Materials Literature
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Abstract The extensive initial loss of efficiency of antioxidant [4,4′‐thiobis(3‐methyl‐6‐tertbutylphenol)], during hydrostatic pressure testing of medium density polyethylene pipes at 95 and 105°C has been studied. Samples from the pressure‐tested pipes were subsequently investigated by scanning electron microscopy a…
We have studied the influence of halide and halate ions on the enhancement factors of surface-enhanced Raman scattering (SERS) in the near-infrared (NIR) wavelength region. It was found that not only an electromagnetic enhancement mechanism but also a chemical enhancement mechanism contributes to the total surface enh…
The density of the low-rate (<0.1 nm/s) sputtered molybdenum films can be controlled between 48% and 96% of the bulk material by the variation of argon pressure from 4.7 to 0.45 Pa. Small angle x-ray scattering shows the existence of columnar voids with a typical size of 10 nm, especially in the low-density fil…
Abstract The effect of heat treatments on the swelling, dispersion, particle charge and particle aggregation of Li-, Na-, K-, Mg-, Ca- and Al-Wyoming bentonite was investigated. Before thermal treatment, unheated (25 °C) Li-, Na- and K-clays showed increased d 001 spacing on glycerol solvation and dispersed spontaneou…
Abstract The geometry of threading dislocations (TDs), non‐equilibrium defects that are generated as a result of stress relaxation in thin films, is considered in order to provide a basis for their reduction behavior during heteroepitaxial growth. This paper, the first of a two‐part series, discusses the geometric pos…
Abstract In aqueous media substituted protoporphyrins and amphiphilic tetraphenylporphyrins aggregate to fibers, tubules, helical ribbons and sheets. Six different types are presented, characterized by the excitonic shifts in the electronic absorption spectra. On excitation, the aggregates from octopusporphyrin show f…
Discomfort results when sweat accumulates on the skin. The sorption of water vapor by hygroscopic clothing near the skin and its release when the clothing moves away from the body can enhance sweat removal. Such a process depends on the relative humidity being higher near the skin than in the ambient atmosphere, and m…
Gypsum and halite are the most common salts in reg soils developed on alluvial parent material under extremely arid conditions in the Negev Desert, Israel. The aim of this paper is to document the changes in the micromorphology of these salts at different stages of Reg soil development on two alluvial fan chronosequen…
Tension‐tension cyclic‐fatigue tests of a two‐dimensional‐woven‐SiC‐fiber‐SiC‐matrix composite (SiC/SiC) prepared by chemical vapor infiltration (CVI) were conducted in air at room temperature and in argon at 1000°C. The cyclic‐fatigue limit (10 7 cycles) at room temperature was ∼160 MPa, which was ∼80% of the monoton…
X-ray structure determination and pyroelectric and piezoelectric measurements have been carried out on mesogenic mixtures composed of achiral side chain polymers and their monomers. Certain mixtures show antiferroelectric polarization hysteresis loops in the mesophase which was shown to be a bilayered smectic C, while…
The Field Induced Spin Density Waves (FISDWs) found in organic conductors represent a unique series of transitions which meld the one-dimensional physics of the Peierls instability with the two-dimensional physics of the Quantum Hall Effect. This paper presents a pedagogical introduction to the FISDW's in the Bechgaar…
The dielectric properties of nematic liquid crystal (4-cyano-4′-n-pentylbiphenyl: 5CB) cells in the ultralow frequency regime was investigated. A dielectric relaxation, whose relaxation time is 160 s, is observed at 303 K, and the dielectric relaxation is found to be independent of applied electric field. It is shown…
It is confirmed that the calculation of the demagnetizing field in micromagnetic simulations can be accelerated significantly by using the discrete convolution theorem and the fast Fourier transform (FFT). When the magnetization distribution is periodic, application of the theorem to the demagnetizing field calculatio…
X-ray photoemission measurements of the core levels and valence electronic structure of LaCo${\mathrm{O}}_{3}$ and ${\mathrm{La}}_{0.5}$${\mathrm{Ca}}_{0.5}$Co${\mathrm{O}}_{3}$ high quality epitaxial films are presented. Shifts of the core levels and main valence band features are consistent with a doping-induced cha…
The morphologies of thin, substrate-free block copolymer films have been examined by cross-sectional TEM. Two poly(styrene-b-butadiene) diblock copolymers were studied: one that forms PS cylinders and the other that forms PB cylinders in the bulk. Films were annealed while supported by metal TEM grids, embedded, and u…
Abstract A new class of amphiphilic macromolecules has successfully been synthesized by creating well‐defined diblock copolymers of polystyrene (PS, M n 3.2 × 10 3 , M w / M n =1.04) with poly‐(propylene imine) dendrimers. A poly‐styrene core molecule with a primary amine end‐group was prepared by a quantitative thre…
The results of Rietveld refinements using synchrotron X-ray powder diffraction data collected in transmission mode with a new flat imaging-plate (IP) technique agree with those obtained from other techniques, m-ZrO2 was chosen as test compound because it was the standard selected by the Commission on Powder Diffractio…
A series of novel, unsymmetrically substituted metallo-phthalocyanines was synthesized, along with their symmetrically substituted analogs, and the effects of structure and metal substitution on their photophysical and photoredox properties were investigated. The macrocycles were synthesized using a mixed-condensation…
The electrical resistivity of polymer composites is studied as a function of temperature. The initial resistivity ρ of thermoplastic or thermoset containing a metallic filler is in the range of 1–10×10−2 Ω cm. Around the curing temperature of epoxies, the resistivity increases by eight to twelve orders of magnitude. F…
The mechanical behavior of reaction‐sintered alumina: 30 vol% calcium hexaluminate (Al 2 O 3 :CaAl 12 O 19, or A1 2 O 3 : CA 6 ) composites was evaluated using the indentation strength in bending technique. A composite in which the hexaluminate (CA 6 ) phase possessed a platelike morphology showed more‐pronounced R ‐c…