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Lead Oxide (lead + oxide)
Selected AbstractsOn the Initial Stages of Electrooxidation of Aqueous Maleic Acid on Bi-Doped PbO2ELECTROANALYSIS, Issue 15 2007Carlos Borras Abstract Oxidation of maleic acid in aqueous solution on bismuth-doped lead oxide has been studied. The effects of hydrodynamic conditions on the oxidation rate have been identified. The number of electrons transferred during the initial stages of oxidation as well as the apparent heterogeneous rate constant was obtained from the combined analysis of rotating ring-disk currents and the decrease of concentration at constant potential, determined from UV-vis measurements. The number of electrons involved during electrochemical oxidation was found to be 12, indicating full mineralization to CO2, and the heterogeneous rate constant for oxidation at 1.6,V was 9.8×105,cm s,1. [source] Mild oxidative cyclization of sydnone-benzoylhydrazone with lead oxide to 2,5-disubstituted-1,3,4-oxadiazole,sydnone hybrid derivativesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2009Kuo-Chen Chiang The mild oxidation of sydnone-benzoylhydrazone hybrids with lead oxide in acetic acid/dichloromethane solution inducted their intramolecular cyclization to provide the corresponding 2,5-disubstituted-1,3,4-oxidiazole derivatives. The sydnone moiety has been efficient preserved for the future work in the mild oxidation. J. Heterocyclic Chem., (2009). [source] Preparation of Highly Dense PZN,PZT Thick Films by the Aerosol Deposition Method Using Excess-PbO PowderJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2007Jong-Jin Choi Lead zinc niobate,lead zirconate titanate thick films with a thickness of 50,100 ,m were deposited on silicon and alumina substrates using the aerosol deposition method. The effects of excess lead oxide (PbO) on stress relaxation during postannealing were studied. Excess PbO content was varied from 0 to 5 mol%. The as-deposited film had a fairly dense microstructure with nanosized grains. The films deposited on silicon were annealed at temperatures of 700°C, and the films deposited on sapphire were annealed at 900°C in an electrical furnace. The annealed film was detached and cracks were generated due to the high residual compressive stress and thermal stress induced by thermal expansion coefficient mismatch. However, the film deposited using powder containing 2% of excess PbO showed no cracking or detachment from the substrate after the postannealing process. The PbO evaporation at elevated temperature during the postannealing process seemed to have reduced the residual compressive stress. The remanent polarization and relative dielectric constant of the 50 ,m thick films annealed at 900°C were 43.1 ,C/cm2 and 1400, respectively, which were comparable with the values of a bulk specimen prepared by a powder sintering process. [source] Sintering Behavior and Surface Microstructure of PbO-Rich PbNi1/3Nb2/3O3,PbTiO3,PbZrO3 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2001Masao Kondo The sintering behavior and surface microstructure of PbNi1/3Nb2/3O3,PbTiO3,PbZrO3 (PNiNb-PT-PZ) ceramics were investigated. The PNiNb-PT-PZ ceramics with the stoichiometric composition and the addition of excess lead oxide (PbO-rich ceramics) were sintered by liquid-phase sintering in accordance with the solution-reprecipitation mechanism at temperatures below the melting point of PbO. The temperature at which the liquid phase forms fell to near the eutectic point of the PbO,Nb2O5 and the PbO,TiO2 system (868°C) with the addition of 5 mol% PbO. As the calcination temperature influenced the sinterability of the stoichiometric PNiNb-PT-PZ ceramic, unreacted PbO was considered to be the source of the liquid phase in the sintering of the stoichiometric powder. The secondary phase was observed at the surface of PbO-rich ceramics and was suggested to be a liquid phase expelled from inside the ceramic. A sintering scheme of PNiNb-PT-PZ ceramics was proposed, and the high sinterability of PNiNb-PT-PZ ceramics was attributed to the low formation temperature of the liquid phase. [source] MICRO-RAMAN SPECTROSCOPY CHARACTERIZATION OF DELLA ROBBIA GLAZES,ARCHAEOMETRY, Issue 4 2007M. SENDOVA Micro-Raman spectroscopy and the laser-induced transformation technique were used for systematic study of five coloured glazes on Saint John the Baptist (29 inch tondo), a majolica terracotta relief attributed to Luca Della Robbia and on permanent exhibit in The John and Mable Ringling Museum of Art. We suggest that ions in a lead silicate matrix, called ,lead ultramarine', could contribute to the famous Della Robbia blue colour, in addition to the effect of Co atoms as suggested previously by Pappalardo et al. (2004). The original yellow glaze contains lead(II) antimonate. The green is a mixture of the yellow and blue pigments, the brown contains hematite, and the white glaze contains tin dioxide as an opacifier. The use of lead oxide as a main fluxing agent is confirmed by laser-induced micro-crystallization. [source] Malkata and Lisht Glassmaking Technologies: Towards a Specific Link between Second Millennium BCARCHAEOMETRY, Issue 1 2002J. L. Mass Elemental analyses have been conducted on 61 coloured opaque glasses from the Malkata and Lisht New Kingdom glass factories. The presence of tin in several of the blue glasses suggests that a bronze casting byproduct or corrosion product was the source of the copper colorant for these glasses. A positive correlation between the lead and antimony concentrations of the yellow and green opaque glasses, plus a consistent excess of lead oxide in these glasses, suggests the use of antimony-rich cupellation litharge as the source for the Pb2Sb2O7 , colorant in these glasses. The metallurgical byproducts used to colour the Malkata and Lisht glasses provide an explicit mechanism for Peltenburg's theory of interaction between second millennium BC glassmakers and contemporary metalworkers. [source] Rapid synthesis of lead oxide nanorods by one-step solid-state chemical reaction at room temperatureCHINESE JOURNAL OF CHEMISTRY, Issue 11 2004Ya-Li Cao Abstract A simple and facile method was reported to synthesize lead oxide nanorods. Nanorods of lead oxide were obtained directly from grinding solid metal salt and sodium hydroxide in agate mortar with the assistance of a suitable nonionic surfactant in only one step, which is different from the result of hydroxide in solution. The product has been characterized by XRD, TEM and SEM. The formation mechanism of rod-like morphology is discussed and the surfactant plays an important soft-template role in modifying the interface of solid-state reaction and according process of rod-formation. [source] The arterial supply of the patellar tendon: Anatomical study with clinical implications for knee surgeryCLINICAL ANATOMY, Issue 3 2009Jack Pang Abstract The middle-third of the patellar tendon (PT) is well-established as a potential graft for cruciate ligament reconstruction, but there is little anatomical basis for its use. Although studies on PT vascular anatomy have focused on the risk to tendon pedicles from surgical approaches and knee pathophysiology, the significance of its blood supply to grafting has not been adequately explored previously. This investigation explores both the intrinsic and extrinsic arterial anatomy of the PT, as relevant to the PT graft. Ten fresh cadaveric lower limbs underwent angiographic injection of the common femoral artery with radio-opaque lead oxide. Each tendon was carefully dissected, underwent plain radiography and subsequently schematically reconstructed. The PT demonstrated a well-developed and consistent vascularity from three main sources: antero-proximally, mainly by the inferior-lateral genicular artery; antero-distally via a choke-anastomotic arch between the anterior tibial recurrent and inferior medial genicular arteries; and posteriorly via the retro-patellar anastomotic arch in Hoffa's fat pad. Two patterns of pedicles formed this arch: inferior-lateral and descending genicular arteries (Type-I); superior-lateral, inferior-lateral, and superior-medial genicular arteries (Type-II). Both types supplied the posterior PT, with the majority of vessels descending to its middle-third. The middle-third PT has a richer intrinsic vascularity, which may enhance its ingrowth as a graft, and supports its conventional use in cruciate ligament reconstruction. The pedicles supplying the PT are endangered during procedures where Hoffa's fat pad is removed including certain techniques of PT harvest and total knee arthroplasty. Clin. Anat. 22:371,376, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||