Materials Literature
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The elusive chiral twisted alkene, 5,5′-bi-5H-cyclopenta[2,1-b : 3,4-b′]dipyridinylidene, known also as 9,9′-bi-4,5-diazafluorenylidene (BDAF), has been prepared in racemic form from 9-bromo-4,5-diazafluorene and from 9,9′-bi-4,5-diazafluorenyl and fully characterised. X-Ray measurements show that there is a twist of…
A novel acetophenone, cynantetrone (1), was isolated from the rhizome of Cynanchum taiwanianum and its structure determined by spectroscopic methods. Compound 1 and cynandione B (3) showed significant in vitro cytotoxicity against T-24 cell lines, and 3 also against PLC/PRF/5 cell lines.
Volume phase (VP) gratings are now available and being applied to the applications of astronomical spectroscopy, Raman spectroscopy, ultrafast lasers, and wavelength division multiplexers. A volume phase grating results from the recording of an interferometric pattern within the volume of a material which, when suitab…
Freisetzung des Liganden aus dem durch Templatsynthese gewonnenen Nickelkomplex 1 lieferte Isoporphycen (als Octaethylderivat 2), das erste Porphyrin-Konstitutionsisomer mit einem N4-Kern, bei dem E/Z-Isomerie ins Spiel kommt: 2 liegt als E-Isomer vor, das mit einer gerade noch nachweisbaren Menge (2 %) an Z-Isomer in…
Microwave and hot filament chemical vapor deposition processes were combined to deposit highly oriented and textured diamond films on Si (100). The sequential growth process yields closely packed crystallites with (100) surfaces that show no grain boundaries over areas of up to 60 000 μm2 by scanning electron microsco…
We demonstrate a general approach to identify and locate minority species at buried interfaces which are of fundamental interest in many fields of solid state research. The approach combines soft x-ray emission for bulk and photoelectron spectroscopy for surface sensitivity. In the present study, the interface between…
The dynamics of the freezing transition of the rotator phase crystal of ethanol into its orientational glass phase is monitored by measurements of molecular rotational components in the quasielastic neutron scattering spectrum. We demonstrate that phenomena observed at pico- and nanosecond scales can be mapped onto th…
The effect of spatially homogeneous time-periodic external forcing on dendritic solidification has been studied by phase-field modeling and experiments on liquid crystal. It is shown that the frequency of dendritic sidebranching can be tuned by oscillating pressure or heating. The main parameters that influence this p…
Both oxidized and reduced glutathione (gamma-L-Glu-L-Cys-Gly) react with the anticancer complex [Pt(en)Cl(2)] to form the bicyclic complex illustrated (en=ethylenediamine). This unprecedented structure, which was determined from extensive NMR experiments, contains a ten-membered macrochelate ring.
Barium strontium titanate films with good ferroelectricity have been obtained by a developed sol-gel processing, using a highly dilute spin-on solution. X-ray diffraction and scanning electron microscopy investigations show that large grains with the size of 100–200 nm in the films are formed from highly dilute spin-o…
More than 50 years after Otto Bayer's detailed description of [m,n]-polyurethanes, the first general synthesis of [n]-polyurethanes 1 is described. This series of aliphatic [n]-polyurethanes is synthesized by the in situ polymerization of the corresponding alpha,omega-isocyanato alcohol monomers, which in turn are mad…
The density of states and one-particle spectral function $A(\mathbf{k},\ensuremath{\omega})$ of the one- and two-orbital models for manganites, the latter with Jahn-Teller phonons, are evaluated using Monte Carlo techniques. Unexpectedly robust pseudogap (PG) features were found at low and intermediate temperatures, p…
We argue that the charge ordering observed in $50%$ doped manganites is a manifestation of the peculiar antiferromagnetic spin ordering. The latter, combined with the large Hund's rule physics in manganites, divides the whole system into the quasi-one-dimensional zigzag objects, which exhibit a very unique electronic…
Silica thin films containing Si nanocrystals and Er3+ were prepared by ion implantation. Excess Si concentrations ranged from 5% to 15%; Er3+ concentration for all samples was 0.5%. Samples exhibited photoluminescence at 742 nm (attributed to Si nanocrystals), 654 nm (defects due to Er3+ implantation), and at 1.53 μm…
Liberation of the ligand from the nickel complex 1 obtained by template synthesis yielded isoporphycene (as the octaethyl derivative 2), the first constitutional isomer of porphyrin with an N(4) core for which E/Z isomerism is involved: Compound 2 is present as the E isomer, which is in rapid, presumably acid-catalyze…
Amplifying planar waveguide structures in Er-doped nanocrystalline II/VI semiconductor layer systems were developed by photolithography and wet chemical etching. 2 μm thick planar waveguides on glass substrates with lateral dimensions down to 5 μm with rectangular cross section were realized. By optical excitation a m…
In contrast to the binary switchable mirror films (YHx, LaHx, REHx with RE:rare earth) which have a weak red transparency window in their metallic dihydride phase, rare-earth alloys containing magnesium are remarkable for the large contrast between their metallic dihydride and transparent trihydride phase. By means of…
Numerical calculations reveal that the target and spiral growth patterns in spherulites can be generated from the time-dependent Ginzburg-Landau equations (model $C$) by coupling a conserved compositional order parameter and a nonconserved crystal ordering parameter. Of particular interest is that the periodic concent…
Semipermeable nanoscopic hollow spheres or cages with diameters in the sub-micrometer to the 100 nm range are accessible by the self-assembly of polymers onto sub-micrometer sized particles (Möhwald et al.) or by the formation of shell-cross-linked polymeric micelles (Wooley et al.) followed by chemical degradation of…
Carbon nanotubes (CNTs), standing perpendicularly to a substrate with an electrode, were fabricated by thermal catalytic decomposition of ethylene from Co particles electrochemically embedded at the bottom of anodic alumina nanoholes. The thermal durability of the alumina nanoholes for the CNTs growth process was achi…