串级结构Z扫描特性的分析

对非线性介质串级结构的Z扫描特性进行了分析，分别给出了解析解和数值解. 解析分析主要是基于高斯分解方法（GDM）和分布透镜方法的组合；数值分析采用了Crank-Nicholson有限差分方法和快速汉克尔变换方法(FHT). 同时，也给出了这两种数值分析的使用条件和方法. 将解析结果、数值结果和实验结果进行了比较，结果显示它们具有很好的一致性. 关键词： 串级结构 Z扫描 有限差分方法 快速汉克尔变换     

Belousov-Zhabotinskii反应的研究——不同气氛下的振荡现象

本文考察了不同气氛下, 丙二酸(MA)、邻菲罗啉亚铁离子和溴酸根之间反应的振荡现象。结果表明, 氢气与氮气对此反应的振荡基本上是惰性的, 而氧气对此反应的振荡有明显的影响。对氧的影响作了较仔细的研究, 观察到氧气氛下反应出现的一些特殊振荡波形。此外还对邻菲罗啉亚铁离子的离解造成的影响作了初步探讨。结合熟知的反应机理对实验结果进行了若干分析。     

Tunable Chirality of Self-Assembled Dipeptides Mediated by Bipyridine Derivative

Supramolecular peptide assemblies have been widely used for the development of biomedical, catalytical, and optical materials with chiral nanostructures in view of the intrinsic chirality of peptides. However, the assembly pathway and chiral transformation behavior of various peptides remain largely elusive especially for the transient assemblies under out-of-equilibrium conditions. Herein, the N-fluorenylmethoxycarbonyl-protected phenylalanine-tyrosine dipeptide (Fmoc-FY) was used as a peptide assembly platform, which showed that the assembly proceeds multistep evolution. The original spheres caused by liquid-liquid phase separation (LLPS) can nucleate and elongate into the formation of right-handed helices which were metastable and easily converted into microribbons. Interestingly, a bipyridine derivative can be introduced to effectively control the assembly pathway and induce the formation of thermodynamically stable right-handed or left-handed helices at different stoichiometric ratios. In addition, the chiral assembly can also be regulated by ultrasound or enzyme catalysis. This minimalistic system not only broadens the nucleation-elongation mechanisms of protein aggregates but also promotes the controllable design and development of chiral biomaterials.     

肾上腺素氧化反应的研究——氧化反应动力学和机理以及自由及中间体

用紫外吸收光谱法结合计算机模拟研究了肾上腺素(Adjn)在Cu(Ⅱ)离子催化下, 用H_2O_2氧化产生肾上腺素红(Adom)的反应动力学, 考查了反应的速率随体系中肾上腺素的初始浓度, Cu(Ⅱ)离子浓度和H_2O_2浓度的变化情况。在流动法或添加自由基稳定剂的条件下, 利用顺磁共振法检测丁肾上腺素自氧化, 光氧化和Cu(Ⅱ)离子催化H_2O_2氧化产生的半醌自由基。考查了Cu(Ⅱ)离子催化下自由基的相对浓度随反应条件的变化情况。在反应动力学和顺磁共振实验的基础上所提出的可能的反应机理, 半定量地解释此反应动力学实验结果和顺磁共振实验中的自由基行为。     

金属碳化钨与液相染料光敏剂协同促进光催化制氢（英文）

使用WC作为光催化材料通过水还原制氢很常见,但它通常需要与有效的光吸收剂协同才能产生有意义的光催化活性。这可归因于WC的窄带隙,导致水的氧化还原能力不足。有趣的是,我们的研究通过一种新型固液光催化体系克服了这种限制,该体系将裸WC光催化剂与液相光敏赤藓红B(Er B)相结合。这种概念的提出消除了将WC耦合到光吸收半导体的需要,这通常需要繁琐的程序来获得适当的功能化光催化复合材料。实验结果表明,在可见光(λ=520 nm)照射下,所提出的固液光催化体系产生了显著的氢气,然而,只有在三乙醇胺(TEOA)作为牺牲试剂的共同存在下。显然,仅加入WC和Er B的空白实验在典型的光催化条件下表现出几乎为零的光催化活性和无法测量的H₂生成。在光照TEOA溶液中仅存在Er B或WC的光反应中也观察到类似的活性。这些空白实验证实了所有三种成分的重要性,即WC、Er B和TEOA,它们分别作为光催化剂、光吸收剂和牺牲试剂,在我们提出的体系中产生有意义的H₂。值得注意的是,在我们的调查中系统地研究了三个关键参数,即p H值、Er B和WC浓度的影响。发现H     

Constructing Oxygen Vacancies via Engineering Heterostructured Fe3C/Fe3O4 Catalysts for Electrochemical Ammonia Synthesis

Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions provides an intriguing pathway to convert N₂ into NH₃. However, significant kinetic barriers of the NRR at low temperatures in desirable aqueous electrolytes remain a grand challenge due to the inert N≡N bond of the N₂ molecule. Herein, we propose a unique strategy for in situ oxygen vacancy construction to address the significant trade-off between N₂ adsorption and NH₃ desorption by building a hollow shell structured Fe₃C/Fe₃O₄ heterojunction coated with carbon frameworks (Fe₃C/Fe₃O₄@C). In the heterostructure, the Fe₃C triggers the oxygen vacancies of the Fe₃O₄ component, which are likely active sites for the NRR. The design could optimize the adsorption strength of the N₂ and N_xH_y intermediates, thus boosting the catalytic activity for the NRR. This work highlights the significance of the interaction between defect and interface engineering for regulating electrocatalytic properties of heterostructured catalysts for the challenging NRR. It could motivate an in-depth exploration to advance N₂ reduction to ammonia.     

Substituent Effect to Fine-Tune Energy Levels of Atom-Precise [MoOS3]2− Modified Copper(I) Thiolate Clusters Boosting Recyclable Photocatalysis

The propulsion of photocatalytic hydrogen (H₂) production is limited by the rational design and regulation of catalysts with precise structures and excellent activities. In this work, the [MoOS₃]²⁻ unit is introduced into the Cu^I clusters to form a series of atomically-precise Mo^VI−Cu^I bimetallic clusters of [Cu₆(MoOS₃)₂(C₆H₅(CH₂)S)₂(P(C₆H₄−R)₃)₄] ⋅ xCH₃CN (R=H, CH₃, or F), which show high photocatalytic H₂ evolution activities and excellent stability. By electron push-pull effects of the surface ligand, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of these Mo^VI−Cu^I clusters can be finely tuned, promoting the resultant visible-light-driven H₂ evolution performance. Furthermore, Mo^VI−Cu^I clusters loaded onto the surface of magnetic Fe₃O₄ carriers significantly reduced the loss of catalysts in the collection process, efficiently addressing the recycling issues of such small cluster-based catalyst. This work not only highlights a competitively universal approach on the design of high-efficiency cluster photocatalysts for energy conversion, but also makes it feasible to manipulate the catalytic performance of clusters through a rational substituent strategy.     

检测谷胱甘肽的荧光探针

谷胱甘肽作为细胞中最丰富的非蛋白巯基化合物,对维持人体正常生理活动有着重要作用。因此,能够高效灵敏检测谷胱甘肽意义重大。荧光探针法具有操作方便、特异性优良和灵敏度高等优点,成为目前检测生物样品中谷胱甘肽的主要手段。荧光探针法的成功应用还得益于谷胱甘肽的特殊结构特征,如巯基的亲核性、还原性、对金属离子高亲合力以及氨基的协同反应能力。本文针对近五年来特异性检测谷胱甘肽的荧光探针进行总结,将其分为有机荧光探针和无机荧光探针两大类,并结合香豆素、BODIPY、罗丹明、花菁、苯并噻唑、萘酰亚胺、金属有机骨架、半导体量子点、碳点、金属纳米颗粒、二氧化锰纳米片、石墨烯量子点等有机/无机荧光探针的结构特征,综述了迈克尔加成反应、亲核取代、还原反应以及硫醇诱导的2,4-二硝基苯磺酰基的断裂反应与络合反应等传感机理。同时,对探针的设计策略、谷胱甘肽的响应模式及其在实际中的应用进行了阐述和分析,以期为新型谷胱甘肽荧光探针的构建提供新的思路。