Materials Literature
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Abstract Die Vorteile heterogener Single‐Site‐Katalysatoren (single‐site heterogeneous catalysts, SSHCs) sind vielfältig. Sie ermöglichen es – sowohl experimentell als auch mit Computermethoden – den Mechanismus und die Kinetik eines katalytischen Umsatzes zu bestimmen, und sie machen die Energetik von Intermediaten e…
The field emission properties of individual multiwalled carbon nanotubes have been measured simultaneously in correlation to the emitter images and their real work functions at tips by the in situ transmission electron microscopy method. The field emission of a single nanotube still follows the Fowler-Nordheim law. Th…
The chemical sensitivity of electronic transport in carbon nanotubes under the physisorption of molecular species is investigated using a tight-binding scheme, parametrized by first-principles calculations. Such a computational method enables tackling of the complex electronic properties of chemically grafted conducti…
$Cu_3TeO_6$ is a modest frustrated $S=1/2$ spin system, which undergoes an anti-ferromagnetic transition at $T_N\sim61$ $K$. The anti-ferromagnetic spin alignment in $Cu_3TeO_6$ below $T_N$ is supposed to induce a magneto-elastic strain of the lattice. The complete absorption spectrum of $Cu_3TeO_6$ is obtained throug…
The LnBaCo 2 O 5+ δ cobaltites with ordered A-site cations exhibit a very rich phase diagram as a function of the oxygen content, which determines the doping of CoO 2 planes. By means of thermogravimetry analysis (TGA), we study the appropriate way to tailor oxygen contents in PrBaCo 2 O 5+ δ compounds. Starting from…
The Casimir and van der Waals interaction between two dissimilar thick dielectric plates is reconsidered on the basis of thermal quantum field theory in Matsubara formulation. We briefly review two main derivations of the Lifshitz formula in the framework of thermal quantum field theory without use of the fluctuation-…
Ga(In, Al)N alloys are used as an active layer or cladding layer in light emitting diodes and laser diodes. x-ray diffraction is extensively used to evaluate the crystalline quality, the chemical composition and the residual strain in Ga(Al,In)N thin films, which directly determine the emission wavelength and the devi…
Thin films of laser molecular-beam epitaxy grown ZnO films were studied with respect to their optical properties. 4-K reflectivity was used to analyze various samples grown at different biaxial in-plane strain. The spectra show two structures at 3.37 eV corresponding to the A-free exciton transition and at 3.38 eV cor…
We derive the path integral of the semiclassical, one dimensional anharmonic Holstein model assuming that the electron motion takes place in a bath of non linear oscillators with quartic on site hard (and soft) potentials. The interplay between {\it e-ph} coupling and anharmonic force constant is analysed both in the…
Ratchet effect, observed in many systems starting from living organism to artificially designed device, is a manifestation of motion in asymmetric potential. Here we report results of a conductivity study of Polypyrrole nanowires, which have been prepared by a simple method to generate a variation of doping concentrat…
We present a simple theory of the thermodynamics of an incommensurate quantum solid. The ground state of the solid is assumed to be an incommensurate crystal, with quantum zero-point vacancies and interstitials and thus a non-integer number of atoms per unit cell. We show that the low temperature variation of the net…
We study the dynamics of flexible polymer chains in solution by combining multiparticle-collision dynamics (MPCD), a mesoscale simulation method, and molecular-dynamics simulations. Polymers with and without excluded-volume interactions are considered. With an appropriate choice of the collision time step for the MPCD…
This study explores how to populate the surface of the carbon nanotubes with functional molecules that can be toggled back-and-forth between different molecular conformations. The molecules synthesized for this study are tagged with a photoswitchable headgroup and a functional group which directs the assembly on the s…
Patterned glycine crystals nucleated on functionalized metallic square islands. This approach can be used to fabricate particles with micron dimensions and screen solid forms under different conditions. The size of the glycine crystals is controlled by the dimensions of the islands. High energy metastable beta-glycine…
Spinning out: A cyanide-bridged molecular square (see picture) has been isolated and found to undergo thermally induced, two-step spin crossover. Molecules with more than one spin-crossover site are suitable building blocks for multistepped molecular switches.
Pyridoxine (vitamin B6) is a cofactor required by numerous enzymes in all cellular organisms. Plants are the major source of vitamin B6 for animals, yet the biosynthesis pathway and the function of vitamin B6 in plants are not well elucidated. In this study, an Arabidopsis pyridoxine synthase gene PDX1 was characteriz…
The growth of binary alloy clusters on a weakly interacting substrate through codeposition of two atomic species is studied by kinetic Monte Carlo simulation. Our model describes salient features of CoPt$_3$-nanoclusters, as obtained recently by the molecular-beam epitaxy technique. The clusters display perpendicular…
The polarized Raman spectra of orthorhombic RMnO3 series (R=La,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Y) were studied at room temperature. The variation of phonon frequencies with R ionic radius rR as a whole confirms the commonly accepted Raman line assignments with two noticeable exceptions: (1) with decreasing rR the stretching A…
Considerable effort has been expended on theoretical studies of superhydrophobic surfaces with two-tier (micro and nano) roughness, but experimental studies are few due to the difficulties in fabricating such surfaces in a controllable way. The objective of this work is to experimentally study the wetting and hydropho…
A small number of isolated Au3+ ions (0.02 Au3+/nm2) heterogenized on a zirconia surface from a cheap inorganic source (HAuCl4) is able to grant high catalytic activity for the selective hydrogenation of 1,3-butadiene (see picture). The catalytic turnover and mass activity rates of the Au3+ ions are respectively one a…