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Geophagy, the deliberate act of eating soil, has been observed in various primate species, although the reasons for this behavior are poorly understood. The present study supports the general hypothesis that the physical and/or chemical nature of the soil is a likely reason for geophagy in hybrid macaque monkeys of Kowloon, Hong Kong. Samples were taken(More)
Density functional theory is used to show that the adhesion between single-walled carbon nanotubes (SWNTs) and the catalyst particles from which they grow needs to be strong to support nanotube growth. It is found that Fe, Co, and Ni, commonly used to catalyze SWNT growth, have larger adhesion strengths to SWNTs than Cu, Pd, and Au and are therefore likely(More)
The molecular dynamics method, based on an empirical potential energy surface, was used to study the effect of catalyst particle size on the growth mechanism and structure of single-walled carbon nanotubes (SWNTs). The temperature for nanotube nucleation (800-1100 K), which occurs on the surface of the cluster, is similar to that used in catalyst chemical(More)
Fe nanoclusters are becoming the standard catalysts for growing single-walled carbon nanotubes via chemical vapor decomposition. Contrary to the Gibbs-Thompson model, we find that the reduction of the catalyst size requires an increase of the minimum temperature necessary for the growth. We address this phenomenon in terms of solubility of C in Fe(More)
The Gibbs-ensemble Monte Carlo methods based on the extended single point charge [H. J. C. Berendsen, J. R. Grigera, and T. P. Straatsma, J. Phys. Chem. 91, 6269 (1987)] potential-energy surface have been used to study the clustering of vapor phase water under vapor-liquid equilibrium conditions between 300 and 600 K. It is seen that the number of clusters,(More)
Density-functional theory is used to assess the validity of modeling metal clusters as single atoms or rings of atoms when determining adhesion strengths between clusters and single-walled carbon nanotubes ͑SWNTs͒. Representing a cluster by a single atom or ring gives the correct trends in SWNT-cluster adhesion strengths ͑FeϷ CoϾ Ni͒, but the single-atom(More)
We review the advances made in understanding the mechanism of catalyzed carbon nanotube growth, with the main focus on direct dynamics and molecular dynamics studies of single-walled carbon nanotube (SWNT) growth. These studies have deepened our understanding of the catalytic SWNT nucleation and growth mechanisms, but more accurate and efficient methods are(More)
A simple model for joining two single-walled carbon nanotubes (SWNTs) with different, arbitrary chiralities is used to systematically label junction structures which contain pentagon-heptagon pairs. The model is also used, together with density functional theory, to study the energetics of diameter and chirality changes of thin SWNTs during catalyzed growth(More)
We report the observation of unusually strong and systematic changes in the electron transport in metallic single-walled carbon nanotubes that are undergoing collisions with inert gas atoms or small molecules. At fixed gas temperature and pressure, changes in the resistance and thermopower of thin films are observed that scale as roughly M(1/3), where M is(More)
Fungal endophytes in cool-season grasses may affect communities at multiple trophic levels. However, it is unclear whether community-scale endophyte effects arise due to the endophyte itself or as a result of unique, endophyte–host interactions. We used a long-term field experiment to test whether common-toxic (CT) and non-ergot alkaloid-producing (novel)(More)