Materials Literature
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Electroless deposition of gold on the pore walls of polycarbonate templates is currently the best known method for controlling inside diameters of template-synthesized nanotubes. It would be very useful to have alternative template-based synthetic chemistries that yield nanotubes composed of other materials, but which…
We use ab initio methods to calculate the physical and electronic properties of carbon adatoms on different characteristic carbon nanotubes. We found that for every tube the energetically favored adsorption geometry is a ``bridgelike'' structure between two surface carbons, perpendicular to the long axis of the tube.…
The oxidation of sulfides with H(2)O(2) catalyzed by iron tetrakis(pentafluorophenyl)porphyrin in EtOH is an efficient and chemoselective process. With a catalyst concentration 0.03-0.09% of that of the substrate, sulfoxides are obtained with yields generally around 90-95% of isolated product. With vinyl and allyl sul…
2-(Dimethylamino)ethyl methacrylate (DMA) was block copolymerized with methyl methacrylate (MMA) using group transfer polymerization to give four AB diblock, ABA triblock, and BAB triblock copolymers of low polydispersity (Mw/Mn < 1.20). In addition, a near-monodisperse styrene-functionalized DMA-based macromonomer wa…
A series of poly(ethylene oxide)- b -polystyrene (PEO- b -PS) diblock copolymers were designed and synthesized to study the change in crystal orientation of PEO blocks under different confinement sizes. The volume fraction of PEO blocks ( f PEO ) in these copolymers was kept almost identical (the f PEO values were bet…
We report the fabrication and electrical characterization of a single electron transistor in a modulation doped silicon/silicon-germanium heterostructure. The quantum dot is fabricated by electron beam lithography and subsequent reactive ion etching. The dot potential and electron density are modified by laterally def…
Planar model catalysts were prepared by deposition of size-selected gold clusters containing up to seven atoms on rutile TiO2 (110). Molecular oxygen is observed to bind inefficiently to the surface, probably at oxygen vacancies, and some oxygen also appears to bind to the gold clusters. Stable CO binding is observed…
Sequential addition of sulfur and Cd(acac)2 into the colloid solution of FePt nanoparticles ( approximately 2.5 nm) under a reductive environment generates heterodimers of CdS and FePt with sizes of approximately 7 nm. The heterodimers exhibit both superparamagnetism and fluorescence, indicating that the discrete prop…
In this work, a simple and inexpensive method is introduced for the immobilization of the hazardous elements Cd, Pb, and Fe from their aqueous solutions in compressed fossil fuel fly ash formulations, as candidates for waste forms. The molded formulations were prepared by initially mixing the hazardous waste solutions…
Abstract TlInS 2 single crystals are studied through the conductivity and Hall effect measurements in the temperature regions of 100‐400 and 170‐400 K, respectively. An anomalous behavior of Hall voltage, which changes sign below 315 K, is interpreted through the existence of deep donor impurity levels that behave as…
Abstract A method is presented for developing multiple particle breakage distribution functions that include the shape factor, as well as the particle size. The technique is to first develop a joint probability distribution that accounts for the size and shape factor of each child particle. This is then reduced by suc…
A maskless method for patterning substrates using surface relief structures on azobenzene‐functionalized polymer is demonstrated. Surface relief structures are inscribed on a polymer film spin‐coated on an indium tin oxide (ITO) substrate by exposure to an interference pattern. Etching with oxygen plasma followed by a…
A new synthesis of the silicon‐network‐backbone polymer poly(methylsilyne) gives a material that is easily converted by pyrolysis to smooth continous films of stoichiometric silicon carbide (see Figure). The films are adherent to the silicon or alumina substrates, and show root mean square roughness of 169 Å over a 50…
We study the aging dynamics in a model for dense simple liquids, in which particles interact through a hard-core repulsion complemented by a short-ranged attractive potential, of the kind found in colloidal suspensions. In this system, at large packing fractions, kinetically arrested disordered states can be created b…
A synergistic study, using gradient corrected density functional theory and photoelectron spectroscopy, shows that the presence of oxygen can fundamentally alter the interaction between two Mn atoms. The normally weak interaction between two Mn atoms exhibits strong bonding when an oxygen atom is added to form ${\math…
Abstract The flow stress in the yield surface of plastic constitutive equation is modified with a higher order gradient term of the effective plastic strain to model the effect of inhomogeneous deformation in granular materials. The gradient constitutive model has been incorporated into the finite element code ABAQUS…
Abstract CoSBA-15 with different nSi/nCo ratio have been synthesized in acidic media using nonionic surfactants and characterized, for the first time, by XRD, AAS, N2 adsorption, UV–vis DRS and ESR spectroscopy. Spectroscopic data show that all cobalt atoms in CoSBA-15 are extensively in tetrahedral coordination.
Abstract Highly ordered anodic porous alumina was fabricated by anodization of vapor-deposited Al that had been deposited on a self-organized periodic array of polystyrene particles with a submicron-scale diameter on a glass plate. The ordered bumpy structure of the particle array surface was replicated on the deposit…
Abstract In our previous work, we showed that the structural recovery responses of an epoxy after relative humidity (RH)‐jumps through the glass concentration have similar phenomenology to, but different kinetics from, those obtained by temperature (T)‐jumps. In this article, we report results from physical aging expe…
Self‐assembled monolayer coating of silane molecules on the surface of nanometric particles of hydroxyapatite and TiO 2 has been performed using a supercritical (SC) fluid method. The performance of the SC method is compared to that of a conventional (CV) aqueous alcohol method (see Figure). SC anhydrous silanization…