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Sample records for acid anodized caa

  1. Chromic acid anodizing of aluminum foil

    NASA Technical Reports Server (NTRS)

    Dursch, H.

    1988-01-01

    The success of the Space Station graphite/epoxy truss structure depends on its ability to endure long-term exposure to the LEO environment, primarily the effects of atomic oxygen and the temperture cycling resulting from the 94 minute orbit. This report describes the development and evaluation of chromic acid anodized (CAA) aluminum foil as protective coatings for these composite tubes. Included are: development of solar absorptance and thermal emittance properties required of Al foil and development of CAA parameters to achieve these optical properties; developing techniques to CAA 25 ft lengths of Al foil; developing bonding processes for wrapping the Al foil to graphite/epoxy tubes; and atomic oxygen testing of the CAA Al foil. Two specifications were developed and are included in the report: Chromic Acid Anodizing of Aluminum Foil Process Specification and Bonding of Anodized Aluminum Foil to Graphite/Epoxy Tubes. Results show that CAA Al foil provides and excellent protective and thermal control coating for the Space Station truss structure.

  2. Early detection of circulating anodic antigen (CAA) in a case of acute schistosomiasis mansoni with Katayama fever.

    PubMed

    Gundersen, S G; Ravn, J; Haagensen, I

    1992-01-01

    A 34-year-old male developed acute Katayama fever with fever, diarrhoea, joint pains, headache, urticarial rash and eosinophilia 18 days after falling into and spending 15 min in the water during water-skiing in the outlet of the Volta river. Low anti-schistosomal antibody titres were found by the immunofluorescence assay after 4 weeks, and the first Schistosoma mansoni eggs were found in faeces after 6 weeks. Both symptoms and eosinophilia increased the first days after treatment with oxamniquine, after which he improved gradually. Examination of frozen sera by the newly developed Magnetic Beads Antigen Capture-EIA (MBAC-EIA) later demonstrated a peak in schistosomal circulating anodic antigen (CAA) levels of diagnostic significance already 4 weeks after he was infected. PMID:1411323

  3. Early detection of circulating anodic antigen (CAA) in a case of acute schistosomiasis mansoni with Katayama fever.

    PubMed

    Gundersen, S G; Ravn, J; Haagensen, I

    1992-01-01

    A 34-year-old male developed acute Katayama fever with fever, diarrhoea, joint pains, headache, urticarial rash and eosinophilia 18 days after falling into and spending 15 min in the water during water-skiing in the outlet of the Volta river. Low anti-schistosomal antibody titres were found by the immunofluorescence assay after 4 weeks, and the first Schistosoma mansoni eggs were found in faeces after 6 weeks. Both symptoms and eosinophilia increased the first days after treatment with oxamniquine, after which he improved gradually. Examination of frozen sera by the newly developed Magnetic Beads Antigen Capture-EIA (MBAC-EIA) later demonstrated a peak in schistosomal circulating anodic antigen (CAA) levels of diagnostic significance already 4 weeks after he was infected.

  4. Analysis of the interphase of a polyamide bonded to chromic acid anodized Ti-6AL-4V

    SciTech Connect

    Guinta, R.K.; Kander, R.G.

    2000-01-06

    Structural adhesive joints, when tested as made, typically fail cohesively through the centerline of the adhesive. However, in any study of adhesive joint durability, failure near the adhesive/substrate interface becomes an important consideration. In the current study, an interfacially debonding adhesive test, the notched coating adhesion (NCA) test, was applied to LaRC(trademark) PETI-5 adhesive bonded to chronic acid anodized (CAA) Ti-6Al-4V. Post-failure analysis of the interphase region included X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). Mechanical interlocking between an adhesive and a substrate occurs when the liquid adhesive flows into interstices of the substrate, solidifies, and becomes locked in place. Mechanical interlocking is believed to significantly contribute to the adhesion of substrates that exhibit microroughness, such as metal surfaces treated with chromic acid anodization or sodium hydroxide anodization. Filbey and Wightman found that an epoxy penetrated the pores of CAA Ti-6Al-4V, one of the limited number of pore penetration studies that have been reported. In the current study, the penetration of PETI-5 into the pores of CAA Ti-6Al-4V is investigated through analysis of adhesive/substrate failure surfaces.

  5. A comparison of chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1992-01-01

    Because of federal and state mandates restricting the use of hexavalent chromium, it was deemed worthwhile to compare the corrosion protection afforded 2219-T87 aluminum alloy by both Type I chromic acid and Type II sulfuric acid anodizing per MIL-A-8625. Corrosion measurements were made on large, flat 2219-T87 aluminum alloy sheet material with an area of 1 cm(exp 2) exposed to a corrosive medium of 3.5-percent sodium chloride at pH 5.5. Both ac electrochemical impedance spectroscopy and the dc polarization resistance techniques were employed. The results clearly indicate that the corrosion protection obtained by Type II sulfuric acid anodizing is superior, and no problems should result by substituting Type II sulfuric acid anodizing for Type I chromic acid anodizing.

  6. Growth behavior of anodic oxide formed by aluminum anodizing in glutaric and its derivative acid electrolytes

    NASA Astrophysics Data System (ADS)

    Nakajima, Daiki; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

    2014-12-01

    The growth behavior of anodic oxide films formed via anodizing in glutaric and its derivative acid solutions was investigated based on the acid dissociation constants of electrolytes. High-purity aluminum foils were anodized in glutaric, ketoglutaric, and acetonedicarboxylic acid solutions under various electrochemical conditions. A thin barrier anodic oxide film grew uniformly on the aluminum substrate by glutaric acid anodizing, and further anodizing caused the film to breakdown due to a high electric field. In contrast, an anodic porous alumina film with a submicrometer-scale cell diameter was successfully formed by ketoglutaric acid anodizing at 293 K. However, the increase and decrease in the temperature of the ketoglutaric acid resulted in non-uniform oxide growth and localized pitting corrosion of the aluminum substrate. An anodic porous alumina film could also be fabricated by acetonedicarboxylic acid anodizing due to the relatively low dissociation constants associated with the acid. Acid dissociation constants are an important factor for the fabrication of anodic porous alumina films.

  7. Thin-film sulfuric acid anodizing as a replacement for chromic acid anodizing

    SciTech Connect

    Kallenborn, K.J.; Emmons, J.R.

    1995-03-01

    Chromic acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process.

  8. Thin-film sulfuric acid anodizing as a replacement for chromic acid anodizing

    NASA Technical Reports Server (NTRS)

    Kallenborn, K. J.; Emmons, J. R.

    1995-01-01

    Chromic acid has long been used to produce a thin, corrosion resistant (Type I) coating on aluminum. Following anodizing, the hardware was sealed using a sodium dichromate solution. Sealing closes up pores inherent in the anodized coating, thus improving corrosion resistance. The thinness of the brittle coating is desirable from a fatigue standpoint, and chromium was absorbed by the coating during the sealing process, further improving corrosion resistance. Unfortunately, both chromic acid and sodium dichromate contain carcinogenic hexavalent chromium. Sulfuric acid is being considered as a replacement for chromic acid. Sulfuric acid of 10-20 percent concentration has traditionally been used to produce relatively thick (Types II and III) or abrasion resistant (Type III) coatings. A more dilute, that is five weight percent, sulfuric acid anodizing process, which produces a thinner coating than Type II or III, with nickel acetate as the sealant has been developed. The process was evaluated in regard to corrosion resistance, throwing power, fatigue life, and processing variable sensitivity, and shows promise as a replacement for the chromic acid process.

  9. The corrosion protection of several aluminum alloys by chromic acid and sulfuric acid anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1994-01-01

    The corrosion protection afforded 7075-T6, 7075-T3, 6061-T6, and 2024-T3 aluminum alloys by chromic acid and sulfuric acid anodizing was examined using electrochemical techniques. From these studies, it is concluded that sulfuric acid anodizing provides superior corrosion protection compared to chromic acid anodizing.

  10. S-N Fatigue Behavior of Anodized 7050-T7451 Produced in Different Electrolytes

    NASA Astrophysics Data System (ADS)

    Lee, Eungyeong; Jeong, Yooin; Kim, Sangshik

    2012-06-01

    The effect of anodizing layers processed in different electrolytes of chromic acid (chromic acid anodizing [CAA]), sulfuric acid (sulfuric acid anodizing [SAA]), and tartaric acid (tartaric acid anodizing [TAA]) on the S-N fatigue behavior of the 7050-T7451 specimen was examined. The fatigue tests were conducted at an R ratio of 0.1 and at three different stress levels of 200, 220, and 270 MPa. Some specimens were exposed to continuous salt spraying of 5 pct NaCl solution for 336 hours and subsequently fatigue tested at an applied stress of 200 MPa. The detrimental effect of anodizing on the S-N fatigue resistance of 7050-T7451 was observed. The fatigue resistance varied with different anodizing electrolytes particularly at low stress with the greatest resistance for the TAA followed by CAA and SAA. The fractographic and micrographic observations showed the morphological difference in each anodized layer, which seemed to determine the ease of crack initiation and the resistance to S-N fatigue. The resistance to S-N fatigue of anodized 7050-T7451 specimens was, for example, affected strongly by the nature of preanodized layer with different acid-pickling processes. The pits found in the pre-CAA specimens seemed to be slightly irregular and deeper than those in the pre-TAA counterparts, reducing the fatigue resistance of the 7050-T7451 specimens. The CAA, SAA, and TAA specimens showed similar resistance to corrosion plus fatigue.

  11. Structural tuning of photoluminescence in nanoporous anodic alumina by hard anodization in oxalic and malonic acids

    NASA Astrophysics Data System (ADS)

    Santos, Abel; Alba, Maria; Rahman, Mahbubur M.; Formentín, Pilar; Ferré-Borrull, Josep; Pallarès, Josep; Marsal, Lluis F.

    2012-04-01

    We report on an exhaustive and systematic study about the photoluminescent properties of nanoporous anodic alumina membranes fabricated by the one-step anodization process under hard conditions in oxalic and malonic acids. This optical property is analysed as a function of several parameters (i.e. hard anodization voltage, pore diameter, membrane thickness, annealing temperature and acid electrolyte). This analysis makes it possible to tune the photoluminescent behaviour at will simply by modifying the structural characteristics of these membranes. This structural tuning ability is of special interest in such fields as optoelectronics, in which an accurate design of the basic nanostructures (e.g. microcavities, resonators, filters, supports, etc.) yields the control over their optical properties and, thus, upon the performance of the nanodevices derived from them (biosensors, interferometers, selective filters, etc.)

  12. The anodic oxidation of p-benzoquinone and maleic acid

    SciTech Connect

    Bock, C.; MacDougall, B.

    1999-08-01

    The oxidation of organics, in particular of p-benzoquinone and maleic acid, at high anodic potentials has been studied using a range of anode materials such as noble-metal-based oxides and antimony-doped tin oxides. The influence of the current density was also investigated showing that the oxidation rate of p-benzoquinone increased only slightly with increasing current density. The efficiency of the p-benzoquinone oxidation was found to depend on several properties of the anode material, not just its chemical nature. Furthermore, efficiencies for the partial oxidation of p-benzoquinone using specially prepared noble-metal-oxide-based anodes were found to be only somewhat smaller or even as high as those observed for PbO{sub 2} or antimony-doped tin oxide anodes, respectively. The anodic electrolysis of maleic acid solutions was found to decrease the activity of IrO{sub 2} for the oxidation of organic compounds. This was not observed when PbO{sup 2} was employed for the oxidation of maleic acid.

  13. Comparison of sulfuric and oxalic acid anodizing for preparation of thermal control coatings for spacecraft

    NASA Technical Reports Server (NTRS)

    Le, Huong G.; Watcher, John M.; Smith, Charles A.

    1988-01-01

    The development of thermal control surfaces, which maintain stable solar absorptivity and infrared emissivity over long periods, is challenging due to severe conditions in low-Earth orbit (LEO). Some candidate coatings are second-surface silver-coated Teflon; second-surface, silvered optical solar reflectors made of glass or quartz; and anodized aluminum. Sulfuric acid anodized and oxalic acid anodized aluminum was evaluated under simulated LEO conditions. Oxalic acid anodizing shows promise of greater stability in LEO over long missions, such as the 30 years planned for the Space Station. However, sulfuric acid anodizing shows lower solar absorptivity.

  14. Passive and transpassive anodic behavior of chalcopyrite in acid solutions

    NASA Astrophysics Data System (ADS)

    Warren, G. W.; Wadsworth, M. E.; El-Raghy, S. M.

    1992-01-01

    The electrochemical oxidation of CuFeS2 in various acid solutions was studied using electrodes made from massive samples. The primary techniques employed were potentiodynamic polarization and constant potential experiments supplemented by capacitance measurements. It was the purpose of this study to investigate the behavior of: (1) several sources of CuFeS2 in H2SO4 electrolytes, and (2) a single source of CuFeS2 in various dilute acids. Electrochemical characterization of CuFeS2 from various locations was performed in 1 M H2SO4 which showed significant differences in their behavior. All samples exhibited passive-like response during anodic polarization. The current density in this passive region was reproducible and showed differences of up to two orders of magnitude between samples from different sources which has been attributed mainly to the presence of impurities in some of the samples. During anodic polarization CuFeS2 was found to be sensitive to pH at higher potential, but insensitive at low potential in sulfate solution. In addition, current decay measurements at constant potential in the low potential-passive region were found to follow the Sato-Cohen (logarithmic) model for solid film formation. Based on current and mass balance measurements, two intermediate sulfide phases appeared to form in the sequence CuFeS2 → S, → S2. At higher potentials, in the transpassive region, the observed increase in current is compatible with the decomposition of water to form chemisorbed oxygen which releases copper and forms sulfate ions.

  15. Passive and transpassive anodic behavior of chalcopyrite in acid solutions

    NASA Astrophysics Data System (ADS)

    Warren, G. W.; Wadsworth, M. E.; El-Raghy, S. M.

    1982-12-01

    The electrochemical oxidation of CuFeS2 in various acid solutions was studied using electrodes made from massive samples. The primary techniques employed were potentiodynamic polarization and constant potential experiments supplemented by capacitance measurements. It was the purpose of this study to investigate the behavior of: (1) several sources of CuFeS2 in H2SO4 electrolytes, and (2) a single source of CuFeS2 in various dilute acids. Electrochemical characterization of CuFeS2 from various locations was performed in 1 M H2SO4 which showed significant differences in their behavior. All samples exhibited passive-like response during anodic polarization. The current density in this passive region was reproducible and showed differences of up to two orders of magnitude between samples from different sources which has been attributed mainly to the presence of impurities in some of the samples. During anodic polarization CuFeS2 was found to be sensitive to pH at higher potential, but insensitive at low potential in sulfate solution. In addition, current decay measurements at constant potential in the low potential-passive region were found to follow the Sato-Cohen (logarithmic) model for solid film formation. Based on current and mass balance measurements, two intermediate sulfide phases appeared to form in the sequence CuFeS2→S1→S2. At higher potentials, in the transpassive region, the observed increase in current is compatible with the decomposition of water to form chemisorbed oxygen which releases copper and forms sulfate ions.

  16. CAA for Jet Noise Physics

    NASA Technical Reports Server (NTRS)

    Mankbadi, Reda

    2001-01-01

    Dr. Mankbadi summarized recent CAA results. Examples of the effect of various boundary condition schemes on the computed acoustic field, for a point source in a uniform flow, were shown. Solutions showing the impact of inflow excitations on the result were also shown. Results from a large eddy simulation, using a fourth-order MacCormack scheme with a Smagorinsky sub-grid turbulence model, were shown for a Mach 2.1 unheated jet. The results showed that the results were free from spurious modes. Results were shown for a Mach 1.4 jet using LES in the near field and the Kirchhoff method for the far field. Predicted flow field characteristics were shown to be in good agreement with data and predicted far field directivities were shown to be in qualitative agree with experimental measurements.

  17. Synthesis of iridescent Ni-containing anodic aluminum oxide films by anodization in oxalic acid

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Ma, Hong-Mei; Zhang, Yan-Jun; Li, Ru-Song; Sun, Hui-Yuan

    2016-02-01

    Ni-containing anodic aluminum oxide films with highly saturated colors were synthesized using an ac electrodeposition method, and the optical and magnetic characteristics of the films were characterized. Precisely controllable color tuning could be obtained using wet-chemical etching to thin and widen the anodic aluminum oxide films pores isotropically before Ni deposition. Magnetic measurements indicate that such colored composite films not exhibit obvious easy magnetization direction. The resulted short (200 nm in length) and wide (50 nm in diameter) Ni nanowires present only fcc phase. The magnetization reversal mechanism is in good agreement with the symmetric fanning reversal mode which is discussed in detail. Such films may find applications in decoration, display and multifunctional anti-counterfeiting applications.

  18. Stresses in sulfuric acid anodized coatings on aluminum

    NASA Technical Reports Server (NTRS)

    Alwitt, R. S.; Xu, J.; Mcclung, R. C.

    1993-01-01

    Stresses in porous anodic alumina coatings have been measured for specimens stabilized in air at different temperatures and humidities. In ambient atmosphere the stress is tensile after anodic oxidation and is compressive after sealing. Exposure to dry atmosphere causes the stress to change to strongly tensile, up to 110 MPa. The stress increase is proportional to the loss of water from the coating. These changes are reversible with changes in humidity. Similar reversible effects occur upon moderate temperature changes. The biaxial modulus of the coating is about 100 GPa.

  19. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates

    PubMed Central

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-01

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation. PMID:24535886

  20. Nanoporous anodic aluminum oxide with a long-range order and tunable cell sizes by phosphoric acid anodization on pre-patterned substrates.

    PubMed

    Surawathanawises, Krissada; Cheng, Xuanhong

    2014-01-20

    Nanoporous anodic aluminum oxide (AAO) has been explored for various applications due to its regular cell arrangement and relatively easy fabrication processes. However, conventional two-step anodization based on self-organization only allows the fabrication of a few discrete cell sizes and formation of small domains of hexagonally packed pores. Recent efforts to pre-pattern aluminum followed with anodization significantly improve the regularity and available pore geometries in AAO, while systematic study of the anodization condition, especially the impact of acid composition on pore formation guided by nanoindentation is still lacking. In this work, we pre-patterned aluminium thin films using ordered monolayers of silica beads and formed porous AAO in a single-step anodization in phosphoric acid. Controllable cell sizes ranging from 280 nm to 760 nm were obtained, matching the diameters of the silica nanobead molds used. This range of cell size is significantly greater than what has been reported for AAO formed in phosphoric acid in the literature. In addition, the relationships between the acid concentration, cell size, pore size, anodization voltage and film growth rate were studied quantitatively. The results are consistent with the theory of oxide formation through an electrochemical reaction. Not only does this study provide useful operational conditions of nanoindentation induced anodization in phosphoric acid, it also generates significant information for fundamental understanding of AAO formation.

  1. Electrochemical incineration of sulfanilic acid at a boron-doped diamond anode.

    PubMed

    El-Ghenymy, Abdellatif; Arias, Conchita; Cabot, Pere Lluís; Centellas, Francesc; Garrido, José Antonio; Rodríguez, Rosa María; Brillas, Enric

    2012-06-01

    The anodic oxidation of sulfanilic acid solutions has been studied in acidic medium using a divided cell with a boron-doped diamond (BDD) anode and a stainless steel cathode. Overall mineralization was achieved under all experimental conditions tested due to the efficient destruction of sulfanilic acid and all its by-products with hydroxyl radicals generated at the BDD anode from water oxidation. The alternative use of an undivided cell with the same electrodes gave rise to the coating of the cathode with polymeric compounds, thus preventing the complete electrochemical incineration of sulfanilic acid. The solutions treated in the anodic compartment of the divided cell were degraded at similar rate under pH regulation within the pH interval 2.0-6.0. The mineralization current efficiency was enhanced when the applied current decreased and the initial substrate concentration increased. The decay of sulfanilic acid was followed by reversed-phase HPLC, showing a pseudo first-order kinetics. Hydroquinone and p-benzoquinone were identified as aromatic intermediates by gas chromatography-mass spectrometry and/or reversed-phase HPLC. Maleic, acetic, formic, oxalic and oxamic acids were detected as generated carboxylic acids by ion-exclusion HPLC. Ionic chromatographic analysis of electrolyzed solutions revealed that the N content of sulfanilic acid was mainly released as NH(4)(+) ion and in much smaller proportion as NO(3)(-) ion.

  2. Acidity and aluminum toxicity caused by iron oxidation around anode bars

    SciTech Connect

    Shen, S.; Pepper, G.E.; Hassett, J.J.; Stucki, J.W.

    1998-08-01

    Soil acidity and aluminum toxicity are serious environmental problems often found in humid temperate and tropical regions or in areas with acid rain. Iron oxidation in soils can also cause high concentrations of H{sup +}, which, in turn, causes an increase of Al{sup 3+} in the soil solution. To examine this problem, a study was undertaken to discover the cause of crop damage in crops planted over buried anode bars. Anode bars are part of an impressed current cathodic protection system for pipelines near Decatur, Illinois. Soil samples were collected from the problem site and from a non-problem site for comparison. Results showed that Fe oxidation around anode bars at the problem site is stimulated by electric current, a situation that results in high concentrations of H{sup +} and reduces soil pH to less than 3.0. Under the low pH condition, the content of available Al is very high, and therefore, the soil solution becomes toxic for soybean roots. Exchangeable Al was 360 to 700 ppm in soil immediately adjacent to anode bars but only 3 ppm in the soil midway between anode bars. The damage to the plants, such as reduced vegetative growth and lowered seed yield, developed in a circular pattern over the anode bars. Factors contributing to the problem were soil Fe content, rectifier voltage, and soil drainage.

  3. Electro-oxidation of perfluorooctanoic acid by carbon nanotube sponge anode and the mechanism.

    PubMed

    Xue, An; Yuan, Zi-Wen; Sun, Yan; Cao, An-Yuan; Zhao, Hua-Zhang

    2015-12-01

    As an emerging persistent organic pollutant (POPs), perfluorooctanoic acid (PFOA) exists widely in natural environment. It is of particular significance to develop efficient techniques to remove low-concentration PFOA from the contaminated waters. In this work, we adopted a new material, carbon nanotube (CNT) sponge, as electrode to enhance electro-oxidation and achieve high removal efficiency of low-concentration (100μgL(-1)) PFOA from water. CNT sponge was pretreated by mixed acids to improve the surface morphology, hydrophilicity and the content of carbonyl groups on the surface. The highest removal efficiencies for low-concentration PFOA electrolyzed by acid-treated CNT sponge anode proved higher than 90%. The electro-oxidation mechanism of PFOA on CNT sponge anode was also discussed. PFOA is adsorbed on the CNT sponge rapidly increasing the concentration of PFOA on anode surface. When the potential on the anode is adjusted to more than 3.5V, the adsorbed PFOA undergoes electrochemically oxidation and hydrolysis to produce shorter-chain perfluorocarboxylic acids with less CF2 unit. The efficient electro-oxidation of PFOA by CNT sponge anode is due to the combined effect of adsorption and electrochemical oxidation. These findings provide an efficient method to remove actual concentration PFOA from water. PMID:26172515

  4. Artificially MoO3 graded ITO anodes for acidic buffer layer free organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Lee, Hye-Min; Kim, Seok-Soon; Kim, Han-Ki

    2016-02-01

    We report characteristics of MoO3 graded ITO anodes prepared by a RF/DC graded sputtering for acidic poly(3,4-ethylene dioxylene thiophene):poly(styrene sulfonic acid) (PEDOT:PSS)-free organic solar cells (OSCs). Graded sputtering of the MoO3 buffer layer on top of the ITO layer produced MoO3 graded ITO anodes with a sheet resistance of 12.67 Ω/square, a resistivity of 2.54 × 10-4 Ω cm, and an optical transmittance of 86.78%, all of which were comparable to a conventional ITO anode. In addition, the MoO3 graded ITO electrode showed a greater work function of 4.92 eV than that (4.6 eV) of an ITO anode, which is beneficial for hole extraction from an organic active layer. Due to the high work function of MoO3 graded ITO electrodes, the acidic PEDOT:PSS-free OSCs fabricated on the MoO3 graded ITO electrode exhibited a power conversion efficiency 3.60% greater than that of a PEDOT:PSS-free OSC on the conventional ITO anode. The successful operation of PEDOT:PSS-free OSCs indicates simpler fabrication steps for cost-effective OSCs and elimination of interfacial reactions caused by the acidic PEDOT:PSS layer for reliable OSCs.

  5. Electro-oxidation of perfluorooctanoic acid by carbon nanotube sponge anode and the mechanism.

    PubMed

    Xue, An; Yuan, Zi-Wen; Sun, Yan; Cao, An-Yuan; Zhao, Hua-Zhang

    2015-12-01

    As an emerging persistent organic pollutant (POPs), perfluorooctanoic acid (PFOA) exists widely in natural environment. It is of particular significance to develop efficient techniques to remove low-concentration PFOA from the contaminated waters. In this work, we adopted a new material, carbon nanotube (CNT) sponge, as electrode to enhance electro-oxidation and achieve high removal efficiency of low-concentration (100μgL(-1)) PFOA from water. CNT sponge was pretreated by mixed acids to improve the surface morphology, hydrophilicity and the content of carbonyl groups on the surface. The highest removal efficiencies for low-concentration PFOA electrolyzed by acid-treated CNT sponge anode proved higher than 90%. The electro-oxidation mechanism of PFOA on CNT sponge anode was also discussed. PFOA is adsorbed on the CNT sponge rapidly increasing the concentration of PFOA on anode surface. When the potential on the anode is adjusted to more than 3.5V, the adsorbed PFOA undergoes electrochemically oxidation and hydrolysis to produce shorter-chain perfluorocarboxylic acids with less CF2 unit. The efficient electro-oxidation of PFOA by CNT sponge anode is due to the combined effect of adsorption and electrochemical oxidation. These findings provide an efficient method to remove actual concentration PFOA from water.

  6. Analysis of nanopore arrangement and structural features of anodic alumina layers formed by two-step anodizing in oxalic acid using the dedicated executable software

    NASA Astrophysics Data System (ADS)

    Zaraska, Leszek; Stępniowski, Wojciech J.; Sulka, Grzegorz D.; Ciepiela, Eryk; Jaskuła, Marian

    2014-02-01

    Anodic porous alumina layers were fabricated by a two-step self-organized anodization in 0.3 M oxalic acid under various anodizing potentials ranging from 30 to 60 V at two different temperatures (10 and 17 ∘C). The effect of anodizing conditions on structural features and pore arrangement of AAO was investigated in detail by using the dedicated executable publication combined with ImageJ software. With increasing anodizing potential, a linear increase of the average pore diameter, interpore distance, wall thickness and barrier layer thickness, as well as a decrease of the pore density, were observed. In addition, the higher pore diameter and porosity values were obtained for samples anodized at the elevated temperature, independently of the anodizing potential. A degree of pore order was investigated on the basis of Delaunay triangulations (defect maps) and calculation of pair distribution or angle distribution functions (PDF or ADF), respectively. All methods confirmed that in order to obtain nanoporous alumina with the best, hexagonal pore arrangement, the potential of 40 V should be applied during anodization. It was confirmed that the dedicated executable publication can be used to a fast and complex analysis of nanopore arrangement and structural features of nanoporous oxide layers.

  7. Fast fabrication of self-ordered anodic porous alumina on oriented aluminum grains by high acid concentration and high temperature anodization.

    PubMed

    Cheng, Chuan; Ngan, Alfonso H W

    2013-05-31

    Anodic porous alumina, which exhibits a characteristic nanohoneycomb structure, has been used in a wide range of nanotechnology applications. The conventional fabrication method of mild anodization (MA) requires a prolonged anodization time which is impractical for batch processing, and self-ordered porous structures can only be formed within narrow processing windows so that the dimensions of the resultant structures are extremely limited. The alternative hard anodization (HA) may easily result in macroscopic defects on the alumina surface. In this work, by systematically varying the anodization conditions including the substrate grain orientation, electrolyte concentration, temperature, voltage, and time, a new oxalic acid based anodization method, called high acid concentration and high temperature anodization (HHA), is found, which can result in far better self-ordering of the porous structures at rates 7-26 times faster than MA, under a continuous voltage range of 30-60 V on (001) oriented Al grains. Unlike HA, no macroscopic defects appear under the optimum self-ordered conditions of HHA at 40 V, even for pore channels grown up to high aspect ratios of more than 3000. Compared to MA and HA, HHA provides more choices of self-ordered nano-porous structures with fast and mechanically stable formation features for practical applications. PMID:23619572

  8. Cluster CAA Module for PaPCo

    NASA Astrophysics Data System (ADS)

    Faden, J.; Åsnes, A.; Friedel, R.; Taylor, M.; McCaffrey, S.; Perry, C.; Goldstein, M. L.

    A PaPCo module for visualization of data from the CAA has been developed. This module retrieves data from the CAA web interface, and allows for discovery and plotting of new datasets. PaPCo is modular, open source IDL software that uses plug-in modules to bring new datasets on to a stack of time series plots (www.papco.org). PaPCo includes modules for plotting data from Cluster/PEACE and Cluster/RAPID, CDA Web data which includes Cluster Prime Parameters, and various modules from CRRES, POLAR, GPS, and many other spacecraft. The Cluster CAA module is presented, as well as a brief description of PaPCo's use and installation procedure.

  9. Enhancement of power production with tartaric acid doped polyaniline nanowire network modified anode in microbial fuel cells.

    PubMed

    Liao, Zhi-Hong; Sun, Jian-Zhong; Sun, De-Zhen; Si, Rong-Wei; Yong, Yang-Chun

    2015-09-01

    The feasibility to use tartaric acid doped PANI for MFC anode modification was determined. Uniform PANI nanowires doped with tartaric acid were synthesized and formed mesoporous networks on the carbon cloth surface. By using this tartaric acid doped PANI modified carbon cloth (PANI-TA) as the anode, the voltage output (435 ± 15 mV) and power output (490 ± 12 mW/m(2)) of MFC were enhanced by 1.6 times and 4.1 times compared to that of MFC with plain carbon cloth anode, respectively. Strikingly, the performance of PANI-TA MFC was superior to that of the MFCs with inorganic acids doped PNAI modified anode. These results substantiated that tartaric acid is a promising PANI dopant for MFC anode modification, and provided new opportunity for MFC performance improvement.

  10. Corrosion and Protection of Lead Anodes in Acidic Copper Sulphate Solutions

    NASA Astrophysics Data System (ADS)

    Cifuentes, L.; Astete, E.; Crisotomo, G.; Simpson, J.; Cifuentes, G.; Pilleux, M.

    It is known that lead anodes used in the industrial extraction of copper by electrolysis (electrowinning) suffer corrosion as a result of accidental or intended current interruptions. In order to improve understanding of the corrosion and protection of such anodes, the effects of the concentrations of copper, sulphuric acid, cobalt, iron, manganese, chloride and an organic additive (guar) on the corrosion of lead have been studied by means of weight loss tests and surface analysis techniques (X-ray photoelectron spectroscopy, X-ray diffraction, and wavelength dispersive spectroscopy). The rate of corrosion of lead during current interruptions increases with increasing concentration of sulphuric acid and copper, whereas it decreases markedly in the presence of cobalt and iron and, to a lesser extent, in the presence of chloride and the organic additive. Manganese is the only impurity whose presence does not reduce the rate of corrosion; it is also the only element which precipitates in significant amounts on the lead anode surface under the conditions studied. A method is proposed to establish the optimum anodic protection current density during current interruptions in electrowinning cells. Three current density ranges have been found, of which the 'high' protection range could be caused by the degree of compactness acquired by the PbO2 layer at applied anodic current densities in excess of 60 A m-2.

  11. Porous aluminum room temperature anodizing process in a fluorinated-oxalic acid solution

    NASA Astrophysics Data System (ADS)

    Dhahri, S.; Fazio, E.; Barreca, F.; Neri, F.; Ezzaouia, H.

    2016-08-01

    Anodizing of aluminum is used for producing porous insulating films suitable for different applications in electronics and microelectronics. Porous-type aluminum films are most simply realized by galvanostatic anodizing in aqueous acidic solutions. The improvement in application of anodizing technique is associated with a substantial reduction of the anodizing voltage at appropriate current densities as well as to the possibility to carry out the synthesis process at room temperature in order to obtain a self-planarizing dielectric material incorporated in array of super-narrow metal lines. In this work, the anodizing of aluminum to obtain porous oxide was carried out, at room temperature, on three different substrates (glass, stainless steel and aluminum), using an oxalic acid-based electrolyte with the addition of a relatively low amount of 0.4 % of HF. Different surface morphologies, from nearly spherical to larger porous nanostructures with smooth edges, were observed by means of scanning electron microscopy. These evidences are explained by considering the formation, transport and adsorption of the fluorine species which react with the Al3+ ions. The behavior is also influenced by the nature of the original substrate.

  12. Acid blue 29 decolorization and mineralization by anodic oxidation with a cold gas spray synthesized Sn-Cu-Sb alloy anode.

    PubMed

    do Vale-Júnior, Edilson; Dosta, Sergi; Cano, Irene Garcia; Guilemany, Josep Maria; Garcia-Segura, Sergi; Martínez-Huitle, Carlos Alberto

    2016-04-01

    The elevated cost of anodic materials used in the anodic oxidation for water treatment of effluents undermines the real application of these technologies. The study of novel alternative materials more affordable is required. In this work, we report the application of Sn-Cu-Sb alloys as cheap anodic material to decolorize azo dye Acid Blue 29 solutions. These anodes have been synthesized by cold gas spray technologies. Almost complete decolorization and COD abatement were attained after 300 and 600 min of electrochemical treatment, respectively. The influence of several variables such as supporting electrolyte, pH, current density and initial pollutant concentration has been investigated. Furthermore, the release and evolution of by-products was followed by HPLC to better understand the oxidative power of Sn-Cu-Sb electrodes.

  13. Effect of Sulfuric Acid Concentration on Electrochemical Characteristics of Nano Porous Structure Formed by Anodizing Process.

    PubMed

    Lee, Jung-Hyung; Lee, Seung-Jun; Kim, Seong-Jong

    2016-02-01

    Aluminum alloy is a very strong reactivity material, but it has excellent corrosion resistance due to protective oxide film created in air. However, it is not practical because the film thickness is uneven and varies depending on the generation condition. Therefore, aluminum anodizing was performed to form film with commercially applicable hardness, corrosion resistance, and wear resistance. This offers such advantages as commercial applicability to large areas and low prices. In this study, the electrochemical characteristics with concentration of sulfuric acid electrolyte were compared with the two-step anodizing method which is widely used. A surface observation revealed regular structures and pores with the size of several tens of nm, and the anodized film presented excellent corrosion resistance with considerably low corrosion current density in sea water. PMID:27433656

  14. Effect of Sulfuric Acid Concentration on Electrochemical Characteristics of Nano Porous Structure Formed by Anodizing Process.

    PubMed

    Lee, Jung-Hyung; Lee, Seung-Jun; Kim, Seong-Jong

    2016-02-01

    Aluminum alloy is a very strong reactivity material, but it has excellent corrosion resistance due to protective oxide film created in air. However, it is not practical because the film thickness is uneven and varies depending on the generation condition. Therefore, aluminum anodizing was performed to form film with commercially applicable hardness, corrosion resistance, and wear resistance. This offers such advantages as commercial applicability to large areas and low prices. In this study, the electrochemical characteristics with concentration of sulfuric acid electrolyte were compared with the two-step anodizing method which is widely used. A surface observation revealed regular structures and pores with the size of several tens of nm, and the anodized film presented excellent corrosion resistance with considerably low corrosion current density in sea water.

  15. The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes.

    PubMed

    Bensalah, Nasr; Dbira, Sondos; Bedoui, Ahmed

    2016-07-01

    In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond (BDD) anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in NaCl; however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and NaClO4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine (Cl2, HClO, ClO(-)) electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density (≤10mA/cm(2)) and neutral medium (pH in the range 6-9) should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate. PMID:27372125

  16. Evaluation of lead anode reactions in acid sulfate electrolytes. 1: Lead alloys with cobalt additives

    SciTech Connect

    Yu, P.; O`Keefe, T.J.

    1999-04-01

    Lead alloys, such as lead-calcium-tin and lead-silver, are the primary insoluble anodes used in the electrowinning of metals. While some difficulties are encountered in their use, there is no obvious replacement that is economically and technically competitive. Two of the specific problems with lead include decreased cathode purity due to incorporation from corrosion products and the relatively high overpotential which increases cell voltage. To gain an improved understanding of the fundamental behavior of lead anodes, the polarization behavior of six different alloys in sulfuric acid was evaluated. Some tests were also made with Co(II) in the acid sulfate electrolyte. Notable differences were found in the multiple activation-passivation cycles, stability, and relative activity for oxygen evolution for the alloys, and the relative trends in behavior were established. Electrochemical impedance spectroscopy studies were also conducted at selected potentials. Overall, the data show that the electrochemical response, particularly the degree of polarization for the oxygen evolution reaction, of the lead alloy anodes are dependent on the surface phases and structures present. The ability to depolarize the anode reaction using Co(II) was particularly sensitive to the lead composition.

  17. Cell Adhesion and in Vivo Osseointegration of Sandblasted/Acid Etched/Anodized Dental Implants

    PubMed Central

    Kim, Mu-Hyon; Park, Kyeongsoon; Choi, Kyung-Hee; Kim, Soo-Hong; Kim, Se Eun; Jeong, Chang-Mo; Huh, Jung-Bo

    2015-01-01

    The authors describe a new type of titanium (Ti) implant as a Modi-anodized (ANO) Ti implant, the surface of which was treated by sandblasting, acid etching (SLA), and anodized techniques. The aim of the present study was to evaluate the adhesion of MG-63 cells to Modi-ANO surface treated Ti in vitro and to investigate its osseointegration characteristics in vivo. Four different types of Ti implants were examined, that is, machined Ti (control), SLA, anodized, and Modi-ANO Ti. In the cell adhesion study, Modi-ANO Ti showed higher initial MG-63 cell adhesion and induced greater filopodia growth than other groups. In vivo study in a beagle model revealed the bone-to-implant contact (BIC) of Modi-ANO Ti (74.20% ± 10.89%) was much greater than those of machined (33.58% ± 8.63%), SLA (58.47% ± 12.89), or ANO Ti (59.62% ± 18.30%). In conclusion, this study demonstrates that Modi-ANO Ti implants produced by sandblasting, acid etching, and anodizing improve cell adhesion and bone ongrowth as compared with machined, SLA, or ANO Ti implants. These findings suggest that the application of Modi-ANO surface treatment could improve the osseointegration of dental implant. PMID:25955650

  18. Boric/sulfuric acid anodizing of aluminum alloys 2024 and 7075: Film growth and corrosion resistance

    SciTech Connect

    Thompson, G.E.; Zhang, L.; Smith, C.J.E.; Skeldon, P.

    1999-11-01

    The influence of boric acid (H{sub 3}BO{sub 3}) additions to sulfuric acid (H{sub 2}SO{sub 4}) were examined for the anodizing of Al 2024-T3 (UNS A92024) and Al 7075-T6 (UNS A97075) alloys at constant voltage. Alloys were pretreated by electropolishing, by sodium dichromate (Na{sub 2}Cr{sub 2}O{sub 7})/H{sub 2}SO{sub 4} (CSA) etching, or by alkaline etching. Current-time responses revealed insignificant dependence on the concentration of H{sub 3}BO{sub 3} to 50 g/L. Pretreatments affected the initial film development prior to the establishment of the steady-state morphology of the porous film, which was related to the different compositions and morphologies of pretreated surfaces. More detailed studies of the Al 7075-T6 alloy indicated negligible effects of H{sub 3}BO{sub 3} on the coating weight, morphology of the anodic film, and thickening rate of the film, or corrosion resistance provided by the film. In salt spray tests, unsealed films formed in H{sub 2}SO{sub 4} or mixed acid yielded similar poor corrosion resistances, which were inferior to that provided by anodizing in chromic acid (H{sub 2}CrO{sub 4}). Sealing of films in deionized water, or preferably in chromate solution, improved corrosion resistance, although not matching the far superior performance provided by H{sub 2}CrO{sub 4} anodizing and sealing.

  19. Direct anodic hydrochloric acid and cathodic caustic production during water electrolysis

    NASA Astrophysics Data System (ADS)

    Lin, Hui-Wen; Cejudo-Marín, Rocío; Jeremiasse, Adriaan W.; Rabaey, Korneel; Yuan, Zhiguo; Pikaar, Ilje

    2016-02-01

    Hydrochloric acid (HCl) and caustic (NaOH) are among the most widely used chemicals by the water industry. Direct anodic electrochemical HCl production by water electrolysis has not been successful as current commercially available electrodes are prone to chlorine formation. This study presents an innovative technology simultaneously generating HCl and NaOH from NaCl using a Mn0.84Mo0.16O2.23 oxygen evolution electrode during water electrolysis. The results showed that protons could be anodically generated at a high Coulombic efficiency (i.e. ≥ 95%) with chlorine formation accounting for 3 ~ 5% of the charge supplied. HCl was anodically produced at moderate strengths at a CE of 65 ± 4% together with a CE of 89 ± 1% for cathodic caustic production. The reduction in CE for HCl generation was caused by proton cross-over from the anode to the middle compartment. Overall, this study showed the potential of simultaneous HCl and NaOH generation from NaCl and represents a major step forward for the water industry towards on-site production of HCl and NaOH. In this study, artificial brine was used as a source of sodium and chloride ions. In theory, artificial brine could be replaced by saline waste streams such as Reverse Osmosis Concentrate (ROC), turning ROC into a valuable resource.

  20. Direct anodic hydrochloric acid and cathodic caustic production during water electrolysis

    PubMed Central

    Lin, Hui-Wen; Cejudo-Marín, Rocío; Jeremiasse, Adriaan W.; Rabaey, Korneel; Yuan, Zhiguo; Pikaar, Ilje

    2016-01-01

    Hydrochloric acid (HCl) and caustic (NaOH) are among the most widely used chemicals by the water industry. Direct anodic electrochemical HCl production by water electrolysis has not been successful as current commercially available electrodes are prone to chlorine formation. This study presents an innovative technology simultaneously generating HCl and NaOH from NaCl using a Mn0.84Mo0.16O2.23 oxygen evolution electrode during water electrolysis. The results showed that protons could be anodically generated at a high Coulombic efficiency (i.e. ≥ 95%) with chlorine formation accounting for 3 ~ 5% of the charge supplied. HCl was anodically produced at moderate strengths at a CE of 65 ± 4% together with a CE of 89 ± 1% for cathodic caustic production. The reduction in CE for HCl generation was caused by proton cross-over from the anode to the middle compartment. Overall, this study showed the potential of simultaneous HCl and NaOH generation from NaCl and represents a major step forward for the water industry towards on-site production of HCl and NaOH. In this study, artificial brine was used as a source of sodium and chloride ions. In theory, artificial brine could be replaced by saline waste streams such as Reverse Osmosis Concentrate (ROC), turning ROC into a valuable resource. PMID:26848031

  1. Air-breathing direct formic acid microfluidic fuel cell with an array of cylinder anodes

    NASA Astrophysics Data System (ADS)

    Zhu, Xun; Zhang, Biao; Ye, Ding-Ding; Li, Jun; Liao, Qiang

    2014-02-01

    An air-breathing direct formic acid membraneless microfluidic fuel cell using graphite cylinder arrays as the anode is proposed. The three dimensional anode volumetrically extends the reactive surface area and improves fuel utilization. The effects of spacer configuration, fuel and electrolyte concentration as well as reactant flow rate on the species transport and cell performance are investigated. The dynamic behavior of generated CO2 bubbles is visualized and its effect on current generation is discussed. The results show that the absence of two spacers adjacent to the cathode surface improves the cell performance by reducing the proton transfer resistance. The CO2 gas bubbles are constrained within the anode array and expelled by the fluid flow periodically. Proper reactant concentration and flow rate are crucial for cell operation. At optimum conditions, a maximum current density of 118.3 mA cm-3 and a peak power density of 21.5 mW cm-3 are obtained. In addition, benefit from the volumetrically stacked anodes and enhanced fuel transfer, the maximum single pass fuel utilization rate reaches up to 87.6% at the flow rate of 1 mL h-1.

  2. Mechanism and kinetics of electrochemical degradation of uric acid using conductive-diamond anodes.

    PubMed

    Dbira, Sondos; Bensalah, Nasr; Bedoui, Ahmed

    2016-12-01

    Uric acid (UA) is one of the principal effluents of urine wastewaters, widely used in agriculture as fertilizer, which is potentially dangerous and biorefractory. Hence, the degradation of UA (2,6,8-trihydroxy purine) in aqueous solution of pH 3.0 has been studied by conductive-diamond electrochemical oxidation. Hydroxyl radicals formed from water oxidation at the surface of boron-doped diamond anodes were the main oxidizing agents. Effects of current density and supporting electrolyte on the degradation rate and process efficiency are assessed. Results show that the increase of current density from 20 to 60 mA cm(-2) leads to a decrease in the efficiency of the electrochemical process. In addition, the best degradation occurred in the presence of NaCl as conductive electrolyte. Interestingly, an almost total mineralization of 50 ppm UA was obtained when anodic oxidation was performed at low current densities (20 mA cm(-2)) and in the presence of NaCl. This result confirmed that the electrolysis using diamond anodes is a very interesting technology for the treatment of UA. The identification of UA transformation products was performed by high-performance liquid chromatography (HPLC). HPLC analysis of treated solutions revealed that oxalic acid and urea were the two intermediates found. Oxalic acid was the most persistent product. Based on detected intermediates and bibliographic research, a mechanism of UA mineralization by anodic oxidation has been proposed. Ionic chromatography analysis confirmed the release of [Formula: see text] and [Formula: see text] ions during UA mineralization. PMID:27108970

  3. Mechanism and kinetics of electrochemical degradation of uric acid using conductive-diamond anodes.

    PubMed

    Dbira, Sondos; Bensalah, Nasr; Bedoui, Ahmed

    2016-12-01

    Uric acid (UA) is one of the principal effluents of urine wastewaters, widely used in agriculture as fertilizer, which is potentially dangerous and biorefractory. Hence, the degradation of UA (2,6,8-trihydroxy purine) in aqueous solution of pH 3.0 has been studied by conductive-diamond electrochemical oxidation. Hydroxyl radicals formed from water oxidation at the surface of boron-doped diamond anodes were the main oxidizing agents. Effects of current density and supporting electrolyte on the degradation rate and process efficiency are assessed. Results show that the increase of current density from 20 to 60 mA cm(-2) leads to a decrease in the efficiency of the electrochemical process. In addition, the best degradation occurred in the presence of NaCl as conductive electrolyte. Interestingly, an almost total mineralization of 50 ppm UA was obtained when anodic oxidation was performed at low current densities (20 mA cm(-2)) and in the presence of NaCl. This result confirmed that the electrolysis using diamond anodes is a very interesting technology for the treatment of UA. The identification of UA transformation products was performed by high-performance liquid chromatography (HPLC). HPLC analysis of treated solutions revealed that oxalic acid and urea were the two intermediates found. Oxalic acid was the most persistent product. Based on detected intermediates and bibliographic research, a mechanism of UA mineralization by anodic oxidation has been proposed. Ionic chromatography analysis confirmed the release of [Formula: see text] and [Formula: see text] ions during UA mineralization.

  4. Exciton-blocking phosphonic acid-treated anode buffer layers for organic photovoltaics

    NASA Astrophysics Data System (ADS)

    Zimmerman, Jeramy D.; Song, Byeongseop; Griffith, Olga; Forrest, Stephen R.

    2013-12-01

    We demonstrate significant improvements in power conversion efficiency of bilayer organic photovoltaics by replacing the exciton-quenching MoO3 anode buffer layer with an exciton-blocking benzylphosphonic acid (BPA)-treated MoO3 or NiO layer. We show that the phosphonic acid treatment creates buffers that block up to 70% of excitons without sacrificing the hole extraction efficiency. Compared to untreated MoO3 anode buffers, BPA-treated NiO buffers exhibit a ˜ 25% increase in the near-infrared spectral response in diphenylanilo functionalized squaraine (DPSQ)/C60-based bilayer devices, increasing the power conversion efficiency under 1 sun AM1.5G simulated solar illumination from 4.8 ± 0.2% to 5.4 ± 0.3%. The efficiency can be further increased to 5.9 ± 0.3% by incorporating a highly conductive exciton blocking bathophenanthroline (BPhen):C60 cathode buffer. We find similar increases in efficiency in two other small-molecule photovoltaic systems, indicating the generality of the phosphonic acid-treated buffer approach to enhance exciton blocking.

  5. Performance of AA5052 alloy anode in alkaline ethylene glycol electrolyte with dicarboxylic acids additives for aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, DaPeng; Zhang, DaQuan; Lee, KangYong; Gao, LiXin

    2015-11-01

    Dicarboxylic acid compounds, i.e. succinic acid (SUA), adipic acid (ADA) and sebacic acid (SEA), are used as electrolyte additives in the alkaline ethylene glycol solution for AA5052 aluminium-air batteries. It shows that the addition of dicarboxylic acids lowers the hydrogen gas evolution rate of commercial AA5052 aluminium alloy anode. AA5052 aluminium alloy has wide potential window for electrochemical activity and better discharge performance in alkaline ethylene glycol solution containing dicarboxylic acid additives. ADA has the best inhibition effect for the self-corrosion of AA5052 anode among the three dicarboxylic acid additives. Fourier transform infrared spectroscopy (FT-IR) reveals that dicarboxylic acids and aluminium ions can form coordination complexes. Quantum chemical calculations shows that ADA has a smaller energy gap (ΔE, the energy difference between the lowest unoccupied orbital and the highest occupied orbital), indicating that ADA has the strongest interaction with aluminium ions.

  6. Streamlining CAA compliance plans yields added benefits

    SciTech Connect

    Miller, D.A. )

    1993-02-01

    A common approach to compliance with air emissions standards at some facilities consists of correcting deficiencies noted by regulators during their annual or semi-annual visits without developing long-term compliance plans. Many times, plant officials do not know which regulations apply to their sources. Industry no longer can afford to depend on such hit-or-miss compliance strategies. Under the CAA Amendments, EPA is empowerd to issue field citations of $5,000 per day for each violation, and monetary penalties can reach millions of dollars and be accompanied by prison sentences up to 15 years. Developing a plant-wide emissions compliance plan is one of the best ways to minimize future compliance liabilities. Data collected for such plans typically are stored in a computerized database, which also can be used in other compliance activities.

  7. Second Computational Aeroacoustics (CAA) Workshop on Benchmark Problems

    NASA Technical Reports Server (NTRS)

    Tam, C. K. W. (Editor); Hardin, J. C. (Editor)

    1997-01-01

    The proceedings of the Second Computational Aeroacoustics (CAA) Workshop on Benchmark Problems held at Florida State University are the subject of this report. For this workshop, problems arising in typical industrial applications of CAA were chosen. Comparisons between numerical solutions and exact solutions are presented where possible.

  8. Quick Win or Slow Burn: Modelling UK HE CAA Uptake

    ERIC Educational Resources Information Center

    Warburton, Bill

    2009-01-01

    The uptake of CAA in UK higher education (HE) on a large scale lags behind the expectations of CAA specialists. A research project was undertaken with the aim of discovering and addressing the underlying reasons for this. The research was conducted according to Strauss and Corbin's (1998) prescription for grounded theory (GT) research. During…

  9. Degradation of trans-ferulic acid in acidic aqueous medium by anodic oxidation, electro-Fenton and photoelectro-Fenton.

    PubMed

    Flores, Nelly; Sirés, Ignasi; Garrido, José Antonio; Centellas, Francesc; Rodríguez, Rosa María; Cabot, Pere Lluís; Brillas, Enric

    2016-12-01

    Solutions of pH 3.0 containing trans-ferulic acid, a phenolic compound in olive oil mill wastewater, have been comparatively degraded by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Trials were performed with a BDD/air-diffusion cell, where oxidizing OH was produced from water discharge at the BDD anode and/or in the solution bulk from Fenton's reaction between cathodically generated H2O2 and added catalytic Fe(2+). The substrate was very slowly removed by AO-H2O2, whereas it was very rapidly abated by EF and PEF, at similar rate in both cases, due to its fast reaction with OH in the bulk. The AO-H2O2 process yielded a slightly lower mineralization than EF, which promoted the accumulation of barely oxidizable products like Fe(III) complexes. In contrast, the fast photolysis of these latter species under irradiation with UVA light in PEF led to an almost total mineralization with 98% total organic carbon decay. The effect of current density and substrate concentration on the performance of all treatments was examined. Several solar PEF (SPEF) trials showed its viability for the treatment of wastewater containing trans-ferulic acid at larger scale. Four primary aromatic products were identified by GC-MS analysis of electrolyzed solutions, and final carboxylic acids like fumaric, acetic and oxalic were detected by ion-exclusion HPLC. A reaction sequence for trans-ferulic acid mineralization involving all the detected products is finally proposed. PMID:26691522

  10. Degradation of trans-ferulic acid in acidic aqueous medium by anodic oxidation, electro-Fenton and photoelectro-Fenton.

    PubMed

    Flores, Nelly; Sirés, Ignasi; Garrido, José Antonio; Centellas, Francesc; Rodríguez, Rosa María; Cabot, Pere Lluís; Brillas, Enric

    2016-12-01

    Solutions of pH 3.0 containing trans-ferulic acid, a phenolic compound in olive oil mill wastewater, have been comparatively degraded by anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Trials were performed with a BDD/air-diffusion cell, where oxidizing OH was produced from water discharge at the BDD anode and/or in the solution bulk from Fenton's reaction between cathodically generated H2O2 and added catalytic Fe(2+). The substrate was very slowly removed by AO-H2O2, whereas it was very rapidly abated by EF and PEF, at similar rate in both cases, due to its fast reaction with OH in the bulk. The AO-H2O2 process yielded a slightly lower mineralization than EF, which promoted the accumulation of barely oxidizable products like Fe(III) complexes. In contrast, the fast photolysis of these latter species under irradiation with UVA light in PEF led to an almost total mineralization with 98% total organic carbon decay. The effect of current density and substrate concentration on the performance of all treatments was examined. Several solar PEF (SPEF) trials showed its viability for the treatment of wastewater containing trans-ferulic acid at larger scale. Four primary aromatic products were identified by GC-MS analysis of electrolyzed solutions, and final carboxylic acids like fumaric, acetic and oxalic were detected by ion-exclusion HPLC. A reaction sequence for trans-ferulic acid mineralization involving all the detected products is finally proposed.

  11. Nanopores in GaN by electrochemical anodization in hydrofluoric acid: Formation and mechanism

    NASA Astrophysics Data System (ADS)

    Chen, Danti; Xiao, Hongdi; Han, Jung

    2012-09-01

    We report the use of hydrofluoric acid (HF) as an electrolyte in etching and porosifying GaN. HF is found to be effective in rendering a wide range of nanoporous morphology, from curved branches to highly parallel straight pores. Under suitable conditions, the porosification proceeds at a rate greater than 100 μm/min. To elucidate the etching mechanism, cyclic voltammetry is performed, together with a parametric mapping of electrolysis variables such as the doping of GaN, the concentration of HF electrolyte, and the anodization voltage. We demonstrate that the formation of nanoporous structures is largely due to the local breakdown of the reverse-biased semiconductor junction. A quantitative agreement between the estimated width of space-charge region and the observed variation in morphology lends support to a depletion layer model developed previously in the etching of porous-Si.

  12. Chemometric study on the electrochemical incineration of nitrilotriacetic acid using platinum and boron-doped diamond anode.

    PubMed

    Zhang, Chunyong; He, Zhenzhu; Wu, Jingyu; Fu, Degang

    2015-07-01

    This study investigated the electrochemical incineration of nitrilotriacetic acid (NTA) at boron-doped diamond (BDD) and platinum (Pt) anodes. Trials were performed in the presence of sulfate electrolyte media under recirculation mode. The parameters that influence the degradation efficiency were investigated, including applied current density, flow rate, supporting electrolyte concentration and reaction time. To reduce the number of experiments, the system had been managed under chemometric technique named Doehlert matrix. As a consequence, the mineralization of NTA demonstrated similar behavior upon operating parameters on these two anodes. Further kinetic study indicated that the degradations followed pseudo-first-order reactions for both BDD and Pt anodes, and the reaction rate constant of the former was found to be higher than that of the latter. Such difference could be interpreted by results from fractal analysis. In addition, a reaction sequence for NTA mineralization considering all the detected intermediates was also proposed.

  13. Chemometric study on the electrochemical incineration of nitrilotriacetic acid using platinum and boron-doped diamond anode.

    PubMed

    Zhang, Chunyong; He, Zhenzhu; Wu, Jingyu; Fu, Degang

    2015-07-01

    This study investigated the electrochemical incineration of nitrilotriacetic acid (NTA) at boron-doped diamond (BDD) and platinum (Pt) anodes. Trials were performed in the presence of sulfate electrolyte media under recirculation mode. The parameters that influence the degradation efficiency were investigated, including applied current density, flow rate, supporting electrolyte concentration and reaction time. To reduce the number of experiments, the system had been managed under chemometric technique named Doehlert matrix. As a consequence, the mineralization of NTA demonstrated similar behavior upon operating parameters on these two anodes. Further kinetic study indicated that the degradations followed pseudo-first-order reactions for both BDD and Pt anodes, and the reaction rate constant of the former was found to be higher than that of the latter. Such difference could be interpreted by results from fractal analysis. In addition, a reaction sequence for NTA mineralization considering all the detected intermediates was also proposed. PMID:25747300

  14. Oxygen-18 study of the mechanism of promoter action of thiocyanate ions in the electrosynthesis of persulfuric acid and ammonium persulfate at platinum anodes

    SciTech Connect

    Kasatkin, E.V.; Larchenko, L.I.; Potapova, G.F.

    1987-02-01

    The authors use labelled oxygen to study the involvement of water and sulfate ions in molecular oxygen evolution during the anodic synthesis of persulfuric acid and ammonium persulfate at a platinum anode in an electrolytic cell with and without thiocyanate as a promoter for the electrocatalytic reaction.

  15. Beta test results for the CAA mini-SAM system

    SciTech Connect

    Johnson, R.C.; Monagle, M.

    1997-04-01

    The mission of the Chemical Analysis Automation (CAA) Program is to automate methods for chemical analysis of environmental samples. To accomplish this mission, the CAA team has developed automated laboratory systems based on a plug-and-work strategy for integrating components. Realizing that standardization is the key to implementing this strategy, CAA has developed, demonstrated, and encouraged commercialization of standards for laboratory automation. While the CAA mission is driven by the analyses in support of the extensive remediation programs of the Departments of Energy and Defense, it also impacts any industry that depends upon high volumes of repetitive chemical analysis. A Standard Analysis Method (SAM) is any collection of hardware and software used to automate part or all of a method. The method automated for the Mini-SAM testing is EPA Method 3550, which outlines semivolatiles extraction by sonication. The list of semivolatiles includes the polychlorinated biphenyl (PCB) analytes of interest. The basic building block of a SAM is the Standard Laboratory Module (SLM). For the Mini-SAM test an automated sonication SLM and an automated concentration SLM were configured to perform the extraction and concentration processes. The Mini-SAM differs from the Full-SAM in that a fully automated delivery of materials, samples, and extracts is not required. The intent of the Beta Test of the Mini-SAM was threefold. Firstly, the Mini-SAM Beta Test met a milestone mandated by the Department of Energy in the course of the program effort. Secondly, the CAA Program secured an independent assessment of the equipment and its capabilities from Assagai Analytical Laboratory. Lastly, the Program captured real-world sample data. The independent assessment, coupled with CAA observation of equipment performance, was used to determine strengths and weaknesses of the Mini-SAM and to compile possible modifications for CAA engineers to address.

  16. Spontaneous modification of graphite anode by anthraquinone-2-sulfonic acid for microbial fuel cells.

    PubMed

    Tang, Xinhua; Li, Haoran; Du, Zhuwei; Ng, How Yong

    2014-07-01

    In this study, anthraquinone-2-sulfonic acid (AQS), an electron transfer mediator, was immobilized onto graphite felt surface via spontaneous reduction of the in situ generated AQS diazonium cations. Cyclic voltammetry (CV) and energy dispersive spectrometry (EDS) characterizations of AQS modified graphite demonstrated that AQS was covalently grafted onto the graphite surface. The modified graphite, with a surface AQS concentration of 5.37 ± 1.15 × 10(-9)mol/cm(2), exhibited good electrochemical activity and high stability. The midpoint potential of the modified graphite was about -0.248 V (vs. normal hydrogen electrode, NHE), indicating that electrons could be easily transferred from NADH in bacteria to the electrode. AQS modified anode in MFCs increased the maximum power density from 967 ± 33 mW/m(2) to 1872 ± 42 mW/m(2). These results demonstrated that covalently modified AQS functioned as an electron transfer mediator to facilitate extracellular electron transfer from bacteria to electrode and significantly enhanced the power production in MFCs.

  17. Destruction of 4-phenolsulfonic acid in water by anodic contact glow discharge electrolysis.

    PubMed

    Yang, Haiming; An, Baigang; Wang, Shaoyan; Li, Lixiang; Jin, Wenjie; Li, Lihua

    2013-06-01

    Destruction of 4-phenolsulfonic acid (4-PSA) in water was carried out using anodic contact glow discharge electrolysis. Accompanying the decay of 4-PSA, the amount of total organic carbon (TOC) in water correspondingly decreased, while the sulfonate group of 4-PSA was released as sulfate ion. Oxalate and formate were obtained as minor by-products. Additionally, phenol, 1,4-hydroquinone, hydroxyquinol and 1,4-benzoquinone were detected as primary intermediates in the initial stages of decomposition of 4-PSA. A reaction pathway involving successive attacks of hydroxyl and hydrogen radicals was assumed on the basis of the observed products and kinetics. It was revealed that the decay of both 4-PSA and TOC obeyed a first-order rate law. The effects of different Fe ions and initial concentrations of 4-PSA on the degradation rate were investigated. It was found that the presence of Fe ions could increase the degradation rate of 4-PSA, while initial concentrations lower than 80 mmol/L had no significant effect on kinetic behaviour. The disappearance rate of 4-PSA was significantly affected by pH. PMID:24191593

  18. Nanopore formation on the surface oxide of commercially pure titanium grade 4 using a pulsed anodization method in sulfuric acid.

    PubMed

    Williamson, R S; Disegi, J; Griggs, J A; Roach, M D

    2013-10-01

    Titanium and its alloys form a thin amorphous protective surface oxide when exposed to an oxygen environment. The properties of this oxide layer are thought to be responsible for titanium and its alloys biocompatibility, chemical inertness, and corrosion resistance. Surface oxide crystallinity and pore size are regarded to be two of the more important properties in establishing successful osseointegration. Anodization is an electrochemical method of surface modification used for colorization marking and improved bioactivity on orthopedic and dental titanium implants. Research on titanium anodization using sulphuric acid has been reported in the literature as being primarily conducted in molarity levels 3 M and less using either galvanostatic or potentiostatic methods. A wide range of pore diameters ranging from a few nanometers up to 10 μm have been shown to form in sulfuric acid electrolytes using the potentiostatic and galvanostatic methods. Nano sized pores have been shown to be beneficial for bone cell attachment and proliferation. The purpose of the present research was to investigate oxide crystallinity and pore formation during titanium anodization using a pulsed DC waveform in a series of sulfuric acid electrolytes ranging from 0.5 to 12 M. Anodizing titanium in increasing sulfuric acid molarities showed a trend of increasing transformations of the amorphous natural forming oxide to the crystalline phases of anatase and rutile. The pulsed DC waveform was shown to produce pores with a size range from ≤0.01 to 1 μm(2). The pore size distributions produced may be beneficial for bone cell attachment and proliferation. PMID:23807314

  19. Functioning of antimony film electrode in acid media under cyclic and anodic stripping voltammetry conditions.

    PubMed

    Sebez, Bine; Ogorevc, Bozidar; Hocevar, Samo B; Veber, Marjan

    2013-06-27

    New insights into the functioning, i.e. electrochemical behaviour and analytical performance, of in situ prepared antimony film electrodes (SbFEs) under square-wave anodic stripping (SW-ASV) and cyclic (CV) voltammetry conditions are presented by studying several key operational parameters using Pb(II), Cd(II) and Zn(II) as model analyte ions. Five different carbon- and metal-based substrate transducer electrodes revealed a clear advantage of the former ones while the concentration of the precursor Sb(III) ion exhibited a distinct influence on the ASV functioning of the SbFE. Among six acids examined as potential supporting electrolytes the HNO3 was demonstrated to yield nearly identical results in conducting ASV experiments with SbFE as so far almost exclusively used HCl. This is extremely important as HNO3 is commonly employed acidifying agent in trace metal analysis, especially in elemental mass spectrometry measurements. By carrying out a systematic CV and ASV investigation using a medium exchange protocol, we confirmed the formation of poorly soluble oxidized Sb species at the substrate electrode surface at the end of each stripping step, i.e. at the potentials beyond the anodic dissolution of the antimony film. Hence, the significance of the cleaning and initializing the surface of a substrate electrode after accomplishing a stripping step was thoroughly studied in order to find conditions for a complete removal of the adhered Sb-oxides and thus to assure a memory-free functioning of the in situ prepared SbFE. Finally, the practical analytical application of the proposed ASV method was successfully tested and evaluated by measuring the three metal analytes in ground (tap) and surface (river) water samples acidified with HNO3. Our results approved the appropriateness of the SbFE and the proposed method for measuring low μg L(-1) levels of some toxic metals, particularly taking into account the possibility of on-field testing and the use of low cost

  20. Anodic oxidation of ethylenediaminetetraacetic acid on platinum electrode in alkaline medium

    SciTech Connect

    Pakalapati, S.N.R.; Popov, B.N.; White, R.E.

    1996-05-01

    Ethylenediaminetetraacetic acid (EDTA) forms strong metal complexes and is often used to remove scale from heat-transfer equipment and to decontaminate equipment exposed to radioactive material. However, the resultant waste in the form of EDTA-metal complex is hard to treat due to the high stability of such complexes. The anodic oxidation of ethylenediaminetetraacetic acid (EDTA) was studied in alkaline medium on a smooth platinum electrode. Bulk electrolysis indicated that stable organic intermediates (formaldehyde and glyoxal) are formed during the oxidation of EDTA and that complete oxidation to CO{sub 2} can be achieved. The proposed pathway suggests that the acetate groups in EDTA are initially oxidized, generating formaldehyde and ethylenediamine. The rest potential of EDTA (0.066 to 0.164 V vs. Hg/HgO) was observed to be higher than for other organic species. In alkaline medium, very little EDTA oxidation was found to occur on bare platinum. Limiting-current behavior due to PtO formation was observed immediately positive of the rest potential. Tafel behavior (Tafel slope 120 mV/dec) was observed in the potential region positive of the cessation of the bulk of oxide film formation and negative of the onset of O{sub 2} evolution. The reaction order of EDTA was determined to be {approximately}0.5, and that of OH{sup {minus}} was close to zero. The reaction mechanism consistent with the experimental data involves Temkin-type adsorption and a first-electron-transfer rate-determining step.

  1. Leaching lithium from the anode electrode materials of spent lithium-ion batteries by hydrochloric acid (HCl).

    PubMed

    Guo, Yang; Li, Feng; Zhu, Haochen; Li, Guangming; Huang, Juwen; He, Wenzhi

    2016-05-01

    Spent lithium-ion batteries (LIBs) are considered as an important secondary resource for its high contents of valuable components, such as lithium and cobalt. Currently, studies mainly focus on the recycling of cathode electrodes. There are few studies concentrating on the recovery of anode electrodes. In this work, based on the analysis result of high amount of lithium contained in the anode electrode, the acid leaching process was applied to recycle lithium from anode electrodes of spent LIBs. Hydrochloric acid was introduced as leaching reagent, and hydrogen peroxide as reducing agent. Within the range of experiment performed, hydrogen peroxide was found to have little effect on lithium leaching process. The highest leaching recovery of 99.4wt% Li was obtained at leaching temperature of 80°C, 3M hydrochloric acid and S/L ratio of 1:50g/ml for 90min. The graphite configuration with a better crystal structure obtained after the leaching process can also be recycled.

  2. Mineralization of salicylic acid in acidic aqueous medium by electrochemical advanced oxidation processes using platinum and boron-doped diamond as anode and cathodically generated hydrogen peroxide.

    PubMed

    Guinea, Elena; Arias, Conchita; Cabot, Pere Lluís; Garrido, José Antonio; Rodríguez, Rosa María; Centellas, Francesc; Brillas, Enric

    2008-01-01

    Solutions containing 164 mg L(-1) salicylic acid of pH 3.0 have been degraded by electrochemical advanced oxidation processes such as anodic oxidation, anodic oxidation with electrogenerated H(2)O(2), electro-Fenton, photoelectro-Fenton and solar photoelectro-Fenton at constant current density. Their oxidation power has been comparatively studied in a one-compartment cell with a Pt or boron-doped diamond (BDD) anode and a graphite or O(2)-diffusion cathode. In the three latter procedures, 0.5mM Fe(2+) is added to the solution to form hydroxyl radical (()OH) from Fenton's reaction between Fe(2+) and H(2)O(2) generated at the O(2)-diffusion cathode. Total mineralization is attained for all methods with BDD and for photoelectro-Fenton and solar photoelectro-Fenton with Pt. The poor decontamination achieved in anodic oxidation and electro-Fenton with Pt is explained by the slow removal of most pollutants by ()OH formed from water oxidation at the Pt anode in comparison to their quick destruction with ()OH produced at BDD. ()OH generated from Fenton's reaction oxidizes rapidly all aromatic pollutants, but it cannot destroy final Fe(III)-oxalate complexes. Solar photoelectro-Fenton treatments always yield quicker degradation rate due to the very fast photodecarboxylation of these complexes by UVA irradiation supplied by solar light. The effect of current density on the degradation rate, efficiency and energy cost of all methods is examined. The salicylic acid decay always follows a pseudo-first-order kinetics. 2,3-Dihydroxybenzoic, 2,5-dihydroxybenzoic, 2,6-dihydroxybenzoic, alpha-ketoglutaric, glycolic, glyoxylic, maleic, fumaric, malic, tartronic and oxalic acids are detected as oxidation products. A general reaction sequence for salicylic acid mineralization considering all these intermediates is proposed.

  3. Benchmark Solutions for Computational Aeroacoustics (CAA) Code Validation

    NASA Technical Reports Server (NTRS)

    Scott, James R.

    2004-01-01

    NASA has conducted a series of Computational Aeroacoustics (CAA) Workshops on Benchmark Problems to develop a set of realistic CAA problems that can be used for code validation. In the Third (1999) and Fourth (2003) Workshops, the single airfoil gust response problem, with real geometry effects, was included as one of the benchmark problems. Respondents were asked to calculate the airfoil RMS pressure and far-field acoustic intensity for different airfoil geometries and a wide range of gust frequencies. This paper presents the validated that have been obtained to the benchmark problem, and in addition, compares them with classical flat plate results. It is seen that airfoil geometry has a strong effect on the airfoil unsteady pressure, and a significant effect on the far-field acoustic intensity. Those parts of the benchmark problem that have not yet been adequately solved are identified and presented as a challenge to the CAA research community.

  4. Anodized aluminum on LDEF

    NASA Technical Reports Server (NTRS)

    Golden, Johnny L.

    1993-01-01

    A compilation of reported analyses and results obtained for anodized aluminum flown on the Long Duration Exposure Facility (LDEF) was prepared. Chromic acid, sulfuric acid, and dyed sulfuric acid anodized surfaces were exposed to the space environment. The vast majority of the anodized surface on LDEF was chromic acid anodize because of its selection as a thermal control coating for use on the spacecraft primary structure, trays, tray clamps, and space end thermal covers. Reports indicate that the chromic acid anodize was stable in solar absorptance and thermal emittance, but that contamination effects caused increases in absorptance on surfaces exposed to low atomic oxygen fluences. There were some discrepancies, however, in that some chromic acid anodized specimens exhibited significant increases in absorptance. Sulfuric acid anodized surfaces also appeared stable, although very little surface area was available for evaluation. One type of dyed sulfuric acid anodize was assessed as an optical baffle coating and was observed to have improved infrared absorptance characteristics with exposure on LDEF.

  5. Poly (acrylic acid sodium) grafted carboxymethyl cellulose as a high performance polymer binder for silicon anode in lithium ion batteries

    PubMed Central

    Wei, Liangming; Chen, Changxin; Hou, Zhongyu; Wei, Hao

    2016-01-01

    The design of novel binder systems is required for the high capacity silicon (Si) anodes which usually undergo huge volume change during the charge/discharge cycling. Here, we introduce a poly (acrylic acid sodium)-grafted-carboxymethyl cellulose (NaPAA-g-CMC) copolymer as an excellent binder for Si anode in lithium ion batteries (LIBs). The NaPAA-g-CMC copolymer was prepared via a free radical graft polymerization method by using CMC and acrylic acid as precursors. Unlike the linear, one-dimensional binders, the NaPAA-g-CMC copolymer binder is expected to present multi-point interaction with Si surface, resulting in enhanced binding ability with Si particles as well as with the copper (Cu) current collectors, and building a stable solid electrolyte interface (SEI) layer on the Si surface. The NaPAA-g-CMC based Si anode shows much better cycle stability and higher coulombic efficiency than those made with the well-known linear polymeric binders such as CMC and NaPPA. PMID:26786315

  6. Poly (acrylic acid sodium) grafted carboxymethyl cellulose as a high performance polymer binder for silicon anode in lithium ion batteries.

    PubMed

    Wei, Liangming; Chen, Changxin; Hou, Zhongyu; Wei, Hao

    2016-01-01

    The design of novel binder systems is required for the high capacity silicon (Si) anodes which usually undergo huge volume change during the charge/discharge cycling. Here, we introduce a poly (acrylic acid sodium)-grafted-carboxymethyl cellulose (NaPAA-g-CMC) copolymer as an excellent binder for Si anode in lithium ion batteries (LIBs). The NaPAA-g-CMC copolymer was prepared via a free radical graft polymerization method by using CMC and acrylic acid as precursors. Unlike the linear, one-dimensional binders, the NaPAA-g-CMC copolymer binder is expected to present multi-point interaction with Si surface, resulting in enhanced binding ability with Si particles as well as with the copper (Cu) current collectors, and building a stable solid electrolyte interface (SEI) layer on the Si surface. The NaPAA-g-CMC based Si anode shows much better cycle stability and higher coulombic efficiency than those made with the well-known linear polymeric binders such as CMC and NaPPA. PMID:26786315

  7. Poly (acrylic acid sodium) grafted carboxymethyl cellulose as a high performance polymer binder for silicon anode in lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wei, Liangming; Chen, Changxin; Hou, Zhongyu; Wei, Hao

    2016-01-01

    The design of novel binder systems is required for the high capacity silicon (Si) anodes which usually undergo huge volume change during the charge/discharge cycling. Here, we introduce a poly (acrylic acid sodium)-grafted-carboxymethyl cellulose (NaPAA-g-CMC) copolymer as an excellent binder for Si anode in lithium ion batteries (LIBs). The NaPAA-g-CMC copolymer was prepared via a free radical graft polymerization method by using CMC and acrylic acid as precursors. Unlike the linear, one-dimensional binders, the NaPAA-g-CMC copolymer binder is expected to present multi-point interaction with Si surface, resulting in enhanced binding ability with Si particles as well as with the copper (Cu) current collectors, and building a stable solid electrolyte interface (SEI) layer on the Si surface. The NaPAA-g-CMC based Si anode shows much better cycle stability and higher coulombic efficiency than those made with the well-known linear polymeric binders such as CMC and NaPPA.

  8. Elimination of a pollution associated with chromic acid during the electro-deposition of Cr(III) using appropriate anodic and membrane materials in a double film bath.

    PubMed

    Jiang, Xiaojun; Chen, Wenchao; Xu, Hongbo

    2009-01-01

    A method using trivalent chromium has been used to replace hexavalent chromium for the electro-deposition of chromium. Using a tri-chamber bath system various anodic materials and membranes were evaluated to minimize the production of environmentally and health damaging chromic acid. By measuring the absorbance of Cr(VI) at 640 nm, the results indicate that the use of a titanium plated ruthenium (Ti-Ru) anode produces the least amount of chromic acid byproduct compared to lead-gold alloy and graphite anodes. The concentration of Cr(VI) in the immediate vicinity of the Ti-Ru anode decreased from 0.389 mg/L to 0 during a 40-min deposition period. The use of a Nafion(TM) quaternary cation exchange membrane portioning the buffer and anode selectively prevented Cr(III) from entering the anode compartment whilst allowing the migration of H(+) to maintain overall voltaic continuity. It has been demonstrated that the use of a Ti-Ru anode with a Nafion(TM) membrane can eliminate the production of chromic acid associated with the electro-deposition of chromium plate thereby preventing its health damaging exposure to plant operators and preventing discharge of Cr(VI) into the environment. Addition of a surfactant improved current efficiency by 34.7%.

  9. Fourth Computational Aeroacoustics (CAA) Workshop on Benchmark Problems

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D. (Editor)

    2004-01-01

    This publication contains the proceedings of the Fourth Computational Aeroacoustics (CAA) Workshop on Benchmark Problems. In this workshop, as in previous workshops, the problems were devised to gauge the technological advancement of computational techniques to calculate all aspects of sound generation and propagation in air directly from the fundamental governing equations. A variety of benchmark problems have been previously solved ranging from simple geometries with idealized acoustic conditions to test the accuracy and effectiveness of computational algorithms and numerical boundary conditions; to sound radiation from a duct; to gust interaction with a cascade of airfoils; to the sound generated by a separating, turbulent viscous flow. By solving these and similar problems, workshop participants have shown the technical progress from the basic challenges to accurate CAA calculations to the solution of CAA problems of increasing complexity and difficulty. The fourth CAA workshop emphasized the application of CAA methods to the solution of realistic problems. The workshop was held at the Ohio Aerospace Institute in Cleveland, Ohio, on October 20 to 22, 2003. At that time, workshop participants presented their solutions to problems in one or more of five categories. Their solutions are presented in this proceedings along with the comparisons of their solutions to the benchmark solutions or experimental data. The five categories for the benchmark problems were as follows: Category 1:Basic Methods. The numerical computation of sound is affected by, among other issues, the choice of grid used and by the boundary conditions. Category 2:Complex Geometry. The ability to compute the sound in the presence of complex geometric surfaces is important in practical applications of CAA. Category 3:Sound Generation by Interacting With a Gust. The practical application of CAA for computing noise generated by turbomachinery involves the modeling of the noise source mechanism as a

  10. Oxidation of phenol and chlorophenols on platinized titanium anodes in an acidic medium

    NASA Astrophysics Data System (ADS)

    Mokbel, Saleh Mohammed; Kolosov, E. N.; Mikhalenko, I. I.

    2016-06-01

    A comparative study of oxidation of phenol, 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol on Pt/Ti and Ce,Pt/Ti electrocatalysts is performed via cyclic voltammetry. It is shown that the surface morphology and roughness of the anode do not change after modification with cerium. The formal kinetic orders of electrooxidation of all compounds are found to be less than one. It is shown that the β temperature coefficients of the rate of oxidation of chlorophenols grow by 10 to 50% when the Ce,Pt/Ti anode is used at a substrate concentration of 1 mM. A tenfold increase in concentration reduces the effect of cerium additive, except for 3-chlorophenol: the latter exhibits a 250% increase in the β value, compared to the Pt/Ti anode.

  11. Lead dioxide film sonoelectrodeposition in acidic media: Preparation and performance of stable practical anodes.

    PubMed

    Sáez, V; Esclapez, M D; Frías-Ferrer, A J; Bonete, P; Tudela, I; Díez-García, M I; González-García, J

    2011-07-01

    Practical lead dioxide anodes have been obtained by electrodeposition on glassy carbon and titanium substrates in the presence and in the absence of an ultrasound field. The films obtained by mechanical agitation on glassy carbon are strongly improved when the electrodeposition process is carried out with the ultrasound field, providing adherent deposits free from nodules and stress, but with pores appearing occasionally. These enhanced properties were not achieved by mechanical conditions, even when optimization of temperature, current density, additives and geometrical aspects was attempted. The best practical anodes were obtained by sonoelectrodeposition using specially treated titanium as substrate, providing comparable behavior to commercial electrodes. PMID:21195010

  12. Amorphous polymeric anode materials from poly(acrylic acid) and tin(II) oxide for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hiroyuki; Nakanishi, Shinji; Iba, Hideki; Itoh, Takahito

    2015-02-01

    The reaction of poly(acrylic acid) (PAA) and tin oxide (II) (SnO) provides an amorphous product (PSnA), which was found to be a promising precursor of an anode material for lithium ion batteries. The anode electrode composed of PSnA as the active material and polyimide as the binder showed a better cycling performance than the anode electrode using SnO as the active material. It is considered that the organic polymer chain present in PSnA might act as a buffer to the volume change in the active material during the charge-discharge cycles. The X-ray diffraction (XRD) results of the electrode after delithiation revealed that nano-sized cubic tin (α-Sn) and tetragonal tin (β-Sn) particles are formed in the active material. Therefore, it is concluded that these nano-sized tin particles in the polymer matrix were effective for the storage and release of Li ions.

  13. Preparing the CAA Title V operating permit application

    SciTech Connect

    Wyles, T.R. )

    1994-01-01

    The CAA amendments contain 11 new and amended titles, including enhanced non-attainment area provisions, additional conditions for controlling hazardous air pollutants, expanded monitoring and record keeping requirements, and increased enforcement authority. The cornerstone of the regulation is the operating permits program (Title V). In the past, permits have been issued to construct or modify sources, and some sources have been permitted in states with operating permit programs. Such programs will remain in effect. However, under the new CAA, most emissions sources will be required to have an operating permit. Title V's permit provision initially affects about 34,000 major facilities and may affect another 350,000 smaller sources in the future. The amendments also increase the number of regulated pollutants from 21 to about 200. Operating permits limit emissions from manufacturing operations, and place further restrictions on raw materials and products.

  14. Third Computational Aeroacoustics (CAA) Workshop on Benchmark Problems

    NASA Technical Reports Server (NTRS)

    Dahl, Milo D. (Editor)

    2000-01-01

    The proceedings of the Third Computational Aeroacoustics (CAA) Workshop on Benchmark Problems cosponsored by the Ohio Aerospace Institute and the NASA Glenn Research Center are the subject of this report. Fan noise was the chosen theme for this workshop with representative problems encompassing four of the six benchmark problem categories. The other two categories were related to jet noise and cavity noise. For the first time in this series of workshops, the computational results for the cavity noise problem were compared to experimental data. All the other problems had exact solutions, which are included in this report. The Workshop included a panel discussion by representatives of industry. The participants gave their views on the status of applying computational aeroacoustics to solve practical industry related problems and what issues need to be addressed to make CAA a robust design tool.

  15. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are also…

  16. Hybrid CFD/CAA Modeling for Liftoff Acoustic Predictions

    NASA Technical Reports Server (NTRS)

    Strutzenberg, Louise L.; Liever, Peter A.

    2011-01-01

    This paper presents development efforts at the NASA Marshall Space flight Center to establish a hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) simulation system for launch vehicle liftoff acoustics environment analysis. Acoustic prediction engineering tools based on empirical jet acoustic strength and directivity models or scaled historical measurements are of limited value in efforts to proactively design and optimize launch vehicles and launch facility configurations for liftoff acoustics. CFD based modeling approaches are now able to capture the important details of vehicle specific plume flow environment, identifY the noise generation sources, and allow assessment of the influence of launch pad geometric details and sound mitigation measures such as water injection. However, CFD methodologies are numerically too dissipative to accurately capture the propagation of the acoustic waves in the large CFD models. The hybrid CFD/CAA approach combines the high-fidelity CFD analysis capable of identifYing the acoustic sources with a fast and efficient Boundary Element Method (BEM) that accurately propagates the acoustic field from the source locations. The BEM approach was chosen for its ability to properly account for reflections and scattering of acoustic waves from launch pad structures. The paper will present an overview of the technology components of the CFD/CAA framework and discuss plans for demonstration and validation against test data.

  17. Effect of various de-anodizing techniques on the surface stability of non-colored and colored nanoporous AAO films in acidic solution

    NASA Astrophysics Data System (ADS)

    Awad, Ahmed M.; Shehata, Omnia S.; Heakal, Fakiha El-Taib

    2015-12-01

    Anodic aluminum oxide (AAO) is well known as an important nanostructured material, and a useful template in the fabrication of nanostructures. Nanoporous anodic alumina (PAA) with high open porosity was prepared by adopting three de-anodizing regimes following the first anodizing step and preceding the second one. The de-anodizing methods include electrolytic etching (EE) and chemical etching using either phosphoric acid (PE) or sodium hydroxide (HE) solutions. Three of the obtained AAO samples were black colored by electrodeposition of copper nanoparticles in their pores. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques were used to characterize the electrochemical performance of the two sets of the prepared samples. In general, the data obtained in aggressive aerated 0.5 M HCl solution demonstrated dissimilar behavior for the three prepared samples despite that the second anodizing step was the same for all of them. The data indicated that the resistance and thickness of the inner barrier part of nano-PAA film, are the main controlling factors determining its stability. On the other hand, coloring the film decreased its stability due to the galvanic effect. The difference in the electrochemical behavior of the three colored samples was discussed based on the difference in both the pore size and thickness of the outer porous part of PAA film as supported by SEM, TEM and cross-sectional micrographs. These results can thus contribute for better engineering applications of nanoporous AAO.

  18. Cluster Ion Spectrometry (CIS) Data Archiving in the CAA

    NASA Astrophysics Data System (ADS)

    Dandouras, I. S.; Barthe, A.; Penou, E.; Brunato, S.; Reme, H.; Kistler, L. M.; Blagau, A.; Facsko, G.; Kronberg, E.; Laakso, H. E.

    2009-12-01

    The Cluster Active Archive (CAA) aims at preserving the four Cluster spacecraft data, so that they are usable in the long-term by the scientific community as well as by the instrument team PIs and Co-Is. This implies that the data are filed together with the descriptive and documentary elements making it possible to select and interpret them. The CIS (Cluster Ion Spectrometry) experiment is a comprehensive ionic plasma spectrometry package onboard the four Cluster spacecraft, capable of obtaining full three-dimensional ion distributions (about 0 to 40 keV/e) with a time resolution of one spacecraft spin (4 sec) and with mass-per-charge composition determination. The CIS package consists of two different instruments, a Hot Ion Analyser (HIA) and a time-of-flight ion Composition Distribution Function (CODIF) analyser. For the archival of the CIS data a multi-level approach has been adopted. The CAA archival includes processed raw data (Level 1 data), moments of the ion distribution functions (Level 2 data), and calibrated high-resolution data in a variety of physical units (Level 3 data). The latter are 3-D ion distribution functions and 2-D pitch-angle distributions. In addition, a software package has been developed to allow the CAA user to interactively calculate partial or total moments of the ion distributions. Instrument cross-calibration has been an important activity in preparing the data for archival. The CIS data archive includes also experiment documentation, graphical products for browsing through the data, and data caveats. In addition, data quality indexes are under preparation, to help the user. Given the complexity of an ion spectrometer, and the variety of its operational modes, each one being optimised for a different magnetospheric region or measurement objective, consultation of the data caveats by the end user will always be a necessary step in the data analysis.

  19. Many new CAA requirements, deadlines scheduled during next five years

    SciTech Connect

    Iwanchuk, R. )

    1993-06-01

    Since the CAA Amendments were signed into law, EPA's rulemaking process has been underway, delineating specific compliance regulations. Many of the legislation's requirements and deadlines will be finalized over the next five years. The following list summarizes upcoming regulations and anticipated compliance deadlines. Title I applies to VOC and NOx controls in ozone non-attainment areas. Title III contains the Hazardous Organic National Emission Standard for Hazardous Air Pollutants. Title V consists of the operating permit rule. Title VII applies to the enhanced monitoring rule. The rule will require major sources to enhance monitoring systems to determine whether compliance is continuous or intermittent.

  20. Phase transformations of high-purity PbI2 nanoparticles synthesized from lead-acid accumulator anodes

    NASA Astrophysics Data System (ADS)

    Malevu, T. D.; Ocaya, R. O.; Tshabalala, K. G.

    2016-09-01

    High-purity hexagonal lead iodide nanoparticles have been synthesized from a depleted sealed lead acid battery anode. The synthesized product was found to consist of the rare 6R polytype form of PbI2 that is thought to have good potential in photovoltaic applications. We investigate the effects of annealing time and post-melting temperature on the structure and optical properties using 1.5418 Å CuKα radiation. Photoluminescence measurements were done under 150 W/221 nm wavelength xenon excitation. Phase transformation was observed through XRD peaks when annealing time increased from 0.5-5 h. The nanoparticle grain size and inter-planar distance appeared to be independent of annealing time. PL measurements show three broad peaks in a range of 400 nm to 700 nm that are attributed to excitonic, donor-acceptor pair and luminescence bands from the deep levels.

  1. Removal of Acid Black 194 dye from water by electrocoagulation with aluminum anode.

    PubMed

    Vidal, Jorge; Villegas, Loreto; Peralta-Hernández, Juan M; Salazar González, Ricardo

    2016-01-01

    Application of an electrocoagulation process (EC) for the elimination of AB194 textile dye from synthetic and textile wastewater (effluent) contaminated with AB194 dye, was carried out using aluminum anodes at two different initial pH values. Tafel studies in the presence and absence of the dye were performed. The aluminum species formed during the electrolysis were quantified by atomic absorption, and the flocs formed in the process were analyzed by HPLC-MS. Complete removal of AB194 from 1.0 L of solution was achieved applying low densities current at initial pH values of 4.0 and 8.0. The removal of AB194 by EC was possible with a short electrolysis time, removing practically 100% of the total organic carbon content and chemical oxygen demand. The final result was completely discolored water lacking dye and organic matter. An effluent contaminated with 126 mg L(-1) AB194 dye from a Chilean textile industry was also treated by EC under optimized experimental conditions, yielding discolored water and considerably decreasing the presence of organic compounds (dye + dyeing additives), with very low concentrations of dissolved Al(3+). Analysis of flocs showed the presence of the original dye without changes in its chemical structure.

  2. Removal of Acid Black 194 dye from water by electrocoagulation with aluminum anode.

    PubMed

    Vidal, Jorge; Villegas, Loreto; Peralta-Hernández, Juan M; Salazar González, Ricardo

    2016-01-01

    Application of an electrocoagulation process (EC) for the elimination of AB194 textile dye from synthetic and textile wastewater (effluent) contaminated with AB194 dye, was carried out using aluminum anodes at two different initial pH values. Tafel studies in the presence and absence of the dye were performed. The aluminum species formed during the electrolysis were quantified by atomic absorption, and the flocs formed in the process were analyzed by HPLC-MS. Complete removal of AB194 from 1.0 L of solution was achieved applying low densities current at initial pH values of 4.0 and 8.0. The removal of AB194 by EC was possible with a short electrolysis time, removing practically 100% of the total organic carbon content and chemical oxygen demand. The final result was completely discolored water lacking dye and organic matter. An effluent contaminated with 126 mg L(-1) AB194 dye from a Chilean textile industry was also treated by EC under optimized experimental conditions, yielding discolored water and considerably decreasing the presence of organic compounds (dye + dyeing additives), with very low concentrations of dissolved Al(3+). Analysis of flocs showed the presence of the original dye without changes in its chemical structure. PMID:26745322

  3. CAA for Jet Noise Physics: Issues and Recent Progress

    NASA Technical Reports Server (NTRS)

    Mankbadi, Reda

    2001-01-01

    Dr. Mankbadi summarized recent CAA results. Examples of the effect of various boundary condition schemes on the computed acoustic field, for a point source in a uniform flow, were shown. Solutions showing the impact of inflow excitations on the result were also shown. Results from a large eddy simulation, using a fourth-order MacCormack scheme with a Smagorinsky sub-grid turbulence model, were shown for a Mach 2.1 unheated jet. The results showed that the results were free from spurious modes. Results were shown for a Mach 1.4 jet using LES in the near field and the Kirchhoff method for the far field. Predicted flow field characteristics were shown to be in good agreement with data and predicted far field directivities were shown to be in qualitative agree with experimental measurements.

  4. Using Focus Groups to Investigate the Presence of Formative Feedback in CAA

    ERIC Educational Resources Information Center

    Broughton, Stephen; Hernandez-Martinez, Paul; Robinson, Carol L.

    2012-01-01

    The aim of this project was to examine the effectiveness of feedback offered by computer-aided assessment (CAA). CAA provides practice tests for undergraduates, and feedback to help them improve their scores and mathematical understanding. However, there is a lack of evidence-based literature on the effect of formative feedback in mathematics…

  5. Anodes - Technology review

    NASA Astrophysics Data System (ADS)

    Wallis, L.; Wills, R. G. A.

    2014-06-01

    Many electrochemical energy storage technologies utilize anodes that are specific to the chemistry of the device. Anodes must be designed for devices including primary and secondary batteries, fuel cells and capacitors. These applications include a diverse range of operational conditions, including aqueous, solid or organic media. This paper will provide a brief overview of anode technologies for medium (e.g. electric and hybrid electric vehicles) and large (e.g. integration of renewable energy generation to electrical networks) battery applications. Established and developing storage technologies will be discussed to provide an insight into how anodes (materials, manufacturing processes and modes of operation) differ between specific applications and devices. Lead-acid batteries are used as a case study to provide a practical example and guide discussion onto the question of future challenges and opportunities.

  6. Multifunctional co-poly(amic acid): A new binder for Si-based micro-composite anode of lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Lin, Che-Tseng; Huang, Tzu-Yang; Huang, Jau-Jiun; Wu, Nae-Lih; Leung, Man-kit

    2016-10-01

    Multifunctional co-poly(amic acid) (PAmA) containing pyrene and carboxylic acid side-chains is developed as a binder for the recycled kerf-loss Si-Ni-SiC composite anode. The capacity retention performance of the lithium-ion battery can be apparently enhanced. In a long-cycle test of 300 lithiation/delithiation cycles, 79% of capacity retention is achieved. In considering that the recycled kerf-loss Si sample contains 38 wt% inactive micro-sized SiC abrasive particles, the achieved capacity of 648 mAh g-1 is reasonably high in comparison to other reported values. Small anode thickness expansion of 43% is found in a 100 cycle test, reflecting that the use of the PAmA binder can create strong interconnection among the silicon particles, conductive carbons and copper electrode.

  7. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

    SciTech Connect

    Zhu, Jing; Zheng, Xin; Wang, Jie; Wu, Zexing; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/C and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.

  8. Structurally ordered Pt–Zn/C series nanoparticles as efficient anode catalysts for formic acid electrooxidation

    DOE PAGES

    Zhu, Jing; Zheng, Xin; Wang, Jie; Wu, Zexing; Han, Lili; Lin, Ruoqian; Xin, Huolin L.; Wang, Deli

    2015-09-15

    Controlling the size, composition, and structure of bimetallic nanoparticles is of particular interest in the field of electrocatalysts for fuel cells. In the present work, structurally ordered nanoparticles with intermetallic phases of Pt3Zn and PtZn have been successfully synthesized via an impregnation reduction method, followed by post heat-treatment. The Pt3Zn and PtZn ordered intermetallic nanoparticles are well dispersed on a carbon support with ultrasmall mean particle sizes of ~5 nm and ~3 nm in diameter, respectively, which are credited to the evaporation of the zinc element at high temperature. These catalysts are less susceptible to CO poisoning relative to Pt/Cmore » and exhibited enhanced catalytic activity and stability toward formic acid electrooxidation. The mass activities of the as-prepared catalysts were approximately 2 to 3 times that of commercial Pt at 0.5 V (vs. RHE). As a result, this facile synthetic strategy is scalable for mass production of catalytic materials.« less

  9. Process for anodizing aluminum foil

    SciTech Connect

    Ball, J.A.; Scott, J.W.

    1984-11-06

    In an integrated process for the anodization of aluminum foil for electrolytic capacitors including the formation of a hydrous oxide layer on the foil prior to anodization and stabilization of the foil in alkaline borax baths during anodization, the foil is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing the borax solution having a pH of 8.5 to 9.5 and a temperature above 80/sup 0/ C. and then reanodizing the foil. The process is useful in anodizing foil to a voltage of up to 760 V.

  10. Kinetic modeling of 2,4-dichlorophenoxyacetic acid (2,4-D) degradation in soil slurry by anodic fenton treatment.

    PubMed

    Kong, Lingjun; Lemley, Ann T

    2006-05-31

    Anodic Fenton treatment (AFT) has been shown to be a promising technology in pesticide wastewater treatment. However, no research has been conducted on the AFT application to contaminated soils. In this study, the 2,4-D degradation kinetics of AFT in a silt loam soil slurry were investigated for the first time, and the effects of various experimental conditions including initial 2,4-D concentration, Fenton reagent delivery rate, amount of humic acid (HA) addition, and pH were examined. The 2,4-D degradation in soil slurry by AFT was found to follow a two-stage kinetic model. During the early stage of AFT (the first 4-5 min), the 2,4-D concentration profile followed a pseudo-first-order kinetic model. In the later stage (typically after 5 or 6 min), the AFT kinetic model provided a better fit. This result is most likely due to the existence of (*)OH scavengers and 2,4-D sorption on soil. The Fe(2+) delivery rate was shown to be a more significant factor in degradation rate than the H(2)O(2) delivery rate when the Fe(2+)/H(2)O(2) ratios were in the range of 1:2 to 1:10. The presence of HA in soil lowered the AFT rate, most probably due to the competition with 2,4-D for consumption of (*)OH and increased sorption of 2,4-D on soil. The optimal pH for 2,4-D degradation in soil slurry by AFT was observed to be in the range of pH 2-3.

  11. Electro-fenton and photoelectro-fenton degradation of sulfanilic acid using a boron-doped diamond anode and an air diffusion cathode.

    PubMed

    El-Ghenymy, Abdellatif; Garrido, José Antonio; Centellas, Francesc; Arias, Conchita; Cabot, Pere Lluís; Rodríguez, Rosa María; Brillas, Enric

    2012-04-01

    The mineralization of sulfanilic acid has been studied by electro-Fenton (EF) and photoelectro-Fenton (PEF) reaction with UVA light using an undivided electrochemical cell with a boron-doped diamond (BDD) anode and an air diffusion cathode able to generate H(2)O(2). Organics were then oxidized by hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton's reaction between generated H(2)O(2) and added Fe(2+). The UVA irradiation in PEF enhanced the production of hydroxyl radicals in the bulk, accelerating the removal of organics and photodecomposed intermediates like Fe(III)-carboxylate complexes. Partial decontamination of 1.39 mM sulfanilic acid solutions was achieved by EF until 100 mA cm(-2) at optimum conditions of 0.4 mM Fe(2+) and pH 3.0. The increase in current density and substrate content led to an almost total mineralization. In contrast, the PEF process was more powerful, yielding almost complete mineralization in less electrolysis time under comparable conditions. The kinetics for sulfanilic acid decay always followed a pseudo-first-order reaction. Hydroquinone and p-benzoquinone were detected as aromatic intermediates, whereas acetic, maleic, formic, oxalic, and oxamic acids were identified as generated carboxylic acids. NH(4)(+) ion was preferentially released in both treatments, along with NO(3)(-) ion in smaller proportion.

  12. Anodic films

    SciTech Connect

    Muller, R.H.

    1983-08-01

    Surface layers are formed on many metals by anodic reaction. Such layers include the products of charge and discharge in many storage batteries, dielectric films used in electronic and optical circuits and display devices, layers responsible for passivity and corrosion protection, and films generated in metal shaping and finishing operations such as anodization, coloring, electropolishing, electrochemical machining and deburring. Anodic films are formed by solid-solid transformations or by dissolution-precipitation processes. Film properties and mechanisms of formation can be determined in situ by a number of optical techniques which have recently become available.

  13. 2 CFR 1532.1120 - What is the purpose of CAA or CWA disqualification?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... and Reinstatement Under the Clean Air Act and Clean Water Act § 1532.1120 What is the purpose of CAA or CWA disqualification? As provided for in Executive Order 11738 (3 CFR, 1973 Comp., p. 799),...

  14. 2 CFR 1532.1120 - What is the purpose of CAA or CWA disqualification?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... and Reinstatement Under the Clean Air Act and Clean Water Act § 1532.1120 What is the purpose of CAA or CWA disqualification? As provided for in Executive Order 11738 (3 CFR, 1973 Comp., p. 799),...

  15. 2 CFR 1532.1120 - What is the purpose of CAA or CWA disqualification?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... and Reinstatement Under the Clean Air Act and Clean Water Act § 1532.1120 What is the purpose of CAA or CWA disqualification? As provided for in Executive Order 11738 (3 CFR, 1973 Comp., p. 799),...

  16. 2 CFR 1532.1120 - What is the purpose of CAA or CWA disqualification?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... and Reinstatement Under the Clean Air Act and Clean Water Act § 1532.1120 What is the purpose of CAA or CWA disqualification? As provided for in Executive Order 11738 (3 CFR, 1973 Comp., p. 799),...

  17. Studies on the enhancement of solid electrolyte interphase formation on graphitized anodes in LiX-carbonate based electrolytes using Lewis acid additives for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Li, L. F.; Xie, B.; Lee, H. S.; Li, H.; Yang, X. Q.; McBreen, J.; Huang, X. J.

    The new electrolyte systems utilizing one type of Lewis acids, the boron based anion receptors (BBARs) with LiF, Li 2O, or Li 2O 2 in carbonate solutions have been developed and reported by us. These systems open up a new approach in developing non-aqueous electrolytes with higher operating voltage and less moisture sensitivity for lithium-ion batteries. However, the formation of a stable solid electrolyte interphase (SEI) layer on the graphitized anodes is a serious problem needs to be solved for these new electrolyte systems, especially when propylene carbonate (PC) is used as a co-solvent. Using lithium bis(oxalato)borate (LiBOB) as an additives, the SEI layer formation on mesophase carbon microbeads (MCMB) anode is significantly enhanced in these new electrolytes containing boron-based anion receptors, such as tris(pentafluorophenyl) borane, and lithium salt such as LiF, or lithium oxides such as Li 2O or Li 2O 2 in PC and dimethyl carbonate (DMC) solvents. The cells using these electrolytes and MCMB anodes cycled very well and the PC co-intercalation was suppressed. Fourier transform infrared spectroscopy (FTIR) studies show that one of the electrochemical decomposition products of LiBOB, lithium carbonate (Li 2CO 3), plays a quite important role in the stablizing SEI layer formation.

  18. Self-ordered nanopore arrays through hard anodization assisted by anode temperature ramp

    NASA Astrophysics Data System (ADS)

    Mohammadniaei, M.; Maleki, K.; Kashi, M. Almasi; Ramezani, A.; Mayamei, Y.

    2016-10-01

    In the present work, hard anodization assisted by anode temperature ramp was employed to fabricate self-ordered nanoporous alumina in the wide range of interpore distances (259-405 nm) in pure oxalic acid and mixture of oxalic and phosphoric acid solutions. Anode temperature ramp technique was employed to adjust the anodization current density to optimize the self-ordering of the nanopore arrays in the interpore range in which no ordered self-assembled hard anodized anodic aluminum oxide has reported. It is found that the certain ratios of oxalic and phosphoric acid solutions in this anodization technique increased self-ordering of the nanopores especially for anodization voltages over the 170 V by increasing alumina's viscous flow which could lead to decrease the overall current density of anodization, yet leveled up by anode temperature ramp. However, below 150 V anodization voltage, the ratio of interpore distance to the anodization voltage of the both anodization techniques was the same (~2 nm/V), while above this voltage, it increased to about 2.2 nm/V.

  19. Electrodegradation of the Acid Green 28 dye using Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes.

    PubMed

    Irikura, Kallyni; Bocchi, Nerilso; Rocha-Filho, Romeu C; Biaggio, Sonia R; Iniesta, Jesús; Montiel, Vicente

    2016-12-01

    The statistical Response Surface Methodology (RSM) is applied to investigate the effect of different parameters (current density, j, NaCl concentration, [NaCl], pH, and temperature, θ) and their interactions on the electrochemical degradation of the Acid Green (AG) 28 dye using a Ti/β-PbO2 or Ti-Pt/β-PbO2 anode in a filter-press reactor. LC/MS is employed to identify intermediate compounds. For both anodes, the best experimental conditions are j = 50 mA cm(-2), [NaCl] = 1.5 g L(-1), pH = 5, and θ = 25 °C. After 3 h of electrolysis, a dye solution treated under these conditions presents the following parameters: electric charge per unit volume of the electrolyzed solution required for 90% decolorization (Q(90)) of 0.34-0.37 A h L(-1), %COD removal of ∼100%, specific energy consumption of 18-20 kW h m(-3), and %TOC removal of 32-33%. No loss of the β-PbO2 film is observed during all the experiments. The β-PbO2 films present excellent stability for solutions with pH ≥ 5 ([Pb(2+)] < 0.5 mg L(-1)). Chloroform is the only volatile organic halo compound present in the treated solution under those optimized conditions. Hydroxylated anthraquinone derivatives, aromatic chloramines, and naphthoquinones are formed during the electrolyses. The Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes show significantly better performance than a commercial DSA anode for the electrochemical degradation of the AG 28 dye. The Ti/β-PbO2 anode, prepared as described in this work, is an excellent option for the treatment of textile effluents because of its low cost of fabrication and good performance. PMID:27604754

  20. Electrodegradation of the Acid Green 28 dye using Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes.

    PubMed

    Irikura, Kallyni; Bocchi, Nerilso; Rocha-Filho, Romeu C; Biaggio, Sonia R; Iniesta, Jesús; Montiel, Vicente

    2016-12-01

    The statistical Response Surface Methodology (RSM) is applied to investigate the effect of different parameters (current density, j, NaCl concentration, [NaCl], pH, and temperature, θ) and their interactions on the electrochemical degradation of the Acid Green (AG) 28 dye using a Ti/β-PbO2 or Ti-Pt/β-PbO2 anode in a filter-press reactor. LC/MS is employed to identify intermediate compounds. For both anodes, the best experimental conditions are j = 50 mA cm(-2), [NaCl] = 1.5 g L(-1), pH = 5, and θ = 25 °C. After 3 h of electrolysis, a dye solution treated under these conditions presents the following parameters: electric charge per unit volume of the electrolyzed solution required for 90% decolorization (Q(90)) of 0.34-0.37 A h L(-1), %COD removal of ∼100%, specific energy consumption of 18-20 kW h m(-3), and %TOC removal of 32-33%. No loss of the β-PbO2 film is observed during all the experiments. The β-PbO2 films present excellent stability for solutions with pH ≥ 5 ([Pb(2+)] < 0.5 mg L(-1)). Chloroform is the only volatile organic halo compound present in the treated solution under those optimized conditions. Hydroxylated anthraquinone derivatives, aromatic chloramines, and naphthoquinones are formed during the electrolyses. The Ti/β-PbO2 and Ti-Pt/β-PbO2 anodes show significantly better performance than a commercial DSA anode for the electrochemical degradation of the AG 28 dye. The Ti/β-PbO2 anode, prepared as described in this work, is an excellent option for the treatment of textile effluents because of its low cost of fabrication and good performance.

  1. MetaCAA: A clustering-aided methodology for efficient assembly of metagenomic datasets.

    PubMed

    Reddy, Rachamalla Maheedhar; Mohammed, Monzoorul Haque; Mande, Sharmila S

    2014-01-01

    A key challenge in analyzing metagenomics data pertains to assembly of sequenced DNA fragments (i.e. reads) originating from various microbes in a given environmental sample. Several existing methodologies can assemble reads originating from a single genome. However, these methodologies cannot be applied for efficient assembly of metagenomic sequence datasets. In this study, we present MetaCAA - a clustering-aided methodology which helps in improving the quality of metagenomic sequence assembly. MetaCAA initially groups sequences constituting a given metagenome into smaller clusters. Subsequently, sequences in each cluster are independently assembled using CAP3, an existing single genome assembly program. Contigs formed in each of the clusters along with the unassembled reads are then subjected to another round of assembly for generating the final set of contigs. Validation using simulated and real-world metagenomic datasets indicates that MetaCAA aids in improving the overall quality of assembly. A software implementation of MetaCAA is available at https://metagenomics.atc.tcs.com/MetaCAA.

  2. The anodic passivation of lithium

    SciTech Connect

    James, S.D.

    1983-10-01

    The anodic passivation of Li has been characterized at room temperature in a variety of electrolytes (propylene carbonate, thionyl chloride, sulfur dioxide), as a function of convection and current density and in the presence of water and other impurities. In thionyl chloride the effect of salt concentration (0.5-4.5M, LiA1C1/sub 4/) and acidity (0.5-3M, A1C1/sub 3/) has been studied. The evidence accumulated suggests that anodic passivation is caused by anodic enrichment and eventual precipitation of electrolyte salt in superficial anolyte.

  3. ANODIC TREATMENT OF URANIUM

    DOEpatents

    Kolodney, M.

    1959-02-01

    A method is presented for effecting eloctrolytic dissolution of a metallic uranium article at a uniform rate. The uranium is made the anode in an aqueous phosphoric acid solution containing nitrate ions furnished by either ammonium nitrate, lithium nitrate, sodium nitrate, or potassium nitrate. A stainless steel cathode is employed and electrolysls carried out at a current density of about 0.1 to 1 ampere per square inch.

  4. In-situ electrochemical measurements of total concentration and speciation of heavy metals in acid mine drainage (AMD): assessment of the use of anodic stripping voltammetry.

    PubMed

    Jung, Hun-Bok; Yun, Seong-Taek; Kim, Soon-Oh; Jung, Myung Chae; So, Chil-Sup; Koh, Yong-Kwon

    2006-06-01

    We assessed the use of anodic stripping voltammetry (ASV) for in-situ determinations of both total concentration and speciation of dissolved heavy metals (Cd, Cu, Pb and Zn) in acid mine drainage (AMD). In the Kwangyang Au-Ag mine area of South Korea, different sites with varying water chemistry within an AMD were studied with a field portable anodic stripping voltammeter. Anodic stripping voltammetry after wet oxidation (acidification) was very sensitive enough to determine total concentration of dissolved Cd because Cd was dominantly present as 'labile' species, whilst the technique was not so effective for determining total Cu especially in the downstream sites from the retention pond, due to its complexation with organic matter. For dissolved Pb, the concentrations determined by ASV after wet oxidation generally agreed with those by ICP-AES. In the downstream samples (pH>5), however, ASV data after wet oxidation were lower than ICP-AES data because a significant fraction of dissolved Pb was present in those samples as 'inert' species associated with colloidal iron oxide particles. The determination of total dissolved Zn by ASV after wet oxidation appeared to be unsatisfactory for the samples with high Cu content, possibly due to the interference by the formation of Zn-Cu intermetallic compounds on the mercury coated electrode. In AMD samples with high dissolved iron, use of ultraviolet irradiation was not effective for determining total concentrations because humate destruction by UV irradiation possibly resulted in the removal of a part of dissolved heavy metals from waters through the precipitation of iron hydroxides. PMID:16767566

  5. High cycling stability of anodes for lithium-ion batteries based on Fe3O4 nanoparticles and poly(acrylic acid) binder

    NASA Astrophysics Data System (ADS)

    Maroni, F.; Gabrielli, S.; Palmieri, A.; Marcantoni, E.; Croce, F.; Nobili, F.

    2016-11-01

    Fe3O4 nanoparticles synthesized by a base catalyzed method are tested as anode material for Li-ion batteries. The pristine nanoparticles are morphologically characterized showing an average size of 11 nm. Electrodes are prepared using high-molecular weight Poly (acrylic acid) as improved binder and ethanol as low cost and environmentally friendly solvent. The evaluation of electrochemical properties shows high specific capacity values of 857 mA hg-1 after 200 cycles at a specific current of 462 mAg-1, as well as an excellent rate capability with specific current values up to 18480 mAg-1. To the best of our knowledge, this is the first report of Fe3O4 nanoparticles cycling with PAA as binder.

  6. CFD-CAA Coupled Calculations of a Tandem Cylinder Configuration to Assess Facility Installation Effects

    NASA Technical Reports Server (NTRS)

    Redonnet, Stephane; Lockard, David P.; Khorrami, Mehdi R.; Choudhari, Meelan M.

    2011-01-01

    This paper presents a numerical assessment of acoustic installation effects in the tandem cylinder (TC) experiments conducted in the NASA Langley Quiet Flow Facility (QFF), an open-jet, anechoic wind tunnel. Calculations that couple the Computational Fluid Dynamics (CFD) and Computational Aeroacoustics (CAA) of the TC configuration within the QFF are conducted using the CFD simulation results previously obtained at NASA LaRC. The coupled simulations enable the assessment of installation effects associated with several specific features in the QFF facility that may have impacted the measured acoustic signature during the experiment. The CFD-CAA coupling is based on CFD data along a suitably chosen surface, and employs a technique that was recently improved to account for installed configurations involving acoustic backscatter into the CFD domain. First, a CFD-CAA calculation is conducted for an isolated TC configuration to assess the coupling approach, as well as to generate a reference solution for subsequent assessments of QFF installation effects. Direct comparisons between the CFD-CAA calculations associated with the various installed configurations allow the assessment of the effects of each component (nozzle, collector, etc.) or feature (confined vs. free jet flow, etc.) characterizing the NASA LaRC QFF facility.

  7. 40 CFR 59.1 - Final determinations under Section 183(e)(3)(C) of the CAA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Final determinations under Section 183(e)(3)(C) of the CAA. 59.1 Section 59.1 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER...

  8. 40 CFR 59.1 - Final determinations under Section 183(e)(3)(C) of the CAA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Final determinations under Section 183(e)(3)(C) of the CAA. 59.1 Section 59.1 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL VOLATILE ORGANIC COMPOUND EMISSION STANDARDS FOR CONSUMER...

  9. Synthesis and screening of a CaaL peptide library versus FTase reveals a surprising number of substrates

    PubMed Central

    Krzysiak, Amanda J.; Aditya, Animesh V.; Hougland, James L.; Fierke, Carol A.; Gibbs, Richard A.

    2010-01-01

    Proteins bearing a CaaL sequence are typically geranylgeranylated to enable their proper localization and function. We found that many of the dansyl-GCaaL peptides representing mammalian CaaL proteins can be farnesylated by FTase. This result may have important implications for prenylated protein biology. PMID:20005705

  10. Mechanism of Enhanced Electrochemical Oxidation of 2,4-dichlorophenoxyacetic Acid with in situ Microwave Activated Boron-doped Diamond and Platinum Anodes

    NASA Astrophysics Data System (ADS)

    Gao, Junxia; Zhao, Guohua; Liu, Meichuan; Li, Dongming

    2009-09-01

    Remarkable enhancement in degradation effect is achieved at in situ activated boron-doped diamond (BDD) and Pt anodes with different extent through electrochemical oxidation (EC) of 2,4-dichlorophenoxyacetic acid (2,4-D) with microwave (MW) radiation in a flow system. Results show that when EC is activated with MW radiation, the complete mineralization time of 2,4-D at the BDD is reduced quickly from 10 to 4 h while Chemical oxygen demand (COD) removal at Pt is increased from 37.7 to 58.3% at 10 h; the initial current efficiency is both improved about 1.5 times while the pseudo-first-order rate constant is increased by 153 and 119% at the BDD and Pt, respectively. To gain insight into the higher efficiency in microwave activated EC, the mechanism has therefore been systematically evaluated from the essence of electrochemical reaction and the accumulated hydroxyl radical concentration. 2,4-Dichlorophenol, catechol, benquinone, and maleic and oxalic acids are the main intermediates on the Pt anode measured by high performance liquid chromatography (HPLC), while the intermediates on the BDD electrode include 2,4-dichlorophenol, hydroquinone, and maleic and oxalic acids. The reaction pathway with microwave radiation is the same as that in a conventional electrochemical oxidation on both electrodes. While less and lower aromatic intermediates produce at the BDD with MW, which suggests the higher ring-open ratio and the faster oxidation of carboxylic acids. With microwave radiation, the ring-open ratio at the BDD is increased to 98.8% from 85.6%; the value at Pt is increased to 67.3% from 35.9%. So microwave radiation can activate the electrochemical oxidation, which leads to the higher efficiency. This promotion is mainly due to the higher accumulated hydroxyl radical concentration and the effects by microwave radiation. All the results prove that the BDD electrode presents much better mineralization performance with MW. To the best of our knowledge, it is the first

  11. Effect of the Pd/MWCNTs anode catalysts preparation methods on their morphology and activity in a direct formic acid fuel cell

    NASA Astrophysics Data System (ADS)

    Lesiak, B.; Mazurkiewicz, M.; Malolepszy, A.; Stobinski, L.; Mierzwa, B.; Mikolajczuk-Zychora, A.; Juchniewicz, K.; Borodzinski, A.; Zemek, J.; Jiricek, P.

    2016-11-01

    Impact of Pd/MWCNTs catalysts preparation method on the catalysts morphology and activity in a formic acid electrooxidation reaction was investigated. Three reduction methods of Pd precursor involving reduction in a high pressure microwave reactor (Pd1), reduction with NaBH4 (Pd2) and microwave-assisted polyol method (Pd3) were used in this paper. Crystallites size and morphology were studied using the scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), whereas elemental composition, Pd chemical state and functional groups content by the X-ray photoelectron spectroscopy (XPS). The prepared catalysts were tested in a direct formic acid fuel cell (DFAFC) as an anode material. The catalytic activity was correlated with a mean fraction of the total Pd atoms exposed at the surface (FE). The value of FE was calculated from the crystallites size distribution determined by the STEM measurements. Non-linear dependence of a current density versus FE, approaching the maximum at FE≈0.25 suggests that the catalytic process proceeded at Pd nanocrystallites faces, with inactive edges and corners. Pd2 catalyst exhibited highest activity due to its smallest Pd crystallites (3.2 nm), however the absence of Pd crystallites aggregation and low content of carbon in PdCx phase, i.e. x = 4 at.% may also affect the observed.

  12. The caa3 terminal oxidase of Bacillus stearothermophilus. Transient spectroscopy of electron transfer and ligand binding.

    PubMed

    Giuffrè, A; D'Itri, E; Giannini, S; Brunori, M; Ubbink-Kok, T; Konings, W N; Antonini, G

    1996-06-14

    The thermophilic bacterium Bacillus stearothermophilus possesses a caa3-type terminal oxidase, which was previously purified (De Vrij, W., Heyne, R. I. R., and Konings, W. N. (1989) Eur. J. Biochem. 178, 763-770). We have carried out extensive kinetic experiments on the purified enzyme by stopped-flow time-resolved optical spectroscopy combined with singular value decomposition analysis. The results indicate a striking similarity of behavior between this enzyme and the electrostatic complex between mammalian cytochrome c and cytochrome c oxidase. CO binding to fully reduced caa3 occurs with a second order rate constant (k = 7.8 x 10(4)M-1 s-1) and an activation energy (E* = 6.1 kcal mol-1) similar to those reported for beef heart cytochrome c oxidase. Dithionite reduces cytochrome a with bimolecular kinetics, while cytochrome a3 (and CuB) is reduced via intramolecular electron transfer. When the fully reduced enzyme is mixed with O2, cytochrome a3, and cytochrome c are rapidly oxidized, whereas cytochrome a remains largely reduced in the first few milliseconds. When cyanide-bound caa3 is mixed with ascorbate plus TMPD, cytochrome c and cytochrome a are synchronously reduced; the value of the second order rate constant (k = 3 x 10(5) M-1 s-1 at 30 degrees C) suggests that cytochrome c is the electron entry site. Steady-state experiments indicate that cytochrome a has a redox potential higher than cytochrome c. The data from the reaction with O2 reveal a remarkable similarity in the kinetic, equilibrium, and optical properties of caa3 and the electrostatic complex cytochrome c/cytochrome c oxidase. PMID:8662862

  13. Electron transfer kinetics of caa3 oxidase from Bacillus stearothermophilus: a hypothesis for thermophilicity.

    PubMed Central

    Giuffrè, A; Watmough, N J; Giannini, S; Brunori, M; Konings, W N; Greenwood, C

    1999-01-01

    The O2 reaction and the reverse electron transfer of the thermophilic caa3 terminal oxidase of Bacillus stearothermophilus have been studied by laser flash-photolysis. The results show that both reactions, although studied at a temperature of 20 degreesC, far from the optimal temperature of > 60 degreesC for caa3, follow a kinetic behavior essentially identical to that observed with the electrostatic complex between mammalian cyt c and cyt c oxidase. In the O2 reaction cyt a and cyt a3 are very quickly oxidized; cyt a is then re-reduced via CuA, whereas cyt c oxidation is apparently rate-limited by the oxidation of CuA. Upon photodissociation of the mixed valence-CO caa3, reverse electron transfer from the binuclear center to cyt a3+ (tau1 = 3 micros) and CuA2+ (tau2 = 64 micros) is observed, while cyt c is not reduced by any detectable level. These results seem to rule out accounting for enzymatic thermophilicity by altered kinetics of intramolecular electron transfer involving the cyt center in the reduced configuration, which is very fast. On the basis of these results and previous data, we propose that thermophilicity involves an increased activation barrier for the reduction of cyt a3-CuB in the configuration typical of the oxidized site. PMID:9876155

  14. Severe hepatocellular disease in mice lacking one or both CaaX prenyltransferases.

    PubMed

    Yang, Shao H; Chang, Sandy Y; Tu, Yiping; Lawson, Gregory W; Bergo, Martin O; Fong, Loren G; Young, Stephen G

    2012-01-01

    Protein farnesyltransferase (FTase) and protein geranylgeranyltransferase-I (GGTase-I) add 15- or 20-carbon lipids, respectively, to proteins that terminate with a CaaX motif. These posttranslational modifications of proteins with lipids promote protein interactions with membrane surfaces in cells, but the in vivo importance of the CaaX prenyltransferases and the protein lipidation reactions they catalyze remain incompletely defined. One study concluded that a deficiency of FTase was inconsequential in adult mice and led to little or no tissue pathology. To assess the physiologic importance of the CaaX prenyltransferases, we used conditional knockout alleles and an albumin-Cre transgene to produce mice lacking FTase, GGTase-I, or both enzymes in hepatocytes. The hepatocyte-specific FTase knockout mice survived but exhibited hepatocellular disease and elevated transaminases. Mice lacking GGTase-I not only had elevated transaminases but also had dilated bile cannaliculi, hyperbilirubinemia, hepatosplenomegaly, and reduced survival. Of note, GGTase-I-deficient hepatocytes had a rounded shape and markedly reduced numbers of actin stress fibers. Hepatocyte-specific FTase/GGTase-I double-knockout mice closely resembled mice lacking GGTase-I alone, but the disease was slightly more severe. Our studies refute the notion that FTase is dispensable and demonstrate that GGTase-I is crucial for the vitality of hepatocytes.

  15. Severe hepatocellular disease in mice lacking one or both CaaX prenyltransferases[S

    PubMed Central

    Yang, Shao H.; Chang, Sandy Y.; Tu, Yiping; Lawson, Gregory W.; Bergo, Martin O.; Fong, Loren G.; Young, Stephen G.

    2012-01-01

    Protein farnesyltransferase (FTase) and protein geranylgeranyltransferase-I (GGTase-I) add 15- or 20-carbon lipids, respectively, to proteins that terminate with a CaaX motif. These posttranslational modifications of proteins with lipids promote protein interactions with membrane surfaces in cells, but the in vivo importance of the CaaX prenyltransferases and the protein lipidation reactions they catalyze remain incompletely defined. One study concluded that a deficiency of FTase was inconsequential in adult mice and led to little or no tissue pathology. To assess the physiologic importance of the CaaX prenyltransferases, we used conditional knockout alleles and an albumin–Cre transgene to produce mice lacking FTase, GGTase-I, or both enzymes in hepatocytes. The hepatocyte-specific FTase knockout mice survived but exhibited hepatocellular disease and elevated transaminases. Mice lacking GGTase-I not only had elevated transaminases but also had dilated bile cannaliculi, hyperbilirubinemia, hepatosplenomegaly, and reduced survival. Of note, GGTase-I–deficient hepatocytes had a rounded shape and markedly reduced numbers of actin stress fibers. Hepatocyte-specific FTase/GGTase-I double-knockout mice closely resembled mice lacking GGTase-I alone, but the disease was slightly more severe. Our studies refute the notion that FTase is dispensable and demonstrate that GGTase-I is crucial for the vitality of hepatocytes. PMID:22039581

  16. 2 CFR 1532.1200 - How will I know if I am disqualified under the CAA or CWA?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... disqualifies you. As a practical matter, you may learn about your disqualification from your defense counsel, a... disqualified under the CAA or CWA? There may be several ways that you learn about your disqualification....

  17. 40 CFR 51.1103 - Application of classification and attainment date provisions in CAA section 181 of subpart 2 to...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... attainment date provisions in CAA section 181 of subpart 2 to areas subject to § 51.1102(a). 51.1103 Section... attainment date provisions in CAA section 181 of subpart 2 to areas subject to § 51.1102(a). (a) In... Ozone NAAQS (0.075 ppm) for Areas Subject to Section 51.1102(a) Area class 8-hour design value(ppm...

  18. 40 CFR 51.1103 - Application of classification and attainment date provisions in CAA section 181 of subpart 2 to...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... attainment date provisions in CAA section 181 of subpart 2 to areas subject to § 51.1102(a). 51.1103 Section... attainment date provisions in CAA section 181 of subpart 2 to areas subject to § 51.1102(a). (a) In... Ozone NAAQS (0.075 ppm) for Areas Subject to Section 51.1102(a) Area class 8-hour design value(ppm...

  19. 40 CFR 51.1103 - Application of classification and attainment date provisions in CAA section 181 of subpart 2 to...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... attainment date provisions in CAA section 181 of subpart 2 to areas subject to § 51.1102(a). 51.1103 Section... attainment date provisions in CAA section 181 of subpart 2 to areas subject to § 51.1102(a). (a) In... Ozone NAAQS (0.075 ppm) for Areas Subject to Section 51.1102(a) Area class 8-hour design value(ppm...

  20. Porous carbon-coated silica macroparticles as anode materials for lithium ion batteries: Effect of boric acid

    NASA Astrophysics Data System (ADS)

    Kim, Young-Kuk; Moon, Jong-Woo; Lee, Jung-Goo; Baek, Youn-Kyung; Hong, Seong-Hyun

    2014-12-01

    We report carbon-coated porous silica macroparticles (SiO2@C) prepared using polymeric templates and subsequent carbonization with sucrose for improved electrochemical energy storage in lithium-ion batteries (LIBs). In addition, boron is introduced to improve the stability of electrochemical cells by pyrolyzing mixtures of sucrose and boric acid (SiO2@C + B) under inert atmosphere. The initially large surface area of porous SiO2 (SBET ∼ 658 m2 g-1) is reduced to 102 m2 g-1 after carbonization and introduction of boric acid. Surface of both SiO2@C and SiO2@C + B are covered with amorphous carbon. In particular, SiO2@C + B particles containing borosilicate (Si-O-B) phase and B-O bondings and Si-C-O bondings are also detected from the X-ray photoelectron spectra. The SiO2@C + B macroparticles shows high reversible charge capacity up to 503 mAh g-1 after 103 cycles of Li intercalation/de-intercalation although initial capacity was 200 mAh g-1. The improved charge capacity of SiO2@C + B is attributed to formation of advantageous microstructures induced from boric acid.

  1. Variable anodic thermal control coating

    NASA Technical Reports Server (NTRS)

    Gilliland, C. S.; Duckett, J. (Inventor)

    1983-01-01

    A process for providing a thermal control solar stable surface coating for aluminum surfaces adapted to be exposed to solar radiation wherein selected values within the range of 0.10 to 0.72 thermal emittance (epsilon sub tau) and 0.2 to 0.4 solar absorptance (alpha subs) are reproducibly obtained by anodizing the surface area in a chromic acid solution for a selected period of time. The rate voltage and time, along with the parameters of initial epsilon sub tau and alpha subs, temperature of the chromic acid solution, acid concentration of the solution and the material anodized determines the final values of epsilon/tau sub and alpha sub S. 9 Claims, 5 Drawing Figures.

  2. Electrochemical oxidation of reverse osmosis concentrate on boron-doped diamond anodes at circumneutral and acidic pH.

    PubMed

    Bagastyo, Arseto Y; Batstone, Damien J; Kristiana, Ina; Gernjak, Wolfgang; Joll, Cynthia; Radjenovic, Jelena

    2012-11-15

    Electrochemical processes have been widely investigated for degrading organic contaminants present in wastewater. This study evaluated the performance of electrochemical oxidation using boron-doped diamond (BDD) electrodes by forming OH() for the treatment of reverse osmosis concentrate (ROC) from secondary-treated wastewater effluents. Since oxidation by OH() and active chlorine species (HClO/ClO(-)) is influenced by pH, the electrochemical oxidation of ROC was evaluated at controlled pH 6-7 and at pH 1-2 (no pH adjustment). A high concentration of chloride ions in the ROC enhanced the oxidation, and 7-11% of Coulombic efficiency for chemical oxygen demand (COD) removal was achieved with 5.2 Ah L(-1) of specific electrical charge. Complete COD removal was observed after 5.2 and 6.6 Ah L(-1), yet the corresponding dissolved organic carbon (DOC) removal was only 48% (at acidic pH) and 59% (at circumneutral pH). Although a higher operating pH seemed to enhance the participation of OH() in oxidation mechanisms, high concentrations of chloride resulted in the formation of significant concentrations of adsorbable organic chlorine (AOCl) after electrochemical oxidation at both pH. While adsorbable organic bromine (AOBr) was degraded at a higher applied electrical charge, a continuous increase in AOCl concentration (up to 0.88 mM) was observed until the end of the experiments (i.e. 10.9 Ah L(-1)). In addition, total trihalomethanes (tTHMs) and total haloacetic acids (tHAAs) were further degraded with an increase in electrical charge under both pH conditions, to final total concentrations of 1 and 4 μM (tTHMs), and 12 and 22 μM (tHAAs), at acidic and circumneutral pH, respectively. In particular, tHAAs were still an order of magnitude above their initial concentration in ROC after further electrooxidation. Where high chloride concentrations are present, it was found to be necessary to separate chloride from ROC prior to electrochemical oxidation in order to

  3. Electrochemical oxidation of reverse osmosis concentrate on boron-doped diamond anodes at circumneutral and acidic pH.

    PubMed

    Bagastyo, Arseto Y; Batstone, Damien J; Kristiana, Ina; Gernjak, Wolfgang; Joll, Cynthia; Radjenovic, Jelena

    2012-11-15

    Electrochemical processes have been widely investigated for degrading organic contaminants present in wastewater. This study evaluated the performance of electrochemical oxidation using boron-doped diamond (BDD) electrodes by forming OH() for the treatment of reverse osmosis concentrate (ROC) from secondary-treated wastewater effluents. Since oxidation by OH() and active chlorine species (HClO/ClO(-)) is influenced by pH, the electrochemical oxidation of ROC was evaluated at controlled pH 6-7 and at pH 1-2 (no pH adjustment). A high concentration of chloride ions in the ROC enhanced the oxidation, and 7-11% of Coulombic efficiency for chemical oxygen demand (COD) removal was achieved with 5.2 Ah L(-1) of specific electrical charge. Complete COD removal was observed after 5.2 and 6.6 Ah L(-1), yet the corresponding dissolved organic carbon (DOC) removal was only 48% (at acidic pH) and 59% (at circumneutral pH). Although a higher operating pH seemed to enhance the participation of OH() in oxidation mechanisms, high concentrations of chloride resulted in the formation of significant concentrations of adsorbable organic chlorine (AOCl) after electrochemical oxidation at both pH. While adsorbable organic bromine (AOBr) was degraded at a higher applied electrical charge, a continuous increase in AOCl concentration (up to 0.88 mM) was observed until the end of the experiments (i.e. 10.9 Ah L(-1)). In addition, total trihalomethanes (tTHMs) and total haloacetic acids (tHAAs) were further degraded with an increase in electrical charge under both pH conditions, to final total concentrations of 1 and 4 μM (tTHMs), and 12 and 22 μM (tHAAs), at acidic and circumneutral pH, respectively. In particular, tHAAs were still an order of magnitude above their initial concentration in ROC after further electrooxidation. Where high chloride concentrations are present, it was found to be necessary to separate chloride from ROC prior to electrochemical oxidation in order to

  4. Morphological features of electrodeposited Pt nanoparticles and its application as anode catalysts in polymer electrolyte formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Jeon, Hongrae; Joo, Jiyong; Kwon, Youngkook; Uhm, Sunghyun; Lee, Jaeyoung

    Electrodeposited Pt nanoparticles on carbon substrate show various morphologies depending on the applied potentials. Dendritic, pyramidal, cauliflower-like, and hemi-spherical morphologies of Pt are formed at potential ranges between -0.2 and 0.3 V (vs. Ag/AgCl) and its particle sizes are distributed from 8 to 26 nm. Dendritic bulky particles over 20 nm are formed at an applied potential of -0.2 V, while low deposition potential of 0.2 V causes dense hemi-spherical structure of Pt less than 10 nm. The influence of different Pt shapes on an electrocatalytic oxidation of formic acid is represented. Consequently, homogeneous distribution of Pt nanoparticles with average particle of ca. 14 nm on carbon paper results in a high surface to volume ratio and the better power performance in a fuel cell application.

  5. Mammalian Cell Cytotoxicity and Genotoxicity of the Haloacetic Acids, A Major Class of Drinking Water Disinfection By-Products

    EPA Science Inventory

    The haloacetic acids (HAAs) are disinfection by-products (DBPs) that are formed during the disinfection of drinking water, wastewaters and recreational pool waters. Currently, five HAAs [bromoacetic acid (BAA), dibromoacetic acid (DBAA), chloroacetic acid (CAA), dichloroacetic ac...

  6. FLUORINE CELL ANODE ASSEMBLY

    DOEpatents

    Cable, R.E.; Goode, W.B. Jr.; Henderson, W.K.; Montillon, G.H.

    1962-06-26

    An improved anode assembly is deslgned for use in electrolytlc cells ln the productlon of hydrogen and fluorlne from a moIten electrolyte. The anode assembly comprises a copper post, a copper hanger supported by the post, a plurality of carbon anode members, and bolt means for clamplng half of the anode members to one slde of the hanger and for clamplng the other half of the anode members to the other slde of the hanger. The heads of the clamplng bolts are recessed withln the anode members and carbon plugs are inserted ln the recesses above the bolt heads to protect the boIts agalnst corroslon. A copper washer is provided under the head of each clamplng boIt such that the anode members can be tightly clamped to the hanger with a resultant low anode jolnt resistance. (AEC)

  7. Comparative effects of oral aromatic and branched-chain amino acids on urine calcium and excretion

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aromatic amino acids (AAAs) bind to the calcium sensor receptor (CaR) but branched-chain amino acids (B-CAAs) do not; by binding to this receptor, AAAs have an increased potential to affect calcium homeostasis. This study was conducted to determine and compare the effects of AAAs and B-CAAs on calci...

  8. Least-Squares Spectral Element Solutions to the CAA Workshop Benchmark Problems

    NASA Technical Reports Server (NTRS)

    Lin, Wen H.; Chan, Daniel C.

    1997-01-01

    This paper presents computed results for some of the CAA benchmark problems via the acoustic solver developed at Rocketdyne CFD Technology Center under the corporate agreement between Boeing North American, Inc. and NASA for the Aerospace Industry Technology Program. The calculations are considered as benchmark testing of the functionality, accuracy, and performance of the solver. Results of these computations demonstrate that the solver is capable of solving the propagation of aeroacoustic signals. Testing of sound generation and on more realistic problems is now pursued for the industrial applications of this solver. Numerical calculations were performed for the second problem of Category 1 of the current workshop problems for an acoustic pulse scattered from a rigid circular cylinder, and for two of the first CAA workshop problems, i. e., the first problem of Category 1 for the propagation of a linear wave and the first problem of Category 4 for an acoustic pulse reflected from a rigid wall in a uniform flow of Mach 0.5. The aim for including the last two problems in this workshop is to test the effectiveness of some boundary conditions set up in the solver. Numerical results of the last two benchmark problems have been compared with their corresponding exact solutions and the comparisons are excellent. This demonstrates the high fidelity of the solver in handling wave propagation problems. This feature lends the method quite attractive in developing a computational acoustic solver for calculating the aero/hydrodynamic noise in a violent flow environment.

  9. Antioxidant activity of puha (Sonchus oleraceus L.) as assessed by the cellular antioxidant activity (CAA) assay.

    PubMed

    McDowell, Arlene; Thompson, Scott; Stark, Mirjam; Ou, Zong-Quan; Gould, Kevin S

    2011-12-01

    There is considerable interest in antioxidant dietary components that can be protective against degenerative diseases in humans. Puha (Sonchus oleraceus L.) is a rich source of polyphenols, and exhibits strong antioxidant activity as measured by the 2,2-diphenylpicrylhydrazyl (DPPH) assay. However, the potential of puha to protect against degenerative diseases requires that low molecular weight antioxidants (LMWA) are absorbed by, and active in, human cells. The cellular antioxidant activity (CAA) assay was used to investigate the antioxidant activity of puha leaf extracts. Preparation methods of freezing and freeze-drying reduced the total polyphenolic content compared with fresh puha, but did not affect the LMWA potential as determined by the DPPH assay. The IC(50) values were 0.012 ± 0.003 mg/mL and 0.010 ± 0.005 mg/mL for freeze-dried and fresh puha leaves, respectively. Using the CAA assay, it was shown that LMWAs from foliar extracts of puha were effectively absorbed into HepG2 cells, and exerted antioxidant activity at levels comparable to those of extracts from blueberry fruits, the much-touted antioxidant superfood. Methylene blue staining of HepG2 cells indicated that puha extracts were not cytotoxic at concentrations below 100 mg DW/mL. The data indicate the potential of puha as a nutraceutical supplement for human health.

  10. Structural Engineering of Nanoporous Anodic Alumina Photonic Crystals by Sawtooth-like Pulse Anodization.

    PubMed

    Law, Cheryl Suwen; Santos, Abel; Nemati, Mahdieh; Losic, Dusan

    2016-06-01

    This study presents a sawtooth-like pulse anodization approach aiming to create a new type of photonic crystal structure based on nanoporous anodic alumina. This nanofabrication approach enables the engineering of the effective medium of nanoporous anodic alumina in a sawtooth-like manner with precision. The manipulation of various anodization parameters such as anodization period, anodization amplitude, number of anodization pulses, ramp ratio and pore widening time allows a precise control and fine-tuning of the optical properties (i.e., characteristic transmission peaks and interferometric colors) exhibited by nanoporous anodic alumina photonic crystals (NAA-PCs). The effect of these anodization parameters on the photonic properties of NAA-PCs is systematically evaluated for the establishment of a fabrication methodology toward NAA-PCs with tunable optical properties. The effective medium of the resulting NAA-PCs is demonstrated to be optimal for the development of optical sensing platforms in combination with reflectometric interference spectroscopy (RIfS). This application is demonstrated by monitoring in real-time the formation of monolayers of thiol molecules (11-mercaptoundecanoic acid) on the surface of gold-coated NAA-PCs. The obtained results reveal that the adsorption mechanism between thiol molecules and gold-coated NAA-PCs follows a Langmuir isotherm model, indicating a monolayer sorption mechanism.

  11. 40 CFR 51.903 - How do the classification and attainment date provisions in section 181 of subpart 2 of the CAA...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... attainment date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? 51... date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? (a) In accordance with section 181(a)(1) of the CAA, each area subject to § 51.902(a) shall be classified...

  12. 40 CFR 51.903 - How do the classification and attainment date provisions in section 181 of subpart 2 of the CAA...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... attainment date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? 51... date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? (a) In accordance with section 181(a)(1) of the CAA, each area subject to § 51.902(a) shall be classified...

  13. 40 CFR 51.903 - How do the classification and attainment date provisions in section 181 of subpart 2 of the CAA...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... attainment date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? 51... date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? (a) In accordance with section 181(a)(1) of the CAA, each area subject to § 51.902(a) shall be classified...

  14. 40 CFR 51.903 - How do the classification and attainment date provisions in section 181 of subpart 2 of the CAA...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... attainment date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? 51... date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? (a) In accordance with section 181(a)(1) of the CAA, each area subject to § 51.902(a) shall be classified...

  15. 40 CFR 51.903 - How do the classification and attainment date provisions in section 181 of subpart 2 of the CAA...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... attainment date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? 51... date provisions in section 181 of subpart 2 of the CAA apply to areas subject to § 51.902(a)? (a) In accordance with section 181(a)(1) of the CAA, each area subject to § 51.902(a) shall be classified...

  16. Anodized Ti3SiC2 As an Anode Material for Li-ion Microbatteries.

    PubMed

    Tesfaye, Alexander T; Mashtalir, Olha; Naguib, Michael; Barsoum, Michel W; Gogotsi, Yury; Djenizian, Thierry

    2016-07-01

    We report on the synthesis of an anode material for Li-ion batteries by anodization of a common MAX phase, Ti3SiC2, in an aqueous electrolyte containing hydrofluoric acid (HF). The anodization led to the formation of a porous film containing anatase, a small quantity of free carbon, and silica. By varying the anodization parameters, various oxide morphologies were produced. The highest areal capacity was achieved by anodization at 60 V in an aqueous electrolyte containing 0.1 v/v HF for 3 h at room temperature. After 140 cycles performed at multiple applied current densities, an areal capacity of 380 μAh·cm(-2) (200 μA·cm(-2)) has been obtained, making this new material, free of additives and binders, a promising candidate as a negative electrode for Li-ion microbatteries. PMID:27282275

  17. CAA amendments` Title III could mean `future shock` to U.S. industry competitiveness

    SciTech Connect

    Rocco, V.A.

    1995-06-01

    While the regulated community awaits congressional action that could alter the government`s role in environmental protection and enforcement, the stipulations of existing regulations continue to unfold. Attention is focused on upcoming permitting deadlines imposed by the Clean Air Act Amendments of 1990, due by November for most facilities, and on products and strategies for air pollution control. Unless Congress adopts the unlikely strategy of rolling back all environmental regulations, the obligations on industry imposed by the CAA Amendments will continue to set forth a formidable compliance task. The Amendments ``created a complex maze of new and dramatically altered regulatory programs that will influence how US industry must operate well into the next century.`` This article provides an overview and guidelines for complying with the new rules.

  18. Crystallographic analysis of CaaX prenyltransferases complexed with substrates defines rules of protein substrate selectivity.

    PubMed

    Reid, T Scott; Terry, Kimberly L; Casey, Patrick J; Beese, Lorena S

    2004-10-15

    Post-translational modifications are essential for the proper function of many proteins in the cell. The attachment of an isoprenoid lipid (a process termed prenylation) by protein farnesyltransferase (FTase) or geranylgeranyltransferase type I (GGTase-I) is essential for the function of many signal transduction proteins involved in growth, differentiation, and oncogenesis. FTase and GGTase-I (also called the CaaX prenyltransferases) recognize protein substrates with a C-terminal tetrapeptide recognition motif called the Ca1a2X box. These enzymes possess distinct but overlapping protein substrate specificity that is determined primarily by the sequence identity of the Ca1a2X motif. To determine how the identity of the Ca1a2X motif residues and sequence upstream of this motif affect substrate binding, we have solved crystal structures of FTase and GGTase-I complexed with a total of eight cognate and cross-reactive substrate peptides, including those derived from the C termini of the oncoproteins K-Ras4B, H-Ras and TC21. These structures suggest that all peptide substrates adopt a common binding mode in the FTase and GGTase-I active site. Unexpectedly, while the X residue of the Ca1a2X motif binds in the same location for all GGTase-I substrates, the X residue of FTase substrates can bind in one of two different sites. Together, these structures outline a series of rules that govern substrate peptide selectivity; these rules were utilized to classify known protein substrates of CaaX prenyltransferases and to generate a list of hypothetical substrates within the human genome.

  19. Ring laser gyroscope anode

    SciTech Connect

    Ljung, B.H.

    1981-03-17

    An anode for a ring laser gyroscope which provides improved current stability in the glow discharge path is disclosed. The anode of this invention permits operation at lower currents thereby allowing a reduction of heat dissipation in the ring laser gyroscope. The anode of one embodiment of this invention is characterized by a thumbtack appearance with a spherical end where the normal sharp end of the thumbtack would be located. The stem of the anode extends from the outside of the gyroscope structure to the interior of the structure such that the spherical end is substantially adjacent to the laser beam.

  20. Carbonate fuel cell anodes

    DOEpatents

    Donado, R.A.; Hrdina, K.E.; Remick, R.J.

    1993-04-27

    A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel/iron, cobalt/iron, nickel/iron/aluminum, cobalt/iron/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about 5 weight percent of the anode. A process is described for production of the lithium ferrite containing anode by slipcasting.

  1. Carbonate fuel cell anodes

    DOEpatents

    Donado, Rafael A.; Hrdina, Kenneth E.; Remick, Robert J.

    1993-01-01

    A molten alkali metal carbonates fuel cell porous anode of lithium ferrite and a metal or metal alloy of nickel, cobalt, nickel/iron, cobalt/iron, nickel/iron/aluminum, cobalt/iron/aluminum and mixtures thereof wherein the total iron content including ferrite and iron of the composite is about 25 to about 80 percent, based upon the total anode, provided aluminum when present is less than about 5 weight percent of the anode. A process for production of the lithium ferrite containing anode by slipcasting.

  2. Rocky Flats CAAS System Recalibrated, Retested, and Analyzed to Install in the Criticality Experiments Facility at the Nevada Test Site

    SciTech Connect

    Kim, S; Heinrichs, D; Biswas, D; Huang, S; Dulik, G; Scorby, J; Boussoufi, M; Liu, B; Wilson, R

    2009-05-27

    Neutron detectors and control panels transferred from the Rocky Flats Plant (RFP) were recalibrated and retested for redeployment to the CEF. Testing and calibration were successful with no failure to any equipment. Detector sensitivity was tested at a TRIGA reactor, and the response to thermal neutron flux was satisfactory. MCNP calculated minimum fission yield ({approx} 2 x 10{sup 15} fissions) was applied to determine the thermal flux at selected detector positions at the CEF. Thermal flux levels were greater than 6.39 x 10{sup 6} (n/cm{sup 2}-sec), which was about four orders of magnitude greater than the minimum alarm flux. Calculations of detector survivable distances indicate that, to be out of lethal area, a detector needs to be placed greater than 15 ft away from a maximum credible source. MCNP calculated flux/dose results were independently verified by COG. CAAS calibration and the testing confirmed that the RFP CAAS system is performing its functions as expected. New criteria for the CAAS detector placement and 12-rad zone boundaries at the CEF are established. All of the CAAS related documents and hardware have been transferred from LLNL to NSTec for installation at the CEF high bay areas.

  3. 40 CFR 51.902 - Which classification and nonattainment area planning provisions of the CAA shall apply to areas...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... area planning provisions of the CAA shall apply to areas designated nonattainment for the 1997 8-hour NAAQS? 51.902 Section 51.902 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Implementation of 8-hour Ozone National Ambient Air Quality Standard § 51.902 Which classification...

  4. 2 CFR 1532.1110 - How will a CAA or CWA conviction affect my eligibility to participate in Federal contracts...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the Clean Air Act and Clean Water Act § 1532.1110 How will a CAA or CWA conviction affect my... debarment and suspension system (i.e. covered transactions under subpart A through I of 2 CFR part 180, or prohibited awards under 48 CFR part 9, subpart 9.4), if you: (a) Will perform any part of the transaction...

  5. 2 CFR 1532.1110 - How will a CAA or CWA conviction affect my eligibility to participate in Federal contracts...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... the Clean Air Act and Clean Water Act § 1532.1110 How will a CAA or CWA conviction affect my... debarment and suspension system (i.e. covered transactions under subpart A through I of 2 CFR part 180, or prohibited awards under 48 CFR part 9, subpart 9.4), if you: (a) Will perform any part of the transaction...

  6. 2 CFR 1532.1110 - How will a CAA or CWA conviction affect my eligibility to participate in Federal contracts...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... the Clean Air Act and Clean Water Act § 1532.1110 How will a CAA or CWA conviction affect my... debarment and suspension system (i.e. covered transactions under subpart A through I of 2 CFR part 180, or prohibited awards under 48 CFR part 9, subpart 9.4), if you: (a) Will perform any part of the transaction...

  7. 2 CFR 1532.1130 - How does disqualification under the CAA or CWA differ from a Federal discretionary suspension or...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Clean Air Act and Clean Water Act § 1532.1130 How does disqualification under the CAA or CWA differ from... 2 CFR part 180 or under 48 CFR part 9, subpart 9.4, are exclusions imposed at the discretion of... I of 2 CFR part 180, or under 48 CFR part 9, subpart 9.4....

  8. 2 CFR 1532.1130 - How does disqualification under the CAA or CWA differ from a Federal discretionary suspension or...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Clean Air Act and Clean Water Act § 1532.1130 How does disqualification under the CAA or CWA differ from... 2 CFR part 180 or under 48 CFR part 9, subpart 9.4, are exclusions imposed at the discretion of... I of 2 CFR part 180, or under 48 CFR part 9, subpart 9.4....

  9. 2 CFR 1532.1110 - How will a CAA or CWA conviction affect my eligibility to participate in Federal contracts...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... the Clean Air Act and Clean Water Act § 1532.1110 How will a CAA or CWA conviction affect my... debarment and suspension system (i.e. covered transactions under subpart A through I of 2 CFR part 180, or prohibited awards under 48 CFR part 9, subpart 9.4), if you: (a) Will perform any part of the transaction...

  10. 2 CFR 1532.1130 - How does disqualification under the CAA or CWA differ from a Federal discretionary suspension or...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Clean Air Act and Clean Water Act § 1532.1130 How does disqualification under the CAA or CWA differ from... 2 CFR part 180 or under 48 CFR part 9, subpart 9.4, are exclusions imposed at the discretion of... I of 2 CFR part 180, or under 48 CFR part 9, subpart 9.4....

  11. 2 CFR 1532.1130 - How does disqualification under the CAA or CWA differ from a Federal discretionary suspension or...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Clean Air Act and Clean Water Act § 1532.1130 How does disqualification under the CAA or CWA differ from... 2 CFR part 180 or under 48 CFR part 9, subpart 9.4, are exclusions imposed at the discretion of... I of 2 CFR part 180, or under 48 CFR part 9, subpart 9.4....

  12. 40 CFR 51.902 - Which classification and nonattainment area planning provisions of the CAA shall apply to areas...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... area planning provisions of the CAA shall apply to areas designated nonattainment for the 1997 8-hour NAAQS? 51.902 Section 51.902 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Implementation of 8-hour Ozone National Ambient Air Quality Standard § 51.902 Which classification...

  13. 40 CFR 51.902 - Which classification and nonattainment area planning provisions of the CAA shall apply to areas...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Implementation of 8-hour Ozone National Ambient Air Quality Standard § 51.902 Which classification and... with a 1-hour ozone design value equal to or greater than 0.121 ppm at the time the Administrator signs...) Covered under subpart 1 (CAA). An area designated nonattainment for the 8-hour ozone NAAQS with a...

  14. 40 CFR 51.902 - Which classification and nonattainment area planning provisions of the CAA shall apply to areas...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Implementation of 8-hour Ozone National Ambient Air Quality Standard § 51.902 Which classification and... with a 1-hour ozone design value equal to or greater than 0.121 ppm at the time the Administrator signs...) Covered under subpart 1 (CAA). An area designated nonattainment for the 8-hour ozone NAAQS with a...

  15. 40 CFR 51.126 - Determination of widespread use of ORVR and waiver of CAA section 182(b)(3) Stage II gasoline...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... and waiver of CAA section 182(b)(3) Stage II gasoline vapor recovery requirements. 51.126 Section 51... FOR PREPARATION, ADOPTION, AND SUBMITTAL OF IMPLEMENTATION PLANS Control Strategy § 51.126 Determination of widespread use of ORVR and waiver of CAA section 182(b)(3) Stage II gasoline vapor...

  16. 40 CFR 51.126 - Determination of widespread use of ORVR and waiver of CAA section 182(b)(3) Stage II gasoline...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 2 2012-07-01 2012-07-01 false Determination of widespread use of ORVR and waiver of CAA section 182(b)(3) Stage II gasoline vapor recovery requirements. 51.126 Section 51... Determination of widespread use of ORVR and waiver of CAA section 182(b)(3) Stage II gasoline vapor...

  17. Recovery of plutonium from electrorefining anode heels at Savannah River

    SciTech Connect

    Gray, J H; Gray, L W; Karraker, D G

    1987-03-01

    In a joint effort, the Savannah River Laboratory (SRL), Savannah River Plant (SRP), and the Rocky Flats Plant (RFP) have developed two processes to recover plutonium from electrorefining anode heel residues. Aqueous dissolution of anode heel metal was demonstrated at SRL on a laboratory scale and on a larger pilot scale using either sulfamic acid or nitric acid-hydrazine-fluoride solutions. This direct anode heel metal dissolution requires the use of a geometrically favorable dissolver. The second process developed involves first diluting the plutonium in the anode heel residues by alloying with aluminum. The alloyed anode heel plutonium can then be dissolved using a nitric acid-fluoride-mercury(II) solution in large non-geometrically favorable equipment where nuclear safety is ensured by concentration control.

  18. Structural insights into electron transfer in caa3-type cytochrome oxidase.

    PubMed

    Lyons, Joseph A; Aragão, David; Slattery, Orla; Pisliakov, Andrei V; Soulimane, Tewfik; Caffrey, Martin

    2012-07-26

    Cytochrome c oxidase is a member of the haem copper oxidase superfamily (HCO). HCOs function as the terminal enzymes in the respiratory chain of mitochondria and aerobic prokaryotes, coupling molecular oxygen reduction to transmembrane proton pumping. Integral to the enzyme's function is the transfer of electrons from cytochrome c to the oxidase via a transient association of the two proteins. Electron entry and exit are proposed to occur from the same site on cytochrome c. Here we report the crystal structure of the caa3-type cytochrome oxidase from Thermus thermophilus, which has a covalently tethered cytochrome c domain. Crystals were grown in a bicontinuous mesophase using a synthetic short-chain monoacylglycerol as the hosting lipid. From the electron density map, at 2.36 Å resolution, a novel integral membrane subunit and a native glycoglycerophospholipid embedded in the complex were identified. Contrary to previous electron transfer mechanisms observed for soluble cytochrome c, the structure reveals the architecture of the electron transfer complex for the fused cupredoxin/cytochrome c domain, which implicates different sites on cytochrome c for electron entry and exit. Support for an alternative to the classical proton gate characteristic of this HCO class is presented.

  19. Electrically conductive anodized aluminum coatings

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  20. Anode insulator for electrolytic cell

    SciTech Connect

    Robinson, D.J.

    1986-10-28

    An improved anode insulator is described for use in an electrowinning cell, including spaced anodes each supported by an anode header bar, each having the improved anode insulators disposed thereon for preventing contact with spaced cathodes that are respectively disposed between adjacent anodes, each improved anode insulator comprising: (a) first and second elongated insulating means disposed along intermediate portions of opposite faces of one of the anodes for preventing any contact between the faces of that anode and adjacent cathodes; (b) upper connecting means disposed around the top and side portions of the anode header bar supporting that anode and conforming to the shape of the header bar; and (c) lower connecting means for joining the lower end portions of the first and second elongated insulating means.

  1. Anodic oxidation of benzoquinone using diamond anode.

    PubMed

    Panizza, Marco

    2014-01-01

    The anodic degradation of 1,4-benzoquinone (BQ), one of the most toxic xenobiotic, was investigated by electrochemical oxidation at boron-doped diamond anode. The electrolyses have been performed in a single-compartment flow cell in galvanostatic conditions. The influence of applied current (0.5-2 A), BQ concentration (1-2 g dm(-3)), temperature (20-45 °C) and flow rate (100-300 dm(3) h(-1)) has been studied. BQ decay kinetic, the evolution of its oxidation intermediates and the mineralization of the aqueous solutions were monitored during the electrolysis by high-performance liquid chromatograph (HPLC) and chemical oxygen demand (COD) measurements. The results obtained show that the use of diamond anode leads to total mineralization of BQ in any experimental conditions due to the production of oxidant hydroxyl radicals electrogenerated from water discharge. The decay kinetics of BQ removal follows a pseudo-first-order reaction, and the rate constant increases with rising current density. The COD removal rate was favoured by increasing of applied current, recirculating flow rate and it is almost unaffected by solution temperature. PMID:24710725

  2. High-absorptance high-emittance anodic coating

    NASA Technical Reports Server (NTRS)

    Le, Huong Giang (Inventor); Chesterfield, John L. (Inventor)

    1999-01-01

    A colored anodic coating for use on surfaces of substrates, e.g. aluminum substrates in which it is desirable to maintain a high solar absorptance (.alpha.) and a high infrared emittance (.epsilon.), particularly in low earth orbit space environments. This anodic coating is preferably a dark colored coating, and even more preferably a black coating. This coating allows a touch temperature within an acceptable design range to preclude burning of an astronaut in case of contact, but also allows a solar radiation absorption in an amount such that an .alpha./.epsilon. ratio of unity is achieved. The coating of the invention comprises a first layer in the form of an acid anodized colored anodic layer for achieving a high solar absorptance and a second or high emittance layer in the form of a clear acid anodized layer for achieving a high emittance. The entire coating is quite thin, e.g. 1-2 mils and is quite stable in a hostile space environment of the type encountered in a low earth orbit. The coating is obtained by first creating the high emittance clear anodized coating on the metal surface followed by anodizing using a colored anodizing process.

  3. High-absorptance high-emittance anodic coating

    NASA Technical Reports Server (NTRS)

    Le, Huong Giang (Inventor); Chesterfield, John L. (Inventor)

    1998-01-01

    A colored anodic coating for use on surfaces of substrates, e.g. aluminum substrates in which it is desirable to maintain a high solar absorptance (a) and a high infrared emittance (e), particularly in low earth orbit space environments. This anodic coating is preferably a dark colored coating, and even more preferably a black coating. This coating allows a touch temperature within an acceptable design range to preclude burning of an astronaut in case of contact, but also allows a solar radiation absorption in an amount such that an a/e ratio of unity is achieved. The coating of the invention comprises a first layer in the form of an acid anodized colored anodic layer for achieving a high solar absorptance and a second or high emittance layer in the form of a clear acid anodized layer for achieving a high emittance. The entire coating is quite thin, e.g. 1-2 mils and is quite stable in a hostile space environment of the type encountered in a low earth orbit. The coating is obtained by first creating the high emittance clear anodized coating on the metal surface followed by anodizing using a colored anodizing process.

  4. Ruminal and Abomasal Starch Hydrolysate Infusions Selectively Decrease the Expression of Cationic Amino Acid Transporter mRNA by Small Intestinal Epithelia of Forage-fed Beef Steers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although cationic amino acids (CAA) are consid-ered essential to maximize optimal growth of cattle, transporters responsible for CAA absorption by bovine small intestinal epithelia have not been described. This study was conducted to test 2 hypotheses: 1) the duo¬denal, jejunal, and ileal epithelia ...

  5. Sulfur tolerant anode materials

    SciTech Connect

    Not Available

    1988-05-01

    The goal of this program is the development of a molten carbonate fuel cell (MCFC) anode which is more tolerant of sulfur contaminants in the fuel than the current state-of-the-art nickel-based anode structures. This program addresses two different but related aspects of the sulfur contamination problem. The primary aspect is concerned with the development of a sulfur tolerant electrocatalyst for the fuel oxidation reaction. A secondary issue is the development of a sulfur tolerant water-gas-shift reaction catalyst and an investigation of potential steam reforming catalysts which also have some sulfur tolerant capabilities. These two aspects are being addressed as two separate tasks.

  6. Sulfur tolerant anode materials

    SciTech Connect

    Not Available

    1988-02-01

    The goal of this program is the development of a molten carbonate fuel cell (MCFC) anode which is more tolerant of sulfur contaminants in the fuel than the current state-of-the-art nickel-based anode structures. This program addresses two different but related aspects of the sulfur contamination problem. The primary aspect is concerned with the development of a sulfur tolerant electrocatalyst for the fuel oxidation reaction. A secondary issue is the development of a sulfur tolerant water-gas-shift reaction catalyst and an investigation of potential steam reforming catalysts which also have some sulfur tolerant capabilities. These two aspects are being addressed as two separate tasks.

  7. Sulfur tolerant anode materials

    SciTech Connect

    Not Available

    1987-02-01

    The goal of this program is the development of a molten carbonate fuel cell (MCFC) anode which is more tolerant of sulfur contaminants in the fuel than the current state-of-the-art nickel-based anode structures. This program addresses two different but related aspects of the sulfur contamination problem. The primary aspect is concerned with the development of a sulfur tolerant electrocatalyst for the fuel oxidation reaction. A secondary issue is the development of a sulfur tolerant water-gas-shift reaction catalyst and an investigation of potential steam reforming catalysts which also have some sulfur tolerant capabilities. These two aspects are being addressed as two separate tasks.

  8. Heat treatment effect on crystal structure and design of highly sensitive room temperature CO2 gas sensors using anodic Bi2O3 nanoporous formed in a citric acid electrolyte

    NASA Astrophysics Data System (ADS)

    Ahila, M.; Dhanalakshmi, J.; Celina Selvakumari, J.; Pathinettam Padiyan, D.

    2016-10-01

    The effect of annealing temperature on the crystal structure of anodic bismuth trioxide (ABO) layers prepared via anodization in a citric acid-based electrolyte was studied. The samples were annealed in air at temperatures ranging from 200 °C to 600 °C. Characterization of nanoporous ABO layers was carried out through x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–visible (UV–Vis) diffuse reflectance spectroscopy and photoluminescence (PL). Effects of heat treatment on crystallinity, morphology and gas-sensing properties were investigated in detail. The XRD measurements showed that a gradual phase change from beta to gamma occurs with an increase in annealing temperature. The beta to gamma transformation occurred between 500 and 600 °C. The changes in the average crystallite sizes of beta and gamma occurring during heat treatment of the ABO layers are correlated with the mechanism of gamma-phase nucleation. During the growth of the gamma phase, the grain size gets enlarged with a reduction in the total area of grain boundary. The pores’ formation and the pore diameter of both anodized and annealed samples were found to be in the range of 50 to 150 nm. The band gap of the ABO layer crystallines was determined using the diffuse reflectance technique according to the Kubelka–Munk theory. Results showed that the band gap of the ABO layer decreased from 4.09 to 2.42 eV when the particle size decreased from 58 to 24 nm. The CO2 sensing properties of the ABO were investigated at room temperature for 0–100 ppm concentration. The variations in the electrical resistances were measured with the exposure of CO2 as a function of time. The maximum value of the response magnitude of 77% was obtained for 100 ppm of CO2. These experimental results show that the ABO layer of nanoporous is a promising material for CO2 sensors at room temperature.

  9. The effect of carboxylic acid anions on the stability of framework mineral grains in petroleum reservoirs

    SciTech Connect

    MacGowan, D.B.; Surdam, R.C.; Ewing, R.E. )

    1990-06-01

    This paper presents experimental and empirical evidence to show that carboxylic acid anions (CAA's) are a major diagenetic control on first-cycle basins in Jurassic-to-Pleistocene reservoirs in the 80-to-120{degrees}C thermal window.

  10. A scanning tunneling microscopy study of the structure of thin oxide films grown on Ni(111) single crystal surfaces by anodic polarization in acid electrolyte

    NASA Astrophysics Data System (ADS)

    Maurice, V.; Talah, H.; Marcus, P.

    1994-03-01

    Scanning tunneling microscopy has been used to study ex situ (in air) the thin oxide films (passive films) grown on Ni(111) by anodic polarization at +550, +650 and +750 mV/SHE in 0.05 M H 2SO 4. Atomic resolution imaging demonstrates the crystalline character of the oxide film and the epitaxy with the substrate. Two levels of roughening with respect to the non-polarized surfaces are observed: on a mesoscopic scale and on the atomic scale. The roughening on the mesoscopic scale increases with higher polarization potentials. The observed roughness is attributed to the result of the competition between metal dissolution and nucleation and growth of the oxide film. The roughening on the atomic scale is independent of the polarization potential. It is evidenced by the formation of a stepped crystalline lattice whose parameters fit those of a (111)-oriented NiO surface. The presence of steps indicates a tilt of (8 ± 5)° of the surface of the film with respect to the (111) orientation. The possible epitaxial relationships resulting from the surface tilt are discussed. Local variations of the film thickness at the step edges are likely to result from the surface tilt and may constitute preferential sites for the local breakdown of passivity.

  11. Anode initiated surface flashover switch

    DOEpatents

    Brainard, John P.; Koss, Robert J.

    2003-04-29

    A high voltage surface flashover switch has a pair of electrodes spaced by an insulator. A high voltage is applied to an anode, which is smaller than the opposing, grounded, cathode. When a controllable source of electrons near the cathode is energized, the electrons are attracted to the anode where they reflect to the insulator and initiate anode to cathode breakdown.

  12. Inert Anode Report

    SciTech Connect

    none,

    1999-07-01

    This ASME report provides a broad assessment of open literature and patents that exist in the area of inert anodes and their related cathode systems and cell designs, technologies that are relevant for the advanced smelting of aluminum. The report also discusses the opportunities, barriers, and issues associated with these technologies from a technical, environmental, and economic viewpoint.

  13. Anodes for alkaline electrolysis

    DOEpatents

    Soloveichik, Grigorii Lev

    2011-02-01

    A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

  14. Anodic Polarization Curves Revisited

    ERIC Educational Resources Information Center

    Liu, Yue; Drew, Michael G. B.; Liu, Ying; Liu, Lin

    2013-01-01

    An experiment published in this "Journal" has been revisited and it is found that the curve pattern of the anodic polarization curve for iron repeats itself successively when the potential scan is repeated. It is surprising that this observation has not been reported previously in the literature because it immediately brings into…

  15. Movable anode x-ray source with enhanced anode cooling

    DOEpatents

    Bird, Charles R.; Rockett, Paul D.

    1987-01-01

    An x-ray source having a cathode and a disc-shaped anode with a peripheral surface at constant radius from the anode axis opposed to the cathode. The anode has stub axle sections rotatably carried in heat conducting bearing plates which are mounted by thermoelectric coolers to bellows which normally bias the bearing plates to a retracted position spaced from opposing anode side faces. The bellows cooperate with the x-ray source mounting structure for forming closed passages for heat transport fluid. Flow of such fluid under pressure expands the bellows and brings the bearing plates into heat conducting contact with the anode side faces. A worm gear is mounted on a shaft and engages serrations in the anode periphery for rotating the anode when flow of coolant is terminated between x-ray emission events.

  16. Movable anode x-ray source with enhanced anode cooling

    DOEpatents

    Bird, C.R.; Rockett, P.D.

    1987-08-04

    An x-ray source is disclosed having a cathode and a disc-shaped anode with a peripheral surface at constant radius from the anode axis opposed to the cathode. The anode has stub axle sections rotatably carried in heat conducting bearing plates which are mounted by thermoelectric coolers to bellows which normally bias the bearing plates to a retracted position spaced from opposing anode side faces. The bellows cooperate with the x-ray source mounting structure for forming closed passages for heat transport fluid. Flow of such fluid under pressure expands the bellows and brings the bearing plates into heat conducting contact with the anode side faces. A worm gear is mounted on a shaft and engages serrations in the anode periphery for rotating the anode when flow of coolant is terminated between x-ray emission events. 5 figs.

  17. Formation of anodic aluminum oxide with serrated nanochannels.

    PubMed

    Li, Dongdong; Zhao, Liang; Jiang, Chuanhai; Lu, Jia G

    2010-08-11

    We report a simple and robust method to self-assemble porous anodic aluminum oxide membranes with serrated nanochannels by anodizing in phosphoric acid solution. Due to high field conduction and anionic incorporation, an increase of anodizing voltage leads to an increase of the impurity levels and also the field strength across barrier layer. On the basis of both experiment and simulation results, the initiation and formation of serrated channels are attributed to the evolution of oxygen gas bubbles followed by plastic deformation in the oxide film. Alternating anodization in oxalic and phosphoric acids is applied to construct multilayered membranes with smooth and serrated channels, demonstrating a unique way to design and construct a three-dimensional hierarchical system with controllable morphology and composition. PMID:20617804

  18. A shunt pathway limits the CaaX processing of Hsp40 Ydj1p and regulates Ydj1p-dependent phenotypes

    PubMed Central

    Hildebrandt, Emily R; Cheng, Michael; Zhao, Peng; Kim, June H; Wells, Lance; Schmidt, Walter K

    2016-01-01

    The modifications occurring to CaaX proteins have largely been established using few reporter molecules (e.g. Ras, yeast a-factor mating pheromone). These proteins undergo three coordinated COOH-terminal events: isoprenylation of the cysteine, proteolytic removal of aaX, and COOH-terminal methylation. Here, we investigated the coupling of these modifications in the context of the yeast Ydj1p chaperone. We provide genetic, biochemical, and biophysical evidence that the Ydj1p CaaX motif is isoprenylated but not cleaved and carboxylmethylated. Moreover, we demonstrate that Ydj1p-dependent thermotolerance and Ydj1p localization are perturbed when alternative CaaX motifs are transplanted onto Ydj1p. The abnormal phenotypes revert to normal when post-isoprenylation events are genetically interrupted. Our findings indicate that proper Ydj1p function requires an isoprenylatable CaaX motif that is resistant to post-isoprenylation events. These results expand on the complexity of protein isoprenylation and highlight the impact of post-isoprenylation events in regulating the function of Ydj1p and perhaps other CaaX proteins. DOI: http://dx.doi.org/10.7554/eLife.15899.001 PMID:27525482

  19. Fabrication of porous anodic alumina using normal anodization and pulse anodization

    NASA Astrophysics Data System (ADS)

    Chin, I. K.; Yam, F. K.; Hassan, Z.

    2015-05-01

    This article reports on the fabrication of porous anodic alumina (PAA) by two-step anodizing the low purity commercial aluminum sheets at room temperature. Different variations of the second-step anodization were conducted: normal anodization (NA) with direct current potential difference; pulse anodization (PA) alternate between potential differences of 10 V and 0 V; hybrid pulse anodization (HPA) alternate between potential differences of 10 V and -2 V. The method influenced the film homogeneity of the PAA and the most homogeneous structure was obtained via PA. The morphological properties are further elucidated using measured current-transient profiles. The absent of current rise profile in PA indicates the anodization temperature and dissolution of the PAA structure were greatly reduced by alternating potential differences.

  20. Nickel anode electrode

    DOEpatents

    Singh, Prabhakar; Benedict, Mark

    1987-01-01

    A nickel anode electrode fabricated by oxidizing a nickel alloying material to produce a material whose exterior contains nickel oxide and whose interior contains nickel metal throughout which is dispersed the oxide of the alloying material and by reducing and sintering the oxidized material to form a product having a nickel metal exterior and an interior containing nickel metal throughout which is dispersed the oxide of the alloying material.

  1. Sensitivity and Specificity of a Urine Circulating Anodic Antigen Test for the Diagnosis of Schistosoma haematobium in Low Endemic Settings

    PubMed Central

    Knopp, Stefanie; Corstjens, Paul L. A. M.; Koukounari, Artemis; Cercamondi, Colin I.; Ame, Shaali M.; Ali, Said M.; de Dood, Claudia J.; Mohammed, Khalfan A.; Utzinger, Jürg; Rollinson, David; van Dam, Govert J.

    2015-01-01

    Background Elimination of schistosomiasis as a public health problem and interruption of transmission in selected areas are key goals of the World Health Organization for 2025. Conventional parasitological methods are insensitive for the detection of light-intensity infections. Techniques with high sensitivity and specificity are required for an accurate diagnosis in low-transmission settings and verification of elimination. We determined the accuracy of a urine-based up-converting phosphor-lateral flow circulating anodic antigen (UCP-LF CAA) assay for Schistosoma haematobium diagnosis in low-prevalence settings in Zanzibar, Tanzania. Methodology A total of 1,740 urine samples were collected in 2013 from children on Pemba Island, from schools where the S. haematobium prevalence was <2%, 2–5%, and 5–10%, based on a single urine filtration. On the day of collection, all samples were tested for microhematuria with reagent strips and for the presence of S. haematobium eggs with microscopy. Eight months later, 1.5 ml of urine from each of 1,200 samples stored at -20°C were analyzed by UCP-LF CAA assay, while urine filtration slides were subjected to quality control (QCUF). In the absence of a true ‘gold’ standard, the diagnostic performance was calculated using latent class analyses (LCA). Principal Findings The ‘empirical’ S. haematobium prevalence revealed by UCP-LF CAA, QCUF, and reagent strips was 14%, 5%, and 4%, respectively. LCA revealed a sensitivity of the UCP-LF CAA, QCUF, and reagent strips of 97% (95% confidence interval (CI): 91–100%), 86% (95% CI: 72–99%), and 67% (95% CI: 52–81%), respectively. Test specificities were consistently above 90%. Conclusions/Significance The UCP-LF CAA assay shows high sensitivity for the diagnosis of S. haematobium in low-endemicity settings. Empirically, it detects a considerably higher number of infections than microscopy. Hence, the UCP-LF CAA employed in combination with QCUF, is a promising tool for

  2. Inert anodes for aluminum smelting

    SciTech Connect

    Weyand, J.D.; Ray, S.P.; Baker, F.W.; DeYoung, D.H.; Tarcy, G.P.

    1986-02-01

    The use of nonconsumable or inert anodes for replacement of consumable carbon anodes in Hall electrolysis cells for the production of aluminum has been a technical and commercial goal of the aluminum industry for many decades. This report summarizes the technical success realized in the development of an inert anode that can be used to produce aluminum of acceptable metal purity in small scale Hall electrolysis cells. The inert anode material developed consists of a cermet composition containing the phases: copper, nickel ferrite and nickel oxide. This anode material has an electrical conductivity comparable to anode carbon used in Hall cells, i.e., 150 ohm {sup {minus}1}cm{sup {minus}1}. Metal purity of 99.5 percent aluminum has been produced using this material. The copper metal alloy present in the anode is not removed by anodic dissolution as does occur with cermet anodes containing a metallic nickel alloy. Solubility of the oxide phases in the cryolite electrolyte is reduced by: (1) saturated concentration of alumina, (2) high nickel oxide content in the NiO-NiFe{sub 2}O{sub 4} composition, (3) lowest possible cell operating temperature, (4) additions of alkaline or alkaline earth fluorides to the bath to reduce solubilities of the anode components, and (5) avoiding bath contaminants such as silica. Dissolution rate measurements indicate first-order kinetics and that the rate limiting step for dissolution is mass transport controlled. 105 refs., 234 figs., 73 tabs.

  3. Pd and PdCo alloy nanoparticles supported on polypropylenimine dendrimer-grafted graphene: A highly efficient anodic catalyst for direct formic acid fuel cells

    NASA Astrophysics Data System (ADS)

    Hosseini, Hadi; Mahyari, Mojtaba; Bagheri, Akbar; Shaabani, Ahmad

    2014-02-01

    For the first time, Pd and PdCo alloy nanoparticles supported on polypropylenimine dendrimer-grafted graphene (Pd and PdCo/PPI-g-G) are prepared and characterized with Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The electrocatalytic activity of Pd and PdCo/PPI-g-G are investigated in terms of formic acid electrooxidation in H2SO4 aqueous solution. The PdCo/PPI-g-G shows much higher formic acid oxidation activities in comparison with Pd/PPI-g-G, and it is more resistant to the surface poisoning. This improved electrocatalytic performance may be due to the fine dispersion of PdCo alloy nanoparticles and bi-functional effect. The kinetic parameters such as charge transfer coefficient and the diffusion coefficient of formic acid are estimated under the quasi steady-state conditions.

  4. Self-doped anthranilic acid-pyrrole copolymer/gold electrodes for selective preconcentration and determination of Cu(I) by differential pulse anodic stripping voltammetry.

    PubMed

    Nateghi, M R; Fallahian, M H

    2007-05-01

    Electropolymerization of anthranilic acid/pyrrole (AA/PY) at solid substrate electrodes (platinum, gold, and glassy carbon) gave stable and water-insoluble films under a wide range of pH. Combining high conductivity of the polypyrrole (PPY) and pH independence of the electrochemical activity of the self-doped carboxylic acid-substituted polyaniline allows us to prepare an improved functionalized PPY-modified electrode to collect and measure Cu(I) species. The differential pulse stripping analysis of the copper ions using a polyanthranilic acid-co-polypyrrole (PAA/PPY)-modified electrode consisted of three steps: accumulation, electrochemical reduction to the elemental copper and stripping step. Factors affecting these steps, including electropolymerization conditions, accumulation and stripping medium, reduction potential, reduction time and accumulation time, were systematically investigated. A detection limit of 5.3 x 10(-9) M Cu(I) was achieved for a 7.0 min accumulation. For 12 determinations of Cu(I) at concentrations of 1.0 x 10(-8) M, an RSD of 3.5% was obtained. The log I(p) was found to vary linearly with log[Cu(I)] in the concentration range from 7.0 x 10(-9) to 1.0 x 10(-5) M.

  5. Optimization of Aluminum Anodization Conditions for the Fabrication of Nanowires by Electrodeposition

    NASA Technical Reports Server (NTRS)

    Fucsko, Viola

    2005-01-01

    Anodized alumina nanotemplates have a variety of potential applications in the development of nanotechnology. Alumina nanotemplates are formed by oxidizing aluminum film in an electrolyte solution.During anodization, aluminum oxidizes, and, under the proper conditions, nanometer-sized pores develop. A series of experiments was conducted to determine the optimal conditions for anodization. Three-micrometer thick aluminum films on silicon and silicon oxide substrates were anodized using constant voltages of 13-25 V. 0.1-0.3M oxalic acid was used as the electrolyte. The anodization time was found to increase and the overshooting current decreased as both the voltage and the electrolyte concentrations were decreased. The samples were observed under a scanning electron microscope. Anodizing with 25V in 0.3M oxalic acid appears to be the best process conditions. The alumina nanotemplates are being used to fabricate nanowires by electrodeposition. The current-voltage characteristics of copper nanowires have also been studied.

  6. Formation of Anodic Aluminum Oxide with Branched and Meshed Pores.

    PubMed

    Kim, Byeol; Lee, Jin Seok

    2016-06-01

    Anodic aluminum oxide (AAO), with a self-ordered hexagonal array, is important for various applications in nanofabrication including as the fabrication of nanotemplates and other nanostructures. With the consideration, there have been many efforts to control the characteristic parameters of porous anodic alumina by adjustment of the anodizing conditions such as the electrolyte, temperature, applied potential, and Al purity. In particular, impurities in Al are changing the morphology of an alumina film; however, the formation mechanism has not yet been explained. In this work, we anodized a high purity (99.999%, Al(high)) and low purity (99.8%, Al(low)) aluminum foil by a two-step anodization process in an oxalic acid solution or phosphoric acid. It was found that the purity of aluminum foil has influenced the morphology of the alumina film resulting in branched and meshed pores. Also, electrochemical analysis indicated that the branched and meshed pores in the low-purity Al foil formed by the presence of impurities. Impurities act as defects and change the general growth mechanism for pore formation by inducing an electric field imbalance during anodization. This work contributes to the research field of topographical chemistry and applied fields including nanofabrication. PMID:27427755

  7. Corrosion Resistance and Color Properties of Anodized Ti-6Al-4V

    NASA Astrophysics Data System (ADS)

    Karambakhsh, Ali; Afshar, Abdollah; Malekinejad, Pejman

    2012-01-01

    In this research, color anodizing of Ti-6Al-4V alloy was performed in phosphoric acid solution of 0.4 M concentration and within 30 s in different voltages (10-120 V) of a DC power supply. The effect of anodizing voltages on the color and thickness of anodized layers on Ti-6Al-4V alloy surface was surveyed. Thickness and refractive index of layers were measured by spectrophotometery and reflectance curves. According to the results, thickness of layers increased with increasing anodizing voltage and was in the range of 38-167 nm. Also the refractive index of anodic film was approximately constant at about 2 and increased inconsiderably with increasing anodizing voltage. Corrosion resistance of the anodized samples in 20 and 50 V was surveyed in physiological solutions of Ringer's solution, Artificial Saliva solution, and Ringer's + 150 mM H2O2 solution at the temperature of 37 °C by potentiodynamic polarization method. The anodized sample in 50 V indicated lower corrosion rate than the non-anodized sample as well as the sample which was anodized in 20 V in all solutions. The non-anodized sample indicated the highest corrosion rate of about 0.25 μA cm-2.

  8. Alternative Anode Reaction for Copper Electrowinning

    SciTech Connect

    Not Available

    2005-07-01

    This report describes a project funded by the Department of Energy, with additional funding from Bechtel National, to develop a copper electrowinning process with lower costs and lower emissions than the current process. This new process also includes more energy efficient production by using catalytic-surfaced anodes and a different electrochemical couple in the electrolyte, providing an alternative oxidation reaction that requires up to 50% less energy than is currently required to electrowin the same quantity of copper. This alternative anode reaction, which oxidizes ferric ions to ferrous, with subsequent reduction back to ferric using sulfur dioxide, was demonstrated to be technically and operationally feasible. However, pure sulfur dioxide was determined to be prohibitively expensive and use of a sulfur burner, producing 12% SO{sub 2}, was deemed a viable alternative. This alternate, sulfur-burning process requires a sulfur burner, waste heat boiler, quench tower, and reaction towers. The electrolyte containing absorbed SO{sub 2} passes through activated carbon to regenerate the ferrous ion. Because this reaction produces sulfuric acid, excess acid removal by ion exchange is necessary and produces a low concentration acid suitable for leaching oxide copper minerals. If sulfide minerals are to be leached or the acid unneeded on site, hydrogen was demonstrated to be a potential reductant. Preliminary economics indicate that the process would only be viable if significant credits could be realized for electrical power produced by the sulfur burner and for acid if used for leaching of oxidized copper minerals on site.

  9. A dynamic inert metal anode.

    SciTech Connect

    Hryn, J. N.

    1998-11-09

    A new concept for a stable anode for aluminum electrowinning is described. The anode consists of a cup-shaped metal alloy container filled with a molten salt that contains dissolved aluminum. The metal alloy can be any of a number of alloys, but it must contain aluminum as a secondary alloying metal. A possible alloy composition is copper with 5 to 15 weight percent aluminum. In the presence of oxygen, aluminum on the metal anode's exterior surface forms a continuous alumina film that is thick enough to protect the anode from chemical attack by cryolite during electrolysis and thin enough to maintain electrical conductivity. However, the alumina film is soluble in cryolite, so it must be regenerated in situ. Film regeneration is achieved by the transport of aluminum metal from the anode's molten salt interior through the metal wall to the anode's exterior surface, where the transported aluminum oxidizes to alumina in the presence of evolving oxygen to maintain the protective alumina film. Periodic addition of aluminum metal to the anode's interior keeps the aluminum activity in the molten salt at the desired level. This concept for an inert anode is viable as long as the amount of aluminum produced at the cathode greatly exceeds the amount of aluminum required to maintain the anode's protective film.

  10. Thin film buried anode battery

    DOEpatents

    Lee, Se-Hee; Tracy, C. Edwin; Liu, Ping

    2009-12-15

    A reverse configuration, lithium thin film battery (300) having a buried lithium anode layer (305) and process for making the same. The present invention is formed from a precursor composite structure (200) made by depositing electrolyte layer (204) onto substrate (201), followed by sequential depositions of cathode layer (203) and current collector (202) on the electrolyte layer. The precursor is subjected to an activation step, wherein a buried lithium anode layer (305) is formed via electroplating a lithium anode layer at the interface of substrate (201) and electrolyte film (204). The electroplating is accomplished by applying a current between anode current collector (201) and cathode current collector (202).

  11. Mechanism of formation of dense anodic films of PbO on lead and lead alloys in sulfuric acid: Use of an {sup 18}O tracer

    SciTech Connect

    Rocca, E.; Steinmetz, J.; Weber, S.

    1999-01-01

    In order to elucidate the growth mechanism of the passive {alpha}-PbO at the interface grid/positive active material of the lead-acid batteries, a sequential electrochemical method using {sup 18}O was set up. It was established that the formation of a thick, dense PbO layer on pure lead and lead alloys (Pb-Sb, Pb-Ca-Sn), in potential conditions simulating deep discharged batteries for electric vehicles, is the consequence of a solid-state process, with O{sup 2{minus}} as the predominant diffusing species. Diffusion of O{sup 2{minus}} anions occurs along the grain boundaries of PbO, as well as in the grain bulk, probably between the two neighboring planes of Pb{sup 2+} cations of the PbO tetragonal structure.

  12. Caffeic acid ameliorates colitis in association with increased Akkermansia population in the gut microbiota of mice

    PubMed Central

    Zhang, Zhan; Wu, Xinyue; Cao, Shuyuan; Wang, Li; Wang, Di; Yang, Hui; Feng, Yiming; Wang, Shoulin; Li, Lei

    2016-01-01

    Emerging evidence shows that dietary agents and phytochemicals contribute to the prevention and treatment of ulcerative colitis (UC). We first reported the effects of dietary caffeic acid (CaA) on murine experimental colitis and on fecal microbiota. Colitis was induced in C57BL/6 mice by administration of 2.5% dextran sulfate sodium (DSS). Mice were fed a control diet or diet with CaA (1 mM). Our results showed that dietary CaA exerted anti-inflammatory effects in DSS colitis mice. Moreover, CaA could significantly suppress the secretion of IL-6, TNFα, and IFNγ and the colonic infiltration of CD3+ T cells, CD177+ neutrophils and F4/80+ macrophages via inhibition of the activation of NF-κB signaling pathway. Analysis of fecal microbiota showed that CaA could restore the reduction of richness and inhibit the increase of the ratio of Firmicute to Bacteroidetes in DSS colitis mice. And CaA could dramatically increase the proportion of the mucin-degrading bacterium Akkermansia in DSS colitis mice. Thus, CaA could ameliorate colonic pathology and inflammation in DSS colitis mice, and it might be associated with a proportional increase in Akkermansia. PMID:27177331

  13. Assessing the potential of amino acid 13C patterns as a carbon source tracer in marine sediments: effects of algal growth conditions and sedimentary diagenesis

    NASA Astrophysics Data System (ADS)

    Larsen, T.; Bach, L. T.; Salvatteci, R.; Wang, Y. V.; Andersen, N.; Ventura, M.; McCarthy, M. D.

    2015-08-01

    Burial of organic carbon in marine sediments has a profound influence in marine biogeochemical cycles and provides a sink for greenhouse gases such as CO2 and CH4. However, tracing organic carbon from primary production sources as well as its transformations in the sediment record remains challenging. Here we examine a novel but growing tool for tracing the biosynthetic origin of amino acid carbon skeletons, based on naturally occurring stable carbon isotope patterns in individual amino acids (δ13CAA). We focus on two important aspects for δ13CAA utility in sedimentary paleoarchives: first, the fidelity of source diagnostic of algal δ13CAA patterns across different oceanographic growth conditions, and second, the ability of δ13CAA patterns to record the degree of subsequent microbial amino acid synthesis after sedimentary burial. Using the marine diatom Thalassiosira weissflogii, we tested under controlled conditions how δ13CAA patterns respond to changing environmental conditions, including light, salinity, temperature, and pH. Our findings show that while differing oceanic growth conditions can change macromolecular cellular composition, δ13CAA isotopic patterns remain largely invariant. These results emphasize that δ13CAA patterns should accurately record biosynthetic sources across widely disparate oceanographic conditions. We also explored how δ13CAA patterns change as a function of age, total nitrogen and organic carbon content after burial, in a marine sediment core from a coastal upwelling area off Peru. Based on the four most informative amino acids for distinguishing between diatom and bacterial sources (i.e., isoleucine, lysine, leucine and tyrosine), bacterially derived amino acids ranged from 10 to 15 % in the sediment layers from the last 5000 years, and up to 35 % during the last glacial period. The greater bacterial contributions in older sediments indicate that bacterial activity and amino acid resynthesis progressed, approximately as a

  14. Mesoporous Silicon-Based Anodes

    NASA Technical Reports Server (NTRS)

    Peramunage, Dharmasena

    2015-01-01

    For high-capacity, high-performance lithium-ion batteries. A new high-capacity anode composite based on mesoporous silicon is being developed. With a structure that resembles a pseudo one-dimensional phase, the active anode material will accommodate significant volume changes expected upon alloying and dealloying with lithium (Li).

  15. A historical overview of the development of manganese (Mn) pharmacokinetic data under Section 211(b) of the Clean Air Act (CAA)

    EPA Science Inventory

    Abstract for Manganese 2016A historical overview of the development of manganese (Mn) pharmacokinetic data under Section 211(b) of the Clean Air Act (CAA)William K BoyesBackground. In the 1990’s, the use of methylcyclopentadienyl manganese tricarbonyl (MMT) as an octane-enh...

  16. Anode film formation and control

    DOEpatents

    Koski, O.; Marschman, S.C.

    1990-05-01

    A protective film is created about the anode within a cryolite-based electrolyte during electrolytic production of aluminum from alumina. The film functions to minimize corrosion of the anode by the cryolitic electrolyte and thereby extend the life of the anode. Various operating parameters of the electrolytic process are controlled to maintain the protective film about the anode in a protective state throughout the electrolytic reduction of alumina. Such parameters include electrolyte temperature, electrolyte ratio, current density, and Al[sub 2]O[sub 3] concentration. An apparatus is also disclosed to enable identification of the onset of anode corrosion due to disruption of the film to provide real time information regarding the state of the film. 3 figs.

  17. Anodic Concentration Polarization in SOFCs

    SciTech Connect

    Williford, Rick E.; Chick, Lawrence A.; Maupin, Gary D.; Simner, Steve P.; Stevenson, Jeffry W.; Khaleel, Mohammad A.; Wachsman, ED, et al

    2003-08-01

    Concentration polarization is important because it determines the maximum power output of a solid oxide fuel cell (SOFC) at high fuel utilization. Anodic concentration polarization occurs when the demand for reactants exceeds the capacity of the porous ceramic anode to supply them by gas diffusion mechanisms. High tortuosities (bulk diffusion resistances) are often assumed to explain this behavior. However, recent experiments show that anodic concentration polarization originates in the immediate vicinity of the reactive triple phase boundary (TPB) sites near the anode/electrolyte interface. A model is proposed to describe how concentration polarization is controlled by two localized phenomena: competitive adsorption of reactants in areas adjacent to the reactive TPB sites, followed by relatively slow surface diffusion to the reactive sites. Results suggest that future SOFC design improvements should focus on optimization of the reactive area, adsorption, and surface diffusion at the anode/electrolyte interface.

  18. Anode film formation and control

    DOEpatents

    Koski, Oscar; Marschman, Steven C.

    1990-01-01

    A protective film is created about the anode within a cryolite-based electrolyte during electrolytic production of aluminum from alumina. The film function to minimize corrosion of the anode by the cryolitic electrolyte and thereby extend the life of the anode. Various operating parameters of the electrolytic process are controlled to maintain the protective film about the anode in a protective state throughout the electrolytic reduction of alumina. Such parameters include electrolyte temperature, electrolyte ratio, current density, and Al.sub.2 O.sub.3 concentration. An apparatus is also disclosed to enable identification of the onset of anode corrosion due to disruption of the film to provide real time information regarding the state of the film.

  19. A Highly Controllable Electrochemical Anodization Process to Fabricate Porous Anodic Aluminum Oxide Membranes.

    PubMed

    Lin, Yuanjing; Lin, Qingfeng; Liu, Xue; Gao, Yuan; He, Jin; Wang, Wenli; Fan, Zhiyong

    2015-12-01

    Due to the broad applications of porous alumina nanostructures, research on fabrication of anodized aluminum oxide (AAO) with nanoporous structure has triggered enormous attention. While fabrication of highly ordered nanoporous AAO with tunable geometric features has been widely reported, it is known that its growth rate can be easily affected by the fluctuation of process conditions such as acid concentration and temperature during electrochemical anodization process. To fabricate AAO with various geometric parameters, particularly, to realize precise control over pore depth for scientific research and commercial applications, a controllable fabrication process is essential. In this work, we revealed a linear correlation between the integrated electric charge flow throughout the circuit in the stable anodization process and the growth thickness of AAO membranes. With this understanding, we developed a facile approach to precisely control the growth process of the membranes. It was found that this approach is applicable in a large voltage range, and it may be extended to anodization of other metal materials such as Ti as well. PMID:26706687

  20. Catalyzed electrochemical gasification of carbonaceous materials at anode and electrowinning of metals at cathode

    SciTech Connect

    Vaughan, R.J.

    1983-09-20

    The electrochemical gasification reaction of carbonaceous materials by anodic oxidation in an aqueous acidic electrolyte to produce oxides of carbon at the anode and metallic elements at the cathode of an electrolysis cell is catalyzed by the use of an iron catalyst.

  1. X-ray reflectivity study of formation of multilayer porous anodic oxides of silicon.

    SciTech Connect

    Chu, Y.; Fenollosa, R.; Parkhutik, V.; You, H.

    1999-07-21

    The paper reports data on the kinetics of anodic oxide films growth on silicon in aqueous solutions of phosphoric acids as well as a study of the morphology of the oxides grown in a special regime of the oscillating anodic potential. X-ray reflectivity measurements were performed on the samples of anodic oxides using an intense synchrotron radiation source. They have a multilayer structure as revealed by theoretical fitting of the reflectivity data. The oscillations of the anodic potential are explained in terms of synchronized oxidation/dissolution reactions at the silicon surface and accumulation of mechanic stress in the oxide film.

  2. On the anodic aluminium oxide refractive index of nanoporous templates

    NASA Astrophysics Data System (ADS)

    Hierro-Rodriguez, A.; Rocha-Rodrigues, P.; Valdés-Bango, F.; Alameda, J. M.; Jorge, P. A. S.; Santos, J. L.; Araujo, J. P.; Teixeira, J. M.; Guerreiro, A.

    2015-11-01

    In the present study, we have determined the intrinsic refractive index of anodic aluminium oxide, which is originated by the formation of nanoporous alumina templates. Different templates have been fabricated by the conventional two-step anodization procedure in oxalic acid. Their porosities were modified by chemical wet etching allowing the tuning of their effective refractive indexes (air-filled nanopores  +  anodic aluminium oxide). By standard spectroscopic light transmission measurements, the effective refractive index for each different template was extracted in the VIS-NIR region. The determination of the intrinsic anodic aluminium oxide refractive index was performed by using the Maxwell-Garnett homogenization theory. The results are coincident for all the fabricated samples. The obtained refractive index (~1.55) is quite lower (~22%) than the commonly used Al2O3 handbook value (~1.75), showing that the amorphous nature of the anodic oxide structure strongly conditions its optical properties. This difference is critical for the correct design and modeling of optical plasmonic metamaterials based on anodic aluminium oxide nanoporous templates.

  3. Cross-talk between Aβ and endothelial SSAO/VAP-1 accelerates vascular damage and Aβ aggregation related to CAA-AD.

    PubMed

    Solé, Montse; Miñano-Molina, Alfredo J; Unzeta, Mercedes

    2015-02-01

    An association between semicarbazide-sensitive amine oxidase (SSAO) and cerebral amyloid angiopathy (CAA) related to Alzheimer's disease (AD) has been largely postulated. Increased SSAO activity and expression have been detected in cerebrovascular tissue and plasma of AD patients, colocalizing with cerebrovascular amyloid-beta (Aβ) deposits. As an enzyme, SSAO metabolizes primary amines generating hydrogen peroxide, ammonia, and aldehydes. The ability of these products to generate oxidative stress, to enhance the advanced glycation end-product generation, to promote the Aβ aggregation in vitro, and to induce apoptosis supports its role in CAA-related vascular pathology. However, whether the SSAO increase constitutes a cause or it is a consequence of the pathologic process has not been elucidated so far. To set up the nature of this relationship, vascular cell models expressing SSAO were treated with different Aβ forms, simulating the CAA conditions in vitro. It was found that the presence of the vasculotropic Dutch-mutated Aβ1-40 increases (Aβ1-40 D) the SSAO-dependent toxicity, which is accompanied by an increase of SSAO protein availability in endothelial cell membranes. In addition, SSAO enhances Aβ1-40 D and Aβ1-42 deposition on vascular cells by both activity-dependent and -independent mechanisms. Thus, we provide evidences indicating that Aβ itself could be one of the factors inducing SSAO increase in AD, enhancing its toxic effect, and inducing the vascular dysfunction and, in turn, that SSAO stimulates Aβ deposition on the vascular walls, thereby contributing to the CAA-AD progression. Therefore, molecules inhibiting SSAO could provide an alternative treatment for preventing/delaying the progress of CAA-AD-associated vasculopathy.

  4. CaaX-prenyltransferases are essential for expression of genes involvedin the early stages of monoterpenoid biosynthetic pathway in Catharanthus roseus cells.

    PubMed

    Courdavault, Vincent; Thiersault, Martine; Courtois, Martine; Gantet, Pascal; Oudin, Audrey; Doireau, Pierre; St-Pierre, Benoit; Giglioli-Guivarc'h, Nathalie

    2005-04-01

    CaaX-prenyltransferases (CaaX-PTases) catalyse the covalent attachment of isoprenyl groups to conserved cysteine residues located at the C-terminal CaaX motif of a protein substrate. This post-translational modification is required for the function and/or subcellular localization of some transcription factors and components of signal transduction and membrane trafficking machinery. CaaX-PTases, including protein farnesyltransferase (PFT) and type-I protein geranylgeranyltransferase (PGGT-I), are heterodimeric enzymes composed of a common alpha subunit and a specific beta subunit. We have established RNA interference cell lines targeting the beta subunits of PFT and PGGT-I, respectively, in the Catharanthus roseus C20D cell line, which synthesizes monoterpenoid indole alkaloids in response to auxin depletion from the culture medium. In both types of RNAi cell lines, expression of a subset of genes involved in the early stage of monoterpenoid biosynthetic pathway (ESMB genes), including the MEP pathway, is strongly decreased. The role of CaaX-PTases in ESMB gene regulation was confirmed by using the general prenyltransferase inhibitor s-perillyl alcohol (SP) and the specific PFT inhibitor Manumycin A on the wild type line. Furthermore, supplementation of SP inhibited cells with monoterpenoid intermediates downstream of the steps encoded by the ESMB genes restores monoterpenoid indole alkaloids biosynthesis. We conclude that protein targets for both PFT and PGGT-I are required for the expression of ESMB genes and monoterpenoid biosynthesis in C. roseus, this represents a non previously described role for protein prenyltransferase in plants.

  5. Recovery of aluminum alum from waste anode-oxidizing solution

    SciTech Connect

    Lin, S.H.; Lo, M.C.

    1998-12-31

    Recovery of aluminum alum (aluminum ammonium sulfate) by crystallization from waste anode-oxidizing solution in the aluminum surface finishing industry was investigated in this study. Effects of various operating conditions including the mole ratio of ammonium hydroxide and aluminum ion, temperature and seed alum dosage on the aluminum alum formation, acid recovery and aluminum ion removal were examined. Both one- and two-step processes of crystallization were employed in synthesizing the aluminum alum and in the meantime in reducing the aluminum ion concentration in the waste anode-oxidizing solution. Based on the test results, optimum operating conditions were recommended for efficient operation of the crystallization process. The residual acid solution after crystallization was found suitable for reuse in the anode-oxidizing process.

  6. Exciton quenching at PEDOT:PSS anode in polymer blue-light-emitting diodes

    SciTech Connect

    Abbaszadeh, D.; Wetzelaer, G. A. H.; Nicolai, H. T.

    2014-12-14

    The quenching of excitons at the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) anode in blue polyalkoxyspirobifluorene-arylamine polymer light-emitting diodes is investigated. Due to the combination of a higher electron mobility and the presence of electron traps, the recombination zone shifts from the cathode to the anode with increasing voltage. The exciton quenching at the anode at higher voltages leads to an efficiency roll-off. The voltage dependence of the luminous efficiency is reproduced by a drift-diffusion model under the condition that quenching of excitons at the PEDOT:PSS anode and metallic cathode is of equal strength. Experimentally, the efficiency roll-off at high voltages due to anode quenching is eliminated by the use of an electron-blocking layer between the anode and the light-emitting polymer.

  7. Enlarged meristems and delayed growth in plp mutants result from lack of CaaX prenyltransferases.

    PubMed

    Running, Mark P; Lavy, Meirav; Sternberg, Hasana; Galichet, Arnaud; Gruissem, Wilhelm; Hake, Sarah; Ori, Naomi; Yalovsky, Shaul

    2004-05-18

    Meristems require a myriad of intercellular signaling pathways for coordination of cell division within and between functional zones and clonal cell layers. This control of cell division ensures a constant availability of stem cells throughout the life span of the meristem while limiting overproliferation of meristematic cells and maintaining the meristem structure. We have undertaken a genetic screen to identify additional components of meristem signaling pathways. We identified pluripetala (plp) mutants based on their dramatically larger meristems and increased floral organ number. PLURIPETALA encodes the alpha-subunit shared between protein farnesyltransferase and protein geranylgeranyltransferase-I. plp mutants also have altered abscisic acid responses and overall much slower growth rate. plp is epistatic to mutations in the beta-subunit of farnesyltransferase and shows a synergistic interaction with clavata3 mutants. plp mutants lead to insights into the mechanism of meristem homeostasis and provide a unique in vivo system for studying the functional role of prenylation in eukaryotes.

  8. Enlarged meristems and delayed growth in plp mutants result from lack of CaaX prenyltransferases

    PubMed Central

    Running, Mark P.; Lavy, Meirav; Sternberg, Hasana; Galichet, Arnaud; Gruissem, Wilhelm; Hake, Sarah; Ori, Naomi; Yalovsky, Shaul

    2004-01-01

    Meristems require a myriad of intercellular signaling pathways for coordination of cell division within and between functional zones and clonal cell layers. This control of cell division ensures a constant availability of stem cells throughout the life span of the meristem while limiting overproliferation of meristematic cells and maintaining the meristem structure. We have undertaken a genetic screen to identify additional components of meristem signaling pathways. We identified pluripetala (plp) mutants based on their dramatically larger meristems and increased floral organ number. PLURIPETALA encodes the α-subunit shared between protein farnesyltransferase and protein geranylgeranyltransferase-I. plp mutants also have altered abscisic acid responses and overall much slower growth rate. plp is epistatic to mutations in the β-subunit of farnesyltransferase and shows a synergistic interaction with clavata3 mutants. plp mutants lead to insights into the mechanism of meristem homeostasis and provide a unique in vivo system for studying the functional role of prenylation in eukaryotes. PMID:15128936

  9. Multi-anode ionization chamber

    DOEpatents

    Bolotnikov, Aleksey E.; Smith, Graham; Mahler, George J.; Vanier, Peter E.

    2010-12-28

    The present invention includes a high-energy detector having a cathode chamber, a support member, and anode segments. The cathode chamber extends along a longitudinal axis. The support member is fixed within the cathode chamber and extends from the first end of the cathode chamber to the second end of the cathode chamber. The anode segments are supported by the support member and are spaced along the longitudinal surface of the support member. The anode segments are configured to generate at least a first electrical signal in response to electrons impinging thereon.

  10. Determination of chloroacetic acids in drinking water using suppressed ion chromatography with solid-phase extraction.

    PubMed

    Yoshikawa, Kenji; Soda, Yuko; Sakuragawa, Akio

    2009-12-01

    Suppressed ion chromatography with a conductivity detector was developed for the determination of trace amounts of underivatized chloroacetic acids (CAAs). When sodium carbonate and methanol were used as a mobile phase, the simultaneous determination of each CAA took approximately 25 min. The linearity, reproducibility and detection limits were determined for the proposed method. For the solid-phase extraction step, the effects of the pH of the sample solution, sample volume and the eluting agent were tested. Under the optimized extracting conditions, the average recoveries for CAAs spiked in tap water were 83-107%, with an optimal preconcentration factor of 20. The reproducibility of recovery rate for CAAs was 1.2-3.8%, based upon 6 repetitions of the recovery experiments.

  11. Relationship of cytochrome caa sub 3 from Thermus thermophilus to other heme- and copper-containing terminal oxidases

    SciTech Connect

    Mather, M.W.; Springer, P.; Fee, J.A.

    1990-01-01

    Cytochrome oxidases are a key component of the energy metabolism of most aerobic organisms from mammals to bacteria. They are the final enzyme of the membrane associated respiratory chain responsible for converting the chemical energy of reduced substrates to a transmembrane electrochemical potential, which issused by the cell for a wide variety of energy-requiring processes. The most widely studied oxidase is the cytochrome c oxidase of the mammalian mitochondrion. This complex, integral membrane protein contains 13 subunits and four canonical metal centers: heme center a and a{sub 3}; copper centers CU{sub A} and CU{sub B}. It is responsible for electron transfer from reduced chytochrome c to dioxygen with the concomitant reduction of dioxygen to water and the coupled vectorial transfer of protons across the mitochondrial membrane. In this communication we will describe preliminary results of DNA sequencing experiments with the cytochrome caa{sub 3} oxidase, initially undertaken to determine the nature of the subunits of this oxidase and shed light on the distribution of the metal centers. We will speculate on oxidase gene and protein structures and evolutionary relationships in the light of these results and recent sequencing results from other groups. 47 refs., 4 figs., 1 tab.

  12. Free and combined amino acids in marine background atmospheric aerosols over the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Mandalakis, Manolis; Apostolaki, Maria; Tziaras, Thrasivoulos; Polymenakou, Paraskevi; Stephanou, Euripides G.

    2011-02-01

    During a six-week intensive field campaign at a background marine site of the Eastern Mediterranean, consecutive 24-h air samples were collected and analyzed for combined (CAA) and free amino acids (FAA), as well as for key chemical characteristics of aerosols. The total concentration of CAA (719 ± 326 pmol m -3) was on average four times higher than that of FAA (172 ± 147 pmol m -3), while glycine was the most abundant compound detected in both FAA and CAA. Back-trajectory analysis demonstrated that the geographical origin of the air masses did not have a significant influence on the atmospheric levels of amino acids. Wind speed was found to be the most important meteorological factor and it exhibited a negative correlation with both FAA and CAA. Moreover, FAA and CAA concentrations showed a more pronounced correlation with water-soluble organic carbon (WSOC) than elemental carbon. On average, FAA and CAA accounted for 0.3 ± 0.2% and 1.8 ± 0.8% of WSOC, respectively. The levels of anionic surfactants determined as methylene blue active substances did not show any positive correlation with CAA, while the corresponding correlation with FAA was only of marginal significance. The total protein concentration measured by NanoOrange assay was six times higher compared to that measured through CAA. It is suggested that the results from the application of commercially available protein quantitation kits should always be considered with caution, as these are more prone to matrix-related interferences.

  13. Electrically Conductive Anodized Aluminum Surfaces

    NASA Technical Reports Server (NTRS)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to < or = 10(exp 9) Omega-cm. The present treatment does this. The treatment is a direct electrodeposition process in which the outer anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic

  14. Nano structural anodes for radiation detectors

    DOEpatents

    Cordaro, Joseph V.; Serkiz, Steven M.; McWhorter, Christopher S.; Sexton, Lindsay T.; Retterer, Scott T.

    2015-07-07

    Anodes for proportional radiation counters and a process of making the anodes is provided. The nano-sized anodes when present within an anode array provide: significantly higher detection efficiencies due to the inherently higher electric field, are amenable to miniaturization, have low power requirements, and exhibit a small electromagnetic field signal. The nano-sized anodes with the incorporation of neutron absorbing elements (e.g., .sup.10B) allow the use of neutron detectors that do not use .sup.3He.

  15. Sodium hydroxide anodization of Ti-Al-4V adherends

    NASA Technical Reports Server (NTRS)

    Filbey, Jennifer A.; Wightman, J. P.; Progar, D. J.

    1987-01-01

    The use of sodium hydroxide anodization (SHA) for Ti-6Al-4V adherends is examined. The SHA surface is evaluated using SEM, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The SHA procedures of Kennedy et al. (1983) were employed in this experiment. The photomicrographs of the SHA (sandblasted) and PSHA (sandblasted and pickled) oxide surface reveal that the two surfaces differ. The PSHA is patchy and similar to a chromic acid anodization surface and the porosity of the PSHA is more uniform than the SHA surface. The compositions of the surfaces are studied. It is noted that SHA is an effective pretreatment for Ti-6Al-4V adherends.

  16. Anodized Steel Electrodes for Supercapacitors.

    PubMed

    Sagu, Jagdeep S; Wijayantha, K G Upul; Bohm, Mallika; Bohm, Siva; Kumar Rout, Tapan

    2016-03-01

    Steel was anodized in 10 M NaOH to enhance its surface texture and internal surface area for application as an electrode in supercapacitors. A mechanism was proposed for the anodization process. Field-emission gun scanning electron microscopy (FEGSEM) studies of anodized steel revealed that it contains a highly porous sponge like structure ideal for supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) measurements showed that the surface of the anodized steel was Fe2O3, whereas X-ray diffraction (XRD) measurements indicated that the bulk remained as metallic Fe. The supercapacitor performance of the anodized steel was tested in 1 M NaOH and a capacitance of 18 mF cm(-2) was obtained. Cyclic voltammetry measurements showed that there was a large psueudocapacitive contribution which was due to oxidation of Fe to Fe(OH)2 and then further oxidation to FeOOH, and the respective reduction of these species back to metallic Fe. These redox processes were found to be remarkably reversible as the electrode showed no loss in capacitance after 10000 cycles. The results demonstrate that anodization of steel is a suitable method to produce high-surface-area electrodes for supercapacitors with excellent cycling lifetime. PMID:26891093

  17. Anodized Steel Electrodes for Supercapacitors.

    PubMed

    Sagu, Jagdeep S; Wijayantha, K G Upul; Bohm, Mallika; Bohm, Siva; Kumar Rout, Tapan

    2016-03-01

    Steel was anodized in 10 M NaOH to enhance its surface texture and internal surface area for application as an electrode in supercapacitors. A mechanism was proposed for the anodization process. Field-emission gun scanning electron microscopy (FEGSEM) studies of anodized steel revealed that it contains a highly porous sponge like structure ideal for supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) measurements showed that the surface of the anodized steel was Fe2O3, whereas X-ray diffraction (XRD) measurements indicated that the bulk remained as metallic Fe. The supercapacitor performance of the anodized steel was tested in 1 M NaOH and a capacitance of 18 mF cm(-2) was obtained. Cyclic voltammetry measurements showed that there was a large psueudocapacitive contribution which was due to oxidation of Fe to Fe(OH)2 and then further oxidation to FeOOH, and the respective reduction of these species back to metallic Fe. These redox processes were found to be remarkably reversible as the electrode showed no loss in capacitance after 10000 cycles. The results demonstrate that anodization of steel is a suitable method to produce high-surface-area electrodes for supercapacitors with excellent cycling lifetime.

  18. Square-wave anodic-stripping voltammetric determination of Cd, Pb, and Cu in a hydrofluoric acid solution of siliceous spicules of marine sponges (from the Ligurian Sea, Italy, and the Ross Sea, Antarctica).

    PubMed

    Truzzi, C; Annibaldi, A; Illuminati, S; Bassotti, E; Scarponi, G

    2008-09-01

    Square-wave anodic-stripping voltammetry (SWASV) was set up and optimized for simultaneous determination of cadmium, lead, and copper in siliceous spicules of marine sponges, directly in the hydrofluoric acid solution (approximately 0.55 mol L(-1) HF, pH approximately 1.9). A thin mercury-film electrode (TMFE) plated on to an HF-resistant epoxy-impregnated graphite rotating-disc support was used. The optimum experimental conditions, evaluated also in terms of the signal-to-noise ratio, were as follows: deposition potential -1100 mV vs. Ag/AgCl, KCl 3 mol L(-1), deposition time 3-10 min, electrode rotation 3000 rpm, SW scan from -1100 mV to +100 mV, SW pulse amplitude 25 mV, frequency 100 Hz, DeltaE(step) 8 mV, t(step) 100 ms, t(wait) 60 ms, t(delay) 2 ms, t(meas) 3 ms. Under these conditions the metal peak potentials were Cd -654 +/- 1 mV, Pb -458 +/- 1 mV, Cu -198 +/- 1 mV. The electrochemical behaviour was reversible for Pb, quasi-reversible for Cd, and kinetically controlled (possibly following chemical reaction) for Cu. The linearity of the response with concentration was verified up to approximately 4 microg L(-1) for Cd and Pb and approximately 20 microg L(-1) for Cu. The detection limits were 5.8 ng L(-1), 3.6 ng L(-1), and 4.3 ng L(-1) for Cd, Pb, and Cu, respectively, with t(d) = 5 min. The method was applied for determination of the metals in spicules of two specimens of marine sponges (Demosponges) from the Portofino natural reserve (Ligurian Sea, Italy, Petrosia ficiformis) and Terra Nova Bay (Ross Sea, Antarctica, Sphaerotylus antarcticus). The metal contents varied from tens of ng g(-1) to approximately 1 microg g(-1), depending on the metal considered and with significant differences between the two sponge species. PMID:18642105

  19. Phenothiazine-based CaaX competitive inhibitors of human farnesyltransferase bearing a cysteine, methionine, serine or valine moiety as a new family of antitumoral compounds.

    PubMed

    Dumitriu, Gina-Mirabela; Bîcu, Elena; Belei, Dalila; Rigo, Benoît; Dubois, Joëlle; Farce, Amaury; Ghinet, Alina

    2015-10-15

    A new family of CaaX competitive inhibitors of human farnesyltransferase based on phenothiazine and carbazole skeleton bearing a l-cysteine, l-methionine, l-serine or l-valine moiety was designed, synthesized and biologically evaluated. Phenothiazine derivatives proved to be more active than carbazole-based compounds. Phenothiazine 1b with cysteine residue was the most promising inhibitor of human farnesyltransferase in the current study.

  20. Novel patterns by focused ion beam guided anodization.

    PubMed

    Chen, Bo; Lu, Kathy; Tian, Zhipeng

    2011-01-18

    Focused ion beam patterning is a powerful technique for guiding the growth of ordered hexagonal porous anodic alumina. This study shows that, with the guidance of the focused ion beam patterning, hexagonal porous anodic alumina with interpore distances from 200 to 425 nm can be fabricated at 140 V in 0.3 M phosphoric acid. When the interpore distance is increased to 500 nm, alternating diameter nanopore arrays are synthesized with the creation and growth of new small pores at the junctions of three large neighboring pores. Moreover, alternating diameter nanopore arrays in hexagonal arrangement are fabricated by focused ion beam patterning guided anodization. Interpore distance is an important parameter affecting the arrangement of alternating diameter nanopore arrays. Different types of novel patterns are obtained by designing different focused ion beam concave arrays. The fundamental understanding of the process is discussed.

  1. Combined effect of loss of the caa3 oxidase and Crp regulation drives Shewanella to thrive in redox-stratified environments.

    PubMed

    Zhou, Guangqi; Yin, Jianhua; Chen, Haijiang; Hua, Yijie; Sun, Linlin; Gao, Haichun

    2013-09-01

    Shewanella species are a group of facultative Gram-negative microorganisms with remarkable respiration abilities that allow the use of a diverse array of terminal electron acceptors (EA). Like most bacteria, S. oneidensis possesses multiple terminal oxidases, including two heme-copper oxidases (caa3- and cbb3-type) and a bd-type quinol oxidase. As aerobic respiration is energetically favored, mechanisms underlying the fact that these microorganisms thrive in redox-stratified environments remain vastly unexplored. In this work, we discovered that the cbb3-type oxidase is the predominant system for respiration of oxygen (O2), especially when O2 is abundant. Under microaerobic conditions, the bd-type quinol oxidase has a significant role in addition to the cbb3-type oxidase. In contrast, multiple lines of evidence suggest that under test conditions the caa3-type oxidase, an analog to the mitochondrial enzyme, has no physiological significance, likely because of its extremely low expression. In addition, expression of both cbb3- and bd-type oxidases is under direct control of Crp (cAMP receptor protein) but not the well-established redox regulator Fnr (fumarate nitrate regulator) of canonical systems typified in Escherichia coli. These data, collectively, suggest that adaptation of S. oneidensis to redox-stratified environments is likely due to functional loss of the caa3-type oxidase and switch of the regulatory system for respiration.

  2. Structural and Mechanical Characteristics of Anodic Oxide Films on Titanium

    SciTech Connect

    Pang, Mengzhi; Eakins, Daniel E; Norton, Murray G; Bahr, David F

    2001-01-01

    Oxide films were grown electrochemically on polycrystalline titanium in 0.1 M sulfuric acid (H2SO4) from open-circuit potential to a final potential of 9.4 V (vs silver-silver chloride [Ag-AgCl]) using three anodization rates: a step polarization, growth at 200 mV/s, and growth at 1 mV/s. Anodic polarization curves showed various degrees of oxygen evolution above 5.4 VAg-AgCl, indicating that the extent of oxide film breakdown depends on film growth rate, with slower growth rates undergoing more severe film breakdown. In-situ characterization of mechanical behavior of oxide films by nanoindentation revealed that the oxide film can sustain a tensile stress up to 2.5 GPa prior to film fracture. Among these three anodization rates, the oxide film formed by step polarization exhibited the highest film-strengthening effect. At applied potentials prior to oxide film breakdown, all films exhibited a strength of ≈1 GPa. The films ranged from amorphous titanium dioxide (TiO2) to anatase, with the extent of crystallization increasing with decreasing film growth rate. Correlations between electrochemical polarization, structural characteristics, and the mechanical behavior of these anodic films are discussed in relationship to electrostrictive stresses, which may lead to the breakdown of passive films. KEY WORDS: anodic polarization, films, nanoindentation, titanium, transmission electron microscopy.

  3. A Pre-Steady State Kinetic Analysis of the αY60W mutant of trans-3-Chloroacrylic Acid Dehalogenase: Implications for the Mechanism of the Wild-type Enzyme†

    PubMed Central

    Huddleston, Jamison P.; Schroeder, Gottfried K.; Johnson, Kenneth A.; Whitman, Christian P.

    2012-01-01

    The bacterial degradation of the nematicide 1,3-dichloropropene, an isomeric mixture, requires the action of trans- and cis-3-chloracrylic acid dehalogenase (CaaD and cis-CaaD, respectively). Both enzymes are tautomerase superfamily members and share a core catalytic mechanism for the hydrolytic dehalogenation of the respective isomer of 3-haloacrylate. The observation that cis-CaaD requires two additional residues raises the question of how CaaD carries out a comparable reaction with fewer catalytic residues. As part of an effort to determine the basis for the apparently simpler CaaD-catalyzed reaction, the kinetic mechanism was determined by stopped-flow and chemical quench techniques using a fluorescent mutant form of the enzyme, αY60W-CaaD, and trans-3-bromoacrylate as the substrate. The data from these experiments as well as bromide inhibition studies are best accommodated by a six-step model that provides individual rate constants for substrate binding, chemistry, and a proposed conformational change occurring after chemistry followed by release of malonate semialdehyde and bromide. The conformational change and product release rates are comparable and together they limit the rate of turnover. The kinetic analysis and modeling studies validate the αY60W-CaaD mutant as an accurate reporter of active site events during the course of the enzyme-catalyzed reaction. The kinetic mechanism for the αY60W-CaaD-catalyzed reaction is comparable to that obtained for the cis-CaaD-catalyzed reaction. The kinetic model and the validated αY60W-CaaD mutant set the stage for an analysis of active site mutants to explore the contributions of individual catalytic residues and the basis for the simplicity of the reaction. PMID:23110338

  4. Three-dimensional anode engineering for the direct methanol fuel cell

    NASA Astrophysics Data System (ADS)

    Bauer, A.; Oloman, C. W.; Gyenge, E. L.

    Catalyzed graphite felt three-dimensional anodes were investigated in direct methanol fuel cells (DMFCs) operated with sulfuric acid supporting electrolyte. With a conventional serpentine channel flow field the preferred anode thickness was 100 μm, while a novel flow-by anode showed the best performance with a thickness of 200-300 μm. The effects of altering the methanol concentration, anolyte flow rate and operating temperature on the fuel cell superficial power density were studied by full (2 3 + 1) factorial experiments on a cell with anode area of 5 cm 2 and excess oxidant O 2 at 200 kPa(abs). For operation in the flow-by mode with 2 M methanol at 2 cm 3 min -1 and 353 K the peak power density was 2380 W m -2 with a PtRuMo anode catalyst, while a PtRu catalyst yielded 2240 W m -2 under the same conditions.

  5. Assessing the Risk That Phytophthora melonis Can Develop a Point Mutation (V1109L) in CesA3 Conferring Resistance to Carboxylic Acid Amide Fungicides

    PubMed Central

    Chen, Lei; Zhu, Shusheng; Lu, Xiaohong; Pang, Zhili; Cai, Meng; Liu, Xili

    2012-01-01

    The risk that the plant pathogen Phytophthora melonis develops resistance to carboxylic acid amide (CAA) fungicides was determined by measuring baseline sensitivities of field isolates, generating resistant mutants, and measuring the fitness of the resistant mutants. The baseline sensitivities of 80 isolates to flumorph, dimethomorph and iprovalicarb were described by unimodal curves, with mean EC50 values of 0.986 (±0.245), 0.284 (±0.060) and 0.327 (±0.068) µg/ml, respectively. Seven isolates with different genetic background (as indicated by RAPD markers) were selected to generate CAA-resistance. Fifty-five resistant mutants were obtained from three out of seven isolates by spontaneous selection and UV-mutagenesis with frequencies of 1×10−7 and 1×10−6, respectively. CAA-resistance was stable for all mutants. The resistance factors of these mutants ranged from 7 to 601. The compound fitness index (CFI  =  mycelial growth × zoospore production × pathogenicity) was often lower for the CAA-resistant isolates than for wild-type isolates, suggesting that the risk of P. melonis developing resistance to CAA fungicides is low to moderate. Among the CAA-resistant isolates, a negative correlation between EC50 values was found for iprovalicarb vs. flumorph and for iprovalicarb vs. dimethomorph. Comparison of the full-length cellulose synthase 3 (CesA3) between wild-type and CAA-resistant isolates revealed only one point mutation at codon position 1109: a valine residue (codon GTG in wild-type isolates) was converted to leucine (codon CTG in resistant mutants). This represents a novel point mutation with respect to mutations in CesA3 conferring resistance to CAA fungicides. Based on this mutation, an efficient allelic-specific PCR (AS-PCR) method was developed for rapid detection of CAA-resistance in P. melonis populations. PMID:22848705

  6. Tested Demonstrations: Dyeing of Anodized Aluminum.

    ERIC Educational Resources Information Center

    Gilbert, George L., Ed.

    1983-01-01

    Provides a list of needed materials, required preparations, and instructions for demonstrating the dyeing of anodized aluminum. Discusses the chemistry involved and gives equations for reactions occurring at the anode and cathode. (JM)

  7. Anodes for Rechargeable Lithium-Sulfur Batteries

    SciTech Connect

    Cao, Ruiguo; Xu, Wu; Lu, Dongping; Xiao, Jie; Zhang, Jiguang

    2015-04-10

    In this work, we will review the recent developments on the protection of Li metal anode in Li-S batteries. Various strategies used to minimize the corrosion of Li anode and reducing its impedance increase will be analyzed. Other potential anodes used in sulfur based rechargeable batteries will also be discussed.

  8. Anode Fall Formation in a Hall Thruster

    SciTech Connect

    Leonid A. Dorf; Yevgeny F. Raitses; Artem N. Smirnov; Nathaniel J. Fisch

    2004-06-29

    As was reported in our previous work, accurate, nondisturbing near-anode measurements of the plasma density, electron temperature, and plasma potential performed with biased and emissive probes allowed the first experimental identification of both electron-repelling (negative anode fall) and electron-attracting (positive anode fall) anode sheaths in Hall thrusters. An interesting new phenomenon revealed by the probe measurements is that the anode fall changes from positive to negative upon removal of the dielectric coating, which appears on the anode surface during the course of Hall thruster operation. As reported in the present work, energy dispersion spectroscopy analysis of the chemical composition of the anode dielectric coating indicates that the coating layer consists essentially of an oxide of the anode material (stainless steel). However, it is still unclear how oxygen gets into the thruster channel. Most importantly, possible mechanisms of anode fall formation in a Hall thruster with a clean and a coated anodes are analyzed in this work; practical implication of understanding the general structure of the electron-attracting anode sheath in the case of a coated anode is also discussed.

  9. Anode power deposition in quasi-steady MPD arcs. [accelerator anode heat flux measurement

    NASA Technical Reports Server (NTRS)

    Saber, A. J.; Jahn, R. G.

    1973-01-01

    The power deposited in the anode of a quasi-steady MPD accelerator has been measured directly by thermocouples attached to the inside surface of a shell anode which provide a local measurement of anode heat flux. The results over a range of arc currents from 5.5 to 44 kiloamperes and argon mass flows from 1 g/sec to 48 g/sec show that the fraction of the total input power deposited in the anode decreases drastically from 50% at an arc power of 200 kW to 10% at 20 MW, and that anode power is not uniformly deposited in the anode. A theoretical model of the anode heat transfer, including effects of anode work function, electron thermal energy, and anode sheath, can be brought into reasonable agreement with the measurements, provided the effective range of the conduction electrons from within the discharge plasma to the anode surface is properly acknowledged.

  10. Anode binders for electrochemical cells

    SciTech Connect

    Ismail, M.I.

    1986-08-26

    An electrochemical cell is described comprised of an alkaline electrolyte, a manganese dioxide cathode and a gelled anode comprised of mercury amalgamated zinc, a starch graft copolymer gelling agent and a liquid petrolatum binder in amounts between 0.02% to 0.2% by weight thereof.

  11. Electrochemical cell with calcium anode

    DOEpatents

    Cooper, John F.; Hosmer, Pamela K.; Kelly, Benjamin E.

    1979-01-01

    An electrochemical cell comprising a calcium anode and a suitable cathode in an alkaline electrolyte consisting essentially of an aqueous solution of an hydroxide and a chloride. Specifically disclosed is a mechanically rechargeable calcium/air fuel cell with an aqueous NaOH/NaCl electrolyte.

  12. High performance zinc anode for battery applications

    NASA Technical Reports Server (NTRS)

    Casey, John E., Jr. (Inventor)

    1998-01-01

    An improved zinc anode for use in a high density rechargeable alkaline battery is disclosed. A process for making the zinc electrode comprises electrolytic loading of the zinc active material from a slightly acidic zinc nitrate solution into a substrate of nickel, copper or silver. The substrate comprises a sintered plaque having very fine pores, a high surface area, and 80-85 percent total initial porosity. The residual porosity after zinc loading is approximately 25-30%. The electrode of the present invention exhibits reduced zinc mobility, shape change and distortion, and demonstrates reduced dendrite buildup cycling of the battery. The disclosed battery is useful for applications requiring high energy density and multiple charge capability.

  13. Improved Anode for a Direct Methanol Fuel Cell

    NASA Technical Reports Server (NTRS)

    Valdez, Thomas; Narayanan, Sekharipuram

    2005-01-01

    A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the

  14. Crystallization kinetics of citric acid anhydrate

    NASA Astrophysics Data System (ADS)

    Nemdili, L.; Koutchoukali, O.; Bouhelassa, M.; Seidel, J.; Mameri, F.; Ulrich, J.

    2016-10-01

    The solubility curve, metastable zone width (MSZW) and Crystallization kinetics (nucleation and growth) were measured and estimated during batch crystallization of citric acid anhydrate (CAA). The solubility of citric acid in pure water was measured over the temperature range from 15 to 60 °C using a refractometer. The experimental data were correlated by the modified Apelblat equation. The MSZW was determined under four cooling rates for different citric acid concentrations by means of an ultrasonic technique. The primary nucleation kinetics of CAA was calculated based on these data and the polythermal method of Nyvlt. It was found that the MSZW obtained is in good agreement with literature. Crystal growth rates were calculated by two methods. The first one used seeded isothermal growth experiments (desupersaturation curve) and the derivatives method of Garside. The second method used the measurement of the dimension change of a single crystal in a microscopic cell at different supersaturation levels.

  15. Anode power deposition in magnetoplasmadynamic thrusters

    NASA Technical Reports Server (NTRS)

    Gallimore, A. D.; Kelly, A. J.; Jahn, R. G.

    1993-01-01

    Results of anode heat-flux and anode fail measurements from a multimegawatt self-field quasi-steady magnetoplasmadynamic (MPD) thruster are presented. Measurements were obtained with argon and helium propellants for a variety of currents and mass flow rates. Anode heat flux was directly measured with thermocouples attached to the inner surface of a hollowed section. Anode falls were determined both from floating probes and through heat flux measurements. Comparison of data acquired through either method shows excellent agreement. Anode falls varied between 4-50 V with anode power fractions reaching 70 percent with helium at 150 kW, and 50 percent with argon at 1.9 MW. The anode fall was found to correlate well with electron Hall parameters calculated from triple Langmuir and magnetic probe data collected near the anode. Two possible explanations for this result are proposed: (1) the establishment of large electric fields at the anode to maintain current conduction across the strong magnetic fields; and (2) anomalous resistivity resulting from the onset of microturbulence in the plasma. To investigate the latter hypothesis, electric field, magnetic field, and current density profiles measured in the vicinity of the anode were incorporated into Ohm's law to estimate the electrical conductivity. Results of this analysis show a substantial deviation of the measured conductivity from that calculated with classical formulas. These results imply that anomalous effects are present in the plasma near the anode.

  16. Anodes for cathodic protection of reinforced concrete

    SciTech Connect

    S.J. Bullard; B.S. Covino, Jr.; S.D. Cramer; G.R. Holcomb; J.H. Russell

    2000-03-01

    Consumable anodes were evaluated in the laboratory for use in cathodic protection systems for steel reinforced concrete bridges in coastal environments and in areas where de-icing salts are employed. The anode materials include Zn-hydrogel and thermal-sprayed Zn, Zn-15Al, and Al-12Zn-0.2In. These anodes were evaluated for service in both galvanic (GCP) and impressed current (ICCP) cathodic protection systems. ICCP anodes were electrochemically aged at a factor of 15 times greater than used by the Oregon Department of Transportation in typical coastal ICCP systems (2.2 mA/m{sup 2} based on anode area). Increasing moisture at the anode-concrete interface reduced the operating voltage of all the anodes. The pH at the anode-concrete interface fell to 7 to 8.5 with electrochemical age. Bond strength between the anodes and concrete decreased with electrochemical aging. Interfacial chemistry was the critical link between long-term anode performance and electrochemical age. Zn-hydrogel and the rmal-sprayed Zn and Al-12Zn-0.2In GCP anodes appear to supply adequate protection current to rebar in the Cape Perpetua Viaduct.

  17. [Vernier Anode Design and Image Simulation].

    PubMed

    Zhao, Ai-rong; Ni, Qi-liang; Song, Ke-fei

    2015-12-01

    Based-MCP position-sensitive anode photon-counting imaging detector is good at detecting extremely faint light, which includes micro-channel plate (MCP), position-sensitive anode and readout, and the performances of these detectors are mainly decided by the position-sensitive anode. As a charge division anode, Vernier anode using cyclically varying electrode areas which replaces the linearly varying electrodes of wedge-strip anode can get better resolution and greater electrode dynamic range. Simulation and design of the Vernier anode based on Vernier's decode principle are given here. Firstly, we introduce the decode and design principle of Vernier anode with nine electrodes in vector way, and get the design parameters which are the pitch, amplitude and the coarse wavelength of electrode. Secondly, we analyze the effect of every design parameters to the imaging of the detector. We simulate the electron cloud, the Vernier anode and the detector imaging using Labview software and get the relationship between the pitch and the coarse wavelength of the anode. Simultaneously, we get the corresponding electron cloud for the designing parameters. Based on the result of the simulation and the practical machining demand, a nine electrodes Vernier anode was designed and fabricated which has a pitch of 891 µm, insulation width of 25 µm, amplitude of 50 µm, coarse pixel numbers of 5. PMID:26964205

  18. [Vernier Anode Design and Image Simulation].

    PubMed

    Zhao, Ai-rong; Ni, Qi-liang; Song, Ke-fei

    2015-12-01

    Based-MCP position-sensitive anode photon-counting imaging detector is good at detecting extremely faint light, which includes micro-channel plate (MCP), position-sensitive anode and readout, and the performances of these detectors are mainly decided by the position-sensitive anode. As a charge division anode, Vernier anode using cyclically varying electrode areas which replaces the linearly varying electrodes of wedge-strip anode can get better resolution and greater electrode dynamic range. Simulation and design of the Vernier anode based on Vernier's decode principle are given here. Firstly, we introduce the decode and design principle of Vernier anode with nine electrodes in vector way, and get the design parameters which are the pitch, amplitude and the coarse wavelength of electrode. Secondly, we analyze the effect of every design parameters to the imaging of the detector. We simulate the electron cloud, the Vernier anode and the detector imaging using Labview software and get the relationship between the pitch and the coarse wavelength of the anode. Simultaneously, we get the corresponding electron cloud for the designing parameters. Based on the result of the simulation and the practical machining demand, a nine electrodes Vernier anode was designed and fabricated which has a pitch of 891 µm, insulation width of 25 µm, amplitude of 50 µm, coarse pixel numbers of 5.

  19. Anode power in quasisteady magnetoplasmadynamic accelerators

    NASA Technical Reports Server (NTRS)

    Saber, A. J.; Jahn, R. G.

    1978-01-01

    Anode heat flux in a quasi-steady MPD accelerator has been measured directly and locally by thermocouples attached to the inside surface of a shell anode. These measurements show that over a range of arc current from 5.5 to 44 kA, and argon mass flow from 1 to 48 g/s, the fraction of the total arc power deposited in the anode decreases from 50% at 200 kW to 10% at 20 MW. A theoretical model of the anode heat transfer asserts that energy exchange between electrons and heavy particles in the plasma near the anode occurs over distances greater than the anode sheath thickness, and hence the usual anode fall voltage, electron temperature, and work function contributions to the anode heat flux are supplemented by a contribution from the interelectrode potential. Calculations of anode heat flux using the measured current density, plasma potential, and electron temperature in the plasma adjacent to the anode agree with the direct measurements and indicate that the decrease in anode power fraction at higher arc powers can be attributed to the smaller mean free paths in the interelectrode plasma.

  20. Fabrication of advanced design (grooved) cermet anodes

    NASA Astrophysics Data System (ADS)

    Windisch, C. F., Jr.; Huettig, F. R.

    1993-05-01

    Attempts were made to fabricate full-size anodes with advanced, or grooved, design using isostatic pressing, slip casting injection molding. Of the three approaches, isostatic pressing produced an anode with dimensions nearest to the target specifications, without serious macroscopic flaws. This approach is considered the most promising for making advanced anodes for aluminum smelting. However, significant work still remains to optimize the physical properties and microstructure of the anode, both of which were significantly different from that of previous anodes. Injection molding and slip casting yielded anode materials with serious deficiencies, including cracks and holes. Injection molding gave cermet material with the best intrinsic microstructure, i.e., the microstructure of the material between macroscopic flaws was very similar to that of anodes previously made at PNL. The reason for the similarity may have to do with amount of residual binder in the material prior to sintering.

  1. Fabrication of advanced design (grooved) cermet anodes

    SciTech Connect

    Windisch, C.F. Jr.; Huettig, F.R.

    1993-05-01

    Attempts were made to fabricate full-size anodes with advanced, or grooved, design using isostatic pressing, slip casting injection molding. Of the three approaches, isostatic pressing produced an anode with dimensions nearest to the target specifications, without serious macroscopic flaws. This approach is considered the most promising for making advanced anodes for aluminum smelting. However, significant work still remains to optimize the physical properties and microstructure of the anode, both of which were significantly different from that of previous anodes. Injection molding and slip casting yielded anode materials with serious deficiencies, including cracks and holes. Injection molding gave cermet material with the best intrinsic microstructure, i.e., the microstructure of the material between macroscopic flaws was very similar to that of anodes previously made at PNL. Reason for the similarity may have to do with amount of residual binder in the material prior to sintering.

  2. Surface modifications for enhanced enzyme immobilization and improved electron transfer of PQQ-dependent glucose dehydrogenase anodes.

    PubMed

    Lopez, Ryan J; Babanova, Sofia; Artyushkova, Kateryna; Atanassov, Plamen

    2015-10-01

    Pyrroloquinoline quinone dependent soluble glucose dehydrogenase (PQQ-sGDH) enzymatic MWCNT electrodes were p roduced using 1-pyrenecarboxylic acid (PCA) activated through carbodiimide functionalization and 1-Pyrenebutyric acid N-hydroxysuccinimide ester (PBSE) as tethering agents. At 600 mV potential, the current density generated by the activated-PCA tethered PQQ-sGDH anode was significantly greater than the current density generated by the untethered PQQ-sGDH and PBSE tethered anodes, and performance was nearly identical to the performance of a covalently bound PQQ-sGDH anode. A technique for covalently bonding heme-b (hemin), a natural quinohemoprotein porphyrin redox cofactor, to carbon nanotubes modified with arylamine groups is reported. The resulting performance of the covalently bound hemin PQQ-sGDH anode is considerably higher than that of any other PQQ-sGDH anodes tested.

  3. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

    Sopchak, David A.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Kotovsky, Jack; Graff, Robert T.

    2010-08-17

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  4. Micro-electro-mechanical systems phosphoric acid fuel cell

    DOEpatents

    Sopchak, David A.; Morse, Jeffrey D.; Upadhye, Ravindra S.; Kotovsky, Jack; Graff, Robert T.

    2010-12-21

    A phosphoric acid fuel cell system comprising a porous electrolyte support, a phosphoric acid electrolyte in the porous electrolyte support, a cathode electrode contacting the phosphoric acid electrolyte, and an anode electrode contacting the phosphoric acid electrolyte.

  5. Effect of anodization on the surface characteristics and electrochemical behaviour of zirconium in artificial saliva.

    PubMed

    Romonti, Daniela E; Gomez Sanchez, Andrea V; Milošev, Ingrid; Demetrescu, Ioana; Ceré, Silvia

    2016-05-01

    The paper is focused on elaboration of ZrO2 films on pure zirconium via anodizing in phosphoric acid with and without fluoride at constant potentials of 30 V and 60 V. The structure and composition of the films were investigated using scanning electronic microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The composition of the oxides formed at both potentials can be identified as monoclinic ZrO2. In addition to Zr and O, the layers formed in phosphoric acid contain phosphorus originating from the phosphoric acid. When the phosphoric acid solution contains NaF, fluorine is also incorporated into the oxide layer. The oxides formed at a higher voltage have greater roughness than those formed at 30 V. Anodized samples exhibit smaller current densities during anodic polarization compared to the as-received zirconium covered with native oxide. PMID:26952447

  6. Electrochemical mineralization pathway of quinoline by boron-doped diamond anodes.

    PubMed

    Wang, Chunrong; Ma, Keke; Wu, Tingting; Ye, Min; Tan, Peng; Yan, Kecheng

    2016-04-01

    Boron-doped diamond anodes were selected for quinoline mineralization, and the resulting intermediates, phenylpropyl aldehyde, phenylpropionic acid, and nonanal were identified and followed during quinoline oxidation by gas chromatography-mass spectrometry and high-performance liquid chromatography. The evolutions of formic acid, acetic acid, oxalic acid, NO2(-), NO3(-), and NH4(+) were quantified. A new reaction pathway for quinoline mineralization by boron-doped diamond anodes has been proposed, where the pyridine ring in quinoline is cleaved by a hydroxyl radical giving phenylpropyl aldehyde and NH4(+). Phenylpropyl aldehyde is quickly oxidized into phenylpropionic acid, and the benzene ring is cleaved giving nonanal. This is further oxidized to formic acid, acetic acid, and oxalic acid. Finally, these organic intermediates are mineralized to CO2 and H2O. NH4(+) is also oxidized to NO2(-) and on to NO3(-). The results will help to gain basic reference for clearing intermediates and their toxicity.

  7. Preventing Cracking of Anodized Coatings

    NASA Technical Reports Server (NTRS)

    He, Charles C.; Heslin, Thomas M.

    1995-01-01

    Anodized coatings have been used as optical and thermal surfaces in spacecraft. Particulate contamination from cracked coatings is a concern for many applications. The major cause for the cracking is the difference in the coefficient of thermal expansion between the oxide coatings and the aluminum substrate. The loss of water when the coating is exposed to a vacuum also could induce cracking of the coating. Hot-water sealing was identified as the major cause for the cracking of the coatings because of the large temperature change when the parts were immersed in boiling water and the water was absorbed in the coating. when the hot-water sealing process was eliminated, the cracking resistance of the anodized coatings was greatly improved. Also, it was found that dyed black coatings were more susceptible than clear coatings to cracking during thermo-vacuum cyclings.

  8. Novel, electrolyte solutions comprising fully inorganic salts with high anodic stability for rechargeable magnesium batteries

    SciTech Connect

    Doe, RE; Han, R; Hwang, J; Gmitter, AJ; Shterenberg, I; Yoo, HD; Pour, N; Aurbach, D

    2014-01-01

    Herein the first inorganic magnesium salt solution capable of highly reversible magnesium electrodeposition is presented. Synthesized by acid-base reaction of MgCl2 and Lewis acidic compounds such as AlCl3, this salt class demonstrates upwards of 99% Coulombic efficiency, deposition overpotential of <200 mV, and anodic stability of 3.1 V.

  9. Anodic Fenton process assisted by a microbial fuel cell for enhanced degradation of organic pollutants.

    PubMed

    Liu, Xian-Wei; Sun, Xue-Fei; Li, Dao-Bo; Li, Wen-Wei; Huang, Yu-Xi; Sheng, Guo-Ping; Yu, Han-Qing

    2012-09-15

    The electro-Fenton process is efficient for degradation of organic pollutants, but it suffers from the high operating costs due to the need of power investment. Here, a new anodic Fenton system is developed for energy-saving and efficient treatment of organic pollutants by incorporating microbial fuel cell (MFC) into an anodic Fenton process. This system is composed of an anodic Fenton reactor and a two-chamber air-cathode MFC. The power generated from a two-chamber MFC is used to drive the anodic Fenton process for Acid Orange 7 (AO7) degradation through accelerating in situ generation of Fe(2+) from sacrificial iron. The kinetic results show that the MFC-assisted anodic Fenton process system had a significantly higher pseudo-first-order rate constant than those for the chemical Fenton methods. The electrochemical analysis reveals that AO7 did not hinder the corrosion of iron. The anodic Fenton process was influenced by the MFC performance. It was also found that increasing dissolved oxygen in the cathode improved the MFC power density, which in turn enhanced the AO7 degradation rate. These clearly demonstrate that the anodic Fenton process could be integrated with MFC to develop a self-sustained system for cost-effective and energy-saving electrochemical wastewater treatment.

  10. Effect of CrO3 Sealing Time on Anodized A12024-T3

    NASA Astrophysics Data System (ADS)

    Korda, Akhmad A.; Hidayat, R. Z.

    2016-08-01

    The effect of CrO3 sealing time on anodized aluminum alloy has been investigated. A1 2024-T3 were used as substrate. Anodizing was carried out using chromic acid. CrO3 sealing was conducted in CrO3 solution for 30, 60, 90, 120 and 150 minutes. As comparison, other specimens were also prepared as anodized and boiled water sealing. Thickness of the coating was observed by optical microscope. Anodized and sealing layer was analyzed by X- ray diffraction. The hardness of as anodized, boiled water sealing and CrO3 sealing were compared. The highest hardness is achieved by CrO3 sealed specimen and followed by boiled water sealing and as anodized specimens. The longer the processes of CrO3 sealing the higher layer thickness and therefore the higher hardness of the oxide layer. The best resistance to electrolyte penetration is achieved by the CrO3 sealed specimen followed by boiled water sealed and as anodized specimens. The higher thickness of oxide layer, the higher the resistance against electrolyte penetration.

  11. Bacterial adherence to anodized titanium alloy

    NASA Astrophysics Data System (ADS)

    Pérez-Jorge Peremarch, C.; Pérez Tanoira, R.; Arenas, M. A.; Matykina, E.; Conde, A.; De Damborenea, J. J.; Gómez Barrena, E.; Esteban, J.

    2010-11-01

    The aim of this study was to evaluate Staphylococcus sp adhesion to modified surfaces of anodized titanium alloy (Ti-6Al-4V). Surface modification involved generation of fluoride-containing titanium oxide nanotube films. Specimens of Ti-6Al-4V alloy 6-4 ELI-grade 23- meets the requirements of ASTM F136 2002A (AMS 2631B class A1) were anodized in a mixture of sulphuric/hydrofluoric acid at 20 V for 5 and 60 min to form a 100 nm-thick porous film of 20 nm pore diameter and 230 nm-thick nanotube films of 100 nm in diameter. The amount of fluorine in the oxide films was of 6% and of 4%, respectively. Collection strains and six clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis were studied. The adherence study was performed using a previously published protocol by Kinnari et al. The experiments were performed in triplicates. As a result, lower adherence was detected for collection strains in modified materials than in unmodified controls. Differences between clinical strains were detected for both species (p<0.0001, Kruskal-Wallis test), although global data showed similar results to that of collection strains (p<0.0001, Kruskal-Wallis test). Adherence of bacteria to modified surfaces was decreased for both species. The results also reflect a difference in the adherence between S. aureus and S. epidermidis to the modified material. As a conclusion, not only we were able to confirm the decrease of adherence in the modified surface, but also the need to test multiple clinical strains to obtain more realistic microbiological results due to intraspecies differences.

  12. Electrospray ionization tandem mass spectrometric study on the effect of N-terminal beta- and gamma-carbo amino acids on fragmentation of GABA-hybrid peptides.

    PubMed

    Ramesh, V; Ramesh, M; Srinivas, R; Sharma, G V M; Jayaprakash, P

    2008-11-01

    The fragmentations of protonated and deprotonated ions of a new class of N-blocked hybrid Boc-carbopeptides containing repeats of gamma-Caa/gammaAbu- and beta-Caa/gammaAbu- (Caa==C-linked carbo gamma(4)-/beta(3)- amino acids derived from D-xylose, gammaAbu = gamma-aminobutyric acid) have been studied using electrospray ionization (ESI) ion-trap tandem mass spectrometry (MS/MS). MS/MS of a pair of these protonated diastereomers produces distinct fragmentation of the Boc group. The formation of [M + H-56](+) corresponding to loss of isobutylene is more pronounced for Boc-NH-(R)-gamma-Caa-gammaAbu-OH (2) whereas it is of low abundance for Boc-NH-(S)-gamma-Caa-gammaAbu--OH (1). Similarly, MS(2) of [M--H](-) of 2 produces an abundant [M--H--C(CH(3))(3)OH--CO(2)](-) ion, which is absent for its diastereomeric isomer 1. From this, it can be suggested that MS/MS of N-blocked Boc-protected carbopeptides may be helpful in distinguishing the stereochemistry of the N-terminus Caa. MS(3) of [M + H-Boc + H](+) ions of peptides with a gamma-amino acid (gamma-Caa/gammaAbu) at the N-terminus produces only abundant y(n) (+) ions. On the other hand, characteristic fragmentations involving the peptide backbone (b(n) (+) and y(n) (+)) and the side chain are seen when beta-Caa is at the N-terminus of the peptides. MS(3) of the [M--H--C(CH(3))(3)OH](-) ion of peptides containing gamma-Caa/gammaAbu at the N-terminus gave y(n) (-) and [M--H--C(CH(3))(3)OH--CO(2)](-) ions, whereas the presence of beta-Caa at the N-terminus yielded predominantly [M--H--C(CH(3))(3)OH--HNCO](-). Thus, on the basis of our previous study and that presented here we propose that the fragmentation of these hybrid carbopeptides is highly influenced by the type of carbo amino acid present at the N-terminus. PMID:18837002

  13. Microbial fuel cell with improved anode

    DOEpatents

    Borole, Abhijeet P.

    2010-04-13

    The present invention relates to a method for preparing a microbial fuel cell, wherein the method includes: (i) inoculating an anodic liquid medium in contact with an anode of the microbial fuel cell with one or more types of microorganisms capable of functioning by an exoelectrogenic mechanism; (ii) establishing a biofilm of the microorganisms on and/or within the anode along with a substantial absence of planktonic forms of the microorganisms by substantial removal of the planktonic microorganisms during forced flow and recirculation conditions of the anodic liquid medium; and (iii) subjecting the microorganisms of the biofilm to a growth stage by incorporating one or more carbon-containing nutritive compounds in the anodic liquid medium during biofilm formation or after biofilm formation on the anode has been established.

  14. Formation of Nanoporous Anodic Alumina by Anodization of Aluminum Films on Glass Substrates.

    PubMed

    Lebyedyeva, Tetyana; Kryvyi, Serhii; Lytvyn, Petro; Skoryk, Mykola; Shpylovyy, Pavlo

    2016-12-01

    Our research was aimed at the study of aluminum films and porous anodic alumina (PAA) films in thin-film РАА/Al structures for optical sensors, based on metal-clad waveguides (MCWG). The results of the scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies of the structure of Al films, deposited by DC magnetron sputtering, and of PAA films, formed on them, are presented in this work.The study showed that the structure of the Al films is defined by the deposition rate of aluminum and the thickness of the film. We saw that under anodization in 0.3 M aqueous oxalic acid solution at a voltage of 40 V, the PAA film with a disordered array of pores was formed on aluminum films 200-600 nm thick, which were deposited on glass substrates with an ultra-thin adhesive Nb layer. The research revealed the formation of two differently sized types of pores. The first type of pores is formed on the grain boundaries of aluminum film, and the pores are directed perpendicularly to the surface of aluminum. The second type of pores is formed directly on the grains of aluminum. They are directed perpendicularly to the grain plains. There is a clear tendency to self-ordering in this type of pores. PMID:27083584

  15. Process for forming sulfuric acid

    DOEpatents

    Lu, Wen-Tong P.

    1981-01-01

    An improved electrode is disclosed for the anode in a sulfur cycle hydrogen generation process where sulfur dioxie is oxidized to form sulfuric acid at the anode. The active compound in the electrode is palladium, palladium oxide, an alloy of palladium, or a mixture thereof. The active compound may be deposited on a porous, stable, conductive substrate.

  16. Controlling interferometric properties of nanoporous anodic aluminium oxide

    NASA Astrophysics Data System (ADS)

    Kumeria, Tushar; Losic, Dusan

    2012-01-01

    A study of reflective interference spectroscopy [RIfS] properties of nanoporous anodic aluminium oxide [AAO] with the aim to develop a reliable substrate for label-free optical biosensing is presented. The influence of structural parameters of AAO including pore diameters, inter-pore distance, pore length, and surface modification by deposition of Au, Ag, Cr, Pt, Ni, and TiO2 on the RIfS signal (Fabry-Perot fringe) was explored. AAO with controlled pore dimensions was prepared by electrochemical anodization of aluminium using 0.3 M oxalic acid at different voltages (30 to 70 V) and anodization times (10 to 60 min). Results show the strong influence of pore structures and surface modifications on the interference signal and indicate the importance of optimisation of AAO pore structures for RIfS sensing. The pore length/pore diameter aspect ratio of AAO was identified as a suitable parameter to tune interferometric properties of AAO. Finally, the application of AAO with optimised pore structures for sensing of a surface binding reaction of alkanethiols (mercaptoundecanoic acid) on gold surface is demonstrated.

  17. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    SciTech Connect

    Abe Fetterman, Yevgeny Raitses, and Michael Keidar

    2008-04-08

    The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

  18. Fast anodization fabrication of AAO and barrier perforation process on ITO glass.

    PubMed

    Liu, Sida; Xiong, Zuzhou; Zhu, Changqing; Li, Ma; Zheng, Maojun; Shen, Wenzhong

    2014-01-01

    Thin films of porous anodic aluminum oxide (AAO) on tin-doped indium oxide (ITO) substrates were fabricated through evaporation of a 1,000- to 2,000-nm-thick Al, followed by anodization with different durations, electrolytes, and pore widening. A faster method to obtain AAO on ITO substrates has been developed, which with 2.5 vol.% phosphoric acid at a voltage of 195 V at 269 K. It was found that the height of AAO films increased initially and then decreased with the increase of the anodizing time. Especially, the barrier layers can be removed by extending the anodizing duration, which is very useful for obtaining perforation AAO and will broaden the application of AAO on ITO substrates. PMID:24708829

  19. The adsorption of α-cyanoacrylic acid on anatase TiO2 (101) and (001) surfaces: A density functional theory study

    NASA Astrophysics Data System (ADS)

    Ma, Jin-Gang; Zhang, Cai-Rong; Gong, Ji-Jun; Yang, Bing; Zhang, Hai-Min; Wang, Wei; Wu, You-Zhi; Chen, Yu-Hong; Chen, Hong-Shan

    2014-12-01

    The adsorption of α-cyanoacrylic acid (CAA) on anatase TiO2 (101) and (001) surfaces, including adsorption energies, structures, and electronic properties, have been studied by means of density functional theory calculations in connection with ultrasoft pseudopotential and generalized gradient approximation based upon slab models. The most stable structure of CAA on anatase TiO2 (101) surface is the dissociated bidentate configuration where the cyano N and carbonyl O bond with two adjacent surface Ti atoms along [010] direction and the dissociated H binds to the surface bridging O which connects the surface Ti bonded with carbonyl O. While for the adsorption of CAA on (001) surface, the most stable structure is the bidentate configuration through the dissociation of hydroxyl in carboxyl moiety. The O atoms of carboxyl bond with two neighbor surface Ti along [100] direction, and the H from dissociated hydroxyl interacts with surface bridging O, generating OH species. The adsorption energies are estimated to be 1.02 and 3.25 eV for (101) and (001) surfaces, respectively. The analysis of density of states not only suggests the bonds between CAA and TiO2 surfaces are formed but also indicates that CAA adsorptions on TiO2 (101) and (001) surfaces provide feasible mode for photo-induced electron injection through the interface between TiO2 and CAA. This is resulted from that, compared with the contribution of CAA orbitals in valence bands, the conduction bands which are mainly composed of Ti 3d orbitals have remarkable reduction of the component of CAA orbitals.

  20. The adsorption of α-cyanoacrylic acid on anatase TiO{sub 2} (101) and (001) surfaces: A density functional theory study

    SciTech Connect

    Ma, Jin-Gang; Gong, Ji-Jun; Zhang, Hai-Min; Wang, Wei; Zhang, Cai-Rong Chen, Yu-Hong; Yang, Bing; Wu, You-Zhi; Chen, Hong-Shan

    2014-12-21

    The adsorption of α-cyanoacrylic acid (CAA) on anatase TiO{sub 2} (101) and (001) surfaces, including adsorption energies, structures, and electronic properties, have been studied by means of density functional theory calculations in connection with ultrasoft pseudopotential and generalized gradient approximation based upon slab models. The most stable structure of CAA on anatase TiO{sub 2} (101) surface is the dissociated bidentate configuration where the cyano N and carbonyl O bond with two adjacent surface Ti atoms along [010] direction and the dissociated H binds to the surface bridging O which connects the surface Ti bonded with carbonyl O. While for the adsorption of CAA on (001) surface, the most stable structure is the bidentate configuration through the dissociation of hydroxyl in carboxyl moiety. The O atoms of carboxyl bond with two neighbor surface Ti along [100] direction, and the H from dissociated hydroxyl interacts with surface bridging O, generating OH species. The adsorption energies are estimated to be 1.02 and 3.25 eV for (101) and (001) surfaces, respectively. The analysis of density of states not only suggests the bonds between CAA and TiO{sub 2} surfaces are formed but also indicates that CAA adsorptions on TiO{sub 2} (101) and (001) surfaces provide feasible mode for photo-induced electron injection through the interface between TiO{sub 2} and CAA. This is resulted from that, compared with the contribution of CAA orbitals in valence bands, the conduction bands which are mainly composed of Ti 3d orbitals have remarkable reduction of the component of CAA orbitals.

  1. Reduced adhesion of macrophages on anodized titanium with select nanotube surface features

    PubMed Central

    Rajyalakshmi, Amancherla; Ercan, Batur; Balasubramanian, K; Webster, Thomas J

    2011-01-01

    One of the important prerequisites for a successful orthopedic implant apart from being osteoconductive is the elicitation of a favorable immune response that does not lead to the rejection of the implant by the host tissue. Anodization is one of the simplest surface modification processes used to create nanotextured and nanotubular features on metal oxides which has been shown to improve bone formation. Anodization of titanium (Ti) leads to the formation of TiO2 nanotubes on the surface, and the presence of these nanotubes mimics the natural nanoscale features of bone, which in turn contributes to improved bone cell attachment, migration, and proliferation. However, inflammatory cell responses on anodized Ti remains to be tested. It is hypothesized that surface roughness and surface feature size on anodized Ti can be carefully manipulated to control immune cell (specifically, macrophages) responses. Here, when Ti samples were anodized at 10 V in the presence of 1% hydrofluoric acid (HF) for 1 minute, nanotextured (nonnanotube) surfaces were created. When anodization of Ti samples was carried out with 1% HF for 10 minutes at 15 V, nanotubes with 40–50 nm diameters were formed, whereas at 20 V with 1% HF for 10 minutes, nanotubes with 60–70 nm diameters were formed. In this study, a reduced density of macrophages was observed after 24 hours of culture on nanotextured and nanotubular Ti samples which were anodized at 10, 15, and 20 V, compared with conventional unmodified Ti samples. This in vitro study thus demonstrated a reduced density of macrophages on anodized Ti, thereby providing further evidence of the greater efficacy of anodized Ti for orthopedic applications. PMID:21980239

  2. Fabrication of the superhydrophobic surface on aluminum alloy by anodizing and polymeric coating

    NASA Astrophysics Data System (ADS)

    Liu, Wenyong; Luo, Yuting; Sun, Linyu; Wu, Ruomei; Jiang, Haiyun; Liu, Yuejun

    2013-01-01

    We reported the preparation of the superhydrophobic surface on aluminum alloy via anodizing and polymeric coating. Both the different anodizing processes and different polymeric coatings of aluminum alloy were investigated. The effects of different anodizing conditions, such as electrolyte concentration, anodization time and current on the superhydrophobic surface were discussed. The results showed that a good superhydrophobic surface was facilely fabricated by polypropylene (PP) coating after anodizing. The optimum conditions for anodizing were determined by orthogonal experiments. When the concentration of oxalic acid was 10 g/L, the concentration of NaCl was 1.25 g/L, anodization time was 40 min, and anodization current was 0.4 A, the best superhydrophobic surface on aluminum alloy with the contact angle (CA) of 162° and the sliding angle of 2° was obtained. On the other hand, the different polymeric coatings, such as polystyrene (PS), polypropylene (PP) and polypropylene grafting maleic anhydride (PP-g-MAH) were used to coat the aluminum alloy surface after anodizing. The results showed that the superhydrophobicity was most excellent by coating PP, while the duration of the hydrophobic surface was poor. By modifying the surface with the silane coupling agent before PP coating, the duration of the superhydrophobic surface was improved. The morphologies of the superhydrophobic surface were further confirmed by optical microscope (OM) and scanning electron microscope (SEM). Combined with the material of PP with the low surface free energy, the micro/nano-structures of the surface resulted in the superhydrophobicity of the aluminum alloy surface.

  3. Use of a hydrogen anode for nitrate waste destruction

    SciTech Connect

    Kalu, E.E.; White, R.E.; Hobbs, D.T.

    1996-10-01

    Processes are being evaluated to separate the high-level radioactive species from the waste and store them permanently in the form of durable solids. The remaining low-level radioactive waste contains species such as nitrites and nitrates that are capable of contaminating ground water. The use of a hydrogen gas-fed anode and an acid analyte in an electrochemical cell used to destroy nitrate is demonstrated. A mixed Na{sub 2}SO{sub 4}/H{sub 2}SO{sub 4} anolyte is shown to favor nitrate cell performance and the generation of a higher hydroxide ion concentration in the catholyte. The suggested scheme is an apparent method of sodium sulfate disposal and a possible means through which ammonia (to ammonium sulfate, fertilizer) and hydrogen gas could be recycled through the anode side of the reactor. This could result in a substantial savings in the operation of a nitrate destruction cell.

  4. Metallic anodes for next generation secondary batteries.

    PubMed

    Kim, Hansu; Jeong, Goojin; Kim, Young-Ugk; Kim, Jae-Hun; Park, Cheol-Min; Sohn, Hun-Joon

    2013-12-01

    Li-air(O2) and Li-S batteries have gained much attention recently and most relevant research has aimed to improve the electrochemical performance of air(O2) or sulfur cathode materials. However, many technical problems associated with the Li metal anode have yet to be overcome. This review mainly focuses on the electrochemical behaviors and technical issues related to metallic Li anode materials as well as other metallic anode materials such as alkali (Na) and alkaline earth (Mg) metals, including Zn and Al when these metal anodes were employed for various types of secondary batteries.

  5. Anode composite for molten carbonate fuel cell

    DOEpatents

    Iacovangelo, Charles D.; Zarnoch, Kenneth P.

    1983-01-01

    An anode composite useful for a molten carbonate fuel cell comprised of a porous sintered metallic anode component having a porous bubble pressure barrier integrally sintered to one face thereof, said barrier being comprised of metal coated ceramic particles sintered together and to said anode by means of said metal coating, said metal coating enveloping said ceramic particle and being selected from the group consisting of nickel, copper and alloys thereof, the median pore size of the barrier being significantly smaller than that of the anode.

  6. A Mutational Analysis of the Active Site Loop Residues in cis-3-Chloroacrylic Acid Dehalogenase

    PubMed Central

    Schroeder, Gottfried K.; Huddleston, Jamison P.; Johnson, William H.; Whitman, Christian P.

    2013-01-01

    cis -3-Chloroacrylic acid dehalogenase (cis-CaaD) from Pseudomonas pavonaceae 170 and a homologue from Corynebacterium glutamicum designated Cg10062 share 34% sequence identity (54% similarity). The former catalyzes a key step in a bacterial catabolic pathway for the nematocide 1,3-dichloropropene, whereas the latter has no known biological activity. Although Cg10062 has the six active site residues (Pro-1, His-28, Arg-70, Arg-73, Tyr-103, Glu-114) that are critical for cis-CaaD activity, it shows only a low level cis-CaaD activity and lacks the specificity of cis-CaaD: Cg10062 processes both isomers of 3-chloroacrylate with a preference for the cis-isomer. Although the basis for these differences is unknown, a comparison of the crystal structures of the enzymes covalently modified by an adduct resulting from their incubation with the same inhibitor offers a possible explanation. A 6-residue active site loop in cis-CaaD shows a strikingly different conformation from that observed in Cg10062: the loop closes down on the active site of cis-CaaD, but not on that of Cg10062. In order to examine what this loop might contribute to cis-CaaD catalysis and specificity, the residues were changed individually to those found in Cg10062. Subsequent kinetic and mechanistic analysis suggests that the T34A mutant of cis-CaaD is more Cg10062-like. The mutant enzyme shows a 4-fold increase in Km (using cis-3-bromoacrylate), but not to the degree observed for Cg10062 (687-fold). The mutation also causes a 4-fold decrease in the burst rate (compared to the wild type cis-CaaD), whereas Cg10062 shows no burst rate. More telling is the reaction of the T34A mutant of cis-CaaD with the alternate substrate, 2,3-butadienoate. In the presence of NaBH4 and the allene, cis-CaaD is completely inactivated after one turnover due to the covalent modification of Pro-1. The same experiment with Cg10062 does not result in the covalent modification of Pro-1. The different outcomes are attributed to

  7. Electrochemical incineration of diclofenac in neutral aqueous medium by anodic oxidation using Pt and boron-doped diamond anodes.

    PubMed

    Brillas, Enric; Garcia-Segura, Sergi; Skoumal, Marcel; Arias, Conchita

    2010-04-01

    The degradation of diclofenac, a common non-steroidal anti-inflammatory drug, in aqueous medium has been studied by anodic oxidation (AO) using an undivided cell with a Pt or boron-doped diamond (BDD) anode. Operating without pH regulation, AO with Pt acidifies the solution with precipitation of its protonated form, whereas using BDD, the solution becomes alkaline and only attains partial mineralization. Total incineration of low contents of the drug is feasible by AO with BDD in a neutral buffer medium of pH 6.5. Comparative treatment with Pt gives poor decontamination. The diclofenac decay always follows a pseudo first-order reaction. The increase in current for AO with BDD accelerates the degradative process, but decreases its efficiency. 2-Hydroxyphenylacetic acid, 2,5-dihydroxyphenylacetic acid, 2,6-dichloroaniline and 2,6-dichlorohydroquinone have been identified as aromatic intermediates. For AO with Pt, high amounts of malic, succinic, tartaric and oxalic acids are accumulated in the bulk and the N-derivatives produced are rapidly destroyed with loss of NH4+. When BDD is employed, some carboxylic acids are also accumulated in small extent, with a larger persistence of oxalic and oxamic acids. The process involves the formation of different N-derivatives that slowly release NH4+ and NO3(-) ions. Chloride ion is lost in all cases.

  8. Gaseous Refining of Anode Copper

    NASA Astrophysics Data System (ADS)

    Goyal, Pradeep; Themelis, N. J.; Zanchuk, Walter A.

    1982-12-01

    The refining of blister copper prior to casting into anodes consists of oxidizing the copper melt to remove sulfur and then reducing its oxygen content. The age-old "wood poling" technique for deoxidation is gradually being replaced by the injection of reducing gases through one or two tuyeres. Thermodynamic and mass transfer analysis as well as laboratory tests have shown that the operating efficiency of gas injection can be improved considerably by enhancing mixing and gas-liquid mass transfer conditions within the copper bath. The injection of inert gas through porous plugs offers a viable industrial means for effecting such an improvement.

  9. Characterization of the complete mitochondrial genome of the Grey-backed Shrike, Lanius tephronotus (Aves: Passeriformes): the first representative of the family Laniidae with a novel CAA stop codon at the end of cox2 gene.

    PubMed

    Qian, Chaoju; Yan, Xia; Guo, Zhichun; Wang, Yuanxiu; Li, Xixi; Yang, Jianke; Kan, Xianzhao

    2013-08-01

    The complete Grey-backed Shrike mitochondrial genome has been sequenced to be 16,820 bp in length, consisting of 37 encode genes: 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. In addition, a single control region was also observed. Compared with other reported Passeriformes mtgenome sequences, three bases CAA were detected at the end of Lanius tephronotus cox2 gene with the downstream adjacent base T. The first base of CAA probably occurred C to U transcript editing event resulting in a normal stop codon UAA.

  10. Anodization process produces opaque, reflective coatings on aluminum

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Opaque, reflective coatings are produced on aluminum articles by an anodizing process wherein the anodizing bath contains an aqueous dispersion of finely divided insoluble inorganic compounds. These particles appear as uniformly distributed occlusions in the anodic deposit on the aluminum.

  11. Overcoming Geometry-Induced Stiffness with IMplicit-Explicit (IMEX) Runge-Kutta Algorithms on Unstructured Grids with Applications to CEM, CFD, and CAA

    NASA Technical Reports Server (NTRS)

    Kanevsky, Alex

    2004-01-01

    My goal is to develop and implement efficient, accurate, and robust Implicit-Explicit Runge-Kutta (IMEX RK) methods [9] for overcoming geometry-induced stiffness with applications to computational electromagnetics (CEM), computational fluid dynamics (CFD) and computational aeroacoustics (CAA). IMEX algorithms solve the non-stiff portions of the domain using explicit methods, and isolate and solve the more expensive stiff portions using implicit methods. Current algorithms in CEM can only simulate purely harmonic (up to lOGHz plane wave) EM scattering by fighter aircraft, which are assumed to be pure metallic shells, and cannot handle the inclusion of coatings, penetration into and radiation out of the aircraft. Efficient MEX RK methods could potentially increase current CEM capabilities by 1-2 orders of magnitude, allowing scientists and engineers to attack more challenging and realistic problems.

  12. Formic acid fuel cells and catalysts

    DOEpatents

    Masel, Richard I.; Larsen, Robert; Ha, Su Yun

    2010-06-22

    An exemplary fuel cell of the invention includes a formic acid fuel solution in communication with an anode (12, 134), an oxidizer in communication with a cathode (16, 135) electrically linked to the anode, and an anode catalyst that includes Pd. An exemplary formic acid fuel cell membrane electrode assembly (130) includes a proton-conducting membrane (131) having opposing first (132) and second surfaces (133), a cathode catalyst on the second membrane surface, and an anode catalyst including Pd on the first surface.

  13. An oxygen pumping anode for electrowinning aluminium.

    PubMed

    Liu, Changqing; Ji, Xiaobo; Zhang, Pingmin; Chen, Qiyuan; Banks, Craig E

    2013-05-01

    The chemical potential of oxygen ions at the novel oxygen pumping anode for electrowinning aluminum was manipulated by the electromotive forces to create thermodynamic stability. It is our anticipation that this newly designed anode can be applied to electrochemical metallurgy of other metals, such as the direct electrochemical reduction of TiO2 in the FFC process. PMID:23519386

  14. Remote control for anode-cathode adjustment

    DOEpatents

    Roose, Lars D.

    1991-01-01

    An apparatus for remotely adjusting the anode-cathode gap in a pulse power machine has an electric motor located within a hollow cathode inside the vacuum chamber of the pulse power machine. Input information for controlling the motor for adjusting the anode-cathode gap is fed into the apparatus using optical waveguides. The motor, controlled by the input information, drives a worm gear that moves a cathode tip. When the motor drives in one rotational direction, the cathode is moved toward the anode and the size of the anode-cathode gap is diminished. When the motor drives in the other direction, the cathode is moved away from the anode and the size of the anode-cathode gap is increased. The motor is powered by batteries housed in the hollow cathode. The batteries may be rechargeable, and they may be recharged by a photovoltaic cell in combination with an optical waveguide that receives recharging energy from outside the hollow cathode. Alternatively, the anode-cathode gap can be remotely adjusted by a manually-turned handle connected to mechanical linkage which is connected to a jack assembly. The jack assembly converts rotational motion of the handle and mechanical linkage to linear motion of the cathode moving toward or away from the anode.

  15. Anode power deposition in a MPD thruster with a magnetically annulled Hall parameter anode

    NASA Technical Reports Server (NTRS)

    Gallimore, Alec D.; Kelly, Arnold J.; Jahn, Robert G.

    1992-01-01

    Results from previous studies indicate that the anode fall increases monotonically with the electron Hall parameter. In an attempt to reduce the anode fall by decreasing the local electron Hall parameter, a proof-of-concept test was performed in which an array of 36 permanent magnets were imbedded within the anode of a high power quasi-steady MPD thruster to decrease the local azimuthal component of the induced magnetic field. The modified thruster was operated at power levels between 150 kW and 4 MW with Ar and He propellants. Terminal voltage, triple probe, floating probe, and magnetic probe measurements were made to characterize the performance of the thruster with new anode. Incorporation of the modified anode resulted in a reduction of the anode fall by up to 15 V with Ar and 20 V with He, which corresponded to decreased anode power fractions of 40 and 45 percent with Ar and He, respectively.

  16. Antioxidant Activity and α-Glucosidase Inhibitory Activities of the Polycondensate of Catechin with Glyoxylic Acid

    PubMed Central

    Ma, Hanjun; Liu, Benguo

    2016-01-01

    In order to investigate polymeric flavonoids, the polycondensate of catechin with glyoxylic acid (PCG) was prepared and its chemically antioxidant, cellular antioxidant (CAA) and α-glucosidase inhibitory activities were evaluated. The DPPH and ABTS radical scavenging activities and antiproliferative effect of PCG were lower than those of catechin, while PCG had higher CAA activity than catechin. In addition, PCG had very high α-glucosidase inhibitory activities (IC50 value, 2.59 μg/mL) in comparison to catechin (IC50 value, 239.27 μg/mL). Inhibition kinetics suggested that both PCG and catechin demonstrated a mixture of noncompetitive and anticompetitive inhibition. The enhanced CAA and α-glucosidase inhibitor activities of PCG could be due to catechin polymerization enhancing the binding capacity to the cellular membrane and enzymes. PMID:26960205

  17. One hundred anode microchannel plate ion detector

    SciTech Connect

    He Yi; Poehlman, John F.; Alexander, Andrew W.; Boraas, Kirk; Reilly, James P.

    2011-08-15

    A one-hundred-anode microchannel plate detector is constructed on a 10 cm x 15 cm printed circuit board and attached to a homebuilt matrix assisted laser desorption ionization (MALDI) time-of-flight mass spectrometer. Ringing and cross talk between anodes have been successfully eliminated and preliminary mass spectra of peptide ions recorded. With one hundred anodes on the printed circuit board, spatial information about the ion beam can also be readily determined with this detector. During operation, the detector anode assembly loses sensitivity after ions strike it for a considerable period of time due to charging of the non-conductive regions between anodes. However, this effect can be minimized by deflecting matrix ions away from the detector.

  18. The effects of the oral administration of fish oil concentrate on the release and the metabolism of (/sup 14/C)arachidonic acid and (/sup 14/C)eicosapentaenoic acid by human platelets

    SciTech Connect

    Hirai, A.; Terano, T.; Hamazaki, T.; Sajiki, J.; Kondo, S.; Ozawa, A.; Fujita, T.; Miyamoto, T.; Tamura, Y.; Kumagai, A.

    1982-11-01

    It has been suggested by several investigators that eicosapentaenoic acid (C20:5 omega 3, EPA) might have anti-thrombotic effects. In this experiment, the effect of the oral administration of EPA rich fish oil concentrate on platelet aggregation and the release and the metabolism of (/sup 1 -14/C)arachidonic acid and ((U)-/sup 14/C)eicosapentaenoic acid by human platelets was studied. Eight healthy male subjects ingested 18 capsules of fish oil concentrate (EPA 1.4 g) per day for 4 weeks. Plasma and platelet concentrations of EPA markedly increased, while those of arachidonic acid (C20:4 omega 6, AA) and docosahexaenoic acid (C22:6 omega 3, DHA) did not change. Platelet aggregation induced by collagen and ADP was reduced. Collagen induced (/sup 14/C)thromboxane B2 (TXB2) formation from (/sup 14/C)AA prelabeled platelets decreased. There was no detectable formation of (/sup 14/C)TXB3 from (/sup 14/C)EPA prelabeled platelets, and the conversion of exogenous (/sup 14/C)EPA to (/sup 14/C)TXB3 was lower than that of (/sup 14/C)AA to (/sup 14/C)TXB2. The release of (/sup 14/C)AA from (/sup 14/C)AA prelabeled platelets by collagen was significantly decreased. These observations raise the possibility that the release of arachidonic acid from platelet lipids might be affected by the alteration of EPA content in platelets.

  19. Polymer nanoimprinting using an anodized aluminum mold for structural coloration

    NASA Astrophysics Data System (ADS)

    Kikuchi, Tatsuya; Nishinaga, Osamu; Natsui, Shungo; Suzuki, Ryosuke O.

    2015-06-01

    Polymer nanoimprinting of submicrometer-scale dimple arrays with structural coloration was demonstrated. Highly ordered aluminum dimple arrays measuring 530-670 nm in diameter were formed on an aluminum substrate via etidronic acid anodizing at 210-270 V and subsequent anodic oxide dissolution. The nanostructured aluminum surface led to bright structural coloration with a rainbow spectrum, and the reflected wavelength strongly depends on the angle of the specimen and the period of the dimple array. The reflection peak shifts gradually with the dimple diameter toward longer wavelength, reaching 800 nm in wavelength at 670 nm in diameter. The shape of the aluminum dimple arrays were successfully transferred to a mercapto-ester ultra-violet curable polymer via self-assembled monolayer coating and polymer replications using a nanoimprinting technique. The nanostructured polymer surfaces with positively and negatively shaped dimple arrays also exhibited structural coloration based on the periodic nanostructure, and reflected light mostly in the visible region, 400-800 nm. This nanostructuring with structural coloration can be easily realized by simple techniques such as anodizing, SAM coating, and nanoimprinting.

  20. Pulse electrodeposition of adherent nickel coatings onto anodized aluminium surfaces

    NASA Astrophysics Data System (ADS)

    Frantz, Cédric; Vichery, Charlotte; Zechner, Johannes; Frey, Damian; Bürki, Gerhard; Cebeci, Halil; Michler, Johann; Philippe, Laetitia

    2015-03-01

    Aluminium is one of the mostly used elements in the industry because of its abundance and low weight. However, the deposition of a metallic coating requires performing the so-called zincate pre-treatment in order to allow the formation of inter-metallic bonds and thereby achieving sufficient adherence. In this work, porous anodic aluminium oxide (AAO) is used as an anchoring intermediate layer for nickel coatings. AAO is grown anodically in sulfuric acid and nickel coatings are deposited by potentiostatic reverse pulse electrodeposition onto as-anodized aluminium surfaces. The electrodeposition of nickel is initiated onto the electrochemically thinned barrier layer of AAO and pursued until the complete covering of the oxide. The electrochemical behavior of Watts and sulfamate baths is investigated by cyclic voltammetry for different barrier layer thickness, allowing to validate the thinning conditions and to determine the appropriate deposition potential of nickel. GD-OES measurements show that low duty cycles are necessary to achieve high filling ratio of the AAO. SEM micrographs show that a smooth uniform coating is obtained when nickel is deposited in presence of additives.

  1. Parasitic Currents Caused by Different Ionic and Electronic Conductivities in Fuel Cell Anodes.

    PubMed

    Schalenbach, Maximilian; Zillgitt, Marcel; Maier, Wiebke; Stolten, Detlef

    2015-07-29

    The electrodes in fuel cells simultaneously realize electric and ionic conductivity. In the case of acidic polymer electrolytes, the electrodes are typically made of composites of carbon-supported catalyst and Nafion polymer electrolyte binder. In this study, the interaction of the proton conduction, the electron conduction, and the electrochemical hydrogen conversion in such composite electrode materials was examined. Exposed to a hydrogen atmosphere, these composites displayed up to 10-fold smaller resistivities for the proton conduction than that of Nafion membranes. This effect was ascribed to the simultaneously occurring electrochemical hydrogen oxidation and evolution inside the composite samples, which are driven by different proton and electron resistivities. The parasitic electrochemical currents resulting were postulated to occur in the anode of fuel cells with polymer, solid oxide, or liquid alkaline electrolytes, when the ohmic drop of the ion conduction in the anode is higher with the anodic kinetic overvoltage (as illustrated in the graphical abstract). In this case, the parasitic electrochemical currents increase the anodic kinetic overpotential and the ohmic drop in the anode. Thinner fuel cell anodes with smaller ohmic drops for the ion conduction may reduce the parasitic electrochemical currents.

  2. Characterization of Raw and Decopperized Anode Slimes from a Chilean Refinery

    NASA Astrophysics Data System (ADS)

    Melo Aguilera, Evelyn; Hernández Vera, María Cecilia; Viñals, Joan; Graber Seguel, Teófilo

    2016-04-01

    This work characterizes raw and decopperized slimes, with the objective of identifying the phases in these two sub-products. The main phases in copper anodes are metallic copper, including CuO, which are present in free form or associated with the presence of copper selenide or tellurides (Cu2(Se,Te)) and several Cu-Pb-Sb-As-Bi oxides. During electrorefining, the impurities in the anode release and are not deposited in the cathode, part of them dissolving and concentrated in the electrolyte, and others form a raw anode slime that contains Au, Ag, Cu, As, Se, Te and PGM, depending on the composition of the anode. There are several recovery processes, most of which involve acid leaching in the first step to dissolve copper, whose product is decopperized anode slime. SEM analysis revealed that the mineralogical species present in the raw anode slime under study were mainly eucarite (CuAgSe), naumannite (Ag2Se), antimony arsenate (SbAsO4), and lead sulfate (PbSO4). In the case of decopperized slime, the particles were mainly composed of SbAsO4 (crystalline appearance), non-stoichiometric silver selenide (Ag(2- x)Se), and chlorargyrite (AgCl).

  3. Alternative anodic reactions in water splitting. Final report

    SciTech Connect

    Murphy, O.J.; Bockris, J. O'M.

    1984-10-01

    An anodic depolarization path to hydrogen production through water electrolysis has been examined, using lignite, grass and household wastes. Iron was removed from lignite by extensive washing. The degree of dissolution of lignite in 5 M H/sub 2/So/sub 4/ at 100/sup 0/C is ca. 0.1 wt %. Washed lignite dissolves less than unwashed material. Cyclic voltammograms showed peaks arising from dissolved organics. Increase of temperature produced more peaks. In alkaline solution, peaks disappeared. Oxidation currents were three times greater if the lignite particles were in contact with the electrode compared with their absence from solution. Platinum anodes oxidized lignite better than PbO/sub 2/. Redox systems, added to the electrolyte, helped compound formation. Grass and household wastes gave similar results but lower oxidation currents. Compounds present in solution prior to electrolysis dissolve off the internal surfaces of lignite particles. Increased oxidation currents, caused when lignite particles came in contact with the anode, arose, not because of enhanced electrochemical reactions, but from enhanced lignite dissolution following erosion. The organic compounds eventually form CO/sub 2/; the presence of heavy oils lasts for 10 hr. Current densities up to 750 mA cm/sup -2/ at ca. 1 V should be obtainable. The hydrocarbons are formed via a Kolbe mechanism from carboxylic acids. Speculative economic considerations show that the final cost of hydrogen produced, using lignite as an anode depolarizer, is considerably cheaper than that from natural gas: $0.40 per GJ, or less, compared to $5 per GJ.

  4. The Nitrogen-Nitride Anode.

    SciTech Connect

    Delnick, Frank M.

    2014-10-01

    Nitrogen gas N 2 can be reduced to nitride N -3 in molten LiCl-KCl eutectic salt electrolyte. However, the direct oxidation of N -3 back to N 2 is kinetically slow and only occurs at high overvoltage. The overvoltage for N -3 oxidation can be eliminated by coordinating the N -3 with BN to form the dinitridoborate (BN 2 -3 ) anion which forms a 1-D conjugated linear inorganic polymer with -Li-N-B-N- repeating units. This polymer precipitates out of solution as Li 3 BN 2 which becomes a metallic conductor upon delithiation. Li 3 BN 2 is oxidized to Li + + N 2 + BN at about the N 2 /N -3 redox potential with very little overvoltage. In this report we evaluate the N 2 /N -3 redox couple as a battery anode for energy storage.

  5. Using Heteropolyacids in the Anode Catalyst Layer of Dimethyl Ether PEM Fuel Cells

    SciTech Connect

    Ferrell III, J. R.; Turner, J. A.; Herring, A. M.

    2008-01-01

    In this study, polarization experiments were performed on a direct dimethyl ether fuel cell (DMEFC). The experimental setup allowed for independent control of water and DME flow rates. Thus the DME flow rate, backpressure, and water flow rate were optimized. Three heteropoly acids, phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and silicotungstic acid (STA) were incorporated into the anode catalyst layer in combination with Pt/C. Both PTA-Pt and STA-Pt showed higher performance than the Pt control at 30 psig of backpressure. Anodic polarizations were also performed, and Tafel slopes were extracted from the data. The trends in the Tafel slope values are in agreement with the polarization data. The addition of phosphotungstic acid more than doubled the power density of the fuel cell, compared to the Pt control.

  6. Electrochemical surface modification of carbon mesh anode to improve the performance of air-cathode microbial fuel cells.

    PubMed

    Luo, Jianmei; Chi, Meiling; Wang, Hongyu; He, Huanhuan; Zhou, Minghua

    2013-12-01

    A convenient and promising alternative to surface modification of carbon mesh anode was fulfilled by electrochemical oxidation in the electrolyte of nitric acid or ammonium nitrate at ambient temperature. It was confirmed that such an anode modification method was low cost and effective not only in improving the efficiency of power generation in microbial fuel cells (MFCs) for synthetic wastewater treatment, but also helping to reduce the period for MFCs start-up. The MFCs with anode modification in electrolyte of nitric acid performed the best, achieving a Coulombic efficiency enhancement of 71 %. As characterized, the electrochemical modification resulted in the decrease of the anode potential and internal resistance but the increase of current response and nitrogen-containing and oxygen-containing functional groups on the carbon surface, which might contribute to the enhancement on the performances of MFCs.

  7. Conductive Anodic Filament (CAF) Formation

    NASA Astrophysics Data System (ADS)

    Caputo, Antonio

    Conductive anodic filament (CAF) is a failure mode in printed wiring boards (PWBs) which occurs under high humidity and high voltage gradient conditions. The filament, a copper salt, grows from anode to cathode along the epoxy-glass interface. Ready and Turbini (2000) identified this copper salt as the Cu 2(OH)3Cl, atacamite compound. This work has investigated the influence of polyethylene glycol (PEG) and polyethylene propylene glycol (PEPG) fluxing agents on the chemical nature of CAF. For coupons processed with PEPG flux, with and without chloride, a copper-chloride containing compound was formed in the polymer matrix. This compound was characterized using x-ray photoelectron spectroscopy (XPS) as CuCl and an electrochemical mechanism for the formation of the chloride-containing CAF has been proposed. For PEG flux, with and without chloride, it has been shown that CAF only formed, but no copper containing compound formed in the matrix. It appears for PEG fluxed coupons, a PEG-Cu-Cl complex forms, binds the available Cu and acts as a barrier to the formation of CuCl in the polymer matrix. Meeker and Lu Valle (1995) have previously proposed that CAF failure is best represented by two competing reactions -- the formation of a copper chloride corrosion compound (now identified as Cu2(OH)3Cl) and the formation of innocuous trapped chlorine compounds. Since no evidence of any trapped chloride compounds has been found, we propose that the formation of CAF is best represented by a single non-reversible reaction. For coupons processed with a high bromide-containing flux, bromide containing CAF was created and characterized using transmission electron microscopy (TEM) to be Cu2(OH)3Br. In addition, a copper-containing compound was formed in the polymer matrix and characterized using XPS as CuBr. An electrochemical mechanism for the formation of bromide-containing CAF has been proposed based on the XPS data.

  8. Carbons for battery anodes prepared using inorganic templates

    SciTech Connect

    Winans, R.E.; Carrado, K.A.; Sandi, G.

    1997-07-01

    Unique carbons with demonstrated utility as anodes for lithium secondary batteries have been prepared by heating hydrocarbons within an inorganic template. Disordered carbons with novel and desirable molecular porosity were synthesized by the pyrolysis of pyrene at 700 C within a pillared clay. The clay was removed by treatment with acid, leaving behind carbons with 15 to 50 {angstrom} holes. These holey carbons, when converted into electrodes, allow rapid diffusion of the lithium into and out of a carbon. Favorable results have been obtained in several tests, for example, a reversible capacity of 825 mAh/g has been achieved, about four times greater than commercial batteries using convention pyrolytic carbon.

  9. Nanopore gradients on porous aluminum oxide generated by nonuniform anodization of aluminum.

    PubMed

    Kant, Krishna; Low, Suet P; Marshal, Asif; Shapter, Joseph G; Losic, Dusan

    2010-12-01

    A method for surface engineering of structural gradients with nanopore topography using the self-ordering process based on electrochemical anodization of aluminum is described. A distinct anodization condition with an asymmetrically distributed electric field at the electrolyte/aluminum interface is created by nonparallel arrangement between electrodes (tilted by 45°) in an electrochemical cell. The anodic aluminum oxide (AAO) porous surfaces with ordered nanopore structures with gradual and continuous change of pore diameters from 80 to 300 nm across an area of 0.5-1 cm were fabricated by this anodization using two common electrolytes, oxalic acid (0.3 M) and phosphoric acid (0.3 M). The formation of pore gradients of AAO is explained by asymmetric and gradual distribution of the current density and temperature variation generated on the surface of Al during the anodization process. Optical and wetting gradients of prepared pore structures were confirmed by reflective interferometric spectroscopy and contact angle measurements showing the ability of this method to generate porous surfaces with multifunctional gradients (structural, optical, wetting). The study of influence of pore structures on cell growth using the culture of neuroblastoma cells reveals biological relevance of nanopore gradients and the potential to be applied as the platform for spatially controllable cell growth and cell differentiation.

  10. Anode materials for electrochemical waste destruction

    NASA Technical Reports Server (NTRS)

    Molton, Peter M.; Clarke, Clayton

    1990-01-01

    Electrochemical Oxidation (ECO) offers promise as a low-temperature, atmospheric pressure method for safe destruction of hazardous organic chemical wastes in water. Anode materials tend to suffer corrosion in the intensely oxidizing environment of the ECO cell. There is a need for cheaper, more resistant materials. In this experiment, a system is described for testing anode materials, with examples of several common anodes such as stainless steel, graphite, and platinized titanium. The ECO system is simple and safe to operate and the experiment can easily be expanded in scope to study the effects of different solutions, temperatures, and organic materials.

  11. Effect of selenium and vitamin E deficiencies on the fate of arachidonic acid in rat isolated lungs

    SciTech Connect

    Uotila, P.; Puustinen, T.

    1985-06-01

    The fate of exogenous /sup 14/C-arachidonic acid (/sup 14/C-AA) was investigated in the isolated lungs of rats fed selenium and vitamin E deficient diet or diets supplemented with selenium and/or vitamin E. When 80 nmol of /sup 14/C-AA was infused into the pulmonary circulation most of the infused /sup 14/C-AA was found in different phospholipid and neutral lipid fractions of the perfused lungs. Only less than ten percent of the infused radioactivity was recovered in the perfusion effluent. The amount of arachidonate metabolites in the perfusion effluent was negligible, and most of the radioactivity in the perfusion effluent consisted of unmetabolized arachidonate. Selenium deficiency had no significant effect on the distribution of /sup 14/C-AA in different lung lipid fractions. However, in the lungs of vitamin E deficient rats the amount of radioactivity was slightly increased in the neutral lipid fraction, which was due to the increased amount of /sup 14/C-AA in the diacylglycerols. The amount of radioactivity was increased especially in the 1,3-diacylglycerols. The amount of radioactivity was increased especially in the 1,3-diacylglycerols. The amount of /sup 14/C-AA in the triacylglycerols and in different phospholipids was not significantly changed. The present study might indicate that selenium deficiency has no significant effect on the fate of exogenous arachidonic acid in isolated rat lungs, and that vitamin E deficiency would slightly increase the amount of arachidonic acid in the diacylglycerols.

  12. Fabrication, structural characterization and sensing properties of polydiacetylene nanofibers templated from anodized aluminum oxide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polydiacetylene (PDA), a unique conjugated polymer, has shown its potential in the application of chem/bio-sensors and optoelectronics. In this work, we first infiltrated PDA monomer (10, 12-pentacosadiynoic acid, PCDA) melted into the anodized aluminum oxide template, and then illuminated the infil...

  13. Structural and mechanistic analysis of trans-3-chloroacrylic acid dehalogenase activity

    SciTech Connect

    Pegan, Scott D.; Serrano, Hector; Whitman, Christian P.; Mesecar, Andrew D.

    2008-12-01

    The X-ray structure of a noncovalently modified trans-3-chloroacrylic acid dehalogenase with a substrate-homolog acetate bound in the active site has been determined to 1.7 Å resolution. Elucidation of catalytically important water is reported and multiple conformations of the catalytic residue αGlu52 are observed. Trans-3-chloroacrylic acid dehalogenase (CaaD) is a critical enzyme in the trans-1, 3-dichloropropene (DCP) degradation pathway in Pseudomonas pavonaceae 170. This enzyme allows bacteria to use trans-DCP, a common component in commercially produced fumigants, as a carbon source. CaaD specifically catalyzes the fourth step of the pathway by cofactor-independent dehalogenation of a vinyl carbon–halogen bond. Previous studies have reported an X-ray structure of CaaD under acidic conditions with a covalent modification of the catalytic βPro1 residue. Here, the 1.7 Å resolution X-ray structure of CaaD under neutral (pH 6.5) conditions is reported without the presence of the covalent adduct. In this new structure, a substrate-like acetate molecule is bound within the active site in a position analogous to the putative substrate-binding site. Additionally, a catalytically important water molecule was identified, consistent with previously proposed reaction schemes. Finally, flexibility of the catalytically relevant side chain αGlu52 is observed in the structure, supporting its role in the catalytic mechanism.

  14. A review of anode phenomena in vacuum arces

    NASA Astrophysics Data System (ADS)

    Miller, H. Craig

    1988-09-01

    This report discusses arc modes at the anode, experimental results pertinent to anode phenomena, and theoretical explanations of anode phenomena. The dominant mechanism controlling the formation of an anode spot appears to depend upon the electrode geometry, the electrode material, and the current waveforms of the particular vacuum arc being considered. In specific experimental conditions, either magnetic constriction in the gap plasma or gross anode melting or local anode evaporation can trigger the transition. However, the most probable explanation of anode spot formation is a combination theory, which considers magnetic constriction in the plasma together with the fluxes of material from the anode and cathode as well as the thermal, electrical, and geometric effects of the anode in analyzing the behavior of the anode and the nearby plasma.

  15. A review of anode phenomena in vacuum arces

    SciTech Connect

    Miller, H.C.

    1988-09-01

    This report discusses arc modes at the anode, experimental results pertinent to anode phenomena, and theoretical explanations of anode phenomena. The dominant mechanism controlling the formation of an anode spot appears to depend upon the electrode geometry, the electrode material, and the current waveforms of the particular vacuum arc being considered. In specific experimental conditions, either magnetic constriction in the gap plasma or gross anode melting or local anode evaporation can trigger the transition. However, the most probable explanation of anode spot formation is a combination theory, which considers magnetic constriction in the plasma together with the fluxes of material from the anode and cathode as well as the thermal, electrical, and geometric effects of the anode in analyzing the behavior of the anode and the nearby plasma. 88 refs., 6 figs., 8 tabs.

  16. Use of Both Anode and Cathode Reactions in Wastewater Treatment

    NASA Astrophysics Data System (ADS)

    Brillas, Enric; Sirés, Ignasi; Cabot, Pere LluíS.

    Here, we describe the fundamentals, laboratory experiments, and environmental applications of indirect electrooxidation methods based on H2O2 electrogeneration such as electro-Fenton, photoelectro-Fenton and peroxicoagulation for the treatment of acidic wastewaters containing toxic and recalcitrant organics. These methods are electrochemical advanced oxidation processes that can be used in divided and undivided electrolytic cells in which pollutants are oxidized by hydroxyl radical (•OH) produced from anode and/or cathode reactions. H2O2 is generated from the two-electron reduction of O2 at reticulated vitreous carbon, graphite, carbon-felt, and O2-diffusion cathodes. The most usual method is electro-Fenton where Fe2 + added to the wastewater reacts with electrogenerated H2O2 to yield •OH and Fe3 + from Fenton's reaction. An advantage of this technique is that Fe2 + is continuously regenerated from cathodic reduction of Fe3 +. The characteristics of different electro-Fenton systems where pollutants are simultaneously destroyed by •OH formed in the medium from Fenton's reaction and at the anode surface from water oxidation are explained. The effect of the anode [Pt or boron-doped diamond (BDD)] and cathode (carbon-felt or O2-diffusion) on the degradation rate of persistent industrial by-products, herbicides, pharmaceuticals, dyes, etc. is examined. Initial pollutants react much more rapidly with •OH formed in the medium and their degradation sequences are discussed from aromatic intermediates and finally short aliphatic acids are detected. The synergetic positive catalytic effect of Cu2 + on the electro-Fenton process is evidenced. The photoelectro-Fenton method involves the irradiation of the wastewater with UVA light that rapidly photodecomposes complexes of Fe3 + with final carboxylic acids enhancing total decontamination. The peroxicoagulation method uses a sacrificial Fe anode that is continuously oxidized to Fe2 + and organics are either mineralized

  17. Effects of anode material on arcjet performance

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.; Curran, Frank M.; Larson, C. A.

    1992-01-01

    Anodes fabricated from four different materials were tested in a modular arcjet thruster at 1 kW power level on nitrogen/hydrogen mixtures. A two-percent thoriated tungsten anode served as the control. Graphite was chosen for its ease in fabrication, but experienced severe erosion in the constrictor and diverging side. Hafnium carbide and lanthanum hexaboride were chosen for their low work functions but failed due to thermal stress and reacted with the propellant. When compared to the thoriated tungsten nozzle, thruster performance was significantly lower for the lanthanum hexaboride insert and the graphite nozzle, but was slightly higher for the hafnium carbide nozzle. Both the lanthanum hexaboride and hafnium carbide nozzle operated at higher voltages. An attempt was made to duplicate higher performance hafnium carbide results, but repeated attempts at machining a second anode insert were unsuccessful. Graphite, hafnium carbide, and lanthanum hexaboride do not appear viable anode materials for low power arcjet thrusters.

  18. Pilot demonstration of cerium oxide coated anodes

    SciTech Connect

    Gregg, J.S.; Frederick, M.S.; Shingler, M.J.; Alcorn, T.R.

    1992-10-01

    Cu cermet anodes were tested for 213 to 614 hours with an in-situ deposited CEROX coating in a pilot cell operated by Reynolds Manufacturing Technology Laboratory. At high bath ratio ([approximately]1.5) and low current density (0.5 A/cm[sup 2]), a [ge]1 mm thick dense CEROX coating was deposited on the anodes. At lower bath ratios and higher current density, the CEROX coating was thinner and less dense, but no change in corrosion rate was noted. Regions of low current density on the anodes and sides adjacent to the carbon anode sometimes had thin or absent CEROX coatings. Problems with cracking and oxidation of the cermet substrates led to higher corrosion rates in a pilot cell than would be anticipated from lab scale results.

  19. Metal assisted anodic etching of silicon.

    PubMed

    Lai, Chang Quan; Zheng, Wen; Choi, W K; Thompson, Carl V

    2015-07-01

    Metal assisted anodic etching (MAAE) of Si in HF, without H2O2, is demonstrated. Si wafers were coated with Au films, and the Au films were patterned with an array of holes. A Pt mesh was used as the cathode while the anodic contact was made through either the patterned Au film or the back side of the Si wafer. Experiments were carried out on P-type, N-type, P(+)-type and N(+)-type Si wafers and a wide range of nanostructure morphologies were observed, including solid Si nanowires, porous Si nanowires, a porous Si layer without Si nanowires, and porous Si nanowires on a thick porous Si layer. Formation of wires was the result of selective etching at the Au-Si interface. It was found that when the anodic contact was made through P-type or P(+)-type Si, regular anodic etching due to electronic hole injection leads to formation of porous silicon simultaneously with metal assisted anodic etching. When the anodic contact was made through N-type or N(+)-type Si, generation of electronic holes through processes such as impact ionization and tunnelling-assisted surface generation were required for etching. In addition, it was found that metal assisted anodic etching of Si with the anodic contact made through the patterned Au film essentially reproduces the phenomenology of metal assisted chemical etching (MACE), in which holes are generated through metal assisted reduction of H2O2 rather than current flow. These results clarify the linked roles of electrical and chemical processes that occur during electrochemical etching of Si. PMID:26059556

  20. Current-less anodization of intrinsic silicon powder grains: Formation of fluorescent Si nanoparticles

    NASA Astrophysics Data System (ADS)

    Nielsen, D.; Abuhassan, L.; Alchihabi, M.; Al-Muhanna, A.; Host, Jon; Nayfeh, M. H.

    2007-06-01

    We examine current-less anodization of Si powder grains which are dispersed in a liquid. The grains are prepared red luminescent using a platinum catalyst from a chloroplatinic acid precursor. We also use the procedure to form dispersions of fluorescent Si nanoparticles in the size range of 3-6 nm across by subsequent sonication of the grains. The results are discussed in terms of the calculated thickness of the depletion layer in the grains due to a light metal doping and compared with recent results for the anodization of wirelike geometry.

  1. Fibrous zinc anodes for high power batteries

    NASA Astrophysics Data System (ADS)

    Zhang, X. Gregory

    This paper introduces newly developed solid zinc anodes using fibrous material for high power applications in alkaline and large size zinc-air battery systems. The improved performance of the anodes in these two battery systems is demonstrated. The possibilities for control of electrode porosity and for anode/battery design using fibrous materials are discussed in light of experimental data. Because of its mechanical integrity and connectivity, the fibrous solid anode has good electrical conductivity, mechanical stability, and design flexibility for controlling mass distribution, porosity and effective surface area. Experimental data indicated that alkaline cells made of such anodes can have a larger capacity at high discharging currents than commercially available cells. It showed even greater improvement over commercial cells with a non-conventional cell design. Large capacity anodes for a zinc-air battery have also been made and have shown excellent material utilization at various discharge rates. The zinc-air battery was used to power an electric bicycle and demonstrated good results.

  2. Anode power deposition in applied-field MPD thrusters

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.; Soulas, George C.

    1992-01-01

    Anode power deposition is the principal performance limiter of magnetoplasmadynamic (MPD) thrusters. Current thrusters lose between 50 and 70 percent of the input power to the anode. In this work, anode power deposition was studied for three cylindrical applied magnetic field thrusters for a range of argon propellant flow rates, discharge currents, and applied-field strengths. Between 60 and 95 percent of the anode power depositions resulted from electron current conduction into the anode, with cathode radiation depositing between 5 and 35 percent of the anode power, and convective heat transfer from the hot plasma accounting for less than 5 percent. While the fractional anode power loss decreased with increasing applied-field strength and anode size, the magnitude of the anode power increased. The rise in anode power resulted from a linear rise in the anode fall voltage with applied-field strength and anode radius. The anode fall voltage also rose with decreasing propellant flow rate. The trends indicate that the anode fall region is magnetized, and suggest techniques for reducing the anode power loss in MPD thrusters.

  3. Anode power deposition in applied-field MPD thrusters

    NASA Technical Reports Server (NTRS)

    Myers, Roger M.; Soulas, George C.

    1992-01-01

    Anode power deposition is the principle performance limiter of magnetoplasmadynamic (MPD) thrusters. Current thrusters lose between 50 and 70 percent of the input power to the anode. In this work, anode power deposition was studied for three cylindrical applied magnetic field thrusters for a range of argon propellant flow rates, discharge currents, and applied-field strengths. Between 60 and 95 percent of the anode power deposition resulted from electron current conduction into the anode, with cathode radiation depositing between 5 and 35 percent of the anode power, and convective heat transfer from the hot plasma accounting for less than 5 percent. While the fractional anode power loss decreased with increasing applied-field strength and anode size, the magnitude of the anode power increased. The rise in anode power resulted from a linear rise in the anode fall voltage with applied-field strength and anode radius. The anode fall voltage also rose with decreasing propellant flow rate. The trends indicate that the anode fall region is magnetized, and suggest techniques for reducing the anode power loss in MPD thrusters.

  4. A Standard Analysis Method (SAM) for the automated analysis of polychlorinated biphenyls (PCBs) in soils using the chemical analysis automation (CAA) paradigm: Validation and performance

    SciTech Connect

    Rzeszutko, C.; Johnson, C.R.; Monagle, M.; Klatt, L.N.

    1997-11-01

    The Chemical Analysis Automation (CAA) program is developing a standardized modular automation strategy for chemical analysis. In this automation concept, analytical chemistry is performed with modular building blocks that correspond to individual elements of the steps in the analytical process. With a standardized set of behaviors and interactions, these blocks can be assembled in a plug-and-play manner into a complete analysis system. These building blocks, which are referred to as Standard laboratory Modules (SLM), interface to a host control system that orchestrates the entire analytical process, from sample preparation through data interpretation. The integrated system is called a Standard Analysis Method (SAM). A SAM for the automated determination of polychlorinated biphenyls (PCBs) in soils, assembled in a mobile laboratory, is undergoing extensive testing and validation. The SAM consists of the following SLMs: a four-channel Soxhlet extractor, a high-volume concentration, a column clean-up, a gas chromatography, a PCB data-interpretation module, a robot, and a human-computer interface. The SAM is configured to meet the requirements specified in the US Environmental Protection Agency`s (EPA) SW-846 methods 3541/3620A/8082 for the analysis of PCBs in soils. The PCB SAM will be described along with the developmental test plan. Performance data obtained during developmental testing will also be discussed.

  5. A standard analysis method (SAM) for the automated analysis of polychlorinated biphenyls (PCBs) in soils using the chemical analysis automation (CAA) paradigm: validation and performance

    SciTech Connect

    Rzeszutko, C.; Johnson, C.R.; Monagle, M.; Klatt, L.N.

    1997-10-01

    The Chemical Analysis Automation (CAA) program is developing a standardized modular automation strategy for chemical analysis. In this automation concept, analytical chemistry is performed with modular building blocks that correspond to individual elements of the steps in the analytical process. With a standardized set of behaviors and interactions, these blocks can be assembled in a `plug and play` manner into a complete analysis system. These building blocks, which are referred to as Standard Laboratory Modules (SLM), interface to a host control system that orchestrates the entire analytical process, from sample preparation through data interpretation. The integrated system is called a Standard Analysis Method (SAME). A SAME for the automated determination of Polychlorinated Biphenyls (PCB) in soils, assembled in a mobile laboratory, is undergoing extensive testing and validation. The SAME consists of the following SLMs: a four channel Soxhlet extractor, a High Volume Concentrator, column clean up, a gas chromatograph, a PCB data interpretation module, a robot, and a human- computer interface. The SAME is configured to meet the requirements specified in U.S. Environmental Protection Agency`s (EPA) SW-846 Methods 3541/3620A/8082 for the analysis of pcbs in soils. The PCB SAME will be described along with the developmental test plan. Performance data obtained during developmental testing will also be discussed.

  6. Electrophoretic deposition of PTFE particles on porous anodic aluminum oxide film and its tribological properties

    NASA Astrophysics Data System (ADS)

    Zhang, Dongya; Dong, Guangneng; Chen, Yinjuan; Zeng, Qunfeng

    2014-01-01

    Polytetrafluoroethylene (PTFE) composite film was successfully fabricated by depositing PTFE particles into porous anodic aluminum oxide film using electrophoretic deposition (EPD) process. Firstly, porous anodic aluminum oxide film was synthesized by anodic oxidation process in sulphuric acid electrolyte. Then, PTFE particles in suspension were directionally deposited into the porous substrate. Finally, a heat treatment at 300 °C for 1 h was utilized to enhance PTFE particles adhesion to the substrate. The influence of anodic oxidation parameters on the morphology and micro-hardness of the porous anodic aluminum oxide film was studied and the PTFE particles deposited into the pores were authenticated using energy-dispersive spectrometer (EDS) and scanning electron microscopy (SEM). Tribological properties of the PTFE composite film were investigated under dry sliding. The experimental results showed that the composite film exhibit remarkable low friction. The composite film had friction coefficient of 0.20 which deposited in 15% PTFE emulsion at temperature of 15 °C and current density of 3 A/dm2 for 35 min. In addition, a control specimen of porous anodic aluminum oxide film and the PTFE composite film were carried out under the same test condition, friction coefficient of the PTFE composite film was reduced by 60% comparing with the control specimen at 380 MPa and 100 mm/s. The lubricating mechanism was that PTFE particles embedded in porous anodic aluminum oxide film smeared a transfer film on the sliding path and the micro-pores could support the supplement of solid lubricant during the sliding, which prolonged the lubrication life of the aluminum alloys.

  7. PEO of pre-anodized Al-Si alloys: Corrosion properties and influence of sealings

    NASA Astrophysics Data System (ADS)

    Mohedano, M.; Matykina, E.; Arrabal, R.; Mingo, B.; Pardo, A.

    2015-08-01

    Voltage-controlled PEO coatings were developed on A356 aluminum alloys (gravity-cast and rheocast) with a pre-anodized layer. The influence of the alloy manufacturing process and the effect of Si-rich phase on the structure and composition of the oxide layers were evaluated using SEM, EDS and XRD. The pre-anodized oxide layer preserves the microstructure of the substrate due to the presence of secondary phases that have a different behavior relative to the matrix during anodizing. PEO coatings consisted of a mixture of α-Al2O3, γ-Al2O3 and mullite. The corrosion behavior and the effectiveness of different sealing techniques based on salts of nickel, cobalt, cerium and phosphonic acid were also studied. Post-treatments improved the hydrophobic properties of the coatings and showed a beneficial effect, significantly increasing the coating impedance and thereby reducing the susceptibility to corrosion.

  8. Method for providing uranium articles with a corrosion resistant anodized coating

    DOEpatents

    Waldrop, Forrest B.; Washington, Charles A.

    1982-01-01

    Uranium articles are provided with anodized oxide coatings in an aqueous solution of an electrolyte selected from the group consisting of potassium phosphate, potassium hydroxide, ammonium hydroxide, and a mixture of potassium tetraborate and boric acid. The uranium articles are anodized at a temperature greater than about 75.degree. C. with a current flow of less than about 0.036 A/cm.sup.2 of surface area while the pH of the solution is maintained in a range of about 2 to 11.5. The pH values of the aqueous solution and the low current density utilized during the electrolysis prevent excessive dissolution of the uranium and porosity in the film or watering. The relatively high temperature of the electrolyte bath inhibits hydration and the attendant deleterious pitting so as to enhance corrosion resistance of the anodized coating.

  9. Method for providing uranium articles with a corrosion-resistant anodized coating

    DOEpatents

    Waldrop, F.B.; Washington, C.A.

    1981-01-07

    Uranium articles are provided with anodized oxide coatings in an aqueous solution of an electrolyte selected from the group consisting of potassium phosphate, potassium hydroxide, ammonium hydroxide, and a mixture of potassium tetraborate and boric acid. The uranium articles are anodized at a temperature greater than about 75/sup 0/C with a current flow of less than about 0.036 A/cm/sup 2/ of surface area while the pH of the solution is maintained in a range of about 2 to 11.5. The pH values of the aqueous solution and the low current density utilized during the electrolysis prevent excessive dissolution of the uranium and porosity in the film or watering. The relatively high temperature of the electrolyte bath inhibits hydration and the attendant deleterious pitting so as to enhance corrosion resistance of the anodized coating.

  10. Structural and mechanistic analysis of trans-3-chloroacrylic acid dehalogenase activity

    SciTech Connect

    Pegan, Scott D.; Serrano, Hector; Whitman, Christian P.; Mesecar, Andrew D.

    2009-03-04

    Trans-3-chloroacrylic acid dehalogenase (CaaD) is a critical enzyme in the trans-1,3-dichloropropene (DCP) degradation pathway in Pseudomonas pavonaceae 170. This enzyme allows bacteria to use trans-DCP, a common component in commercially produced fumigants, as a carbon source. CaaD specifically catalyzes the fourth step of the pathway by cofactor-independent dehalogenation of a vinyl carbon-halogen bond. Previous studies have reported an X-ray structure of CaaD under acidic conditions with a covalent modification of the catalytic {beta}Pro1 residue. Here, the 1.7 {angstrom} resolution X-ray structure of CaaD under neutral (pH 6.5) conditions is reported without the presence of the covalent adduct. In this new structure, a substrate-like acetate molecule is bound within the active site in a position analogous to the putative substrate-binding site. Additionally, a catalytically important water molecule was identified, consistent with previously proposed reaction schemes. Finally, flexibility of the catalytically relevant side chain {alpha}Glu52 is observed in the structure, supporting its role in the catalytic mechanism.

  11. Electrospun titania-based fibers for high areal capacity Li-ion battery anodes

    NASA Astrophysics Data System (ADS)

    Self, Ethan C.; Wycisk, Ryszard; Pintauro, Peter N.

    2015-05-01

    Electrospinning is utilized to prepare composite fiber Li-ion battery anodes containing titania and carbon nanoparticles with a poly (acrylic acid) binder. The electrospun material exhibits a stable charge/discharge capacity with only 5% capacity fade over 450 cycles at 0.5 C. Compared to a conventional slurry cast electrode of the same composition, the electrospun anode demonstrates 4-fold higher capacity retention (31% vs. 7.9%) at a charge/discharge rate of 5 C. Electrospinning is also used to prepare ultrathick anodes (>1 mm) with areal capacities up to 3.9 mAh cm-2. Notably, the thick electrodes exhibit areal capacities of 2.5 and 1.3 mAh cm-2 at 1 C and 2 C, respectively. Electrospun anodes with densely packed fibers have a 2 C volumetric capacity which exceeds that of the slurry cast material (21.2 and 17.5 mAh cm-3, respectively). The excellent performance of the electrospun anodes is attributed to interfiber voids which provide complete electrolyte intrusion, a large electrode/electrolyte interface, and short Li+ transport pathways between the electrolyte and titania nanoparticles.

  12. Advanced image analysis of the surface pattern emerging in Ni3Al intermetallic alloys on anodization

    NASA Astrophysics Data System (ADS)

    Salerno, Marco; Stępniowski, Wojciech; Cieślak, Grzegorz; Norek, Małgorzata; Michalska-Domańska, Marta; Karczewski, Krzysztof; Chilimoniuk, Paulina; Polkowski, Wojciech; Jóźwik, Paweł; Bojar, Zbigniew

    2016-07-01

    Anodization of Ni3Al alloy is of interest in the field of industrial manufacturing, thanks to the formation of protective oxide layer on the materials working in corrosive environments and high temperatures. However, homogeneous surface treatment is paramount for technological applications of this material. The anodization conditions have to be set outside the ranges of corrosion and “burning”, which is the electric field enhanced anodic dissolution of the metal. In order to check against occurrence of these events, proper quantitative means for assessing the surface quality have to be developed and established. We approached this task by advanced analysis of scanning electron microscope images of anodized Ni3Al plates. The anodization was carried out in 0.3 M citric acid at two temperatures of 0 and 30°C and at voltages in the range of 2 12 V. Different figures can be used to characterize the quality of the surface, in terms of uniformity. Here, the concept of regularity ratio spread is used for the first time on surfaces of technological interest. Additionally, the Minkowski parameters have been calculated and their meaning is discussed.

  13. Anode Interactions with Coal Gas Contaminants

    SciTech Connect

    Marina, Olga A.; Coffey, Greg W.; Coyle, Christopher A.; Nguyen, Carolyn D.; Thomsen, Edwin C.; Pederson, Larry R.

    2008-08-13

    This report describes efforts to characterize the interactions nickel anodes with phosphorus in coal gas using three different button cell configurations to emphasize particular degradation modes. Important parameters addressed included contaminant concentration, temperature, reaction time, fuel utilization, and current density. In addition, coupon tests in flow-through and flow-by arrangements were conducted to complement cell tests. The studies have involved extensive electrochemical testing using both dc and ac methods. Post-test analyses to determine the composition and extent of nickel modification are particularly important to understanding reactions that have occurred. This report also provides a thermodynamic assessment of contaminant reactions with nickel in a coal gas environment with regard to alteration phase formation. Contaminants addressed were phosphorus, arsenic, sulfur, selenium, and antimony. Phosphorus was found to interact strongly with nickel and result in extensive alteration phase formation, consistent with expectations based on thermodynamic properties. Even in button cell tests where the fuel utilization was low, phosphorus was found to be nearly completely captured by the nickel anode. For anode-supported cells, an important degradation mode involved loss of electronic percolation, the result of nickel phosphide formation, grain growth, and inducement of micro-fractures within the anode support. Even with excessive anode support conversion, electrochemical degradation rates were often very low. This is attributed to a “shadowing effect,” whereby a dense structure such as current leads prevent phosphorus from reacting with the nickel directly underneath. This effect maintains an electrical pathway to the active interface, and allows the cell to operate with minimal degradation until the anode is essentially completely consumed. In a planar stack, ribs on the interconnect plate would be expected to provide this conductive pathway in the

  14. New High-Energy Nanofiber Anode Materials

    SciTech Connect

    Zhang, Xiangwu; Fedkiw, Peter; Khan, Saad; Huang, Alex; Fan, Jiang

    2013-11-15

    The overall goal of the proposed work was to use electrospinning technology to integrate dissimilar materials (lithium alloy and carbon) into novel composite nanofiber anodes, which simultaneously had high energy density, reduced cost, and improved abuse tolerance. The nanofiber structure allowed the anodes to withstand repeated cycles of expansion and contraction. These composite nanofibers were electrospun into nonwoven fabrics with thickness of 50 μm or more, and then directly used as anodes in a lithium-ion battery. This eliminated the presence of non-active materials (e.g., conducting carbon black and polymer binder) and resulted in high energy and power densities. The nonwoven anode structure also provided a large electrode-electrolyte interface and, hence, high rate capacity and good lowtemperature performance capability. Following are detailed objectives for three proposed project periods. • During the first six months: Obtain anodes capable of initial specific capacities of 650 mAh/g and achieve ~50 full charge/discharge cycles in small laboratory scale cells (50 to 100 mAh) at the 1C rate with less than 20 percent capacity fade; • In the middle of project period: Assemble, cycle, and evaluate 18650 cells using proposed anode materials, and demonstrate practical and useful cycle life (750 cycles of ~70% state of charge swing with less than 20% capacity fade) in 18650 cells with at least twice improvement in the specific capacity than that of conventional graphite electrodes; • At the end of project period: Deliver 18650 cells containing proposed anode materials, and achieve specific capacities greater than 1200 mAh/g and cycle life longer than 5000 cycles of ~70% state of charge swing with less than 20% capacity fade.

  15. Chemical enhancement of metallized zinc anode performance

    SciTech Connect

    Bennett, J.

    1998-12-31

    Galvanic current delivered to reinforced concrete by a metallized zinc anode was studied relative to the humidity of its environment and periodic direct wetting. Current decreased quickly at low humidity to values unlikely to meet accepted cathodic protection criteria, but could be easily restored by direct wetting of the anode. Thirteen chemicals were screened for their ability to enhance galvanic current. Such chemicals, when applied to the exterior surface of the anode, are easily transported by capillary action to the anode-concrete interface where they serve to maintain the interface conductive and the zinc electrochemically active. The most effective chemicals were potassium and lithium bromide, acetate, chloride and nitrate, which increased galvanic current by a factor of 2--15, depending on relative humidity and chloride contamination of the concrete. This new technique is expected to greatly expand the number of concrete structures which can be protected by simple galvanic cathodic protection, The use of lithium-based chemicals together with metallized zinc anode is also proposed for mitigation of existing problems due to ASR. In this case, lithium which prevents or inhibits expansion due to ASR can be readily injected into the concrete. A new process, electrochemical maintenance of concrete (EMC), is also proposed to benefit reinforced concrete structures suffering from chloride-induced corrosion.

  16. Boat electrofishing relative to anode arrangement

    USGS Publications Warehouse

    Miranda, L.E.; Kratochvil, M.

    2008-01-01

    We assessed the effect of boom (i.e., anode) arrangement (a single boom and double booms spaced 1.3, 1.9, and 3.2 m apart) on the characteristics of the electric field formed ahead of an electrofishing boat as well as on fish catch. Anode arrangement affected the lengthwise and crosswise characteristics of the field. As a general rule, rearranging the anodes from a single boom located centrally to a double-boom system with broadly separated anodes shifted the strength of the field outward (away from the center) and forward (away from the boat). The highest voltage gradients occurred when the anodes had the greatest separation. Catch rates varied by boom arrangement, increasing as boom separation increased. Differences in species and length selectivity with respect to boom arrangement were minor. We suggest that the double-boom arrangement with the booms placed about 1.9 m apart (but no more than about 2.5 m) is suitable for most electrofishing applications. ?? Copyright by the American Fisheries Society 2008.

  17. Electrolytic Cell For Production Of Aluminum Employing Planar Anodes.

    DOEpatents

    Barnett, Robert J.; Mezner, Michael B.; Bradford, Donald R

    2004-10-05

    A method of producing aluminum in an electrolytic cell containing alumina dissolved in an electrolyte, the method comprising providing a molten salt electrolyte having alumina dissolved therein in an electrolytic cell. A plurality of anodes and cathodes having planar surfaces are disposed in a generally vertical orientation in the electrolyte, the anodes and cathodes arranged in alternating or interleaving relationship to provide anode planar surfaces disposed opposite cathode planar surfaces, the anode comprised of carbon. Electric current is passed through anodes and through the electrolyte to the cathodes depositing aluminum at the cathodes and forming carbon containing gas at the anodes.

  18. Anode current density distribution in a cusped field thruster

    SciTech Connect

    Wu, Huan Liu, Hui Meng, Yingchao; Zhang, Junyou; Yang, Siyu; Hu, Peng; Chen, Pengbo; Yu, Daren

    2015-12-15

    The cusped field thruster is a new electric propulsion device that is expected to have a non-uniform radial current density at the anode. To further study the anode current density distribution, a multi-annulus anode is designed to directly measure the anode current density for the first time. The anode current density decreases sharply at larger radii; the magnitude of collected current density at the center is far higher compared with the outer annuli. The anode current density non-uniformity does not demonstrate a significant change with varying working conditions.

  19. Caffeic acid improves cell viability and protects against DNA damage: involvement of reactive oxygen species and extracellular signal-regulated kinase

    PubMed Central

    Li, Y.; Chen, L.J.; Jiang, F.; Yang, Y.; Wang, X.X.; Zhang, Z.; Li, Z.; Li, L.

    2015-01-01

    Hormesis is an adaptive response to a variety of oxidative stresses that renders cells resistant to harmful doses of stressing agents. Caffeic acid (CaA) is an important antioxidant that has protective effects against DNA damage caused by reactive oxygen species (ROS). However, whether CaA-induced protection is a hormetic effect remains unknown, as is the molecular mechanism that is involved. We found that a low concentration (10 μM) of CaA increased human liver L-02 cell viability, attenuated hydrogen peroxide (H2O2)-mediated decreases in cell viability, and decreased the extent of H2O2-induced DNA double-strand breaks (DSBs). In L-02 cells exposed to H2O2, CaA treatment reduced ROS levels, which might have played a protective role. CaA also activated the extracellular signal-regulated kinase (ERK) signal pathway in a time-dependent manner. Inhibition of ERK by its inhibitor U0126 or by its specific small interfering RNA (siRNA) blocked the CaA-induced improvement in cell viability and the protective effects against H2O2-mediated DNA damage. This study adds to the understanding of the antioxidant effects of CaA by identifying a novel molecular mechanism of enhanced cell viability and protection against DNA damage. PMID:25831202

  20. Enhanced electrokinetic remediation of lead-contaminated soil by complexing agents and approaching anodes.

    PubMed

    Zhang, Tao; Zou, Hua; Ji, Minhui; Li, Xiaolin; Li, Liqiao; Tang, Tang

    2014-02-01

    Optimizing process parameters that affect the remediation time and power consumption can improve the treatment efficiency of the electrokinetic remediation as well as determine the cost of a remediation action. Lab-scale electrokinetic remediation of Pb-contaminated soils was investigated for the effect of complexant ethylenediaminetetraacetic acid (EDTA) and acetic acid and approaching anode on the removal efficiency of Pb. When EDTA was added to the catholyte, EDTA dissolved insoluble Pb in soils to form soluble Pb-EDTA complexes, increasing Pb mobility and accordingly removal efficiency. The removal efficiency was enhanced from 47.8 to 61.5 % when the EDTA concentration was increased from 0.1 to 0.2 M, showing that EDTA played an important role in remediation. And the migration rate of Pb was increased to 72.3 % when both EDTA and acetic acid were used in the catholyte. The "approaching anode electrokinetic remediation" process in the presence of both EDTA and acetic acid had a higher Pb-removal efficiency with an average efficiency of 83.8 %. The efficiency of electrokinetic remediation was closely related to Pb speciation. Exchangeable and carbonate-bounded Pb were likely the forms which could be removed. All results indicate that the approaching anode method in the presence of EDTA and acetic acid is an advisable choice for electrokinetic remediation of Pb-contaminated soil. PMID:24203258

  1. Microwave processing of tantalum capacitor anodes

    SciTech Connect

    Lauf, R J; Hamby, C; Holcombe, C E; Vierow, W F

    1992-08-01

    Porous tantalum anodes were sintered at temperatures from 1600 to 1900{degrees}C using a conventional high-vacuum furnace as well as both 2.45 GHz fixed-frequency and 4--8 GHz variable-frequency microwave furnaces. Various insulation and casketing techniques were used to couple the microwave power to the tantalum compacts. Several types of tantalum powder were used to assess the effect of microwave processing on sintered surface area and impurity levels. Some microwave sintered anodes have an unusual surface rippling not seen on conventionally fired parts. The rippling suggests that a microscopic arcing or plasma might have been generated. Two important effects could be exploited if this phenomenon can be controlled. First, the effective tantalum surface area could be increased, yielding higher capacitance per volume. Second, surface impurities might be cleaned away, allowing the formation of a better dielectric film during the anodization process and, ultimately, higher working voltage.

  2. Nanocomposite protective coatings for battery anodes

    DOEpatents

    Lemmon, John P; Xiao, Jie; Liu, Jun

    2014-01-21

    Modified surfaces on metal anodes for batteries can help resist formation of malfunction-inducing surface defects. The modification can include application of a protective nanocomposite coating that can inhibit formation of surface defects. such as dendrites, on the anode during charge/discharge cycles. For example, for anodes having a metal (M'), the protective coating can be characterized by products of chemical or electrochemical dissociation of a nanocomposite containing a polymer and an exfoliated compound (M.sub.a'M.sub.b''X.sub.c). The metal, M', comprises Li, Na, or Zn. The exfoliated compound comprises M' among lamella of M.sub.b''X.sub.c, wherein M'' is Fe, Mo, Ta, W, or V, and X is S, O, or Se.

  3. An Insoluble Titanium-Lead Anode for Sulfate Electrolytes

    SciTech Connect

    Ferdman, Alla

    2005-05-11

    The project is devoted to the development of novel insoluble anodes for copper electrowinning and electrolytic manganese dioxide (EMD) production. The anodes are made of titanium-lead composite material produced by techniques of powder metallurgy, compaction of titanium powder, sintering and subsequent lead infiltration. The titanium-lead anode combines beneficial electrochemical behavior of a lead anode with high mechanical properties and corrosion resistance of a titanium anode. In the titanium-lead anode, the titanium stabilizes the lead, preventing it from spalling, and the lead sheathes the titanium, protecting it from passivation. Interconnections between manufacturing process, structure, composition and properties of the titanium-lead composite material were investigated. The material containing 20-30 vol.% of lead had optimal combination of mechanical and electrochemical properties. Optimal process parameters to manufacture the anodes were identified. Prototypes having optimized composition and structure were produced for testing in operating conditions of copper electrowinning and EMD production. Bench-scale, mini-pilot scale and pilot scale tests were performed. The test anodes were of both a plate design and a flow-through cylindrical design. The cylindrical anodes were composed of cylinders containing titanium inner rods and fitting over titanium-lead bushings. The cylindrical design allows the electrolyte to flow through the anode, which enhances diffusion of the electrolyte reactants. The cylindrical anodes demonstrate higher mass transport capabilities and increased electrical efficiency compared to the plate anodes. Copper electrowinning represents the primary target market for the titanium-lead anode. A full-size cylindrical anode performance in copper electrowinning conditions was monitored over a year. The test anode to cathode voltage was stable in the 1.8 to 2.0 volt range. Copper cathode morphology was very smooth and uniform. There was no

  4. Graphene/silicon nanocomposite anode with enhanced electrochemical stability for lithium-ion battery applications

    NASA Astrophysics Data System (ADS)

    Maroni, F.; Raccichini, R.; Birrozzi, A.; Carbonari, G.; Tossici, R.; Croce, F.; Marassi, R.; Nobili, F.

    2014-12-01

    A graphene/silicon nanocomposite has been synthesized, characterized and tested as anode active material for lithium-ion batteries. A morphologically stable composite has been obtained by dispersing silicon nanoparticles in graphene oxide, previously functionalized with low-molecular weight polyacrylic acid, in eco-friendly, low-cost solvent such as ethylene glycol. The use of functionalized graphene oxide as substrate for the dispersion avoids the aggregation of silicon particles during the synthesis and decreases the detrimental effect of graphene layers re-stacking. Microwave irradiation of the suspension, inducing reduction of graphene oxide, and the following thermal annealing of the solid powder obtained by filtration, yield a graphene/silicon composite material with optimized morphology and properties. Composite anodes, prepared with high-molecular weight polyacrylic acid as green binder, exhibited high and stable reversible capacity values, of the order of 1000 mAh g-1, when cycled using vinylene carbonate as electrolyte additive. After 100 cycles at a current of 500 mA g-1, the anode showed a discharge capacity retention of about 80%. The mechanism of reversible lithium uptake is described in terms of Li-Si alloying/dealloying reaction. Comparison of the impedance responses of cells tested in electrolytes with or without vinylene carbonate confirms the beneficial effects of the additive in stabilizing the composite anode.

  5. Efficient processing of reaction-sintered silicon carbide by anodically oxidation-assisted polishing

    NASA Astrophysics Data System (ADS)

    Tu, Qunzhang; Shen, Xinmin; Zhou, Jianzhao; He, Xiaohui; Yamamura, Kazuya

    2015-10-01

    Reaction-sintered silicon carbide (RS-SiC) is a promising optical material for the space telescope systems. Anodically oxidation-assisted polishing is a method to machine RS-SiC. The electrolyte used in this study is a mixture of hydrogen peroxide (H2O2) and hydrochloric acid (HCl), and the oxidation potential has two modes: constant potential and high-frequency-square-wave potential. Oxide morphologies are compared by scanning electron microscope/energy dispersive x-ray spectroscopy and scanning white-light interferometer. The results indicate that anodic oxidation under constant potential can not only obtain a relatively smooth surface but also be propitious to obtain high material removal rate. The oxidation depth in anodic oxidation under constant potential is calculated by comparing surface morphologies before and after hydrofluoric acid etching. The theoretical oxidation rate is 5.3 nm/s based on the linear Deal-Grove model. Polishing of the oxidized RS-SiC is conducted to validate the machinability of the oxide layer. The obtained surface roughness root-mean-square is around 4.5 nm. Thus, anodically oxidation-assisted polishing can be considered as an efficient method, which can fill the performance gap between the rough figuring and fine finishing of RS-SiC. It can improve the machining quality of RS-SiC parts and promote the application of RS-SiC products.

  6. Behaviour of non-standard composition copper bearing anodes from the copper refining process.

    PubMed

    Marković, R; Friedrich, B; Stajić-Trosić, J; Jordović, B; Jugović, B; Gvozdenović, M; Stevanović, J

    2010-10-15

    This paper addresses on investigation the possibility of electrolytic treatment the sulphur acidic waste solution, obtained in the conventional electrolytic copper refining process. Beside the high copper concentration, the high concentration of other metals, in this case nickel, is the main characteristic of these waste solutions. Due to this fact, the copper bearing anodes with non-standard nickel, lead, tin and antimony content were specially prepared for the refining process. Nickel content of all anodes was approximately 7.5 mass%, and the content of lead, tin and antimony was varied. The preliminary results, obtained using the standard electrochemical techniques, have indicated that the copper bearing anodes could be used under the same conditions as well as in the conventional copper refining process. The measurements in constant galvanostatic pulse have pointed out that the all chemical elements from copper bearing anodes were dissolved and only copper was deposited onto the cathode. It was also pointed out that Ni concentration in the base working electrolyte (sulphur acidic waste solution), after 72 h of process, increased to 102 mass% at T(1)=63+/-2 degrees C and up to 122 mass% at T(1)=73+/-2 degrees C, while arsenic concentration decreased to a minimum value. PMID:20667423

  7. Silicon Whisker and Carbon Nanofiber Composite Anode

    NASA Technical Reports Server (NTRS)

    Lang, Christopher M.

    2015-01-01

    Phase II Objectives: Demonstrate production levels of grams per batch; Achieve full cell anode capacity of greater than 1,000 mAh/g at a charge rate of 10 (C/10) and 0 degree C; Establish a full cell cycle life of over 300 cycles; Display an operating temperature of negative 30 degrees C to plus 30 degrees C; Demonstrate a rate capability of C/5 or higher; Deliver to NASA three 2.5 Ah cells (energy density greater than 220 Wh/kg); Exhibit the safety features of the anode and full cells; Design a 1 kWh prismatic battery pack.

  8. Aerogel and xerogel composites for use as carbon anodes

    DOEpatents

    Cooper, John F.; Tillotson, Thomas M.; Hrubesh, Lawrence W.

    2010-10-12

    A method for forming a reinforced rigid anode monolith and fuel and product of such method. The method includes providing a solution of organic aerogel or xerogel precursors including at least one of a phenolic resin, phenol (hydroxybenzene), resorcinol(1,3-dihydroxybenzene), or catechol(1,2-dihydroxybenzene); at least one aldehyde compound selected from the group consisting of formaldehyde, acetaldehyde, and furfuraldehyde; and an alkali carbonate or phosphoric acid catalyst; adding internal reinforcement materials comprising carbon to said precursor solution to form a precursor mixture; gelling said precursor mixture to form a composite gel; drying said composite gel; and pyrolyzing said composite gel to form a wettable aerogel/carbon composite or a wettable xerogel/carbon composite, wherein said composites comprise chars and said internal reinforcement materials, and wherein said composite is suitable for use as an anode with the chars being fuel capable of being combusted in a molten salt electrochemical fuel cell in the range from 500 C to 800 C to produce electrical energy. Additional methods and systems/compositions are also provided.

  9. Hydrogen anode for nitrate waste destruction. Revision 2

    SciTech Connect

    Hobbs, D.T.; Kalu, E.E.; White, R.E.

    1996-02-10

    Large quantities of radioactive and hazardous wastes have been generated from nuclear materials production during the past fifty years. Processes are under evaluation to separate the high level radioactive species from the waste and store them permanently in the form of durable solids. The schemes proposed will separate the high level radioactive components, cesium-137 and strontium-90, into a small volume for incorporation into a glass wasteform. The remaining low-level radioactive waste contain species such as nitrites and nitrates that are capable of contaminating ground water. Electrochemical destruction of the nitrate and nitrite before permanent storage has been proposed. Not only will the electrochemical processing destroy these species, the volume of the waste could also be reduced. The use of a hydrogen gas-fed anode and an acid anolyte in an electrochemical cell used to destroy nitrate was demonstrated. A mixed Na{sub 2}SO{sub 4}/H{sub 2}SO{sub 4} anolyte was shown to favor the nitrate cell performance, and the generation of a higher hydroxide ion concentration in the catholyte. The suggested scheme is an apparent method of sodium sulfate disposal and a possible means through which ammonia (to ammonium sulfate, fertilizer) and hydrogen gas could be recycled through the anode side of the reactor. This could result in a substantial savings in the operation of a nitrate destruction cell.

  10. Fuel cell system shutdown with anode pressure control

    DOEpatents

    Clingerman, Bruce J.; Doan, Tien M.; Keskula, Donald H.

    2002-01-01

    A venting methodology and pressure sensing and vent valving arrangement for monitoring anode bypass valve operating during the normal shutdown of a fuel cell apparatus of the type used in vehicle propulsion systems. During a normal shutdown routine, the pressure differential between the anode inlet and anode outlet is monitored in real time in a period corresponding to the normal closing speed of the anode bypass valve and the pressure differential at the end of the closing cycle of the anode bypass valve is compared to the pressure differential at the beginning of the closing cycle. If the difference in pressure differential at the beginning and end of the anode bypass closing cycle indicates that the anode bypass valve has not properly closed, a system controller switches from a normal shutdown mode to a rapid shutdown mode in which the anode inlet is instantaneously vented by rapid vents.

  11. 4. Anode Building. View is to the east. This facility, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. Anode Building. View is to the east. This facility, which was used for the cleaning and manufacture of anodes, was documented prior to demolition in 1993. - Sullivan Electrolytic Zinc Plant, Government Gulch, Kellogg, Shoshone County, ID

  12. Self-cleaning rotating anode X-ray source

    DOEpatents

    Paulikas, Arvydas P.

    1989-01-01

    A self-cleaning rotating anode x-ray source comprising an evacuable housing, a rotatable cylindrical anode within the housing, a source of electrons within the housing which electrons are caused to impinge upon the anode to produce x-rays, and means for ionizing residual particles within the housing and accelerating such ions so as to impinge upon the anode to sputter impurities from the surface thereof.

  13. Salt passivation during anodic iridium dissolution in chloride melts

    SciTech Connect

    Saltykova, N.A.; Pechorskaya, L.S.; Baraboshkin, A.N.; Kotovskii, S.N.; Kosikhin, L.T.

    1986-11-01

    Anodic iridium dissolution in chloride melts at 500-700/sup 0/C was studied by potentiostatic, potentiodynamic, and galvanostatic techniques. It was found that an iridium anode is passivated by hexachloroiridates, first by the iridium (III) salt and at more positive potentials by the iridium (IV) salt. Values for anode resistance during passivation by salt films were calculated. It was shown that the morphology of the dissolving anode surface is determined by the value of polarization.

  14. Dissipation factor as a predictor of anodic coating performance

    DOEpatents

    Panitz, Janda K. G.

    1995-01-01

    A dissipation factor measurement is used to predict as-anodized fixture performance prior to actual use of the fixture in an etching environment. A dissipation factor measurement of the anodic coating determines its dielectric characteristics and correlates to the performance of the anodic coating in actual use. The ability to predict the performance of the fixture and its anodized coating permits the fixture to be repaired or replaced prior to complete failure.

  15. Self-cleaning rotating anode x-ray source

    DOEpatents

    Paulikas, A.P.

    1987-06-02

    A self-cleaning rotating anode x-ray source comprising and evacuable housing, a rotatable cylindrical anode within the housing, a source of electrons within the housing which electrons are caused to impinge upon the anode to produce x-rays, and means for ionizing residual particles within the housing and accelerating such ions so as to impinge upon the anode to sputter impurities from the surface thereof. 2 figs.

  16. The research of anodic microdischarges in plasma-electrolyte processing

    NASA Astrophysics Data System (ADS)

    Kashapov, L. N.; Kashapov, N. F.; Kashapov, R. N.

    2015-06-01

    The article is devoted to the topic of anodic microdischarges in plasma-electrolyte processing. The aim of this work is to research the conditions of anodic micro-discharges during the plasma-electrolytic treatment and the influence they have on the surface of metals. As a result of experimental researches, was made a mechanism of influence anodic microdischarges on the surface of the electrode, burning of anodic microdischarges occur in the voltage range of 40-100 W.

  17. Polyaniline-Coated Carbon Nanotube Ultrafiltration Membranes: Enhanced Anodic Stability for In Situ Cleaning and Electro-Oxidation Processes.

    PubMed

    Duan, Wenyan; Ronen, Avner; Walker, Sharon; Jassby, David

    2016-08-31

    Electrically conducting membranes (ECMs) have been reported to be efficient in fouling prevention and destruction of aqueous chemical compounds. In the current study, highly conductive and anodically stable composite polyaniline-carbon nanotube (PANI-CNT) ultrafiltration (UF) ECMs were fabricated through a process of electropolymerization of aniline on a CNT substrate under acidic conditions. The resulting PANI-CNT UF ECMs were characterized by scanning electron microscopy, atomic force microscopy, a four-point conductivity probe, cyclic voltammetry, and contact angle goniometry. The utilization of the PANI-CNT material led to significant advantages, including: (1) increased electrical conductivity by nearly an order of magnitude; (2) increased surface hydrophilicity while not impacting membrane selectivity or permeability; and (3) greatly improved stability under anodic conditions. The membrane's anodic stability was evaluated in a pH-controlled aqueous environment under a wide range of anodic potentials using a three-electrode cell. Results indicate a significantly reduced degradation rate in comparison to a CNT-poly(vinyl alcohol) ECM under high anodic potentials. Fouling experiments conducted with bovine serum albumin demonstrated the capacity of the PANI-CNT ECMs for in situ oxidative cleaning, with membrane flux restored to its initial value under an applied potential of 3 V. Additionally, a model organic compound (methylene blue) was electrochemically transformed at high efficiency (90%) in a single pass through the anodically charged ECM. PMID:27525344

  18. Polyaniline-Coated Carbon Nanotube Ultrafiltration Membranes: Enhanced Anodic Stability for In Situ Cleaning and Electro-Oxidation Processes.

    PubMed

    Duan, Wenyan; Ronen, Avner; Walker, Sharon; Jassby, David

    2016-08-31

    Electrically conducting membranes (ECMs) have been reported to be efficient in fouling prevention and destruction of aqueous chemical compounds. In the current study, highly conductive and anodically stable composite polyaniline-carbon nanotube (PANI-CNT) ultrafiltration (UF) ECMs were fabricated through a process of electropolymerization of aniline on a CNT substrate under acidic conditions. The resulting PANI-CNT UF ECMs were characterized by scanning electron microscopy, atomic force microscopy, a four-point conductivity probe, cyclic voltammetry, and contact angle goniometry. The utilization of the PANI-CNT material led to significant advantages, including: (1) increased electrical conductivity by nearly an order of magnitude; (2) increased surface hydrophilicity while not impacting membrane selectivity or permeability; and (3) greatly improved stability under anodic conditions. The membrane's anodic stability was evaluated in a pH-controlled aqueous environment under a wide range of anodic potentials using a three-electrode cell. Results indicate a significantly reduced degradation rate in comparison to a CNT-poly(vinyl alcohol) ECM under high anodic potentials. Fouling experiments conducted with bovine serum albumin demonstrated the capacity of the PANI-CNT ECMs for in situ oxidative cleaning, with membrane flux restored to its initial value under an applied potential of 3 V. Additionally, a model organic compound (methylene blue) was electrochemically transformed at high efficiency (90%) in a single pass through the anodically charged ECM.

  19. Coaxial anode improves sensitivity of gas radiation counters

    NASA Technical Reports Server (NTRS)

    Kraushaar, W. L.

    1974-01-01

    Anode wire itself is enclosed by three segments. Two on ends are rejector segments, and middle one is primary charge-detecting segment. Anode wire is made from tungsten and is surrounded by enamel insulation. Enamel is covered by segments of vapor-deposited gold. At one point in center segment, gold layer makes direct contact with anode wire.

  20. Influence of electropolishing and anodic oxidation on morphology, chemical composition and corrosion resistance of niobium.

    PubMed

    Sowa, Maciej; Greń, Katarzyna; Kukharenko, Andrey I; Korotin, Danila M; Michalska, Joanna; Szyk-Warszyńska, Lilianna; Mosiałek, Michał; Zak, Jerzy; Pamuła, Elżbieta; Kurmaev, Ernst Z; Cholakh, Seif O; Simka, Wojciech

    2014-09-01

    The work presents results of the studies performed on electropolishing of pure niobium in a bath that contained: sulphuric acid, hydrofluoric acid, ethylene glycol and acetanilide. After the electropolishing, the specimens were subjected to anodic passivation in a 1moldm(-3) phosphoric acid solution at various voltages. The surface morphology, thickness, roughness and chemical composition of the resulting oxide layers were analysed. Thusly prepared niobium samples were additionally investigated in terms of their corrosion resistance in Ringer's solution. The electropolished niobium surface was determined to be smooth and lustrous. The anodisation led to the growth of barrier-like oxide layers, which were enriched in phosphorus species.

  1. Influence of electropolishing and anodic oxidation on morphology, chemical composition and corrosion resistance of niobium.

    PubMed

    Sowa, Maciej; Greń, Katarzyna; Kukharenko, Andrey I; Korotin, Danila M; Michalska, Joanna; Szyk-Warszyńska, Lilianna; Mosiałek, Michał; Zak, Jerzy; Pamuła, Elżbieta; Kurmaev, Ernst Z; Cholakh, Seif O; Simka, Wojciech

    2014-09-01

    The work presents results of the studies performed on electropolishing of pure niobium in a bath that contained: sulphuric acid, hydrofluoric acid, ethylene glycol and acetanilide. After the electropolishing, the specimens were subjected to anodic passivation in a 1moldm(-3) phosphoric acid solution at various voltages. The surface morphology, thickness, roughness and chemical composition of the resulting oxide layers were analysed. Thusly prepared niobium samples were additionally investigated in terms of their corrosion resistance in Ringer's solution. The electropolished niobium surface was determined to be smooth and lustrous. The anodisation led to the growth of barrier-like oxide layers, which were enriched in phosphorus species. PMID:25063150

  2. An inert metal anode for magnesium electrowinning

    SciTech Connect

    Moore, J. F.; Hryn, J. N.; Pellin, M. J.; Calaway, W. F.; Watson, K.

    1999-12-01

    Results from the development of a novel type of anode for electrowinning Mg are reported. A tailored alloy system based on the binary Cu-Al can be made to form a thin alumina layer on its surface that is relatively impervious to attack by the molten chloride melt at high temperature. This barrier is thin enough (5--50 nm) to conduct electrical current without significant IR loss. As the layer slowly dissolves, the chemical potential developed at the surface drives the diffusion of aluminum from the bulk alloy to reform (heal) the protective alumina layer. In this way, an anode that generates Cl{sub 2} (melt electrolysis) and O{sub 2} (wet feed hydrolysis) and no chlorocarbons can be realized. Further, the authors expect the rate of loss of the anode to be dramatically less than the coke-derived carbon anodes typically in use for this technology, leading to substantial cost savings and ancillary pollution control by eliminating coke plant emissions, as well as eliminating chlorinated hydrocarbon emissions from Mg electrowinning cells.

  3. Hybrid anode for semiconductor radiation detectors

    DOEpatents

    Yang, Ge; Bolotnikov, Aleksey E; Camarda, Guiseppe; Cui, Yonggang; Hossain, Anwar; Kim, Ki Hyun; James, Ralph B

    2013-11-19

    The present invention relates to a novel hybrid anode configuration for a radiation detector that effectively reduces the edge effect of surface defects on the internal electric field in compound semiconductor detectors by focusing the internal electric field of the detector and redirecting drifting carriers away from the side surfaces of the semiconductor toward the collection electrode(s).

  4. Silicon Whisker and Carbon Nanofiber Composite Anode

    NASA Technical Reports Server (NTRS)

    Ma, Junqing (Inventor); Newman, Aron (Inventor); Lennhoff, John (Inventor)

    2015-01-01

    A carbon nanofiber can have a surface and include at least one crystalline whisker extending from the surface of the carbon nanofiber. A battery anode composition can be formed from a plurality of carbon nanofibers each including a plurality of crystalline whiskers.

  5. Anode for rechargeable ambient temperature lithium cells

    NASA Technical Reports Server (NTRS)

    Huang, Chen-Kuo (Inventor); Surampudi, Subbarao (Inventor); Attia, Alan I. (Inventor); Halpert, Gerald (Inventor)

    1994-01-01

    An ambient room temperature, high density, rechargeable lithium battery includes a Li(x)Mg2Si negative anode which intercalates lithium to form a single crystalline phase when x is up to 1.0 and an amorphous phase when x is from 1 to 2.0. The electrode has good reversibility and mechanical strength after cycling.

  6. Anode materials for lithium-ion batteries

    DOEpatents

    Sunkara, Mahendra Kumar; Meduri, Praveen; Sumanasekera, Gamini

    2014-12-30

    An anode material for lithium-ion batteries is provided that comprises an elongated core structure capable of forming an alloy with lithium; and a plurality of nanostructures placed on a surface of the core structure, with each nanostructure being capable of forming an alloy with lithium and spaced at a predetermined distance from adjacent nanostructures.

  7. Luminescence characteristics of nanoporous anodic alumina annealed at different temperatures

    NASA Astrophysics Data System (ADS)

    Ilin, D. O.; Vokhmintsev, A. S.; Weinstein, I. A.

    2016-09-01

    Anodic aluminum oxide (AAO) membranes with 100 µm thickness were synthesized in oxalic acid solution under constant current density. Grown samples were annealed in 500-1250 °C range for 5 h in air. Average pore diameter was evaluated using quantitative analysis of SEM images and appeared to be within 78-86 nm diapason. It was found there was a broad emission band in the 350-620 nm region of photoluminescence (PL) spectra in amorphous membranes which is attributed to F-type oxygen deficient centers or oxalic ions. It was shown that intensive red emission caused by Cr3+ (696 nm) and Mn4+ (680 nm) impurities dominates in PL of AAO samples with crystalline α- and δ-phases after annealing at 1100-1250 °C temperatures.

  8. Evaluation of AA5052 alloy anode in alkaline electrolyte with organic rare-earth complex additives for aluminium-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, Dapeng; Li, Heshun; Liu, Jie; Zhang, Daquan; Gao, Lixin; Tong, Lin

    2015-10-01

    Behaviours of the AA5052 aluminium alloy anode of the alkaline aluminium-air battery are studied by the hydrogen evolution test, the electrochemical measurements and the surface analysis method. The combination of amino-acid and rare earth as electrolyte additives effectively retards the self-corrosion of AA5052 aluminium alloy in 4 M NaOH solution. It shows that the combination of L-cysteine and cerium nitrate has a synergistic effect owing to the formation of a complex film on AA5052 alloy surface. The organic rare-earth complex can decrease the anodic polarisation, suppress the hydrogen evolution and increase the anodic utilization rate.

  9. Degradation of hydroxycinnamic acid mixtures in aqueous sucrose solutions by the Fenton process.

    PubMed

    Nguyen, Danny M T; Zhang, Zhanying; Doherty, William O S

    2015-02-11

    The degradation efficiencies and behaviors of caffeic acid (CaA), p-coumaric acid (pCoA), and ferulic acid (FeA) in aqueous sucrose solutions containing the mixture of these hydroxycinnamic acids (HCAs) were studied by the Fenton oxidation process. Central composite design and multiresponse surface methodology were used to evaluate and optimize the interactive effects of process parameters. Four quadratic polynomial models were developed for the degradation of each individual acid in the mixture and the total HCAs degraded. Sucrose was the most influential parameter that significantly affected the total amount of HCA degraded. Under the conditions studied there was a <0.01% loss of sucrose in all reactions. The optimal values of the process parameters for a 200 mg/L HCA mixture in water (pH 4.73, 25.15 °C) and sucrose solution (13 mass %, pH 5.39, 35.98 °C) were 77% and 57%, respectively. Regression analysis showed goodness of fit between the experimental results and the predicted values. The degradation behavior of CaA differed from those of pCoA and FeA, where further CaA degradation is observed at increasing sucrose and decreasing solution pH. The differences (established using UV/vis and ATR-FTIR spectroscopy) were because, unlike the other acids, CaA formed a complex with Fe(III) or with Fe(III) hydrogen-bonded to sucrose and coprecipitated with lepidocrocite, an iron oxyhydroxide. PMID:25585639

  10. Degradation of hydroxycinnamic acid mixtures in aqueous sucrose solutions by the Fenton process.

    PubMed

    Nguyen, Danny M T; Zhang, Zhanying; Doherty, William O S

    2015-02-11

    The degradation efficiencies and behaviors of caffeic acid (CaA), p-coumaric acid (pCoA), and ferulic acid (FeA) in aqueous sucrose solutions containing the mixture of these hydroxycinnamic acids (HCAs) were studied by the Fenton oxidation process. Central composite design and multiresponse surface methodology were used to evaluate and optimize the interactive effects of process parameters. Four quadratic polynomial models were developed for the degradation of each individual acid in the mixture and the total HCAs degraded. Sucrose was the most influential parameter that significantly affected the total amount of HCA degraded. Under the conditions studied there was a <0.01% loss of sucrose in all reactions. The optimal values of the process parameters for a 200 mg/L HCA mixture in water (pH 4.73, 25.15 °C) and sucrose solution (13 mass %, pH 5.39, 35.98 °C) were 77% and 57%, respectively. Regression analysis showed goodness of fit between the experimental results and the predicted values. The degradation behavior of CaA differed from those of pCoA and FeA, where further CaA degradation is observed at increasing sucrose and decreasing solution pH. The differences (established using UV/vis and ATR-FTIR spectroscopy) were because, unlike the other acids, CaA formed a complex with Fe(III) or with Fe(III) hydrogen-bonded to sucrose and coprecipitated with lepidocrocite, an iron oxyhydroxide.

  11. Anodic adsorptive stripping voltammetric determination of the anesthetic drug: methohexital sodium.

    PubMed

    Farghaly, O A; El-Wadood, H M; Ghandour, M A

    1999-11-01

    Methohexital (MS) determination is based on the formation of insoluble mercury salt on a hanging mercury drop electrode after preaccumulation by adsorption. This property was exploited in developing a highly sensitive stripping voltammetric procedure for the determination of the drug. The anodic current of adsorbed compound is measured by linear sweep anodic stripping voltammetry (LSASV), preceded by a period of preconcentration. The effect of various parameters such as supporting electrolyte composition, pH, initial potential, scan rate, accumulation time and ionic strength are discussed to characterize the interfacial and redox behavior. The detection limit was found to be 2x10(-7) M (56.8 ppb) with 180-s accumulation time. The interference of some amino acids, ascorbic acid and some metal ions was investigated. The application of this method was tested in the determination of methohexital in spiked urine samples. The precision of the method is satisfactory with a relative standard deviation of 2.5%.

  12. Blockage of TGFβ-SMAD2 by demethylation-activated miR-148a is involved in caffeic acid-induced inhibition of cancer stem cell-like properties in vitro and in vivo

    PubMed Central

    Li, Yuan; Jiang, Fei; Chen, Lijun; Yang, Ye; Cao, Shuyuan; Ye, Yuting; Wang, Xingxing; Mu, Juan; Li, Zhong; Li, Lei

    2015-01-01

    Current standard practices for treatment of cancers are less than satisfactory because of recurrence mediated by cancer stem cells (CSCs). Caffeic acid (CaA) is a novel anti-tumor agent that inhibits proliferation, migration, and invasion in human cancer cells. However, little is known about the functions of CaA in regulating CSCs-like properties and the potential molecular mechanisms. Here, we found that CaA attenuated the CSCs-like properties by the microRNA-148a (miR-148a)-mediated inhibition of transforming growth factor beta (TGFβ)-SMAD2 signaling pathway both in vitro and in vivo. CaA enhanced the expression of miR-148a by inducing DNA methylation. MiR-148a, which targeted the SMAD2-3′UTR, decreased the expression of SMAD2. Knockdown of miR-148a abolished the CaA-induced inhibition of TGFβ-SMAD2 signal pathway and the CSCs-like properties. Our study found a novel mechanism that CaA inhibits the CSCs-like properties via miR-148a-mediated inhibition of TGFβ-SMAD2 signaling pathway, which may help to identify a new approach for the treatment of human cancers. PMID:26106521

  13. Experimental studies of anode sheath phenomena in a hall thruster.

    SciTech Connect

    Dorf, L. A.; Fisch, N. J.; Raitses, Yevgeny F.

    2004-01-01

    Both electron-repelling (negative anode fall) and electron-attracting (positive anode fall) anode sheaths in a Hall thruster were identified experimentally by performing accurate, non-disturbing near-anode measurements with biased and emissive probes. An interesting new phenomenon revealed by the probe measurements is that the anode fall changes from positive to negative upon removal of the dielectric coating, which appears on the anode surface during the course of Hall thruster operation. Probe measurements in a Hall thruster with three different magnetic field configurations show that an anode fall at the clean anode is a function of the radial magnetic field profile inside the channel. A positive anode fall formation mechanism suggested in this work is that: (1) when the anode front surface is coated with dielectric, a discharge current closes to the anode at the surfaces that remain conductive, (2) a total thermal electron current toward the conductive area is significantly smaller than the discharge current, therefore an additional electron flux needs to be attracted toward the conductive surfaces by the electronattracting sheath that appears at these surfaces.

  14. Alternate anode materials for cathodic protection of steel reinforced concrete

    SciTech Connect

    Russell, James H.; Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Holcomb, Gordon R.; Cryer, Curtis B.

    2001-01-01

    Consumable and non-consumable anodes were evaluated in the laboratory for use in cathodic protection (CP) systems for steel reinforced concrete bridges in coastal environments and in areas where deicing salts are employed. The anode materials included Zn-hydrogel and thermal-sprayed Zn, Zn-15Al, Al-12Zn-0.2In, and cobalt-sprayed Ti. These anodes were evaluated for service in both galvanic (GCP) and impressed current (ICCP) cathodic protection systems. Impressed current CP anodes were electrochemically aged at a current density 15 times as great as that used by the Oregon Department of Transportation in typical coastal ICCP systems (2.2 mA/m2 based on anode area). Increasing moisture at the anode-concrete interface reduced the operating voltage of all the anodes. Bond strength between the anodes and concrete decreased with electrochemical aging. The Zn-15Al and Al-12Zn-0.2In anodes provided adequate protection in GCP but their life was too short in the accelerated ICCP tests. Zinc had an adequate life in ICCP tests but was inadequate as a galvanic anode. Zinc-hydrogel performed well in both tests when the hydrogel was kept moist. Titanium was an excellent anode for ICCP, but is not suitable for GCP.

  15. Perovskites for use as sulfur tolerant anodes

    NASA Astrophysics Data System (ADS)

    Howell, Thomas G.

    One of the major obstacles encountered when using solid oxide fuel cells with hydrocarbon fuels is sulfur poisoning. The current anode material used is Ni/YSZ and Ni is not sulfur tolerant; therefore, the performance of the cell will degrade over time due to the formation of NiS. Perovskites have demonstrated superior sulfur tolerance but lack the high conductivity and catalytic activity of Ni/YSZ cermets. One of the objectives of this effort is to explore the substitution of the A-site in an A2MgMoO 6 perovskite with Sr and Ba, to create Sr2MgMoO6 (SMMO) and Ba2MgMoO6 (BMMO), respectively, to improve the sulfur tolerance of solid oxide fuel cells (SOFCs). Sr2MgMoO 6, a double perovskite, has been previously studied and is suggested as a material of interest because of its relatively high conductivity and catalytic potential. Barium has not been previously studied and was selected as the dopant because the ionic radii (1.61 A) resulted in a calculated tolerance factor of 1.036 for BMMO when compared to SMMO, which has an ionic radii of 1.44 A and a calculated tolerance factor of 0.978. The tolerance factor for BaSrMgMoO6, a bi-substituted material synthesized for comparison as an intermediate formulation, was calculated to be 1.00. Another objective is to synthesize and characterize a series of lanthanum (La) doped Sr2MgMoO6 (SMMO) or La doped Sr2MgNbO 6 (SMNO) anode materials, which can be used in combination with electrolytes containing lanthanum to mitigate the effects of lanthanum poisoning in SOFCs. Currently, a La0.4Ce0.6O1.8 (LDC) transition layer is used with many perovskite-based anode materials to prevent La diffusion into the anode from the La0.8Sr0.2Ga0.8Mg 0.2O2.8 (LSGM) electrolyte, which can create a resistive La species that impedes electrochemical performance. To accomplish this, a new class of anode materials was synthesized with the goal of balancing La chemical potential between these neighboring materials. It was hypothesized that by

  16. Methods for determining the degree of baking in anodes

    SciTech Connect

    Hughes, C.P.

    1996-10-01

    Anode baking temperature is recognized as a critical factor in determining anode quality and performance. It is difficult and costly to measure directly and an indirect method, the coke L{sub c} technique, is often used. In this technique, baking temperature is estimated from the average crystallite size in the c direction (L{sub c}) of a coke sample placed in the anode stubhole. The paper details the results of a large statistically designed experimental program in which coke L{sub c} results were compared to anode properties routinely measured by smelters. Anode thermal conductivity and air and carboxy reactivity were found to correlate well with baking temperature. A direct anode L{sub c} measurement technique was also strongly associated with temperature, particularly at high baking temperatures. Recommendations are given on the usefulness and simplicity of traditional anode property measurements for assessing baking temperatures as alternatives to the coke L{sub c} method.

  17. Aluminum anodization in a basic ambient temperature molten salt

    SciTech Connect

    Carlin, R.T.; Osteryoung, R.A. . Dept. of Chemistry)

    1989-05-01

    The authors describe aluminum anodization studied in the basic AlCl/sub 3/:1-methyl-3-ethylimidazolium chloride (ImCl) ambient temperature molten salt (AlCl/sub 3/:ImCl molar ratio ..e..1.0). The anodization process was studied as a function of chloride anion concentration. Two different anodization processes are observed with onset potentials of approximately -1.1 and 0V. The more cathodic anodization involves formation of the tetrachloroaluminate anion and exhibits a limiting current controlled by diffusion of chloride to the electrode surface. The number of chlorides required for each Al anodized was determined to be 4.6 +- 0.4. The more anodic anodization shows no diffusion control. A value for the diffusion coefficient of chloride was obtained which is lower than previously reported; the difference involves using an n value of 1, rather than 2/3. No reduction of the tetrachloroaluminate anion was observed even at elevated temperatures.

  18. Methods for making anodes for lithium ion batteries

    SciTech Connect

    Xu, Wu; Canfield, Nathan L.; Zhang, Ji-Guang; Liu, Wei; Xiao, Jie; Wang, Deyu; Yang, Z. Gary

    2015-05-26

    Methods for making composite anodes, such as macroporous composite anodes, are disclosed. Embodiments of the methods may include forming a tape from a slurry including a substrate metal precursor, an anode active material, a pore-forming agent, a binder, and a solvent. A laminated structure may be prepared from the tape and sintered to produce a porous structure, such as a macroporous structure. The macroporous structure may be heated to reduce a substrate metal precursor and/or anode active material. Macroporous composite anodes formed by some embodiments of the disclosed methods comprise a porous metal and an anode active material, wherein the anode active material is both externally and internally incorporated throughout and on the surface of the macroporous structure.

  19. Electrochemical Characteristics of Tin Oxide-Graphite as Anode Material for Lithium-ion Cells

    NASA Astrophysics Data System (ADS)

    Hasanaly, Siti Munirah

    2010-03-01

    Tin oxide anode materials used in lithium-ion cells experience large volume changes during charging and discharging which cause substantial losses in capacity. In this work, the tin oxide-graphite composite is proposed as an alternative anode material to overcome this problem. The composite was synthesised from a solution of tin chloride dihydrate and graphite powders with citric acid as the chelating agent. In this sol-gel method, a solid phase is formed through a chemical reaction in a liquid phase at moderate temperature. The technique offers several advantages compared to the solid state synthesis technique such as the ability to maintain the homogeneous mixture of precursors during synthesis and to produce small particles. The electrochemical behaviour of the anode material was investigated by means of galvanostatic charge discharge technique. An initial reversible capacity of 748 mAh/g is obtained and nearly 600 mAh/g was retained upon the reaching the fifth cycle. This study shows that the presence of graphite is able to minimise the agglomeration of tin particles that causes large volume changes during cycling, thereby improving cyclability of the anode material.

  20. Polarographic study of hydrogen peroxide anodic current and its application to antioxidant activity determination.

    PubMed

    Sužnjević, Desanka Ž; Pastor, Ferenc T; Gorjanović, Stanislava Ž

    2011-09-15

    Behavior of hydrogen peroxide in alkaline medium has been studied by direct current (DC) polarography with dropping mercury electrode (DME) aiming to apply it in antioxidant (AO) activity determination. Development of a peroxide anodic current having form of a peak, instead of common polarographic wave, has been investigated. As a base for this investigation the interaction of H(2)O(2) with anodically dissolved mercury was followed. Formation of mercury complex [Hg(O(2)H)(OH)] has been confirmed. The relevant experimental conditions, such as temperature, concentration and pH dependence, as well as time stability of hydrogen peroxide anodic current, have been assessed. Development of an AO assay based on decrease of anodic current of hydrogen peroxide in the presence of antioxidants (AOs) has been described. Under optimized working conditions, a series of benzoic acids along with corresponding cinnamate analogues have been tested for hydrogen peroxide scavenging activity. In addition, the assay versatility has been confirmed on various complex samples.

  1. Mineralization of paracetamol in aqueous medium by anodic oxidation with a boron-doped diamond electrode.

    PubMed

    Brillas, Enric; Sirés, Ignasi; Arias, Conchita; Cabot, Pere Lluís; Centellas, Francesc; Rodríguez, Rosa María; Garrido, José Antonio

    2005-01-01

    The degradation of 100ml of solutions with paracetamol (N-(4-hydroxyphenyl)acetamide) up to 1 g l(-1) in the pH range 2.0-12.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a graphite cathode, both of 3-cm2 area, by applying a current of 100, 300 and 450 mA between 25 and 45 degrees C. Complete mineralization is always achieved due to the great concentration of hydroxyl radical (*OH) generated at the BDD surface, with release of NH4+ and NO3- ions. The mineralization rate is pH-independent, increases with increasing applied current and temperature, but decreases when drug concentration raises from 315 mg l(-1). Reversed-phase chromatography revealed a similar complex paracetamol decay in acid and alkaline media. Ion-exclusion chromatography allowed the detection of oxalic and oxamic acids as ultimate carboxylic acids. When the same solutions have been comparatively treated with a Pt anode, a quite poor mineralization is found because of the production of much lower *OH concentration. Under these conditions, the degradation rate is enhanced in alkaline medium and polymerization of intermediates is favored in concentrated solutions. Paracetamol can be completely destroyed with Pt and its kinetics follows a pseudo-first-order reaction with a constant rate independent of pH.

  2. Electrochemical behavior of the boron anode in aqueous solutions

    NASA Technical Reports Server (NTRS)

    Delduca, B. S.

    1972-01-01

    The electrochemical oxidation of p-type boron in 0.2 N NaNO3 solutions of pH 0.4 to 13.1 was studied by galvanostatic techniques. The capacitance of the electrode, Tafel slopes, and a limited analysis of reaction mechanisms are reported. The anodic dissolution in acid solution is a charge-transfer-limited one-electron reaction to form a monovalent species in the over-potential region of 0.25 to 0.70 V. The dissolution in basic solution is most probably a one-electron charge-transfer reaction from a monovalent to divalent species involving three hydroxyl ions. Open circuit potentials were mixed potentials, probably due to hydrogen formation at open circuit but not contributing to the electrochemical reaction at the applied overpotential. Exchange current, estimated by extrapolation of the Tafel line to the standard oxidation potential for the boron reaction, were of the order of 10 to the minus 6th power A/cm2 in acid solution and 10 to the minus 12th power A/cm2 in basic solution. The reaction order of the rate determining acidic and basic reactions was determined with regard to (H+) and (OH-). The level of illumination had no effect on the electrochemical behavior of the electrode.

  3. Distribution of haloacetic acids in the water columns of the Laurentian Great Lakes and Lake Malawi.

    PubMed

    Scott, Brian F; Spencer, Christine; Marvin, Christopher H; MacTavish, David C; Muir, Derek C G

    2002-05-01

    Haloacetic acids (HAAs) are persistent and mildly phytotoxic compounds that have been detected in many aquatic environments, including the waters of the Great Lakes. Sources of HAAs, especially of trifluoroacetic acid (TFA), are not well understood. In this study we assessed the influence of urbanization on the concentrations and profiles of HAAs in the Laurentian Great Lakes and in Lake Malawi, an African Great Lake. Vertical depth profiles for these compounds were taken for each of the Great Lakes with additional profiles taken 2 years later for Lakes Erie and Ontario. The results showed that while TFA was relatively constant throughout the water column, the chloroacetic acids (CAAs) varied with depth. There was a trend of increasing TFA proceeding from Lake Superior to Lake Ontario (18-150 ng/L). Total CAA concentrations were relatively constant throughout the lakes (approximately 500 ng/L) with dichloroacetic acid being the most abundant. No bromoacetic acids were detected. In the Detroit River, a connecting channel between Lakes Huron and Erie, the TFA values were similar to those in Lake Huron, but the CAAs levels were higher than in the upstream lakes and dependent on location, indicating inputs from urban areas along the river. These results were compared to those from Lake Malawi, which has a high population density within the watershed but no heavy industry. CAAs were nondetectable, and TFA concentrations were just at the detection limit (1 ng/L). Total HAA in the water column of Lakes Superior and Huron was compared to annual precipitation inputs at a site situated near both lakes. For Lake Huron, precipitation was a minor contributor to the total HAA inventory of the lake, but for Lake Superior precipitation could be the major contributor to the mass of HAA in this lake. Generally, high HAA levels paralleled the degree of industrial activity in the adjacent waters.

  4. Fuel cell anode configuration for CO tolerance

    DOEpatents

    Uribe, Francisco A.; Zawodzinski, Thomas A.

    2004-11-16

    A polymer electrolyte fuel cell (PEFC) is designed to operate on a reformate fuel stream containing oxygen and diluted hydrogen fuel with CO impurities. A polymer electrolyte membrane has an electrocatalytic surface formed from an electrocatalyst mixed with the polymer and bonded on an anode side of the membrane. An anode backing is formed of a porous electrically conductive material and has a first surface abutting the electrocatalytic surface and a second surface facing away from the membrane. The second surface has an oxidation catalyst layer effective to catalyze the oxidation of CO by oxygen present in the fuel stream where at least the layer of oxidation catalyst is formed of a non-precious metal oxidation catalyst selected from the group consisting of Cu, Fe, Co, Tb, W, Mo, Sn, and oxides thereof, and other metals having at least two low oxidation states.

  5. Investigation of mechanism of anode plasma formation in ion diode with dielectric anode

    SciTech Connect

    Pushkarev, A.

    2015-10-15

    The results of investigation of the anode plasma formation in a diode with a passive anode in magnetic insulation mode are presented. The experiments have been conducted using the BIPPAB-450 ion accelerator (350–400 kV, 6–8 kA, 80 ns) with a focusing conical diode with B{sub r} external magnetic field (a barrel diode). For analysis of plasma formation at the anode and the distribution of the ions beam energy density, infrared imaging diagnostics (spatial resolution of 1–2 mm) is used. For analysis of the ion beam composition, time-of-flight diagnostics (temporal resolution of 1 ns) were used. Our studies have shown that when the magnetic induction in the A-C gap is much larger than the critical value, the ion beam energy density is close to the one-dimensional Child-Langmuir limit on the entire working surface of the diode. Formation of anode plasma takes place only by the flashover of the dielectric anode surface. In this mode, the ion beam consists primarily of singly ionized carbon ions, and the delay of the start of formation of the anode plasma is 10–15 ns. By reducing the magnetic induction in the A-C gap to a value close to the critical one, the ion beam energy density is 3–6 times higher than that calculated by the one-dimensional Child-Langmuir limit, but the energy density of the ion beam is non-uniform in cross-section. In this mode, the anode plasma formation occurs due to ionization of the anode material with accelerated electrons. In this mode, also, the delay in the start of the formation of the anode plasma is much smaller and the degree of ionization of carbon ions is higher. In all modes occurred effective suppression of the electronic component of the total current, and the diode impedance was 20–30 times higher than the values calculated for the mode without magnetic insulation of the electrons. The divergence of the ion beam was 4.5°–6°.

  6. Investigation of mechanism of anode plasma formation in ion diode with dielectric anode

    NASA Astrophysics Data System (ADS)

    Pushkarev, A.

    2015-10-01

    The results of investigation of the anode plasma formation in a diode with a passive anode in magnetic insulation mode are presented. The experiments have been conducted using the BIPPAB-450 ion accelerator (350-400 kV, 6-8 kA, 80 ns) with a focusing conical diode with Br external magnetic field (a barrel diode). For analysis of plasma formation at the anode and the distribution of the ions beam energy density, infrared imaging diagnostics (spatial resolution of 1-2 mm) is used. For analysis of the ion beam composition, time-of-flight diagnostics (temporal resolution of 1 ns) were used. Our studies have shown that when the magnetic induction in the A-C gap is much larger than the critical value, the ion beam energy density is close to the one-dimensional Child-Langmuir limit on the entire working surface of the diode. Formation of anode plasma takes place only by the flashover of the dielectric anode surface. In this mode, the ion beam consists primarily of singly ionized carbon ions, and the delay of the start of formation of the anode plasma is 10-15 ns. By reducing the magnetic induction in the A-C gap to a value close to the critical one, the ion beam energy density is 3-6 times higher than that calculated by the one-dimensional Child-Langmuir limit, but the energy density of the ion beam is non-uniform in cross-section. In this mode, the anode plasma formation occurs due to ionization of the anode material with accelerated electrons. In this mode, also, the delay in the start of the formation of the anode plasma is much smaller and the degree of ionization of carbon ions is higher. In all modes occurred effective suppression of the electronic component of the total current, and the diode impedance was 20-30 times higher than the values calculated for the mode without magnetic insulation of the electrons. The divergence of the ion beam was 4.5°-6°.

  7. High performance anode for advanced Li batteries

    SciTech Connect

    Lake, Carla

    2015-11-02

    The overall objective of this Phase I SBIR effort was to advance the manufacturing technology for ASI’s Si-CNF high-performance anode by creating a framework for large volume production and utilization of low-cost Si-coated carbon nanofibers (Si-CNF) for the battery industry. This project explores the use of nano-structured silicon which is deposited on a nano-scale carbon filament to achieve the benefits of high cycle life and high charge capacity without the consequent fading of, or failure in the capacity resulting from stress-induced fracturing of the Si particles and de-coupling from the electrode. ASI’s patented coating process distinguishes itself from others, in that it is highly reproducible, readily scalable and results in a Si-CNF composite structure containing 25-30% silicon, with a compositionally graded interface at the Si-CNF interface that significantly improve cycling stability and enhances adhesion of silicon to the carbon fiber support. In Phase I, the team demonstrated the production of the Si-CNF anode material can successfully be transitioned from a static bench-scale reactor into a fluidized bed reactor. In addition, ASI made significant progress in the development of low cost, quick testing methods which can be performed on silicon coated CNFs as a means of quality control. To date, weight change, density, and cycling performance were the key metrics used to validate the high performance anode material. Under this effort, ASI made strides to establish a quality control protocol for the large volume production of Si-CNFs and has identified several key technical thrusts for future work. Using the results of this Phase I effort as a foundation, ASI has defined a path forward to commercialize and deliver high volume and low-cost production of SI-CNF material for anodes in Li-ion batteries.

  8. Simple and Automated Coulometric Titration of Acid Using Nonisolated Electrodes

    ERIC Educational Resources Information Center

    Kuntzleman, Thomas S.; Kenney, Joshua B.; Hasbrouck, Scott; Collins, Michael J.; Amend, John R.

    2011-01-01

    Coulometric titrations involve the quantification of analyte by measurements of current and time. In most coulometric titrations, the anode and cathode are placed in isolated cells that are connected by a salt bridge. By contrast, the experiments described here involve coulometric titrations (of acidic protons in solution) using a silver anode and…

  9. Novel electrochemical behavior of zinc anodes in zinc/air batteries in the presence of additives

    NASA Astrophysics Data System (ADS)

    Lee, Chang Woo; Sathiyanarayanan, K.; Eom, Seung Wook; Kim, Hyun Soo; Yun, Mun Soo

    In our continued efforts to find an electrically rechargeable zn/air secondary battery, we report the unique behavior of a zinc oxide anode in the presence of additives such as phosphoric acid, tartaric acid, succinic acid and citric acid. These additives were added to the electrolyte, which is an 8.5 M KOH solution containing 25 g of ZnO and 3000 ppm of polyethylene glycol in 1 l of water. In zn/air systems there are two main problems namely the hydrogen overpotential and dendrite formation during recharging. Investigations have studied in detail both of the problems in order to overcome them. The results obtained in presence of additives are compared with the behavior of the electrolyte 8.5 M KOH in the absence of additives. It has been concluded that the hydrogen overpotential is raised enormously while dendrite formation is reduced to some extent. Out of the four acids studied, the order of increase in hydrogen overpotential is: tartaric acid > succinic acid > phosphoric acid > citric acid. The prevention of dendrite formation follows the order: citric acid > succinic acid > tartaric acid > phosphoric acid.

  10. Anode arc motion in high power arcjets

    NASA Technical Reports Server (NTRS)

    Harris, W. J.; O'Hair, E. A.; Hatfield, L. L.; Kristiansen, M.; Mankins, J. S.

    1992-01-01

    The long-term operational lifetime of most medium to high power arcjets is currently limited by the rapid deterioration of the arcjet electrodes. To a large extent, the rate of this deterioration is related to the motion of the arc discharge on the electrode surfaces. This paper details a series of experiments aimed at studying the temporal behavior of dc arcs on a water-cooled radially-segmented 30 kW class arcjet anode. The experimental anode used for these tests was made of copper, and was divided into four equivalent radial segments which were electrically isolated with aluminum oxide gaskets. The current carried by each segment was measured independently using four calibrated resistive shunts, and was analyzed by digital computer. The tests were limited to nitrogen propellant over a current range of 100-250 A dc. Results show that for the range of total currents considered here, the current distribution in the segmented arcjet anode is generally asymmetric, exhibiting random fluctuations over a wide range of frequencies.

  11. Lithium Metal Anodes for Rechargeable Batteries

    SciTech Connect

    Xu, Wu; Wang, Jiulin; Ding, Fei; Chen, Xilin; Nasybulin, Eduard N.; Zhang, Yaohui; Zhang, Jiguang

    2013-10-29

    Rechargeable lithium metal batteries have much higher energy density than those of lithium ion batteries using graphite anode. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries (upon repeated charge/discharge cycling) and limited Coulombic efficiency during lithium deposition/striping has prevented their practical application over the past 40 years. With the emerging of post Li-ion batteries, safe and efficient operation of lithium metal anode has become an enabling technology which may determine the fate of several promising candidates for the next generation of energy storage systems, including rechargeable Li-air battery, Li-S battery, and Li metal battery which utilize lithium intercalation compounds as cathode. In this work, various factors which affect the morphology and Coulombic efficiency of lithium anode will be analyzed. Technologies used to characterize the morphology of lithium deposition and the results obtained by modeling of lithium dendrite growth will also be reviewed. At last, recent development in this filed and urgent need in this field will also be discussed.

  12. Anode arc motion in high power arcjets

    NASA Astrophysics Data System (ADS)

    Harris, W. J.; O'Hair, E. A.; Hatfield, L. L.; Kristiansen, M.; Mankins, J. S.

    1992-07-01

    The long-term operational lifetime of most medium to high power arcjets is currently limited by the rapid deterioration of the arcjet electrodes. To a large extent, the rate of this deterioration is related to the motion of the arc discharge on the electrode surfaces. This paper details a series of experiments aimed at studying the temporal behavior of dc arcs on a water-cooled radially-segmented 30 kW class arcjet anode. The experimental anode used for these tests was made of copper, and was divided into four equivalent radial segments which were electrically isolated with aluminum oxide gaskets. The current carried by each segment was measured independently using four calibrated resistive shunts, and was analyzed by digital computer. The tests were limited to nitrogen propellant over a current range of 100-250 A dc. Results show that for the range of total currents considered here, the current distribution in the segmented arcjet anode is generally asymmetric, exhibiting random fluctuations over a wide range of frequencies.

  13. Protection of MOS capacitors during anodic bonding

    NASA Astrophysics Data System (ADS)

    Schjølberg-Henriksen, K.; Plaza, J. A.; Rafí, J. M.; Esteve, J.; Campabadal, F.; Santander, J.; Jensen, G. U.; Hanneborg, A.

    2002-07-01

    We have investigated the electrical damage by anodic bonding on CMOS-quality gate oxide and methods to prevent this damage. n-type and p-type MOS capacitors were characterized by quasi-static and high-frequency CV-curves before and after anodic bonding. Capacitors that were bonded to a Pyrex wafer with 10 μm deep cavities enclosing the capacitors exhibited increased leakage current and interface trap density after bonding. Two different methods were successful in protecting the capacitors from such damage. Our first approach was to increase the cavity depth from 10 μm to 50 μm, thus reducing the electric field across the gate oxide during bonding from approximately 2 × 105 V cm-1 to 4 × 104 V cm-1. The second protection method was to coat the inside of a 10 μm deep Pyrex glass cavity with aluminium, forming a Faraday cage that removed the electric field across the cavity during anodic bonding. Both methods resulted in capacitors with decreased interface trap density and unchanged leakage current after bonding. No change in effective oxide charge or mobile ion contamination was observed on any of the capacitors in the study.

  14. Cellular porous anodic alumina grown in neutral organic electrolyte. 1. Structure, composition, and properties of the films

    SciTech Connect

    Liu, Y.; Alwitt, R.S.; Shimizu, K.

    2000-04-01

    Anodic alumina films with cellular porous structure grow in neutral organic electrolytes with low water content and containing ethylene glycol and a large dicarboxylic acid. An Al carboxylate precipitates in the pore and is extruded from the coating. The porous structure develops even though the current efficiency for film formation is near 95%. The coating matrix contains substantial organic material, 15 wt % by thermal analysis. It is an oxide/organic composite with higher field strength and lower dielectric constant than pure anodic alumina.

  15. Alternative consumable anodes for cathodic protection of reinforced concrete bridges

    SciTech Connect

    Bullard, Sophie J.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Holcomb, Gordon R.; Russell, James H.; Cryer, C.B.; Laylor, H.M.

    1999-01-01

    Alternative consumable anodes were evaluated in the laboratory for use in cathodic protection systems for steel reinforced concrete bridges in coastal environments and in areas where deicing salts are employed. The anode materials included zinc hydrogel foil and thermal-sprayed Zn, Zn-15Al, and Al-12Zn-0.2In alloys. They were evaluated for service in both impressed current (ICCP) and galvanic (GCP) cathodic protection systems. ICCP anodes were electrochemically aged at current densities of five to fifteen times that used by the Oregon Department of Transportation (Oregon DOT) in typical coastal CP systems (2.2 mA/m2 based on anode area). GCP anodes were electrochemically aged at a rate defined by the steel-anode couple. Both types of anodes were exposed to 80°F, a relative humidity of 85 pct, and were periodically wetted with deionized water. The Zn anode gave the best performance in ICCP systems. The four anodes all produced sufficient current density suitable for use in GCP systems. The anodes materials, ranked in increasing order of GCP current output, were: thermal-sprayed Al-12Zn-0.2In, Zn hydrogel, thermal-sprayed Zn-15Al, and thermal-sprayed Zn.

  16. Pack aluminization of nickel anode for molten carbonate fuel cells

    NASA Astrophysics Data System (ADS)

    Chun, H. S.; Park, G. P.; Lim, J. H.; Kim, K.; Lee, J. K.; Moon, K. H.; Youn, J. H.

    1994-04-01

    The aluminum pack cementation (pack aluminization) process on a porous nickel anode for molten carbonate fuel cells has been studied to improve anode creep resistance. The porous nickel substrates used in this study were fabricated by doctor blade equipment followed by sintering (850 C). Packs surrounding the Ni anode were made by mixing Al2O3 powder, Al powder, and NaCl as activator. The pack aluminization was performed at 700 to 850 C for 0.5-5.0 h. After pack aluminization, the principal Ni-Al intermetallic compounds detected were Ni3Al at 700 C, NiAl at 750 C and Ni3Al2 at 800 C. The aluminum content in the aluminized Ni anode was proportional to the square root of pack aluminizing time. With increasing the Al content in the anode, the creep of the anode decreased. It was nearly constant (2.0%) when the Al content was above 5.0%. Although the exchange current density (24 mA/sq cm) for the aluminized (2.5 wt.%) Ni anode was somewhat lower than that of the pure Ni anode (40 mA/sq cm), the performance of a single cell using an aluminized Ni anode was similar to that of the one with pure Ni anode.

  17. Ascorbic acid (AA) metabolism in protection against radiation damage

    SciTech Connect

    Rose, R.C.; Koch, M.J.

    1986-03-05

    The possibility is considered that AA protects tissues against radiation damage by scavenging free radicals that result from radiolysis of water. A physiologic buffer (pH 6.7) was incubated with /sup 14/C-AA and 1 mM thiourea (to slow spontaneous oxidation of AA). Aliquots were assayed by HPLC and scintillation spectrometry to identify the /sup 14/C-label. Samples exposed to Cobalt-60 radiation had a half time of AA decay of < 3 minutes compared with nonirradiated samples (t/sub 1/2/ > 30 minutes) indicating that AA scavenges radiation-induced free radicals and forms the ascorbate free radical (AFR). Pairs of /sup 14/C-AFR disproportionate, with the net effect of /sup 14/C-dehydroascorbic acid formation from /sup 14/C-AA. Having established that AFR result from ionizing radiation in an aqueous solution, the possibility was evaluated that a tissue factor reduces AFR. Cortical tissue from the kidneys of male rats was minced, homogenized in buffer and centrifuged at 8000 xg. The supernatant was found to slow the rate of radiation-induced AA degradation by > 90% when incubated at 23/sup 0/C in the presence of 15 ..mu..M /sup 14/C-AA. Samples of supernatant maintained at 100/sup 0/C for 10 minutes or precipitated with 5% PCA did not prevent radiation-induced AA degradation. AA may have a specific role in scavenging free radicals generated by ionizing radiation and thereby protect body tissues.

  18. Monohaloacetic acid drinking water disinfection by-products inhibit follicle growth and steroidogenesis in mouse ovarian antral follicles in vitro.

    PubMed

    Jeong, Clara H; Gao, Liying; Dettro, Tyler; Wagner, Elizabeth D; Ricke, William A; Plewa, Michael J; Flaws, Jodi A

    2016-07-01

    Water disinfection greatly reduced the incidence of waterborne diseases, but the reaction between disinfectants and natural organic matter in water leads to the formation of drinking water disinfection by-products (DBPs). DBPs have been shown to be toxic, but their effects on the ovary are not well defined. This study tested the hypothesis that monohalogenated DBPs (chloroacetic acid, CAA; bromoacetic acid, BAA; iodoacetic acid, IAA) inhibit antral follicle growth and steroidogenesis in mouse ovarian follicles. Antral follicles were isolated and cultured with either vehicle or DBPs (0.25-1.00mM of CAA; 2-15μM of BAA or IAA) for 48 and 96h. Follicle growth was measured every 24h and the media were analyzed for estradiol levels at 96h. Exposure to DBPs significantly inhibited antral follicle growth and reduced estradiol levels compared to controls. These data demonstrate that DBP exposure caused ovarian toxicity in vitro. PMID:27151372

  19. Controlling Pore Geometries and Interpore Distances of Anodic Aluminum Oxide Templates via Three-Step Anodization.

    PubMed

    Lim, Jin-Hee; Wiley, John B

    2015-01-01

    Porous alumina membranes have attracted much attention because they are very useful templates for the fabrication of various nanostructures important to nanotechnology. However, there are challenges in controlling pore geometries and interpore distances in alumina templates while maintaining highly ordered hexagonal pore structures. Herein, a three-step anodization method is utilized to prepare anodic alumina templates with various pore morphologies (e.g., arched-shape, tree-like, branched-shape) and tunable interpore distances. Such structures are not found within the more traditional alumina templates fabricated by a two-step anodization of aluminum films. The range of interpore distances and pore diameters within the modified templates increases with increasing voltages. In contrast, under decreasing voltages, hexagonally ordered pores can also branch into several pores with smaller sizes and reduced interpore distances. Electrochemical growth of metal nanowires in the modified templates helps to highlight details of the pore structures and which pore channels are active.

  20. Anodic Aluminum Oxide (AAO) Membranes for Cellular Devices

    NASA Astrophysics Data System (ADS)

    Ventura, Anthony P.

    Anodic Aluminum Oxide (AAO) membranes can be fabricated with a highly tunable pore structure making them a suitable candidate for cellular hybrid devices with single-molecule selectivity. The objective of this study was to characterize the cellular response of AAO membranes with varying pore sizes to serve as a proof-of-concept for an artificial material/cell synapse system. AAO membranes with pore diameters ranging from 34-117 nm were achieved via anodization at a temperature of -1°C in a 2.7% oxalic acid electrolyte. An operating window was established for this setup to create membranes with through-pore and disordered pore morphologies. C17.2 neural stem cells were seeded onto the membranes and differentiated via serum withdrawal. The data suggests a highly tunable correlation between AAO pore diameter and differentiated cell populations. Analysis of membranes before and after cell culture indicated no breakdown of the through-pore structure. Immunocytochemistry (ICC) showed that AAO membranes had increased neurite outgrowth when compared to tissue culture treated (TCT) glass, and neurite outgrowth varied with pore diameter. Additionally, lower neuronal percentages were found on AAO as compared to TCT glass; however, neuronal population was also found to vary with pore diameter. Scanning electron microscopy (SEM) and ICC images suggested the presence of a tissue-like layer with a mixed-phenotype population. AAO membranes appear to be an excellent candidate for cellular devices, but more work must be completed to understand the surface chemistry of the AAO membranes as it relates to cellular response.

  1. Organic anodes and sulfur/selenium cathodes for advanced Li and Na batteries

    NASA Astrophysics Data System (ADS)

    Luo, Chao

    To address energy crisis and environmental pollution induced by fossil fuels, there is an urgent demand to develop sustainable, renewable, environmental benign, low cost and high capacity energy storage devices to power electric vehicles and enhance clean energy approaches such as solar energy, wind energy and hydroenergy. However, the commercial Li-ion batteries cannot satisfy the critical requirements for next generation rechargeable batteries. The commercial electrode materials (graphite anode and LiCoO 2 cathode) are unsustainable, unrenewable and environmental harmful. Organic materials derived from biomasses are promising candidates for next generation rechargeable battery anodes due to their sustainability, renewability, environmental benignity and low cost. Driven by the high potential of organic materials for next generation batteries, I initiated a new research direction on exploring advanced organic compounds for Li-ion and Na-ion battery anodes. In my work, I employed croconic acid disodium salt and 2,5-Dihydroxy-1,4-benzoquinone disodium salt as models to investigate the effects of size and carbon coating on electrochemical performance for Li-ion and Na-ion batteries. The results demonstrate that the minimization of organic particle size into nano-scale and wrapping organic materials with graphene oxide can remarkably enhance the rate capability and cycling stability of organic anodes in both Li-ion and Na-ion batteries. To match with organic anodes, high capacity sulfur and selenium cathodes were also investigated. However, sulfur and selenium cathodes suffer from low electrical conductivity and shuttle reaction, which result in capacity fading and poor lifetime. To circumvent the drawbacks of sulfur and selenium, carbon matrixes such as mesoporous carbon, carbonized polyacrylonitrile and carbonized perylene-3, 4, 9, 10-tetracarboxylic dianhydride are employed to encapsulate sulfur, selenium and selenium sulfide. The resulting composites exhibit

  2. Effect of the local electric field on the formation of an ordered structure in porous anodic alumina

    NASA Astrophysics Data System (ADS)

    Lazarouk, S. K.; Katsuba, P. S.; Leshok, A. A.; Vysotskii, V. B.

    2015-09-01

    Experimental data and a model are presented, and the electric field that appears in porous alumina during electrochemical anodic oxidation of aluminum in electrolytes based on an aqueous solution of oxalic acid at a voltage of 90-250 V is calculated. It is found that the electric field in the layers with a porosity of 1-10% in growing alumina reaches 109-1010 V/m, which exceeds the electric strength of the material and causes microplasma patterns emitting visible light at the pore bottom, the self-organization of the structure of porous alumina, and the anisotropy of local porous anodizing. Moreover, other new effects are to be expected during aluminum anodizing under the conditions that ensure a high electric field inside the barrier layer of porous oxide.

  3. Fundamental Investigation of Si Anode in Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Wu, James J.; Bennett, William R.

    2012-01-01

    Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is approximately 10 times of graphite and it is an abundant element on earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of Si anode during the first cycle, the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes.

  4. Materials characterization of cermet anodes tested in a pilot cell

    SciTech Connect

    Windisch, C.F. Jr.; Strachan, D.M.; Henager, C.H. Jr.; Alcorn, T.R.; Tabereaux, A.T.; Richards, N.E.

    1993-02-01

    Cermet anodes were evaluated as nonconsumable substitutes for carbon anodes using a pilot-scale reduction cell at the Reynolds Manufacturing Technology Laboratory. After pilot cell testing, tile anodes were subjected to extensive materials characterization and physical properties measurements at the Pacific Northwest Laboratory. Significant changes in the composition of the cermet anodes were observed including the growth of a reaction layer and penetration of electrolyte deep into the cermet matrix. Fracture strength and toughness were measured as a function of temperature and the ductile-brittle transition wasreduced by 500C following pilot cell testing. These results imply difficulties with anode material and control of operating conditions in the pilot cell, and suggest that additional development work be performed before the cermet anodes are used in commercial reduction cells. The results also highlight specific fabrication and operational considerations that should be addressed in future testing.

  5. Formation of anodic layers on InAs (111)III. Study of the chemical composition

    SciTech Connect

    Valisheva, N. A. Tereshchenko, O. E.; Prosvirin, I. P.; Kalinkin, A. V.; Goljashov, V. A.; Levtzova, T. A.; Bukhtiyarov, V. I.

    2012-04-15

    The chemical composition of {approx}20-nm-thick anodic layers grown on InAs (111)III in alkaline and acid electrolytes containing or not containing NH{sub 4}F is studied by X-ray photoelectron spectroscopy. It is shown that the composition of fluorinated layers is controlled by the relation between the concentrations of fluorine and hydroxide ions in the electrolyte and by diffusion processes in the growing layer. Fluorine accumulates at the (anodic layer)/InAs interface. Oxidation of InAs in an acid electrolyte with a low oxygen content and a high NH{sub 4}F content brings about the formation of anodic layers with a high content of fluorine and elemental arsenic and the formation of an oxygen-free InF{sub x}/InAs interface. Fluorinated layers grown in an alkaline electrolyte with a high content of O{sup 2-} and/or OH{sup -} groups contain approximately three times less fluorine and consist of indium and arsenic oxyfluorides. No distinction between the compositions of the layers grown in both types of fluorine-free electrolytes is established.

  6. Cerium oxide coated anodes for aluminum electrowinning: Topical report, October 1, 1986-June 30, 1987

    SciTech Connect

    Walker, J. K.

    1987-12-01

    Because of the cost of building and maintaining a carbon anode plant and the energy penalties associated with the use of carbon anodes in the production of aluminum, the use of inert anodes has long been proposed. Various cermet anodes have been investigated. In this paper, tests on a material, cerium oxyfluoride (CEROX), deposited in situ as an anode, are reported. (JDH)

  7. Conductive polymer coatings for anodes in aqueous electrowinning

    NASA Astrophysics Data System (ADS)

    Alfantazi, A. M.; Moskalyk, R. R.

    2003-07-01

    This article discusses the potential application of electrically conductive polymers as protective coatings for permanent lead anodes employed in aqueous electrowinning processes. Also presented are results from a preliminary study of the performance of two intrinsically conductive polymers (polyaniline and poly 3,4,5-trifluorophenylthiophene [TFPT]) under mild copper electrowinning conditions as conductive and protective coatings on anodic surfaces. The laboratory results indicated that using lead alloy anodes coated with TFPT merits continued research.

  8. Tracing Carbon Sources through Aquatic and Terrestrial Food Webs Using Amino Acid Stable Isotope Fingerprinting

    PubMed Central

    Larsen, Thomas; Ventura, Marc; Andersen, Nils; O’Brien, Diane M.; Piatkowski, Uwe; McCarthy, Matthew D.

    2013-01-01

    Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ13C patterns among amino acids (δ13CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ13CAA patterns in contrast to bulk δ13C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ13CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ13C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ13C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs. PMID:24069196

  9. Tracing carbon sources through aquatic and terrestrial food webs using amino acid stable isotope fingerprinting.

    PubMed

    Larsen, Thomas; Ventura, Marc; Andersen, Nils; O'Brien, Diane M; Piatkowski, Uwe; McCarthy, Matthew D

    2013-01-01

    Tracing the origin of nutrients is a fundamental goal of food web research but methodological issues associated with current research techniques such as using stable isotope ratios of bulk tissue can lead to confounding results. We investigated whether naturally occurring δ(13)C patterns among amino acids (δ(13)CAA) could distinguish between multiple aquatic and terrestrial primary production sources. We found that δ(13)CAA patterns in contrast to bulk δ(13)C values distinguished between carbon derived from algae, seagrass, terrestrial plants, bacteria and fungi. Furthermore, we showed for two aquatic producers that their δ(13)CAA patterns were largely unaffected by different environmental conditions despite substantial shifts in bulk δ(13)C values. The potential of assessing the major carbon sources at the base of the food web was demonstrated for freshwater, pelagic, and estuarine consumers; consumer δ(13)C patterns of essential amino acids largely matched those of the dominant primary producers in each system. Since amino acids make up about half of organismal carbon, source diagnostic isotope fingerprints can be used as a new complementary approach to overcome some of the limitations of variable source bulk isotope values commonly encountered in estuarine areas and other complex environments with mixed aquatic and terrestrial inputs.

  10. Stability of the anodic growth porous tungsten oxide in different solutions

    SciTech Connect

    Chai, Y.; Yam, F. K.; Hassan, Z.

    2015-05-15

    This article presents the study of the stability of the anodic growth porous tungsten oxide (WO{sub 3}) film in different solutions. As-anodized films are relatively stable in acidic electrolytes like sulphuric acid (H{sub 2}SO{sub 4}), hydrochloric acid (HCl) but not in oxalic acid. In higher pH solution, rate of dissolution of the WO{sub 3} film is higher. Annealing at 400 °C for 2 h transform the as-grown sample from amorphous phase to the crystalline phase and this significantly improve the stability of the film in high pH solution. Photocurrent measurements reveal that there is no significant difference of the electrolyte used (0.5 M H{sub 2}SO{sub 4}, 0.33 M H{sub 3}PO{sub 4}, 0.1 M sodium sulfate (Na{sub 2}SO{sub 4})) on the photocurrent. As-annealed films exhibit good stablility for the long photoelectrochemical (PEC) measurements (1700 s) in 0.5 M H{sub 2}SO{sub 4} and 0.1 M Na{sub 2}SO{sub 4}. There is no effect on the photocurrent for the variation of the concentration of the acidic solution (H{sub 2}SO{sub 4}). However, lower photocurrent was obtained as the concentration of Na{sub 2}SO{sub 4} was increased.

  11. Nonpolar GaN grown on Si by hydride vapor phase epitaxy using anodized Al nanomask

    NASA Astrophysics Data System (ADS)

    Polyakov, A. Y.; Markov, A. V.; Mezhennyi, M. V.; Govorkov, A. V.; Pavlov, V. F.; Smirnov, N. B.; Donskov, A. A.; D'yakonov, L. I.; Kozlova, Y. P.; Malakhov, S. S.; Yugova, T. G.; Osinsky, V. I.; Gorokh, G. G.; Lyahova, N. N.; Mityukhlyaev, V. B.; Pearton, S. J.

    2009-01-01

    GaN growth by the hydride vapor phase technique on (100) Si substrates masked by porous Al anodic oxide is described. The masks were prepared by vacuum deposition of Al with subsequent anodic oxidation in dilute sorrel acid. The grown GaN layer is nonpolar, with (112¯0) a-orientation and a full width at half maximum of the (112¯0) reflection below 500 arc sec and showing small anisotropy. This result is comparable with the results obtained for a-GaN growth using selective epitaxy or advanced buffer growth routines. Microcathodoluminescence spectra of the grown films confirm a low density of stacking faults. Possible growth mechanisms are discussed.

  12. Mesh-on-lead anodes for copper electrowinning

    NASA Astrophysics Data System (ADS)

    Moats, Michael; Hardee, Kenneth; Brown, Carl

    2003-07-01

    ELTECH System Corporation has developed and patented a Mesh-on-Lead™ (MOL™) (Mesh-on-Lead and MOL are trademarks of ELTECH Systems Corporation) anode for primary copper electrowinning operations. Over the past five years, ELTECH has demonstrated the MOL concept with full-scale anodes at several premier commercial tankhouses. During these demonstrations MOL anodes exhibited numerous performance advantages relative to standard Pb-Ca-Sn anodes, including reduced power consumption due to lower oxygen evolution over-potential, improved cathode quality, minimized lead sludge generation, eliminated cobalt addition as a result of stabilized lead substrate, and improved current efficiency due to reduced short circuiting.

  13. Testing and Characterization of Anode Current in Aluminum Reduction Cells

    NASA Astrophysics Data System (ADS)

    Wang, Yongliang; Tie, Jun; Sun, Shuchen; Tu, Ganfeng; Zhang, Zhifang; Zhao, Rentao

    2016-06-01

    Anode current is an important parameter in the aluminum reduction process, but to test the anode current accurately is difficult at present. This study tested the individual anode current using the fiber-optic current sensor. The testing results show that this method can effectively avoid the interference of the electromagnetic field, and the current is measured with high precision which error is less than 1 pct. In the paper, the test currents under different cell conditions, including anode changing, metal tapping, abnormal current, and anode effect, are investigated using the method of time-domain and frequency-domain analysis, and the simulation method is also combined to investigate the cell conditions. The results prove that different cell conditions will show different anode current characteristics, and the individual current can monitor the cell conditions, especially the localized cell conditions. Some abnormal cell conditions can be found through anode current rather than cell voltage. The anode current can also be used for early detection of anode effect.

  14. The corrosion protection of 2219-T87 aluminum by anodizing

    NASA Technical Reports Server (NTRS)

    Danford, M. D.

    1991-01-01

    Various types of anodizing coatings were studied for 2219-T87 aluminum. These include both type II and type III anodized coats which were water sealed and a newly developed and proprietary Magnaplate HCR (TM) coat. Results indicate that type II anodizing is not much superior to type II anodizing as far as corrosion protection for 2219-T87 aluminum is concerned. Magnaplate HCR (TM) coatings should provide superior corrosion protection over an extended period of time using a coating thickness of 51 microns (2.0 mils).

  15. Cooling for a rotating anode X-ray tube

    DOEpatents

    Smither, Robert K.

    1998-01-01

    A method and apparatus for cooling a rotating anode X-ray tube. An electromagnetic motor is provided to rotate an X-ray anode with cooling passages in the anode. These cooling passages are coupled to a cooling structure located adjacent the electromagnetic motor. A liquid metal fills the passages of the cooling structure and electrical power is provided to the motor to rotate the anode and generate a rotating magnetic field which moves the liquid metal through the cooling passages and cooling structure.

  16. Finding Platinum-Coating Gaps On Titanium Anodes

    NASA Technical Reports Server (NTRS)

    Bodemeijer, Ronnald; Flowers, Cecil E.

    1990-01-01

    Simple procedure makes gaps visible to eye. New gap-detection method consists of plating thin layer of non-silver-colored metal like copper or gold on anode. Contrast in color between plated metal and bare anode material makes gaps stand out. If anode passes inspection, copper or gold plate removable by reversal of test-plating current. Remains to be determined whether test plating and removal damages anode. New method simpler and more economical than previous attempts to identify gaps in platinum.

  17. Characterization of a newly identified mycobacterial tautomerase with promiscuous dehalogenase and hydratase activities reveals a functional link to a recently diverged cis-3-chloroacrylic acid dehalogenase.

    PubMed

    Baas, Bert-Jan; Zandvoort, Ellen; Wasiel, Anna A; Quax, Wim J; Poelarends, Gerrit J

    2011-04-12

    The enzyme cis-3-chloroacrylic acid dehalogenase (cis-CaaD) is found in a bacterial pathway that degrades a synthetic nematocide, cis-1,3-dichloropropene, introduced in the 20th century. The previously determined crystal structure of cis-CaaD and its promiscuous phenylpyruvate tautomerase (PPT) activity link this dehalogenase to the tautomerase superfamily, a group of homologous proteins that are characterized by a catalytic amino-terminal proline and a β-α-β structural fold. The low-level PPT activity of cis-CaaD, which may be a vestige of the function of its progenitor, prompted us to search the databases for a homologue of cis-CaaD that was annotated as a putative tautomerase and test both its PPT and cis-CaaD activity. We identified a mycobacterial cis-CaaD homologue (designated MsCCH2) that shares key sequence and active site features with cis-CaaD. Kinetic and 1H NMR spectroscopic studies show that MsCCH2 functions as an efficient PPT and exhibits low-level promiscuous dehalogenase activity, processing both cis- and trans-3-chloroacrylic acid. To further probe the active site of MsCCH2, the enzyme was incubated with 2-oxo-3-pentynoate (2-OP). At pH 8.5, MsCCH2 is inactivated by 2-OP due to the covalent modification of Pro-1, suggesting that Pro-1 functions as a nucleophile at pH 8.5 and attacks 2-OP in a Michael-type reaction. At pH 6.5, however, MsCCH2 exhibits hydratase activity and converts 2-OP to acetopyruvate, which implies that Pro-1 is cationic at pH 6.5 and not functioning as a nucleophile. At pH 7.5, the hydratase and inactivation reactions occur simultaneously. From these results, it can be inferred that Pro-1 of MsCCH2 has a pKa value that lies in between that of a typical tautomerase (pKa of Pro-1∼6) and that of cis-CaaD (pKa of Pro-1∼9). The shared activities and structural features, coupled with the intermediate pKa of Pro-1, suggest that MsCCH2 could be characteristic of an evolutionary intermediate along the past route for the

  18. Anodized titania: Processing and characterization to improve cell-materials interactions for load bearing implants

    NASA Astrophysics Data System (ADS)

    Das, Kakoli

    The objective of this study is to investigate in vitro cell-materials interactions using human osteoblast cells on anodized titanium. Titanium is a bioinert material and, therefore, gets encapsulated after implantation into the living body by a fibrous tissue that isolates them from the surrounding tissues. In this work, bioactive nonporous and nanoporous TiO2 layers were grown on commercially pure titanium substrate by anodization process using different electrolyte solutions namely (1) H3PO 4, (2) HF and (3) H2SO4, (4) aqueous solution of citric acid, sodium fluoride and sulfuric acid. The first three electrolytes produced bioactive TiO2 films with a nonporous structure showing three distinctive surface morphologies. Nanoporous morphology was obtained on Ti-surfaces from the fourth electrolyte at 20V for 4h. Cross-sectional view of the nanoporous surface reveals titania nanotubes of length 600 nm. It was found that increasing anodization time initially increased the height of the nanotubes while maintaining the tubular array structure, but beyond 4h, growth of nanotubes decreased with a collapsed array structure. Human osteoblast (HOB) cell attachment and growth behavior were studied using an osteoprecursor cell line (OPC 1) for 3, 7 and 11 days. Colonization of the cells was noticed with distinctive cell-to-cell attachment on HF anodized surfaces. TiO2 layer grown in H2SO4 electrolyte did not show significant cell growth on the surface, and some cell death was also noticed. Good cellular adherence with extracellular matrix extensions in between the cells was noticed for samples anodized with H3PO 4 electrolyte and nanotube surface. Cell proliferation was excellent on anodized nanotube surfaces. An abundant amount of extracellular matrix (ECM) between the neighboring cells was also noticed on nanotube surfaces with filopodia extensions coming out from cells to grasp the nanoporous surface for anchorage. To better understand and compare cell-materials interactions

  19. Degradation of anti-inflammatory drug ketoprofen by electro-oxidation: comparison of electro-Fenton and anodic oxidation processes.

    PubMed

    Feng, Ling; Oturan, Nihal; van Hullebusch, Eric D; Esposito, Giovanni; Oturan, Mehmet A

    2014-01-01

    The electrochemical degradation of the nonsteroidal anti-inflammatory drug ketoprofen in tap water has been studied using electro-Fenton (EF) and anodic oxidation (AO) processes with platinium (Pt) and boron-doped diamond (BDD) anodes and carbon felt cathode. Fast degradation of the parent drug molecule and its degradation intermediates leading to complete mineralization was achieved by BDD/carbon felt, Pt/carbon felt, and AO with BDD anode. The obtained results showed that oxidative degradation rate of ketoprofen and mineralization of its aqueous solution increased by increasing applied current. Degradation kinetics fitted well to a pseudo-first-order reaction. Absolute rate constant of the oxidation of ketoprofen by electrochemically generated hydroxyl radicals was determined to be (2.8 ± 0.1) × 10(9) M(-1) s(-1) by using competition kinetic method. Several reaction intermediates such as 3-hydroxybenzoic acid, pyrogallol, catechol, benzophenone, benzoic acid, and hydroquinone were identified by high-performance liquid chromatography (HPLC) analyses. The formation, identification, and evolution of short-chain aliphatic carboxylic acids like formic, acetic, oxalic, glycolic, and glyoxylic acids were monitored with ion exclusion chromatography. Based on the identified aromatic/cyclic intermediates and carboxylic acids as end products before mineralization, a plausible mineralization pathway was proposed. The evolution of the toxicity during treatments was also monitored using Microtox method, showing a faster detoxification with higher applied current values.

  20. The Synthesis and In Vivo Pharmacokinetics of Fluorinated Arachidonic Acid: Implications for Imaging Neuroinflammation

    PubMed Central

    Pichika, Rama; Taha, Ameer Y.; Gao, Fei; Kotta, Kishore; Cheon, Yewon; Chang, Lisa; Kiesewetter, Dale; Rapoport, Stanley I.; Eckelman, William C.

    2012-01-01

    Arachidonic acid (AA) is found in high concentrations in brain phospholipids and is released as a second messenger during neurotransmission and much more so during neuroinflammation and excitotoxicity. Upregulated brain AA metabolism associated with neuroinflammation has been imaged in rodents using [1-14C]AA and with PET in Alzheimer disease patients using [1-11C]AA. Radiotracer brain AA uptake is independent of cerebral blood flow, making it an ideal tracer despite altered brain functional activity. However, the 20.4-min radioactive half-life of 11C-AA and challenges of routinely synthesizing 11C fatty acids limit their translational utility as PET biomarkers. Methods As a first step to develop a clinically useful 18F-fluoroarachidonic acid (18F-FAA) with a long radioactive half-life of 109.8 min, we report here a high-yield stereoselective synthetic method of non-radioactive 20-19F-FAA. We tested its in vivo pharmacokinetics by infusing purified nonradioactive 19F-FAA intravenously for 5 min at 2 doses in unanesthetized mice and measured its plasma and brain distribution using gas chromatography–mass spectrometry. Results Incorporation coefficients of injected 19F-FAA into brain phospholipids (ratio of brain 19F-FAA concentration to plasma input function) were 3- to 29-fold higher for choline glycerophospholipid and phosphatidylinositol than for ethanolamine glycerophospholipid and phosphatidylserine at each of the 2 tested doses. The selectivities and values of incorporation coefficients were comparable to those reported after [1-14C]AA (the natural arachidonate) infusion in mice. Conclusion These results suggest that it would be worthwhile to translate our stereoselective synthetic method for 19F-FAA to synthesize positron-emitting 18F-FAA for human brain AA metabolism in neuroinflammatory disorders such as Alzheimer disease. PMID:22851635

  1. Orally administered rosmarinic acid is present as the conjugated and/or methylated forms in plasma, and is degraded and metabolized to conjugated forms of caffeic acid, ferulic acid and m-coumaric acid.

    PubMed

    Baba, Seigo; Osakabe, Naomi; Natsume, Midori; Terao, Junji

    2004-05-28

    Rosmarinic acid (RA) is contained in various Lamiaceae herbs used commonly as culinary herbs. Although RA has various potent physiological actions, little is known on its bioavailability. We therefore investigated the absorption and metabolism of orally administered RA in rats. After being deprived of food for 12 h, RA (50 mg/kg body weight) or deionized water was administered orally to rats. Blood samples were collected from a cannula inserted in the femoral artery before and at designated time intervals after administration of RA. Urine excreted within 0 to 8 h and 8 to 18 h post-administration was also collected. RA and its related metabolites in plasma and urine were measured by LC-MS after treatment with sulfatase and/or beta-glucuronidase. RA, mono-methylated RA (methyl-RA) and m-coumaric acid (COA) were detected in plasma, with peak concentrations being reached at 0.5, 1 and 8 h after RA administration, respectively. RA, methyl-RA, caffeic acid (CAA), ferulic acid (FA) and COA were detected in urine after RA administration. These components in plasma and urine were present predominantly as conjugated forms such as glucuronide or sulfate. The percentage of the original oral dose of RA excreted in the urine within 18 h of administration as free and conjugated forms was 0.44 +/- 0.21% for RA, 1.60 +/- 0.74% for methyl-RA, 1.06 +/- 0.35% for CAA, 1.70 +/- 0.45% for FA and 0.67 +/- 0.29% for COA. Approximately 83% of the total amount of these metabolites was excreted in the period 8 to 18 h after RA administration. These results suggest that RA was absorbed and metabolized as conjugated and/or methylated forms, and that the majority of RA absorbed was degraded into conjugated and/or methylated forms of CAA, FA and COA before being excreted gradually in the urine. PMID:15120569

  2. Comparison of sodium naphthenate and air-ionization corona discharge as surface treatments for the ethylene-tetrafluoroethylene polymer (ETFE) to improve adhesion between ETFE and acrylonitrile-butadiene-styrene polymer (ABS) in the presence of a cyanoacrylate adhesive (CAA)

    NASA Astrophysics Data System (ADS)

    Lucía Johanning-Solís, Ana; Stradi-Granados, Benito A.

    2014-09-01

    This study compares two ethylene-tetrafluoroethylene (ETFE) surface activation treatments, namely chemical attack with a solution of sodium naphthenate and plasma erosion via air-ionization corona discharge in order to improve the adhesive properties of the ETFE. An experimental design was prepared for both treatments in order to assess the effect of the treatment characteristics on the tensile load needed to break the bond between the ETFE and the acrylonitrile-butadiene-styrene polymer (ABS) formed with a cyanoacrylate adhesive (CAA) applied between them. The reason for the selection of this problem is that both polymers are frequently used in the biomedical industry for their properties, and they need to be joined firmly in biomedical devices, and the cyanoacrylate adhesive is the adhesive traditionally used for fluoropolymers, in this case the ETFE, and the same CAA has also shown good adhesion with ABS. However, the strength of the bond for the triplet ETFE-CAA-ABS has not been reported and the improvement of the strength of the bond with surface treatments is not found in scholarly journals for modern medical devices such as stents and snares. Both treatments were compared based on the aforementioned design of experiments. The case where ETFE receives no surface treatment serves as the reference. The results indicated that the three factors evaluated (initial drying of the material, temperature of the chemical bath, and immersion time), and their interactions have no significant effect over the tensile load at failure (tensile strength) of the adhesive bond being evaluated. For the air-ionization corona discharge treatment, two factors were evaluated: discharge exposition time and air pressure. The results obtained from this experimental design indicate that there is no significant difference between the levels of the factors evaluated. These results were unexpected as the ranges used were representative of the maximum ranges permissible in manufacturing

  3. Degradation of 1-hydroxy-2,4-dinitrobenzene from aqueous solutions by electrochemical oxidation: role of anodic material.

    PubMed

    Quiroz, Marco A; Sánchez-Salas, José L; Reyna, Silvia; Bandala, Erick R; Peralta-Hernández, Juan M; Martínez-Huitle, Carlos A

    2014-03-15

    Electrochemical oxidation (ECOx) of 1-hydroxy-2,4-dinitrobenzene (or 2,4-dinitrophenol: 2,4-DNP) in aqueous solutions by electrolysis under galvanostatic control was studied at Pb/PbO2, Ti/SnO2, Ti/IrxRuySnO2 and Si/BDD anodes as a function of current density applied. Oxidative degradation of 2,4-DNP has clearly shown that electrode material and the current density applied were important parameters to optimize the oxidation process. It was observed that 2,4-DNP was oxidized at few substrates to CO2 with different results, obtaining good removal efficiencies at Pb/PbO2, Ti/SnO2 and Si/BDD anodes. Trends in degradation way depend on the production of hydroxyl radicals (OH) on these anodic materials, as confirmed in this study. Furthermore, HPLC results suggested that two kinds of intermediates were generated, polyhydroxylated intermediates and carboxylic acids. The formation of these polyhydroxylated intermediates seems to be associated with the denitration step and substitution by OH radicals on aromatic rings, this being the first proposed step in the reaction mechanism. These compounds were successively oxidized, followed by the opening of aromatic rings and the formation of a series of carboxylic acids which were at the end oxidized into CO2 and H2O. On the basis of these information, a reaction scheme was proposed for each type of anode used for 2,4-D oxidation.

  4. Green synthesis of boron doped graphene and its application as high performance anode material in Li ion battery

    SciTech Connect

    Sahoo, Madhumita; Sreena, K.P.; Vinayan, B.P.; Ramaprabhu, S.

    2015-01-15

    Graphical abstract: Boron doped graphene (B-G), synthesized by simple hydrogen induced reduction technique using boric acid as boron precursor, have more uneven surface as a result of smaller bonding distance of boron compared to carbon, showed high capacity and high rate capability compared to pristine graphene as an anode material for Li ion battery application. - Abstract: The present work demonstrates a facile route for the large-scale, catalyst free, and green synthesis approach of boron doped graphene (B-G) and its use as high performance anode material for Li ion battery (LIB) application. Boron atoms were doped into graphene framework with an atomic percentage of 5.93% via hydrogen induced thermal reduction technique using graphite oxide and boric acid as precursors. Various characterization techniques were used to confirm the boron doping in graphene sheets. B-G as anode material shows a discharge capacity of 548 mAh g{sup −1} at 100 mA g{sup −1} after 30th cycles. At high current density value of 1 A g{sup −1}, B-G as anode material enhances the specific capacity by about 1.7 times compared to pristine graphene. The present study shows a simplistic way of boron doping in graphene leading to an enhanced Li ion adsorption due to the change in electronic states.

  5. Degradation of 1-hydroxy-2,4-dinitrobenzene from aqueous solutions by electrochemical oxidation: role of anodic material.

    PubMed

    Quiroz, Marco A; Sánchez-Salas, José L; Reyna, Silvia; Bandala, Erick R; Peralta-Hernández, Juan M; Martínez-Huitle, Carlos A

    2014-03-15

    Electrochemical oxidation (ECOx) of 1-hydroxy-2,4-dinitrobenzene (or 2,4-dinitrophenol: 2,4-DNP) in aqueous solutions by electrolysis under galvanostatic control was studied at Pb/PbO2, Ti/SnO2, Ti/IrxRuySnO2 and Si/BDD anodes as a function of current density applied. Oxidative degradation of 2,4-DNP has clearly shown that electrode material and the current density applied were important parameters to optimize the oxidation process. It was observed that 2,4-DNP was oxidized at few substrates to CO2 with different results, obtaining good removal efficiencies at Pb/PbO2, Ti/SnO2 and Si/BDD anodes. Trends in degradation way depend on the production of hydroxyl radicals (OH) on these anodic materials, as confirmed in this study. Furthermore, HPLC results suggested that two kinds of intermediates were generated, polyhydroxylated intermediates and carboxylic acids. The formation of these polyhydroxylated intermediates seems to be associated with the denitration step and substitution by OH radicals on aromatic rings, this being the first proposed step in the reaction mechanism. These compounds were successively oxidized, followed by the opening of aromatic rings and the formation of a series of carboxylic acids which were at the end oxidized into CO2 and H2O. On the basis of these information, a reaction scheme was proposed for each type of anode used for 2,4-D oxidation. PMID:24462986

  6. Hybrid phosphazene anodes for energy storage applications

    SciTech Connect

    Eric J. Dufek; Mark L. Stone; Kevin L. Gering; Frederick F. Stewart; David Jamison; Aaron D. Wilson; Lucia M. Petkovic; Mason K. Harrup; Harry W. Rollins

    2014-12-01

    The use of hybrid cyclic phosphazene polymer/graphite anodes, where the phosphazene serves as distributed loci for Li deposition, has been investigated. Capacity within the hybrid system was found to occur reversibly in distinct regions. At the most positive voltages, above 0.06 V vs Li/Li+, the capacity was associated mostly with Li+ intercalation into graphite. In the most negative region, deposition of Li within the polymer was the predominate mechanism. A transitional region is inferred by the data whereby bulk aggregation or clustering of Li atoms occurs in proximity to the phosphazene sites that then serve as a template for more widespread population of Li within the anode at higher voltages, akin to a nucleation process. In full cells with a mixed oxide cathode, controlling the extent of Li deposition by limiting the charging voltage to 4.45 V enabled repeated cycling with no loss in capacity. Capacities as high as 183 mAh g-1 have been achieved for systems containing as little as 10% graphite while retaining coulombic efficiencies of 98% over 50 cycles. This level of cycling equates to the deposition of 7.4 Li per cyclic phosphazene.

  7. Solution-processed copper-nickel nanowire anodes for organic solar cells

    NASA Astrophysics Data System (ADS)

    Stewart, Ian E.; Rathmell, Aaron R.; Yan, Liang; Ye, Shengrong; Flowers, Patrick F.; You, Wei; Wiley, Benjamin J.

    2014-05-01

    This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper-nickel nanowire films exhibited efficiencies of 4.9%.This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper-nickel nanowire films exhibited efficiencies of 4.9%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01024h

  8. The history of progress in dimensionally stable anodes

    NASA Astrophysics Data System (ADS)

    Duby, Paul

    1993-03-01

    This article provides a brief history of dimensionally stable anodes by reviewing innovations in the chlor-alkali industry, electroplating and electrogalvanizing, and electrowinning. These anodes are attractive for numerous reasons (e.g.,.long life and reduced energy consumption), but they must still overcome the hurdle of cost togain wider acceptance for applications in the metallurgical process industries.

  9. Fundamental Investigation of Silicon Anode in Lithium-Ion Cells

    NASA Technical Reports Server (NTRS)

    Wu, James J.; Bennett, William R.

    2012-01-01

    Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is 10 times of graphite and it is an abundant element on Earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. Understanding solid electrolyte interphase (SEI) formation along with the lithium ion insertion/de-insertion kinetics in silicon anodes will provide greater insight into overcoming these issues, thereby lead to better cycle performance. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of a Si anode during the first cycle; the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes, and the combination of cyclic voltammetry with impedance spectroscopy provides a useful tool to evaluate the effectiveness of the design modifications on the Si anode performance.

  10. Electrolytic production of high purity aluminum using inert anodes

    DOEpatents

    Ray, Siba P.; Liu, Xinghua; Weirauch, Jr., Douglas A.

    2001-01-01

    A method of producing commercial purity aluminum in an electrolytic reduction cell comprising inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The inert anodes used in the process preferably comprise a cermet material comprising ceramic oxide phase portions and metal phase portions.

  11. Tubular bamboo charcoal for anode in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Li, Jun; Ye, Dingding; Zhu, Xun; Liao, Qiang; Zhang, Biao

    2014-12-01

    The anode material plays a significant role in determining the performance of microbial fuel cells (MFCs). In this study, the bamboo charcoal tube is proposed as a novel anode substrate by carbonizing the natural bamboo. Its surface functional groups, biocompatibility and internal resistance are thoroughly investigated. Performance of the MFCs with a conventional graphite tube anode and a bamboo charcoal tube anode is also compared. The results indicate that the tubular bamboo charcoal anode exhibits advantages over the graphite tube anode in terms of rougher surface, superior biocompatibility and smaller total internal resistance. Moreover, the X-ray photoelectron spectroscopy (XPS) analysis for the bamboo charcoal reveals that the introduced C-N bonds facilitate the electron transfer between the biofilm and electrodes. As a result, the MFC with a bamboo charcoal tube anode achieves a 50% improvement in the maximum power density over the graphite tube case. Furthermore, scale-up of the bamboo charcoal tube anode is demonstrated by employing a bundle of tubular bamboo charcoal to reach higher power output.

  12. Carbon paint anode for reinforced concrete bridges in coastal environments

    SciTech Connect

    Cramer, Stephen D.; Bullard, Sophie J.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Russell, James H.; Cryer, C.B.; Laylor, H.M.

    2002-01-01

    Solvent-based acrylic carbon paint anodes were installed on the north approach spans of the Yaquina Bay Bridge (Newport OR) in 1985. The anodes continue to perform satisfactorily after more than 15 years service. The anodes were inexpensive to apply and field repairs are easily made. Depolarization potentials are consistently above 100 mV with long-term current densities around 2 mA/m 2. Bond strength remains adequate, averaging 0.50 MPa (73 psi). Some deterioration of the anode-concrete interface has occurred in the form of cracks and about 4% of the bond strength measurements indicated low or no bond. Carbon anode consumption appears low. The dominant long-term anode reaction appears to be chlorine evolution, which results in limited further acidification of the anode-concrete interface. Chloride profiles were depressed compared to some other coastal bridges suggesting chloride extraction by the CP system. Further evidence of outward chloride migration was a flat chloride profile between the anode and the outer rebar.

  13. Electrolytic production of high purity aluminum using ceramic inert anodes

    DOEpatents

    Ray, Siba P.; Liu, Xinghua; Weirauch, Douglas A.; DiMilia, Robert A.; Dynys, Joseph M.; Phelps, Frankie E.; LaCamera, Alfred F.

    2002-01-01

    A method of producing commercial purity aluminum in an electrolytic reduction cell comprising ceramic inert anodes is disclosed. The method produces aluminum having acceptable levels of Fe, Cu and Ni impurities. The ceramic inert anodes used in the process may comprise oxides containing Fe and Ni, as well as other oxides, metals and/or dopants.

  14. Virtual cathode microwave generator having annular anode slit

    DOEpatents

    Kwan, Thomas J. T.; Snell, Charles M.

    1988-01-01

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.

  15. Results from a pilot cell test of cermet anodes

    SciTech Connect

    Windisch, Jr, C F; Strachan, D M; Henager, Jr, C H; Greenwell, E N; Alcorn, T R

    1992-08-01

    Goal was to develop long-lasting, energy-efficient anodes for Hall-Heroult cells used to produce Al metal. The anodes were made from a ceramic/metal composite consisting of NiO and NiFe{sub 2}O{sub 4} and a Cu/Ni metal phase. Thirteen cermet anodes were tested at Reynolds Metals Co., Muscle Shoals, AL. All anodes corroded severely during the pilot test. Electrolyte components were found deep within the anodes. However, there were many deficiencies in the pilot cell test, mainly the failure to maintain optimal operating conditions. It is concluded that there is a variety of fabrication and operational considerations that need to be addressed carefully in any future testing. 118 figs, 16 tabs, 17 refs.(DLC)

  16. Experiences in retrofitting sacrificial anodes in offshore Arabian Gulf

    SciTech Connect

    Kiefer, J.H.; Thomason, W.H.; Alansari, N.G.

    1998-12-31

    An analysis was made of the cathodic protection systems of fifteen (15) fixed offshore platforms. These steel template structures are located in the warm waters off the coast of the United Arab Emirates with water depth varying between 125 and 185 feet. The operator employs a systematic survey program to monitor the corrosion protection systems including the assessment of sacrificial anode depletion, and measurement of the anode and platform potentials. These data are used to design new anode retrofits for the older structures to extend the life of the CP systems. This paper presents an analysis of the field survey measurements, the method used to evaluate when new anodes are required, how many are needed, and where to locate retrofit anodes.

  17. Natural gas anodes for aluminium electrolysis in molten fluorides.

    PubMed

    Haarberg, Geir Martin; Khalaghi, Babak; Mokkelbost, Tommy

    2016-08-15

    Industrial primary production of aluminium has been developed and improved over more than 100 years. The molten salt electrolysis process is still suffering from low energy efficiency and considerable emissions of greenhouse gases (CO2 and PFC). A new concept has been suggested where methane is supplied through the anode so that the CO2 emissions may be reduced significantly, the PFC emissions may be eliminated and the energy consumption may decrease significantly. Porous carbon anodes made from different graphite grades were studied in controlled laboratory experiments. The anode potential, the anode carbon consumption and the level of HF gas above the electrolyte were measured during electrolysis. In some cases it was found that the methane oxidation was effectively participating in the anode process. PMID:27210046

  18. Focused cathode design to reduce anode heating during vircator operation

    SciTech Connect

    Lynn, Curtis F.; Dickens, James C.; Neuber, Andreas A.

    2013-10-15

    Virtual cathode oscillators, or vircators, are a type of high power microwave device which operates based on the instability of a virtual cathode, or cloud of electrons, which forms when electron current injected into the drift tube exceeds the space charge limited current within the drift tube. Anode heating by the electron beam during vircator operation ultimately limits achievable pulse lengths, repetition rates, and the duration of burst mode operation. This article discusses a novel cathode design that focuses electrons through holes in the anode, thus significantly reducing anode heating by the electrons emitted from the cathode during the first transit through the A-K gap. Reflexing electrons continue to deposit energy on the anode; however, the discussed minimization of anode heating by main beam electrons has the potential to enable higher repetition rates as well as efficiency and longer diode lifetime. A simulation study of this type of cathode design illustrates possible advantages.

  19. Interfacial chemistry of zinc anodes for reinforced concrete structures

    SciTech Connect

    Covino, B.S. Jr.; Bullard, S.J.; Cramer, S.D.; Holcomb, G.R.; McGill, G.E.; Cryer, C.B.; Stoneman, A.; Carter, R.R.

    1997-12-01

    Thermally-sprayed zinc anodes are used in both galvanic and impressed current cathodic protection systems for reinforced concrete structures. The Albany Research Center, in collaboration with the Oregon Department of Transportation, has been studying the effect of electrochemical aging on the bond strength of zinc anodes for bridge cathodic protection systems. Changes in anode bond strength and other anode properties can be explained by the chemistry of the zinc-concrete interface. The chemistry of the zinc-concrete interface in laboratory electrochemical aging studies is compared with that of several bridges with thermal-sprayed zinc anodes and which have been in service for 5 to 10 years using both galvanic and impressed current cathodic protection systems. The bridges are the Cape Creek Bridge on the Oregon coast and the East Camino Undercrossing near Placerville, CA. Also reported are interfacial chemistry results for galvanized steel rebar from the 48 year old Longbird Bridge in Bermuda.

  20. Carbon-Coated, Diatomite-Derived Nanosilicon as a High Rate Capable Li-ion Battery Anode

    PubMed Central

    Campbell, Brennan; Ionescu, Robert; Tolchin, Maxwell; Ahmed, Kazi; Favors, Zachary; Bozhilov, Krassimir N.; Ozkan, Cengiz S.; Ozkan, Mihrimah

    2016-01-01

    Silicon is produced in a variety of ways as an ultra-high capacity lithium-ion battery (LIB) anode material. The traditional carbothermic reduction process required is expensive and energy-intensive; in this work, we use an efficient magnesiothermic reduction to convert the silica-based frustules within diatomaceous earth (diatomite, DE) to nanosilicon (nanoSi) for use as LIB anodes. Polyacrylic acid (PAA) was used as a binder for the DE-based nanoSi anodes for the first time, being attributed for the high silicon utilization under high current densities (up to 4C). The resulting nanoSi exhibited a high BET specific surface area of 162.6 cm2 g−1, compared to a value of 7.3 cm2 g−1 for the original DE. DE contains SiO2 architectures that make ideal bio-derived templates for nanoscaled silicon. The DE-based nanoSi anodes exhibit good cyclability, with a specific discharge capacity of 1102.1 mAh g−1 after 50 cycles at a C-rate of C/5 (0.7 A gSi−1) and high areal loading (2 mg cm−2). This work also demonstrates the fist rate capability testing for a DE-based Si anode; C-rates of C/30 - 4C were tested. At 4C (14.3 A gSi−1), the anode maintained a specific capacity of 654.3 mAh g−1 – nearly 2x higher than graphite’s theoretical value (372 mAh g−1). PMID:27713474

  1. Carbon-Coated, Diatomite-Derived Nanosilicon as a High Rate Capable Li-ion Battery Anode

    NASA Astrophysics Data System (ADS)

    Campbell, Brennan; Ionescu, Robert; Tolchin, Maxwell; Ahmed, Kazi; Favors, Zachary; Bozhilov, Krassimir N.; Ozkan, Cengiz S.; Ozkan, Mihrimah

    2016-10-01

    Silicon is produced in a variety of ways as an ultra-high capacity lithium-ion battery (LIB) anode material. The traditional carbothermic reduction process required is expensive and energy-intensive; in this work, we use an efficient magnesiothermic reduction to convert the silica-based frustules within diatomaceous earth (diatomite, DE) to nanosilicon (nanoSi) for use as LIB anodes. Polyacrylic acid (PAA) was used as a binder for the DE-based nanoSi anodes for the first time, being attributed for the high silicon utilization under high current densities (up to 4C). The resulting nanoSi exhibited a high BET specific surface area of 162.6 cm2 g‑1, compared to a value of 7.3 cm2 g‑1 for the original DE. DE contains SiO2 architectures that make ideal bio-derived templates for nanoscaled silicon. The DE-based nanoSi anodes exhibit good cyclability, with a specific discharge capacity of 1102.1 mAh g‑1 after 50 cycles at a C-rate of C/5 (0.7 A gSi‑1) and high areal loading (2 mg cm‑2). This work also demonstrates the fist rate capability testing for a DE-based Si anode; C-rates of C/30 - 4C were tested. At 4C (14.3 A gSi‑1), the anode maintained a specific capacity of 654.3 mAh g‑1 – nearly 2x higher than graphite’s theoretical value (372 mAh g‑1).

  2. Using fuel cells or anode depolarization to reduce electrowinning energy consumption

    SciTech Connect

    Cook, G.M.

    1985-01-01

    Some existing and proposed metal electrowinning plant sites have hydrogen available to reduce the need for purchased energy. Hydrogen can reduce the energy consumption of electrowinning processes by depolarizing the anode; alternatively, it can be used in a fuel cell to generate dc electricity and heat at high efficiency. The use of H/sub 2/ to depolarize an anode in zinc electrowinning has been shown to reduce overall cell voltage by nearly 2 volts at 450 A/m/sup 2/. In a fuel cell, electricity can be produced with an efficiency of about 45 to 50% compared to about 30 to 32% for conventional generating equipment and the heat produced is available at temperatures which vary from about 150/sup 0/C for phosphoric acid fuel cells to 550 to 800/sup 0/C for advanced high temperature fuel cell systems. This paper examines the increased complexity that the depolarized anode and molten carbonate fuel cell technologies impose upon the electrowinning process, assesses the extent of energy savings that are available, and provides insight into the impact on capital and operating costs. 7 references.

  3. Synthesis of coral-like tantalum oxide films via anodization in mixed organic-inorganic electrolytes.

    PubMed

    Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Sun, Hongwei; Huo, Mingxin

    2013-01-01

    We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two-electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%.

  4. Electrochemical Fabrication of ZnO Nanowires in Anodized Aluminum Template Using Cyclic Voltammetry

    NASA Astrophysics Data System (ADS)

    Koney, Shalini Katyayani

    This thesis work studies in detail the fabrication ZnO in Anodic Aluminum Template using Cyclic Voltammetry which is one of the electrochemical deposition methods. In this current work the Aluminum is anodized in Oxalic and Sulphuric acids for different timings with constant current density of 10mA/cm 2. The hexagonal pores were observed after the anodization process. The pores are filled with Zinc using the Cyclic Voltammetry Method of Electrochemical deposition. The samples are then oxidized at 300°C to form the Zinc oxide nanowires. The presence of Zinc is tested using various techniques like Atomic Force Microscopy and Scanning Electron Microscopy which shows the presence of Zinc in the pores. To analytically prove the presence of Zinc Optical Spectroscopy is used. The absorption and reflection spectrums are studied to determine the presence of Zinc Oxide. The Zinc Oxide film was found to have strong absorbance at 0.50 at 340 nm. The thickness of the oxide layer is determined as 354.3 nm. The band gap of the Zinc oxide was found to be at 3.23eV.

  5. Anodic oxidation of o-nitrophenol on BDD electrode: variable effects and mechanisms of degradation.

    PubMed

    Rabaaoui, Nejmeddine; Saad, Mohamed El Khames; Moussaoui, Younes; Allagui, Mohamed Salah; Bedoui, Ahmed; Elaloui, Elimame

    2013-04-15

    The electrochemical oxidation of pesticide, o-nitrophenol (ONP) as one kind of pesticide that is potentially dangerous and biorefractory, was studied by galvanostatic electrolysis using boron-doped diamond (BDD) as anode. The influence of several operating parameters, such as applied current density, supporting electrolyte, and initial pH value, was investigated. The best degradation occurred in the presence of Na2SO4 (0.05 M) as conductive electrolyte. After 8h, nearly complete degradation of o-nitrophenol was achieved (92%) using BDD electrodes at pH 3 and at current density equals 60 mA cm(-2). The decay kinetics of o-nitrophenol follows a pseudo-first-order reaction. Aromatic intermediates such as catechol, resorcinol, 1,2,4-trihydroxybenzene, hydroquinone and benzoquinone and carboxylic acids such as maleic glycolic, malonic, glyoxilic and oxalic, have been identified and followed during the ONP treatment by chromatographic techniques. From these anodic oxidation by-products, a plausible reaction sequence for ONP mineralization on BDD anodes is proposed. PMID:23500425

  6. Development of biologically modified anodes for energy harvesting using microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Sumner, James J.; Ganguli, Rahul; Chmelka, Brad

    2012-06-01

    Biological fuel cells hold promise as an alternative energy source to batteries for unattended ground sensor applications due to the fact that they can be extremely long lived. This lifetime can be extended over batteries by scavenging fuel from the deployed environment. Microbial fuel cells (MFC) are one class of such sources that produce usable energy from small organic compounds (i.e. sugars, alcohols, organic acids, and biopolymers) which can be easily containerized or scavenged from the environment. The use of microorganisms as the anodic catalysts is what makes these systems unique from other biofuel cell designs. One of the main drawbacks of engineering a sensor system powered by an MFC is that power densities and current flux are extremely low in currently reported systems. The power density is limited by the mass transfer of the fuel source to the catalyst, the metabolism of the microbial catalysts and the electron transfer from the organism to the anode. This presentation will focus on the development of a new style of microbially-modified anodes which will increase power density to a level where a practical power source can be engineered. This is being achieved by developing a three dimensional matrix as an artificial, conductive biofilm. These artificial biofilms will allow the capture of a consortium of microbes designed for efficient metabolism of the available fuel source. Also it will keep the microbes close to the electrode allowing ready access by fuel and providing a low resistance passage of the liberated electrons from fuel oxidation.

  7. Characterization of calcium phosphate deposited on valve metal by anodic oxidation with polarity inversion.

    PubMed

    Okawa, Seigo; Homma, Kikuo; Kanatani, Mitsugu; Watanabe, Kouichi

    2009-07-01

    Electrochemical deposition of calcium phosphate (CAP) on valve metals such as Ta, Nb, and Zr, was performed by anodic oxidation with alternate polarity inversion at an applied 20 VDC. A saturated hydroxyapatite(HAP)-phosphoric acid solution (pH 3) was used as the electrolyte. FTIR, XRD, and XPS were employed to investigate the detailed characteristics of the deposition. HAP was precipitated on Ta; HAP including brushite and monetite on Nb; and HAP and monetite on Zr. The Ca/P atomic ratios were 1.3-1.5 by XPS, and HPO(4)(2- )bands were detected on Ta by FTIR. Therefore, the HAP precipitated on Ta was a Ca-deficient HAP. In addition, the XPS spectra of the specimens showed that phosphate ions were incorporated into the anodic oxide film. Deposits with nano-grain size were observed by AFM. The results confirmed that CAP with nano-grain size was deposited on valve metals by the anodic oxidation with polarity inversion. PMID:19721291

  8. Synthesis of Coral-Like Tantalum Oxide Films via Anodization in Mixed Organic-Inorganic Electrolytes

    PubMed Central

    Yu, Hongbin; Zhu, Suiyi; Yang, Xia; Wang, Xinhong; Sun, Hongwei; Huo, Mingxin

    2013-01-01

    We report a simple method to fabricate nano-porous tantalum oxide films via anodization with Ta foils as the anode at room temperature. A mixture of ethylene glycol, phosphoric acid, NH4F and H2O was used as the electrolyte where the nano-porous tantalum oxide could be synthesized by anodizing a tantalum foil for 1 h at 20 V in a two–electrode configuration. The as-prepared porous film exhibited a continuous, uniform and coral-like morphology. The diameters of pores ranged from 30 nm to 50 nm. The pores interlaced each other and the depth was about 150 nm. After calcination, the as-synthesized amorphous tantalum oxide could be crystallized to the orthorhombic crystal system. As observed in photocatalytic experiments, the coral-like tantalum oxide exhibited a higher photocatalytic activity for the degradation of phenol than that with a compact surface morphology, and the elimination rate of phenol increased by 66.7%. PMID:23799106

  9. On the variation in the electrical properties and ac conductivity of through-thickness nano-porous anodic alumina with temperature

    NASA Astrophysics Data System (ADS)

    Tahir, Mahmood; Mehmood, Mazhar; Nadeem, Muhammad; Waheed, Abdul; Tanvir, Muhammad Tauseef

    2013-09-01

    The electrical response of self-organized through-thickness anodic alumina with hexagonal arrangement of cylindrical pores has been studied as a function of temperature. Mechanically stable thick porous anodic alumina was prepared, by through-thickness anodic oxidation of aluminum sheet in sulfuric acid, with extremely high aspect ratio pores exhibiting fairly uniform diameter and interpore distance. It was observed that the electrical properties of through-thickness anodic alumina are very sensitive to minute changes in temperature and the role of surface conductivity in governing its electrical response cannot be overlooked. At high frequencies, intrinsic dielectric response of anodic alumina was dominant. The frequency-dependent conductivity behavior at low and intermediate frequencies was explained on the basis of correlated barrier hopping (CBH) and quantum mechanical tunneling (QMT) models, respectively. Experimental data was modeled using an equivalent circuit consisting of Debye circuit, for bulk alumina, parallel to surface conduction path. The surface conduction was primarily based on two circuits in series, each with a parallel arrangement of a resistor and a constant phase element. This suggested heterogeneity in alumina pore surface, possibly related with islands of physisorbed water separated by the regions of chemisorbed water. Temperature dependence of some circuit elements has been analyzed to express different charge migration phenomena occurring in nano-porous anodic alumina.

  10. Heterostructure composites of rGO/GeO2/PANI with enhanced performance for Li ion battery anode material

    NASA Astrophysics Data System (ADS)

    Sarkar, Sumanta; Borah, Rohan; Santhosha, A. L.; Dhanya, R.; Narayana, Chandrabhas; Bhattacharyya, Aninda J.; Peter, Sebastian C.

    2016-02-01

    A novel solvothermal method has been used for the synthesis of porous ellipsoidal GeO2 particles with oleic acid and oleylamine as solvent and co-surfactant, respectively and its performance has been studied as an anode material for Li ion battery applications. The presence of highly hydrophobic oleic acid and oleylamine on the surface of the as synthesized sample imparts a detrimental effect on its performance. Although removal of the capping agents with glacial acetic acid improves the performance to some extent, a drastic enhancement in both the specific capacity and cycling stability is observed when the nanoparticles are wrapped with rGO/PANI composites at low temperature.

  11. Anodic deprotonation of polyaniline films in alcohol solutions

    SciTech Connect

    Susumu Kuwabata, Nobuo Kihira ); Hiroshi Yoneyama

    1993-05-01

    Polyaniline films prepared by electrochemical oxidation of aniline possess high redox activities both in aqueous acidic and in nonaqueous solutions. The high durability of the film against the redox cycling opens applications of this material to electrochromic and electronic devices and cathode-active materials of rechargeable lithium batteries. Polyaniline films immersed in alcohol solutions such as methanol, ethanol, 1-propanol, and 2-propanol are deprotonated by applying anodic potentials. The potential at which the deprotonation reaction is induced to occur is the most negative at methanol among the above four kinds of alcohols used, and ethanol, 1-propanol, and 2-propanol follow in this order. This finding is quantitatively discussed in terms of the difference of the affinity of the solvent for the protonated polyaniline. An equation to predict the potential at which the conductance of polyaniline is decreased to one-half of the highest conductance by the deprotonation is derived, and the validity of the equation is verified for results obtained both in aqueous solutions of different pH values and in the above alcohol solutions. 26 refs., 9 figs.

  12. Development of anode zone using dual-anode system to reduce organic matter crossover in membraneless microbial fuel cells.

    PubMed

    Kim, Jisu; Kim, Bongkyu; An, Junyeong; Lee, Yoo Seok; Chang, In Seop

    2016-08-01

    To prevent the occurrence of the organic crossover in membraneless microbial fuel cells (ML-MFCs), dual-anode MFC (DA-MFC) was designed from multi-anode concept to ensure anode zone. The anode zone addressed increase the utilization of organic matter in ML-MFCs, as the result, the organic crossover was prevented and performance of MFCs were enhanced. The maximum power of the DA-MFC was 0.46mW, which is about 1.56 times higher than the ML-MFC (0.29mW). Furthermore, the DA-MFC had advantage in correlation of organic substance concentration and dissolved oxygen concentration, and even electric over-potential. In addition, in terms of cathode fouling, the DA-MFC showed clearer surface. Hence, the anode zone should be considered in the advanced ML-MFC for practically use in wastewater treatment process, and also for scale-up of MFCs.

  13. An analytical model for liquid-anode and vapor-anode AMTEC converters

    SciTech Connect

    Tournier, Jean-Michel; El-Genk, Mohamed S.; Schuller, Michael; Hausgen, Paul

    1997-01-10

    This paper describes a lumped analytical model of liquid-anode single-tube and vapor-anode multi-tube AMTEC cells. The model results agreed well with experimental data for Mo, NbN and TiN electrodes. Results showed that Mo and NbN electrodes exhibit high B values between 400 and 600 A.K{sup 1/2}/Pa.m{sup 2}, and have the potential for peak power densities slightly above 1 W/cm{sup 2}, with efficiencies as high as 28%. In contrast, TiN electrodes have lower temperature-independent exchange currents, between 120 and 135 A.K{sup 1/2}/Pa.m{sup 2}, lower peak power densities between 0.5 and 0.75 W/cm{sup 2}, and efficiencies below 24% at a BASE temperature of 1200 K. These values of B compare well with that reported by other investigators.

  14. A dual anode nickel-hydrogen cell

    NASA Astrophysics Data System (ADS)

    Gahn, Randall F.; Ryan, Timothy P.

    1992-02-01

    A dual anode cell with decreased polarization effects provides improved performance characteristics, such as voltage characteristics and depth-of-discharge characteristics. A hydrogen electrode is placed on both sides of a nickel electrode. An electrolyte saturated separator is placed between each hydrogen electrode and the nickel electrode. The electrolyte saturated separator can be a layered-type separator consisting of one layer of zirconia knit cloth next to the hydrogen electrode and a layer of radiation-grafted polyethylene film next to the nickel electrode. These layers of the electrochemical cell are cut in a pineapple-slice configuration. Both hydrogen electrodes are connected in parallel to form a single electrical node. The electrochemical cell is placed in a vessel pressurized with hydrogen and saturated with a potassium hydroxide electrolyte. A gas screen is placed on the outer surface of each of the hydrogen electrodes.

  15. Surface roughness of anodized titanium coatings.

    SciTech Connect

    Dugger, Michael Thomas; Chinn, Douglas Alan

    2010-10-01

    Samples of grade five 6Al4V titanium alloy were coated with two commercial fluoropolymer anodizations (Tiodize and Canadize) and compared. Neither coating demonstrates significant outgassing. The coatings show very similar elemental analysis, except for the presence of lead in the Canadize coating, which may account for its lower surface friction in humid environments. Surface roughness has been compared by SEM, contact profilometry, optical profilometry, power spectral density and bidirectional scattering distribution function (BSDF). The Tiodize film is slightly smoother by all measurement methods, but the Canadize film shows slightly less scatter at all angles of incidence. Both films exhibited initial friction coefficients of 0.2 to 0.4, increasing to 0.4 to 0.8 after 1000 cycles of sliding due to wear of the coating and ball. The coatings are very similar and should behave identically in most applications.

  16. Mechanisms of anode power deposition in a low pressure free burning arc

    NASA Technical Reports Server (NTRS)

    Soulas, George C.; Myers, Roger M.

    1994-01-01

    Anode power deposition is a dominant power loss mechanism for arc jets and MPD thrusters. In this study, a free burning arc experiment was operated at pressures and current densities similar to those in arc jets and MPD thrusters in an attempt to identify the physics controlling this loss mechanism. Use of a free burning arc allowed for the isolation of independent variables controlling anode power deposition and provided a convenient and flexible way to cover a broad range of currents, anode surface pressures, and applied magnetic field strengths and orientations using an argon gas. Test results showed that anode power deposition decreased with increasing anode surface pressure up to 6.7 Pa (0.05 torr) and then became insensitive to pressure. Anode power increased with increasing arc current while the electron number density near the anode surface increased linearity. Anode power also increased with increasing applied magnetic field strength due to an increasing anode fall voltage. Applied magnetic field orientation had an effect only at high currents and low anode surface pressures, where anode power decreased when applied field lines intercepted the anode surface. The results demonstrated that anode power deposition was dominated by the current carrying electrons and that the anode fall voltage was the largest contributor. Furthermore, the results showed that anode power deposition can be reduced by operating at increased anode pressures, reduced arc currents, and applied magnetic field strengths and with magnetic field lines intercepting the anode.

  17. ZIRCONIUM OXIDE NANOSTRUCTURES PREPARED BY ANODIC OXIDATION

    SciTech Connect

    Dang, Y. Y.; Bhuiyan, M.S.; Paranthaman, M. P.

    2008-01-01

    Zirconium oxide is an advanced ceramic material highly useful for structural and electrical applications because of its high strength, fracture toughness, chemical and thermal stability, and biocompatibility. If highly-ordered porous zirconium oxide membranes can be successfully formed, this will expand its real-world applications, such as further enhancing solid-oxide fuel cell technology. Recent studies have achieved various morphologies of porous zirconium oxide via anodization, but they have yet to create a porous layer where nanoholes are formed in a highly ordered array. In this study, electrochemical methods were used for zirconium oxide synthesis due to its advantages over other coating techniques, and because the thickness and morphology of the ceramic fi lms can be easily tuned by the electrochemical parameters, such as electrolyte solutions and processing conditions, such as pH, voltage, and duration. The effects of additional steps such as pre-annealing and post-annealing were also examined. Results demonstrate the formation of anodic porous zirconium oxide with diverse morphologies, such as sponge-like layers, porous arrays with nanoholes ranging from 40 to 75 nm, and nanotube layers. X-ray powder diffraction analysis indicates a cubic crystallographic structure in the zirconium oxide. It was noted that increased voltage improved the ability of the membrane to stay adhered to the zirconium substrate, whereas lower voltages caused a propensity for the oxide fi lm to fl ake off. Further studies are needed to defi ne the parameters windows that create these morphologies and to investigate other important characteristics such as ionic conductivity.

  18. Zirconium Oxide Nanostructures Prepared by Anodic Oxidation

    SciTech Connect

    Dang, Ying Yi; Bhuiyan, Md S; Paranthaman, Mariappan Parans

    2008-01-01

    Zirconium oxide is an advanced ceramic material highly useful for structural and electrical applications because of its high strength, fracture toughness, chemical and thermal stability, and biocompatibility. If highly-ordered porous zirconium oxide membranes can be successfully formed, this will expand its real-world applications, such as further enhancing solid-oxide fuel cell technology. Recent studies have achieved various morphologies of porous zirconium oxide via anodization, but they have yet to create a porous layer where nanoholes are formed in a highly ordered array. In this study, electrochemical methods were used for zirconium oxide synthesis due to its advantages over other coating techniques, and because the thickness and morphology of the ceramic films can be easily tuned by the electrochemical parameters, such as electrolyte solutions and processing conditions, such as pH, voltage, and duration. The effects of additional steps such as pre-annealing and post-annealing were also examined. Results demonstrate the formation of anodic porous zirconium oxide with diverse morphologies, such as sponge-like layers, porous arrays with nanoholes ranging from 40 to 75 nm, and nanotube layers. X-ray powder diffraction analysis indicates a cubic crystallographic structure in the zirconium oxide. It was noted that increased voltage improved the ability of the membrane to stay adhered to the zirconium substrate, whereas lower voltages caused a propensity for the oxide film to flake off. Further studies are needed to define the parameters windows that create these morphologies and to investigate other important characteristics such as ionic conductivity.

  19. Mechanistic aspects of phenol electrochemical degradation by oxidation on a Ta/PbO{sub 2} anode

    SciTech Connect

    Tahar, N.B.; Savall, A.

    1998-10-01

    The electrochemical oxidation of phenol in an aqueous solution is a complex transformation involving several transfer steps of oxygen atoms and electrons. Transfer of the oxygen atom occurs through the intermediary of hydroxyl radicals adsorbed on the active sites of the anode. Galvanostatic electrolyses of phenol (10.5 to 105 mmol/dm{sup 3}) in aqueous solution at pH 2 on a Ta/PbO{sub 2} anode were followed by high-pressure liquid chromatography and by analysis of the total organic carbon. Hydroquinone, catechol, 1,4-benzoquinone (1,4-BQ), maleic and fumaric acids, and carbon dioxide are the main products. The nonidentified products consist mainly of polymers. Study of the influence of temperature shows that the rate consumption of phenol initially at 21 mmol/dm{sup 3} is mass transport limited. CO{sub 2} is immediately formed following the 1,4-BQ-maleic acid pathway involving 20 faradays and forming 4 mol of CO{sub 2} and/or the 1,4-BQ-intermediary in C2 pathway at 16 faradays with formation of 2 mol of CO{sub 2}. The faradaic yield values show that a phenol molecule adsorbed on a catalytic site undergoes a succession of oxidation steps involving, on average, five electrons without desorption of the intermediate products. This number of electrons varies according to the operating conditions (temperature, anodic current density, initial phenol concentration, hydrodynamic conditions, etc.). The mean faradaic yield decreases during electrolysis; it can reach 70% at the beginning of electrolysis of a 21 mmol/dm{sup 3} phenol solution for an anodic current density of 100 mA/cm{sup 2}. The phenol conversion into insoluble polymers increases as a function of its initial concentration and the anodic current density but it does not exceed 10%.

  20. Lead electrowinning in a fluoborate medium. Use of hydrogen diffusion anodes

    NASA Astrophysics Data System (ADS)

    Expósito, E.; González-García, J.; Bonete, P.; Montiel, V.; Aldaz, A.

    The results of an investigation of the electrowinning of lead employing a fluoboric acid bath are reported. The electrodeposition lead reaction was studied by voltammetric methods and scanning electron microscopy (SEM) microphotographs of the electrodeposited lead were taken. The effects of current density, temperature, catholyte flow and H + concentration were investigated on a laboratory scale to optimise operating conditions. Finally, the substitution of the traditionally used Dimensionally Stable Anode (DSA) by a Hydrogen Diffusion Electrode (HDE) was made in order to decrease the energy consumption (EC) of the overall process.

  1. Direct electrodeposition of Cu2Sb for lithium-ion battery anodes.

    PubMed

    Mosby, James M; Prieto, Amy L

    2008-08-13

    We describe the direct single potential electrodeposition of crystalline Cu2Sb, a promising anode material for lithium-ion batteries, from aqueous solutions at room temperature. The use of citric acid as a complexing agent increases the solubility of antimony salts and shifts the reduction potentials of copper and antimony toward each other, enabling the direct deposition of the intermetallic compound at pH 6. Electrodeposition of Cu2Sb directly onto conducting substrates represents a facile synthetic method for the synthesis of high quality samples with excellent electrical contact to a substrate, which is critical for further battery testing. PMID:18627144

  2. A high performance hybrid battery based on aluminum anode and LiFePO4 cathode

    DOE PAGES

    Sun, Xiao-Guang; Bi, Zhonghe; Liu, Hansan; Bridges, Craig A.; Paranthaman, Mariappan Parans; Dai, Sheng; Brown, Gilbert M.

    2015-12-07

    A unique battery hybrid utilizes an aluminum anode, a LiFePO4 cathode and an acidic ionic liquid electrolyte based on 1-ethyl-3-methylimidazolium chloride (EMImCl) and aluminum trichloride (AlCl 3) (EMImCl-AlCl 3, 1-1.1 in molar ratio) with or without LiAlCl4 is proposed. This hybrid ion battery delivers an initial high capacity of 160 mAh g-1 at a current rate of C/5. It also shows good rate capability and cycling performance.

  3. Practical Electrochemical Anodic Oxidation of Polycyclic Lactams for Late Stage Functionalization**

    PubMed Central

    Frankowski, Kevin J.; Liu, Ruzhang; Milligan, Gregory L.; Moeller, Kevin D.

    2015-01-01

    Electrochemistry provides a powerful tool for the late-stage functionalization of complex lactams. A two-stage protocol for converting lactams, many of which are preparable through the intramolecular Schmidt reaction of keto azides, is presented. In the first step, anodic oxidation in MeOH using a repurposed power source provides a convenient route to lactams bearing a methoxy group adjacent to nitrogen. Treatment of these intermediates with a Lewis acid in DCM permits the regeneration of a reactive acyliminium ion that is then reacted with a range of nucleophilic species. PMID:26371961

  4. A high performance hybrid battery based on aluminum anode and LiFePO4 cathode.

    PubMed

    Sun, Xiao-Guang; Bi, Zhonghe; Liu, Hansan; Fang, Youxing; Bridges, Craig A; Paranthaman, M Parans; Dai, Sheng; Brown, Gilbert M

    2016-01-28

    A novel hybrid battery utilizing an aluminum anode, a LiFePO4 cathode and an acidic ionic liquid electrolyte based on 1-ethyl-3-methylimidazolium chloride (EMImCl) and aluminum trichloride (AlCl3) (EMImCl-AlCl3, 1-1.1 in molar ratio) with or without LiAlCl4 is proposed. The hybrid ion battery delivers an initial high capacity of 160 mA h g(-1) at a current rate of C/5. It also shows good rate capability and cycling performance.

  5. Effect of nitro substituent on electrochemical oxidation of phenols at boron-doped diamond anodes.

    PubMed

    Jiang, Yi; Zhu, Xiuping; Li, Hongna; Ni, Jinren

    2010-02-01

    In order to investigate nitro-substitutent's effect on degradation of phenols at boron-doped diamond (BDD) anodes, cyclic voltammetries of three nitrophenol isomers: 2-nitrophenol (2NP), 3-nitrophenol (3NP) and 4-nitrophenol (4NP) were studied, and their bulk electrolysis results were compared with phenol's (Ph) under alkaline condition. The voltammetric study showed nitrophenols could be attacked by hydroxyl radicals and nitro-group was released from the aromatic ring. Results of bulk electrolysis showed degradation of all phenols were fit to a pseudo first-order equation and followed in this order: 2NP>4NP>3NP>Ph. Molecular structures, especially carbon atom charge, significantly influenced the electrochemical oxidation of these isomers. Intermediates were analyzed during the electrolysis process, and were mainly catechol, resorcinol, hydroquinone, and carboxylic acids, such as acetic acid and oxalic acid. A simple degradation pathway was proposed. Moreover, a linear increasing relationship between degradation rates and Hammett constants of the studied phenols was observed, which demonstrated that electrochemical oxidation of these phenols was mainly initiated by electrophilic attack of hydroxyl radicals at BDD anodes.

  6. Surface characteristics and bioactivity of an anodized titanium surface

    PubMed Central

    Kim, Kyul; Lee, Bo-Ah; Piao, Xing-Hui; Chung, Hyun-Ju

    2013-01-01

    Purpose The aim of this study was to evaluate the surface properties and biological response of an anodized titanium surface by cell proliferation and alkaline phosphatase activity analysis. Methods Commercial pure titanium (Ti) disks were prepared. The samples were divided into an untreated machined Ti group and anodized Ti group. The anodization of cp-Ti was formed using a constant voltage of 270 V for 60 seconds. The surface properties were evaluated using scanning electron microscopy, X-ray photoelectron spectroscopy, and an image analyzing microscope. The surface roughness was evaluated by atomic force microscopy and a profilometer. The contact angle and surface energy were analyzed. Cell adhesion, cell proliferation, and alkaline phosphatase activity were evaluated using mouse MC3T3-E1 cells. Results The anodized Ti group had a more porous and thicker layer on its surface. The surface roughness of the two groups measured by the profilometer showed no significant difference (P>0.001). The anodized Ti dioxide (TiO2) surface exhibited better corrosion resistance and showed a significantly lower contact angle than the machined Ti surface (P>0.001). Although there was no significant difference in the cell viability between the two groups (P>0.001), the anodized TiO2 surface showed significantly enhanced alkaline phosphatase activity (P<0.001). Conclusions These results suggest that the surface modification of Ti by anodic oxidation improved the osteogenic response of the osteoblast cells. PMID:24040573

  7. Interconnected hollow carbon nanospheres for stable lithium metal anodes.

    PubMed

    Zheng, Guangyuan; Lee, Seok Woo; Liang, Zheng; Lee, Hyun-Wook; Yan, Kai; Yao, Hongbin; Wang, Haotian; Li, Weiyang; Chu, Steven; Cui, Yi

    2014-08-01

    For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g(-1)) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm(-2). The Coulombic efficiency improves to ∼ 99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes.

  8. Influence of anode surface chemistry on microbial fuel cell operation.

    PubMed

    Santoro, Carlo; Babanova, Sofia; Artyushkova, Kateryna; Cornejo, Jose A; Ista, Linnea; Bretschger, Orianna; Marsili, Enrico; Atanassov, Plamen; Schuler, Andrew J

    2015-12-01

    Self-assembled monolayers (SAMs) modified gold anodes are used in single chamber microbial fuel cells for organic removal and electricity generation. Hydrophilic (N(CH3)3(+), OH, COOH) and hydrophobic (CH3) SAMs are examined for their effect on bacterial attachment, current and power output. The different substratum chemistry affects the community composition of the electrochemically active biofilm formed and thus the current and power output. Of the four SAM-modified anodes tested, N(CH3)3(+) results in the shortest start up time (15 days), highest current achieved (225 μA cm(-2)) and highest MFC power density (40 μW cm(-2)), followed by COOH (150 μA cm(-2) and 37 μW cm(-2)) and OH (83 μA cm(-2) and 27 μW cm(-2)) SAMs. Hydrophobic SAM decreases electrochemically active bacteria attachment and anode performance in comparison to hydrophilic SAMs (CH3 modified anodes 7 μA cm(-2) anodic current and 1.2 μW cm(-2) MFC's power density). A consortium of Clostridia and δ-Proteobacteria is found on all the anode surfaces, suggesting a synergistic cooperation under anodic conditions.

  9. Atmospheric pressure arc discharge with ablating graphite anode

    SciTech Connect

    Nemchinsky, V. A.; Raitses, Y.

    2015-05-18

    The anodic carbon arc discharge is used to produce carbon nanoparticles. Recent experiments with the carbon arc at atmospheric pressure helium demonstrated the enhanced ablation rate for narrow graphite anodes resulting in high deposition rates of carbonaceous products on the copper cathode (Fetterman et al 2008 Carbon 46 1322–6). The proposed model explains these results with interconnected steady-state models of the cathode and the anode processes. When considering cathode functioning, the model predicts circulation of the particles in the near-cathode region: evaporation of the cathode material, ionization of evaporated atoms and molecules in the near-cathode plasma, return of the resulting ions to the cathode, surface recombination of ions and electrons followed again by cathode evaporation etc. In the case of the low anode ablation rate, the ion acceleration in the cathode sheath provides the major cathode heating mechanism. In the case of an intensive anode ablation, an additional cathode heating is due to latent fusion heat of the atomic species evaporated from the anode and depositing at the cathode. Using the experimental arc voltage as the only input discharge parameter, the model allows us to calculate the anode ablation rate. A comparison of the results of calculations with the available experimental data shows reasonable agreement.

  10. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2012-05-15

    A system is described for forming metal hydroxide from a metal carbonate utilizing a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate, in particular water-insoluble calcium carbonate or magnesium carbonate, is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide. Among other uses, the metal hydroxide formed can be employed to absorb acid gases such as carbon dioxide from a gas mixture. The invention can also generate hydrogen and oxidative gases such as oxygen or chlorine.

  11. Hydrogen evolution inhibitors for cells having zinc anodes

    SciTech Connect

    Przybyla, F.J.; Rossler, E.J.

    1980-03-25

    Hydrogen evolution in cells having zinc anodes is reduced or eliminated by incorporating in the cell a surfactant which is a complex phosphate ester of a surfactant of the ethylene oxide adduct type. This surfactant is added in such a manner that, directly or upon wetting of the anode by the electrolyte, there is an adsorption of surfactant on the surface of the zinc anode material, whereby hydrogen evolution is inhibited. The surfactant is desirably present in the cell in an amount of from 0.001% to 5% by weight of the zinc component of the cell

  12. Anodic electrosynthesis of some peroxy compounds on glassy carbon electrodes

    SciTech Connect

    Khomutov, N.E.; Zakhodyakina, N.A.; Svirida, L.V.; Nesvat, N.V.

    1987-11-10

    The authors present the results of a study of the anodic electrosynthesis of hydrogen peroxide and its derivatives on glassy carbon in solutions of sodium carbonate and sodium carbonate with sodium borate. We studied the kinetics of anodic processes on glassy carbon with the aid of polarization measurements and a method for determining the concentrations of active oxygen in the anolyte and the current efficiency. The current efficiencies with respect to active oxygen obtained on glassy carbon in the mixed solution of sodium borate and sodium carbonate are close to the current efficiencies which are observed on platinum anodes in the industrial electrosynthesis of perborates.

  13. Inert Anode Life in Low Temperature Reduction Process

    SciTech Connect

    Bradford, Donald R.

    2005-06-30

    The production of aluminum metal by low temperature electrolysis utilizing metal non-consumable anodes and ceramic cathodes was extensively investigated. Tests were performed with traditional sodium fluoride--aluminum fluoride composition electrolytes, potassium fluoride-- aluminum fluoride electrolytes, and potassium fluoride--sodium fluoride--aluminum fluoride electrolytes. All of the Essential First-Tier Requirements of the joint DOE-Aluminum Industry Inert Anode Road Map were achieved and those items yet to be resolved for commercialization of this technology were identified. Methods for the fabrication and welding of metal alloy anodes were developed and tested. The potential savings of energy and energy costs were determined and potential environmental benefits verified.

  14. Unstable behavior of anodic arc discharge for synthesis of nanomaterials

    NASA Astrophysics Data System (ADS)

    Gershman, Sophia; Raitses, Yevgeny

    2016-09-01

    A short carbon arc operating with a high ablation rate of the graphite anode exhibits a combined motion of the arc and the arc attachment to the anode. A characteristic time scale of this motion is in a 10‑3 s range. The arc exhibits a negative differential resistance before the arc motion occurs. Thermal processes in the arc plasma region interacting with the ablating anode are considered as possible causes of this unstable arc behavior. It is also hypothesized that the arc motion could potentially cause mixing of the various nanoparticles synthesized in the arc in the high ablation regime.

  15. Seawater piping systems designed with AISI 316 and RCP anodes

    SciTech Connect

    Valen, S.; Johnsen, R.; Gartland, P.O.; Drugli, J.M.

    1999-11-01

    Internal cathodic protection by resistor controlled anodes--Resistor controlled Cathodic Protection (RCP)--has been introduced as an alternative method for the prevention of localized corrosion of seawater transportation systems. More than 1000 RCP anodes have been installed in seawater piping systems made from highly alloyed stainless steel which previously had suffered from corrosion. The application of cheaper stainless steels like AISI 316 in combination with RCP anodes results in significant cost savings for the seawater system, and a few systems have been installed. This paper gives a short review of the theoretical background, and a presentation of the experience from some of the installations with these materials and RCP.

  16. Cobalt phosphide as a new anode material for sodium storage

    NASA Astrophysics Data System (ADS)

    Li, Wei-Jie; Yang, Qiu-Ran; Chou, Shu-Lei; Wang, Jia-Zhao; Liu, Hua-Kun

    2015-10-01

    A novel anode material for sodium ion batteries - nanosized CoP particles - was synthesized by a facile and productive ball-milling method. The CoP was tested as an anode candidate for sodium ion batteries. It delivered a high initial specific capacity of 770 mAh g-1, and excellent rate capability, demonstrating that CoP is a promising anode candidate for sodium ion storage. Ex-situ X-ray photoelectron spectroscopy and scanning transmission electron microscopy were carried out to investigate the sodium storage mechanism of CoP.

  17. Unstable behavior of anodic arc discharge for synthesis of nanomaterials

    NASA Astrophysics Data System (ADS)

    Gershman, Sophia; Raitses, Yevgeny

    2016-09-01

    A short carbon arc operating with a high ablation rate of the graphite anode exhibits a combined motion of the arc and the arc attachment to the anode. A characteristic time scale of this motion is in a 10-3 s range. The arc exhibits a negative differential resistance before the arc motion occurs. Thermal processes in the arc plasma region interacting with the ablating anode are considered as possible causes of this unstable arc behavior. It is also hypothesized that the arc motion could potentially cause mixing of the various nanoparticles synthesized in the arc in the high ablation regime.

  18. Fabrication of alumina films with laminated structures by ac anodization

    NASA Astrophysics Data System (ADS)

    Segawa, Hiroyo; Okano, Hironaga; Wada, Kenji; Inoue, Satoru

    2014-02-01

    Anodization techniques by alternating current (ac) are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50-200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials.

  19. Cu-Ni-Fe anodes having improved microstructure

    DOEpatents

    Bergsma, S. Craig; Brown, Craig W.

    2004-04-20

    A method of producing aluminum in a low temperature electrolytic cell containing alumina dissolved in an electrolyte. The method comprises the steps of providing a molten electrolyte having alumina dissolved therein in an electrolytic cell containing the electrolyte. A non-consumable anode and cathode is disposed in the electrolyte, the anode comprised of Cu--Ni--Fe alloys having single metallurgical phase. Electric current is passed from the anode, through the electrolyte to the cathode thereby depositing aluminum on the cathode, and molten aluminum is collected from the cathode.

  20. Na-Ion Battery Anodes: Materials and Electrochemistry.

    PubMed

    Luo, Wei; Shen, Fei; Bommier, Clement; Zhu, Hongli; Ji, Xiulei; Hu, Liangbing

    2016-02-16

    The intermittent nature of renewable energy sources, such as solar and wind, calls for sustainable electrical energy storage (EES) technologies for stationary applications. Li will be simply too rare for Li-ion batteries (LIBs) to be used for large-scale storage purposes. In contrast, Na-ion batteries (NIBs) are highly promising to meet the demand of grid-level storage because Na is truly earth abundant and ubiquitous around the globe. Furthermore, NIBs share a similar rocking-chair operation mechanism with LIBs, which potentially provides high reversibility and long cycling life. It would be most efficient to transfer knowledge learned on LIBs during the last three decades to the development of NIBs. Following this logic, rapid progress has been made in NIB cathode materials, where layered metal oxides and polyanionic compounds exhibit encouraging results. On the anode side, pure graphite as the standard anode for LIBs can only form NaC64 in NIBs if solvent co-intercalation does not occur due to the unfavorable thermodynamics. In fact, it was the utilization of a carbon anode in LIBs that enabled the commercial successes. Anodes of metal-ion batteries determine key characteristics, such as safety and cycling life; thus, it is indispensable to identify suitable anode materials for NIBs. In this Account, we review recent development on anode materials for NIBs. Due to the limited space, we will mainly discuss carbon-based and alloy-based anodes and highlight progress made in our groups in this field. We first present what is known about the failure mechanism of graphite anode in NIBs. We then go on to discuss studies on hard carbon anodes, alloy-type anodes, and organic anodes. Especially, the multiple functions of natural cellulose that is used as a low-cost carbon precursor for mass production and as a soft substrate for tin anodes are highlighted. The strategies of minimizing the surface area of carbon anodes for improving the first-cycle Coulombic efficiency are

  1. Na-Ion Battery Anodes: Materials and Electrochemistry.

    PubMed

    Luo, Wei; Shen, Fei; Bommier, Clement; Zhu, Hongli; Ji, Xiulei; Hu, Liangbing

    2016-02-16

    The intermittent nature of renewable energy sources, such as solar and wind, calls for sustainable electrical energy storage (EES) technologies for stationary applications. Li will be simply too rare for Li-ion batteries (LIBs) to be used for large-scale storage purposes. In contrast, Na-ion batteries (NIBs) are highly promising to meet the demand of grid-level storage because Na is truly earth abundant and ubiquitous around the globe. Furthermore, NIBs share a similar rocking-chair operation mechanism with LIBs, which potentially provides high reversibility and long cycling life. It would be most efficient to transfer knowledge learned on LIBs during the last three decades to the development of NIBs. Following this logic, rapid progress has been made in NIB cathode materials, where layered metal oxides and polyanionic compounds exhibit encouraging results. On the anode side, pure graphite as the standard anode for LIBs can only form NaC64 in NIBs if solvent co-intercalation does not occur due to the unfavorable thermodynamics. In fact, it was the utilization of a carbon anode in LIBs that enabled the commercial successes. Anodes of metal-ion batteries determine key characteristics, such as safety and cycling life; thus, it is indispensable to identify suitable anode materials for NIBs. In this Account, we review recent development on anode materials for NIBs. Due to the limited space, we will mainly discuss carbon-based and alloy-based anodes and highlight progress made in our groups in this field. We first present what is known about the failure mechanism of graphite anode in NIBs. We then go on to discuss studies on hard carbon anodes, alloy-type anodes, and organic anodes. Especially, the multiple functions of natural cellulose that is used as a low-cost carbon precursor for mass production and as a soft substrate for tin anodes are highlighted. The strategies of minimizing the surface area of carbon anodes for improving the first-cycle Coulombic efficiency are

  2. Performance of Solid Oxide Fuel Cell With La and Cr Co-doped SrTiO3 as Anode.

    PubMed

    Yi, Fenyun; Chen, Hongyu; Li, He

    2014-06-01

    The La0.3Sr0.55Ti0.9Cr0.1O3-δ (LSTC10) anode material was synthesized by citric acid-nitrate process. The yttria-stabilized zirconia (YSZ) electrolyte-supported cell was fabricated by screen printing method using LSTC10 as anode and (La0.75Sr0.25)0.95MnO3-δ (LSM) as cathode. The electrochemical performance of cell was tested by using dry hydrogen as fuel and air as oxidant in the temperature range of 800-900 °C. At 900 °C, the open circuit voltage (OCV) and the maximum power density of cell are 1.08 V and 13.0 mW·cm(-2), respectively. The microstructures of cell after performance testing were investigated by scanning electron microscope (SEM). The results show that the anode and cathode films are porous and closely attached to the YSZ electrolyte. LSTC10 is believed to be a kind of potential solid oxide fuel cell (SOFC) anode material.

  3. Ohmic resistance affects microbial community and electrochemical kinetics in a multi-anode microbial electrochemical cell

    NASA Astrophysics Data System (ADS)

    Dhar, Bipro Ranjan; Ryu, Hodon; Santo Domingo, Jorge W.; Lee, Hyung-Sool

    2016-11-01

    Multi-anode microbial electrochemical cells (MxCs) are considered as one of the most promising configurations for scale-up of MxCs, but understanding of anode kinetics in multiple anodes is limited in the MxCs. In this study we assessed microbial community and electrochemical kinetic parameters for biofilms on individual anodes in a multi-anode MxC to better comprehend anode fundamentals. Microbial community analysis targeting 16S rRNA Illumina sequencing showed that Geobacter genus was abundant (87%) only on the biofilm anode closest to a reference electrode (low ohmic energy loss) in which current density was the highest among three anodes. In comparison, Geobacter populations were less than 1% for biofilms on other two anodes distant from the reference electrode (high ohmic energy loss), generating small current density. Half-saturation anode potential (EKA) was the lowest at -0.251 to -0.242 V (vs. standard hydrogen electrode) for the closest biofilm anode to the reference electrode, while EKA was as high as -0.134 V for the farthest anode. Our study proves that electric potential of individual anodes changed by ohmic energy loss shifts biofilm communities on individual anodes and consequently influences electron transfer kinetics on each anode in the multi-anode MxC.

  4. Electrochemical technique and copper-promoted transformations: selective hydroxylation and amination of arylboronic acids.

    PubMed

    Qi, Hong-Lin; Chen, Dong-Song; Ye, Jian-Shan; Huang, Jing-Mei

    2013-08-01

    An efficient and selective electrosynthesis of phenols and anilines from arylboronic acids in aqueous ammonia is achieved in an undivided cell. By simply changing the concentration of aqueous ammonia and the anode potential, good yields of phenols and anilines can be obtained chemoselectively with high reaction rates. We propose that anodic oxidation could have played an important role in these transformations. PMID:23808633

  5. Electrochemical formation of hydroxide for enhancing carbon dioxide and acid gas uptake by a solution

    DOEpatents

    Rau, Gregory Hudson

    2014-07-01

    A system for forming metal hydroxide from a metal carbonate utilizes a water electrolysis cell having an acid-producing anode and a hydroxyl-producing cathode immersed in a water solution of sufficient ionic content to allow an electric current to pass between the hydroxyl-producing cathode and the acid-producing anode. A metal carbonate is placed in close proximity to the acid-producing anode. A direct current electrical voltage is provided across the acid-producing anode and the hydroxyl-producing cathode sufficient to generate acid at the acid-producing anode and hydroxyl ions at the hydroxyl-producing cathode. The acid dissolves at least part of the metal carbonate into metal and carbonate ions allowing the metal ions to travel toward the hydroxyl-producing cathode and to combine with the hydroxyl ions to form the metal hydroxide. The carbonate ions travel toward the acid-producing anode and form carbonic acid and/or water and carbon dioxide.

  6. Passive films on magnesium anodes in primary batteries

    NASA Technical Reports Server (NTRS)

    Ratnakumar, B. V.

    1988-01-01

    The characteristics of the passive films over Mg anodes, which essentially govern the voltage delay of the latter, have been determined nondestructively from an analysis of the transient and steady-state response of the electrode potential to low amplitude galvanostatic polarization under various experimental conditions viz., with different corrosion inhibitor coatings on Mg, after various periods of ageing of anode in solutions containing corrosion inhibitors, at various low temperatures etc. Using these parameters, the kinetics of film build-up or dissolution under these conditions have been monitored. The morphology of the anode film has been verified with scanning electron microscopy. Similar transients at low temperatures point out a steep rise in the film resistivity which is essentially responsible for the severe voltage delay. Finally, possible application of this technique in secondary Li batteries to improve cycling characteristics of the Li anode has been pointed out.

  7. Multi-Anode Frequency Triplers at Sub-Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Maestrini, Alain; Tripon-Canseliet, Charlotte; Ward, John S.; Javadi, Hamid; Gill, John; Chattopadhyay, Goutam; Schlecht, Erich; Mehdi, Imran

    2005-01-01

    We report on the design methodology of fix-tuned split-block waveguide balanced frequency triplers working at 300,600 and 900 GHz. They feature four to six GaAs Schottky planar diodes in a balanced configuration. A 6-anode 300 GHz tripler, a 6-anode 560 GHz tripler and a 4-anode 900 GHz tripler will be fabricated with JPL membrane technology in order to minimize dielectric loading and ensure accurate thickness of the substrate. A 4-anode 600 GHz tripler was fabricated with JPL substrateless technology that delivers 0.8-1.6mW in the 540-640 GHz band at room temperature. When cooled to l2OK this tripler delivers 2-4mW from 540 to 640 GHz.

  8. Blue fluorescent organic light emitting diodes with multilayered graphene anode

    SciTech Connect

    Hwang, Joohyun; Choi, Hong Kyw; Moon, Jaehyun; Shin, Jin-Wook; Joo, Chul Woong; Han, Jun-Han; Cho, Doo-Hee; Huh, Jin Woo; Choi, Sung-Yool; Lee, Jeong-Ik; Chu, Hye Yong

    2012-10-15

    As an innovative anode for organic light emitting devices (OLEDs), we have investigated graphene films. Graphene has importance due to its huge potential in flexible OLED applications. In this work, graphene films have been catalytically grown and transferred to the glass substrate for OLED fabrications. We have successfully fabricated 2 mm × 2 mm device area blue fluorescent OLEDs with graphene anodes which showed 2.1% of external quantum efficiency at 1000 cd/m{sup 2}. This is the highest value reported among fluorescent OLEDs using graphene anodes. Oxygen plasma treatment on graphene has been found to improve hole injections in low voltage regime, which has been interpreted as oxygen plasma induced work function modification. However, plasma treatment also increases the sheet resistance of graphene, limiting the maximum luminance. In summary, our works demonstrate the practical possibility of graphene as an anode material for OLEDs and suggest a processing route which can be applied to various graphene related devices.

  9. High-performance lithium battery anodes using silicon nanowires.

    PubMed

    Chan, Candace K; Peng, Hailin; Liu, Gao; McIlwrath, Kevin; Zhang, Xiao Feng; Huggins, Robert A; Cui, Yi

    2008-01-01

    There is great interest in developing rechargeable lithium batteries with higher energy capacity and longer cycle life for applications in portable electronic devices, electric vehicles and implantable medical devices. Silicon is an attractive anode material for lithium batteries because it has a low discharge potential and the highest known theoretical charge capacity (4,200 mAh g(-1); ref. 2). Although this is more than ten times higher than existing graphite anodes and much larger than various nitride and oxide materials, silicon anodes have limited applications because silicon's volume changes by 400% upon insertion and extraction of lithium which results in pulverization and capacity fading. Here, we show that silicon nanowire battery electrodes circumvent these issues as they can accommodate large strain without pulverization, provide good electronic contact and conduction, and display short lithium insertion distances. We achieved the theoretical charge capacity for silicon anodes and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.

  10. Controlled Fabrication of Nanoporous Oxide Layers on Zircaloy by Anodization

    NASA Astrophysics Data System (ADS)

    Park, Yang Jeong; Ha, Jun Mok; Ali, Ghafar; Kim, Hyun Jin; Addad, Yacine; Cho, Sung Oh

    2015-09-01

    We have presented a mechanism to explain why the resulting oxide morphology becomes a porous or a tubular nanostructure when a zircaloy is electrochemically anodized. A porous zirconium oxide nanostructure is always formed at an initial anodization stage, but the degree of interpore dissolution determines whether the final morphology is nanoporous or nanotubular. The interpore dissolution rate can be tuned by changing the anodization parameters such as anodization time and water content in an electrolyte. Consequently, porous or tubular oxide nanostructures can be selectively fabricated on a zircaloy surface by controlling the parameters. Based on this mechanism, zirconium oxide layers with completely nanoporous, completely nanotubular, and intermediate morphologies between a nanoporous and a nanotubular structure were controllably fabricated.

  11. Topics in Chemical Instrumentation: CII. Automated Anodic Stripping Voltammetry.

    ERIC Educational Resources Information Center

    Stock, John T.; Ewing, Galen W., Ed.

    1980-01-01

    Presents details of anodic stripping analysis (ASV) in college chemistry laboratory experiments. Provides block diagrams of the analyzer system, circuitry and power supplies of the automated stripping analyzer, and instructions for implementing microcomputer control of the ASV. (CS)

  12. Anode consumption on a subsea X-mas tree

    SciTech Connect

    Lye, R.E.

    1998-12-31

    Anode consumption and coating breakdown on a X-mas tree installed at the Troll Field in the Norwegian North Sea was investigated after 5 years. A comparison with a spare tree and one tree being exposed for only 3--4 months was done. The epoxy coating has several blisters, in particular on stainless steel surfaces. Water inside the blisters has a pH of 13-14 indicating that the cathodic reaction occurs inside them. The anode dimensions indicate an overall anode consumption of approximately 20%, while the design allows 27% after 5 years. This indicates that the original design is quite conservative. If the design had been done according to present day design rules, the conservatism would be reduced; an overall anode consumption of 23% is then likely (still less than allowed 27%).

  13. 4. ANODIZED ALUMINUM WATER FOUNTAIN, DIABLO POWERHOUSE, CUSTOMMADE FOR THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. ANODIZED ALUMINUM WATER FOUNTAIN, DIABLO POWERHOUSE, CUSTOM-MADE FOR THE VISITORS LOBBY, 1989. - Skagit Power Development, Diablo Powerhouse, On Skagit River, 6.1 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  14. Recent Development on Anodes for Na-Ion Batteries

    SciTech Connect

    Bommier, C; Ji, XL

    2015-01-23

    New discoveries in anode materials for sodium ion batteries (NIBs) are highly necessary to achieve the goals of widespread applications, such as electric vehicles (EVs) and grid-level energy storage. Carbon-based materials are critical for this task as they are inexpensive, abundant, and versatile. They contain a plethora of structures and morphologies, ranging from highly ordered graphite or nanotubes to highly disordered amorphous carbon, thus making them very attractive for electrochemical energy storage. This review attempts to cover past and recent progress in the development of carbon-based anode materials for NIBs. To give a larger context, the article will briefly cover other anode materials for NIBs as well. The aim of this paper is to provide a timely update for researchers currently involved in the respective fields or to serve as a starting point for individuals who would like to gain a greater knowledge of new NIB anode materials.

  15. Virtual cathode microwave generator having annular anode slit

    SciTech Connect

    Kwan, T.J.T.; Snell, C.M.

    1988-03-08

    A microwave generator using an oscillating virtual cathode is described comprising: a cathode for emitting electrons; an anode for accelerating emitted electrons from the cathode, the anode having an annular slit therethrough effective for forming the virtual cathode and having at least one range thickness relative to electrons reflected from the virtual cathode; and magnet means for producing a magnetic field having a field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit and to enable the electrons reflected from the virtual cathode to axially diverge from the annular beam. The reflected electrons return toward the cathode diverge from the annular beam and are absorbed by the anode to substantially eliminate electrons reflexing between the cathode and the virtual cathode.

  16. Nanocomposite anode materials for sodium-ion batteries

    DOEpatents

    Manthiram, Arumugam; Kim Il, Tae; Allcorn, Eric

    2016-06-14

    The disclosure relates to an anode material for a sodium-ion battery having the general formula AO.sub.x--C or AC.sub.x--C, where A is aluminum (Al), magnesium (Mg), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), molybdenum (Mo), tungsten (W), niobium (Nb), tantalum (Ta), silicon (Si), or any combinations thereof. The anode material also contains an electrochemically active nanoparticles within the matrix. The nanoparticle may react with sodium ion (Na.sup.+) when placed in the anode of a sodium-ion battery. In more specific embodiments, the anode material may have the general formula M.sub.ySb-M'O.sub.x--C, Sb-MO.sub.x--C, M.sub.ySn-M'C.sub.x--C, or Sn-MC.sub.x--C. The disclosure also relates to rechargeable sodium-ion batteries containing these materials and methods of making these materials.

  17. VIEW OF INTERIOR SPACE WITH ANODIZING TANK AND LIQUID BIN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF INTERIOR SPACE WITH ANODIZING TANK AND LIQUID BIN STORAGE TANK IN FOREGROUND, FACING NORTH. - Douglas Aircraft Company Long Beach Plant, Aircraft Parts Receiving & Storage Building, 3855 Lakewood Boulevard, Long Beach, Los Angeles County, CA

  18. Porphyrin Dye-Sensitized Zinc Oxide Aggregated Anodes for Use in Solar Cells.

    PubMed

    Syu, Yu-Kai; Tingare, Yogesh; Lin, Shou-Yen; Yeh, Chen-Yu; Wu, Jih-Jen

    2016-01-01

    Porphyrin YD2-o-C8-based dyes were employed to sensitize room-temperature (RT) chemical-assembled ZnO aggregated anodes for use in dye-sensitized solar cells (DSSCs). To reduce the acidity of the YD2-o-C8 dye solution, the proton in the carboxyl group of a porphyrin dye was replaced with tetrabuthyl ammonium (TBA⁺) in this work. The short-circuit current density (Jsc) of the YD2-o-C8-TBA-sensitized ZnO DSSCs is higher than that of the YD2-o-C8-sensitized cells, resulting in the improvement of the efficiency of the YD2-o-C8-based ZnO DSSCs. With an appropriate incorporation of chenodeoxycholic acid (CDCA) as coadsorbate, the Jsc and efficiency of the YD2-o-C8-TBA-sensitized ZnO DSSC are enhanced due to the improvement of the incident-photon-to-current efficiency (IPCE) values in the wavelength range of 400-450 nm. Moreover, a considerable increase in Jsc is achieved by the addition of a light scattering layer in the YD2-o-C8-TBA-sensitized ZnO photoanodes. Significant IPCE enhancement in the range 475-600 nm is not attainable by tuning the YD2-o-C8-TBA sensitization processes for the anodes without light scattering layers. Using the RT chemical-assembled ZnO aggregated anode with a light scattering layer, an efficiency of 3.43% was achieved in the YD2-o-C8-TBA-sensitized ZnO DSSC. PMID:27527136

  19. New Anode Material for Rechargeable Li-ION Cells

    NASA Technical Reports Server (NTRS)

    Huang, C. -K.; Smart, M.; Halpert, G.; Surampudi, S.; Wolfenstine, J.

    1995-01-01

    Carbon materials, such as graphite, cokes, pitch and PAN fibers, are being evaluated in lithium batteries as alternate anode materials with some degree of success. There is an effort to look for other non-carbon anode materials which have larger Li capacity, higher rate capability, smaller first charge capacity loss and better mechanical stability during cycling. A Li-Mg-Si material is evaluated.

  20. Development of Carbon Anode for Rechargeable Lithium Cells

    NASA Technical Reports Server (NTRS)

    Huang, C. -K.; Surampudi, S.; Halpert, G.

    1994-01-01

    Conventionally, rechargeable lithium cells employ a pure lithium anode. To overcome problems associated with the pure lithium electrode, it has been proposed to replace the conventional electrode with an alternative material having a greater stability with respect to the cell electrolytes. For this reason, several graphitic and coke based carbonaceous materials were evaluated as candidate anode materials...In this paper, we summarize the results of the studies on Li-ion cell development.

  1. Anode for a secondary, high-temperature electrochemical cell

    DOEpatents

    Vissers, Donald R.; Tani, Benjamin S.

    1976-01-01

    A high-temperature, secondary electrochemical cell includes an anode containing lithium, an electrolyte containing lithium ions and a cathode containing a chalcogen material such as sulfur or a metallic sulfide. The anode includes a porous substrate formed of, for instance, a compacted mass of entangled metallic fibers providing interstitial crevices for receiving molten lithium metal. The surfaces of the interstitial crevices are provided with a coating of cobalt metal to enhance the retention of the molten lithium metal within the substrate.

  2. Fuel cell having dual electrode anode or cathode

    DOEpatents

    Findl, Eugene

    1985-01-01

    A fuel cell that is characterized by including a dual electrode anode that is operable to simultaneously electro-oxidize a gaseous fuel and a liquid fuel. In alternative embodiments, a fuel cell having a single electrode anode is provided with a dual electrode cathode that is operable to simultaneously reduce a gaseous oxidant and a liquid oxidant to electro-oxidize a fuel supplied to the cell.

  3. Fuel cell having dual electrode anode or cathode

    DOEpatents

    Findl, E.

    1984-04-10

    A fuel cell that is characterized by including a dual electrode anode that is operable to simultaneously electro-oxidize a gaseous fuel and a liquid fuel. In alternative embodiments, a fuel cell having a single electrode anode is provided with a dual electrode cathode that is operable to simultaneously reduce a gaseous oxidant and a liquid oxidant to electro-oxidize a fuel supplied to the cell.

  4. Stainless steel anodes for alkaline water electrolysis and methods of making

    SciTech Connect

    Soloveichik, Grigorii Lev

    2014-01-21

    The corrosion resistance of stainless steel anodes for use in alkaline water electrolysis was increased by immersion of the stainless steel anode into a caustic solution prior to electrolysis. Also disclosed herein are electrolyzers employing the so-treated stainless steel anodes. The pre-treatment process provides a stainless steel anode that has a higher corrosion resistance than an untreated stainless steel anode of the same composition.

  5. Titanium dental implant surfaces obtained by anodic spark deposition - From the past to the future.

    PubMed

    Kaluđerović, Milena R; Schreckenbach, Joachim P; Graf, Hans-Ludwig

    2016-12-01

    Commercial titanium-based dental implants are obtained applying various methods such as machining, acid etching, anodization, plasma spraying, grit blasting or combination techniques yielding materials with smooth or micro-roughened surfaces. Those techniques are used to optimize the surface properties and to maximize biocompatibility and bioactivity with bone tissue. Present review is focused on the material surfaces obtained by anodic spark deposition (ASD). From the early 1980s till present, the results of numerous studies have shown that anodically oxidized surfaces with different dopants express a positive effect on osteoblasts behavior in vitro and osseointegration in vivo. Those surfaces demonstrated a high biocompatibility and rapid osseointegration in clinical application. This paper provides an overview of the preparation of implant surfaces by employing ASD process. Moreover, reviewed are clinically used ASD implant surfaces (Ticer, TiUnite, Osstem, etc.). The electrolyte variations in ASD process and their influence on surface properties are given herein. Using different electrolytes, anode voltages and temperatures, the above fabrication process can yield various surface morphologies from smooth to rough, porous surfaces. Furthermore, ASD enables thickening of oxide layers and enrichment with different dopands from used electrolyte, which hinder release of potentially toxic titanium ions in surrounding tissue. Particularly exciting results were achieved by calcium and phosphorus doping of the oxide layer (Ticer, ZL Microdent; TiUnite, Nobel Biocare Holding AB) which significantly increased the osteocompatibility. Ticer, a dental implant with anodically oxidized surface and the first among similar materials employed in clinical practice, was found to promote fast osteoblast cell differentiation and mineralization processes. Moreover, Ticer accelerate the integration with the bone, increase the bone/implant contact and improve primary and secondary

  6. Effect of surface anodization on stability of orthodontic microimplant

    PubMed Central

    Karmarker, Sanket; Yu, Wonjae

    2012-01-01

    Objective To determine the effect of surface anodization on the interfacial strength between an orthodontic microimplant (MI) and the rabbit tibial bone, particularly in the initial phase after placement. Methods A total of 36 MIs were driven into the tibias of 3 mature rabbits by using the self-drilling method and then removed after 6 weeks. Half the MIs were as-machined (n = 18; machined group), while the remaining had anodized surfaces (n = 18; anodized group). The peak insertion torque (PIT) and the peak removal torque (PRT) values were measured for the 2 groups of MIs. These values were then used to calculate the interfacial shear strength between the MI and cortical bone. Results There were no statistical differences in terms of PIT between the 2 groups. However, mean PRT was significantly greater for the anodized implants (3.79 ± 1.39 Ncm) than for the machined ones (2.05 ± 1.07 Ncm) (p < 0.01). The interfacial strengths, converted from PRT, were calculated at 10.6 MPa and 5.74 MPa for the anodized and machined group implants, respectively. Conclusions Anodization of orthodontic MIs may enhance their early-phase retention capability, thereby ensuring a more reliable source of absolute anchorage. PMID:23112925

  7. Anode Sheath and Double Layer Solutions with Ionization

    NASA Astrophysics Data System (ADS)

    Scheiner, Brett S.; Baalrud, Scott D.

    2014-10-01

    When an electrode in a plasma is biased more positive than the plasma potential it attracts electrons and repels ions forming a region of negative space charge (electron sheath). Ballistic electrons moving towards this anode gain energy equal to the difference in electrostatic potential energy, Δϕ = ϕ (x) -ϕplasma , with a maximum of ϕanode -ϕplasma . When ϕanode is large enough, electrons can gain enough energy to ionize neutral atoms through electron impact ionization. This leads to a layer of increased ion density near the anode, which can exceed the local electron density at large enough anode biases forming a double layer. We model the sheath potential profile using Poisson's equation with a fluid model for the electron density in the case without ionization and formulate an integral equation for the case with ionization where the ion density depends on an integral from ϕ (x) to ϕanode. An analytic form of the sheath electric field is obtained for the case without ionization and we demonstrate that it asymptotically agrees with the Child-Langmuir solution. We numerically obtain double layer solutions when including ionization and show that the potential profile expands beyond that of the Child-Langmuir solution. This work was supported by the Office of Fusion Science at the U.S. Department of Energy under Contract DE-AC04-94SL85000.

  8. Hyper-dendritic nanoporous zinc foam anodes

    SciTech Connect

    Chamoun, Mylad; Hertzberg, Benjamin J.; Gupta, Tanya; Davies, Daniel; Bhadra, Shoham; Van Tassell, Barry.; Erdonmez, Can; Steingart, Daniel A.

    2015-04-24

    The low cost, significant reducing potential, and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1 - 96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrast to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~ 88% at full depth-of-discharge at various rates indicating a superb rate-capability. The rechargeability of Zn⁰/Zn²⁺ showed significant capacity retention over 100 cycles at a 40% depth-of-discharge to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge-discharge cycling and presented superior performance compared to bulk zinc electrodes.

  9. Hyper-dendritic nanoporous zinc foam anodes

    DOE PAGES

    Chamoun, Mylad; Hertzberg, Benjamin J.; Gupta, Tanya; Davies, Daniel; Bhadra, Shoham; Van Tassell, Barry.; Erdonmez, Can; Steingart, Daniel A.

    2015-04-24

    The low cost, significant reducing potential, and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1 - 96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrastmore » to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~ 88% at full depth-of-discharge at various rates indicating a superb rate-capability. The rechargeability of Zn⁰/Zn²⁺ showed significant capacity retention over 100 cycles at a 40% depth-of-discharge to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge-discharge cycling and presented superior performance compared to bulk zinc electrodes.« less

  10. Process for anodizing a robotic device

    DOEpatents

    Townsend, William T.

    2011-11-08

    A robotic device has a base and at least one finger having at least two links that are connected in series on rotary joints with at least two degrees of freedom. A brushless motor and an associated controller are located at each joint to produce a rotational movement of a link. Wires for electrical power and communication serially connect the controllers in a distributed control network. A network operating controller coordinates the operation of the network, including power distribution. At least one, but more typically two to five, wires interconnect all the controllers through one or more joints. Motor sensors and external world sensors monitor operating parameters of the robotic hand. The electrical signal output of the sensors can be input anywhere on the distributed control network. V-grooves on the robotic hand locate objects precisely and assist in gripping. The hand is sealed, immersible and has electrical connections through the rotary joints for anodizing in a single dunk without masking. In various forms, this intelligent, self-contained, dexterous hand, or combinations of such hands, can perform a wide variety of object gripping and manipulating tasks, as well as locomotion and combinations of locomotion and gripping.

  11. Porous Anodic Aluminum Oxide with Serrated Nanochannels

    NASA Astrophysics Data System (ADS)

    Li, Dongdong; Zhao, Liang; Lu, Jia G.

    2010-03-01

    Self-assembled nanoporous anodic aluminum oxide (AAO) membrane with straight channels has long been an important tool in synthesizing highly ordered and vertically aligned quasi-1D nanostructures for various applications. Recently shape-selective nanomaterials have been achieved using AAO as a template. It is envisioned that nanowires with multi-branches will significantly increase the active functional sites for applications as sensors, catalysts, chemical cells, etc. Here AAO membranes with serrated nanochannels have been successfully fabricated via a two-step annodization method. The serrated channels with periodic intervals are aligned at an angle of ˜25^circ along the stem channels. The formation of the serrated channels is attributed to the evolution of oxygen gas bubbles and the resulted plastic deformation in oxide membrane. In order to reveal the inside channel structure, Platinum are electrodeposited into the AAO template. The as-synthesized serrated Pt nanowires demonstrate a superior electrocatalytic activity. This is attributed to the enhanced electric field strength around serrated tips as shown in the electric field simulation by COMOSL. Moreover, hierarchical serrated/straight hybrid structures can be constructed using this simple and novel self assembly technique.

  12. Impact de la preparation des anodes crues et des conditions de cuisson sur la fissuration dans des anodes denses

    NASA Astrophysics Data System (ADS)

    Amrani, Salah

    La fabrication de l'aluminium est realisee dans une cellule d'electrolyse, et cette operation utilise des anodes en carbone. L'evaluation de la qualite de ces anodes reste indispensable avant leur utilisation. La presence des fissures dans les anodes provoque une perturbation du procede l'electrolyse et une diminution de sa performance. Ce projet a ete entrepris pour determiner l'impact des differents parametres de procedes de fabrication des anodes sur la fissuration des anodes denses. Ces parametres incluent ceux de la fabrication des anodes crues, des proprietes des matieres premieres et de la cuisson. Une recherche bibliographique a ete effectuee sur tous les aspects de la fissuration des anodes en carbone pour compiler les travaux anterieurs. Une methodologie detaillee a ete mise au point pour faciliter le deroulement des travaux et atteindre les objectifs vises. La majorite de ce document est reservee pour la discussion des resultats obtenus au laboratoire de l'UQAC et au niveau industriel. Concernant les etudes realisees a l'UQAC, une partie des travaux experimentaux est reservee a la recherche des differents mecanismes de fissuration dans les anodes denses utilisees dans l'industrie d'aluminium. L'approche etait d'abord basee sur la caracterisation qualitative du mecanisme de la fissuration en surface et en profondeur. Puis, une caracterisation quantitative a ete realisee pour la determination de la distribution de la largeur de la fissure sur toute sa longueur, ainsi que le pourcentage de sa surface par rapport a la surface totale de l'echantillon. Cette etude a ete realisee par le biais de la technique d'analyse d'image utilisee pour caracteriser la fissuration d'un echantillon d'anode cuite. L'analyse surfacique et en profondeur de cet echantillon a permis de voir clairement la formation des fissures sur une grande partie de la surface analysee. L'autre partie des travaux est basee sur la caracterisation des defauts dans des echantillons d'anodes crues

  13. Cell Adhesion and Growth on the Anodized Aluminum Oxide Membrane.

    PubMed

    Park, Jeong Su; Moon, Dalnim; Kim, Jin-Seok; Lee, Jin Seok

    2016-03-01

    Nanotopological cues are popular tools for in vivo investigation of the extracellular matrix (ECM) and cellular microenvironments. The ECM is composed of multiple components and generates a complex microenvironment. The development of accurate in vivo methods for the investigation of ECM are important for disease diagnosis and therapy, as well as for studies on cell behavior. Here, we fabricated anodized aluminum oxide (AAO) membranes using sulfuric and oxalic acid under controlled voltage and temperature. The membranes were designed to possess three different pore and interpore sizes, AAO-1, AAO-2, and AAO-3 membranes, respectively. These membranes were used as tools to investigate nanotopology-signal induced cell behavior. Cancerous cells, specifically, the OVCAR-8 cell-line, were cultured on porous AAO membranes and the effects of these membranes on cell shape, proliferation, and viability were studied. AAO-1 membranes bearing small sized pores were found to maintain the spreading shape of the cultured cells. Cells cultured on AAO-2 and AAO-3 membranes, bearing large pore-sized AAO membranes, changed shape from spreading to rounding. Furthermore, cellular area decreased when cells were cultured on all three AAO membranes that confirmed decreased levels of focal adhesion kinase (FAK). Additionally, OVCAR-8 cells exhibited increased proliferation on AAO membranes possessing various pore sizes, indicating the importance of the nanosurface structure in regulating cell behaviors, such as cell proliferation. Our results suggest that porous-AAO membranes induced nanosurface regulated cell behavior as focal adhesion altered the intracellular organization of the cytoskeleton. Our results may find potential applications as tools in in vivo cancer research studies. PMID:27280255

  14. Cloud Point Extraction for Electroanalysis: Anodic Stripping Voltammetry of Cadmium.

    PubMed

    Rusinek, Cory A; Bange, Adam; Papautsky, Ian; Heineman, William R

    2015-06-16

    Cloud point extraction (CPE) is a well-established technique for the preconcentration of hydrophobic species from water without the use of organic solvents. Subsequent analysis is then typically performed via atomic absorption spectroscopy (AAS), UV-vis spectroscopy, or high performance liquid chromatography (HPLC). However, the suitability of CPE for electroanalytical methods such as stripping voltammetry has not been reported. We demonstrate the use of CPE for electroanalysis using the determination of cadmium (Cd(2+)) by anodic stripping voltammetry (ASV). Rather than using the chelating agents which are commonly used in CPE to form a hydrophobic, extractable metal complex, we used iodide and sulfuric acid to neutralize the charge on Cd(2+) to form an extractable ion pair. This offers good selectivity for Cd(2+) as no interferences were observed from other heavy metal ions. Triton X-114 was chosen as the surfactant for the extraction because its cloud point temperature is near room temperature (22-25 °C). Bare glassy carbon (GC), bismuth-coated glassy carbon (Bi-GC), and mercury-coated glassy carbon (Hg-GC) electrodes were compared for the CPE-ASV. A detection limit for Cd(2+) of 1.7 nM (0.2 ppb) was obtained with the Hg-GC electrode. ASV with CPE gave a 20x decrease (4.0 ppb) in the detection limit compared to ASV without CPE. The suitability of this procedure for the analysis of tap and river water samples was demonstrated. This simple, versatile, environmentally friendly, and cost-effective extraction method is potentially applicable to a wide variety of transition metals and organic compounds that are amenable to detection by electroanalytical methods.

  15. Cloud Point Extraction for Electroanalysis: Anodic Stripping Voltammetry of Cadmium

    PubMed Central

    Rusinek, Cory A.; Bange, Adam; Papautsky, Ian; Heineman, William R.

    2016-01-01

    Cloud point extraction (CPE) is a well-established technique for the pre-concentration of hydrophobic species from water without the use of organic solvents. Subsequent analysis is then typically performed via atomic absorption spectroscopy (AAS), UV-Vis spectroscopy, or high performance liquid chromatography (HPLC). However, the suitability of CPE for electroanalytical methods such as stripping voltammetry has not been reported. We demonstrate the use of CPE for electroanalysis using the determination of cadmium (Cd2+) by anodic stripping voltammetry (ASV) as a representative example. Rather than using the chelating agents which are commonly used in CPE to form a hydrophobic, extractable metal complex, we used iodide and sulfuric acid to neutralize the charge on Cd2+ to form an extractable ion pair. Triton X-114 was chosen as the surfactant for the extraction because its cloud point temperature is near room temperature (22–25° C). Bare glassy carbon (GC), bismuth-coated glassy carbon (Bi-GC), and mercury-coated glassy carbon (Hg-GC) electrodes were compared for the CPE-ASV. A detection limit for Cd2+ of 1.7 nM (0.2 ppb) was obtained with the Hg-GC electrode. Comparison of ASV analysis without CPE was also investigated and a 20x decrease (4.0 ppb) in the detection limit was observed. The suitability of this procedure for the analysis of tap and river water samples was also demonstrated. This simple, versatile, environmentally friendly and cost-effective extraction method is potentially applicable to a wide variety of transition metals and organic compounds that are amenable to detection by electroanalytical methods. PMID:25996561

  16. Cell Adhesion and Growth on the Anodized Aluminum Oxide Membrane.

    PubMed

    Park, Jeong Su; Moon, Dalnim; Kim, Jin-Seok; Lee, Jin Seok

    2016-03-01

    Nanotopological cues are popular tools for in vivo investigation of the extracellular matrix (ECM) and cellular microenvironments. The ECM is composed of multiple components and generates a complex microenvironment. The development of accurate in vivo methods for the investigation of ECM are important for disease diagnosis and therapy, as well as for studies on cell behavior. Here, we fabricated anodized aluminum oxide (AAO) membranes using sulfuric and oxalic acid under controlled voltage and temperature. The membranes were designed to possess three different pore and interpore sizes, AAO-1, AAO-2, and AAO-3 membranes, respectively. These membranes were used as tools to investigate nanotopology-signal induced cell behavior. Cancerous cells, specifically, the OVCAR-8 cell-line, were cultured on porous AAO membranes and the effects of these membranes on cell shape, proliferation, and viability were studied. AAO-1 membranes bearing small sized pores were found to maintain the spreading shape of the cultured cells. Cells cultured on AAO-2 and AAO-3 membranes, bearing large pore-sized AAO membranes, changed shape from spreading to rounding. Furthermore, cellular area decreased when cells were cultured on all three AAO membranes that confirmed decreased levels of focal adhesion kinase (FAK). Additionally, OVCAR-8 cells exhibited increased proliferation on AAO membranes possessing various pore sizes, indicating the importance of the nanosurface structure in regulating cell behaviors, such as cell proliferation. Our results suggest that porous-AAO membranes induced nanosurface regulated cell behavior as focal adhesion altered the intracellular organization of the cytoskeleton. Our results may find potential applications as tools in in vivo cancer research studies.

  17. Cloud Point Extraction for Electroanalysis: Anodic Stripping Voltammetry of Cadmium.

    PubMed

    Rusinek, Cory A; Bange, Adam; Papautsky, Ian; Heineman, William R

    2015-06-16

    Cloud point extraction (CPE) is a well-established technique for the preconcentration of hydrophobic species from water without the use of organic solvents. Subsequent analysis is then typically performed via atomic absorption spectroscopy (AAS), UV-vis spectroscopy, or high performance liquid chromatography (HPLC). However, the suitability of CPE for electroanalytical methods such as stripping voltammetry has not been reported. We demonstrate the use of CPE for electroanalysis using the determination of cadmium (Cd(2+)) by anodic stripping voltammetry (ASV). Rather than using the chelating agents which are commonly used in CPE to form a hydrophobic, extractable metal complex, we used iodide and sulfuric acid to neutralize the charge on Cd(2+) to form an extractable ion pair. This offers good selectivity for Cd(2+) as no interferences were observed from other heavy metal ions. Triton X-114 was chosen as the surfactant for the extraction because its cloud point temperature is near room temperature (22-25 °C). Bare glassy carbon (GC), bismuth-coated glassy carbon (Bi-GC), and mercury-coated glassy carbon (Hg-GC) electrodes were compared for the CPE-ASV. A detection limit for Cd(2+) of 1.7 nM (0.2 ppb) was obtained with the Hg-GC electrode. ASV with CPE gave a 20x decrease (4.0 ppb) in the detection limit compared to ASV without CPE. The suitability of this procedure for the analysis of tap and river water samples was demonstrated. This simple, versatile, environmentally friendly, and cost-effective extraction method is potentially applicable to a wide variety of transition metals and organic compounds that are amenable to detection by electroanalytical methods. PMID:25996561

  18. An analytical model for liquid-anode and vapor-anode AMTEC converters

    SciTech Connect

    Tournier, J.; El-Genk, M.S.; Schuller, M.; Hausgen, P.

    1997-01-01

    This paper describes a lumped analytical model of liquid-anode single-tube and vapor-anode multi-tube AMTEC cells. The model results agreed well with experimental data for Mo, NbN and TiN electrodes. Results showed that Mo and NbN electrodes exhibit high B values between 400 and 600A.K{sup 1/2}/Pa.m{sup 2}, and have the potential for peak power densities slightly above 1W/cm{sup 2}, with efficiencies as high as 28{percent}. In contrast, TiN electrodes have lower temperature-independent exchange currents, between 120 and 135A.K{sup 1/2}/Pa.m{sup 2}, lower peak power densities between 0.5 and 0.75W/cm{sup 2}, and efficiencies below 24{percent} at a BASE temperature of 1200 K. These values of B compare well with that reported by other investigators. {copyright} {ital 1997 American Institute of Physics.}

  19. Electrochemical degradation of 4-chloroguaiacol for wastewater treatment using PbO2 anodes.

    PubMed

    Samet, Y; Elaoud, S Chaabane; Ammar, S; Abdelhedi, R

    2006-12-01

    Electrochemical oxidation of 4-chloroguaiacol (4-CG) at Nb/PbO(2) anodes was studied under different experimental conditions such as initial concentration of substrate, electrolysis time, temperature and pH. We measured the concentrations of 4-chlorocatechol (4-CC), 2-methoxyhydroquinone (2-MHQ), maleic acid (MA) and carbon dioxide as the main products. Black solid particles consisting mainly of polymers were formed during electrolysis. A mechanism of electrochemical oxidation of 4-CG was investigated. The oxidation of 4-CG can generally be described by simple pseudo first-order kinetics. The degradation of 4-CG was favoured at high temperature and lower initial concentration of 4-CG and low solution pH. However, the increase of temperature has not a significant effect on the mineralization of carboxylic acids. Moreover, these products required long electrolysis time.

  20. Structural and wetting properties of porous anodic alumina templates prepared by different electrolytes

    NASA Astrophysics Data System (ADS)

    Suchitra S., M.; Reddy, P. Ramana; Udayashankar, N. K.

    2016-05-01

    Porous anodic alumina (PAA) has been extensively studied in recent years due to their unique properties and applications for manufacturing nanostructured materials. In this article, we report our studies on structural and wetting properties of PAA membranes prepared using different electrolytes such as sulphuric, oxalic and phosphoric acids. The morphological parameters such as pore diameter and porosity were measured using SEM and analysed using image-J software. The structural investigation of PAA membranes was carried out through X-ray diffraction analysis and it was confirmed that PAA membranes were amorphous in nature. The wetting behaviour of PAA membranes were measured using contact angle measurement technique. The results show that PAA membranes were hydrophilic in nature with contact angles 26.03°, 35.21° and 42.0° for sulphuric, oxalic and phosphoric acids respectively.