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We describe here the high yield filling (i.e. > 50%) of single walled nanotubes (SWNTs) with a variety of halides, achieved according to various modified filling procedures. Both bundles and discrete SWNTs can be filled continuously up to lengths of several hundred nm, often with filling yields approaching 60-70% or better. In addition some high yield filled SWNTs were subjected to long-term washing in either boiling or room temperature, aqueous media, which does not remove the filling from the tubules, but enables effective removal of water-soluble extraneous materials.

Using high resolution electron microscopy and first principles quantum mechanical calculations we have explored the fundamental physics and chemistry of the semiconductor, HgTe grown inside single wall carbon nanotubes. This material forms a low-dimensional structure based on a repeating Hg2Te2 motif in which both atom species adopt new coordination geometries not seen in the bulk. Density-functional theory calculations confirm the stability of this structure and demonstrate conclusively that it arises solely as a consequence of constrained low dimensionality. This change is directly correlated with a modified electronic structure in which the low-dimensional form of HgTe is transformed from a bulk semimetal to a semiconductor.

Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005.

Restored high resolution transmission electron microscopy (HRTEM) images have been recorded from 1D semiconductor crystals formed within narrow diameter (ca. 1.4 nm) single walled carbon nanotubes (SWNTs). Two unique projections were obtained from separate crystal fragments encapsulated within separate nanotubes that has facilitated the reconstruction of the three dimensional arrangement of atoms within the two encapsulated fragments.

In common with rocksalt-type alkali halide phases and also semiconductors such as GeTe and SnTe, SnSe forms all-surface two atom-thick low dimensional crystals when encapsulated within single walled nanotubes (SWNTs) with diameters below ∼1.4 nm. Whereas previous density functional theory (DFT) studies indicate that optimised low-dimensional trigonal HgTe changes from a semi-metal to a semi-conductor, low-dimensional SnSe crystals typically undergo band-gap expansion. In slightly wider diameter SWNTs (∼1.4–1.6 nm), we observe that three atom thick low dimensional SnSe crystals undergo a previously unobserved form of a shear inversion phase change resulting in two discrete strain states in a section of curved nanotube. Under low-voltage (i.e. 80–100 kV) imaging conditions in a transmission electron microscope, encapsulated SnSe crystals undergo longitudinal and rotational oscillations, possibly as a result of the increase in the inelastic scattering cross-section of the sample at those voltages.

Increased exposure of women soldiers to combat in current conflicts heightens interest in the question of whether risk and resilience factors differ for female and male military personnel prior to deployment. The authors examined this question in a panel of 522 National Guard soldiers (462 men and 60 women) poised for deployment to Iraq. Soldiers completed a battery of self-report measures, including the PTSD Checklist, Beck Depression Inventory-II, and scales from the Deployment Risk and Resilience Inventory. Modest differences were observed between women and men on predeployment risk factors and some risk-related correlations with PTSD and depression measures; however, gender did not moderate the associations between hypothesized risk/resilience factors and baseline mental health. Implications for interventions and future research are discussed.

A new tubular form of HgTe grown in narrow single walled carbon nanotubes is described with Hg and Te in reduced coordination. Two unique projections obtained by HRTEM from two separate crystal fragments enabled reconstruction of the atomic arrangement of the new form. DFT confirmed the stability of the new structure and that it has a modified band gap, transforming HgTe from a semimetal to a semiconductor (band gap +1.3eV). HRTEM shows that as the nanotube diameter increases, the new form is no longer obtained and for diameters of 1.6-2 nm, disordered HgTe is obtained, for diameters >2 nm, sphalerite HgTe is obtained.

One hundred and sixty eight subjects participated in a randomised crossover study to determine whether halving or doubling the present dietary cholesterol intake from eggs had any influence on blood cholesterol concentration in people following current dietary recommendations. During the first eight weeks all participants were advised to follow a reduced fat diet (26% total energy for hyperlipidaemic patients, 35% total energy for normolipidaemic volunteers) with an increased ratio of polyunsaturated to saturated fatty acids. This background diet was continued throughout the 16 week experimental period, during which participants ate either two or seven eggs a week. A small but significant increase in total cholesterol was seen after four weeks in the group eating seven eggs a week compared with that in the group eating two eggs a week, but this was no longer apparent after eight weeks. Previous studies suggesting that dietary cholesterol has a greater effect on the serum cholesterol concentration either have been carried out against a background of a higher fat intake or have contrasted extreme cholesterol intakes. A further reduction in dietary cholesterol seems to be unnecessary in those people who have already reduced their intake of saturated fat and increased the ratio of polyunsaturated to saturated fatty acids and fibre rich carbohydrate.