Elastic precursor of the transformation from glycolipid-nanotube to -vesicle

By the combination of optical tweezer manipulation and digital video microscopy, the flexural rigidity of single glycolipid "nano" tubes has been measured below the transition temperature at which the lipid tubules are transformed into vesicles. Consequently, we have found a clear reduction of the rigidity obviously before the transition as temperature increasing. Further experiments of infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) have suggested a microscopic change of the tube walls, synchronizing with the precursory softening of the nanotubes.Comment: 9 pages, 6 figure

Structure and magnetism in carbon nanotubes including magnetic wire

金沢大学大学院自然科学研究科計算科学金沢大学理学部We have studied the electronic structure of the carbon nanotubes which include Fe atomic wire with using the density functional theory. As the stable geometries, we obtained the straight and zigzag wires, which have ferromagnetic and antiferromagnetic alignments, respectively. The antiferromagnets consists of the two ferromagnetic dimers which couple in antiparallel alignment. We presents the band dispersions and the density of states for the magnetic nanotubes. The electronic structure at the Fermi level consists of the Fe 3d and C 2pπ states, which shows a strong hybridization between them. © EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2007

Ab initio study of canted magnetism of finite atomic chains at surfaces

By using ab initio methods on different levels we study the magnetic ground state of (finite) atomic wires deposited on metallic surfaces. A phenomenological model based on symmetry arguments suggests that the magnetization of a ferromagnetic wire is aligned either normal to the wire and, generally, tilted with respect to the surface normal or parallel to the wire. From a first principles point of view, this simple model can be best related to the so--called magnetic force theorem calculations being often used to explore magnetic anisotropy energies of bulk and surface systems. The second theoretical approach we use to search for the canted magnetic ground state is first principles adiabatic spin dynamics extended to the case of fully relativistic electron scattering. First, for the case of two adjacent Fe atoms an a Cu(111) surface we demonstrate that the reduction of the surface symmetry can indeed lead to canted magnetism. The anisotropy constants and consequently the ground state magnetization direction are very sensitive to the position of the dimer with respect to the surface. We also performed calculations for a seven--atom Co chain placed along a step edge of a Pt(111) surface. As far as the ground state spin orientation is concerned we obtain excellent agreement with experiment. Moreover, the magnetic ground state turns out to be slightly noncollinear.Comment: 8 pages, 5 figures; presented on the International Conference on Nanospintronics Design and Realizations, Kyoto, Japan, May 2004; to appear in J. Phys.: Cond. Matte

Developments in the Ni–Nb–Zr amorphous alloy membranes

Most of the global H2 production is derived from hydrocarbon-based fuels, and efficient H2/CO2 separation is necessary to deliver a high-purity H2 product. Hydrogen-selective alloy membranes are emerging as a viable alternative to traditional pressure swing adsorption processes as a means for H2/CO2 separation. These membranes can be formed from a wide range of alloys, and those based on Pd are the closest to commercial deployment. The high cost of Pd (USD *31,000 kg-1) is driving the development of less-expensive alternatives, including inexpensive amorphous (Ni60Nb40)100-xZrx alloys. Amorphous alloy membranes can be fabricated directly from the molten state into continuous ribbons via melt spinning and depending on the composition can exhibit relatively high hydrogen permeability between 473 and 673 K. Here we review recent developments in these low-cost membrane materials, especially with respect to permeation behavior, electrical transport properties, and understanding of local atomic order. To further understand the nature of these solids, atom probe tomography has been performed, revealing amorphous Nb-rich and Zr-rich clusters embedded in majority Ni matrix whose compositions deviated from the nominal overall composition of the membrane

Non-collinear magnetic moments of seven-atom Cr, Mn and Fe clusters

The non-collinearity of magnetic moments of pentagonal bipyramid Cr7, Mn7 and Fe7 clusters is discussed. The magnetic moments are calculated by the discrete variational non-collinear spin-density functional method. For the Cr7 cluster, a coplanar magnetic arrangement appears at the large interatomic distance. With decreasing the interatomic distance, the coplanar arrangement changes to the parallel arrangement with a small absolute magnetic moment. For the Mn7 cluster, the magnetic arrangement changes from coplanar to antiparallel with decreasing the interatomic distance. Also for the Fe7 cluster, some coplanar magnetic moments appear at the interatomic distance of 2.23 Å. In these coplanar magnetic arrangements, the magnetic moment at the basal site of the pentagon rotates with a step of 144 degrees for the Cr7 clusters and 72 degrees for the Mn7 and Fe7 clusters

Bonding properties and structures of titanium clusters on (10, 0) single wall carbon nano capsule

We optimize whole structures of Ti clusters, Tin (n=1, 3 and 7), on a zigzag-type (10, 0) single wall carbon nano capsule, C160, by using the first principles molecular dynamics within the spin density functional approximation, and discuss the bonding properties of Ti clusters on the C160. For all the clusters, the most stable configuration includes a site above a center of C-hexagonal or pentagonal ring. The shape of Ti7 cluster is very different by the located site. The cluster in which Ti atoms are located around centers of hexagon has a flat bottom and flatten the curvature of C wall below it