Materials Literature
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We have investigated the electron density profiles normal to the substrate of 20−80 nm thick films of stereoregular poly(methyl methacrylate) (PMMA) spin-cast on silicon wafers by X-ray reflectometry. The reflectivity curves were analyzed using a least-squares procedure based on the distorted-wave Born approximation t…
Abstract The electrical and mechanical behaviors of carbon black‐filled. Poly(vinyl acetate) latex‐based polymer composites were examined. These composites were found to exhibit percolation thresholds in electrical conductivity near 2 vol% carbon black due to their segregated microstructures. Storage modulus and ultim…
Dielectric properties and phase formation of Bi‐based pyrochlore ceramics were evaluated for the Bi 2 O 3 –ZnO–Ta 2 O 5 system. The compositional range r Bi 2 (Zn 1/3 Ta 2/3 ) 2 O 7 · (1− r )(Bi 3/2 Zn 1/2 )(Zn 1/2 Ta 3/2 )O 7 (0 ≤ r ≤ 1) in Bi 2 O 3 –ZnO–Ta 2 O 5 was investigated to determine the relative solubility…
High resolution electron energy loss spectroscopy (HREELS), low-energy electron diffraction (LEED), and thermal desorption spectroscopy (TDS) were used to study lateral interactions in the adsorbate layer of the CO/Rh(111) system. The vibrational spectra show that CO adsorbs exclusively on top at low coverage. At abou…
A sensor of thick film NiO doped with alkali ions was fabricated and coated with Pt as the catalyst on half of its surface. When this sensor was exposed to air mixed with hydrogen gas, the catalytic reaction heated up the Pt-coated surface, and then thermoelectric voltage appeared across the hot and cold region of the…
Partially wetting water droplets with sizes smaller than the capillary length acquire a distinct spherical cap shape controlled by the equilibrium contact angle, which is specific for different substrates and conditions. Images of such droplets in an environmental scanning electron microscope (ESEM) show strong topogr…
Abstract Silica-filled polydimethylsiloxane networks are submitted to successive stretching cycles, in order to get the stabilized stretching curve, at variable temperature. This study explains the peculiar temperature dependence of the first stretching curve of filled rubbers, and highlights the molecular origin of t…
Electron diffraction via the transmission electron microscope is a powerful method for characterizing the structure of materials, including perfect crystals and defect structures. The advantages of electron diffraction over other methods, e.g., x-ray or neutron, arise from the extremely short wavelength (≈2 pm), the s…
Carbon multiwall nanotubes (MWNTs) can be used for separation processes if the mechanisms for sorption and desorption are known. This study describes the sorption mechanism for butane on MWNTs at room temperature and relative pressures ranging from 0 to 0.9. Previous workers have studied the sorption of hydrogen, 1-3…
Abstract Sequential poly(ester amide)s derived from glycine were synthesized by a two‐step method, involving a final thermal polyesterification. Molecular weights were in general higher than those obtained with the previously reported synthesis on the basis of interfacial polyamidation. Polymers with stiff units like…
Three kinds of bismuth-layer-structured ferroelectric (BLSF) ceramics, CaBi 4 Ti 4 O 15 (CBT), Ca 0.8 (CeNa) 0.1 Bi 4 Ti 4 O 15 (CNBT), and Na-deficient Ca 0.8 (Ce 0.1 Na 0.05 \Box 0.05 )Bi 4 Ti 4 O 15 [CN\BoxBT] (where \Box represents vacancies) were prepared by a conventional ceramic technique. X-ray powder diffract…
The crystallization behavior and structure of polyamide 6 (PA6) nanocomposites containing 3 wt.-% montmorillonite (MMT) were investigated for different cooling conditions using differential scanning calorimetry and X-ray diffraction. In sharp contrast to PA6 and other semicrystalline polymers, increased cooling rates…
The conductivity and structure of 8‐mol%‐yttria‐stabilized zirconia with additions of nickel oxide has been investigated, both in the as‐prepared state and after reduction of NiO in hydrogen. During reduction at 1000°C, the conductivity decreases by 40%–50% and most of the NiO dissolved in the zirconia is exsolved in…
Plastic instability associated with formation of narrow flow channels results from dislocation pinning–unpinning by defect clusters. We investigate the dynamics of dislocation interaction with radiation-induced defect clusters, and specifically with, firstly, sessile self-interstitial atom clusters in dislocation deco…
Refractive index (RI) measurements, depolarized collision-induced light (CILS) scattering and ab initio quantum chemical calculations are used to determine the dipole (α), dipole–quadrupole (A), and dipole–octopole polarizability (E) of adamantane, C10H16. For this molecule of symmetry group Td the three polarizabilit…
Huge second harmonic generation (SHG) activityis displayed by the new hybrid inorganic–organic material [DAMS*][Cu5I6] (see Figure). Ab-initio XRPD structure determination explains this through the presence of cationic guest J-aggregates between Cu-defective anionic host CuI slabs. Thermal stability and thin-film suit…
A new icosahedral quasicrystal has been found in Zn 85-x Mg x Sc 15 ( x = 3,4,5) alloys annealed at 922K for 5-100h. Electron diffraction and powder X-ray diffraction experiments indicate that this quasicrystal has a primitive icosahedral quasilattice (P type) and a six-dimensional lattice parameter a 6D =0.7115nm. Th…
The luminescence of lanthanide(III) ions emitting in the near-infrared region is ideally suited for telecommunications applications, and a number of applications have been developed. These are in general based on inorganic matrices, but polymer-based matrices would have advantages in device fabrication. In organic mat…
Abstract When CO 2 dissolves into a polypropylene (PP), its crystallization kinetics changes These changes were studied, in the expectation that the information would reflect on the behavior of other semicrystalline polyolefins. The isothermal crystallizatior rate of the PP‐CO 2 solutions was measured using a high‐pre…
Medium-chain-length polyhydroxyalkanoates (PHAs) are polyesters having properties of biodegradable thermoplastics and elastomers that are naturally produced by a variety of pseudomonads. Saccharomyces cerevisiae was transformed with the Pseudomonas aeruginosa PHAC1 synthase modified for peroxisome targeting by the add…