Reported is an asymmetric reductive dicarbofunctionalization of unactivated alkenes. Under the catalysis of a Ni/BOX system, various aryl bromides, incorporating a pendant olefinic unit, were ...successfully reacted with an array of primary alkyl bromides in the presence of Zn as a reductant, furnishing a series of benzene‐fused cyclic compounds bearing a quaternary stereocenter in high enantioselectivities. Notably, this reaction avoids the use of pregenerated organometallics and demonstrates high tolerance of sensitive functionalities. The preliminary mechanistic investigations reveal that this Ni‐catalyzed reaction proceeds as a cascade consisting of migratory insertion and cross‐coupling with a nickel(I)‐mediated intramolecular 5‐exo cyclization as the enantiodetermining step.
Ring fusion: A nickel‐catalyzed asymmetric arylalkylation of tethered unactivated alkenes provides benzene‐fused cyclic compounds containing a quaternary stereocenter in a highly enantioselective fashion. The generation of organometallics is not necessary, and the functional‐group tolerance is high.
This paper deals with the periodic solutions problem for impulsive differential equations. By using Lyapunov’s second method and the contraction mapping principle, some conditions ensuring the ...existence and global attractiveness of unique periodic solutions are derived, which are given from impulsive control and impulsive perturbation points of view. As an application, the existence and global attractiveness of unique periodic solutions for Hopfield neural networks are discussed. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed results.
•The e-commerce sales mode and information sharing are considered.•Manufacturer’s investment efficiency affects parties’ sales mode selection.•Information sharing strategy affects parties’ sales mode ...preferences.•E-retailer’s prediction accuracy affects both parties’ optimal decisions.•Players can benefit from more accurate prediction information.
Demand forecasting is important information for all enterprises. Accurate forecast information determines the success of supply chain operations. This paper studies the selection strategy of e-commerce sales mode and information sharing strategy in a dual-channel supply chain. The manufacturer and e-retailer enter a Stackelberg competition. The e-retailer independently decides to share or not share forecasting demand information to the manufacturer. The results show that only if the investment efficiency of the manufacturer’s after-sales service is high, e-retailer is willing to share demand forecasting information. Information sharing does not always add value to the e-retailer, which may lead to the ‘precision trap’ of the e-retailer. Moreover, forecasting accuracy always has a positive impact on the e-retailer’s profit. However, the manufacturer would benefit from more accurate forecasting demand in the case of sharing information. Otherwise, prediction accuracy is negatively correlated with the manufacturer’s profit. Besides, the selection strategy of e-commerce sales mode depends on the level of the manufacturer’s investment efficiency. Specifically, if the manufacturer invests in after-sales service more efficiently, platform sales mode is preferred. If not, they prefer wholesale sales mode.
The iron and steel industry accounts for about 20% of the annual industrial energy utilization. The intensive fossil fuel consumption in steel industry is associated with CO2 emission. In the absence ...of economically feasible and efficient methods for capture and storage of enormous quantities of CO2 emissions from steel industry, the use of biomass products as a source of energy and reducing agents provides a promising alternative solution for green steel production. However, the biomass application in iron and steel industry is still limited and it suffers strong competition from fossil fuels. The challenges of biomass usage in steel industry are included technical and economic aspects which required synergy between steelmaking and bioenergy sectors. Although intensive work has been carried out separately, there is a lack of link between these two vital sectors. The present article provides a comprehensive review of recent research progresses which have been conducted on biomass upgrading and analysing the opportunities and obstacles for biomass implementation in iron and steel industry. In the first part, an overview on the energy consumption and CO2 emissions in different iron and steelmaking routes is clarified. Moreover, the potential approaches of biomass conversion processes and upgrading technologies are reviewed. In the second part, an attention has been paid to the utilization of torrefied/pyrolyzed biomass in the energy-intensive ironmaking processes. Biomass addition to coal blend during cokemaking and its influence on the product coke quality is discussed. The partial and complete substitution of coke breeze with biochar in sintering process and its influence on the product sinter quality is explained. The impact of charcoal top charging or injection into blast furnace has been elaborated. Benefits and limitations of biomass application in each process are thoroughly discussed. In the third part, an economic analysis of biomass implementation for low-carbon steel is addressed.
Herein we report a chromium-catalyzed allylic defluorinative ketyl olefin coupling between aldehydes and α-trifluoromethyl alkenes, which provides novel and efficient access to diverse ...gem-difluorohomoallylic alcohols. Remarkably, the high chemoselectivity of this reaction enables the conversion of the formyl moiety in the presence of various easily reducible functionalities including ketone, organohalides, aziridine, sulfone, alkyne, and unactivated alkene. The utility of this method is demonstrated by various simple derivatizations of the attached hydroxyl group of the coupling products. The preliminary mechanistic investigations suggest a reaction pathway with a rate-limiting C–C forming step followed by facile β-fluoro elimination.
People with autism spectrum disorder (ASD) have cognitive ability, organizational communication, and self-expression difficulties. It is necessary to study their processing and comprehension of what ...they hear; their problem-solving, logic, and understanding of cause-and-effect, inference, and the meaning of proverbs; and their ability to ask and answer questions to assess the cognitive stage of their autism. We designed an organizational sentence menu (OSM) to teach children with ASD to communicate with artificial intelligence (AI) robots (operant interaction for auditory understanding, OIAU). Speech generation devices (SGDs) with various OSM designs were tested on four children with autism spectrum disorder, and their improvement was assessed. We used applied behavioral analysis (ABA) to compare the effects of our interventions using various OSM designs. The results showed that our pedagogical guidance strategies were effective. These strategies incorporated AI robot-supported recommendations for the design of interactive operating interfaces that emerge from a stakeholder perspective. This study provides useful information on alternatives that help children with ASD advance their understanding of social interaction.
The 4+3 annulation of aza‐o‐quinone methides and pyridinium 1,4‐zwitterionic thiolates has been developed for the one‐step synthesis of functionalized 2,3‐unsaturated 4,1‐benzothiazepines under mild ...and metal‐free conditions. The produced 4,1‐benzothiazepines can easily be converted into biologically interesting sulfoxides and sulfones via selective oxidization with m‐CPBA.
In the past decades ancient DNA research has brought numerous insights to archaeological research where traditional approaches were limited. The determination of sex in human skeletal remains is ...often challenging for physical anthropologists when dealing with incomplete, juvenile or pathological specimens. Molecular approaches allow sexing on the basis of sex-specific markers or by calculating the ratio of DNA derived from different chromosomes. Here we propose a novel approach that relies on the ratio of X chromosome-derived shotgun sequencing data to the autosomal coverage, thus establishing the probability of an XX or XY karyotype. Applying this approach to the individuals of the Upper Paleolithic triple burial of Dolní Věstonice reveals that all three skeletons, including the individual DV 15, whose sex has long been debated due to a pathological condition, were male.
Solar‐to‐hydrogen conversion based on photocatalytic and photoelectrocatalytic water splitting is considered as a promising technology for sustainable hydrogen production. Developing earth‐abundant ...H2‐production materials with robust activity and stability has become the mainstream in this field. Due to the unique properties and characteristics, transition metal phosphides (TMPs) have been proven to be high performance co‐catalysts to replace some of the classic precious metal materials in photocatalytic water splitting. In this Minireview, we summarize the recent significant progress of TMPs as cocatalysts for water splitting reaction with high activity and stability. Firstly, the characteristic of TMPs is briefly introduced. Then, we mainly discuss the recent research efforts toward their application as photocatalytic co‐catalysts in photocatalytic H2‐production, O2‐evolution and photoelectrochemical water splitting. Finally, the catalytic mechanism, current existing challenges and future working directions for improving the performance of TMPs are proposed.
What's all the phos about? This Minireview concerns recent progress in metal phosphide‐based heterogeneous photocatalysts for water splitting to produce high‐purity hydrogen. Various systems with optimized or enhanced photocatalytic efficiency are introduced through specific examples. The possible catalytic mechanism, recent challenges, and future research directions for optimizing the performance of metal‐phosphide‐based co‐catalysts are discussed.
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