Materials Literature
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Abstract The morphology of a number of polyamides (PA)—namely, PA‐66, PA‐6/PA‐66 blends, and PA‐6/PA‐66 copolymers—prepared from HCOOH solution and from the melt has been examined as well as the effect of annealing. In the blends, the PA‐6 crystallizes within the PA‐66 spherulites. When prepared from HCOOH solution at…
We report on measurements of the thermal conductivity of the quasi-one-dimensional conductor (${\mathrm{NbSe}}_{4}$${)}_{10}$${\mathrm{I}}_{3}$ between 80 and 320 K. We show that the thermal conductivity exhibits a well-defined minimum below the Peierls transition temperature ${\mathit{T}}_{\mathit{p}}$=285 K. Such be…
Dynamic pore collapse in porous materials is studied by analyzing the finite deformation of an elastic/viscoplastic spherical shell under impulsive pressure loading. Effects of dynamic loading rate, pore size, initial porosity, strain-rate sensitivity, strain hardening, thermal softening, and mass density of the matri…
Rhombohedral forms of layered boron nitride (r-BN) as mixtures with copper powders were shock compressed and quenched from pressures in the range 8–50 GPa. Recovered specimens were investigated by x-ray diffraction and electron microscopy. The graphite-like BN (h-BN) and turbostratic BN (t-BN) phases are observed in t…
Measurements are reported for the electrical conductivity of different compositions of silicate glasses containing copper and vanadium in the temperature range 200--500 K. The experimental results for the two systems are found to be very similar and are analyzed with respect to theoretical models existing in the liter…
Abstract The effect of the ethylene–methylacrylate copolymer as a chemical compatibilizer in the 50:50 blend of low‐density polyethylene (LDPE) and polydimethylsiloxane rubber (PDMS) has been studied in detail. Ethylene–methylacrylate (EMA) reacted with PDMS rubber during melt‐mixing at 180°C to form EMA‐grafted PDMS…
A convenient experimental method for determining the relative angular distribution of photoemission from solid materials has been proposed. Experiments were simultaneously simulated with the Monte Carlo model describing realistic photoelectron transport in solids. It has been proved that a major part of the observed d…
Abstract In polymer blends, the crystallization of the dispersed semicrystalline component depends on the type and distribution of the nucleating heterogeneities and on the level of the dispersion. Either fractionated or coincident crystallization may result. In this study, the effect of compatibilizers on the crystal…
A semiempirical molecular-dynamic density-functional approach is used to perform a systematic investigation of the stability, structure, and properties of quenched pure and hydrogenated amorphous carbon dependent on the mass density and the hydrogen concentration. By comparing the total structure energies for supercel…
We present a photoluminescence study of the free-exciton singlet and triplet ground states in GaTe as a function of temperature from 5 to 40 K. Over the range 5--25 K, the temperature variation of excitonic-emission line width and peak energy comes mainly from exciton--acoustic-phonon interactions via the deformation…
The photoluminescence and optical absorption properties of Zn-doped GaS crystals prepared by the iodine vapor transport method are reported. Undoped GaS crystals are also used for comparison. Zn substituted for a Ga site acts as an acceptor having a deep energy level and forms a complex with the iodine coactivator, wh…
A method of graphically representing complex dielectric data is described, which is particularly useful for situations where the Cole–Cole representation is unsuitable. The representation emphasizes the orientational dipolar contribution to the conductivity by plotting σχ″=ωεv(ε′−ε∞) vs σχ′=ωεvε″. We discuss the utili…
Measurements are reported on the electrical resistivity \ensuremath{\rho}(T) along the c axis of a single crystal of ${\mathrm{VO}}_{2}$, from the metal-insulator transition at T=333 K up to 840 K. The temperature dependence is very linear, and a fit to Bloch-Gr\"uneisen theory gives a residual resistivity ${\mathrm{\…
Stresses were measured in 〈111〉-textured Ag/Ni multilayered thin films from the substrate curvature and from lattice parameter measurements by x-ray diffraction. The difference between the total multilayer film stress and the layer deposition stresses can be attributed to a tensile interface stress of −2.27±0.67 J/m2.…
We present data concerning the dynamics of photoexcitation of defect centers in germanium-doped silica glass optical fibers and fiber preforms. It is shown that two-photon absorption of mode-locked and Q-switched light at 527 nm results in partial ionization of the germanium oxygen deficiency center (GODC) 400-nm lumi…
We report strong visible photoluminescence (PL) at room temperature from oxidized Si nanometer-sized spheres with a spherical crystalline Si (c-Si) core and an amorphous ${\mathrm{SiO}}_{2}$ (a-${\mathrm{SiO}}_{2}$) surface layer. The peak energy of the broad PL spectrum is about 1.65 eV, which is independent of the c…
Helically coiled forms of the carbon cage on the nanometer scale are theoretically proposed. The optimized surface construction for different types of helically coiled structures consisting of sevenfold, sixfold, and fivefold rings of carbon atoms is given. The thermal stability of various helical structures is studie…
Stealth liposomes have recently emerged as a promising antitumor drug delivery system, yet no studies have been reported to examine their dynamic behavior at the microcirculatory level. In this investigation, we have used in vivo fluorescence videomicroscopy to study the decay in plasma concentration and the interstit…
Abstract Various nylon 6‐clay hybrids, such as molecular composites of nylon 6 and silicate layers of montmorillonite and saponite, NCHs and NCHPs, respectively, have been synthesized. Sorption of water in those hybrids was measured to estimate the resistance to water permeation. The diffusion coefficient D and the pa…
A highly tetrahedrally bonded form on nonhydrogenated amorphous carbon (a-C) is produced by deposition from filtered medium-energy ion beams. A range of such films was grown and the ${\mathit{sp}}^{3}$-bonded fractions, plasmon energies, compressive stresses, and resistivities were measured as a function of ion energy…