Materials Literature
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We have determined the adsorptive capacity of Xe on the different groups of binding sites available to this atom on a sample of single-walled carbon nanotube (SWNT) bundles. The SWNT's used were not treated after production: hence, the caps at the ends of each of the tubes remain intact. By comparing these experimenta…
Substitution of the weakly binding aqua ligand in [Cu(tren)OH2](2+) and [Cu(tpa)OH2](2+) (tren = tris(2-aminoethyl)amine; tpa = tris(2-pyridylmethyl)amine) by a cyano ligand on ferricyanide results in the assembly of heteropolynuclear cations around the cyanometalate core. In water, the reduction of the Fe(III) core t…
The diffusion of deuterated hexane in conformational isomers of a heterogeneous polymer, H 12 MDI (4,4‘-dicyclohexylmethane diisocyanate)/BD (1,4-butanediol)/PTMO (poly(tetramethylene oxide)), was investigated at a fixed hard segment content of 30 wt % and compared to the diffusion of acetonitrile. The effective diffu…
Vibrational study by Raman spectroscopy was made of the layered perovskite compounds of the formula M 2 La 2 Ti 3 O 10 (M = H, Li, Na, K, Rb), K 2 La 2 Ti 3 O 10 ·2H 2 O, and H 2 La 2 Ti 3 O 10 · n H 2 O. The spectral features above 400 cm -1 were similar in all of the unhydrated samples suggesting that the bands orig…
A dinuclear Ru(III) complex, [Ru2Cl2(PPh3)2(μ-Cl)2(μ-salhn)], has been synthesized and characterized by analytical, spectroscopic, magnetic, and X-ray diffractometry. The redox active complex displays two reductions corresponding to RuIII2/RuIIIRuII and RuIIIRuII/RuII2 couples. A weak antiferromagnetic spin coupling i…
31 P and 13 C NMR studies are reported for a smectic A liquid crystal of haxakis[4-dodecyl(4-biphenoxy)]cyclotriphosphazene. In an intense magnetic field, the long axes of the biphenylene fragments and the alkyl chains align along the magnetic field, and the cyclotriphosphazene (ctp) ring-normal points preferentially…
Molecular dynamics (MD) simulations have been performed to study the flexibility of smectite clay minerals. We aim at the quantitative understanding of the mechanical behavior of a single clay layer in a completely exfoliated state. The repeating unit of a clay layer is taken to be a o = 0.52 nm and b o = 0.902 nm wit…
Tensile properties and morphology of tetrafunctional multigraft copolymers are investigated dependent on PS volume fraction and number of branch points. It is found that tetrafunctional multigraft copolymers with 22 vol % PS and seven branch points show a surprising high strain at break of about 2100%, about double th…
Confinement effects on first-order and second-order Raman scattering in nanocrystalline silicon are presented. The average dimension of the nanocrystals has been determined by an analysis of the first-order Raman spectra using the phenomenological phonon confinement model. The second-order acoustic bands 2LA and 2TA d…
First-principles calculations are used to investigate the electronic properties of the surfaces of polyethylene. The calculations support the experimental evidence of a negative electron affinity, with calculated values of -0.17 eV and -0.10 eV for surfaces with chains perpendicular and parallel to the surface normal,…
Dehydroxylation and silanization processes on the silica surface are studied by ab initio molecular dynamics. The (100) and (111) surfaces of β-cristobalite are used as two possible models of the hydroxylated amorphous surface. The activation energy and latent heat for the dehydroxylation reactions of the (100) surfac…
The depletion-induced phase separation in a mixture of colloidal particles (PMMA-latex) and nonadsorbing polymers [poly(styrene)] in a solvent (mixture of tetralin, cis-decalin, and carbon tetrachloride) was investigated in real space with confocal scanning laser microscopy in the initial, intermediate, and final stag…
Heteroatoms of Al and Ti are effectively introduced into the framework of ordered mesoporous silica materials (designated as MAS-7 and MTS-9, respectively) in strong acidic media (pH < 0) by a two-step procedure. MAS-7 shows high catalytic activities for the cracking of both small (cumene) and bulky (1,3,5-tri-isoprop…
The extension of the first-principles generalized pseudopotential theory (GPT) to transition-metal (TM) aluminides produces pair and many-body interactions that allow efficient calculations of total energies. In aluminum-rich systems treated at the pair-potential level, one practical limitation is a transition-metal o…
Comment on PRL v. 86, p. 5084 (2001) [cond-mat/0101016]. We point out that the authors' simulations are consistent with the known theory of steady-state solutions in this system.
The temperature-dependence of the magnetization near the surface of a band-ferromagnet is measured with monolayer resolution. The simultaneous application of novel highly surface-sensitive techniques enables one to deduce the layer-dependent magnetization curves at a Fe(100) surface. Analysis of data is based on a sim…
Decomposable hollow capsules based on deoxyribonucleic acid (DNA) and a low molecular weight organic molecule, a naturally occurring polyamine, spermidine (SP), were formed by applying the layer-by-layer adsorption strategy to colloid particles, viz., assembling DNA/SP multilayers on colloids and subsequently removing…
We have prepared hydrogenated single-wall and multiwall carbon nanotubes, as well as graphite, via a dissolved metal reduction method in liquid ammonia. The hydrogenated derivatives are thermally stable up to 400 °C. Above 400 °C, a characteristic decomposition takes place accompanied with the simultaneous formations…
We examine the behavior of the D-band feature in the Raman spectra of single-walled carbon nanotube (SWNT) bundles, observed between 1250 and $1450 {\mathrm{cm}}^{\ensuremath{-}1},$ as a function of the laser excitation energy. We used three SWNT samples with different diameters, and show that the D-band behavior of S…
The Raman spectra of a wide range of disordered and amorphous carbons have been measured under excitation from 785 to 229 nm. The dispersion of peak positions and intensities with excitation wavelength is used to understand the nature of resonant Raman scattering in carbon and how to derive the local bonding and disor…