Materials Literature
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Four new series of biforked mesogens derived from 3,4-dialkoxybenzoic acids or 3,4-dialkoxybenzaldehydes have been prepared and studied. These derivatives exhibit an interesting polymorphism in which both columnar and lamellar mesophases exist in the same series and in some cases in the same compound. The short chain…
Time‐dependent deformation behavior induced by an indentation, called indentation creep, was investigated for Na 2 O · 3SiO 2 glasses with various water contents by measuring the indentation depth as a function of time using a conical indenter. It was found that the indentation creep behavior of the glasses could be b…
ADVERTISEMENT RETURN TO ISSUEPREVArticlePerfluoroalkylene-activated poly(aryl ether) synthesisJeff W. Labadie and James L. HedrickCite this: Macromolecules 1990, 23, 26, 5371–5373Publication Date (Print):December 1, 1990Publication History Published online1 May 2002Published inissue 1 December 1990https://pubs.acs.org…
Monazite‐type CePO 4 powder (average grain size 0.3 μm) was dry‐pressed to disks or bars. The green compacts began to sinter above 950°C. Relative density ≧ 99% and apparent porosity <1% were achieved when the specimens were sintered at 1500°C for 1 h in air. The linear thermal expansion coefficient and thermal con…
A new type of chiral discotic liquid crystal is described. It is based on a triphenylene core but carries only one asymmetric side chain per mesogen. This system displays a columnar liquid-crystalline mesophase with a helical superstructure and a pitch of 3·0 nm over a temperature range of 227 K. Upon cooling it forms…
On average 110 coupled metallocycles are present in an oligomer stack when the phthalocyaninatoiron complex 1, R1 R2 2-Et-C6H12, is allowed to react with benzene diisocyanide. This and other oligomers could be characterized by 57Fe-Mössbauer and NMR spectroscopy.
Abstract The shear modulus and loss of ca. 30% crystalline nylon‐12 have been measured over the temperature range 100–440 K and frequency range 10 −4 −1 Hz. The effect of water and physical aging of the amorphous regions on the relaxation spectra have been investigated. Absorbed water decreases both the temperature an…
The combination of porphyrin and acetylene chemistry leads to interesting novel molecules. This is illustrated by the synthesis of the first acetylene-cumulene-porphyrinoid 1, which can be regarded as a stretched porphycene.
Abstract The electrochemical properties of phenolic resin-based activated carbon fiber cloth (ACFC) in an aqueous electrolyte and in a nonaqueous organic electrolyte have been investigated. The differential electric double-layer capacitance of ACFC with the specific surface area of 1630 m2 g−1 in the aqueous electroly…
Hans Fischer's octaethylporphyrin (OEP) is so far the best available and most investigated of all synthetic porphyrins. The bisvinylogue OEP 1 has now been synthesized in high yields in a few steps. Owing to its chemical stability, good accessibility, and hitherto most intense UV/VIS absorption for an organic dye, thi…
La transformation de phase, qui s'etend sur plus de 600K, s'effectue en deux etapes. De faibles deplacements d'atomes, associes a des ellipsoides thermiques hautement anisotropes, indiquent un caractere displacif pour le debut de la transformation. Ensuite les deux structures restent presque inchangees, la transformat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPlanar tetracoordinate carbon in zirconocene complex Cp2Zr(.mu.-.eta.1,.eta.2-Me3SiCCPh)(.mu.-Cl)AlMe2Gerhard Erker, Roland Zwettler, Carl Krueger, Ralf Noe, and Stefan WernerCite this: J. Am. Chem. Soc. 1990, 112, 26, 9620–9621Publication Date (Print):December 1, 1990Public…
Microwave plasma chemical vapor deposition was used to deposit diamond films on polished silicon and then the substrate was back-etched to form taut free-standing membranes up to 75 mm diam. Raman spectroscopy and x-ray diffraction verify that the films are diamond. Transmission electron microscopy and x-ray diffracti…
Chiral discotic liquid crystalline polymers are of interest because of their similarity to helical polymers, and for a comparison with chiral rod-shaped liquid crystals. They are now accessible in several forms, e.g. by doping achiral donor polymers with chiral acceptors (see Figure). The chirality of the discotic pha…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron delocalization in molecule-bridged polymetallic systems. Unique neutral complexes of TCNE or TCNQ and up to four organometallic fragments (C5R5)(CO)2MnRenate Gross-Lannert, Wolfgang Kaim, and Barbara Olbrich-DeussnerCite this: Inorg. Chem. 1990, 29, 25, 5046–5053Pub…
In this symposium an attempt was made to cover all of the current research thrusts in this emerging field of research by inviting internationally-known authorities in the various subfields of this general topic. The major emphasis became the high temperature corrosion behavior in corrosive gases and molten liquids lar…
The dynamic problem is approximated by a time series of static analysis problems. An algorithm is described wherein in each time step the material properties of the target and the geometry of the deflection cone are derived.An experimental program was performed involving bullets fired at Kevlar 29 fabric targets.
For the isotopic blend of polystyrene (PS) PS/deutero PS (M=106 dalton), the Flory–Huggins interaction parameter χ(φ,T) was determined by means of the structure factor S(Q) measured by small angle neutron scattering (SANS). From χ(φ,T), the miscibility gap and the corresponding spinodal line was evaluated with a criti…
The theoretical aspects of magnetic resonance (MR) imaging contrast agents are reviewed, and their current applications to the central nervous system (CNS) and their future applications are discussed. Profound differences exist between contrast agents used for MR imaging and computerized tomography (CT). In MR imaging…
Neutron-diffraction experiments were performed in order to investigate the structure of the thermoelastic martensite of the ${\mathrm{Ni}}_{62.5}$${\mathrm{Al}}_{37.5}$ alloy. The following results were obtained: (i) the low-temperature phase has a seven-layered monoclinic unit cell (7M martensite). (ii) Anomalous shi…