Materials Literature
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A large first-order magnetic phase transition in an organic radical, 1,3,5-trithia-2,4,6-triazapentalenyl, is described. The transition occurs with a wide thermal hysteresis loop over the temperature range 230 to 305 kelvin. The high-temperature phase is paramagnetic, and its structure consists of a uniform one-dimens…
Ferroelectric and paraelectric films deposited on dielectric and semiconductor substrates were studied at the frequency range 0.3-100 GHz and temperature interval 300-700 K in comparison with chemically equivalent bulk materials. A dielectric spectroscopy method helps to trace the change of dielectric polarization and…
Dynamical properties of bulk poly(propylene sulfide) (PPS) were investigated for a range of molar masses between 600 and 50 000 g/mol. The primary and secondary relaxation (α-relaxation and β-relaxation) were studied using dielectric spectroscopy. The local segmental relaxation (α-relaxation) and the chain backbone co…
Structures of water-insoluble complexes of polyethyleneimine (PEI) and fluorinated acids, varying in chain length from 4 to 16, were examined via contact angle measurements, X-ray diffraction, and infrared spectroscopy. The wettability of complex surfaces was shown to decrease with increasing chain length. The surface…
New heterobinucleating ligands for heme−Cu O2-reactivity studies feature a variably appended tridentate chelate {N,N-bis[2-(2-pyridyl)ethyl]amine} possessing an already established copper(I)/O2 chemistry. Reduced metal complexes have been synthesized and characterized. (3L)FeII (1a), a heme−Fe(II) empty-tether complex…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTTransverse Cylindrical Microdomain Orientation in an LC Diblock Copolymer under Oscillatory ShearChinedum Osuji, Yuanming Zhang, Guoping Mao, Christopher K. Ober, and Edwin L. ThomasView Author Information Program in Polymer Science…
The kaolinite−mullite reaction process has been studied by single- and triple-quantum 27 Al magic-angle spinning (MAS) NMR. All materials have also been characterized by 29 Si MAS NMR and powder X-ray diffraction. It has been shown that in order to record reliable 27 Al MAS NMR spectra it is important to use very fast…
11-Aminoundecanoic acid capped titanium dioxide (capped-TiO 2 ) nanoparticles (63 ± 2 Å total diameter and 20−24 Å core diameter) and polyallylamine hydrochloride, PAH, have been layer-by-layer self-assembled onto precoated (by poly(diallyldimethylammonium chloride), PDDA, or PAH) substrates. The ultrathin S-PDDA(capp…
Reactions of Cu(hfacac)(2).H(2)O (hfacac = hexafluoroacetylacetonate) with pyrazine, 3-cyanopyridine, 1,2-bis(4-pyridyl)ethane, and 4,4'-trimethylenebipyridine in methylene chloride have been studied. Two types of products were obtained and crystallographically characterized: compounds 1 (Cu(hfacac)(2)(pyrazine)(2), o…
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…