Materials Literature
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The new semiempirical methods, PDDG/PM3 and PDDG/MNDO, have been parameterized for halogens. For comparison, the original MNDO and PM3 were also reoptimized for the halogens using the same training set; these modified methods are referred to as MNDO' and PM3'. For 442 halogen-containing molecules, the smallest mean ab…
The surfactant-encapsulated europium-substituted heteropolyoxotungatate, (DODA) 11 H 2 [Eu(SiW 11 O 39 ) 2 (H 2 O) 4 ] (SEC-2), is structurally characterized in detail and its photophysical behaviors are investigated. The DODA alkyl chains of SEC-2 are well ordered in the solid state, solvent-casting film, and Langmui…
The conversion of NO to N2 is a key issue encountered in the control of emission from vehicles. The selectivity of NO reduction on two platinum group metals, Ir and Pt, including the close-packed flat surface and the monatomic steps are extensively studied within the first-principles density functional theory framewor…
Photochromic diarylethene derivatives containing 2,4-diphenylphenyl substituents formed stable amorphous solids and showed reversible solid-state photochromism. Refractive indices of the amorphous films changed reversibly with the photochromic reactions as much as Δ n = 0.028 at 817 nm. Changes in both absorption band…
Platelet adhesion to the surfaces of biomaterials preadsorbed with plasma previously has been shown to be mediated exclusively by surface-bound fibrinogen and does not seem to involve the other adhesion proteins in plasma (Tsai et al., J Biomed Mater Res 2002;60:348-359). In this study, the influence of surface-bound…
We report in this study that an oxoiron(IV) porphyrin complex bearing electron-deficient porphyrin ligand, (TPFPP)FeIV=O (TPFPP = meso-tetrakis(pentafluorophenyl)porphinato dianion), shows reactivities similar to those found in oxoiron(IV) porphyrin pi-cation radicals. In the epoxidation of olefins by the (TPFPP)FeIV=…
Gaps in the voluminous data on pyrolysis of polyethylene that impede mechanistic understanding are highlighted, especially for H:C material balances, product distributions at varying conversions in isothermal closed systems, and inconsistencies between GC and FIMS analyses of products with lower volatility. Thermochem…
We present measurements of Shubnikov-de Haas oscillations in arrays of bismuth nanowires with diameters comparable to the Fermi wavelength. For 80-nm wires the hole concentration is less than 30% of that for bulk Bi, consistent with current models of quantum confinement effects. However, 30-nm wires nanowires which ar…
We propose that localized defects in magnetic semiconductors act as deep impurities and can be described by the Anderson model. Within this model, hybridization of d-orbitals and p-orbitals gives rise to a non-RKKY indirect exchange mechanism, when the localized d-electrons are exchanged through both conduction and va…
Semiconductor quantum wires constitute a promising thermoelectric material because of the increase of the electronic density of states in low-dimensional materials. We studied the magnetic-field-dependent resistance and Seebeck coefficient of a high-density network of 6-nm-diameter wires of Bi and of Bi(1-x)Te(x), x=0…
In dynamic Monte Carlo simulations, using for example the Metropolis dynamic, it is often required to simulate for long times and to simulate large systems. We present an overview of advanced algorithms to simulate for larger times and to simulate larger systems. The longer-time algorithm focused on is the Monte Carlo…
Compressed copper powder has a very large electrical resistance (1MOhm), due to the oxide layer on grains (100 micro m). We observe that its voltage-current U-I characteristics are nonlinear, and undergo an instability, from an insulating to a conductive state at relatively small applied voltages. Current through the…
In this paper, we elucidate the vibrational response of cylindrical nanorods to ultrafast laser-induced heating. A theoretical analysis of the expected behavior is first presented. This analysis predicts that both extensional and breathing vibrational modes of the rods should be excited by laser-induced heating. Analy…
We present results of the preparation (by precursor decomposition), characterization (with x-ray diffraction, transmission electron microscopy, and dc magnetization measurements), and detailed computation (using density functional theory) of polycrystalline ZnO with up to 15% substitution of the zinc sites by divalent…
Supramolekulare Chirogenese: Die supramolekulare Wechselwirkung von achiralem Bis(zinkporphyrin) mit enantiomerenreinen Aminosäure-Derivaten führt zur Induktion von Chiralität. Vorzeichen und Größe des Circulardichroismus werden durch die Polarität des Lösungsmittels bestimmt (siehe Bild).
In a RF induction thermal plasma chemical vapour deposition system the substrate is used as an electrical probe to monitor the diamond film evolution in situ . The evolving electron emission current allows us to identify the transition from the initial nucleation stage to the diamond growth stage. A direct-current bia…
Quasi‐amorphous BaTiO 3 thin films (see Figure) represent a polar ionic solid without spatial periodicity. Most probably, polarity of the quasi‐amorphous BaTiO 3 is associated with directional ordering of crystal motifs formed in the steep temperature gradient and stabilized by high in‐plane mechanical stress. A remar…
We present exact results on the thermal conductivity of the one-dimensional spin-1/2 XXZ model in the massive antiferromagnetic and ferromagnetic regimes. The thermal Drude weight is calculated by a lattice path integral formulation. Numerical results for wide ranges of temperature and anisotropy as well as analytical…
p-Chlorophenol (4-CP) is a recalcitrant organic pollutant that is biologically toxic in industrial wastewater. A high-frequency ultrasonic device operated at 1.7 MHz was designed and used successfully to degrade 4-CP. Iodine liberation in the KI aqueous solution confirmed that effective cavitation occurred under the h…
Super Structures: By thermally evaporating elemental layers onto substrates at ambient temperature, structural precursors are constructed with appropriate composition and modulation lengths to kinetically favor the formation of the desired superstructure. On annealing, these modulated elemental reactants form metastab…