Materials Literature
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A detailed study on bromination and subsequent imidization of perylene bisanhydride with cyclohexylamine is reported. The present results reveal that previously reported 1,7-difunctionalized perylene bisimides are presumably contaminated with the respective 1,6 regioisomers. N,N'-Dicyclohexyl-1,7-dibromoperylene bisim…
In this work, the suitability of imidazolium-based ionic liquid solvents is investigated for the dissolution and regeneration of silkworm (Bombyx mori) silk. Within an ionic liquid the anion plays a larger role in dictating the ultimate solubility of the silk. The dissolution of the silk in the ionic liquid is confirm…
In order to obtain high reflectance of EUV and X-ray multilayer mirrors, highly polished substrate surfaces with rms roughness σ<sub>rms</sub> = 0,1-0.2 nm are necessary. However, the simultaneous achievement of low micro-roughness and precise surface figure is very challenging and often not accomplished. Theref…
A number of X-ray astronomical missions of near future (Constellation-X, XEUS, Simbol-X) will make use of hard X-rays (10-100 keV) optics with broad-band multilayer coatings. A possible technique under development is based on an extension of the already tested replication of a coated mandrel by e-beam deposition and n…
We have investigated the energetics of hydrogen site occupation in LaNi5Hn (hexagonal P63mc structure) and LaCo5Hn (orthorhombic Cmmm structure) via calculation of the site-dependent enthalpies of hydride formation ΔH. For each structure ΔH was determined for a broad variety of hydrogen configurations. In LaNi5Hn(LaCo…
Crystal structure of nobleite from locality Jarandol (Serbia) has been refined using single-crystal data (Mo K α radiation, CCD area detector) to the conventional R 1 factor 0.0324 for 2432 reflections having I > 2σ( I ) and 0.0540 for all 3383 data. Hydrogen atoms were found in difference Fourier maps and were refine…
We apply the simplified bond hyperpolarizability model to calculate bulk third-harmonic generation from tetrahedrally bonded crystals of cubic symmetry, comparing the results to data for crystalline Si. We find very good agreement between model predictions and data. Only scaling is needed for the $ps$ and $sp$ polariz…
Museumite, ideally Pb 5 AuSbTe 2 S 12 , is a newly identified mineral from the gold-telluride deposit of Sacarimb, Metaliferi Mountains, western Romania. The mineral occurs as anhedral to subhedral grains up to 300 μm in cavities and vugs of large nagyagite crystals and it does not show any inclusion or intergrowth of…
The crystal structure of pellouxite, a natural Pb-Sb-(Cu,Ag) oxy-chloro-sulfide from Tuscany (Italy), has been solved and refined using single-crystal X-ray-diffraction, with a final R = 0.044. The symmetry is monoclinic, space group C 2/ m , with a = 55.824(11), b = 4.0892(8), c = 24.128(5) A, β = 113.14(3)°, V = 506…
Transparent and nanostructured polymer membranes (see Figure of cells attached to membrane surface) have been fabricated successfully via the polymerization of bicontinuous microemulsions. The resultant membranes demonstrate temperature-dependent swelling behavior with increased water uptake at lower temperatures. The…
We have used ion implantation for erbium doping of mesoporous silicon microcavities. Optically active erbium-doped microcavities with Q factors in excess of 1500 have been demonstrated. We observed strong modification of the emission properties of the erbium in the microcavity with an accompanying cavity enhancement f…
Bulk ZnO substrates were rapid thermal annealed in either air or N2 at temperatures up to 500°C. The root-mean-square roughness of the surface as measured by atomic force microscopy begins to increase even after 200°C anneals in N2 or 300°C in air. The Schottky barrier height, ΦB, obtained from Pt∕Au diodes fabricated…
Preparation of water-filled silicone nanocapsules of controlled size is reported. Catanionic vesicles are used as templates for tetramethylcyclotetrasiloxane (D4H) crosslinking reactions inside their bilayers. Various characterization techniques confirmed the synthesis of nonporous, impermeable, highly crosslinked, ho…
Open-pored mesoscopic 2D titania layers (see Figure) were fabricated by using a nanoparticle layer as a template. Monodisperse polymer particles approximately 60 nm in diameter were spontaneously formed by dissolving polystyrene-b-poly(N-methyl-2-vinylpyridinium iodide) in toluene. These particles self-assembled at th…
Strong ultraviolet electroluminescence with an external quantum efficiency above 1% is observed from an indium-tin oxide/SiO2:Gd∕Si metal–oxide–semiconductor structure. The SiO2:Gd active layer is prepared by thermal oxidation followed by Gd+ implantation and annealing. The electroluminescence spectra show a sharp pea…
Pellouxite, the second natural oxy-chloro-sulfosalt after pillaite, has been discovered in cavities of calcite veins in the \nsmall Fe-Ba deposit of Buca della Vena mine, Apuan Alps (Tuscany, Italy). The new mineral name honours professor Alberto \nPelloux (1868-1948), curator of the mineralogical Mu…
We report on the synthesis of the Si∕ZnS and Si∕ZnSe core/shell nanocrystal structures produced via a two-stage thermal evaporation of SiO and ZnS or SiO and ZnSe powder mixtures. These core/shell structures display spherical and elliptical polycrystalline particles. Most of the Si∕ZnS core/shell nanocrystal structure…
Abstract Summary: A simple spectrophotometric method is proposed for determining deacetylation degrees ( DD ) of chitinous materials using phosphoric acid as the UV‐transparent solvent system. Calibrating by the extinction coefficients ( A 210 ) of D ‐glucosamine and N ‐acetyl‐ D ‐glucosamine, DD values (24–88%) were…
Two different types of erbium-doped silicon nanocrystals, along with undoped, oxide-capped Si dots, are employed to probe the impact of the impurity center location on phase transition pressure. Using a combination of high pressure optical absorption, micro-Raman, and x-ray diffraction measurements in a diamond anvil…
A transparent glass–ceramic containing borate crystallites in tellurite glass is reported. Controlled heat treatment resulted in surface crystallization of BaB4O7 in the BaO–B2O3–TeO2 glass system. The second-order optical nonlinearities observed in these surface crystallized glasses were attributed to the distortion…