The enormous amount of basic research into carbon nanotubes has sparked interest in the potential applications of these novel materials. One promising use of carbon nanotubes is as fillers in a composite material to improve mechanical behaviour, electrical transport and thermal transport. For composite materials with high thermal conductivity, the thermal conductance across the nanotube-matrix interface is of particular interest. Here we use picosecond transient absorption to measure the interface thermal conductance (G) of carbon nanotubes suspended in surfactant micelles in water. Classical molecular dynamics simulations of heat transfer from a carbon nanotube to a model hydrocarbon liquid are in agreement with experiment. Our findings indicate that heat transport in a nanotube composite material will be limited by the exceptionally small interface thermal conductance (G approximately 12 MW m(-2) K(-1)) and that the thermal conductivity of the composite will be much lower than the value estimated from the intrinsic thermal conductivity of the nanotubes and their volume fraction.
Carbon nanotube transistors exhibiting high on-state conductance, carrier mobilities, and on−off ratios are achieved using polymer electrolytes as gate media. Nearly ideal gate efficiencies allow operation at very small voltages without the commonly observed problem of hysteresis in back-gated nanotube and nanowire transistors. By varying the electron donating and accepting ability of the chemical groups of the host polymer, unipolar p or n devices or ambipolar transistors that are stable at room temperature in air are also shown to be easily fabricated. With simple methods such as spin casting of polymer films, high-performance polymer electrolyte-gated nanotube transistors may provide useful components for and an alternative route to developing hybrid electronics.
Photoinduced conductivity changes in single-walled carbon nanotube transistors have been examined. Low-intensity ultraviolet light significantly reduces the p-channel conductance while simultaneously increasing the n-channel conductance. A combination of optical absorption and electron transport measurements reveals that these changes occur without variations in dopant concentrations. Possible sites of oxygen photodesorption and its implications on the observed electronic properties of nanotubes are considered.
Schistosomes are intravascular parasitic worms that cause the debilitating disease schistosomiasis. To better understand how these long-lived parasites may subvert host immune and hemostatic capabilities, we examine here the impact of adult Schistosoma mansoni worms on the human serum proteome. Normal human serum (150 μl) was incubated at 37°C for one hour either in the presence or absence of adult worms (~50 pairs). Thereafter parasites were removed, serum samples were labeled and their proteins resolved for comparative analysis by 2D-Differential in-Gel Electrophoresis (2D-DIGE). Several differences were noted between the two samples. Twenty protein spots were recovered and identified following trypsin digestion and mass spectroscopy. Strikingly, most of these (11/20) are associated with the complement system and include complement components C3, C4, factor B, complement factor H related protein 1 and clusterin. Western blot analysis confirms the impact of the worms on C3, C4 and factor B in serum. The data suggest that schistosomes engage complement but can rapidly degrade selected complement proteins which may help explain the worm’s refractoriness towards complement-mediated attack. Other serum proteins identified as being impinged upon by schistosomes are alpha 2 macroglobulin, alpha 1 anti-chymotrypsin, actin cytoplasmic 2, serum amyloid A-4, protein DDX26B, hemoglobin subunit B and serum albumin. While the molecular nature of the interaction between these proteins and schistosomes is not known, possible roles for some of them in hemostasis, immune evasion and in the host response to serum stress are suggested.
Photoinduced conductivity changes and effects of thermal annealing in carbon nanotube transistors have been examined. Low-intensity ultraviolet light significantly reduces the p-channel conductance while simultaneously increasing the n-channel conductance. A combination of optical absorption and electron transport measurements reveals that these changes occur without variations in dopant concentrations. Measurements with different metals reveal that UV induces oxygen desorption from the electrodes rather than from nanotubes. In Ti-nanotube contact where the Schottky barrier plays an important role, photodesorption of oxygen mainly occurs from the native oxide of Ti electrodes. Decrease in the p-channel conductance arises from the metal work function change which causes larger hole Schottky barrier. Non-Schottky Pd-contacted nanotube transistors do not show photodesorption effects with low intensity UV. Thermal annealing of nanotube transistors with Ti/Au electrodes also leads to the disappearance of the photodesorption effects. However, a noticeable p-doping is observed to upon air exposure after thermal annealing.
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