Free-energy coarse-grained potential for C60.

We propose a new deformable free energy method for generating a free-energy coarse-graining potential for C60. Potentials generated from this approach exhibit a strong temperature dependence and produce excellent agreement with benchmark fully atomistic molecular dynamics simulations. Parameter sets for analytical fits to this potential are provided at four different temperatures.

A first principles based polarizable O(N) interatomic force field for bulk silica.

We present a reformulation of the Tangney-Scandolo interatomic force field for silica [J. Chem. Phys. 117, 8898 (2002)], which removes the requirement to perform an Ewald summation. We use a Yukawa factor to screen electrostatic interactions and a cutoff distance to limit the interatomic potential range to around 10 Å. A reparametrization of the potential is carried out, fitting to data from density functional theory calculations. These calculations were performed within the local density approximation since we find that this choice of functional leads to a better match to the experimental structural and elastic properties of quartz and amorphous silica than the generalized gradient approximation approach used to parametrize the original Tangney-Scandolo force field. The resulting O(N) scheme makes it possible to model hundreds of thousands of atoms with modest computational resources, without compromising the force field accuracy. The new potential is validated by calculating structural, elastic, vibrational, and thermodynamic properties of α-quartz and amorphous silica.

Temperature dependence of the optical transition energies of carbon nanotubes: the role of electron-phonon coupling and thermal expansion.

Tunable Raman spectroscopy is used to measure the optical transition energies Eii of individual single wall carbon nanotubes. Eii is observed to shift down in energy by as much as 50 meV, from -160 to 300 degrees C, in contrast with previous measurements performed on nanotubes in alternate environments, which show upshifts and downshifts in Eii with temperature. We determine that electron-phonon coupling explains our experimental observations of nanotubes suspended in air, neglecting thermal expansion. In contrast, for nanotubes in surfactant or in bundles, thermal expansion of the nanotubes' environment exerts a nonisotropic pressure on the nanotube that dominates over the effect of electron-phonon coupling.

Nutrition and lifestyle survey of 15-17 year old second level school pupils in the Cork city area.

This study deals with the dietary intakes of a representative sample of Cork city area, school-going children, aged 15-17 years (n=125). Dietary intake was assessed by diet history with published food portion sizes to estimate size. Background data and information on lifestyle were collected by means of a questionnaire. Results indicate that, in general, the study group was reasonably well nourished. However, fat consumption (40%) was higher than the target of <35% for energy intake, for both males and females, and saturated fat intake (15%) was also above the 10% of energy guideline. The percentage of energy derived from carbohydrate (45%) was below the guideline value of 50% for energy intake for males and females. Relatively low iron, calcium and folate intakes were found for females. Smoking was more prevalent among females than males. Alcohol consumption among females was higher than among males. Even though all students participated in some physical activity, less females participated in high activity sport. Based on these results, some concern about the dietary habits and the related health consequences in Cork adolescents appears justified.