Materials Literature
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The aim of this work is to investigate electronic structure, magnetic properties, and electrical resistivity of the ${\mathrm{Fe}}_{2}{\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{V}}_{x}\mathrm{Sn}$ Heusler alloys. We report x-ray photoelectron valence-band spectra and compare the results with those obtained from the self…
Field-induced magnetic order has been investigated in detail in the interacting spin 3/2 dimer system Cs3Cr2Br9. Elastic and inelastic neutron scattering measurements were performed up to H=6 T, well above the critical field H(c1) approximately 1.5 T. The ordering displays incommensurabilities and a large hysteresis b…
Chemistry makes the difference between metallic and semiconducting carbon nanotubes. It can also be used to turn metallic nanotubes into semiconducting ones, for example, by the addition of a simple organic fragment. This breakthrough has clear practical implications for nanotechnology. Moreover it begins to reveal th…
The question of why the iron displacement out of the porphyrin plane is enhanced in quintet states of singly ligated iron-porphyrin complexes compared to lower spin states and unligated iron-porphyrin is addressed. The spatial size of the Fe 2+ atom is analyzed with respect to different spin states, and it is shown th…
Guests in an achiral cavity experience asymmetric magnetic environments induced by chiral centers outside the cavity.
Nitrogen substitution reaction in a graphene sheet and carbon nanotubes of different diameter are investigated using the generalized tight-binding molecular dynamics method. The formation of a vacancy in curved graphene sheet or a carbon nanotube is found to cause a curvature dependent local reconstruction of the surf…
In the dithienylethene photochrome series, linking two photochromes together directly, or with an ethynyl spacer, shuts down the photoswitching of one of the photochromes. We report here, that for dihydropyrenes, two photochromes can be linked together without affecting the ability of either to photoswitch. [reaction-…
A series of polyoxometalates (POM)/1,10-decanediamine ultrathin films were fabricated by self-assembly, and their photochromic properties were investigated. It is found that the films fabricated from molybdenum POMs show better photochromic responses than those from tungsten POMs. The photochromic responses of these h…
Synthesis and magnetic studies of annelated macrocyclic polyradicals and a related high-spin polymer with macrocyclic repeat units are described. Polyarylmethyl polyether precursors to the polyradicals and the related polymer are prepared by using Negishi cross-coupling of difunctionalized calix[4]arene-based macrocyc…
The thickness and curvature profiles of partially wetting condensing drops of 2-propanol on a quartz surface were measured using image analyzing interferometry and a new data analysis procedure. The profiles give fundamental insight into the phenomena of phase change, pressure gradient, fluid flow and spreading in a c…
Funktion(alis)iert: Organische Gruppen mit mehreren Alkoxysilansubstituenten werden in der Synthese mesoporöser organisch-anorganischer Hybridmaterialien verwendet (siehe Schema). Die entstehenden Systeme enthalten die organischen Bausteine als integralen Bestandteil der Porenwand. Je nach der Funktionalität der organ…
Time-resolved small-angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) analyses were used to study the isothermal crystallization and remelting of poly(ethylene isophthalate- co -terephthalate)s containing 0−10 mol % isophthalate unit. For each of the polymers considered, evidence of the formati…
2. Negative-index media 393 3. Wave propagation and refraction in left-handed media 394 4. Negative refraction and the causality principle 395
The structural evolution of regenerated Bombyx mori silk fibroin during shearing with a Couette cell has been studied in situ by synchrotron radiation small- and wide-angle x-ray scattering techniques. An elongation of fibroin molecules was observed with increasing shear rate, followed by an aggregation phase. The agg…
We propose an atomistic model for the nucleation of aluminum oxide on the Al(111) surface derived from first principles molecular dynamics simulations. The process begins with the dissociative adsorption of O2 molecules on the metal surface, which occurs via a "hot-atom" mechanism driven by the partial filling of the…
Nanostructures (nanotubes, nanowires, etc.) have been the object of intense theoretical and experimental investigations in recent years. Among these structures, helical nanosprings or nanocoils have attracted particular interest due to their special mechanical properties. In this work, we investigated structural prope…
The role of molecular structure, charge, and hydrophobicity in polyelectrolyte layer-by-layer assembly (LbL) of thin films has been studied using the model polypeptides poly-L-glutamatic acid (PLGA) and poly-L-lysine (PLL), quartz crystal microbalance (QCM), and circular dichroism spectroscopy (CD). The adsorption beh…
Tree-shaped molecules consisting of octa-p-phenylene as a stem segment and oligoether dendrons as a flexible head were synthesized and characterized. The molecular tree based on a small flexible head self-assembles into a lamellar structure, whereas the molecule based on a larger headgroup self-assembles into a discre…
The kinetics of exchange ofphenylethanethiolate ligands (PhC2S) of monolayer-protected clusters (MPCs, average formula Au140(PhC2S)53) by para-substituted arylthiols (p-X-ArSH) are described. 1H NMR measurements of thiol concentrations show that the exchange reaction is initially rapid and gradually slows almost to a…
Littoral diatom assemblages from different natural substrates (stones, mud, reeds) were used for estimating trophic status in seven perialpine lakes near Salzburg (Austria). Four trophic status indices were compared with the actual chemical data and the annual averages of total phosphorus concentrations. Diatom assemb…