Degradation of Structurally Defined Graphene Nanoribbons by Myeloperoxidase and the Photo-Fenton Reaction

As an emerging member of the graphene family, structurally defined graphene nanoribbons (GNRs) have shown promising applications in various fields. The evaluation of the degradability of GNRs is particularly important for assessing the persistence level and risk of these materials in living organisms and the environment. However, there is a void in the study of the degradation of GNRs. Here, we report the degradation behavior of GNRs in the presence of human myeloperoxidase (hMPO) or treated with the photo-Fenton (PF) reaction. With the assistance of potassium hydroxide or imidazole, which facilitates the dispersion of GNRs in the aqueous solution, GNRs underwent only partial degradation after 25-hour incubation with hMPO, while, the PF reaction degraded GNRs almost completely after 120 hours. These results indicate that structurally precise GNRs can be efficiently degraded under suitable conditions, providing more opportunities for future applications in different fields.     

Rationally Designed Three-Layered Cu2S@Carbon@MoS2 Hierarchical Nanoboxes for Efficient Sodium Storage

Hybrid materials, integrating the merits of individual components, are ideal structures for efficient sodium storage. However, the construction of hybrid structures with decent physical/electrochemical properties is still challenging. Now, the elaborate design and synthesis of hierarchical nanoboxes composed of three-layered Cu₂S@carbon@MoS₂ as anode materials for sodium-ion batteries is reported. Through a facile multistep template-engaged strategy, ultrathin MoS₂ nanosheets are grown on nitrogen-doped carbon-coated Cu₂S nanoboxes to realize the Cu₂S@carbon@MoS₂ configuration. The design shortens the diffusion path of electrons/Na⁺ ions, accommodates the volume change of electrodes during cycling, enhances the electric conductivity of the hybrids, and offers abundant active sites for sodium uptake. By virtue of these advantages, these three-layered Cu₂S@carbon@MoS₂ hierarchical nanoboxes show excellent electrochemical properties in terms of decent rate capability and stable cycle life.     

细胞色素P450酶催化的烷烃选择性羟化

碳氢键选择氧化是合成化学领域的重要课题,其中烷烃选择性羟化反应更是面临着化学选择性、区域选择性和立体选择性等多重挑战.细胞色素P450酶广泛分布于动植物和微生物体内,是公认的多功能生物氧化催化剂.P450酶对惰性C-H键的选择性氧化具有独特优势,在催化烷烃选择性羟化反应方面拥有巨大潜力.本综述简述了P450单加氧酶及其催化烷烃选择性羟化的反应机理,梳理了来自CYP153家族、CYP52家族和其他家族的天然P450酶催化各类烷烃底物的氧化反应和选择性,讨论了理性设计和定向进化策略在开发烷烃羟化P450突变酶过程中的经典案例,介绍了底物工程、诱饵分子、双功能小分子协同催化等几种化学活化P450酶的策略及其在烷烃羟化上的应用,探讨了P450酶在烷烃选择性羟化方面所面临的挑战和解决途径,并展望了其应用前景.     

Fabrication of Heterostructured Fe2TiO5–TiO2 Nanocages with Enhanced Photoelectrochemical Performance for Solar Energy Conversion

Photocatalysts with well‐designed compositions and structures are desirable for achieving highly efficient solar‐to‐chemical energy conversion. Heterostructured semiconductor photocatalysts with advanced hollow structures possess beneficial features for promoting the activity towards photocatalytic reactions. Here we develop a facile synthetic strategy for the fabrication of Fe₂TiO₅–TiO₂ nanocages (NCs) as anode materials in photoelectrochemical (PEC) water splitting cells. A hydrothermal reaction is performed to transform MIL‐125(Ti) nanodisks (NDs) to Ti–Fe–O NCs, which are further converted to Fe₂TiO₅–TiO₂ NCs through a post annealing process. Owing to the compositional and structural advantages, the heterostructured Fe₂TiO₅–TiO₂ NCs show enhanced performance for PEC water oxidation compared with TiO₂ NDs, Fe₂TiO₅ nanoparticles (NPs) and Fe₂TiO₅–TiO₂ NPs.     

Structure Determination of Alkynyl‐Protected Gold Nanocluster Au22(tBuC≡C)18 and Its Thermochromic Luminescence

An alkynyl‐protected gold nanocluster, Au₂₂(^tBuC≡C)₁₈ ( 1 ), has been synthesized and its structure has been determined by single‐crystal X‐ray diffraction. The molecular structure consists of a Au₁₃ cuboctahedron kernel and three [Au₃(^tBuC≡C)₄] trimeric staples. The cluster 1 has strong luminescence in the solid state with a 15 % quantum yield, and it displays interesting thermochromic luminescence as revealed by temperature‐dependent emission spectra. The enhanced room‐temperature emission is characterized as thermally activated delayed fluorescence.     

Effect of ethyl‐bridged diphenylphosphine oxide on flame retardancy and thermal properties of epoxy resin

Three commercialized flame retardants, 1,2‐bis(diphenylphosphinoyl)ethane (EDPO), 6,6‐(1,2‐phenethyl)bis‐6H‐dibenz[c,e][1,2]oxaphosphorin‐6,6‐dioxide (HTP‐6123), and hexa‐phenoxy‐cyclotriphosphazene (HPCTP), were used to prepare the flame retardant diglycidyl ether of bisphenol A (DGEBA) epoxy resin (EP) under the same experimental conditions. The effects of T_g, thermal stability, and water absorption properties of EP caused by the three flame retardants were investigated and compared, together with their flame retardant efficiency. Results showed that the introduction of the three flame retardants improved the flame retardant performance of EP but led to decreases in T_g and decomposition temperature. EDPO showed higher flame retardant efficiency than the other two flame retardants. EP/EDPO showed higher thermal stability, better flame retardant performance, higher T_g value, and lower water absorption than EP/HTP‐6123 and EP/HPCTP. The study discovered that EDPO and HTP‐6123 primarily act through the gas phase flame retardant mechanism, while HPCTP is primarily driven by the condensed phase mechanism.     

Interfacial Design of Dendrite‐Free Zinc Anodes for Aqueous Zinc‐Ion Batteries

Aqueous zinc‐ion batteries have rapidly developed recently as promising energy storage devices in large‐scale energy storage systems owing to their low cost and high safety. Research on suppressing zinc dendrite growth has meanwhile attracted widespread attention to improve the lifespan and reversibility of batteries. Herein, design methods for dendrite‐free zinc anodes and their internal mechanisms are reviewed from the perspective of optimizing the host–zinc interface and the zinc–electrolyte interface. Furthermore, a design strategy is proposed to homogenize zinc deposition by regulating the interfacial electric field and ion distribution during zinc nucleation and growth. This Minireview can offer potential directions for the rational design of dendrite‐free zinc anodes employed in aqueous zinc‐ion batteries.     

Rationally Designed Three‐Layered Cu2S@Carbon@MoS2 Hierarchical Nanoboxes for Efficient Sodium Storage

Hybrid materials, integrating the merits of individual components, are ideal structures for efficient sodium storage. However, the construction of hybrid structures with decent physical/electrochemical properties is still challenging. Now, the elaborate design and synthesis of hierarchical nanoboxes composed of three‐layered Cu₂S@carbon@MoS₂ as anode materials for sodium‐ion batteries is reported. Through a facile multistep template‐engaged strategy, ultrathin MoS₂ nanosheets are grown on nitrogen‐doped carbon‐coated Cu₂S nanoboxes to realize the Cu₂S@carbon@MoS₂ configuration. The design shortens the diffusion path of electrons/Na⁺ ions, accommodates the volume change of electrodes during cycling, enhances the electric conductivity of the hybrids, and offers abundant active sites for sodium uptake. By virtue of these advantages, these three‐layered Cu₂S@carbon@MoS₂ hierarchical nanoboxes show excellent electrochemical properties in terms of decent rate capability and stable cycle life.     

DIC Challenge 2.0: Developing Images and Guidelines for Evaluating Accuracy and Resolution of 2D Analyses

Experimental Mechanics - The DIC Challenge 2.0 follows on from the work accomplished in the first Digital Image Correlation (DIC) Challenge Reu et al. (Experimental Mechanics 58(7):1067, 1). The...     

Dynamics of the electromechanical sieve with hysteretic iron-core inductor

We study bifurcations and the chaotic behavior of a periodically forced electromechanical sieve. The dynamical behavior of the system is analyzed when supplied with the sinusoidal and square voltage sources. Analytical calculations and numerical simulations are also carried out for this electromechanical system and the results obtained are shown in terms of frequency–response diagrams, time–displacement diagrams, and phase portraits. Depending on the system parameters the analytical calculations and the numerical simulations exhibit regions of periodic and chaotic behaviors. For experimental validation, a small electromechanical sieve has been designed and realized. Amplitude jumps, hysteresis, and multistability are also observed. Good agreements are found between our theoretical results and experimental ones.