Nonaqueous rechargeable lithium–oxygen batteries (LOBs) are one of the most promising candidates for future electric vehicles and wearable/flexible electronics. However, their development is severely ...hindered by the sluggish kinetics of the ORR and OER during the discharge and charge processes. Here, we employ MOF-assisted spatial confinement and ionic substitution strategies to synthesize Ru single atoms riveted with nitrogen-doped porous carbon (Ru SAs-NC) as the electrocatalytic material. By using the optimized Ru0.3 SAs-NC as electrocatalyst in the oxygen-breathing electrodes, the developed LOB can deliver the lowest overpotential of only 0.55 V at 0.02 mA cm–2. Moreover, in-situ DEMS results quantify that the e–/O2 ratio of LOBs in a full cycle is only 2.14, indicating a superior electrocatalytic performance in LOB applications. Theoretical calculations reveal that the Ru–N4 serves as the driving force center, and the amount of this configuration can significantly affect the internal affinity of intermediate species. The rate-limiting step of the ORR on the catalyst surface is the occurrence of 2e– reactions to generate Li2O2, while that of the OER pathway is the oxidation of Li2O2. This work broadens the field of vision for the design of single-site high-efficiency catalysts with maximum atomic utilization efficiency for LOBs.
Reported herein is the first direct, metal‐catalyzed reductive functionalization of secondary amides to give functionalized amines and heterocycles. The method is shown to have exceptionally broad ...scope with respect to suitable nucleophiles, which cover both hard and soft C nucleophiles as well as a P nucleophile. The reaction exhibits good chemoselectivity and tolerates several sensitive functional groups.
A soft touch: A versatile, direct, metal‐catalyzed reductive functionalization reaction of secondary amides, to give functionalized amines and heterocycles, was developed. A broad substrate scope for both the amide and nucleophile was observed. Viable nucleophiles include reactive and soft C nucleophiles as well as a P nucleophile. The reaction exhibits good chemoselectivity and tolerates several sensitive functional groups (FGs).
Polymer nanocomposites have been investigated for about three decades. To get deep insights into the modifying effects of various nanofillers on mechanical and physical properties of polymer ...nanocomposites, the three basic aspects of processing, characterization and properties are critically reviewed in this paper. Nanofillers can be classified into three major types of two-dimensional (2D) layered, one-dimensional (1D) fibrous and zero-dimensional (0D) spherical ones and this review thus discusses in detail the processing, characterization and properties of the three types of polymer nanocomposites. It starts with an introduction of various nanoscale fillers such as two-dimensional (2D) nano-clay, graphene and MXene, one dimensional (1D) carbon nanofibers and nanotubes, zero dimensional (0D) silica nanoparticles and ZnO quantum dots as well as nanofiller-polymer interfaces. The processing of these polymer nanocomposites using different methods and the characterization of nanofillers and polymer nanocomposites using various techniques are described. Finally, the mechanical and physical properties of these polymer nanocomposites are discussed by considering the effects of nanofiller type, dispersion and contents; also, interface properties show significant effects on the mechanical properties of polymer nanocomposites and are discussed in some details. Keywords: Polymer nanocomposite, Nanofiller, Processing, Characterization, Mechanical and physical properties
Thermal transport in graphene–polymer nanocomposite is complicated and has not been well understood. The interfacial thermal transport between graphene nanofiller and polymer matrix is expected to ...play a key role in controlling the overall thermal performance of graphene–polymer nanocomposite. In this work, we investigated the thermal transport across graphene–polymer interfaces functionalized with end-grafted polymer chains using molecular dynamics simulations. The effects of grafting density, chain length and initial morphology on the interfacial thermal transport were systematically investigated. It was found that end-grafted polymer chains could significantly enhance interfacial thermal transport and the underlying mechanism was considered to be the enhanced vibration coupling between graphene and polymer. In addition, a theoretical model based on effective medium theory was established to predict the thermal conductivity in graphene–polymer nanocomposites.
All-solid-state sodium-ion battery is regarded as the next generation battery to replace the current commercial lithium-ion battery, with the advantages of abundant sodium resources, low price and ...high-level safety. As one critical component in sodium-ion battery, solid-state electrolyte should possess superior operational safety and design simplicity, yet reasonable high room-temperature ionic conductivity. This paper gives a comprehensive review on the recent progress in solid-state electrolyte materials for sodium-ion battery, including inorganic ceramic/glass-ceramic, organic polymer and ceramic-polymer composite electrolytes, and also provides a comparison of the ionic conductivity in various solid-state electrolyte materials. The development of solid-state electrolytes suggests a bright future direction: all solid-state sodium-ion battery could be fully used to power all electric road vehicles, portable electronic devices and large-scale grid support. Keywords: Sodium ion battery, Ionic conductivity, Inorganic solid electrolyte, Solid polymer electrolyte, Ceramic-polymer composite electrolyte
Flexible ultrasensitive piezoresistive strain sensors were fabricated by CO2 Laser ablating of the surface of the multiwall carbon nanotube/polydimethylsiloxane (MWCNT/PDMS) composite film prepared ...by a coating process. The effects of the MWCNT content and the applied laser power on the electrical and sensing performances of the MWCNT/PDMS composite strain sensor were systematically investigated. It is found that, after laser ablating, the electrical conductivity and the sensing gauge factor of the MWCNT/PDMS film were greatly improved only by the addition of 1.0 wt% of MWCNT, which is below the percolation threshold of the MWCNT in the PDMS matrix. A novel boscage-like structure at the surface of the film formed by the ablation of the PDMS and the rearrangement of the MWCNT during the laser ablating process was found responsible for the ultrahigh gauge factor of the composite strain sensor, which is about 513 at the strain of 5.0%. The facile and cost-effective fabrication process of the flexible ultrasensitive strain sensor could be simply extended to other polymer composites for the development of new multifunctional and wearable electronic devices.
Water splitting is one of the ideal technologies to meet the ever increasing demands of energy. Many materials have aroused great attention in this field. The family of nickel-based sulfides is one ...of the examples that possesses interesting properties in water-splitting fields. In this paper, a controllable and simple strategy to synthesize nickel sulfides was proposed. First, we fabricated NiS2 hollow microspheres via a hydrothermal process. After a precise heat control in a specific atmosphere, NiS porous hollow microspheres were prepared. NiS2 was applied in hydrogen evolution reaction (HER) and shows a marvelous performance both in acid medium (an overpotential of 174 mV to achieve a current density of 10 mA/cm2 and the Tafel slope is only 63 mV/dec) and in alkaline medium (an overpotential of 148 mV to afford a current density of 10 mA/cm2 and the Tafel slope is 79 mV/dec). NiS was used in oxygen evolution reaction (OER) showing a low overpotential of 320 mV to deliver a current density of 10 mA/cm2, which is meritorious. These results enlighten us to make an efficient water-splitting system, including NiS2 as HER catalyst in a cathode and NiS as OER catalyst in an anode. The system shows high activity and good stabilization. Specifically, it displays a stable current density of 10 mA/cm2 with the applying voltage of 1.58 V, which is a considerable electrolyzer for water splitting.
Over the last decades, the fabrication of 3D tissues has become commonplace in tissue engineering and regenerative medicine. However, conventional 3D biofabrication techniques such as scaffolding, ...microengineering, and fiber and cell sheet engineering are limited in their capacity to fabricate complex tissue constructs with the required precision and controllability that is needed to replicate biologically relevant tissues. To this end, 3D bioprinting offers great versatility to fabricate biomimetic, volumetric tissues that are structurally and functionally relevant. It enables precise control of the composition, spatial distribution, and architecture of resulting constructs facilitating the recapitulation of the delicate shapes and structures of targeted organs and tissues. This Review systematically covers the history of bioprinting and the most recent advances in instrumentation and methods. It then focuses on the requirements for bioinks and cells to achieve optimal fabrication of biomimetic constructs. Next, emerging evolutions and future directions of bioprinting are discussed, such as freeform, high‐resolution, multimaterial, and 4D bioprinting. Finally, the translational potential of bioprinting and bioprinted tissues of various categories are presented and the Review is concluded by exemplifying commercially available bioprinting platforms.
Recent advances in translating 3D bioprinting to the clinics are reviewed, including developments in bioprinting strategies, innovations in bioinks for bioprinting, advances in bioprinting of complex architectures, and the translational potential of bioprinted tissue‐like structures. Commercially available bioprinting platforms are briefly discussed toward the end.
N6‐methyladenosine (m6A) is a novel epitranscriptomic marker that contributes to regulating diverse biological processes through controlling messenger RNA metabolism. However, it is unknown if m6A ...RNA methylation affects uveal melanoma (UM) development. To address this question, we probed its function and molecular mechanism in UM. Initially, we demonstrated that global RNA m6A methylation levels were dramatically elevated in both UM cell lines and clinical specimens. Meanwhile, we found that METTL3, a main m6A regulatory enzyme, was significantly increased in UM cells and specimens. Subsequently, cycloleucine (Cyc) or METTL3 targeted small interfering RNA was used to block m6A methylation in UM cells. We found that Cyc or silencing METTL3 significantly suppressed UM cell proliferation and colony formation through cell cycle G1 arrest, as well as migration and invasion by functional analysis. On the other hand, overexpression of METTL3 had the opposite effects. Furthermore, bioinformatics and methylated RNA immunoprecipitation‐quantitative polymerase chain reaction identified c‐Met as a direct target of m6A methylation in UM cells. In addition, western blot analysis showed that Cyc or knockdown of METTL3 downregulated c‐Met, p‐Akt, and cell cycle‐related protein levels in UM cells. Taken together, our results demonstrate that METTL3‐mediated m6A RNA methylation modulates UM cell proliferation, migration, and invasion by targeting c‐Met. Such a modification acts as a critical oncogenic regulator in UM development.
METTL3‐mediated m6A RNA methylation promotes uveal melanoma cell proliferation, migration, and invasion by targeting c‐Met. Such modification acts as a critical oncogenic regulator in uveal melanoma development.
PDF
