391 research outputs found

    Palladium-Catalyzed <i>ortho</i>-C–H Alkoxycarbonylation of Aromatic Aldehydes via a Transient Directing Group Strategy

    No full text
    Transient directing groups (TDGs) can be a powerful strategy for directly functionalizing C–H bonds of aldehydes. We report a palladium-catalyzed o-C–H alkoxycarbonylation of benzaldehydes using a catalytic amount of aromatic amine to form a transient imine that plays the role of a monodentate TDG. The reaction conditions were applied to a broad range of aldehydes, and the corresponding 2-formyl benzoates were used as direct precursors for the synthesis of phthalides and 1-isoindolinones

    20190601-Supplementary_material-corrected – Supplemental material for Mid-Holocene drylands: A multi-model analysis using Paleoclimate Modelling Intercomparison Project Phase III (PMIP3) simulations

    No full text
    Supplemental material, 20190601-Supplementary_material-corrected for Mid-Holocene drylands: A multi-model analysis using Paleoclimate Modelling Intercomparison Project Phase III (PMIP3) simulations by Shanshan Liu, Dabang Jiang and Xianmei Lang in The Holocene</p

    Flexible Thermopiles Based on Hydrogels with Carriers Moving in Opposite Directions

    No full text
    Thermoelectric generators based on body heat are green, sustainable, and flexible power sources, and their efficiency could be greatly improved by thermopiles. Herein, a unique concept of thermopiles is proposed in which two types of hydrogels with positively charged carriers moving in different directions are fabricated. One of them shows a positive Seebeck coefficient of 3.81 mV/K due to the movement of cations from the cold to hot region, while the other displays a negative Seebeck coefficient of āˆ’2.33 mV/K due to the movement of cations in the opposite direction. Notably, the Seebeck coefficient of the latter is increased by 50 times in comparison to that of the original component due to the conversion from an electronic to an ionic thermoelectric conductor. Also, the thermopile with a Seebeck coefficient of 6.18 mV/K shows excellent flexibility and stability when applied in wearable textiles. Compared to traditional wearable thermopiles, the thermopiles based on hydrogels containing carriers with opposite thermal motion directions exhibit a much more outstanding thermoelectric performance. This work contributes to addressing the lack of n-type thermoelectric materials and extending the field of thermoelectric devices

    Additional file 1 of Metabolomic analysis for asymptomatic hyperuricemia and gout based on a combination of dried blood spot sampling and mass spectrometry technology

    No full text
    Additional file 1: Figure S1. A 200-times permutation test for assessing the performance of PLS-DA model among control group, asymptomatic hyperuricemia, and gout. Table S1. Detected metabolites in control, AHU, and gout groups

    Pyrolysis-Free Synthesis of Bimetal Phthalocyanine Covalent Organic Polymers/Ordered Mesoporous Carbon Nanocomposites for an Efficient Oxygen Reduction Reaction

    No full text
    The development of non-noble metal–nitrogen ring complex (M–N–C) catalysts with high activity and stability for the oxygen reduction reaction (ORR) is of great significance. However, M–N–C catalysts are generally prepared from precursors under high-temperature pyrolysis, which leads to complex product structures and makes it difficult to identify the catalytic active center. Herein, we have successfully structured a novel bimetal phthalocyanine covalent organic polymer/ordered mesoporous carbon (CoFe-COP/OMC) electrocatalyst through a pyrolysis-free approach. Due to the well-defined active sites (Fe/CoN4), ordered COP structure, and highly conductive carrier materials, the CoFe-COP/OMC nanocomposite exhibits remarkable ORR electrocatalytic activity with a half-wave potential and initial potential of 0.908 and 0.932 V (vs reversible hydrogen electrode (RHE)), respectively, a limiting current density of 5.35 mA cm–2, and a nearly four-electron reduction pathway. In addition, the acquired hybrid catalysts show excellent methanol resistance and electrochemical stability compared with Pt/C. The outstanding performance confirms that the CoFe-COP/OMC nanocomposite is a promising high-efficiency ORR catalyst for metal–air batteries and fuel cells

    Conversion of Pyridine <i>N</i>‑Oxides to Tetrazolopyridines

    No full text
    An efficient and convenient procedure for the conversion of pyridine N-oxides to tetrazolopyridines by treatment with 4-toluene sulfonyl chloride and sodium azide in toluene at elevated temperature is described

    Conversion of Pyridine <i>N</i>‑Oxides to Tetrazolopyridines

    No full text
    An efficient and convenient procedure for the conversion of pyridine <i>N</i>-oxides to tetrazolopyridines by treatment with 4-toluene sulfonyl chloride and sodium azide in toluene at elevated temperature is described

    A hydrophobic bio-adsorbent synthesized by nanoparticle-modified graphene oxide coated corn straw pith for dye adsorption and photocatalytic degradation

    No full text
    A novel bio-adsorbent was prepared from corn straw pith (CSP), graphene oxide (GO) and TiO2 through one-step synthesis for adsorption and photocatalytic reduction of dyes. CSP and GO acted as stent and coat, respectively. TiO2 nanoparticles attached on the surface of the adsorbent played a role in the degradation of dyes and endowed the adsorbent with hydrophobicity. When the loading of GO and TiO2 were 5 and 20 wt.% respectively, the adsorbent had quite an ideal structure and satisfactory removal efficiency. There were an electrostatic attraction, hydrophobic and π–π interactions in the process of adsorption. The pseudo-second-order and the Langmuir model described the adsorption behaviour well. The dyes loaded on the adsorbent could be degraded by irradiation with ultraviolet light (UV). After five cycles, the removal efficiency of malachite green, methylene blue and rhodamine b by CSP-5GO-20TiO2 decreased by 3.77%, 23.89% and 32.01%, respectively. Therefore, the bio-adsorbent has the advantages of economy, environmental protection, and the concept of sustainable development.</p
    • …
    corecore