The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Lionel Roue - One of the best experts on this subject based on the ideXlab platform.
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nitrate removal by a paired electrolysis on copper and ti iro2 coupled electrodes influence of the anode cathode Surface Area Ratio
Water Research, 2010Co-Authors: David Reyter, Daniel Belanger, Lionel RoueAbstract:In this study, nitrate removal in alkaline media by a paired electrolysis with copper cathode and Ti/IrO(2) anode enabled the conversion of nitrate to nitrogen. Optimum conditions for carrying out reduction of nitrate to ammonia and subsequent oxidation of the produced ammonia to nitrogen were found. At the copper cathode, electroreduction of nitrate to ammonia was optimal near -1.4 V vs Hg/HgO. At the Ti/IrO(2) anode, a pH value of 12, the presence of chloride and a potential fixed around 2.3 V vs Hg/HgO permitted the production of hypochlorite, leading to the oxidation of ammonia to nitrogen with a N(2) selectivity of 100%. Controlling the cathode/anode Surface Area Ratio, and thus the current density, appeared to be a very efficient way of shifting electrode potentials to optimal values, consequently favoring the conversion of nitrate to nitrogen during a paired galvanostatic electrolysis. A cathode/anode Surface Area Ratio of 2.25 was shown to be the most efficient to convert nitrate to nitrogen.
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Nitrate removal by a paired electrolysis on copper and Ti/IrO2 coupled electrodes – Influence of the anode/cathode Surface Area Ratio
Water research, 2009Co-Authors: David Reyter, Daniel Belanger, Lionel RoueAbstract:In this study, nitrate removal in alkaline media by a paired electrolysis with copper cathode and Ti/IrO(2) anode enabled the conversion of nitrate to nitrogen. Optimum conditions for carrying out reduction of nitrate to ammonia and subsequent oxidation of the produced ammonia to nitrogen were found. At the copper cathode, electroreduction of nitrate to ammonia was optimal near -1.4 V vs Hg/HgO. At the Ti/IrO(2) anode, a pH value of 12, the presence of chloride and a potential fixed around 2.3 V vs Hg/HgO permitted the production of hypochlorite, leading to the oxidation of ammonia to nitrogen with a N(2) selectivity of 100%. Controlling the cathode/anode Surface Area Ratio, and thus the current density, appeared to be a very efficient way of shifting electrode potentials to optimal values, consequently favoring the conversion of nitrate to nitrogen during a paired galvanostatic electrolysis. A cathode/anode Surface Area Ratio of 2.25 was shown to be the most efficient to convert nitrate to nitrogen.
Tibor T Glant - One of the best experts on this subject based on the ideXlab platform.
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Effects of particles on fibroblast prolifeRation and bone resorption in vitro.
Clinical orthopaedics and related research, 1997Co-Authors: Arun S Shanbhag, Joshua J Jacobs, Jonathan Black, Jorge O Galante, Tibor T GlantAbstract:An in vitro study was conducted to determine the ability of particle challenged human peripheral monocytes to modulate fibroblast prolifeRation and bone resorption. The effects of commercially pure titanium, titanium-aluminum-vanadium, and ultrahigh molecular weight polyethylene wear debris, either fabricated or retrieved from patients with failed total hip arthroplasties, were examined as a function of the composition, size, and dose of particles. In vitro generated particles were selected to be matched closely in particle size distribution to that found in vivo. Dosages were controlled by standardizing the Ratio of particle Surface Area to mean monocyte Surface Area. The results support the hypothesis that, in vitro, challenge of monocytes by particulate wear debris results in a biphasic dose response. For the metal particles, fibrogenesis was observed over the range of 1x to 10x Surface Area Ratio (the Surface Area of particles to the Surface Area of cells), although for metallic and polyethylene particles, saturated doses of 10x Surface Area Ratio were required to stimulate bone resorption. In addition, metallic particles were able to stimulate fibrogenesis at doses at which simulated and retrieved polyethylene were ineffective. Although there may be a nonosteolytic chronically tolerable annual dose of ultrahigh molecular weight polyethylene wear debris corresponding to approximately 1x Surface Area Ratio, lower doses, especially of metallic debris, may produce reactive fibroblast prolifeRation and fibroplasia that may contribute to implant loosening and failure.
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macrophage particle interactions effect of size composition and Surface Area
Journal of Biomedical Materials Research, 1994Co-Authors: Arun S Shanbhag, Joshua J Jacobs, Jonathan Black, Jorge O Galante, Tibor T GlantAbstract:Particulate wear-debris are detected in histiocytes/macrophages of granulomatous tissues adjacent to loose joint prostheses. Such cell-particle interactions have been simulated in vitro by challenging macrophages with particles dosed according to weight percent, volume percent, and number of particles. Each of these dosage methods has inherent shortcomings due to varying size and density of challenging particles of different compositions. In this study we challenged P388D1 macrophages with titania and polystyrene particles (< 2 microns), with dosage based on the Ratio of the Surface Area of the particles to the Surface Area of the cells. The effect of size and composition on (1) the bone resorbing activity, (2) fibroblast prolifeRation, and (3) secretion of IL-1 and PGE2 was determined. Macrophage response to particulate debris appears to be dependent on particle size, composition, and dose as given by Surface Area Ratio. P388D1 macrophages challenged with titania particles released IL-1, but did not stimulate fibroblasts. Inhibition of macrophage DNA synthesis at higher Surface Area Ratios suggests cell damage or death. Particle-stimulated cells increased bone resorption up to 125% of controls but released only basal levels of PGE2. Macrophages stimulated by wear particles are expected to synthesize numerous factors affecting events in the bone-implant interface. Using the concept of Surface Area Ratio allows us to study and compare such cellular responses to wear particles in a standardized manner.
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Macrophage/particle interactions: Effect of size, composition and Surface Area
Journal of biomedical materials research, 1994Co-Authors: Arun S Shanbhag, Joshua J Jacobs, Jonathan Black, Jorge O Galante, Tibor T GlantAbstract:Particulate wear-debris are detected in histiocytes/macrophages of granulomatous tissues adjacent to loose joint prostheses. Such cell-particle interactions have been simulated in vitro by challenging macrophages with particles dosed according to weight percent, volume percent, and number of particles. Each of these dosage methods has inherent shortcomings due to varying size and density of challenging particles of different compositions. In this study we challenged P388D1 macrophages with titania and polystyrene particles (< 2 microns), with dosage based on the Ratio of the Surface Area of the particles to the Surface Area of the cells. The effect of size and composition on (1) the bone resorbing activity, (2) fibroblast prolifeRation, and (3) secretion of IL-1 and PGE2 was determined. Macrophage response to particulate debris appears to be dependent on particle size, composition, and dose as given by Surface Area Ratio. P388D1 macrophages challenged with titania particles released IL-1, but did not stimulate fibroblasts. Inhibition of macrophage DNA synthesis at higher Surface Area Ratios suggests cell damage or death. Particle-stimulated cells increased bone resorption up to 125% of controls but released only basal levels of PGE2. Macrophages stimulated by wear particles are expected to synthesize numerous factors affecting events in the bone-implant interface. Using the concept of Surface Area Ratio allows us to study and compare such cellular responses to wear particles in a standardized manner.
Klaus J. Hüttinger - One of the best experts on this subject based on the ideXlab platform.
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chemistry and kinetics of chemical vapor deposition of pyrocarbon v influence of reactor volume deposition Surface Area Ratio
Carbon, 1998Co-Authors: A. Becker, Klaus J. HüttingerAbstract:Abstract Pyrocarbon deposition from methane was studied at ambient pressure and a temperature of 1100 °C using a vertical hot-wall reactor with a honeycomb structure as substrate. Compared to the deposition tube used in previous studies this substrate exhibits a 15-fold increase in Surface Area. The methane initial partial pressure was varied up to 75 kPa, and the residence time up to 1 second. The results are compared with those obtained with the tube. The Surface Area is shown to decisively influence the chemistry and kinetics of deposition reactions and thus also the major growth species of pyrocarbon. With residence time increasing from zero to one second the Ratio of Surface-related pyrocarbon deposition rates obtained with tube and honeycomb structure vary by a factor of about 18. With increasing initial partial pressure, deposition rates tend to approach a limiting value indicating satuRation adsorption. Pyrocarbon deposition rates as a function of residence time and initial partial pressure have been simulated considering complex homogeneous and heterogeneous reactions.
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Chemistry and kinetics of chemical vapor deposition of pyrocarbon — V influence of reactor volume/deposition Surface Area Ratio
Carbon, 1998Co-Authors: A. Becker, Klaus J. HüttingerAbstract:Abstract Pyrocarbon deposition from methane was studied at ambient pressure and a temperature of 1100 °C using a vertical hot-wall reactor with a honeycomb structure as substrate. Compared to the deposition tube used in previous studies this substrate exhibits a 15-fold increase in Surface Area. The methane initial partial pressure was varied up to 75 kPa, and the residence time up to 1 second. The results are compared with those obtained with the tube. The Surface Area is shown to decisively influence the chemistry and kinetics of deposition reactions and thus also the major growth species of pyrocarbon. With residence time increasing from zero to one second the Ratio of Surface-related pyrocarbon deposition rates obtained with tube and honeycomb structure vary by a factor of about 18. With increasing initial partial pressure, deposition rates tend to approach a limiting value indicating satuRation adsorption. Pyrocarbon deposition rates as a function of residence time and initial partial pressure have been simulated considering complex homogeneous and heterogeneous reactions.
David Reyter - One of the best experts on this subject based on the ideXlab platform.
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nitrate removal by a paired electrolysis on copper and ti iro2 coupled electrodes influence of the anode cathode Surface Area Ratio
Water Research, 2010Co-Authors: David Reyter, Daniel Belanger, Lionel RoueAbstract:In this study, nitrate removal in alkaline media by a paired electrolysis with copper cathode and Ti/IrO(2) anode enabled the conversion of nitrate to nitrogen. Optimum conditions for carrying out reduction of nitrate to ammonia and subsequent oxidation of the produced ammonia to nitrogen were found. At the copper cathode, electroreduction of nitrate to ammonia was optimal near -1.4 V vs Hg/HgO. At the Ti/IrO(2) anode, a pH value of 12, the presence of chloride and a potential fixed around 2.3 V vs Hg/HgO permitted the production of hypochlorite, leading to the oxidation of ammonia to nitrogen with a N(2) selectivity of 100%. Controlling the cathode/anode Surface Area Ratio, and thus the current density, appeared to be a very efficient way of shifting electrode potentials to optimal values, consequently favoring the conversion of nitrate to nitrogen during a paired galvanostatic electrolysis. A cathode/anode Surface Area Ratio of 2.25 was shown to be the most efficient to convert nitrate to nitrogen.
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Nitrate removal by a paired electrolysis on copper and Ti/IrO2 coupled electrodes – Influence of the anode/cathode Surface Area Ratio
Water research, 2009Co-Authors: David Reyter, Daniel Belanger, Lionel RoueAbstract:In this study, nitrate removal in alkaline media by a paired electrolysis with copper cathode and Ti/IrO(2) anode enabled the conversion of nitrate to nitrogen. Optimum conditions for carrying out reduction of nitrate to ammonia and subsequent oxidation of the produced ammonia to nitrogen were found. At the copper cathode, electroreduction of nitrate to ammonia was optimal near -1.4 V vs Hg/HgO. At the Ti/IrO(2) anode, a pH value of 12, the presence of chloride and a potential fixed around 2.3 V vs Hg/HgO permitted the production of hypochlorite, leading to the oxidation of ammonia to nitrogen with a N(2) selectivity of 100%. Controlling the cathode/anode Surface Area Ratio, and thus the current density, appeared to be a very efficient way of shifting electrode potentials to optimal values, consequently favoring the conversion of nitrate to nitrogen during a paired galvanostatic electrolysis. A cathode/anode Surface Area Ratio of 2.25 was shown to be the most efficient to convert nitrate to nitrogen.
Lesley Lovettdoust - One of the best experts on this subject based on the ideXlab platform.
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biomonitoring site quality in stressed aquatic ecosystems using vallisneria americana
Ecological Applications, 2001Co-Authors: Kelly Potter, Lesley LovettdoustAbstract:Leaf-to-root Surface Area Ratios in Vallisneria americana have been shown to provide a simple and inexpensive relative measure of sublethal effects of organochlorine contamination. The present study was conducted to determine whether this index of Surface Area could be used as an effective biomonitor of overall site quality in stressed aquatic ecosystems. The leaf-to-root Surface Area Ratio was determined for samples of V. americana collected from 225 microsites within 12 Areas of Concern (environmentally contaminated Areas designated by the International Joint Commission) throughout the Laurentian Great Lakes of Ontario. Statistical analyses indicate that 77% of the variation in the Surface Area index could be attributed to differences among microsites, with only 23% of variation occurring among plants within a microsite. A multiple regression equation was developed for predicting the leaf-to-root Surface Area Ratio from several measures of microsite quality. Significant parameters affecting the Surface Area Ratio included plant density, light intensity, and an index of sediment contamination. In contrast, measures of water contamination did not show any correlation with leaf-to-root Surface Area Ratio. These observations support the hypothesis that V. americana accumulates contaminants primarily from the sediments and that the leaf-to-root Surface Area Ratio can be used to construct contours of point source impact zones in Areas of Concern. The regression model developed here provides a simple, inexpensive means for monitoring overall site quality throughout the Great Lakes.
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laboratory assay of sediment phytotoxicity using the macrophyte vallisneria americana
Environmental Toxicology and Chemistry, 1997Co-Authors: Maciej Biernacki, Jon Lovettdoust, Lesley LovettdoustAbstract:In contrast to their ecological importance, submersed rooted macrophytes have been overlooked in environmental science. Presently, the array of standard phytotoxic bioassays includes only one free-floating vascular macrophyte (Lemna) and several algal species. A short-term and inexpensive assay was studied for feasibility in evaluating sediment quality. Cloned ramets of the macrophyte Vallisneria americana were used to test phytotoxicity of sediments collected at different locations in the Detroit River. Ramets were planted in sediment samples and placed in greenhouse aquaria. After a week of exposure, ramets of V. americana were destructively sampled and preserved. The leaf and root Surfaces Areas were determined, and plant biomass was recorded for each ramet. An index of the leaf-to-root Surface Area Ratio was a reliable predictor of sediment phytotoxicity; the Ratio of leaf-to-root mass was also useful but proved less consistent. Ramets grown in sediments that were relatively less contaminated with organic compounds had lower values of the leaf-to-root Surface Area Ratio, while plants grown in more contaminated sediments had greater values. Results of analyses of variance indicated that the index of leaf-to-root Surface Area Ratio responded to sediment quality but was not significantly affected by either variation in plant genotype or interaction between sediment and plant genotype. There was a significant correlation (p < 0.001) between rank-ordered results of the present greenhouse study and results of leaf-to-root Surface Area Ratios for plants previously surveyed in the field.
