Materials Literature
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A series of novel azo polyelectrolytes have been synthesized based on an extremely reactive precursor polymer, poly(acryloyl chloride) (PAC), prepared from acryloyl chloride by radical polymerization. The precursor polymer was post-functionalized by the Schotten-Baumann reaction of PAC and several aromatic azo reactan…
We introduce a first-principles scheme for calculating a core-hole potential for core-electron excitations. The scheme incorporates atomic and solid-state screening in the description of core excitations in several materials. We compare the results calculated using our scheme to experimental x-ray absorption and inela…
Abstract A series of terpolymers were synthesized by the chemical oxidative polymerization of m ‐phenylenediamine (MPD), o ‐anisidine (AS), and 2,3‐xylidine (XY) in hydrochloride aqueous medium. The yield, intrinsic viscosity, and solubility of the terpolymers were studied by changing the MPD/AS/XY molar ratio from 10…
Crowded solutions of densely branched polymers with starlike architecture undergo a reversible gelation upon heating. This phenomenon is characterized by slow kinetics and is attributed to the formation of clusters causing a partial dynamic arrest of the swollen interpenetrating spheres at high temperatures. A kinetic…
The crystallization, dissolution, and associated pseudo-polymorphic behavior of citric acid crystals from aqueous solution is investigated using temperature-programmed and isothermal batch experiments. Quantitative attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy is used to measure in s…
Sol−gel nanocasting is used to imprint the soft-matter structures of lyotropic phases of nonionic n -alkyl−poly(ethylene oxide) amphiphiles (“C x E y ”) into solid porous silica. Small angle X-ray scattering (SAXS), nitrogen sorption, and transmission electron microscopy (TEM) are used to investigate the dependence of…
The optical absorption of point-defect-free SiO(2) glass in the vacuum ultraviolet region is primarily controlled by the concentrations of three- and four-membered ring structures composed of heavily strained Si-O-Si bonds. The main channel of color center formation by F(2) excimer laser (7.9 eV) irradiation is not Fr…
Semiconductor nanoparticles, NPs, exhibit fluorescence properties that are closely related to the nature of their surface. CdSe NPs that range in size from 2 to 15 nm in diameter fluoresce with both near-band-edge emission and deep-trap emission, depending on the quality of the surface. When butylamine is added to col…
Deformation properties of multi-wall gold nanowires under compressive loading are studied. Nanowires are simulated using a realistic many-body potential. Simulations start from cylindrical fcc(111) structures at T=0 K. After annealing cycles axial compression is applied on multi-shell nanowires for a number of radii a…
We study the geometrical characteristic of quasi-static fractures in disordered media, using iterated conformal maps to determine the evolution of the fracture pattern. This method allows an efficient and accurate solution of the Lamé equations without resorting to lattice models. Typical fracture patterns exhibit inc…
Monte-Carlo simulation technique has been used to investigate the effect of temperature and adsorbed gases on the composition profile of unsupported Pt-Rh nanocatalysts. For a 2406 atom fcc cubo-octahedral Pt$_{\rm{}50}$Rh$_{\rm{}50}$ nanocatalyst the shell-wise composition for all the eight shells has been simulated.…
We report Raman scattering and visible to near-infrared absorption spectra of solid hydrogen under static pressure up to 285 GPa at 85-140 K. We obtain pressure dependences of vibron and phonon modes in agreement with previously determined to lower pressures. The results indicate the stability of the ordered molecular…
We present the results of a study of the specific heat on a single crystal of ${\mathrm{Pr}}_{0.63}{\mathrm{Ca}}_{0.37}{\mathrm{MnO}}_{3}$ performed over a temperature range 3--300 K in the presence of 0 and 8 T magnetic fields. An estimate of the entropy and latent heat in a magnetic field at the first-order charge-o…
Dark soliton excitations are shown to exist in single wall carbon nanotubes (SWCNTs). At first, the nonlinear effective interatomic potential and the difference equation for longitudinal lattice displacement are obtained for the SWCNTs by expanding Brenner's many-body potential in a Taylor series up to fourth-order te…
We discuss numerical and theoretical results for models of magnetization switching in nanoparticles and ultrathin films. The models and computational methods include kinetic Ising and classical Heisenberg models of highly anisotropic magnets which are simulated by dynamic Monte Carlo methods, and micromagnetics models…
The effect of thermal fluctuations on a thin film magnetoresistive element has been calculated. The technique involves adding to the basic spin dynamics a general form of interaction with a thermal bath. For a general anisotropic magnetic system the resulting equation can be written as a Langevin equation for a harmon…
Methanol oxidation on a supported Pt fuel cell catalyst was investigated by on-line differential electrochemical mass spectrometry (DEMS) at continuous electrolyte flow and defined catalyst utilization, employing a thin-film electrode setup and a thin-layer flow-through cell. The active surface of the Pt/Vulcan (E-TEK…
Despite the importance of (11)B nuclear magnetic resonance (NMR) in structural studies of borate glasses, no clear means of correlating NMR parameters with the number of nonbridging oxygens on three-coordinate boron has been demonstrated. In this work, a series of anhydrous, polycrystalline, binary borates has been ex…
Subsequent to work by Boustani on B 12 clusters in free space, a study is made of B 12 clusters embedded in graphitic fragments with use of Hartree−Fock methodology. To gain insight about defect embedding for an extended graphite layer, clusters of varying sizes up to 336 C atoms have been studied. Bonding density map…
Abstract A ternary system polypropylene (PP)/calcium carbonate (CaCO 3 )/high molar mass polysiloxane has been investigated with respect to its processing, crystallization, and dynamic mechanical properties. The filling level of PP varied from 2.5 vol % to 6.5 vol % CaCO 3 and 0.6 vol % to 2.5 vol % polysiloxane, and…