Lithium-storage properties of gallic acid-reduced graphene oxide and silicon-graphene composites

Graphene oxide (GO) was de-oxygenated using gallic acid under mild conditions to prepare reduced graphene oxide (RGO). The resultant RGO showed a lithium-ion storage capacity of 1280\ua0mA\ua0h\ua0g at a current density of 200\ua0mA\ua0g after 350 cycles when used as an anode for lithium ion batteries. The RGO was further used to stabilize silicon (Si) nanoparticles to prepare silicon-graphene composite electrode materials. Experimental results showed that a composite electrode prepared with a mass ratio of Si:GO\ua0=\ua01:2 exhibited the best lithium ion storage performance

Ideology in the Era of Xi Jinping

Publisher Copyright: © 2018, The Author(s).After 1978, Maoism as a living mass ideological and social force in the People’s Republic of China largely died away. The Party state’s legitimacy since that time has been based on a new pillar of economic competence and the delivery of tangible economic gains. But China is still a place where, at least within the political elite, there is an identifiable ideology and associated language that links the aims of a political force, the Communist Party of China, with national prosperity, historic rejuvenation, and the delivery of the political goals promised when the Communist Party was founded almost a century ago – modernity in Chinese society. Ideology has not disappeared in this interpretation. It has just become more concealed, more nuanced, and in some spaces more flexible. For Chinese contemporary leaders, ideology is partly a body of practices, beliefs, and language which have been bequeathed to them by previous leaders, and which show that they are part of the same historic movement that runs from 1921 to 1949, and through 1978 until today. This body of practices is aimed at maintaining a sustainable system of one party rule, as well as an assertion of discipline and control in the core tactical spaces of political power. Under Xi, a group of twelve keywords maps out the discursive space that matters to the CPC today. These terms exemplify the ways in which the contemporary CPC is willing to use ideas from diverse sources, either from its own past, or from classical Chinese thinking, as a means of achieving emotional as well as intellectual impact, and to assist in the delivery of the major Party goal of the twenty-first century – the creation of a great nation with the CPC at the heart of its governance. Underlying the keywords and the ideological space they define is the larger notion of the Party, not just attending to material but also spiritual needs – and creating not just a wealthy country, but also a spiritual socialist civilization.publishersversionPeer reviewe

Morphological diversity of single neurons in molecularly defined cell types.

Dendritic and axonal morphology reflects the input and output of neurons and is a defining feature of neuronal types1,2, yet our knowledge of its diversity remains limited. Here, to systematically examine complete single-neuron morphologies on a brain-wide scale, we established a pipeline encompassing sparse labelling, whole-brain imaging, reconstruction, registration and analysis. We fully reconstructed 1,741 neurons from cortex, claustrum, thalamus, striatum and other brain regions in mice. We identified 11 major projection neuron types with distinct morphological features and corresponding transcriptomic identities. Extensive projectional diversity was found within each of these major types, on the basis of which some types were clustered into more refined subtypes. This diversity follows a set of generalizable principles that govern long-range axonal projections at different levels, including molecular correspondence, divergent or convergent projection, axon termination pattern, regional specificity, topography, and individual cell variability. Although clear concordance with transcriptomic profiles is evident at the level of major projection type, fine-grained morphological diversity often does not readily correlate with transcriptomic subtypes derived from unsupervised clustering, highlighting the need for single-cell cross-modality studies. Overall, our study demonstrates the crucial need for quantitative description of complete single-cell anatomy in cell-type classification, as single-cell morphological diversity reveals a plethora of ways in which different cell types and their individual members may contribute to the configuration and function of their respective circuits

A comparative study of electrocapacitive properties of manganese dioxide clusters dispersed on different carbons

Manganese dioxide (MnO) clusters were directly grown on different carbons, including reduced graphene oxide (RGO), multi-wall carbon nanotubes (CNTs), and carbon black (Vulcan XC-72), via a chelation-mediated aqueous solution method. The electrocapacitive properties of the composite materials were evaluated by using cycle voltammetry, electrochemical impedance spectroscopy (EIS), and charge/discharge techniques. The composite electrode consisting of RGO and MnO performed the best among the composite electrodes studied with a specific capacitance as high as 260 F/g at a current density of 0.3 A/g. EIS data revealed the smallest charge transfer resistance in electrode. The results suggest that two-dimensional (2D) RGO sheets are an excellent support for pseudocapacitive MnO. This study provides fundamental insights into the role of a carbon support in carbon-transition- metal-oxide composite electrodes for supercapacitors

Synthesis and capacitive properties of manganese oxide nanosheets dispersed on functionalized graphene sheets

Functionalized graphene was prepared by reducing functionalized graphene oxide with poly(diallyldimethylammonium chloride) (PDDA), transferring the surface charge of reduced graphene oxide (RGO) from negative to positive. A composite material of functionalized RGO with manganese dioxide (MnO ) nanosheets can be obtained by dispersing negatively charged MnO nanosheets on the functionalized RGO sheets via an electrostatic coprecipitation method. The structures of composites were investigated by high-resolution transmission electron microscopy (HRTEM), which indicated that the MnO nanosheets dispersed on functionalized RGO sheets, exhibiting a layered structure. The composite material exhibited enhanced capacitive performances than those of pure functionalized RGO and Na-typed birnessite (Na/MnO) sheets, attributing to the synergic effect of both components. Additionally, over 89% of original capacitance was retained after 1000 cycles, indicating a good cycle stability of the composite materials

Graphene-metal-oxide composites for the degradation of dyes under visible light irradiation

Reduced graphene oxide (RGO) was respectively modified with tin dioxide (SnO) and titanium dioxide (TiO) via a direct redox reaction between the graphene oxide (GO) and the reactive cations Sn and Ti, forming RGO-SnO and RGO-TiO composites. During this redox reaction, GO was reduced to RGO while Sn and Ti were oxidized to SnO and TiO, depositing on the surface of the RGO. The composite materials were found to exhibit very interesting photocatalytic properties for degrading Rhodamine B under visible light irradiation. First, their photocatalytic activities were higher than that of P25 (a commercial TiO as a benchmark photocatalyst). Second, the reaction mechanism catalyzed by the composite materials was different from that of semiconductor photocatalysis. Characterization data showed that the excellent photocatalytic performance of the composite materials was associated with the good electrical conductivity and effective charge separation because of the presence of RGO. The present work opens up a new avenue to preparing RGO-based composite materials and provides new insights into the photocatalytic degradation of dyes under visible light irradiation

Ultrathin MnO2 nanofibers grown on graphitic carbon spheres as high-performance asymmetric supercapacitor electrodes

Growing MnO nanofibers on graphitic hollow carbon spheres (GHCS) is conducted by refluxing GHCS in a KMnO aqueous solution aimed to enhance the electrochemically active surface area of MnO. The stoichiometric redox reaction between GHCS and MnO yields GHCS-MnO composites with controllable MnO content. It is found that these ultrathin MnO nanofibers are vertically grown on the external surface of the GHCS, yielding a composite electrode showing good electron transport, rapid ion penetration, fast and reversible Faradic reaction, and excellent rate performance when used as supercapacitor electrode materials. An asymmetric supercapacitor cell with GHCS-MnO as the positive electrode and GHCS as the negative electrode can be reversibly charged/discharged at a cell voltage of 2.0 V in a 1.0 mol L NaSO aqueous electrolyte, delivering an energy density of 22.1 Wh kg and a power density of 7.0 kW kg. The asymmetric supercapacitor exhibits an excellent electrochemical cycling stability with 99% initial capacitance and 90% coulombic efficiency remained after 1000 continuous cycles measured using the galvanostatic charge-discharge technique

A high-performance asymmetric supercapacitor fabricated with graphene-based electrodes

An asymmetric supercapacitor (ASC) was fabricated using reduced graphene oxide (RGO) sheets modified with ruthenium oxide (RGO-RuO ) or polyaniline (RGO-PANi) as the anode and cathode, respectively. The ASC exhibited a significantly improved capacitive performance in comparison with that of the symmetric supercapacitors fabricated with RGO-RuO or RGO-PANi as the electrodes. The improvement was attributed to the broadened potential window in an aqueous electrolyte, leading to an energy density of 26.3 W h kg , about two-times higher than that of the symmetrical supercapacitors based on RGO-RuO (12.4 W h kg ) and RGO-PANi (13.9 W h kg ) electrodes. In addition, a power density of 49.8 kW kg was obtained at an energy density of 6.8 W h kg