Mapping the Complete Photocycle that Powers a Large Stokes Shift Red Fluorescent Protein

Large Stokes shift (LSS) red fluorescent proteins (RFPs) are highly desirable for bioimaging advances. The RFP mKeima, with coexisting cis- and trans-isomers, holds significance as an archetypal system for LSS emission due to excited-state proton transfer (ESPT), yet the mechanisms remain elusive. We implemented femtosecond stimulated Raman spectroscopy (FSRS) and various time-resolved electronic spectroscopies, aided by quantum calculations, to dissect the cis- and trans-mKeima photocycle from ESPT, isomerization, to ground-state proton transfer in solution. This work manifests the power of FSRS with global analysis to resolve Raman fingerprints of intermediate states. Importantly, the deprotonated trans-isomer governs LSS emission at 620 nm, while the deprotonated cis-isomer's 520 nm emission is weak due to an ultrafast cis-to-trans isomerization. Complementary spectroscopic techniques as a table-top toolset are thus essential to study photochemistry in physiological environments.     

Synchronous Dual Electrolyte Additive Sustains Zn Metal Anode with 5600 h Lifespan

Despite conspicuous merits of Zn metal anodes, the commercialization is still handicapped by rampant dendrite formation and notorious side reaction. Manipulating the nucleation mode and deposition orientation of Zn is a key to rendering stabilized Zn anodes. Here, a dual electrolyte additive strategy is put forward via the direct cooperation of xylitol (XY) and graphene oxide (GO) species into typical zinc sulfate electrolyte. As verified by molecular dynamics simulations, the incorporated XY molecules could regulate the solvation structure of Zn²⁺, thus inhibiting hydrogen evolution and side reactions. The self-assembled GO layer is in favor of facilitating the desolvation process to accelerate reaction kinetics. Progressive nucleation and orientational deposition can be realized under the synergistic modulation, enabling a dense and uniform Zn deposition. Consequently, symmetric cell based on dual additives harvests a highly reversible cycling of 5600 h at 1.0 mA cm⁻²/1.0 mAh cm⁻².     

Comprehensive Mechanism for CO Electroreduction on Dual-Atom-Catalyst-Anchored N-Doped Graphene

Carbon neutrality has drawn increasing attention for realizing the carbon cyclization and reducing the greenhouse effect. Although the C1 products, such as CO, can be achieved with a high Faraday efficiency, the targeted production of C2 fuels as well as the mechanism have not been systematically investigated. In this work, we carry out a first-principles study to screen dual-atom catalysts (DACs) for producing C2 fuels through the electrocatalytic carbon monoxide reduction reaction (e-CORR). We find that methanol, ethanol and ethylene can be produced on both DAC−Co and DAC−Cu, while acetate can be achieved on DAC−Cu only. Importantly, methanol and ethylene are preferred on DAC−Co, while acetate and ethylene on DAC−Cu. Furthermore, we show that the explicit solvent can enhance the adsorption and influence the protonation steps, which subsequently affects the protonation and dimerization behavior as well as the performance and selectivity of e-CORR on DACs. We further demonstrate that the C−C coupling is easy to be formed and stabilized if the Integrated Crystal Orbital Hamilton Population (ICOHP) is low because of the low energy barrier. Our findings provide not only guidance on the design of novel catalysts for e-CORR, but an insightful understanding on the reduction mechanism.     

基于结构虚拟筛选发现蛋白质精氨酸甲基转移酶5抑制剂

蛋白质精氨酸甲基转移酶5(PRMT5)是蛋白质甲基转移酶家族(PRMTs)的重要一员,其主要生理功能是催化精氨酸单对称二甲基化。PRMT5的上调发生在不同类型的肿瘤中,并与不良预后密切相关,已被视为肿瘤治疗中的潜在靶点。近年来,已有多种PRMT5抑制剂进入临床试验,但目前尚未有药物获批上市。本研究基于Glide对接的虚拟筛选和生物活性实验,发现化合物8018-1271对PRMT5酶的抑制活性IC₅₀值为13.56±0.86μmol/L,并通过分子动力学揭示其与PRMT5蛋白结构域的相互作用模式。本研究所得化合物8018-1271可作为进一步改造的先导化合物,为新型PRMT5抑制剂的发现提供参考。     

电纺纤维在超级电容器中的应用

对高性能超级电容器不断增长的需求促进了电极隔膜和电极材料的快速发展。静电纺丝法制备的纳米纤维具有较高的孔隙率、较好电化学活性、较大的表面积以及良好的结构稳定性等优点,已被广泛应用于超级电容器的隔膜和电极材料。本文简要综述了近年来电纺纳米纤维在超级电容器用隔膜和电极材料的研究进展;着重讨论了通过静电纺丝和其他后处理方法制备的碳基纳米纤维、碳基复合纳米纤维、导电聚合物基复合纳米纤维和金属氧化物纳米纤维等用于超级电容器的电极材料。研究表明,多孔结构的构建、活化处理以及杂原子掺杂可以提高碳纳米纤维的比表面积、电化学活性、润湿性和石墨化程度,从而增强其电化学性能。此外,通过共混、化学沉积和电化学沉积等方法,将碳纳米纤维与金属氧化物、导电聚合物结合,可以改善其电容、倍率性能和循环稳定性。最后,提出上述研究中存在的问题,并对未来静电纺丝纳米纤维材料在超级电容器的发展前景进行了展望。     

Two Uranyl Complexes with Pyromellitic Acid. A Heterometallic Complex with U=O–CuII Interaction

Two uranyl complexes based on pyromellitic acid were hydrothermally synthesized, and their X‐ray single‐crystal diffraction structures were determined. Complex [UO₂(Hbtec)]^–(Himd)⁺ · H₂O ( 1 ) (H₄btec = pyromellitic acid, imd = imidazole), is an ionic complex, which shows a typical (4, 4) topological structure in the space. A heterometallic complex, UO₂Cu(btec)(phen) ( 2 ) (phen = 1,10‐phenanthroline) results from the reaction of uranyl nitrate and copper(II) bromide with pyromellitic acid. The structure of complex 2 revealed that the chains of UO₇ and CuO₃N₂ units were connected to each other through the carboxyl groups and U=O–Cu interactions to create a two‐dimensional framework.     

金属氧化物和硅沉积改性 ZnO/SiO2/ZSM-5的甲醇择形芳构化反应催化研究

采用真空浸渍法对ZSM-5分子筛进行硅沉积和负载金属修饰,制备了复合改性的ZnO/SiO₂/ZSM-5催化剂,并将它应用于甲醇择形芳构化反应中。采用XRD、BET、NH₃-TPD、SEM、TEM等方法对制备的催化剂进行了物化表征。考察硅沉积次数和ZnO负载量对甲醇芳构化反应(MTA)中对二甲苯(PX)的选择性和收率的影响。结果表明,两次硅沉积改性并负载2.0%金属ZnO的ZSM-5分子筛具有较高的PX收率,在优化的反应温度420 ℃、反应压力0.2 MPa、甲醇空速WHSV为1.25 h^-1下,PX收率在28%以上。     

氧化钛负载脱硝催化剂的碱中毒过程：氧化钒的保留和氧化钨的牺牲

V2O5-WO3/TiO2催化剂目前已广泛用于电厂和工业锅炉燃烧废气脱硝,但燃烧原料煤及石油中含有的杂质元素碱金属与碱土金属元素可吸附在催化剂上,不仅会减少催化剂酸性位的数量,还会与催化活性元素结合生成惰性物种,导致催化剂失活。因此,已有许多有关钒钨钛催化剂碱中毒的研究,从催化剂的氧化还原能力、酸性位损失及表面孔结构等方面进行了讨论。但这些研究大多集中在碱中毒对活性组分V2O5的影响及中毒催化剂的活性变化,很少涉及催化剂中WO3的作用,也缺乏有关不同活性元素与钾盐反应的实验证据。本文采用过量浸渍法制备了不同钒和钨含量的钒钨钛催化剂,研究了氯化钾对其氨法选择性催化还原(NH3-SCR)活性的失活效应。利用感应耦合等离子体、N2吸附、拉曼光谱、H2程序升温还原、NH3吸附红外光谱和NH3氧化活性等手段对新鲜和中毒催化剂的性质进行了表征,特别探讨了V2O5和WO3对催化剂抗碱中毒能力的贡献。
　　催化剂活性测试结果表明, V2O5含量越高,活性温度窗口越宽,而且含有WO3的三元催化剂活性高于V2O5/TiO2二元催化剂。催化剂的BET比表面积和孔结构取决于TiO2载体,随活性组分配比变化不大,说明催化剂物理结构性质并非影响活性的主要因素。原位红外光谱及H2程序升温还原测试结果表明,随V2O5含量提高,催化剂表面Br?nsted酸性位数量及氧化还原能力提高。作为反应的主要活性物种, V2O5在碱中毒处理后变成惰性的偏钒酸钾KVO3,使催化剂中Br?nsted酸性位减少,热稳定性下降,并削弱了催化剂的氧化还原能力,因此低钒含量的催化剂容易严重中毒失活。在高钒负载量(3%)时,部分V2O5在碱中毒后得以保留,从而使催化剂保持了一定的脱硝催化活性。
　　另外, WO3能给催化剂表面提供热稳定的酸性位,虽然WO3自身的氧化还原能力差,但其能改善V2O5的分散性,从而提高V2O5-WO3/TiO2催化剂的活性。除此之外, WO3在催化剂碱中毒过程中还能扮演牺牲剂,与钾反应生成钨酸钾(K2WO4),即在V2O5与钾离子结合形成KVO3的同时,部分WO3也会与钾反应形成K2WO4,可以使三元催化剂保留更多的活性V物种。因此,在所研究的催化剂中,高钒负载量的V2O5-WO3/TiO2催化剂表现出最好的抗碱中毒能力。
　　活性影响因素分析表明,对于新鲜催化剂,其表面吸附的NH3量足够多,催化剂活性与表面酸性相关度不大,脱硝效率主要取决于催化剂的氧化还原能力。但是,对于碱中毒处理后的催化剂,其表面吸附NH3的能力大大削弱,这时脱硝效率除了受催化剂氧化还原能力影响,在很大程度上也依赖于催化剂的表面酸性。