Materials Literature
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Nanoparticles of the ferrimagnetic ε-Fe 2 O 3 oxide have been synthesized by the sol–gel method. Here we report on the measurement of the dielectric permittivity as a function of temperature, frequency and magnetic field. It is found that, coinciding with the transition from collinear ferrimagnetic ordering to an inco…
A three-dimensional lattice of micron-scale coated spheres is shown to have an isotropic negative index of refraction at infrared frequencies. The materials used are entirely non-magnetic. The Mie scattering theory of the constituent spheres is used in the effective medium theory. The physical mechanisms and procedure…
A new type of alkalide compound, Li+(calix[4]pyrrole)M- (M = Li, Na, and K), is presented in theory, which may be stable at room temperature. It has been shown by our calculations that the first hyperpolarizability (beta) is considerably large by means of the density functional theory method. The beta values are deter…
Cationic water-soluble poly(fluorene-co-phenylene)s with electron withdrawing or donating substituents on the conjugated backbone were designed and synthesized. Fluorescence resonance energy transfer (FRET) experiments between these conjugated polymers and dye-labeled single-stranded DNA (ssDNA-C*) reveal the importan…
We report on an inelastic (Raman) light scattering study of the local structure of amorphous GeTe (a-GeTe) films. A detailed analysis of the temperature-reduced Raman spectra has shown that appreciable structural changes occur as a function of temperature. These changes involve modifications of atomic arrangements suc…
The determination of high-resolution structures of proteins requires crystals of suitable quality. Because of the new impetus given to structural biology by structural genomics/proteomics, the problem of crystallizing proteins is becoming increasingly acute. There is therefore an urgent requirement for the development…
The most important factor that causes delamination between copper alloy lead frame and epoxy mold compound is copper oxide. To identify the factors that influence the formation of oxide film on copper substrate, oxidation mechanism of several lead-frame copper alloys was investigated. The oxide film structure of coppe…
The paper describes the failure mechanisms of medium voltage inter-turn insulation as a consequence of space charge formation and partial discharge (PD) activity. In order to investigate the failure behavior, models of turn insulation are prepared with magnetic wires having polyimide and nano-filled coating. The agein…
Direct waveguide definition of a negative photoresist (SU8) containing tricyanovinylidenediphenylaminobenzene (TCVDPA) as electro-optic (EO) chromophore, has been demonstrated for the first time. This was possible by utilising the chromophore low absorption window in the UV region allowing crosslinking of the host pol…
Abstract The energy levels of valence bands (VBs) and core levels (CLs) of SbSeI single crystals have been investigated theoretically. A molecular model of the SbSeI crystal was used for the calculations of VBs and CLs by the Hartree–Fock method (UHF). This molecular cluster consisting of 20 molecules was used for cal…
The temperature dependence of the structure of the mixed-anion Tutton salt K2[Cu(H2O)6](SO4)(2x)(SeO4)(2-2x) has been determined for crystals with 0, 17, 25, 68, 78, and 100% sulfate over the temperature range of 85-320 K. In every case, the [Cu(H2O)6]2+ ion adopts a tetragonally elongated coordination geometry with a…
Quantum chemical calculations have been performed to investigate the interaction of a water molecule with gas phase aluminum oxide cluster anions. While oxygen-rich clusters (AlxOy-,x<y) (including Al2O3- which resembles the stoichiometry of bulk alumina) form hydroxides as the end product, many aluminum-rich clusters…
We report the density-functional-theory study of the electronic structure and exchange interactions in four diluted magnetic semiconductors (ZnMe)O, $\mathrm{Me}=\mathrm{Mn},\mathrm{Fe},\mathrm{Co},\mathrm{Ni}$. The calculations are performed for two impurity concentrations of 25% and 6.25%. For all systems the intera…
The hydrophobicity of composite insulators is a very important property for composite insulators used on transmission lines. An off-line test to indicate the hydrophobicity of a composite insulator has been developed by STRI, but it can not be used under on-line conditions. The objective of this paper is focused on an…
Investigations of the lightning impulse breakdown characteristics of a SF6/N2 gas mixture, N2 gas and CO2 gas have been carried out. In the case of the SF6/N2 gas mixture the 50% breakdown (electric) field strength for the positive impulse voltage was slightly lower than that for the negative impulse voltage, and the…
We report that capillary flows in an evaporating thin film create line patterns, with widths ranging from a few micrometers to less than 100 nm. Deliberate patterning of such lines requires contact-line pinning and the presence of foaming surfactants. Large-scale photolithography can guide and control these structures…
Abstract The exfoliation of clay layers was realized in a tri‐hydroxyl branched polyether polyol by direct mixing and the corresponding exfoliated polyurethane/clay nanocomposite was prepared by further in situ curing. The effects of various surface‐modified organoclays and various polyol types on the intercalation an…
To understand the formation mechanism of helical supramolecular structures in the smectic C (SmC) liquid crystalline (LC) phase of BPCA-C n -P m OH ( n is the number of methylene units, n = 6−10) (see: Jeong, K.-U.; Jin, S.; Ge, J. J.; Knapp, B. S.; Graham, M. J.; Ruan, J.; Guo, M.; Xiong, H.; Harris, F. W.; Cheng, S.…
The transmission characteristics of small slots and circular apertures in conducting films are described using a waveguide mode analysis and numerical simulations. A set of modes are shown to exist for a circular waveguide hole which propagate for an arbitrarily small diameter. As the hole becomes small, loading with…
The optical absorption and excitonic properties of wurtzite ZnO are investigated by means of an ab initio approach taking into account electron-hole correlations. This is done by solving the Bethe-Salpeter equation, using the results of density functional theory calculations as a starting point. Our main focus is the…