Materials Literature
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Graphite, carbon-coated silicon, and carbon-coated nickel surfaces were bombarded with obliquely incident Ar+ ions at room temperature. The sputtered surfaces were covered with conical protrusions, ∼2.5×105mm−2 or higher in numerical density, and partially aligned single carbon nanofibers (CNFs), ∼20nm in diameter and…
Si clathrates ${({\mathrm{Ba}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x})}_{8}{\mathrm{Si}}_{46}$ with $x\ensuremath{\leqslant}0.75$ have been successfully synthesized and their superconductivity studied both experimentally and by ab initio calculations. The linear decrease of the cubic lattice parameter with the Sr content…
As a well-known oxidation catalyst, platinum is currently being used to convert NO to $\mathrm{N}{\mathrm{O}}_{2}$ for absorption in so-called $\mathrm{N}{\mathrm{O}}_{x}$ traps under excess oxygen conditions, where direct conversion of NO to nitrogen gas is prohibitive. By performing kinetic Monte Carlo simulations w…
Abstract The propagation of plane waves in an isotropic chiral medium (ICM) is investigated. Simple conditions are derived—in terms of the constitutive parameters of the ICM—for the phase velocity to be directed opposite to the direction of power flow. It is demonstrated that phase velocity and power flow may be oppos…
The spatially anisotropic kinetics involved in the chemical reaction between highly ordered pyrolytic graphite (HOPG) and a beam containing hyperthermal (approximately 8 km s(-1)) O((3)P) atomic oxygen and molecular oxygen yields unique surface morphologies. Upon exposure at moderate sample temperatures (298-423 K), n…
Scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) was used to determine the chemical distribution of semiconductor shell material around colloidal core-shell CdSe/ZnS quantum dots (QDs). EELS signals from positions around the QD indicate a well-defined shell of ZnS…
We have fabricated epitaxial Pr0.7Ca0.3MnO3∕SrTi0.9998Nb0.0002O3 (PCMO∕Nb:STO) junctions and characterized the interface electronic properties. The PCMO∕Nb:STO junctions show highly rectifying current density–voltage (J–V) characteristics without an apparent breakdown in the reverse bias up to 100V at room temperature…
A family of molecule-based magnets of general formula M[TCNQ] y (M = Mn, Fe, Co, Ni; TCNQ = 7,7,8,8-tetracyano- p -quinodimethane) has been synthesized and characterized. The materials have been synthesized from both M a (CO) b and [M(NCMe) 6 ][SbF 6 ] 2 starting materials, complementing previous studies utilizing [M(…
Density difference fluid flows and sedimentation of growing crystals are greatly reduced when crystallization takes place in a reduced gravity environment. In the case of macromolecular crystallography a crystal of a biological macromolecule is used for diffraction experiments (x-ray or neutron) so as to determine the…
Atomic-scale studies using advanced simulation techniques have investigated the energetics of defects, oxygen migration, and dopant incorporation in the proton-conducting SrCeO 3 system. The interatomic potential model first reproduces the observed distorted perovskite structure of SrCeO 3 . Substitution with trivalen…
A new approach to fluorescence “turn-on” chemosensors based on a photoinduced electron transfer (PET) strategy involving conjugated polymers has been developed. Two new conjugated polymers dea-PPETE and tmeda-PPETE were synthesized and characterized. These two polymers use diethylamino and N, N, N ‘-trimethylethylened…
A surface modification technique was developed for the covalent immobilization of poly(vinyl alcohol) (PVA)-heparin hydrogel onto electrically conductive polypyrrole (PPY) film with the objective of achieving controlled release of heparin. First, aldehyde groups were introduced onto PPY film through poly(ethylene glyc…
We have measured the photoconductivity excitation spectra of individual semiconducting carbon nanotubes incorporated as the channel of field-effect transistors. In addition to the pronounced resonance that correlates with the second van Hove transition (E(22)) in semiconducting carbon nanotubes, a weaker sideband at a…
Abstract For Abstract see ChemInform Abstract in Full Text.
Intrinsic catalytic process by capillary condensation of Ga-atoms into nanotrenches, formed among impinging islands during the wurzite-GaN thin film deposition, is shown to be an effective path to growing GaN nanorods without metal catalysts. The nano-capillary brings within it a huge imbalance in equilibrium partial…
We report on electrical spin injection measurements on multiwall carbon nanotubes (MWNTs). We use a ferromagnetic alloy Pd1−xNix with x≈0.7 which allows us to obtain devices with resistances as low as 5.6kΩ at 300 K. The yield of device resistances below 100kΩ, at 300 K, is around 50%. We measure at 2 K a hysteretic m…
Oily core polyurethane nanocapsules with a mean diameter of 200 nm were formulated in miniemulsion by interfacial polycondensation. The encapsulation process in miniemulsion was optimized by the choice of the surfactant type (anionic, cationic, or nonionic) and concentration; hexadecane was the costabilizer. Size dist…
Acidic proteins from many biogenic minerals are implicated in directing the formation of crystal polymorphs and morphologies. We characterize the first extremely acidic proteins purified from biomineralized aragonite. These abalone nacre proteins are two variants of 8.7 and 7.8 kDa designated AP8 (for aragonite protei…
We investigate the interaction effect between oxygen impurities in crystalline germanium on the basis of a quantum rotor model. The dipolar interaction of nearby oxygen impurities engenders non-trivial low-lying excitations, giving rise to anomalous behaviors for oxygen-doped germanium (Ge:O) below a few degrees Kelvi…
Temperature-dependent x-ray diffraction of the low-dimensional spin 1/2 quantum magnet TiOCl shows that the phase transition at T_{c2} = 90 K corresponds to a lowering of the lattice symmetry. Below T_{c1} = 66 K a twofold superstructure develops, that indicates the formation of spin-singlet pairs via direct exchange…