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Optical absorption and photoluminescence (PL) properties of colloidal TiO(2) nanotubes, produced by the alkali hydrothermal method, were studied at room temperature in the range 300-700 nm. Nanotubes having an internal diameter in the range 2.5-5 nm have very similar optical properties, in contrast to the expected behavior for quasi-1-D systems. This is explained by the complete thermal smearing of all 1-D effects, due to the large effective mass of charge carriers in TiO(2), resulting in an apparent 2-D behavior of TiO(2) nanotubes.

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We report on transport measurements of YBa 2Cu 3O (7-delta) single crystals with different oxygen contents in the geometry B, J ||ab (J perpendicularB). Our data show that the vortices become confined between the Cu-O planes below a well-defined temperature at which the effective size 2xi of the vortex core is approximately equal to the period of the Cu-O layers. This confinement strongly increases the vortex liquid freezing temperature. A new melting line is found separating a vortex liquid and a smectic phase, which shows an oscillatory field dependence reflecting differences between commensurate and incommensurate smectic states.

Nanomechanical shuttles transferring small groups of electrons or even individual electrons from one electrode to another offer a novel approach to the problem of controlled charge transport. Here, we report the fabrication of shuttle-junctions consisting of a 20 nm diameter gold nanoparticle embedded within the gap between two gold electrodes. The nanoparticle is attached to the electrodes through a monolayer of "flexible" organic molecules which play the role of "springs" so that when a sufficient voltage bias is applied, the nanoparticle starts to oscillate transferring electrons from one electrode to the other. Currentvoltage characteristics for the fabricated devices have been measured and compared with the results of our computer simulations.In 1998, a group of theoreticians 1 proposed a novel mechanism of charge transport in nanostructures based on mechanical shuttling of electrons. The basic element (see Fig. 1), which is called a shuttle-junction, consists of a metallic nanoparticle connected by flexible, "elastic" molecules to two nanoelectrodes. For low applied voltages where the nanoparticle is stationary the device is similar to a single-electron transistor (SET). 2 The vibrational process