Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
ε-Caprolactone was polymerized in bulk at 80°C with 2,2-dibutyl-2-stanna-1,3-dioxepane (DSDOP) as initiator. The reaction time was varied for monomer/initiator molar ratios of 20, 100 and 500. A rapid and complete conversion of the monomer and only slight transesterification or back-biting degradation were found after…
The optical properties of silicon nanocrystallites of known sizes, present in supercritically dried porous silicon films of porosities as high as 92%, have been measured by a variety of techniques. The bandgap and luminescence energies have been measured as a function of size for the first time. The bandgap increases…
WS2 microtubes, ribbons, and ropes are some of the unusual forms of inorganic crystals – grown by a chemical transport reaction – for which evidence is presented here. The Figure shows a WS2 rope composed of four nanotubes with one nanotube periodically wound around the widest tube. A further example, of two nanotubes…
A new chlorosulfonylated tetradentate beta-diketone, 4,4'-bis(1",1",1",2",2",3",3"-heptafluoro-4",6"-hexanedion-6 "-yl) chlorosulfo-o-terphenyl (BHHCT), was synthesized as a chelating label for Eu3+. BHHCT can be covalently bound to proteins under mild conditions and forms a strongly fluorescent chelate with Eu3+. Bov…
The shape fixity and recovery in a film of shape memory polymer of polyurethane series were investigated by the thermomechanical cycling tests with loading at various temperatures. The results are summarized as follows: (1) Strain is recovered at temperatures in the vicinity of the glass transition temperature Tg for…
We have investigated the unreconstructed (0001) surface structure of sapphire (α- Al 2 O 3 ) by grazing incidence X-ray scattering. Modulations along the crystal truncation rods were analyzed in order to determine the chemical nature of the terminating plane, and the structural relaxations of the first few atomic plan…
This paper constitutes a review of the control of toxic metal emissions using sorbents. The objective of sorbent-injection methods is to effectively capture the metal species (preferably transform it to an environmentally benign form) and to suppress the fraction in the submicrometer mode. The design of an effective s…
Single-molecule Raman spectroscopy of a cyanine dye in aqueous silver colloidal solution with the use of surface-enhanced Raman scattering at near-infrared excitation (NIR-SERS) is reported. A characteristic Poisson distribution of SERS signals due to the Brownian motion of single dye molecule-loaded silver particles…
The hot electron dynamics in 11±2 nm diameter Au particles has been examined by transient absorption and bleach recovery measurements. These experiments show that the timescale for energy relaxation by electron–phonon coupling decreases as the pump laser power decreases, and that the relaxation time is independent of…
The structural state of dendritic macromolecules at air–water (Langmuir monolayers) and air–solid (adsorbed monolayers, self-assembled films, and cast films) interfaces is discussed. Examples of undistorted and compressed dendritic macromolecules within monolayers and multilayer films are presented. The high interacti…
Sr 3 Al 2 O 6 , SrAl 2 O 4 , SrAl 4 O 7 , and SrAl 12 O 19 that have been doped with Eu 2+ and Dy 3+ ions have been grown by a floating‐zone technique for application as long‐duration phosphors. Long‐duration phosphorescence with a variety of colors has been observed in SrA l2 O 4 , SrAl 4 O 7 , and SrAl 12 O 19 cryst…
Solid oxide fuel cells that contain mixed ionic‐electronic conductors (MIECs) as electrolytes exhibit maximum efficiency at high ionic current density due to a small electronic leakage current. At low ionic current density the electronic current increases due to partial reduction of the electrolyte and efficiency decr…
The structural properties of ${\mathrm{Pr}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ were studied by x-ray synchrotron and neutron-powder diffraction as a function of temperature $(15<T<300$ K), and as a function of x-ray fluence at 15 and 20 K. The temperature evolution of the lattice parameters and of the s…
Uniform spherical powders of Ce 0.9 Gd 0.1 O 1.95 with an average diameter of 250 nm were obtained at 700°C from a sol‐gel process of mixing nitrates and ethylene glycol. Broadening of the X‐ray peaks of the fluorite structure reveals a small crystallite size within the powders. Sintering in air of pressed pellets of…
Guymont's (Phys. Rev. B (1981), 24, 2647) nondisruption condition is made the basis for dividing phase transitions in crystals into nondisruptive and disruptive categories. Ferroic phase transitions are defined as nondisruptive phase transitions involving a change of point-group symmetry. Prototype symmetry is also de…
We have studied the thermodynamics of isolated homopolymer chains of varying stiffness using a lattice model. A complex phase behaviour is found; phases include chain-folded “crystalline” structures, the disordered globule and the coil. It is found, in agreement with recent theoretical calculations, that the temperatu…
Precise X-ray and high-energy transmission electron diffraction methods were used for the study of electron density and electrostatic potential in MgO crystals. The structure amplitudes were determined and their accuracy estimated using ab initio Hartree–Fock structure amplitudes as criteria. The electrostatic potenti…
Elastic moduli and refractive index of diamond, in the temperature range 300--1600 K, are determined using Brillouin scattering. The elastic moduli decrease by only $\ensuremath{\approx}8%$ up to 1600 K, indicating that diamond retains its reputed hardness even at high temperatures. We review the most commonly employe…
Abstract The reactive extrusion of polylactide (PLA) with a free radical initiator resulting in a branched polymer was accomplished. Reaction conditions were in the range of 160°C to 200°C with an initiator concentration between 0.0 and 0.5%. Triple detector size exclusion chromatography, melt flow index, thermal grav…
An immunological analysis of an Escherichia coli strain unable to synthesize the main pyruvate formate-lyase enzyme Pfl revealed the existence of a weak, cross-reacting 85 kDa polypeptide that exhibited the characteristic oxygen-dependent fragmentation typical of a glycyl radical enzyme. Polypeptide fragmentation of t…