Materials Literature
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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…
We report the observation of laser emission from a luminescent dye-doped cholesteric liquid crystal (CLC) excited by another dye-doped CLC laser. The idea is based on the cascade of two CLC cells containing two different dyes where the emission band of the first overlaps the absorption band of the second. This system…
The effect of negative capacitance (NC) was observed and investigated in conducting polymers with embedded PbS nanocrystals. NC occurred for signal frequencies up to 1MHz and was absent in control samples without nanocrystals. The amplitude of NC increased with the applied bias and was accompanied by a superlinear cur…
Eu 2 O 3 thin films were epitaxially grown on (001)LaAlO3(LAO) substrates using a polymer-assisted deposition technique. Microstructural studies by x-ray diffraction and transmission electron microscopy show that the films are epitaxial with an orientational relationship of (001)Eu2O3∥(001)LAO and [11¯0]Eu2O3∥[100]LAO…
Abstract The isolation and structural characterisation of a novel tris[peroxotitanium( IV )]‐substituted α‐Dawson polyoxometalate (POM), [α‐1,2,3‐P 2 W 15 (TiO 2 ) 3 O 56 (OH) 3 ] 9− ( 1a ), containing side‐on coordination (i.e. η 2 ‐coordination) of the peroxo group to the titanium( IV ) atom are described. A water‐s…
An oxide ion conducting material, La1.94Ba0.06Mo2O9, with ionic conductivity of the order of 0.084S∕cm at 800°C in air was prepared by a citrate-nitrate auto-ignition process. A 3% Ba doping has suppressed the resistive transition of unsubstituted La2Mo2O9, which in turn stabilized the high-temperature cubic phase at…
A new method based on nebulized spray pyrolysis is applied to the preparation of metal (zinc, cadmium, cobalt, and lead) nanowires. The resulting nanowires are single- crystalline. The oxidation of metal nanowires yields one-dimensional oxidic nanostructures. In the case of zinc metal, tubular ZnO is obtained.
Femtosecond pump–probe experiments have been carried out on an ensemble of single-wall carbon nanotubes deposited on a glass substrate. Measurements of transient changes of transmission and reflection provide an estimate of the real and imaginary parts of the second-order hyperpolarizability of carbon nanotubes. These…
Graphitic features are detected on 4H-SiC surface following oxidation and etching using surface enhanced Raman spectroscopy (SERS). The electronic state of the carbon is sp2 on both the Si- and C-faces of 4H-SiC. The structures of the “carbon clusters” consist of two-dimensional graphitic flakes less than 2 nm and one…
Abstract We report for the first time on the electroassisted biomimetic activation of molecular oxygen by a newly prepared electropolymerized polypyrrole‐manganese phthalocyanine film. The prepared films and their intervention in the electroassisted catalytic reduction of molecular oxygen were analyzed by cyclic volta…
Strong temperature-dependent photovoltaic effects have been observed in the heterojunction composed of a La0.32Pr0.35Ca0.33MnO3 (LPCM) film and a 0.5 wt % Nb-doped SrTiO3 substrate. The photovoltage shows a monotonic increase with the decrease of temperature, and its relative change can be as large as ∼7000% for a mod…
Epitaxial Pb(Zr,Ti)O3 (PZT) films 50 and 250nm thick with the Zr∕(Zr+Ti) ratio from 0.13 to 0.65 were grown on (100)cSrRuO3∕∕(100)SrTiO3 substrates at 540°C by pulsed-metalorganic chemical vapor deposition. The crystal orientation, lattice parameter, axial angle, and relative volume fraction of constituent domains wer…
The enzymatic degradation of typical chemically synthesized biodegradable plastics, such as poly(butylene adipate) and poly(epsilon-caprolactone), to a repolymerizable cyclic oligomer under continuous flow using an enzyme column was studied, directed towards green chemical recycling. It was confirmed that both polymer…
We propose ${\mathrm{Si}}_{x}{\mathrm{Ge}}_{1\ensuremath{-}x}$ alloys as suitable candidates for spintronic applications. Remarkably, our first-principles investigation explains, within the local spin density approximation, the microscopic mechanism that stabilizes the half metallicity in Si matrices under Ge alloying…
In order to explore the large shear-strain-induced polymorph, α-Ti3GeC2 polycrystals were investigated by using a synchrotron radiation source to 64GPa under nonhydrostatic state. Upon compression to 26.6GPa, α-Ti3GeC2 starts to transform to β-Ti3GeC2. As compared to α-Ti3GeC2, the cell parameter a of β-Ti3GeC2 is sli…
Na K-edge X ray absorption near-edge structure (XANES) spectra for minerals and glasses were collected using synchrotron radiation. Na-K XANES is a good structural probe to determine the coordination state of this element in important minerals and glasses. From the XANES spectra on crystalline reference phases with di…
We report on the mechanism of photodegradation of porous silicon luminescence in ambient containing molecular oxygen. Energy transfer from excitons confined in silicon nanocrystallites to molecular oxygen results in the generation of highly chemically reactive singlet oxygen molecules. The subsequent interaction of si…
Dual-frequency addressed hybrid-aligned nematic (HAN) liquid crystal cell is demonstrated as a variable optical attenuator at 1.55μm wavelength. By controlling the low- and high-frequency electric field, the dual-frequency liquid crystal (DFLC) molecules can be reoriented parallel or perpendicular to the substrates so…