To investigate the effects of anthropogenic activity, namely, land use change and reservoir construction, on particulate organiccarbon (POc) transport, we collected monthly water samples during September 2007 to Augu...
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To investigate the effects of anthropogenic activity, namely, land use change and reservoir construction, on particulate organiccarbon (POc) transport, we collected monthly water samples during September 2007 to August 2009 from the Longchuanjiang River to understand seasonal variations in the concentrations of organiccarbon species and their sources and the yield of organic and inorganiccarbon from the catchment in the Upper Yangtze basin. The contents of riverine POc, total organiccarbon and total suspended sediment (TSS) changed synchronously with water discharge, whereas the contents of dissolved organiccarbon had a small variation. The POcconcentration in the suspended sediment decreased non-linearly with increasing TSS concentration. Higher molar c/N ratio of particulate organic matter (average 77) revealed that POc was dominated by terrestrially derived organic matter in the high flows and urban wastewaters in the low flows. The TSS transported by this river was 2.7?x?105?t/yr in 2008. The specific fluxes of total organiccarbon and dissolved inorganiccarbon (DIc) were 5.6 and 6?t/km2/yr, respectively, with more than 90% in the high flow period. A high carbon yield in the catchment of the upper Yangtze was due to human-induced land use alterations and urban wastes. consistent with most rivers in the monsoon climate regions, the dissolved organiccarbonPOc ratio of the export flux was low (0.41). Twenty-two percent (0.9?t/km2/yr) of POc out of 4?t/km2/yr was from autochthonous production and 78% (3.1?t/km2/yr) from allochthonous production. The annual sediment load and hence the organiccarbon flux have been affected by environmental alterations of physical, chemical and hydrological conditions in the past 50?years, demonstrating the impacts of human disturbances on the global and local carbon cycling. Finally, we addressed that organiccarbon flux should be reassessed using adequate samples (i.e. at least two times in low-flow month, four times in high
First-principles calculations based on density functional theory was performed to analyse the structural stability of transition metal carbides TMc (TM=Ru, Rh, Pd, Os, Ir, Pt). It is observed that zinc-blende phase is...
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First-principles calculations based on density functional theory was performed to analyse the structural stability of transition metal carbides TMc (TM=Ru, Rh, Pd, Os, Ir, Pt). It is observed that zinc-blende phase is the most stable one for these carbides. Pressure-induced structural phase transition from zinc blende to NiAs phase is predicted at the pressures of 248.5 GPa, 127 GPa and 142 GPa for Osc, Irc and Ptc, respectively. The electronic structure reveals that Ruc exhibits a semiconducting behaviour with an energy gap of 0.7056eV. The high bulk modulus values of these carbides indicate that these metal carbides are super hard materials. The high B/G value predicts that the carbides are ductile in their most stable phase.
The authors report a facile approach to high-purity carbon nanofibres (cNFs), by performing chemical vapour deposition on aluminium foils loaded with metal (nickel or cobalt) nitrates, and then peeling the as-grown cN...
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The authors report a facile approach to high-purity carbon nanofibres (cNFs), by performing chemical vapour deposition on aluminium foils loaded with metal (nickel or cobalt) nitrates, and then peeling the as-grown cNFs off. The growth of cNFs was catalysed by metal nanoparticles and followed bottom-growth mechanism, and the high-purity cNFs were achieved due to detachment of cNFs from their underlying metal nanoparticles during the peeling process. This approach may pave a new way for the controlled and scalable synthesis of high-purity carbon materials.
The performance of electrochemical capacitors containing different commercial carbon fibers is reviewed. High specificcapacitance (ca. 300 F/g) is obtained with low surface area carbon fiber (< 1 m(2)/g) using a p...
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The performance of electrochemical capacitors containing different commercial carbon fibers is reviewed. High specificcapacitance (ca. 300 F/g) is obtained with low surface area carbon fiber (< 1 m(2)/g) using a proprietary activation process. capacitance is primarily achieved through pseudocapacitance resulting from surface functional groups. The performance of these devices is dependent on the type of carbon fiber, its carbon content, aspect ratio and microstructure. These devices can achieve high cycle life (ca. 100k) without significant loss in capacitance.
A terahertz (THz) modulator based on graphene is proposed and analysed by use of equivalent transmission line of a homogeneous medium and the local anisotropic model of the graphene conductivity. The result calculated...
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A terahertz (THz) modulator based on graphene is proposed and analysed by use of equivalent transmission line of a homogeneous medium and the local anisotropic model of the graphene conductivity. The result calculated by the equivalent circuit is consistent with that obtained by Fresnel transfer matrices. For the modulator proposed here, when the frequency of carrier wave is 0.6 THz, the theoretical analysis indicates that the modulation bandwidth is 55.5 kHz and the modulation depth is 81.3% for voltage change from 0 to 50 V.
Utilising a biological material, a novel cNT nanostructure conjugated by semiconductor nanoparticles (NPs) was synthesised intended for electronics devices with unprecedented properties. A peptide aptamer that has an ...
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Utilising a biological material, a novel cNT nanostructure conjugated by semiconductor nanoparticles (NPs) was synthesised intended for electronics devices with unprecedented properties. A peptide aptamer that has an affinity for carbonaceous materials was fused to a cage-shaped protein (LiDps) to be displayed on its outer surface. As a potential coulomb island, semiconductor NPs were synthesised within the cavity of engineered protein (NHBP-LiDps). By the affinity of the peptide aptamer, the NHBP-LiDps proteins accommodating semiconductor NPs were adhered to surround the cNTs with nanometre-scaled gaps defined by the thickness of the protein cage. Using a dielectrophoresis assembly, the random network of cNTs conjugated by the NHBP-LiDps with NP cores was formed between a pair of electrodes. Electroniccharacterisation was performed on the random network of cNTs conjugated with NPs. coulomb blockade was observed. When cNTs were dispatched between a pair of electrodes, ohmiccharacteristics were observed. Apparently, the direct contact between cNTs was avoided by the NHBP-LiDps proteins surrounding the cNTs. The results are the first steps towards revealing unique electronic properties of these cNT conjugates.
Light-induced generation of free electrons is of interest for a wide variety of vacuum electronic devices and systems. The properties of nanomaterials, stemming from their geometry and the strong manifestation of quan...
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Light-induced generation of free electrons is of interest for a wide variety of vacuum electronic devices and systems. The properties of nanomaterials, stemming from their geometry and the strong manifestation of quantum phenomena in them, have opened up new avenues for developing new cathodes and exploring and exploiting electron emission. This article presents the heat trap effect-efficient localized heating of carbon nanotube arrays using light, leading to electron emission through the thermionic mechanism. This process requires unexpectedly modest amounts of optical power-available from sources such as handheld lasers-and dramatically simplifies the electron emitter. Potential applications, including thermionic and thermoelectricconversion for solar-energy harvesting and simple electron-beam systems, are also highlighted.
As the outer surface of a nanoporous carbon is treated with 16-mercaptohexadecanoic acid, the carbon particles can form a stable suspension in water. When the water phase is compressed, the liquid infiltration behavio...
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As the outer surface of a nanoporous carbon is treated with 16-mercaptohexadecanoic acid, the carbon particles can form a stable suspension in water. When the water phase is compressed, the liquid infiltration behavior in the nanopores becomes significantly different from that of untreated material, suggesting that the inner surface is also modified. After the treatment, the infiltration pressure does not decrease. Therefore, the chain configurations at the inner and outer surfaces must be different, which explains the variations in infiltration pressure and volume.
High-spin organic molecular materials are recent subjects of active studies. In diradicals and radical pairs, the ground states are usually singlet due to the overlap of the orbitals containing the unpaired electrons....
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High-spin organic molecular materials are recent subjects of active studies. In diradicals and radical pairs, the ground states are usually singlet due to the overlap of the orbitals containing the unpaired electrons. When the singly occupied orbitals are orthogonal to each other, triplet states become ground states. Thanks to the promotion of our understanding of how to stabilize the triple relative to the singlet, a number of examples of purely organic assemblies of free radicals and oligo/polyradicals have been accumulated, in which more than two electron spins are aligned in parallel. Approaches toward high T-c and tunable organic molecule-based magnets are in steady progress.
A printable high-speed thin-film transistor (TFT) fabricated on a regular plastic transparency film is proposed. The carrier transport layer of the TFT is an ultrapure carbon nanotube (cNT) thin film of high density (...
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A printable high-speed thin-film transistor (TFT) fabricated on a regular plastic transparency film is proposed. The carrier transport layer of the TFT is an ultrapure carbon nanotube (cNT) thin film of high density (> 1000 cNTs per mu m(2)) formed at room temperature by dispensing a tiny droplet of an electronic-grade cNT solution, which does not contain any surfactant. This cNT TFT exhibited a high-modulation speed of 312 MHz and a large current-carrying capacity beyond 20 mA. A unique ink-jet printing compatible process demonstrated herein would enable mass production of large-area electroniccircuits on any virtually desired flexible substrate at low cost and high throughput.
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