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Allylic amines are prevalent and vital structural components present in many bioactive compounds and natural products. Additionally, they serve as valuable intermediates and building blocks, with wide‐ranging applications in organic synthesis. However, direct α‐C(sp3)−H alkenylation of feedstock amines, particularly for the preparation of α‐alkenylated cyclic amines, has posed a longstanding challenge. Herein, we present a general, mild, operationally simple, and transition‐metal‐free α‐alkenylation of various readily available amines with alkenylborate esters in excellent E/Z ‐ and diastereoselectivities. This method features good compatibility with water and oxygen, broad substrate scope, and excellent functional group tolerance, thereby enabling the late‐stage modification of various complex molecules. Mechanistic studies suggest that the formation of a photoactive electron donor‐acceptor complex between 2‐iodobenzamide and the tetraalkoxyborate anion, which subsequently undergoes photoinduced single electron transfer and intramolecular 1,5‐hydrogen atom transfer to generate the crucial α‐amino radicals, is the key to success of this chemistry. [ABSTRACT FROM AUTHOR]

Allenes represent a distinctive class of organic molecules characterized by their unique physical and chemical properties. Among them, chiral allenes play a significant role in modern chemistry. They not only serve as pivotal frameworks for natural products and drug molecules but also are essential building blocks in organic synthesis. Over the years, numerous remarkable and efficient methods have been developed for the synthesis of chiral allenes. Notably, the catalytic synthesis of chiral allenes using transition metals in conjunction with chiral ligands has garnered considerable attention. This review paper aims to provide an overview of recent advancements in the synthesis of chiral allenes through asymmetric 1,4‐difunctionalization of 1,3‐enynes, in which two distinct strategies including non‐radical and radical processes are highlighted. [ABSTRACT FROM AUTHOR]

Iridium- and ruthenium-based materials show high activity for oxygen evolution reaction (OER) in acidic media while Ru-based catalysts exhibit low stability, but Ir-based materials are limited by their high cost and low reserves. The rational design of the OER electrocatalysts to balance activity, stability, and cost is facing a challenge. Herein, we report a strategy to synthesize Ir-RuOx@WO3 catalyst using a low-temperature wet reflux method to deposit Ir-RuOx nanoparticles on ultrafine WO3 nanowires. Due to the metal–metal support interaction (MMSI) between Ir-RuOx and WO3, the abundant hydroxyl groups on the surface, and the protection of active sites by the mild catalyst synthesis method, Ir-RuOx@WO3 demonstrates the OER activity with a low overpotential of 148 mV at 10 mA/cm2 while the total precious metal usage is only 7.673 wt % (2.990 wt % Ir and 4.647 wt % Ru). Besides, with Ru activating the valence state of Ir to improve the activity and Ir stabilizing the Ru site to improve the stability, Ir-RuOx@WO3 achieved relative activity-stability balance as there was no noticeable degradation when operating at 10 mA/cm2 for 12 h. This study presents design concepts of acidic OER catalysts to balance activity, stability, and cost, promoting the widespread use of PEMWE technology in industrial settings. [ABSTRACT FROM AUTHOR]

Determination of rock mass deformation modulus (Erm) is an important but very challenging task in rock mechanics and rock engineering. Direct measurements of Erm by in-situ tests are expensive, time-consuming, and sometimes even impossible. Since the nondestructive and easy geophysical method is commonly used to measure the P-wave velocity (Vp) in the field, the study has developed an empirical correlation between Erm and Vp based on 834 collected datasets by considering both inherent and transformation uncertainties. The information criteria are employed to select the best model for deriving a general empirical correlation. The maximum likelihood estimation (MLE) method and computational intelligence techniques like particle swarm optimisation (PSO), artificial bee colony (ABC), and differential evolution (DE) algorithms are used to specify the incorporated parameters of each candidate model. Based on the derived general empirical equation, a Bayesian equivalent sample approach using Markov Chain Monte Carlo (MCMC) simulation is applied to conduct probabilistic characterisation of Erm by combining prior knowledge and project-specific observed Vp data. Comparative studies of the results from theory and in-situ measured Erm values suggest that the proposed method is effective and validate the applicability of the derived general empirical correlation. [ABSTRACT FROM AUTHOR]

The absorption and metabolism of indigestible dietary glycans play a crucial role in maintaining the integrity of the intestinal barrier and shaping the gut microbiota. Three chemically modified products of xylan, including carboxymethylated xylan, xylan–zinc complex, and carboxymethylated xylan–zinc complex, were synthesized using xylan from sugarcane bagasse. The potential effects of xylan before and after modification on the intestinal barriers and intestinal microbiota of mice were subsequently investigated and compared, revealing distinct changes in the gut microbiota of mice. The results suggest that the chemically modified xylan products have the potential to induce specific regulatory functions on the gut microbiota. [ABSTRACT FROM AUTHOR]