Materials Literature
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One of the most important parameters that determine the transport properties of a quantum dot array is the exciton dissociation energy, i.e., the energy $\ensuremath{\Delta}E$ required to dissociate an exciton into an electron and a hole localized in different dots. We show that a pseudopotential calculation for a dot…
We extended the sensitivity of Raman correlation spectroscopy in solution to the single-molecule level by applying surface- and resonance-enhanced Raman scattering (SERRS) combined with time-gated, confocal signal detection. The brightness of the SERRS signal of single Rhodamine 6G molecules adsorbed on a single silve…
Phase transitions and staging in doped single-wall carbon nanotubes (SWNT's) are controversial issues. Here, we report on combined in situ conductivity and Raman measurements of Rb-doped SWNT's. Striking correlations between resistance, changes of resistance under laser irradiation, and frequency of the main Raman pea…
Relations between the thermodynamics and dynamics of supercooled liquids approaching a glass transition is a topic of considerable interest. The potential energy surface of model liquids has been increasingly studied, since it provides a connection between the configurational component of the partition function on the…
Dense poly(styrene sulfonate sodium salt) brushes were prepared on silicone wafers using a two-step procedure: polystyrene (PS) chains, terminated by a reactive trichlorosilane group, were first covalently grafted, and then the PS brush was converted to a poly(styrene sulfonate) brush by a soft sulfonation reaction. E…
The magnetic ground state of perovskite structure ${\mathrm{CaRuO}}_{3}$ has been enigmatic for decades. Here we show that paramagnetic ${\mathrm{CaRuO}}_{3}$ can be made ferromagnetic by very small amounts of partial substitution of Ru by Ti. Magnetic hysteresis loops are observed at 5 K for as little as 2% Ti substi…
The substitution of ruthenium for manganese has been studied in the ${\mathrm{Sm}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ series, leading to a magnetic (T vs x) phase diagram where a large region of ferromagnetic metallic phases appears. These results are compared with those obtained by chromium doping…
Ample experimental evidence has been accumulated demonstrating that the formation of monodispersed colloids proceeds through a more complex mechanism, than the generally excepted diffusional "burst nucleation" process. Instead, the synthesis of narrow-size-distribution colloidal dispersions involves several stages, i.…
We devise a two dimensional model that mimics the recently observed power law distributions for the amplitudes and durations of the acoustic emission signals observed during martensitic transformation [ Vives {\it et al}, Phys. Rev. Lett. {\bf 72}, 1694 (1994)]. We include a threshold mechanism arising from the atherm…
Calculations based on density functional theory (DFT) have been carried out to investigate the electronic and magnetic properties of the alpha-Keggin anions mentioned in the title. The atomic populations and the distribution of the electron density computed for the studied clusters support the hypothesis that an oxidi…
A set of iron(II) complexes that exhibit a temperature-dependent spin-crossover between the low-spin and the high-spin state were studied by density functional methods. The total electronic energy, the zero-point vibrational energy, and the entropy were calculated in order to determine the free energy. While the calcu…
A new synthetic method was developed to produce robust, highly crystalline, organic-monolayer passivated silicon (Si) nanocrystals in a supercritical fluid. By thermally degrading the Si precursor, diphenylsilane, in the presence of octanol at 500 degrees C and 345 bar, relatively size-monodisperse sterically stabiliz…
Plastic wastes, which cause a serious environmental problem in urban areas, can serve as sources of energy. Catalytic treatment of High Density Polyethylene (HDPE) has shown that the degradation of HDPE resulted in the production of a stream of gaseous hydrocarbons varied in the range C1-C8. The degradation was carrie…
Abstract This article establishes the processing–microstructure–motion–property relationship of high‐speed melt‐spun nylon‐6 fibers. From solid‐state 1 H NMR T 1ρ (spin–lattice relaxation time in the rotating frame) relaxation studies, all nylon‐6 fibers spun at 4500–6100 m/min showed three‐component exponential decay…
Abstract Chitosan (chitosan acetic acid salt) and whey (65% protein) films were coated with a nitrocellulose lacquer or laminated with polyethylene to enhance their water resistance and gas barrier properties in humid environments. The barrier properties were measured by the Cobb 60 test and water‐vapor (100% relative…
The diamond-to-\ensuremath{\beta}-tin phase transitions of Si and Ge under uniaxial compression are investigated with ab initio calculations. A thermodynamic analysis is used to identify the transition pressures at uniaxial compression. The transition pressures were found to be pronouncedly lower than those at hydrost…
The depletion interaction between two parallel repulsive walls confining a dilute solution of long and flexible polymer chains is studied by field-theoretic methods. Special attention is paid to self-avoidance between chain monomers relevant for polymers in a good solvent. Our direct approach avoids the mapping of the…
In this work, we present the results of the investigation of the effect of prolonged cycling on the hydriding/dehydriding properties and on the structure of nanocrystalline MgH 2 −V composite under hydrogen containing 110 ppm of carbon monoxide. The hydrogen charge and discharge kinetics of the nanocomposite hydride w…
An experimental study showed the enhancement effect of di- tert -butyl peroxide on poly(α-methylstyrene) (PAMS) thermal degradation in trichlorobenzene solution (12.5 g/L). Peroxide was continuously injected into the reacting polymer solution at low flow rates (0.3−4.0 mL/h). Samples were taken periodically and analyz…
The cis-doubly N-confused porphyrin, H2N2CP, containing two adjacent confused pyrrole rings has been investigated from the point of view of its acid-base and electrochemical behavior in dichloromethane. This novel porphyrin isomer can form two metal-carbon bonds in the central core, stabilizing metal ions in unusually…