Edge-Oriented Graphene on Carbon Nanofiber for High-Frequency Supercapacitors

High-frequency supercapacitors are being studied with the aim to replace the bulky electrolytic capacitors for current ripple filtering and other functions used in power systems. Here, 3 D edge-oriented graphene(EOG)was grown encircling carbon nanofiber(CNF) framework to form a highly conductive electrode with a large surface area. Such EOG/CNF electrodes were tested in aqueous and organic electrolytes for high-frequency supercapacitor development. For the aqueous and the organic cell, the characteristic frequency at-45° phase angle was found to be as high as 22 and 8.5 k Hz, respectively. At 120 Hz, the electrode capacitance density was 0.37 and 0.16 m F cm^(-2) for the two cells. In particular, the 3 V high-frequency organic cell was successfully tested as filtering capacitor used in AC/DC converter, suggesting the promisingpotential of this technology for compact power supply design and other applications.

PI3 kinase isoform p110δis more important than p110αin KIT signaling in hematopoietic cells

PI3 kinases are important for KIT signaling and KIT mutants mediated cell transformation.In order to know the difference of PI3 kinase isoforms p110αand p110δin the signaling of wild-type KIT and the often occurred KIT mutation D816V in hematopoietic malignancy mastocytosis,the predominant PI3 kinase isoform p110δin hematopoietic tissues was knocked out in hematopoietic cells.We found that loss of p110δexpression dramatically inhibits PI3 kinase activation mediated by both wild-type KIT and KIT/D816V.By over expression of p110αin p110δknock out cells,wild-type KIT mediated PI3 kinase activation was not changed while over expression of p110δincreased PI3 kinase activation.Similarly,in KIT/D816V expressing cells without p110δexpression,over expression of p110δbut not p110αrestored PI3 kinase activation.In agreement with the signaling results,cell proliferation,cell survival and cell cycle assay further showed that over expression of p110δbut not p110αin p110δknock out cells increases both wild-type KIT and KIT/D816V mediated cell survival and proliferation.These results suggested that p110δplays a more important role than p110αin KIT signaling and KIT mutant mediated cell transformation in hematopoietic cells.

Ultrathin Al2O3-coated reduced graphene oxide membrane for stable lithium metal anode

Lithium （Li） metal has been considered as the most attractive anode materials for Li-ion batteries （LIBs） due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase （SEI） and dendritic Li on the metal anode, however, hindered its practical application. Herein, to address the issues, a Li-free electrode with ultrathin Al2O3 coated on reduced graphene oxide （rGO） membrane that covers a Cu foil current collector was developed. The composite electrode exhibits excellent interfacial protection of lithium metal deposited between Cu foil and rGO electrochemically. Firstly, it affords good Li^＋ permeability from the electrolyte. Secondly, the ultrathin Al2O3 has sufficient mechanical strength to inhibit the penetration of Li dendrite. Li metal was observed uniformly deposited between rGO membrane and Cu collector, and stable cycle performance of Li plating/stripping with Coulombic efficiency of ~ 91.75% at the lOOth cycle is achieved in organic carbonate electrolyte without any additives.

3-D Edge-Oriented Electrocatalytic NiCo_(2)S_(4)Nanoflakes on Vertical Graphene for Li-S Batteries

Polysulfide shuttle effect,causing extremely low Coulombic efficiency and cycling stability,is one of the toughest challenges hindering the development of practical lithium sulfur batteries(LSBs).Introducing catalytic nanostructures to stabilize the otherwise soluble polysulfides and promote their conversion to solids has been proved to be an effective strategy in attacking this problem,but the heavy mass of catalysts often results in a low specific energy of the whole electrode.Herein,by designing and synthesizing a free-standing edge-oriented NiCo_(2)S_(4)/vertical graphene functionalized carbon nanofiber(NCS/EOG/CNF)thin film as a catalytic overlayer incorporated in the sulfur cathode,the polysulfide shuttle effect is largely alleviated,revealed by the enhanced electrochemical performance measurements and the catalytic function demonstration.Different from other reports,the NiCo_(2)S_(4)nanosheets synthesized here have a 3-D edge-oriented structure with fully exposed edges and easily accessible in-plane surfaces,thus providing a high density of active sites even with a small mass.The EOG/CNF scaffold further renders the high conductivity in the catalytic structure.Combined,this novel structure,with high sulfur loading and high sulfur fraction,leads to high-performance sulfur cathodes toward a practical LSB technology.