Materials Literature
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The syntheses of eight new star-shaped D(3)-symmetric arrays in which three 15-(pyrid-4-yl)porphyrin subunits are attached to the 1, 3, and 5 positions of a benzene core through linkers consisting of collinear repetitive phenylethynyl units have been carried out using Pd(0)-catalyzed coupling reactions. By the same pr…
The bending of a carbon nanotube is studied by considering the structural evolution of a carbon nanotorus from elastic deformation to the onset of the kinks and eventually to the collapse of the walls of the nanotorus. The changes in the electronic properties due to delocalized deformations are contrasted with those d…
Previous studies had demonstrated that the T g of polymer thin films is strongly dependent on the interactions, γ s, between the polymer and the underlying substrate. We present a study of the glass transition temperature, T g, in thin films of polystyrene, PS, as a function of film thickness and as a function of γ s…
Small drops sliding down a partially wetting substrate bifurcate between different shapes depending on their capillary number Ca. At low Ca, they are delimited by a rounded, smooth contact line. At intermediate values they develop a corner at the trailing edge, the angle of which evolves from flat to 60 degrees with i…
Controlling the surface properties of nanoparticulate materials is necessary if they are to be exploited in applications such as colloidal crystals or biolabeling. By tailoring the polymer flexibility and the electrostatic forces involved in polyelectrolyte adsorption onto highly curved gold surfaces, through variatio…
An accurate Patterson function, free of artifacts, is obtained by transforming low-energy electron diffraction I-V spectra at multiple incident angles. The demonstration is carried out using normal incidence measured spectra and calculated spectra at three angles of incidence. The errors between intensity spots in the…
The aim of this work is to study by means of dielectric and dynamic-mechanical techniques the miscibility and molecular mobility of sequential interpenetrating polymer networks (IPNs). Sequential poly(butyl acrylate)/poly(butyl methacrylate) interpenetrating networks with different cross-linking densities were prepare…
Low-temperature structural and magnetic properties of ${\mathrm{Bi}}_{0.5}{\mathrm{Sr}}_{0.5}{\mathrm{MnO}}_{3}$ investigated by neutron and synchrotron x-ray diffraction are reported. High-resolution powder diffraction data evidenced two-phase coexistence. One of the phases presents charge-exchange (CE) -type magneti…
[reaction: see text] A modified cinchona alkaloid was grafted onto a mesoporous molecular sieve and onto amorphous silica gel. These heterogeneous ligands were employed in the asymmetric dihydroxylation of olefins under Sharpless conditions. The supported ligands yielded equivalent enantioselectivity compared with tha…
The electronic structure and total energy of the Al and Cu alumina interfaces have been calculated with the plane wave pseudopotential method based on Lanczos diagonalization of the Kohn-Sham density matrix. For both interfaces we found in-plane relaxation, resulting in the rotation of the O triangle and expansion of…
The hydrogen bond consisting of a hydrogen atom positioned asymmetrically between a nitrogen and an oxygen atom $(\mathrm{N}---\mathrm{H}\ensuremath{\cdot}\ensuremath{\cdot}\ensuremath{\cdot}\mathrm{O})$ plays a central role in the structure and functionality of proteins and amino acids. The urea crystal is a simple s…
Elemental direct combination to synthesize ZnSe and CdSe only occurs at very high temperature. However, in this paper, a simplest hydrothermal elemental-direct-reaction method to produce nanocrystalline ZnSe and CdSe is established, only using water as reaction medium. It greatly decreases the temperature for the dire…
[Fe(abpt)2(N(CN)2)2] (abpt = 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole) represents the first example of an iron(II) spin-crossover compound containing dicyanamide ligand, [N(CN)(2)](-), as a counterion. It shows an incomplete two-step spin transition with around 37% of HS molecules trapped in the low-temperature re…
Highly crystalline germanium (Ge) nanocrystals in the size range 2--10 nm were grown in inverse micelles and purified and size separated by high-pressure liquid chromatography with on-line optical and electrical diagnostics. The nanocrystals retain the diamond structure of bulk Ge down to at least 2.0 nm (containing a…
Molecular dynamics simulations are used to investigate the diffusive flow of binary molecular mixtures through single-walled carbon nanotubes. Both H-terminated and C-terminated open nanotube ends are considered in the study. The specific mixtures examined are methane/ethane, methane/ n -butane, and methane/isobutane.…
Atomic force microscopy has been used to image the crystallization of polyethylene shish kebab crystals in situ, in real time, with nanometer resolution. Images of the extended chain backbone and overgrowth and subsequent interdigitation of lamellae have been obtained. Direct observation of the interdigitation process…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTEfficient Lewis Acid-Catalyzed Stereocontrolled Radical Polymerization of AcrylamidesYutaka Isobe, Daigo Fujioka, Shigeki Habaue, and Yoshio OkamotoView Author Information Department of Applied Chemistry Graduate School of Engineering, Nagoya University Furo-cho, Chiku…
We calculate the vibrational density-of-states in an insulating nanoparticle that is in weak mechanical contact with a semi-infinite substrate. The work is motivated by a recent experiment by Yang et al., where the low-energy phonon density-of-states of Y2O3 nanoparticles doped with Eu was measured. Preliminary result…
We report on the production of ordered assemblies of silicon nanostructures by means of irradiation of a Si(100) substrate with 1.2 keV Ar ions at normal incidence. Atomic Force and High-Resolution Transmission Electron microscopies show that the silicon structures are crystalline, display homogeneous height, and spon…
Spatial dependence of the magnetic field and the superconducting current in a flux line pinned by a screw dislocation are computed. Interaction of a superconducting vortex with the chiral-symmetry breaking elastic strain of a screw dislocation results in a helical current along the axis of the dislocation. It is argue…