Anomalous low temperature specific heat of He-3 inside nanotube bundles

Helium atoms and hydrogen molecules can be strongly bound inside interstitial channels within bundles of carbon nanotubes. An exploration of the low energy and low temperature properties of He-3 atoms is presented here. Recent study of the analogous He-4 system has shown that the effect of heterogeneity is to yield a density of states N(E) that is qualitatively different from the one-dimensional (1D) form of N(E) that would occur for an ideal set of identical channels. In particular, the functional form of N(E) is that of a 4D gas near the very lowest energies and a 2D gas at somewhat higher energies. Similar behavior is found here for He-3. The resulting thermodynamic behavior of this fermi system is computed, yielding an anomalous form of the heat capacity and its dependence on coverage.Comment: 11 pages, 6 figure

Los textos de enseñanza de las ciencias experimentales como promotores de competencias de pensamiento científico (cpc) en una nueva cultura docente

En este trabajo se presentan los aspectos epistemológicos y praxiológicos de un proyecto editorial para la enseñanza de la química, la física y la biología, estructurados y orientados sobre las directrices de la ciencia escolar basada en el modelo cognitivo de ciencia. Interesa especialmente, que el profesor de ciencias naturales, disponga de nuevos elementos teóricos y prácticos para fundamentar una posición epistemológica frente al conocimiento que se elabora en la escuela y que es transmitido en los libros de texto de ciencia. Su finalidad principal es posicionar en el estudiantado y en los docentes el interés por la noción de ciencia, ciudadanía y valores, promoviendo la idea de competencias de pensamiento científico y problematizando la retórica de los libros de texto

Quasi-one and two-dimensional transitions of gases adsorbed on nanotube bundles

Grand canonical Monte Carlo simulations have been performed to determine the adsorption behavior of Ar and Kr atoms on the exterior surface of a rope (bundle) consisting of many carbon nanotubes. The computed adsorption isotherms reveal phase transitions associated with the successive creation of quasi-one dimensional lines of atoms near and parallel to the intersection of two adjacent nanotubes.Comment: 12 pages, 6 figures, submitted to J. Chem. Phy