Ceria nanoclusters coupled with Ce-Nx sites for efficient oxygen reduction in Zn-air batteries.

Rational construction of efficient carbon-supported rare earth cerium nanoclusters as oxygen reduction reaction (ORR) is of great significance to promote the practical application of zinc-air batteries (ZABs). Herein, N doped conductive carbon black anchored CeO2 nanoclusters (CeO2 Clusters/NC) for the ORR is reported. The volatile cerium species vaporized by CeO2 nanoclusters at high temperatures are captured by nitrogen-rich carbon carriers to form highly dispersed Ce-Nx active sites. Benefiting from the coupling effect between oxygen vacancies-enriched CeO2 nanoclusters and highly dispersed Ce-Nx sites, the prepared 2CeO2 Clusters/NC catalyst possesses an ORR half-wave potential of 0.88 V, superior electrochemical stability, and better methanol tolerance compared to commercial Pt/C catalysts. Moreover, the 2CeO2 Clusters/NC involved liquid ZABs show excellent energy efficiency, superior stability, and a high energy density of 982 Wh kg-1 at 10 mA cm-2.

The Dual Role of Astrocyte-Derived Exosomes and Their Contents in the Process of Alzheimer's Disease.

Millions of patients worldwide are affected by Alzheimer's disease (AD), and the number of patients with AD is increasing. However, current treatment can only improve symptoms but cannot cure the disease. Astrocytes, glial cells in the central nervous system, play important roles in support, nutrition, protection, and information transmission in the nervous system. Pathological changes in astrocytes are closely associated with the development and progression of AD. As carriers for material and information exchange between astrocytes and other neural cells, astrocyte-derived exosomes (ADEs) have been widely studied in recent years, and ADE secretion has been shown to be increased in patients with AD and animal models of AD. ADEs contain a variety of substances, including nucleic acids, proteins, and lipids. The contents of ADEs can effectively control oxidative stress and detoxification during the early development of AD, thereby playing positive and negative roles in the occurrence and development of AD. In this review, we elaborate on the functions of ADEs and their components in AD and discuss their applications in AD research and clinical practice.

Immobilization of Cytochrome C by Benzoic Acid (BA)-Functional UiO-66-NO2 and the Enzyme Activity Assay.

Recently, metal-organic frameworks (MOFs) are considered to be the moderate hosts for the bio-enzymes owing to their unique 3D pores and controllable surface affinity to the target molecules. In this work, the benzoic acid (BA)-modulated UiO-66-NO2 was introduced, and cytochrome c (Cyt C) was chosen as the target enzyme to evaluate the immobilization efficiency of the resulting UiO-66-NO2-BA. The immobilization conditions including pH, adsorption time, and temperature and the initial concentrations of BA were optimized. The adsorption kinetics and thermodynamics were analyzed to further explore the enhanced adsorption mechanism. It is worth noted that all the UiO-66-NO2-BA exhibited evidently enhanced adsorption capacities in comparison with the unmodified UiO-66-NO2 due to the formation of the chemical bonds between the UiO-66-NO2-BA and cytochrome C, indicating the positive roles of BA modification. Finally, the activities of the immobilized cytochrome C were assessed by using the catalytic oxidation of ABTS in the presence of H2O2, which reactions were also conducted over the free cytochrome C for comparison. The evidently improved stability under definite pH range, prolonged durability against the organic solvents, and the good reusability of the immobilized cytochrome C highlight the prospect applications of functional MOF immobilized enzymes in the practical catalytic reactions.

Efficient immobilization of catalase on mesoporous MIL-101 (Cr) and its catalytic activity assay.

Enzyme immobilization using metal-organic frameworks (MOFs) as carriers has aroused significant interest owing to the unique pore structure and versatile surface functional groups of MOFs. Catalase (CAT) is an important industrial enzyme that is widely used in the catalytic decomposition of hydrogen peroxide in the fields of food and biological products. In this study, mesoporous MIL-101 (Cr), synthesized through a facile hydrothermal process, was applied for CAT immobilization for the first time. The immobilization capacity of MIL-101 (Cr) for CAT was studied systematically by batch adsorption tests under different adsorption conditions, including the variation of the solution pH, operation temperature, adsorption time, and initial concentration of CAT. Based on these test findings, the optimum adsorption conditions and maximum adsorption capacity were determined. The adsorption kinetics were simulated to further explore the adsorption mechanism, and they suggest that chemical adsorption, rather than physical adsorption, is the main CAT adsorption mechanism. A comparison of Fourier transform infrared (FT-IR) spectra of MIL-101 (Cr) without and with adsorbed CAT reveals the formation of amide bonding between the -NH of CAT and the uncoordinated -CO of MIL-101(Cr). Finally, the stability and activity of the immobilized CAT were assessed, and an improved insensitivity against changes in pH and a prolonged storage time demonstrate the enhanced stability of immobilized CAT by MIL-101 (Cr) carriers. This study demonstrates the application of MOFs as functional supports for the efficient immobilization of versatile enzymes.

Copper ions-assisted inorganic dynamic porogen of graphene-like multiscale microporous carbon nanosheets for effective carbon dioxide capture.

The superior ultramicroporosity and enriched surface CO2-philic sites are simultaneously required features for high-efficiency carbon-based CO2 adsorbents. Unfortunately, these characteristics are usually incompatible and difficult to integrate into one porous carbon material. Herein, we report a new copper ions (Cu2+)-assisted dynamic porogen to construct hierarchically microporous carbon nanosheets in a large scale with high heterogeneity for solving such issue. Cu2+ can be equably dispersed in precursor by coordination interactions of COO-Cu and Cu-N, which can anchor more N/O-containing species in final product. The reduced cuprous ions (Cu+) in pyrolysis process functions as a dynamic porogen to tailor uniform ultramicropores. Importantly, copper salt extracted in this synthetic procedure allows cyclic utilization, realizing a green and low-cost process. The obtained carbon sheets possess a graphene-like morphology, a high surface area and a high-proportioned multiscale microporosity, especially a high-density ultramicropores of 0.4-0.7 nm and supermicroproes of 0.8-1.5 nm. The maximized synergistic effect of morphology, high density of multi-sized ultramicroporosity and surface high heterogeneity endow the resultant microporous carbon nanosheets with the remarkable CO2 capture property, including a high uptake, a moderate adsorption heat, a good selectivity and superior recyclability.

Benzodioxole derivative as coinitiator for dental resin.

OBJECTIVE: The aim of this work was to examine whether it was possible to substitute benzodioxole derivatives for amine as coinitiators for dental application. MATERIAL AND METHODS: A mixture of urethane dimethacrylate (UDMA)/triethylene glycol dimethacrylate (TEGDMA) (70/30 wt%), camphorquinone (CQ) and coinitiators was photocured. Real time Fourier Transform Infrared Spectroscopy with a horizontal sample holder was used to monitor the extent of polymerization. Dynamic mechanical analysis was performed over a temperature range from -50 degrees C to 200(o)C, with a ramping rate of 5(o)C per minute, using extension mode. RESULTS: Benzodioxole derivatives as coinitiator improved the rate of polymerization and final double bond conversion of the dental resin. The cured samples showed similar properties, e.g. modulus, glass transition temperature, water sorption and solubility. CONCLUSION: The results indicate that two benzodioxole derivatives, piperonyl alcohol (PAL) and benzodioxole (BDO), are viable alternatives to conventional amines as coinitiator. The biocompatibility of benzodioxole derivatives makes them more promising than amine in dental resin formulations.