Solubility-Boosted Molecular Sieving-Based Separation for Purification of Acetylene in Core–Shell IL@MOF Composites

Considering the small amount of CO₂ as a contaminant in industrial gas mixtures, developing CO₂-selective adsorbents exhibit advantages in directly obtaining pure C₂H₂ in one-step to reduce the energy consumption. However, it is still a great challenge due to the essential molecular feature of C₂H₂, including the triple bond and high polarizability. Herein, a simple but effective CO₂-facilitated transport strategy is presented to realize the overwhelming adsorption of CO₂ over C₂H₂ by constructing core–shell composite structures using ionic liquid (IL) and metal-organic framework (MOF). With the aid of excellent solubility of CO₂ in IL and almost total exclusion of C₂H₂, the obtained materials boost molecular sieving-based separation of CO₂/C₂H₂. Density functional theory calculations combining molecular dynamic simulations revealed the solution-diffusion mechanism for CO₂, which is rarely reported in solid adsorbents. Ideal adsorbed solution theory selectivity for CO₂/C₂H₂ with 1/1 and 1/3 volume ratios can reach over 10⁴ and 4000 at 100 kPa with a high CO₂ uptake of 40.3 cm³ g⁻¹, superior to those of the reported materials so far. More importantly, this solution-based separation strategy can avoid the difficulty for precise control of the regulation of adsorbent structure, which may be beneficial to practical production.     

In Situ Non-Topotactic Reconstruction-Induced Synergistic Active Centers for Polysulfide Cascade Catalysis

Most reported catalysts for lithium-sulfur battery can work for only one of the multiple elementary reactions, thereby resulting in the gradual enrichment of unconverted polysulfides at the catalytic centers and aggravating the shuttle effect. Herein, the concept of cascade catalysis based on a ternary heterostructure, which divides sulfur redox reactions into distinct steps by multiple catalytic centers, is proposed to realize the tandem reduction of Li₂S₈ to Li₂S. As a proof of concept, the ternary heterostructure Na_0.67Ni_0.25Mn_0.75O₂(NNMO)-MnS₂-Ni₃S₄ achieved by in situ non-topotactic electrochemical reconstruction successfully integrates three types of active centers into one structure to achieve cascade catalysis. More specifically, NNMO acts as an adsorption mediator to effectively capture polysulfides, MnS₂ functions better in catalyzing the conversion of polysulfides into Li₂S₄ and Ni₃S₄ demonstrates an enhanced catalytic effect for Li₂S precipitation. This synergistic cascade catalysis originates primarily from the dynamic energy-level matching between the metal d-band center and the lowest unoccupied molecular orbital of the polysulfides, affording appropriate molecular orbital hybridization and facile interfacial electron transition and thus endowing favorable sulfur reduction kinetics. Eventually, the NNMO-MnS₂-Ni₃S₄/S composite electrode exhibits excellent rate performance and high restraining ability toward the polysulfide shuttle under long cycling, high sulfur loading and low electrolyte conditions.     

多轴同步系统模糊补偿虚拟主轴偏差耦合控制

在多轴同步系统中，同步控制的目标包括降低同步误差，减小跟踪误差。针对普通偏差耦合控制在实际应用中的问题，对其结构进行改进。该结构通过引入虚拟主轴，虚拟主轴在参考各轴反馈转速的同时，同步完成各轴转速给定补偿，优化了同步控制性能，简化了转速补偿结构。然后，通过结合模糊补偿，可自适应修正控制参数。最后，通过机构运动进行了试验验证，试验结果表明该控制方法相对传统偏差耦合控制结构，在简化系统结构的同时，可进一步提高同步控制性能，在存在负载扰动的运行工况下，可有效降低跟踪误差。该方法也为相关领域的同步控制提供了参考。     

供水低碳自动调度控制系统建模仿真与运行(上)--供水管网宏观模型建模过程

本刊有幸邀请到市政供水系统变频节能及自动化方面专家游庆元总工,他毕业于华中科技大学机械工程学院,长期工作在水处理第一线,曾在长沙水司和惠州水司工作研究管网压力控制模型40年,受邀在供水行业讲座30余场,在主流期刊发表相关论文40多篇,理论和实操经验丰富,在行业处于领先地位。2-4期将陆续刊登其供水低碳自动调度控制系统建模仿真与运行(上)、(中)、(下),为广大读者推送市政供水行业的应用技术及经典案例,敬请期待。     

锂离子电磁纳米合金负极材料的研究进展

综述了锂离子电池纳米合金负极材料的研究进展。讨论了该类材料的电化学性能、制备工艺及发展前景。     

Dilute Aqueous Hybrid Electrolyte with Regulated Core-Shell-Solvation Structure Endows Safe and Low-Cost Potassium-Ion Energy Storage Devices

High-concentration “water-in-salt” (WIS) electrolytes with the wider electrochemical stability window (ESW) can give rise to safe, non-flammable, and high-energy aqueous potassium-ion energy storage devices, thus highlighting the prospect for applications in grid-scale energy storage. However, WIS electrolytes usually depend on highly concentrated salts, leading to serious concerns about cost and sustainability. Here, an aqueous low-concentration-based potassium-ion hybrid electrolyte is demonstrated with the regulated core-shell-solvation structure by using an aprotic solvent, i.e., trimethyl phosphate, to limit the water activity. This aqueous hybrid electrolyte has a low salt concentration (1.6 mol L⁻¹) of potassium trifluoromethanesulfonate but with an expanded ESW up to 3.4 V and the nonflammable property. Based on this dilute aqueous hybrid electrolyte, electrochemical double-layer capacitors are capable of working within a large voltage range (0–2.4 V) at a wide range of temperatures from −20 to 60 °C. An aqueous potassium-ion battery consisting of an organic 3,4,9,10-perylenetetracarboxylic diimide anode, Prussian blue K_1.5Mn_0.61Fe_0.39[Fe(CN)₆]_0.77·H₂O cathode and this dilute aqueous hybrid electrolyte can operate well at rates between 0.2 and 4.0 C and deliver a high energy density of 66.5 Wh kg⁻¹ as well as a durable cycling stability with a capacity retention of 84.5% after 600 cycles at 0.8 C.     

Optimization design of a permanent magnet used for a low field (0.2 T) movable MRI system

Magnetic Resonance Materials in Physics, Biology and Medicine - To design a lightweight permanent magnet for a lowfield movable head imaging MRI system. To reduce the weight of the magnet, the pole...     

不同维度玻璃纤维对GRC抗弯性能的影响

采用一维短切玻璃纤维、二维玻璃纤维网格布、三维间隔连体玻纤织物(3D织物)对水泥基材料进行增强,得到不同维度玻璃纤维增强水泥(GRC);根据四点弯曲测试得到不同维度GRC试件的抗弯荷载-挠度曲线,结合测试过程中的裂缝发展情况,分析不同维度玻璃纤维对水泥基材料抗弯性能的影响规律,并建立不同维度GRC试件的抗弯荷载-挠度曲线拟合方程,计算其强度和韧性指标.结果 表明:在弹性变形阶段和塑性变形阶段,不同维度GRC试件的荷载与挠度均有较好的线性关系,在弹塑性过渡阶段,3D织物GRC试件的抗弯荷载与挠度呈正弦函数关系;与纯水泥砂浆试件相比,一维短切玻璃纤维GRC试件、二维玻璃纤维网格布GRC试件、3D织物GRC试件的抗弯破坏强度分别提高53％、92％、193％,韧度指数分别达26.7、34.3、73.6;3D织物GRC使得GRC材料由低强度脆性破坏向高强、高韧性提升.     

Detection of Glucose Based on Noble Metal Nanozymes: Mechanism,Activity Regulation,and Enantioselective Recognition

Glucose monitoring is essential to evaluate the degree of glucose metabolism disorders. The enzymatic determination has been the most widely used method in glucose detection because of its high efficiency, accuracy, and sensitivity. Noble metal nanomaterials (NMs, i.e., Au, Ag, Pt, and Pd), inheriting their excellent electronic, optical, and enzyme-like properties, are classified as noble metal nanozymes (NMNZs). As the NMNZs are often involved in two series of reactions, the oxidation of glucose and the chromogenic reaction of peroxide, here the chemical mechanism by employing NMNZs with glucose oxidase (GOx) and peroxidase (POD) mimicking activities is briefly summarized first. Subsequently, the regulation strategies of the GOx-like, POD-like and tandem enzyme-like activities of NMNZs are presented in detail, including the materials, size, morphology, composition, and the reaction condition of the representative NMs. In addition, in order to further mimic the enantioselectivity of enzyme, the design of NMNZs with enantioselective recognition of d -glucose and l -glucose by using different chiral compounds (DNA, amino acids, and cyclodextrins) and molecular imprinting is further described in this review. Finally, the feasible solutions to the existing challenges and a vision for future development possibilities are discussed.