Polatsauer1180

Sensitive detection and effective removal of copper ions (Cu2+) from water are still arduous tasks required to protect public health and environmental safety because of the serious impacts of Cu2+ on humans and other organisms. Merestinib nmr Herein, we report the design and fabrication of self-supporting flexible amidated polyacrylonitrile/branched polyethyleneimine nanofiber membranes (abbreviated as aPAN/BPEI NMs) via facile electrospinning and a subsequent hydrothermal method, which are used not only as strips for the visual detection of Cu2+ but also as effective adsorbents for the removal of Cu2+ from water. Because aPAN/BPEI NMs are self-supporting, they can be easily removed from the solution to reduce secondary pollution to the environment. Based on the high Cu2+ binding capacity of BPEI, Cu2+ ions are adsorbed on the aPAN/BPEI NMs, which leads to the appearance of new absorbance bands at 280 and 636 nm and a color change from yellow to blue. aPAN/BPEI NMs are utilized for the visual detection of Cu2+ with a linear range of 50-700 μM and limits of detection of 11.5 and 4.8 μM (absorption peaks at 280 and 636 nm). More importantly, aPAN/BPEI NMs exhibit excellent selectivity and certain recovery with a simple treatment. Furthermore, by utilizing the adsorption characteristics of Cu2+ in aqueous media, it can be effectively removed by aPAN/BPEI NMs with a remarkable adsorption capacity of 209.53 mg·g-1. Additionally, the removal of Cu2+ by aPAN/BPEI NMs does not exhibit interference by other foreign ions. The adsorption process conforms well to the pseudo-second order (PSO) kinetic model and Jovanovich model, proving that adsorption occurs via chemical and monolayer adsorption mechanisms. Accordingly, this work will provide theoretical and technical support for the design and fabrication of novel heavy metal ion detection-removal integrated materials exhibiting high sensitivity and strong adsorption.Fluorescence bioimaging through the second near-infrared window (NIR-II, 1000-1700 nm) has attracted much attention due to its deep penetration and high contrast. However, exploring new fluorescent materials, especially small molecular fluorophores with long wavelength and high brightness, is still quite challenging. By expanding π-conjugation and enhancing the intramolecular charge transfer effect, herein we report a series of new xanthene-based NIR-II dyes, named VIXs. Among these dyes, VIX-4 exhibits the best performance with fluorescence emission at 1210 nm and high brightness and has been used for dynamically imaging the blood flow of mice at 200 fps. By virtue of high spatiotemporal resolution of the dynamic imaging, we can distinguish directly the artery and vein through the blood flow direction and measure the blood flow volume by the videos. This study provides not only an effective tool for high spatial and temporal resolution bioimaging but also a new and promising conjugated skeleton for NIR-II dyes.Preparation of edge-rich two-dimensional (2D) transition metal dichalocogenides (TMDs) has been actively investigated with the aim to improve their electrical and catalytic properties. Here, we elucidate the role of potassium ions in oxidation of TMDs and suggest a consequent novel anisotropic etching mechanism driven by self-running oxide droplets. We discover that potassium-mediated oxidation of MoS2 leads to the formation of K-intercalated hexagonal-phase molybdenum oxides (h-KxMoO3), whereas orthorhombic-phase oxides are formed in the absence of potassium ions. Metastable h-KxMoO3 appears to have decomposed into oxide droplets at higher temperature. Self-running of the oxide droplets leads to layer-by-layer anisotropic etching of MoS2 along the armchair direction. The motion of the droplets appears to be triggered by the surface energy instability between the oxide droplets and the underlying MoS2 layer. This study opens new possibilities to design and manufacture novel edge-rich 2D TMDs that do not follow the equilibrium Wulff shape by modulating their oxidation with the assistance of alkali metals and also offers fundamental insights into the interactions between nanodroplets and 2D materials toward edge engineering.We herein report a selective and catalytic C(sp3)-H functionalization approach to access amines bearing organo-sulfonyl and organo-thiol groups. This reaction proceeds through a cascade process of N-radical formation, alkyl radical formation via 1,5-HAT, and C-S bond formation, thereby offering a series of functionalized amines. This method could enable primary, secondary, and tertiary C(sp3)-H sulfonylation and thiolation and also exhibits good functional group tolerance.Single-atom alloys (SAAs) make up a special class of alloy surface catalysts that offer well-defined, isolated active sites in a more inert metal host. link2 The dopant sites are generally assumed to have little or no influence on the properties of the host metal, and transport of chemical reactants and products to and from the dopant sites is generally assumed to be facile. Here, by performing density functional theory calculations and surface science experiments, we identify a new physical effect on SAA surfaces, whereby adsorption is destabilized by ≤300 meV on host sites within the perimeter of the reactive dopant site. We identify periodic trends for this behavior and demonstrate a zone of exclusion around the reactive sites for a range of adsorbates and combinations of host and dopant metals. Experiments confirm an increased barrier for diffusion of CO toward the dopant on a RhCu SAA. This effect offers new possibilities for understanding and designing active sites with tunable energetic landscapes surrounding them.The high dependence of cathodic oxygen reduction reaction on precious Pt catalysts hinders the large-scale commercialization of proton exchange membrane (PEM) fuel cells, while the most promising alternative FeNC catalyst cannot achieve satisfying fuel cell performance yet. By considering the different requirements of atomically dispersed FeNC catalyst on the mass-transfer structure from that of nanoparticle Pt-based catalysts, this work develops a "porogen-in-resin" strategy to approach the Fe, N-doped interconnected porous carbon sheet (ip-FeNCS) catalyst. Three-dimensional (3D) interconnected porous structure and two-dimensional (2D) nanosheet morphology are therefore facilely combined in ip-FeNCS to simultaneously achieve the requirements on the transfer of reactants and accessibility of FeN active sites. Not only great ORR activity can be achieved under both alkaline and acid conditions but also the ip-FeNCS catalyst shows superb activity in practical PEM fuel cells from the high power output to 413 mW/cm2. Such fuel cell performance places this ip-FeNCS catalyst among the best FeNC ORR catalysts reported thus far. This work presents a general and facile approach toward the mass-transfer structure engineering of atomically dispersed carbon catalysts for practical PEM fuel cell applications.We reported herein a copper-catalyzed trifluoromethylarylated cycloaddition of imidazoles and olefins using CF3SO2Cl as the radical source to synthesize highly functionalized tricyclic imidazoles. This procedure exhibits a wide range of substrate scope with 25%-93% isolated yields (36 examples). Mechanistic studies were carried out to support a free trifluoromethyl radical pathway.Aromaticity is a fundamental and important concept in chemistry, and usually, the enhancement of aromaticity brings additional thermodynamic stability to a compound. Moreover, since radicals can act as intermediates in chemical reactions, they have attracted considerable attention from both experimental and theoretical chemists for a long time. However, it remains unclear whether there is a relationship between the thermodynamic stability of cyclic planar radicals and their aromaticity. In this work, using various aromaticity indices including anisotropy of the induced current density analysis and nucleus-independent chemical shifts against the radical stabilization energy, we systematically investigated the relationship between aromaticity and the thermodynamic stability of α-methyl heterocyclics. Density functional theory calculations suggest that the stronger the antiaromaticity of the original form heterocyclics, the higher the thermodynamic stability of the corresponding radicals, which is in sharp contrast to the general knowledge that aromaticity brings compounds' thermodynamic stabilities. The principal interacting spin orbital analysis shows that the stronger the π-bond formed between the heterocyclics and the α-methyl carbon, the more spin density the radicals tend to be distributed on the heterocyclics. Thus, the strong π-bonding is one of the factors for improving the thermodynamic stability of radicals.Flavonoids in grapes contribute the quality of the berry, but the flavonoid diversity and the regulatory networks underlying the variation require a further investigation. In this study, we integrated multi-omics data to systematically explore the global metabolic and transcriptional profiles in the skins and pulps of three grape cultivars. The results revealed large-scale differences involved in the flavonoid metabolic pathway. A total of 133 flavonoids, including flavone and flavone C-glycosides, were identified. Beyond the visible differences of anthocyanins, there was large variation in other sub-branched flavonoids, most of which were positively correlated with anthocyanins in grapes. The expressions of most flavonoid biosynthetic genes and the major regulators MYBA1 were strongly consistent with the changes in flavonoids. Integrative analysis identified two novel transcription factors (MYB24 and MADS5) and two ubiquitin proteins (RHA2) as promising regulatory candidates for flavonoid biosynthesis in grapes. Further verification in various grape accessions indicated that five major genes including flavonol 3'5'-hydroxylase (F3'5'H), UDP-glucoseflavonoid 3-O-glycosyl-transferase, anthocyanin O-methyltransferase, acyltransferase (3AT), and glutathione S-transferase (GST4) controlled flavonoid variation in grape berries. These findings provide valuable information for understanding the mechanism of flavonoid biosynthesis in grape berries and the further development of grape health products.A thorough characterization of the textural properties of hierarchical porous carbons (HPCs) is of utmost importance as it provides information that aids in the selection of a suitable material for a given application and in understanding the phenomena observed once the material becomes part of a system. link3 Gas adsorption-desorption isotherms coupled with the application of density functional theory (DFT) models to these isotherms are common tools for the textural characterization of HPCs, for which pore shape is an essential factor for the determination of pore size distributions (PSDs). By analyzing the experimental adsorption data of a series of CO2-activated HPCs with a progressive development of porosity, it is shown that artifacts are found in the derived PSDs when a slit-cylinder pore shape boundary is fixed at 2 nm, which is the case for the original dual-shape nonlocal DFT (2D-NLDFT-HS) and hybrid quenched solid DFT (QSDFT) models. This study presents a new dual-shape 2D-NLDFT-HS (DS-HS) model that, combined with the 2D-NLDFT-HS model for CO2, provides the possibility of analyzing simultaneously N2 and CO2 adsorption-desorption isotherms and adjusting at the same time the limits for the assumed slit and cylindrical pore shapes.