Materials Literature
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Shape-persistent macrocycles with an interior in the nanometer regime allow the attachment of (functional) side groups at defined positions at the ring. These side groups can have either a fixed orientation relative to the molecular backbone or they can adapt their orientation according to an external stimulus. The pr…
The conjugated polymer polyaniline is a promising material for sensors, since its conductivity is highly sensitive to chemical vapors. Nanofibers of polyaniline are found to have superior performance relative to conventional materials due to their much greater exposed surface area. A template-free chemical synthesis i…
Low-dimensional free-standing aggregates of bare gold clusters are studied by the molecular dynamics simulation. Icosahedra of 55 and 147 atoms are equilibrated at T=300 K. Then, their one- and two-dimensional assemblies are investigated. It is found that icosahedra do not coalescence into large drops, but stable amor…
We present experimental and modeling studies of UV nanosecond pulsed laser desorption and ablation of (111) bulk silicon. The results involve a new approach to the analysis of plume formation dynamics under high-energy photon irradiation of the semiconductor surface. Non-thermal, photo-induced desorption has been obse…
The diffusion of deuterium-labeled atactic polystyrene (dPS) from the surface of a precrystallized polydisperse, isotactic polystyrene (iPS) matrix was measured using dynamic secondary ion mass spectroscopy (DSIMS). The detailed depth profiles indicated two types of mass transport into the iPS matrix. A layer near the…
Treatment of Ti−Beta synthesized by the fluoride method with basic quaternary ammonium solution followed by calcination enhanced the epoxidation activity with hydrogen peroxide, which is due to the reduction of the amount of fluorine contained in the catalyst.
A novel extended amphiphilic dendrimer with linear poly(ethylene oxide) (PEO) attached to a PEO-like dendritic core as hydrophilic fraction and eight docosyl chain branches as hydrophobic fraction has been prepared for the use as structure-directing agent for silica-type materials. The extended dendrimer exhibits a he…
Recently reported results indicate that the formation of surfactant-free, oil-in-water emulsions can be significantly enhanced by the almost complete removal of dissolved gases and that the reintroduction of dissolved gases does not immediately destabilize the already-formed emulsions. These initial experiments have b…
Our calculations indicate that a chromium or vanadium atomic chain adsorbed on an armchair carbon nanotube opens up a band gap for the minority spin, making the whole system a 100% spin-polarized conductor. The gaps are 0.49 and 0.44 eV for V and Cr, respectively. The adsorption of manganese, iron, cobalt, or nickel c…
Oxidation and oxygenation of (HCTPPH)Fe(II)Br an iron(II) complex of 2-aza-5,10,15,20-tetraphenyl-21-carbaporphyrin (CTPPH)H2 have been followed by 1H and 2H NMR spectroscopy. Addition of I2 or Br2 to the solution of (HCTPPH)Fe(II)Br in the absence of dioxygen results in one-electron oxidation yielding [(HCTPPH)Fe(III…
Ordered arrays of carbon nanotubes in bent and straight states were prepared using “wet” deposition of nanotube solutions on a patterned surface. This approach provided a means for the formation of highly oriented and textured nanotube arrays of different types. Moreover, under certain conditions, nanotube loops of di…
The molecular sieving property of a continuous b-oriented pure-silica-zeolite (PSZ) MFI monocrystal film was demonstrated in a zeolite-modified electrode (ZME) configuration using redox molecules of different sizes. Ru(NH3)63+ (diameter approximately 5.5 A) was able to traverse the film, while Co(phen)32+ (diameter ap…
We present a two-step synthesis route that yields nanometer-size crystalline germanium in the form of a black powder. It relies on high temperature decomposition of tetraethylgermane (TEG) in organic solvents. The presence of pure germanium with diamond structure is unambiguously attested by powder XRD measurements. L…
Porous sulfonic acid functionalized silica spheres have been prepared by oxidation ofthiol-functionalized mesoporous silica samples obtained by co-condensation of (mercaptopropyl)trimethoxysilane and tetraethoxysilane in the presence ofcetyltrimethylammonium as a template. The physicochemical characteristics of the re…
We report the ring-opening polymerization reaction of ε-caprolactone in supercritical carbon dioxide (scCO 2 ) using an enzyme catalyst, Lipase B from Candida antarctica supported on macroporous beads (Novozym-435). Ring-opening polymerization of lactones is more commonly performed in organic solvents or in bulk using…
Carbon nanotube (CNT) transistors, sensors, and field emitters have recently attracted much attention. However, it is difficult to form ordered submonolayer arrays of these molecular wires because of their high aspect ratio and strong inter-nanotube van der Waals interactions. A tractable procedure for the formation o…
The fluorescence of a triad with TTF and anthracence units can be reversibly modulated by sequential oxidation and reduction. Thus, a new redox fluorescence switch can be established on the basis of this new triad. [structure: see text]
A linear scaling method for calculation of the static {\em ab inito} response within self-consistent field theory is developed and applied to calculation of the static electric polarizability. The method is based on density matrix perturbation theory [Niklasson and Challacombe, cond-mat/0311591], obtaining response fu…
Activated carbon composite prepared from rice husk using phosphoric acid activation has been studied through precarbonization of the precursor followed by chemical activation. This method can produce carbons with micro- and mesoporous structure. The ratio of chemical activating agent to precarbonized carbon was fixed…
A new generation of optically encoded beads has been prepared by using mesoporous polystyrene beads and surfactant-coated semiconductor quantum dots. In comparison with nonporous beads of similar sizes and chemical compositions, the encoded porous beads are approximately 1000 times brighter and 5 times more uniform in…