Materials Literature
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The role of local fields in the optical response of silicon nanocrystals is analyzed using a tight binding approach. Our calculations show that, at variance with bulk silicon, local field effects dramatically modify the silicon nanocrystal optical response. An explanation is given in terms of surface electronic polari…
Fourier Transform Infrared (FTIR) spectroscopy has been utilized during high rate E-beam evaporation/deposition of YBa2Cu3O7 (YBCO). The results demonstrate the great utility of FTIR as an in situ monitor of YBCO deposition and processing. We detect different (amorphous/fine polycrystalline) insulating pre-existing ph…
A possible origin of unusual temperature behavior of transport coefficients observed in densely packed polycrystalline CaAl_{2} compound [M. Ausloos et al., J. Appl. Phys. 96, 7338 (2004)] is discussed, including a power-like dependence of resistivity with $ρ\propto T^{-3/4}$ and N-like form of the thermopower. All th…
Using a highly-sensitive home-made mutual-inductance technique, temperature profiles of the magnetic penetration depth $λ(T)$ in the optimally-doped $Sm_{1.85}Ce_{0.15}CuO_4$ thin films have been extracted. The low-temperature behavior of $λ(T)$ is found to be best-fitted by linear $Δλ(T)/λ(0)= \ln(2)k_BT/Δ_0$ and qua…
To probe the influence of structural disorder on low-temperature behavior of magnetic penetration depth in electron-doped high-T_C superconductors, a comparative study of high-quality Pr_{1.85}Ce_{0.15}CuO_4 (PCCO) and Sm_{1.85}Ce_{0.15}CuO_4 (SCCO) thin films is presented. The obtained results confirm a d-wave pairin…
Improvement of the photovoltaic efficiency (from 1.2% to 3%) via exposure of organic poly(3-hexylthiophene) (P3HT) + phenyl-C61-butyric acid methyl ester (PCBM) devices to solvent vapor at room temperature is reported. In situ photoluminescence (PL) and Raman spectroscopies, in conjunction with optical absorption data…
Propeller-shaped molecules diphenyldibenzofulvene ( 1 ) and (4-methoxyphenyl)phenyldibenzofulvene ( 2 ) were nonemissive when dissolved in good solvents but became luminescent when aggregated in poor solvents or in the solid state, showing a novel phenomenon of aggregation-induced emission (AIE). 8-Phenylbenzo[ e ]ace…
The micelle of an ABC triblock copolymer having a core−shell−corona architecture was used as a template for the fabrication of a hollow silica nanosphere. Silica was deposited on a poly(styrene- b -2-vinyl pyridine- b -ethylene oxide) (PS−PVP−PEO) micelle by the sol−gel method. At pH 4, the PVP block of the PS−PVP−PEO…
The biosynthesis of silver nanoparticles has been successfully conducted using Plectonema boryanum UTEX 485, a filamentous cyanobacterium, reacted with aqueous AgNO3 solutions (approximately 560 mg/L Ag) at 25-100 degrees C for up to 28 days. The interaction of cyanobacteria with aqueous AgNO3 promoted the precipitati…
BACKGROUND: Collagen is a well-established and important biomaterial that could be used to help meet significant medical needs for various soft-tissue replacements. Many efforts to create engineered soft-tissue constructs by seeding cells within collagen gels have been hampered because constituent cells contract colla…
The electronic structure of porous silicon (PS) has been characterized by optical reflectance spectra analyses. Using a Cary-500 spectrometer, the reflectance spectra of PS are measured in the photon energy range of 0.4-6 eV. The spectral responses of optical constants are calculated for PS and Si by Kramers-Kronig an…
Elongated CdSe nanocrystals (nanorods) coated with long phosphonate ligands are deposited by pulse valve injection under ultrahigh vacuum on atomically clean surfaces. The alignment of individual CdSe nanorods is observed on the $\mathrm{Si}(100)\text{\ensuremath{-}}2\ifmmode\times\else\texttimes\fi{}1:\mathrm{H}$ sur…
In this work, a series of MoO 3 /TiO 2 −SiO 2 catalysts were tested in the transesterification of dimethyl oxalate (DMO) with phenol to produce methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO). The evaluation results showed that MoO 3 /TiO 2 −SiO 2 catalysts were more active and selective than both MoO 3 /SiO 2…
Abstract The bromine addition to the SBR double bonds in chloroform at 0°C has been investigated by FTIR, 1 H NMR and DSC techniques. In this case, bromine molecules react exclusively with the polydiene double bonds and the polystyrene units are unaffected. The bromine reacts preferentially with 1,4‐trans double bonds…
Racemic 1-phenylethylamine was optically resolved by its own derivative formed with glutaric acid namely (+)-(R)-N-(1-phenylethyl)glutaramic acid. The amide acid resolving agent was synthesized from (+)-(R)-1-phenylethylamine by N-derivatization. The glutaric acid derivative was the next in a homologous series of dica…
Utilizing a combination of the in situ magneto-optical Kerr effect and scanning tunneling microscopy and spectroscopy measurements, we show that the (100) surface of the B2 bulk paramagnetic CoAl is an excellent representation of a two-dimensional ferromagnet. The order-parameter critical exponent beta=0.22+/-0.02 is…
Dynamic in situ spectroscopic ellipsometry studies of poly(vinyl alcohol)−poly(acrylic acid) (PVA−PAA) composite films are presented. Thin films immobilized on glass substrates were conditioned over time in aqueous media. Dynamic measurements consisted of thickness (swelling ratio) and optical constant changes in time…
Kleines Molekül, große Strukturen: Das Verknüpfen zweier zwitterionischer Bindungsmotive mit einem lipophilen Alkyllinker liefert ein amphiphiles Bis-Zwitterion, das sich sogar in polaren Lösungen zu Vesikeln organisiert. Die Daten sprechen dafür, dass zwei Bis-Zwitterionen dimerisieren und anschließend, vermutlich au…
Abstract Silica xerogels containing Sm 3+ ions and SnO 2 nanocrystals were prepared in a sol–gel process. The image of transmission electron microscopy (TEM) shows that the SnO 2 nanocrystals are dispersed in the silica matrix. The X-ray diffraction (XRD) of the sample confirms the tetragonal phase of SnO 2 . The xero…
Eu-doped nanocrystalline Lu 2 O 3 with different particle sizes was prepared by combustion synthesis. The local structures around the rare-earth Lu and Eu ions were studied by using both Lu and Eu L 3 edge X-ray absorption spectroscopy. According to the extended X-ray absorption fine structure (EXAFS) analysis, detail…