Paste electrodes have been constructed using single-wall carbon nanotubes mixed with mineral oil. The electrochemical behavior of such electrodes prepared with different percentages of carbon nanotubes has been compared with that of graphite paste electrodes and evaluated with respect to the electrochemistry of ferricyanide with cyclic voltammetry. Carbon nanotubes were purified by a treatment with concentrated nitric acid, then oxidized in air. In addition, electrochemical pretreatments were carried out to increase the selectivity of carbon nanotube electrodes. Performances of carbon nanotube paste and carbon paste electrodes were evaluated by studying such parameters as current peak, deltaEp, anodic and cathodic current ratio, and charge density toward several different electroactive molecules. Data interpretation based on the carbon nanotubes and carbon surface area is presented. Carbon nanotube paste and carbon paste electrodes were tested as H2O2 and NADH probes, and several analytical parameters were evaluated. The oxidative behavior of dopamine was examined at these electrodes. The two-electron oxidation of dopamine to dopaminequinone showed an excellent reversibility in cyclic voltammetry that was significantly better than that observed at carbon paste electrodes.

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The observed alpha decay half-life values of favoured alpha transitions of ℓ = 5 in bismuth isotopes have been analysed in the framework of a model based on quantum mechanical tunnelling through a potential barrier where the centrifugal and overlapping effects are taken into account. In particular, the very recently measured alpha decay half-life value of (1.9 ± 0.2) × 1019 y for the unique naturally occurring 209Bi isotope has been reproduced by the present approach as (1.0 ± 0.3) × 1019 y. Also, the partial alpha decay half-lives for a number of unmeasured alpha transitions of ℓ = 5 in bismuth isotopes are predicted by the model, thus making it possible to demonstrate the influence of the 126 neutron shell closure on the alpha decay half-life. The present approach is shown to be successfully applicable to other isotopic sequences of alpha-emitter nuclides.

Polymeric thin films have been awakening continuous and growing interest for application in nanotechnology. For such applications, the assessment of their (nano)mechanical properties is a key issue, since they may dramatically vary between the bulk and the thin film state, even for the same polymer. Therefore, techniques are required for the in situ characterization of mechanical properties of thin films that must be nondestructive or only minimally destructive. Also, they must also be able to probe nanometer-thick ultrathin films and layers and capable of imaging the mechanical properties of the sample with nanometer lateral resolution, since, for instance, at these scales blends or copolymers are not uniform, their phases being separated. Atomic force microscopy (AFM) has been proposed as a tool for the development of a number of techniques that match such requirements. In this review, we describe the state of the art of the main AFM-based methods for qualitative and quantitative single-point measurements and imaging of mechanical properties of polymeric thin films, illustrating their specific merits and limitations.

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We have investigated the electronic states of highly oriented pyrolitic graphite and single-walled carbon nanotubes using x-ray absorption spectroscopy (XAS) before and after annealing treatment in ultrahigh vacuum, and observed that the small peak between π* and σ* features, which has been previously assigned to free-electron-like interlayer states, disappears after in situ annealing treatment, suggesting that the signal may be assigned to a surface contamination, especially oxygen contamination introduced by chemical processing or gas adsorption. Additional experiments by photoelectron spectroscopy as well as XAS methods, performed after aging in air, fully support this interpretation.

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