Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Pancake vortices in stacks of thin superconducting films or layers are considered. It is stressed that in the absence of Josephson coupling topological restrictions upon possible configurations of vortices are removed and various examples of structures forbidden in bulk superconductors are given. In particular, it is…
Thermoreversible gelation of relatively short n -alkanes and a variety of other organic liquids has been accomplished using low concentrations of long n -alkanes (chain lengths from 24 to 36 carbon atoms) as gelators. The stability of the gels is discussed in terms of gelator concentration, gelation temperature, and t…
The effects of “short term shearing” on the subsequent crystallization of a polydisperse Ziegler−Natta isotactic polypropylene are observed using in situ optical measurements and ex situ microscopy. Imposition of brief intervals of shear (0.25−20 s, less than a thousandth of the quiescent crystallization time) can red…
The microstructure of ethene/norbornene copolymers produced by metallocene/methylaluminoxane catalysts is investigated by 13 C NMR spectroscopy. The microstructure of alternating copolymers is assigned on the pentad level by comparison of the pentad distribution in 13 C NMR spectra with the calculated distribution acc…
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…