Optical properties of potassium niobate thin films prepared by the polymeric precursor method

Thin films of potassium niobate were deposited on MgO (100) substrates by the polymeric precursor method and annealing in static air at 600 degreesC for 20 h. The obtained films were characterized by X-ray diffraction, atomic force microscopy (AFM) and the prism coupling method. The phi-scan diffraction evidenced the growth of the films with fourfold symmetry. AFM study shows that the films are homogeneous, dense and present a smooth surface. The refractive index and optical losses were strongly influenced by the degree of crystallinity. (C) 2004 Elsevier B.V. All rights reserved.

Crystallization and preliminary X-ray diffraction analysis of a novel Arg49 phospholipase A(2) homologue from Zhaoermia mangshanensis venom

Zhaoermiatoxin, an Arg49 phospholipase A(2) homologue from Zhaoermia mangshanensis (formerly Trimeresurus mangshanensis, Ermia mangshanensis) venom is a novel member of the PLA(2)-homologue family that possesses an arginine residue at position 49, probably arising from a secondary Lys49 -> Arg substitution that does not alter the catalytic inactivity towards phospholipids. Like other Lys49 PLA(2) homologues, zhaoermiatoxin induces oedema and strong myonecrosis without detectable PLA(2) catalytic activity. A single crystal with maximum dimensions of 0.2 x 0.2 x 0.5 mm was used for X-ray diffraction data collection to a resolution of 2.05 angstrom using synchrotron radiation and the diffraction pattern was indexed in the hexagonal space group P6(4), with unit-cell parameters a = 72.9, b = 72.9, c = 93.9 angstrom.

Effect of the excess of bismuth on the morphology and properties of the BaBi2Ta2O9 ceramics

In this study, the effect of bismuth content on the crystal structure, morphology and electric properties of barium-bismuth-tantalate (BBT) ceramics was explored with the aid of X-ray diffraction (XRD), scanning electron microcopy (SEM), dielectric properties and ferroelectric hysteresis loops. BaBi2Ta2O9 (BBT) ceramics have been successfully prepared by the solid-state reaction. The BBT phase was crystallized at 900 degreesC for 2 h. The excess of bismuth controls the grain size, affecting the density of the material. Measurements of dieletric constant and dieletric losses confirm that the material is a ferroeletric with a Curie temperature around 77 degreesC. The dieletric constant measured at room temperature was 400, with a dielectric loss of 0.03. Both the phase-transition behaviour and ferroelectric properties, such as spontaneous polarization (P-s), showed a dependence on Bi content. (C) 2004 Elsevier B.V. All rights reserved.

CRYSTALLIZATION AND PRELIMINARY DIFFRACTION DATA OF 2 MYOTOXINS ISOLATED FROM THE VENOMS OF BOTHROPS-ASPER (TERCIOPELO) AND BOTHROPS-NUMMIFER (JUMPING VIPER)

Two myotoxins isolated from B. asper (myotoxin II) and B. nummifer (myotoxin I) snake venoms have been crystallized and their diffraction properties are described. These myotoxins are phospholipase A2 variants which lack enzymatic activity; B. asper myotoxin II is a lysine-49 phospholipase. Crystals were obtained at room temperature by standard hanging-drop vapour diffusion methods. Crystals diffracted to a resolution of 2.8 and 2.3 angstrom, respectively.

X-ray powder diffraction analysis of methionine sulfoxide

Powder X-ray diffraction data for methionine sulfoxide, C5H11NO3S, obtained from the commercial amino acid, are presented in this work. Monoclinic cell parameters are: a = 15.500 Angstrom; b = 3.820 Angstrom; c = 13.490 Angstrom; 8=97.300 degrees. (C) 2001 International Centre for Diffraction Data.

Crystallization and preliminary X-ray diffraction analysis of an anti-H(O) lectin from Lotus tetragonolobus seeds

The seed lectin from Lotus tetragonolobus (LTA) has been crystallized. The best crystals grew over several days and were obtained using the vapour-diffusion method at a constant temperature of 293 K. A complete structural data set was collected at 2.00 angstrom resolution using a synchrotron-radiation source. LTA crystals were found to be monoclinic, belonging to space group P2(1), with unit-cell parameters a = 68.89, b = 65.83, c = 102.53 angstrom, alpha = gamma = 90, beta = 92 degrees. Molecular replacement yielded a solution with a correlation coefficient and R factor of 34.4 and 51.6%, respectively. Preliminary analysis of the molecular-replacement solution indicates a new quaternary association in the LTA structure. Crystallographic refinement is under way.

Synthesis by the polymeric precursor method and characterization of undoped and Sn, Cr and V-doped ZrTiO4

In this work, zirconium titanate doped with 0. 1, 0.2, and 0.4 mole% of tin, chromium and vanadium was synthesized by the polymeric precursors method and characterized by thermal analysis (TG/DTA), X-ray diffraction (XRD), nitrogen adsorption and scanning electronic microscopy (SEM). The powder presented two mass losses attributed to the exit of water and to the pyrolysis of the organic material. The surface area reduction observed from 500 degrees C indicates the beginning of the sintering process. All the dopants led to changes in the lattice parameters and to the decrease of both crystallite size and particle size. (c) 2005 Elsevier B.V. All rights reserved.

Friction losses in valves and fittings for viscoplastic fluids

Data on pressure drop were obtained in stainless steel, sanitary fittings and valves during laminar and turbulent flow of aqueous suspensions of sucrose and bentonite. The rheological properties of these suspensions were determined and the Bingham model provided the best fitting with the experimental data. Friction losses were measured in fully- and partially-open butterfly and plug valves, bends and union. Values of loss coefficients (k(f)) were calculated and correlated as functions of the classical Reynolds number and the Reynolds number proposed by Govier and Aziz (1972) for viscoplastic fluids. The two-k method and a new proposed model presented the best adjustments for the Govier and Aziz Reynolds number, and Hedstrom and classical Reynolds numbers, respectively.

Influence of the LiNbO3 and KNbO3 seeds on the sintering and electrical properties of PMN ceramic

The effect of LiNbO3 and KNbO3 seeds on the microstructure and dielectric characteristics of PMN ceramic prepared by columbite route have been investigated with the addition of 0, 1, and 2-wt% of seeds. X-ray diffraction, Scanning Electron Microscopy and an impedance analyzer were used to characterize the influence of seeds on physical characteristics and dielectric properties of PMN. LiNbO3 -seeded PMN samples present a significant increase in the amount of perovskite phase. The addition of LiNbO3 seeds in sintered PMN ceramics at 1100degreesC during 4 h causes a decrease in the porosity and the amount of pyrochlore phase. Weight losses during sintering of PMN ceramics are suppressed more significantly for LiNbO3 -seeded PMN. T-m of PMN ceramics changes with seeds concentration. KNbO3 seeds displace T-m to lower temperature whereas LiNbO3 causes its elevation. Dielectric constants of approximately 13,000 at 1 kHz was measured at -5degreesC in PMN ceramics with 1-wt% of LiNbO3 seeds.

Allocation of the costs of transmission losses

An analysis of the performance of six major methods of loss allocation for generators and demands was conducted, based on pro-rata (two), on incremental factors (two), on proportional sharing (PS) (one), and on electric circuit theory (one). Using relatively simple examples which can easily be checked, the advantages and disadvantages of each were ascertained and the results confirmed using a larger sample system (IEEE-118). The discussion considers the location and size of generators and demands, as well as the merits of the location of these agents for each configuration based on an analysis of the effect of various network modifications. Furthermore, an application in the South-Southeastern Brazilian Systems is performed. Conclusions and recommendations are presented. (C) 2004 Elsevier B.V. All rights reserved.

Crystallization and preliminary X-ray diffraction analysis of suramin, a highly charged polysulfonated napthylurea, complexed with a myotoxic PLA(2) from Bothrops asper venom

Suramin is a highly charged polysulfonated napthylurea that interferes in a number of physiologically relevant processes such as myotoxicity, blood coagulation and several kinds of cancers. This synthetic compound was complexed with a myotoxic Lys49 PLA(2) from Bothrops asper venom and crystallized by the hanging-drop vapor diffusion method at 18 degreesC. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit cell parameters a=49.05, b=63.84 and c=85.67 Angstrom, Diffraction data was collected to 1.78 Angstrom. (C) 2004 Elsevier B.V. All rights reserved.

Using artificial neural networks for identification of electrical losses in transformers during the manufacturing phase

The paper describes a novel neural model to estimate electrical losses in transformer during the manufacturing phase. The network acts as an identifier of structural features on electrical loss process, so that output parameters can be estimated and generalized from an input parameter set. The model was trained and assessed through experimental data taking into account core losses, copper losses, resistance, current and temperature. The results obtained in the simulations have shown that the developed technique can be used as an alternative tool to make the analysis of electrical losses on distribution transformer more appropriate regarding to manufacturing process. Thus, this research has led to an improvement on the rational use of energy.

Optical properties of Mg doped LiNbO3 thin films grown by polymeric precursor method.

Polymeric precursor solution was used to deposit by spin-coating pure and Mg doped LiNbO3 thin films on sapphire substrates. The effects of magnesium addition on crystallinity, morphology and optical properties of the annealed films were investigated. X-ray diffraction patterns indicate the oriented growth of the films. AFM studies show that the films are very homogeneous, dense and present smooth surfaces. The refractive index and optical losses obtained by the prism coupling method were influenced by the magnesium addition.

Effects of processing on the structure of zein/oleic acid films investigated by X-ray diffraction

Zein films plasticized with oleic acid were formed by solution casting, by the stretching of moldable resins, and by blown film extrusion. The effects of the forming process on film structure were investigated by X-ray diffraction. Wide-angle X-ray scattering (WAXS) patterns showed d-spacings at 4.5 and 10 angstrom, which were attributed to the zein alpha-helix backbone and inter-helix packing, respectively. The 4.5.angstrom d-spacing remained stable under processing while the 10 angstrom d-spacing varied with processing treatment. Small-angle X-ray scattering (SAXS) detected a long-range periodicity for the formed films but not for unprocessed zein, which suggests that the forming process-promoted film structure development is possibly aided by oleic acid. The SAXS d-spacing varied among the samples (130-238 angstrom) according to zein origin and film-forming method. X-ray scattering data suggest that the zein molecular structure resists processing but the zein supramolecular arrangements in the formed films are dependent on processing methods.

X-ray powder diffraction analysis of a silver(I)-aspartame complex

Synchrotron X-ray powder diffraction (XRPD) data were collected for the silver(I)-aspartame complex [Ag(C14H17N2O5)]center dot 1/2 H2O. The complex was obtained from a stoichiometric mixture of aspartame (3-amino-N-(alpha-carboxyphenethyl)-succinamic acid N-methyl ester, C14H18N2O5), Na2CO3, and AgNO3. Indexing using Crysfire and Chekcell proposed an orthorhombic unit cell with space group P222(1). The lattice parameters are a = 12.4750(1) angstrom, b = 21.60614(14) angstrom, and c = 4.88888(9) angstrom. (C) 2006 International Centre for Diffraction Data.