Materials Literature
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Ion-pair formation between carboxylate anions on particle surfaces and tetraoctylammonium cations caused the phase transfer of well-characterized, water-soluble gold nanoparticles into an organic phase. Stepwise extraction procedures demonstrated for the first time that the initially fractionated solution included gol…
The use of polycarbonates as thermally decomposable, sacrificial materials for the formation of microchannels is presented. Polycarbonates decompose in the temperature range of 200-300 °C. Two polycarbonates, polyethylene carbonate and polypropylene carbonate, have been used to fabricate microchannels in three differe…
We show that it is possible to perform full microscopic calculations of the phonon-assisted and no-phonon radiative transitions in silicon nanocrystals. These are based on a tight-binding Hamiltonian for the electron and electron-phonon part together with a valence force-field model for phonons. We predict an unexpect…
Theoretical investigations have been carried out to explore the possibilities of Li + ion intercalation or insertion through the side-wall or through the cap region of carbon nanotubes. Hartree−Fock(HF), MP2 and density functional (DFT) theories with minimal to extended basis sets were used to examine simple models of…
Resol type phenolic resin/layered silicate nanocomposites (RPLSNs) are prepared by melt intercalation using various layered silicates such as sodium montmorillonite (MMT) and ω-amino acid modified montmorillonites (C3M, C6M, and C12M). The most hydrophilic MMT is the most compatible with the resol type phenolic resin…
The thermal oxidation of metals by water vapour and by oxygen is compared and several ideas are advanced to explain the differences often observed. The incorporation of hydroxyl ions in the oxide is shown to be of importance, but possible only if vacancy or interstitial oxide defects are present. The decomposition rat…
Current proposals for the catalytic mechanism of aspartic proteinases are largely based on X-ray structures of bound oligopeptide inhibitors possessing nonhydrolyzable analogues of the scissile peptide bond. However, the positions of protons on the catalytic aspartates and the ligand in these complexes have not been d…
Femtosecond pump−probe transient spectroscopy is used to compare the time dependence of the bleach recovery of CdSe nanorods with that of nanodots. In the quantum dots the bleach spectrum evolved rapidly to its characteristic shape, while in the nanorods, the higher energy exciton states are first populated within the…
Thermal decomposition pathways of our recently prepared hydrotalcite-like compounds Mg 1 - x Al x (OH) 2 (NO 3 ) x · n H 2 O in x = 0.20−0.34 ( J. Phys. Chem. B 2001, 105, 1743−1749) have been investigated with XRD, DTA, TGA, FTIR, and combined TGA/FTIR techniques. It has been found that, unlike those in carbonated hy…
Vanadium oxide nanotubes have been formed from the layered vanadium oxide precursor V 2 O 5+ δ [C 12 H 25 NH 3 ]. Both the precursor and tubes have been characterized. The black nanotubes have a relatively low thermal stability in oxygen, being oxidized to V 2 O 5 below 200 °C. A new manganese vanadium oxide nanotube,…
We report magnetic and transport properties of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ba}}_{x}{\mathrm{MnO}}_{3}$ $(x=0.05--0.33)$ epitaxial thin films. Compared with the corresponding bulk materials, the ferromagnetic transition temperature is reduced in the compressive strained ${\mathrm{La}}_{1\ensuremath{-}x}{\…
A dibenzyl substituted poly(3,4-propylenedioxythiophene) was designed and synthesized, and exhibited a contrast of 89% at 632 nm with switching speeds of 400 ms and coloration efficiency of 575 cm2 C−1.
Constitutive equations are derived for the viscoelastic behavior of filled elastomers at isothermal loading with finite strains. A particle-reinforced rubber is thought of as a composite where regions with low concentrations of junctions between chains are randomly distributed in the bulk material. The onset of these…
A theoretical study on the rotational dynamics of H2 molecules trapped in the interstitial channels (ICs) of a carbon nanotube bundle is presented. The potential used in this study is modeled as a sum of atom-atom (C-H) van der Waals interactions and electrostatic interactions of the molecule with the surrounding nano…
This paper has two parts. The first part uses a single point of view to discuss the reflection and averaging mechanisms of spin-transfer between current-carrying electrons and the ferromagnetic layers of magnetic/non-magnetic heterostructures. The second part incorporates both effects into a matrix Boltzmann equation…
Protein adsorption and growth of primary human osteoblasts on self-assembled monolayers of alkylthiols on gold (SAMs) with carboxylic acid and hydroxyl and methyl termini were investigated. Single-component SAMs and SAMs patterned by photolithographic techniques were used. Cell growth on patterned SAMs demonstrated pr…
A new sugar-based gelator 1 was synthesized, and its gelation ability was evaluated in organic solvents and water. Very surprisingly, 1 was found to gelate organic solvents as well as water, indicating that 1 can act as an amphiphilic gelator. We characterized on superstructures of an aqueous gel from 1 using SEM, TEM…
Crystallization of 5-methyl-2-[(2-nitrophenyl)amino]-3-thiophenecarbonitrile (1), previously found to produce six conformational polymorphs from solution, on single-crystal pimelic acid (PA) substrates results in selective and oriented growth of the metastable "YN" (yellow needle) polymorph on the (101)(PA) faces of t…
In classical enzymology, intermediates and transition states in a catalytic mechanism are usually inferred from a series of biochemical experiments. Here, we derive an enzyme mechanism from true atomic-resolution x-ray structures of reaction intermediates. Two ultra-high resolution structures of wild-type and mutant d…
Novel organic/inorganic hybrid copolymers have been prepared using single site catalysis. Ethylene copolymers incorporating a norbornylene-substituted polyhedral oligomeric silsesquioxane (POSS) macromonomer have been prepared using a metallocene/methylaluminoxane (MAO) cocatalyst system. Isotactic polypropylene-conta…