Materials Literature
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We present a density-functional theory for the growth of equilibrium nematic and smectic-A wetting layers near free surfaces. In the nematic case our theory predicts complete wetting, with the integrated order parameter diverging logarithmically as one approaches the ordering temperature from the isotropic phase. When…
Abstract Four periods of loess deposition in the Lower Mississippi Valley can be identified on the basis of geochemical and mineralogical criteria, radiocarbon dating, and thermoluminescence dating. These are designated Loess Units 1,2,3, and 4 in order of increasing age. Carbonate‐rich Unit 1 loess comprises more tha…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSize effects on the .alpha.-.beta. transformation of phthalocyanine crystalsFumio IwatsuCite this: J. Phys. Chem. 1988, 92, 6, 1678–1681Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March 1988https://pubs.acs.org/doi/…
A sol-gel process for low-temperature preparation of BaTiO{sub 3} powders is described. Chemical polymerization between barium acetate and titanium(IV) isopropoxide leads to the formation of barium titanate gels. After suitable drying and calcination treatments, the barium titanate gels were converted to BaTiO{sub 3}…
Abstract Polypropylene was degraded by injection of a free‐radical initiator during extrusion. Molecular weight distribution, molecular weight averages, and melt flow index were measured to see the effect of initiator concentration (0.00 to 0.04 wt%), temperature (200 and 220°C), and screw rpm (31 and 44). Initiator c…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIntramolecular photochemical electron transfer. 4. Singlet and triplet mechanisms of electron transfer in a covalently linked porphyrin-amide-quinone moleculeJohn A. Schmidt, Alan R. McIntosh, Alan C. Weedon, James R. Bolton, John S. Connolly, John K. Hurley, and Michael R.…
Evidence of a first-order smectic-A--smectic-${C}^{\mathrm{*}}$ (SmA-Sm${C}^{\mathrm{*}}$) transition is presented. Detailed x-ray studies on 4-(3-methyl-2-chloropentanoyloxy)4'-heptyloxybiphenyl show that the SmA-Sm${C}^{\mathrm{*}}$ transition in this material is characterized by a discontinuous jump in the layer sp…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCollapse of poly(ethylene oxide) monolayersDaniel J. Kuzmenka and Steve GranickCite this: Macromolecules 1988, 21, 3, 779–782Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March 1988https://pubs.acs.org/doi/10.1021/ma0…
Hysteresis loops and remanent polarization below Tt -70 °C suggest that a ferroelectric phase can be induced in PMN crystals by an electric field parallel to [110], [111], and [001]. This could be corroborated, however, only for the two former cases by optical investigations and X-ray analysis.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of aromatic polyamides from N,N'-bis(trimethylsilyl)-substituted aromatic diamines and aromatic diacid chloridesYoshiyuki Oishi, Masaaki Kakimoto, and Yoshio ImaiCite this: Macromolecules 1988, 21, 3, 547–550Publication Date (Print):March 1, 1988Publication History…
An adiabatic scanning calorimeter has been used to study the thermal behavior of the liquid-crystal cholesteryl nonanoate in a temperature range covering all phase transitions involving the three different blue phases occurring in this substance. Results for the temperature dependence of the enthalpy and the heat capa…
The crystal structure and the magnetic properties are determined for several novel ternary intermetallic compounds of the type RFe/sub 10/T/sub 2/, where R represents Ti, V, Cr, Mo, W, or Si. All these compounds show a strong ferromagnetic behavior, with Curie temperatures in the range 350 K to 600 K. The magnetic and…
The synthesis of a new series of heterocyclic mesogens, the trans-4-alkyloxy-4'-stilbazoles (CnH2n+1OC6H4CH=CHC5H4N), is described and the phase behaviour is reported for all homologues between methyloxy (C1) and dodecyloxy (C12). For n < 3, the compounds are non-mesomorphic; monotropic smectic phases are observed for…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMonolayer of polystyrene monomolecular particles on a water surface studied by Langmuir-type film balance and transmission electron microscopyJiro KumakiCite this: Macromolecules 1988, 21, 3, 749–755Publication Date (Print):March 1, 1988Publication History Published online1…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSpectroscopy of transition region speciesPhilip R. BrooksCite this: Chem. Rev. 1988, 88, 2, 407–428Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March 1988https://pubs.acs.org/doi/10.1021/cr00084a004https://doi.org/10…
Time-resolved fluorescence and fluorescence anisotropy measurements have been performed on solutions of high molecular weight polysilane materials. The physical processes responsible for the decay of the anisotropy are discussed.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProperties of neutral clusters from scattering experimentsUdo BuckCite this: J. Phys. Chem. 1988, 92, 5, 1023–1031Publication Date (Print):March 1, 1988Publication History Published online1 May 2002Published inissue 1 March 1988https://pubs.acs.org/doi/10.1021/j100316a008htt…
The effect of rare‐earth oxide additives on the densification of silicon nitride by pressureless sintering at 1600° to 1700°C and by gas pressure sintering under 10 MPa of N 2 at 1800° to 2000°C was studied. When a single‐component oxide, such as CeO 2 , Nd 2 O 3 , La 2 O 3 , Sm 2 O 3 , or Y 2 O 3 , was used as an add…
Aluminosilicate gels with compositions Al 2 O 2 /SiO 2 and 2 were prepared by gelling a mixture of colloidal pseudo‐boehmite and a silica sol prepared from acid‐hydrolyzed Si(OC 2 H 5 ) 4 . Upon heating the pseudo‐boehmite transforms to γ‐Al 2 O 3 around 400°C, then to δ‐Al 2 O 3 at 1050°C, and at 1200°C reacts with a…
The role that bacterial surface hydrophobicity (surface tension) plays in determining the extent of adhesion of polymer substrates and phagocytic ingestion is reviewed. The early attachment phase in bacterial adhesion is shown to depend critically on the relative surface tensions of the three interacting phases; i.e.,…