Wet acid oxidation treatment methods have been widely reported as an effective method to purify and oxidize the surface of industrial multi-walled carbon nanotubes (MWCNT). This work examines the use of a concentrated HNO3/H2SO4 mixture in an attempt to optimize the purification procedure of industrial MWCNT with diameter distribution statistics. It is shown that acid treatments of several hours are enough to purify the nanotubes. The electrical and thermal conductivities of epoxy composites containing 0.05-0.25 wt. % of acid-treated MWCNT has been studied. The electrical conductivity of the composites decreases by more than three orders, whereas the thermal conductivity of the same specimen increases very modestly as a function of the filler content.

Photo-active pi-conjugated molecules (quaterthiophene and phthalocyanine) are either encapsulated into the hollow core of single-walled carbon nanotubes or non-covalently stacked at their outer surface in order to elaborate hybrid nano-systems with new physical properties, providing practical routes to fit different requirements for potential applications. In this study, we are interested in the relationship between the structure and the opto-electronic properties. The structural properties are investigated mainly by x-ray diffraction and/or Transmission Electron Microscopy and Raman spectroscopy. We evidence that the supramolecular organizations of confined quaterthiophenes depend on the nanocontainer size whereas phthalocyanine encapsulation leads the formation of a 1D-phase for which the angle between the molecule ring and the nanotube axis is close to 32°. Confined phthalocyanine molecules display Raman spectra hardly altered with respect to the bulk phase, suggesting a rather weak interaction with the tubes. In contrast, the vibrational properties of the molecules stacked at the outer surface of tubes display important modifications. We assume a significant curvature of the phthalocyanine induced by the interaction with the tube walls and a change of the central atom position within the molecular ring, in good agreement with our DFT calculations.

Biological nano-channels expressed in living cells, where they ensure keyphysiological functions, feature outstanding efficiency in terms of both ionselectivity and conductivity. The latter generally exceeds, by 3 to 4 orderof magnitude, the values expected from classical hydrodynamics. This propertyof biological nano-channels may result from their pore width in the rangeof the Debye length (0.3-30 nm) and this currently grounds many researchworks aimed at developing the use of solid-state porous nano-materials for‘‘high-throughput’’ molecular and ion sensing or sorting, with applicationssuch as drug delivery, energy conversion, water desalination and others. Singlewalled carbon nanotubes (SWNTs), which make nano-pores with welldefinedstructural and physical properties, may allow us to overcomingmany limitations of other nano-materials. The possibility of transportingions and molecules through these SWNTs has already been reported by othergroups (Lee et al., 2010, Science 329:1320; Liu et al., 2010, Science 327:64).In this context, we aim at studying the usableness of SWNT-incorporating devicesfor discriminating ions and single small biomolecules, using nucleotidesand amino acids as model compounds. Here, we will present the first part ofthis work, which consists in the fabrication of microfluidic devices incorporatingindividual SWNTs and the study of ion transport inside these devicesusing ionic current measurements, i.e. patch-clamp type. A study of the selectivityof these SWNTs will be also shown using different cations-basedelectrolytes.

We studied the oxygen etching of individual single-walled carbon nanotubes on silicon oxide substrates using atomic force microscopy and high-temperature environmental scanning electron microscopy. Our in situ observations show that carbon nanotubes are not progressively etched from their ends, as frequently assumed, but disappear segment by segment. Atomic force microscopy, before and after oxidation, reveals that the oxidation of carbon nanotubes on substrates proceeds through a local cutting that is followed by a rapid etching of the disconnected nanotube segment. Unexpectedly, semiconducting nanotubes appear more reactive under these conditions than metallic ones. We also show that exposure to electron and laser beams locally increases the chemical reactivity of carbon nanotubes on such substrates. These results are rationalized by considering the effect of substrate-trapped charges on the nanotube density of states close to the Fermi level, which is impacted by the substrate type and the exposure to electron and laser beams.

Nuclear magnetic resonance imaging (NMRI) is a powerful tool for biological investigations. Nevertheless, the imaging resolution performance results in the combination of the magnetic field (B0) and the antenna efficiency. This latter one results in a compromise between the size of the sample, the location of the region of interest and the homogeneity requirement. In the context of spinal cord imaging on mice, a ribbon solenoid coil is used to enhance the efficiency of the MRI experiment. This paper details the calculation of the local magnetization contribution to the induced voltage of MRI coils. The modeling is illustrated on ribbon solenoid antennas used in emitter–receiver mode for the study. The analytical model, which takes into account the emitting mode, the receiving step and the imaging sequence, is compared to the measurement performed on a 9.4 T VARIAN MRI apparatus. The efficiency of the antenna, in terms of signal to noise ratio, is significantly enhanced with respect to a commercial quadrature volumic antenna, given a significant advantage for the study of spinal cord injuries.