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Selected AbstractsMorphine, opioids, and the feline pulmonary vascular bedACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2008A. D. KAYE Background: Opioid-induced vasodepressor responses have been reported in a variety of species and laboratory models. The aim of this study was to ascertain the relative potencies of different clinically relevant opioids compared with traditional vasodepressor agents in the feline pulmonary vascular bed. A second aim was to study the effects of morphine and to identify the receptors involved in the mediation or the modulation of these effects. Methods: This was a prospective vehicle-controlled study involving an intact chest preparation of adult mongrel cats. The effects of various opioids, morphine, fentanyl, remifentanil, sufentanil, and meperidine were compared with other vasodepressor agents. Additionally, the effects of l - N5 -(1-iminoethyl) ornithine hydrochloride (l -NIO) (nitric oxide synthase inhibitor), nimesulide [selective cyclooxygenase (COX)-2 inhibitor], glibenclamide (ATP-sensitive K+ channel blocker), naloxone (non-selective opioid receptor antagonist), and diphenhydramine (histamine H1 -receptor antagonist) were investigated on pulmonary arterial responses to morphine and other selected agonists in the feline pulmonary vascular bed. The systemic pressure and lobar arterial perfusion pressure were continuously monitored, electronically averaged, and recorded. Results: In the cat pulmonary vascular bed of the isolated left lower lobe, morphine, remifentanil, fentanyl, sufentanil, and meperidine induced a dose-dependent moderate vasodepressor response and it appeared that sufentanil was the most potent on a nanomolar basis. The effects of morphine were not significantly altered after administration of l -NIO, nimesulide, and glibenclamide. However, the vascular responses to morphine were significantly attenuated following administration of naloxone and diphenhydramine. Conclusion: The results of the present study suggest that sufentanil appears to have slightly more potency and morphine the least of the five opioid agonists studied on a nanomolar basis. Morphine-induced vasodilatory responses appeared to be mediated or modulated by both opioid receptor and histamine-receptor-sensitive pathways. [source] Differential Central NOS-NO Signaling Underlies Clonidine Exacerbation of Ethanol-Evoked Behavioral ImpairmentALCOHOLISM, Issue 3 2010Tara S. Bender Background:, The molecular mechanisms that underlie clonidine exacerbation of behavioral impairment caused by ethanol are not fully known. We tested the hypothesis that nitric oxide synthase (NOS)-derived nitric oxide (NO) signaling in the locus coeruleus (LC) is implicated in this phenomenon. Methods:, Male Sprague,Dawley rats with intracisternal (i.c.) and jugular vein cannulae implanted 6 days earlier were tested for drug-induced behavioral impairment. The latter was assessed as the duration of loss of righting reflex (LORR) and rotorod performance every 15 minutes until the rat recovered to the baseline walk criterion (180 seconds). In a separate cohort, we measured p-neuronal NOS (nNOS), p-endothelial NOS (eNOS), and p-ERK1/2 in the LC following drug treatment, vehicle, or NOS inhibitor. Results:, Rats that received clonidine [60 Ig/kg, i.v. (intravenous)] followed by ethanol (1 or 1.5 g/kg, i.v.) exhibited synergistic impairment of rotorod performance. Intracisternal pretreatment with nonselective NOS inhibitor N, -nitro- l -arginine methyl ester (l -NAME, 0.5 mg) or selective nNOS inhibitor N -propyl- l -arginine (1 ,g) exacerbated the impairment of rotorod performance caused by clonidine,ethanol combination. Exacerbation of behavioral impairment was caused by l -NAME enhancement of the effect of ethanol, not clonidine. l -NAME did not influence blood ethanol levels; thus, the interaction was pharmacodynamic. LORR caused by clonidine (60 ,g/kg, i.v.),ethanol (1 g/kg, i.v.) combination was abolished by selective inhibition of central eNOS (l -NIO, 10 ,g i.c.) but not by nNOS inhibition under the same conditions. Western blot analyses complemented the pharmacological evidence by demonstrating that clonidine,ethanol combination inhibits phosphorylation (activation) of nNOS (p-nNOS) and increases the level of phosphorylated eNOS (p-eNOS) in the LC; the change in p-nNOS was paralleled by similar change in LC p-ERK1/2. NOS inhibitors alone did not affect the level of nitrate/nitrite, p-nNOS, p-eNOS, or p-ERK1/2 in the LC. Conclusions:, Alterations in NOS-derived NO in the LC underlie clonidine,ethanol induced behavioral impairment. A decrease in nNOS activity, due at least partly to a reduction in nNOS phosphorylation, mediates rotorod impairment, while enhanced eNOS activity contributes to LORR, elicited by clonidine,ethanol combination. [source] Facilitation of Myocardial PI3K/Akt/nNOS Signaling Contributes to Ethanol-Evoked Hypotension in Female RatsALCOHOLISM, Issue 7 2009Mahmoud M. El-Mas Background:, The mechanism by which ethanol reduces cardiac output (CO) and blood pressure (BP) in female rats remains unclear. We tested the hypothesis that enhancement of myocardial phosphatidylinositol 3-kinase (PI3K)/Akt signaling and related neuronal nitric oxide synthase (nNOS) and/or endothelial nitric oxide synthase (eNOS) activity constitutes a cellular mechanism for the hemodynamic effects of ethanol. Methods:, We measured the level of phosphorylated eNOS (p-eNOS) and p-nNOS in the myocardium of ethanol (1 g/kg intragastric, i.g.) treated female rats along with hemodynamic responses [BP, CO, stroke volume, (SV), total peripheral resistance, (TPR)], and myocardial nitrate/nitrite levels (NOx) levels. Further, we investigated the effect of selective pharmacological inhibition of nNOS with N, -propyl- l -arginine (NPLA) or eNOS with N5 -(1-iminoethyl)- l -ornithine (l -NIO) on cellular, hemodynamic, and biochemical effects of ethanol. The effects of PI3K inhibition by wortmannin on the cardiovascular actions of ethanol and myocardial Akt phosphorylation were also investigated. Results:, The hemodynamic effects of ethanol (reductions in BP, CO, and SV) were associated with significant increases in myocardial NOx and myocardial p-nNOS and p-Akt expressions while myocardial p-eNOS remained unchanged. Prior nNOS inhibition by NPLA (2.5 or 12.5 ,g/kg) attenuated hemodynamic effects of ethanol and abrogated associated increases in myocardial NOx and cardiac p-nNOS contents. The hemodynamic effects of ethanol and increases in myocardial p-Akt phosphorylation were reduced by wortmannin (15 ,g/kg). On the other hand, although eNOS inhibition by l -NIO (4 or 20 mg/kg) in a dose-dependent manner attenuated ethanol-evoked hypotension, the concomitant reductions in CO and SV remained unaltered. Also, selective eNOS inhibition uncovered dramatic increases in TPR in response to ethanol, which appeared to have offset the reduction in CO. Neither NPLA nor l -NIO altered plasma ethanol levels. Conclusions:, These findings implicate the myocardial PI3K/Akt/nNOS signaling in the reductions in BP and CO produced by ethanol in female rats. [source] Characteristics and function of cardiac mitochondrial nitric oxide synthaseTHE JOURNAL OF PHYSIOLOGY, Issue 4 2009Elena N. Dedkova We used laser scanning confocal microscopy in combination with the nitric oxide (NO)-sensitive fluorescent dye DAF-2 and the reactive oxygen species (ROS)-sensitive dyes CM-H2DCF and MitoSOX Red to characterize NO and ROS production by mitochondrial NO synthase (mtNOS) in permeabilized cat ventricular myocytes. Stimulation of mitochondrial Ca2+ uptake by exposure to different cytoplasmic Ca2+ concentrations ([Ca2+]i= 1, 2 and 5 ,m) resulted in a dose-dependent increase of NO production by mitochondria when l -arginine, a substrate for mtNOS, was present. Collapsing the mitochondrial membrane potential with the protonophore FCCP or blocking the mitochondrial Ca2+ uniporter with Ru360 as well as blocking the respiratory chain with rotenone or antimycin A in combination with oligomycin inhibited mitochondrial NO production. In the absence of l -arginine, mitochondrial NO production during stimulation of Ca2+ uptake was significantly decreased, but accompanied by increase in mitochondrial ROS production. Inhibition of mitochondrial arginase to limit l -arginine availability resulted in 50% inhibition of Ca2+ -induced ROS production. Both mitochondrial NO and ROS production were blocked by the nNOS inhibitor (4S)- N -(4-amino-5[aminoethyl]aminopentyl)- N,-nitroguanidine and the calmodulin antagonist W-7, while the eNOS inhibitor l - N5 -(1-iminoethyl)ornithine (l -NIO) or iNOS inhibitor N -(3-aminomethyl)benzylacetamidine, 2HCl (1400W) had no effect. The superoxide dismutase mimetic and peroxynitrite scavenger MnTBAP abolished Ca2+ -induced ROS generation and increased NO production threefold, suggesting that in the absence of MnTBAP either formation of superoxide radicals suppressed NO production or part of the formed NO was transformed quickly to peroxynitrite. In the absence of l -arginine, mitochondrial Ca2+ uptake induced opening of the mitochondrial permeability transition pore (PTP), which was blocked by the PTP inhibitor cyclosporin A and MnTBAP, and reversed by l -arginine supplementation. In the presence of the mtNOS cofactor (6R)-5,6,7,8,-tetrahydrobiopterin (BH4; 100 ,m) mitochondrial ROS generation and PTP opening decreased while mitochondrial NO generation slightly increased. These data demonstrate that mitochondrial Ca2+ uptake activates mtNOS and leads to NO-mediated protection against opening of the mitochondrial PTP, provided sufficient availability of l -arginine and BH4. In conclusion, our data show the importance of l -arginine and BH4 for cardioprotection via regulation of mitochondrial oxidative stress and modulation of PTP opening by mtNOS. [source] Influence of the starting powders on the synthesis of nickel ferriteCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2006F. Kenfack Abstract The thermal decomposition of freeze-dried nickel(II)-iron(III) formate was investigated by means of DTA, TG, mass spectrometry and X-ray powder diffractometry. For the preparation of homogeneous freeze-dried nickel(II)-iron(III) formate precursors, a rigorous control of nickel ion concentration in the precursor solution was required. The decomposition of the reactive nickel(II)-iron(III) formate does not only reflect aspects of single formates, but also an interaction between components which lowers the decomposition temperature. Crystalline nickel ferrite powders were obtained at 600-800°C. This temperature is quite lower than 1100°C employed for the ceramic method. In the presence of air, the regeneration of nickel ferrite from the taenite phase (,Ni,Fe) is accomplished at 800°C. This temperature is also 300°C below the temperature employed when the mixtures NiO:,-Fe2O3 or Ni:2Fe are the starting powders. The main reason for the high reactivity of the freeze-dried formates and the taenite alloy is the large homogeneity of these precursors. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Highly Sensitive Electrogenerated Chemiluminescence Detecting Ranitidine Based On Chemically Modifying Microenvironment of the Chemiluminescence ReactionELECTROANALYSIS, Issue 11 2005Xingwang Zheng Abstract Using a graphite electrode modified with vaseline and NiO, ranitidine showed a strongly ECL enhancing effect for the weak ECL signal of electrooxidation of luminol. Based on this finding, a more sensitive ECL method for ranitidine was firstly proposed. Under the optimum experimental conditions, the ranitidine hydrochloride concentration in the range of 3.0×10,8,9.0×10,6,mol/L was proportional to the enhancing ECL signal and offered a 9×10,9,mol/L detection limit for ranitidine hydrochloride. At the same time, based on the investigation on this ECL reaction mechanism, a new concept, to improve the suitable ECL reaction micro-environment with chemically modified electrode technique for the better analytical performances of ECL analysis was also firstly proposed. [source] Formation of Nickel Oxide Nanotubes with Uniform Wall Thickness by Low-Temperature Thermal Oxidation Through Understanding the Limiting Effect of Vacancy Diffusion and the Kirkendall PhenomenonADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Yi Ren Abstract In this work, the step-wise oxidation mechanism of nickel (Ni) nanowires is elucidated. Rapid vacancy diffusion plays a significant role at low temperatures in forming heterostructures of nickel oxide (NiO) nanotubes with Ni nanowires. Subsequent investigations of Ni nanowire oxidation at higher temperatures and faster temperature ramp rates show that it is difficult to bypass this rapid vacancy diffusion stage, which affects the formation of the final structure. Therefore, it is unlikely to form solid NiO nanowires or NiO nanotubes with uniform wall thickness through the conventional annealing/oxidation process of Ni nanowires. Instead, a step-wise oxidation process by combining low temperature oxidation with a chemical etching step is utilized to produce for the first time NiO nanotubes with uniform wall thickness from Ni nanowires. [source] Fine-microstructure Mediated Efficient Hydrogen Oxidation in Ni/YSZ Anode Fabricated from Novel Co-precipitation Derived NanocompositesFUEL CELLS, Issue 2 2010K. Sato Abstract Fine-microstructure mediated efficient hydrogen oxidation was demonstrated on nickel/yttria-stabilised zirconia (Ni/YSZ) anode fabricated from NiO/YSZ nanocomposite particles, synthesised via a novel co-precipitation method using YSZ nanoparticles with the average size of 3,nm. Transmission electron microscopy image revealed that nanocomposite particles calcined at 600,°C consisted of homogeneously distributed NiO and YSZ nanocrystals, approximately 5,nm large. The Ni/YSZ anode was fabricated by sintering the screen-printed nanocomposites at 1,300,°C and their subsequent reduction. The anode had a uniform porous microstructure consisting of fine grains in the range of 200,300,nm, and exhibited quite low area-specific resistance (ASR) of 2.29, 0.43 and 0.15,,,cm2 at 600, 700 and 800,°C, respectively. [source] Reactivity in LaGaO3/Ni and CeO2/Ni SystemsFUEL CELLS, Issue 2 2006N. Solak Abstract The reactivity in CeO2/Ni and LaGaO3/Ni systems, which are constituents of intermediate temperature solid oxide fuel cell (IT-SOFC) anodes, has been investigated both computationally and experimentally. The CALPHAD-method (CALculating of PHAse Diagrams), employing BINGSS and THERMOCALC software, was used to obtain a self-consistent set of Gibbs energy functions describing the systems. Interactions in the LaGaO3/Ni system were predicted using a thermodynamic database developed for the La-Ga-Ni-O system. Similarly, to analyze the CeO2/Ni system, the Ce-Ni-O ternary phase diagram was calculated using known thermodynamic data for binary Ce-O, Ni-O, and Ce-Ni systems. The experimental work was designed based on the calculated phase diagrams. While the La-Ga-Ni-O system experiments were conducted in air, the Ce-Ni-O system was also investigated in a reducing atmosphere. The calculated Ce-Ni-O diagram is in good agreement with the experimental results. It has been found that NiO does not react with CeO2. Extended solid solutions of La(Ga,Ni)O3, La2(Ni,Ga)O4, and La4(Ni,Ga)3O10 were found in the La-Ga-Ni-O system. Additionally, the compound LaNiGa11O19, with magnetoplumbite-type structure, has been found, which has not been reported in the literature so far. It is concluded that La2NiO4 is not chemically compatible, as a cathode material, with the LSGM electrolyte. [source] Low-Temperature-Grown Transition Metal Oxide Based Storage Materials and Oxide Transistors for High-Density Non-volatile MemoryADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Myoung-Jae Lee Abstract An effective stacked memory concept utilizing all-oxide-based device components for future high-density nonvolatile stacked structure data storage is developed. GaInZnO (GIZO) thin-film transistors, grown at room temperature, are integrated with one-diode (CuO/InZnO),one-resistor (NiO) (1D,1R) structure oxide storage node elements, fabricated at room temperature. The low growth temperatures and fabrication methods introduced in this paper allow the demonstration of a stackable memory array as well as integrated device characteristics. Benefits provided by low-temperature processes are demonstrated by fabrication of working devices over glass substrates. Here, the device characteristics of each individual component as well as the characteristics of a combined select transistor with a 1D,1R cell are reported. X-ray photoelectron spectroscopy analysis of a NiO resistance layer deposited by sputter and atomic layer deposition confirms the importance of metallic Ni content in NiO for bi-stable resistance switching. The GIZO transistor shows a field-effect mobility of 30,cm2,V,1,s,1, a Vth of +1.2,V, and a drain current on/off ratio of up to 108, while the CuO/InZnO heterojunction oxide diode has forward current densities of 2,×,104,A,cm,2. Both of these materials show the performance of state-of-the-art oxide devices. [source] High Incident Photon-to-Current Conversion Efficiency of p-Type Dye-Sensitized Solar Cells Based on NiO and Organic ChromophoresADVANCED MATERIALS, Issue 29 2009Peng Qin The synthesis and characterization of an organic dye, P4, together with its performance in p-type dye-sensitized solar cells (DSSCs) is presented. A solar-cell device based on P4 and an electrolyte that contains the I,/I3, couple in acetonitrile yielded an IPCE value of 44% on a transparent NiO film only 1,1.4,,m thick, the highest value obtained so far. [source] Monodisperse Nanoparticles of Ni and NiO: Synthesis, Characterization, Self-Assembled Superlattices, and Catalytic Applications in the Suzuki Coupling Reaction,ADVANCED MATERIALS, Issue 4 2005J. Park Monodisperse spherical Ni nanoparticles with diameters of 2 nm, 5 nm, and 7 nm were synthesized from the thermal decomposition of a Ni,oleylamine complex. Ni nanocrystal superlattices were generated via the controlled evaporation of solvent (see Figure). The nanoparticles were successfully used as catalysts for the Suzuki coupling reaction, and were readily oxidized to produce NiO nanoparticles. [source] Porous structure of NiO-based xerogelsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2000H. Fischer NiO-based xerogels were prepared by sol-gel processing starting from the NiCl2 -BuOH-H2O system. Structural features associated to the porosity of xerogels were studied by small-angle X-ray scattering. Xerogels heat-treated at low temperatures (423 and 573 K) are composed of hydrated NiCl2 small crystals and exhibit an essentially single mode nanoporous structure with an average pore radius of ,75 Å. Xerogels heat-treated at 973 and 1173 K are composed of aggregates of NiO crystals which only contain intergrain mesopores with radii exceeding 200 Å. A mixture of phases is observed in xerogels heat-treated at 773 K. Xerogels with a water concentration of 2 mol/(mol NiCl2) exhibit a narrow nanopore size distribution. Water concentrations higher or lower than 2 mol promote the formation of nanoporous structures with wider size distributions. [source] Fe2O3 on Ce-, Ca-, or Mg-stabilized ZrO2 as oxygen carrier for chemical-looping combustion using NiO as additiveAICHE JOURNAL, Issue 8 2010Magnus Rydén Abstract Oxygen-carrier particles for chemical-looping combustion have been manufactured by freeze granulation. The particles consisted of 60 wt % Fe2O3 as active phase and 40 wt % stabilized ZrO2 as support material. Ce, Ca, or Mg was used to stabilize the ZrO2. The hardness and porosity of the particles were altered by varying the sintering temperature. The oxygen carriers were examined by redox experiments in a batch fluidized-bed reactor at 800,950°C, using CH4 as fuel. The experiments showed good reactivity between the particles and CH4. NiO was used as an additive and was found to reduce the fraction of unconverted CH4 with up to 80%. The combustion efficiency was 95.9% at best and was achieved using 57 kg oxygen carrier per MW fuel. Most produced oxygen carriers appear to have been decently stable, but using Ca as stabilizer resulting in uneven results. Further, particles sintered at high temperatures had a tendency to defluidize. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Chemical-looping combustion process: Kinetics and mathematical modelingAICHE JOURNAL, Issue 4 2010Ion Iliuta Abstract Chemical Looping Combustion technology involves circulating a metal oxide between a fuel zone where methane reacts under anaerobic conditions to produce a concentrated stream of CO2 and water and an oxygen rich environment where the metal is reoxidized. Although the needs for electrical power generation drive the process to high temperatures, lower temperatures (600,800°C) are sufficient for industrial processes such as refineries. In this paper, we investigate the transient kinetics of NiO carriers in the temperature range of 600 to 900°C in both a fixed bed microreactor (WHSV = 2-4 g CH4/h/g oxygen carrier) and a fluid bed reactor (WHSV = 0.014-0.14 g CH4/h per g oxygen carrier). Complete methane conversion is achieved in the fluid bed for several minutes. In the microreactor, the methane conversion reaches a maximum after an initial induction period of less than 10 s. Both CO2 and H2O yields are highest during this induction period. As the oxygen is consumed, methane conversion drops and both CO and H2 yields increase, whereas the CO2 and H2O concentrations decrease. The kinetics parameter of the gas,solids reactions (reduction of NiO with CH4, H2, and CO) together with catalytic reactions (methane reforming, methanation, shift, and gasification) were estimated using experimental data obtained on the fixed bed microreactor. Then, the kinetic expressions were combined with a detailed hydrodynamic model to successfully simulate the comportment of the fluidized bed reactor. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Noninvasive in vivo electron paramagnetic resonance study to estimate pulmonary reducing ability in mice exposed to NiO or C60 nanoparticlesJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 6 2009Hidekatsu Yokoyama MD Abstract Purpose To develop new methods that can estimate the influences of manufactured nanomaterials on biological systems, the in vivo pulmonary reducing ability of mice that had received inhalation exposures to NiO or C60 nanoparticles was investigated using a 700 MHz electron paramagnetic resonance (EPR) spectrometer. Materials and Methods NiO or C60 suspensions were atomized and mice in exposure chambers inhaled the resulting aerosol particles for 3 hours. The exposure conditions, number-based geometric average diameters, and the average number concentration were precisely controlled at almost the same levels for both NiO and C60 nanoparticles. Two days or 2 weeks after exposure, an EPR study was conducted noninvasively. Temporal changes in EPR signal intensity at the target area (ie, lung field) were obtained by the region-selected intensity determination (RSID) method. Results NiO nanoparticles significantly suppressed pulmonary reducing ability 2 days and 2 weeks after exposure, but C60 nanoparticles had no such effect. Conclusion This is the first in vivo estimation of the reducing ability in experimental animals exposed to manufactured nanoparticles. J. Magn. Reson. Imaging 2009. © 2009 Wiley-Liss, Inc. [source] Novel Fabrication of Ca-Doped LaNbO4 Thin-Film Proton-Conducting Fuel Cells by Pulsed Laser DepositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2010Anna Magrasó Thin films of 0.5% Ca-doped La0.995Ca0.005NbO4,, (LCNO) proton-conducting electrolytes of ,2 ,m thickness were obtained by pulsed laser deposition on NiO,LaNbO4 composite substrates. The morphology of the films was granular after annealing at T,1000°C and evolved to spherical-like grains at 1100°C and above. The structure and composition of the films were characterized by X-ray diffraction and X-ray photoelectron spectrocopy. LCNO films showed the monoclinic fergusonite-type structure at room temperature. The area-specific resistance for a ,2-,m-thick electrolyte was in the order of 0.4 ,·cm2 at 600°C based on estimates of the electrode area. Temperature dependency of the electrical conductivity at 600°,700°C was comparable with that of bulk disks of the material. [source] Fabrication of Thin-Film SrCe0.9Eu0.1O3,, Hydrogen Separation Membranes on Ni,SrCeO3 Porous Tubular SupportsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Heesung Yoon SrCe0.9Eu0.1O3,, thin-film (,30 ,m) tubular hydrogen separation membranes were developed in order to obtain high hydrogen fluxes. Fifteen centimeters long, one end closed, NiO,SrCeO3 tubular supports were fabricated by tape casting, followed by rolling the green tape on a circular rod. SrCe0.9Eu0.1O3,, powders were prepared by the citrate process and coated on partially sintered NiO,SrCeO3 tubular supports. Leakage-free hydrogen membrane cells were obtained by adjusting the presintering and final sintering temperatures to reduce the difference of linear shrinkage rates between SrCe0.9Eu0.1O3,, thin films and NiO,SrCeO3 supports. A hydrogen flux of 2.2 cm3/min was obtained for the SrCe0.9Eu0.1O3,, on Ni,SrCeO3 tubular hydrogen separation membranes at 900°C using 25% H2 balanced with Ar and 3% H2O as the feed gas and He as the sweep gas. Thus, a 40% single pass yield of pure H2 was achieved with this membrane. [source] YSZ-Induced Crystallographic Reorientation of Ni Particles in Ni,YSZ CermetsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007Miguel A. Laguna-Bercero Metal,ceramic interfaces in Ni,YSZ (YSZ, yttria-stabilized zirconia)-textured porous cermets prepared by reduction of NiO,YSZ directionally solidified eutectics have been studied by transmission electron microscopy and X-ray pole figure experiments. Before reduction of NiO, the interfacial plane isbut after reduction, the Ni phase does not maintain the same crystallographic orientation as the NiO parent phase. Ni undergoes an interface-induced crystallographic reorientation to form the lower energy (002)Ni,(002)YSZ interface. This process has been studied as a function of the reduction temperature, and it seems to be more effective at ,800°C. Metal,ceramic low-energy interfaces prevent Ni particle coarsening and impart long-term stability to the cermet. [source] Preparation of Matrix-Type Nickel Oxide/Samarium-Doped Ceria Composite Particles by Spray PyrolysisJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2007Seiichi Suda Matrix-type nickel oxide (NiO)/samarium-doped ceria (SDC) composite particles, in which NiO and SDC nano-particles were homogeneously dispersed, were synthesized by spray pyrolysis (SP) for an anode precursor of intermediate-temperature solid oxide fuel cells (IT-SOFCs). SP of an aqueous solution containing Ni, Ce, and Sm salts resulted in capsule-type composite particles that had NiO enveloped with SDC. The capsule-type composite particles actually prevent Ni aggregation between particles, but they cannot have a large contact area between nickel (Ni) and SDC. A matrix-type composite particle is expected to have a large contact area because the matrix-type composite is comprised of nanometer-sized Ni and SDC particles. An adequate addition of ethylene glycol successfully resulted in matrix-type NiO/SDC composite particles. The matrix-type composite particles also showed higher anode performance than the capsule-type composite particles in these experiments and they were effective as precursors of high-performance IT-SOFC anodes. [source] Preparation of a Porous Cermet SOFC Anode Substrate by Gelcasting of NiO,YSZ PowdersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2007Kuttan Prabhakaran A porous NiO,YSZ substrate for anode-supported solid oxide fuel cells has been prepared by gelcasting of NiO,YSZ powders using urea,formaldehyde monomers, followed by humidity-controlled drying, binder removal, and sintering of the gelled bodies. The gelled bodies had sufficient strength to remove even 2-mm-thick samples from the mold immediately after gelation. A gelcast NiO,YSZ sample sintered at 1450°C for 2 h showed an open porosity of ,53 vol%, and the porosity increased to ,58% upon reduction with hydrogen. Pore sizes measured on the scanning electron microscopy photomicrograph of NiO,YSZ and Ni,YSZ cermet substrates are in the range of 2,5 ,m. Urea,formaldehyde polymer, present in a high amount (,13 wt%) in the gelcast body, acts as a template for pores. [source] Electrophoretic Deposition of YSZ Particles on Non-Conducting Porous NiO,YSZ Substrates for Solid Oxide Fuel Cell ApplicationsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2006Laxmidhar Besra This paper reports a method of performing electrophoretic deposition (EPD) on non-conducting substrates overcoming the requirement of a conducting substrate through the use of porous substrates. The conductivity of the substrate is therefore no longer a limiting factor in the application of EPD. This method is applicable to the fabrication of thick or thin layers of ceramic or metal for various applications. As an example, thin and dense yttria-stabilized zirconia (YSZ) layers have been deposited on a non-conducting NiO,YSZ substrate by EPD from a non-aqueous suspension. A solid oxide fuel cell constructed on these sintered bilayers exhibited power densities of 384 and 611 mW/cm2 at 750° and 850°C, respectively. [source] Preparation of NiAl2O4/SiO2 and Co2+ -Doped NiAl2O4/SiO2 Nanocomposites by the Sol,Gel RouteJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2006I. Prakash NiAl2O4/SiO2 and Co2+ -doped NiAl2O4/SiO2 nanocomposite materials of compositions 5% NiO , 6% Al2O3, 89% SiO2 and 0.2% CoO , 4.8% NiO , 6% Al2O3, 89% SiO2, respectively, were prepared by a sol,gel process. NiAl2O4 and cobalt-doped NiAl2O4 nanocrystals were grown in a SiO2 amorphous matrix at around 1073 K by heating the dried gels from 333 to 1173 K at the rate of 1 K/min. The formations of NiAl2O4 and cobalt-doped NiAl2O4 nanocrystals in SiO2 amorphous matrix were confirmed through X-ray powder diffraction, Fourier transform infrared spectroscopy, differential scanning calorimeter, transmission electron microscopy (TEM), and optical absorption spectroscopy techniques. The TEM images revealed the uniform distribution of NiAl2O4 and cobalt-doped NiAl2O4 nanocrystals in the amorphous SiO2 matrix and the size was found to be ,5,8 nm. [source] Synthesis of Biomorphous Nickel Oxide from a Pinewood Template and Investigation on a Hierarchical Porous StructureJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2006Zhaoting Liu The hydrothermal synthesis of biomorphous nickel oxide (NiO) with pine template and nickel nitrate precursor is reported here. The morphology, porosity and connectivity of porous products in different length scales were characterized by field emission scanning electron microscopy, X-ray diffraction and nitrogen adsorption measurements. Their porous structures were found to be hierarchical from 1 up to 25 ,m (in micrometer scale) and from 2 nm to 60 nm (in nanometer scale). Furthermore, depending on the heat-treatment temperatures, the porosity of the pine-templated NiO can be designed. [source] Fabrication of NiO Nanoparticle-Coated Lead Zirconate Titanate Powders by the Heterogeneous Precipitation MethodJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2003Ping-Hua Xiang NiO nanoparticle-coated lead zirconate titanate (PZT) powders are successfully fabricated by the heterogeneous precipitation method using PZT, Ni(NO3)2·6H2O, and NH4HCO3 as the starting materials. The amorphous NiCO3·2Ni(OH)2·2H2O are uniformly coated on the surface of PZT particles. XRD analysis and the selected-area diffraction (SAD) pattern indicate that the amorphous coating layer is crystallized to NiO after being calcined at 400°C for 2 h. TEM images show that the NiO particles of ,8 nm are spherical and weakly agglomerated. The thickness of the nanocrystalline NiO coating layer on the surface of PZT particle is ,30 nm. [source] Optimization of a Composite Working Electrode for a New Family of Electrochemical Cell for NO DecompositionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2003Kazuyuki Matsuda The electrochemical properties of a composite (NiO)x,(yttria-stabilized zirconia (YSZ))1,x working electrode for a new type of electrochemical cell for NO decomposition in the presence of excess oxygen are investigated. It is shown that the dependence of the NO conversion on the value of the current passed through the electrochemical cell with a nanoporous (NiO)x,(YSZ)1,x working electrode is linear and that the value of current efficiency depends on the NO and O2 gas concentrations only (,= [NO] /([NO] + 2[O2]). The optimum NiO addition (35% by volume) to the YSZ resulted in a decrease of the cell operating voltage and, as a result, in a decrease in the electrical power required for NO decomposition. The observed high performance of the composite working electrode at this composition is consistent with the effective medium percolation theory, which predicts the ambipolar transport behavior of the composite mixed ionic,electronic (YSZ,NiO) conductors as a function of the volume fraction of each of the randomly distributed constituent phases. [source] Synthesis of Highly Porous Yttria-Stabilized Zirconia by Tape-Casting MethodsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2003Martha Boaro Porous ceramics of Y2O3 -stabilized ZrO2 (YSZ) were prepared by tape-casting methods using both pyrolyzable pore formers and NiO followed by acid leaching. The porosity of YSZ wafers increased in a regular manner with the mass of graphite or polymethyl methacrylate (PMMA) to between 60% and 75% porosity. SEM indicated that the shape of the pores in the final ceramic was related to the shape of the pore formers, so that the pore size and microstructure of YSZ wafers could be controlled by the choice of pore former. Dilatometry measurements showed that measurable shrinkage started at 1300 K, and a total shrinkage of 26% was observed, independent of the amount or type of pore former used. Temperature-programmed oxidation (TPO) measurements on the green tapes demonstrated that the binders and dispersants were combusted between 550 and 750 K, that PMMA decomposed to methyl methacrylate between 500 and 700 K, and that graphite combusted above 900 K. The porosity of YSZ ceramics prepared by acid leaching of nickel from NiO,YSZ, with 50 wt% NiO, was studied as a function of NiO and YSZ particle size. Significant changes in pore dimension were found when NiO particle size was changed. [source] Solid-Solution Effects of a Small Amount of Nickel Oxide Addition on Phase Stability and Mechanical Properties of Yttria-Stabilized Tetragonal Zirconia PolycrystalsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2003Hiroki Kondo Stability and mechanical properties of the tetragonal phase were investigated for NiO-doped yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) systems. Only 0.3 mol% of NiO in solid solution could be added to the Y-TZP while maintaining the tetragonal phase. Fracture toughness improved remarkably on addition of a small amount of NiO. Raman spectroscopy analysis around cracks introduced by Vickers indentation revealed that the amount of monoclinic phase transformed from tetragonal phase was increased. It was confirmed that fracture toughness improvement was due not only to increased grain size, but also to Y-TZP destabilization by solid solution of NiO. [source] Zirconia-Based Metastable Solid Solutions through Self-Propagating High-Temperature Synthesis: Synthesis, Characterization, and Mechanistic InvestigationsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2000Filippo Maglia Cubic Zr1,xMexOy(Me = Fe, Co, Ni, Cu) metastable solid solutions with metal content significantly higher than equilibrium levels have been synthesized by the self-propagating high-temperature synthesis method based on a thermite reaction between metallic zirconium and the transition-metal oxides CoO, Fe2O3, CuO, and NiO. Through in situ XRD analysis, it was determined that when heated to 1100°C, the cubic solid solution transformed to the tetragonal phase with the concomitant formation of iron oxide. When cooled to lower temperatures, the tetragonal phase transformed to the monoclinic phase at or below 500°C. Results of auxiliary experiments strongly suggest that the formation of the solid solution takes place behind the combustion front by a reaction between zirconia and the metal. [source] NiO-induced crystallization and optical characteristics of Li2O,CaF2,P2O5 glass systemPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2008G. Murali Krishna Abstract Li2O,CaF2,P2O5 glasses mixed with different concentrations of NiO (ranging from 0 mol% to 2.0 mol%) were crystallized. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy and differential thermal analysis. Studies were extended to optical absorption and magnetic susceptibility of these glass ceramic samples. The XRD and SEM studies reveal the presence of lithium phosphate, calcium phosphate and nickel phosphate crystal phases. The optical absorption studies together with magnetic susceptibility measurements indicate a gradual transformation of nickel ions from tetrahedral sites to octahedral sites (lasing sites) as the concentration of NiO is increased beyond 0.8 mol%. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||