Materials Literature
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Theory suggests that the otherwise rapid folding of simple heteropolymer models becomes "glassy"-dominated by multiple kinetically trapped misfolded states-at low temperatures or when the overall bias toward the native state is reduced relative to the depth of local minima. Experimental observations of nonsingle-expon…
The described study concentrated on the investigation of II-VI semiconductor quantum dots, prepared as colloidal species imbedded in phosphate glass, or chemically deposited on a substrate. The ultimate goal of the present research was concerned with the examination of the influence of the surface/interface quality on…
A family of graft copolymers that can sterically inhibit interactions between biological surfaces was developed. These copolymers contained phenylboronic acid (PBA) groups as saccharide-binding moieties on a poly-(L-lysine) backbone and poly(ethylene glycol) (PEG) grafted as adhesion-resisting side chains. These copol…
We describe two efficient methods of estimating the fluid permeability of standard models of porous media by using the statistics of continuous Brownian motion paths that initiate outside a sample and terminate on contacting the porous sample. The first method associates the "penetration depth" with a specific propert…
Cd2Os2O7 crystallizes in the pyrochlore structure and undergoes a metal-insulator transition (MIT) near 226 K. We have characterized the MIT in Cd2Os2O7 using X-ray diffraction, resistivity at ambient and high pressure, specific heat, magnetization, thermopower, Hall coefficient, and thermal conductivity. Both single…
The crystallization of isotactic poly(4-methylpentene-1) in its stable tetragonal crystal modification based on the 72 helix conformation was achieved on three different low molecular weight organic substrates and on polytetrafluoroethylene. The contact face was always the (100) face, although the details of the epita…
The recently developed macroscopic model of light-induced equilibrium of spin-crossover solids is extended to the case of two equivalent sublattices coupled `antiferromagnetically'. To do this, we use an Ising-like model involving two coupling parameters of opposite signs for the intra- and inter-sublattice interactio…
Delayed hydride cracking (DHC) in Zr-2.5Nb alloy material is of interest to the CANDU (CANada Deuterium Uranium) industry in the context of the potential to initiate DHC at a blunt flaw in a CANDU reactor pressure tube. The material is susceptible to DHC when there is diffusion of hydrogen atoms to the flaw, precipita…
Semi-interpenetrating polymer networks (semi-IPNs) were prepared from linear polyurethane (PUR) and polycyanurate (PCN) networks. Wide-angle X-ray scattering measurements showed that the IPNs were amorphous, and differential scanning calorimetry and small-angle X-ray scattering measurements suggested that they were ma…
Electron emission from bulk Pt/PZT/Pt and RuO2/PZT/RuO2 ferroelectric cathodes is reported. The total emission current (0.8 A) and polarization fatigue are high for ferroelectric cathodes with Pt electrodes, while emission current (0.18 A) and polarization fatigue are significantly lower for cathodes with RuO2 electro…
The nucleation and initial stages of growth of aluminium oxide deposited on two different polymer surfaces [poly(ethylene terephthalate), (PET) and amorphous polypropylene, (PP)] have been studied by atomic force microscopy (AFM). The permeation of water vapor and oxygen through the films has been measured. The initia…
Dissolving-grade wood pulp fibers were partially esterified by mixed p-toluene sulfonic/hexanoic acid anhydride in a nonswelling suspending agent. A biphasic morphology was revealed by atomic force microscopy (AFM) for the compression-molded, partially modified pulp fibers. The AFM phase images indicated distinct peri…
Intermediate scattering functions for density fluctuation in D2O contained in pores of a Vycor glass have been measured using an improved neutron spin-echo spectrometer at two supercooled temperatures. The measurements cover the time range from 1 to 2300 ps with the Q range spanning the first diffraction peak of water…
We have studied the magnetic and magnetotransport properties of the perovskite LaMn1−xCuxO3 (x⩽0.3). All of these compounds show ferromagnetism and cluster glass behavior at low temperatures. Though no metallic-insulating transition associated with the ferromagnetic–paramagnetic transition appears, a large magnetoresi…
A general solution of the elastic fields in 1D hexagonal quasicrystals with point groups 6 mm , 62 h 2 h , m 2 h and 6/ m h mm is given in terms of four `harmonic' functions F i ( i = 1,2,3,4). Then we consider the problem of a circular crack embedded in an infinite 1D hexagonal quasicrystal of point group 6 mm . The…
INTRODUCTION In most textbooks, biofilm formation on surfaces has been depicted as a sequence of events. Depending on the particular interest of the author, these events are split up into four or more steps (Escher & Characklis, 1990; Van Loosdrecht et al. , 1990). The sequence is presented in Fig. 1. Traditionally, b…
We study numerically the one dimensional ferromagnetic Kondo lattice, a model widely used to describe nickel and manganese perovskites. By including a nearest-neighbor Coulomb interaction ( V) and a superexchange interaction between the localized moments ( K), we obtain the phase diagram in parameter space for several…
The transition in diamond crystal morphology from well-faceted microcrystalline to nanocrystalline phases as a function of increasing argon (Ar) concentration has been studied in a hot-filament chemical vapor deposition (HFCVD) system. The range of Ar concentration in a Ar–methane–hydrogen mixture that permits well-fa…
The quantitation of long-chain branching (LCB) and short-chain branching (SCB) in polyethylene (PE) was accomplished with a combination of carbon nuclear magnetic resonance (13C NMR) spectroscopy and size exclusion chromatography (SEC) with universal calibration. We demonstrate how the spectroscopic and chromatographi…
A ferroelectric superlattice with an antiferroelectric interfacial coupling is considered; the same model describes a bilayer with antiferroelectric coupling. By mapping minimum points in the Landau free energy expression and plotting them against the applied electric field, a triple hysteresis loop pattern is obtaine…