Materials Literature
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The freezing transition of a strongly dipolar Lennard-Jones fluid is investigated using Monte Carlo simulation. It is found that the system undergoes a ferroelectric liquid-to-solid transition when cooled under a constant pressure. Near the triple point the stable solid phase is a body-centered orthorhombic ferroelect…
A novel approach to the preparation of light-emitting diodes is presented here. Hybrid sol–gel layers have been employed as a film-forming rigid matrix doped with highly fluorescent perylene dyes (e.g., see Fig.) as light emitters. Electroluminescence was found to be remarkable even at incorporation levels as low as 6…
Control over the long-range orientation of liquid crystals (LCs) has been achieved by embedding LCs into porous thin films with engineered microstructures. Glancing angle deposition was used to fabricate these porous thin films (see Figure), and results are summarized here that show how the films act as alignment or “…
Abstract Silane coupling agents containing a carboxy group are not known because the chloro- or alkoxy group is reactive to the carboxylic acid. In this study, silane coupling agents bearing a 2-nitrobenzyl ester as a protecting group of carboxylic acid were synthesized and applied for surface modification of silica g…
A novel method has been found to enhance the metastable zone width of solutions in their supersaturated region in order to grow large size crystals. In which, the incorporation of a small quantity of Ethylenediamine tetra acetic acid (EDTA), a well-known chelating agent, enhances the zone width significantly due to it…
A critical examination of the reference X-ray powder-diffraction patterns of the serpentine minerals in the Powder-Diffraction File (PDF) database has revealed an unsettling situation. Most of the patterns in, or previously in, the PDF database are inaccurate, misidentified, or of poor quality. The PDF database is not…
peer reviewed
In situ Raman scattering measurements have been obtained for vitreous ${\mathrm{ZnCl}}_{2}$ compressed isothermally to 25 GPa. The Raman spectra indicate that, in contrast to other tetrahedral framework glasses, when compressed at room temperature glassy ${\mathrm{ZnCl}}_{2}$ crystallizes to the high-pressure ${\mathr…
Two previously unreported low-temperature structures of chlorine on silver(111) are discussed: the sharp Ag(111)−(√3 × √3)R30°−Cl, which disorders above 195 K and a split spot pattern assigned as Ag(111)−(13 × 13)−Cl. The latter surface is also disordered at room temperature and gives a diffuse pattern reminiscent of…
X-ray photoelectron spectra are reported for ordered and disordered chain conformations of poly(ethylene glycol) and poly(tetramethylene glycol). Both polymers show a conformational dependent intensity change at the top of the (C 2s + O 2s) band of the valence level spectrum, which is interpreted as due to changes in…
A prototype oxide thermoelectric element has been fabricated for the first time, for the application of power generation at high temperatures in air. Sintered bodies of Li 0.025 Ni 0.975 O(p-type) and Ba 0.4 Sr 0.6 PbO 3 (n-type) were directly joined under the uniaxial pressure of 4 MPa at 1123 K for 10 h in air. The…
Low-temperature vesuvianites crystallize in the two space groups P4/n or P4nc due to different arrangements of Ca-dodecahedra and M 2+,3+ square pyramids that form strings along the fourfold axes. Long-range ordered vesuvianites of acentric P4nc symmetry may have the same diffraction symmetry as centrosymmetric disord…
Abstract— Recently, it was found that some materials doped with rare‐earth ions show bright and long‐lasting phosphorescence. They do not include radioactive elements and can be safely used as luminous paints for use in the dark. Some of them are better than the traditional zinc sulfide doped with copper (ZnS:Cu). The…
Thin films of phenylphosphine oxide-containing polymers were exposed to low Earth orbit aboard a space shuttle flight (STS-85) as part of flight experiment designated Evaluation of Space Environment and Effects on Materials (ESEM). This flight experiment was a cooperative effort between the NASA Langley Research Cente…
The strength of yams spliced under different conditions is investigated. Statistical models that help predict the strength of the splices under different splicing and yarn parameters are established, and the optimum splicing conditions (optimizing both the splicer and the yam parameters) are investigated. The results…
The lamellar phase in diblock copolymer systems appears as a result of a competition between molecular and entropic forces, which selects a preferred periodicity of the lamellae. Grain boundaries are formed when two grains of different orientations meet. We investigate the case where the lamellae meet symmetrically wi…
The interaction domain for cytochrome c on the cytochrome bc(1) complex was studied using a series of Rhodobacter sphaeroides cytochrome bc(1) mutants in which acidic residues on the surface of cytochrome c(1) were substituted with neutral or basic residues. Intracomplex electron transfer was studied using a cytochrom…
We present results of Monte Carlo simulations for dilute to concentrated solutions of athermal, homogeneous dendritic polymers. The dendritic polymers are composed of tangent hard-spheres and vary from generation 0 to generation 5. These simulations investigate the effect of hyperbranching on the structure and thermod…
Normal coordinate analyses for 2-, 3- and 4-acetylpyridine and acetophenone were carried out employing a systematic procedure based on a modified valence force field that is comparable to those used previously for different aromatic molecules. The general valence force fields (GVFF) were determined using a set of 41 p…
We report the detailed temperature variation of the dielectric constant across the nematic-isotropic transition in both the normal and UV-irradiated states of a commercially available room temperature nematic mixture (E7 from E-Merck) doped with a small quantity (4.5 mol %) of a liquid crystalline azo compound. The ph…