Materials Literature
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Abstract Novel epoxy‐terminated monomers based on imine groups were synthesized and their mesogenic properties studied. Aliphatic spacers of different lengths were introduced between the rigid unit and the glycidylic group, and their liquid‐crystalline behavior was examined. They were reacted with primary aromatic dia…
The high-frequency dynamics of ${\mathrm{Sr}}_{0.61}{\mathrm{Ba}}_{0.39}{\mathrm{Nb}}_{2}{\mathrm{O}}_{6}$ are studied using the micro-Brillouin scattering technique to elucidate the uniaxial relaxor behavior. It is found that broad central peaks (CP's) appear at about 400 \ifmmode^\circ\else\textdegree\fi{}C, which i…
Methanol is a common industrial solvent and is added to water to enhance hydrocarbon solubility and to prevent solid hydrate from forming, as well as other applications. One of the side effects of methanol addition to water is to greatly reduce the solubility of ionic solids, particularly divalent solids. The effect o…
A sol−gel procedure using acetic anhydride as a substitute for water using a condensing reagent for the tetraethoxysilane (TEOS) to silica conversion is reported. The mixed solution obtained from the reaction of TEOS and acetic anhydride at 110 °C was allowed to stand in air for several weeks, resulting in gel formati…
A major limitation in determining the effects of ultrasound frequency in sonochemistry in relation to cavitation is that no reliable relationship exists between the energy supplied to the system and the energy converted by the cavitation process in producing a sonochemical effect. However, the current study presents a…
A hybrid density functional theory (DFT) method has been used to interpret the data for the adsorption of nitrogen at 77 K within the porous structure of a sample of synthetic saponite expanded with stable SiO 2 ·TiO 2 colloidal particles and dried by different methods. Air drying (AD) favor the formation of structure…
A series of polyoxometalates PW12O40(3-), SiW12O40(4-), and P2Mo18O62(6-) have been used as photocatalysts for recovery of copper and production of fine metal particles. The process involves absorption of light by polyoxometalates, oxidation of an organic substrate, for instance, propan-2-ol as sacrificial reducing re…
Carbon nanotubes possess a very rich spectrum of plasmon modes. For the single wall, metallic carbon nanotubes, in addition to the high frequency plasma modes in the UV range and the depolarization shifted van Hove plasma resonances, there are also low frequency, gapless plasmon modes in the far-infrared frequency ran…
High performance antennas have been realized on proton-implanted Si with 10/sup 6/ /spl Omega/-cm resistivity. Sharp antenna resonance and low loss up to 20 GHz are observed indicating excellent antenna quality. In contrast, very poor antenna characteristics are found on conventional oxide-isolated Si because of the l…
Electromagnetic wave scattering by two rectangular troughs on a conducting ground plane, which is the simplest trough-grating geometry, is rigorously analyzed using the Kobayashi potential method. The formulation is extended and derived here for the H polarization case. By using the derived far field solution, numeric…
In this paper, the characteristics of corona current of a single insulator under high voltage is studied in different methods. The results show that the characteristics of corona current are different with their status. From these characteristics, an insulator's status can be decided online.
The aim of this work is to propose a mathematical model for the iron losses prediction in soft magnetic materials with any supply voltage. The starting point for the analysis is the knowledge of the iron losses with sinusoidal supply. The model is based on the separation of the losses contributions due to hysteresis,…
Cable joints are generally known to be the weak points of underground distribution lines. One of the most common failure modes of premolded cable joints is linked to the occurrence of dielectric breakdown at the interface. Many parameters may influence the dielectric strength of a cable-joint interface: surface roughn…
The electrical power industry worldwide has some 35 years of manufacturing and field experience with compressed gas, SF/sub 6/ or SF/sub 6//N/sub 2/ mixtures, switchgear and transmission lines (GIS/GIL). Such equipment is in use for distribution as well as the highest transmission voltages, and a 1000 kV GIS is curren…
For dimensioning and optimum control of Peltier coolers and heat pumps, an accurate numerical description of the performance parameters under various operation conditions is required. Here, the situation for homogeneous bismuth antimony telluride based Peltier cooler material is discussed, using representative values…
Non-linear field-grading materials are used to avoid stress concentrations in many AC and DC high voltage applications. One way to obtain materials having the desired non-linear characteristics is to use compounds, such as an insulating polymer with a semiconducting filler. A possible filler is silicon carbide (SiC).…
This paper presents a new approach of modeling the dynamic behavior of supercapacitors using impedance spectroscopy. The new Matlab/Simulink model can be used in simulating the voltage response and energy efficiency, e.g. for automotive power systems. The model in the frequency domain, the parameter calculation as wel…
Highly efficient, segmented thermoelectric unicouples incorporating advanced thermoelectric materials with superior thermoelectric figures of merit are currently being developed at the Jet Propulsion Laboratory (JPL). These segmented unicouples include a combination of state-of-the-art thermoelectric materials based o…
Samples of ${\mathrm{La}}_{0.6}{\mathrm{Sr}}_{0.4}{\mathrm{FeO}}_{3\ensuremath{-}\ensuremath{\delta}}$ compounds prepared by quenching in different gaseous environments were studied by x-ray diffraction, neutron diffraction, magnetization measurements, and M\"ossbauer spectroscopy (MS). All materials are single phase…
gamma-alumina is known to transform to theta-alumina and finally to alpha-alumina upon thermal treatment with a catastrophic loss of porosity and catalytic activity. First-principles calculations were performed to investigate the atomic scale mechanism of the gamma- to theta-alumina transformation. The transformation…