid intelligent algorithm model designed in this paper has stronger robustness and accuracy with relative error almost within ±5% in the advance prediction of CO 2 emissions. The modeling scheme proposed in this study can not only provide strong support for the Chinese government and industry departments to formulate policies related to the carbon peaking and carbon neutrality goals, but also can be extended to the research of other socioeconomic-related issues., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2022 Pan Wang et al.)

Pollen tube integrity, growth and guidance are crucial factors in plant sexual reproduction. Members of the plant Skewed5 (SKU5) Similar (SKS) family show strong similarity to multicopper oxidases (MCOs), but they lack conserved histidines in MCO active sites. The functions of most SKS family members are unknown. Here, we show that Arabidopsis pollen-expressed SKS11 and SKS12 play important roles in pollen tube integrity, growth and guidance. The sks11sks12 mutant exhibited significantly reduced male fertility. Most of the pollen from sks11sks12 plants burst when germinated, and the pollen tubes grew slowly and exhibited defective growth along the funiculus and micropyle. SKS11-GFP and SKS12-mCherry were detected at the cell wall in pollen tubes. The contents of several cell wall polysaccharides and arabinogalactans were decreased in the pollen tube cell walls of sks11sks12 plants. Staining with a reactive oxygen species (ROS)-sensitive dye and use of the H 2 O 2 sensor HyPer revealed that the ROS content in the pollen tubes of sks11sks12 plants was remarkably reduced. SKS11 444His-Ala , in which the last conserved histidine was mutated, could restore the mutant phenotypes of sks11sks12. Thus, SKS11/12 are required for pollen tube integrity, growth and guidance possibly by regulating the ROS level and cell wall polysaccharide deposition or remodeling in pollen tubes., (© 2021 Society for Experimental Biology and John Wiley & Sons Ltd.)