Communication of integrated dielectric permitivity and NMR–characteristics of oil with its physical and chemical properties

The paper presents the results of experimental studies on the dielectric and NMR characteristics of oil samples. The relationship between the complex dielectric constant and the NMR parameters of oil with its density, viscosity and group composition has been established. It was found that the results of these methods directly depend on the content of resinous–asphaltenic compounds in the composition of the studied oil sample.

Effect of Gamma Irradiation on Dielectric Permitivity of Polymer (PVA-CH) Film

The objectives of this study are to investigate the effects of radiation on dielectric properties of PVA-CH films. Polymer (PVA-CH) films were irradiated with Gamma ray at 12 kGy. Polymer film containing PVA (poly Vinyl Alcohol) and Chloral Hydrate (CH) has been prepared by solution casting technique. The obtained polymer composite layers were irradiated with γ – rays at various doses to investigate the radiation effect on dielectric permittivity in the frequency range of 20 Hz – 1 MHz at room temperatures. The real (ε’) and imaginary (ε”) dielectric constant are found to increase with increase in irradiation dose.

p-Xylylenediamine and Its New Polyimides

<p><em>p</em>-Xylylenediamine was synthesized with high yield through a hydrogenization of dinitrile of terephthalic acid. The effect of catalyst and solvent on the yield of the product was studied. The hydrogenization was carried out on skeletal catalysts based on alloy of Reney nickel Ni:Al (1:1) in aliphatic alcohols (C₁-C₄) at 4.0 MPa and 60 ^oC. New alkanearomatic polyimides were synthesized by one-step polycondensation of <em>p</em>-xylylenediamine and dianhydride of tricyclodecentetracarboxylic acid in the presence of isonicotinic acid as a catalyst in nonpolar amide solvents at 110-120 ^oC. The films based on the synthesized polyalkanimides are stable with 70-80 MPa breaking strength and 30-40% elongation. The glass transition temperature of the polymers is within 265-280 ^oC temperature range, the temperature of decomposition is above 340 ^oC. The tangent of dielectic loss of the films at 1 kHz and 25 ^oC is 0.002-0.004, the dielectric permitivity is about 3.22-3.35.</p>

Dielectric properties of materials at microwave frequencies

The paper introduces the review of the present state of art in the measurement of the interaction of electromagnetic waves with different kinds of materials. It is analysis of the possibilities of the mea­surement of the interaction of high frequencies waves (microwaves) with materials and proposal of the experimental method for the studies mentioned above.The electromagnetic field consists of two components: electric and magnetic field. The influence of these components on materials is different. The influence of the magnetic field is negligible and it has no impact on practical use. The influence of the electric field is strong as the interaction between them results in the creation of electric currents in the material (Křivánek and Buchar, 1993).Experiments focused on the evaluation of the complex dielectric permitivity of different materials have been performed. The permitivity of solid material is also measurable by phasemethod, when the specimen is a part of transmission sub-circuit. Microwave instrument for complex permittivity measurement works in X frequency band (8.2–12.5) GHz, the frequency 10.1 GHz was used for all the measurement in the laboratory of physics, Mendel University in Brno. The extensive number of experimental data have been obtained for different materials. The length of the square side of the ae­rial open end was 50 mm and internal dimensions of waveguides were 23 mm × 10 mm. The samples have form of the plate shape with dimensions 150 mm × 150 mm × 4 mm.

Dielectric and Ferroelectric Properties of Ba1-xSrxTiO3 Thin Films Prepared by Pulsed Laser Deposition

In this work, BST (x=0.7, 0.5, 0.3) films have been deposited onto Nb-SrTiO3 substrate with pulsed laser deposition. The crystal structure and surface morphology have been characterized by X-ray diffraction (XRD) and atomic force microscopy, respectively. XRD results revealed that in certain elaboration condition the films were aligned along (00l) direction, normal to the substrate surface. The dielectric loss, relative dielectric permitivity, and polarization of BST films strongly depended on Sr content at room temperature. The tunability of relative dielectric permitivity of BST films exhibited strongly dependence on Sr content, and BST-0.5 shows the maximun K (K = tunability/loss) value.

Darboux transformation for classical acoustic spectral problem

We study discrete isospectral symmetries for the classical acoustic spectral problem in spatial dimensions one and two by developing a Darboux (Moutard) transformation formalism for this problem. The procedure follows steps similar to those for the Schrödinger operator. However, there is no one-to-one correspondence between the two problems. The technique developed enables one to construct new families of integrable potentials for the acoustic problem, in addition to those already known. The acoustic problem produces a nonlinear Harry Dym PDE. Using the technique, we reproduce a pair of simple soliton solutions of this equation. These solutions are further used to construct a new positon solution for this PDE. Furthermore, using the dressing-chain approach, we build a modified Harry Dym equation together with its LA pair. As an application, we construct some singular and nonsingular integrable potentials (dielectric permitivity) for the Maxwell equations in a 2D inhomogeneous medium.

Nano-Micro Scale Characterization of Dielectric Materials

Thin films of dielectric materials are used as insulating layers in microelectronic systems, including integrated circuits and printed circuit boards. Polymer and spin-on-glasses are widely used as coatings and interlevel dielectrics. The dielectric permitivity and loss are the electrical properties of most interest. However, characterization and optimization of the mechanical properties is essential to the successful implementation and usage of these insulators. In this presentation, thin-film structures for measuring direction-dependent properties (dielectric constant, elastic modulus, and coefficient of thermal expansion), and nano-indentation results on spin-on-glass materials will be presented. Significant improvement in the fracture toughness of nanoporous methylsilsesquioxane glass films has been demonstrated upon introduction of porosity into the films.