1,724,072 research outputs found
Copper-Catalyzed Intermolecular Heck-Like Coupling of Cyclobutanone Oximes Initiated by Selective C−C Bond Cleavage
No full textThe first example of intermolecular olefination of cyclobutanone oximes with alkenes via selective C−C bond cleavage leading to the synthesis of nitriles in the presence of a cheap copper catalyst is reported. The procedure is distinguished by mild and safe reaction conditions that avoid ligand, oxidant, base, or toxic cyanide salt. A wide scope of cyclobutanones and olefin coupling components can be used without compromising efficiency and scalability. The alternative visible-light-driven photoredox process for this coupling reaction was also uncovered
Single-Electron-Transfer-Induced C(sp3)-N Couplings via C-C Bond Cleavage of Cycloketoxime Esters
No full textA practical single-electron-transfer-induced selective C(sp3)-N coupling of cycloketoximes with anilines via C-C bond cleavage under copper-catalytic and synergetic photoredox/copper-catalytic reaction systems has been uncovered. These two powerful and simple protocols demonstrated excellent selectivity and good functional group compatibility without any base or ligand control. Preliminary mechanistic experiments indicated that a radical-mediated process was involved in these transformations
Modeling Delayed Flow Liquefaction Initiation after Cyclic Loading
No full textGround shaking during earthquakes can be a prominent cause of strength loss in loose saturated soils. In some cases, uncontrolled pore pressure build-up and liquefaction may occur with a time lag with respect to strong ground motion, especially when the time-dependent properties of the soil interact with the constraints brought by undrained and/or partially drained conditions. Here a rate-dependent law based on the critical state theory has been used to replicate the cyclic response of sand by taking into account density effects. The model equations have been inspected to define indices of delayed undrained instability. Then, the model has been calibrated by considering laboratory tests for both monotonic and cyclic undrained loading on loose Hostun sand. Numerical simulations of undrained creep stages following cyclic loading have been performed to illustrate the transition from stable to unstable creep as a function of the number of cycles, thus providing a conceptual framework to evaluate the risk of delayed flow liquefaction in loose sandy deposits
SYNERGISING LIVESTOCK AND AGRICULTURAL BY-PRODUCTS FOR BIOENERGY PRODUCTION: AN INTEGRATED 20-YEAR FORECAST USING ARTIFICIAL INTELLIGENCE TECHNIQUES
No full textAligning with global renewable energy strategies and sustainable agricultural practices, this research showcases a pioneering study on using agricultural and livestock by-products for bioenergy production. We detailed a 20-year forecast to evaluate the bioenergy potential from agricultural waste in Jianghan Plain, China. By integrating diverse datasets, including climate and environmental data, satellite imagery, policy directives, and field surveys, the study employs Artificial Neural Networks (ANN) for precise bioenergy potential predictions in crop residues and future trends in manure production. Results indicate an average annual bioenergy potential of 4.37×1011 kJ from 2001 to 2020, with projections indicating an increase to 5.33×1011 kJ by 2030. The findings illustrate a substantial bioenergy potential with a significant shift from crop straws to livestock manure as the mixed primary sources, underscoring the need for localised bioenergy strategies. This research offers valuable insights into sustainable bioenergy utilisation, contributing to the discourse on renewable energy and climate change mitigation
Transition-metal-catalyzed Chelation-assisted C-H Functionalization of Aromatic Substrates
No full textIn the past decade, transition-metal-catalyzed C-H activations have been very popular in the research field of organometallic chemistry, and have been considered as efficient and convenient strategies to afford complex natural products, functional advanced materials, fluorescent compounds, and pharmaceutical compounds. In this account, we begin with a brief introduction to the development of transition-metal-catalyzed C-H activation, especially the development of transition-metal-catalyzed chelation-assisted C-H activation. Then, a more detailed discussion is directed towards our recent studies on the transition-metal-catalyzed chelation-assisted oxidative C-H/C-H functionalization of aromatic substrates bearing directing functional groups. Transition-metal-catalyzed chelation-assisted C-H activation provides atom- and step-economical approaches for the construction of functional compounds. In this account, a more detailed discussion is directed towards our recent studies of the transition-metal-catalyzed chelation-assisted C-H/C-H functionalization of aromatic substrates bearing directing functional groups
Renewable energy communities in rural areas: A comprehensive overview of current development, challenges, and emerging trends
No full textAchieving environmental and economic stability amid climate change requires renewable energy technologies. This review analyses 86 articles on rural energy communities, highlighting key technological, economic, and social drivers of their growth and sustainability. Findings show that rural energy development (38%), community engagement (36%), and agricultural integration (26%) are key focus areas, supported by drivers like technological innovation, regulatory frameworks, and community participation. Emerging trends reveal a shift from localised solutions to integrated hybrid systems and smart grids across three stages (2004–2024). Cross-country comparisons indicate varied regional priorities, with environmental benefits emphasised in China, Thailand, and Italy, and economic gains in the U.S., Poland, and India. Main challenges include financial constraints (21%), infrastructure (35%), regulation (44%), and participation (52%). Core elements for development are resilience, scalability, and innovation, with strong correlations (R2 > 0.80) between resilience, economic benefits, and social engagement. This review underscores the need for innovation, policy support, and community involvement to foster resilient, scalable rural energy communities, promoting sustainability and energy security
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
