Materials Literature
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Molecular dynamics (MD) simulations are undertaken on a series of five copolyimides based on two different dianhydrides: the flexible 4,4‘-oxydiphthalic dianhydride (ODPA) and the rigid bulky bicyclo(2.2.2)-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA). The diamines are respectively 4,4‘-oxydi(phenylamine) (ODA…
beta-[SiW(12)O(40)](4)(-) (C(3)(v) symmetry) is sufficiently higher in energy than its alpha-isomer analogue that effectively complete conversion to alpha-[SiW(12)O(40)](4)(-) (T(d)) is observed. By contrast, beta- and alpha-[AlW(12)O(40)](5)(-) (beta- and alpha-1; C(3)(v) and T(d), respectively) are sufficiently clos…
An efficient method for doping a transition metal oxide (TMO) with hole carriers is presented: photocarrier injection (PCI) in an oxide heterostructure. It is shown that an insulating vanadium dioxide (VO 2 ) film is rendered metallic under light irradiation by PCI from an n-type titanium dioxide (TiO 2 ) substrate do…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTSynthesis of Size-Tunable Silver Iodide Nanowires in Reverse MicellesSheng Xu, Haicheng Zhou, Jian Xu, and Yadong LiView Author Information Department of Chemistry, the Key Laboratory of Atomic and Molecular Nanoscience (China Ministry of Education), Tsinghua University, Beijin…
Using the density-functional perturbation theory, the vibrational and dielectric properties are calculated for five ${\mathrm{C}}_{3}{\mathrm{N}}_{4}$ crystalline phases. The vibrational frequencies are found to differ significantly from one phase to another, thus giving a strong support to the use of Raman scattering…
Composite polymeric insulators are increasingly being accepted by the traditionally cautious electric utilities worldwide. They currently represent about 70% of installed new high voltage insulators in North America. The tremendous growth in the applications of non-ceramic insulators is due to their advantages over th…
We describe a method for producing and characterizing electrically connected single-wall carbon nanotube scanned-probe tips. The stable contact resistance, of the order of 100 kΩ, makes these tips suitable for conducting probe applications. The nanotubes, grown by chemical vapor deposition, are mounted on the end of m…
Bundles of single-wall carbon nanotubes (SWCNTs) coalesce forming multiwall carbon nanotubes (MWCNTs), containing from two to six nested tubes, under thermal treatment at high temperatures [(2200-2400) degrees C]. This structural transformation is confirmed by extensive molecular dynamics (MD) simulations. The simulat…
Diagnostic measurements of dielectric materials can be performed either in time-domain or frequency-domain. If the dielectric material can be described as a linear system the acquired information in the two domains are in theory equivalent. In time-domain charging/discharging currents and recovery voltage are used and…
This paper discusses results of non-destructive dielectric tests using oscillating voltages. In particular, using comparison to discharge detection on HV cables at the conventional power frequency of 50 (60)Hz, the sensitivity and the reproducibility of this new method for on-site testing is discussed. Based on labora…
The vibrational states, absorption energies, and diffusions of H in Pd and ${\mathrm{Pd}}_{1\ensuremath{-}x}{\mathrm{Ag}}_{x}(0<~x<~1)$ have been studied by first-principle calculations. All results compare favorably to experiment. The zero-point motion of H is important in the determination of the H site occupa…
The vibrational and electronic properties of ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}$ layers with Mn fractions $0<~x<~2.8%,$ grown on GaAs(001) substrates by low-temperature molecular-beam epitaxy, are investigated by micro-Raman spectroscopy and far-infrared (FIR) reflectance spectroscopy.…
Surface chemistries that prevent protein adsorption and render surfaces nonadhesive have emerged as promising biomaterial modifications for minimizing host-implant inflammatory responses and providing a nonspecific background for the presentation of bioactive motifs to elicit directed cellular responses. Oligo(ethylen…
Industrial recycling is a practice of growing importance while impending 'Take Back' European legislation and economic pressures are increasing. Landfill sites are becoming exhausted and the industry could benefit from a novel approach to recycling pre and post consumer waste. Cost constraints limit the number of diff…
The paper deals with Gaussian modeling of harmonic vectors in power systems. Starting from the bivariate Gaussian distribution of the vector resolved components, the univariate magnitude and phase densities are presented both in closed form solutions, which apply when opportune hypotheses are verified, and by more gen…
In the paper, two control methods of a four-leg three-phase invertor for UPS and active filter applications are discussed. The inverter output voltage is represented as a three-dimensional space vector. Two PWM schemes are investigated: open loop sinusoidal PWM; and feedback multilevel hysteresis PWM current control.…
Photoinduced magnetic phase transition of $\mathrm{RbMnFe}(\mathrm{CN}{)}_{6}$ has been investigated by means of x-ray-absorption fine structure spectroscopy. Upon visible-light (532 nm) irradiation at 30 K, the material undergoes the photoinduced tautomeric spin transition. Mn and Fe K-edge x-ray-absorption near-edge…
A palladium-mediated assembling strategy was developed to construct organized, three-dimensional multiporphyrin arrays, wherein layers of multiporphyrin arrays can be embedded via a Py−Pd−Py coordination unit directly on solid substrates. Multilayers of the multiporphyrin arrays were characterized by use of X-ray phot…
The double-layer capacitor (DLC) for power applications is a new device. A simple resistive capacitive equivalent circuit is insufficient to characterize its terminal behaviour. Based on physical reasoning, an equivalent circuit is proposed to provide the power electronics engineer with a model for the terminal behavi…
The magnetization reversal has been examined by the temperature dependence of the coercivity, the initial magnetization curve, minor hysteresis loops, and thermal activation in isotropic nanocrystalline Pr-Fe-B ribbons. The coercivity mechanism is found to vary with temperature. At 20 K, the coercivity is mainly deter…