bluuebunny/crossref_metadata_2025 huggingface dataset:
The reaction between hemoglobin α-subunit and haptoglobin
Authors: Terpstra Frank A. , Smith David B.
Published: December 2009

The interaction between human hemoglobin α-subunit and porcine haptoglobin was investigated by polyacrylamide gel electrophoresis, gel filtration chromatography, sedimentation through excess α-subunit and gel filtration in an α-subunit-containing medium. No interaction was detected by the first two methods indicating dissociation of the complex during the application of these separation techniques. The latter two methods, in which the complex is studied in a medium of excess subunits, showed that haptoglobin became saturated with the binding of two α-subunits.
4-Keto-γ-carotene(β,ψ-caroten-4-one), the major pigment of an Arthrobacter sp.
Authors: Fiasson Jean-Louis , Arpin Noël , Perrier Joseph
Published: December 2009

The major pigment of a new species of Arthrobacter was found to be an uncommon carotenoid, identified as β,ψ-caroten-4-one (4-keto-γ-carotene) from physical and chemical evidence. The taxonomical implications are discussed.
Preparation of active run-off 80S ribosomes and their subunits from mouse liver
Authors: Faber A. J. , Tamaoki T.
Published: December 2009

A method is described for the preparation of active run-off 80S ribosomes and 40S and 60S subunits of mouse liver. A polysome preparation was incubated at 37 °C for 10 min under the condition for protein synthesis (4 mM Mg2+, 100 mM KCl). Puromycin (10 mM) and 2 M KCl were added to a final concentration of 0.1 mM and 500 mM, respectively, and the reaction mixture was further incubated at 37 °C for 10 min. This latter treatment destabilized small polysomes and 'stuck' 80S particles, which were remaining after the first incubation, leading to complete release of 40S and 60S particles. Thus, the present method minimized variations in yield of subunits due to polysome preparations and preincubation conditions. The subunits were separated by sucrose density-gradient centrifugation or recovered by precipitation following reassociation into 80S particles (run-off 80S). The reformation of 80S particles from the subunits occurred spontaneously at 5 mM Mg2+ and 100 mM KCl. The isolated 40S and 60S subunits, separately, showed low phenylalanine-incorporating activity in the presence of poly(U), but when recombined, polymerized up to 10 phenylalanine residues per couple.
Purine catabolism in man: inhibition of 5′-phosphomonoesterase activities from placental microsomes
Authors: Fox Irving H. , Marchant Pamela J.
Published: December 2009

The 5′-phosphomonoesterase activity of 5′-nucleotidase (EC 3.1.3.5) and alkaline phosphatase (EC 3.1.3.1) participates in the catabolism of purine ribonucleotides to uric acid in humans.Initial velocity studies of 5′-nucleotidase suggest a sequential mechanism of interaction between AMP and MgCl2, with a Km of 14 and 3 μM, respectively. With product inhibition studies the apparent Ki's for adenosine, inosine, cytidine, and inorganic phosphate were 0.4, 3.0, 5.0, and 42 mM, respectively. A large number of nucleoside mono-, di-, and tri-phosphate compounds were inhibitors of the enzyme. Allopurinol ribonucleotide, ADP, or ATP were competitive inhibitors when AMP was the substrate, with a Ki slope of 10, 20, or 54 μM, respectively. GTP was a noncompetitive inhibitor, with a Ki slope of 120 μM.The phosphomonoesterase activity of human placental microsomal alkaline phosphatase had a pH optimum of 10.0 and had only 18% of maximum activity at pH 7.4. Substrates and inhibitors included almost any phosphorylated compound. The Km for AMP was 0.4 mM and the apparent Ki for Pi was 0.6 mM. Activity was increased only 19% by 5 mM MgCl2.These observations suggest that 5′-nucleotidase and alkaline phosphatase may be inhibited by ATP and Pi, respectively, under normal intracellular conditions, and that AMP may be preferentially hydrolyzed by 5′-nucleotidase.
Effects of the electric field on the virtual mass of a flowing fluid sphere
Authors: Kendoush Abdullah Abbas
Published: December 2009

A hydrodynamic solution was used to calculate the virtual mass coefficients of a flowing fluid sphere in a liquid medium subjected to an electric field. The values of the virtual mass coefficient of the bubble and a drop were found to be different from the classical value of half. The new result was validated by comparison with the experimental data of other investigators.
Observation of the 557.7 nm to 297.2 nm brightness ratio in the auroral spectrum with OSIRIS on Odin
Authors: Gattinger R. L. , Lloyd N. D. , Bourassa A. E. , Degenstein D. A. , McDade I. C. , Llewellyn E. J.
Published: December 2009

The two optically forbidden lines of atomic oxygen, O(1S–1D) at 557.7 nm and O(1S–3P) at 297.2 nm, serve as important diagnostics in atmospheric, planetary, and cometary studies. Originating from the same upper state, the emission brightness ratio, B(557.7)/B(297.2), must necessarily be constant. The reported emission ratio of these two lines from both theoretical and experimental investigations varies by approximately a factor of two. These two emissions are observed simultaneously in auroral spectra by the OSIRIS spectrograph on the Odin spacecraft, offering another opportunity to perform the ratio measurement. Because of the considerable wavelength separation between these two atomic lines, precise instrumental relative response calibrations can be problematic. To maintain accurate on-orbit spectral calibrations, an atmospheric radiation model with multiple Rayleigh scatter is employed to constantly track instrumental response. An example of a calibrated single bright auroral spectrum over the full OSIRIS wavelength range of 275 to 815 nm, limb tangent altitude 105 km, is presented. Using a number of individual auroral spectra, the observed OI 557.7 nm brightness is plotted versus the observed OI 297.2 nm brightness to both verify the required linear relationship and to experimentally determine the brightness ratio. Spectral contamination by other auroral emission features is removed. From the linear fit, the observed B(557.7)/B(297.2) ratio is 9.3 ± 0.5. By comparison, a ratio of 9.8 ± 1 was recently reported, determined by combining results from a number of observational databases separated in time and in wavelength coverage.
Glyphosate efficacy on eastern Canadian forest weeds. Part II: deposit–response relationships and crop tolerance
Authors: Pitt D. G. , Fleming R. A. , Thompson D. G. , Kettela E. G.
Published: December 2009

First-season herbicide efficacy and crop tolerance results are presented for a range of glyphosate (VISION®) rates (0–1.00 kg acid equivalent per hectare) aerially applied with two different dispersal systems (AU5000 Micronairs® and conventional hydraulic nozzles). Derivative-free nonlinear regression was used to model post-treatment raspberry cover (Rubusidaeus L. var. strigosus (Michx.) Maxim.) as an exponentially decreasing function of chemical deposit (R2 = 0.87). Similar methods were used to model post-treatment crown area as a function of chemical deposit and pretreatment crown area for pin cherry (Prunuspensylvanica L.f.) (R2 = 0.92), red maple (Acerrubrum L.) (R2 = 0.79), white birch (Betulapapyrifera Marsh.) (R2 = 0.93), elderberry (Sambucuspubens Michx.) (R2 = 0.85), and aspen (Populustremuloides Michx.) (R2 = 0.96). Acceptable first-season control (>60% cover reduction) of raspberry, pin cherry, elderberry, and aspen was achieved with rates of deposit ≥0.50 kg acid equivalent per hectare. Red maple and white birch crown area reduction averaged 60% at the highest rate tested (1 kg acid equivalent per hectare). Significant differences in efficacy attributable to the different dispersal systems were found only for pin cherry: the Micronair system resulted in 30% greater efficacy on one of the four blocks tested (P < 0.0001). On this particular block, characterized by unstable weather conditions during treatment, both systems produced significantly greater efficacy than observed on the other blocks for all species studied except aspen (P < 0.01). No significant differences were detected in black spruce (Piceamariana (Mill.) B.S.P.) health patterns in areas treated with the two different application systems (P = 0.780). Crop trees in untreated areas declined in health relative to trees in treated areas (P < 0.001).
Clear-cutting, woody residue removal, and nonsymbiotic nitrogen fixation in forest soils of the Inland Pacific Northwest
Authors: Jurgensen M.F. , Graham R.T. , Larsen M.J. , Harvey A.E.
Published: December 2009

The effect of clear-cutting and woody residue removal on soil nonsymbiotic nitrogen fixation, as estimated by the acetylene reduction technique, was investigated on a subalpine fir (Abieslasiocarpa (Hook.) Nutt.) site in western Montana and on a cedar (Thujaplicata (Donn ex D. Don) Lindl.)–hemlock (Tsugaheterophylla (Raf) Sarg.) site in northern Idaho. Nitrogen fixation in the forest floor, soil wood, and mineral soil on the subalpine fir site averaged 0.9 kg N•ha−1•year−1 in the uncut stand. This nitrogen input was reduced by 10% after clear-cutting followed by prescribed burning, and by 22% after clear-cutting followed by intensive residue removal. Nitrogen fixation in the uncut cedar–hemlock stand averaged 1.1 kg N•ha−1•year−1 and was reduced by 26% after prescribed burning. Clear-cutting only and clear-cutting followed by intensive woody residue removal had little effect on nitrogen fixation. However, large amounts of woody residue left on the cut site nearly doubled the amounts of nitrogen fixation compared with the uncut stand. Lower nitrogen fixation after harvesting on both the Idaho and Montana sites was due mostly to reductions in forest floor and large woody residue. Replacement of nitrogen losses from prescribed burning on these sites by nonsymbiotic nitrogen fixation and precipitation would take from 150 to 400 years, depending on the severity of the bum treatments.
Diversity of woody species 10 years after four harvesting treatments in the oak–pine type
Authors: McMinn James W.
Published: December 2009

Oak–pine stands in the Upper Piedmont of Georgia were whole-tree harvested to 10- and 2.5-cm DBH limits in both the dormant and early growing season, then allowed to regenerate spontaneously with no further perturbations. After 10 years, stands harvested in the early growing season exhibited higher diversity than those harvested in the dormant season. After the dormant-season harvests, 10-cm-limit stands tended to be more diverse than 2.5-cm-limit stands. The harvest disturbance primarily affected evenness, rather than species richness.
Réponse du β-glucosyle de l'alcool coniférylique du Pinussylvestris à l'inoculation du Ceratocystisbruneociliata au liber
Authors: Vagueresse M.H. Daurade - Le , Bounias M.
Published: December 2009

Inoculation of stems of Pinussylvestris with Ceratocystisbruneociliata leads to a decrease in the concentration of heterosides in inner bark samples collected from the necrotic area. Controls were collected from the trunc side opposite to the inoculated area and from healthy trees. Acidic and enzymatic hydrolysis of the heteroside fraction followed by chromatographic and spectral analyses indicated that the main component of this fraction was β-glucosyl-coniferyl alcohol. The latter product of hydrolysis was also observed in infected tissues. The released glucose may serve as an energy source for defense reactions in which the aglycone could be utilized as a precursor for the production of lignin in the formation of protective barriers or in the direct inhibition of fungus growth.
A note on root development, bud activity, and survival of Douglas-fir, and survival of western hemlock and noble-fir seedlings, following exposure to ethylene during cold storage
Authors: Blake John I. , Linderman Robert G.
Published: December 2009

Three cold storage experiments were conducted with bare-root Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings from coastal Oregon and eastern Washington Cascade sources. The objectives were to determine the effects of ambient, below-ambient (KMnO4 pellets), and 0.5 and 5 ppm ethylene during short-term storage on subsequent root development (expt. 1) and bud activity (expt. 2), and to relate these results to survival in the field after prolonged cold storage (expt. 3). Root numbers and lengths were measured 28 days following a 7-day storage period after lifting seedlings on September 27 and December 1. In the coastal source, root numbers and lengths in the 5 ppm ethylene treatment were, respectively, 46 and 49% greater in September, and 22 and 13% greater in December, than the controls. No comparable treatment effects were found for the Cascade source. Neither the KMnO4 nor the 0.5 ppm ethylene treatments affected root development in either seed source. For terminal buds in the controls, the number of days to 50% bud break was increased 2–8 days by a 30-day cold storage period compared with a 7-day period. For the coastal source, no increase in the time to 50% bud break was observed in the 5 ppm ethylene treatment. Seedling survival was evaluated in the field for the same treatments following 4 months cold storage for the Douglas-fir sources, coastal western hemlock (Tsugaheterophylla (Raf.) Sarg.), and noble fir (Abiesprocera Rehd.). Survival for the 5 ppm ethylene treatment compared with the control was increased by 55% in the coastal Douglas-fir source and by 13% in western hemlock. These results suggest that stimulated root development and bud activity may be partially responsible for the observed survival increase following cold storage at elevated ethylene levels.
Characterization of Lithium-based Solid Polymer Electrolytes
Authors: Barbosa Paula , Rodrigues Luísa , Silva Maria M. , Smith Michael
Published: December 2009

Sol-gel derived poly(oxyethylene)/siloxane hybrids doped with lithium hexafluoroantimonate, LiSbF6, have been prepared. Compositions of these novel xerogel electrolytes were identified using the conventional d-U(2000)nLiSbF6 notation, (where n is the molar ratio of oxyethylene moieties per Li+ ion) and samples with n between ∞ and 2.5 were characterized by conductivity measurements, cyclic voltammetry at a gold microelectrode and thermal analysis. The electrolyte films produced were obtained as transparent and amorphous monoliths with encouraging electrochemical and thermal properties.
Influence of Lithium Salts on Physicochemical Properties of Lithium Polysulphide Solutions in Sulfolane
Authors: Kolosnitsyn Vladimir , Kuzmina Elena , Karaseva Elena
Published: December 2009

The influence of the nature and concentration of lithium salts on the physicochemical properties (electrical conductivity and dynamic viscosity) of lithium polysulphide solutions in sulfolane was studied. We established that the viscosity of lithium polysulphide solutions increased significantly when lithium salts were added and at the same time the electrical conductivity practically did not change. We assumed that the lithium polysulphides are associated by the cross-link of lithium ions in solutions and there is a relay-race mechanism of charge transfer in lithium polysulphide solutions.
Fabrication and Characterization of Heteropolyacid Immobilized Membranes
Authors: Sachdeva Sonny , Sharma Neeraj , Emery Michael M. , Hamrock Steven J. , Herring Andrew M.
Published: December 2009

Lacunary heteropolyacids ([α-H8SiW11O39].14H2O) (HSiW11) have been immobilized in a perfluorosulfonic acid (PFSA) polymer with pendant side chain -O(CF2)4SO3H on metal oxide as a support using sol-gel method. Infrared spectroscopy revealed a strong interaction between the support material and the HSiW11. The surface morphology of the membrane, studied using the Scanning electron microscopy showed that the uniformly dispersed inorganic HSiW particles immobilized in the membrane have size range of 50-100 nm. The X-ray diffraction data revealed that the heteropolyacids exhibited an amorphous character in the ionomer matrix evident from the broadening of the HPA peaks. Proton conductivity of the HSiW loaded as well as the control membrane has been obtained at 100 and 30% relative humidity in the temperature range of 50-120 oC. The conductivity of the HSiW immobilized membranes increased with the increase in temperature and humidity and was observed to be higher than the control PFSA ionomer membrane.
The Influence of the Semiconducting Properties of Passive Films on Pitting Resistance
Authors: Harrington Scott P. , Devine Thomas M.
Published: December 2009

The pitting resistance of transition metals and alloys is influenced by the semiconducting properties of the n-type passive films that form on their surface. Chromium rich films that have flatband potentials significantly lower than their corrosion potentials develop large energy barriers to charge transfer, which inhibits the reduction reaction. Sluggish reduction kinetics both suppresses a material's corrosion potential, which decreases pitting activity, and decreases the rate of oxidation that can take place inside occluded regions, which makes pits more likely to repassivate. Conversely, iron's passive film has a flatband potential above its corrosion potential in chloride solutions, which leads to an ohmic contact with the electrolyte and contributes to iron's low pitting resistance.
Electromagnetic Induction Corrosion Control Technology (EICCT)
Authors: Macdonald Digby D. , Lewis Michael , McLafferty Jason , Peek Randy
Published: December 2009

Over the past several years, a new corrosion control technology has been developed for protecting damaged, painted surfaces in contact with ambient atmospheres. The method makes use of electromagnetically-induced surface currents and, to date, the efficacy of the method has been demonstrated with painted, galvanized steel. While the exact mechanism of protection has yet to be thoroughly defined, the technique appears to work by the induced current inhibiting passivation of the zinc and hence maintaining the zinc in the active state. Accordingly, the active zinc is more effective in protecting the underlying steel, compared with passivated zinc in the absence of the electromagnetically-induced current. Thus, the technique is not a classical, impressed current cathodic protection system and no electrolyte is needed between an anode (which does not exist, anyway) and the damaged area. Experiments have demonstrated that the induced current is spread uniformly across the surfaces of complex shapes, so that induction at a single point is effective in protecting the whole body, that the power consumption is very low, and possibly that the induced signal can be tailored to optimize the efficacy. To our knowledge, EICCT is a new, radically different corrosion control technology that may find extensive application in protecting metallic structures.
Carbon Nanotube Structures as Ionic Barriers: A New Corrosion Prevention Concept
Authors: Sreevatsa Sreeya , Grebel H.
Published: December 2009

We consider a new concept - the electronic barrier - for corrosion prevention. The barrier is an electronic p-n junction made by topping one film of functionalized carbon nanotubes on another. Potentiodynamic tests, Raman spectroscopy and inspection by scanning electron microscope revealed that the order of the layers (namely, p-n or n-p) with respect to the metal surface does determine whether the metal corrodes or not.
Sub-Surface Electrochemical Effects on the Spontaneous Deposition of Cerium Conversion Coatings on Aluminum Alloys
Authors: Treu Becky L. , Joshi Simon , Pinc William R. , O'Keefe Matthew , Fahrenholtz William
Published: December 2009

The combination of CeCl3 and H2O2 in cerium-based conversion coating (CeCC) solutions causes the dissolution of the aluminum alloy substrate, resulting in formation of voids a few microns below the surface during deposition. Localized, excessive dissolution of aluminum occurs near intermetallic particles over approximately 10% of the substrate surface. Alternate deposition methods were explored whereby either H2O2 or chloride content was reduced to minimize dissolution. An alternative oxidant, NaClO4, added to offset the impact of lower H2O2 content. CeCCs were deposited without sub-surface voids, but the resulting coatings had poor corrosion protection compared to CeCCs deposited with H2O2 alone. Coatings prepared with alternate Ce3+ salts using different ratios of CeCl3 and Ce(NO3)3, along with higher concentrations of H2O2, were thicker and more uniform than coatings with lower H2O2 content. However, CeCCs deposited from solutions containing H2O2 and CeCl3 had the highest overall electrochemical impedance and exhibited the best corrosion protection.
Electrochemical Study of Corrosion Behavior of Rare Earth Based Chemical Conversion Coating on Aerospace Aluminum Alloy
Authors: Kiyota Sayuri , Valdez Benjamín , Stoytcheva Margarita , Zlatev Roumen , Schorr Michael
Published: December 2009

The anticorrosion properties of cerium and praseodymium based chemical conversion coatings deposited on AA6061-T6 were evaluated in NaCl 0.01 M aqueous solution at room temperature using Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization (PDP). Coatings microstructure and morphology were observed by Scanning Electron Microscopy (SEM). Coatings compositions were characterized by Energy Dispersive X-Ray Spectroscopy (EDX). The obtained results showed that: 1) Cerium sulphate based coatings possess superior resistance to localized corrosion in comparison to the praseodymium nitrate based ones; 2) One minute of immersion shows good anticorrosive properties of the Ce2(SO4)3 based coatings; 3) Post-deposition phosphate treatment notably improves the anticorrosive behavior and 4) Hydrogen peroxide addition to the cerium based formulation accelerates the coating formation.
Peculiarities of Inhibition Copper Local Activation by Benzotriazole Under Different Temperatures
Authors: Skrypnikova Ekaterina , Kaluzhina Svetlana , Agafonova Lubov
Published: December 2009

It was made the estimation of possibility benzotriazole (BТАН) action in the concentration range 1×10-7÷1×10-2 M for inhibition of copper local activation (LA) in alkaline-chloride and alkaline-sulphate solutions. It was shown, that BТАН inhibits copper LA according to adsorption-polymerization mechanism at both studied systems, and its efficiency grows under additive concentration and temperature of background solution increase.
Deterministic Modeling of the Corrosion of Low-Carbon Steel by Dissolved Carbon Dioxide and the Effect of Acetic Acid. I-Effect of Carbon Dioxide.
Authors: Rosas-Camacho Omar , Uquidi-Macdonald Mirna , Macdonald Digby D.
Published: December 2009

Carbon dioxide corrosion of carbon steel in brine has been a recognized problem in oil production and it is becoming more common with the use of CO2-flooding as an oil recovery technique. The presence of acetic acid is systematic in oil fields, however, its role in corrosion has not been well-recognized and it is still debated. The present work was carried out, first, focusing on an understanding of CO2-corrosion of low-carbon steel and, later to ascertain the effect of acetic acid. This understanding is achieved by developing a deterministic model that explains and accounts for the experimental observations from Electrochemical Impedance Spectroscopy (EIS) data. The impedance model, based on the Point Defect Model, provides a good account of the formation and growth of a bi-layer that comprises an oxide (inner) layer adjacent the surface and a precipitated (outer) layer of siderite, FeCO3, forming on the top of the inner layer.
Topologically Ordered Corrosion Maps of Nickel Alloys
Authors: Uquidi-Macdonald Mirna , Kamrun-Nahar Mst
Published: December 2009

This study was developed to provide an optimum methodology for designing metal alloys. Information on general and localized (pitting and crevices) corrosion of the most commonly used Nickel alloys were obtained from NIST. A 2-dimentional Kohonen map was designed and trained with the available data. We constructed a 3D figure (2D Kohonen map and a third dimension containing the corrosion rates of each cell in the Kohonen map) for all alloy-environment couples in the data. Once the Kohonen map was trained, we "designed" new Nickel-alloys by choosing two of the alloys (C22 and Incoloy 825 (UNS: N008825, alloy 825)) on the Nickel NIST list (composition, environment and corrosion rates), and by systematically modifying the alloy compositions by adding minor alloy elements (one at a time). For the newly created alloy, we chose the same environment as that of the original alloys (C22 or Incoloy 825). We located-in the Kohonen map-- the cells in which the original alloys (C22 and Incoloy 825) were stored; then, we located in which cells the "new alloys" are clustered. The alloys may migrate towards higher or lower corrosion rate cells. Accordingly, the beneficial or detrimental impact of adding those minor alloy elements in the alloys of origin (C22 or Incoloy 825) can be explored. Thereby, the "evolutionary road" of corrosion properties of metal alloys can be traced in the 3D figure and "If-then" scenarios for the new alloys - can be explored.
Selection of Electrode Area for Electrochemical Noise Measurements for CO2 Corrosion in Different NaCl Solutions
Authors: Jiang Xiu , Nesic Srdjan
Published: December 2009

Electrochemical investigation of localized CO2 corrosion of X-65 mild steel in 0.1, 1.0, 10 and 20 wt% NaCl solutions at 80oC has been conducted using linear polarization resistance (LPR) and electrochemical noise (EN) techniques. EN measurements were carried out only on 11.6 cm2 electrodes in 0.1, 10 and 20 wt % NaCl solution. EN was obtained from both 11.6 cm2 and 1 cm2 electrodes in 1 wt % NaCl solution to learn how the surface area affects EN measurements. Current noise and potential noise between two nominally identical electrodes were simultaneously recorded using a ZRA (Zero Resistance Ammeter). Chemical dissolution of corrosion product layer was accomplished by adjusting pH and saturation values with respect to FeCO3. Surface morphologies and pit depths were observed by scanning electron microscopy (SEM) and infinite focus microscopy (IFM) for 3D optical analysis. The results showed that electrode size influenced the EN signal. Transients related to metastable pitting were best observed with 1 cm2 coupons in 1 wt % NaCl solutions, but such transients were not clearly obtained for 11.6 cm2 coupons in the 0.1, 1, 10, 20 wt % NaCl solution. Both general corrosion rate and localized corrosion rate did not significantly change with increasing NaCl concentrations.
Embedded Reference Electrode for Potential-Monitoring of Cathodic Protective Systems
Authors: Merten Bobbi Jo E. , Battocchi Dante , Tallman Dennis , Bierwagen Gordon
Published: December 2009

Micron-scale silver (Ag) wires were chemically oxidized in 0.05M FeCl3 solution to form Ag/AgCl reference electrodes. The wire electrodes were embedded between a topcoat and metal-rich primer-a sacrificial coating-to monitor the corrosion protection by its open circuit potential (OCP). A metal-rich system equipped with an embedded reference electrode (ERE) would allow in-situ measurement of the OCP; this indicates the level of protection afforded by the coating to the substrate and aims to eliminate the standard, less-accurate practice of scheduled maintenance. Measurement of the metal-rich primer/substrate OCP versus the ERE, and also versus a saturated calomel electrode (SCE), were the key experimental techniques to verify the concept's validity. Also, potentiodynamic experiments were utilized to mimic imposed-potential cathodic protection systems; the potential versus ERE, recorded with an additional potentiostat, responded favorably. This study shows the feasibility of a Ag/AgCl ERE for use in cathodic protective systems by effectively relaying OCP information. Further experiments using electrochemical impedance spectroscopy (EIS) and in-situ OCP measurements in a salt spray chamber strengthen this conclusion. This methodology allows the possibility of upgrading the monitoring and control systems currently used for imposed cathodic protection as well as the in-situ observation of corrosion protection levels for metal-rich sacrificial coatings.
Effect of Carbon Content on the Electrochemical Impedance of As-Cast CoCrMo Alloys
Authors: Montero-Ocampo Cecilia , López Martínez Eduardo
Published: December 2009

In this work, the effect of carbon content on the resultant impedance diagrams and surface appearance of ASTM-F75 as-cast cobalt-based alloys was investigated. The electrochemical properties of the alloy in the passive and transpassive states were studied. Potentiodynamic polarization and electrochemical impedance spectroscopy tests were carried out. It was found that the properties of passive film on CoCrMo alloy changed with potential. The highest resistance to pitting corrosion of the passive film was observed for the low C content alloy which was attributed to a greater chemical and microstructural homogeneity (e.g. a uniform distribution of fine carbides and fine grained structure) in the as-cast condition. The results of the investigation led to the conclusion that the use of low C content ASTM-F75 as-cast alloys in the manufacture of orthopedic implants may result in a lower release rate of corrosion products which should improve the in vivo performance of the implants.
Laser Treated Carbon Composites for the Determination of Suicide Biomarkers: Development of a Forensic Diagnosis Device
Authors: Villalba Maria , Slater Stacey , Davis James
Published: December 2009

The ongoing debate about the possible link between the serotonin metabolite - 5-hydroxyindoleacetic acid (5-HIAA) - and suicidal behavior requires a more robust specification of reference ranges for normal and "at risk" subjects. As such, there is a need for a revision of analytical techniques for the speedy, selective and sensitive detection of the monoamine biomarkers. A new approach to the production of a carbon composite electrode and its solvent free, laser ablative modification to enhance the performance in the detection of the neurotransmitters is presented. The integration of the electrodes within conventional chromatographic architectures is assessed and its use in the quantification of 5-HIAA within human urine has been critically evaluated and found to be superior to the HPLC-UV.
A Mössbauer Spectroscopy Study of Electronic Processes in LixFePO4
Authors: Tan Hongjin , Dodd Joanna , Fultz Brent
Published: December 2009

LixFePO4 solid solutions with different lithium concentrations, x, were investigated by Mössbauer spectrometry at temperatures between 25° and 210°. The Mössbauer spectra show a temperature dependence of their isomer shifts (EIS) and electric quadrupole splittings (EQ), typical of thermally-activated, electronic relaxation processes involving 57Fe ions. The activation energies for the fluctuations of EQ and EIS do not have a measurable dependence on the concentration of lithium, but varies between Fe3+ and Fe2+. Typically, for the Fe2+ components of the spectra, the fluctuations of EQ occurred at lower temperatures than the fluctuations of EIS, with activation energy of 512 meV for EQ and 551 meV for EIS. The more facile fluctuations of EQ for Fe2+ are evidence for local motions of neighboring Li+ ions.
High Voltage (~5V) Olivine-Type LiCoPO4/C Nano-Particle Cathode Material Synthesized from Modified Solid State Reaction
Authors: Gnanaraj Joseph S. , Puglia Frank , Lucht Bratt , Yang Li
Published: December 2009

Nano particle sized LiCoPO4 cathode material was synthesized through modified solid state reaction and other methods. Carbon coating on the surface of the cathode material particles was carried out using an in situ carbon coating procedure. The calcination temperatures between 550° and 750° were used to synthesize cathode materials. The synthesized cathode materials were characterized by X-ray powder diffraction (XRD) for structure determination, scanning electron microscopy (SEM) for morphology studies, particle size analyses. Coin/pouch cells were built and cycled in standard carbonate based lithium hexafluoride phosphate (LiPF6) electrolyte solutions. The cathode film forming additives include 2,3-dihydrofuran (2,3-DHF) and 2,5-dihydrofuran (2,5-DHF), LiFOB, and vinylene carbonate (VC) were also investigated in cells.
Hydrothermal Processed TiO2 Nanoparticles for Optimization in Dye-Sensitized Solar Cells Using Statistical Experimental Strategies
Authors: Yang Chien-Hsin , Liao Shao-Hong
Published: December 2009

Nanostructure TiO2 is prepared using the hydrothermal process for applications as an anode in dye-sensitized solar cells (DSSCs). The effect of such fabrication conditions as the resistance of fluorine doped tin oxide-coated (FTO) glass, polyethylene glycol (PEG) content in TiO2 paste, TiO2 film thickness, electrolyte solvent, and the preparation of Pt counter electrode on the performance of the DSSC device, is systematically studied using fractional factorial design methodology. Fractional factorial analysis indicates that the effects of TiO2 film thickness, preparation of Pt counter electrode, as well as the two-factor interactions of FTO substrate and TiO2 film thickness, TiO2 film thickness and electrolyte solvent, and TiO2 film thickness and preparation of Pt counter electrode, are the key variables influencing the device efficiency. The optimal conditions of the device efficiency occurs for a 10 Ω/square FTO substrate, 15 wt% PEG content in TiO2 paste, ~ 6 μm TiO2 film thickness, MPN solvent in electrolyte, and spin-coated Pt counter electrode, generating a maximum device efficiency of ~ 9 %.
EIS Analysis of the Triple Phase Boundary Model
Authors: Dhanda Abhishek , O'Hayre Ryan , Pitsch Heinz
Published: December 2009

TPB properties at the Pt/Nafion interfaces in a PEMFC depend on the relative rates of reaction and diffusion processes. In this work, electrochemical impedance analysis is performed to model the coupling between the reaction and diffusion phenomena in the TPB zone. Transfer function for the PEMFC system is obtained for the ORR reaction mechanism where the first electron transfer step is considered as the RDS. An analytical expression is derived for the coupled impedance element based on the transient concentration profile and the ORR kinetics. The model is used to study the transient response of a PEMFC system in terms of the TPB parameters.
Electrodeposition of Heavy Metals (Cu; Ni; Zn and Cd) from Industrial Effluents
Authors: Addi Yassine , Duverneuil Patrick , Khouider ALI
Published: December 2009

Our technique consists on the recuperation of heavy metals such as Cu; Ni; Zn and Cd from an industrial wastewater by electrode position. The experiments were carried out in a cell of a capacity of 1 litre. The electrodes are made of stainless steel sheets for the cathode with a surface of 1dm2 and a grid anode of titanium coated with ruthenium oxide. The water flow (1) was constant and kept at a rate of 0, 35 l/min. The pH of the solution was at 1 for the removal of Cu; Ni; Zn and Cd. Different values of current densities are applied to remove elements. More than 98% of metal reduction was obtain and the solution obtained contains metals concentrations in agreement with Algerian legislations.
Diffusivity of Oxygen in Molten Lead - Bismuth Eutectic Alloy (44.5% Pb - 55.5% Bi)
Authors: Verdaguer Ariadna , Colominas Sergi , Abella Jordi
Published: December 2009

Lead - bismuth eutectic alloy, LBE. (44.5% Pb - 55.5% Bi) is one of the proposed alloys to be used as a coolant for Accelerator Driven System reactors. LBE is highly corrosive for structural steels. In order to avoid this corrosion, a passivation layer of magnetite on the structural material should be formed and maintained stable. In this direction, many studies about physicochemical properties of oxygen in molten LBE have been performed. In this work, a method to determine the oxygen diffusivity in LBE has been developed. It is based in the following electrochemical cell: O2 (reference mixture), Pt // YSZ // O2 (LBE) Oxygen diffusion coefficient at 460, 500 and 540ºC has been obtained. They show a good agreement with other bibliographic experimental data, so the method presented in this work is a good way to determine oxygen diffusion in LBE
Application of Single-Use PCB Gold Disc Electrodes for "in-situ" Determination of As(III) in Natural Waters
Authors: Zlatev Roumen , Stoytcheva Margarita , Valdez Benjamin , Álvarez Lidia , Cobo Juan
Published: December 2009

A simple and cheap type of disposable Au disc electrodes was developed and fabricated by PCB technology, massively used in electronic industry. This electrodes were successfully applied for "in-situ" As(III) determination in natural ground waters by the Square Wave Anodic Stripping Voltammetry (SWASV). A detection limit of 5.8 μg/L was reached at 20 s deposition time and -480 mV deposition potential. A conductometry based method was developed allowing the achievement of results reproducibility of 7.8 % to 1.5 % for the As(III) concentrations in the range from 5.8 μg/L to 250 μg/L by surface reproducibility correction of the disposable electrodes.
Determination of Heavy Metals in Samples with Caolite of Guanajuato by Voltammetry with Anodic Redisolution
Authors: Pineda Kevin A. , Bustos Erika , García María G.
Published: December 2009

In this work the results are reported of the content of ionic metal as Pb2+, Cd2+, Cu2+, Zn2+ and Hg2+ in samples of water and minerals. The metals were determined by the method of Voltammetry with Anodic Redisolution at constant potential of -1.2 V vs. Ag/AgCl (saturated KCl) at the same time of pre-concentration during 360 s, the speed sweeping was of 70 mV/s and the biggest current of pick was observed. The electrolyte support was evaluated, as 0.1M HCl, 0.001M KCl and 0.01M KNO3, on a layer of Hg over the glassy carbon electrode. A straight line were determined in base of the calibration curves in presence of the different metals in different concentration values, 49.2 to 325 µg/L for Pb2+, Cd2+, Cu2+, and 1140 to 2369 µg/L to Zn2+ with lineal regression coefficient of 0.9978 for each one the metals determinate. The content of metals in the samples, they were determined by means of extrapolation and the method of standard addition.
Limiting Current Studies in an Electrodialysis Cell: Influence of Mean Linear Velocity and KCl Concentration in the Diluate Channel
Authors: Alvarado Montalvo Lucia G. , Ojeda Escamilla Carmen , Delgadillo Gómez Jose A. , Rodríguez- Torres Israel
Published: December 2009

This work aims to obtain the limiting current for an electrodialysis cell in function of linear velocity and salt concentration. The current was read at each velocity for different KCl concentrations. The limiting currents were obtained from dilute resistance-reciprocal of current curves. Fitting the limiting current density (ilim) values vs. linear velocity (u) for each KCl concentration, allowed to determine the coefficients m and n of the empirical correlation ilim= m u^nC. n varied from 24994 to 12208 A snm1-n keq-1 and n between 0.41 -0.39. n showed a little dependence on hydrodynamic conditions and a strong reliance on salt concentration, whereas m is affected only by the salt concentration.
Identification of Flavonoid Oxidation Potentials as a Function of pH
Authors: Gómez Pineda Luis E. , Oropeza-Guzmán Mercedes T. , Pina-Luis Georgina
Published: December 2009

The electrochemical oxidation of 3-hydroxyflavone, 6-hydroxyflavone and 2',3,4',5,7-pentahydroxyflavone (Morin) on a glassy carbon electrode have been studied, using cyclic and square-wave voltammetry techniques, over a wide pH interval. The study reveals that the mechanism of electron transfer is a complex and pH dependent process. The oxidation of 3-hydroxyflavone showed two peaks in acidic medium corresponding to the oxidation of OH group at C-3 and OH group at C-4, according with the equilibrium between the neutral and cationic species (Scheme 2). The 6-hydroxyflavone only exhibit one peak in all pH range, corresponding to the oxidation of OH group at C-6. The oxidation mechanism of Morin proceeds in sequential steps, related with the OH groups in the resorcinol moiety at ring B and OH group at C-3 of the flavonoid structure. The chemical and electrochemical optimal conditions for simultaneous determination of these flavonoids are described.
Analysis of the Oxygen Reduction Reaction on Au/C Particles Using the Electrochemical Impedance Spectroscopy
Authors: Vázquez-Huerta Gerardo , Ramos-Sanchez Guadalupe , Antaño-López René , Solorza-Feria Omar
Published: December 2009

Au particles with nanometric size (~5nm) were synthesized from AuCl3 reduction by NaBH4. Au particles supported in Carbon Vulcan XC-72 (Au/C) were used as working electrode in a 0.5M H2SO4 solution saturated with O2. The Nyquist and Bode spectra of Au/C obtained at potentials (E) greater than 0.38 V vs NHE show a single loop, associated to the reduction of O2 to H2O2. The impedance spectra of Au/C for E < 0.38 V show a second loop associated to a second process, ie. the reduction of H2O2 to H2O. The values of Rtc1 corresponding to the first loop were used in order to calculate the kinetic parameters of the oxygen reduction reaction (ORR). The values of the Tafel slope (b) and the charge transfer coefficient (α) obtained from impedance spectra are -0.111 V/dec-1 and 0.53, respectively.
Electrochemical Study of Co(II)/Co(III) on Different Electrode Materials for Energy Storage in Redox Flow Cells
Authors: Lopez-Estrada Salvador A. , Alatorre-Ordaz Alejandro , Gutierrez-Granados Silvia , Ponce-de-León Carlos , Walsh Franck C.
Published: December 2009

The development of redox flow cells has been carried out through the use of several redox couples which oxidize and reduce to store electrical energy. Some of the problems encountered in redox cells include: low solubility of redox couples, slow kinetics, low stability of electrode materials and high toxicity of the electroactive species. In this paper, Co(III)/Co(II) has been investigated as a possible electroactive material because of its high oxidizing power and the low toxicity of Co(III). The electrochemical study of Co(III)/Co(II) was carried out on electrodes of vitreous carbon, Au, Pt, Pb and stainless steel, type 316. Results show that the high oxidizing power of Co(III) does not enable its reduction reaction in the aforementioned electrode materials possibly due to electrode surface corrosion and water oxidation. However, the electrolysis of Co(III) with a Pb electrode shows that the system is reversible and forms PbO2 on the electrode surface.
Electrochemical Characterization of CPEs Modified with Gold Nanoparticles Deposited by Immersion
Authors: Beristain-Ortiz Gabriela , Hernández-Guevara Esteban , Reynoso-Soto Edgar , Rivero-Espejel Ignacio , Oropeza-Guzmán Mercedes T.
Published: December 2009

In this work a bibliographical review is presented as well as preliminar experiments on the development of modified electrodes with metallic nanoparticles. These electrodes showed good properties as: sensitivity, limit of detection, stability and catalytic activity. When modifying the sensing surface of the carbon paste electrodes (CPEs) benefits like: low cost and renewable surfaces are obtained. In recent works, cyclic voltammetry studies (VC) have been widely used in the electrodeposition of nanoparticles as well as in the characterization of the electrodes. The modification of CPE was done by inmersion in colloidal solutions of gold nanoparticles of different sizes as prospective sensors for toxic components especially in extremely low concentrations.
Synthesis and Characterization of Bimetallic PdM Nanoparticles (M =Ag, Cu) Oxygen Reduction Electrocatalysts
Authors: Martínez-Casillas Diana C. , Solorza-Feria Omar
Published: December 2009

Electrochemical studies on the catalytic activity of bimetallic PdAg and PdCu compounds for the oxygen reduction reaction (ORR) in acid media are presented. The electrocatalytic activity for the ORR was evaluated using cyclic voltammetry (CV) and rotating-disk electrode (RDE) measurements in a 0.5 M H2SO4 electrolyte at 25 {degree sign}C. These materials were synthesized through PdCl2, AgNO3 and CuCl reductions with NaBH4 in a THF solution. The synthesized powder electrocatalysts were characterized by powder X-ray diffraction (XRD) and data analyzed with the software MDI jade 5.0. The XRD results show evidence of the alloy particles with 3nm as average sizes. The electrochemical current-potential behavior was compared with the Palladium and Platinum. Kinetics results show that the bimetallic catalysts containing Ag and Cu are more active for the ORR than the Pd pure, and less active than the nanometric Pt.
Industrial Wastewater Treatment by Electrocoagulation-Direct Anodic Oxidation System
Authors: Linares-Hernández Ivonne , Barrera-Díaz Carlos , Juárez-GarcíaRojas Pablo C. , Roa-Morales Gabriela , Ureña Fernando
Published: December 2009

This paper shows the results of experimental investigations in industrial wastewater treatment by electrochemical processes, the first one uses iron electrocoagulation and the second employs boron-doped diamond electrooxidation. The coupled treatment reduced chemical oxygen demand (COD) by 99 %, color by 100 % and turbidity by 100 %. The initial and final quality levels in the wastewater were monitored using UV-Vis spectrometry and cyclic voltammetry.
Study of Copper Electrodeposition from Ammonia Bath with Different Electrochemical Techniques
Authors: Figueroa-Ramírez Sandra J. , Miranda-Hernández Margarita
Published: December 2009

An electrochemical study for the copper electrodeposition on nanostructured carbon black films electrodes supported in glassy carbon (GC) is presented, using the cyclic voltammetry of reversal potential (Eλ), chronoamperometry, chronocoulometry and chronopotentiometry techniques in the electrolytic system 10-3M CuCl2;1M NH4OH, 1M KCl, pH =10. The cyclic voltammetry studies allow characterizing the potential range by copper electrodeposition in two steps: Cu(II) to Cu(I) and Cu(I) to Cu(0). A Chronocoulometry study shows an important adsorption process of chlorine ions, couple to the copper deposit. The quantity of monolayer and atoms of metallic copper, were evaluated by chronopotentiometry studies.
Analysis of the Copper Electrodeposition Current Transients in Nitrates Media
Authors: Aguilar-Sánchez Miriam , Palomar-Pardavé Manuel , Corona-Avendaño Silvia , Romero-Romo Mario Alberto , Ramírez-Silva Teresa , Scharifker Benjamin , Mostany Jorge , Rodriguez-Torres Israel
Published: December 2009

This work deals with the kinetic changes originated by nitrate presence on copper nucleation. From analysis of experimental potentiostatic current transients recorded during copper electrodeposition from aqueous solutions, with and without nitrate ions, it is shown that when NO3- are present, the copper nucleation rate increases while the number density of active site almost remains constant for every applied potential considered.
Cobalt Electrodeposition Process from Electrolytic Baths based on CoSO4 and (NH4)2SO4. Influence of [Co(II)]
Authors: Granados Neri Madai , Mendoza-Huizar Luis H.
Published: December 2009

In this work we carried out an electrochemical study of the cobalt electrodeposition from ammonium sulfate solutions (x CoSO4 + 1M (NH4)2SO4, where x=0.005, 0.01, 0.05 and 0.1M) onto glassy carbon electrode. From the potentiostatic study, it was obtained that the nucleation rate increases with the increment of cobalt in the plating bath. From our thermodynamic study we found that the [Co(H2O)6]2+ chemical specie was the predominant complex. The conditional equilibrium potential (Eq) depends on the cobalt concentration in the solution, thus an increase in [Co(II)] decreases the Eq. A clear linear tendency in the plot lnA vs E was observed for systems II and III. However, non linear plots were gotten for systems I and IV, indicating the existence of additional processes that affects the nucleation and growth mechanisms.