Materials Literature
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X-ray diffraction data at atomic resolution to 0.98 A with 136 380 observed unique reflections were collected using a high quality proteinase K crystals grown under microgravity conditions and cryocooled. The structure has been refined anisotropically with REFMAC and SHELX-97 with R-factors of 11.4 and 12.8%, and R(fr…
Tetraaryloxy-substituted perylene tetracarboxylic acid bisimides with one or two 4-pyridyl receptor substituents at the imide functionality were synthesized and employed in transition metal directed self-assembly with Pd(II) and Pt(II) phosphane triflates. Upon mixing of the components, quantitative formation of funct…
We survey recent work on designing and evaluating quantum computing implementations based on nuclear or bound-electron spins in semiconductor heterostructures at low temperatures and in high magnetic fields. General overview is followed by a summary of results of our theoretical calculations of decoherence time scales…
Twenty-three triboluminescent organic and inorganic materials were examined for crystal symmetry, differences between photoluminescence and triboluminescence emission spectra, spectroscopic evidence of an electrical discharge, and persistence of activity under liquids; some were also tested under other atmospheres. Th…
The optical properties and electronic structure of a homologous series of CdSe cluster molecules covering a size range between 0.7 and 2 nm are investigated. CdSe cluster molecules with 4, 8 10, 17, and 32 Cd atoms, capped by selenophenol ligands, were crystallized from solution and their structures determined by sing…
Thermogravimetric analysis (TGA) simultaneously coupled with mass spectrometry (MS) and Fourier transform infrared spectrometry (FTIR) was developed as an original technique to study the thermal modification/degradation of poly(epsilon-caprolactone) (PCL) through in depth analysis of the evolved gas. Perfectly well-de…
Carbon nanotubes were discovered soon after the successful laboratory synthesis of fullerenes. Since their discovery in 1991, there has been intensive research activity in the area of carbon nanotubes, not only because of their fascinating structural features and properties, but also because of their potential technol…
The photoinduced surface wettability conversion reactions of ZnO and TiO 2 thin films were investigated by means of water contact angle measurement and X-ray photoelectron spectroscopy. Before ultraviolet (UV) illumination, ZnO and TiO 2 films exhibited water contact angles of ∼109 and ∼54°, respectively. UV illuminat…
The effect of Mn substitution for Co on the structure and magnetic properties of Sm 2 Co 17- x Mn x compounds with x = 0-8 were investigated by means of x-ray diffraction (XRD) and magnetization measurements. XRD patterns show that all samples are single phase with rhombohedral Th 2 Zn 17 -type structure. The substitu…
Monte Carlo simulations of ultrafast electron processes in Ag and Au have been used to analyze transient reflectivity as well as two-photon photoemission experiments. The model consisted of an electron Fermi gas coupled to longitudinal acoustic phonons. A laser pulse of finite width excited the electrons, after which…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTMorphological Changes during the Annealing of Polybutene-1 FiberJoshua M. Samon, Jerold M. Schultz, and Benjamin S. HsiaoView Author Information Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716, and Department of Chemistry, State University of…
We have studied the ac conductivity of several compositions of strontium vanadate semiconducting glasses in the frequency range 10 Hz-2 MHz and in the temperature range 80-450 K. We have analysed the experimental results in the framework of the quantum tunnelling and classical hopping models. We observe that tunnellin…
The objective of this study is to establish a comprehensive set of backscatter factors for mammography based on the exposure model proposed by the European Protocol on Dosimetry in Mammography. The Monte Carlo calculated backscatter factors (BSFs) presented in this study are for various exposure conditions encountered…
A recent rigorous analysis of the broad thermoluminescence (TL) peak of a Brown microcline has shown it to be due to an exponential distribution of traps. Incidentally, from the statistical point of view one expects the traps to follow a Gaussian distribution. In order to elucidate the origin of the exponential trap d…
The effect of impurity on the two-dimensional (2D) nucleation rate, J, was investigated by estimating the edge free energy, γ, on the (0001) face of a hydroxyapatite crystal in the presence of magnesium and zinc as impurities. It was found that edge free energies, γ, at 0.06 mM magnesium and 0.75 μM zinc concentration…
Appreciable oxygen permeability at elevated temperatures (650–850°C) allows the well-known high-temperature superconductor YBa2Cu3O6+δ to be used as an oxygen separation membrane. Permeation of air through a YBa2Cu3O6+δ disk 1.2 mm thick gave an O2 stream in which N2 was barely detectable by gas chromatography. This t…
Constant-pressure molecular dynamics simulations and a systematic analysis of the local atomic structures have been performed to study the structural evolution of aluminium on different cooling runs. The regular and defective icosahedral atomic configurations depend strongly on the cooling rate, which is responsible f…
Mn–O and Mn–Mn interatomic distances were determined in LaxCa1−xMnO3 films grown heteroepitaxially on single crystal SrTiO3 and LaAlO3 substrates by molecular beam epitaxy. Mn–O bond lengths were found to be fixed at ∼1.975 Å for both types of substrates, while the Mn–Mn distance was detected to be larger for films gr…
We report 27 Al and 29 Si Nuclear Magnetic Resonance (NMR) spectra, collected at magnetic fields of 14.1 and 18.8 Tesla on samples as small as 1 mg, for Al‐bearing MgSiO 3 perovskite synthesized at 26–28 GPa. For Al, we find a 1∶1 ratio of two types of sites: a symmetrical, octahedral site and a low symmetry, distorte…
The thermal oxidation of polypropylene was probed, in situ, by a novel technique that simultaneously monitors chemically induced light emission (chemiluminescence) and changes in FTIR emission spectra of an oxidizing sample. The results obtained from this technique demonstrated that the chemiluminescence intensity ( I…