Materials Literature
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The crystalline carbon nanotubes having mesopores that are open at one end, with pore width of 4 ± 0.8 nm, were characterized by XRD, XPS, and HRTEM. The N 2 adsorption isotherm of multiwall carbon nanotubes was measured at 77 K. A hump was observed near P / P 0 = 0.4 in the adsorption isotherm. The adsorption isother…
We report the results of extensive Dynamic Monte Carlo simulations of systems of self-assembled Equilibrium Polymers without rings in good solvent. Confirming recent theoretical predictions, the mean-chain length is found to scale as $\Lav = \Lstar (ϕ/\phistar)^α\propto ϕ^α\exp(δE)$ with exponents $α_d=δ_d=1/(1+γ) \ap…
We consider the growth of a polymer layer on a flat surface in a good solvent by in-situ polymerization. This is viewed as a modified form of diffusion-limited aggregation without branching. We predict theoretically the formation of a pseudo-brush with density rhog(z) \propto z^{-2/3} and characteristic height \propto…
Unconcatenated, unknotted polymer rings in the melt are subject to strong interactions with neighboring chains due to the presence of topological constraints. We study this by computer simulation using the bond-fluctuation algorithm for chains with up to N=512 statistical segments at a volume fraction Φ=0.5 and show t…
We report results of extensive Dynamical Monte Carlo investigations on self-assembled Equilibrium Polymers (EP) without loops in good solvent. (This is thought to provide a good model of giant surfactant micelles.) Using a novel algorithm we are able to describe efficiently both static and dynamic properties of system…
Si anodic dissolution in acidic fluoride medium has been investigated in different regimes (porous silicon formation, electropolishing under stationary and oscillating current) by probe beam deflection (PBD) or the “mirage” technique. Evolution of deflection signal allows monitoring of dissolution processes both under…
A simple model is proposed to calculate the charge distribution in the two-electron-reduced isopolytungstate [W10O32].6- It is shown that the experimentally observed asymmetric excess electron distribution is due to competition of the electronic delocalization between equatorial metal sites and Coulomb repulsion.
Polyethylene glycol (PEG)-linked manganese halogenated porphyrins (Chart 1) catalyzed oxidation of azo dyes (Chart 2) by H 2 O 2 under mild conditions such as pH 8.0 at 25 °C especially when imidazole was present, causing the decoloration of azo dyes. The decoloration of azo dyes by synthetic manganese porphyrins unde…
Dielectric measurements were carried out on undiluted cis -polyisoprene (PI) over a wide frequency range from 10 -4 to 10 5 Hz around the glass transition temperature T g (=200 K). The data indicate that the dielectric loss curves including both the normal and segmental mode processes are superposable in the range abo…
(3 S )-3-[(Benzyloxycarbonyl)methyl]morpholine-2,5-dione (BMD) has been successfully copolymerized with ε-caprolactone for a wide range of mole fractions in the feed. The sequence analysis of the copolymers has also been carried out on the basis of the clear interpretation of the 13 C NMR spectra of the copolymers. DC…
The local structure of glasses in the system Na 2 O−B 2 O 3 −Al 2 O 3 is studied by multinuclear magic-angle spinning (MAS) solid-state NMR spectroscopy at 7.0 and 11.7 T. The 23 Na isotropic chemical shifts vary linearly with Na 2 O concentration, indicating that the sodium ions are homogeneously distributed over the…
Development of an ellipsometry to the case of a coherent far infrared irradiation, low temperatures and small samples is described, including a decision of the direct and inverse problems of the convergent beam ellipsometry for an arbitrary wavelength, measurement technique and a compensating orientation of cryostat w…
We have performed total-energy density-functional calculations using first-principles pseudopotentials to determine the atomic and electronic structure of neutral surface and subsurface vacancies at the GaP(110) surface. The cation as well as the anion surface vacancy show a pronounced inward relaxation of the three n…
A novel synthetic procedure for the preparation of hyperbranched polymers with narrow molecular weight distribution and enhanced degree of branching (DB) has been studied, using computer simulation to model the kinetics of the process. Slow addition of AB m monomers to B f core molecules in solution (“core-dilution/sl…
Raman line shapes of the longitudinal optical phonon have been analyzed for the pseudobinary alloy system CdSxTe1−x over the full alloy range. The polycrystalline thin films were grown by pulsed laser deposition at, typically, 370 °C including films with x values throughout the miscibility gap (0.06<x<0.…
The stability of quasicrystals is related to the Hume-Rothery mechanism known to take place in many intermetallics, especially Al-Cu alloys. In order to assess to what extent the electronic density of states in aperiodic Al-Cu-Fe compounds is sensitive to Hume-Rothery stabilization, we present experimental measurement…
A Sb-mediated growth technique is developed to deposit Ge quantum dots (QDs) of small size, high density, and free of dislocations. These QDs were grown at low growth temperature by molecular beam epitaxy. The photoluminescence and absorption properties of these Ge QDs suggest an indirect-to-direct conversion, which i…
A method for transforming low-density configurations of rods, discs or spheres to rigidly jammed packings is described. In D dimensions, it repeats a cycle in which each particle is moved towards to the centre of the cage of the D + 1 neighbouring particles that most closely contain it. Low-density fluid configuration…
Designed as a ferromagnetically coupled spin pentamer, the macrocyclic polyradical 1 possesses an average spin of S=10 in the ground state. This is the highest spin quantum number that has yet been measured for an organic molecule. Ar=tBuC6H4.
Infrared (IR) transmittance spectra were measured for a series of samples with different particle sizes. Two extra absorption peaks appear when the average particle size of the samples is smaller than 60 nm; these peaks can be ascribed to the surface stretching and bending modes of the octahedra. When the average part…