Electrochemical Investigations of Mn and Al Co‐doped Li2FeSiO4/C Cathodes for Li‐Ion Battery

Few studies on orthosilicate cathodes co‐doped with two cations have been reported until now. Here, we report the synthesis of Mn and Al co‐doped Li₂Fe_0.8?xMn_0.2Al_xSiO₄ (x = 0.05 and 0.1) by a solid‐state reaction route and characterized by X‐ray diffraction (XRD), particle size analysis, scanning electron microscopy (SEM), galvanostatic charge/discharge tests, and capacity intermittent titration technique (CITT), as compared to the single‐doped Li₂Fe_0.8Mn_0.2SiO₄. Though the co‐doping leads to a slight decreased capacity owing to the increased impurity and Al³⁺ inertia, a better cycling performance is obtained as expected. Especially when x is 0.05, the modified sample (Li₂Fe_0.75Mn_0.2Al_0.05SiO₄) shows an initial discharge capacity of 159.3 mAh/g and high capacity retention of 78% after 50 charge/discharge cycles. The present work indicates that a synergistic effect of Mn and Al co‐substitution at the Fe site could partly make up the disadvantage of single Mn doping, and might provide an effective guide for the dopant incorporation to Li₂FeSiO₄ systems.     

Environment‐sensitive Fluorescent Turn‐on Chemical Probe for the Specific Detection of O‐Methylguanine‐DNA Methyltransferase (MGMT) in Living Cells

MGMT protein, which has been associated with resistance to antitumor alkylation drugs for many patients, is a very useful prognostic marker to provide a guide for therapeutic decisions. Considering the large number of cellular samples that have to be handled daily at the hospitals, it is thus important to develop a rapid and simple analytical method to distinguish MGMT activity in different types of cells. In this paper, we describe a MGMT‐activated fluorescence turn‐on probe for the rapid no‐wash imaging of MGMT in living cells. The probe consists of a specific MGMT suicide pseudosubstrate, O⁶‐benzyl‐guanine and an environment‐sensitive fluorophore, SBD. In the presence of MGMT, the enzyme transfers SBD to the protein active site where the hydrophobic surrounding causes the fluorophore to exhibit more than 50‐fold fluorescence enhancement. With this probe, bright fluorescence was observed for MGMT‐positive, Hela S3 and MCF‐7 cells, while MGMT‐deficient CHO cells displayed no fluorescence. We believe that this fluorescence activation probe design can also be extended to detect other transferases, for which there are still no effective methods to image them in living cells.     

Promotional effect of cobalt addition on catalytic performance of Ce<Subscript>0.5</Subscript>Zr<Subscript>0.5</Subscript>O<Subscript>2</Subscript> mixed oxide for diesel soot combustion

A series of Co-modified Ce_0.5Zr_0.5O₂ catalysts with different concentrations of Co (mass %: 0, 2, 4, 6, 8, 10) was investigated for diesel soot combustion. Ce_0.5Zr_0.5O₂ was prepared using the coprecipitation method and Co was loaded onto the oxide using the incipient wetness impregnation method. The activities of the catalysts were evaluated by thermogravimetric (TG) analysis and temperature-programmed oxidation (TPO) experiments. The results showed the soot combustion activities of the catalysts to be effectively improved by the addition of Co, 6 % Co/Ce_0.5Zr_0.5O₂ and that the 8 % Co/Ce_0.5Zr_0.5O₂ catalysts exhibited the best catalytic performance in terms of lower soot ignition temperature (T_i at 349°C) and maximal soot oxidation rate temperature (T_m at 358°C). The reasons for the improved activity were investigated by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), H₂ temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). These results revealed that the presence of Co could lower the reduction temperature due to the synergistic effect between Co and Ce, thereby improving the activity of the catalysts in soot combustion. The 6 % Co catalyst exhibited the best catalytic performance, which could be attributed to the greater amounts of Co³⁺ and surface oxygen species on the catalyst.     

Visualization of Vibrational Modes in Real Space by Tip‐Enhanced Non‐Resonant Raman Spectroscopy

We present a general theory to model the spatially resolved non‐resonant Raman images of molecules. It is predicted that the vibrational motions of different Raman modes can be fully visualized in real space by tip‐enhanced non‐resonant Raman scattering. As an example, the non‐resonant Raman images of water clusters were simulated by combining the new theory and first‐principles calculations. Each individual normal mode gives rise its own distinct Raman image, which resembles the expected vibrational motions of the atoms very well. The characteristics of intermolecular vibrations in supermolecules could also be identified. The effects of the spatial distribution of the plasmon as well as nonlinear scattering processes were also addressed. Our study not only suggests a feasible approach to spatially visualize vibrational modes, but also provides new insights in the field of nonlinear plasmonic spectroscopy.     

Interface Engineering in Two‐Dimensional Heterostructures: Towards an Advanced Catalyst for Ullmann Couplings

The design of advanced catalysts for organic reactions is of profound significance. During such processes, electrophilicity and nucleophilicity play vital roles in the activation of chemical bonds and ultimately speed up organic reactions. Herein, we demonstrate a new way to regulate the electro‐ and nucleophilicity of catalysts for organic transformations. Interface engineering in two‐dimensional heteronanostructures triggered electron transfer across the interface. The catalyst was thus rendered more electropositive, which led to superior performance in Ullmann reactions. In the presence of the engineered 2D Cu₂S/MoS₂ heteronanostructure, the coupling of iodobenzene and para‐chlorophenol gave the desired product in 92 % yield under mild conditions (100 °C). Furthermore, the catalyst exhibited excellent stability as well as high recyclability with a yield of 89 % after five cycles. We propose that interface engineering could be widely employed for the development of new catalysts for organic reactions.     

Solution‐Liquid‐Solid Synthesis of Hexagonal Nickel Selenide Nanowire Arrays with a Nonmetal Catalyst

Inorganic nanowire arrays hold great promise for next‐generation energy storage and conversion devices. Understanding the growth mechanism of nanowire arrays is of considerable interest for expanding the range of applications. Herein, we report the solution‐liquid‐solid (SLS) synthesis of hexagonal nickel selenide nanowires by using a nonmetal molecular crystal (selenium) as catalyst, which successfully brings SLS into the realm of conventional low‐temperature solution synthesis. As a proof‐of‐concept application, the NiSe nanowire array was used as a catalyst for electrochemical water oxidation. This approach offers a new possibility to design arrays of inorganic nanowires.     

Dual‐Targeting Nanovesicles for In Situ Intracellular Imaging of and Discrimination between Wild‐type and Mutant p53

p53 is a tumor‐suppressor protein related to the cell cycle and programmed cell apoptosis. Herein, dual‐targeting nanovesicles are designed for in situ imaging of intracellular wild‐type p53 (WTp53) and mutant p53 (MUp53). Nanovesicle‐encapsulated plasmonic gold nanoparticles (AuNPs) were functionalized with consensus DNA duplexes, and a fluorescein isothiocyanate (FITC)‐marked anti‐MUp53 antibody was conjugated to the nanovesicle surface. After entering the cytoplasm, the released AuNPs aggregated through recognition of WTp53 and the double‐stranded DNA. The color changes of AuNPs were observed using dark‐field microscopy, which showed the intracellular WTp53 distribution. The MUp53 location was detected though the immunological recognition between FITC‐labeled anti‐MUp53 and MUp53. Thus, a one‐step incubation method for the in situ imaging of intracellular WTp53 and MUp53 was obtained; this was used to monitor the p53 level under a drug treatment.     

Isolating Reactions at the Picoliter Scale: Parallel Control of Reaction Kinetics at the Liquid–Liquid Interface

Miniaturized liquid–liquid interfacial reactors offer enhanced surface area and rapid confinement of compounds of opposite solubility, yet they are unable to provide in situ reaction monitoring at a molecular level at the interface. A picoreactor operative at the liquid–liquid interface is described, comprising plasmonic colloidosomes containing Ag octahedra strategically assembled at the water‐in‐decane emulsion interface. The plasmonic colloidosomes isolate ultrasmall amounts of solutions (<200 pL), allowing parallel monitoring of multiple reactions simultaneously. Using the surface‐enhanced Raman spectroscopy (SERS) technique, in situ monitoring of the interfacial protonation of dimethyl yellow (p‐dimethylaminoazobenzene (DY)) is performed, revealing an apparent rate constant of 0.09 min^?1 for the first‐order reaction. The presence of isomeric products with similar physical properties is resolved, which would otherwise be indiscernible by other analytical methods.     

Cyclometalated Palladium(II) N‐Heterocyclic Carbene Complexes: Anticancer Agents for Potent In Vitro Cytotoxicity and In Vivo Tumor Growth Suppression

Palladium(II) complexes are generally reactive toward substitution/reduction, and their biological applications are seldom explored. A new series of palladium(II) N‐heterocyclic carbene (NHC) complexes that are stable in the presence of biological thiols are reported. A representative complex, [Pd(C^N^N)(N,N′‐nBu₂NHC)](CF₃SO₃) ( Pd1 d , HC^N^N=6‐phenyl‐2,2′‐bipyridine, N,N′‐nBu₂NHC=N,N′‐di‐n‐butylimidazolylidene), displays potent killing activity toward cancer cell lines (IC₅₀=0.09–0.5 μm ) but is less cytotoxic toward a normal human fibroblast cell line (CCD‐19Lu, IC₅₀=11.8 μm ). In vivo anticancer studies revealed that Pd1 d significantly inhibited tumor growth in a nude mice model. Proteomics data and in vitro biochemical assays reveal that Pd1 d exerts anticancer effects, including inhibition of an epidermal growth factor receptor pathway, induction of mitochondrial dysfunction, and antiangiogenic activity to endothelial cells.     

Bioassay‐guided isolation of an active compound with protein tyrosine phosphatase 1B inhibitory activity from Sargassum fusiforme by high‐speed counter‐current chromatography

A rapid and efficient method using high‐speed counter‐current chromatography was established for the bioassay‐guided separation of an active compound with protein tyrosine phosphatase 1B inhibitory activity from Sargassum fusiforme. Under the bioassay guidance, the ethyl acetate extract with the best IC₅₀ value of 0.37 ± 0.07 μg/mL exhibited a potential protein tyrosine phosphatase 1B inhibitory activity, which was further separated by high‐speed counter‐current chromatography. The separation was performed with a two‐phase solvent system composed of n‐hexane/methanol/water (5:4:1, v/v). As a result, dibutyl phthalate (19.7 mg) with the purity of 95.3% was obtained from 200 mg of the ethyl acetate extract. Its IC₅₀ was 14.05 ± 0.06 μM, which was further explained by molecular docking. The result of molecular docking showed that dibutyl phthalate enfolded in the catalytic site of protein tyrosine phosphatase 1B. The main force between dibutyl phthalate and protein tyrosine phosphatase 1B was the hydrogen bond interaction with Gln266. In addition, hydrogen bond, van der Waals force and hydrophobic interaction with the amino acids (Ala217, Ile219, and Gly220) were also responsible for the stable protein‐ligand complex.