Many types of metal and semiconductor nanoparticles (NPs) are created via colloidal synthetic methods, which renders the materials hydrophobic. Such NPs are dispersed in water through surface organic cap exchange or by amphiphilic polymer encapsulation; often, water solubility is achieved via the presence of carboxylic acid functionalities on the solubilizing agents. While this renders the material water-soluble, subsequent functionalization of the systems can be very difficult. The most obvious method to derivatize carboxylic acid coated NPs is to conjugate chemical and biological moieties containing amine functionality to the NP surface using the water-soluble activator 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). However, the excess use of this reagent appears to cause complete and permanent precipitation of the NPs. We report here our method on the chemical and biological functionalization of a variety of semiconductor nanoparticle systems using novel carbodiimide reagents. These reagents do not cause precipitation even at high loading levels and can be used to efficiently functionalize carboxylic acid coated NPs.

The rational design of advanced structures consisting of multiple components with excellent electrochemical capacitive properties is one of the crucial hindrances to be overcome for high‐performance supercapacitors (SCs). Herein, a superfast and facile synthesis of flower‐like NiMn‐layered double hydroxides (NiMn‐LDH) with high SC performance using an electrodeposition process on nickel foam is proposed. Oxygen vacancies are then modulated via mild H2O2 treatment for the first time, significantly promoting the electrochemical energy storage performance. The oxygen‐vacancy abundant NiMn‐LDH (Ov‐LDH) reaches a maximum specific capacity of 1183 C g−1 at the current density of 1 A g−1 and retains a high capacity retention of 835 C g−1 even at a current density of up to 10 A g−1. Furthermore, the assembled asymmetric SC device achieves a high specific energy density of 46.7 Wh kg−1 at a power density of 1.7 kW kg−1. Oxygen vacancies are proven to play a vital role in the improvement of electrochemistry performance of LDH based on experimental and theoretical studies. This vacancy engineering strategy provides a new insight into SC active materials and should be beneficial for the design of the next generation of energy storage devices.

Due to the high surface ratio and dispersed metal sites, organometallic sheets provide a very special platform for catalysis. Here we investigate the CO2 electroreduction performance of expanded phthalocyanine sheets with different transition metal dimers using density functional theory. We have determined Mn dimer to be the best active center, and the reaction path CO2 → COOH* → CO* → CHO* → CH2O* → CH3O* → CH3OH is identified as the preferable one with the overpotential of 0.84 eV. Electronic structures analyses show that σ-bonding−π-backbonding mode exists when COOH* adsorbed on Mn2-Pc, which is different from the bonding mode on Mn-Pc counterpart. Our study indicates that the introduction of metal dimer in porous covalent organic frameworks provides a new strategy for the design of catalytic materials for CO2 electroreduction.

Developing noble metal-free bifunctional oxygen electrocatalysts is vital for metal−air batteries. Herein, we present a facile approach to fabricating N-doped carbon nanosheet networks with metal nanoparticles (M/N-CNSNs) readily converted from metal−organic frameworks. The resultant Co/N-CNSNs show superior bifunctional oxygen catalytic activity attributed to the efficient active sites and fast mass diffusion enabled by the nanosheet structure. It is worth noting that the first-principles studies prove the Co/N−C sites to be the oxygen reduction reaction active sites, where the most favorable ones are the carbon atoms next to Co-coordinated pyridinic N. Interestingly, the cobalt content plays an important role in Co/N−C sites but was not directly involved in the catalytic process. In a Zn−air battery, a small voltage gap without obvious voltage loss is found for the Co/N-CNSNs. This facile approach enables scalable synthesis, representing an essential step toward the popularization of metal−air batteries.

ROS induce the recruitment of PRDX6 to mitochondria, where PRDX6 controls ROS homeostasis in the initial step of PINK1-Parkin-mediated mitophagy. Our study provides new insight into the initial regulatory mechanisms of mitophagy and reveals the protective role of PRDX6 in the clearance of damaged mitochondria.

Amyloid plaques are crucial for the pathogenesis of Alzheimer disease (AD). Phagocytosis of fibrillar ␤-amyloid (A␤) by activated microglia is essential for A␤ clearance in Alzheimer disease. However, the mechanism underlying A␤ clearance in the microglia remains unclear. In this study, we performed stable isotope labeling of amino acids in cultured cells for quantitative proteomics analysis to determine the changes in protein expression in BV2 microglia treated with or without A␤. Among 2742 proteins identified, six were significantly up-regulated and seven were down-regulated by A␤ treatment. Bioinformatic analysis revealed strong over-representation of membrane proteins, including lipoprotein lipase (LPL), among proteins regulated by the A␤ stimulus. We verified that LPL expression increased at both mRNA and protein levels in response to A␤ treatment in BV2 microglia and primary microglial cells. Silencing of LPL reduced microglial phagocytosis of A␤, but did not affect degradation of internalized A␤. Importantly, we found that enhanced cyclin-dependent kinase 5 (CDK5) activity by increasing p35-to-p25 conversion contributed to LPL up-regulation and promoted A␤ phagocytosis in microglia, whereas inhibition of CDK5 reduced LPL expression and A␤ internalization. Furthermore, A␤ plaques was increased with reducing p25 and LPL level in APP/PS1 mouse brains, suggesting that CDK5/p25 signaling plays a crucial role in microglial phagocytosis of A␤. In summary, our findings reveal a potential role of the CDK5/p25-LPL signaling pathway in A␤ phagocytosis by microglia and provide a new insight into the molecular pathogenesis of Alzheimer disease. Molecular & Cellular

This paper studies the possibility of using a laser-generated ‘‘plasma waveguide’’ to transfer electromagnetic (EM) energy. The plasma waveguide is a cylindrical vacuum core surrounded by a plasma cladding. The analysis shows that guided-mode fields do exist inside the core. Like a general dielectric waveguide, the plasma waveguide is characterized by a ‘‘normalized frequency parameter’’ (also called the V number). Although the permittivity of the plasma varies strongly with frequency, the V number surprisingly remains constant over the entire frequency range. Because of this property, the frequency dependence of the plasma waveguide is different; it has a wider high-frequency response than the general dielectric waveguide. The EM pulse can propagate in the plasma waveguide at close to the speed of light and keep its profile and shape unchanged. When the V number is smaller than 2.4048 (the first root of the zero-order Bessel function), only the single HE11 mode exists in the plasma waveguide. Unlike the dielectric waveguide, however, there is no high-frequency limitation for single-mode propagation. The EM fields outside the core in the plasma decrease exponentially with increasing radius. Thus, practically, a plasma cladding of sufficient thickness is all that is required to confine the EM wave. Such a plasma waveguide can be generated by a hollow laser beam in upper space and used for guiding EM pulses. A brief survey on laser-generated plasmas is given.

The good performance of Cu displayed in CO2 conversion promotes the study on how to disperse Cu into 2D materials for better catalysis. Inspired by the recent studies on new 2D porous B sheets [Angew. Chem., Int. Ed., 2017, 56, 10093; Adv. Mater., 2018, 30, 1704025; Phys. Rev. Lett., 2017, 118, 096401], here for the first time we have explored the catalytic properties of Cu atomic chains on β-borophene sheets, and have found that the Cu-B sheet can break the scaling relationship through providing secondary adsorption sites, thus leading to small overpotentials in the preferable reaction pathway CO2 → COOH* → CO* → CHO* → CH2O* → CH3O* → CH3OH. The Cu atomic chains also lower the energy barrier by forming assistant adsorptions of H*. Electronic structure analyses further show that the Cu atomic chain structure stabilizes the CHO* bonding through an enhanced σ bonding-π back-bonding mode. Our study not only sheds light on the design of new catalysts for effective CO2 conversion but also expands the applications of B sheets.