Synergy between Plasmonic and Electrocatalytic Activation of Methanol Oxidation on Palladium–Silver Alloy Nanotubes

Localized surface plasmon resonance (LSPR) excitation of noble metal nanoparticles has been shown to accelerate and drive photochemical reactions. Here, LSPR excitation is shown to enhance the electrocatalysis of a fuel‐cell‐relevant reaction. The electrocatalyst consists of Pd_xAg alloy nanotubes (NTs), which combine the catalytic activity of Pd toward the methanol oxidation reaction (MOR) and the visible‐light plasmonic response of Ag. The alloy electrocatalyst exhibits enhanced MOR activity under LSPR excitation with significantly higher current densities and a shift to more positive potentials. The modulation of MOR activity is ascribed primarily to hot holes generated by LSPR excitation of the Pd_xAg NTs.     

Electron–Proton Co‐doping‐Induced Metal–Insulator Transition in VO2 Film via Surface Self‐Assembled l‐Ascorbic Acid Molecules

Charge doping is an effective way to induce the metal–insulator transition (MIT) in correlated materials for many important utilizations, which is however practically limited by problem of low stability. An electron–proton co‐doping mechanism is used to achieve pronounced phase modulation of monoclinic vanadium dioxide (VO₂) at room temperature. Using l ‐ascorbic acid (AA) solution to treat VO₂, the ionized AA^? species donate electrons to the adsorbed VO₂ surface. Charges then electrostatically attract surrounding protons to penetrate, and eventually results in stable hydrogen‐doped metallic VO₂. The variations of electronic structures, especially the electron occupancy of V 3d/O 2p hybrid orbitals, were examined by synchrotron characterizations and first‐principle theoretical simulations. The adsorbed molecules protect hydrogen dopants from escaping out of lattice and thereby stabilize the metallic phase for VO₂.     

Photocaged Quinone Methide Crosslinkers for Light‐Controlled Chemical Crosslinking of Protein–Protein and Protein–DNA Complexes

Small‐molecule crosslinkers are invaluable for probing biomolecular interactions and for crosslinking mass spectrometry. Existing chemical crosslinkers target only a small selection of amino acids, while conventional photo‐crosslinkers target almost all residues non‐specifically, complicating data analysis. Herein, we report photocaged quinone methide (PQM)‐based crosslinkers that target nine nucleophilic residues through Michael addition, including Gln, Arg, and Asn, which are inaccessible to existing chemical crosslinkers. PQM crosslinkers were used in vitro, in Escherichia coli, and in mammalian cells to crosslink dimeric proteins and endogenous membrane receptors. The heterobifunctional crosslinker NHQM could crosslink proteins to DNA, for which few crosslinkers exist. The photoactivatable reactivity of these crosslinkers and their ability to target multiple amino acids will enhance the use of chemical crosslinking for studies of protein–protein and protein–DNA networks and for structural biology.     

In Situ Observation of Dynamic Galvanic Replacement Reactions in Twinned Metallic Nanowires by Liquid Cell Transmission Electron Microscopy

Galvanic replacement is a versatile approach to prepare hollow nanostructures with controllable morphology and elemental composition. The primary issue is to identify its fundamental mechanism. In this study, in situ liquid cell transmission electron microscopy was employed to monitor the dynamic reaction process and to explore the mechanism of galvanic replacement. The detailed reaction process was revealed based on in situ experiments in which small Au particles first appeared around Ag nanowires; they coalesced, grew, and adhered to Ag nanowires. After that, small pits grew from the edge of Ag nanowires to form tubular structures, and then extended along the Ag nanowires to obtain hollowed structures. All of our experimental observations from the viewpoint of electron microscopy, combined with DFT calculations, contribute towards an in‐depth understanding of the galvanic replacement reaction process and the design of new materials with hollow structures.     

Flexible antenna design on PDMS substrate for implantable bioelectronics applications

In the current field of biomedical engineering, the research on implanted antennas has attracted more and more attention. This paper presents a flexible terrestrial radiating antenna with circular polarization characteristics that satisfy various requirements for biomedical implantable antennas. The new type of flexible material is adopted and a novel model is proposed. The square ground with small gap is implemented in the proposed antenna. The passive components can match the impedance and meet the requirements of the circular polarization wave. Simulation is carried out in a single layer tissue model to estimate the performance of the antenna and compared with multilayer tissue model. In addition, the flexible circularly polarized antenna has low profile characteristics and a wide axial ratio bandwidth of 250 MHz, ranging from 2.28 to 2.53 GHz. This paper uses pork to simulate single‐layer and multi‐layer tissue model. The flexible circular polarized antenna prototype is placed in the organization model for performance simulation test, and the measurement impedance bandwidth of 500 MHz is realized in the industrial scientific medical frequency band of 2.4–2.48 GHz.     

A chlorinated non-fullerene acceptor for efficient polymer solar cells

Improving the performance and reducing the manufacturing costs are the main directions for the development of organic solar cells in the future. Here, the strategy that uses chemical structure modification to optimize the photoelectric properties is reported. A new narrow bandgap (1.30 eV) chlorinated non-fullerene electron acceptor (Y15), based on benzo[d][1,2,3] triazole with two 3-undecyl-thieno[2′,3′:4,5] thieno[3,2-b] pyrrole fused -7-heterocyclic ring, with absorption edge extending to the near-infrared (NIR) region, namely A-DA'D-A type structure, is designed and synthesized. Its electrochemical and optoelectronic properties are systematically investigated. Benefitting from its NIR light harvesting, the fabricated photovoltaic devices based on Y15 deliver a high power conversion efficiency (PCE) of 14.13%, when blending with a wide bandgap polymer donor PM6. Our results show that the A-DA'D-A type molecular design and application of near-infrared electron acceptors have the potential to further improve the PCE of polymer solar cells (PSCs).     

Synthesis and Characterization of Some Novel Dendritic Phenothiazine Derivatives

Russian Journal of Organic Chemistry - Three novel dendritic phenothiazine derivatives consisting of a biphenyl core, phenothiazine branching units, and terminal 3,7-di-tert-butylphenothiazine...     

Molecular level comparison of water extractives of maple and oak with negative and positive ion ESI FT‐ICR mass spectrometry

Soluble extractives in wood function to protect living trees from destructive agents and also contribute to wood color and fragrance. Some extractive components have biological activities with medical applications. They also play important roles in wood processing and related applications. To increase the knowledge of wood chemistry, maple and oak were extracted by water. Ultraviolet/visible (UV/vis) spectroscopy indicated the presence of a phenolic compound, resorcinol, in maple extractives having higher molecular mass and more aromatic components than oak extractives. Negative and positive electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT‐ICR‐MS) identified thousands of formulas in the two samples in the m/z range of 200 to 800. They mainly fall into the lignin‐like, carbohydrate‐like, and tannin‐like compound categories. The top 25 peaks (ie, formulas) with the highest relative magnitude in negative ESI represented nearly 50% of the summed total spectral magnitude of all formulas assigned in the maple and oak extractives. Furthermore, the base peak (ie, most abundant peak) accounted for about 14% of the total abundance in each wood sample. Literature comparisons identified 17 of 20 formulas in the top five peaks of the four spectra as specific bioactive compounds in trees and other plants, implying the potential to explore utilization of maple and oak extractives for functional and medicinal applications. The various profiling of the top 25 peaks from the two samples also suggested the possible application of FT‐ICR‐MS for detecting chemical markers useful in profiling and identification of wood types and sources.     

Synthesis of mesoporous-silica coated multi-branched gold nanoparticles for surface enhanced Raman scattering evaluation of 4-bromomethcathinone

Mesoporous silica-coated multi-branched gold nanoparticles (bAu@mesoSiO₂) aiming for enhanced Raman sensing for 4-bromomethcathinone (4-BMC) detection is reported. In this work, we present an effective strategy to probe the Raman signal of 4-MBC. Morphologies and optical properties of the synthesized materials with different [Au³⁺]/[Au⁰] ratios are characterized utilizing transmission electron microscopy (TEM), UV–vis and mid-infrared spectroscopy. Both experimental and theoretical (simulation) studies were investigated. Taking advantages of gold core branches that provide highly localized and strongly enhanced electromagnetic fields due to plasmon resonance, surface-enhanced Raman scattering (SERS) is observed. The experimental results show that the SERS intensity exhibits a 100-fold increase with the increased average length and quantity of gold branches (nano tips). The analytical performance yielded a detection limit of 0.1?mg/ml for the 4-MBC target within 5?mins. The sensing method will likely find further improvement and broad use in the forensic science. Besides rapid detection and portability, the combination of the Raman effect and enhanced materials imparts other notable advantages, such as its non-contact and free of reagents.