Materials Literature
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We present a theoretical analysis and first-principles calculation of the radiative lifetime of excitons in semiconducting carbon nanotubes. An intrinsic lifetime of the order of 10 ps is computed for the lowest optically active bright excitons. The intrinsic lifetime is, however, a rapid increasing function of the ex…
Abstract In the modeling of nanoscale electronic devices, the non‐equilibrium Green's function technique is gaining increasing popularity. One complication in this method is the need for computation of the “self‐energy” functions that account for the interactions between the active portion of a device and its leads. I…
A weakly modulated dielectric grating is equivalent to a planar waveguide. As the high-order spatial sub-waves couple with the leaky mode of the grating, guided-mode resonance (GMR) occurs. In this paper, the resonance positions of a weakly modulated dielectric grating are studied based on the eigenvalue equation of a…
Abstract Blends of poly( N ‐vinyl‐2‐pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) with sodium alginate (NaAlg) were prepared via casting from aqueous solutions. All the obtained blend films were optically clear to the naked eye. The surface properties of the films were analyzed by atomic force microscopy (AFM) and…
The polarized total-reflection X-ray absorption fine structure method was applied to characterize zinc porphyrins at the air-water interface. The X-ray absorption near edge structure exhibited a significant difference depending on the polarization of the X-ray. A shoulder peak of the Zn K-edge corresponding to the 1s-…
The guanine nucleotide binding protein Ras plays a central role as molecular switch in cellular signal transduction. Ras cycles between a GDP-bound "off" state and a GTP-bound "on" state. Specific oncogenic mutations in the Ras protein are found in up to 30% of all human tumors. Previous 31P NMR studies had demonstrat…
We have measured adsorption of xenon on purified HiPco single-walled carbon nanotubes (SWNTs) for coverages in the first layer. We compare the results on this substrate to those our group obtained in earlier measurements on lower purity arc-discharge produced nanotubes. To obtain an estimate for the binding energy of…
Decagonal quasicrystals are made of pairs of atomic planes with pentagonal symmetry periodically stacked along a 10-fold axis. We have investigated the atomic structure of the 2-fold surface of a decagonal Al-Ni-Co quasicrystal using scanning tunneling microscopy. The surface consists of terraces separated by steps of…
Abstract Nanocomposites of polyimides (PI) with covalently grafted polyhedral oligomeric silsesquioxane (R 7 R′Si 8 O 12 or POSS) units were prepared by thermally‐initiated free‐radical graft polymerization of methacrylcyclopentyl‐POSS (MA‐POSS) with the ozone‐pretreated poly[ N , N ′‐(1,4‐phenylene)‐3,3′,4,4′‐benzoph…
Thermal stress that pharmaceutical solids are exposed to during manufacturing can induce various phase transitions in bulk drug substances or excipients, resulting in altered dosage form performance. This paper reports on the thermally induced transformations of a macrolide antibiotic, erythromycin A dihydrate, invest…
Diffusion of hydrogen in metals is a fundamental process in hydrogen storage in metal hydrides, hydrogen purification by metal membranes, and in hydrogen embrittlement. Quantitative applications of existing models for hydrogen diffusion by activated hopping and quantum tunneling require large scale first principles ca…
Abstract The fine structure in the solid state and phase transition behavior of newly synthesized comb copolymers having fluorocarbon and hydrocarbon side‐chains were investigated by temperature controlled wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). From the WAXD profiles, two kind…
Abstract In this study, two different carbons (synthetic graphite particles and carbon fiber) were added to nylon 6,6, and the resulting composites were tested for both the through‐plane thermal conductivity k thru and the in‐plane thermal conductivity k in , using the transient plane source method. The first goal of…
Abstract An area of considerable current interest is the development of a practical approach for assembling inorganic nanoparticles into well‐defined arrays because such a technique would offer immense opportunities leading to applications in microimaging, optoelectronics, therapeutics, etc. This paper illustrates a n…
The preparation and characterization of a series of trinuclear mixed-valence cyano-bridged Co(III)-Fe(II)-Co(III) compounds derived from known dinuclear [[L(n)Co(III)(mu-NC)]Fe(II)(CN)(5)](-) complexes (L(n)() = N(5) or N(3)S(2) n-membered pendant amine macrocycle) are presented. All of the new trinuclear complexes we…
The effects of a Au thin layer on the rate of energy transfer from Si nanocrystals (Si-nc's) to ${\mathrm{Er}}^{3+}$ were studied. The energy transfer rate was found to oscillate with increasing the separation between the active layer and the Au thin film. The period of the oscillation agreed well with that of the cal…
The optical properties of the poly(N-benzylaniline) thin film were investigated by optical characterization. The optical constants such as refractive index and dielectric constant were determined from the transmittance and reflectance spectra of the film. The refractive index dispersion was analyzed by the Wemple-DiDo…
Recently, we proposed a simple, large-scale hydrothermal synthesis of flexible nanocables with silver as cores and cross-linked poly(vinyl alcohol) (PVA) as shells in which silver ions catalyzed the cross-linking of PVA chains under hydrothermal conditions and a so-called synergistic soft−hard template mechanism (SSHM…
[reaction: see text] Synthesis of new quinaldine-based squaraine dyes linked to cellular recognition elements that exhibit near-infrared absorption (>740 nm) are described. Both product analysis and theoretical calculations substantiate the interesting electronic effects of various substituents in the dye formation re…
An evolutionary optimization process involving a genetic algorithm and combinatorial chemistry was employed for the development of green phosphors which are suitable for tricolor white-light-emitting diodes. To accomplish a high luminescent efficiency at 400 nm excitation, we screened a seven-cation oxide system inclu…