Fabrication of carbon nanotube assemblies on Ni–Mo substrates mimics law of natural forest growth

We fabricated cone-shaped carbon nanotube assemblies, which align in a densely packed geometry like a cedar tree forest, on unpatterned nanocomposite substrate of Ni and Mo by the DC plasma assisted hot filament chemical vapor deposition. Carbon nanotubes initially grew on the nickel domains created during deposition, forming cone-shaped assemblies. These assemblies grew keeping their shape with decreasing their number density by merging together. The relationship between the mean volume and the number density of conical-shaped tree-like assemblies was similar to one of natural plant forest.     

Fluid-dynamic interaction between two spheres

Experiment of fluid-dynamic interaction between two spheres was conducted to obtain basic information concerning the two-phase flow, especially in dense phase. Two or three spheres were set up in a water tunnel in the longitudinal or transverse direction with Reynolds numbers less than 10³. The flow behind the sphere was visualized by the use of condense milk and change in vortex structure due to the interaction was observed in detail. Additionally, drag force on the sphere was measured by a pendulum method which was developed to detect small drag, and the range of distance in which the drag is affected by the interaction was shown.     

Large positive magnetoresistance of insulating organic crystals in the non-ohmic region

We report a large positive magnetoresistance ratio in insulating organic crystals theta-(ET)(2)CsZn(SCN)(4) at low temperatures at which they exhibit highly nonlinear current-voltage characteristics. Despite the nonlinearity, the magnetoresistance ratio is independent of the applied voltage. The magnetoresistance ratio depends little on the magnetic field direction and is described by a simple universal function of mu(B)B/k(B)T, where mu(B) is the Bohr magneton. The positive magnetoresistance may be caused by magnetic-field-induced parallel alignment of spins of mobile and localized electrons, and a resulting blockade of electrical conduction due to the Pauli exclusion principle.     

Engineering control over the conformation of the alkyne-aryl bond by the introduction of cationic charge

A novel arylene-ethynylene molecule has been synthesized. This molecule is more stable in a coplanar form than in a twisted form as in the cases of typical arylene-ethynylene molecules. When the cationic charge was introduced into the pi-conjugated system, the perpendicularly twisted form became more stable than the coplanar state. The conformational change was controlled by introduction and removal of cationic charge, confirmed by the absorption and fluorescence spectroscopy and DFT calculation.     

Acceleration of a QM/MM‐QMC simulation using GPU

We accelerated an ab initio molecular QMC calculation by using GPGPU. Only the bottle‐neck part of the calculation is replaced by CUDA subroutine and performed on GPU. The performance on a (single core CPU + GPU) is compared with that on a (single core CPU with double precision), getting 23.6 (11.0) times faster calculations in single (double) precision treatments on GPU. The energy deviation caused by the single precision treatment was found to be within the accuracy required in the calculation, ～10^?5 hartree. The accelerated computational nodes mounting GPU are combined to form a hybrid MPI cluster on which we confirmed the performance linearly scales to the number of nodes. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

Solvent-dependent supramolecular assemblies of π-conjugated anion-responsive acyclic oligopyrroles

Amide-attached pyrrole-based π-conjugated anion receptors showed solvent-dependent assembled modes such as H-aggregates that were soluble in octane and highly organized structures that provided supramolecular gels in CH(2)Cl(2) and 1,4-dioxane in the absence of π-π stacking.     

Epitaxial thin films of ATiO(3-x)H(x) (A = Ba, Sr, Ca) with metallic conductivity

Epitaxial thin films of titanium perovskite oxyhydride ATiO(3-x)H(x) (A = Ba, Sr, Ca) were prepared by CaH(2) reduction of epitaxial ATiO(3) thin films deposited on a (LaAlO(3))(0.3)(SrAl(0.5)Ta(0.5)O(3))(0.7) substrate. Secondary ion mass spectroscopy detected a substantial amount and uniform distribution of hydride within the film. SrTiO(3)/LSAT thin film hydridized at 530 °C for 1 day had hydride concentration of 4.0 × 10(21) atoms/cm(3) (i.e., SrTiO(2.75)H(0.25)). The electric resistivity of all the ATiO(3-x)H(x) films exhibited metallic (positive) temperature dependence, as opposed to negative as in BaTiO(3-x)H(x) powder, revealing that ATiO(3-x)H(x) are intrinsically metallic, with high conductivity of 10(2)-10(4) S/cm. Treatment with D(2) gas results in hydride/deuteride exchange of the films; these films should be valuable in further studies on hydride diffusion kinetics. Combined with the materials' inherent high electronic conductivity, new mixed electron/hydride ion conductors may also be possible.