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Aji A Anappara, Julin Joseph
Here we report single-step synthesis of white-light emitting carbon dots (CDs) through a green, facile and cheap electrochemical route using graphite rods as the carbon source. Under UV-excitation, the aqueous dispersion of as-synthesized CDs exhibited broad-band emission which covers a significant fraction of visible spectrum; owing to the heterogeneity in the particle-size and surface-functional groups. The CDs were further explored for their potential as UV-to-visible color-convertor under remote-phosphor technology by capping a 365 nm UV-LED chip with CDs-loaded PMMA to obtain color parameters: CIE (0...
December 7, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Li Song, Tao Wang, Yiou Ma, Hairong Xue, Hu Guo, Xiaoli Fan, Wei Xia, Hao Gong, Jianping He
The scarcity, high cost and poor stability of precious metal-based electrocatalysts have stimulated the development of novel non-precious metal catalysts to oxygen reduction reaction (ORR) for the use in fuel cells and metal-air batteries. Here, we in-situ fabricated a hybrid material (Co-W-C/N) with functional species (tungsten carbide and cobalt nanoparticles) encapsulated in N-doped porous carbon framework, through a facile multi-constituents co-assembly method combined with subsequent annealing treatment...
December 7, 2016: Chemistry: a European Journal
Hidetaka Ishihara, Yen-Chang Chen, Nicholas De Marco, Oliver Lin, Chih-Meng Huang, Vipawee Limsakoune, Yi-Chia Chou, Yang Yang, Vincent Tung
The tantalizing prospect of harnessing the unique properties of graphene crumpled nanostructures continues to fuel tremendous interest in energy storage and harvesting applications. However, the paper ball-like, hard texture, and closed-sphere morphology of current 3D graphitic nanostructure production not only constricts the conductive pathways but also limits the accessible surface area. Here, we report new insights into electrohydrodynamically-generated droplets as colloidal nanoreactors in that the stimuli-responsive nature of reduced graphene oxide can lead to the formation of crumpled nanostructures with a combination of open structures and doubly curved, saddle-shaped edges...
December 7, 2016: Scientific Reports
Thi Mien Trung Huynh, Thanh Hai Phan, Oleksandr Ivasenko, Stijn F L Mertens, Steven De Feyter
Highly oriented pyrolytic graphite (HOPG) can be covalently grafted with aryl radicals generated via the electrochemical reduction of 3,5-bis-tert-butyl-diazonium cations (3,5-TBD). The structure of the grafted layer and its stability under electrochemical conditions were assessed with electrochemical scanning tunneling microscopy (EC-STM) and cyclic voltammetry (CV). Stable within a wide (>2.5 V) electrochemical window, the grafted species can be locally removed using EC-STM-tip nanolithography. Using dibenzyl viologen as an example, we show that the generated nanocorrals of bare graphitic surface can be used to study nucleation and growth of self-assembled structures under conditions of nanoconfinement and electrochemical potential control...
December 7, 2016: Nanoscale
A Six, A Bocheux, F Charra, F Mathevet, D Kreher, A-J Attias
Here we report the synthesis and characterization of a series of new phenylene-vinylene tectons. The study by scanning tunneling microscopy of their supramolecular self-assembly at the interface between a phenyloctane solution and highly oriented pyrolytic graphite  demonstrates that variation of concentration and length of alkyl chains led to the formation of different networks, a compact one and a nanoporous one, with a fine control of the lattice parameters. The study of guest-host properties of the nanoporous network revealed a selectivity toward guest compounds according to their shape and size...
December 6, 2016: Nanotechnology
Jinhua Yao, Huan Chen, Fang Jiang, Zhongyi Jiao, Mingchang Jin
In this work, TiO2-CdS-gCNNSs heterojunction photocatalysts were successfully synthesized. CdS was deposited on the surface of gCNNSs via electrostatic attraction; TiOC, TiOCO and TiON bonds were produced in TiO2-CdS-gCNNSs, strengthening the interaction between TiO2 and gCNNSs. The TiO2-CdS-gCNNSs photocatalyst showed excellent photocatalytic activity for phenol degradation under visible-light irradiation, which was higher than that of CdS-gCNNSs, CdS-TiO2 and TiO2-gCNNSs. The improved photocatalytic performance of TiO2-CdS-gCNNSs was ascribed to more adsorption sites, enhanced light harvesting ability and effective separation rate of electron-hole pairs...
November 15, 2016: Journal of Colloid and Interface Science
Stephanie C Kosnik, Justin F Binder, Maxemilian C Nascimento, Charles L B Macdonald
We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable low-valent-phosphorus-containing compound acts as a useful P(+) transfer agent. Unlike traditional methods employed to access low-coordinate phosphorus species which usually require pyrophoric phosphorus-containing precursors (white phosphorus, Tris(trimethylsilyl)phosphine, etc.), or harsh reducing agents (alkali metals, potassium graphite, etc.), the current approach does not involve pyrophoric or explosive reagents and can be done on large scales (>20 g) in excellent yields by undergraduates with basic air-free synthetic training...
November 22, 2016: Journal of Visualized Experiments: JoVE
Jinyang Dong, Yanming Xue, Chao Zhang, Qunhong Weng, Pengcheng Dai, Yijun Yang, Min Zhou, Cuiling Li, Qiuhong Cui, Xiaohong Kang, Chengchun Tang, Yoshio Bando, Dmitri Golberg, Xi Wang
A novel carbon structure, highly branched homogeneous-N-doped graphitic (BNG) tubular foam, is designed via a novel N, N-dimethylformamide (DMF)-mediated chemical vapor deposition method. More structural defects are found at the branched portions as compared with the flat tube domains providing abundant active sites and spacious reservoirs for Li(+) storage. An individual BNG branch nanobattery is constructed and tested using in situ transmission electron microscopy and the lithiation process is directly visualized in real time...
December 2, 2016: Advanced Materials
G A Wurden, L A Stephey, C Biedermann, M W Jakubowski, J P Dunn, M Gamradt
A high-resolution imaging system, consisting of megapixel mid-IR and visible cameras along the same line of sight, has been prepared for the new W7-X stellarator and was operated during Operational Period 1.1 to view one of the five inboard graphite limiters. The radial line of sight, through a large diameter (184 mm clear aperture) uncoated sapphire window, couples a direct viewing 1344 × 784 pixel FLIR SC8303HD camera. A germanium beam-splitter sends visible light to a 1024 × 1024 pixel Allied Vision Technologies Prosilica GX1050 color camera...
November 2016: Review of Scientific Instruments
L B Fletcher, U Zastrau, E Galtier, E J Gamboa, S Goede, W Schumaker, A Ravasio, M Gauthier, M J MacDonald, Z Chen, E Granados, H J Lee, A Fry, J B Kim, C Roedel, R Mishra, A Pelka, D Kraus, B Barbrel, T Döppner, S H Glenzer
We present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5...
November 2016: Review of Scientific Instruments
Colin Harthcock, Abdolreza Jahanbekam, Jeremy R Eskelsen, David Y Lee
We describe an example of a piecewise gas chamber that can be customized to incorporate a low flux of gas-phase radicals with an existing surface analysis chamber for in situ and stepwise gas-surface interaction experiments without any constraint in orientation. The piecewise nature of this gas chamber provides complete angular freedom and easy alignment and does not require any modification of the existing surface analysis chamber. In addition, the entire gas-surface system is readily differentially pumped with the surface chamber kept under ultra-high-vacuum during the gas-surface measurements...
November 2016: Review of Scientific Instruments
F Bedoya, J P Allain, R Kaita, C H Skinner, L Buzi, B E Koel
A novel Plasma Facing Components (PFCs) diagnostic, the Materials Analysis Particle Probe (MAPP), has been recently commissioned in the National Spherical Torus Experiment Upgrade (NSTX-U). MAPP is currently monitoring the chemical evolution of the PFCs in the NSTX-U lower divertor at 107 cm from the tokamak axis on a day-to-day basis. In this work, we summarize the methodology that was adopted to obtain qualitative and quantitative descriptions of the samples chemistry. Using this methodology, we were able to describe all the features in all our spectra to within a standard deviation of ±0...
November 2016: Review of Scientific Instruments
Fuming Li, Zhipeng Chen, Ge Zhuang, Hai Liu, Lizhi Zhu
The fast reciprocating magnetic probe (FRMP) system is newly developed on the Joint Texas Experimental Tokamak (J-TEXT) to measure the local magnetic fluctuations at the plasma edge. The magnetic probe array in the FRMP consists of four 2-dimensional magnetic probes arranged at different radial locations to detect local poloidal and radial magnetic fields. These probes are protected by a graphite and boron nitride casing to improve the frequency response of each probe; they are mounted on the head of a movable rod, which is oriented along radial direction at the top of the torus...
November 2016: Review of Scientific Instruments
M Krychowiak, A Adnan, A Alonso, T Andreeva, J Baldzuhn, T Barbui, M Beurskens, W Biel, C Biedermann, B D Blackwell, H S Bosch, S Bozhenkov, R Brakel, T Bräuer, B Brotas de Carvalho, R Burhenn, B Buttenschön, A Cappa, G Cseh, A Czarnecka, A Dinklage, P Drews, A Dzikowicka, F Effenberg, M Endler, V Erckmann, T Estrada, O Ford, T Fornal, H Frerichs, G Fuchert, J Geiger, O Grulke, J H Harris, H J Hartfuß, D Hartmann, D Hathiramani, M Hirsch, U Höfel, S Jabłoński, M W Jakubowski, J Kaczmarczyk, T Klinger, S Klose, J Knauer, G Kocsis, R König, P Kornejew, A Krämer-Flecken, N Krawczyk, T Kremeyer, I Książek, M Kubkowska, A Langenberg, H P Laqua, M Laux, S Lazerson, Y Liang, S C Liu, A Lorenz, A O Marchuk, S Marsen, V Moncada, D Naujoks, H Neilson, O Neubauer, U Neuner, H Niemann, J W Oosterbeek, M Otte, N Pablant, E Pasch, T Sunn Pedersen, F Pisano, K Rahbarnia, L Ryć, O Schmitz, S Schmuck, W Schneider, T Schröder, H Schuhmacher, B Schweer, B Standley, T Stange, L Stephey, J Svensson, T Szabolics, T Szepesi, H Thomsen, J-M Travere, H Trimino Mora, H Tsuchiya, G M Weir, U Wenzel, A Werner, B Wiegel, T Windisch, R Wolf, G A Wurden, D Zhang, A Zimbal, S Zoletnik
Wendelstein 7-X, a superconducting optimized stellarator built in Greifswald/Germany, started its first plasmas with the last closed flux surface (LCFS) defined by 5 uncooled graphite limiters in December 2015. At the end of the 10 weeks long experimental campaign (OP1.1) more than 20 independent diagnostic systems were in operation, allowing detailed studies of many interesting plasma phenomena. For example, fast neutral gas manometers supported by video cameras (including one fast-frame camera with frame rates of tens of kHz) as well as visible cameras with different interference filters, with field of views covering all ten half-modules of the stellarator, discovered a MARFE-like radiation zone on the inboard side of machine module 4...
November 2016: Review of Scientific Instruments
T Döppner, D Kraus, P Neumayer, B Bachmann, J Emig, R W Falcone, L B Fletcher, M Hardy, D H Kalantar, A L Kritcher, O L Landen, T Ma, A M Saunders, R D Wood
We are developing x-ray Thomson scattering for applications in implosion experiments at the National Ignition Facility. In particular we have designed and fielded MACS, a high-efficiency, gated x-ray spectrometer at 7.5-10 keV [T. Döppner et al., Rev. Sci. Instrum. 85, 11D617 (2014)]. Here we report on two new Bragg crystals based on Highly Oriented Pyrolytic Graphite (HOPG), a flat crystal and a dual-section cylindrically curved crystal. We have performed in situ calibration measurements using a brass foil target, and we used the flat HOPG crystal to measure Mo K-shell emission at 18 keV in 2nd order diffraction...
November 2016: Review of Scientific Instruments
Guillemette Crépeaux, Housam Eidi, Marie-Odile David, Yasmine Baba-Amer, Eleni Tzavara, Bruno Giros, François-Jérôme Authier, Christopher Exley, Christopher A Shaw, Josette Cadusseau, Romain K Gherardi
Aluminium (Al) oxyhydroxide (Alhydrogel(®)), the main adjuvant licensed for human and animal vaccines, consists of primary nanoparticles that spontaneously agglomerate. Concerns about its safety emerged following recognition of its unexpectedly long-lasting biopersistence within immune cells in some individuals, and reports of chronic fatigue syndrome, cognitive dysfunction, myalgia, dysautonomia and autoimmune/inflammatory features temporally linked to multiple Al-containing vaccine administrations. Mouse experiments have documented its capture and slow transportation by monocyte-lineage cells from the injected muscle to lymphoid organs and eventually the brain...
November 28, 2016: Toxicology
Bao Zha, Meiqiu Dong, Xinrui Miao, Shan Peng, Yican Wu, Kai Miao, Yi Hu, Wenli Deng
Herein, the photophysical properties of two π-conjugated thienophenanthrene derivatives (6,9- and 5,10-DBTD) are reported. Their self-assembled monolayers in aliphatic hydrocarbon solvents under different concentrations were investigated by scanning tunneling microscopy on a graphite surface. The STM results revealed that the self-assembled structures of the two geometrical isomers exhibited absolutely different behaviors. At the aliphatic solvent/graphite interface, 6,9-DBTD produced almost a single stable coassembled linear structure, except for that with n-tridecane as the solvent...
December 1, 2016: Nanoscale
Xiaoli Hu, Nicholas Chan, Ashlie Martini, Philip Egberts
Amplitude modulated atomic force microscopy (AM-AFM) was used to examine the influence of the size of the AFM tip apex on the measured surface topography of single highly oriented pyrolytic graphite (HOPG) atomic steps. Experimental measurements were complemented by molecular dynamics simulations of AM-AFM and the results from both were evaluated by comparison of the measured or simulated width of the topography at the step to that predicted using simple rigid-body geometry. The results showed that the step width, which is a reflection of the resolution of the measurement, increased with tip size, as expected, but also that the difference between the measured/simulated step width and the geometric calculation was tip size dependent...
December 1, 2016: Nanotechnology
K Vasanth Kumar, Srinivas Gadipelli, Kathrin Preuss, Harshit Porwal, Tingting Zhao, Zheng Xiao Guo, Maria-Magdalena Titirici
We propose a new synthetic route towards nanoporous functional carbon materials based on salt templating with pore-padding approach (STPP). STPP relies on the use of a pore-padding agent that undergoes an initial polymerisation/ condensation process prior to the formation of a solid carbon framework. The pore-padding agent allows tailoring hierarchically the pore-size distribution and controlling the amount of heteroatom (nitrogen in this case) functionalities as well as the type of nitrogen (graphitic, pyridinic, oxides of nitrogen) incorporated within the carbon framework in a single-step-process...
November 30, 2016: ChemSusChem
Parakandy Muzhikara Pratheeksha, Erabhoina Hari Mohan, Bulusu Venkata Sarada, Mantripragada Ramakrishna, Kalyan Hembram, Pulakhandam Veera Venkata Srinivas, Paul Joseph Daniel, Tata Narasinga Rao, Srinivasan Anandan
In the present study, LiFePO4 (LFP) has been synthesized using a flame spray pyrolysis unit followed by carbon coating on LFP using a novel strategy of dehydration assisted polymerization process (DAP) in order to improve its electronic conductivity. Characterization studies revealed the presence of a pure LFP structure and the formation of a thin, uniform and graphitic carbon layer with a thickness of 6-8 nm on the surface of the LFP. A carbon coated LFP with 3 wt% of carbon, using a DAP process, delivered a specific capacity of 167 mA h g(-1) at a 0...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
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