Materials Literature
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The early stages of thermal oxidation of the basal plane of highly oriented graphite (HOPG) have been investigated in ozonized air. Scanning tunneling microscopy (STM) was employed to determine the surface topography on the nanometer scale. At temperatures within the range 300−500 °C and at O 3 concentrations below 1…
The interaction of ethyne with vacuum-dehydrated CuNaY zeolite has been investigated by means of Fourier transform infrared spectroscopy and cluster model density functional theory calculations. The spectra show three bands: two which are symmetry-forbidden for the free molecule but become allowed in the adsorbed stat…
The chemical composition of lipids from bast fibers of flax (Linum usitatissimum), which are commonly used for high-quality paper pulp production, was thoroughly studied by gas chromatography-mass spectrometry. The main compounds identified were waxes, series of long chain n-fatty alcohols, n-aldehydes, n-fatty acids,…
A high-speed camera was used to observe the motion of the three-phase contact (TPC) line for a small rising bubble ruptured by a submerged horizontal glass plate. The experimental data for the radial position of the TPC line as a function of time were used to examine both hydrodynamic and molecular-kinetic models prev…
Barium hexaferrite was synthesized by chemical co-precipitation. Its Mössbauer spectra were obtained. A semi-empirical model, based on the Phillips theory of bonding, has been developed for quantitative explanation of the Mössbauer isomer shifts of Fe ions in BaFe 12 O 19 crystals. The results show that, using the rel…
Three series of nanocrystalline powders of Lu 2 O 3 :Eu with Eu concentration varying from 0.05 to 13% were prepared. All specimens were obtained through combustion synthesis using urea or glycine as the fuel. The powders of the first series consisted of materials with crystallites about 13 nm in size and were prepare…
Bacterial receiver domains mediate the cellular response to environmental changes through conformational changes induced by phosphorylation of a conserved aspartate residue. While the structures of several activated receiver domains have recently been determined, there is substantial variation in the conformational ch…
With their interesting electrical, structural, and physical properties, carbon nanotubes (CNTs) are envisioned to impact future nanoelectronics, nanosensors, and nanophotonics. Current research and development efforts in the growth of CNTs rely on the time-consuming one-parameter-at-a-time approach, whereby marginal v…
CaWO 4 phosphor films doped with rare-earth ions (Eu 3+ , Dy 3+ , Sm 3+ , Er 3+ ) were prepared by the Pechini sol–gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis, atomic force microscopy, and photoluminescence spectra, as well as lifet…
The perovskite La 1/3 Sr 2/3 FeO 3−δ was investigated by neutron diffraction, magnetic and Mössbauer spectroscopy measurements. La 1/3 Sr 2/3 FeO 3−δ undergoes magnetic ordering at T = 190–200 K accompanied by charge disproportionation. Magnetic peaks due to charge ordering are observed below 200 K. The charge orderin…
Recent studies of zirconium tungstate, ${\mathrm{ZrW}}_{2}{\mathrm{O}}_{8},$ show an isotropic negative thermal expansion (NTE) over a wide temperature range. It has been proposed that the low-energy phonon vibrational modes, observed in both specific heat and phonon density-of-states measurements, are responsible for…
We report, in this letter, a simple thermal oxidation approach to growing large-scale arrays of aligned tungsten oxide nanorods on planar substrates. By passing a current of ∼50 A through a tungsten spiral coil in a vacuum of ∼3 × 10 −2 Torr, single-crystalline WO 2.9 nanorods, ∼20 nm in diameter and ∼400 nm long, wer…
We report on the nucleation and growth of tetracene in a thin liquid film which is continuously supersaturated by vapor deposition of molecules onto the film. In a first stage, nucleation and fast anisotropic two-dimensional dendritic growth occurs. In a second stage, the dendrites coarsen into pallet-shaped crystals.…
In this work, we investigated the mechanism involved in the photoinitiated cross-linking of the polyester poly(propylene fumarate) (PPF) using the initiator bis(2,4,6-trimethylbenzoyl) phenylphosphine oxide (BAPO). It was hypothesized that BAPO has the ability to cross-link PPF into solid polymer networks, without the…
This Communication reports a low-temperature diamond synthesis technique, in which diamonds (10-250 mum) can form at a temperature as low as 440 degrees C by reduction of dense CO2 with metallic Na. The X-ray diffraction pattern of a powder sample shows three reflection peaks, indexed with 111, 220, and 311, correspon…
Traditional pictures of optical properties in phenylacetylene dendrimers view the molecule as a collection of independent chromophores, linked by meta-substitution at the central phenyl ring. While this picture is reasonable for explaining the observed absorption trends, it breaks down in describing the emission behav…
We establish a strict correlation between the total photoelectron yield spectra and the surface conductivity of hydrogenated diamond. The decomposition of the yield spectra into electron and exciton derived contributions requires an upward surface band bending to accompany surface conductivity, while an essentially fl…
Fluorescent colloidal particles, fabricated by depositing a thin gold film on one side of the particle, show intensity fluctuation (blinking) under an optical microscope because of their rotational Brownian motion. Interactions between molecules immobilized on the surfaces of the particle and the solid substrate restr…
Medical ultrasound is a highly valuable diagnostic tool, especially when compared with other imaging modalities. It is a noninvasive, real-time, portable, extremely safe method compared with X-ray and inexpensive relative to magnetic resonance imaging. However, ultrasound is limited in its ability to distinguish betwe…
Collagen is the most abundant protein in animals. Natural collagen consists of a triple helix of (Xaa-Yaa-Gly)n chains, in which the Xaa and Yaa residues are often l-proline. Here, a (2S,4S)-4-fluoroproline (flp) residue is shown to be greatly stabilizing in the Xaa position (but destabilizing in the Yaa position). In…