基于可拓和组合赋权的矿井通风系统优化评价

矿井通风系统具有随机性、模糊性和不确定性等特征,一般单一的赋权评价法难以对其进行准确的优化评价.采用模糊层次分析法和熵权法的组合赋权法不仅可以提升对目标评价的准确性还能避免单一赋权的偶然性和局限性,结合可拓学的优度评价法,依据优度排序,得到最优方案.事实证明,基于组合赋权的可拓评价模型较其他评价方法更为客观,评价结果更加符合实际,可为解决类似优化方案问题提供一种新思路和方法.     

一类具有收获率的脉冲Lotka-Volterra竞争合作系统的八个正概周期解

研究了一类具有收获率的脉冲Lotka-Volterra竞争合作系统的正概周期解.通过利用重合度理论延拓定理、概周期理论和不等式分析技巧,获得了系统至少存在8个正概周期解的充分条件,推广和改进了早期文献的相关结果.     

“禁摩限电”效果综合评价模型

将交通需求级别进行划分后,通过数据包络分析法计算交通需求匹配度和交通运行效率,近乎绝对细化交通运行表现,依据具有时间轴的四维交通状况模拟建立了全新多维度的交通评价体系。此外,利用模糊层次分析法确定道路交通安全评价指标体系中各个指标的权重,同时作出基于差异驱动原理的综合评价。最后,将交通的污染指标提炼为机动车的排放指标和电动车的耗电指标来衡量交通工具对环境的影响。     

Solvable <Emphasis Type="Italic">D</Emphasis><Subscript>2</Subscript>-groups

Let G be a finite group, Irr¹(G) be the set of nonlinear irreducible characters of G and cd¹(G) the set of degrees of the characters in Irr¹(G). A group G is said to be a D₂-group if|cd¹(G)|=|Irr¹(G)|-2. In this paper, we give a complete classification of solvable D₂-groups.     

三核过渡金属配合物在催化反应中的研究进展

多核过渡金属配合物作为一类广泛应用的均相催化剂,其设计灵感往往来自天然酶的多金属活性位点所发挥的重要作用.目前,三核金属配合物作为活化小分子的多金属催化剂受到了广泛的关注.为深入理解三核过渡金属配合物在催化反应中作用特点,对近年报道的代表性三核过渡金属配合物按金属中心进行分类,并对配体环境形成特点及催化应用进行综述.从金属中心出发,讨论了三核过渡金属配合物的几何结构和电子特征;从配体环境出发,总结了关联三个独立的金属位点的配位环境特征;在催化应用方面,重点综述了三核过渡金属配合物在涉及特定化学键活化反应的催化作用机制,最后对三核过渡金属配合物的催化应用前景进行展望.     

Mechanistic insights into methylene blue removal via olive stone-activated carbon: A study on surface porosity and characterization

Global attention is increasingly focused on the adverse health and environmental impacts of textile dyes, marking the necessity for effective and sustainable dye remediation strategies in industrial wastewater. This study introduces a novel, eco-friendly activated carbon produced from olive stones (OLS), a readily available by-product of the olive oil industry. The OLS was chemically activated with H₃PO₄ and KOH, creating two materials: OLS-P and OLS-K, respectively. These were then utilized as cost-effective adsorbents for the removal of methylene blue (MB) dye. The activated materials were characterized via X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), iodine number, and pHpzc analysis, with the zero-point charge determined as approximately pH 1 for OLS-P and pH 8 for OLS-K. Batch adsorption experiments conducted at various temperatures revealed that adsorption process followed the pseudo-second-order kinetic model and the Langmuir isotherm model. Temperature was found to significantly impact adsorption performance, with OLS-K demonstrating a substantial increase in adsorption capacity (q_e) from 6.27 mg/g at 23˚C to 94.7 mg/g at 32 ˚C. Conversely, OLS-P displayed a decrease in q_e from 16.78 mg/g at 23 ˚C to 3.67 mg/g at 32 ˚C as temperature increased. The study highlights the potential of KOH-treated olive stones as a promising, cost-efficient adsorbent for methylene blue remediation from wastewater.     

Modular Synthesis of ortho-Thiolated Aryl Esters Enabled with Thiocarbonate through Catellani Strategy

Herein, we report a palladium/norbornene/copper co-catalyzed single-step approach that merges selective ortho C−H bond esterification with ipso thiolation for construction of synthetically versatile 2-arylthio aryl esters under exceptionally mild conditions. Importantly, this process proceeded in a highly efficient manner, allowing alkoxycarbonyl and thio groups to be installed into one aryl iodides simultaneously by harnessing thiocarbonate as bifunctional reagent. The method has been demonstrated to accommodate good functionalities and features broad substrate scope.     

Rhodium-Catalyzed C8-Alkenylation of Isoquinolones with Maleimides

An efficient Rh(III)-catalyzed C−H alkenylation of N-protected isoquinolone with maleimides is reported. The carbonyl group of isoquinolone acts as an inherent directing group. Various N-substituents in the maleimide, including alkyl, aryl, and even H and −OH, were well tolerated under the developed reaction condition. This protocol showed broad substrate scope, good selectivity, and excellent yields. Hammett plot is also drawn to check the effect of substituents on the reaction progress.     

A Fujiwara-Moritani-Type Alkenylation Using a Traceless Directing Group Strategy: A Rare Example of C−C Bond Formation towards the C2-Carbon of Terminal Alkenes

Herein we report, a rhodium-catalyzed Fujiwara-Moritani-type reaction of unactivated terminal alkenes and benzoic acid derivatives bearing electron donating residues under mild conditions. The acid functionality acts as a traceless directing group delivering products alkenylated in meta-position to the electron donating substituent in contrast to the usually obtained ortho- and para-substitution in Friedel-Crafts-type reactions. Remarkably, the new C−C bond is formed to the C2 of the terminal olefin, in contrast to similar reported transformations. Initially formed mixtures of exo- and endo-double bond isomers can be efficiently isomerized to the more stable endo-products.     

How Ligand Geometry Affects the Reactivity of Co(II) Cyclam Complexes

Cobalt complexes are extensively studied as bioinspired models for non-heme oxygenases as they facilitate both the stabilization and characterization of metal-oxygen intermediates. As an analog to the well-known Co(cyclam) complex Co{N₄} (cyclam=1,4,8,11-tetraazacyclotetradecane), the Co^II complex Co{i-N₄} with the isomeric isocyclam ligand (isocyclam=1,4,7,11-tetraazacyclotetradecane) was synthesized and characterized. Despite the identical N₄ donor set of both complexes, Co{i-N₄} enables the 2e⁻/2H⁺ reduction of O₂ with a lower overpotential (η_eff of 385 mV vs. 540 mV for Co{N₄} ), albeit with a diminished turnover frequency. Characterization of the intermediates formed upon O₂ activation of Co{i-N₄} reveals a structurally identified stable μ-peroxo Co^III dimer as the main product. A superoxo Co^III species is also formed as a minor product, as indicated by EPR spectroscopy. In further reactivity studies, the electrophilicity of these in situ generated Co−O₂ species was demonstrated by the oxidation of the O−H bond of TEMPO−H (2,2,6,6-tetramethylpiperidin-1-ol) via a H atom abstraction process. Unlike the known Co(cyclam), Co{i-N₄} can be employed in oxygen atom transfer reactions oxidizing triphenylphosphine to the corresponding phosphine oxide highlighting the impact of geometrical modifications of the ligand while preserving the ring size and donor atom set on the reactivity of biomimetic oxygen activating complexes.