隧道支护结构体系及其协同作用

隧道支护结构体系是围岩稳定性控制的关键,也是隧道设计的基本任务,而对支护结构之间相互作用过程和机制的系统认识则是定量化设计的基础. 本文从隧道围岩结构性和支护作用的本质特征出发,提出隧道支护具有"调动"和"协助"围岩承载的基本作用,明确了二者的功能分配原则和实现方式,即分别通过超前支护的保障作用、初期支护的核心作用和二次衬砌的安全储备作用共同完成;针对围岩的正面挤出、前倾式冒落和后倾式冒落等三种超前破坏模式,分别给出了相应的超前支护方式和支护效果评价方法;提出初期支护作为隧道围岩附加载荷的主要承担者,包括锚固体系与拱架及喷射混凝土结构,分别通过"调动"和"协助"围岩实现其承载功能,且同时具有"支"与"护"的作用;阐明了二次衬砌结构作为安全储备功能的内涵,建立了二次衬砌结构的载荷分担比率与刚度匹配性、支护时机的关系,并据此给出了二次衬砌结构参数和施作时机的建议值;建立了以围岩变形量$S$最小和协同度$\xi$最优为目标,基于超前支护、初期支护和二次衬砌与围岩相互作用三阶段的协同支护优化模型,明确了支护结构体系与围岩、不同支护结构之间以及支护结构要素之间三个层次的协同关系,并提出了隧道支护结构体系协同优化设计方法.      

Mechanically fabricated Metal–organic framework/resin composite nanoparticles for efficient basic catalysis

Zeolitic imidazolate framework‐8 (ZIF‐8) was successfully composited with an anionic basic resin 201 × 7 (717‐resin) to provide a novel ZIF‐8/717‐resin composite. Its catalytic activity toward the Knoevenagel condensation reaction was evaluated. Results showed that ZIF‐8/717‐resin composite could efficiently catalyze this reaction, affording the corresponding products in good to excellent yields. Good functional group tolerance, mild reaction conditions, good stability and reusability of the catalyst are the major features of present protocol.     

Engineered Targeted Hyaluronic Acid–Glutathione‐Stabilized Gold Nanoclusters/Graphene Oxide–5‐Fluorouracil as a Smart Theranostic Platform for Stimulus‐Controlled Fluorescence Imaging‐Assisted Synergetic Chemo/Phototherapy

A theranostic platform with integrated diagnostic and therapeutic functions as well as specific targeted and controlled combination therapy to enhance treatment efficacy is of great importance for a wide range of biomedical applications. Here, we first attempted to develop biocompatible hyaluronic acid (HA)–glutathione (GSH) conjugate stabilized gold nanoclusters (GNCs) combined with graphene oxide (GO), accompanied by loading 5‐fluorouracil (5FU), as a novel theranostic platform (HG‐GNCs/GO‐5FU, HG refers to HA‐GSH). Multifunctional HG‐GNCs possessed excellent fluorescence, photosensitivity and specific targeting ability to the cancer cells while their fluorescence and singlet oxygen generation could be strongly inhibited by GO and then effectively restored by lysosomal hyaluronidase in tumor cells. The sustained and complete release of 5FU from HG‐GNCs/GO could also be stimulated successively by enzymatic degradation of HA and light‐induced heat effect of GO under laser irradiation so that turn‐on cell imaging‐assisted synergistic therapeutic strategies associated with triple enzyme/light‐controlled chemo/photothermal/photodynamic therapy could be achieved at the same time, reducing greatly the side effects of materials to normal cells. Our study presents a novel strategy to combine targeting and bioimaging with triple therapies to enhance the antitumor effect.     

基于WSR的水利工程全过程协同管理研究

在水利工程管理当中,从前期决策、勘察设计、建造到运营维护的全过程,引入全过程协同管理,可以产生和助力发挥协同效应.以都江堰工程为例,运用物理-事理-人理方法论(Wuli-Shili-Renli System Approach,以下简称WSR方法论),从物理、事理、人理角度,对协同管理进行系统分析,通过构建基于WSR系统的协同管理三维分析模型、协同管理分析矩阵和协同管理分析框架,为水利工程的协同管理提供启示和借鉴,助力于发挥水利工程协同管理全过程的协同效应.     

Preparation of an organic–inorganic hybrid based on synergy of Brønsted and Lewis acid centres as heterogeneous magnetic nanocatalyst for ultrafast synthesis of acetaminophen

A heterogeneous nanocatalyst based on a Cu(II) complex containing phosphotungstic acid and N/O‐donor ligands supported on cobalt ferrite nanoparticles was successfully prepared. The synthesized nanocatalyst was characterized using various techniques. The magnetic nanocatalyst was examined as an efficient and synergistic catalyst for ultrafast synthesis of acetaminophen at room temperature and under solventless conditions. The examined synergistic nanocatalyst, which has both Lewis and Brønsted acidic sites, could be easily separated from the reaction system and reused several times without significant loss of its activity. The synthesized acetaminophen was also fully characterized.     

Enantioselective and Synergistic Herbicidal Activities of Common Amino Acids Against Amaranthus tricolor and Echinochloa crus-galli

Amino acids have a wide range of biological activities, which usually rely on the stereoisomer presented. In this study, glycine and 21 common α-amino acids were investigated for their herbicidal property against Chinese amaranth (Amaranthus tricolor L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.). Both d- and l-isomers, as well as a racemic mixture, were tested and found that most compounds barely inhibited germination but moderately suppressed seedling growth. Various ratios of d:l-mixture were studied and synergy between enantiomers was found. For Chinese amaranth, the most toxic d:l-mixtures were at 3:7 (for glutamine), 8:2 (for methionine), and 5:5 (for tryptophan). For barnyard grass, rac-glutamine was more toxic than the pure forms; however, d-tryptophan exhibited greater activity than racemate and l-isomer, indicating the sign of enantioselective toxicity. The mode of action was unclear, but d-tryptophan caused bleaching of leaves, indicating pigment synthesis of the grass was inhibited. The results highlighted the enantioselective and synergistic toxicity of some amino acids, which relied upon plant species, chemical structures, and concentrations. Overall, our finding clarifies the effect of stereoisomers, and provides a chemical clue of amino acid herbicides, which may be useful in the development of herbicides from natural substances.     

Metal–Organic Framework (MOF)-Derived Electron-Transfer Enhanced Homogeneous PdO-Rich Co3O4 as a Highly Efficient Bifunctional Catalyst for Sodium Borohydride Hydrolysis and 4-Nitrophenol Reduction

Developing a bifunctional catalyst with low cost and high catalytic performance in NaBH₄ hydrolysis for H₂ generation and selective reduction of nitroaromatics will make a significant impact in the field of sustainable energy and water purification. Herein, a low-loading homogeneously dispersed Pd oxide-rich Co₃O₄ polyhedral catalyst (PdO-Co₃O₄) with concave structure is reported by using a metal–organic framework (MOF)-templated synthesis method. The results show that the PdO-Co₃O₄ catalyst has an exceptional turnover frequency (3325.6 mol_H2 min⁻¹ mol_Pd⁻¹), low activation energy (43.2 kJ mol⁻¹), and reasonable reusability in catalytic H₂ generation from NaBH₄ hydrolysis. Moreover, the optimized catalyst also shows excellent catalytic performance in the NaBH₄ selective reduction of 4-nitrophenol to 4-aminiphenol with a high first-order reaction rate of approximately 1.31 min⁻¹. These excellent catalytic properties are mainly ascribed to the porous concave structure, monodispersed Pd oxide, as well as the unique synergy between PdO and Co₃O₄ species, which result in a large specific surface area, high conductivity, and fast solute transport and gas emissions.     

Hydrogenation of nitroarenes catalyzed by a dipalladium complex

A dipalladium complex [Pd₂( L )Cl₂](PF₆)₂ ( 2 ), via the substitution of (PhCN)₂PdCl₂ with 5‐phenyl‐2,8‐bis(6′‐bipyridinyl)‐1,9,10‐anthyridine ( L ) followed by the anion exchange, was found to be a good pre‐catalyst for the reduction of nitroarenes to yield the corresponding anilines under atmospheric pressure of hydrogen in methanol. This method provides a straightforward access to a diverse array of functionalized anilines, exhibiting a possible application in synthetic chemistry. The catalytic activity of this complex is enhanced by the di‐metallic system via the synergistic effect.     

Step-by-step synthesis of copper(I) complex supported on platinum nanoparticle-decorated mesoporous silica hollow spheres and its remarkable catalytic performance in Sonogashira coupling reaction

In this study, a step-by-step method for the synthesis of platinum nanoparticles and copper(I) complex supported on mesoporous silica hollow spheres (Pt-MSHSs-Cu) is introduced. Scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption, energy-dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, and elemental and thermogravimetric analyses were applied for characterization of the surface, structure, size, phase composition, and morphology of the synthesized materials. The characterized material, Pt-MSHSs-Cu, was used as an efficient and heterogeneous catalyst in the Sonogashira coupling reaction under different reaction conditions. In comparison with MSHSs, Cu(I)-functionalized MSHSs (MSHSs-Cu), and Pt-MSHSs samples, the Pt-MSHSs-Cu catalyst exhibited significantly increased catalytic performance with 91.50% yield. Therefore, the results obtained suggested a synergistic effect derived from platinum nanoparticles, MSHSs substrate, and copper(I) complex, which enhanced the rate of the Sonogashira coupling reaction.     

Synergy of Iron Doping and Cyano Groups for Enhanced Photocatalytic Hydrogen Production over C3N4

Improving the insufficient carrier separation dynamics is still of significance in carbon nitride (C₃N₄) research. Extensive research has been devoted to improving the carrier separation efficiency through a single strategy, while ignoring the synergistic enhancement effect produced by coupling two or more conventional strategies. Herein, we reported the fabrication of cyano group-containing Fe-doped C₃N₄ porous materials via direct co-calcination of iron acetylacetonate and melamine for synergistically improving the photocatalytic performance. Iron acetylacetonate can promote the generation of cyano groups and form Fe-doping in C₃N₄, thereby increasing the visible-light absorption and reactive sites. Further, the internal donor-acceptor system formed by cyano groups and Fe-doped sites promoted charge carrier separation and inhibited the radiation recombination of e⁻-h⁺ pairs. The optimized photocatalytic activity of Fe−CN-2 sample was 4.5 times of bulk C₃N₄ (BCN).