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Sample records for air electrode surface

  1. Oxide modified air electrode surface for high temperature electrochemical cells

    DOEpatents

    Singh, Prabhakar; Ruka, Roswell J.

    1992-01-01

    An electrochemical cell is made having a porous cermet electrode (16) and a porous lanthanum manganite electrode (14), with solid oxide electrolyte (15) between them, where the lanthanum manganite surface next to the electrolyte contains a thin discontinuous layer of high surface area cerium oxide and/or praseodymium oxide, preferably as discrete particles (30) in contact with the air electrode and electrolyte.

  2. Experimental study of cylindrical air electrodes

    NASA Astrophysics Data System (ADS)

    Viitanen, M.; Lamminen, J.; Lampinen, M. J.

    1991-11-01

    The electrodes studied here are cylindrical and prepared to be placed inside the inner surface of a sintered brass tube, which is nickel-plated. Previously we have reported on the preparation of flat air electrodes and also on long run tests carried out with these electrodes. The electrode material was prepared by the so-called wet method to obtain a carbon dough which is easy to handle. The material preparation remains the same, but owing to the different geometrical shape, the preparation of the electrode itself is quite different. We have studied here the long-term performance of these new cylindrical air electrodes and at the same time measured the carbonate content of the electrolyte. We have also analyzed by comparative methods which property of the electrode lowers the performance after a fairly long period.

  3. Bifunctional oxygen/air electrodes

    NASA Astrophysics Data System (ADS)

    Jörissen, Ludwig

    A selective review on the materials and construction principles used for bifunctional oxygen/air electrodes is given. The discussion emphasizes the catalytically active materials used for the construction of these electrodes, which are a key component in electrically rechargeable air breathing electrochemical systems. Whereas, in acid electrolytes normally noble metal catalysts must be used, there is a possibility to use less expensive transition metal oxides in alkaline electrolytes. Typical transition metal oxides have the perovskite, pyrochlore and spinel structure.

  4. Zinc electrode and rechargeable zinc-air battery

    SciTech Connect

    Ross, P.N. Jr.

    1989-06-27

    This patent describes an improved zinc electrode for a rechargeable zinc-air battery comprising an outer frame and a porous foam electrode support within the frame which is treated prior to the deposition of zinc thereon to inhibit the formation of zinc dendrites on the external surface thereof. The outer frame is provided with passageways for circulating an alkaline electrolyte through the treated zinc-coated porous foam. A novel rechargeable zinc-air battery system is also disclosed.

  5. Zinc electrode and rechargeable zinc-air battery

    SciTech Connect

    Ross, Jr., Philip N.

    1989-01-01

    An improved zinc electrode is disclosed for a rechargeable zinc-air battery comprising an outer frame and a porous foam electrode support within the frame which is treated prior to the deposition of zinc thereon to inhibit the formation of zinc dendrites on the external surface thereof. The outer frame is provided with passageways for circulating an alkaline electrolyte through the treated zinc-coated porous foam. A novel rechargeable zinc-air battery system is also disclosed which utilizes the improved zinc electrode and further includes an alkaline electrolyte within said battery circulating through the passageways in the zinc electrode and an external electrolyte circulation means which has an electrolyte reservoir external to the battery case including filter means to filter solids out of the electrolyte as it circulates to the external reservoir and pump means for recirculating electrolyte from the external reservoir to the zinc electrode.

  6. Volume-surface barrier discharge in dried air in three-electrode system fed by impulse high voltage with nanosecond rise time

    NASA Astrophysics Data System (ADS)

    Malashin, Maxim; Rebrov, Igor; Nebogatkin, Sergey; Sokolova, Marina; Nikitin, Alexey; Voevodin, Vadim; Krivov, Sergey

    2016-08-01

    Results of experimental investigation of a volume-surface barrier discharge in a three-electrode system under periodic impulse voltage applied to the surface discharge (SD) electrodes and a d.c. potential applied to an additional third electrode are presented. It is shown that there is a strong influence of polarity and amplitude of the d.c. potential on the direct current "extracted" out of the surface discharge plasma layer by electric field of the third electrode. The amount of charged positive species that constitute the "extracted" current prevails under positive impulse voltage for low values of the negative d.c. potential of the third electrode. The amount of negative species prevails with higher values of the positive d.c. positive of the third electrode. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  7. Metal | polypyrrole battery with the air regenerated positive electrode

    NASA Astrophysics Data System (ADS)

    Grgur, Branimir N.

    2014-12-01

    Recharge characteristics of the battery based on the electrochemically synthesized polypyrrole cathode and aluminum, zinc, or magnesium anode in 2 M NH4Cl are investigated. It is shown that polypyrrole electrode can be regenerated by the reoxidation with the dissolved oxygen from the air. Using the polypyrrole synthesized on high surface graphite-felt electrode under modest discharge conditions, stable discharge voltage of 1.1 V is obtained. Such behavior is explained by the complex interaction of polypyrrole and hydrogen peroxide produced by the oxygen reduction reaction. The electrochemical characteristics are compared with the zinc-manganese dioxide and zinc-air systems.

  8. Surface characterization of platinum electrodes.

    PubMed

    Solla-Gullón, José; Rodríguez, Paramaconi; Herrero, Enrique; Aldaz, Antonio; Feliu, Juan M

    2008-03-14

    The quantitative analysis of the different surface sites on platinum samples is attempted from pure voltammetric data. This analysis requires independent knowledge of the fraction of two-dimensional (111) and (100) domains. Specific site-probe reactions are employed to achieve this goal. Irreversibly-adsorbed bismuth and tellurium have been revealed to be sensitive to the presence of (111) terrace domains of different width whereas almost all sites involved in (100) ordered domains have been characterized through germanium adatoms. The experimental protocol follows that used with well-defined single-crystal electrodes and, therefore, requires careful control of the surface cleanliness. Platinum basal planes and their vicinal stepped surfaces have been employed to obtain calibration plots between the charge density measured under the adatom redox peak, specific for the type of surface site, and the corresponding terrace size. The evaluation of the (100) bidimensional domains can also be achieved using the voltammetric profiles, once the fraction of (111) ordered domains present in the polyoriented platinum has been determined and their featureless contribution has been subtracted from the whole voltammetric response. Using that curve, it is possible to perform a deconvolution of the adsorption states of the polycrystalline sample different from those related to (111) domains. The fraction of (100)-related states in the deconvoluted voltammogram can then be compared to that expected from the independent estimation coming from the charge involved in the redox process undergone by the irreversibly-adsorbed germanium and thus check the result of the deconvolution. The information about the surface-site distribution can also be applied to analyze the voltammetric profile of nanocrystalline platinum electrodes.

  9. PEDOT:PSS as multi-functional composite material for enhanced Li-air-battery air electrodes

    PubMed Central

    Yoon, Dae Ho; Yoon, Seon Hye; Ryu, Kwang-Sun; Park, Yong Joon

    2016-01-01

    We propose PEDOT:PSS as a multi-functional composite material for an enhanced Li-air-battery air electrode. The PEDOT:PSS layer was coated on the surface of carbon (graphene) using simple method. A electrode containing PEDOT:PSS-coated graphene (PEDOT electrode) could be prepared without binder (such as PVDF) because of high adhesion of PEDOT:PSS. PEDOT electrode presented considerable discharge and charge capacity at all current densities. These results shows that PEDOT:PSS acts as a redox reaction matrix and conducting binder in the air electrode. Moreover, after cycling, the accumulation of reaction products due to side reaction in the electrode was significantly reduced through the use of PEDOT:PSS. This implies that PEDOT:PSS coating layer can suppress the undesirable side reactions between the carbon and electrolyte (and/or Li2O2), which causes enhanced Li-air cell cyclic performance. PMID:26813852

  10. Surface potential distribution and airflow performance of different air-exposed electrode plasma actuators at different alternating current/direct current voltages

    SciTech Connect

    Yang, Liang; Yan, Hui-Jie; Qi, Xiao-Hua; Hua, Yue; Ren, Chun-Sheng

    2015-04-15

    Asymmetric surface dielectric barrier discharge (SDBD) plasma actuators have been intensely studied for a number of years due to their potential applications for aerodynamic control. In this paper, four types of actuators with different configurations of exposed electrode are proposed. The SDBD actuators investigated are driven by dual-power supply, referred to as a fixed AC high voltage and an adjustable DC bias. The effects of the electrode structures on the dielectric surface potential distribution, the electric wind velocity, and the mean thrust production are studied, and the dominative factors of airflow acceleration behavior are revealed. The results have shown that the actions of the SDBD actuator are mainly dependent on the geometry of the exposed electrode. Besides, the surface potential distribution can effectively affect the airflow acceleration behavior. With the application of an appropriate additional DC bias, the surface potential will be modified. As a result, the performance of the electric wind produced by a single SDBD can be significantly improved. In addition, the work also illustrates that the actuators with more negative surface potential present better mechanical performance.

  11. Improved zinc electrode and rechargeable zinc-air battery

    SciTech Connect

    Ross, P.N. Jr.

    1988-06-21

    The invention comprises an improved rechargeable zinc-air cell/battery having recirculating alkaline electrolyte and a zinc electrode comprising a porous foam support material which carries the active zinc electrode material. 5 figs.

  12. Surface stabilized electrodes for lithium batteries

    SciTech Connect

    Thackeray, Michael M.; Kang, Sun-Ho; Johnson, Christopher S.

    2015-09-08

    A stabilized electrode comprising a metal oxide or lithium-metal-oxide electrode material is formed by contacting a surface of the electrode material, prior to cell assembly, with an aqueous or a non-aqueous acid solution having a pH greater than 4 but less than 7 and containing a stabilizing salt, to etch the surface of the electrode material and introduce stabilizing anions and cations from the salt into said surface. The structure of the bulk of the electrode material remains unchanged during the acid treatment. The stabilizing salt comprises fluoride and at least one cationic material selected from the group consisting of ammonium, phosphorus, titanium, silicon, zirconium, aluminum, and boron.

  13. Electrocatalysts for bifunctional oxygen/air electrodes

    NASA Astrophysics Data System (ADS)

    Nikolova, V.; Iliev, P.; Petrov, K.; Vitanov, T.; Zhecheva, E.; Stoyanova, R.; Valov, I.; Stoychev, D.

    Oxygen reduction and evolution have been studied with respect to the development of bifunctional air/oxygen electrode (BFE). Three groups of catalysts have been prepared: (i) Cu xCo 3- xO 4 by thermal decomposition of mixed nitrate and carbonate precursors; (ii) thin films of Co-Ni-Te-O and Co-Te-O were deposited by vacuum co-evaporation of Co, Ni and TeO 2 and (iii) Co xO v/ZrO 2 films were obtained by electrochemical deposition. The electrochemical behavior of the chemically synthesized catalysts was studied on classical bilayered gas diffusion electrodes (GDEs), where the catalyst is in form of powder. The GDE catalyzed with vacuum deposited catalysts was prepared by direct deposition of the catalyst on gas-supplying layer, thus creating a ready-to-use gas diffusion electrode. Catalysts prepared electrochemically were first deposited on Ni foam and than pressed onto the gas-supplying layer. Different catalysts deposited on classical and originally designed GDEs were compared by their electrochemical performances. Cu 0.3Co 2.7O 4 deposited on a classical bilayered GDE with loading of 50 mg cm -2 exhibits stable current-voltage characteristics after 200 charge-discharge cycles in a real metal hydride-air battery. The electrochemically and vacuum deposited Co xO v/ZrO 2, Co-Ni-Te-O and Co-Te-O films exhibit much higher mass activity compared to Cu 0.2Co 2.8O 4 for both oxygen reduction and evolution reactions. The difference is that the loading of electrochemically and vacuum deposited films is 0.06 mg cm -2 only, which is a substantial advantage from a practical viewpoint.

  14. Surface protected lithium-metal-oxide electrodes

    DOEpatents

    Thackeray, Michael M.; Kang, Sun-Ho

    2016-04-05

    A lithium-metal-oxide positive electrode having a layered or spinel structure for a non-aqueous lithium electrochemical cell and battery is disclosed comprising electrode particles that are protected at the surface from undesirable effects, such as electrolyte oxidation, oxygen loss or dissolution by one or more lithium-metal-polyanionic compounds, such as a lithium-metal-phosphate or a lithium-metal-silicate material that can act as a solid electrolyte at or above the operating potential of the lithium-metal-oxide electrode. The surface protection significantly enhances the surface stability, rate capability and cycling stability of the lithium-metal-oxide electrodes, particularly when charged to high potentials.

  15. Method of making an air electrode material having controlled sinterability

    DOEpatents

    Vasilow, Theodore R.; Kuo, Lewis J. H.; Ruka, Roswell J.

    1994-01-01

    A tubular, porous ceramic electrode structure (3) is made from the sintered admixture of doped lanthanum manganite and an additive containing cerium where a solid electrolyte (4), substantially surrounds the air electrode, and a porous outer fuel electrode (7) substantially surrounds the electrolyte, to form a fuel cell (1).

  16. Method of making an air electrode material having controlled sinterability

    DOEpatents

    Vasilow, T.R.; Kuo, L.J.H.; Ruka, R.J.

    1994-08-30

    A tubular, porous ceramic electrode structure is made from the sintered admixture of doped lanthanum manganite and an additive containing cerium where a solid electrolyte, substantially surrounds the air electrode, and a porous outer fuel electrode substantially surrounds the electrolyte, to form a fuel cell. 2 figs.

  17. Bi-functional air electrodes for metal-air batteries. Final report, September 15, 1993--December 14, 1994

    SciTech Connect

    Swette, L.L.; Manoukian, M.; LaConti, A.B.

    1995-12-01

    The program was directed to the need for development of bifunctional air electrodes for Zn-Air batteries for the consumer market. The Zn-Air system, widely used as a primary cell for hearing-aid batteries and as a remote-site power source in industrial applications, has the advantage of high energy density, since it consumes oxygen from the ambient air utilizing a thin, efficient fuel-cell-type gas-diffusion electrode, and is comparatively low in cost. The disadvantages of the current technology are a relatively low rate capability, and the lack of simple reversibility. {open_quotes}Secondary{close_quotes} Zn-Air cells require a third electrode for oxygen evolution or mechanical replacement of the Zinc anodes; thus the development of a bifunctional air electrode (i.e., an electrode that can alternately consume and evolve oxygen) would be a significant advance in Zn-Air cell technology. Evaluations of two carbon-free non-noble metal perovskite-type catalyst systems, La{sub 1-x}CA{sub x}CoO{sub 3} as bifunctional catalysts for potential application in Zn-air batteries were carried out. The technical objectives were to develop higher-surface-area materials and to fabricate reversible electrodes by modifying the hydrophobic/hydrophilic balance of the catalyst-binder structures.

  18. Advanced Materials for Neural Surface Electrodes

    PubMed Central

    Schendel, Amelia A.; Eliceiri, Kevin W.; Williams, Justin C.

    2015-01-01

    Designing electrodes for neural interfacing applications requires deep consideration of a multitude of materials factors. These factors include, but are not limited to, the stiffness, biocompatibility, biostability, dielectric, and conductivity properties of the materials involved. The combination of materials properties chosen not only determines the ability of the device to perform its intended function, but also the extent to which the body reacts to the presence of the device after implantation. Advances in the field of materials science continue to yield new and improved materials with properties well-suited for neural applications. Although many of these materials have been well-established for non-biological applications, their use in medical devices is still relatively novel. The intention of this review is to outline new material advances for neural electrode arrays, in particular those that interface with the surface of the nervous tissue, as well as to propose future directions for neural surface electrode development. PMID:26392802

  19. Advanced Materials for Neural Surface Electrodes.

    PubMed

    Schendel, Amelia A; Eliceiri, Kevin W; Williams, Justin C

    2014-12-01

    Designing electrodes for neural interfacing applications requires deep consideration of a multitude of materials factors. These factors include, but are not limited to, the stiffness, biocompatibility, biostability, dielectric, and conductivity properties of the materials involved. The combination of materials properties chosen not only determines the ability of the device to perform its intended function, but also the extent to which the body reacts to the presence of the device after implantation. Advances in the field of materials science continue to yield new and improved materials with properties well-suited for neural applications. Although many of these materials have been well-established for non-biological applications, their use in medical devices is still relatively novel. The intention of this review is to outline new material advances for neural electrode arrays, in particular those that interface with the surface of the nervous tissue, as well as to propose future directions for neural surface electrode development.

  20. Influence of the morphology on the platinum electrode surface activity

    NASA Astrophysics Data System (ADS)

    Reiner, Andreas; Steiger, Beat; Scherer, Günther G.; Wokaun, Alexander

    Polycrystalline Pt electrodes with different surface characteristics were investigated by cyclic voltammetry (CV) in 0.5 M H 2SO 4. Plane electrodes showed a decrease in electrochemically active surface area while cycling in the hydrogen underpotential region (H upd), in contrast, electrodes roughened by intensive pre-cycling exhibited a stable value for the electrochemically active surface.

  1. 21 CFR 870.2370 - Electrocardiograph surface electrode tester.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Electrocardiograph surface electrode tester. 870.2370 Section 870.2370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... Electrocardiograph surface electrode tester. (a) Identification. An electrocardiograph surface electrode tester is...

  2. Experimental investigation of a thermionic converter with developed surface electrodes

    SciTech Connect

    Luke, J.R.; El-Genk, M.S.; Adrian, J.M.

    1997-01-01

    A thermionic converter with developed planar electrode surfaces is designed and tested. One of the electrodes has concentric circular grooves cut into its surface, while the other electrode surface is smooth. The grooves are 0.5 mm deep and 0.5 mm wide, having lands that are 1.0 mm wide. The experimental setup is flexible so that either the smooth or developed surface electrode can be operated as the emitter, with the other operating as the collector. The I-V characteristics and power output are compared for the two electrode arrangements. {copyright} {ital 1997 American Institute of Physics.}

  3. Effects of atmospheric air plasma treatment of graphite and carbon felt electrodes on the anodic current from Shewanella attached cells.

    PubMed

    Epifanio, Monica; Inguva, Saikumar; Kitching, Michael; Mosnier, Jean-Paul; Marsili, Enrico

    2015-12-01

    The attachment of electrochemically active microorganisms (EAM) on an electrode is determined by both the chemistry and topography of the electrode surface. Pre-treatment of the electrode surface by atmospheric air plasma introduces hydrophilic functional groups, thereby increasing cell attachment and electroactivity in short-term experiments. In this study, we use graphite and carbon felt electrodes to grow the model EAM Shewanella loihica PV-4 at oxidative potential (0.2 V vs. Ag/AgCl). Cell attachment and electroactivity are measured through electrodynamic methods. Atmospheric air plasma pre-treatment increases cell attachment and current output at graphite electrodes by 25%, while it improves the electroactivity of the carbon felt electrodes by 450%. Air plasma pre-treatment decreased the coulombic efficiency on both carbon felt and graphite electrodes by 60% and 80%, respectively. Microbially produced flavins adsorb preferentially at the graphite electrode, and air plasma pre-treatment results in lower flavin adsorption at both graphite and carbon felt electrodes. Results show that air plasma pre-treatment is a feasible option to increase current output in bioelectrochemical systems.

  4. Tensor veli palatini electromyography with surface electrode applied transnasally

    PubMed Central

    Picciotti, PM; Della Marca, G; Restuccia, D; Rigante, M; Di Nardo, W; Scarano, E

    2005-01-01

    Summary A new technique is proposed for paratubal electromyography, using a surface, non-invasive, electrode applied transnasally under nasopharyngoscope guidance. This electrode records activity of the tensor veli palatini muscle during swallowing. This technique is of interest for two reasons: endoscopic guid-ance offers the possibility to check correct positioning of the electrode recording at tensor veli palatini muscle level. Introduction of the non-invasive surface electrode is simple and not painful. PMID:16116836

  5. Performance and cycle life of carbon- and conductive-based air electrodes for rechargeable Zn-air battery applications

    NASA Astrophysics Data System (ADS)

    Chellapandi Velraj, Samgopiraj

    The development of high-performance, cyclically stable bifunctional air electrodes are critical to the commercial deployment of rechargeable Zn-air batteries. The carbon material predominantly used as support material in the air electrodes due to its higher surface area and good electrical conductivity suffers from corrosion at high oxygen evolution overpotentials. This study addresses the carbon corrosion issues and suggests alternate materials to replace the carbon as support in the air electrode. In this study, Sm0.5Sr0.5CoO3-delta with good electrochemical performance and cyclic lifetime was identified as an alternative catalyst material to the commonly used La0.4Ca 0.6CoO3 catalyst for the carbon-based bifunctional electrodes. Also, a comprehensive study on the effects of catalyst morphology, testing conditions on the cycle life as well as the relevant degradation mechanism for the carbon-based electrode was conducted in this dissertation. The cyclic life of the carbon-based electrodes was strongly dependent on the carbon support material, while the degradation mechanisms were entirely controlled by the catalyst particle size/morphology. Some testing conditions like resting time and electrolyte concentration did not change the cyclic life or degradation mechanism of the carbon-based electrode. The current density used for cyclic testing was found to dictate the degradation mechanism leading to the electrode failure. An alternate way to circumvent the carbon corrosion is to replace the carbon support with a suitable electrically-conductive ceramic material. In this dissertation, LaNi0.9Mn0.1O3, LaNi 0.8Co0.2O3, and NiCo2O4 were synthesized and evaluated as prospective support materials due to their good electrical conductivity and their ability to act as the catalyst needed for the bifunctional electrode. The carbon-free electrodes had remarkably higher catalytic activity for oxygen evolution reaction (OER) when compared to the carbon-based electrode. However

  6. Characterization of gas diffusion electrodes for metal-air batteries

    NASA Astrophysics Data System (ADS)

    Danner, Timo; Eswara, Santhana; Schulz, Volker P.; Latz, Arnulf

    2016-08-01

    Gas diffusion electrodes are commonly used in high energy density metal-air batteries for the supply of oxygen. Hydrophobic binder materials ensure the coexistence of gas and liquid phase in the pore network. The phase distribution has a strong influence on transport processes and electrochemical reactions. In this article we present 2D and 3D Rothman-Keller type multiphase Lattice-Boltzmann models which take into account the heterogeneous wetting behavior of gas diffusion electrodes. The simulations are performed on FIB-SEM 3D reconstructions of an Ag model electrode for predefined saturation of the pore space with the liquid phase. The resulting pressure-saturation characteristics and transport correlations are important input parameters for modeling approaches on the continuum scale and allow for an efficient development of improved gas diffusion electrodes.

  7. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, L.; Ruka, R.J.; Singhal, S.C.

    1999-08-03

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO{sub 3}. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell. 3 figs.

  8. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, Lewis; Ruka, Roswell J.; Singhal, Subhash C.

    1999-01-01

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell.

  9. Modulated Surface Vibrational Spectroscopies at Electrode/Electrolyte Interfaces.

    DTIC Science & Technology

    1984-11-28

    methanol, formaldehyde, or formic acid . Figure 8 gives examples of the spectra obtained from a poisoned electrode for the system platinum/formaldehyde...reflection losses at the atmosphere /window interface allowing more of the radiation to be utilized at the solution/electrode interface. More details on the... catalysis at electrode surfaces. * . ~ . . *~~ . . . . . . . . ’ . . . . .. . . . . . . . . .j

  10. Reversible air electrodes integrated with an anion-exchange membrane for secondary air batteries

    NASA Astrophysics Data System (ADS)

    Fujiwara, Naoko; Yao, Masaru; Siroma, Zyun; Senoh, Hiroshi; Ioroi, Tsutomu; Yasuda, Kazuaki

    Reversible air electrodes integrated with a polymer electrolyte membrane have been proposed for use in rechargeable metal-air batteries or unitized regenerative fuel cells to reduce the impact of atmospheric carbon dioxide. Reversible air electrodes were prepared with an anion-exchange membrane (AEM) as a polymer electrolyte membrane and platinum-based catalysts. The AEM at the interface between the alkaline electrolyte and the air electrode layer plays major roles in AEM-type air electrodes as follows: it blocks (a) the permeation of cations in the alkaline electrolyte into the air electrode layer to prevent carbonate precipitation, (b) penetration of the alkaline solution itself, and (c) neutralization of the alkaline electrolyte by carbon dioxide, all of which prevent performance degradation of oxygen reactions. Catalysts for decreasing the overvoltage of oxygen reactions were also investigated with the AEM-type air electrode, and the overall efficiency was improved due to a remarkable decrease in the potential for the oxygen evolution reaction with Pt-Ir catalysts.

  11. Cryogenic surface-electrode ion trap apparatus

    NASA Astrophysics Data System (ADS)

    Dubielzig, Timko; Carsjens, Martina; Kohnen, Matthias; Grondkowski, Sebastian; Ospelkaus, Christian

    2014-05-01

    In this talk we describe the infrastructure necessary to operate a surface-electrode ion trap with integrated microwave conductors for near-field quantum control of 9Be+ in a cryogenic environment. These traps are promising systems for analog quantum simulators and for quantum logic applications. Our group recently developed a trap with an integrated meander-like microwave guide for driving motional sidebands on an 9Be+ ion. The trap will be operated in a cryogenic vacuum chamber. We will discuss the vibrational isolated closed cycle cryostat and the design of the vacuum chamber with all electrical supplies necessary to apply two different microwave currents, dc voltages and three independent rf supplies to generate a reconfigurable rf trapping potential. We will also discuss the used hyperfine qubit and the laser systems required to cool and repump. Furthermore we will present the cryogenic, high aperture and fully acromatic imaging system.

  12. Assembly of Self-Cleaning Electrode Surface for the Development of Refreshable Biosensors.

    PubMed

    Zhu, Xiaoli; Chen, Yaoyao; Feng, Chang; Wang, Wei; Bo, Bing; Ren, Ruixin; Li, Genxi

    2017-04-04

    Passivation of electrode surface and tedious reconstruction of biosensing architectures have long plagued researchers for the development of electrochemical biosensors. Here, we report a novel self-cleaning electrode by modifying the commonly used working electrode with superhydrophobic and conductive nanocomposite. Owing to the superhydrophobicity and the chemical stability, the electrode avoids passivation result from both adsorption of molecules and oxidation in air. The high conductivity and the high effective area also allow the achievement of enhanced electrochemical signals. On the basis of comprehensive studies on this novel electrode, we have applied it in the fabrication of refreshable electrochemical biosensors for both electro-active and electro-inactive targets. For both cases, detection of the targets can be well performed, and the self-cleaning electrode can be refreshed by simply washing and applied for successive measurements in a long period.

  13. Air entrainment in hairy surfaces

    NASA Astrophysics Data System (ADS)

    Nasto, Alice; Regli, Marianne; Brun, P.-T.; Alvarado, José; Clanet, Christophe; Hosoi, A. E.

    2016-07-01

    Motivated by diving semiaquatic mammals, we investigate the mechanism of dynamic air entrainment in hairy surfaces submerged in liquid. Hairy surfaces are cast out of polydimethylsiloxane elastomer and plunged into a fluid bath at different velocities. Experimentally, we find that the amount of air entrained is greater than what is expected for smooth surfaces. Theoretically, we show that the hairy surface can be considered as a porous medium and we describe the air entrainment via a competition between the hydrostatic forcing and the viscous resistance in the pores. A phase diagram that includes data from our experiments and biological data from diving semiaquatic mammals is included to place the model system in a biological context and predict the regime for which the animal is protected by a plastron of air.

  14. Detecting Skin Burns Induced by Surface Electrodes

    DTIC Science & Technology

    2007-11-02

    density image were taken, the electrode peeled off the skin, and a photograph taken to complete the post-burn dataset. Finally, the used electrodes were...suggesting the breakdown of the barrier layer capacitance in the skin epidermis . Line monitoring of the skin impedance can predict the onset of the burns

  15. Confinement of reaction components at electrode surface

    DOEpatents

    Luca, Oana R.; Weitekamp, Raymond; Grubbs, Robert H.; Atwater, Harry A.; Mitrovic, Slobodan

    2017-03-14

    A CO.sub.2 reduction electrode includes an active layer on an electrode base. The active layer includes a polymer that includes one or more reaction components selected from a group consisting of a CO.sub.2 reduction catalyst and an activator that bonds CO.sub.2 so as to form a CO.sub.2 reduction intermediate.

  16. Bifunctional air electrodes containing elemental iron powder charging additive

    DOEpatents

    Liu, Chia-tsun; Demczyk, Brian G.; Gongaware, Paul R.

    1982-01-01

    A bifunctional air electrode for use in electrochemical energy cells is made, comprising a hydrophilic layer and a hydrophobic layer, where the hydrophilic layer essentially comprises a hydrophilic composite which includes: (i) carbon; (ii) elemental iron particles having a particle size of between about 25 microns and about 700 microns diameter; (iii) an oxygen evolution material; (iv) a nonwetting agent; and (v) a catalyst, where at least one current collector is formed into said composite.

  17. Electrode structures and surfaces for Li batteries

    DOEpatents

    Thackeray, Michael M.; Kang, Sun-Ho; Balasubramanian, Mahalingam; Croy, Jason

    2017-03-14

    This invention relates to methods of preparing positive electrode materials for electrochemical cells and batteries. It relates, in particular, to a method for fabricating lithium-metal-oxide electrode materials for lithium cells and batteries. The method comprises contacting a hydrogen-lithium-manganese-oxide material with one or more metal ions, preferably in an acidic solution, to insert the one or more metal ions into the hydrogen-lithium-manganese-oxide material; heat-treating the resulting product to form a powdered metal oxide composition; and forming an electrode from the powdered metal oxide composition.

  18. Novel air electrode for metal-air battery with new carbon material and method of making same

    DOEpatents

    Ross, P.N. Jr.

    1988-06-21

    This invention relates to a rechargeable battery or fuel cell. More particularly, this invention relates to a novel air electrode comprising a new carbon electrode support material and a method of making same. 3 figs.

  19. Surface modification of active material structures in battery electrodes

    DOEpatents

    Erickson, Michael; Tikhonov, Konstantin

    2016-02-02

    Provided herein are methods of processing electrode active material structures for use in electrochemical cells or, more specifically, methods of forming surface layers on these structures. The structures are combined with a liquid to form a mixture. The mixture includes a surface reagent that chemically reacts and forms a surface layer covalently bound to the structures. The surface reagent may be a part of the initial liquid or added to the mixture after the liquid is combined with the structures. In some embodiments, the mixture may be processed to form a powder containing the structures with the surface layer thereon. Alternatively, the mixture may be deposited onto a current collecting substrate and dried to form an electrode layer. Furthermore, the liquid may be an electrolyte containing the surface reagent and a salt. The liquid soaks the previously arranged electrodes in order to contact the structures with the surface reagent.

  20. Novel configuration of bifunctional air electrodes for rechargeable zinc-air batteries

    NASA Astrophysics Data System (ADS)

    Li, Po-Chieh; Chien, Yu-Ju; Hu, Chi-Chang

    2016-05-01

    A novel configuration of two electrodes containing electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) pressed into a bifunctional air electrode is designed for rechargeable Zn-air batteries. MOC/25BC carbon paper (MOC consisting of α-MnO2 and XC-72 carbon black) and Fe0.1Ni0.9Co2O4/Ti mesh on this air electrode mainly serve as the cathode for the ORR and the anode for the OER, respectively. The morphology and physicochemical properties of Fe0.1Ni0.9Co2O4 are investigated through scanning electron microscopy, inductively coupled plasma-mass spectrometry, and X-ray diffraction. Electrochemical studies comprise linear sweep voltammetry, rotating ring-disk electrode voltammetry, and the full-cell charge-discharge-cycling test. The discharge peak power density of the Zn-air battery with the unique air electrode reaches 88.8 mW cm-2 at 133.6 mA cm-2 and 0.66 V in an alkaline electrolyte under an ambient atmosphere. After 100 charge-discharge cycles at 10 mA cm-2, an increase of 0.3 V between charge and discharge cell voltages is observed. The deep charge-discharge curve (10 h in each step) indicates that the cell voltages of discharge (1.3 V) and charge (1.97 V) remain constant throughout the process. The performance of the proposed rechargeable Zn-air battery is superior to that of most other similar batteries reported in recent studies.

  1. High surface area electrode for high efficient microbial electrosynthesis

    NASA Astrophysics Data System (ADS)

    Nie, Huarong; Cui, Mengmeng; Lu, Haiyun; Zhang, Tian; Russell, Thomas; Lovley, Derek

    2012-02-01

    Microbial electrosynthesis, a process in which microorganisms directly accept electrons from an electrode to convert carbon dioxide and water into multi carbon organic compounds, affords a novel route for the generation of valuable products from electricity or even wastewater. The surface area of the electrode is critical for high production. A biocompatible, highly conductive, three-dimensional cathode was fabricated from a carbon nanotube textile composite to support the microorganism to produce acetate from carbon dioxide. The high surface area and macroscale porous structure of the intertwined CNT coated textile ?bers provides easy microbe access. The production of acetate using this cathode is 5 fold larger than that using a planar graphite electrode with the same volume. Nickel-nanowire-modified carbon electrodes, fabricated by microwave welding, increased the surface area greatly, were able to absorb more bacteria and showed a 1.5 fold increase in performance

  2. Gas diffusion-type oxygen electrode using perovskite-type oxides for metal-air batteries

    SciTech Connect

    Hyodo, Takeo; Miura, Norio; Yamazoe, Noboru

    1995-12-31

    In order to develop an air cathode of metal-air batteries, oxygen reduction behavior of gas diffusion-type carbon electrodes loaded with perovskite-type oxides, La{sub 1{minus}x}A{prime}{sub x}FeO{sub 3} (A{prime} = Ca, Sr, Ba, 0 {le} x {le} 1.0), was examined in 8 M KOH at 60 C. Among the oxide catalysts tested, La{sub 0.5}Sr{sub 0.5}FeO{sub 3} (specific surface area: 21.5 m{sup 2}{center_dot}g{sup {minus}1}) gave the highest electrode performance. On the basis of electrode reaction kinetics, H{sub 2}O{sub 2} decomposition rates, and temperature programmed desorption of oxygen, it was concluded that such a performance was attributable to the active sites of the oxide for the direct 4-electron reduction of oxygen. Moreover, the electrode using La{sub 0.5}Sr{sub 0.5}FeO{sub 3} was found to be rather stable in a short-term operation for 90 h at 300 mA{center_dot}cm{sup {minus}2}.

  3. Stability of carbon electrodes for aqueous lithium-air secondary batteries

    NASA Astrophysics Data System (ADS)

    Ohkuma, Hirokazu; Uechi, Ichiro; Matsui, Masaki; Takeda, Yasuo; Yamamoto, Osamu; Imanishi, Nobuyuki

    2014-01-01

    The air electrode performance of various carbon materials, such as Ketjen black (KB), acetylene black (AB and AB-S), Vulcan XC-72R (VX), and vapor grown carbon fiber (VGCF) with and without La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) catalyst were examined in an aqueous solution of saturated LiOH with 10 M LiCl in the current density range 0.2-2.0 mA cm-2. The best performance for oxygen reduction and evolution reactions was observed for the KB electrode, which has the highest surface area among the carbon materials examined. A steady over-potential of 0.2 V was obtained for the oxygen reduction reaction using the KB electrode without the catalyst, while the over-potential was 0.15 V for KB with the LSCF catalyst at 2.0 mA cm-2. The over-potentials for the oxygen evolution reaction were slightly higher than those for the oxygen reduction reaction, and gradually increased with the polarization period. Analysis of the gas in the cell after polarization above 0.4 V revealed the evolution of a small amount of CO during the oxygen evolution reaction by the decomposition of carbon in the electrode. The amount of CO evolved was significantly decreased by the addition of LSCF to the carbon electrode.

  4. In-Situ Surface EXAFS at Chemically Modified Electrodes.

    DTIC Science & Technology

    1987-07-28

    characterization of underpotentially deposited copper on gold(ll) electrodes. [12] We now present an in-situ surface EXAFS study of electropolymerized... deposition or adsorption of metallic adlayers (6] or transition metal complexes. [7] In addition the electrode can act as a simple electron shuttle to...structure at all stages of polymer deposition . These values correlate very well with the known coordination member of six and a Ru-N distance of 2.056 A

  5. Silicon surface-electrode ion traps for quantum information processing

    NASA Astrophysics Data System (ADS)

    Doret, S. Charles; Slusher, Richart

    2010-03-01

    The Georgia Tech Research Institute (GTRI) is designing, building, and testing scalable surface-electrode ion traps for quantum information applications, fabricated using silicon VLSI technology. A wide range of trap architectures have been developed, including a linear trap capable of holding long chains of equally spaced ions, a 90-degree X-junction, and an integrated micromirror with collection efficiency approaching 20%. Fabrication features that can be integrated with the surface electrodes include multilayer interconnects, optics for enhanced light collection, flexible optical access through beveled slots extending through the substrate, and recessed wire bonds for clear laser access across the trap surface. Traps are designed at GTRI using in-house codes that calculate trap fields, compute the full motion of ions confined in the trap, including micromotion, and optimize electrode shapes and transport waveforms using genetic algorithms. We will present designs and initial test results for several of these traps, as well as plans for their use in future experiments.

  6. Chemical and morphological characteristics of lithium electrode surfaces

    NASA Technical Reports Server (NTRS)

    Yen, S. P. S.; Shen, D.; Vasquez, R. P.; Grunthaner, F. J.; Somoano, R. B.

    1981-01-01

    Lithium electrode surfaces were analyzed for chemical and morphological characteristics, using electron spectroscopy chemical analysis (ESCA) and scanning electron microscopy (SEM). Samples included lithium metal and lithium electrodes which were cycled in a 1.5 M lithium arsenic hexafluoride/two-methyl tetrahydrofuran electrolyte. Results show that the surface of the as-received lithium metal was already covered by a film composed of LiO2 and an Li2O/CO2 adduct with a thickness of approximately 100-200 A. No evidence of Ni3 was found. Upon exposure of the lithium electrode to a 1.5 M LiAsF6/2-Me-THF electrochemical environment, a second film was observed to form on the surface, consisting primarily of As, Si, and F, possibly in the form of lithium arsenic oxyfluorides or lithium fluorosilicates. It is suggested that the film formation may be attributed to salt degradation.

  7. Carbon-based air electrodes carrying MnO 2 in zinc-air batteries

    NASA Astrophysics Data System (ADS)

    Wei, Zidong; Huang, Wenzhang; Zhang, Shengtao; Tan, Jun

    Catalysts prepared from the carbon black impregnated with manganous nitrate solution and then heated at temperature from 270°C to 450°C were investigated. It was found that the impregnated catalysts heated at temperature of 340°C exhibited the best catalytic activity for oxygen reduction in alkaline electrolyte. It was also found that the XRD spectra of pyrolytic MnO 2 from manganous nitrate over 340°C were different from those below 340°C. The enhanced catalysis of air electrodes was ascribed to the formation of MnO 2 crystal with d-value of 2.72 Å as the impregnated-catalysts was heated at temperature of 340°C. The other factors in preparation of air electrodes were also discussed.

  8. Surface analysis of new chlorpromazinium plastic membrane electrodes.

    PubMed

    Al-Shatti, L A; Marafie, H M; Shoukry, A F

    2008-01-22

    New chlorpromazinium (Cp) plastic membrane electrodes of the conventional type were constructed and characterized. They are based on incorporation of Cp-reineckate (CpRn) ion pair, Cp-phosphotungstate (Cp3PT), or Cp-phosphomolybdate (Cp3PM) ion associate into poly(vinyl chloride) membrane. The electrodes exhibited calibration graph slopes of 49.83, 52.87, and 61.30 mV/Cp concentration decade over life spans of 1, 5, and 3 days, respectively. All electrodes proved to be selective for Cp and have been applied to the assay of a pharmaceutical preparation. Energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), as well as scanning electron microscopy (SEM) showed that the limitation of the lifetime of the electrodes is attributed to leaching of the ion exchanger from the membrane into the test solution in addition to deformation of the surface.

  9. An improved bifunctional oxygen (air) electrode for reversible alkaline fuel cell systems and for rechargeable metal-air batteries

    NASA Astrophysics Data System (ADS)

    Kordesch, K.; Steininger, K.-H.; Tomantschger, K.

    1988-10-01

    Electrodes with a nickel layer of dual pore structure on the electrolyte side and a PTFE-bonded carbon layer on the oxygen (air) side are discussed, with application to space energy storage. During the electrolyis stage, the oxygen fills the large pores of the porous Ni structure with gas. During the discharge cycle, the iron/air or zinc/air cell of the carbon layer operates as a regular oxygen electrode.

  10. Modified carbon surfaces as "organic electrodes" that exhibit conductance switching.

    PubMed

    Solak, Ali Osman; Eichorst, Laura R; Clark, William J; McCreery, Richard L

    2003-01-15

    Glassy carbon (GC) surfaces modified with monolayers of biphenyl and nitrobiphenyl molecules were examined as voltammetric electrodes for ferrocene, benzoquinone, and tetracyanoquinodimethane electrochemistry in acetonitrile. The modified electrodes exhibited slower electron transfer than unmodified GC, by factors that varied with the monolayer and redox system. However, after a negative potential excursion to approximately -2.0 V versus Ag+/Ag, the modified electrodes exhibited much faster electron-transfer kinetics, approaching those observed on unmodified GC. The effect is attributed to an apparently irreversible structural change in the biphenyl or nitrobiphenyl monolayer, which increases the rate of electron tunneling. The transition to the "ON" state is associated with electron injection into the monolayer similar to that observed in previous spectroscopic investigations and causes a significant decrease in the calculated HOMO-LUMO gap for the monolayer molecule. Once the monolayer is switched ON, it supports rapid electron exchange with outer-sphere redox systems, but not with dopamine, which requires adsorption to the GC surface. The increase in electron-transfer rate with electron injection is consistent with an increase in electron tunneling rate through the monolayer, caused by a significant decrease in tunneling barrier height. The ON electrode can reduce biphenyl- or nitrobiphenyldiazonium reagent in solution to permit formation of a second modification layer of biphenyl or nitrobiphenyl molecules. This "double derivatization" procedure was used to prepare tetraphenyl- and nitrotetraphenyl-modified electrodes, which exhibit significantly slower electron transfer than their biphenyl and nitrobiphenyl counterparts. A "switching" electrode may have useful properties for electroanalytical applications and possibly in electrocatalysis. In addition, the ON state represents an "organic electrode" in which electron transfer occurs at an interface between an

  11. Application of surface enhanced Raman spectroscopy to the study of SOFC electrode surfaces.

    PubMed

    Li, Xiaxi; Blinn, Kevin; Fang, Yingcui; Liu, Mingfei; Mahmoud, Mahmoud A; Cheng, Shuang; Bottomley, Lawrence A; El-Sayed, Mostafa; Liu, Meilin

    2012-05-07

    SERS provided by sputtered silver was employed to detect trace amounts of chemical species on SOFC electrodes. Considerable enhancement of Raman signal and lowered detection threshold were shown for coked nickel surfaces, CeO(2) coatings, and cathode materials (LSM and LSCF), suggesting a viable approach to probing electrode degradation and surface catalytic mechanism.

  12. Heating rate and electrode charging measurements in a scalable, microfabricated, surface-electrode ion trap

    NASA Astrophysics Data System (ADS)

    Allcock, D. T. C.; Harty, T. P.; Janacek, H. A.; Linke, N. M.; Ballance, C. J.; Steane, A. M.; Lucas, D. M.; Jarecki, R. L.; Habermehl, S. D.; Blain, M. G.; Stick, D.; Moehring, D. L.

    2012-06-01

    We characterise the performance of a surface-electrode ion "chip" trap fabricated using established semiconductor integrated circuit and micro-electro-mechanical-system (MEMS) microfabrication processes, which are in principle scalable to much larger ion trap arrays, as proposed for implementing ion trap quantum information processing. We measure rf ion micromotion parallel and perpendicular to the plane of the trap electrodes, and find that on-package capacitors reduce this to ≲10 nm in amplitude. We also measure ion trapping lifetime, charging effects due to laser light incident on the trap electrodes, and the heating rate for a single trapped ion. The performance of this trap is found to be comparable with others of the same size scale.

  13. New tetradecyltrimethylammonium-selective electrodes: surface composition and topography as correlated with electrode's life span.

    PubMed

    Marafie, Hayat M; Al-Shammari, Tahani F; Shoukry, Adel F

    2012-03-15

    Two conventional plastic membrane electrodes that are selective for the tetradecyltrimethylammonium cation (TTA) have been prepared. The ion exchangers of these sensors were the ion associate, TTA-PT, and the ion aggregate, TTA-PSS, where PT and PSS are phosphotungstate and polystyrene sulfonate, respectively. The following performance characteristics of the TTA-PT- and TTA-PSS-containing electrodes were found: conditioning time of 30 and 20 min; potential response of 58.2 and 61.1 mV/TTA concentration decade; rectilinear concentration ranges of 2.0 × 10(-5)-5.0 × 10(-2) and 1.5 × 10(-5)-7.9 × 10(-2) mol L(-1); average working pH ranges of 4.0-10.5 and 3.8-10.7; life spans of 20 and 28 weeks, and isothermal temperature coefficients of 4.44 × 10(-4) and 6.10 × 10(-4)V/°C, respectively. Both electrodes exhibited high selectivity for TTA with an increasing number of inorganic and quaternary ammonium surfactant cations. These electrodes have been successfully applied to assay an antiseptic formulation containing TTA. Surface analyses using electron microscopy and X-ray photoelectron spectroscopy were used to determine the cause of the limited life span of plastic membrane electrodes.

  14. Probing and mapping electrode surfaces in solid oxide fuel cells.

    PubMed

    Blinn, Kevin S; Li, Xiaxi; Liu, Mingfei; Bottomley, Lawrence A; Liu, Meilin

    2012-09-20

    Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen (1-7). The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion(2). Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation(8-12). It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition(8, 10, 13, 14) ("coking") and sulfur poisoning(11, 15) and the manner in which surface modifications stave off this degradation(16). The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM

  15. Surface Analysis of 4-Aminothiophenol Adsorption at Polycrystalline Platinum Electrodes

    NASA Technical Reports Server (NTRS)

    Rosario-Castro, Belinda I.; Fachini, Estevao R.; Contes, Enid J.; Perez-Davis, Marla E.; Cabrera, Carlos R.

    2008-01-01

    Formation of self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) on polycrystalline platinum electrodes has been studied by surface analysis and electrochemistry techniques. The 4-ATP monolayer was characterized by cyclic voltammetry (CV), Raman spectroscopy, reflection absorption infrared (RAIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) experiments give an idea about the packing quality of the monolayer. RAIR and Raman spectra for 4-ATP modified platinum electrodes showed the characteristic adsorption bands for neat 4-ATP indicating the adsorption of 4-ATP molecules on platinum surface. The adsorption on platinum was also evidenced by the presence of sulfur and nitrogen peaks by XPS survey spectra of the modified platinum electrodes. High resolution XPS studies and RAIR spectrum for platinum electrodes modified with 4-ATP indicate that molecules are sulfur-bonded to the platinum surface. The formation of S-Pt bond suggests that ATP adsorption gives up an amino terminated SAM. Thickness of the monolayer was evaluated via angle-resolved XPS (AR-XPS) analyses. Derivatization of 4-ATP SAM was performed using 16-Br hexadecanoic acid.

  16. Investigation of Lithium-Air Battery Discharge Product Formed on Carbon Nanotube and Nanofiber Electrodes

    NASA Astrophysics Data System (ADS)

    Mitchell, Robert Revell, III

    Carbon nanotubes have been actively investigated for integration in a wide variety of applications since their discovery over 20 years ago. Their myriad desirable material properties including exceptional mechanical strength, high thermal conductivities, large surface-to-volume ratios, and considerable electrical conductivities, which are attributable to a quantum mechanical ability to conduct electrons ballistically, have continued to motivate interest in this material system. While a variety of synthesis techniques exist, carbon nanotubes and nanofibers are most often conveniently synthesized using chemical vapor deposition (CVD), which involves their catalyzed growth from transition metal nanoparticles. Vertically-aligned nanotube and nanofiber carpets produced using CVD have been utilized in a variety of applications including those related to energy storage. Li-air (Li-O2) batteries have received much interest recently because of their very high theoretical energy densities (3200 Wh/kgLi2O2 ). which make them ideal candidates for energy storage devices for future fully-electric vehicles. During operation of a Li-air battery O2 is reduced on the surface a porous air cathode, reacting with Li-ions to form lithium peroxide (Li-O2). Unlike the intercalation reactions of Li-ion batteries, discharge in a Li-air cell is analogous to an electrodeposition process involving the nucleation and growth of the depositing species on a foreign substrate. Carbon nanofiber electrodes were synthesized on porous substrates using a chemical vapor deposition process and then assembled into Li-O2 cells. The large surface to volume ratio and low density of carbon nanofiber electrodes were found to yield a very high gravimetric energy density in Li-O 2 cells, approaching 75% of the theoretical energy density for Li 2O2. Further, the carbon nanofiber electrodes were found to be excellent platforms for conducting ex situ electron microscopy investigations of the deposition Li2O2 phase

  17. Surface Temperature variability from AIRS.

    NASA Astrophysics Data System (ADS)

    Ruzmaikin, A.; Dang, V. T.; Aumann, H. H.

    2015-12-01

    To address the existence and possible causes of the climate hiatus in the Earth's global temperature we investigate the trends and variability in the surface temperature using retrievals obtained from the measurements by the Atmospheric Infrared Sounder (AIRS) and its companion instrument, the Advanced Microwave Sounding Unit (AMSU), onboard of Aqua spacecraft in 2002-2014for the day and night conditions. The data used are L3 monthly means on a 1x1degree spatial grid. We separate the land and ocean temperatures, as well as temperatures in Artic, Antarctic and desert regions. We compare the satellite data with the new surface data produced by Karl et al. (2015) who denies the reality of the climate hiatus. The difference in the regional trends can help to explain why the global surface temperature remains almost unchanged but the frequency of occurrence of the extreme events increases under rising anthropogenic forcing. The day-night difference is an indicator of the anthropogenic trend. This work was supported by the Jet Propulsion Laboratory of the California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  18. Hot-rolling nanowire transparent electrodes for surface roughness minimization.

    PubMed

    Hosseinzadeh Khaligh, Hadi; Goldthorpe, Irene A

    2014-01-01

    Silver nanowire transparent electrodes are a promising alternative to transparent conductive oxides. However, their surface roughness presents a problem for their integration into devices with thin layers such as organic electronic devices. In this paper, hot rollers are used to soften plastic substrates with heat and mechanically press the nanowires into the substrate surface. By doing so, the root-mean-square surface roughness is reduced to 7 nm and the maximum peak-to-valley value is 30 nm, making the electrodes suitable for typical organic devices. This simple process requires no additional materials, which results in a higher transparency, and is compatible with roll-to-roll fabrication processes. In addition, the adhesion of the nanowires to the substrate significantly increases.

  19. Long-range surface plasmons in electrode structures

    NASA Technical Reports Server (NTRS)

    Stegeman, G. I.; Burke, J. J.

    1983-01-01

    Surface polaritons guided by symmetric double metal film structures are analyzed, with particular attention given to the attenuation of the two long-range modes that occur. It is found that long-range surface plasmon polariton modes do exist for double electrode structures over a limited range of material parameters. Guided by thin metal electrodes, surface plasmon polaritons can achieve millimeter plus propagation distances in the near infrared. It is pointed out that if the slab is electrooptic, then very low voltages will be needed to manipulate the waves. The fact that long-range modes exist simultaneously with junction tunnel plasmons may be of use in providing directional radiation from light-emitting junctions or the inverse process of light to electrical energy conversion.

  20. High surface area, low weight composite nickel fiber electrodes

    NASA Technical Reports Server (NTRS)

    Johnson, Bradley A.; Ferro, Richard E.; Swain, Greg M.; Tatarchuk, Bruce J.

    1993-01-01

    The energy density and power density of light weight aerospace batteries utilizing the nickel oxide electrode are often limited by the microstructures of both the collector and the resulting active deposit in/on the collector. Heretofore, these two microstructures were intimately linked to one another by the materials used to prepare the collector grid as well as the methods and conditions used to deposit the active material. Significant weight and performance advantages were demonstrated by Britton and Reid at NASA-LeRC using FIBREX nickel mats of ca. 28-32 microns diameter. Work in our laboratory investigated the potential performance advantages offered by nickel fiber composite electrodes containing a mixture of fibers as small as 2 microns diameter (Available from Memtec America Corporation). These electrode collectors possess in excess of an order of magnitude more surface area per gram of collector than FIBREX nickel. The increase in surface area of the collector roughly translates into an order of magnitude thinner layer of active material. Performance data and advantages of these thin layer structures are presented. Attributes and limitations of their electrode microstructure to independently control void volume, pore structure of the Ni(OH)2 deposition, and resulting electrical properties are discussed.

  1. Novel air electrode for metal-air battery with new carbon material and method of making same

    DOEpatents

    Ross, Jr., Philip N.

    1990-01-01

    A novel carbonaceous electrode support material is disclosed characterized by a corrosion rate of 0.03 wt. %/hour or less when measured a5 550 millivolts vs. a Hg/HgO electrode in a 30 wt. % KOH electrolyte a5 30.degree. C. The electrode support material comprises a preselected carbon black material which has been heat-treated by heating the material to a temperature of from about 2500.degree. to about 3000.degree. C. over a period of from about 1 to about 5 hours in an inert atmosphere and then maintaining the preselected carbon black material at this temperature for a period of at least about 1 hour, and preferably about 2 hours, in the inert atmosphere. A carbonaceous electrode suitable for use as an air electrode in a metal-air cell may be made from the electrode support material by shaping and forming it into a catalyst support and then impregnating it with a catalytically active material capable of catalyzing the reaction with oxygen at the air electrode of metal-air cell.

  2. Multiple surface DBD electrode system for efficient and controlled generation of ozone

    NASA Astrophysics Data System (ADS)

    Prukner, Vaclav; Hoffer, Petr; Simek, Milan

    2016-09-01

    Electrical characteristics and ozone production measurements were performed to evaluate the efficiency of ozone generation using an amplitude-modulated AC Surface Dielectric Barrier Discharge (SDBD) in dry synthetic air and pure oxygen at atmospheric pressure. To increase the concentration and production of ozone we used the multiple SDBD electrode system consisting of several identical elements in parallel configuration. Each SDBD element is made of a thin alumina plate (10cm x 10 cm x 0,065cm) with metallic strips deposited on the upper side as a HV electrode and full square or strips on the opposite side as a ground electrode. An influence of a photocatalyst on ozone production was studied as well by inserting thin alumina plates coated with titanium dioxide thin films between SDBD electrodes. Alternatively, the SDBD electrodes directly coated with titanium dioxide were tested either. Dependence of ozone production on the discharge duty cycle and gas flow rate of 0,8 slm - 10 slm were evaluated. Work supported by TACR (Contract No. TA03010098).

  3. Influence of surface oxidation on ion dynamics and capacitance in porous and nonporous carbon electrodes

    DOE PAGES

    Dyatkin, Boris; Zhang, Yu; Mamontov, Eugene; ...

    2016-04-07

    Here, we investigate the influence of surface chemistry and ion confinement on capacitance and electrosorption dynamics of room-temperature ionic liquids (RTILs) in supercapacitors. Using air oxidation and vacuum annealing, we produced defunctionalized and oxygen-rich surfaces of carbide-derived carbons (CDCs) and graphene nanoplatelets (GNPs). While oxidized surfaces of porous CDCs improve capacitance and rate handling abilities of ions, defunctionalized nonporous GNPs improve charge storage densities on planar electrodes. Quasi-elastic neutron scattering (QENS) and inelastic neutron scattering (INS) probed the structure, dynamics, and orientation of RTIL ions confined in divergently functionalized pores. Oxidized, ionophilic surfaces draw ions closer to pore surfaces andmore » enhance potential-driven ion transport during electrosorption. Molecular dynamics (MD) simulations corroborated experimental data and demonstrated the significance of surface functional groups on ion orientations, accumulation densities, and capacitance.« less

  4. Influence of surface oxidation on ion dynamics and capacitance in porous and nonporous carbon electrodes

    SciTech Connect

    Dyatkin, Boris; Zhang, Yu; Mamontov, Eugene; Kolesnikov, Alexander I.; Cheng, Yongqiang; Meyer, III, Harry M.; Cummings, Peter T.; Gogotsi, Yury G.

    2016-04-07

    Here, we investigate the influence of surface chemistry and ion confinement on capacitance and electrosorption dynamics of room-temperature ionic liquids (RTILs) in supercapacitors. Using air oxidation and vacuum annealing, we produced defunctionalized and oxygen-rich surfaces of carbide-derived carbons (CDCs) and graphene nanoplatelets (GNPs). While oxidized surfaces of porous CDCs improve capacitance and rate handling abilities of ions, defunctionalized nonporous GNPs improve charge storage densities on planar electrodes. Quasi-elastic neutron scattering (QENS) and inelastic neutron scattering (INS) probed the structure, dynamics, and orientation of RTIL ions confined in divergently functionalized pores. Oxidized, ionophilic surfaces draw ions closer to pore surfaces and enhance potential-driven ion transport during electrosorption. Molecular dynamics (MD) simulations corroborated experimental data and demonstrated the significance of surface functional groups on ion orientations, accumulation densities, and capacitance.

  5. Gradient porous electrode architectures for rechargeable metal-air batteries

    DOEpatents

    Dudney, Nancy J.; Klett, James W.; Nanda, Jagjit; Narula, Chaitanya Kumar; Pannala, Sreekanth

    2016-03-22

    A cathode for a metal air battery includes a cathode structure having pores. The cathode structure has a metal side and an air side. The porosity decreases from the air side to the metal side. A metal air battery and a method of making a cathode for a metal air battery are also disclosed.

  6. Nanoscale Decoration of Electrode Surfaces with an STM

    DTIC Science & Technology

    1999-05-30

    covered Au( 111) surface due to underpotential deposition . E,,,P, = + 10 mV vs. Cu/Cu++, E, = - 30 mV, I, = 2 nA. (b) Same area, but after anodic...Abstract The tip of a scanning tunnelling microscope (STM) has been used to deposit nanometer-sized clusters of copper or silver on bare and thiol...covered gold electrode surfaces at predetermined positions. First, metal is deposited electrochemically onto the STM tip, then the clusters are formed by a

  7. Stability in alkaline aqueous electrolyte of air electrode protected with fluorinated interpenetrating polymer network membrane

    NASA Astrophysics Data System (ADS)

    Bertolotti, Bruno; Messaoudi, Houssam; Chikh, Linda; Vancaeyzeele, Cédric; Alfonsi, Séverine; Fichet, Odile

    2015-01-01

    We developed original anion exchange membranes to protect air electrodes operating in aqueous lithium-air battery configuration, i.e. supplied with atmospheric air and in concentrated aqueous lithium hydroxide. These protective membranes have an interpenetrating polymer network (IPN) architecture combining a hydrogenated cationic polyelectrolyte network based on poly(epichlorohydrin) (PECH) and a fluorinated neutral network based on perfluoropolyether (Fluorolink® MD700). Two phases, each one rich in one of the polymer, are co-continuous in the materials. This morphology allows combining their properties according to the weight proportions of each polymer. Thus, PECH/Fluorolink IPNs show ionic conductivity varying from 1 to 2 mS cm-1, water uptake from 30 to 90 wt.% and anionic transport number from 0.65 to 0.80 when the PECH proportion varies from 40 to 90 wt.%. These membranes have been systematically assembled on air electrodes. Air electrode protected with PECH/Fluorolink 70/30 IPN shows outstanding stability higher than 1000 h, i.e. a 20-fold increase in the lifetime of the non-modified electrode. This efficient membrane/air electrode assembly is promising for development of alkaline electrolyte based storage or production energy systems, such as metal air batteries or alkaline fuel cells.

  8. Equivalent ambipolar carrier injection of electrons and holes with Au electrodes in air-stable field effect transistors

    SciTech Connect

    Kanagasekaran, Thangavel E-mail: Shimotani@m.tohoku.ac.jp Ikeda, Susumu; Kumashiro, Ryotaro; Shimotani, Hidekazu E-mail: Shimotani@m.tohoku.ac.jp Shang, Hui; Tanigaki, Katsumi E-mail: Shimotani@m.tohoku.ac.jp

    2015-07-27

    Carrier injection from Au electrodes to organic thin-film active layers can be greatly improved for both electrons and holes by nano-structural surface control of organic semiconducting thin films using long-chain aliphatic molecules on a SiO{sub 2} gate insulator. In this paper, we demonstrate a stark contrast for a 2,5-bis(4-biphenylyl)bithiophene (BP2T) active semiconducting layer grown on a modified SiO{sub 2} dielectric gate insulator between two different modifications of tetratetracontane and poly(methyl methacrylate) thin films. Important evidence that the field effect transistor (FET) characteristics are independent of electrode metals with different work functions is given by the observation of a conversion of the metal-semiconductor contact from the Schottky limit to the Bardeen limit. An air-stable light emitting FET with an Au electrode is demonstrated.

  9. Electrode electrolyte interlayers containing cerium oxide for electrochemical fuel cells

    DOEpatents

    Borglum, Brian P.; Bessette, Norman F.

    2000-01-01

    An electrochemical cell is made having a porous fuel electrode (16) and a porous air electrode (13), with solid oxide electrolyte (15) therebetween, where the air electrode surface opposing the electrolyte has a separate, attached, dense, continuous layer (14) of a material containing cerium oxide, and where electrolyte (16) contacts the continuous oxide layer (14), without contacting the air electrode (13).

  10. Microfabrication of Surface Electrode Ion Traps for Quantum Information Experiments

    NASA Astrophysics Data System (ADS)

    Ge, Yufei; Labaziewicz, Jaroslaw; Antohi, Paul; Chuang, Isaac

    2008-03-01

    Surface electrode ion traps, while promising for large-scale quantum computation, have long been challenged by ion heating rates which increase rapidly as trap length scales are reduced. Through a series of measurements on over fifteen traps, we show that ion heating rates are surprisingly sensitive to electrode material and morphology, and in particular, to details of the fabrication procedure. For example, one 75 μm size trap, made of chemically etched silver on a single crystal quartz substrate, showed a minimum heating rate of ˜40 quanta/second, when prepared by annealing at 760^oC in vacuum for one hour. This annealing smooths sharp edges, and significantly reduces breakdown voltage. However, if the annealing temperature is lowered to 720^oC, leaving the breakdown voltage still robustly high, the heating rate jumps to ˜1000 quanta/second. With electroplated gold, on a silver seed layer, a record low heating rate of ˜2 quanta/second is obtained. We present details of the fabrication procedures, evaluate alternative electrode materials such as niobium nitride, and explain how these measurements were obtained with an ion trap operated at 6 Kelvin, containing a single strontium ion, sideband cooled to its quantum ground state of motion.

  11. Influence of Structure and Surface Chemistry of Porous Carbon Electrodes on Supercapacitor Performance

    NASA Astrophysics Data System (ADS)

    Dyatkin, Boris

    Electrochemical double layer capacitors, which rely on electrosorption of ions in nanostructured carbon electrodes, can supplement or even replace traditional batteries in energy harvesting and storage applications. While supercapacitors offer > 10 kW/kg power densities, their ~5 Wh/kg energy densities are insufficient for many automotive and grid storage applications. Most prior efforts have focused on novel high-performing ionic liquid electrolytes and porous carbons with tunable pore diameters and high specific surface areas. However, existing research lacks fundamental understanding of the influence of surface heterogeneity and disorder, such as graphitic defects and functional groups, on key electrosorption properties at electrode-electrolyte interfaces. These interactions significantly impact charge accumulation densities, ion transport mechanisms, and electrolyte breakdown processes. Subsequently, they must be investigated to optimize ion screening, charge mobilities, and operating voltage windows of the devices. The research in this dissertation examined the influence of surface functional groups and structural ordering on capacitance, electrosorption dynamics, and electrochemical stability of external and internal surface of carbon electrodes. High-temperature vacuum annealing, air oxidation, hydrogenation, and amination were used to tune pore surface compositions and decouple key structural and chemical properties of carbide-derived carbons. The approach combined materials characterization by a variety of techniques, neutron scattering studies of ion dynamics, electrochemical testing, and MD simulations to investigate the fundamental intermolecular interactions and dynamics of ions electrosorption in different pore architectures and on planar graphene surfaces. Contrary to expected results and existing theories, defect removal via defunctionalization and graphitization decreased capacitance. Hydrogenated surfaces benefitted electrosorption, while oxygen

  12. Multifunctional Indium Tin Oxide Electrode Generated by Unusual Surface Modification

    NASA Astrophysics Data System (ADS)

    Bouden, Sarra; Dahi, Antoine; Hauquier, Fanny; Randriamahazaka, Hyacinthe; Ghilane, Jalal

    2016-11-01

    The indium tin oxide (ITO) material has been widely used in various scientific fields and has been successfully implemented in several devices. Herein, the electrochemical reduction of ITO electrode in an organic electrolytic solution containing alkali metal, NaI, or redox molecule, N-(ferrocenylmethyl) imidazolium iodide, was investigated. The reduced ITO surfaces were investigated by X-ray photoelectron spectroscopy and grazing incident XRD demonstrating the presence of the electrolyte cation inside the material. Reversibility of this process after re-oxidation was evidenced by XPS. Using a redox molecule based ionic liquid as supporting electrolyte leads to fellow electrochemically the intercalation process. As a result, modified ITO containing ferrocenyl imidazolium was easily generated. This reduction process occurs at mild reducing potential around ‑1.8 V and causes for higher reducing potential a drastic morphological change accompanied with a decrease of the electrode conductivity at the macroscopic scale. Finally, the self-reducing power of the reduced ITO phase was used to initiate the spontaneous reduction of silver ions leading to the growth of Ag nanoparticles. As a result, transparent and multifunctional active ITO surfaces were generated bearing redox active molecules inside the material and Ag nanoparticles onto the surface.

  13. Multifunctional Indium Tin Oxide Electrode Generated by Unusual Surface Modification

    PubMed Central

    Bouden, Sarra; Dahi, Antoine; Hauquier, Fanny; Randriamahazaka, Hyacinthe; Ghilane, Jalal

    2016-01-01

    The indium tin oxide (ITO) material has been widely used in various scientific fields and has been successfully implemented in several devices. Herein, the electrochemical reduction of ITO electrode in an organic electrolytic solution containing alkali metal, NaI, or redox molecule, N-(ferrocenylmethyl) imidazolium iodide, was investigated. The reduced ITO surfaces were investigated by X-ray photoelectron spectroscopy and grazing incident XRD demonstrating the presence of the electrolyte cation inside the material. Reversibility of this process after re-oxidation was evidenced by XPS. Using a redox molecule based ionic liquid as supporting electrolyte leads to fellow electrochemically the intercalation process. As a result, modified ITO containing ferrocenyl imidazolium was easily generated. This reduction process occurs at mild reducing potential around −1.8 V and causes for higher reducing potential a drastic morphological change accompanied with a decrease of the electrode conductivity at the macroscopic scale. Finally, the self-reducing power of the reduced ITO phase was used to initiate the spontaneous reduction of silver ions leading to the growth of Ag nanoparticles. As a result, transparent and multifunctional active ITO surfaces were generated bearing redox active molecules inside the material and Ag nanoparticles onto the surface. PMID:27857192

  14. Lanthanum manganite-based air electrode for solid oxide fuel cells

    DOEpatents

    Ruka, R.J.; Kuo, L.; Li, B.

    1999-06-29

    An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO[sub 3]. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La[sub w]Ca[sub x]Ln[sub y]Ce[sub z]MnO[sub 3], wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics. 10 figs.

  15. Lanthanum manganite-based air electrode for solid oxide fuel cells

    DOEpatents

    Ruka, Roswell J.; Kuo, Lewis; Li, Baozhen

    1999-01-01

    An air electrode material for a solid oxide fuel cell is disclosed. The electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode material preferably comprises La, Ca, Ce and at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd. The B-site of the electrode material comprises Mn with substantially no dopants. The ratio of A:B is preferably slightly above 1. A preferred air electrode composition is of the formula La.sub.w Ca.sub.x Ln.sub.y Ce.sub.z MnO.sub.3, wherein Ln comprises at least one lanthanide selected from Sm, Gd, Dy, Er, Y and Nd, w is from about 0.55 to about 0.56, x is from about 0.255 to about 0.265, y is from about 0.175 to about 0.185, and z is from about 0.005 to about 0.02. The air electrode material possesses advantageous chemical and electrical properties as well as favorable thermal expansion and thermal cycle shrinkage characteristics.

  16. Surface modifications of electrode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Fu, L. J.; Liu, H.; Li, C.; Wu, Y. P.; Rahm, E.; Holze, R.; Wu, H. Q.

    2006-02-01

    Since the birth of the lithium ion battery in the early 1990s, its development has been very rapid and it has been widely applied as power source for a lot of light and high value electronics due to its significant advantages over traditional rechargeable battery systems. Recent research demonstrates the importance of surface structural features of electrode materials for their electrochemical performance, and in this paper the latest progress on this aspect is reviewed. Electrode materials are either anodic or cathodic ones. The former mainly include graphitic carbons, whose surfaces can be modified by mild oxidation, deposition of metals and metal oxides, coating with polymers and other kinds of carbons. Through these modifications, the surface structures of the graphitic carbon anodes are improved, and these improvements include: (1) smoothing the active edge surfaces by removing some reactive sites and/or defects on the graphite surface, (2) forming a dense oxide layer on the graphite surface, and (3) covering active edge structures on the graphite surface. Meanwhile, other accompanying changes occur: (1) production of nanochannels/micropores, (2) an increase in the electronic conductivity, (3) an inhibition of structural changes during cycling, (4) a reduction of the thickness of the SEI (solid-electrolyte-interface) layer, and (5) an increase in the number of host sites for lithium storage. As a result, the direct contact of graphite with the electrolyte solution is prevented, its surface reactivity with electrolytes, the decomposition of electrolytes, the co-intercalation of the solvated lithium ions and the charge-transfer resistance are decreased, and the movement of graphene sheets is inhibited. When the surfaces of cathode materials, mainly including LiCoO 2, LiNiO 2 and LiMn 2O 4, are coated with oxides such as MgO, Al 2O 3, ZnO, SnO 2, ZrO 2, Li 2Oṡ2B 2O 3 glass and other electroactive oxides, the coating can prevent their direct contact with the

  17. A study of the glow discharge characteristics of contact electrodes at atmospheric pressure in air

    SciTech Connect

    Liu, Wenzheng Sun, Guangliang Li, Chuanhui; Zhang, Rongrong

    2014-04-15

    Electric field distributions and discharge properties of rod-rod contact electrodes were studied under the condition of DBD for the steady generation of atmospheric pressure glow discharge plasma (APGD) in air. We found that under the effect of the initial electrons generated in a nanometer-scale gap, the rod-rod cross-contact electrodes yielded APGD plasma in air. Regarding the rod-rod cross-contact electrodes, increasing the working voltage expanded the strong electric field area of the gas gap so that both discharge area and discharge power increased, and the increase in the number of contact points kept the initial discharge voltage unchanged and caused an increase in the plasma discharge area and discharge power. A mesh-like structure of cross-contact electrodes was designed and used to generate more APGD plasma, suggesting high applicability.

  18. Clean Air Markets - Monitoring Surface Water Chemistry

    EPA Pesticide Factsheets

    Learn about how EPA uses Long Term Monitoring (LTM) and Temporily Integrated Monitoring of Ecosystems (TIME) to track the effect of the Clean Air Act Amendments on acidity of surface waters in the eastern U.S.

  19. Dynamic air layer on textured superhydrophobic surfaces.

    PubMed

    Vakarelski, Ivan U; Chan, Derek Y C; Marston, Jeremy O; Thoroddsen, Sigurdur T

    2013-09-03

    We provide an experimental demonstration that a novel macroscopic, dynamic continuous air layer or plastron can be sustained indefinitely on textured superhydrophobic surfaces in air-supersaturated water by a natural gas influx mechanism. This type of plastron is an intermediate state between Leidenfrost vapor layers on superheated surfaces and the equilibrium Cassie-Baxter wetting state on textured superhydrophobic surfaces. We show that such a plastron can be sustained on the surface of a centimeter-sized superhydrophobic sphere immersed in heated water and variations of its dynamic behavior with air saturation of the water can be regulated by rapid changes of the water temperature. The simple experimental setup allows for quantification of the air flux into the plastron and identification of the air transport model of the plastron growth. Both the observed growth dynamics of such plastrons and millimeter-sized air bubbles seeded on the hydrophilic surface under identical air-supersaturated solution conditions are consistent with the predictions of a well-mixed gas transport model.

  20. Optical Diagnostics of Air Flows Induced in Surface Dielectric Barrier Discharge Plasma Actuator

    NASA Astrophysics Data System (ADS)

    Kobatake, Takuya; Deguchi, Masanori; Suzuki, Junya; Eriguchi, Koji; Ono, Kouichi

    2014-10-01

    A surface dielectric barrier discharge (SDBD) plasma actuator has recently been intensively studied for the flow control over airfoils and turbine blades in the fields of aerospace and aeromechanics. It consists of two electrodes placed on both sides of the dielectric, where one is a top powered electrode exposed to the air, and the other is a bottom grounded electrode encapsulated with an insulator. The unidirectional gas flow along the dielectric surfaces is induced by the electrohydrodynamic (EHD) body force. It is known that the thinner the exposed electrode, the greater the momentum transfer to the air is, indicating that the thickness of the plasma is important. To analyze plasma profiles and air flows induced in the SDBD plasma actuator, we performed time-resolved and -integrated optical emission and schlieren imaging of the side view of the SDBD plasma actuator in atmospheric air. We applied a high voltage bipolar pulse (4-8 kV, 1-10 kHz) between electrodes. Experimental results indicated that the spatial extent of the plasma is much smaller than that of the induced flows. Experimental results further indicated that in the positive-going phase, a thin and long plasma is generated, where the optical emission is weak and uniform; on the other hand, in the negative-going phase, a thick and short plasma is generated, where a strong optical emission is observed near the top electrode.

  1. Modelling and Assessing Air-Surface Integration

    DTIC Science & Technology

    2011-06-01

    2011), Qu?c City , Qu?c, Canada, June 21-23, 2011. U.S. Government or Federal Rights License. 14. ABSTRACT Air-Surface Integration (ASI) is an...structure capability and identifies socio-technical issues in the ASI system for capability designers . 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF...for capability designers . 1. Introduction Air Surface Integration (ASI) has been conducted by forces in a variety of operations dating back to

  2. CNT Sheet Air Electrode for the Development of Ultra-High Cell Capacity in Lithium-Air Batteries

    PubMed Central

    Nomura, Akihiro; Ito, Kimihiko; Kubo, Yoshimi

    2017-01-01

    Lithium-air batteries (LABs) are expected to provide a cell with a much higher capacity than ever attained before, but their prototype cells present a limited areal cell capacity of no more than 10 mAh cm−2, mainly due to the limitation of their air electrodes. Here, we demonstrate the use of flexible carbon nanotube (CNT) sheets as a promising air electrode for developing ultra-high capacity in LAB cells, achieving areal cell capacities of up to 30 mAh cm−2, which is approximately 15 times higher than the capacity of cells with lithium-ion battery (LiB) technology (~2 mAh cm−2). During discharge, the CNT sheet electrode experienced enormous swelling to a thickness of a few millimeters because of the discharge product deposition of lithium peroxide (Li2O2), but the sheet was fully recovered after being fully charged. This behavior results from the CNT sheet characteristics of the flexible and fibrous conductive network and suggests that the CNT sheet is an effective air electrode material for developing a commercially available LAB cell with an ultra-high cell capacity. PMID:28378746

  3. Modeling of global surface air temperature

    NASA Astrophysics Data System (ADS)

    Gusakova, M. A.; Karlin, L. N.

    2012-04-01

    A model to assess a number of factors, such as total solar irradiance, albedo, greenhouse gases and water vapor, affecting climate change has been developed on the basis of Earth's radiation balance principle. To develop the model solar energy transformation in the atmosphere was investigated. It's a common knowledge, that part of the incoming radiation is reflected into space from the atmosphere, land and water surfaces, and another part is absorbed by the Earth's surface. Some part of outdoing terrestrial radiation is retained in the atmosphere by greenhouse gases (carbon dioxide, methane, nitrous oxide) and water vapor. Making use of the regression analysis a correlation between concentration of greenhouse gases, water vapor and global surface air temperature was obtained which, it is turn, made it possible to develop the proposed model. The model showed that even smallest fluctuations of total solar irradiance intensify both positive and negative feedback which give rise to considerable changes in global surface air temperature. The model was used both to reconstruct the global surface air temperature for the 1981-2005 period and to predict global surface air temperature until 2030. The reconstructions of global surface air temperature for 1981-2005 showed the models validity. The model makes it possible to assess contribution of the factors listed above in climate change.

  4. Effect of surface modifiers on the electrode reactions and conformation of cytochrome c3 adsorbed on a silver electrode.

    PubMed

    Hobara, D; Niki, K; Cotton, T M

    1998-01-01

    Surface-enhanced resonance Raman scattering and electroreflectance voltammetry were used to investigate the effect of electrode surface modification on the structure and redox properties of cytochrome c3 immobilized on Ag surfaces. It is shown that the redox reactions of cytochrome c3 are more reversible at an 11-mercaptoundecanoic acid modified Ag electrode as compared to a bare metal surface. The heme of cytochrome c3 is in a mixed low and high spin state when adsorbed at the bare electrode, whereas only the low spin form is present on the 11-mercaptoundecanoic acid modified electrode, suggesting that the native conformation is maintained in the latter case. The reduction potential is close to that of the most positive macroscopic potential as determined by electroreflectance spectroscopy. In contrast, the reduction potential as determined by SERRS undergoes a large positive shift in the presence of 4,4'-bipyridine, the magnitude of which is dependent upon the concentration of 4,4'-bipyridine. These results indicate that the effect of the cytochrome c3 interaction with the 4,4'-bipyridine-modified surface is significantly different as compared to its interaction with the 11-mercaptoundecaodoic acid modified surface. Moreover, the results emphasize that electrode modifiers can have dramatically different effects on the redox properties of different proteins. It is well known that 4,4'-bipyridine acts as a redox promoter in the case of cytochrome c, whereas no electrochemical or electroreflectance response was observed in the case of cytochrome c3.

  5. Conductive polymer foam surface improves the performance of a capacitive EEG electrode.

    PubMed

    Baek, Hyun Jae; Lee, Hong Ji; Lim, Yong Gyu; Park, Kwang Suk

    2012-12-01

    In this paper, a new conductive polymer foam-surfaced electrode was proposed for use as a capacitive EEG electrode for nonintrusive EEG measurements in out-of-hospital environments. The current capacitive electrode has a rigid surface that produces an undefined contact area due to its stiffness, which renders it unable to conform to head curvature and locally isolates hairs between the electrode surface and scalp skin, making EEG measurement through hair difficult. In order to overcome this issue, a conductive polymer foam was applied to the capacitive electrode surface to provide a cushioning effect. This enabled EEG measurement through hair without any conductive contact with bare scalp skin. Experimental results showed that the new electrode provided lower electrode-skin impedance and higher voltage gains, signal-to-noise ratios, signal-to-error ratios, and correlation coefficients between EEGs measured by capacitive and conventional resistive methods compared to a conventional capacitive electrode. In addition, the new electrode could measure EEG signals, while the conventional capacitive electrode could not. We expect that the new electrode presented here can be easily installed in a hat or helmet to create a nonintrusive wearable EEG apparatus that does not make users look strange for real-world EEG applications.

  6. Fuel Cell Electrodes for Hydrogen-Air Fuel Cell Assemblies.

    DTIC Science & Technology

    The report describes the design and evaluation of a hydrogen-air fuel cell module for use in a portable hydrid fuel cell -battery system. The fuel ... cell module consists of a stack of 20 single assemblies. Each assembly contains 2 electrically independent cells with a common electrolyte compartment

  7. Low cost stable air electrode material for high temperature solid oxide electrolyte electrochemical cells

    DOEpatents

    Kuo, Lewis J. H.; Singh, Prabhakar; Ruka, Roswell J.; Vasilow, Theodore R.; Bratton, Raymond J.

    1997-01-01

    A low cost, lanthanide-substituted, dimensionally and thermally stable, gas permeable, electrically conductive, porous ceramic air electrode composition of lanthanide-substituted doped lanthanum manganite is provided which is used as the cathode in high temperature, solid oxide electrolyte fuel cells and generators. The air electrode composition of this invention has a much lower fabrication cost as a result of using a lower cost lanthanide mixture, either a natural mixture or an unfinished lanthanide concentrate obtained from a natural mixture subjected to incomplete purification, as the raw material in place of part or all of the higher cost individual lanthanum. The mixed lanthanide primarily contains a mixture of at least La, Ce, Pr, and Nd, or at least La, Ce, Pr, Nd and Sm in its lanthanide content, but can also include minor amounts of other lanthanides and trace impurities. The use of lanthanides in place of some or all of the lanthanum also increases the dimensional stability of the air electrode. This low cost air electrode can be fabricated as a cathode for use in high temperature, solid oxide fuel cells and generators.

  8. Low cost stable air electrode material for high temperature solid oxide electrolyte electrochemical cells

    DOEpatents

    Kuo, L.J.H.; Singh, P.; Ruka, R.J.; Vasilow, T.R.; Bratton, R.J.

    1997-11-11

    A low cost, lanthanide-substituted, dimensionally and thermally stable, gas permeable, electrically conductive, porous ceramic air electrode composition of lanthanide-substituted doped lanthanum manganite is provided which is used as the cathode in high temperature, solid oxide electrolyte fuel cells and generators. The air electrode composition of this invention has a much lower fabrication cost as a result of using a lower cost lanthanide mixture, either a natural mixture or an unfinished lanthanide concentrate obtained from a natural mixture subjected to incomplete purification, as the raw material in place of part or all of the higher cost individual lanthanum. The mixed lanthanide primarily contains a mixture of at least La, Ce, Pr, and Nd, or at least La, Ce, Pr, Nd and Sm in its lanthanide content, but can also include minor amounts of other lanthanides and trace impurities. The use of lanthanides in place of some or all of the lanthanum also increases the dimensional stability of the air electrode. This low cost air electrode can be fabricated as a cathode for use in high temperature, solid oxide fuel cells and generators. 4 figs.

  9. Tip surface changes in endocardial stimulation electrode, visualised by scanning electron microscopy.

    PubMed

    Hladky, M; Horn, V; Kamaryt, P; Cabanova, J; Zeman, K

    1975-01-01

    The authors have been probably the first investigators who applied scanning electron microscopy to studies of the changes occurring in the surface of the metalic tip of an endocardial stimulating electrode. They found a lowered conductivity for secondary electron emission, and describe the surface changes in a platiniridium-tipped electrode which had been used for almost four years, in comparison with an unused electrode.

  10. Restructuring of an Ir(210) electrode surface by potential cycling.

    PubMed

    Soliman, Khaled A; Kolb, Dieter M; Kibler, Ludwig A; Jacob, Timo

    2014-01-01

    This study addresses the electrochemical surface faceting and restructuring of Ir(210) single crystal electrodes. Cyclic voltammetry measurements and in situ scanning tunnelling microscopy are used to probe structural changes and variations in the electrochemical behaviour after potential cycling of Ir(210) in 0.1 M H2SO4. Faceted structures are obtained electrochemically as a function of time by cycling at a scanrate of 1 V·s(-1) between -0.28 and 0.70 V vs SCE, i.e., between the onset of hydrogen evolution and the surface oxidation regime. The electrochemical behaviour in sulfuric acid solution is compared with that of thermally faceted Ir(210), which shows a sharp characteristic voltammetric peak for (311) facets. Structures similar to thermally-induced faceted Ir(210) are obtained electrochemically, which typically correspond to polyoriented facets at nano-pyramids. These structures grow anisotropically in a preferred direction and reach a height of about 5 nm after 4 h of cycling. The structural changes are reflected in variations of the electrocatalytic activity towards carbon monoxide adlayer oxidation.

  11. Restructuring of an Ir(210) electrode surface by potential cycling

    PubMed Central

    Soliman, Khaled A; Kolb, Dieter M; Jacob, Timo

    2014-01-01

    Summary This study addresses the electrochemical surface faceting and restructuring of Ir(210) single crystal electrodes. Cyclic voltammetry measurements and in situ scanning tunnelling microscopy are used to probe structural changes and variations in the electrochemical behaviour after potential cycling of Ir(210) in 0.1 M H2SO4. Faceted structures are obtained electrochemically as a function of time by cycling at a scanrate of 1 V·s−1 between −0.28 and 0.70 V vs SCE, i.e., between the onset of hydrogen evolution and the surface oxidation regime. The electrochemical behaviour in sulfuric acid solution is compared with that of thermally faceted Ir(210), which shows a sharp characteristic voltammetric peak for (311) facets. Structures similar to thermally-induced faceted Ir(210) are obtained electrochemically, which typically correspond to polyoriented facets at nano-pyramids. These structures grow anisotropically in a preferred direction and reach a height of about 5 nm after 4 h of cycling. The structural changes are reflected in variations of the electrocatalytic activity towards carbon monoxide adlayer oxidation. PMID:25247118

  12. Surface analysis of supercapacitor electrodes after long-lasting constant current tests

    NASA Astrophysics Data System (ADS)

    Jänes, Alar; Eskusson, Jaanus; Lust, Enn

    2013-12-01

    FIB-SEM, XPS, TOF-SIMS and electrochemical methods have been used for the characterisation of physical properties and chemical composition of microporous carbide derived carbon electrodes, prepared from TiC at 950 °C (noted as TiC-CDC) after 40000 charge/discharge cycles. Changes in surface chemical composition of TiC-CDC electrodes, includes partial contamination with reaction intermediates (F2, CHO-, CN-, organic radicals), and Al current collectors, like partial dissolution of Al from positively charged electrode and deposition of Al onto the negatively charged TiC-CDC electrode surface, have been analysed.

  13. Platinum electrode modification: Unique surface carbonization approach to improve performance and sensitivity.

    PubMed

    Lee, Hwi Yong; Barber, Cedrick; Minerick, Adrienne R

    2015-08-01

    Many microfluidic devices, also known as lab-on-a-chip devices, employ electrochemical detection methods using microelectrodes. Miniaturizing electrodes inevitably reduces electrode sensitivity and decreases the S/N, which limits applications within microfluidic devices. However, microelectrode surface modification can increase the surface area and sensitivity. In the present work, we report substantial improvement in platinum electrode performance and sensitivity by coating with carbon from red blood cells. The larger goal of this work was to measure DC electrical resistances of red blood cell suspensions in a microchannel for hematocrit determination. It was observed that as current responses of red blood cell suspensions were measured, the platinum electrode performance (reproducibility and S/N) improved with time. The platinum electrode electrocatalytic activity for red blood cell current measurements improved by 140%. Systematic experimentation revealed that red blood cells adsorb and carbonize the platinum electrode surfaces. The electrode surfaces before and after performance improvements were analyzed by field emission scanning electron microscopy, energy dispersive spectrometry, and Raman spectrometry. The formed carbon layers on the electrode surfaces were found to be proteomic and increased surface area with a porous three-dimensional structure, thus improving performance and stabilizing currents.

  14. Surface-enhanced Raman scattering of single-walled carbon nanotubes on modified silver electrode.

    PubMed

    Hou, Xiaomiao; Fang, Yan

    2008-04-01

    A roughed silver electrode modified with gold/silver nanoparticles is used as a substrate, on which high quality SERS of SWCNTs are obtained, indicating that the modified silver electrode is a high-quality SERS-active substrate for SWCNTs. Some new bands that indicate the structure of SWCNTs were obtained. The gold/silver nanoparticles modified on the roughed silver electrode surface can not only make sure the strong adsorption of SWCNTs in this system but also play an important role in magnifying the surface local electric field near the silver electrode surface through resonant surface plasmon excitation. From the rich information on the modified silver electrode obtained from the SERS and the potential dependent SERS, we may deduce the probable SERS mechanism in the process. The theory and experiment results indicate that it is can be used as a new technique for monitoring synthesis quality of SWCNTs. The probable reasons are given.

  15. Layered perovskite oxide: a reversible air electrode for oxygen evolution/reduction in rechargeable metal-air batteries.

    PubMed

    Takeguchi, Tatsuya; Yamanaka, Toshiro; Takahashi, Hiroki; Watanabe, Hiroshi; Kuroki, Tomohiro; Nakanishi, Haruyuki; Orikasa, Yuki; Uchimoto, Yoshiharu; Takano, Hiroshi; Ohguri, Nobuaki; Matsuda, Motofumi; Murota, Tadatoshi; Uosaki, Kohei; Ueda, Wataru

    2013-07-31

    For the development of a rechargeable metal-air battery, which is expected to become one of the most widely used batteries in the future, slow kinetics of discharging and charging reactions at the air electrode, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively, are the most critical problems. Here we report that Ruddlesden-Popper-type layered perovskite, RP-LaSr3Fe3O10 (n = 3), functions as a reversible air electrode catalyst for both ORR and OER at an equilibrium potential of 1.23 V with almost no overpotentials. The function of RP-LaSr3Fe3O10 as an ORR catalyst was confirmed by using an alkaline fuel cell composed of Pd/LaSr3Fe3O10-2x(OH)2x·H2O/RP-LaSr3Fe3O10 as an open circuit voltage (OCV) of 1.23 V was obtained. RP-LaSr3Fe3O10 also catalyzed OER at an equilibrium potential of 1.23 V with almost no overpotentials. Reversible ORR and OER are achieved because of the easily removable oxygen present in RP-LaSr3Fe3O10. Thus, RP-LaSr3Fe3O10 minimizes efficiency losses caused by reactions during charging and discharging at the air electrode and can be considered to be the ORR/OER electrocatalyst for rechargeable metal-air batteries.

  16. High performance air electrode for solid oxide regenerative fuel cells fabricated by infiltration of nano-catalysts

    NASA Astrophysics Data System (ADS)

    Lee, Sung-il; Kim, Jeonghee; Son, Ji-Won; Lee, Jong-Ho; Kim, Byung-Kook; Je, Hae-June; Lee, Hae-Weon; Song, Huesup; Yoon, Kyung Joong

    2014-03-01

    A high performance air electrode fabricated by infiltration of highly active nano-catalysts into a porous scaffold is demonstrated for high-temperature solid oxide regenerative fuel cells (SORFCs). The nitrate precursor solution for Sm0.5Sr0.5CoO3 (SSC) catalyst is impregnated into a porous La0.6Sr0.4Co0.2Fe0.8O3 (LSCF)-gadolinia-doped ceria (GDC) composite backbone, and extremely fine SSC nano-particles are uniformly synthesized by in-situ crystallization at the initial stage of SORFC operation via homogeneous nucleation induced by urea decomposition. The SSC nano-catalysts are in the size range of 40-80 nm and stable against coarsening upon the SORFC operation at 750 °C. The electrochemical performance is significantly improved by incorporation of SSC nano-catalysts in both power generation and hydrogen production modes. Systematic analysis on the impedance spectra reveals that the surface modification of the air electrode with nano-catalysts remarkably accelerates the chemical surface exchange reactions for both O2 reduction and O2- oxidation, which are the major limiting processes for SORFC performance.

  17. Ethanol oxidation on Pt single-crystal electrodes: surface-structure effects in alkaline medium.

    PubMed

    Busó-Rogero, Carlos; Herrero, Enrique; Feliu, Juan M

    2014-07-21

    Ethanol oxidation in 0.1 M NaOH on single-crystal electrodes has been studied using electrochemical and FTIR techniques. The results show that the activity order is the opposite of that found in acidic solutions. The Pt(111) electrode displays the highest currents and also the highest onset potential of all the electrodes. The onset potential for the oxidation of ethanol is linked to the adsorption of OH on the electrode surface. However, small (or even negligible) amounts of CO(ads) and carbonate are detected by FTIR, which implies that cleavage of the C-C bond is not favored in this medium. The activity of the electrodes diminishes quickly upon cycling. The diminution of the activity is proportional to the measured currents and is linked to the formation and polymerization of acetaldehyde, which adsorbs onto the electrode surface and prevents further oxidation.

  18. Assemblies of protective anion exchange membrane on air electrode for its efficient operation in aqueous alkaline electrolyte

    NASA Astrophysics Data System (ADS)

    Bertolotti, Bruno; Chikh, Linda; Vancaeyzeele, Cédric; Alfonsi, Séverine; Fichet, Odile

    2015-01-01

    Aqueous alkaline metal-air batteries represent promising energy storage devices when supplied with atmospheric air. However, under this condition, the air electrode shows a very short life time (i.e. 50 h of operation in 5 M LiOH at -10 mA cm-2), mainly due to the precipitation of carbonates inside the electrode porosity. The air electrode can then be protected by an anion exchange membrane on the electrolyte side. In this paper, we demonstrate that the efficiency of this protective membrane depends on the assembly method on the electrode. When a modified poly(epichlorohydrin) (PECH) network is synthesized directly on the electrode, the polymer seeps inside the electrode porosity, and a suitable interface inducing negligible additional polarization in comparison with classical pressure-assembled membranes is obtained. This protected electrode shows improved stability of up to 160 h of operation in 5 M LiOH. This performance is improved to 350 h by adjusting the conductivity and the ionic exchange capacity. Finally, the interest of interpenetrating polymer network (IPN) architecture compared to a single network is confirmed. Indeed, an electrode protected with a PECH/poly(2-hydroxyethyl methacrylate) (PHEMA) IPN is stable for 650 h in 5 M LiOH. In addition, degradation process becomes reversible since the assembly can be regenerated, which is not possible for the bare electrode.

  19. Electrode

    SciTech Connect

    Clere, T.M.

    1983-08-30

    A 3-dimensional electrode is disclosed having substantially coplanar and substantially flat portions and ribbon-like curved portions, said curved portions being symmetrical and alternating in rows above and below said substantially coplanar, substantially flat portions, respectively, and a geometric configuration presenting in one sectional aspect the appearance of a series of ribbon-like oblate spheroids interrupted by said flat portions and in another sectional aspect, 90/sup 0/ from said one aspect, the appearance of a square wave pattern.

  20. In situ plasma removal of surface contaminants from ion trap electrodes

    SciTech Connect

    Haltli, Raymond A.

    2015-05-01

    In this thesis, the construction and implementation of an in situ plasma discharge designed to remove surface contaminants from electrodes in an ion trapping experimental system is presented with results. In recent years, many advances have been made in using ion traps for quantum information processing. All of the criteria defined by DiVincenzo for using ion traps for implementing a quantum computer have been individually demonstrated, and in particular surface traps provide a scalable platform for ions. In order to be used for quantum algorithms, trapped ions need to be cooled to their motional (quantum mechanical) ground state. One of the hurdles in integrating surface ion traps for a quantum computer is minimizing electric field noise, which causes the ion to heat out of its motional ground state and which increases with smaller ion-to-electrode distances realized with surface traps. Surface contamination of trap electrodes is speculated to be the primary source of electric field noise. The main goal achieved by this work was to implement an in situ surface cleaning solution for surface electrode ion traps, which would not modify the ion trap electrode surface metal. Care was taken in applying the RF power in order to localize a plasma near the trap electrodes. A method for characterizing the energy of the plasma ions arriving at the ion trap surface is presented and results for plasma ion energies are shown. Finally, a method for quantifying the effectiveness of plasma cleaning of trap electrodes, using the surface analysis technique of X-ray photoelectron spectroscopy for measuring the amount and kind of surface contaminants, is described. A significant advantage of the trap electrode surface cleaning method presented here is the minimal changes necessary for implementation on a working ion trap experimental system.

  1. Global surface air temperatures - Update through 1987

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lebedeff, Sergej

    1988-01-01

    Data from meteorological stations show that surface air temperatures in the 1980s are the warmest in the history of instrumental records. The four warmest years on record are all in the 1980s, with the warmest years in the analysis being 1981 and 1987. The rate of warming between the mid-1960s and the present is higher than that which occurrred in the previous period of rapid warming between the 1880s and 1940.

  2. The cold and atmospheric-pressure air surface barrier discharge plasma for large-area sterilization applications

    SciTech Connect

    Wang Dacheng; Zhao Di; Feng Kecheng; Zhang Xianhui; Liu Dongping; Yang Size

    2011-04-18

    This letter reports a stable air surface barrier discharge device for large-area sterilization applications at room temperature. This design may result in visually uniform plasmas with the electrode area scaled up (or down) to the required size. A comparison for the survival rates of Escherichia coli from air, N{sub 2} and O{sub 2} surface barrier discharge plasmas is presented, and the air surface plasma consisting of strong filamentary discharges can efficiently kill Escherichia coli. Optical emission measurements indicate that reactive species such as O and OH generated in the room temperature air plasmas play a significant role in the sterilization process.

  3. Flexible shrink-induced high surface area electrodes for electrochemiluminescent sensing.

    PubMed

    Pegan, Jonathan D; Ho, Adrienne Y; Bachman, Mark; Khine, Michelle

    2013-11-07

    Photolithographically defined metallic thin film on commodity shrink-wrap is leveraged to create robust electrodes. By thermally shrinking the film, electrodes are reduced by 20× in footprint for improved resolution and conductivity with >600% enhancements in electrochemically active surface area; as electrochemiluminescent sensors, they demonstrate improved limits of detection.

  4. Electrochemical oxidation of guanine: electrode reaction mechanism and tailoring carbon electrode surfaces to switch between adsorptive and diffusional responses.

    PubMed

    Li, Qian; Batchelor-McAuley, Christopher; Compton, Richard G

    2010-06-03

    The electrochemical oxidation of guanine is studied in aqueous media at various carbon electrodes. Specifically edge plane pyrolytic graphite (EPPG), basal plane pyrolytic graphite (BPPG), and highly ordered pyrolytic graphite (HOPG) were used, and the voltammetry was found to vary significantly. In all cases, signals characteristic of adsorbed guanine were seen and the total charge passed varied from surface to surface in the order roughened BPPG > EPPG > BPPG > HOPG. It is of note that the peak height for the EPPG electrode is less than that found for roughened BPPG; furthermore, across the series of electrodes, there is a significant decrease in peak potential with increasing density of edge plane sites present at the electrode surface. This leads us to conclude that there are two dominating and controlling factors present: (i) the density of basal plane sites on which guanine can adsorb and (ii) the density of edge plane sites necessary for the electro-oxidation of the analyte. This conclusion is corroborated through further experiments with multi- and single-walled carbon nanotubes. Adsorption was seen to be enhanced by modification of the EPPG surface with alumina particles, and as such, increased peak signals were observed in their presence. It is further reported that via the pre-adsorption of acetone onto the graphite surface that the adsorption of guanine may be blocked, resulting in a diffusional voltammetric signal. This diffusional response has been successfully modeled and gives insight into the complex -4e(-), -4H(+) oxidation mechanism; specifically, it enables explanation of the observed change in rate-determining step with scan rate. The oxidation of guanine first proceeds via a two-electron oxidation followed by a chemical step to form 8-oxoguanine, then 8-oxoguanine is then further oxidized to form nonelectroactive products. The change is mechanism is attributed to the variation in potential of the first and second electron transfer with scan

  5. The Effect of Anodic Surface Treatment on the Oxidation of Catechols at Ultrasmall Carbon Ring Electrodes

    DTIC Science & Technology

    1991-07-09

    selectivity. A model of the surface formed following anodic oxidation is consistent with previous models involving both surface cleanliness and carbon...involving both surface cleanliness and carbon structure orientation. 2 INTRODUCTION Because of the vast electroanalytical utility of carbon electrodes...of the electron transfer rate following treatment are a function of the surface cleanliness and the orientation of the carbon structure

  6. Electrochemical oxidation of hydrazine and its derivatives on the surface of metal electrodes in alkaline media

    NASA Astrophysics Data System (ADS)

    Asazawa, Koichiro; Yamada, Koji; Tanaka, Hirohisa; Taniguchi, Masatoshi; Oguro, Keisuke

    Electrochemical oxidation of hydrazine and its derivatives on the surface of various metal electrodes in alkaline media was investigated. A comparison of various polycrystalline metal electrodes (Ni, Co, Fe, Cu, Ag, Au, and Pt) showed that Co and Ni electrodes have a lower onset potential for hydrazine oxidation than the Pt electrode. The onset oxidation potential of APA (aminopolyacrylamide), a hydrazine derivative (-0.127 V vs. reversible hydrogen electrode, RHE), was similar to that of hydrazine hydrate (-0.178 V vs. RHE) in the case of the Co electrode. APA oxidation was possible because of hydrazine desorption that was caused by APA hydrolysis. The hydrolysis reaction was brought about by a heat treatment. This result suggests that the hydrazine hydrolysis reaction of hydrazine derivatives makes it possible to store hydrazine hydrate safely.

  7. Effects of electrode surface roughness on motional heating of trapped ions

    NASA Astrophysics Data System (ADS)

    Lin, Kuan-Yu; Low, Guang Hao; Chuang, Isaac L.

    2016-07-01

    Electric-field noise is a major source of motional heating in trapped-ion quantum computation. While the influence of trap-electrode geometries on electric-field noise has been studied in patch potential and surface adsorbate models, only smooth surfaces are accounted for by current theory. The effects of roughness, a ubiquitous feature of surface electrodes, are poorly understood. We investigate its impact on electric-field noise by deriving a rough-surface Green's function and evaluating its effects on adsorbate-surface binding energies. At cryogenic temperatures, heating-rate contributions from adsorbates are predicted to exhibit an exponential sensitivity to local surface curvature, leading to either a large net enhancement or suppression over smooth surfaces. For typical experimental parameters, orders-of-magnitude variations in total heating rates can occur depending on the spatial distribution of adsorbates. Through careful engineering of electrode surface profiles, our results suggests that heating rates can be tuned over orders of magnitudes.

  8. Silver nanowire/polyaniline composite transparent electrode with improved surface properties

    SciTech Connect

    Kumar, A.B.V. Kiran; Jiang, Jianwei; Bae, Chang Wan; Seo, Dong Min; Piao, Longhai Kim, Sang-Ho

    2014-09-15

    Highlights: • AgNWs/PANI transparent electrode was prepared by layer-by-layer coating method. • The surface roughness of the electrode reached to 6.5 nm (root mean square). • The electrode had reasonable sheet resistance (25 Ω/□) and transmittance (83.5%). - Abstract: Silver nanowires (AgNWs) are as potential candidates to replace indium tin oxide (ITO) in transparent electrodes because of their preferred conducting and optical properties. However, their rough surface properties are not favorable for the fabrication of optoelectronic devices, such as displays and thin-film solar cells. In the present investigation, AgNWs/polyaniline composite transparent electrodes with better surface properties were successfully prepared. AgNWs were incorporated into polyaniline:polystyrene sulfonate (PANI:PSS) by layer-by-layer coating and mechanical pressing. PANI:PSS decreased the surface roughness of the AgNWs electrode by filling the gap of the random AgNWs network. The transparent composite electrode had decreased surface roughness (root mean square 6.5 nm) with reasonable sheet resistance (25 Ω/□) and transmittance (83.5%)

  9. Nature of the Surface-Exposed Cytochrome-Electrode Interactions in Electroactive Biofilms of Desulfuromonas acetoxidans.

    PubMed

    Alves, A; Ly, H K; Hildebrandt, P; Louro, R O; Millo, D

    2015-06-25

    Metal-respiring bacteria are microorganisms capable of oxidizing organic pollutants present in wastewater and transferring the liberated electrons to an electrode. This ability has led to their application as catalysts in bioelectrochemical systems (BESs), a sustainable technology coupling bioremediation to electricity production. Crucial for the functioning of these BESs is a complex protein architecture consisting of several surface-exposed multiheme proteins, called outer membrane cytochromes, wiring the cell metabolism to the electrode. Although the role of these proteins has been increasingly understood, little is known about the protein-electrode interactions and their impact on the performance of BESs. In this study, we used surface-enhanced resonance Raman spectroscopy in combination with electrochemical techniques to unravel the nature of the protein-electrode interaction for the outer membrane cytochrome OmcB from Desulfuromonas acetoxidans (Dace). Comparing the spectroelectrochemical properties of OmcB bound directly to the electrode surface with those of the same protein embedded inside an electroactive biofilm, we have shown that the surface-exposed cytochromes of Dace biofilms are in direct contact with the electrode surface. Even if direct binding causes protein denaturation, the biofilm possesses the ability to minimize the extent of the damage maximizing the amount of cells in direct electrical communication with the electrode.

  10. Simulating Supercapacitors: Can We Model Electrodes As Constant Charge Surfaces?

    PubMed

    Merlet, Céline; Péan, Clarisse; Rotenberg, Benjamin; Madden, Paul A; Simon, Patrice; Salanne, Mathieu

    2013-01-17

    Supercapacitors based on an ionic liquid electrolyte and graphite or nanoporous carbon electrodes are simulated using molecular dynamics. We compare a simplified electrode model in which a constant, uniform charge is assigned to each carbon atom with a realistic model in which a constant potential is applied between the electrodes (the carbon charges are allowed to fluctuate). We show that the simulations performed with the simplified model do not provide a correct description of the properties of the system. First, the structure of the adsorbed electrolyte is partly modified. Second, dramatic differences are observed for the dynamics of the system during transient regimes. In particular, upon application of a constant applied potential difference, the increase in the temperature, due to the Joule effect, associated with the creation of an electric current across the cell follows Ohm's law, while unphysically high temperatures are rapidly observed when constant charges are assigned to each carbon atom.

  11. Multilayer graphene electrodes for one-port surface acoustic wave resonator mass sensor

    NASA Astrophysics Data System (ADS)

    Leong, Ainan; Swamy, Varghese; Ramakrishnan, N.

    2017-02-01

    A one-port surface acoustic wave (SAW) resonator mass sensor composed of multilayer graphene (MLG) electrodes was investigated by the finite element method (FEM) and analyses were carried out to study the enhancement of sensitivity and the secondary effects caused by MLG electrodes on the performance of the resonator. Unlike metal electrodes, MLG electrode offers elastic loading to the contact surface, as evidenced by the increase in the surface velocity of the SAW device. In terms of the sensitivity of the mass sensor, MLG electrode showed the largest center frequency shift in response to a change in mass loading, as well as when used as a gas sensor to detect volatile organic compounds (VOCs). Also, MLG electrodes offered the least triple transit signal (TTS) and bulk acoustic wave (BAW) generations compared with Al and Au–Cr electrodes. Thus, the one-port SAW resonator with graphene electrodes not only possesses excellent performance characteristics but also gives rise to new opportunities in the development of highly sensitive mass sensors.

  12. Solid oxide fuel cells, and air electrode and electrical interconnection materials therefor

    DOEpatents

    Bates, J.L.

    1992-09-01

    In one aspect of the invention, an air electrode material for a solid oxide fuel cell comprises Y[sub 1[minus]a]Q[sub a]MnO[sub 3], where Q is selected from the group consisting of Ca and Sr or mixtures thereof and a' is from 0.1 to 0.8. Preferably, a' is from 0.4 to 0.7. In another aspect of the invention, an electrical interconnection material for a solid oxide fuel cell comprises Y[sub 1[minus]b]Ca[sub b]Cr[sub 1[minus]c]Al[sub c]O[sub 3], where b' is from 0.1 to 0.6 and c' is from 0 to 9.3. Preferably, b' is from 0.3 to 0.5 and c' is from 0.05 to 0.1. A composite solid oxide electrochemical fuel cell incorporating these materials comprises: a solid oxide air electrode and an adjacent solid oxide electrical interconnection which commonly include the cation Y, the air electrode comprising Y[sub 1[minus]a]Q[sub a]MnO[sub 3], where Q is selected from the group consisting of Ca and Sr or mixtures thereof and a' is from 0.1 to 0.8, the electrical interconnection comprising Y[sub 1[minus]b]Ca[sub b]Cr[sub 1[minus]c]Al[sub c]O[sub 3], where b' is from 0.1 to 0.6 and c' is from 0.0 to 0.3; a yttrium stabilized solid electrolyte comprising (1[minus]d)ZrO[sub 2]-(d)Y[sub 2]O[sub 3] where d' is from 0.06 to 0.5; and a solid fuel electrode comprising X-ZrO[sub 2], where X' is an elemental metal. 5 figs.

  13. Solid oxide fuel cells, and air electrode and electrical interconnection materials therefor

    DOEpatents

    Bates, J. Lambert

    1992-01-01

    In one aspect of the invention, an air electrode material for a solid oxide fuel cell comprises Y.sub.1-a Q.sub.a MnO.sub.3, where "Q" is selected from the group consisting of Ca and Sr or mixtures thereof and "a" is from 0.1 to 0.8. Preferably, "a" is from 0.4 to 0.7. In another aspect of the invention, an electrical interconnection material for a solid oxide fuel cell comprises Y.sub.1-b Ca.sub.b Cr.sub.1-c Al.sub.c O.sub.3, where "b" is from 0.1 to 0.6 and "c" is from 0 to 9.3. Preferably, "b" is from 0.3 to 0.5 and "c" is from 0.05 to 0.1. A composite solid oxide electrochemical fuel cell incorporating these materials comprises: a solid oxide air electrode and an adjacent solid oxide electrical interconnection which commonly include the cation Y, the air electrode comprising Y.sub.1-a Q.sub.a MnO.sub.3, where "Q" is selected from the group consisting of Ca and Sr or mixtures thereof and "a" is from 0.1 to 0.8, the electrical interconnection comprising Y.sub.1-b Ca.sub.b Cr.sub.1-c Al.sub.c O.sub.3, where "b" is from 0.1 to 0.6 and "c" is from 0.0 to 0.3; a yttrium stabilized solid electrolyte comprising (1-d)ZrO.sub.2 -(d)Y.sub.2 O.sub.3 where "d" is from 0.06 to 0.5; and a solid fuel electrode comprising X-ZrO.sub.2, where "X" is an elemental metal.

  14. in situ plasma removal of surface contaminants from ion trap electrodes

    SciTech Connect

    Haltli, Raymond A.

    2015-04-01

    This research resulted in a construction and implementation of an in situ plasma discharge to remove surface contaminants from electrodes in an ion trapping experimental system is presented with results.

  15. Numerical modelling of needle-grid electrodes for negative surface corona charging system

    NASA Astrophysics Data System (ADS)

    Zhuang, Y.; Chen, G.; Rotaru, M.

    2011-08-01

    Surface potential decay measurement is a simple and low cost tool to examine electrical properties of insulation materials. During the corona charging stage, a needle-grid electrodes system is often used to achieve uniform charge distribution on the surface of the sample. In this paper, a model using COMSOL Multiphysics has been developed to simulate the gas discharge. A well-known hydrodynamic drift-diffusion model was used. The model consists of a set of continuity equations accounting for the movement, generation and loss of charge carriers (electrons, positive and negative ions) coupled with Poisson's equation to take into account the effect of space and surface charges on the electric field. Four models with the grid electrode in different positions and several mesh sizes are compared with a model that only has the needle electrode. The results for impulse current and surface charge density on the sample clearly show the effect of the extra grid electrode with various positions.

  16. The effect of electrode surface roughness on the motional heating rate of electromagnetic trapped ions

    NASA Astrophysics Data System (ADS)

    Lin, Kuan-Yu; Low, Guang Hao; Chuang, Isaac

    Electric field noise is a major source of motional heating in trapped ion quantum computation. While it is well known that this noise is influenced by trap electrode geometry in patch potential and surface adsorbate models, this has only been analyzed for smooth surfaces. We investigate the dependence of electric field noise on the roughness of surface electrodes by deriving a Green's function describing this roughness, and evaluating its effects on adsorbate-surface binding energies. At cryogenic temperature, surface roughness is found to exponentially enhance or suppress heating rate, depending on the density distribution of surface adsorbates. Our result suggests that heating rates can be tuned over orders of magnitude by careful engineering of electrode surface profiles.

  17. A large-area diffuse air discharge plasma excited by nanosecond pulse under a double hexagon needle-array electrode.

    PubMed

    Liu, Zhi-Jie; Wang, Wen-Chun; Yang, De-Zheng; Wang, Sen; Zhang, Shuai; Tang, Kai; Jiang, Peng-Chao

    2014-01-01

    A large-area diffuse air discharge plasma excited by bipolar nanosecond pulse is generated under a double hexagon needle-array electrode at atmospheric pressure. The images of the diffuse discharge, electric characteristics, and the optical emission spectra emitted from the diffuse air discharge plasma are obtained. Based on the waveforms of pulse voltage and current, the power consumption, and the power density of the diffuse air discharge plasma are investigated under different pulse peak voltages. The electron density and the electron temperature of the diffuse plasma are estimated to be approximately 1.42×10(11) cm(-3) and 4.4 eV, respectively. The optical emission spectra are arranged to determine the rotational and vibrational temperatures by comparing experimental with simulated spectra. Meanwhile, the rotational and vibrational temperatures of the diffuse discharge plasma are also discussed under different pulse peak voltages and pulse repetition rates, respectively. In addition, the diffuse air discharge plasma can form an area of about 70×50 mm(2) on the surface of dielectric layer and can be scaled up to the required size.

  18. Silver nanoparticle-decorated carbon nanotubes as bifunctional gas-diffusion electrodes for zinc-air batteries

    NASA Astrophysics Data System (ADS)

    Wang, T.; Kaempgen, M.; Nopphawan, P.; Wee, G.; Mhaisalkar, S.; Srinivasan, M.

    Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence may be useful for mobile and portable applications.

  19. Method of forming macro-structured high surface area transparent conductive oxide electrodes

    DOEpatents

    Forman, Arnold J.; Chen, Zhebo; Jaramillo, Thomas F.

    2016-01-05

    A method of forming a high surface area transparent conducting electrode is provided that includes depositing a transparent conducting thin film on a conductive substrate, where the transparent conducting thin film includes transparent conductive particles and a solution-based transparent conducting adhesive layer which serves to coat and bind together the transparent conducting particles, and heat treating the transparent conducting adhesion layer on the conductive substrate, where an increased surface area transparent conducting electrode is formed.

  20. Studies on the oxygen reduction catalyst for zinc-air battery electrode

    NASA Astrophysics Data System (ADS)

    Wang, Xianyou; Sebastian, P. J.; Smit, Mascha A.; Yang, Hongping; Gamboa, S. A.

    In this paper, perovskite type La 0.6Ca 0.4CoO 3 as a catalyst of oxygen reduction was prepared, and the structure and performance of the catalysts was examined by means of IR, X-ray diffraction (XRD), and thermogravimetric (TG). Mixed catalysts doped, some metal oxides were put also used. The cathodic polarization curves for oxygen reduction on various catalytic electrodes were measured by linear sweep voltammetry (LSV). A Zn-air battery was made with various catalysts for oxygen reduction, and the performance of the battery was measured with a BS-9300SM rechargeable battery charge/discharge device. The results showed that the perovskite type catalyst (La 0.6Ca 0.4CoO 3) doped with metal oxide is an excellent catalyst for the zinc-air battery, and can effectively stimulate the reduction of oxygen and improve the properties of zinc-air batteries, such as discharge capacity, etc.

  1. Mechanical Behavior of Free-Standing Fuel Cell Electrodes on Water Surface.

    PubMed

    Kim, Sanwi; Kim, Jae-Han; Oh, Jong-Gil; Jang, Kyung-Lim; Jeong, Byeong-Heon; Hong, Bo Ki; Kim, Taek-Soo

    2016-06-22

    Fundamental understanding of the mechanical behavior of polymer electrolyte fuel cell electrodes as free-standing materials is essential to develop mechanically robust fuel cells. However, this has been a significant challenge due to critical difficulties, such as separating the pristine electrode from the substrate without damage and precisely measuring the mechanical properties of the very fragile and thin electrodes. We report the mechanical behavior of free-standing fuel cell electrodes on the water surface through adopting an innovative ice-assisted separation method to separate the electrode from decal transfer film. It is found that doubling the ionomer content in electrodes increases not only the tensile stress at the break and the Young's modulus (E) of the electrodes by approximately 2.1-3.5 and 1.7-2.4 times, respectively, but also the elongation at the break by approximately 1.5-1.7 times, which indicates that stronger, stiffer, and tougher electrodes are attained with increasing ionomer content, which have been of significant interest in materials research fields. The scaling law relationship between Young's modulus and density (ρ) has been unveiled as E ∼ ρ(1.6), and it is compared with other materials. These findings can be used to develop mechanically robust electrodes for fuel cell applications.

  2. A motion artifact generation and assessment system for the rapid testing of surface biopotential electrodes.

    PubMed

    Cömert, Alper; Hyttinen, Jari

    2015-01-01

    Dry electrodes can reduce cost while increasing the usability and comfort of wearable monitoring systems. They are, however, susceptible to motion artifacts. The present electrode testing methods lack reliability and do not separate the factors that affect the motion artifact. In this paper, we introduce a first generation motion artifact generation and assessment system that generates the speed, amplitude, and pattern-wise programmable movement of the electrode. The system simultaneously measures electrode-skin impedance, the motion artifact, and one channel of an electrocardiogram that contains the motion artifact and monitors the mounting force applied to the electrode. We demonstrate the system by comparing the applied movement and the measured signals for electrode movements up to 6 mm and movement frequencies from 0.4 Hz to 4 Hz. Results show that the impedance change and surface potential are visually clearly related to the applied motion, with average correlations of 0.89 and 0.64, respectively. The applied force, electrode location, and electrode structure all affect the motion artifact. The setup enables the motion of the electrode to be accurately controlled. The system can be used as a precursor to the testing of integrated systems because it enables thorough, repeatable, and robust motion artifact studies. The system allows a deeper insight into motion artifacts and the interplay of the various factors that affect them.

  3. High-voltage electrode optimization towards uniform surface treatment by a pulsed volume discharge

    NASA Astrophysics Data System (ADS)

    Ponomarev, A. V.; Pedos, M. S.; Scherbinin, S. V.; Mamontov, Y. I.; Ponomarev, S. V.

    2015-11-01

    In this study, the shape and material of the high-voltage electrode of an atmospheric pressure plasma generation system were optimised. The research was performed with the goal of achieving maximum uniformity of plasma treatment of the surface of the low-voltage electrode with a diameter of 100 mm. In order to generate low-temperature plasma with the volume of roughly 1 cubic decimetre, a pulsed volume discharge was used initiated with a corona discharge. The uniformity of the plasma in the region of the low-voltage electrode was assessed using a system for measuring the distribution of discharge current density. The system's low-voltage electrode - collector - was a disc of 100 mm in diameter, the conducting surface of which was divided into 64 radially located segments of equal surface area. The current at each segment was registered by a high-speed measuring system controlled by an ARM™-based 32-bit microcontroller. To facilitate the interpretation of results obtained, a computer program was developed to visualise the results. The program provides a 3D image of the current density distribution on the surface of the low-voltage electrode. Based on the results obtained an optimum shape for a high-voltage electrode was determined. Uniformity of the distribution of discharge current density in relation to distance between electrodes was studied. It was proven that the level of non-uniformity of current density distribution depends on the size of the gap between electrodes. Experiments indicated that it is advantageous to use graphite felt VGN-6 (Russian abbreviation) as the material of the high-voltage electrode's emitting surface.

  4. Electrochemistry as an attractive and effective tool for the synthesis and immobilization of porphyrins on an electrode surface.

    PubMed

    Hebié, Seydou; Dimé, Abdou K D; Devillers, Charles H; Lucas, Dominique

    2015-05-26

    Magnesium(II) 10-phenyl-5,15-p-ditolylporphyrin is easily and cleanly transformed by electrolysis. A nitro group is first introduced at the free meso position by anodic substitution. Hydrogenation into the amine is then carried out electrocatalytically under ambient conditions with water as a hydrogen supplier. The synthesized porphyrin under the nickel(II) form can be covalently grafted onto a platinum electrode by electrochemical reduction of the diazonium cation, generated in situ by a reaction of the nickel(II) aminoporphyrin with sodium nitrite and trifluoroacetic acid. The electrosynthesized thin film gives an electrochemical response typical of a porphyrin material. Films grown under our conditions have a maximum surface coverage of approximately 5×10(-10)  mol cm(-2). The modified electrode exhibits a reproducible electrochemical behavior and a good level of stability over potential cycling and exposition to air.

  5. Enhanced surface production in H{sup -} ion sources by introducing a negatively biased secondary electrode

    SciTech Connect

    An, Young Hwa; Jung, Bong Ki; Hwang, Y. S.

    2010-02-15

    A transformer coupled plasma negative hydrogen ion source with an external rf antenna has been developed at SNU, which is capable of continuous operation with long lifetime. A positively biased plasma electrode (PE) has been successfully used for the optimization of H{sup -} extraction. With molybdenum-coated stainless steel PE, the enhancement of H{sup -} production at the electrode surface was observed at the bias voltage lower than the plasma potential. However, the low bias voltage is unfavorable to H{sup -} beam extraction since the negative ions are repelled. A second electrode is inserted in front of the PE to enhance H{sup -} production at the electrode surface without impeding beam extraction. By biasing the secondary electrode (SE) more negatively, H{sup -} production is clearly enhanced although the SE itself reduces H{sup -} beam currents because of suppressed electron transport in front of the PE. In this configuration enhancement of surface productions is most pronounced in tantalum electrode among various electrode materials.

  6. A highly permeable and enhanced surface area carbon-cloth electrode for vanadium redox flow batteries

    NASA Astrophysics Data System (ADS)

    Zhou, X. L.; Zhao, T. S.; Zeng, Y. K.; An, L.; Wei, L.

    2016-10-01

    In this work, a high-performance porous electrode, made of KOH-activated carbon-cloth, is developed for vanadium redox flow batteries (VRFBs). The macro-scale porous structure in the carbon cloth formed by weaving the carbon fibers in an ordered manner offers a low tortuosity (∼1.1) and a broad pore distribution from 5 μm to 100 μm, rendering the electrode a high hydraulic permeability and high effective ionic conductivity, which are beneficial for the electrolyte flow and ion transport through the porous electrode. The use of KOH activation method to create nano-scale pores on the carbon-fiber surfaces leads to a significant increase in the surface area for redox reactions from 2.39 m2 g-1 to 15.4 m2 g-1. The battery assembled with the present electrode delivers an energy efficiency of 80.1% and an electrolyte utilization of 74.6% at a current density of 400 mA cm-2, as opposed to an electrolyte utilization of 61.1% achieved by using a conventional carbon-paper electrode. Such a high performance is mainly attributed to the combination of the excellent mass/ion transport properties and the high surface area rendered by the present electrode. It is suggested that the KOH-activated carbon-cloth electrode is a promising candidate in redox flow batteries.

  7. Polymer Coatings of Cochlear Implant Electrode Surface – An Option for Improving Electrode-Nerve-Interface by Blocking Fibroblast Overgrowth

    PubMed Central

    Hadler, C.; Aliuos, P.; Brandes, G.; Warnecke, A.; Bohlmann, J.; Dempwolf, W.; Menzel, H.; Lenarz, T.; Reuter, G.; Wissel, K.

    2016-01-01

    Overgrowth of connective tissue and scar formation induced by the electrode array insertion increase the impedance and, thus, diminish the interactions between neural probes as like cochlear implants (CI) and the target tissue. Therefore, it is of great clinical interest to modify the carrier material of the electrodes to improve the electrode nerve interface for selective cell adhesion. On one side connective tissue growth needs to be reduced to avoid electrode array encapsulation, on the other side the carrier material should not compromise the interaction with neuronal cells. The present in vitro-study qualitatively and quantitatively characterises the interaction of fibroblasts, glial cells and spiral ganglion neurons (SGN) with ultrathin poly(N,N-dimethylacrylamide) (PDMAA), poly(2-ethyloxazoline) (PEtOx) and poly([2-methacryloyloxy)ethyl]trimethylammoniumchlorid) (PMTA) films immobilised onto glass surfaces using a photoreactive anchor layer. The layer thickness and hydrophilicity of the polymer films were characterised by ellipsometric and water contact angle measurement. Moreover the topography of the surfaces was investigated using atomic force microscopy (AFM). The neuronal and non-neuronal cells were dissociated from spiral ganglions of postnatal rats and cultivated for 48 h on top of the polymer coatings. Immunocytochemical staining of neuronal and intermediary filaments revealed that glial cells predominantly attached on PMTA films, but not on PDMAA and PEtOx monolayers. Hereby, strong survival rates and neurite outgrowth were only found on PMTA, whereas PDMAA and PEtOx coatings significantly reduced the SG neuron survival and neuritogenesis. As also shown by scanning electron microscopy (SEM) SGN strongly survived and retained their differentiated phenotype only on PMTA. In conclusion, survival and neuritogenesis of SGN may be associated with the extent of the glial cell growth. Since PMTA was the only of the polar polymers used in this study bearing

  8. A Lithographically-Patterned, Elastic Multi-electrode Array for Surface Stimulation of the Spinal Cord

    PubMed Central

    Meacham, Kathleen W.; Giuly, Richard J.; Guo, Liang; Hochman, Shawn; DeWeerth, Stephen P.

    2008-01-01

    A new, scalable process for microfabrication of a silicone-based, elastic multi-electrode array (MEA) is presented. The device is constructed by spinning poly(dimethylsiloxane) (PDMS) silicone elastomer onto a glass slide, depositing and patterning gold to construct wires and electrodes, spinning on a second PDMS layer, and then micropatterning the second PDMS layer to expose electrode contacts. The micropatterning of PDMS involves a custom reactive ion etch (RIE) process that preserves the underlying gold thin film. Once completed, the device can be removed from the glass slide for conformal interfacing with neural tissue. Prototype MEAs feature electrodes smaller than those known to be reported on silicone substrate (60 μm diameter exposed electrode area) and were capable of selectively stimulating the surface of the in vitro isolated spinal cord of the juvenile rat. Stretchable serpentine traces were also incorporated into the functional PDMS-based MEA, and their implementation and testing is described. PMID:17914674

  9. Renewable Solid Electrodes in Microfluidics: Recovering the Electrochemical Activity without Treating the Surface.

    PubMed

    Teixeira, Carlos A; Giordano, Gabriela F; Beltrame, Maisa B; Vieira, Luis C S; Gobbi, Angelo L; Lima, Renato S

    2016-11-15

    The contamination, passivation, or fouling of the detection electrodes is a serious problem undermining the analytical performance of electroanalytical devices. The methods to regenerate the electrochemical activity of the solid electrodes involve mechanical, physical, or chemical surface treatments that usually add operational time, complexity, chemicals, and further instrumental requirements to the analysis. In this paper, we describe for the first time a reproducible method for renewing solid electrodes whenever their morphology or composition are nonspecifically changed without any surface treatment. These renewable electrodes are the closest analogue to the mercury drop electrodes. Our approach was applied in microfluidics, where the downsides related to nonspecific modifications of the electrode are more critical. The renewal consisted in manually sliding metal-coated microwires across a channel with the sample. For this purpose, the chip was composed of a single piece of polydimethylsiloxane (PDMS) with three parallel channels interconnected to one perpendicular and top channel. The microwires were inserted in each one of the parallel channels acting as working, counter, and pseudoreference electrodes for voltammetry. This assembly allowed the renewal of all the three electrodes by simply pulling the microwires. The absence of any interfaces in the chips and the elastomeric nature of the PDMS allowed us to pull the microwires without the occurrence of leakages for the electrode channels even at harsh flow rates of up to 40.0 mL min(-1). We expect this paper can assist the researchers to develop new microfluidic platforms that eliminate any steps of electrode cleaning, representing a powerful alternative for precise and robust analyses to real samples.

  10. Effects of Electrode Surface Morphology on the Transduction of Ionic Polymer-Metal Composites

    NASA Astrophysics Data System (ADS)

    Palmre, Viljar

    Ionic polymer-metal composites (IPMCs) are innovative smart materials that exhibit electromechanical and mechanoelectrical transduction (conversion of electrical input into mechanical deformation and vice versa). Due to low driving voltage (< 5 V) and ability to operate in aqueous environment, IPMCs are attractive for developing soft actuators and sensors for underwater robots and medical devices. This dissertation focuses on investigating the effects of electrode surface morphology in the transduction of Pt and Pd-Pt electrodes-based IPMCs, with the aim to improve the electrode surface design and thereby enhance the transduction performance of the material. Firstly, the synthesis techniques are developed to control and manipulate the surface structure of the mentioned electrodes through the electroless plating process. Using these techniques, IPMCs with different electrode surface structures are fabricated. The changes in the electrode surface morphology and the resulting effects on the material's electromechanical, mechanoelectrical, electrochemical and mechanical properties area examined and analyzed. This study shows that increasing the impregnation-reduction cycles under appropriate conditions leads to the formation and growth of platinum nanoparticles with sharp tips and edges---called Pt nanothorn assemblies---at the polymer-electrode interface. IPMCs designed with such nanostructured Pt electrodes are first to be reported. The experiments demonstrate that the formation and growth of Pt nanothorn assemblies at the electrode interface increases considerably the total transported charge during the transduction, thereby increasing significantly the displacement and blocking force output of IPMC. The improvement of the mentioned electromechanical properties was 3--5 times, depending on the input voltage and frequency used. Also, the peak mechanoelectrically induced voltage increased somewhat, although the overall effect of the surface structure was relatively

  11. Practical aspects in surface biopotential electrode placement for smart clothing: A simulation study

    NASA Astrophysics Data System (ADS)

    Mulyadi, Indra H.; Haueisen, Jens; Supriyanto, Eko

    2017-02-01

    In addition to physiological aspects, placement of surface biopotential electrodes for smart clothing should consider practical aspects due to their dynamic application environment. This study is aimed at finding the best places to put the electrode on areas where the measurement is practically reliable. Calculation was performed by using three practical aspects: 1) skin-shirt gap; 2) shirt movement, and 4) regional sweat rate. We employed 3DS Max software to simulate shirt behavior. The simulation result showed that generally practical satisfaction degrees are higher in the posterior. The quantitative approach may help smart clothing designers to choose the locations to place electrodes.

  12. Conformable actively multiplexed high-density surface electrode array for brain interfacing

    DOEpatents

    Rogers, John; Kim, Dae-Hyeong; Litt, Brian; Viventi, Jonathan

    2015-01-13

    Provided are methods and devices for interfacing with brain tissue, specifically for monitoring and/or actuation of spatio-temporal electrical waveforms. The device is conformable having a high electrode density and high spatial and temporal resolution. A conformable substrate supports a conformable electronic circuit and a barrier layer. Electrodes are positioned to provide electrical contact with a brain tissue. A controller monitors or actuates the electrodes, thereby interfacing with the brain tissue. In an aspect, methods are provided to monitor or actuate spatio-temporal electrical waveform over large brain surface areas by any of the devices disclosed herein.

  13. Surface electromyographic electrode pair with built-in buffer-amplifiers.

    PubMed

    Fujisawa, M; Uchida, K; Yamada, Y; Ishibashi, K

    1990-03-01

    By means of a surface electrode with an operational amplifier, a new electrode unit suitable for an electromyographic-biofeedback apparatus and for portable electromyography used outside a Faraday cage was developed. The operational amplifier, which has an output impedance lower than 10 ohms, functions as an efficient buffer amplifier and is able to protect the EMG signals from background noises. This new electrode unit is small (32 x 12 x 5 mm), waterproof, and inexpensive. Because its structure is simple, it can be built in any laboratory.

  14. Lactose electroisomerization into lactulose: effect of the electrode material, active membrane surface area-to-electrode surface area ratio, and interelectrode-membrane distance.

    PubMed

    Aït-Aissa, Amara; Aïder, Mohammed

    2014-01-01

    The aim of the present work was to study and develop an innovative, clean, and environmentally friendly process for lactulose synthesis by electroactivation of lactose. In this work, the electrode material (type 304 stainless steel, titanium, and copper), dimensionless interelectrode-membrane distance at the cathodic compartment (0.36, 0.68, and 1), and the membrane:electrode surface area ratio (0.23, 0.06, and 0.015) were considered to be the factors that could affect the kinetic conversion of lactose into lactulose. The reactions were conducted under an initial lactose concentration of 0.15mol/L at 10°C, Froude number (mixing speed) of 2.05×10(-2), and electric current intensity of 300mA for 30min. The highest lactulose formation yield of 32.50% (0.05mol/L) was obtained by using a copper electrode, interelectrode-membrane distance of 0.36, and membrane:electrode surface area ratio of 0.23. The 2-parameter Langmuir, Freundlich, and Temkin isotherm models were used for the prediction of the lactose isomerization kinetics as well as the 3-parameter Langmuir-Freundlich isotherm model. It was shown that the lactose isomerization kinetics into lactulose followed the Temkin and Langmuir-Freundlich models with coefficients of determination of 0.99 and 0.90 and a relative error of 1.42 to 1.56% and 4.27 to 4.37%, respectively.

  15. Kilohertz Electrical Stimulation Nerve Conduction Block: Effects of Electrode Surface Area.

    PubMed

    Patel, Yogi A; Kim, Brian S; Rountree, William S; Butera, Robert J

    2017-03-17

    Kilohertz electrical stimulation (KES) induces repeatable and reversible conduction block of nerve activity and is a potential therapeutic option for various diseases and disorders resulting from pathological or undesired neurological activity. However successful translation of KES nerve block to clinical applications is stymied by many unknowns such as the relevance of the onset response, acceptable levels of waveform contamination, and optimal electrode characteristics. We investigated the role of electrode geometric surface area on the KES nerve block threshold using 20 and 40 kHz current-controlled sinusoidal KES. Electrodes were electrochemically characterized and used to characterize typical KES waveforms and electrode charge characteristics. KES nerve block amplitudes, onset duration, and recovery of normal conduction after delivery of KES were evaluated along with power requirements for effective KES nerve block. Results from this investigation demonstrate that increasing electrode geometric surface area provides for a more power efficient KES nerve block. Reductions in block threshold by increased electrode surface area were found to be KESfrequency dependent, with block thresholds and average power consumption reduced by >2x with 20 kHz KES waveforms and >3x for 40 kHz KES waveforms.

  16. Permanent hydrophilization of outer and inner surfaces of polytetrafluoroethylene tubes using ambient air plasma generated by surface dielectric barrier discharges

    SciTech Connect

    Pavliňák, D.; Galmiz, O.; Zemánek, M.; Brablec, A.; Čech, J.; Černák, M.

    2014-10-13

    We present an atmospheric pressure ambient air plasma technique developed for technically simple treatment of inner and/or outer surfaces of plastic tubes and other hollow dielectric bodies. It is based on surface dielectric barrier discharge generating visually diffuse plasma layers along the treated dielectric surfaces using water-solution electrodes. The observed visual uniformity and measured plasma rotational and vibrational temperatures of 333 K and 2350 K indicate that the discharge can be readily applied to material surface treatment without significant thermal effect. This is exemplified by the obtained permanent surface hydrophilization of polytetrafluoroethylene tubes related to the replacement of a high fraction (more than 80%) of the surface fluorine determined by X-ray photoelectron spectroscopy. A tentative explanation of the discharge mechanism based on high-speed camera observations and the discharge current and voltage of measurements is outlined.

  17. Global trends of measured surface air temperature

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lebedeff, Sergej

    1987-01-01

    The paper presents the results of surface air temperature measurements from available meteorological stations for the period of 1880-1985. It is shown that the network of meteorological stations is sufficient to yield reliable long-term, decadal, and interannual temperature changes for both the Northern Hemisphere and the Southern Hemisphere, despite the fact that most stations are located on the continents. The results indicate a global warming of about 0.5-0.7 C in the past century, with warming of similar magnitude in both hemispheres. A strong warming trend between 1965 and 1980 raised the global mean temperature in 1980 and 1981 to the highest level in the period of instrumental records. Selected graphs of the temperature change in each of the eight latitude zones are included.

  18. Electrochemical decolorization of dye wastewater by surface-activated boron-doped nanocrystalline diamond electrode.

    PubMed

    Chen, Chienhung; Nurhayati, Ervin; Juang, Yaju; Huang, Chihpin

    2016-07-01

    Complex organics contained in dye wastewater are difficult to degrade and often require electrochemical advanced oxidation processes (EAOPs) to treat it. Surface activation of the electrode used in such treatment is an important factor determining the success of the process. The performance of boron-doped nanocrystalline diamond (BD-NCD) film electrode for decolorization of Acid Yellow (AY-36) azo dye with respect to the surface activation by electrochemical polarization was studied. Anodic polarization found to be more suitable as electrode pretreatment compared to cathodic one. After anodic polarization, the originally H-terminated surface of BD-NCD was changed into O-terminated, making it more hydrophilic. Due to the oxidation of surface functional groups and some portion of sp(2) carbon in the BD-NCD film during anodic polarization, the electrode was successfully being activated showing lower background current, wider potential window and considerably less surface activity compared to the non-polarized one. Consequently, electrooxidation (EO) capability of the anodically-polarized BD-NCD to degrade AY-36 dye was significantly enhanced, capable of nearly total decolorization and chemical oxygen demand (COD) removal even after several times of re-using. The BD-NCD film electrode favored acidic condition for the dye degradation; and the presence of chloride ion in the solution was found to be more advantageous than sulfate active species.

  19. Air Damping in a Fan-Shaped Rotational Resonator with Comb Electrodes

    NASA Astrophysics Data System (ADS)

    Uchida, Yuki; Sugano, Koji; Tsuchiya, Toshiyuki; Tabata, Osamu; Ikehara, Tsuyoshi

    We theoretically and experimentally evaluated the damping effect in a rotational resonator with a comb-drive actuator and sensor. The resonator was fabricated from an SOI wafer and has a fan-shaped mass. The underlying substrate was removed using back side deep reactive ion etching. One set of comb electrodes was attached to each side of the mass: one for electrostatic driving and the other for capacitive detection. In our theoretical analysis, the dynamics of the resonator were simplified so that they could be represented by a lumped system. In this lumped system, the damping coefficient was estimated by assuming the damping to be slide film damping and the air flow to be a Stokes flow. The phase shift due to the slide film damping of thick air layers was included in the lumped system. In the experimental evaluation, one side of the rotational combs was removed step-by-step and a half of the mass using a laser trimming tool so that the individual damping effects caused by the comb electrodes and mass could be determined quantitatively. We compared the experimental results with the results of the theoretical analysis and found that the difference in the damping coefficients between the experimental results and results of the theoretical analysis was less than 40%.

  20. Air support facilities. [interface between air and surface transportation systems

    NASA Technical Reports Server (NTRS)

    1975-01-01

    Airports are discussed in terms of the interface between the ground and air for transportation systems. The classification systems, design, facilities, administration, and operations of airports are described.

  1. New insights into the electrode mechanism of lithium sulfur batteries via air-free post-test analysis.

    PubMed

    Chen, Lin; Dietz Rago, Nancy L; Bloom, Ira D; Shaw, Leon L

    2016-08-02

    Effects of the volume expansion and shrinkage of Li2S cathodes on electrochemical cycle life are investigated via post-test analysis without exposure to air. The engineered electrodes that confine volume changes within micro-reactors have significantly longer life than the electrodes without the micro-reactor structure, providing the first unambiguous evidence of the importance of confining volume changes for improved battery performance.

  2. Photochemically controlled electrochemical deposition and dissolution of Ag0 nanoclusters on au electrode surfaces.

    PubMed

    Riskin, Michael; Katz, Eugenii; Gutkin, Vitaly; Willner, Itamar

    2006-12-05

    A photoisomerizable thiolated nitrospiropyran SP, (1a), monolayer is assembled on a Au electrode by the primary deposition of thiolated nitromerocyanine isomer 1b as a monolayer on the electrode, followed by the irradiation of the surface with visible light, lambda > 475 nm. The surface coverage of nitrospiropyran units (1a) on the electrode is 2 x 10-10 mole cm-2. Irradiation of the electrode with UV light, 320 nm < lambda < 360 nm, results in the nitromerocyanine, MR, monolayer on the electrode that binds Ag+ ions to the phenolate units. The Ag+ ions associated with the MR monolayer undergo cyclic reduction to surface-confined Ag0 nanoclusters, and reoxidation and dissolution of the Ag0 nanoclusters to Ag+ ions associated with the monolayer are demonstrated. The electron-transfer rate constants for the reduction of Ag+ to Ag0 and for the dissolution of Ag0 were determined by chronoamperometry and correspond to ketred = 12.7 s-1 and ketox = 10.5 s-1, respectively. The nanoclustering rate was characterized by surface plasmon resonance measurements, and it proceeds on a time scale of 10 min. The size of the Ag0 nanoclusters is in the range of 2 to 20 nm. The electrochemically induced reduction of the MR-Ag+ monolayer to the MR-Ag0 surface and the reoxidation of the MR-Ag0 surface control the hydrophilic-hydrophobic properties of the surface. The advancing contact angle of the MR-Ag0-functionalized surface is 59 degrees , and the contact angle of the MR-Ag+-monolayer-functionalized surface is 74 degrees . Photoisomerization of the Ag0-MR surface to the Ag0-SP state, followed by the oxidation of the Ag0 nanoclusters, results in the dissolution of the Ag+ ions into the electrolyte solution.

  3. Trends in Surface Temperature from AIRS.

    NASA Astrophysics Data System (ADS)

    Ruzmaikin, A.; Aumann, H. H.

    2014-12-01

    To address possible causes of the current hiatus in the Earth's global temperature we investigate the trends and variability in the surface temperature using retrievals obtained from the measurements by the Atmospheric Infrared Sounder (AIRS) and its companion instrument, the Advanced Microwave Sounding Unit (AMSU), onboard of Aqua spacecraft in 2002-2014. The data used are L3 monthly means on a 1x1degree spatial grid. We separate the land and ocean temperatures, as well as temperatures in Artic, Antarctic and desert regions. We find a monotonic positive trend for the land temperature but not for the ocean temperature. The difference in the regional trends can help to explain why the global surface temperature remains almost unchanged but the frequency of occurrence of the extreme events increases under rising anthropogenic forcing. The results are compared with the model studies. This work was supported by the Jet Propulsion Laboratory of the California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  4. Zinc/air battery R and D research and development of bifunctional oxygen electrode: Tasks I and II, Final report

    SciTech Connect

    Klein, M.; Viswanathan, S.

    1986-12-01

    Studies were conducted of the bifunctional oxygen electrode. The development of a rechargeable metal-oxygen (air) cell has been hampered to a great extent by the lack of a stable and cost effective oxygen electrode capable of use during both charge and discharge. The first type of bifunctional electrode consists of two distinct catalytifc layers. The oxygen reduction catalyst layer containing a supported gold catalyst is in contact with a hydrophilic nickel layer in which evolution of oxygen takes place. Loadings of gold from 0.5 to 1.0 mg/cm/sup 2/ were investigated; carbon, graphite, metal, and spinel oxides were evaluated as substrates. The second part of the research effort was centered on developing a reversible oxygen electrode containing only one catalytic layer for both reduction and evolution of oxygen. The work was directed specifically to the study of perovskite type of oxides with the composition AA/sup 1/BO/sub 3/ where A is an element of the lanthanide series, A/sup 1/ is an alkaline earth metal and B, a first row transition element. Initial polarization data obtained in unscrubbed air gave a value of approximately 200 millivolts vs Hg/HgO reference electrode at a current density of 50 ma/cm/sup 2/. Electrodes were made both by roll-bonding and by pelletizing techniques and tested for polarization and cycle life. This study also indicates the optimum process conditions for the manufacture of oxides and fabrication of electrodes.

  5. Three-Dimensional Adhesion Map Based on Surface and Interfacial Cutting Analysis System for Predicting Adhesion Properties of Composite Electrodes.

    PubMed

    Kim, Kyuman; Byun, Seoungwoo; Cho, Inseong; Ryou, Myung-Hyun; Lee, Yong Min

    2016-09-14

    Using a surface and interfacial cutting analysis system (SAICAS) that can measure the adhesion strength of a composite electrode at a specific depth from the surface, we can subdivide the adhesion strength of a composite electrode into two classes: (1) the adhesion strength between the Al current collector and the cathode composite electrode (FAl-Ca) and (2) the adhesion strength measured at the mid-depth of the cathode composite electrode (Fmid). Both adhesion strengths, FAl-Ca and Fmid, increase with increasing electrode density and loading level. From the SAICAS measurement, we obtain a mathematical equation that governs the adhesion strength of the composite electrodes. This equation revealed a maximum accuracy of 97.2% and 96.1% for FAl-Ca and Fmid, respectively, for four randomly chosen composite electrodes varying in electrode density and loading level.

  6. Low temperature formation of electrode having electrically conductive metal oxide surface

    DOEpatents

    Anders, Simone; Anders, Andre; Brown, Ian G.; McLarnon, Frank R.; Kong, Fanping

    1998-01-01

    A low temperature process is disclosed for forming metal suboxides on substrates by cathodic arc deposition by either controlling the pressure of the oxygen present in the deposition chamber, or by controlling the density of the metal flux, or by a combination of such adjustments, to thereby control the ratio of oxide to metal in the deposited metal suboxide coating. The density of the metal flux may, in turn, be adjusted by controlling the discharge current of the arc, by adjusting the pulse length (duration of on cycle) of the arc, and by adjusting the frequency of the arc, or any combination of these parameters. In a preferred embodiment, a low temperature process is disclosed for forming an electrically conductive metal suboxide, such as, for example, an electrically conductive suboxide of titanium, on an electrode surface, such as the surface of a nickel oxide electrode, by such cathodic arc deposition and control of the deposition parameters. In the preferred embodiment, the process results in a titanium suboxide-coated nickel oxide electrode exhibiting reduced parasitic evolution of oxygen during charging of a cell made using such an electrode as the positive electrode, as well as exhibiting high oxygen overpotential, resulting in suppression of oxygen evolution at the electrode at full charge of the cell.

  7. Synthesis, Structure and Reactivity of Molecules Attached to Electrode Surfaces.

    DTIC Science & Technology

    2014-09-26

    Among cations of the same charge, those least strongly hydrated and those of relatively small size predominated. At the cyanide -pretreated Pt(lll) surface...Ca , Ba +, LaJ+, Tetramethyl Ammonium, Choline and Acetylcholine Cations at Pt(ll1) Surfaces Containing an Ordered Layer of Cyanide , Stephen D

  8. On-Surface Cross Coupling Methods for the Construction of Modified Electrode Assemblies with Tailored Morphologies.

    PubMed

    Gietter, Amber A S; Pupillo, Rachel C; Yap, Glenn P A; Beebe, Thomas P; Rosenthal, Joel; Watson, Donald A

    2013-01-01

    Controlling the molecular topology of electrode-catalyst interfaces is a critical factor in engineering devices with specific electron transport kinetics and catalytic efficiencies. As such, the development of rational methods for the modular construction of tailorable electrode surfaces with robust molecular wires (MWs) exhibiting well-defined molecular topologies, conductivities and morphologies is critical to the evolution and implementation of electrochemical arrays for sensing and catalysis. In response to this need, we have established modular on-surface Sonogashira and Glaser cross-coupling processes to synthetically install arrays of ferrocene-capped MWs onto electrochemically functionalized surfaces. These methods are of comparable convenience and efficiency to more commonly employed Huisgen methods. Furthermore, unlike the Huisgen reaction, this new surface functionalization chemistry generates modified electrodes that do not contain unwanted ancillary metal binding sites, while allowing the bridge between the ferrocenyl moiety and electrode surface to be synthetically tailored. Electrochemical and surface analytical characterization of these platforms demonstrate that the linker topology and connectivity influences the ferrocene redox potential and the kinetics of charge transport at the interface.

  9. Generalized Butler-Volmer relation on a curved electrode surface under the action of stress

    NASA Astrophysics Data System (ADS)

    Yang, FuQian

    2016-11-01

    According to the principle of thermal activation process, the energy state of a material under the action of stress is a function of local stress. A generalized Butler-Volmer relationship for the electrode reaction on the surface of a curved electrode is derived, which takes account of the effects of local stress and the radius of mean curvature. From this relationship, the overpotential is found to be proportional to hydrostatic stress and the activation volume under the condition of open circuit. The conditions for the deposition of the material made solely from solute atoms and the formation of surface pits and porous structures are obtained, using the generalized Butler-Volmer relationship.

  10. Modification of the surface morphology of the silicon substrate for boron-doped diamond electrodes in electrochemical wastewater treatment applications

    NASA Astrophysics Data System (ADS)

    Bak, Ji-Yoon; Lee, Choong-Hyun; Kim, Jung-Do; Lim, Dae-Soon

    2016-01-01

    For electrochemical wastewater treatment applications, textured boron-doped diamond (BDD) electrodes were fabricated by using a simple and cost-effective etching process. On the basis of the surface area measurement, the etching time was optimized in order to achieve higher electrochemical wastewater treatment performance. The surface structure, electrochemical properties, and electrochemical oxidation performance of the electrodes were characterized by using Raman spectroscopy and atomic force microscopy, in addition to electrochemical techniques. The textured BDD electrode demonstrated a dense and large surface area with no change in the film's properties. The effective surface area of the textured BDD electrode was approximately twice as large as that of the planar BDD electrode. The electrochemical results clearly demonstrate that the enhanced surface area of the BDD electrode achieves a higher current efficiency and much lower energy consumption in the electrochemical oxidation of methyl-orange.

  11. Sequence and Temperature Influence on Kinetics of DNA Strand Displacement at Gold Electrode Surfaces.

    PubMed

    Biala, Katarzyna; Sedova, Ada; Flechsig, Gerd-Uwe

    2015-09-16

    Understanding complex contributions of surface environment to tethered nucleic acid sensing experiments has proven challenging, yet it is important because it is essential for interpretation and calibration of indispensable methods, such as microarrays. We investigate the effects of DNA sequence and solution temperature gradients on the kinetics of strand displacement at heated gold wire electrodes, and at gold disc electrodes in a heated solution. Addition of a terminal double mismatch (toehold) provides a reduction in strand displacement energy barriers sufficient to probe the secondary mechanisms involved in the hybridization process. In four different DNA capture probe sequences (relevant for the identification of genetically modified maize MON810), all but one revealed a high activation energy up to 200 kJ/mol during hybridization, that we attribute to displacement of protective strands by capture probes. Protective strands contain 4 to 5 mismatches to ease their displacement by the surface-confined probes at the gold electrodes. A low activation energy (30 kJ/mol) was observed for the sequence whose protective strand contained a toehold and one central mismatch, its kinetic curves displayed significantly different shapes, and we observed a reduced maximum signal intensity as compared to other sequences. These findings point to potential sequence-related contributions to oligonucleotide diffusion influencing kinetics. Additionally, for all sequences studied with heated wire electrodes, we observed a 23 K lower optimal hybridization temperature in comparison with disc electrodes in heated solution, and greatly reduced voltammetric signals after taking into account electrode surface area. We propose that thermodiffusion due to temperature gradients may influence both hybridization and strand displacement kinetics at heated microelectrodes, an explanation supported by computational fluid dynamics. DNA assays with surface-confined capture probes and temperature

  12. Investigation of ozone zero phenomenon using new electrode and surface analysis technique

    NASA Astrophysics Data System (ADS)

    Taguchi, M.; Ochiai, Y.; Kawagoe, R.; Kato, Y.; Teranishi, K.; Suzuki, S.; Itoh, H.

    2011-07-01

    Results of our experimental investigation on the ozone zero phenomenon suggested us the importance of the electrode surface condition. This means that the main cause of the phenomenon, that is, temporal decrease of ozone concentration at the outlet of DBD type ozone generator and the recovery characteristics from the phenomenon are considered as the surface reaction process, which are influenced strongly by the surface condition. The surface condition is never constant during the ozone generation and varies gradually or remarkably with time depending on the experimental conditions. Therefore we have been continued to make clear the cause of the phenomenon, for example, the reproducibility of the phenomenon, using new electrodes and together with the surface analysis technique etc. In this paper, we describe on the above results and discussion.

  13. Ethylenediamine-modified oriented MCM-41 at the electrode surface, cobalt adsorption ability and electrochemical performance.

    PubMed

    Rafiee, Mohammad; Karimi, Babak; Arshi, Simin; Vali, Hojatollah

    2014-03-28

    Mesoporous silica thin films (MCM-41) functionalized with ethylenediamine groups were electrochemically fabricated on electrode surfaces. These ligand functionalized film were a promising matrix for the immobilization of cobalt ions and preparation of cobalt complexes covalently bound to the MCM-41 support. The constructed MCM-41 were characterized by TEM, EDS and TGA analysis. This method yields uniform thin films with hexagonal mesochannels aligned and accessible to electrode surface. Well-defined electrode responses were, therefore, observed for the anchored complexes which made the electrochemical analysis of the structure possible as well. Voltammetric studies revealed the reactivity of the covalently bound complexes differed significantly from the dissolved ones. The anchored complexes preferred to be in their oxidized form which inhibits formation of oxygen adducts. The covalently bound complexes had relatively good leaching stability with good catalytic performance towards hydrogen peroxide reduction.

  14. Estimation of Surface Roughness due to Electrode Erosion in Field-Distortion Gas Switch

    NASA Astrophysics Data System (ADS)

    Liu, Xuandong; Wang, Hu; Li, Xiaoang; Zhang, Qiaogen; Wei, Jin; Qiu, Aici

    2013-08-01

    Field distortion gas switch is one of the crucial elements in a Marx generator, fast linear transformer driver and other pulsed power installations. The performance of the gas switch, which is dramatically affected by the surface roughness due to electrode erosion during the discharge process, directly influences the output parameters, stability and reliability of the pulsed power system. In this paper, an electrode surface roughness (ESR) calculation model has been established based on a great deal of experimental data under operating current. The discharge current waveform, the peak height of the burr, the radius and the depth of etch pits in the electrode erosion region were used to predict the ESR. Also, experimental results indicate that this calculation model can effectively estimate the ESR of the test gas switch.

  15. Glow Discharge Emission Spectra in Air with Liquid Electrode Based on Distilled Water

    NASA Astrophysics Data System (ADS)

    Chuchman, M. P.; Mesarosz, L. V.; Shuaibov, A. K.; Kiris, V. V.; Tarasenko, N. V.

    2016-11-01

    The results of spectroscopic studies of a glow discharge plasma at atmospheric pressure in air with an electrode based on distilled water are presented. The parametric effects affecting the discharge emission are analyzed. The dependence of the emission intensity of the various discharge components and their spatial localization in the discharge gap on the current strength is explained by change in the discharge geometry and the conditions of oxidation with increase of the current. It is shown that the composition of the gas mixture in the electrode gap changes with increase of the discharge current from nitrogen-rich (12-19 mA) to rich in water vapor and its dissociation products (19-24 mA). At higher currents, the gas mixture is also rich in the products of plasma chemical reactions and nitric oxide in particular. The redistribution of the radiation intensity of the molecules of nitrogen and its oxide with increase of the current occurs mainly in the cathode region (at the plasma-fluid boundary), where the formation of oxides is improved as a result of increase in the amount of vaporized solution and in the effectiveness of oxidation reactions with increase of the water temperature and discharge current.

  16. Performance and microbial ecology of air-cathode microbial fuel cells with layered electrode assemblies.

    PubMed

    Butler, Caitlyn S; Nerenberg, Robert

    2010-05-01

    Microbial fuel cells (MFCs) can be built with layered electrode assemblies, where the anode, proton exchange membrane (PEM), and cathode are pressed into a single unit. We studied the performance and microbial community structure of MFCs with layered assemblies, addressing the effect of materials and oxygen crossover on the community structure. Four MFCs with layered assemblies were constructed using Nafion or Ultrex PEMs and a plain carbon cloth electrode or a cathode with an oxygen-resistant polytetrafluoroethylene diffusion layer. The MFC with Nafion PEM and cathode diffusion layer achieved the highest power density, 381 mW/m(2) (20 W/m(3)). The rates of oxygen diffusion from cathode to anode were three times higher in the MFCs with plain cathodes compared to those with diffusion-layer cathodes. Microsensor studies revealed little accumulation of oxygen within the anode cloth. However, the abundance of bacteria known to use oxygen as an electron acceptor, but not known to have exoelectrogenic activity, was greater in MFCs with plain cathodes. The MFCs with diffusion-layer cathodes had high abundance of exoelectrogenic bacteria within the genus Geobacter. This work suggests that cathode materials can significantly influence oxygen crossover and the relative abundance of exoelectrogenic bacteria on the anode, while PEM materials have little influence on anode community structure. Our results show that oxygen crossover can significantly decrease the performance of air-cathode MFCs with layered assemblies, and therefore limiting crossover may be of particular importance for these types of MFCs.

  17. Magnetically Diffused Radial Electric-Arc Air Heater Employing Water-Cooled Copper Electrodes

    NASA Technical Reports Server (NTRS)

    Mayo, R. F.; Davis, D. D., Jr.

    1962-01-01

    A magnetically rotated electric-arc air heater has been developed that is novel in that an intense magnetic field of the order of 10,000 to 25,000 gauss is employed. This field is supplied by a coil that is connected in series with the arc. Experimentation with this heater has shown that the presence of an intense magnetic field transverse to the arc results in diffusion of the arc and that the arc has a positive effective resistance. With the field coil in series with the arc, highly stable arc operation is obtained from a battery power supply. External ballast is not required to stabilize the arc when it is operating at maximum power level. The electrode erosion rate is so low that the airstream contamination is no more than 0.07 percent and may be substantially less.

  18. 29 CFR 1926.1085 - Surface-supplied air diving.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Surface-supplied air diving. 1926.1085 Section 1926.1085 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION... Procedures § 1926.1085 Surface-supplied air diving. Note: The requirements applicable to construction...

  19. Uniform, large surface-area polarization by modifying corona-electrodes geometry.

    PubMed

    Tansel, T; Ener Rusen, S; Rusen, A

    2013-01-01

    We report on the uniform, large scale polarization of ferroelectric materials by a newly designed corona charging technique developing nonconventional electrodes geometry. The results of pyroelectric measurements represented the spatial homogeneity of the polarization attained through a surface area of ~25 cm(2).

  20. Surface oxide growth on platinum electrode in aqueous trifluoromethanesulfonic acid

    NASA Astrophysics Data System (ADS)

    Furuya, Yoshihisa; Mashio, Tetsuya; Ohma, Atsushi; Dale, Nilesh; Oshihara, Kenzo; Jerkiewicz, Gregory

    2014-10-01

    Platinum in the form of nanoparticles is the key and most expensive component of polymer electrolyte membrane fuel cells, while trifluoromethanesulfonic acid (CF3SO3H) is the smallest fluorinated sulfonic acid. Nafion, which acts as both electrolyte and separator in fuel cells, contains -CF2SO3H groups. Consequently, research on the electrochemical behaviour of Pt in aqueous CF3SO3H solutions creates important background knowledge that can benefit fuel cell development. In this contribution, Pt electro-oxidation is studied in 0.1 M aqueous CF3SO3H as a function of the polarization potential (Ep, 1.10 ≤ Ep ≤ 1.50 V), polarization time (tp, 100 ≤ tp ≤ 104 s), and temperature (T, 278 ≤ T ≤ 333 K). The critical thicknesses (X1), which determines the applicability of oxide growth theories, is determined and related to the oxide thickness (dox). Because X1 > dox for the entire range of Ep, tp, and T values, the formation of Pt surface oxide follows the interfacial place-exchange or the metal cation escape mechanism. The mechanism of Pt electro-oxidation is revised and expanded by taking into account possible interactions of cations, anions, and water molecules with Pt. A modified kinetic equation for the interfacial place exchange is proposed. The application of the interfacial place-exchange and metal cation escape mechanisms leads to an estimation of the Ptδ+-Oδ- surface dipole (μPtO), and the potential drop (Vox) and electric field (Eox) within the oxide. The Pt-anion interactions affect the oxidation kinetics by indirectly influencing the electric field within the double layer and the surface oxide.

  1. Fluorescence quenching studies of potential-dependent DNA reorientation dynamics at glassy carbon electrode surfaces.

    PubMed

    Li, Qin; Cui, Chenchen; Higgins, Daniel A; Li, Jun

    2012-09-05

    The potential-dependent reorientation dynamics of double-stranded DNA (ds-DNA) attached to planar glassy carbon electrode (GCE) surfaces were investigated. The orientation state of surface-bound ds-DNA was followed by monitoring the fluorescence from a 6-carboxyfluorescein (FAM6) fluorophore covalently linked to the distal end of the DNA. Positive potentials (i.e., +0.2 V vs open circuit potential, OCP) caused the ds-DNA to align parallel to the electrode surface, resulting in strong dipole-electrode quenching of FAM6 fluorescence. Switching of the GCE potential to negative values (i.e., -0.2 V vs OCP) caused the ds-DNA to reorient perpendicular to the electrode surface, with a concomitant increase in FAM6 fluorescence. In addition to the very fast (submilliseconds) dynamics of the initial reorientation process, slow (0.1-0.9 s) relaxation of FAM6 fluorescence to intermediate levels was also observed after potential switching. These dynamics have not been previously described in the literature. They are too slow to be explained by double layer charging, and chronoamperometry data showed no evidence of such effects. Both the amplitude and rate of the dynamics were found to depend upon buffer concentration, and ds-DNA length, demonstrating a dependence on the double layer field. The dynamics are concluded to arise from previously undetected complexities in the mechanism of potential-dependent ds-DNA reorientation. The possible origins of these dynamics are discussed. A better understanding of these dynamics will lead to improved models for potential-dependent ds-DNA reorientation at electrode surfaces and will facilitate the development of advanced electrochemical devices for detection of target DNAs.

  2. Performance of an electrochemical COD (chemical oxygen demand) sensor with an electrode-surface grinding unit.

    PubMed

    Geun Jeong, Bong; Min Yoon, Seok; Ho Choi, Chang; Koang Kwon, Kil; Sik Hyun, Moon; Heui Yi, Dong; Soo Park, Hyung; Kim, Mia; Joo Kim, Hyung

    2007-12-01

    An electrochemical COD (chemical oxygen demand) sensor using an electrode-surface grinding unit was investigated. The electrolyzing (oxidizing) action of copper on an organic species was used as the basis of the COD measuring sensor. Using a simple three-electrode cell and a surface grinding unit, the organic species is activated by the catalytic action of copper and oxidized at a working electrode, poised at a positive potential. When synthetic wastewater was fed into the system, the measured Coulombic yields were found to be dependent on the COD of the synthetic wastewater. A linear correlation between the Coulombic yields and the COD of the synthetic wastewater was established (10-1000 mg L(-1)) when the electrode-surface grinding procedure was activated briefly at 8 h intervals. When various kinds of wastewater samples obtained from various sewage treatment plants were measured, linear correlations (r(2)> or = 0.92) between the measured EOD (electrochemical oxygen demand) value and COD of the samples were observed. At a practical wastewater treatment plant, the measurement system was successfully operated with high accuracy and good stability over 3 months. These experimental results show that the application of the measurement system would be a rapid and practical method for the determination of COD in water industries.

  3. Metal-mesh based transparent electrode on a 3-D curved surface by electrohydrodynamic jet printing

    NASA Astrophysics Data System (ADS)

    Seong, Baekhoon; Yoo, Hyunwoong; Dat Nguyen, Vu; Jang, Yonghee; Ryu, Changkook; Byun, Doyoung

    2014-09-01

    Invisible Ag mesh transparent electrodes (TEs), with a width of 7 μm, were prepared on a curved glass surface by electrohydrodynamic (EHD) jet printing. With a 100 μm pitch, the EHD jet printed the Ag mesh on the convex glass which had a sheet resistance of 1.49 Ω/□. The printing speed was 30 cm s-1 using Ag ink, which had a 10 000 cPs viscosity and a 70 wt% Ag nanoparticle concentration. We further showed the performance of a 3-D transparent heater using the Ag mesh transparent electrode. The EHD jet printed an invisible Ag grid transparent electrode with good electrical and optical properties with promising applications on printed optoelectronic devices.

  4. Redox kinetics of adriamycin adsorbed on the surface of graphite and mercury electrodes.

    PubMed

    Komorsky-Lovrić, Sebojka

    2006-09-01

    Kinetics of the surface redox reactions of adriamycin (doxorubicin hydrochloride) adsorbed on paraffin-impregnated graphite electrode (PIGE) and on mercury electrode is measured by square-wave voltammetry. In 0.9 mol/L KNO3 buffered to pH 4.65, the standard electrode reaction rate constants of the first quinone/hydroquinone redox couple (see Scheme 2) on PIGE and mercury are k(s1)=49+/-12 s(-1) and k(s1)=147+/-36 s(-1), respectively. Under the same conditions, the standard rate constant of the second redox couple on the PIGE is smaller than 4 s(-1) and the electron transfer coefficient of the reduction is alpha2=0.35.

  5. Estimation of Surface Air Temperature from MODIS 1km Resolution Land Surface Temperature Over Northern China

    NASA Technical Reports Server (NTRS)

    Shen, Suhung; Leptoukh, Gregory G.; Gerasimov, Irina

    2010-01-01

    Surface air temperature is a critical variable to describe the energy and water cycle of the Earth-atmosphere system and is a key input element for hydrology and land surface models. It is a very important variable in agricultural applications and climate change studies. This is a preliminary study to examine statistical relationships between ground meteorological station measured surface daily maximum/minimum air temperature and satellite remotely sensed land surface temperature from MODIS over the dry and semiarid regions of northern China. Studies were conducted for both MODIS-Terra and MODIS-Aqua by using year 2009 data. Results indicate that the relationships between surface air temperature and remotely sensed land surface temperature are statistically significant. The relationships between the maximum air temperature and daytime land surface temperature depends significantly on land surface types and vegetation index, but the minimum air temperature and nighttime land surface temperature has little dependence on the surface conditions. Based on linear regression relationship between surface air temperature and MODIS land surface temperature, surface maximum and minimum air temperatures are estimated from 1km MODIS land surface temperature under clear sky conditions. The statistical errors (sigma) of the estimated daily maximum (minimum) air temperature is about 3.8 C(3.7 C).

  6. Surface structured platinum electrodes for the electrochemical reduction of carbon dioxide in imidazolium based ionic liquids.

    PubMed

    Hanc-Scherer, Florin A; Montiel, Miguel A; Montiel, Vicente; Herrero, Enrique; Sánchez-Sánchez, Carlos M

    2015-10-07

    The direct CO2 electrochemical reduction on model platinum single crystal electrodes Pt(hkl) is studied in [C2mim(+)][NTf2(-)], a suitable room temperature ionic liquid (RTIL) medium due to its moderate viscosity, high CO2 solubility and conductivity. Single crystal electrodes represent the most convenient type of surface structured electrodes for studying the impact of RTIL ion adsorption on relevant electrocatalytic reactions, such as surface sensitive electrochemical CO2 reduction. We propose here based on cyclic voltammetry and in situ electrolysis measurements, for the first time, the formation of a stable adduct [C2mimH-CO2(-)] by a radical-radical coupling after the simultaneous reduction of CO2 and [C2mim(+)]. It means between the CO2 radical anion and the radical formed from the reduction of the cation [C2mim(+)] before forming the corresponding electrogenerated carbene. This is confirmed by the voltammetric study of a model imidazolium-2-carboxylate compound formed following the carbene pathway. The formation of that stable adduct [C2mimH-CO2(-)] blocks CO2 reduction after a single electron transfer and inhibits CO2 and imidazolium dimerization reactions. However, the electrochemical reduction of CO2 under those conditions provokes the electrochemical cathodic degradation of the imidazolium based RTIL. This important limitation in CO2 recycling by direct electrochemical reduction is overcome by adding a strong acid, [H(+)][NTf2(-)], into solution. Then, protons become preferentially adsorbed on the electrode surface by displacing the imidazolium cations and inhibiting their electrochemical reduction. This fact allows the surface sensitive electro-synthesis of HCOOH from CO2 reduction in [C2mim(+)][NTf2(-)], with Pt(110) being the most active electrode studied.

  7. High surface area electrode materials by direct metallization of porous substrates

    SciTech Connect

    Chyan, O.; Chen, J.J.; Liu, M.; Richmond, M.G.; Yang, K.

    1995-12-31

    Recent advances in high surface area (HSA) electrode materials have played an important role in the development of high-performance batteries and fuel cells. HSA electrodes can significantly increase the power-density of batteries and fuel cells by enhancing the heterogeneous electrochemical reaction rate and concurrently reducing battery and fuel cell size and weight. The compactness of HSA electrodes can also reduce the ohmic potential drop, which has the clear advantage of reducing power losses. This paper reports results on utilizing direct metallization of porous substrates to prepare new HSA electrode materials. Specifically, Nickel HSA electrode materials, relevant to the Ni-Cd and metal-hydride rechargeable batteries, were prepared on porous carbon substrates by direct thermolysis of organometallic precursors and/or electroless Ni plating. SEM and XPS characterization results indicate a Ni metallic film was conformally coated over the porous carbon skeleton. The real electroactive areas were determined electrochemically in NaOH solution and results will be discussed in correlation with the metallization conditions.

  8. Comparison of the surface dielectric barrier discharge characteristics under different electrode gaps

    NASA Astrophysics Data System (ADS)

    Gao, Guoqiang; Dong, Lei; Peng, Kaisheng; Wei, Wenfu; Li, Chunmao; Wu, Guangning

    2017-01-01

    Currently, great interests are paid to the surface dielectric barrier discharge due to the diverse and interesting application. In this paper, the influences of the electrode gap on the discharge characteristics have been studied. Aspects of the electrical parameters, the optical emission, and the discharge induced gas flow were considered. The electrode gap varied from 0 mm to 21 mm, while the applied AC voltage was studied in the range of 17 kV-27 kV. Results indicate that with the increase of the electrode gap, the variation of discharge voltage exhibits an increasing trend, while the other parameters (i.e., the current, power, and induced flow velocity) increase first, and then decrease once the gap exceeded the critical value. Mechanisms of the electrode gap influencing these key parameters were discussed from the point of equivalent circuit. The experimental results reveal that an optimal discharge gap can be obtained, which is closely related to the applied voltage. Visualization of the induced flow with different electrode gaps was realized by the Schlieren diagnostic technique. Finally, the velocities of induced gas flow determined by the pitot tube were compared with the results of intensity-integral method, and good agreements were found.

  9. Numerical Study of Ram Air Airfoils and Upper Surface Bleed-Air Control

    DTIC Science & Technology

    2014-06-16

    of ram -air parachute systems to complement the design and analysis of new and existing airdrop systems. In this paper an unsteady numerical study of...two-dimensional, rigid, ram -air sections with an array of upper surface bleed-air actuators is presented. Aerodynamic forces and lift-to-drag ratios of...a modified Clark-Y ram -air airfoil are calculated from unsteady Reynolds-Averaged Navier-Stokes (RANS) simulations, using the Kestrel and Cobalt flow

  10. Silver-Copper Nanoalloy Catalyst Layer for Bifunctional Air Electrodes in Alkaline Media.

    PubMed

    Wu, Xiaoqiang; Chen, Fuyi; Jin, Yachao; Zhang, Nan; Johnston, Roy L

    2015-08-19

    A carbon-free and binder-free catalyst layer composed of a Ag-Cu nanoalloy on Ni foam was used as the air cathode in a zinc-air battery for the first time. The Ag-Cu catalyst was prepared using pulsed laser deposition. The structures of the catalysts were found to consist of crystalline Ag-Cu nanoalloy particles with an average size of 2.58 nm embedded in amorphous Cu films. As observed in the X-ray photoelectron spectra, the Ag 3d core levels shifted to higher binding energies, whereas the Cu 2p core levels shifted to lower binding energies, indicating alloying of the silver and copper. Rotating disk electrode measurements indicated that the oxygen reduction reaction (ORR) proceeded through a four-electron pathway on the Ag50Cu50 and Ag90Cu10 nanoalloy catalysts in alkaline solution. Moreover, the catalytic activity of Ag50Cu50 in the ORR is more efficient than that of Ag90Cu10. By performing charge and discharge cycling measurements, the Ag50Cu50 catalyst layer was confirmed to have a maximum power density of approximately 86.3 mW cm(-2) and an acceptable cell voltage at 0.863 V for current densities up to 100 mA cm(-2) in primary zinc-air batteries. In addition, a round-trip efficiency of approximately 50% at a current density of 20 mA cm(-2) was also obtained in the test.

  11. Electrochemical properties of lithium air batteries with Pt100-xRux (0 ≤ x ≤ 100) electrocatalysts for air electrodes

    NASA Astrophysics Data System (ADS)

    Yui, Yuhki; Sakamoto, Shuhei; Nohara, Masaya; Hayashi, Masahiko; Nakamura, Jiro; Komatsu, Takeshi

    2017-02-01

    Electrochemical properties of lithium air secondary battery cells with Pt100-xRux (0 ≤ x ≤ 100) electrocatalysts, prepared by the formic acid reduction method and loaded into air electrodes were examined in 1 mol/l LiTFSA/TEGDME electrolyte solution. Among the cells, the one with the Pt10Ru90 (x = 90)/carbon sample showed the largest discharge capacity of 1014 mAh/g and the lowest average charge voltage of 3.74 V. In addition, the x = 90 sample showed comparatively good cycle stability with discharge capacity of over 800 mAh/g at the 8th cycle. As a result, x = 90 was confirmed to be the optimized composition as the electrocatalyst for the air electrode.

  12. Diamond detectors with laser induced surface graphite electrodes

    NASA Astrophysics Data System (ADS)

    Komlenok, M.; Bolshakov, A.; Ralchenko, V.; Konov, V.; Conte, G.; Girolami, M.; Oliva, P.; Salvatori, S.

    2016-11-01

    We report on the response of metal-less CVD polycrystalline-diamond pixel sensors under β-particles irradiation. A 21×21 array of 0.18×0.18 mm2 pixels was realized on one side of a 10.0×10.0×0.5 mm3 polycrystalline diamond substrate by means of laser induced surface graphitization. With the same technique, a large graphite contact, used for detector biasing, was fabricated on the opposite side. A coincidence detecting method was used with two other reference polycrystalline diamond detectors for triggering, instead of commonly used scintillators, positioned in the front and on the back of the sensor-array with respect to the impinging particles trajectory. The collected charge distribution at each pixel was analyzed as a function of the applied bias. No change in the pulse height distribution was recorded by inverting the bias voltage polarity, denoting contacts ohmicity and symmetry. A fairly good pixel response uniformity was obtained: the collected charge most probable value saturates for all the pixels at an electric field strength of about ±0.6 V/μm. Under saturation condition, the average collected charge was equal to =1.64±0.02 fC, implying a charge collection distance of about 285 μm. A similar result, within 2%, was also obtained for 400 MeV electrons at beam test facility at INFN Frascati National Laboratory. Experimental results highlighted that more than 84% of impinging particles involved only one pixel, with no significant observed cross-talk effects.

  13. Stabilisation of liquid-air surfaces by particles of low surface energy.

    PubMed

    Binks, Bernard P; Rocher, Anaïs

    2010-08-28

    We describe the stabilisation of liquid-air surfaces by microparticles of a low surface energy solid. By varying the surface tension of the liquid, various particle-stabilised materials from oil dispersions to air-in-oil foams to dry water can be prepared.

  14. Surface EMG-recordings using a miniaturised matrix electrode: a new technique for small animals.

    PubMed

    Biedermann, F; Schumann, N P; Fischer, M S; Scholle, H C

    2000-04-01

    A new method for multichannel surface-EMG measurements in small animals is presented. The underlying scientific aim is the characterisation of the spreading and the co-ordination of skeletal muscle activation between different muscles or muscle parts, depending on various motor tasks. The myoelectrical signals were recorded monopolarly by a 16-channel matrix electrode on the muscle surface directly under the skin on the fascia of the investigated muscle, without damaging the muscle. Surface-EMG's were recorded for at least 5 days after surgery without electrical interferences. During defined motor tasks, the projection of the myoelectrical activation of the different parts of the M. triceps brachii of rats (Rattus norvegicus), pikas (Ochotona rufescens) and cuis (Galea musteloides) or the M. anconeus of toads (Bufo marinus) on the muscle surface was mapped. The locomotion of the investigated animals was monitored by a three-dimensional kinematic analysis (video and/or high-speed cineradiography). There was no perceptible influence from application of EMG matrix electrode. The miniaturised matrix electrode seemed practicable in gaining insight into changes in myoelectrical activation patterns (EMG mapping). This allows a characterisation of the intramuscular co-ordination processes corresponding to the actual morphofunctional state of the investigated animals.

  15. Conditions for the formation of nanostructures on electrode surfaces during atomic scale scratching

    NASA Astrophysics Data System (ADS)

    Nielinger, Michael; Berenz, Peter; Xiao, Xiaoyin; Baltruschat, Helmut

    2005-12-01

    A nanoscale place selective electrochemical deposition of foreign metals on different single crystal electrodes induced by a scanning tunnelling microscope (STM) tip was achieved by scanning with the STM tip very closely to an electrode surface which is covered by a monolayer of a foreign metal by underpotential deposition (UPD). Measuring the minimal conductance G, which is necessary for generating nanostructures, shows that a point contact between the STM tip and the UPD covered surface is formed. This is considered to be responsible for the tip-induced deposition. On Au(1 1 1) in Cu 2+ containing solutions at potentials positive of submonolayer formation, nanoscale scratches are achieved in this way, whereas in the absence of any foreign metal ions only large defects are introduced under the same conditions.

  16. The effect of surface and internal electrodes on the gait of children with cerebral palsy, spastic diplegic type.

    PubMed

    Young, C C; Rose, S E; Biden, E N; Wyatt, M P; Sutherland, D H

    1989-01-01

    The purpose of this study was to determine whether surface and internal fine-wire electromyography electrodes had an effect on gait. The subjects for the experiments were 38 children with the spastic diplegic type of cerebral palsy. The children were filmed using the high-speed cinematographic technique while they walked (a) with no electrodes (unencumbered), (b) with only surface electrodes, and (c) with internal electrodes. Single stance time, step length, cadence, and walking velocity were compared with analysis of variance and Bonferroni t tests. The results included a significant decrease in cadence (-6.3% of unencumbered walking; p less than 0.05) when comparing walking with surface electrodes with walking without any electrodes. The internal electrodes caused significant decreases from normal walking in the following parameters: step length for both the measured leg (-18.6%; p less than 0.005) and the nonmeasured leg (-18.0%; p less than 0.005), cadence (-7.9%; p less than 0.02), and walking velocity (-23.5%; p less than 0.005). Internal electrodes caused significant decreases as compared with surface electrodes in the step length for both the measured leg (15.7%; p less than 0.01) and the nonmeasured leg (15.6%; p less than 0.005) and walking velocity (19.7%; p less than 0.005). Single stance phase did not change significantly in any of the comparisons. It appears that the addition of the surface electrode apparatus does change the normal gait of a subject, causing a large decrease in cadence. The measurement of gait with internal electrodes causes further change in gait, resulting in large decreases in step length and walking velocity.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. Method and Apparatus for Measuring Surface Air Pressure

    NASA Technical Reports Server (NTRS)

    Lin, Bing (Inventor); Hu, Yongxiang (Inventor)

    2014-01-01

    The present invention is directed to an apparatus and method for remotely measuring surface air pressure. In one embodiment, the method of the present invention utilizes the steps of transmitting a signal having multiple frequencies into the atmosphere, measuring the transmitted/reflected signal to determine the relative received power level of each frequency and then determining the surface air pressure based upon the attenuation of the transmitted frequencies.

  18. Surface-enhanced resonance Raman study of the photoreduction of methylviologen on a p-InP semiconductor electrode

    SciTech Connect

    Feng, Q.; Cotton, T.M.

    1986-03-13

    The redox reactions of methylviologen (MV) at a silver electrode and at a p-InP electrode have been studied by cyclic voltammetry and Raman spectroscopy. By deposition of a silver island overlayer onto a p-InP semiconductor electrode the surface enhancement effect was obtained, allowing the MV reduction products formed at the semiconductor electrode to be monitored in situ. The photovoltaic response on p-InP electrode was not perturbed by the presence of the silver overlayer. Surface-enhanced resonance Raman (SERR) spectroscopy has verified the adsorption of the products from the reduction reactions MV/sup 2 +/ + e/sup -/ ..-->.. MV/sup +/. and MV/sup +/. + e/sup -/ ..-->.. MV/sup 0/. The Raman spectrum of one-electron and two-electron (MV/sup 0/) reduced methylviologen was obtained by exhaustive electrolysis in acetonitrile solution to provide an assignment of the surface spectra. 31 references, 4 figures.

  19. In situ Raman spectroscopy of lithium electrode surface in ambient temperature lithium secondary battery. Final report

    SciTech Connect

    Tachikawa, Hiroyasu

    1992-09-01

    Raman spectroscopy was used to characterize surface layers on lithium electrodes in different solvents such as propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and polyethylene glycol 400 dimethyl ether (PEG400DME). Both DMC and DEC were used singly, and also mixed with either methyl acetate (MA) or methyl formate (MF). The Raman spectra showed that passive films formed on the Li surface in different solvents may have different chemical structures, which changed during the charging and discharging processes. Raman spectroscopy was also applied to characterize zinc electrode surfaces in alkaline solutions. The results suggested that ZnO and Zn(OH){sub 2} formed on the Zn electrode when a passive potential was applied. A solid film of fullerene C{sub 60}, which could be used as a cathode in Li rechargeable batteries, was examined in the PEG400DME solution by both electrochemical and Raman spectroscopy. Cyclic voltammograms (CVs) showed five redox peaks which suggested the formation of C{sub 60}{sup {minus}}, C{sub 60}{sup 2{minus}}, C{sub 60}{sup 3{minus}}, C{sub 60}{sup 4{minus}}, and C{sub 60}{sup 5{minus}}. Raman spectra obtained from a thin C{sub 60} film indicated that the thin fulleride film dissolved in the PEG400DME/LiClO{sub 4} solution at negative potentials.

  20. Use of Surface Enhanced Blocking (SEB) Electrodes for Microbial Cell Lysis in Flow-Through Devices

    PubMed Central

    Talebpour, Abdossamad; Maaskant, Robert; Khine, Aye Aye; Alavie, Tino

    2014-01-01

    By simultaneously subjecting microbial cells to high amplitude pulsed electric fields and flash heating of the cell suspension fluid, effective release of intracellular contents was achieved. The synergistic effect of the applied electric field and elevated temperature on cell lysis in a flow-through device was demonstrated for Gram-negative and Gram-positive bacteria, and Mycobacterium species. The resulting lysate is suitable for downstream nucleic acid amplification and detection without requiring further preparation. The lysis chamber employs surface enhanced blocking electrodes which possess an etched micro-structured surface and a thin layer of dielectric metal oxide which provides a large effective area and blocks transmission of electrical current. The surface enhanced blocking electrodes enable simultaneous suppression of the rapid onset of electric field screening in the bulk of the cell suspension medium and avoidance of undesired electrochemical processes at the electrode-electrolyte interface. In addition the blocking layer ensures the robustness of the cell lysis device in applications involving prolonged flow-through processing of the microbial cells. PMID:25033080

  1. Electrochemical behavior of a typical redox mediator on a modified electrode surface: Experiment and computer simulations

    NASA Astrophysics Data System (ADS)

    Gavilán Arriazu, E. M.; Paz Zanini, Verónica I.; Gulotta, Florencia A.; Araujo, Virginia M.; Pinto, O. A.

    2017-04-01

    This paper describes the study of a redox species electrosorption on a modified electrode by experimental measurements and computer simulation. The propose model is based on the fact that charges are transferred to the electrode when an electroactive species is adsorbed on its surface. The electrode surface is modified by the irreversible adsorption of a non-electroactive species, which blocks a percentage of the adsorption sites. Hence, the electroactive species can only be adsorbed on the surface vacancies, and, when this phenomenon occurs, interact laterally with the non-electroactive one. Lattice-gas models and Monte Carlo simulations in the Gran Canonical Ensemble are used. The analysis conducted is based on the study of adsorption isotherms and voltammograms, for several values of energies and adsorption degrees of the non-electroactive species. In the case of experimental measurements, an artificial clay (Laponite®) represents the non-electroactive species while the redox probe Fe(CN)64- is the electroactive one. The results obtained by the proposed model are compared with experimental voltammograms.

  2. The Impact of Surface Chemistry on Bio-derived Carbon Performance as Supercapacitor Electrodes

    NASA Astrophysics Data System (ADS)

    Alshareef, Niman H.; Whitehair, Daniel; Xia, Chuan

    2016-12-01

    In this study, we demonstrate that highly functionalized and porous carbons can be derived from palm-leaf waste using the template-free facile synthesis process. The derived carbons have high content of nitrogen dopant, high surface area, and various defects. Moreover, these carbons exhibit a high electrical conductivity (107 S m-1). Thanks to the high content of edge N (64.3%) and highly microporous nature (82% of microspores), these biomass-derived carbons show promising performance when used as supercapacitor electrodes. To be specific, these carbonaceous materials show a specific capacitance as high as 197 and 135 F g-1 at 2 and 20 A g-1 in three-electrode configuration, respectively. Furthermore, the symmetrical cells using palm-leaf-derived carbon show an energy density of 8.4 Wh Kg-1 at a power density of 0.64 kW Kg-1, with high cycling life stability (˜8% loss after 10,000 continuous charge-discharge cycles at 20 A g-1). Interestingly, as the power density increases from 4.4 kW kg-1 to 36.8 kW kg-1, the energy density drops slowly from 8.4 Wh kg-1 to 3.4 Wh kg-1. Getting such extremely high power density without significant loss of energy density indicates that these palm-leaf-derived carbons have excellent electrode performance as supercapacitor electrodes.

  3. The Impact of Surface Chemistry on Bio-derived Carbon Performance as Supercapacitor Electrodes

    NASA Astrophysics Data System (ADS)

    Alshareef, Niman H.; Whitehair, Daniel; Xia, Chuan

    2017-03-01

    In this study, we demonstrate that highly functionalized and porous carbons can be derived from palm-leaf waste using the template-free facile synthesis process. The derived carbons have high content of nitrogen dopant, high surface area, and various defects. Moreover, these carbons exhibit a high electrical conductivity (107 S m-1). Thanks to the high content of edge N (64.3%) and highly microporous nature (82% of microspores), these biomass-derived carbons show promising performance when used as supercapacitor electrodes. To be specific, these carbonaceous materials show a specific capacitance as high as 197 and 135 F g-1 at 2 and 20 A g-1 in three-electrode configuration, respectively. Furthermore, the symmetrical cells using palm-leaf-derived carbon show an energy density of 8.4 Wh Kg-1 at a power density of 0.64 kW Kg-1, with high cycling life stability (˜8% loss after 10,000 continuous charge-discharge cycles at 20 A g-1). Interestingly, as the power density increases from 4.4 kW kg-1 to 36.8 kW kg-1, the energy density drops slowly from 8.4 Wh kg-1 to 3.4 Wh kg-1. Getting such extremely high power density without significant loss of energy density indicates that these palm-leaf-derived carbons have excellent electrode performance as supercapacitor electrodes.

  4. AIRS Sea Surface Temperature and Pacific Decadal Oscillation

    NASA Astrophysics Data System (ADS)

    Chen, L. L.

    2015-12-01

    Atmospheric Infrared Sounder (AIRS) has been providing necessary measurements for long term atmospheric and surface processes aboard NASA' s Aqua polar orbiter since May 2002. Here, we use time series of AIRS sea surface temperature (SST) anomalies to show the time evolution of Pacific Decadal Oscillation (PDO) in the Gulf of Alaska (lon:-144.5, lat:54.5) from 2003 to 2014. PDO is connected to the first mode of North Pacific SST variability and is tele-connected to ENSO in the tropics. Further analysis of AIRS data can provide clarification of Pacific climate variability.

  5. Role of Surface Characteristics in Urban Meteorology and Air Quality

    NASA Astrophysics Data System (ADS)

    Sailor, David Jean

    Urbanization results in a landscape with significantly modified surface characteristics. The lower values of reflectivity to solar radiation, surface moisture availability, and vegetative cover, along with the higher values of anthropogenic heat release and surface roughness combine to result in higher air temperatures in urban areas relative to their rural counterparts. Through their role in the surface energy balance and surface exchange processes, these surface characteristics are capable of modifying the local meteorology. The impacts on wind speeds, air temperatures, and mixing heights are of particular importance, as they have significant implications in terms of urban energy use and air quality. This research presents several major improvements to the meteorological modeling methodology for highly heterogeneous terrain. A land-use data base is implemented to provide accurate specification of surface characteristic variability in simulations of the Los Angeles Basin. Several vegetation parameterizations are developed and implemented, and a method for including anthropogenic heat release into the model physics is presented. These modeling advancements are then used in a series of three-dimensional simulations which were developed to investigate the potential meteorological impact of several mitigation strategies. Results indicate that application of moderate tree-planting and urban-lightening programs in Los Angeles may produce summertime air temperature reductions on the order of 4^circ C with a concomitant reduction in air pollution. The analysis also reveals several mechanisms whereby the application of these mitigation strategies may potentially increase pollutant concentrations. The pollution and energy use consequences are discussed in detail.

  6. Role of surface characteristics in urban meteorology and air quality

    SciTech Connect

    Sailor, David Jean

    1993-08-01

    Urbanization results in a landscape with significantly modified surface characteristics. The lower values of reflectivity to solar radiation, surface moisture availability, and vegetative cover, along with the higher values of anthropogenic heat release and surface roughness combine to result higher air temperatures in urban areas relative to their rural counterparts. Through their role in the surface energy balance and surface exchange processes, these surface characteristics are capable of modifying the local meteorology. The impacts on wind speeds, air temperatures, and mixing heights are of particular importance, as they have significant implications in terms of urban energy use and air quality. This research presents several major improvements to the meteorological modeling methodology for highly heterogeneous terrain. A land-use data-base is implemented to provide accurate specification of surface characteristic variability in simulations of the Los Angeles Basin. Several vegetation parameterizations are developed and implemented, and a method for including anthropogenic heat release into the model physics is presented. These modeling advancements are then used in a series of three-dimensional simulations which were developed to investigate the potential meteorological impact of several mitigation strategies. Results indicate that application of moderate tree-planting and urban-lightening programs in Los Angeles may produce summertime air temperature reductions on the order of 4°C with a concomitant reduction in air pollution. The analysis also reveals several mechanisms whereby the application of these mitigation strategies may potentially increase pollutant concentrations. The pollution and energy use consequences are discussed in detail.

  7. Study on electrical characteristics of barrier-free atmospheric air diffuse discharge generated by nanosecond pulses and long wire electrodes

    SciTech Connect

    Li, Lee Liu, Yun-Long; Teng, Yun; Liu, Lun; Pan, Yuan

    2014-07-15

    In room-temperature atmospheric air, the large-scale diffuse plasmas can be generated via high-voltage nanosecond pulses with short rise-time and wire electrodes. Diffuse discharge with the wire electrode length up to 110.0 cm and the discharge spacing of several centimeters has been investigated in this paper. Electrical characteristics of diffuse discharge have been analyzed by their optical photographs and measuring of the voltage and current waveforms. Experimental results show the electrode spacing, and the length of wire electrodes can influence the intensity and mode transition of diffuse discharge. The characteristic of current waveforms is that there are several current oscillation peaks at the time of applied pulsed voltage peak, and at the tail of applied pulse, the conduction current component will compensate the displacement one so that the measured current is unidirectional in diffuse discharge mode. The transition from diffuse discharge to arc discharge is always with the increasing of conduction current density. As for nanosecond pulses with long tail, the long wire electrodes are help for generating non-equilibrium diffuse plasmas.

  8. Microelectrode arrays: a general strategy for using oxidation reactions to site selectively modify electrode surfaces.

    PubMed

    Nguyen, Bichlien H; Kesselring, David; Tesfu, Eden; Moeller, Kevin D

    2014-03-04

    Oxidation reactions are powerful tools for synthesis because they allow for the functionalization of molecules. Here, we present a general method for conducting these reactions on a microelectrode array in a site-selective fashion. The reactions are run as a competition between generation of a chemical oxidant at the electrodes in the array and reduction of the oxidant by a "confining agent" in the solution above the array. The "confining agent" does not need to be more reactive than the substrate fixed to the surface of the array. In many cases, the same substrate placed on the surface of the array can also be used in solution as the confining agent.

  9. Studying the glial cell response to biomaterials and surface topography for improving the neural electrode interface

    NASA Astrophysics Data System (ADS)

    Ereifej, Evon S.

    Neural electrode devices hold great promise to help people with the restoration of lost functions, however, research is lacking in the biomaterial design of a stable, long-term device. Current devices lack long term functionality, most have been found unable to record neural activity within weeks after implantation due to the development of glial scar tissue (Polikov et al., 2006; Zhong and Bellamkonda, 2008). The long-term effect of chronically implanted electrodes is the formation of a glial scar made up of reactive astrocytes and the matrix proteins they generate (Polikov et al., 2005; Seil and Webster, 2008). Scarring is initiated when a device is inserted into brain tissue and is associated with an inflammatory response. Activated astrocytes are hypertrophic, hyperplastic, have an upregulation of intermediate filaments GFAP and vimentin expression, and filament formation (Buffo et al., 2010; Gervasi et al., 2008). Current approaches towards inhibiting the initiation of glial scarring range from altering the geometry, roughness, size, shape and materials of the device (Grill et al., 2009; Kotov et al., 2009; Kotzar et al., 2002; Szarowski et al., 2003). Literature has shown that surface topography modifications can alter cell alignment, adhesion, proliferation, migration, and gene expression (Agnew et al., 1983; Cogan et al., 2005; Cogan et al., 2006; Merrill et al., 2005). Thus, the goals of the presented work are to study the cellular response to biomaterials used in neural electrode fabrication and assess surface topography effects on minimizing astrogliosis. Initially, to examine astrocyte response to various materials used in neural electrode fabrication, astrocytes were cultured on platinum, silicon, PMMA, and SU-8 surfaces, with polystyrene as the control surface. Cell proliferation, viability, morphology and gene expression was measured for seven days in vitro. Results determined the cellular characteristics, reactions and growth rates of astrocytes

  10. Electrical Characteristics, Electrode Sheath and Contamination Layer Behavior of a Meso-Scale Premixed Methane-Air Flame Under AC/DC Electric Fields

    NASA Astrophysics Data System (ADS)

    Chen, Qi; Yan, Limin; Zhang, Hao; Li, Guoxiu

    2016-05-01

    Electrical characteristics of a nozzle-attached meso-scale premixed methane-air flame under low-frequency AC (0-4300 V, 0-500 Hz) and DC (0-3300 V) electric fields were studied. I-V curves were measured under different experimental conditions to estimate the magnitude of the total current 100-102 μA, the electron density 1015-1016 m-3 and further the power dissipation ≤ 0.7 W in the reaction zone. At the same time, the meso-scale premixed flame conductivity 10-4-10-3 Ω-1·m-1 as a function of voltage and frequency was experimentally obtained and was believed to represent a useful order-of magnitude estimate. Moreover, the influence of the collision sheath relating to Debye length (31-98 μm) and the contamination layer of an active electrode on measurements was discussed, based on the combination of simulation and theoretical analysis. As a result, the electrode sheath dimension was evaluated to less than 0.5 mm, which indicated a complex effect of the collision sheath on the current measurements. The surface contamination effect of an active electrode was further analyzed using the SEM imaging method, which showed elements immigration during the contamination layer formation process. supported by National Natural Science Foundation of China (No. 51376021), and the Fundamental Research Fund for Major Universities (No. 2013JBM079)

  11. Conducting elastomer surface texturing: a path to electrode spotting. Application to the biochip production.

    PubMed

    Marquette, Christophe A; Blum, Loïc J

    2004-09-15

    A new active support for electro-chemiluminescent biochip preparation has been developed. This material was based on an original material composed of graphite modified polydimethyl siloxane (PDMS). The addressed inclusion of Sepharose beads at the surface of this elastomeric electrode generated interesting local high specific surface. The electrode was characterised by electrochemical (cyclic voltametry, chronoamperomatry) and imaging (scanning electron microscopy (SEM)) methods, and a surface area increase factor of 50 was found, linked to the texturing of the surface generated by the presence of the Sepharose beads. The consequence of this increase was shown to be a jump of the local electrochemical activity which induced a well defined and localised electro-chemiluminescent signal. The new material was used to design biochips based on the electro-chemiluminescent reaction of luminol with enzymatically produced hydrogen peroxide. Thus, when using beads bearing bio-molecules such nucleic acid or human IgG, in conjunction with glucose oxidas-labelled DNA or antibody, sensitive biochips could be obtained with detection limits of 10(11) and 10(10) molecules, respectively. Multi-parameter enzyme-based biochips could also be achieved by locally adsorbing, at the PDMS-graphite surface, either glucose oxidase, lactate oxidase or choline oxidase. Detection limits of 10 microM for lactate and choline and 20 microM for glucose were found, with detection ranging over two decades at least.

  12. Transitions from near-surface to interior redox upon lithiation in conversion electrode materials

    SciTech Connect

    He, Kai; Xin, Huolin L.; Zhao, Kejie; Yu, Xiqian; Norlund, Dennis; Weng, Tsu-Chien; Li, Jing; Jiang, Yi; Cadigan, Christopher A.; Richards, Ryan M.; Doeff, Marca M.; Yang, Xiao-Qing; Stach, Eric A.; Li, Ju; Lin, Feng; Su, Dong

    2015-01-29

    Nanoparticle electrodes in lithium-ion batteries have both near-surface and interior contributions to their redox capacity, each with distinct rate capabilities. Using combined electron microscopy, synchrotron X-ray methods and ab initio calculations, we have investigated the lithiation pathways that occur in NiO electrodes. We find that the near-surface electroactive (Ni²⁺→Ni⁰) sites saturated very quickly, and then encounter unexpected difficulty in propagating the phase transition into the electrode (referred to as a “shrinking-core” mode). However, the interior capacity for Ni²⁺→Ni⁰ can be accessed efficiently following the nucleation of lithiation “fingers” which propagate into the sample bulk, but only after a certain incubation time. Our microstructural observations of the transition from a slow shrinking-core mode to a faster lithiation finger mode corroborate with synchrotron characterization of large-format batteries, and can be rationalized by stress effects on transport at high-rate discharge. The finite incubation time of the lithiation fingers sets the intrinsic limitation for the rate capability (and thus the power) of NiO for electrochemical energy storage devices. The present work unravels the link between the nanoscale reaction pathways and the C-rate-dependent capacity loss, and provides guidance for the further design of battery materials that favors high C-rate charging.

  13. Transitions from near-surface to interior redox upon lithiation in conversion electrode materials

    DOE PAGES

    He, Kai; Xin, Huolin L.; Zhao, Kejie; ...

    2015-01-29

    Nanoparticle electrodes in lithium-ion batteries have both near-surface and interior contributions to their redox capacity, each with distinct rate capabilities. Using combined electron microscopy, synchrotron X-ray methods and ab initio calculations, we have investigated the lithiation pathways that occur in NiO electrodes. We find that the near-surface electroactive (Ni²⁺→Ni⁰) sites saturated very quickly, and then encounter unexpected difficulty in propagating the phase transition into the electrode (referred to as a “shrinking-core” mode). However, the interior capacity for Ni²⁺→Ni⁰ can be accessed efficiently following the nucleation of lithiation “fingers” which propagate into the sample bulk, but only after a certain incubationmore » time. Our microstructural observations of the transition from a slow shrinking-core mode to a faster lithiation finger mode corroborate with synchrotron characterization of large-format batteries, and can be rationalized by stress effects on transport at high-rate discharge. The finite incubation time of the lithiation fingers sets the intrinsic limitation for the rate capability (and thus the power) of NiO for electrochemical energy storage devices. The present work unravels the link between the nanoscale reaction pathways and the C-rate-dependent capacity loss, and provides guidance for the further design of battery materials that favors high C-rate charging.« less

  14. Surface-modified Mg{sub 2}Ni-type negative electrode materials for Ni-MH battery

    SciTech Connect

    Cui, N.; Luan, B.; Bradhurst, D.; Liu, H.K.; Dou, S.X.

    1997-12-01

    In order to further improve the electrode performance of Mg{sub 1.9}Y{sub 0.1}Ni{sub 0.9}Al{sub 0.1} alloy at ambient temperature, its surface was modified by an ultrasound pretreatment in the alkaline solution and microencapsulation with Ni-P coating. The effects of various surface modifications on the microstructure and electrochemical performance of the alloy electrodes were investigated and compared in this paper. It was found that the modification with ultrasound pretreatment significantly improved the electrocatalytic activity of the negative electrode and then reduced the overpotential of charging/discharging, resulting in a remarkable increase of electrode capacity and high-rate discharge capability but having little influence on the cycle life. However, the electrode fabricated from the microencapsulated alloy powder showed a higher discharge capacity, better high-rate discharge capability and longer cycle life as well.

  15. Rechargeable Lithium-Air Batteries: Development of Ultra High Specific Energy Rechargeable Lithium-Air Batteries Based on Protected Lithium Metal Electrodes

    SciTech Connect

    2010-07-01

    BEEST Project: PolyPlus is developing the world’s first commercially available rechargeable lithium-air (Li-Air) battery. Li-Air batteries are better than the Li-Ion batteries used in most EVs today because they breathe in air from the atmosphere for use as an active material in the battery, which greatly decreases its weight. Li-Air batteries also store nearly 700% as much energy as traditional Li-Ion batteries. A lighter battery would improve the range of EVs dramatically. Polyplus is on track to making a critical breakthrough: the first manufacturable protective membrane between its lithium–based negative electrode and the reaction chamber where it reacts with oxygen from the air. This gives the battery the unique ability to recharge by moving lithium in and out of the battery’s reaction chamber for storage until the battery needs to discharge once again. Until now, engineers had been unable to create the complex packaging and air-breathing components required to turn Li-Air batteries into rechargeable systems.

  16. Surface characteristics of Ti-6Al-4V alloy by EDM with Cu-SiC composite electrode

    NASA Astrophysics Data System (ADS)

    Li, L.; Feng, L.; Bai, X.; Li, Z. Y.

    2016-12-01

    Ti-6Al-4V alloy is widely used in many industries due to its outstanding properties. However, it has poor machinability using conventional mechanical cutting process. Electrical discharge machining is an alternative competitive process to machine titanium alloy by electrical erosion. This article studies the machining characteristics of Ti-6Al-4V with Cu-SiC composite electrode. Surface topography, subsurface microstructure, energy dispersive spectroscopy analysis, and micro-hardness have been analyzed. The machined surfaces show irregular compound structures, droplets of debris, shallow craters, and micro-pores. The surfaces processed by Cu-SiC electrode have fewer number of microcracks compared with that by Cu electrode. Continuous and uniform hardened layer can be achieved by Cu-SiC electrode. The hardened layer has significantly higher hardness than the bulk material because the new phases of TiC and TiSi2 were created on the surface.

  17. Simulation Study on Semiconductor Coupled Surface Acoustic Wave Convolver through a Multi-Strip Electrodes

    NASA Astrophysics Data System (ADS)

    Hohkawa, Kohji; Suda, Takaya; Aoki, Yusuke; Kaneshiro, Chinami; Koh, Keishin

    2001-05-01

    This paper presents results of simulation study on a semiconductor coupled surface acoustic wave (SAW) convolver, in which the propagating SAW on a highly coupling coefficient piezoelectric substrate, couples with a bonded semiconductor diodes through multi-strip electrodes. We focus our study on a relatively wide band device which is the main feature of a highly efficiency device. By using a simple analysis and circuit simulator, based on the simulation program with integrated circuit emphasis (SPICE), we clarified the effect of device parameters, such as the shape of multi-strip tapping electrodes, characteristics of diode, impedance matching condition, kinds of transmission code and electro-mechanical coupling coefficient of SAW, on the device performances. We discussed the phenomenon, which cause the degradation, focusing on the frequency domain. We also clarified the essential problems of second order effect on the wide bandwidth device, which should be solved.

  18. Electrodes patterning on ionic polymer metal composite for making smooth surface on tunable mirrors

    NASA Astrophysics Data System (ADS)

    Cheng, Wei; Su, Guo-Dung J.

    2012-10-01

    Deformable mirror is a very important reflective component in optical system, which can vary the focal length while the surface deform. Nowadays several type of material were used as deformable mirror, such as liquid lens and MEMS deformable mirror. MEMS deformable mirror have been developed in our group and shows the potential. However, the problem of high actuation voltage is not easy to solve. In this thesis, we proposed using low voltage applied material, which is called Ioic-Polymer Metal Composite (IPMC) with the advantage of low applied voltage but high actuation performance. Arbitrary-shaped electrode IPMC was successfully fabricated by simply covering a shadow mask during electroless plating. Maximum central displacement of ellipsoid-shaped electrode IPMC can be achieved up to 350 μm under 2.5 volts applied. We believe this technique can be used in optical system as a deformable mirror in the future.

  19. Voltammetric and impedance behaviours of surface-treated nano-crystalline diamond film electrodes

    SciTech Connect

    Liu, F. B.; Jing, B.; Cui, Y.; Di, J. J.; Qu, M.

    2015-04-15

    The electrochemical performances of hydrogen- and oxygen-terminated nano-crystalline diamond film electrodes were investigated by cyclic voltammetry and AC impedance spectroscopy. In addition, the surface morphologies, phase structures, and chemical states of the two diamond films were analysed by scanning probe microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. The results indicated that the potential window is narrower for the hydrogen-terminated nano-crystalline diamond film than for the oxygen-terminated one. The diamond film resistance and capacitance of oxygen-terminated diamond film are much larger than those of the hydrogen-terminated diamond film, and the polarization resistances and double-layer capacitance corresponding to oxygen-terminated diamond film are both one order of magnitude larger than those corresponding to the hydrogen-terminated diamond film. The electrochemical behaviours of the two diamond film electrodes are discussed.

  20. Semi-analytical model for quasi-double-layer surface electrode ion traps

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Chen, Shuming; Wang, Yaohua

    2016-11-01

    To realize scale quantum processors, the surface-electrode ion trap is an effective scaling approach, including single-layer, double-layer, and quasi-double-layer traps. To calculate critical trap parameters such as the trap center and trap depth, the finite element method (FEM) simulation was widely used, however, it is always time consuming. Moreover, the FEM simulation is also incapable of exhibiting the direct relationship between the geometry dimension and these parameters. To eliminate the problems above, House and Madsen et al. have respectively provided analytic models for single-layer traps and double-layer traps. In this paper, we propose a semi-analytical model for quasi-double-layer traps. This model can be applied to calculate the important parameters above of the ion trap in the trap design process. With this model, we can quickly and precisely find the optimum geometry design for trap electrodes in various cases.

  1. Morphology of Air Nanobubbles Trapped atHydrophobic Nanopatterned Surfaces

    SciTech Connect

    Checco, A.; Hofmann, T.; DiMasi, E.; Black, C.T.; Ocko, B.M.

    2010-04-01

    The details of air nanobubble trapping at the interface between water and a nanostructured hydrophobic silicon surface are investigated using X-ray scattering and contact angle measurements. Large-area silicon surfaces containing hexagonally packed, 20 nm wide hydrophobic cavities provide ideal model surfaces for studying the morphology of air nanobubbles trapped inside cavities and its dependence on the cavity depth. Transmission small-angle X-ray scattering measurements show stable trapping of air inside the cavities with a partial water penetration of 5-10 nm into the pores, independent of their large depth variation. This behavior is explained by consideration of capillary effects and the cavity geometry. For parabolic cavities, the liquid can reach a thermodynamically stable configuration - a nearly planar nanobubble meniscus - by partially penetrating into the pores. This microscopic information correlates very well with the macroscopic surface wetting behavior.

  2. Surface Flux Modeling for Air Quality Applications

    EPA Science Inventory

    For many gasses and aerosols, dry deposition is an important sink of atmospheric mass. Dry deposition fluxes are also important sources of pollutants to terrestrial and aquatic ecosystems. The surface fluxes of some gases, such as ammonia, mercury, and certain volatile organic c...

  3. The effect of surface transport on water desalination by porous electrodes undergoing capacitive charging

    NASA Astrophysics Data System (ADS)

    Shocron, Amit N.; Suss, Matthew E.

    2017-03-01

    Capacitive deionization (CDI) is a technology in which water is desalinated by ion electrosorption into the electric double layers (EDLs) of charging porous electrodes. In recent years significant advances have been made in modeling the charge and salt dynamics in a CDI cell, but the possible effect of surface transport within diffuse EDLs on these dynamics has not been investigated. We here present theory which includes surface transport in describing the dynamics of a charging CDI cell. Through our numerical solution to the presented models, the possible effect of surface transport on the CDI process is elucidated. While at some model conditions surface transport enhances the rate of CDI cell charging, counter-intuitively this additional transport pathway is found to slow down cell charging at other model conditions.

  4. The effect of surface transport on water desalination by porous electrodes undergoing capacitive charging

    NASA Astrophysics Data System (ADS)

    Shocron, Amit N.; Suss, Matthew E.

    2016-07-01

    Capacitive deionization (CDI) is a technology in which water is desalinated by ion electrosorption into the electric double layers (EDLs) of charging porous electrodes. In recent years significant advances have been made in modeling the charge and salt dynamics in a CDI cell, but the possible effect of surface transport within diffuse EDLs on these dynamics has not been investigated. We here present theory which includes surface transport in describing the dynamics of a charging CDI cell. Through our numerical solution to the presented models, the possible effect of surface transport on the CDI process is elucidated. While at some model conditions surface transport enhances the rate of CDI cell charging, counter-intuitively this additional transport pathway is found to slow down cell charging at other model conditions.

  5. Scanning tunneling microscopy of electrochemically activated platinum surfaces. A direct ex-situ determination of the electrode nanotopography

    SciTech Connect

    Vazquez, L.; Gomez, J.; Baro, A.M.; Garcia, N.; Marcos, M.L.; Velasco, J.G.; Vara, J.M.; Arvia, A.J.; Presa, J.; Garcia, A.; Aguilar, M.

    1987-03-18

    A direct scanning tunneling microscopy ex-situ determination on the nanometer scale of the topography of electrochemically highly activated platinum electrodes is presented. A correlation between catalytic activity and surface microtopography becomes evident. This result gives support to a structural model for the activated electrode surface. In the model, a volume with a pebble-like structure allows electrocatalytic processes to occur practically free of diffusion relaxation contributions under usual voltammetric conditions.

  6. An organic surface modifier to produce a high work function transparent electrode for high performance polymer solar cells.

    PubMed

    Choi, Hyosung; Kim, Hak-Beom; Ko, Seo-Jin; Kim, Jin Young; Heeger, Alan J

    2015-02-04

    Modification of an ITO electrode with small-molecule organic surface modifier, 4-chloro-benzoic acid (CBA), via a simple spin-coating method produces a high-work-function electrode with high transparency and a hydrophobic surface. As an alternative to PEDOT:PSS, CBA modification achieves efficiency enhancement up to 8.5%, which is attributed to enhanced light absorption within the active layer and smooth hole transport from the active layer to the anode.

  7. Surface modification of battery electrodes via electroless deposition with improved performance for Na-ion batteries.

    PubMed

    Lahiri, Abhishek; Olschewski, Mark; Gustus, René; Borisenko, Natalia; Endres, Frank

    2016-06-01

    Sodium-ion batteries (SIBs) are emerging as potential stationary energy storage devices due to the abundance and low cost of sodium. A simple and energy efficient strategy to develop electrodes for SIBs with a high charge/discharge rate is highly desirable. Here we demonstrate that by surface modification of Ge, using electroless deposition in SbCl3/ionic liquids, the stability and performance of the anode can be improved. This is due to the formation of GexSb1-x at the surface leading to better diffusion of Na, and the formation of a stable twin organic and inorganic SEI which protects the electrode. By judicious control of the surface modification, an improvement in the capacity to between 50% and 300% has been achieved at high current densities (0.83-8.4 A g(-1)) in an ionic liquid electrolyte NaFSI-[Py1,4]FSI. The results clearly demonstrate that an electroless deposition based surface modification strategy in ionic liquids offers exciting opportunities in developing superior energy storage devices.

  8. Piperidine adsorption on two different silver electrodes: A combined surface enhanced Raman spectroscopy and density functional theory study

    NASA Astrophysics Data System (ADS)

    Hao, Yanling; Fang, Yan

    2007-10-01

    The surface enhanced Raman scattering (SERS) spectra of piperidine in silver colloid solution, on roughened silver electrode and on roughened silver electrode modified with silver nanoparticles were studied, and the high-quality SERS spectra of piperidine on roughened silver electrode modified with silver nanoparticles were obtained for the first time. Surface selection rules derived from the EM enhancement model were employed to deduce piperidine orientations on the different surfaces. On the basis of this, two models of piperidine adsorbed on the surface of the silver nanoparticles were built, and DFT-B3PW91/LanL2dz was applied to calculate the Raman frequencies. It proves that, at higher potential values, the piperidine is perpendicularly standing on the roughened silver electrode surface though its lone-electron pair, but in silver colloid solution and on the silver nanoparticles modified silver electrode the piperidine molecular lies flat on the silver surface. In the meantime, the potential dependent SERS of piperidine on the modified electrode were studied.

  9. Surface passivation of natural graphite electrode for lithium ion battery by chlorine gas.

    PubMed

    Suzuki, Satoshi; Mazej, Zoran; Zemva, Boris; Ohzawa, Yoshimi; Nakajima, Tsuyoshi

    2013-01-01

    Surface lattice defects would act as active sites for electrochemical reduction of propylene carbonate (PC) as a solvent for lithium ion battery. Effect of surface chlorination of natural graphite powder has been investigated to improve charge/discharge characteristics of natural graphite electrode in PC-containing electrolyte solution. Chlorination of natural graphite increases not only surface chlorine but also surface oxygen, both of which would contribute to the decrease in surface lattice defects. It has been found that surface-chlorinated natural graphite samples with surface chlorine concentrations of 0.5-2.3 at% effectively suppress the electrochemical decomposition of PC, highly reducing irreversible capacities, i.e. increasing first coulombic efficiencies by 20-30% in 1 mol L-1 LiClO4-EC/DEC/PC (1:1:1 vol.). In 1 mol L-1 LiPF6-EC/EMC/PC (1:1:1 vol.), the effect of surface chlorination is observed at a higher current density. This would be attributed to decrease in surface lattice defects of natural graphite powder by the formation of covalent C-Cl and C=O bonds.

  10. High surface area electrodes in ionic polymer transducers: numerical and experimental investigations of the chemo-electric behavior

    NASA Astrophysics Data System (ADS)

    Akle, Barbar J.; Wallmersperger, Thomas; Akle, Etienne; Leo, Donald J.

    2008-03-01

    Ionomeric polymer transducers have received considerable attention in the past ten years due to their ability to generate large bending strain and moderate stress at low applied voltages. Ionic polymer transducers consist of an ionomer, usually Nafion, sandwiched between two electrically conductive electrodes. Recently, a novel fabrication technique denoted as the direct assembly process (DAP) enabled controlled electrode architecture in ionic polymer transducers. A DAP transducer usually consists of two high surface area electrodes made of uniform distributed particles sandwiching an ionomer membrane. Further enhancements to the DAP enabled sub-micron control of the electrode architecture. In this study a previously developed finite element model, capable of simulating ionic polymer transducers with high surface area electrodes is used to study the effect of electrode architecture on the actuation performance due to a unit volt step input. Four architectures are considered: Agglomerate, Gradient, Random, and Lines. The four architectures are simulated for low particle loading and high particle loading. The agglomerate presents the case of badly dispersed metal particles in the electrode. Simulation results demonstrate that particle aggregation reduces the actuation performance on an IPT. The Gradient simulates an IPT built using an Impregnation-Reduction method. The Gradient is compared to a randomly distributed electrode which represents an IPT built using the DAP method. Simulation results demonstrate that the DAP built IPT outperforms the one built using the impregnation-reduction method. Finally line architecture is simulated and results demonstrate that it outperforms random architecture especially at high particle loading.

  11. Charging of moving surfaces by corona discharges sustained in air

    SciTech Connect

    Wang, Jun-Chieh Kushner, Mark J.; Zhang, Daihua; Leoni, Napoleon Birecki, Henryk Gila, Omer

    2014-07-28

    Atmospheric pressure corona discharges are used in electrophotographic (EP) printing technologies for charging imaging surfaces such as photoconductors. A typical corona discharge consists of a wire (or wire array) biased with a few hundred volts of dc plus a few kV of ac voltage. An electric discharge is produced around the corona wire from which electrons drift towards and charge the underlying dielectric surface. The surface charging reduces the voltage drop across the gap between the corona wire and the dielectric surface, which then terminates the discharge, as in a dielectric barrier discharge. In printing applications, this underlying surface is continuously moving throughout the charging process. For example, previously charged surfaces, which had reduced the local electric field and terminated the local discharge, are translated out of the field of view and are replaced with uncharged surface. The uncharged surface produces a rebound in the electric field in the vicinity of the corona wire which in turn results in re-ignition of the discharge. The discharge, so reignited, is then asymmetric. We found that in the idealized corona charging system we investigated, a negatively dc biased corona blade with a dielectric covered ground electrode, the discharge is initially sustained by electron impact ionization from the bulk plasma and then dominated by ionization from sheath accelerated secondary electrons. Depending on the speed of the underlying surface, the periodic re-ignition of the discharge can produce an oscillatory charging pattern on the moving surface.

  12. Using electrochemistry - total internal refection imaging ellipsometry to monitor biochemical oxygen demand on the surface tethered polyelectrolyte modified electrode

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Li, Meng; Lv, Bei'er; Chen, YanYan; Ma, Hongwei; Jin, Gang

    2015-03-01

    Our previous work has proposed an electrochemistry - total internal reflection imaging ellipsometry (EC-TIRIE) technique to observe the dissolved oxygen (DO) reduction on Clark electrode since high interface sensitivity makes TIRIE a useful tool to study redox reactions on the electrode surface. To amplify the optical signal noise ratio (OSNR), a surface tethered weak polyelectrolyte, carboxylated poly(oligo(ethylene glycol) methacrylate-random- 2-hydroxyethylmethacrylate) (abbreviated as carboxylated poly(OEGMA-r-HEMA)), has been introduced on the electrode surface. Since Clark electrode is widely used in biochemical oxygen demand (BOD) detection, we use this technique to measure BOD in the sample. The dynamic range of the system is from 0 ˜ 25 mg/L. Two samples have been measured. Compared with the conventional method, the deviation of both optical and electrical signals are less than 10%.

  13. Robust myoelectric signal detection based on stochastic resonance using multiple-surface-electrode array made of carbon nanotube composite paper

    NASA Astrophysics Data System (ADS)

    Shirata, Kento; Inden, Yuki; Kasai, Seiya; Oya, Takahide; Hagiwara, Yosuke; Kaeriyama, Shunichi; Nakamura, Hideyuki

    2016-04-01

    We investigated the robust detection of surface electromyogram (EMG) signals based on the stochastic resonance (SR) phenomenon, in which the response to weak signals is optimized by adding noise, combined with multiple surface electrodes. Flexible carbon nanotube composite paper (CNT-cp) was applied to the surface electrode, which showed good performance that is comparable to that of conventional Ag/AgCl electrodes. The SR-based EMG signal system integrating an 8-Schmitt-trigger network and the multiple-CNT-cp-electrode array successfully detected weak EMG signals even when the subject’s body is in the motion, which was difficult to achieve using the conventional technique. The feasibility of the SR-based EMG detection technique was confirmed by demonstrating its applicability to robot hand control.

  14. Calcium phosphates deposited on titanium electrode surface--part 1: Effect of the electrode polarity and oxide film on the deposited materials.

    PubMed

    Okawa, Seigo; Watanabe, Kouichi; Kanatani, Mitsugu

    2013-01-01

    We report experimental results about the effect of polarity of electrode and anodized titanium oxide film on the deposited materials by electrolysis of an acidic calcium phosphate solution. Mirror-polished titanium and anodized titanium were used as anode or cathode, and a Pt plate was used as a counter electrode. The load voltage was held constant at 20 VDC. No deposited materials were found on the anode surface. On the other hand, dicalcium phosphate dihydrate (DCPD) was deposited on the cathode surface at the beginning of the electrolysis. After the electrolysis time 600 s, the non-stoichiometric hydroxyapatite (HAp) with several hundred nanometers was formed on the specimen surface. Based on X-ray photoelectron spectroscopy data, the anodized oxide film contained both P(5+) and P(3+) ions. This characteristic of the oxide film and the electrolysis conditions were related to the behavior of the deposition of ultra fine HAp with high crystallinity.

  15. Dropwise Condensation Experiments with Humid Air at a Polymer Surface

    NASA Astrophysics Data System (ADS)

    Götze, P.; Philipp, Ch; Gross, U.

    2012-11-01

    A new test facility has been developed to investigate dropwise condensation heat transfer in a humid air environment. It is designed as a closed loop system in which air is circulated by a fan, enabling investigations in the following parameter ranges: velocity up to 20 m/s; Reynolds number up to 20,000; temperature 20 to 100 °C relative humidity up to 100 %. Heat transfer measurements are done with a specifically designed micro sensor which is flush mounted at one of the vertical surfaces of a horizontal flow channel 12 mm × 32 mm (inner width and height, respectively) and covered at its air-side surface by a newly developed polymer layer containing 20 % of carbon nanotubes for improvement of the thermal conductivity. A total of 8 thermocouples is embedded inside the sensor. Their readings serve as input data to a numerical model which enables consideration of heat losses and evaluation of surface temperature and heat flux. The measuring system allows to analyse the effects of heat flux, air-to-wall temperature difference, absolute and relative humidity, and Reynolds number on the heat transfer coefficient. Single phase heat transfer results show excellent agreement with well established correlations for turbulent air flow. The onset of dropwise condensation was detected with very good repeatability. This paper covers details of the experimental device, measuring system and data evaluation including accuracy considerations. Single phase and preliminary dropwise condensation results with humid air are reported.

  16. Individualized localization and cortical surface-based registration of intracranial electrodes

    PubMed Central

    Dykstra, Andrew R.; Chan, Alexander M.; Quinn, Brian T.; Zepeda, Rodrigo; Keller, Corey J.; Cormier, Justine; Madsen, Joseph R.; Eskandar, Emad N.; Cash, Sydney S.

    2011-01-01

    In addition to its widespread clinical use, the intracranial electroencephalogram (iEEG) is increasingly being employed as a tool to map the neural correlates of normal cognitive function as well as for developing neuroprosthetics. Despite recent advances, and unlike other established brain mapping modalities (e.g. functional MRI, magneto- and electroencephalography), registering the iEEG with respect to neuroanatomy in individuals – and coregistering functional results across subjects – remains a significant challenge. Here we describe a method which coregisters high-resolution preoperative MRI with postoperative computerized tomography (CT) for the purpose of individualized functional mapping of both normal and pathological (e.g., interictal discharges and seizures) brain activity. Our method accurately (within 3mm, on average) localizes electrodes with respect to an individual’s neuroanatomy. Furthermore, we outline a principled procedure for either volumetric or surface-based group analyses. We demonstrate our method in five patients with medically-intractable epilepsy undergoing invasive monitoring of the seizure focus prior to its surgical removal. The straight-forward application of this procedure to all types of intracranial electrodes, robustness to deformations in both skull and brain, and the ability to compare electrode locations across groups of patients makes this procedure an important tool for basic scientists as well as clinicians. PMID:22155045

  17. Prediction of visual evoked potentials at any surface location from a set of three recording electrodes.

    PubMed

    Mazinani, Babac A E; Waberski, Till D; van Ooyen, Andre; Walter, Peter

    2008-05-01

    Purpose of this study was to introduce a mathematical model which allows the calculation of a source dipole as the origin of the evoked activity based on the data of three simultaneously recorded VEPs from different locations at the scalp surface to predict field potentials at any neighboring location and to validate this model by comparison with actual recordings. In 10 healthy subjects (25-38, mean 29 years) continuous VEPs were recorded via 96 channels. On the base of the recordings at the positions POz', O1' and O2', a source dipole vector was calculated for each time point of the recordings and VEP responses were back projected for any of the 96 electrode positions. Differences between the calculated and the actually recorded responses were quantified by coefficients of variation (CV). The prediction precision and response size depended on the distance between the electrode of the predicted response and the recording electrodes. After compensating this relationship using a polynomial function, the CV of the mean difference between calculated and recorded responses of the 10 subjects was 2.8 +/- 1.2%. In conclusion, the "Mini-Brainmapping" model can provide precise topographical information with minimal additional recording efforts with good reliability. The implementation of this method in a routine diagnostic setting as an "easy-to-do" procedure would allow to examine a large number of patients and normal subjects in a short time, and thus, a solid data base could be created to correlate well defined pathologies with topographical VEP changes.

  18. Time-lag properties of corona streamer discharges between impulse sphere and dc needle electrodes under atmospheric air conditions.

    PubMed

    Okano, Daisuke

    2013-02-01

    In this study of corona streamer discharges from an impulse generator using a dc power supply, the relationship of the discharge time-lag with the dc bias voltage between the sphere-to-needle electrodes under atmospheric conditions is investigated. Devices utilizing corona discharges have been used to purify air or water, destroy bacteria, and to remove undesirable substances, and in order to achieve fast response times and high power efficiencies in such devices, it is important to minimize the time-lag of the corona discharge. Our experimental results show that (a) the discharge path of a negatively biased needle electrode will be straighter than that of a positively biased needle and (b) the discharge threshold voltage in both the positive and the negative needle electrodes is nearly equal to 33 kV. By expressing the discharge voltage as a power function of time-lag, the extent of corona generation can be quantitatively specified using the exponent of this power function. The observed behavior of a corona streamer discharge between the negative spherical and the positive needle electrodes indicates that the largest power exponent is associated with the shortest time-lag, owing to the reduction in the statistical time-lag in the absence of a formative time-lag.

  19. Time-lag properties of corona streamer discharges between impulse sphere and dc needle electrodes under atmospheric air conditions

    NASA Astrophysics Data System (ADS)

    Okano, Daisuke

    2013-02-01

    In this study of corona streamer discharges from an impulse generator using a dc power supply, the relationship of the discharge time-lag with the dc bias voltage between the sphere-to-needle electrodes under atmospheric conditions is investigated. Devices utilizing corona discharges have been used to purify air or water, destroy bacteria, and to remove undesirable substances, and in order to achieve fast response times and high power efficiencies in such devices, it is important to minimize the time-lag of the corona discharge. Our experimental results show that (a) the discharge path of a negatively biased needle electrode will be straighter than that of a positively biased needle and (b) the discharge threshold voltage in both the positive and the negative needle electrodes is nearly equal to 33 kV. By expressing the discharge voltage as a power function of time-lag, the extent of corona generation can be quantitatively specified using the exponent of this power function. The observed behavior of a corona streamer discharge between the negative spherical and the positive needle electrodes indicates that the largest power exponent is associated with the shortest time-lag, owing to the reduction in the statistical time-lag in the absence of a formative time-lag.

  20. Surface film formation on nickel electrodes in a propylene carbonate solution at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Mogi, Ryo; Inaba, Minoru; Iriyama, Yasutoshi; Abe, Takeshi; Ogumi, Zempachi

    The effect of temperature on surface film formation on nickel electrode was studied in 1 mol dm -3 bis(perfluoroethylsulfonyl)imide dissolved in propylene carbonate by atomic force microscopy (AFM) and ac impedance spectroscopy. Cyclic voltammetry measurements revealed that electrolyte decomposition reactions are accelerated at elevated temperatures, especially at 60 and 80 °C. In situ AFM measurements showed that the film formation is fast and the resulting surface film is thicker at 80 °C than at room temperature. Furthermore, it was confirmed by ac impedance measurements that the resistance of surface film was very low at elevated temperatures. These results were discussed in relation to superior cycling characteristics of lithium deposition and dissolution at the elevated temperatures.

  1. A generic platform for the addressable functionalisation of electrode surfaces through self-induced "electroclick".

    PubMed

    Orain, Christophe; Le Poul, Nicolas; Gomila, Antoine; Kerbaol, Jean-Michel; Cosquer, Nathalie; Reinaud, Olivia; Conan, Françoise; Le Mest, Yves

    2012-01-09

    A novel and general strategy for the immobilisation of functional objects onto electrodes is described. The concept is based on the addition of two pendant ethynyl groups onto a bis(pyridyl)amine derivative, which acts as a molecular platform. This platform is pre-functionalised with an N(3)-tagged object of interest by Huisgen cycloaddition to one of the ethynyl groups in biphasic conditions. Hence, when complexed by Cu(II) , this molecular-object holder can be immobilised, by a "self-induced electroclick", through the second ethynyl group onto N(3)-alkanethiol self-assembled monolayers on a gold electrode. Two different functional groups, a redox innocent ((CH(2))(3)-Ph) and an electrochemical probe (ferrocene), were immobilised by following this strategy. The in situ electrochemical grafting showed, for both systems, that the kinetics of immobilisation is fast. The voltammetric characterisation of the surface-tagged functionalised copper complexes indicated that a good surface coverage was achieved and that a moderately fast electron-transfer reaction occurs. Remarkably, in the case of the redox-active ferrocenyl-immobilised system, the electrochemical response highlighted the involvement of the copper ion of the platform in the kinetics of the electron transfer to the ferrocene moiety. This platform is a promising candidate for applications in surface addressing in areas as diverse as biology and materials.

  2. Appropriately placed surface EMG electrodes reflect deep muscle activity (psoas, quadratus lumborum, abdominal wall) in the lumbar spine.

    PubMed

    McGill, S; Juker, D; Kropf, P

    1996-11-01

    This study tested the possibility of obtaining the activity of deeper muscles in the torso-specifically psoas, quadratus lumborum, external oblique, internal oblique and transverse abdominis, using surface myoelectric electrodes. It was hypothesized that: (1) surface electrodes adequately represent the amplitude of deep muscles (specifically psoas, quadratus lumborum, external oblique, internal oblique, transverse abdominis); (2) a single surface electrode location would best represent the activation profiles of each deep muscle over a broad variety of tasks. We assumed that prediction of activation within 10% of maximum voluntary contraction (RMS difference between the surface and intramuscular channels), over the time history of the signal, was reasonable and acceptable to assist clinical interpretation of muscle activation amplitude, and ultimately for modeled estimates of muscle force. Surface electrodes were applied and intramuscular electrodes were inserted on the left side of the body in five men and three women who then performed a wide variety of flexor tasks (bent knee and straight leg situps and leg raises, curl ups), extensor tasks (including lifting barbells up to 70 kg), lateral bending tasks (standing lateral bend and horizontal lying side support), twisting tasks (standing and sitting), and internal/external hip rotation. Using the criteria of RMS difference and the coefficient of determination (R2) to compare surface with intramuscular myoelectric signals, the results indicated that selected surface electrodes adequately represent the amplitude of deep muscles-always within 15% RMS difference, or less with the exception of psoas where differences up to 20% were observed but only in certain maximum voluntary contraction efforts. It appears reasonable for spine modelers, and particularly clinicians, to assume well selected surface electrode locations provide a representation of these deeper muscles-as long as they recognize the magnitude of error for

  3. EML Surface Air Sampling Program, 1990--1993 data

    SciTech Connect

    Larsen, R.J.; Sanderson, C.G.; Kada, J.

    1995-11-01

    Measurements of the concentrations of specific atmospheric radionuclides in air filter samples collected for the Environmental Measurements Laboratory`s Surface Air Sampling Program (SASP) during 1990--1993, with the exception of April 1993, indicate that anthropogenic radionuclides, in both hemispheres, were at or below the lower limits of detection for the sampling and analytical techniques that were used to collect and measure them. The occasional detection of {sup 137}Cs in some air filter samples may have resulted from resuspension of previously deposited debris. Following the April 6, 1993 accident and release of radionuclides into the atmosphere at a reprocessing plant in the Tomsk-7 military nuclear complex located 16 km north of the Siberian city of Tomsk, Russia, weekly air filter samples from Barrow, Alaska; Thule, Greenland and Moosonee, Canada were selected for special analyses. The naturally occurring radioisotopes that the authors measure, {sup 7}Be and {sup 210}Pb, continue to be detected in most air filter samples. Variations in the annual mean concentrations of {sup 7}Be at many of the sites appear to result primarily from changes in the atmospheric production rate of this cosmogenic radionuclide. Short-term variations in the concentrations of {sup 7}Be and {sup 210}Pb continued to be observed at many sites at which weekly air filter samples were analyzed. The monthly gross gamma-ray activity and the monthly mean surface air concentrations of {sup 7}Be, {sup 95}Zr, {sup 137}Cs, {sup 144}Ce, and {sup 210}Pb measured at sampling sites in SASP during 1990--1993 are presented. The weekly mean surface air concentrations of {sup 7}Be, {sup 95}Zr, {sup 137}Cs, {sup 144}Ce, and {sup 210}Pb for samples collected during 1990--1993 are given for 17 sites.

  4. Electrochemical properties of core-shell TiC-TiO2 nanoparticle films immobilized at ITO electrode surfaces.

    PubMed

    Stott, Susan J; Mortimer, Roger J; Dann, Sandie E; Oyama, Munetaka; Marken, Frank

    2006-12-14

    Titanium carbide (TiC) nanoparticles are readily deposited onto tin-doped indium oxide (ITO) electrodes in the form of thin porous films. The nanoparticle deposits are electrically highly conducting and electrochemically active. In aqueous media (at pH 7) and at applied potentials positive of 0.3 V vs. SCE partial anodic surface oxidation and formation (at least in part) of novel core-shell TiC-TiO2 nanoparticles is observed. Significant thermal oxidation of TiC nanoparticles by heating in air occurs at a temperature of 250 degrees C and leads first to core-shell TiC-TiO2 nanoparticles, next at ca. 350 degrees C to TiO2 (anatase), and finally at temperatures higher than 750 degrees C to TiO2 (rutile). Electrochemically and thermally partially oxidized TiC nanoparticles still remain very active and for some redox systems electrocatalytically active. Scanning and transmission electron microscopy (SEM and TEM), temperature dependent XRD, quartz crystal microbalance, and voltammetric measurements are reported. The electrocatalytic properties of the core-shell TiC-TiO2 nanoparticulate films are surveyed for the oxidation of hydroquinone, ascorbic acid, and dopamine in aqueous buffer media. In TiC-TiO2 core-shell nanoparticle films TiO2 surface reactivity can be combined with TiC conductivity.

  5. Magnetohydrodynamic electrode

    DOEpatents

    Boquist, Carl W.; Marchant, David D.

    1978-01-01

    A ceramic-metal composite suitable for use in a high-temperature environment consists of a refractory ceramic matrix containing 10 to 50 volume percent of a continuous high-temperature metal reinforcement. In a specific application of the composite, as an electrode in a magnetohydrodynamic generator, the one surface of the electrode which contacts the MHD fluid may have a layer of varying thickness of nonreinforced refractory ceramic for electrode temperature control. The side walls of the electrode may be coated with a refractory ceramic insulator. Also described is an electrode-insulator system for a MHD channel.

  6. The nature of the air-cleaved mica surface

    NASA Astrophysics Data System (ADS)

    Christenson, Hugo K.; Thomson, Neil H.

    2016-06-01

    The accepted image of muscovite mica is that of an inert and atomically smooth surface, easily prepared by cleavage in an ambient atmosphere. Consequently, mica is extensively used a model substrate in many fundamental studies of surface phenomena and as a substrate for AFM imaging of biomolecules. In this review we present evidence from the literature that the above picture is not quite correct. The mica used in experimental work is almost invariably cleaved in laboratory air, where a reaction between the mica surface, atmospheric CO2 and water occurs immediately after cleavage. The evidence suggests very strongly that as a result the mica surface becomes covered by up to one formula unit of K2CO3 per nm2, which is mobile under humid conditions, and crystallises under drier conditions. The properties of mica in air or water vapour cannot be fully understood without reference to the surface K2CO3, and many studies of the structure of adsorbed water on mica surfaces may need to be revisited. With this new insight, however, the air-cleaved mica should provide exciting opportunities to study phenomena such as two-dimensional ion diffusion, electrolyte effects on surface conductivity, and two-dimensional crystal nucleation.

  7. Study on the deterioration mechanism of layered rock-salt electrodes using epitaxial thin films - Li(Ni, Co, Mn)O2 and their Zr-O surface modified electrodes

    NASA Astrophysics Data System (ADS)

    Abe, Machiko; Iba, Hideaki; Suzuki, Kota; Minamishima, Hiroaki; Hirayama, Masaaki; Tamura, Kazuhisa; Mizuki, Jun'ichiro; Saito, Tomohiro; Ikuhara, Yuichi; Kanno, Ryoji

    2017-03-01

    Deterioration mechanism of Li(Ni, Co, Mn)O2 and Zr-O surface modified electrodes has been elucidated using epitaxial thin films synthesized by pulsed laser deposition. The electrodes comprise a mixture of layered rock-salt and spinel phases. The deterioration mechanism is analyzed using cyclic voltammetry, in situ X-ray diffraction measurements, and in situ neutron reflectometry. The spinel phase in the electrodes has low electrochemical activity and is not involved in Li insertion/extraction. The amount of Li participating in the charge-discharge reactions in the layered rock-salt phase increases with cycling, inducing a phase change at the electrode surface, lowering the reversibility. In contrast, in the Zr-O surface modified electrode, the spinel phase does not increase on charging/discharging. Thus, the Zr-O modification stabilizes the surface of layered rock-salt structure, thereby improving the cycling characteristics. Also, after the Zr-O modification, the Li concentration in the liquid electrolyte near the electrode/electrolyte interface increases during charging/discharging. The Zr-O surface modification not only stabilizes the electrode surface but also causes changes on the electrolyte side. Using the mixed model electrodes, we elucidate the mechanism of electrode deterioration and the origin of the improvement in cycling characteristics occurring on surface modification.

  8. Influence of surface kinematics on air-sea heat flux

    NASA Astrophysics Data System (ADS)

    Veron, Fabrice; Melville, Ken

    2004-11-01

    The top few meters of the oceanic boundary layer play a critical role in the transfers of momentum, gas, mass and heat between the atmosphere and the ocean. These exchanges must necessarily transfer through the surface, and presumably, the rates at which they do are influence by the dynamics of the surface layer. Heat flux in particular is regulated by the thin surface thermal layer which, at most, is only a few millimeter thick. We are specifically interested in the influence of small coherent structures of the surface turbulence on the heat flux. Using active and passive infrared imaging, we measured the evolution the surface velocity and temperature fields over small areas of a few square meters. High-resolution surface Eulerian velocity fields using cross-correlation techniques (PIV) are obtained. Using active marking of the surface with an infrared CO2 laser, we have not only shown that it is possible to directly recover the Langrangian surface velocity, but also, by marking appropriate patterns on the surface we have been able to measure the shear strain, vorticity, and surface divergence. With the penetration depth of infrared radiation at these wavelengths being a few microns, these techniques appear to be quite apt for direct measurements of ocean surface turbulence. We have also found that the flux of heat through the surface appears to be influenced by the surface wave field. We will discuss the results in the context of air sea heat flux and ocean surface turbulence.

  9. Theoretical approach for optical response in electrochemical systems: Application to electrode potential dependence of surface-enhanced Raman scattering

    SciTech Connect

    Iida, Kenji; Noda, Masashi; Nobusada, Katsuyuki

    2014-09-28

    We propose a theoretical approach for optical response in electrochemical systems. The fundamental equation to be solved is based on a time-dependent density functional theory in real-time and real-space in combination with its finite temperature formula treating an electrode potential. Solvation effects are evaluated by a dielectric continuum theory. The approach allows us to treat optical response in electrochemical systems at the atomistic level of theory. We have applied the method to surface-enhanced Raman scattering (SERS) of 4-mercaptopyridine on an Ag electrode surface. It is shown that the SERS intensity has a peak as a function of the electrode potential. Furthermore, the real-space computational approach facilitates visualization of variation of the SERS intensity depending on an electrode potential.

  10. Silicon micropowder negative electrode endures more than 1000 cycles when a surface-roughened clad current collector is used

    NASA Astrophysics Data System (ADS)

    Kataoka, Riki; Oda, Yoshimitsu; Inoue, Ryouji; Kawasaki, Norioki; Takeichi, Nobuhiko; Kiyobayashi, Tetsu

    2017-04-01

    A surface-roughened clad (S-clad) current collector significantly extends the cycle-life of the lithium ion negative electrode composed of a silicon micropowder and an aqueous binder. The high tensile strength of the S-clad is also proved to be important for improving the battery performance of the electrode by comparison to a surface-roughened pure Cu current collector. Moreover, adding 10 vol.% fluoroethylene carbonate to the electrolyte further extends the cycle-life of the Si electrode. The synergic effect of the high adhesive and tensile strength of the S-clad current collector as well as the electrolyte additive results in maintaining the reversible capacity of 1000 mA h g-1 for more than 1000 cycles, in which 1.0-1.2 mg cm-2 of the active material is loaded on the electrode.

  11. Experimental and DFT theoretical studies of surface enhanced Raman scattering effect on the silver nano arrays modified electrode.

    PubMed

    Zhang, Lisheng; Fang, Yan; Wang, Peijie

    2012-07-01

    Well-ordered silver nano arrays, prepared using anodic aluminum oxide (AAO) template by laser molecular beam epitaxy (L-MBE) method, were adhered to the work electrode using conductive adhesive to be a Surface-enhanced Raman scattering (SERS) substrate. Variable SERS signals of paranitrobenzoic acid (PNA) on the electrode modified with silver nano arrays were recorded with electric potential ranging from 0.1 to -0.5 V. The SERS spectra of PNA using DFT-B3PW91 with lanl2dz based on two models were calculated. It indicate that the adsorption orientation of probe molecules on the silver nano arrays with potential change of the electrode.

  12. An EMG-CT method using multiple surface electrodes in the forearm.

    PubMed

    Nakajima, Yasuhiro; Keeratihattayakorn, Saran; Yoshinari, Satoshi; Tadano, Shigeru

    2014-12-01

    Electromyography computed tomography (EMG-CT) method is proposed for visualizing the individual muscle activities in the human forearm. An EMG conduction model was formulated for reverse-estimation of muscle activities using EMG signals obtained with multi surface electrodes. The optimization process was calculated using sequential quadratic programming by comparing the estimated EMG values from the model with the measured values. The individual muscle activities in the deep region were estimated and used to produce an EMG tomographic image. For validation of the method, isometric contractions of finger muscles were examined for three subjects, applying a flexion load (4.9, 7.4 and 9.8 N) to the proximal interphalangeal joint of the middle finger. EMG signals in the forearm were recorded during the tasks using multiple surface electrodes, which were bound around the subject's forearm. The EMG-CT method illustrates the distribution of muscle activities within the forearm. The change in amplitude and area of activated muscles can be observed. The normalized muscle activities of all three subjects appear to increase monotonically with increases in the load. Kinesiologically, this method was able to estimate individual muscle activation values and could provide a novel tool for studying hand function and development of an examination for evaluating rehabilitation.

  13. Adsorption and surface dynamics of short DNA and LNA oligonucleotides on single-crystal Au(1 1 1) electrode surfaces

    NASA Astrophysics Data System (ADS)

    Wackerbarth, Hainer; Grubb, Mikala; Wengel, Jesper; Chorkendorff, Ib; Ulstrup, Jens

    2006-05-01

    We have studied the surface dynamics of a double-strand decanucleotide (HS-10AT L) with 10 adenine-thymine base pairs linked to a Au(1 1 1)-electrode surface via a hexamethylene thiol linker. The study is based on a combination of voltammetry, interfacial capacitance data, electrochemical in situ scanning tunnelling microscopy, and X-ray photoelectron spectroscopy. The thymine bases of the oligonucleotide are connected to furanoses locked in a C3'- endo configuration called LNA (locked nucleic acid). Hybridization in solution is effected prior to linking to the Au(1 1 1)-surface. The melting point of the linker-free locked decanucleotide, 10AT L is >63 °C. However, voltammetric reductive desorption of the adsorbed thiol-modified double-strand decanucleotide, HS-10AT L, gives almost the same charge as single-strand HS-10A, 29 ± 3 and 27 ± 5 μC cm -2, respectively. In situ STM after HS-10AT L-immobilization also gives images showing highly ordered domains, virtually indistinguishable from those of immobilized HS-10A. X-ray photoelectron spectroscopy gives an N/P ration of 5.0 for HS-10AT L in line with the expected value for single-strand HS-10A (5.0). All three sets of data suggest that HS-10AT L hybridized in solution is significantly dissociated on binding to the Au(1 1 1)-electrode surface. This points to an adsorption mechanism in which a stable high density of Au-S bonds is achieved but at the expense of significant unzipping of the more voluminous duplex form.

  14. Nonlinear Acoustics at the Air-Water Free Surface

    NASA Astrophysics Data System (ADS)

    Pree, Seth; Naranjo, Brian; Putterman, Seth

    2016-11-01

    According to linear acoustics, airborne sound incident on a water surface transmits only a tenth of a percent of its energy. This difficulty of transmitting energy across the water surface limits the feasibility of standoff ultrasound imaging. We propose to overcome this long standing problem by developing new methods of coupling into the medium at standoff. In particular, we believe that the acoustic nonlinearity of both the air and the medium may yield a range of effects in the vicinity of the surface permitting an efficient transmission of ultrasound from the air into the medium. The recent commercial availability of parametric speakers that deliver modulated 100kHz ultrasound at 135dB to nonlinearly generate music at 95dB provides an interesting platform with which to revisit the transmission of sound across acoustic impedance mismatches. We show results of experimental studies of the behavior of the air-water free surface when subjected to large amplitude acoustic pressures from the air. This work was supported by the ARO STIR program.

  15. An In Situ Surface Fourier Transform Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode

    DTIC Science & Technology

    1988-07-15

    Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode by DJ. Blackwood and S. Pons Prepared for publication in J...Secunt ClaMwfkation) An in situ Surface Fourier Transform Infrared Study of the Adsorption of Isoquinoline at a Stationary Mercury Electrode D.lc...SUBJECT TERMS (Continue on roverse if necessary and identify by block ’e’ 9ELD I GROUP I SUB-GROUP infrared spectroelectrochemistry ,adsorption, mercury I

  16. Oxidation of coal and coal pyrite mechanisms and influence on surface characteristics. [Coal pyrite electrodes

    SciTech Connect

    Doyle, F.M.

    1992-01-01

    The objective of this research is to develop a mechanistic understanding of the oxidation of coal and coal pyrite, and to correlate the intrinsic physical and chemical properties of these minerals, along with changes resulting from oxidation, with those surface properties that influence the behavior in physical cleaning processes. The results will provide fundamental insight into oxidation, in terms of the bulk and surface chemistry, the microstructure, and the semiconductor properties of the pyrite. During the eighth quarter, wet chemical and dry oxidation tests were done on Upper Freeport coal from the Troutville [number sign]2 Mine, Clearfield County, Pennsylvania. In addition electrochemical experiments were done on electrodes prepared from Upper Freeport coal pyrite and Pittsburgh coal pyrite samples provided by the US Bureau of Mines, Pittsburgh Research Center, Pennsylvania.

  17. Surface Second Harmonic Generation Studies of Stepped Ag(111) Electrode Surfaces

    DTIC Science & Technology

    1993-05-27

    whether SHG can distinguish between step and terrace sites on the surface by underpotential deposition of Pb2+ on these surfaces. These results will be...described in more detail in a later publication. Although lead underpotential deposition has been studied extensively by conventional electrochemical...methods, the assignment of the deposition processes to the observed three peaks in the v, nolayer deposition region continues to be of question. Current

  18. In situ surface potential evolution along Au/Gd:CeO2 electrode interfaces

    NASA Astrophysics Data System (ADS)

    Zhu, Jiaxin; Wang, Jiaying; Mebane, David S.; Nonnenmann, Stephen S.

    2017-04-01

    We present an investigation of electroactive Au/gadolinium doped ceria electrode interfaces under CO2/CO co-electrolysis environments using a combination of in situ high temperature scanning surface potential microscopy (HT-SSPM) and modified Poisson-Cahn (PC) models. Here charged surface adsorbate-oxygen vacancy interactions manifested in HT-SSPM potential profiles as small perturbations of opposite sign in reference to the applied biases. The positive deviation of surface potential on Au from applied cathodic biases is attributed to the work function difference between gold (ϕAu ˜ 5.31 eV) and graphitic carbon deposits (ϕC ˜ 5.0 eV) formed through CO disproportionation. The negative potential deviation from the applied anodic bias is attributed to negatively charged carboxylates. Results of the PC model confirmed the affinity of oxygen vacancies for the surface, thus supporting in situ experimental evidence of surface vacancy accumulation/depletion processes induced by cathodic/anodic biases.

  19. Emperor penguin body surfaces cool below air temperature

    PubMed Central

    McCafferty, D. J.; Gilbert, C.; Thierry, A.-M.; Currie, J.; Le Maho, Y.; Ancel, A.

    2013-01-01

    Emperor penguins Aptenodytes forsteri are able to survive the harsh Antarctic climate because of specialized anatomical, physiological and behavioural adaptations for minimizing heat loss. Heat transfer theory predicts that metabolic heat loss in this species will mostly depend on radiative and convective cooling. To examine this, thermal imaging of emperor penguins was undertaken at the breeding colony of Pointe Géologie in Terre Adélie (66°40′ S 140° 01′ E), Antarctica in June 2008. During clear sky conditions, most outer surfaces of the body were colder than surrounding sub-zero air owing to radiative cooling. In these conditions, the feather surface will paradoxically gain heat by convection from surrounding air. However, owing to the low thermal conductivity of plumage any heat transfer to the skin surface will be negligible. Future thermal imaging studies are likely to yield further insights into the adaptations of this species to the Antarctic climate. PMID:23466479

  20. Quantification of air plasma chemistry for surface disinfection

    NASA Astrophysics Data System (ADS)

    Pavlovich, Matthew J.; Clark, Douglas S.; Graves, David B.

    2014-12-01

    Atmospheric-pressure air plasmas, created by a variety of discharges, are promising sources of reactive species for the emerging field of plasma biotechnology because of their convenience and ability to operate at ambient conditions. One biological application of ambient-air plasma is microbial disinfection, and the ability of air plasmas to decontaminate both solid surfaces and liquid volumes has been thoroughly established in the literature. However, the mechanism of disinfection and which reactive species most strongly correlate with antimicrobial effects are still not well understood. We describe quantitative gas-phase measurements of plasma chemistry via infrared spectroscopy in confined volumes, focusing on air plasma generated via surface micro-discharge (SMD). Previously, it has been shown that gaseous chemistry is highly sensitive to operating conditions, and the measurements we describe here extend those findings. We quantify the gaseous concentrations of ozone (O3) and nitrogen oxides (NO and NO2, or NOx) throughout the established ‘regimes’ for SMD air plasma chemistry: the low-power, ozone-dominated mode; the high-power, nitrogen oxides-dominated mode; and the intermediate, unstable transition region. The results presented here are in good agreement with previously published experimental studies of aqueous chemistry and parameterized models of gaseous chemistry. The principal finding of the present study is the correlation of bacterial inactivation on dry surfaces with gaseous chemistry across these time and power regimes. Bacterial decontamination is most effective in ‘NOx mode’ and less effective in ‘ozone mode’, with the weakest antibacterial effects in the transition region. Our results underscore the dynamic nature of air plasma chemistry and the importance of careful chemical characterization of plasma devices intended for biological applications.

  1. Air-sea interactions in sea surface temperature frontal region

    NASA Astrophysics Data System (ADS)

    Pianezze, Joris; Redelsperger, Jean-Luc; Ardhuin, Fabrice; Reynaud, Thierry; Marié, Louis; Bouin, Marie-Noelle; Garnier, Valerie

    2015-04-01

    Representation of air-sea exchanges in coastal, regional and global models represent a challenge firstly due to the small scale of acting turbulent processes comparatively to the resolved scales of these models. Beyond this subgrid parameterization issue, a comprehensive understanding of air-sea interactions at the turbulent process scales is still lacking. Many successful efforts are dedicated to measure the energy and mass exchanges between atmosphere and ocean, including the effect of surface waves. In comparison less efforts are brought to understand the interactions between the atmospheric boundary layer and the oceanic mixing layer. In this regard, we are developing research mainly based on ideal and realistic numerical simulations which resolve very small scales (horizontal resolutions from 1 to 100 meters) in using grid nesting technics and coupled ocean-wave-atmosphere models. As a first step, the impact of marked gradients in sea surface temperatures (SST) on air-sea exchanges has been explored through realistic numerical simulations at 100m horizontal resolution. Results from simulations of a case observed during the FROMVAR experiment will be shown. The talk will mainly focus on the marked impact of SST front on the atmospheric boundary layer (stability and winds), the air-sea exchanges and surface parameters (rugosity, drag coefficient) Results will be also shown on the strong impact on the simulated atmosphere of small scale variability of SST field.

  2. Comparison of electrode reduction activities of Geobacter sulfurreducens and an enriched consortium in an air-cathode microbial fuel cell.

    PubMed

    Ishii, Shun'ichi; Watanabe, Kazuya; Yabuki, Soichi; Logan, Bruce E; Sekiguchi, Yuji

    2008-12-01

    An electricity-generating bacterium, Geobacter sulfurreducens PCA, was inoculated into a single-chamber, air-cathode microbial fuel cell (MFC) in order to determine the maximum electron transfer rate from bacteria to the anode. To create anodic reaction-limiting conditions, where electron transfer from bacteria to the anode is the rate-limiting step, anodes with electrogenic biofilms were reduced in size and tests were conducted using anodes of six different sizes. The smallest anode (7 cm(2), or 1.5 times larger than the cathode) achieved an anodic reaction-limiting condition as a result of a limited mass of bacteria on the electrode. Under these conditions, the limiting current density reached a maximum of 1,530 mA/m(2), and power density reached a maximum of 461 mW/m(2). Per-biomass efficiency of the electron transfer rate was constant at 32 fmol cell(-1) day(-1) (178 micromol g of protein(-1) min(-1)), a rate comparable to that with solid iron as the electron acceptor but lower than rates achieved with fumarate or soluble iron. In comparison, an enriched electricity-generating consortium reached 374 micromol g of protein(-1) min(-1) under the same conditions, suggesting that the consortium had a much greater capacity for electrode reduction. These results demonstrate that per-biomass electrode reduction rates (calculated by current density and biomass density on the anode) can be used to help make better comparisons of electrogenic activity in MFCs.

  3. Preliminary study on zinc-air battery using zinc regeneration electrolysis with propanol oxidation as a counter electrode reaction

    NASA Astrophysics Data System (ADS)

    Wen, Yue-Hua; Cheng, Jie; Ning, Shang-Qi; Yang, Yu-Sheng

    A zinc-air battery using zinc regeneration electrolysis with propanol oxidation as a counter electrode reaction is reported in this paper. It possesses functions of both zincate reduction and electrochemical preparation, showing the potential for increasing the electronic energy utilization. Charge/discharge tests and scanning electron microscopy (SEM) micrographs reveal that when a nickel sheet plated with the high-H 2-overpotential metal, cadmium, was used as the negative substrate electrode, the dendritic formation and hydrogen evolution are suppressed effectively, and granular zinc deposits become larger but relatively dense with the increase of charge time. The performance of batteries is favorable even if the charge time is as long as 5 h at the current density of 20 mA cm -2. Better discharge performance is achieved using a 'cavity-opening' configuration for the discharge cell rather than a 'gas-introducing' configuration. The highest energy efficiency is up to 59.2%. That is, the energy consumed by organic electro-synthesis can be recovered by 59.2%. Cyclic voltammograms show that the sintered nickel electrode exhibits a good electro-catalysis activity for the propanol oxidation. The increase of propanol concentration conduces to an enhancement in the organic electro-synthesis efficiency. The organic electro-synthesis current efficiency of 82% can be obtained.

  4. Self-assembly of virus-structured high surface area nanomaterials and their application as battery electrodes.

    PubMed

    Royston, Elizabeth; Ghosh, Ayan; Kofinas, Peter; Harris, Michael T; Culver, James N

    2008-02-05

    High area nickel and cobalt surfaces were assembled using modified Tobacco mosaic virus (TMV) templates. Rod-shaped TMV templates (300 x 18 nm) engineered to encode unique cysteine residues were self-assembled onto gold patterned surfaces in a vertically oriented fashion, producing a >10-fold increase in surface area. Electroless deposition of ionic metals onto surface-assembled virus templates produced uniform metal coatings up to 40 nm in thickness. Within a nickel-zinc battery system, the incorporation of virus-assembled electrode surfaces more than doubled the total electrode capacity. When combined, these findings demonstrate that surface-assembled virus templates provide a robust platform for the fabrication of oriented high surface area materials.

  5. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A.

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  6. A comparison of Pd and Au electrodes-based LiNbO3 surface acoustic wave devices

    NASA Astrophysics Data System (ADS)

    Liu, Bo; Mohammad, Mohammad Ali; Wang, Dan-Yang; Tian, Xiang-Guang; Tao, Lu-Qi; Yang, Yi; Ren, Tian-Ling

    2016-11-01

    We report the comparison of electrode metals for LiNbO3 surface acoustic wave (SAW) devices. Palladium (Pd) was systematically studied as a SAW electrode metal for the first time, compared with gold (Au). Simulations were first conducted to gain an understanding of the differences of the materials and the metallization ratio. Two sets of identical SAW devices were then fabricated using Au and Pd as electrodes with different electrode widths and same SAW period. The insertion losses, types of resonance mode, the resonance frequencies, peak amplitudes, quality factors and trends with different metallization ratios were systematically compared and analyzed. We found that Pd electrode devices only exhibit the parallel resonance frequency and have higher resonance frequency for both the first-order and third-order harmonics. Au electrode devices tend to have a smooth response and a quality factor two times higher than Pd. Both Pd and Au electrode devices have nearly identical electromechanical coupling coefficients, and the quality factor and third-order harmonics both improve with increasing metallization ratio.

  7. Development of interdigitated array electrodes with surface-enhanced Raman scattering functionality.

    PubMed

    Islam, Md Monirul; Ueno, Kosei; Juodkazis, Saulius; Yokota, Yukie; Misawa, Hiroaki

    2010-01-01

    Interdigitated array electrodes with surface-enhanced Raman scattering (SERS) functionality for in situ qualitative and quantitative analysis of electroactive species are demonstrated. Gold nanostructured interdigitated array electrodes (NIDAEs) were fabricated by electron beam lithography, and used for an electrochemical SERS study of K(3)[Fe(CN(6))] in aqueous KClO(4) solution in single and generation-collection modes. The generation-collection mode experiment showed amplification of the SERS band intensity for adsorbed ferricyanide ions at the negative end of the applied potential, while in single mode it was reduced to near zero. This new finding reveals that NIDAEs offer a new opportunity for analytical science by improving analytical sensitivity and detection ability of electroactive species. The electric fields accumulating at nanogaps are promising for manipulating linear and nonlinear optical phenomena. In addition, miniaturized NIDAEs are of great importance for developing lab-on-a-chip devices, and are useful for measurements within small space/volume domains, requiring only small amounts and/or concentrations of analytes.

  8. High specific surface gold electrode on polystyrene substrate: Characterization and application as DNA biosensor.

    PubMed

    Yang, Zhiliu; Liu, Yichen; Lu, Wei; Yuan, Qingpan; Wang, Wei; Pu, Qiaosheng; Yao, Bo

    2016-05-15

    In the past decades, many efforts have been made to improve the sensitivity and specificity of electrochemical DNA biosensors. However, it is still strongly required to develop disposable and reliable DNA biosensors for wide and practical application. In this article, we reported superior electrochemical properties of an integrated plastic-gold electrode (PGE) fabricated in-house by chemical plating on polystyrene substrate. PGEs were found having extremely high capacity of DNA immobilization compared with gold electrodes fabricated by standard sputtering based photolithography. Unique nano-structured surface was observed on PGEs through morphology techniques, which would to some extend give an explanation to higher capacity of DNA immobilization on PGEs. A probable mechanism of carboxylic acid produced on polystyrene substrate after exposure to UV irradiation was proposed and discussed for the first time. This biosensor was applied to detection and manipulate of DNA hybridization. Detection limit of 7.2×10(-11) M and 1-500 nM of linearity range was obtained.

  9. The electrode as organolithium reagent: catalyst-free covalent attachment of electrochemically active species to an azide-terminated glassy carbon electrode surface.

    PubMed

    Das, Atanu K; Engelhard, Mark H; Liu, Fei; Bullock, R Morris; Roberts, John A S

    2013-12-02

    The reaction of a lithium acetylide-ethylenediamine complex with azide-terminated glassy carbon surfaces affords 1,2,3-triazolyllithium surface groups that are active toward covalent C-C coupling reactions, including salt metathesis with an aliphatic halide and nucleophilic addition at an aldehyde. Surface ferrocenyl groups were introduced by reaction with (6-iodohexyl)ferrocene; the voltammetry of electrode samples shows narrow, symmetric peaks indicating uniform attachment. X-ray photoelectron and reflectance infrared spectroscopic data provide further support for the surface-attached products. Formation of the 1,2,3-triazolyllithium linkage requires neither a catalyst nor a strained alkyne. Coverages obtained by this route are similar to those obtained by the more common Cu(I)-catalyzed alkyne-azide coupling (CuAAC) of ethynylferrocene with surface azides. Preconditioning of the glassy carbon disk electrodes at ambient temperature under nitrogen affords coverages comparable to those reported with preconditioning at 1000 °C under hydrogen/nitrogen.

  10. Redox cycling effect on the surface-enhanced Raman scattering signal of crystal violet molecules at nanostructured interdigitated array electrodes.

    PubMed

    Islam, Md Monirul; Ueno, Kosei; Misawa, Hiroaki

    2010-01-01

    Nanostructured interdigitated array (IDA) electrodes with different inter-electrode spacing were demonstrated to improve the detection sensitivity of short-lived electroactive species and to follow interfacial dynamics by their surface-enhanced Raman scattering (SERS) functionality. Nanostructured IDA electrodes fabricated using electron beam lithography were used for an electrochemical SERS study of irreversible electroactive species, crystal violet (CV), in an aqueous KCl solution in single and generation-collection (GC) mode experiments. The GC mode enabled us to amplify the SERS intensity. An inter-electrode spacing dependent study found the maximum number of redox cycling, collection efficiency and amplification of the SERS intensity. Its SERS function disclosed the potential-dependent dynamics of CV molecules at the electrode surface, which was not observed in the redox current. Miniaturized nanostructured IDA electrodes are of great importance for developing lab on chip devices, and are useful for analyzing dynamical features within small space/volume domains, which require small amounts and/or concentration of analytes.

  11. Influence of air flow parameters on nanosecond repetitively pulsed discharges in a pin-annular electrode configuration

    NASA Astrophysics Data System (ADS)

    Heitz, Sylvain A.; Moeck, Jonas P.; Schuller, Thierry; Veynante, Denis; Lacoste, Deanna A.

    2016-04-01

    The effect of various air flow parameters on the plasma regimes of nanosecond repetitively pulsed (NRP) discharges is investigated at atmospheric pressure. The two electrodes are in a pin-annular configuration, transverse to the mean flow. The voltage pulses have amplitudes up to 15 kV, a duration of 10 ns and a repetition frequency ranging from 15 to 30 kHz. The NRP corona to NRP spark (C-S) regime transition and the NRP spark to NRP corona (S-C) regime transition are investigated for different steady and harmonically oscillating flows. First, the strong effect of a transverse flow on the C-S and S-C transitions, as reported in previous studies, is verified. Second, it is shown that the azimuthal flow imparted by a swirler does not affect the regime transition voltages. Finally, the influence of low frequency harmonic oscillations of the air flow, generated by a loudspeaker, is studied. A strong effect of frequency and amplitude of the incoming flow modulation on the NRP plasma regime is observed. Results are interpreted based on the cumulative effect of the NRP discharges and an analysis of the residence times of fluid particles in the inter-electrode region.

  12. The Role of Air-Electrode Structure on the Incorporation of Immiscible PFCs in Nonaqueous Li-O2 Battery.

    PubMed

    Balaish, Moran; Ein-Eli, Yair

    2017-03-22

    Perfluorocarbons (PFCs) are considered advantageous additives to nonaqueous Li-O2 battery due to their superior oxygen solubility and diffusivity compared to common battery electrolytes. Up to now, the main focus was concentrated on PFCs-electrolyte investigation; however, no special attention was granted to the role of carbon structure in the PFCs-Li-O2 system. In our current research, immiscible PFCs, rather than miscible fluorinated ethers, were added to activated carbon class air electrode due to their higher susceptibility toward O2(•-) attack and to their ability to shift the reaction from two-phase to an artificial three-phase reaction zone. The results showed superior battery performance upon PFCs addition at lower current density (0.05 mA cm(-2)) but unexpectedly failed to do so at higher current density (0.1 and 0.2 mA cm(-2)), where oxygen transport limitation is best illustrated. The last was a direct result of liquid-liquid displacement phenomenon occurring when the two immiscible liquids were introduced into the porous carbon medium. The investigation and role of carbon structure on the mechanism upon PFCs addition to Li-O2 system are suggested based on electrochemical characterization, wettability behavior studies, and the physical adsorption technique. Finally, we suggest an optimum air-electrode structure enabling the incorporation of immiscible PFCs in a nonaqueous Li-O2 battery.

  13. Graphene Oxide Involved Air-Controlled Electrospray for Uniform, Fast, Instantly Dry, and Binder-Free Electrode Fabrication.

    PubMed

    Fei, Ling; Yoo, Sang Ha; Villamayor, Rachel Ann R; Williams, Brian P; Gong, Seon Young; Park, Sunchan; Shin, Kyusoon; Joo, Yong Lak

    2017-03-22

    We report a facile air-controlled electrospray method to directly deposit binder-free active materials/graphene oxide (GO) onto current collectors. This method is inspired from an electrospinning process, and possesses all the advantages that electrospinning has such as low cost, easy scaling up, and simultaneous solvent evaporation during the spraying process. Moreover, the spray slurry is only a simple mixture of active materials and GO suspension in water, no binder polymer, organic solvent, and conductive carbon required. In our research, high-capacity Si nanoparticles (Si NP, 70-100 nm) and SiO microparticles (SiO MP, 3-10 μm) were selected to demonstrate the capability of this method to accommodate particles with different sizes. Their mixture with GO was sprayed onto a collector and then thermally annealed in an inert gas to obtain Si NP or SiO MP/reduced graphene oxide (RGO) binder-free electrodes. We are also able to directly deposit fairly large electrode sheets (e.g., 12 × 21 in.) upon the application requirement. To the best of our knowledge, this is the simplest approach to produce Si-related materials/RGO layered structures directly on current collector with controllable area and loading. Si and SiO MP/RGO are evaluated in both half and full lithium cells, showing good electrochemical performance. Prelithiation is also studied and gives a high first cycle Coulombic efficiency. In addition to Si-related materials, other materials with different shapes and sizes (e.g., MoO3 nanobelts, Sn/carbon nanofibers, and commercial sulfur particles) can also be sprayed. Beyond the preparation of battery electrodes, this approach can also be applied for other types of electrode preparation such as that of a supercapacitor, fuel cell, and solar cell.

  14. Biphilic Surfaces for Enhanced Water Collection from Humid Air

    NASA Astrophysics Data System (ADS)

    Benkoski, Jason; Gerasopoulos, Konstantinos; Luedeman, William

    Surface wettability plays an important role in water recovery, distillation, dehumidification, and heat transfer. The efficiency of each process depends on the rate of droplet nucleation, droplet growth, and mass transfer. Unfortunately, hydrophilic surfaces are good at nucleation but poor at shedding. Hydrophobic surfaces are the reverse. Many plants and animals overcome this tradeoff through biphilic surfaces with patterned wettability. For example, the Stenocara beetle uses hydrophilic patches on a superhydrophobic background to collect fog from air. Cribellate spiders similarly collect fog on their webs through periodic spindle-knot structures. In this study, we investigate the effects of wettability patterns on the rate of water collection from humid air. The steady state rate of water collection per unit area is measured as a function of undercooling, angle of inclination, water contact angle, hydrophilic patch size, patch spacing, area fraction, and patch height relative to the hydrophobic background. We then model each pattern by comparing the potential and kinetic energy of a droplet as it rolls downwards at a fixed angle. The results indicate that the design rules for collecting fog differ from those for condensation from humid air. The authors gratefully acknowledge the Office of Naval Research for financial support through Grant Number N00014-15-1-2107.

  15. Effects of pulsed potential on address electrode in a surface-discharge alternating-current plasma display panel

    NASA Astrophysics Data System (ADS)

    Ahn, Jeong Chull; Shintani, Youichi; Tachibana, Kunihide; Sakai, Tetsuo; Kosugi, Naoki

    2003-06-01

    The influence of pulsed potential application onto the address electrode of an ac-type plasma display panel was investigated from the observation of front and side views of Xe atom densities in the metastable (1s5) and excited (2p) states in a unit discharge cell by using microscopic laser absorption spectroscopy and optical emission spectroscopy. It was seen that a predischarge occurs between the address electrode and one of the sustain electrode worked as a preceding anode, which is a similar effect found previously by applying a higher sustain voltage. The predischarge partially erases the surface charge accumulated in the preceding pulse, but it induces a faster main sustain discharge, bowing towards the address electrode, and enhances the production efficiency of Xe(1s5) atoms, if the applied potential is within an optimal range.

  16. Metrological characteristics of the flat voltammetric electrode in time domain with a reversible electrochemical reaction running on the surface

    NASA Astrophysics Data System (ADS)

    Suchocki, Krzysztof

    2016-11-01

    The study deals with metrological characteristics of the flat voltammetric electrode used for determination of ions concentration by the DC voltammetric method, where a reversible reaction of electrochemical oxidation/reduction takes place on the surface. The analysis shows that such voltammetric electrode acts as a transducer of the first order, where the input signal is a concentration of marked ions in tested solution and the output signal is the current associated with a reversible reaction of oxidation / reduction. Metrological characteristics of such electrode in the time domain are determined by its sensitivity and time constant. The values of these parameters are defined by measurements of characteristics of the voltammetric electrode, polarization voltage and marked ions. To determine the effect of a particular volume of each of these parameters several numerical simulations are presented.

  17. Influence of surface states of CuInS2 quantum dots in quantum dots sensitized photo-electrodes

    NASA Astrophysics Data System (ADS)

    Peng, Zhuoyin; Liu, Yueli; Wu, Lei; Zhao, Yinghan; Chen, Keqiang; Chen, Wen

    2016-12-01

    Surface states are significant factor for the enhancement of electrochemical performance in CuInS2 quantum dot sensitized photo-electrodes. DDT, OLA, MPA, and S2- ligand capped CuInS2 quantum dot sensitized photo-electrodes are prepared by thermolysis, solvethermal and ligand-exchange processes, respectively, and their optical properties and photoelectrochemical properties are investigated. The S2- ligand enhances the UV-vis absorption and electron-hole separation property as well as the excellent charge transfer performance of the photo-electrodes, which is attributed to the fact that the atomic S2- ligand for the interfacial region of quantum dots may improve the electron transfer rate. These S2--capped CuInS2 quantum dot sensitized photo-electrodes exhibit the excellent photoelectrochemical efficiency and IPCE peak value, which is higher than that of the samples with DDT, OLA and MPA ligands.

  18. Bio-Decontamination of Water and Surfaces by DC Discharges in Atmospheric Air

    NASA Astrophysics Data System (ADS)

    Machala, Zdenko; Tarabová, Barbora; Pelach, Michal; Šipoldová, Zuzana; Hensel, Karol; Janda, Mário; Šikurová, Libuša

    Two types of DC-driven atmospheric air discharges, including a streamer corona and a transient spark with short high current pulses of limited energy, were employed for bio-decontamination of water and various surfaces (agar plates, plastic foils, human teeth) contaminated by bacteria or spores (Salmonella typhimurium, Bacillus cereus). Both discharges generate cold non-equilibrium plasma. The discharges combined with the electro-spraying of the treated water through the needle electrode lead to fast and efficient bio-decontamination. Experiments comparing direct and indirect plasma effects, oxidation stress measurements in the cell membranes, and chemical changes induced in the treated water enable assessment of the plasma agents being responsible for microbial inactivation. Radicals and reactive oxygen species seem to be dominant biocidal agents, although deeper understanding of the plasma-induced water chemistry and of the temporal evolution of the bio-inactivation processes is needed.

  19. Three-dimensionally ordered macroporous nitroxide polymer brush electrodes prepared by surface-initiated atom transfer polymerization for organic radical batteries.

    PubMed

    Lin, Chun-Hao; Chou, Wei-Jen; Lee, Jyh-Tsung

    2012-01-01

    The synthesis and electrochemical performance of three-dimensionally ordered macroporous (3DOM) nitroxide polymer brush electrodes for organic radical batteries are reported. The 3DOM electrodes are synthesized via polystyrene colloidal crystal templating with electropolymerization of polypyrrole, modification of surface initiator, and surface-initiated atom transfer radical polymerization. The discharge capacity of the 3DOM electrodes is proportional to the thickness of the inverse opal. The discharge capacity of the 3DOM electrode at a discharge rate of 5 C is 40 times higher than that of the planar electrode; its cycle-life performance exhibits 96.1% retention after 250 cycles.

  20. High surface area electrodes in ionic polymer transducers: Numerical and experimental investigations of the electro-chemical behavior

    NASA Astrophysics Data System (ADS)

    Akle, Barbar J.; Habchi, Wassim; Wallmersperger, Thomas; Akle, Etienne J.; Leo, Donald J.

    2011-04-01

    Ionomeric polymer transducer (IPT) is an electroactive polymer that has received considerable attention due to its ability to generate large bending strain (>5%) and moderate stress at low applied voltages (±2 V). Ionic polymer transducers consist of an ionomer, usually Nafion, sandwiched between two electrically conductive electrodes. A novel fabrication technique denoted as the direct assembly process (DAP) enabled controlled electrode architecture in ionic polymer transducers. A DAP built transducer consists of two high surface area electrodes made of electrically conducting particles uniformly distributed in an ionomer matrix sandwiching an ionomer membrane. The purpose of this paper is to investigate and simulate the effect of these high surface area particles on the electro-chemical response of an IPT. Theoretical investigations as well as experimental verifications are performed. The model used consists of a convection-diffusion equation describing the chemical field as well as a Poisson equation describing the electrical field. The two-dimensional model incorporates highly conductive particles randomly distributed in the electrode area. Traditionally, these kinds of electrodes were simulated with boundary conditions representing flat electrodes with a large dielectric permittivity at the polymer boundary. This model enables the design of electrodes with complicated geometrical patterns. In the experimental section, several transducers are fabricated using the DAP process on Nafion 117 membranes. The architecture of the high surface area electrodes in these samples is varied. The concentration of the high surface area RuO2 particles is varied from 30 vol% up to 60 vol% at a fixed thickness of 30 μm, while the overall thickness of the electrode is varied from 10 μm up to 40 μm at a fixed concentration of 45%. The flux and charge accumulation in the materials are measured experimentally and compared to the results of the numerical simulations. Trends of

  1. Memristive behavior of Al2O3 film with bottom electrode surface modified by Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Qin, Shu-Chao; Dong, Rui-Xin; Yan, Xun-Ling

    2014-09-01

    The memristive behavior of Al2O3-based device is significantly improved by introducing Ag nanoparticles (NPs). Inserting Ag NPs can effectively reduce the switching voltages, increase the resistance ratio (about 104) and enhance the sweep endurance (300 cycles). In particular, the stable switching properties are obtained by inserting an Ag NPs layer with an average diameter of 14 nm on the surface of bottom electrode, and the devices show a long retention time (more than 106 s) compared with the devices without Ag NPs. The switching mechanism is related to the oxygen-vacancy-based conducting filaments and the interfacial effect. The local enhancement and nonuniform distribution of electric field have the benefits to promote, induce and modulate the growth of conducting filaments, such as shape, location and orientation, which are responsible for the improvement performance of the devices.

  2. Memristive behavior of Al2O3 film with bottom electrode surface modified by Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Qin, Shu-Chao; Dong, Rui-Xin; Yan, Xun-Ling

    2015-02-01

    The memristive behavior of Al2O3-based device is significantly improved by introducing Ag nanoparticles (NPs). Inserting Ag NPs can effectively reduce the switching voltages, increase the resistance ratio (about 104) and enhance the sweep endurance (300 cycles). In particular, the stable switching properties are obtained by inserting an Ag NPs layer with an average diameter of 14 nm on the surface of bottom electrode, and the devices show a long retention time (more than 106 s) compared with the devices without Ag NPs. The switching mechanism is related to the oxygen-vacancy-based conducting filaments and the interfacial effect. The local enhancement and nonuniform distribution of electric field have the benefits to promote, induce and modulate the growth of conducting filaments, such as shape, location and orientation, which are responsible for the improvement performance of the devices.

  3. Surface morphology of titanium dioxide (TiO2) nanoparticles on aluminum interdigitated device electrodes (IDEs)

    NASA Astrophysics Data System (ADS)

    Azizah, N.; Hashim, U.; Arshad, M. K. Md.; Gopinath, Subash C. B.; Nadzirah, Sh.; Farehanim, M. A.; Fatin, M. F.; Ruslinda, A. R.; Ayub, R. M.

    2016-07-01

    Titanium dioxide (TiO2) nanoparticles based Interdigitated Device Electrodes (IDEs) Nanobiosensor device was developed for intracellular biochemical detection. Fabrication and characterization of Scanning Electron Microscopy (SEM) using IDE nanocoated with TiO2 was studied in this paper. SEM analysis was carried out at 10 kV acceleration volatege and a 9.8 mA emission current to compare IDE with and without TiO2 on the surface area. The simple fabrication process, high sensitivity, and fast response of the TiO2 based IDEs facilitate their applications in a wide range of areas. The small size of semiconductor TiO2 based IDE for sensitive, label-free, real time detection of a wide range of biological species could be explored in vivo diagnostics and array-based screening.

  4. Modular cryostat for ion trapping with surface-electrode ion traps

    NASA Astrophysics Data System (ADS)

    Vittorini, Grahame; Wright, Kenneth; Brown, Kenneth R.; Harter, Alexa W.; Doret, S. Charles

    2013-04-01

    We present a simple cryostat purpose built for use with surface-electrode ion traps, designed around an affordable, large cooling power commercial pulse tube refrigerator. A modular vacuum enclosure with a single vacuum space facilitates interior access and enables rapid turnaround and flexibility for future modifications. Long rectangular windows provide nearly 360° of optical access in the plane of the ion trap, while a circular bottom window near the trap enables NA 0.4 light collection without the need for in-vacuum optics. We evaluate the system's mechanical and thermal characteristics and we quantify ion trapping performance by trapping 40Ca+, finding small stray electric fields, long ion lifetimes, and low ion heating rates.

  5. Fast fabrication of copper nanowire transparent electrodes by a high intensity pulsed light sintering technique in air.

    PubMed

    Ding, Su; Jiu, Jinting; Tian, Yanhong; Sugahara, Tohru; Nagao, Shijo; Suganuma, Katsuaki

    2015-12-14

    Copper nanowire transparent electrodes have received increasing interest due to the low price and nearly equal electrical conductivity compared with other TEs based on silver nanowires and indium tin oxide (ITO). However, a post-treatment at high temperature in an inert atmosphere or a vacuum environment was necessary to improve the conductivity of Cu NW TEs due to the easy oxidation of copper in air atmosphere, which greatly cancelled out the low price advantage of Cu NWs. Here, a high intensity pulsed light technique was introduced to sinter and simultaneously deoxygenate these Cu NWs into a highly conductive network at room temperature in air. The strong light absorption capacity of Cu NWs enabled the welding of the nanowires at contact spots, as well as the removal of the thin layer of residual organic compounds, oxides and hydroxide of copper even in air. The Cu NW TE with a sheet resistance of 22.9 Ohm sq(-1) and a transparency of 81.8% at 550 nm has been successfully fabricated within only 6 milliseconds exposure treatment, which is superior to other films treated at high temperature in a hydrogen atmosphere. The HIPL process was simple, convenient and fast to fabricate easily oxidized Cu NW TEs in large scale in an air atmosphere, which will largely extend the application of cheap Cu NW TEs.

  6. Fundamental Studies of Surface Processes and Trace Analysis Using Solid Electrodes

    DTIC Science & Technology

    1989-11-01

    electrodes. Underpotential deposition (UPD) studies were undertaken at polycystalline silver electrodes. Using the electrochemical quartz crystal... Underpotential deposition (UPD) studies were undertaken at polycrystalline silver electrodes. Using the electrochemical quartz crystal microbalance, it...headings. PHYSICAL ELECTROC I] CAL STUDIES. Tracking Anion Expulsion During Underpotential Deposition of Lead at Silver Using the Quartz Mlerobalance

  7. The Electrode as Organolithium Reagent: Catalyst-Free Covalent Attachment of Electrochemically Active Species to an Azide-Terminated Glassy Carbon Electrode Surface

    SciTech Connect

    Das, Atanu K.; Engelhard, Mark H.; Liu, Fei; Bullock, R. Morris; Roberts, John A.

    2013-12-02

    Glassy carbon electrodes have been activated for modification with azide groups and subsequent coupling with ferrocenyl reagents by a catalyst-free route using lithium acetylide-ethylenediamine complex, and also by the more common Cu(I)-catalyzed alkyne-azide coupling (CuAAC) route, both affording high surface coverages. Electrodes were preconditioned at ambient temperature under nitrogen, and ferrocenyl surface coverages obtained by CuAAC were comparable to those reported with preconditioning at 1000 °C under hydrogen/nitrogen. The reaction of lithium acetylide-ethylenediamine with the azide-terminated electrode affords a 1,2,3-triazolyllithium-terminated surface that is active toward covalent C-C coupling reactions including displacement at an aliphatic halide and nucleophilic addition at an aldehyde. For example, surface ferrocenyl groups were introduced by reaction with (6-iodohexyl)ferrocene; the voltammetry shows narrow, symmetric peaks indicating uniform attachment. Coverages are competitive with those obtained by the CuAAC route. X-ray photoelectron spectroscopic data, presented for each synthetic step, are consistent with the proposed reactions. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. A portion of the research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  8. Global surface air temperature variations: 1851-1984

    SciTech Connect

    Jones, P.D.; Raper, S.C.B.; Kelly, P.M.

    1986-11-01

    Many attempts have been made to combine station surface air temperature data into an average for the Northern Hemisphere. Fewer attempts have been made for the Southern Hemisphere because of the unavailability of data from the Antarctic mainland before the 1950s and the uncertainty of making a hemispheric estimate based solely on land-based analyses for a hemisphere that is 80% ocean. Past estimates have been based largely on data from the World Weather Records (Smithsonian Institution, 1927, 1935, 1947, and U.S. Weather Bureau, 1959-82) and have been made without considerable effort to detect and correct station inhomogeneities. Better estimates for the Southern Hemisphere are now possible because of the availability of 30 years of climatological data from Antarctica. The mean monthly surface air temperature anomalies presented in this package for the than those previously published because of the incorporation of data previously hidden away in archives and the analysis of station homogeneity before estimation.

  9. Environmental dust effects on aluminum surfaces in humid air ambient

    PubMed Central

    Yilbas, Bekir Sami; Hassan, Ghassan; Ali, Haider; Al-Aqeeli, Nasser

    2017-01-01

    Environmental dusts settle on surfaces and influence the performance of concentrated solar energy harvesting devices, such as aluminum troughs. The characteristics of environmental dust and the effects of mud formed from the dust particles as a result of water condensing in humid air conditions on an aluminum wafer surface are examined. The dissolution of alkaline and alkaline earth compounds in water condensate form a chemically active mud liquid with pH 8.2. Due to gravity, the mud liquid settles at the interface of the mud and the aluminum surface while forming locally scattered patches of liquid films. Once the mud liquid dries, adhesion work to remove the dry mud increases significantly. The mud liquid gives rise to the formation of pinholes and local pit sites on the aluminum surface. Morphological changes due to pit sites and residues of the dry mud on the aluminum surface lower the surface reflection after the removal of the dry mud from the surface. The characteristics of the aluminum surface can address the dust/mud-related limitations of reflective surfaces and may have implications for the reductions in the efficiencies of solar concentrated power systems. PMID:28378798

  10. Environmental dust effects on aluminum surfaces in humid air ambient.

    PubMed

    Yilbas, Bekir Sami; Hassan, Ghassan; Ali, Haider; Al-Aqeeli, Nasser

    2017-04-05

    Environmental dusts settle on surfaces and influence the performance of concentrated solar energy harvesting devices, such as aluminum troughs. The characteristics of environmental dust and the effects of mud formed from the dust particles as a result of water condensing in humid air conditions on an aluminum wafer surface are examined. The dissolution of alkaline and alkaline earth compounds in water condensate form a chemically active mud liquid with pH 8.2. Due to gravity, the mud liquid settles at the interface of the mud and the aluminum surface while forming locally scattered patches of liquid films. Once the mud liquid dries, adhesion work to remove the dry mud increases significantly. The mud liquid gives rise to the formation of pinholes and local pit sites on the aluminum surface. Morphological changes due to pit sites and residues of the dry mud on the aluminum surface lower the surface reflection after the removal of the dry mud from the surface. The characteristics of the aluminum surface can address the dust/mud-related limitations of reflective surfaces and may have implications for the reductions in the efficiencies of solar concentrated power systems.

  11. A paradoxical method for NAD+/NADH accumulation on an electrode surface using a hydrophobic ionic liquid.

    PubMed

    Masuda, Miyuki; Motoyama, Yusuke; Kuwahara, Jun; Nakamura, Nobuhumi; Ohno, Hiroyuki

    2013-01-15

    In this communication, we describe a novel and facile method for the immobilization of NAD(+)/NADH on an electrode surface using a hydrophobic ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][Tf(2)N]). By taking advantage of the insolubility of NAD(+)/NADH in hydrophobic ionic liquids, it is expected that NAD(+)/NADH can be retained on the electrode's surface. Alcohol dehydrogenase (ADH) and NAD(+)/NADH were immobilized with a gelatin hydrogel on an electrode that was modified with an electropolymerized ruthenium complex containing 5-amino-1,10-phenanthroline (pAPRu) as a mediator for NADH oxidation. The (ADH, NAD(+))/pAPRu-immobilized electrode exhibited the electrocatalytic oxidation of ethanol in [C4mim][Tf(2)N]. The obtained catalytic current in [C4mim][Tf(2)N] was comparable to that in buffer solution containing NAD(+). It was confirmed by UV-vis spectroscopy that NAD(+) did not dissolve in the [C4mim][Tf(2)N] and was retained on the electrode's surface. Furthermore, we succeeded in constructing an ethanol/O(2) biofuel cell comprised of an (ADH, NAD(+))/pAPRu anode and a bilirubin oxidase cathode using [C4mim][Tf(2)N] as an electrolyte.

  12. Effects of surface tension and electrochemical reactions in Li-ion battery electrode nanoparticles

    NASA Astrophysics Data System (ADS)

    Stein, Peter; Zhao, Ying; Xu, Bai-Xiang

    2016-11-01

    The size- and shape-dependency of the chemo-mechanical behavior of spherical and ellipsoidal nanoparticles in Li-ion battery electrodes are investigated by a stress-assisted diffusion model and 3D finite element simulations. The model features surface tension, a direct coupling between diffusion and elasticity, concentration-dependent diffusivity, and a Butler-Volmer relation for the description of electrochemical reactions that is modified to account for mechanical effects. Simulation results on spherical particles reveal that surface tension causes additional pressure fields in the particles, shifting the stress state towards the compressive regime. This provides mechanical stabilization, allowing, in principle, for higher charge/discharge rates. However, due to this pressure the attainable lithiation for a given potential difference is reduced during insertion, whereas a higher amount of ions is given off during extraction. Ellipsoidal particles with an aspect ratio deviating from that of a sphere with the same volume expose a larger surface area to the intercalation reactions. Consequently, they exhibit accelerated (dis)charge rates. However, due to the enhanced pressure in regions with high curvature, the accessible capacity of ellipsoidal particles is less than that of spherical particles.

  13. Experimental progress with novel surface electrode ion trap structures for quantum information processing

    NASA Astrophysics Data System (ADS)

    Clark, Craig; Blain, Matthew; Benito, Francisco; Chou, Chin-Wen; Descour, Mike; Ellis, Rob; Haltli, Ray; Heller, Edwin; Kemme, Shanalyn; Sterk, Jon; Tabakov, Boyan; Tigges, Chris; Maunz, Peter; Stick, Daniel

    2013-05-01

    Segmented surface electrode ion traps are one of the most mature platforms among candidates for scalable quantum information processing. In this poster, an overview of current results from four specific projects will be presented. Two projects involve increased light collection from trapped ion for state detection and/or remote entangling of distant ions. The first involves cavity integration into a linear surface trap, and the second, involves integration of diffractive optical elements into a linear surface trap for increased light collection. Another project involves a trap with a ring geometry which could be used to trap long chains of equally spaced ions. Finally, we report on initial testing of a trap structure with vastly improved in-plane optical access. In this structure in-plane beams can be focused to less than 8 microns while keeping a distance of at least 5 beam radii to the trap structure. Along with these projects other relevant progress from Sandia National Laboratory's ion trap group will be presented. This work was supported by Sandia's Laboratory Directed Research and Development (LDRD) and the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  14. Effects of the surface mobility on the oxidation of adsorbed CO on platinum electrodes in alkaline media. The role of the adlayer and surface defects.

    PubMed

    Herrero, Enrique; Chen, Qing-Song; Hernández, Javier; Sun, Shi-Gang; Feliu, Juan M

    2011-10-06

    The oxidation of adsorbed CO on Pt single crystal electrodes has been studied in alkaline media. The surfaces used in this study were the Pt(111) electrode and vicinal stepped and kinked surfaces with (111) terraces. The kinked surfaces have either (110) steps broken by (100) kinks or (100) steps broken by (110) kinks and different kink densities. The voltammetric profiles for the CO stripping on those electrodes show peaks corresponding to the oxidation of CO on the (111) terraces, on the (100) steps/kinks and on the (110) steps/kinks at very distinctive potentials. Additionally, the stripping voltammograms always present a prewave. The analysis of the results with the different stepped and kinked surfaces indicates that the presence of the prewave is not associated with defects or kinks in the electrode surface. Also, the clear separation of the CO stripping process in different peak contributions indicates that the mobility of CO on the surface is very low. Using partial CO stripping experiments and studies at different pH, it has been proposed that the low mobility is a consequence of the negative absolute potential at which the adlayers are formed in alkaline media. Also, the surface diffusion coefficient for CO in these media has been estimated from the dependence of the stripping charge of the peaks with the scan rate of the voltammetry.

  15. Surface-catalyzed air oxidation of hydrazines: Environmental chamber studies

    NASA Technical Reports Server (NTRS)

    Kilduff, Jan E.; Davis, Dennis D.; Koontz, Steven L.

    1988-01-01

    The surface-catalyzed air oxidation reactions of fuel hydrazines were studied in a 6500-liter fluorocarbon-film chamber at 80 to 100 ppm concentrations. First-order rate constants for the reactions catalyzed by aluminum, water-damaged aluminum (Al/Al2O3), stainless steel 304L, galvanized steel and titanium plates with surface areas of 2 to 24 sq m were determined. With 23.8 sq m of Al/Al2O3 the surface-catalyzed air oxidation of hydrazine had a half-life of 2 hours, diimide (N2H2) was observed as an intermediate and traces of ammonia were present in the final product mixture. The Al/Al2O3 catalyzed oxidation of monomethylhydrazine yielded methyldiazine (HN = NCH3) as an intermediate and traces of methanol. Unsymmetrical dimethylhydrazine gave no detectable products. The relative reactivities of hydrazine, MMH and UDMH were 130 : 7.3 : 1.0, respectively. The rate constants for Al/Al2O3-catalyzed oxidation of hydrazine and MMH were proportional to the square of the surface area of the plates. Mechanisms for the surface-catalyzed oxidation of hydrazine and diimide and the formation of ammonia are proposed.

  16. Feasibility study of surface-modified carbon cloth electrodes using atmospheric pressure plasma jets for microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Chang, Shih-Hang; Liou, Jyun-Sian; Liu, Jung-Liang; Chiu, Yi-Fan; Xu, Chang-Han; Chen, Bor-Yann; Chen, Jian-Zhang

    2016-12-01

    This study investigated the surface and electrochemical properties of carbon cloth electrodes surface-modified by using atmospheric pressure plasma jets (APPJs) for applications involving microbial fuel cells (MFCs). APPJ treatment made the carbon cloth highly hydrophilic and did not introduce any observable cracks or flaws. MFCs configured with APPJ-treated carbon cloth electrodes exhibited electrochemical performance (maximum power density of 7.56 mW m-2) superior to that of MFCs configured with untreated carbon cloth electrodes (maximum power density of 2.38 mW m-2). This boost in performance can be attributed to the formation of abundant carboxyl and ammonium functional groups on the surface of APPJ-treated carbon cloth, which promoted the formation of anodic biofilms and the adhesion of bacteria, while facilitating the transfer of electrons from the bacteria to the electrodes. APPJ surface modification is non-toxic and environmentally friendly (no exogenous chemicals are required), which is particularly beneficial as the introduction of toxins might otherwise inhibit bacterial growth and metabolism. The APPJ surface modification process is rapid, cost-effective, and applicable to substrates covering a large area, making it ideal for the fabrication of large-scale MFCs and bioelectrochemical bioenergy devices.

  17. Flexible and Highly Biocompatible Nanofiber-Based Electrodes for Neural Surface Interfacing.

    PubMed

    Heo, Dong Nyoung; Kim, Han-Jun; Lee, Yi Jae; Heo, Min; Lee, Sang Jin; Lee, Donghyun; Do, Sun Hee; Lee, Soo Hyun; Kwon, Il Keun

    2017-03-28

    Polyimide (PI)-based electrodes have been widely used as flexible biosensors in implantable device applications for recording biological signals. However, the long-term quality of neural signals obtained from PI-based nerve electrodes tends to decrease due to nerve damage by neural tissue compression, mechanical mismatch, and insufficient fluid exchange between the neural tissue and electrodes. Here, we resolve these problems with a developed PI nanofiber (NF)-based nerve electrode for stable neural signal recording, which can be fabricated via electrospinning and inkjet printing. We demonstrate an NF-based nerve electrode that can be simply fabricated and easily applied due to its high permeability, flexibility, and biocompatibility. Furthermore, the electrode can record stable neural signals for extended periods of time, resulting in decreased mechanical mismatch, neural compression, and contact area. NF-based electrodes with highly flexible and body-fluid-permeable properties could enable future neural interfacing applications.

  18. A nonmonotonic dependence of standard rate constant on reorganization energy for heterogeneous electron transfer processes on electrode surface

    NASA Astrophysics Data System (ADS)

    Xu, Weilin; Li, Songtao; Zhou, Xiaochun; Xing, Wei; Huang, Mingyou; Lu, Tianhong; Liu, Changpeng

    2006-05-01

    In the present work a nonmonotonic dependence of standard rate constant (k0) on reorganization energy (λ) was discovered qualitatively from electron transfer (Marcus-Hush-Levich) theory for heterogeneous electron transfer processes on electrode surface. It was found that the nonmonotonic dependence of k0 on λ is another result, besides the disappearance of the famous Marcus inverted region, coming from the continuum of electronic states in electrode: with the increase of λ, the states for both Process I and Process II ET processes all vary from nonadiabatic to adiabatic state continuously, and the λ dependence of k0 for Process I is monotonic thoroughly, while for Process II on electrode surface the λ dependence of k0 could show a nonmonotonicity.

  19. Global Distribution and Variability of Surface Skin and Surface Air Temperatures as Depicted in the AIRS Version-6 Data Set

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Lee, Jae N.; Iredell, Lena

    2014-01-01

    In this presentation, we will briefly describe the significant improvements made in the AIRS Version-6 retrieval algorithm, especially as to how they affect retrieved surface skin and surface air temperatures. The global distribution of seasonal 1:30 AM and 1:30 PM local time 12 year climatologies of Ts,a will be presented for the first time. We will also present the spatial distribution of short term 12 year anomaly trends of Ts,a at 1:30 AM and 1:30 PM, as well as the spatial distribution of temporal correlations of Ts,a with the El Nino Index. It will be shown that there are significant differences between the behavior of 1:30 AM and 1:30 PM Ts,a anomalies in some arid land areas.

  20. Air-ground interface: Surface waves, surface impedance and acoustic-to-seismic coupling coefficient

    NASA Technical Reports Server (NTRS)

    Daigle, Gilles; Embleton, Tony

    1990-01-01

    In atmospheric acoustics, the subject of surface waves has been an area of discussion for many years. The existence of an acoustic surface wave is now well established theoretically. The mathematical solution for spherical wave propagation above an impedance boundary includes the possibility of a contribution that possesses all the standard properties for a surface wave. Surface waves exist when the surface is sufficiently porous, relative to its acoustical resistance, that it can influence the airborne particle velocity near the surface and reduce the phase velocity of sound waves in air at the surface. This traps some of the sound energy in the air to remain near the surface as it propagates. Above porous grounds, the existence of surface waves has eluded direct experimental confirmation (pulse experiments have failed to show a separate arrival expected from the reduced phase speed) and indirect evidence for its existence has appeared contradictory. The experimental evidence for the existence of an acoustical surface wave above porous boundaries is reviewed. Recent measurements including pulse experiments are also described. A few years ago the acoustic impedance of a grass-covered surface was measured in the frequency range 30 to 300 Hz. Here, further measurements on the same site are discussed. These measurements include core samples, a shallow refractive survey to determine the seismic velocities, and measurements of the acoustic-to-seismic coupling coefficient.

  1. In Vivo Airway Surface Liquid Cl− Analysis with Solid-State Electrodes

    PubMed Central

    Caldwell, Ray A.; Grubb, Barbara R.; Tarran, Robert; Boucher, Richard C.; Knowles, Michael R.; Barker, Pierre M.

    2002-01-01

    The pathogenesis of cystic fibrosis (CF) airways disease remains controversial. Hypotheses that link mutations in CFTR and defects in ion transport to CF lung disease predict that alterations in airway surface liquid (ASL) isotonic volume, or ion composition, are critically important. ASL [Cl−] is pivotal in discriminating between these hypotheses, but there is no consensus on this value given the difficulty in measuring [Cl−] in the “thin” ASL (∼30 μm) in vivo. Consequently, a miniaturized solid-state electrode with a shallow depth of immersion was constructed to measure ASL [Cl−] in vivo. In initial experiments, the electrode measured [Cl−] in physiologic salt solutions, small volume (7.6 μl) test solutions, and in in vitro cell culture models, with ≥93% accuracy. Based on discrepancies in reported values and/or absence of data, ASL Cl− measurements were made in the following airway regions and species. First, ASL [Cl−] was measured in normal human nasal cavity and averaged 117.3 ± 11.2 mM (n = 6). Second, ASL [Cl−] measured in large airway (tracheobronchial) regions were as follows: rabbit trachea and bronchus = 114.3 ± 1.8 mM; (n = 6) and 126.9 ± 1.7 mM; (n = 3), respectively; mouse trachea = 112.8 ± 4.2 mM (n = 13); and monkey bronchus = 112.3 ± 10.9 mM (n = 3). Third, Cl− measurements were made in small (1–2 mm) diameter airways of the rabbit (108.3 ± 7.1 mM, n = 5) and monkey (128.5 ± 6.8 mM, n = 3). The measured [Cl−], in excess of 100 mM throughout all airway regions tested in multiple species, is consistent with the isotonic volume hypothesis to describe ASL physiology. PMID:11773234

  2. Compositional analysis of passivating surface film formed on carbon electrode in organic electrolytic solution using in-situ spectroelectrochemical technique

    NASA Astrophysics Data System (ADS)

    Pyun, Su-Il

    1999-02-01

    In-situ spectroelectrochemical technique has been applied to investigate passivating surface film on porous carbon electrode and plasma enhanced chemical vapour deposited (PECVD) carbon film electrode in organic electrolytic solution consisting of ethylene carbonate (EC) and diethyl carbonate (DEC) solvent, and 1 M LiPF6 and LiAsF6. Water impurity with the concentration of 0 M, 0.02 M, 0.05 M, and 0.1 M H20 was added to 1 M LiPF6-EC/DEC solution. In-situ Fourier transform infra-red (FTIR) spectra of the surface film on both electrodes with the constituents of ROCO2Li, Li2CO3, and LixPFy suggested that the reduction of EC to ROCO2Li runs via a one-electron transfer pathway as a result of diffusion of water through the surface film, and then Li2CO3 formation proceeds simultaneously by the chemical reaction of ROCO2Li with water. From the measured potential dependence of the amount of the salt reduction products, it is suggested that the surface film formed in 1 M LiPF6EC/DEC solution gives a poorer passivity as compared with that formed in 1 M LiAsF6-EC/DEC solution, which is due to the considerable interference of LiPE6 salt reduction with the compact sedimentation of ROCO2Li on the electrode. In-situ FFIR spectra of the surface film showed that all the peak intensities of the three constituents significantly increase with increasing water content under application of the negative potentials with respect to open circuit potential (OCP). From these experimental results, the dependence of the passivity of the surface film on the carbon electrode on the water concentration of the electrolyte, as well as on the lithium salt type, was discussed in view of the salt and solvent reactivities.

  3. New Fabrication Method of Three-Electrode System on Cylindrical Capillary Surface as a Flexible Implantable Microneedle

    NASA Astrophysics Data System (ADS)

    Yang, Zhuoqing; Zhang, Yi; Itoh, Toshihiro; Maeda, Ryutaro

    2013-04-01

    In this present paper, a three-electrode system has been fabricated and integrated on the cylindrical polymer capillary surface by micromachining technology, which could be used as a flexible and implantable microneedle for glucose sensor application in future. A UV lithography system is successfully developed for high resolution alignment on cylindrical substrates. The multilayer alignment exposure for cylindrical polymer capillary substrate is for the first time realized utilizing the lithography system. The ±1 μm alignment precision has been realized on the 330 μm-outer diameter polymer capillary surface, on which the three-electrode structure consisting of two platinum electrodes and one Ag/AgCl reference electrode has been fabricated. The fabricated whole device as microneedle for glucose sensor application has been also characterized in 1 mol/L KCl and 0.02 mol/L K3Fe(CN)6 mix solution. The measured cyclic voltammetry curve shows that the prepared three-electrode system has a good redox property.

  4. Voltammetric studies of Azathioprine on the surface of graphite electrode modified with graphene nanosheets decorated with Ag nanoparticles.

    PubMed

    Asadian, Elham; Iraji Zad, Azam; Shahrokhian, Saeed

    2016-01-01

    By using graphene nanosheets decorated with Ag nanoparticles (AgNPs-G) as an effective approach for the surface modification of pyrolytic graphite electrode (PGE), a sensing platform was fabricated for the sensitive voltammetric determination of Azathioprine (Aza). The prepared AgNPs-G nanosheets were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-vis and Raman spectroscopy techniques. The electrochemical behavior of Aza was investigated by means of cyclic voltammetry. Comparing to the bare PGE, a remarkable enhancement was observed in the response characteristics of Aza on the surface of the modified electrode (AgNPs-G/PGE) as well as a noticeable decrease in its reduction overpotential. These results can be attributed to the incredible enlargement in the microscopic surface area of the electrode due to the presence of graphene nanosheets together with strong adsorption of Aza on its surface. The effect of experimental parameters such as accumulation time, the amount of modifier suspension and pH of the supporting electrolyte were also optimized toward obtaining the maximum sensitivity. Under the optimum conditions, the calibration curve studies demonstrated that the peak current increased linearly with Aza concentrations in the range of 7 × 10(-7) to 1 × 10(-4)mol L(-1) with the detection limit of 68 nM. Further experiments revealed that the modified electrode can be successfully applied for the accurate determination of Aza in pharmaceutical preparations.

  5. Ambient atmosphere-processable, printable Cu electrodes for flexible device applications: structural welding on a millisecond timescale of surface oxide-free Cu nanoparticles

    NASA Astrophysics Data System (ADS)

    Oh, Sang-Jin; Jo, Yejin; Lee, Eun Jung; Lee, Sun Sook; Kang, Young Hun; Jeon, Hye-Ji; Cho, Song Yun; Park, Jin-Seong; Seo, Yeong-Hui; Ryu, Beyong-Hwan; Choi, Youngmin; Jeong, Sunho

    2015-02-01

    Recently, various functional devices based on printing technologies have been of paramount interest, owing to their characteristic processing advantages along with excellent device performance. In particular, printable metallic electrodes have drawn attention in a variety of optoelectronic applications; however, research into printable metallic nanoparticles has been limited mainly to the case of an environmentally stable Ag phase. Despite its earth-abundance and highly conductive nature, the Cu phase, to date, has not been exploited as an ambient atmosphere-processable, printable material due to its critical oxidation problem in air. In this study, we demonstrate a facile route for generating highly conductive, flexible Cu electrodes in air by introducing the well-optimized photonic sintering at a time frame of 10-3 s, at which the photon energy, rather than conventional thermal energy, is instantly provided. It is elucidated here how the surface oxide-free, printed Cu particulate films undergo chemical structural/microstructural evolution depending on the instantly irradiated photon energy, and a successful demonstration is provided of large-area, flexible, printed Cu conductors on various substrates, including polyimide (PI), polyethersulfone (PES), polyethylene terephthalate (PET), and paper. The applicability of the resulting printed Cu electrodes is evaluated via implementation into both flexible capacitor devices and indium-gallium-zinc oxide (IGZO) flexible thin-film transistors.Recently, various functional devices based on printing technologies have been of paramount interest, owing to their characteristic processing advantages along with excellent device performance. In particular, printable metallic electrodes have drawn attention in a variety of optoelectronic applications; however, research into printable metallic nanoparticles has been limited mainly to the case of an environmentally stable Ag phase. Despite its earth-abundance and highly conductive

  6. Corrosion behavior of surface treated steel in liquid sodium negative electrode of liquid metal battery

    NASA Astrophysics Data System (ADS)

    Lee, Jeonghyeon; Shin, Sang Hun; Lee, Jung Ki; Choi, Sungyeol; Kim, Ji Hyun

    2016-03-01

    While liquid metal batteries are attractive options for grid-scale energy storage applications as they have flexible siting capacities and small footprints, the compatibility between structural materials such as current collectors and negative electrode such as sodium is one of major issues for liquid metal batteries. Non-metallic elements such as carbon, oxygen, and nitrogen in the liquid sodium influence the material behaviors of the cell construction materials in the battery system. In this study, the compatibility of structural materials with sodium is investigated in high temperature liquid sodium, and electrochemical impedance spectroscopy (EIS) is used to monitor in-situ the corrosion behavior at the surface of materials in sodium. Chemical vapor deposition (CVD) coatings of SiC and Si3N4 are applied as protective barriers against dissolution and corrosion on the steel surface. The results show that CVD coating of Si compounds can delay corrosion of steel in high temperature liquid sodium comparing to the result of as-received specimens, while SiC coating is more durable than Si3N4 coating in high temperature liquid sodium.

  7. High surface area electrode research. Final technical report, 10 July-31 December 1996

    SciTech Connect

    Roberson, S.; Davis, R.F.

    1996-12-31

    Molybdenum nitride (MOxN (x=1 or 2)) films, 15 micron thick, have been deposited via chemical vapor deposition (CVD) on 50 micron thick polycrystalline titanium substrates using molybdenum pentachloride (MoCl5) and NH3 in a cold wall reactor with vertical pancake heaters. The surface morphology of the films was slightly porous but did not contain the large cracks typical of high surface area MOxN films prepared by conversion of MoO3. Debye-Scherrer calculations indicate that the average particle size of the films was approximately 50 nm. The CvD MOxN films had a two-phase structure which appeared to be 60% d-MoN and 40% g-Mo2N. Energy dispersive X-ray (EDX) data did not reveal the presence of oxygen and chlorine in films deposited above 6000 C. Electrode evaluation via AC impedance spectroscopy and cyclic voltammetry indicates that CVD films were capacitive with a voltage stability of 0.9 volts in 6.4M KOH.

  8. Record low surface air temperature at Vostok station, Antarctica

    NASA Astrophysics Data System (ADS)

    Turner, John; Anderson, Phil; Lachlan-Cope, Tom; Colwell, Steve; Phillips, Tony; Kirchgaessner, AméLie; Marshall, Gareth J.; King, John C.; Bracegirdle, Tom; Vaughan, David G.; Lagun, Victor; Orr, Andrew

    2009-12-01

    The lowest recorded air temperature at the surface of the Earth was a measurement of -89.2°C made at Vostok station, Antarctica, at 0245 UT on 21 July 1983. Here we present the first detailed analysis of this event using meteorological reanalysis fields, in situ observations and satellite imagery. Surface temperatures at Vostok station in winter are highly variable on daily to interannual timescales as a result of the great sensitivity to intrusions of maritime air masses as Rossby wave activity changes around the continent. The record low temperature was measured following a near-linear cooling of over 30 K over a 10 day period from close to mean July temperatures. The event occurred because of five specific conditions that arose: (1) the temperature at the core of the midtropospheric vortex was at a near-record low value; (2) the center of the vortex moved close to the station; (3) an almost circular flow regime persisted around the station for a week resulting in very little warm air advection from lower latitudes; (4) surface wind speeds were low for the location; and (5) no cloud or diamond dust was reported above the station for a week, promoting the loss of heat to space via the emission of longwave radiation. We estimate that should a longer period of isolation occur the surface temperature at Vostok could drop to around -96°C. The higher site of Dome Argus is typically 5-6 K colder than Vostok so has the potential to record an even lower temperature.

  9. AirSWOT: An Airborne Platform for Surface Water Monitoring

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Moller, D.; Smith, L. C.; Pavelsky, T. M.; Alsdorf, D. E.

    2010-12-01

    The SWOT mission, expected to launch in 2020, will provide global measurements of surface water extent and elevation from which storage change and discharge can be derived. SWOT-like measurements are not routinely used by the hydrology community, and their optimal use and associated errors are areas of active research. The purpose of AirSWOT, a system that has been proposed to NASA’s Instrument Incubator Program, is to provide SWOT-like measurements to the hydrology and ocean community to be used to advance the understanding and use of SWOT data in the pre-launch phase. In the post-launch phase, AirSWOT will be used as the SWOT calibration/validation platform. The AirSWOT payload will consist of Kaspar, a multi-beam Ka-band radar interferometer able to produce elevations over a 5 km swath with centimetric precision. The absolute elevation accuracy of the AirSWOT system will be achieved with a combination of high precision Inertial Motion Units (IMUs), ground calibration points, and advanced calibration techniques utilizing a priori knowledge. It is expected that the accuracy of AirSWOT will exceed or match SWOT’s accuracy requirements. In addition to elevation measurements, the AirSWOT payload will include a near-infrared camera able to provide coincident high-resolution optical imagery of the water bodies imaged by the radar. In its initial hydrology deployments, AirSWOT will investigate four field sites: the Ohio-Mississippi confluence, the lower Atchafalaya River on the Mississippi River Delta, the Yukon River basin near Fairbanks, and the Sacramento River, California. The Ohio-Mississippi confluence is targeted for its large discharge, modest slope, and control structures that modulate Ohio but not Mississippi River slopes and elevations. The lower Atchafalaya River includes low slopes, wetlands with differing vegetation types, and some open lakes. Vegetation includes Cyprus forests, floating macrophytes, and grass marshes, all of which impact radar returns

  10. Hydrogen peroxide detection in wet air with a Prussian Blue based solid salt bridged three electrode system.

    PubMed

    Komkova, Maria A; Karyakina, Elena E; Marken, Frank; Karyakin, Arkady A

    2013-03-05

    We report on a novel electroanalytical system for hydrogen peroxide (H2O2) detection in humidity or droplets of aerosol, formed by air bubbling through a washing chamber; the resulting flow mimics the exhaled human breath. The system is based on a planar three-electrode structure (with a Prussian Blue based H2O2 transducer modified working electrode) bridged by a solid salt-saturated filament material (filter paper, cotton textile). Respective to the hydrogen peroxide content in the washing valve, the response of the aerosol-sensing system is linear in the concentration range of 0.1-10 μM, which overlaps the generally accepted H2O2 content in exhaled breath condensate (EBC), with the sensitivity of 8 A M(-1) cm(-2). The response to the upper limit of the calibration range is stable for more than 50 injection cycles recorded within 3 days. Both the stability and the suitable calibration range allow one to consider the reported aerosol-sensing system as a prototype for a simple (avoiding intermediate EBC collection) noninvasive diagnostic tool for pulmonary patients.

  11. Optical and electrical characteristics of a single surface DBD micro-discharge produced in atmospheric-pressure nitrogen and synthetic air

    NASA Astrophysics Data System (ADS)

    Šimek, M.; Prukner, V.; Schmidt, J.

    2011-05-01

    Basic opto-electrical characteristics of a single micro-discharge generated in a surface DBD reactor with a coplanar electrode arrangement were studied with nanosecond time resolution. The discharge electrode geometry based on machinable glass-ceramic was optimized in order to get a system free of the circulating dielectric liquids that are frequently used to insulate and cool metallic electrodes. The build-up and decay of UV-vis-NIR emission by a single micro-discharge unaffected by concurrent or preceding discharge events was inspected during the first 10 µs of the micro-discharge evolution in nitrogen and in synthetic air. Obtained emission waveforms show a great similarity between the surface and volume streamers. The streamer volume-averaged N2(A) concentrations of ~8 × 1014 cm-3 were estimated at t = 1 µs decay time and concentrations of ~(2-4) × 1015 cm-3 were estimated during the streamer propagation phase in nitrogen.

  12. Surface-treated carbon electrodes with modified potential of zero charge for capacitive deionization.

    PubMed

    Wu, Tingting; Wang, Gang; Zhan, Fei; Dong, Qiang; Ren, Qidi; Wang, Jianren; Qiu, Jieshan

    2016-04-15

    The potential of zero charge (Epzc) of electrodes can greatly influence the salt removal capacity, charge efficiency and cyclic stability of capacitive deionization (CDI). Thus optimizing the Epzc of CDI electrodes is of great importance. A simple strategy to negatively shift the Epzc of CDI electrodes by modifying commercial activated carbon with quaternized poly (4-vinylpyridine) (AC-QPVP) is reported in this work. The Epzc of the prepared AC-QPVP composite electrode is as negative as -0.745 V vs. Ag/AgCl. Benefiting from the optimized Epzc of electrodes, the asymmetric CDI cell which consists of the AC-QPVP electrode and a nitric acid treated activated carbon (AC-HNO3) electrode exhibits excellent CDI performance. For inverted CDI, the working potential window of the asymmetric CDI cell can reach 1.4 V, and its salt removal capacity can be as high as 9.6 mg/g. For extended voltage CDI, the salt removal capacity of the asymmetric CDI cell at 1.2/-1.2 V is 20.6 mg/g, which is comparable to that of membrane CDI using pristine activated carbon as the electrodes (19.5 mg/g). The present work provides a simple method to prepare highly positively charged CDI electrodes and may pave the way for the development of high-performance CDI cells.

  13. Is Air Temperature Enough to Predict Lake Surface Temperature?

    NASA Astrophysics Data System (ADS)

    Piccolroaz, S.; Toffolon, M.; Majone, B.

    2014-12-01

    Lake surface water (LST) is a key factor that controls most of the physical and ecological processes occurring in lakes. Reliable estimates are especially important in the light of recent studies, which revealed that inland water bodies are highly sensitive to climate, and are rapidly warming throughout the world. However, an accurate estimation of LST usually requires a significant amount of information that is not always available. In this work, we present an application of air2water, a lumped model that simulates LST as a function of air temperature only. In addition, air2water allows for a qualitative evaluation of the depth of the epilimnion during the annual stratification cycle. The model consists in a simplification of the complete heat budget of the well-mixed surface layer, and has a few parameters (from 4 to 8 depending on the version) that summarize the role of the different heat flux components. Model calibration requires only air and water temperature data, possibly covering sufficiently long historical periods in order to capture inter-annual variability and long-term trends. During the calibration procedure, the information included in input data is retrieved to directly inform model parameters, which can be used to classify the thermal behavior of the lake. In order to investigate how thermal dynamics are related to morphological features, the model has been applied to 14 temperate lakes characterized by different morphological and hydrological conditions, by different sources of temperature data (buoys, satellite), and by variable frequency of acquisition. A good agreement between observed and simulated LST has been achieved, with a RMSE in the order of 1°C, which is fully comparable to the performances of more complex process-based models. This application allowed for a deeper understanding of the thermal response of lakes as a function of their morphology, as well as for specific analyses as for example the investigation of the exceptional

  14. On-Surface Cross Coupling Methods for the Construction of Modified Electrode Assemblies with Tailored Morphologies †

    PubMed Central

    Gietter, Amber A. S.; Pupillo, Rachel C.; Yap, Glenn P. A.; Beebe, Thomas P.

    2014-01-01

    Controlling the molecular topology of electrode–catalyst interfaces is a critical factor in engineering devices with specific electron transport kinetics and catalytic efficiencies. As such, the development of rational methods for the modular construction of tailorable electrode surfaces with robust molecular wires (MWs) exhibiting well-defined molecular topologies, conductivities and morphologies is critical to the evolution and implementation of electrochemical arrays for sensing and catalysis. In response to this need, we have established modular on-surface Sonogashira and Glaser cross-coupling processes to synthetically install arrays of ferrocene-capped MWs onto electrochemically functionalized surfaces. These methods are of comparable convenience and efficiency to more commonly employed Huisgen methods. Furthermore, unlike the Huisgen reaction, this new surface functionalization chemistry generates modified electrodes that do not contain unwanted ancillary metal binding sites, while allowing the bridge between the ferrocenyl moiety and electrode surface to be synthetically tailored. Electrochemical and surface analytical characterization of these platforms demonstrate that the linker topology and connectivity influences the ferrocene redox potential and the kinetics of charge transport at the interface. PMID:25520772

  15. Changes in Impedance at the Electrode-Skin Interface of Surface EMG Electrodes During Long-Term EMG Recordings

    DTIC Science & Technology

    2001-10-25

    1Laboratoire de Modélisation et Sûreté des Systèmes, Université de Technologie de Troyes, Troyes, France 2Institut de Myologie , GH Pitié-Salpêtrière...participated gave their written informed consent. B. Electromyography Surface EMG signals were recorded from tibialis anterior on the right leg of each...P. Leffers, and J. Drukker, “Surface EMG of proximal leg muscles in neuromuscular patients and in healthy controls: relations to force and fatigue,” J

  16. Air-cooled, hydrogen-air fuel cell

    NASA Technical Reports Server (NTRS)

    Shelekhin, Alexander B. (Inventor); Bushnell, Calvin L. (Inventor); Pien, Michael S. (Inventor)

    1999-01-01

    An air-cooled, hydrogen-air solid polymer electrolyte (SPE) fuel cell with a membrane electrode assembly operatively associated with a fluid flow plate having at least one plate cooling channel extending through the plate and at least one air distribution hole extending from a surface of the cathode flow field into the plate cooling channel.

  17. Iron-Air Rechargeable Battery

    NASA Technical Reports Server (NTRS)

    Narayan, Sri R. (Inventor); Prakash, G.K. Surya (Inventor); Kindler, Andrew (Inventor)

    2014-01-01

    Embodiments include an iron-air rechargeable battery having a composite electrode including an iron electrode and a hydrogen electrode integrated therewith. An air electrode is spaced from the iron electrode and an electrolyte is provided in contact with the air electrode and the iron electrodes. Various additives and catalysts are disclosed with respect to the iron electrode, air electrode, and electrolyte for increasing battery efficiency and cycle life.

  18. Generation of large-scale, barrier-free diffuse plasmas in air at atmospheric pressure using array wire electrodes and nanosecond high-voltage pulses

    SciTech Connect

    Teng, Yun; Li, Lee Liu, Yun-Long; Liu, Lun; Liu, Minghai

    2014-10-15

    This paper introduces a method to generate large-scale diffuse plasmas by using a repetition nanosecond pulse generator and a parallel array wire-electrode configuration. We investigated barrier-free diffuse plasmas produced in the open air in parallel and cross-parallel array line-line electrode configurations. We found that, when the distance between the wire-electrode pair is small, the discharges were almost extinguished. Also, glow-like diffuse plasmas with little discharge weakening were obtained in an appropriate range of line-line distances and with a cathode-grounding cross-electrode configuration. As an example, we produced a large-scale, stable diffuse plasma with volumes as large as 18 × 15 × 15 cm{sup 3}, and this discharge region can be further expanded. Additionally, using optical and electrical measurements, we showed that the electron temperature was higher than the gas temperature, which was almost the same as room temperature. Also, an array of electrode configuration with more wire electrodes had helped to prevent the transition from diffuse discharge to arc discharge. Comparing the current waveforms of configurations with 1 cell and 9 cells, we found that adding cells significantly increased the conduction current and the electrical energy delivered in the electrode gaps.

  19. Generation of large-scale, barrier-free diffuse plasmas in air at atmospheric pressure using array wire electrodes and nanosecond high-voltage pulses

    NASA Astrophysics Data System (ADS)

    Teng, Yun; Li, Lee; Liu, Yun-Long; Liu, Lun; Liu, Minghai

    2014-10-01

    This paper introduces a method to generate large-scale diffuse plasmas by using a repetition nanosecond pulse generator and a parallel array wire-electrode configuration. We investigated barrier-free diffuse plasmas produced in the open air in parallel and cross-parallel array line-line electrode configurations. We found that, when the distance between the wire-electrode pair is small, the discharges were almost extinguished. Also, glow-like diffuse plasmas with little discharge weakening were obtained in an appropriate range of line-line distances and with a cathode-grounding cross-electrode configuration. As an example, we produced a large-scale, stable diffuse plasma with volumes as large as 18 × 15 × 15 cm3, and this discharge region can be further expanded. Additionally, using optical and electrical measurements, we showed that the electron temperature was higher than the gas temperature, which was almost the same as room temperature. Also, an array of electrode configuration with more wire electrodes had helped to prevent the transition from diffuse discharge to arc discharge. Comparing the current waveforms of configurations with 1 cell and 9 cells, we found that adding cells significantly increased the conduction current and the electrical energy delivered in the electrode gaps.

  20. Surface and Electrical Characterization of Ag/AgCl Pseudo-Reference Electrodes Manufactured with Commercially Available PCB Technologies

    PubMed Central

    Moschou, Despina; Trantidou, Tatiana; Regoutz, Anna; Carta, Daniela; Morgan, Hywel; Prodromakis, Themistoklis

    2015-01-01

    Lab-on-Chip is a technology that could potentially revolutionize medical Point-of-Care diagnostics. Considerable research effort is focused towards innovating production technologies that will make commercial upscaling financially viable. Printed circuit board manufacturing techniques offer several prospects in this field. Here, we present a novel approach to manufacturing Printed Circuit Board (PCB)-based Ag/AgCl reference electrodes, an essential component of biosensors. Our prototypes were characterized both structurally and electrically. Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS) were employed to evaluate the electrode surface characteristics. Electrical characterization was performed to determine stability and pH dependency. Finally, we demonstrate utilization along with PCB pH sensors, as a step towards a fully integrated PCB platform, comparing performance with discrete commercial reference electrodes. PMID:26213940

  1. Effect of surface modifications on ZnO nanorod arrays electrode for dye-sensitized solar cells.

    PubMed

    Qin, Zi; Huang, Yunhua; Liao, Qingliang; Zhang, Zheng; Zhang, Yue

    2012-01-01

    High quality, large area and well-oriented ZnO nanorod arrays electrodes were successfully synthesized on conductive transparent oxide substrates by low-temperature hydrothermal methods for dye-sensitized solar cells. Aiming at getting further enhancement and study the effect of the surface modification on cell performance, ZnO thin film and ZnO nanoparticles are carried out to modify the as-grown ZnO nanorod arrays. The morphology, structure and photoluminescence property of the modified ZnO electrodes are characterized in detail. Furthermore, the I-V characterization result shows that these modification methods have distinct influences on the performance of the cell based on ZnO nanorod arrays electrode. The overall conversion efficiency can be optimized by choosing the suitable modification route.

  2. Surface study of stainless steel electrode deposition from soil electrokinetic (EK) treatment using X-ray photoelectron spectroscopy (XPS)

    SciTech Connect

    Embong, Zaidi; Johar, Saffuwan; Tajudin, Saiful Azhar Ahmad; Sahdan, Mohd Zainizan

    2015-04-29

    Electrokinetic (EK) remediation relies upon application of a low-intensity direct current through the soil between stainless steel electrodes that are divided into a cathode array and an anode array. This mobilizes charged species, causing ions and water to move toward the electrodes. Metal ions and positively charged organic compounds move toward the cathode. Anions such as chloride, fluoride, nitrate, and negatively charged organic compounds move toward the anode. Here, this remediation techniques lead to a formation of a deposition at the both cathode and anode surface that mainly contributed byanion and cation from the remediated soil. In this research, Renggam-Jerangau soil species (HaplicAcrisol + RhodicFerralsol) with a surveymeter reading of 38.0 ± 3.9 μR/hr has been investigation in order to study the mobility of the anion and cation under the influence electric field. Prior to the EK treatment, the elemental composition of the soil and the stainless steel electrode are measured using XRF analyses. Next, the soil sample is remediated at a constant electric potential of 30 V within an hour of treatment period. A surface study for the deposition layer of the cathode and anode using X-ray Photoelectron spectroscopy (XPS) revealed that a narrow photoelectron signal from oxygen O 1s, carbon, C 1s silica, Si 2p, aluminium, Al 2p and chromium, Cr 2p exhibited on the electrode surface and indicate that a different in photoelectron intensity for each element on both electrode surface. In this paper, the mechanism of Si{sup 2+} and Al{sup 2+} cation mobility under the influence of voltage potential between the cathode and anode will be discussed in detail.

  3. Boron-doped diamond semiconductor electrodes: Efficient photoelectrochemical CO2 reduction through surface modification

    NASA Astrophysics Data System (ADS)

    Roy, Nitish; Hirano, Yuiri; Kuriyama, Haruo; Sudhagar, Pitchaimuthu; Suzuki, Norihiro; Katsumata, Ken-Ichi; Nakata, Kazuya; Kondo, Takeshi; Yuasa, Makoto; Serizawa, Izumi; Takayama, Tomoaki; Kudo, Akihiko; Fujishima, Akira; Terashima, Chiaki

    2016-11-01

    Competitive hydrogen evolution and multiple proton-coupled electron transfer reactions limit photoelectrochemical CO2 reduction in aqueous electrolyte. Here, oxygen-terminated lightly boron-doped diamond (BDDL) thin films were synthesized as a semiconductor electron source to accelerate CO2 reduction. However, BDDL alone could not stabilize the intermediates of CO2 reduction, yielding a negligible amount of reduction products. Silver nanoparticles were then deposited on BDDL because of their selective electrochemical CO2 reduction ability. Excellent selectivity (estimated CO:H2 mass ratio of 318:1) and recyclability (stable for five cycles of 3 h each) for photoelectrochemical CO2 reduction were obtained for the optimum silver nanoparticle-modified BDDL electrode at ‑1.1 V vs. RHE under 222-nm irradiation. The high efficiency and stability of this catalyst are ascribed to the in situ photoactivation of the BDDL surface during the photoelectrochemical reaction. The present work reveals the potential of BDDL as a high-energy electron source for use with co-catalysts in photochemical conversion.

  4. Electrical characterization of gold and platinum thin film electrodes with polyaniline modified surfaces

    NASA Astrophysics Data System (ADS)

    Aggas, John Richard

    Recent studies into soft organic electronics have burgeoned as a result of discoveries of conducting polymers such as polyaniline, polythiophene, and polypyrrole. However, in order to make these conducting polymers suitable for in vivo soft organic electronics, they must be developed so that they can be biocompatible and provide accurate sensing. Chitosan, a naturally occurring polymer structure found in exoskeletons of crustaceans, has been studied for its biocompatible properties. Composites of polyaniline (PAn), an intrinsically conductive polymer (ICP) and chitosan (Chi), a biopolymer, were developed and applied to gold and platinum Thin Film Electrode (TFE) devices. Electropolymerization and drop cast deposition were utilized to modify TFEs with a thin film of PAn or PAn-Chi composite. The impedance response over a spectrum of frequencies was studied for blank control TFEs, platinized TFEs, and platinized TFEs with various polyaniline coatings. Impedance measurements were taken in dry environments, DI Water, and in buffers such as PBS, and HEPES. Current-Voltage (I-V) characterization was used to study the current response and SEM imaging was used to study the surface topography. Resistance was measured for PAn modified unplatinized gold TFEs with varying amounts of incorporated chitosan. Impedance measurements of control and platinized TFEs yielded results similar to a low pass filter. Due to the conductive nature of polyaniline, the impedance of TFEs decreased substantially after poylaniline deposition. Measured resistance values for polyaniline and chitosan composites on TFEs revealed a window of concentrations of incorporated chitosan to lower resistance.

  5. Boron-doped diamond semiconductor electrodes: Efficient photoelectrochemical CO2 reduction through surface modification

    PubMed Central

    Roy, Nitish; Hirano, Yuiri; Kuriyama, Haruo; Sudhagar, Pitchaimuthu; Suzuki, Norihiro; Katsumata, Ken-ichi; Nakata, Kazuya; Kondo, Takeshi; Yuasa, Makoto; Serizawa, Izumi; Takayama, Tomoaki; Kudo, Akihiko; Fujishima, Akira; Terashima, Chiaki

    2016-01-01

    Competitive hydrogen evolution and multiple proton-coupled electron transfer reactions limit photoelectrochemical CO2 reduction in aqueous electrolyte. Here, oxygen-terminated lightly boron-doped diamond (BDDL) thin films were synthesized as a semiconductor electron source to accelerate CO2 reduction. However, BDDL alone could not stabilize the intermediates of CO2 reduction, yielding a negligible amount of reduction products. Silver nanoparticles were then deposited on BDDL because of their selective electrochemical CO2 reduction ability. Excellent selectivity (estimated CO:H2 mass ratio of 318:1) and recyclability (stable for five cycles of 3 h each) for photoelectrochemical CO2 reduction were obtained for the optimum silver nanoparticle-modified BDDL electrode at −1.1 V vs. RHE under 222-nm irradiation. The high efficiency and stability of this catalyst are ascribed to the in situ photoactivation of the BDDL surface during the photoelectrochemical reaction. The present work reveals the potential of BDDL as a high-energy electron source for use with co-catalysts in photochemical conversion. PMID:27892544

  6. Morphology-dependent NiO modified glassy carbon electrode surface for lead(II) and cadmium(II) detection

    NASA Astrophysics Data System (ADS)

    Li, Xuewu; Wen, Hao; Fu, Qiang; Peng, Dai; Yu, Jingui; Zhang, Qiaoxin; Huang, Xingjiu

    2016-02-01

    Glassy carbon electrode (GCE) surfaces have been modified with different NiO morphologies consisting of rods NiO, flakes NiO and balls NiO prepared via the hydrothermal synthesis method for Pb(II) and Cd(II) detection by using the square wave anodic stripping voltammetry (SWASV). Meanwhile, the typical cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), BET surface area and adsorption property of the modified electrode surfaces have been investigated to evaluate their electrochemical detection effect. Results show that balls NiO modified GCE can get the optimal detection ability for its highest detection sensitivity to Pb(II) (13.46 A M-1) and Cd(II) (5.10 A M-1), the lowest detection limit (DL) to Pb(II) (0.08 μM) and Cd(II) (0.07 μM) as well as the superior linear relativity. In addition, an enhanced current at redox peaks, lower electron transfer resistance, larger BET surface area and stronger adsorption capacity have been confirmed for the balls NiO modified GCE surface. Finally, excellent stability and reproducibility of balls NiO modified electrodes for Pb(II) and Cd(II) detection have also been proved via the SWASV responses.

  7. Surface Engineering and Design Strategy for Surface-Amorphized TiO2@Graphene Hybrids for High Power Li-Ion Battery Electrodes.

    PubMed

    Zhou, Tengfei; Zheng, Yang; Gao, Hong; Min, Shudi; Li, Sean; Liu, Hua Kun; Guo, Zaiping

    2015-09-01

    Surface amorphization provides unprecedented opportunities for altering and tuning material properties. Surface-amorphized TiO2@graphene synthesized using a designed low temperature-phase transformation technique exhibits significantly improved rate capability compared to well-crystallized TiO2@graphene and bare TiO2 electrodes. These improvements facilitates lithium-ion transport in both insertion and extraction processes and enhance electrolyte absorption capability.

  8. Investigation of ammonia air-surface exchange processes in a ...

    EPA Pesticide Factsheets

    Recent assessments of atmospheric deposition in North America note the increasing importance of reduced (NHx = NH3 + NH4+) forms of nitrogen (N) relative to oxidized forms. This shift in in the composition of inorganic nitrogen deposition has both ecological and policy implications. Deposition budgets developed from inferential models applied at the landscape scale, as well as regional and global chemical transport models, indicate that NH3 dry deposition contributes a significant portion of inorganic N deposition in many areas. However, the bidirectional NH3 flux algorithms employed in these models have not been extensively evaluated for North American conditions (e.g, atmospheric chemistry, meteorology, biogeochemistry). Further understanding of the processes controlling NH3 air-surface exchange in natural systems is critically needed. Based on preliminary results from the Southern Appalachian Nitrogen Deposition Study (SANDS), this presentation examines processes of NH3 air-surface exchange in a deciduous montane forest at the Coweeta Hydrologic Laboratory in western North Carolina. A combination of measurements and modeling are used to investigate net fluxes of NH3 above the forest and sources and sinks of NH3 within the canopy and forest floor. Measurements of biogeochemical NH4+ pools are used to characterize emission potential and NH3 compensation points of canopy foliage (i.e., green vegetation), leaf litter, and soil and their relation to NH3 fluxes

  9. Evaluation of entrance surface air kerma in pediatric chest radiography

    NASA Astrophysics Data System (ADS)

    Porto, L.; Lunelli, N.; Paschuk, S.; Oliveira, A.; Ferreira, J. L.; Schelin, H.; Miguel, C.; Denyak, V.; Kmiecik, C.; Tilly, J.; Khoury, H.

    2014-11-01

    The objective of this study was to evaluate the entrance surface air kerma in pediatric chest radiography. An evaluation of 301 radiographical examinations in anterior-posterior (AP) and posterior-anterior (PA) (166 examinations) and lateral (LAT) (135 examinations) projections was performed. The analyses were performed on patients grouped by age; the groups included ages 0-1 y, 1-5 y, 5-10 y, and 10-15 y. The entrance surface air kerma was determined with DoseCal software (Radiological Protection Center of Saint George's Hospital, London) and thermoluminescent dosimeters. Two different exposure techniques were compared. The doses received by patients who had undergone LAT examinations were 40% higher, on average, those in AP/PA examinations because of the difference in tube voltage. A large high-dose “tail” was observed for children up to 5 y old. An increase in tube potential and corresponding decrease in current lead to a significant dose reduction. The difference between the average dose values for different age ranges was not practically observed, implying that the exposure techniques are still not optimal. Exposure doses received using the higher tube voltage and lower current-time product correspond to the international diagnostic reference levels.

  10. Supersonic moist air jet impingements on flat surface

    NASA Astrophysics Data System (ADS)

    Alam, Miah Md. Ashraful; Matsuo, Shigeru; Setoguchi, Toshiaki

    2010-02-01

    Pronounced aeroacoustic resonances are exhibited in the flowfield where a jet emerges from an orifice or a nozzle and impinges on a solid surface. One instance where such resonances are produced is in a high speed jet impingement, such as in the space launch vehicle systems, jet-engine exhaust impingement, and in the short take-off and vertical landing (STOVL) aircraft, etc. A highly unsteady flowfield leading to a drastic increase of noise level with very high dynamic pressure and thermal loads are noticed on nearby surfaces results dramatic lift loss, severe ground erosion and hot gas ingestion to the inlet in the jet engines. This highly unsteady behavior of the impinging jets is due to a feedback loop between the fluid and acoustic fields. In actual jet flow, the working gas may contain condensable gas such as steam or moist air. In these cases, the non-equilibrium condensation may occur at the region between nozzle exit and an object. The jet flow with non-equilibrium condensation may be quite different from that without condensation. Therefore, in this study, the effect of the non-equilibrium condensation of moist air on the axisymmetric under-expanded supersonic impinging jet on a vertical flat plate was investigated numerically.

  11. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  12. Air-sea fluxes and surface layer turbulence around a sea surface temperature front

    NASA Technical Reports Server (NTRS)

    Friehe, C. A.; Shaw, W. J.; Davidson, K. L.; Rogers, D. P.; Large, W. G.; Stage, S. A.; Crescenti, G. H.; Khalsa, S. J. S.; Greenhut, G. K.; Li, F.

    1991-01-01

    The observed effects of sharp changes in sea surface temperature (SST) on the air-sea fluxes, surface roughness, and the turbulence structure in the surface layer and the marine atmospheric boundary layer are discussed. In situ flux and turbulence observations were carried out from three aircraft and two ships within the FASINEX framework. Three other aircraft used remote sensors to measure waves, microwave backscatter, and lidar signatures of cloud tops. Descriptions of the techniques, intercomparison of aircraft and ship flux data, and use of different methods for analyzing the fluxes from the aircraft data are described. Changing synoptic weather on three successive days yielded cases of wind direction both approximately parallel and perpendicular to a surface temperature front. For the wind perpendicular to the front, wind over both cold-to-warm and warm-to-cold surface temperatures occurred. Model results consistent with the observations suggest that an internal boundary layer forms at the SST.

  13. In Situ-Grown ZnCo2O4 on Single-Walled Carbon Nanotubes as Air Electrode Materials for Rechargeable Lithium–Oxygen Batteries

    SciTech Connect

    Liu, Bin; Xu, Wu; Yan, Pengfei; Bhattacharya, Priyanka; Cao, Ruiguo; Bowden, Mark E.; Engelhard, Mark H.; Wang, Chong M.; Zhang, Jiguang

    2015-10-12

    Although lithium-oxygen (Li-O2) batteries have great potential to be used as one of the next generation energy storage systems due to their ultrahigh theoretical specific energy, there are still many significant barriers before their practical applications. These barriers include electrolyte and electrode instability, poor ORR/OER efficiency and cycling capability, etc. Development of a highly efficient catalyst will not only enhance ORR/OER efficiency, it may also improve the stability of electrolyte because the reduced charge voltage. Here we report the synthesis of nano-sheet-assembled ZnCo2O4 spheres/single walled carbon nanotubes (ZCO/SWCNTs) composites as high performance air electrode materials for Li-O2 batteries. The ZCO catalyzed SWCNTs electrodes delivered high discharge capacities, decreased the onset of oxygen evolution reaction by 0.9 V during charge processes, and led to more stable cycling stability. These results indicate that ZCO/SWCNTs composite can be used as highly efficient air electrode for oxygen reduction and evolution reactions. The highly enhanced catalytic activity by uniformly dispersed ZnCo2O4 catalyst on nanostructured electrodes is expected to inspire

  14. Coupled modeling of water transport and air-droplet interaction in the electrode of a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Esposito, Angelo; Pianese, Cesare; Guezennec, Yann G.

    In this work, an accurate and computationally fast model for liquid water transport within a proton exchange membrane fuel cell (PEMFC) electrode is developed by lumping the space-dependence of the relevant variables. Capillarity is considered as the main transport mechanism within the gas diffusion layer (GDL). The novelty of the model lies in the coupled simulation of the water transport at the interface between gas diffusion layer and gas flow channel (GFC). This is achieved with a phenomenological description of the process that allows its simulation with relative simplicity. Moreover, a detailed two-dimensional visualization of such interface is achieved via geometric simulation of water droplets formation, growth, coalescence and detachment on the surface of the GDL. The model is useful for optimization analysis oriented to both PEMFC design and balance of plant. Furthermore, the accomplishment of reduced computational time and good accuracy makes the model suitable for control strategy implementation to ensure PEM fuel cells operation within optimal electrode water content.

  15. Impact of Atlantic sea surface temperatures on the warmest global surface air temperature of 1998

    NASA Astrophysics Data System (ADS)

    Lu, Riyu

    2005-03-01

    The year 1998 is the warmest year in the record of instrumental measurements. In this study, an atmospheric general circulation model is used to investigate the role of sea surface temperatures (SSTs) in this warmth, with a focus on the role of the Atlantic Ocean. The model forced with the observed global SSTs captures the main features of land surface air temperature anomalies in 1998. A sensitivity experiment shows that in comparison with the global SST anomalies, the Atlantic SST anomalies can explain 35% of the global mean surface air temperature (GMAT) anomaly, and 57% of the land surface air temperature anomaly in 1998. The mechanisms through which the Atlantic Ocean influences the GMAT are likely different from season to season. Possible detailed mechanisms involve the impact of SST anomalies on local convection in the tropical Atlantic region, the consequent excitation of a Rossby wave response that propagates into the North Atlantic and the Eurasian continent in winter and spring, and the consequent changes in tropical Walker circulation in summer and autumn that induce changes in convection over the tropical Pacific. This in turn affects climate in Asia and Australia. The important role of the Atlantic Ocean suggests that attention should be paid not only to the tropical Pacific Ocean, but also to the tropical Atlantic Ocean in understanding the GMAT variability and its predictability.

  16. Using Satellite Aerosol Retrievals to Monitor Surface Particulate Air Quality

    NASA Technical Reports Server (NTRS)

    Levy, Robert C.; Remer, Lorraine A.; Kahn, Ralph A.; Chu, D. Allen; Mattoo, Shana; Holben, Brent N.; Schafer, Joel S.

    2011-01-01

    The MODIS and MISR aerosol products were designed nearly two decades ago for the purpose of climate applications. Since launch of Terra in 1999, these two sensors have provided global, quantitative information about column-integrated aerosol properties, including aerosol optical depth (AOD) and relative aerosol type parameters (such as Angstrom exponent). Although primarily designed for climate, the air quality (AQ) community quickly recognized that passive satellite products could be used for particulate air quality monitoring and forecasting. However, AOD and particulate matter (PM) concentrations have different units, and represent aerosol conditions in different layers of the atmosphere. Also, due to low visible contrast over brighter surface conditions, satellite-derived aerosol retrievals tend to have larger uncertainty in urban or populated regions. Nonetheless, the AQ community has made significant progress in relating column-integrated AOD at ambient relative humidity (RH) to surface PM concentrations at dried RH. Knowledge of aerosol optical and microphysical properties, ambient meteorological conditions, and especially vertical profile, are critical for physically relating AOD and PM. To make urban-scale maps of PM, we also must account for spatial variability. Since surface PM may vary on a finer spatial scale than the resolution of standard MODIS (10 km) and MISR (17km) products, we test higher-resolution versions of MODIS (3km) and MISR (1km research mode) retrievals. The recent (July 2011) DISCOVER-AQ campaign in the mid-Atlantic offers a comprehensive network of sun photometers (DRAGON) and other data that we use for validating the higher resolution satellite data. In the future, we expect that the wealth of aircraft and ground-based measurements, collected during DISCOVER-AQ, will help us quantitatively link remote sensed and ground-based measurements in the urban region.

  17. 30 CFR 57.5006 - Air Quality-Surface Only [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Air Quality-Surface Only 57.5006 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Air Quality-Surface and Underground §...

  18. 30 CFR 57.5006 - Air Quality-Surface Only [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Air Quality-Surface Only 57.5006 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Air Quality-Surface and Underground §...

  19. 30 CFR 57.5006 - Air Quality-Surface Only [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Air Quality-Surface Only 57.5006 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Air Quality-Surface and Underground §...

  20. 30 CFR 57.5006 - Air Quality-Surface Only [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Air Quality-Surface Only 57.5006 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Air Quality-Surface and Underground §...

  1. 30 CFR 57.5006 - Air Quality-Surface Only [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Air Quality-Surface Only 57.5006 Section 57... MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Air Quality, Radiation, Physical Agents, and Diesel Particulate Matter Air Quality-Surface and Underground §...

  2. Stress response of Escherichia coli induced by surface streamer discharge in humid air

    NASA Astrophysics Data System (ADS)

    Doležalová, Eva; Prukner, Václav; Lukeš, Petr; Šimek, Milan

    2016-02-01

    Inactivation of Escherichia coli by means of surface streamer discharge has been investigated to obtain new insights into the key mechanisms involved, with a particular emphasis placed on the microbial response to plasma-induced stress. The surface streamer discharge was produced in coplanar dielectric barrier discharge electrode geometry, and was driven by an amplitude-modulated ac high voltage in humid synthetic air at atmospheric pressure. The response to plasma-induced stress was evaluated by using conventional cultivation, sublethal injury and resazurin assay and the LIVE/DEAD® BacLight™ Bacterial Viability kit. Compared to conventional cultivation, the LIVE/DEAD® test labels bacteria with damaged membranes, while resazurin assay tracks their metabolic activity. Our results clearly demonstrate that the treated bacteria partly lost their ability to grow properly, i.e. they became injured and culturable, or even viable but nonculturable (VBNC). The ability to develop colonies could have been lost due to damage of the bacterial membrane. Damage of the membranes was mainly caused by the lipid peroxidation, evidencing the key role of oxygen reactive species, in particular ozone. We conclude that the conventional cultivation method overestimates the decontamination efficiency of various plasma sources, and must therefore be complemented by alternative techniques capable of resolving viable but nonculturable bacteria.

  3. Air plasma processing of poly(methyl methacrylate) micro-beads: Surface characterisations

    NASA Astrophysics Data System (ADS)

    Liu, Chaozong; Cui, Nai-Yi; Osbeck, Susan; Liang, He

    2012-10-01

    This paper reports the surface processing of poly(methyl methacrylate) (PMMA) micro-beads by using a rotary air plasma reactor, and its effects on surface properties. The surface properties, including surface wettability, surface chemistry and textures of the PMMA beads, were characterised. It was observed that the air plasma processing can improve the surface wettability of the PMMA microbeads significantly. A 15 min plasma processing can reduce the surface water contact angle of PMMA beads to about 50° from its original value of 80.3°. This was accompanied by about 8% increase in surface oxygen concentration as confirmed by XPS analysis. The optical profilometry examination revealed the air plasma processing resulted in a rougher surface that has a “delicate” surface texture. It is concluded that the surface chemistry and texture, induced by air plasma processing, co-contributed to the surface wettability improvement of PMMA micro-beads.

  4. Molecular Layer Deposition for Surface Modification of Lithium-Ion Battery Electrodes

    SciTech Connect

    Ban, Chunmei; George, Steven M.

    2016-10-21

    Inspired by recent successes in applying molecular layer deposition (MLD) to stabilize lithium-ion (Li-ion) electrodes, this review presents the MLD process and its outstanding attributes for electrochemical applications. The review discusses various MLD materials and their implementation in Li-ion electrodes. The rationale behind these emerging uses of MLD is examined to motivate future efforts on the fundamental understanding of interphase chemistry and the development of new materials for enhanced electrochemical performance.

  5. Atomically resolved graphitic surfaces in air by atomic force microscopy.

    PubMed

    Wastl, Daniel S; Weymouth, Alfred J; Giessibl, Franz J

    2014-05-27

    Imaging at the atomic scale using atomic force microscopy in biocompatible environments is an ongoing challenge. We demonstrate atomic resolution of graphite and hydrogen-intercalated graphene on SiC in air. The main challenges arise from the overall surface cleanliness and the water layers which form on almost all surfaces. To further investigate the influence of the water layers, we compare data taken with a hydrophilic bulk-silicon tip to a hydrophobic bulk-sapphire tip. While atomic resolution can be achieved with both tip materials at moderate interaction forces, there are strong differences in force versus distance spectra which relate to the water layers on the tips and samples. Imaging at very low tip-sample interaction forces results in the observation of large terraces of a naturally occurring stripe structure on the hydrogen-intercalated graphene. This structure has been previously reported on graphitic surfaces that are not covered with disordered adsorbates in ambient conditions (i.e., on graphite and bilayer graphene on SiC, but not on monolayer graphene on SiC). Both these observations indicate that hydrogen-intercalated graphene is close to an ideal graphene sample in ambient environments.

  6. Air Surface Temperature Correlation with Greenhouse Gases by Using Airs Data Over Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Rajab, Jasim Mohammed; MatJafri, M. Z.; Lim, H. S.

    2014-08-01

    The main objective of this study is to develop algorithms for calculating the air surface temperature (AST). This study also aims to analyze and investigate the effects of greenhouse gases (GHGs) on the AST value in Peninsular Malaysia. Multiple linear regression is used to achieve the objectives of the study. Peninsular Malaysia has been selected as the research area because it is among the regions of tropical Southeast Asia with the greatest humidity, pockets of heavy pollution, rapid economic growth, and industrialization. The predicted AST was highly correlated ( R = 0.783) with GHGs for the 6-year data (2003-2008). Comparisons of five stations in 2009 showed close agreement between the predicted AST and the observed AST from AIRS, especially in the wet season (within 1.3 K). The in situ data ranged from 1 to 2 K. Validation results showed that AST ( R = 0.776-0.878) has values nearly the same as the observed AST from AIRS. We found that O3 during the wet season was indicated by a strongly positive beta coefficient (0.264-0.992) with AST. The CO2 yields a reasonable relationship with temperature with low to moderate beta coefficient (-0.065 to 0.238). The O3, CO2, and environmental variables experienced different seasonal fluctuations that depend on weather conditions and topography. The concentration of gases and pollution were the highest over industrial zones and overcrowded cities, and the dry season was more polluted compared with the wet season. These results indicate the advantage of using the satellite AIRS data and a correlation analysis to investigate the effect of atmospheric GHGs on AST over Peninsular Malaysia. An algorithm that is capable of retrieving Peninsular Malaysian AST in all weather conditions with total uncertainties ranging from 1 to 2 K was developed.

  7. Air bubble-shock wave interaction adjacent to gelantine surface

    NASA Astrophysics Data System (ADS)

    Lush, P. A.; Tomita, Y.; Onodera, O.; Takayama, K.; Sanada, N.; Kuwahara, M.; Ioritani, N.; Kitayama, O.

    1990-07-01

    The interaction between a shock wave and an air bubble-adjacent to a gelatine surface is investigated in order to simulate human tissue damage resulting from extracorporeal shock wave lithotripsy. Using high speed cine photography it is found that a shock wave of strength 11 MPa causes 1-3 mm diameter bubbles to produce high velocity microjets with penetration rates of approximately 110 m/s and penetration depths approximately equal to twice the initial bubble diameter. Theoretical considerations for liquid impact on soft solid of similar density indicate that microjet velocities will be twice the penetration rate, i.e. 220 m/s in the present case. Such events are the probable cause of observed renal tissue damage.

  8. Impacts of wind farms on surface air temperatures

    PubMed Central

    Baidya Roy, Somnath; Traiteur, Justin J.

    2010-01-01

    Utility-scale large wind farms are rapidly growing in size and numbers all over the world. Data from a meteorological field campaign show that such wind farms can significantly affect near-surface air temperatures. These effects result from enhanced vertical mixing due to turbulence generated by wind turbine rotors. The impacts of wind farms on local weather can be minimized by changing rotor design or by siting wind farms in regions with high natural turbulence. Using a 25-y-long climate dataset, we identified such regions in the world. Many of these regions, such as the Midwest and Great Plains in the United States, are also rich in wind resources, making them ideal candidates for low-impact wind farms. PMID:20921371

  9. Impacts of wind farms on surface air temperatures.

    PubMed

    Baidya Roy, Somnath; Traiteur, Justin J

    2010-10-19

    Utility-scale large wind farms are rapidly growing in size and numbers all over the world. Data from a meteorological field campaign show that such wind farms can significantly affect near-surface air temperatures. These effects result from enhanced vertical mixing due to turbulence generated by wind turbine rotors. The impacts of wind farms on local weather can be minimized by changing rotor design or by siting wind farms in regions with high natural turbulence. Using a 25-y-long climate dataset, we identified such regions in the world. Many of these regions, such as the Midwest and Great Plains in the United States, are also rich in wind resources, making them ideal candidates for low-impact wind farms.

  10. Evidence of Lunar Phase Influence on Global Surface Air Temperatures

    NASA Technical Reports Server (NTRS)

    Anyamba, Ebby; Susskind, Joel

    2000-01-01

    Intraseasonal oscillations appearing in a newly available 20-year record of satellite-derived surface air temperature are composited with respect to the lunar phase. Polar regions exhibit strong lunar phase modulation with higher temperatures occurs near full moon and lower temperatures at new moon, in agreement with previous studies. The polar response to the apparent lunar forcing is shown to be most robust in the winter months when solar influence is minimum. In addition, the response appears to be influenced by ENSO events. The highest mean temperature range between full moon and new moon in the polar region between 60 deg and 90 deg latitude was recorded in 1983, 1986/87, and 1990/91. Although the largest lunar phase signal is in the polar regions, there is a tendency for meridional equatorward progression of anomalies in both hemispheres so that the warning in the tropics occurs at the time of the new moon.

  11. Marcus-Hush-Chidsey theory of electron transfer to and from species bound at a non-uniform electrode surface: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Henstridge, Martin C.; Batchelor-McAuley, Christopher; Gusmão, Rui; Compton, Richard G.

    2011-11-01

    Two simple models of electrode surface inhomogeneity based on Marcus-Hush theory are considered; a distribution in formal potentials and a distribution in electron tunnelling distances. Cyclic voltammetry simulated using these models is compared with that simulated using Marcus-Hush theory for a flat, uniform and homogeneous electrode surface, with the two models of surface inhomogeneity yielding broadened peaks with decreased peak-currents. An edge-plane pyrolytic graphite electrode is covalently modified with ferrocene via 'click' chemistry and the resulting voltammetry compared with each of the three previously considered models. The distribution of formal potentials is seen to fit the experimental data most closely.

  12. Clean Air Act Guidelines and Standards for Solvent Use and Surface Coating Industry

    EPA Pesticide Factsheets

    This page contains the stationary sources of air pollution for the solvent use and surface coating industries, and their corresponding air pollution regulations. To learn more about the regulations for each industry, just click on the links below.

  13. A Metal-Free, Free-Standing, Macroporous Graphene@g-C₃N₄ Composite Air Electrode for High-Energy Lithium Oxygen Batteries.

    PubMed

    Luo, Wen-Bin; Chou, Shu-Lei; Wang, Jia-Zhao; Zhai, Yu-Chun; Liu, Hua-Kun

    2015-06-01

    The nonaqueous lithium oxygen battery is a promising candidate as a next-generation energy storage system because of its potentially high energy density (up to 2-3 kW kg(-1)), exceeding that of any other existing energy storage system for storing sustainable and clean energy to reduce greenhouse gas emissions and the consumption of nonrenewable fossil fuels. To achieve high energy density, long cycling stability, and low cost, the air electrode structure and the electrocatalysts play important roles. Here, a metal-free, free-standing macroporous graphene@graphitic carbon nitride (g-C3N4) composite air cathode is first reported, in which the g-C3N4 nanosheets can act as efficient electrocatalysts, and the macroporous graphene nanosheets can provide space for Li2O2 to deposit and also promote the electron transfer. The electrochemical results on the graphene@g-C3N4 composite air electrode show a 0.48 V lower charging plateau and a 0.13 V higher discharging plateau than those of pure graphene air electrode, with a discharge capacity of nearly 17300 mA h g(-1)(composite) . Excellent cycling performance, with terminal voltage higher than 2.4 V after 105 cycles at 1000 mA h g(-1)(composite) capacity, can also be achieved. Therefore, this hybrid material is a promising candidate for use as a high energy, long-cycle-life, and low-cost cathode material for lithium oxygen batteries.

  14. Low resistance fuel electrodes

    DOEpatents

    Maskalick, Nichols J.; Folser, George R.

    1989-01-01

    An electrode 6 bonded to a solid, ion conducting electrolyte 5 is made, where the electrode 6 comprises a ceramic metal oxide 18, metal particles 17, and heat stable metal fibers 19, where the metal fibers provide a matrix structure for the electrode. The electrolyte 5 can be bonded to an air electrode cathode 4, to provide an electrochemical cell 2, preferably of tubular design.

  15. Electrode porosity and effective electrocatalyst activity in electrode-membrane-assemblies (MEAs) of PEMFCs

    SciTech Connect

    Fischer, A.; Wendt, H.

    1996-12-31

    New production technologies of membrane-electrode-assemblies for PEWCs which ensure almost complete catalyst utilization by {open_quotes}wetting{close_quotes} the internal catalyst surface with the ionomeric electrolyte, allow for a reduction of Pt-loadings from prior 4 mg cm{sup -2} to now less than 0.5 mg cm{sup -2}. Such electrodes are not thicker than from 5 to 10 {mu}m. Little has been published hitherto about the detailed micromorphology of such electrodes and the role of electrode porosity on electrode performance. It is well known, that the porosity of thicker fuel cell electrodes, e.g. of PAFC or AFC electrodes is decisive for their performance. Therefore the issue of this investigation is to measure and to modify the porosity of electrodes prepared by typical MEA production procedures and to investigate the influence of this porosity on the effective catalyst activity for cathodic reduction of oxygen from air in membrane cells. It may be anticipated that any mass transfer hindrance of gaseous reactants into porous electrodes would manifest itself rather in the conversion of dilute gases than in the conversion of pure gases (e.g. neat oxygen). Therefore in this investigation the performance of membrane cell cathodes with non pressurized air had been compared to that with neat oxygen at cathodes which had a relatively low Pt-loading of 0.15 mg cm{sup -2}.

  16. Microfabricated surface-electrode ion traps for scalable quantum information processing

    NASA Astrophysics Data System (ADS)

    Seidelin, Signe; Britton, Joe; Chiaverini, John; Reichle, Rainer; Bollinger, John; Leibfried, Didi; Wesenberg, Janus; Blakestad, Brad; Epstein, Ryan; Amini, Jason; Brown, Kenton; Home, Jonathan; Hume, David; Shiga, Nobu; Itano, Wayne; Jost, John; Knill, Emmanuel; Langer, Chris; Ozeri, Roee; Wineland, David

    2007-03-01

    We confine individual atomic ions in an rf Paul trap with a novel geometry where the electrodes are located in a single plane and the ions confined above this plane [1,2,3]. This device is realized with simple fabrication procedures, making it a potential candidate for a scalable ion trap for quantum information processing using large numbers of ions. We confine laser-cooled ions 40 micrometers above planar electrodes. These electrodes are fabricated from gold on a fused quartz substrate. The heating rate of the ions is low enough to make the trap useful for quantum information processing. [1] J. Chiaverini et al., Quantum Inf. Comput. 5, 419 (2005). [2] S. Seidelin et al., Phys. Rev. Lett. 96, 253003 (2006). [3] J. Britton et al., quant-ph/0605170.

  17. Pseudocapacitive performance of a solution-processed β-Co(OH)2 electrode monitored through its surface morphology and area.

    PubMed

    Gaikar, P S; Navale, S T; Gaikwad, S L; Al-Osta, Ahmed; Jadhav, V V; Arjunwadkar, P R; Naushad, Mu; Mane, Rajaram S

    2017-03-07

    In the present study, beta-cobalt hydroxide (β-Co(OH)2) electrodes of various nanostructures and surface areas, viz. nano-rhombuses (NRs), nano-plates (NPs), and nano-grass (NGs), have been synthesized directly onto a stainless-steel (SS) substrate using a simple, economical and binder-free chemical solution-process, utilizing three cobalt precursor salts, i.e. cobalt acetate, cobalt chloride, and cobalt nitrate, respectively. Structural elucidation proves the crystallite size, type and phase-purity of β-Co(OH)2, whereas the surface morphology analysis supports the evolution of the above mentioned nanostructures of various surface areas. The electrochemical pseudocapacitor performance investigation demonstrates a specific capacitance (Sc) of 367 F g(-1) at 1 mA cm(-2) for the NP-type morphology, which is higher than that that displayed by the other morphologies. This change in Sc value is attributed to different charge transfer resistance values, which have been obtained from electrochemical impedance spectroscopy spectra. Finally, we attempt to correlate the relationship between the surface morphology, i.e. surface area, and the charge transfer resistance with the obtained specific capacitance value of the respective electrode.

  18. Study of an Ozone Composing Mechanism derived from the Third Element on Surface of Electrode using Oxygen Gas: Part 2

    NASA Astrophysics Data System (ADS)

    Murai, Akira; Nakajima, Tsuyoshi

    In our third experiment, we changed the density of nitrogen through the addition of heat energy to the anode. A computer simulation confirmed the same phenomenon. Then the copper anode was replaced with an antimony anode. We found that antimony worked better than nitrogen as a third element. Finally, in the fourth experiment, we used an industrial ozone generator including ceramic dielectrics and a titanium expanded metal electrode. A decrease in the temperature of the cooling water led to a proportional increase in ozone. It follows the formula of van't Hoff. After spattering the surface of the electrodes with argon gas and supplying the ozone generator with 99% oxygen, we were able to produce ozone which was more than 20% higher in concentration than primary state ozone under the same conditions. The ozone generator produced ozone in high yield efficiency due to the optimum density of a third element like nitrogen on the surface of the electrodes. Antimony works better than nitrogen does as a third element.

  19. Photoelectrochemical electrodes

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Rembaum, A. (Inventor)

    1983-01-01

    The surface of a moderate band gap semiconductor such as p-type molybdenum sulfide is modified to contain an adherent film of charge mediating ionene polymer containing an electroactive unit such as bipyridimium. Electron transport between the electrode and the mediator film is favorable and photocorrosion and recombination processes are suppressed. Incorporation of particles of catalyst such as platinum within the film provides a reduction in overvoltage. The polymer film is readily deposited on the electrode surface and can be rendered stable by ionic or addition crosslinking. Catalyst can be predispersed in the polymer film or a salt can be impregnated into the film and reduced therein.

  20. In situ UV-visible reflection absorption wavelength modulation spectroscopy of species irreversibly adsorbed on electrode surfaces

    SciTech Connect

    Kim, Sunghyun; Scherson, D.A. )

    1992-12-15

    A method is herein described for the in situ detection of species adsorbed on electrode surfaces which employs a vibrating grating to modulate the wavelength of the incident light. This technique denoted as reflection absorption wavelength modulation spectroscopy (RAWMS) has made it possible to obtain at a fixed electrode potential normalized, differential UV-visible spectra of a single, irreversibly adsorbed monolayer of cobalt tetrasulfonated phthalocyanine (Co[sup II]TsPc) on the basal plane of highly oriented pyrolytic graphite (HOPG(bp)) and of methylene blue (MB) on graphite. The (wavelength) integrated difference RAWMS spectra for these adsorbed species were remarkably similar to those observed for the same compounds in aqueous solutions when present in the monomeric form. Complementary wavelength modulation experiments involving a conventional transmission geometry have shown that the instrument involved in the in situ RAWMS measurements is capable of resolving absorbance changes on the order of 0.002 units. 20 refs.

  1. Methane conversion in surface- and volume-type dielectric barrier discharges generated in the presence of metal-mesh electrodes

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kazunobu; Kulinich, S. A.; Ito, Tsuyohito

    2014-09-01

    Methane gas conversion was studied in customized flow-type reactors with different dielectric barrier discharge generated in Ar-CH4-O2 gas mixtures. Different reactor geometries (with either volume or surface-type discharges) and different electrode materials were compared, and gas temperatures during methane conversion processes were evaluated. The discharge was generated by applying either a conventional sinusoid or nanosecond-pulsed voltage. The methane conversion rate was as high as ˜99% with the total gas flow rate of 15 sccm, while the temperatures did not exceed 450 K. No significant effect of electrode material (stainless steel, aluminum, or CuO coated copper) was found, confirming that the conversion temperatures were much lower than those required for activity of typical catalysts. The reactor geometry, flow rate, and oxygen amount could be used to govern both the methane conversion rate and the fractions of components in the final product.

  2. Surface-electrode trap with an integrated permanent magnet for generating a magnetic-field gradient at trapped ions

    NASA Astrophysics Data System (ADS)

    Kawai, Yuji; Shimizu, Kenji; Noguchi, Atsushi; Urabe, Shinji; Tanaka, Utako

    2017-01-01

    We report on a surface-electrode trap with SmCo magnets arranged in a quadrupole configuration underneath the trap electrode. Because the distance between the magnets and the trapped ions can be as little as several hundred micrometers, a large magnetic field is produced without any heat management. The magnetic-field gradient was measured using the Zeeman splitting of a single trapped 40Ca+ ion at several positions, and a field gradient of 36 T m-1 was obtained. Such a field gradient is useful for the generation of a state-dependent force, which is important for quantum simulation and/or quantum gate operation using radio-frequency or microwave radiation.

  3. Variation in the urban vegetation, surface temperature, air temperature nexus.

    PubMed

    Shiflett, Sheri A; Liang, Liyin L; Crum, Steven M; Feyisa, Gudina L; Wang, Jun; Jenerette, G Darrel

    2017-02-01

    Our study examines the urban vegetation - air temperature (Ta) - land surface temperature (LST) nexus at micro- and regional-scales to better understand urban climate dynamics and the uncertainty in using satellite-based LST for characterizing Ta. While vegetated cooling has been repeatedly linked to reductions in urban LST, the effects of vegetation on Ta, the quantity often used to characterize urban heat islands and global warming, and on the interactions between LST and Ta are less well characterized. To address this need we quantified summer temporal and spatial variation in Ta through a network of 300 air temperature sensors in three sub-regions of greater Los Angeles, CA, which spans a coastal to desert climate gradient. Additional sensors were placed within the inland sub-region at two heights (0.1m and 2m) within three groundcover types: bare soil, irrigated grass, and underneath citrus canopy. For the entire study region, we acquired new imagery data, which allowed calculation of the normalized difference vegetation index (NDVI) and LST. At the microscale, daytime Ta measured along a vertical gradient, ranged from 6 to 3°C cooler at 0.1 and 2m, underneath tall canopy compared to bare ground respectively. At the regional scale NDVI and LST were negatively correlated (p<0.001). Relationships between diel variation in Ta and daytime LST at the regional scale were progressively weaker moving away from the coast and were generally limited to evening and nighttime hours. Relationships between NDVI and Ta were stronger during nighttime hours, yet effectiveness of mid-day vegetated cooling increased substantially at the most arid region. The effectiveness of vegetated Ta cooling increased during heat waves throughout the region. Our findings suggest an important but complex role of vegetation on LST and Ta and that vegetation may provide a negative feedback to urban climate warming.

  4. Surface, Water, and Air Biocharacterization (SWAB) Flight Experiment

    NASA Technical Reports Server (NTRS)

    Castro, V. A.; Ott, C. M.; Pierson, D. L.

    2012-01-01

    The determination of risk from infectious disease during spaceflight missions is composed of several factors including both the concentration and characteristics of the microorganisms to which the crew are exposed. Thus, having a good understanding of the microbial ecology aboard spacecraft provides the necessary information to mitigate health risks to the crew. While preventive measures are taken to minimize the presence of pathogens on spacecraft, medically significant organisms have been isolated from both the Mir and International Space Station (ISS). Historically, the method for isolation and identification of microorganisms from spacecraft environmental samples depended upon their growth on culture media. Unfortunately, only a fraction of the organisms may grow on a specific culture medium, potentially omitting those microorganisms whose nutritional and physical requirements for growth are not met. To address this bias in our understanding of the ISS environment, the Surface, Water, and Air Biocharacterization (SWAB) Flight Experiment was designed to investigate and develop monitoring technology to provide better microbial characterization. For the SWAB flight experiment, we hypothesized that environmental analysis using non-culture-based technologies would reveal microorganisms, allergens, and microbial toxins not previously reported in spacecraft, allowing for a more complete health assessment. Key findings during this experiment included: a) Generally, advanced molecular techniques were able to reveal a few organisms not recovered using culture-based methods; however, there is no indication that current monitoring is "missing" any medically significant bacteria or fungi. b) Molecular techniques have tremendous potential for microbial monitoring, however, sample preparation and data analysis present challenges for spaceflight hardware. c) Analytical results indicate that some molecular techniques, such as denaturing gradient gel electrophoresis (DGGE), can

  5. Manufacturing of Protected Lithium Electrodes for Advanced Lithium-Air, Lithium-Water & Lithium-Sulfur Batteries

    SciTech Connect

    Visco, Steven J

    2015-11-30

    The global demand for rechargeable batteries is large and growing rapidly. Assuming the adoption of electric vehicles continues to increase, the need for smaller, lighter, and less expensive batteries will become even more pressing. In this vein, PolyPlus Battery Company has developed ultra-light high performance batteries based on its proprietary protected lithium electrode (PLE) technology. The Company’s Lithium-Air and Lithium-Seawater batteries have already demonstrated world record performance (verified by third party testing), and we are developing advanced lithium-sulfur batteries which have the potential deliver high performance at low cost. In this program PolyPlus Battery Company teamed with Corning Incorporated to transition the PLE technology from bench top fabrication using manual tooling to a pre- commercial semi-automated pilot line. At the inception of this program PolyPlus worked with a Tier 1 battery manufacturing engineering firm to design and build the first-of-its-kind pilot line for PLE production. The pilot line was shipped and installed in Berkeley, California several months after the start of the program. PolyPlus spent the next two years working with and optimizing the pilot line and now produces all of its PLEs on this line. The optimization process successfully increased the yield, throughput, and quality of PLEs produced on the pilot line. The Corning team focused on fabrication and scale-up of the ceramic membranes that are key to the PLE technology. PolyPlus next demonstrated that it could take Corning membranes through the pilot line process to produce state-of-the-art protected lithium electrodes. In the latter part of the program the Corning team developed alternative membranes targeted for the large rechargeable battery market. PolyPlus is now in discussions with several potential customers for its advanced PLE-enabled batteries, and is building relationships and infrastructure for the transition into manufacturing. It is likely

  6. Influence of electrode surface microstructures on the state of short vacuum gaps after interruption of high-frequency currents

    NASA Astrophysics Data System (ADS)

    Niayesh, Kaveh

    2000-09-01

    In this paper the influences of electrode surface microstructures on the electrical field near the new cathode surface and on the distribution of ion density and velocity in the space-charge region after interruption of high-frequency currents in short vacuum gaps have been studied. To investigate these effects, the equations of conservation of mass and momentum are solved two dimensionally in the space-charge region. The results indicate a considerable increase in ion density at the points with high electrical fields, which results in an enhancement of the electrical field at these points compared with one-dimensional calculations. Considering the calculated electrical field near the cathode surface and the power density deposited into the cathode surface by ions, the initiation of a breakdown during the post arc period under the mechanism of explosive electron emission may be possible.

  7. Fundamental Studies of Surfaces Processes and Trace Analysis Using Solid Electrodes.

    DTIC Science & Technology

    1987-08-10

    into studies of heterogeneous electrode kinetics, underpotential deposition and electrocatalysis. The electroanalytical work areas involved trace...ism of the catalysis of formic acid electrooxidation by underpotentially deposited species, b) modelling the interaction of mass transport and light...method. P. UPD Studies in Acetonitrile. (5). The underpotential deposition of lead and silver on gold was studied in acetonitrile as a solvent. The

  8. Electrocatalytic behaviour and application of manganese porphyrin/gold nanoparticle- surface modified glassy carbon electrodes

    NASA Astrophysics Data System (ADS)

    Sebarchievici, I.; Tăranu, B. O.; Birdeanu, M.; Rus, S. F.; Fagadar-Cosma, E.

    2016-12-01

    The main purpose of this research was to obtain manganese porphyrin/gold nanoparticle-modified glassy carbon electrodes and to use them for the detection of H2O2. Two sets of modified electrodes were prepared by drop-cast deposition of 5,10,15,20-tetra(4-methyl-phenyl)porphyrinato manganese(III) chloride alone and of the same Mn-porphyrin and gold-colloid solution and comparatively characterized by Raman, UV-vis, ellipsometry, AFM and TEM microscopy, XPS and cyclic voltammetry. XPS spectrum recorded for GC_MnP_nAu modified electrode displayed the characteristic signals of gold nanoparticles. The optical parameters have greater values for GC_MnP_nAu in comparison with GC_MnP, due to increasing charge transfer efficiency. The MnP_nAu film mediates the electron transfer between H2O2 and GC, evidenced by an increase in the current intensity of the anodic peak, and facilitates the electrochemical regeneration of oxidized H2O2 at cathodic potentials. From the cyclic voltammetry experiments a linear relationship between H2O2 concentration vs oxidation and reduction currents was observed. The linear dependence between density of current and the square root of the scan rate indicates that the oxidation and reduction processes of H2O2 are diffusion controlled. The GC_MnP_nAu modified electrode shows great potential as electrochemical sensor for determination of hydrogen peroxide.

  9. On optimal electrode configuration to estimate hand movements from forearm surface electromyography.

    PubMed

    Paleari, Marco; Di Girolamo, Michela; Celadon, Nicoló; Favetto, Alain; Ariano, Paolo

    2015-01-01

    Understanding the movement of the hand from sEMG signals acquired on the forearm is key in the development of future prosthetics of the upper limb. Despite the technical advancement on this technique, state of the art of sEMG still relies strongly on optimal electrode placement which is typically performed by a specialist by mean of a heuristic search. Involving a specialist has few major disadvantages including high costs and relatively long schedules. This work searches an optimal electrode configuration which could reduce or avoid the intervention of a specialist. More than 200 different possible electrode configurations were assessed by means of the average recognition rate over 11 different movements of the hand, wrist, and fingers. It is shown that using two rows of 8 equally spaced electrodes around the circumference of the forearm could be an optimal trade-off solution to accomplish the task of recognizing hand movement (ARR = 92%) without the need for a specialist or very complex hardware.

  10. Surface-enhanced raman spectra and molecular orientation of phthalazine adsorbed on a silver electrode

    NASA Astrophysics Data System (ADS)

    Takahashi, Machiko; Fujita, Masato; Ito, Masatoki

    1984-08-01

    SERS from phthalazine adsorbed on an Ag electrode was investigated under several conditions of applied voltage and solution concentration. Spectral assignments of the Raman bands were successfully performed and two differently oriented adsorbates, i.e. flat and end-on species, were identified. The contribution of the image field to the SERS intensity was considerable.

  11. Small Gold Nanoparticles Interfaced to Electrodes through Molecular Linkers: A Platform to Enhance Electron Transfer and Increase Electrochemically Active Surface Area.

    PubMed

    Young, Samantha L; Kellon, Jaclyn E; Hutchison, James E

    2016-10-17

    For the smallest nanostructures (<5 nm), small changes in structure can lead to significant changes in properties and reactivity. In the case of nanoparticle (NP)-functionalized electrodes, NP structure and composition, and the nature of the NP-electrode interface have a strong influence upon electrochemical properties that are critical in applications such as amperometric sensing, photocatalysis and electrocatalysis. Existing methods to fabricate NP-functionalized electrodes do not allow for precise control over all these variables, especially the NP-electrode interface, making it difficult to understand and predict how structural changes influence NP activity. We investigated the electrochemical properties of small (dcore < 2.5 nm) gold nanoparticles (AuNPs) on boron doped diamond electrodes using three different electrode fabrication techniques with varying degrees of nanoparticle-electrode interface definition. Two methods to attach AuNPs to the electrode through a covalently bound molecular linker were developed and compared to NP-functionalized electrodes fabricated using solution deposition methods (drop-casting and physiadsorption of a monolayer). In each case, a ferrocene redox probe was tethered to the AuNP surface to evaluate electron transfer through the AuNPs. The AuNPs that were molecularly interfaced with the electrode exhibited nearly ideal, reproducible electrochemical behavior with narrow redox peaks and small peak separations, whereas the solution deposited NPs had broader redox peaks with large peak separations. These data suggest that the molecular tether facilitates AuNP-mediated electron transfer. Interestingly, the molecularly tethered NPs also had significantly more electrochemically active surface area than the solution deposited NPs. The enhanced electrochemical behavior of the molecularly interfaced NPs demonstrates the significant influence of the interface on NP-mediated electron transfer and suggests that similar modified electrodes

  12. Skin frictional resistance of plane surfaces in air

    NASA Technical Reports Server (NTRS)

    Diehl, W S

    1922-01-01

    Given here is the most recent research on skin frictional resistance of plane surfaces in air that was conducted by Dr. Wieselsberger under the direction of Dr. Prandtl of Gottingen University. In all, 16 models were tested. These were divided into four groups, as follows: 1) cloth, in the original condition; 2) cloth, with the nap singed off; 3) cloth, with three coats of dope; and 4) cloth, with six coats of dope. Each group consisted of four models of uniform width, 1 meter, and of lengths of 0.5, 1.0, 1.5, and 2.0 meters. Tests were made on each model at speeds varying from 7.0 to 50 meters per second. The observed total resistance was corrected for the form resistance which was obtained from the pressure distribution on the end of the model. Previous tests had shown that the form resistance due to the rounded front edge used on the models was negligible. The results are expressed in terms of the absolute coefficient of frictionless resistance, C(sub F).

  13. Assessing surface air temperature variability using quantile regression

    NASA Astrophysics Data System (ADS)

    Timofeev, A. A.; Sterin, A. M.

    2014-12-01

    Many researches in climate change currently involve linear trends, based on measured variables. And many of them only consider trends in mean values, whereas it is clear, that not only means, but also whole shape of distribution changes over time and requires careful assessment. For example extreme values including outliers may get bigger, while median has zero slope.Quantile regression provides a convenient tool, that enables detailed analysis of changes in full range of distribution by producing a vector of quantile trends for any given set of quantiles.We have applied quantile regression to surface air temperature observations made at over 600 weather stations across Russian Federation during last four decades. The results demonstrate well pronounced regions with similar values of significant trends in different parts of temperature value distribution (left tail, middle part, right tail). The uncertainties of quantile trend estimations for several spatial patterns of trends over Russia are estimated and analyzed for each of four seasons.For temperature trend estimation over vast territories, quantile regression is an effort consuming approach, but is more informative than traditional instrument, to assess decadal evolution of temperature values, including evolution of extremes.Partial support of ERA NET RUS ACPCA joint project between EU and RBRF 12-05-91656-ЭРА-А is highly appreciated.

  14. Corneal-shaping electrode

    DOEpatents

    Doss, James D.; Hutson, Richard L.

    1982-01-01

    The disclosure relates to a circulating saline electrode for changing corneal shape in eyes. The electrode comprises a tubular nonconductive electrode housing having an annular expanded base which has a surface substantially matched to a subject corneal surface. A tubular conductive electrode connected to a radiofrequency generating source is disposed within the electrode housing and longitudinally aligned therewith. The electrode has a generally hemispherical head having at least one orifice. Saline solution is circulated through the apparatus and over the cornea to cool the corneal surface while radiofrequency electric current emitted from the electrode flows therefrom through the cornea to a second electrode, on the rear of the head. This current heats the deep corneal stroma and thereby effects corneal reshaping as a biological response to the heat.

  15. Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes.

    PubMed

    Li, Zhiyang; Leung, Calvin; Gao, Fan; Gu, Zhiyong

    2015-09-04

    In this paper, vertically aligned Pt nanowire arrays (PtNWA) with different lengths and surface roughnesses were fabricated and their electrochemical performance toward hydrogen peroxide (H₂O₂) detection was studied. The nanowire arrays were synthesized by electroplating Pt in nanopores of anodic aluminum oxide (AAO) template. Different parameters, such as current density and deposition time, were precisely controlled to synthesize nanowires with different surface roughnesses and various lengths from 3 μm to 12 μm. The PtNWA electrodes showed better performance than the conventional electrodes modified by Pt nanowires randomly dispersed on the electrode surface. The results indicate that both the length and surface roughness can affect the sensing performance of vertically aligned Pt nanowire array electrodes. Generally, longer nanowires with rougher surfaces showed better electrochemical sensing performance. The 12 μm rough surface PtNWA presented the largest sensitivity (654 μA·mM⁻¹·cm⁻²) among all the nanowires studied, and showed a limit of detection of 2.4 μM. The 12 μm rough surface PtNWA electrode also showed good anti-interference property from chemicals that are typically present in the biological samples such as ascorbic, uric acid, citric acid, and glucose. The sensing performance in real samples (river water) was tested and good recovery was observed. These Nafion-free, vertically aligned Pt nanowires with surface roughness control show great promise as versatile electrochemical sensors and biosensors.

  16. Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes

    PubMed Central

    Li, Zhiyang; Leung, Calvin; Gao, Fan; Gu, Zhiyong

    2015-01-01

    In this paper, vertically aligned Pt nanowire arrays (PtNWA) with different lengths and surface roughnesses were fabricated and their electrochemical performance toward hydrogen peroxide (H2O2) detection was studied. The nanowire arrays were synthesized by electroplating Pt in nanopores of anodic aluminum oxide (AAO) template. Different parameters, such as current density and deposition time, were precisely controlled to synthesize nanowires with different surface roughnesses and various lengths from 3 μm to 12 μm. The PtNWA electrodes showed better performance than the conventional electrodes modified by Pt nanowires randomly dispersed on the electrode surface. The results indicate that both the length and surface roughness can affect the sensing performance of vertically aligned Pt nanowire array electrodes. Generally, longer nanowires with rougher surfaces showed better electrochemical sensing performance. The 12 μm rough surface PtNWA presented the largest sensitivity (654 μA·mM−1·cm−2) among all the nanowires studied, and showed a limit of detection of 2.4 μM. The 12 μm rough surface PtNWA electrode also showed good anti-interference property from chemicals that are typically present in the biological samples such as ascorbic, uric acid, citric acid, and glucose. The sensing performance in real samples (river water) was tested and good recovery was observed. These Nafion-free, vertically aligned Pt nanowires with surface roughness control show great promise as versatile electrochemical sensors and biosensors. PMID:26404303

  17. An uniform DBD plasma excited by bipolar nanosecond pulse using wire-cylinder electrode configuration in atmospheric air.

    PubMed

    Jiang, Peng-Chao; Wang, Wen-Chun; Zhang, Shuai; Jia, Li; Yang, De-Zheng; Tang, Kai; Liu, Zhi-Jie

    2014-03-25

    In this study, a bipolar nanosecond pulsed power supply with 15 ns rising time is employed to generate an uniform dielectric barrier discharge using the wire-cylinder electrode configuration in atmospheric air. The images, waveforms of pulse voltage and discharge current, and the optical emission spectra of the discharges are recorded. The rotational and vibrational temperatures of plasma are determined by comparing the simulated spectra with the experimental spectra. The effects of pulse peak voltage, pulse repetition rate and quartz tube diameter on the emission intensities of N2 (C(3)Πu→B(3)Πg, 0-0) and N2(+)B(2)Σu(+)→X(2)Σg(+),0-0 and the rotational and vibrational temperatures have been investigated. It is found that the uniform plasma with low gas temperature can be obtained, and the emission intensities of N2 (C(3)Πu→B(3)Πg, 0-0) and N2(+)B(2)Σu(+)→X(2)Σg(+),0-0 rise with increasing the pulse peak voltage and pulse repetition rate, while decrease as the increase of quartz tube diameter. In addition, under the condition of 28 kV pulse peak voltage, 150 Hz pulse repetition rate and 7 mm quartz tube diameter, the plasma gas temperature is determined to be 330 K. The results also indicate that the plasma gas temperature keep almost constant when increasing the pulse peak voltage and pulse repetition rate but increase with the increase of the quartz tube diameter.

  18. Electrochemically deposited gold nanoparticles on a carbon paste electrode surface for the determination of mercury.

    PubMed

    Sahoo, Srikant; Satpati, Ashis Kumar; Reddy, Annareddy Venkata Ramana

    2015-01-01

    An electrochemical method was developed for the determination of Hg at ultratrace levels using an Au nanoparticle (AuNP) array modified carbon paste electrode (CPE) by anodic stripping voltammetry. Scanning electron microscopy measurements imaged the size and shape of AuNPs on the CPE substrate; it was possible to tune the size and the NP density by changing the deposition time and medium. Electrochemical characterization of the AuNP modified CPE was carried out using cyclic voltammetry and electrochemical impedance measurements. Interferences due to some commonly occurring metal ions and surfactants on the stripping peak of Hg were also investigated. The 3σ detection limit for Hg using the AuNP modified electrode was as 0.24 μg/L. This method was applied to determine Hg in soil samples.

  19. Enhanced Output Power of PZT Nanogenerator by Controlling Surface Morphology of Electrode.

    PubMed

    Jung, Woo-Suk; Lee, Won-Hee; Ju, Byeong-Kwon; Yoon, Seok-Jin; Kang, Chong-Yun

    2015-11-01

    Piezoelectric power generation using Pb(Zr,Ti)O3(PZT) nanowires grown on Nb-doped SrTiO3(nb:STO) substrate has been demonstrated. The epitaxial PZT nanowires prepared by a hydrothermal method, with a diameter and length of approximately 300 nm and 7 μm, respecively, were vertically aligned on the substrate. An embossed Au top electrode was applied to maximize the effective power generation area for non-uniform PZT nanowires. The PZT nanogenerator produced output power density of 0.56 μW/cm2 with a voltage of 0.9 V and current of 75 nA. This research suggests that the morphology control of top electrode can be useful to improve the efficiency of piezoelectric power generation.

  20. A microfabricated surface-electrode ion trap for scalable quantum information processing

    NASA Astrophysics Data System (ADS)

    Seidelin, Signe; Chiaverini, John; Reichle, Rainer; Bollinger, John; Leibfried, Didi; Britton, Joe; Wesenberg, Janus; Blakestad, Brad; Epstein, Ryan; Hume, David; Jost, John; Langer, Chris; Ozeri, Roee; Shiga, Nobu; Wineland, David

    2006-05-01

    We demonstrate confinement of individual atomic ions in a radio-frequency Paul trap with a novel geometry where the electrodes are located in a single plane and the ions confined above this plane. This device is realized with a relatively simple fabrication procedure and has important implications for quantum state manipulation and quantum information processing using large numbers of ions. We confine laser-cooled Mg-24 ions approximately 40 micrometer above planar gold electrodes. We measure the ions' motional frequencies and compare them to simulations. From measurements of the escape time of ions from the trap, we also determine a heating rate of approximately five motional quanta per millisecond for a trap frequency of 5.3 MHz.

  1. Microfabricated surface-electrode ion traps for scalable quantum information processing

    NASA Astrophysics Data System (ADS)

    Seidelin, S.; Britton, J.; Chiaverini, J.; Reichle, R.; Bollinger, J. J.; Leibfried, D.; Wesenberg, J. H.; Blakestad, R. B.; Epstein, R. J.; Amini, J. M.; Brown, K. R.; Home, J. P.; Hume, D. B.; Itano, W. M.; Jost, J. D.; Knill, E.; Langer, C.; Ozeri, R.; Shiga, N.; Wineland, D. J.

    2007-06-01

    We confine individual atomic ions in rf Paul traps with a novel geometry where the electrodes are located in a single plane and the ions are confined above this plane ootnotetextJ. Chiaverini et al., Quantum Inf. Comput. 5, 419 (2005).^, ootnotetextS. Seidelin et al., Phys. Rev. Lett. 96, 253003 (2006).^, ootnotetextJ. Britton et al., quant-ph/0605170.. These devices are realized with simple fabrication procedures, making them potentially scalable for quantum information processing using large numbers of ions. For traps fabricated from gold on fused quartz, the ions are 40 micrometers above the planar electrodes and their heating rate is low enough to make the traps useful for quantum information processing.

  2. Dry under water: comparative morphology and functional aspects of air-retaining insect surfaces.

    PubMed

    Balmert, Alexander; Florian Bohn, Holger; Ditsche-Kuru, Petra; Barthlott, Wilhelm

    2011-04-01

    Superhydrophobic surfaces prevent certain body parts of semiaquatic and aquatic insects from getting wet while submerged in water. The air layer on these surfaces can serve the insects as a physical gill. Using scanning electron microscopy, we investigated the morphology of air-retaining surfaces in five insect species with different levels of adaptation to aquatic habitats. We found surfaces with either large and sparse hairs (setae), small and dense hairs (microtrichia), or hierarchically structured surfaces with both types of hairs. The structural parameters and air-film persistence of these surfaces were compared. Air-film persistence varied between 2 days in the beetle Galerucella nymphaea possessing only sparse setae and more than 120 days in the bugs Notonecta glauca and Ilyocoris cimicoides possessing dense microtrichia (up to 6.6 × 10(6) microtrichia per millimeter square). From our results, we conclude that the density of the surface structures is the most important factor that affects the persistence of air films. Combinations of setae and microtrichia are not decisive for the overall persistence of the air film but might provide a thick air store for a short time and a thin but mechanically more stable air film for a long time. Thus, we assume that a dense cover of microtrichia acts as a "backup system" preventing wetting of the body surface in case the air-water interface is pressed toward the surface. Our findings might be beneficial for the development of biomimetic surfaces for long-term air retention and drag reduction under water. In addition, the biological functions of the different air retention capabilities are discussed.

  3. 77 FR 38595 - Taking and Importing Marine Mammals; Precision Strike Weapon and Air-to-Surface Gunnery Training...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-28

    ...; Precision Strike Weapon and Air-to-Surface Gunnery Training and Testing Operations at Eglin Air Force Base... with Precision Strike Weapon (PSW) and Air-to-Surface (AS) gunnery missions, both of which are military... two weapons: (1) The Joint Air-to-Surface Stand-off Missile (JASSM) AGM-158 A and B; and (2) the...

  4. Electrochemical Behavior of Disposable Electrodes Prepared by Ion Beam Based Surface Modification for Biomolecular Recognition

    SciTech Connect

    Erdem, A.; Karadeniz, H.; Caliskan, A.; Urkac, E. Sokullu; Oztarhan, A.; Oks, E.; Nikolayev, A.

    2009-03-10

    Many important technological advances have been made in the development of technologies to monitor interactions and recognition events of biomolecules in solution and on solid substrates. The development of advanced biosensors could impact significantly the areas of genomics, proteomics, biomedical diagnostics and drug discovery. In the literature, there have recently appeared an impressive number of intensive designs for electrochemical monitoring of biomolecular recognition. Herein, the influence of ion implanted disposable graphite electrodes on biomolecular recognition and their electrochemical behaviour was investigated.

  5. Performance and Surface Integrity of Ti6Al4V After Sinking EDM with Special Graphite Electrodes

    NASA Astrophysics Data System (ADS)

    Amorim, Fred L.; Stedile, Leandro J.; Torres, Ricardo D.; Soares, Paulo C.; Henning Laurindo, Carlos A.

    2014-04-01

    Titanium and its alloys have high chemical reactivity with most of the cutting tools. This makes it difficult to work with these alloys using conventional machining processes. Electrical discharge machining (EDM) emerges as an alternative technique to machining these materials. In this work, it is investigated the performance of three special grades of graphite as electrodes when ED-Machining Ti6Al4V samples under three different regimes. The main influences of electrical parameters are discussed for the samples material removal rate, volumetric relative wear and surface roughness. The samples surfaces were evaluated using SEM images, microhardness measurements, and x-ray diffraction. It was found that the best results for samples material removal rate, surface roughness, and volumetric relative wear were obtained for the graphite electrode with 10-μm particle size and negative polarity. For all samples machined by EDM and characterized by x-ray (XRD), it was identified the presence of titanium carbides. For the finish EDM regimes, the recast layer presents an increased amount of titanium carbides compared to semi-finish and rough regimes.

  6. Surface functionality and electrochemical investigations of a graphitic electrode as a candidate for alkaline energy conversion and storage devices.

    PubMed

    Soliman, Ahmed B; Abdel-Samad, Hesham S; Abdel Rehim, Sayed S; Hassan, Hamdy H

    2016-02-26

    Graphite is a typical electrocatalyst support in alkaline energy conversion and storage devices such as fuel cells, supercapacitores and lithium ion batteries. The electrochemical behaviour of a graphite electrode in 0.5 M NaOH was studied to elucidate its surface structure/electrochemical activity relationship. Graphite voltammograms are characterized by an anodic shoulder AI and a cathodic peak CI in addition to the oxygen reduction reaction plateaus, PI and PII. AI and CI were attributed to oxidation and reduction of some graphite surface function groups, respectively. Rotating ring disk electrode (RRDE) study revealed two different oxygen types assigned as inner and outer oxygen. The inner oxygen was reduced via the more efficient 4-electron pathway. The outer oxygen reduction proceeded with a lower efficient 2-electron pathway. The calculated percentages of the 4-electron pathway were ranged from 70% to 90%. A full mechanism for the graphite surface function groups changes over the studied potential window was suggested through the combination between the voltammetric, FT-IR and Raman results.

  7. Influences of internal resistance and specific surface area of electrode materials on characteristics of electric double layer capacitors

    NASA Astrophysics Data System (ADS)

    Suda, Yoshiyuki; Mizutani, Akitaka; Harigai, Toru; Takikawa, Hirofumi; Ue, Hitoshi; Umeda, Yoshito

    2017-01-01

    We fabricated electric double layer capacitors (EDLCs) using particulate and fibrous types of carbon nanomaterials with a wide range of specific surface areas and resistivity as an active material. The carbon nanomaterials used in this study are carbon nanoballoons (CNBs), onion-like carbon (OLC), and carbon nanocoils (CNCs). A commercially used activated carbon (AC) combined with a conductive agent was used as a comparison. We compared the EDLC performance using cyclic voltammetry (CV), galvanostatic charge/discharge testing, and electrochemical impedance spectroscopy (EIS). OLC showed a poor EDLC performance, although it has the lowest resistivity among the carbon nanomaterials. CNB, which has a 1/16 lower specific surface area than AC but higher specific surface area than CNC and OLC, had a higher specific capacitance than CNC and OLC. Moreover, at current densities of 1.5 Ag-1 and larger, the specific capacitance of the EDLC using CNB was almost the same as that using AC. Electrochemical impedance spectroscopy of the EDLCs revealed that the CNB and CNC electrodes had a much lower internal resistance than the AC electrode, which correlated with a low capacitance maintenance factor as the current density increased.

  8. Surface functionality and electrochemical investigations of a graphitic electrode as a candidate for alkaline energy conversion and storage devices

    PubMed Central

    Soliman, Ahmed B.; Abdel-Samad, Hesham S.; Abdel Rehim, Sayed S.; Hassan, Hamdy H.

    2016-01-01

    Graphite is a typical electrocatalyst support in alkaline energy conversion and storage devices such as fuel cells, supercapacitores and lithium ion batteries. The electrochemical behaviour of a graphite electrode in 0.5 M NaOH was studied to elucidate its surface structure/electrochemical activity relationship. Graphite voltammograms are characterized by an anodic shoulder AI and a cathodic peak CI in addition to the oxygen reduction reaction plateaus, PI and PII. AI and CI were attributed to oxidation and reduction of some graphite surface function groups, respectively. Rotating ring disk electrode (RRDE) study revealed two different oxygen types assigned as inner and outer oxygen. The inner oxygen was reduced via the more efficient 4-electron pathway. The outer oxygen reduction proceeded with a lower efficient 2-electron pathway. The calculated percentages of the 4-electron pathway were ranged from 70% to 90%. A full mechanism for the graphite surface function groups changes over the studied potential window was suggested through the combination between the voltammetric, FT-IR and Raman results. PMID:26916054

  9. A Combined “Electrochemical–Frustrated Lewis Pair” Approach to Hydrogen Activation: Surface Catalytic Effects at Platinum Electrodes

    PubMed Central

    Lawrence, Elliot J; Blagg, Robin J; Hughes, David L; Ashley, Andrew E; Wildgoose, Gregory G

    2015-01-01

    Herein, we extend our “combined electrochemical–frustrated Lewis pair” approach to include Pt electrode surfaces for the first time. We found that the voltammetric response of an electrochemical–frustrated Lewis pair (FLP) system involving the B(C6F5)3/[HB(C6F5)3]− redox couple exhibits a strong surface electrocatalytic effect at Pt electrodes. Using a combination of kinetic competition studies in the presence of a H atom scavenger, 6-bromohexene, and by changing the steric bulk of the Lewis acid borane catalyst from B(C6F5)3 to B(C6Cl5)3, the mechanism of electrochemical–FLP reactions on Pt surfaces was shown to be dominated by hydrogen-atom transfer (HAT) between Pt, [Pt–H] adatoms and transient [HB(C6F5)3]⋅ electrooxidation intermediates. These findings provide further insight into this new area of combining electrochemical and FLP reactions, and proffers additional avenues for exploration beyond energy generation, such as in electrosynthesis. PMID:25382457

  10. Surface functionality and electrochemical investigations of a graphitic electrode as a candidate for alkaline energy conversion and storage devices

    NASA Astrophysics Data System (ADS)

    Soliman, Ahmed B.; Abdel-Samad, Hesham S.; Abdel Rehim, Sayed S.; Hassan, Hamdy H.

    2016-02-01

    Graphite is a typical electrocatalyst support in alkaline energy conversion and storage devices such as fuel cells, supercapacitores and lithium ion batteries. The electrochemical behaviour of a graphite electrode in 0.5 M NaOH was studied to elucidate its surface structure/electrochemical activity relationship. Graphite voltammograms are characterized by an anodic shoulder AI and a cathodic peak CI in addition to the oxygen reduction reaction plateaus, PI and PII. AI and CI were attributed to oxidation and reduction of some graphite surface function groups, respectively. Rotating ring disk electrode (RRDE) study revealed two different oxygen types assigned as inner and outer oxygen. The inner oxygen was reduced via the more efficient 4-electron pathway. The outer oxygen reduction proceeded with a lower efficient 2-electron pathway. The calculated percentages of the 4-electron pathway were ranged from 70% to 90%. A full mechanism for the graphite surface function groups changes over the studied potential window was suggested through the combination between the voltammetric, FT-IR and Raman results.

  11. A combined "electrochemical-frustrated lewis pair" approach to hydrogen activation: surface catalytic effects at platinum electrodes.

    PubMed

    Lawrence, Elliot J; Blagg, Robin J; Hughes, David L; Ashley, Andrew E; Wildgoose, Gregory G

    2015-01-07

    Herein, we extend our "combined electrochemical-frustrated Lewis pair" approach to include Pt electrode surfaces for the first time. We found that the voltammetric response of an electrochemical-frustrated Lewis pair (FLP) system involving the B(C6 F5 )3 /[HB(C6 F5 )3 ](-) redox couple exhibits a strong surface electrocatalytic effect at Pt electrodes. Using a combination of kinetic competition studies in the presence of a H atom scavenger, 6-bromohexene, and by changing the steric bulk of the Lewis acid borane catalyst from B(C6 F5 )3 to B(C6 Cl5 )3 , the mechanism of electrochemical-FLP reactions on Pt surfaces was shown to be dominated by hydrogen-atom transfer (HAT) between Pt, [PtH] adatoms and transient [HB(C6 F5 )3 ](⋅) electrooxidation intermediates. These findings provide further insight into this new area of combining electrochemical and FLP reactions, and proffers additional avenues for exploration beyond energy generation, such as in electrosynthesis.

  12. A Combined "Electrochemical-Frustrated Lewis Pair" Approach to Hydrogen Activation: Surface Catalytic Effects at Platinum Electrodes.

    PubMed

    Lawrence, Elliot J; Blagg, Robin J; Hughes, David L; Ashley, Andrew E; Wildgoose, Gregory G

    2014-11-06

    Herein, we extend our "combined electrochemical-frustrated Lewis pair" approach to include Pt electrode surfaces for the first time. We found that the voltammetric response of an electrochemical-frustrated Lewis pair (FLP) system involving the B(C6 F5 )3 /[HB(C6 F5 )3 ](-) redox couple exhibits a strong surface electrocatalytic effect at Pt electrodes. Using a combination of kinetic competition studies in the presence of a H atom scavenger, 6-bromohexene, and by changing the steric bulk of the Lewis acid borane catalyst from B(C6 F5 )3 to B(C6 Cl5 )3 , the mechanism of electrochemical-FLP reactions on Pt surfaces was shown to be dominated by hydrogen-atom transfer (HAT) between Pt, [PtH] adatoms and transient [HB(C6 F5 )3 ](⋅) electrooxidation intermediates. These findings provide further insight into this new area of combining electrochemical and FLP reactions, and proffers additional avenues for exploration beyond energy generation, such as in electrosynthesis.

  13. Suppression of Photoanodic Surface Oxidation of n-Type 6H-SiC Electrodes in Aqueous Electrolytes.

    PubMed

    Sachsenhauser, Matthias; Walczak, Karl; Hampel, Paul A; Stutzmann, Martin; Sharp, Ian D; Garrido, Jose A

    2016-02-16

    The photoelectrochemical characterization of silicon carbide (SiC) electrodes is important for enabling a wide range of potential applications for this semiconductor. However, photocorrosion of the SiC surface remains a key challenge, because this process considerably hinders the deployment of this material into functional devices. In this report, we use cyclic voltammetry to investigate the stability of n-type 6H-SiC photoelectrodes in buffered aqueous electrolytes. For measurements in pure Tris buffer, photogenerated holes accumulate at the interface under anodic polarization, resulting in the formation of a porous surface oxide layer. Two possibilities are presented to significantly enhance the stability of the SiC photoelectrodes. In the first approach, redox molecules are added to the buffer solution to kinetically facilitate hole transfer to these molecules, and in the second approach, water oxidation in the electrolyte is induced by depositing a cobalt phosphate catalyst onto the semiconductor surface. Both methods are found to effectively suppress photocorrosion of the SiC electrodes, as confirmed by atomic force microscopy and X-ray photoelectron spectroscopy measurements. The presented study provides straightforward routes to stabilize n-type SiC photoelectrodes in aqueous electrolytes, which is essential for a possible utilization of this material in the fields of photocatalysis and multimodal biosensing.

  14. H2 production in membraneless bioelectrochemical cells with optimized architecture: The effect of cathode surface area and electrode distance.

    PubMed

    Rivera, Isaac; Bakonyi, Péter; Buitrón, Germán

    2017-03-01

    In this work we report on the hydrogen production capacity of single-chamber microbial electrohydrogenesis cell (MEC) with optimized design characteristics, in particular cathode surface area and anode-cathode spacing using acetate as substrate. The results showed that the maximal H2 production rates and best energetic performances could be obtained using the smallest, 71 cm(2) stainless steel cathode and 4 cm electrode distances, employing a 60 cm(2) bioanode. Cyclic voltammetric analysis was employed to investigate the dominant electron transfer mechanism of the architecturally optimized system.

  15. Colonization by Cladosporium spp. of painted metal surfaces associated with heating and air conditioning systems

    NASA Technical Reports Server (NTRS)

    Ahearn, D. G.; Simmons, R. B.; Switzer, K. F.; Ajello, L.; Pierson, D. L.

    1991-01-01

    Cladosporium cladosporioides and C. hebarum colonized painted metal surfaces of covering panels and register vents of heating, air conditioning and ventilation systems. Hyphae penetrated the paint film and developed characteristic conidiophores and conidia. The colonies were tightly appressed to the metal surface and conidia were not readily detectable via standard air sampling procedures.

  16. Formation of macroscopic surface layers on Fe(0) electrocoagulation electrodes during an extended field trial of arsenic treatment.

    PubMed

    van Genuchten, Case M; Bandaru, Siva R S; Surorova, Elena; Amrose, Susan E; Gadgil, Ashok J; Peña, Jasquelin

    2016-06-01

    Extended field trials to remove arsenic (As) via Fe(0) electrocoagulation (EC) have demonstrated consistent As removal from groundwater to concentrations below 10 μg L(-1). However, the coulombic performance of long-term EC field operation is lower than that of laboratory-based systems. Although EC electrodes used over prolonged periods show distinct passivation layers, which have been linked to decreased treatment efficiency, the spatial distribution and mineralogy of such surface layers have not been investigated. In this work, we combine wet chemical measurements with sub-micron-scale chemical maps and selected area electron diffraction (SAED) to determine the chemical composition and mineral phase of surface layers formed during long-term Fe(0) EC treatment. We analyzed Fe(0) EC electrodes used for 3.5 months of daily treatment of As-contaminated groundwater in rural West Bengal, India. We found that the several mm thick layer that formed on cathodes and anodes consisted of primarily magnetite, with minor fractions of goethite. Spatially-resolved SAED patterns also revealed small quantities of CaCO3, Mn oxides, and SiO2, the source of which was the groundwater electrolyte. We propose that the formation of the surface layer contributes to decreased treatment performance by preventing the migration of EC-generated Fe(II) to the bulk electrolyte, where As removal occurs. The trapped Fe(II) subsequently increases the surface layer size at the expense of treatment efficiency. Based on these findings, we discuss several simple and affordable methods to prevent the efficiency loss due to the surface layer, including alternating polarity cycles and cleaning the Fe(0) surface mechanically or via electrolyte scouring.

  17. Towards combined electrochemistry and surface-enhanced resonance Raman of heme proteins: Improvement of diffusion electrochemistry of cytochrome c at silver electrodes chemically modified with 4-mercaptopyridine.

    PubMed

    Millo, Diego; Ranieri, Antonio; Koot, Wynanda; Gooijer, Cees; van der Zwan, Gert

    2006-08-01

    To date, a successful combination of surface-enhanced resonance Raman spectroscopy (SERRS) and electrochemistry to study heme proteins is inhibited by the problems raised by the prerequisite to use silver as electrode metal. This paper indicates an approach to overcome these problems. It describes a quick and reproducible procedure to prepare silver electrodes chemically modified with 4-mercaptopyridine suitable to perform diffusion electrochemistry of cytochrome c (cyt c). The method involves the employment of a mechanical and a chemical treatment and avoids the use of alumina slurries and any electrochemical pretreatment. Cyclic voltammetry (CV) was used to test the electrochemical response of cyt c, and the CV signals were found identical with those obtained on gold electrodes under the same experimental conditions. Compared to previous literature, a significant improvement of the CV signal of cyt c at silver electrodes was achieved. Preliminary results show that this treatment can be also successfully employed for the preparation of SERRS-active electrodes.

  18. Uncertainties of satellite-derived surface skin temperatures in the polar oceans: MODIS, AIRS/AMSU, and AIRS only

    NASA Astrophysics Data System (ADS)

    Kang, H.-J.; Yoo, J.-M.; Jeong, M.-J.; Won, Y.-I.

    2015-05-01

    Uncertainties in the satellite-derived Surface Skin Temperature (SST) data in the polar oceans during two periods (16-24 April and 15-23 September) of 2003-2014 were investigated and the three datasets were intercompared as follows: MODerate Resolution Imaging Spectroradiometer Ice Surface Temperature (MODIS IST), the SST of the Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit-A (AIRS/AMSU), and AIRS only. AIRS only algorithm was developed in preparation for the degradation of the AMSU-A. MODIS IST was systematically up to 1.65 K warmer at the sea ice boundary and up to 2.04 K colder in the polar sea ice regions of both the Arctic and Antarctic than that of the AIRS/AMSU. This difference in the results could have been caused by the surface classification method. The spatial correlation coefficient of the AIRS only to the AIRS/AMSU (0.992-0.999) method was greater than that of the MODIS IST to the AIRS/AMSU (0.968-0.994). The SST of the AIRS only compared to that of the AIRS/AMSU had a bias of 0.168 K with a RMSE of 0.590 K over the Northern Hemisphere high latitudes and a bias of -0.109 K with a RMSE of 0.852 K over the Southern Hemisphere high latitudes. There was a systematic disagreement between the AIRS retrievals at the boundary of the sea ice, because the AIRS only algorithm utilized a~less accurate GCM forecast over the seasonally-varying frozen oceans than the microwave data. The three datasets (MODIS, AIRS/AMSU and AIRS only) showed significant warming rates (2.3 ± 1.7 ~2.8 ± 1.9 K decade-1) in the northern high latitude regions (70-80° N) as expected from the ice-albedo feedback. The systematic temperature disagreement associated with surface type classification had an impact on the resulting temperature trends.

  19. Uncertainties of satellite-derived surface skin temperatures in the polar oceans: MODIS, AIRS/AMSU, and AIRS only

    NASA Astrophysics Data System (ADS)

    Kang, H.-J.; Yoo, J.-M.; Jeong, M.-J.; Won, Y.-I.

    2015-10-01

    Uncertainties in the satellite-derived surface skin temperature (SST) data in the polar oceans during two periods (16-24 April and 15-23 September) 2003-2014 were investigated and the three data sets were intercompared as follows: MODerate Resolution Imaging Spectroradiometer Ice Surface Temperature (MODIS IST), the SST of the Atmospheric Infrared Sounder/Advanced Microwave Sounding Unit-A (AIRS/AMSU), and AIRS only. The AIRS only algorithm was developed in preparation for the degradation of the AMSU-A. MODIS IST was systematically warmer up to 1.65 K at the sea ice boundary and colder down to -2.04 K in the polar sea ice regions of both the Arctic and Antarctic than that of the AIRS/AMSU. This difference in the results could have been caused by the surface classification method. The spatial correlation coefficient of the AIRS only to the AIRS/AMSU (0.992-0.999) method was greater than that of the MODIS IST to the AIRS/AMSU (0.968-0.994). The SST of the AIRS only compared to that of the AIRS/AMSU had a bias of 0.168 K with a RMSE of 0.590 K over the Northern Hemisphere high latitudes and a bias of -0.109 K with a RMSE of 0.852 K over the Southern Hemisphere high latitudes. There was a systematic disagreement between the AIRS retrievals at the boundary of the sea ice, because the AIRS only algorithm utilized a less accurate GCM forecast over the seasonally varying frozen oceans than the microwave data. The three data sets (MODIS, AIRS/AMSU and AIRS only) showed significant warming rates (2.3 ± 1.7 ~ 2.8 ± 1.9 K decade-1) in the northern high regions (70-80° N) as expected from the ice-albedo feedback. The systematic temperature disagreement associated with surface type classification had an impact on the resulting temperature trends.

  20. Numerical Investigation of Engine Inlet Vane Hot-Air Anti-Icing System with Surface Air Film

    NASA Astrophysics Data System (ADS)

    Ma, Hui; Chen, Weijian; Zhang, Dalin

    The inlet vane of aircraft engine needs to be equipped with anti-icing system to prevent ice accretion on the leading edge due to flight safety requirements, and the engine bleed hot-air is mostly used to heat the vane surface in anti-icing system. In order to save the energy consumption, a new anti-icing structure was developed and investigated with numerical simulation. Besides the use of small tunnels to enhance the heat transfer characteristics, a narrow gap was opened and assigned on the vane surface at the end of the anti-icing tunnels, and the exhaust hot-air was released from the gap to form an air film on the outside surface, which was supposed to prevent the droplets from impinging to the surface and sweep the droplets away. The droplets impingement on the vane surface was investigated by solving the 3D Eulerian air/droplets twophase model, and the impingement results were compared with the original system. Meanwhile, the thermodynamic analysis of the anti-icing system was presented in this paper. The results indicate that the air film is effective to decrease the droplets impingement area, and the new structure could provide more heat flux for anti-icing than the regular anti-icing structure.

  1. Skating on a Film of Air: Drops Impacting on a Surface

    NASA Astrophysics Data System (ADS)

    Kolinski, John M.; Rubinstein, Shmuel M.; Mandre, Shreyas; Brenner, Michael P.; Weitz, David A.; Mahadevan, L.

    2012-02-01

    The commonly accepted description of drops impacting on a surface typically ignores the essential role of the air that is trapped between the impacting drop and the surface. Here we describe a new imaging modality that is sensitive to the behavior right at the surface. We show that a very thin film of air, only a few tens of nanometers thick, remains trapped between the falling drop and the surface as the drop spreads. The thin film of air serves to lubricate the drop enabling the fluid to skate on the air film laterally outward at surprisingly high velocities, consistent with theoretical predictions. Eventually this thin film of air breaks down as the fluid wets the surface via a spinodal-like mechanism. Our results show that the dynamics of impacting drops are much more complex than previously thought, with a rich array of unexpected phenomena that require rethinking classic paradigms.

  2. High performance cermet electrodes

    DOEpatents

    Isenberg, Arnold O.; Zymboly, Gregory E.

    1986-01-01

    Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

  3. Electrochemical, interfacial, and surface studies of the conversion of carbon dioxide to liquid fuels on tin electrodes

    NASA Astrophysics Data System (ADS)

    Wu, Jingjie

    maximize the triple phase boundary length for simultaneous high current density and selectivity towards formate formation (Chapter 3). The Sn GDEs was incorporated into a home-designed scalable full electrochemical cell which features a buffer layer of circulating liquid electrolyte mediating the proton concentration at cathode electrode surface. The Sn GDEs exhibited excellent short-term performance for CO2 reduction with high selectivity towards formate formation at low overpotentials in the full electrochemical cell. Additionally, coupling water oxidation and CO2 reduction was demonstrated in this full electrochemical cell to mimic biosynthesis (Chapter 4). The rapid degradation of selectivity towards formate formation on Sn GDEs in the full electrochemical cell, however, was observed during long-term operation. The degradation mechanism was unraveled due to the decrease of electrode potential resulted from substantial increase of internal ohmic resistance of the full electrochemical cell. The unexpected rise of internal ohmic resistance was attributed to the pulverization of 100 nm Sn nanoparticles due to the hydrogen diffusion induced stress. Based on the understanding of the origin of Sn nanoparticles pulverization, SnO2 nanoparticles of 3˜3.5 nm close to the critical size were utilized and reduced in situ to form Sn catalyst for electrochemical reduction of CO2. The pulverization was suppressed and subsequently a stable performance of electrodes was obtained (Chapter 5). Due to the affinity to oxygen, Sn nanoparticle surface is covered by a native thin oxide layer. The performance of Sn GDEs towards CO2 reduction strongly depends on the initial thickness of the surface oxide layer. The selectivity towards formate production dropped while the hydrogen yield increased as the initial thickness of the oxide layer increased (Chapter 6). These results suggest the underlying of surface structure on the selectivity of Sn electrode for CO2 reduction and provide insight into

  4. Comparisons between Surface-Enhanced Raman and Surface Infrared Spectroscopies for Strongly Perturbed Adsorbates: Thiocyanate at Gold Electrodes.

    DTIC Science & Technology

    1986-07-30

    tu. 3. iptt FCSa, s CATALOG NUtof SBetween Surface -Enhanced Raman anj$ YEO EOTI EIDCvfr Surface Infared Spectroscopies for StrongiV Technical Report...REPORT 8 49 0Comparisons Between Surface-Enhanced Raman and Surface Infrared Spectroscopies for Strongly Perturbed Adsorbates: Thiocyanate at Gold...for thiocyanate adsorbed at the gold-aqueous interface is examined by both surface-enhanced Raman spectroscopy (SERS) and subtractively normalized

  5. Promotional effect of surface hydroxyls on electrochemical reduction of CO2 over SnOx/Sn electrode

    DOE PAGES

    Cui, Chaonan; Han, Jinyu; Zhu, Xinli; ...

    2016-01-16

    In this study, tin oxide (SnOx) formation on tin-based electrode surfaces during CO2 electrochemical reduction can have a significant impact on the activity and selectivity of the reaction. In the present study, density functional theory (DFT) calculations have been performed to understand the role of SnOx in CO2 reduction using a SnO monolayer on the Sn(112) surface as a model for SnOx. Water molecules have been treated explicitly and considered actively participating in the reaction. The results showed that H2O dissociates on the perfect SnO monolayer into two hydroxyl groups symmetrically on the surface. CO2 energetically prefers to react withmore » the hydroxyl, forming a bicarbonate (HCO3(t)*) intermediate, which can then be reduced to either formate (HCOO*) by hydrogenating the carbon atom or carboxyl (COOH*) by protonating the oxygen atom. Both steps involve a simultaneous Csingle bondO bond breaking. Further reduction of HCOO* species leads to the formation of formic acid in the acidic solution at pH < 4, while the COOH* will decompose to CO and H2O via protonation. Whereas the oxygen vacancy (VO) in the oxide monolayer maybe formed by the reduction, it can be recovered by H2O dissociation, resulting in two embedded hydroxyl groups. The results show that the hydroxylated surface with two symmetric hydroxyls is energetically more favorable for CO2 reduction than the hydroxylated VO surface with two embedded hydroxyls. The reduction potential for the former has a limiting-potential of –0.20 V (RHE), lower than that for the latter (–0.74 V (RHE)). Compared to the pure Sn electrode, the formation of SnOx monolayer on the electrode under the operating conditions promotes CO2 reduction more effectively by forming surface hydroxyls, thereby providing a new channel via COOH* to the CO formation, although formic acid is still the major reduction product.« less

  6. Promotional effect of surface hydroxyls on electrochemical reduction of CO2 over SnOx/Sn electrode

    SciTech Connect

    Cui, Chaonan; Han, Jinyu; Zhu, Xinli; Liu, Xiao; Wang, Hua; Mei, Donghai; Ge, Qingfeng

    2016-11-01

    Tin oxide (SnOx) formation on tin-based electrode surfaces during CO2 electrochemical reduction can have a significant impact on the activity and selectivity of the reaction. In the present study, density functional theory (DFT) calculations have been performed to understand the role of SnOx in CO2 reduction using a SnO monolayer on the Sn(112) surface as a model for SnOx. Water molecules have been treated explicitly and considered actively participating in the reaction. The results showed that H2O dissociates on the perfect SnO monolayer into two hydroxyl groups symmetrically on the surface. CO2 energetically prefers to react with the hydroxyl, forming a bicarbonate (HCO3(t)*) intermediate, which can then be reduced to either formate (HCOO*) by hydrogenating the carbon atom or carboxyl (COOH*) by protonating the oxygen atom. Both steps involve a simultaneous C-O bond breaking. Further reduction of HCOO* species leads to the formation of formic acid in the acidic solution at pH < 4, while the COOH* will decompose to CO and H2O via protonation. Whereas the oxygen vacancy (VO) in the monolayer maybe formed by the reduction of the monolayer, it can be recovered by H2O dissociation, resulting in two embedded hydroxyl groups. However, the hydroxylated surface with two symmetric hydroxyls is energetically more favorable for CO2 reduction than the hydroxylated VO surface with two embedded hydroxyls. The reduction potential for the former has a limiting-potential of -0.20 V (RHE), lower than that for the latter (-0.74 V (RHE)). Compared to the pure Sn electrode, the formation of SnOx monolayer on the electrode under the operating conditions promotes CO2 reduction more effectively by forming surface hydroxyls, thereby, providing a new channel via COOH* to the CO formation, although formic acid is still the major reduction product. The work was supported in part by National Natural Sciences Foundation of China (Grant #21373148 and #21206117). The High Performance Computing

  7. Fuel cell electrodes

    DOEpatents

    Strmcnik, Dusan; Cuesta, Angel; Stamenkovic, Vojislav; Markovic, Nenad

    2015-06-23

    A process includes patterning a surface of a platinum group metal-based electrode by contacting the electrode with an adsorbate to form a patterned platinum group metal-based electrode including platinum group metal sites blocked with adsorbate molecules and platinum group metal sites which are not blocked.

  8. Development of a large support surface for an air-bearing type zero-gravity simulator

    NASA Technical Reports Server (NTRS)

    Glover, K. E.

    1976-01-01

    The methods used in producing a large, flat surface to serve as the supporting surface for an air-bearing type zero-gravity simulator using low clearance, thrust-pad type air bearings are described. Major problems encountered in the use of self-leveled epoxy coatings in this surface are discussed and techniques are recommended which proved effective in overcoming these problems. Performance requirements of the zero-gravity simulator vehicle which were pertinent to the specification of the air-bearing support surface are also discussed.

  9. Generation of gold nanostructures at the surface of platinum electrode by electrodeposition for ECL detection for CE.

    PubMed

    Cao, Guangming; Liu, Qian; Huang, Yan; Li, Wang; Yao, Shouzhuo

    2010-03-01

    In this paper, we report a sensitive method for ECL detection for CE based on generation of gold nanostructures at the surface of Pt electrode by electrodeposition. Difenidol hydrochloride was used as a model analyte. With the increase of electrodeposition amount, the morphology of gold nanostructures changed from discrete nanoflowers to dense nanoparticle array. Interestingly, the variation of deposition amount also greatly affected the ECL intensity of difenidol. The ECL intensity increased remarkably with deposition amount and reached the maximum value at the deposition amount of 7.0 x 10(-8)C; further increasing the deposition amount, however, caused the ECL intensity to decrease. Other conditions, including applied potential, injection time and voltage, buffer pH, were also optimized in detail. Under the optimized conditions, the linear response range of difenidol is from 1.0 x 10(-8) to 5.0 x 10(-5) M, and the detection limit was 4.0 x 10(-9) M (S/N=3). The RSDs of ECL intensity and migration time were 2.0 and 1.6%, respectively (n=5, at 7.5 microM difenidol). Compared with using bare electrode, the detection sensitivity was significantly improved by ca. two orders of magnitude. Notably, the nanogold was prepared at the surface of electrode and no nanogold was added to the electrophoretic buffer or detection cell, thus causing no interference to the separation. Finally, the proposed method was successfully applied to the analysis of difenidol in tablets and urine samples. With high sensitivity and good reproducibility, this method provides a promising platform for the determination of pharmaceuticals that have a tertiary amine group such as difenidol.

  10. Micromachined electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.

    2007-12-11

    An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

  11. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.; Christenson, Todd R.

    2006-10-24

    An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

  12. High frequency reference electrode

    DOEpatents

    Kronberg, James W.

    1994-01-01

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

  13. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

  14. Recirculating electric air filter

    DOEpatents

    Bergman, W.

    1985-01-09

    An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

  15. Magnetohydrodynamic electrode

    DOEpatents

    Marchant, David D.; Killpatrick, Don H.

    1978-01-01

    An electrode capable of withstanding high temperatures and suitable for use as a current collector in the channel of a magnetohydrodynamic (MHD) generator consists of a sintered powdered metal base portion, the upper surface of the base being coated with a first layer of nickel aluminide, an intermediate layer of a mixture of nickel aluminide - refractory ceramic on the first layer and a third or outer layer of a refractory ceramic material on the intermediate layer. The sintered powdered metal base resists spalling by the ceramic coatings and permits greater electrode compliance to thermal shock. The density of the powdered metal base can be varied to allow optimization of the thermal conductivity of the electrode and prevent excess heat loss from the channel.

  16. The EUSTACE project: delivering global, daily information on surface air temperature

    NASA Astrophysics Data System (ADS)

    Morice, C. P.; Rayner, N. A.; Auchmann, R.; Bessembinder, J.; Bronnimann, S.; Brugnara, Y.; Conway, E. A.; Ghent, D.; Good, E.; Herring, K.; Kennedy, J.; Lindgren, F.; Madsen, K. S.; Merchant, C. J.; van der Schrier, G.; Stephens, A.; Tonboe, R. T.; Waterfall, A. M.; Mitchelson, J.; Woolway, I.

    2015-12-01

    Day-to-day variations in surface air temperature affect society in many ways; however, daily surface air temperature measurements are not available everywhere. A global daily analysis cannot be achieved with measurements made in situ alone, so incorporation of satellite retrievals is needed. To achieve this, we must develop an understanding of the relationships between traditional (land and marine) surface air temperature measurements and retrievals of surface skin temperature from satellite measurements, i.e. Land Surface Temperature, Ice Surface Temperature, Sea Surface Temperature and Lake Surface Water Temperature. These relationships can be derived either empirically or with the help of a physical model.Here we discuss the science needed to produce a fully-global daily analysis (or ensemble of analyses) of surface air temperature on the centennial scale, integrating different ground-based and satellite-borne data types. Information contained in the satellite retrievals would be used to create globally-complete fields in the past, using statistical models of how surface air temperature varies in a connected way from place to place. As the data volumes involved are considerable, such work needs to include development of new "Big Data" analysis methods.We will present plans and progress along this road in the EUSTACE project (2015-June 2018), i.e.: • providing new, consistent, multi-component estimates of uncertainty in surface skin temperature retrievals from satellites; • identifying inhomogeneities in daily surface air temperature measurement series from weather stations and correcting for these over Europe; • estimating surface air temperature over all surfaces of Earth from surface skin temperature retrievals; • using new statistical techniques to provide information on higher spatial and temporal scales than currently available, making optimum use of information in data-rich eras.Information will also be given on how interested users can become

  17. Charge trapping induced by plasma in alumina electrode surface investigated by thermoluminescence and optically stimulated luminescence

    SciTech Connect

    Ambrico, P. F.; Ambrico, M.; Schiavulli, L.; Ligonzo, T.; Augelli, V.

    2009-02-02

    The plasma of a dielectric barrier discharge can fill traps in the alumina that cover the electrode. Trap energies and lifetimes are estimated by thermoluminescence and optically stimulated luminescence. Comparison with similar results for traps created by other radiation sources clarifies the mechanisms regulating this effect. Alumina's trap energies are approximately 1 eV, and the traps remain active for several days after plasma exposure. These results could be important to keep dielectric barrier discharge plasmas uniform since a trapped charge can be an electron reservoir.

  18. Microfabricated Surface-Electrode Ion Trap for Scalable Quantum Information Processing

    NASA Astrophysics Data System (ADS)

    Seidelin, S.; Chiaverini, J.; Reichle, R.; Bollinger, J. J.; Leibfried, D.; Britton, J.; Wesenberg, J. H.; Blakestad, R. B.; Epstein, R. J.; Hume, D. B.; Itano, W. M.; Jost, J. D.; Langer, C.; Ozeri, R.; Shiga, N.; Wineland, D. J.

    2006-06-01

    Individual laser-cooled Mg+24 ions are confined in a linear Paul trap with a novel geometry where gold electrodes are located in a single plane and the ions are trapped 40μm above this plane. The relatively simple trap design and fabrication procedure are important for large-scale quantum information processing (QIP) using ions. Measured ion motional frequencies are compared to simulations. Measurements of ion recooling after cooling is temporarily suspended yield a heating rate of approximately 5 motional quanta per millisecond for a trap frequency of 2.83 MHz, sufficiently low to be useful for QIP.

  19. Surface chemical analysis of CuO nanofiber composite electrodes at different stages of lithiation/delithiation

    NASA Astrophysics Data System (ADS)

    Gangaja, Binitha; Chandrasekharan, Sruthi; Vadukumpully, Sajini; Nair, Shantikumar V.; Santhanagopalan, Dhamodaran

    2017-02-01

    High aspect ratio, electrospun CuO nanofibers have been fabricated and tested for its electrochemical performance as lithium ion battery anode. These nanofibers are composed of CuO nanoparticles about 35-40 nm in size forming good inter-connected network. Fabricated half cells maintained specific capacity of 310 mAh g-1 at 1C rate for 100 cycles and stabilized capacity of about 120 mAh g-1 at 5C rate for 1000 cycles. Ex situ x-ray photoelectron spectroscopy (XPS) was performed to understand the electrodes surface chemical changes at the end of first discharge, first charge and after tenth charge. The solid electrolyte interface (SEI) layer comprised of LiF, Li2CO3 and Li2O while their quantity varied depending on the stage of lithiation/delithiation. Initially, no copper signal is observed on the surface of the SEI layer. However, in situ sputtering of the electrodes in the XPS chamber revealed that at the end of first discharge, formation Cu0 with detectable fraction of LixCuO2 and hydroxide in the SEI layer. At the end of first charge, a large fraction of Cu2O phase with a small fraction of hydroxide is observed. At the end of 10th charge no change in SEI layer content but increase in thickness was observed.

  20. New electrosurgical ball electrode with nonstick properties

    NASA Astrophysics Data System (ADS)

    Rondinone, Joseph; Brassell, James; Miller, Scott A., III; Thorne, Jonathan O.; Rondinone, David M.; Safabash, Jason; Vega, Felix

    1998-04-01

    A new electrosurgical ball electrode (SilverBulletTM) has been developed for applying radiofrequency (RF) energy to fuse biological and other materials to tissue surfaces. Specifically, the electrode was developed for use in conjunction with the Fusion Medical Technologies, Inc. gelatin patch (RapiSealTM) for use in pulmonary surgery to seal air leaks, and in solid abdominal organ surgeries to provide hemostatic tamponade. The new electrode allows for the application of RF energy in contact mode without the problems of the electrode sticking to the gelatin patch or the underlying tissue. Designed for use with commercially available electrosurgical handpieces, the electrode consists of a stainless steel connector that fits into the hand- piece, and an electrode assembly made from silver that includes a shank region, and a tip extension extending distally from the shank region. The distal tip of the tip extension is rounded and has a length of about 10 mm. The uniqueness of this electrode is the shank region which has a cross sectional area that is larger than the tip extension. The shank region acts as a heat sink to draw away heat from the tip extension while the tip extension itself remains sufficiently small to access desired target sites and display the desired energy transfer properties. In addition to the physical design, the use of silver as the core element provides a material with high electrical and thermal conductivities. The bulk of the electrode is appropriately insulated.

  1. Foam Generation and Air Entrainment Near a Free Surface

    DTIC Science & Technology

    1987-09-30

    plunging jets and by the action of turbulent eddies in water flowing over spillways has been discussed by several authors. Data for the entrained air flow...r = mean jet radius. 1 They determined the size of the region in the liquid which was affected by air entrainment and mea- sured the...Spilling Breaker," J. Fluid Mech., Vol. 63, 1. E.J. McKeogh and D.A. Ervine, 1981, " Air Entrainment Rate and Diffusion Pattern of Plunging Liquid

  2. Electrochemical synthesis of gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode and their application

    NASA Astrophysics Data System (ADS)

    Song, Y. Z.; Li, X.; Song, Y.; Cheng, Z. P.; Zhong, H.; Xu, J. M.; Lu, J. S.; Wei, C. G.; Zhu, A. F.; Wu, F. Y.; Xu, J.

    2013-01-01

    Gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode were prepared using electrochemical synthesis method. The thin films of gold Nanoparticles/multi-walled carbon nanotubes were characterized by scanning electron microscopy, powder X-ray diffraction, and cyclic voltammetry. Electrochemical behavior of adrenaline hydrochloride at gold nanoparticles/multi-walled carbon nanotube modified glassy carbon electrode was investigated. A simple, sensitive, and inexpensive method for determination of adrenaline hydrochloride was proposed.

  3. Facile in situ characterization of gold nanoparticles on electrode surfaces by electrochemical techniques: average size, number density and morphology determination.

    PubMed

    Wang, Ying; Laborda, Eduardo; Salter, Chris; Crossley, Alison; Compton, Richard G

    2012-10-21

    A fast and cheap in situ approach is presented for the characterization of gold nanoparticles from electrochemical experiments. The average size and number of nanoparticles deposited on a glassy carbon electrode are determined from the values of the total surface area and amount of gold obtained by lead underpotential deposition and by stripping of gold in hydrochloric acid solution, respectively. The morphology of the nanoparticle surface can also be analyzed from the "fingerprint" in lead deposition/stripping experiments. The method is tested through the study of gold nanoparticles deposited on a glassy carbon substrate by seed-mediated growth method which enables an easy control of the nanoparticle size. The procedure is also applied to the characterization of supplied gold nanoparticles. The results are in satisfactory agreement with those obtained via scanning electron microscopy.

  4. Optimization of the Air Apportionment in a Tac Thunder Scenario Using Response Surface Methodology

    DTIC Science & Technology

    1994-03-01

    AD-A278 494 L" t22$ OPTIMIZATION OF THE AIR APPORTIONMENT IN A TAC THUNDER SCENARIO USING RESPONSE SURFACE METHODOLOGY THESIS Steven Lee Forsythe...Availability Codes Avail and /or Dist Special OPTIMIZATION OF THE AIR APPORTIONMENT IN A TAC THUNDER SCENARIO USING RESPONSE SURFACE METHODOLOGY ...Using Response Surface Methodology DEFENSE DATE: 01 March 94 COMMITTEE: NAME/DEPARTMENT SIGNATURE Advisor: Lt Col Paul F. Auclair 6.d .4 Assistant

  5. Navy Shipboard Lasers for Surface, Air, and Missile Defense: Background and Issues for Congress

    DTIC Science & Technology

    2010-12-09

    include IPG Photonics (the maker of the fiber SSLs), L- 3 Communications, (continued...) Navy Shipboard Lasers for Surface, Air, and Missile Defense...DATE 09 DEC 2010 2. REPORT TYPE 3 . DATES COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Navy Shipboard Lasers for Surface, Air, and...surface ships— fiber solid state lasers (SSLs), slab SSLs, and free electron lasers (FELs). The Navy’s fiber SSL prototype demonstrator is called the

  6. Navy Shipboard Lasers for Surface, Air, and Missile Defense: Background and Issues for Congress

    DTIC Science & Technology

    2011-04-08

    the maker of the fiber SSLs), L- 3 Communications, (continued...) Navy Shipboard Lasers for Surface, Air, and Missile Defense Congressional Research...08 APR 2011 2. REPORT TYPE 3 . DATES COVERED 00-00-2011 to 00-00-2011 4. TITLE AND SUBTITLE Navy Shipboard Lasers for Surface, Air, and...ballistic missile (ASBM). The Navy and DOD are developing three principal types of lasers for potential use on Navy surface ships— fiber solid state

  7. An Experimental Investigation of Skin Friction on Smooth Surfaces Supporting Air Bearing Channels.

    DTIC Science & Technology

    1986-07-01

    EXPERIMENTAL INVESTIGATION OF SKIN FRICTION ON SMOOTH SURFACES SUPPORTING AIR BEARING CHANNELS ETUDE EXPERIMENTALE DU FROTTEMENT PELLICULAIRE SUR DES SURFACES...LISSES PORTEUSES DE CANAUX ANTI- FROTTEMENT by/par M. Khalid National Aeronautical Establishment AERONAUTICAL NOTE OTTAWA NAE-AN-39 JULY 1986 NRC NO...installant sur la surface des canaux qui agissent comme des valiers d’air. Les mesures ont &t prises A l’aide d’une balance de mesure du frottement

  8. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  9. High performance methanol-oxygen fuel cell with hollow fiber electrode

    NASA Technical Reports Server (NTRS)

    Lawson, Daniel D. (Inventor); Ingham, John D. (Inventor)

    1983-01-01

    A methanol/air-oxygen fuel cell including an electrode formed by open-ended ion-exchange hollow fibers having a layer of catalyst deposited on the inner surface thereof and a first current collector in contact with the catalyst layer. A second current collector external of said fibers is provided which is immersed along with the hollow fiber electrode in an aqueous electrolyte body. Upon passage of air or oxygen through the hollow fiber electrode and introduction of methanol into the aqueous electrolyte, a steady current output is obtained. Two embodiments of the fuel cell are disclosed. In the first embodiment the second metal electrode is displaced away from the hollow fiber in the electrolyte body while in the second embodiment a spiral-wrap electrode is provided about the outer surface of the hollow fiber electrode.

  10. The Effects of TI/PT Bottom Electrode on Crystallographic and Surface Characteristics of PZT Thick Films

    NASA Astrophysics Data System (ADS)

    Koochekzadeh, Ali; Keshavarz Alamdari, Eskandar; Barzegar, Abdolghafar

    The ceramic lead zirconate titanate (PZT) films near the morphotropic phase boundary are successfully integrated into MEMS devices, especially for applications in microsensors and actuators. The ferro/piezo electric properties of PZT thick films are widely dependent on its surface quality and crystallographic orientation growth. This paper indicates the influences of platinum bottom electrode on the surface and crystallographic properties of PZT. Ti (10nm) and Pt (100nm) thin films have been deposited on silicon substrate by thermal evaporation and electron beam respectively without vacuum breaking. After annealing treatment, the Pt film exhibited (111) preferred orientation. Finally one micron thick PZT (54/46) film was deposited by a RF magnetron sputtering at room temperature in pure Argon followed by a conventional post annealing treatment on silicon substrate. The XRD measurements have shown the provskite structure of PZT films with (100) preferred orientation at annealing temperatures above 600°C and (111) preferred orientation above 650°c. The SEM results demonstrate that whatever the annealing temperature is increased, recrystallization grains and black holes on Pt surface occurs and cause morphological change of PZT surface. The AFM test shows the strong RMS roughness of platinum surface after annealing temperature at 650°C.

  11. Failure Mechanisms of Air Entrainment in Drop Impact on Lubricated Surfaces

    NASA Astrophysics Data System (ADS)

    Pack, Min; Hu, Han; Kim, Dong-Ook; Zheng, Zhong; Stone, Howard; Sun, Ying; Drexel University Team; Princeton University Team

    2016-11-01

    Lubricated surfaces have recently been introduced and studied due to their potential benefit in various applications. Combining the techniques of total internal reflection microscopy and reflection interference microscopy, we examine the dynamics of an underlying air film upon drop impact on a lubricated substrate. In contrast to drop impact on solid surfaces where asperities cause random breakup of the entraining air film, we report two air film failure mechanisms on lubricated surfaces. In particular, using thin liquid films of high viscosity, we show that air film rupture shifts from a randomly driven to a controlled event. At low Weber numbers (We) the droplet bounces. At intermediate We, the air film fails at the center as the drop top surface crashes downward owing to impact-induced capillary waves; the resulting liquid-liquid contact time is found to be independent of We. In contrast, at high We, the air film failure occurs much earlier in time at the first inflection point of the air film shape away from the drop center, where the liquid-liquid van der Waals interactions become important. The predictable failure modes of the air film upon drop impact sheds light on droplet deposition in applications such as lubricant-infused self-cleaning surfaces. Support for this work was provided by the National Science Foundation under Grant No. CMMI-1401438 to Y.S.

  12. Visualization and measurement of the air film close ultra-hydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Jasikova, D.; Gasic, M.; Kotek, M.; Kopecky, Václav

    2016-11-01

    The ultra-hydrophobic surfaces have the prospect of great importance in industry, both in applications demanding easy cleaning, and they are presumed to reduce loss when the active parts of hydraulic machines are treated. Interaction of fluids with ultra-hydrophobic surface is accompanied by creation of layer of air, so called air film, which depends on the quality of the surface. The quality of the surface is influenced by the matrix roughness, the character of physical or chemical cover. This properties lead to monolithic air layer presented as air film, or lead to plurality of bubbles of various sizes seated upon the surface. The air film can be observed visually at sufficient magnification and the dynamic interaction between fluid flow and air film can be studied with Global Imaging methods, particularly Particle Image Velocimetry (PIV). There is the velocity profile in the vicinity of the air film in the main interest of the research. Here we present the visualization of air film depending on Reynolds number of flowing liquid.

  13. Land Surface Process and Air Quality Research and Applications at MSFC

    NASA Technical Reports Server (NTRS)

    Quattrochi, Dale; Khan, Maudood

    2007-01-01

    This viewgraph presentation provides an overview of land surface process and air quality research at MSFC including atmospheric modeling and ongoing research whose objective is to undertake a comprehensive spatiotemporal analysis of the effects of accurate land surface characterization on atmospheric modeling results, and public health applications. Land use maps as well as 10 meter air temperature, surface wind, PBL mean difference heights, NOx, ozone, and O3+NO2 plots as well as spatial growth model outputs are included. Emissions and general air quality modeling are also discussed.

  14. Atomic resolution imaging of electrode surfaces in solutions containing reversible redox species

    NASA Astrophysics Data System (ADS)

    Heben, Michael J.; Penner, Reginald M.; Lewis, Nathan S.; Dovek, Moris M.; Quate, Calvin F.

    1989-04-01

    Procedures are described for insulating metal scanning tunneling microscope (STM) tips with either glass or polymer coatings. In solutions containing 0.10 M of a reversible redox couple, Fe(CN)-3/-46, the faradaic limiting current to polymer coated tips was 200-500 pA and that for glass coated tips was <10 pA. For polymer insulated tips, steady-state currents of 10-100 pA were observed at tip-sample displacements less than 0.3 μm. The suppression of faradaic current achieved by these coating procedures enabled the collection of the first atomic resolution STM images of highly ordered pyrolytic graphite electrodes in contact with redox-active electrolytes. Preliminary data for the in situ electrochemical characterization of these tips are also discussed.

  15. A Comparison of Statistical Techniques for Combining Modeled and Observed Concentrations to Create High-Resolution Ozone Air Quality Surfaces

    EPA Science Inventory

    Air quality surfaces representing pollutant concentrations across space and time are needed for many applications, including tracking trends and relating air quality to human and ecosystem health. The spatial and temporal characteristics of these surfaces may reveal new informat...

  16. Electroanalysis using macro-, micro-, and nanochemical architectures on electrode surfaces. Bulk surface modification of glassy carbon microspheres with gold nanoparticles and their electrical wiring using carbon nanotubes.

    PubMed

    Dai, Xuan; Wildgoose, Gregory G; Salter, Chris; Crossley, Alison; Compton, Richard G

    2006-09-01

    Gold nanoparticles (approximately 30-60 nm in diameter) were deposited onto the surface of glassy carbon microspheres (10-20 microm) through electroless plating to produce bulk (i.e., gram) quantities of nanoparticle surface-modified microspheres. The gold nanoparticle-modified powder was then characterized by means of scanning electron microscopy and cyclic voltammetry. The voltammetric response of a macroelectrode consisting of a film of gold nanoparticle-modified glassy carbon microspheres, bound together and "wired-up" using multiwalled carbon nanotubes (MWCNTs), was investigated. We demonstrate that by intelligently exploiting both nano- and microchemical architectures and wiring up the electroactive centers using MWCNTs in this way, we can obtain macroelectrode voltammetric behavior while only using approximately 1% by mass of the expensive gold material that would be required to construct the equivalent gold film macrodisk electrode. The potential utility of electrodes constructed using chemical architectures such as this was demonstrated by applying them to the analytical determination of arsenic(III) concentration. An optimized limit of detection of 2.5 ppb was obtained.

  17. Surface-Tuned Co3O4 Nanoparticles Dispersed on Nitrogen-Doped Graphene as an Efficient Cathode Electrocatalyst for Mechanical Rechargeable Zinc-Air Battery Application.

    PubMed

    Singh, Santosh K; Dhavale, Vishal M; Kurungot, Sreekumar

    2015-09-30

    The most vital component of the fuel cells and metal-air batteries is the electrocatalyst, which can facilitate the oxygen reduction reaction (ORR) at a significantly reduced overpotential. The present work deals with the development of surface-tuned cobalt oxide (Co3O4) nanoparticles dispersed on nitrogen-doped graphene as a potential ORR electrocatalyst possessing some unique advantages. The thermally reduced nitrogen-doped graphene (NGr) was decorated with three different morphologies of Co3O4 nanoparticles, viz., cubic, blunt edged cubic, and spherical, by using a simple hydrothermal method. We found that the spherical Co3O4 nanoparticle supported NGr catalyst (Co3O4-SP/NGr-24h) has acquired a significant activity makeover to display the ORR activity closely matching with the state-of-the-art Pt supported carbon (PtC) catalyst in alkaline medium. Subsequently, the Co3O4-SP/NGr-24h catalyst has been utilized as the air electrode in a Zn-air battery, which was found to show comparable performance to the system derived from PtC. Co3O4-SP/NGr-24h catalyst has shown several hours of flat discharge profile at the discharge rates of 10, 20, and 50 mA/cm(2) with a specific capacity and energy density of ~590 mAh/g-Zn and ~840 Wh/kg-Zn, respectively, in the primary Zn-air battery system. In conjunction, Co3O4-SP/NGr-24h has outperformed as an air electrode in mechanical rechargeable Zn-air battery as well, which has shown consistent flat discharge profile with minimal voltage loss at a discharge rate of 50 mA/cm(2). The present results, thus demonstrate that the proper combination of the tuned morphology of Co3O4 with NGr will be a promising and inexpensive material for efficient and ecofriendly cathodes for Zn-air batteries.

  18. Radiotracer Evaluation of the Contribution of Degradation Products of Phenolic Resins to the Poisoning of Electrodes in the 190 C Hydrogen/Air Fuel Cell.

    DTIC Science & Technology

    1980-12-01

    R.F. Pascoe , H.R. Kunz, "Surface Area Loss of Platinum Supported on Carbon in Phosphoric Acid Electrolyte", J. Electrochem. Soc. 127, 1219 (1980). 4...1a. SUPPLEMENTARY NOTES IS. KEY WORDS (Contin he a reverse side It noceasm, mid Identify by block number) Fuel cells, phosphoric acid , bipolar...plates, phenolic resins, composite graphite, Carbon-14, radiotracer, electro-catalyst, electrode poisoning, platinum on carbon catalyst, acid -resistant

  19. Distillation and Air Stripping Designs for the Lunar Surface

    NASA Technical Reports Server (NTRS)

    Boul, Peter J.; Lange, Kevin E.; Conger, Bruce; Anderson, Molly

    2009-01-01

    Air stripping and distillation are two different gravity-based methods, which may be applied to the purification of wastewater on the lunar base. These gravity-based solutions to water processing are robust physical separation techniques, which may be advantageous to many other techniques for their simplicity in design and operation. The two techniques can be used in conjunction with each other to obtain high purity water. The components and feed compositions for modeling waste water streams are presented in conjunction with the Aspen property system for traditional stage distillation models and air stripping models. While the individual components for each of the waste streams will vary naturally within certain bounds, an analog model for waste water processing is suggested based on typical concentration ranges for these components. Target purity levels for the for recycled water are determined for each individual component based on NASA s required maximum contaminant levels for potable water Distillation processes are modeled separately and in tandem with air stripping to demonstrate the potential effectiveness and utility of these methods in recycling wastewater on the Moon. Optimum parameters such as reflux ratio, feed stage location, and processing rates are determined with respect to the power consumption of the process. Multistage distillation is evaluated for components in wastewater to determine the minimum number of stages necessary for each of 65 components in humidity condensate and urine wastewater mixed streams. Components of the wastewater streams are ranked by Henry s Law Constant and the suitability of air stripping in the purification of wastewater in terms of component removal is evaluated. Scaling factors for distillation and air stripping columns are presented to account for the difference in the lunar gravitation environment. Commercially available distillation and air stripping units which are considered suitable for Exploration Life Support

  20. Elucidating the Surface Reactions of an Amorphous Si Thin Film as a Model Electrode for Li-Ion Batteries.

    PubMed

    Ferraresi, Giulio; Czornomaz, Lukas; Villevieille, Claire; Novák, Petr; El Kazzi, Mario

    2016-11-02

    We investigated during the first lithiation/delithiation process the electrochemical reaction mechanisms at the surface of 30 nm n-doped amorphous silicon (a-Si) thin film used as a negative model electrode for Li-ion batteries. Usage of thin film allowed us to accurately discern the different reaction mechanisms occurring at the surface by avoiding interference from carbon and binder components. The potential dependency of the evolution of the solid electrolyte interphase (SEI) and the reactions on the a-Si and on the copper current collector were elucidated by coupling galvanostatic cycling with postmortem X-ray photoemission spectroscopy and scanning electron microscopy analyses. Our approach revealed the clear reversibility of lithiation/delithiation in the a-Si and native SiO2 layers; such a reaction for SiO2 has not been previously detected and was considered to be an irreversible process. Quantitative and qualitative analyses of the potential-dependent surface evolution revealed the decomposition products of both the salt (LiPF6) and solvent (dimethyl carbonate/ethylene carbonate), giving insight into the complex SEI formation mechanism on the a-Si film but also underlining the strong influence of "inert" materials such as the role of the current collector in the irreversible charge loss. A model mechanism describing the evolutionary complexity of the a-Si surface during the first galvanostatic cycle is proposed and discussed.

  1. Estimation of Surface Air Temperature Over Central and Eastern Eurasia from MODIS Land Surface Temperature

    NASA Technical Reports Server (NTRS)

    Shen, Suhung; Leptoukh, Gregory G.

    2011-01-01

    Surface air temperature (T(sub a)) is a critical variable in the energy and water cycle of the Earth.atmosphere system and is a key input element for hydrology and land surface models. This is a preliminary study to evaluate estimation of T(sub a) from satellite remotely sensed land surface temperature (T(sub s)) by using MODIS-Terra data over two Eurasia regions: northern China and fUSSR. High correlations are observed in both regions between station-measured T(sub a) and MODIS T(sub s). The relationships between the maximum T(sub a) and daytime T(sub s) depend significantly on land cover types, but the minimum T(sub a) and nighttime T(sub s) have little dependence on the land cover types. The largest difference between maximum T(sub a) and daytime T(sub s) appears over the barren and sparsely vegetated area during the summer time. Using a linear regression method, the daily maximum T(sub a) were estimated from 1 km resolution MODIS T(sub s) under clear-sky conditions with coefficients calculated based on land cover types, while the minimum T(sub a) were estimated without considering land cover types. The uncertainty, mean absolute error (MAE), of the estimated maximum T(sub a) varies from 2.4 C over closed shrublands to 3.2 C over grasslands, and the MAE of the estimated minimum Ta is about 3.0 C.

  2. 29 CFR 1910.425 - Surface-supplied air diving.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom times of 30 minutes or less may be conducted to depths of 220 fsw. (2) A decompression chamber shall be... fsw. (3) A bell shall be used for dives with an inwater decompression time greater than 120...

  3. 29 CFR 1910.425 - Surface-supplied air diving.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom times of 30 minutes or less may be conducted to depths of 220 fsw. (2) A decompression chamber shall be... fsw. (3) A bell shall be used for dives with an inwater decompression time greater than 120...

  4. 29 CFR 1910.425 - Surface-supplied air diving.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom times of 30 minutes or less may be conducted to depths of 220 fsw. (2) A decompression chamber shall be... fsw. (3) A bell shall be used for dives with an inwater decompression time greater than 120...

  5. 29 CFR 1910.425 - Surface-supplied air diving.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom times of 30 minutes or less may be conducted to depths of 220 fsw. (2) A decompression chamber shall be... fsw. (3) A bell shall be used for dives with an inwater decompression time greater than 120...

  6. 29 CFR 1910.425 - Surface-supplied air diving.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...-supplied air diving shall not be conducted at depths deeper than 190 fsw, except that dives with bottom times of 30 minutes or less may be conducted to depths of 220 fsw. (2) A decompression chamber shall be... fsw. (3) A bell shall be used for dives with an inwater decompression time greater than 120...

  7. Processes of Ammonia Air-Surface Exchange in a Fertilized Zea Mays Canopy

    EPA Science Inventory

    Recent incorporation of coupled soil biogeochemical and bi-directional NH3 air-surface exchange algorithms into regional air quality models holds promise for further reducing uncertainty in estimates of NH3 emissions from fertilized soils. While this advancement represents a sig...

  8. Fact Sheets: Final Rules to Reduce Toxic Air Pollutants from Surface Coating of Metal Cans

    EPA Pesticide Factsheets

    This page contains the August 2003 final rule fact sheet and the December 2005 final rule fact sheet that contain information on the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Surface Coating of Metal Cans.

  9. Surface Coating of Wood Building Products National Emission Standards for Hazardous Air Pollutants (NESHAP) Applicability Flowchart

    EPA Pesticide Factsheets

    This page contains a January 2005 document that has a flow chart to help you determine if this National Emission Standards for Hazardous Air Pollutants (NESHAP) rule for Surface Coating of Wood Building Products applies to your facility.

  10. Analysis and optimization of surface plasmon-enhanced organic solar cells with a metallic crossed grating electrode.

    PubMed

    Lee, Eungkyu; Kim, Changsoon

    2012-09-10

    We perform a systematic analysis of enhanced short-circuit current density (J(sc) in organic solar cells (OSCs) where one metallic electrode is optically thick and the other consists of a two-dimensional metallic crossed grating. By examining a model device representative of such surface plasmon (SP)-enhanced OSCs by the Fourier modal and finite-element methods for electromagnetic and exciton diffusion calculations, respectively, we provide general guidelines to maximize J(sc) of the SP-enhanced OSCs. Based on this study, we optimize the performance of a small-molecule OSC employing a copper phthalocyanine-fullerene donor-acceptor pair, demonstrating that the optimized SP-enhanced device has J(sc) that is 75 % larger than that of the optimized device with an ITO-based conventional structure.

  11. Liquid-Infused Surfaces with Trapped Air (LISTA) for Drag Force Reduction.

    PubMed

    Hemeda, A A; Tafreshi, H Vahedi

    2016-03-29

    Superhydrophobic (SHP) surfaces are known for their drag-reducing attributes thanks to their ability to trap air in their surface pores and thereby reduce the contact between water and the frictional solid area. SHP surfaces are prone to failure under elevated pressures or because of air-layer dissolution into the surrounding water. Slippery liquid-infused porous surfaces (SLIPS) or liquid-infused surfaces (LIS) in which the trapped air is replaced with a lubricant have been proposed in the literature as a way of eliminating the air dissolution problem as well as improving the surface stability under pressure. While an LIS surface has been shown to reduce drag for flow of water-glycerol mixture (ref 18), no significant drag reduction has yet been reported for the flow of water (a lower viscosity fluid) over LIS. In this concern, we have designed a new surface in which a layer of air is trapped underneath the infused lubricant to reduce the frictional forces preventing the LIS to provide drag reduction for water or any fluid with a viscosity less than that of the lubricant. Drag reduction performance of such surfaces, referred to here as liquid-infused surfaces with trapped air (LISTA), is predicted by solving the biharmonic equation for the water-oil-air three-phase system in transverse grooves with enhanced meniscus stability thanks to double-reentry designs. For the arbitrary dimensions considered in our proof-of-concept study, LISTA designs showed 20-37% advantage over their LIS counterparts.

  12. Enhanced quantum efficiency of photoelectron emission, through surface textured metal electrodes

    SciTech Connect

    Alexander, Anna; Bandaru, Prabhakar R.; Moody, Nathan A.

    2016-03-15

    It is predicted that the quantum efficiency (QE) of photoelectron emission from metals may be enhanced, possibly by an order of magnitude, through optimized surface texture. Through extensive computational simulations, it is shown that the absorption enhancement in select surface groove geometries may be a dominant contributor to enhanced QE and corresponds to localized Fabry–Perot resonances. The inadequacy of extant analytical models in predicting the QE increase, and suggestions for further improvement, are discussed.

  13. Validation of AIRS V6 Surface Temperature over Greenland with GCN and NOAA Stations

    NASA Technical Reports Server (NTRS)

    Lee, Jae N.; Hearty, Thomas; Cullather, Richard; Nowicki, Sophie; Susskind, Joel

    2016-01-01

    This work compares the temporal and spatial characteristics of the AIRSAMSU (Atmospheric Infrared Sounder Advanced Microwave Sounding Unit A) Version 6 and MODIS (Moderate resolution Imaging Spectroradiometer) Collection 5 derived surface temperatures over Greenland. To estimate uncertainties in space-based surface temperature measurements, we re-projected the MODIS Ice Surface Temperature (IST) to 0.5 by 0.5 degree spatial resolution. We also re-gridded AIRS Skin Temperature (Ts) into the same grid but classified with different cloud conditions and surface types. These co-located data sets make intercomparison between the two instruments relatively straightforward. Using this approach, the spatial comparison between the monthly mean AIRS Ts and MODIS IST is in good agreement with RMS 2K for May 2012. This approach also allows the detection of any long-term calibration drift and the careful examination of calibration consistency in the MODIS and AIRS temperature data record. The temporal correlations between temperature data are also compared with those from in-situ measurements from GC-Net (GCN) and NOAA stations. The coherent time series of surface temperature evident in the correlation between AIRS Ts and GCN temperatures suggest that at monthly time scales both observations capture the same climate signal over Greenland. It is also suggested that AIRS surface air temperature (Ta) can be used to estimate the boundary layer inversion.

  14. Multi-pollutant surface objective analyses and mapping of air quality health index over North America.

    PubMed

    Robichaud, Alain; Ménard, Richard; Zaïtseva, Yulia; Anselmo, David

    2016-01-01

    Air quality, like weather, can affect everyone, but responses differ depending on the sensitivity and health condition of a given individual. To help protect exposed populations, many countries have put in place real-time air quality nowcasting and forecasting capabilities. We present in this paper an optimal combination of air quality measurements and model outputs and show that it leads to significant improvements in the spatial representativeness of air quality. The product is referred to as multi-pollutant surface objective analyses (MPSOAs). Moreover, based on MPSOA, a geographical mapping of the Canadian Air Quality Health Index (AQHI) is also presented which provides users (policy makers, public, air quality forecasters, and epidemiologists) with a more accurate picture of the health risk anytime and anywhere in Canada and the USA. Since pollutants can also behave as passive atmospheric tracers, they provide information about transport and dispersion and, hence, reveal synoptic and regional meteorological phenomena. MPSOA could also be used to build air pollution climatology, compute local and national trends in air quality, and detect systematic biases in numerical air quality (AQ) models. Finally, initializing AQ models at regular time intervals with MPSOA can produce more accurate air quality forecasts. It is for these reasons that the Canadian Meteorological Centre (CMC) in collaboration with the Air Quality Research Division (AQRD) of Environment Canada has recently implemented MPSOA in their daily operations.

  15. Adsorption of polystyrene sulfonate to the air surface of water by neutron reflectivity

    SciTech Connect

    YIM,HYUN; KENT,MICHAEL S.; MATHESON,AARON J.; IVKOV,R.; SATIJA,S.; MAJEWSKI,J.; SMITH,G.S.

    2000-05-16

    The adsorption of the strong polyelectrolyte polystyrene sulfonate (PSS) to the air surface of dilute aqueous solutions was investigated as a function of molecular weight and salt concentration. Detailed segment profiles of the deuterated polymer were determined by neutron reflection. Surface activity was also examined through surface tension measurements. In general, the segment profiles are composed of a thin layer (10--20 {angstrom} thick) of high concentration at the air surface, followed by a distinct second layer of much lower segment concentration that extends to larger depths into the liquid. The high segment density at the air surface is due to a strong surface attraction, arising from the low surface tension of the PSS backbone relative to the surface tension of water. At low salt concentration, the profiles tend toward a single dense layer, suggesting that the chains lie nearly flat at the interface in that limit. The adsorbed amount increases with salt concentration, with a stronger dependence for higher molecular weight chains. The adsorbed amounts at the air/water interface are higher than reported previously for PSS adsorbed onto neutral solid surfaces, consistent with the fact that the air-liquid interface provides a stronger surface attraction. While the trends of adsorbed amount and layer thickness with salt concentration and molecular weight are in good agreement with numerical self-consistent field lattice calculations, the measured bilayer profiles are rather different from the smoothly decaying theoretical profiles. The surface tensions of the PSS solutions are significantly lowered relative to those of pure salt solutions. Combining the reflectivity and surface tension measurements, an approximately linear relationship is established between the surface pressure and the PSS adsorbed amount.

  16. Comparison of MODIS Land Surface Temperature and Air Temperature over the Continental USA Meteorological Stations

    NASA Technical Reports Server (NTRS)

    Zhang, Ping; Bounoua, Lahouari; Imhoff, Marc L.; Wolfe, Robert E.; Thome, Kurtis

    2014-01-01

    The National Land Cover Database (NLCD) Impervious Surface Area (ISA) and MODIS Land Surface Temperature (LST) are used in a spatial analysis to assess the surface-temperature-based urban heat island's (UHIS) signature on LST amplitude over the continental USA and to make comparisons to local air temperatures. Air-temperature-based UHIs (UHIA), calculated using the Global Historical Climatology Network (GHCN) daily air temperatures, are compared with UHIS for urban areas in different biomes during different seasons. NLCD ISA is used to define urban and rural temperatures and to stratify the sampling for LST and air temperatures. We find that the MODIS LST agrees well with observed air temperature during the nighttime, but tends to overestimate it during the daytime, especially during summer and in nonforested areas. The minimum air temperature analyses show that UHIs in forests have an average UHIA of 1 C during the summer. The UHIS, calculated from nighttime LST, has similar magnitude of 1-2 C. By contrast, the LSTs show a midday summer UHIS of 3-4 C for cities in forests, whereas the average summer UHIA calculated from maximum air temperature is close to 0 C. In addition, the LSTs and air temperatures difference between 2006 and 2011 are in agreement, albeit with different magnitude.

  17. Elasticity of the hair cover in air-retaining Salvinia surfaces

    NASA Astrophysics Data System (ADS)

    Ditsche, Petra; Gorb, Elena; Mayser, Matthias; Gorb, Stanislav; Schimmel, Thomas; Barthlott, Wilhelm

    2015-11-01

    Immersed in water superhydrophobic surfaces (e.g., lotus) maintain thin temporary air films. In certain aquatic plants and animals, these films are thicker and more persistent. Floating ferns of the genus Salvinia show elaborated hierarchical superhydrophobic surface structures: a hairy cover of complex trichomes. In the case of S. molesta, they are eggbeater shaped and topped by hydrophilic tips, which pin the air-water interface and prevent rupture of contact. It has been proposed that these trichomes can oscillate with the air-water interface, when turbulences occur and thereby stabilize the air film. The deformability of such arrays of trichomes requires a certain elasticity of the structures. In this study, we determined the stiffness of the trichome coverage of S. molesta and three other Salvinia species. Our results confirm the elasticity of the trichome coverage in all investigated Salvinia species. We did not reveal a clear relationship between the time of air retention and stiffness of the trichome coverage, which means that the air retention function is additionally dependent on different parameters, e.g., the trichome shape and surface free energy. These data are not only interesting for Salvinia biology, but also important for the development of biomimetic air-retaining surfaces.

  18. Enhancing Electrochemical Water-Splitting Kinetics by Polarization-Driven Formation of Near-Surface Iron(0): An In Situ XPS Study on Perovskite-Type Electrodes**

    PubMed Central

    Opitz, Alexander K; Nenning, Andreas; Rameshan, Christoph; Rameshan, Raffael; Blume, Raoul; Hävecker, Michael; Knop-Gericke, Axel; Rupprechter, Günther; Fleig, Jürgen; Klötzer, Bernhard

    2015-01-01

    In the search for optimized cathode materials for high-temperature electrolysis, mixed conducting oxides are highly promising candidates. This study deals with fundamentally novel insights into the relation between surface chemistry and electrocatalytic activity of lanthanum ferrite based electrolysis cathodes. For this means, near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and impedance spectroscopy experiments were performed simultaneously on electrochemically polarized La0.6Sr0.4FeO3−δ (LSF) thin film electrodes. Under cathodic polarization the formation of Fe0 on the LSF surface could be observed, which was accompanied by a strong improvement of the electrochemical water splitting activity of the electrodes. This correlation suggests a fundamentally different water splitting mechanism in presence of the metallic iron species and may open novel paths in the search for electrodes with increased water splitting activity. PMID:25557533

  19. Wiring of the aldehyde oxidoreductase PaoABC to electrode surfaces via entrapment in low potential phenothiazine-modified redox polymers.

    PubMed

    Pinyou, Piyanut; Ruff, Adrian; Pöller, Sascha; Alsaoub, Sabine; Leimkühler, Silke; Wollenberger, Ulla; Schuhmann, Wolfgang

    2016-06-01

    Phenothiazine-modified redox hydrogels were synthesized and used for the wiring of the aldehyde oxidoreductase PaoABC to electrode surfaces. The effects of the pH value and electrode surface modification on the biocatalytic activity of the layers were studied in the presence of vanillin as the substrate. The enzyme electrodes were successfully employed as bioanodes in vanillin/O2 biofuel cells in combination with a high potential bilirubin oxidase biocathode. Open circuit voltages of around 700 mV could be obtained in a two compartment biofuel cell setup. Moreover, the use of a rather hydrophobic polymer with a high degree of crosslinking sites ensures the formation of stable polymer/enzyme films which were successfully used as bioanode in membrane-less biofuel cells.

  20. Ratio of the surface-enhanced anti-Stokes scattering to the surface-enhanced Stokes-Raman scattering for molecules adsorbed on a silver electrode

    NASA Astrophysics Data System (ADS)

    Brolo, A. G.; Sanderson, A. C.; Smith, A. P.

    2004-01-01

    Surface-enhanced Raman scattering (SERS) from oxazine 720 (oxa), rhodamine 6G (R6G), and pyridine (py) adsorbed on a rough silver surface was observed. The silver electrode was immersed in aqueous solutions permitting control of the potential bias applied to the surface. SERS spectra in the Stokes and anti-Stokes regions were obtained for several applied potentials and two laser excitation energies. Normalized ratios between the anti-Stokes and the Stokes intensities K were calculated from the SERS spectra. The K ratios differed from unity for all the systems investigated. A preferential enhancement of the (surface-enhanced) Stokes scattering was observed for oxa and py. In contrast, the K ratios were higher than unity for R6G, indicating an increase in the anti-Stokes signal. The K ratios measured in this work decreased with the excitation energy and showed a dependence on the energy of the vibrational modes. These results were satisfactorily explained using resonance models, based on the charge-transfer and electromagnetic theories for SERS. No evidence for a SERS-induced nonthermal population distribution among the vibrational states of the adsorbed molecules (vibrational optical pumping) was found. Therefore, we conclude that the main features of the preferential enhancement of the anti-Stokes scattering for an adsorbed molecule on rough silver can be fully understood in the context of current SERS theories.

  1. Microchip device with 64-site electrode array for multiplexed immunoassay of cell surface antigens based on electrochemiluminescence resonance energy transfer.

    PubMed

    Wu, Mei-Sheng; Shi, Hai-Wei; He, Li-Jing; Xu, Jing-Juan; Chen, Hong-Yuan

    2012-05-01

    This paper describes a novel on-chip microarray platform based on an electrochemiluminescence resonance energy transfer (ECL-RET) strategy for rapid assay of cancer cell surface biomarkers. This platform consists of 64 antigen-decorated CdS nanorod spots with the diameter of 1.0 cm uniformly distributed on 16 indium tin oxide (ITO) strips, which is coated with a multichannel decorated polydimethylsiloxane (PDMS) slice to realize multiplexed determination of antigens. To shorten the immune reaction time in the microchannels and simplify the device, magnetic stirring and four-channel universal serial bus (USB) ports for plug-and-play were used. When Ru(bpy)(3)(2+) labeled antibodies were selectively captured by the corresponding antigens on the CdS nanorod spot array, ECL-RET from the CdS nanorod (donor) by cathodic emission in the presence of K(2)S(2)O(8) to Ru(bpy)(3)(2+) (acceptor) occurred. With signal amplification of Ru(bpy)(3)(2+) and competitive immunoassay, carcinoembryonic antigen (CEA), α-fetoprotein (AFP), and prostate specific antigen (PSA) as models were detected on this microfluidic device via recording the increased ECL-RET signals on electrode surfaces. Furthermore, this multiplexed competitive immunoassay was successfully used for detecting cancer cell surface antigens via the specific antibody-cell interactions and cell counting via cell surface receptors and antigens on the CdS nanorod surface. This platform provides a rapid and simple but sensitive approach with microliter-level sample volume and holds great promise for multiplexed detection of antigens and antigen-specific cells.

  2. Metal monolayer deposition by replacement of metal adlayers on electrode surfaces

    NASA Astrophysics Data System (ADS)

    Brankovic, S. R.; Wang, J. X.; Adžić, R. R.

    2001-03-01

    A new metal deposition method is demonstrated by deposition of a submonolayer of Pt, a monolayer of Pd and a bilayer of Ag on Au(1 1 1) surfaces by using a Cu adlayer as a template. The deposition of these metals occurs as a spontaneous irreversible redox process in which a Cu adlayer, obtained by underpotential deposition, is oxidized by more noble metal cations, which are reduced and simultaneously deposited. The Pt deposit is a two-dimensional submonolayer consisting of partially interconnected nano-clusters of monoatomic height. Pd forms a uniform, but textured monolayer, while Ag forms a bilayer. The deposit of each metal uniformly covers the entire gold surface without preferential deposition along the step edges. This method provides surface adlayer-controlled growth, as compared to the current distribution controlled growth in conventional electrodeposition.

  3. Oil lenses on the air-water surface and the validity of Neumann's rule.

    PubMed

    Nikolov, Alex; Wasan, Darsh

    2016-05-10

    Many studies have focused on the mechanisms of oil spreading over the air-water surface, oil lens formation, and lens dynamics: Franklin et al.(1774), Rayleigh (1890), Neumann and Wangerin (1894), Hardy (1912), Lyons (1930), Langmuir (1933), Miller (1941), Zisman (1941), Pujado and Scriven (1972), Seeto et al. (1983), and Takamura et al. (2012). Despite all of these studies, the phenomenon of the oil lens's air-water surface equilibrium is still under discussion. Here, we highlight an accurate method to study the oil lens's three-phase-contact angle by reflected light interferometry, using both common (CRLI) and differential reflected light interferometry (DRLI) to verify Neumann's rule (the vectorial sum of the three tensions is zero). For non-spreading oils, the validity of Neumann's rule is confirmed for small lenses when the role of the oil film tension around the lens's meniscus is taken into consideration. Neumann's rule was also validated when the monolayer surface pressure isotherm was taken into consideration for oil spreading on the air-water surface. The periodic monolayer surface pressure oscillation of the oil phase monolayer created by the air-evaporating biphilic oil was monitored with time. The monolayer's surface pressure periodic oscillation was attributed to the instability of the aqueous film covering the oil drop phase. The knowledge gained from this study will benefit the fundamental understanding of the oil lens's air-water surface equilibrium and oil spill mechanisms, thereby promoting better methods for the prevention and clean-up of oil spills.

  4. Enhanced Lithium-Ion Intercalation Properties of V[subscript 2]O[subscript 5] Xerogel Electrodes with Surface Defects

    SciTech Connect

    Liu, Dawei; Liu, Yanyi; Pan, Anquiang; Nagle, Kenneth P.; Seidler, Gerald T.; Jeong, Yoon-Ha; Cao, Guozhong

    2011-09-15

    V{sub 2}O{sub 5} xerogel films were fabricated by casting V{sub 2}O{sub 5} sols onto fluorine-doped tin oxide (FTO) glass substrates and annealing at 300 C for 3 h in different annealing atmospheres of air and nitrogen. Films prepared in different annealing conditions possess different grain sizes and crystallinity, while the vanadium ion oxidation state also varies, as identified by X-ray absorption spectroscopy. A nitrogen annealing atmosphere induces the presence of defects, such as V{sup 4+} ions, and associated oxygen vacancies. Thus, the presence of defects, whether on the film surface or in the bulk, can be controlled by using air and nitrogen annealing atmospheres in the proper order. Electrochemical impedance analyses reveal enhanced charge-transfer conductivity in films with more V{sup 4+} and oxygen vacancies on the film surface, that is, a film annealed, first, for 0.5 h in air and then for 2.5 h in nitrogen. Lithium-ion intercalation measurements show that, at a charge/discharge current density of 600 mA g{sup -1}, this film possesses a noticeably better lithium-ion storage capability than films without surface defects. This sample starts with an initial discharge capacity of 139 mA h g{sup -1}, and the capacity increases slowly to a maximum value of 156 mA h g{sup -1} in the 15th cycle, followed by a mild capacity degradation in later cycles. After 50 cycles, the discharge capacity is still as high as 136 mA h g{sup -1}. A much improved lithium-ion intercalation capacity and cyclic stability are attributed to V{sup 4+} surface defects and associated oxygen vacancies introduced by N{sub 2} annealing.

  5. Intervalence transfer of ferrocene moieties adsorbed on electrode surfaces by a conjugated linkage

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Brown, Lauren E.; Konopelski, Joseph P.; Chen, Shaowei

    2009-03-01

    Effective intervalence transfer occurred between the metal centers of ferrocene moieties that were adsorbed onto a ruthenium thin film surface by ruthenium-carbene π bonds, a direct verification of Hush's four-decade-old prediction. Electrochemical measurements showed two pairs of voltammetric peaks where the separation of the formal potentials suggested a Class II behavior. Additionally, the potential spacing increased with increasing ferrocene surface coverage, most probably as a consequence of the enhanced contribution from through-space electronic interactions between the metal centers. In contrast, the incorporation of a sp 3 carbon spacer into the ferrocene-ruthenium linkage led to the diminishment of interfacial electronic communication.

  6. Assembly of selective biomimetic surface on an electrode surface: a design of nano-bio interface for biosensing.

    PubMed

    Gao, Tao; Liu, Fengzhen; Yang, Dawei; Yu, Yue; Wang, Zhaoxia; Li, Genxi

    2015-06-02

    In nature, cellular molecule sensing is usually achieved at the environment/membrane interface. In the meantime, rapid growth of nanotechnology is increasingly pushing engineered nanomaterials to interact with biological surfaces. Herein, inspired by trans-membrane signal transduction, a nano-bio interface has been constructed in this work for biosensing application. The interface is formed between a selective biomembrane mimetic surface (SBMMS) and a function-oriented 2D nanohybrid. Based on the design, target recognition can be performed in a biologically favorable environment, and the nano-bio interaction can be transduced into amplified electrochemical readouts. Furthermore, this sensing platform can be used to analyze various kinds of targets, including proteins, nucleic acids, and small molecules, just by changing the biorecognition element. Low detection limits and wide detection ranges can also be obtained. So, this nano-bio interface may provide a new platform for bioanalytical research in the future.

  7. Failure mechanisms of air entrainment in drop impact on lubricated surfaces.

    PubMed

    Pack, M; Hu, H; Kim, D; Zheng, Z; Stone, H A; Sun, Y

    2017-03-22

    Lubricated surfaces have recently been introduced and studied due to their potential benefit in various configurations and applications. Combining the techniques of total internal reflection microscopy and reflection interference microscopy, we examine the dynamics of an underlying air film upon drop impact on a lubricated substrate where the thin liquid film is immiscible to the drop. In contrast to drop impact on solid surfaces where even the smallest asperities cause random breakup of the entraining air film, we report two air film failure mechanisms on lubricated surfaces. In particular, using ≈5 μm thick liquid films of high viscosity, which should make the substrate nearly atomically smooth, we show that air film rupture shifts from asperity-driven to a controlled event. At low Weber numbers (We < 2, We = ρlU0(2)R/σ, U0 the impact velocity, R the drop radius, and ρl the density and σ the surface tension of the droplet) the droplet bounces. At intermediate We (2 < We < 10), the air film fails at the center as the top surface of the drop crashes downward owing to impact-induced capillary waves; the resulting liquid-liquid contact time is found to be independent of We. In contrast, at high We (We > 10), the air film failure occurs much earlier in time at the first inflection point of the air film shape away from the drop center, where the liquid-liquid van der Waals interactions become important. The predictable failure modes of the air film upon drop impact sheds light on droplet deposition in applications such as lubricant-infused self-cleaning surfaces.

  8. Moisture content, processing yield, and surface color of broiler carcasses chilled by water, air, or evaporative air.

    PubMed

    Jeong, J Y; Janardhanan, K K; Booren, A M; Karcher, D M; Kang, I

    2011-03-01

    This study was conducted to investigate the effects of water chilling (WC), air chilling (AC), and evaporative air chilling (EAC) on the moisture content, processing yield, surface color, and visual appearance of broiler carcasses. For the WC treatment, 1 group of birds was hard scalded and submersed into ice slush, whereas for AC, 1 group of birds was soft scalded and exposed to blowing air (1.0 m/s at 0°C) and for EAC, or 1 group of birds was soft scalded and exposed to blowing air and a cold water spray (every 5 min). During chilling, carcass temperature was reduced most effectively by WC (55 min), followed by EAC (120 min) and AC (155 min). After chilling, both WC and EAC carcasses picked up moisture at 4.6 and 1.0% of their weights, respectively, whereas AC carcasses lost 1.5% of their weight. On cutting at 5 h postmortem, WC carcasses showed the highest (2.5%), EAC showed the second highest (0.4%), and AC showed the least (0.3%) moisture loss. After 24 h of storage, almost 83% of the absorbed water in the WC carcass parts was released as purge, whereas EAC and AC carcasses maintained weights close to the prechilled weights. In an instrumental color evaluation and a visual evaluation by panelists, AC carcasses showed a darker appearance, a more yellow color, and more surface discoloration compared with WC or EAC carcasses.

  9. Bridging Oriented Copper Nanowire-Graphene Composites for Solution-Processable, Annealing-Free, and Air-Stable Flexible Electrodes.

    PubMed

    Zhang, Wang; Yin, Zhenxing; Chun, Alvin; Yoo, Jeeyoung; Kim, Youn Sang; Piao, Yuanzhe

    2016-01-27

    One-dimensional flexible metallic nanowires (NWs) are of considerable interest for next-generation wearable devices. The unavoidable challenge for a wearable electrode is the assurance of high conductivity, flexibility, and durability with economically feasible materials and simple manufacturing processes. Here, we use a straightforward solvothermal method to prepare a flexible conductive material that contains reduced graphene oxide (RGO) nanosheets bridging oriented copper NWs. The GO-assistance route can successfully meet the criteria listed above and help the composite films maintain high conductivity and durable flexibility without any extra treatment, such as annealing or acid processes. The composite film exhibits a high electrical performance (0.808 Ω·sq(-1)) without considerable change over 30 days under ambient conditions. Moreover, the Cu NW-RGO composites can be deposited on polyester cloth as a lightweight wearable electrode with high durability and simple processability and are very promising for a wide variety of electronic devices.

  10. Immobilization of superoxide dismutase on Pt-Pd/MWCNTs hybrid modified electrode surface for superoxide anion detection.

    PubMed

    Zhu, Xiang; Niu, Xiangheng; Zhao, Hongli; Tang, Jie; Lan, Minbo

    2015-05-15

    Monitoring of reactive oxygen species like superoxide anion (O2(∙-)) turns to be of increasing significance considering their potential damages to organism. In the present work, we fabricated a novel O2(∙-) electrochemical sensor through immobilizing superoxide dismutase (SOD) onto a Pt-Pd/MWCNTs hybrid modified electrode surface. The Pt-Pd/MWCNTs hybrid was synthesized via a facile one-step alcohol-reduction process, and well characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The immobilization of SOD was accomplished using a simple drop-casting method, and the performance of the assembled enzyme-based sensor for O2(∙-) detection was systematically investigated by several electrochemcial techniques. Thanks to the specific biocatalysis of SOD towards O2(∙-) and the Pt-Pd/MWCNTs - promoted fast electron transfer at the fabricated interface, the developed biosensor exhibits a fast, selective and linear amperometric response upon O2(∙-) in the concentration scope of 40-1550 μM (R(2)=0.9941), with a sensitivity of 0.601 mA cm(-2) mM(-1) and a detection limit of 0.71 μM (S/N=3). In addition, the favorable biocompatibility of this electrode interface endows the prepared biosensor with excellent long-term stability (a sensitivity loss of only 3% over a period of 30 days). It is promising that the proposed sensor will be utilized as an effective tool to quantitatively monitor the dynamic changes of O2(∙-) in biological systems.

  11. Surface charge accumulation of particles containing radionuclides in open air.

    PubMed

    Kim, Yong-ha; Yiacoumi, Sotira; Tsouris, Costas

    2015-05-01

    Radioactivity can induce charge accumulation on radioactive particles. However, electrostatic interactions caused by radioactivity are typically neglected in transport modeling of radioactive plumes because it is assumed that ionizing radiation leads to charge neutralization. The assumption that electrostatic interactions caused by radioactivity are negligible is evaluated here by examining charge accumulation and neutralization on particles containing radionuclides in open air. A charge-balance model is employed to predict charge accumulation on radioactive particles. It is shown that particles containing short-lived radionuclides can be charged with multiple elementary charges through radioactive decay. The presence of radioactive particles can significantly modify the particle charge distribution in open air and yield an asymmetric bimodal charge distribution, suggesting that strong electrostatic particle interactions may occur during short- and long-range transport of radioactive particles. Possible effects of transported radioactive particles on electrical properties of the local atmosphere are reported. The study offers insight into transport characteristics of airborne radionuclides. Results are useful in atmospheric transport modeling of radioactive plumes.

  12. Surface charge accumulation of particles containing radionuclides in open air

    SciTech Connect

    Kim, Yong-ha; Yiacoumi, Sotira; Tsouris, Costas

    2015-05-01

    Radioactivity can induce charge accumulation on radioactive particles. But, electrostatic interactions caused by radioactivity are typically neglected in transport modeling of radioactive plumes because it is assumed that ionizing radiation leads to charge neutralization. The assumption that electrostatic interactions caused by radioactivity are negligible is evaluated here by examining charge accumulation and neutralization on particles containing radionuclides in open air. Moreover, a charge-balance model is employed to predict charge accumulation on radioactive particles. It is shown that particles containing short-lived radionuclides can be charged with multiple elementary charges through radioactive decay. The presence of radioactive particles can significantly modify the particle charge distribution in open air and yield an asymmetric bimodal charge distribution, suggesting that strong electrostatic particle interactions may occur during short- and long-range transport of radioactive particles. Possible effects of transported radioactive particles on electrical properties of the local atmosphere are reported. Our study offers insight into transport characteristics of airborne radionuclides. Results are useful in atmospheric transport modeling of radioactive plumes.

  13. Surface charge accumulation of particles containing radionuclides in open air

    DOE PAGES

    Kim, Yong-ha; Yiacoumi, Sotira; Tsouris, Costas

    2015-05-01

    Radioactivity can induce charge accumulation on radioactive particles. But, electrostatic interactions caused by radioactivity are typically neglected in transport modeling of radioactive plumes because it is assumed that ionizing radiation leads to charge neutralization. The assumption that electrostatic interactions caused by radioactivity are negligible is evaluated here by examining charge accumulation and neutralization on particles containing radionuclides in open air. Moreover, a charge-balance model is employed to predict charge accumulation on radioactive particles. It is shown that particles containing short-lived radionuclides can be charged with multiple elementary charges through radioactive decay. The presence of radioactive particles can significantly modify themore » particle charge distribution in open air and yield an asymmetric bimodal charge distribution, suggesting that strong electrostatic particle interactions may occur during short- and long-range transport of radioactive particles. Possible effects of transported radioactive particles on electrical properties of the local atmosphere are reported. Our study offers insight into transport characteristics of airborne radionuclides. Results are useful in atmospheric transport modeling of radioactive plumes.« less

  14. Structure and surface chemistry of Al2O3 coated LiMn2O4 nanostructured electrodes with improved lifetime

    NASA Astrophysics Data System (ADS)

    Waller, G. H.; Brooke, P. D.; Rainwater, B. H.; Lai, S. Y.; Hu, R.; Ding, Y.; Alamgir, F. M.; Sandhage, K. H.; Liu, M. L.

    2016-02-01

    Aluminum oxide coatings deposited on LiMn2O4/carbon fiber electrodes by atomic layer deposition (ALD) are shown to enhance cathode performance in lithium-ion batteries. With a thin Al2O3 coating derived from 10 ALD cycles, the electrodes exhibit 2.5 times greater capacity retention over 500 cycles at a rate of 1C as well as enhanced rate capability and decreased polarization resistance. Structural and surface studies of the electrodes before and after cycling reveal that a near-surface phenomenon is responsible for the improved electrochemical performance. The crystal structure and overall morphology of the LiMn2O4 electrode are found to be unaffected by electrochemical cycling, both for coated and uncoated samples. However, evidence of Mn diffusion into the ALD coatings is observed from both transmission electron microscopy/energy-dispersive X-ray spectroscopy (TEM-EDS) and X-ray Photoelectron Spectroscopy (XPS) after electrochemical cycling. Furthermore, XPS analysis of the Al 2p photoemission peak for the ALD coated electrodes reveal a significant shift in binding energy and peak shape, suggesting the presence of an Al-O-F compound formed by sequestering HF in the electrolyte. These observations provide new insight toward understanding the mechanism in which ultrathin coatings of amphoteric oxides can inhibit capacity loss for LiMn2O4 cathodes in lithium-ion batteries.

  15. Drag reductions and the air-water interface stability of superhydrophobic surfaces in rectangular channel flow

    NASA Astrophysics Data System (ADS)

    Zhang, Jingxian; Yao, Zhaohui; Hao, Pengfei

    2016-11-01

    Flow in a rectangular channel with superhydrophobic (SH) top and bottom walls was investigated experimentally. Different SH surfaces, including hierarchical structured surfaces and surfaces with different micropost sizes (width and spacing) but the same solid fraction, were fabricated and measured. Pressure loss and flow rate in the channel with SH top and bottom walls were measured, with Reynolds number changing from 700 to 4700, and the corresponding friction factor for the SH surface was calculated. The statuses of the air plastron on different SH surfaces were observed during the experiment. In our experiment, compared with the experiment for the smooth surface, drag reductions were observed for all SH surfaces, with the largest drag reduction of 42.2%. It was found that the hierarchy of the microstructure can increase the drag reduction by decreasing the solid fraction and enhancing the stability of the air-water interface. With a fixed solid fraction, the drag reduction decreases as the post size (width and spacing) increases, due to the increasing curvature and instability effects of the air-water interface. A correlation parameter between the contact angle hysteresis, the air-water interface stability, and the drag reduction of the SH surfaces was found.

  16. Drag reductions and the air-water interface stability of superhydrophobic surfaces in rectangular channel flow.

    PubMed

    Zhang, Jingxian; Yao, Zhaohui; Hao, Pengfei

    2016-11-01

    Flow in a rectangular channel with superhydrophobic (SH) top and bottom walls was investigated experimentally. Different SH surfaces, including hierarchical structured surfaces and surfaces with different micropost sizes (width and spacing) but the same solid fraction, were fabricated and measured. Pressure loss and flow rate in the channel with SH top and bottom walls were measured, with Reynolds number changing from 700 to 4700, and the corresponding friction factor for the SH surface was calculated. The statuses of the air plastron on different SH surfaces were observed during the experiment. In our experiment, compared with the experiment for the smooth surface, drag reductions were observed for all SH surfaces, with the largest drag reduction of 42.2%. It was found that the hierarchy of the microstructure can increase the drag reduction by decreasing the solid fraction and enhancing the stability of the air-water interface. With a fixed solid fraction, the drag reduction decreases as the post size (width and spacing) increases, due to the increasing curvature and instability effects of the air-water interface. A correlation parameter between the contact angle hysteresis, the air-water interface stability, and the drag reduction of the SH surfaces was found.

  17. The Potential Dependence of Surface Plasmon-Enhanced Second Harmonic Generation at Thin Film Silver Electrodes.

    DTIC Science & Technology

    1983-11-01

    Phy. Rev. B8, 3797 (1981). 11. R. T. Deck and D . Sarid , J. Opt. Soc. Am. 72, 1603 (1982). 12. R. K Corn and M. R. Philpott, "Surface Plasmon-Enhanced...Elctroes . PERFORMING ORG. REPORT NUMBER 7. AUTHOR(*) 11. CONTRACT OR GRANT NUNSERfs) cl Robert M. Corn, Marco Romagnoli, Marc D . Levenson and Michael R...M. Corn Marco Romagnoli Marc D . Levenson Michael R. Philpott Submitted to Chemical Plwysics Leiters IBM Research Laboratory, K33/291 5600 Cottle Road

  18. Igniter electrode life control

    SciTech Connect

    Scott, J.C.

    1985-10-07

    The prevention of electrode material erosion by undercutting in the outer electrode shell of igniter electrodes of jet engine ignition systems is prevented by the application of an electrical insulation coating. The coating is applied to the surface of the outer electrode shell which faces the ceramic insulation around the center electrode where erosion patterns are known to occur. The insulation material is selected from electrical insulation substances such as oxides of aluminum, tungsten, magnesium, beryllium or zirconium by choosing a non-porous electrical-insulating substance with thermal-expansion characteristics approximately equalling those of the outer electrode shell. Since a typical outer electrode shell is composed of 446 stainless steel, an optimum choice for the electrical insulation coating is Al/sub 2/O/sub 3/ deposited with a coating thickness of between 5 and 10 mils.

  19. Experimental Approach to Controllably Vary Protein Oxidation While Minimizing Electrode Adsorption for Boron-Doped Diamond Electrochemical Surface Mapping Applications

    SciTech Connect

    McClintock, Carlee; Hettich, Robert {Bob} L

    2013-01-01

    Oxidative protein surface mapping has become a powerful approach for measuring the solvent accessibility of folded protein structures. A variety of techniques exist for generating the key reagent hydroxyl radicals for these measurements; however, many of these approaches require use of radioactive sources or caustic oxidizing chemicals. The purpose of this research was to evaluate and optimize the use of boron-doped diamond (BDD) electrochemistry as a highly accessible tool for producing hydroxyl radicals as a means to induce a controllable level of oxidation on a range of intact proteins. These experiments utilize a relatively high flow rates to reduce protein residence time inside the electrochemical flow chamber, along with a unique cell activation approach to improve control over the intact protein oxidation yield. Studies were conducted to evaluate the level of protein adsorption onto the electrode surface. This report demonstrates a robust protocol for the use of BDD electrochemistry and high performance LC-MS/MS as a high-throughput experimental pipeline for probing higher order protein structure, and illustrates how it is complementary to predictive computational modeling efforts.

  20. Magnetic control of electrochemical processes at electrode surface using iron-rich graphene materials with dual functionality.

    PubMed

    Lim, Chee Shan; Ambrosi, Adriano; Sofer, Zdeněk; Pumera, Martin

    2014-07-07

    Metal-doped graphene hybrid materials demonstrate promising capabilities in catalysis and various sensing applications. There also exists great interest for on-demand control of the selectivity of many electrochemical processes. In this work, an iron-doped thermally reduced graphene oxide (Fe-TRGO) was prepared and used to investigate the possibility of a reproducible, magnetically controlled method to modulate electrochemical reactivities through a scalable method. We made use of the presence of both magnetic and electrocatalytic properties in the Fe-TRGOs to induce attraction and removal of the Fe-TRGO material onto and off the working electrode surfaces magnetically, thereby controlling the electrochemical oxidation and reduction processes. The outstanding electrochemical performance of the Fe-TRGO material was evident, with enhanced current signals and lower peak potentials observed upon magnetic activation. Reversible and reproducible cycles of activation and deactivation were obtained as the peak heights and peak potentials remained relatively consistent with no apparent carryover between every step. Both components of Fe-TRGO play an electrocatalytic role in the electrochemical sensing. In the cases of the oxygen reduction reaction and reduction of cumene hydroperoxide, the iron oxide plays the role of an electrocatalyst, while in the cases of ascorbic acid, the enhanced electroactivity originates from the high surface area of the graphene portion in the Fe-TRGO hybrid material. The feasibility of this magnetically switchable method for on-demand sensing and energy production thus brings about potential developments for future electrochemical applications.

  1. Magnetic control of electrochemical processes at electrode surface using iron-rich graphene materials with dual functionality

    NASA Astrophysics Data System (ADS)

    Lim, Chee Shan; Ambrosi, Adriano; Sofer, Zdeněk; Pumera, Martin

    2014-06-01

    Metal-doped graphene hybrid materials demonstrate promising capabilities in catalysis and various sensing applications. There also exists great interest for on-demand control of the selectivity of many electrochemical processes. In this work, an iron-doped thermally reduced graphene oxide (Fe-TRGO) was prepared and used to investigate the possibility of a reproducible, magnetically controlled method to modulate electrochemical reactivities through a scalable method. We made use of the presence of both magnetic and electrocatalytic properties in the Fe-TRGOs to induce attraction and removal of the Fe-TRGO material onto and off the working electrode surfaces magnetically, thereby controlling the electrochemical oxidation and reduction processes. The outstanding electrochemical performance of the Fe-TRGO material was evident, with enhanced current signals and lower peak potentials observed upon magnetic activation. Reversible and reproducible cycles of activation and deactivation were obtained as the peak heights and peak potentials remained relatively consistent with no apparent carryover between every step. Both components of Fe-TRGO play an electrocatalytic role in the electrochemical sensing. In the cases of the oxygen reduction reaction and reduction of cumene hydroperoxide, the iron oxide plays the role of an electrocatalyst, while in the cases of ascorbic acid, the enhanced electroactivity originates from the high surface area of the graphene portion in the Fe-TRGO hybrid material. The feasibility of this magnetically switchable method for on-demand sensing and energy production thus brings about potential developments for future electrochemical applications.

  2. Label-free measurement of cell-electrode cleft gap distance with high spatial resolution surface plasmon microscopy.

    PubMed

    Toma, Koji; Kano, Hiroshi; Offenhäusser, Andreas

    2014-12-23

    Understanding the interface between cells or tissues and artificial materials is of critical importance for a broad range of areas. For example, in neurotechnology, the interfaces between neurons and external devices create a link between technical and the nervous systems by stimulating or recording from neural tissue. Here, a more effective interface is required to enhance the electrical characteristics of neuronal recordings and stimulations. Up to now, the lack of a systematic characterization of cell-electrode interaction turns out to be the major bottleneck. In this work, we employed a recently developed surface plasmon microscope (SPM) to monitor in real-time the cell-metal interface and to measure in situ the gap distance of the cleft with the spatial resolution reaching to the optical diffraction limit. The SPM allowed determination of the distance of human embryonic kidney 293 cells cultured on gold surfaces coated with various peptides or proteins without any labeling. This method can dramatically simplify the interaction investigation at metal-living cell interface and should be incorporated into systematic characterization methods.

  3. Nonpoint sources of volatile organic compounds in urban areas - Relative importance of land surfaces and air

    USGS Publications Warehouse

    Lopes, T.J.; Bender, D.A.

    1998-01-01

    Volatile organic compounds (VOCs) commonly detected in urban waters across the United States include gasoline-related compounds (e.g. toluene, xylene) and chlorinated compounds (e.g. chloroform, tetrachloroethane [PCE], trichloroethene [TCE]). Statistical analysis of observational data and results of modeling the partitioning of VOCs between air and water suggest that urban land surfaces are the primary nonpoint source of most VOCs. Urban air is a secondary nonpoint source, but could be an important source of the gasoline oxygenate methyl-tert butyl ether (MTBE). Surface waters in urban areas would most effectively be protected by controlling land-surface sources.

  4. Comparison of Near-Surface Air Temperatures and MODIS Ice-Surface Temperatures at Summit, Greenland (2008-2013)

    NASA Technical Reports Server (NTRS)

    Shuman, Christopher A.; Hall, Dorothy K.; DiGirolamo, Nicolo E.; Mefford, Thomas K.; Schnaubelt, Michael J.

    2014-01-01

    We have investigated the stability of the MODerate resolution Imaging Spectroradiometer (MODIS) infrared-derived ice surface temperature (IST) data from Terra for use as a climate quality data record. The availability of climate quality air temperature data (TA) from a NOAA Global Monitoring Division observatory at Greenlands Summit station has enabled this high temporal resolution study of MODIS ISTs. During a 5 year period (July 2008 to August 2013), more than 2500 IST values were compared with 3-minute average TA values derived from the 1-minute data from NOAAs primary 2 m air temperature sensor. These data enabled an expected small offset between air and surface temperatures at this the ice sheet location to be investigated over multiple annual cycles.

  5. Air mediated dynamics of droplet impact on a smooth, solid surface

    NASA Astrophysics Data System (ADS)

    Kolinski, John; Mahadevan, L.; Rubinstein, Shmuel

    2014-11-01

    Before a falling drop can contact a solid surface, it must displace the air beneath it. Recent calculations and experiments show that as the drop approaches the surface, the air fails to drain, and instead compresses. As the air compresses, the pressure in the gas layer deforms the surface of the drop, thus inhibiting liquid-solid contact. Ultimately, the liquid droplet skates over a nanometer-thin film of air at a strikingly high velocity. These dynamics take place at fleeting timescales and diminutive length-scales, and are obscured by the bulk of the drop, making experimental observation difficult. We directly image the dynamics of the liquid-air interface, and use a novel form of TIR microscopy to study the dynamics and stability of the thin film of air beneath the drop. We show that the stability of the air film governs a novel transition in droplet impact events. NSF GRFP, ISF Grant Number 1415/12 and Harvard MRSEC (DMR-0820484).

  6. BOREAS AES Five-Day Averaged Surface Meteorological and Upper Air Data

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Strub, Richard; Newcomer, Jeffrey A.

    2000-01-01

    The Canadian Atmospheric Environment Service (AES) provided BOREAS with hourly and daily surface meteorological data from 23 of the AES meteorological stations located across Canada and upper air data from 1 station at The Pas, Manitoba. Due to copyright restrictions on the full resolution surface meteorological data, this data set contains 5-day average values for the surface parameters. The upper air data are provided in their full resolution form. The 5-day averaging was performed in order to create a data set that could be publicly distributed at no cost. Temporally, the surface meteorological data cover the period of January 1975 to December 1996 and the upper air data cover the period of January 1961 to November 1996. The data are provided in tabular ASCII files, and are classified as AFM-staff data. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC).

  7. Surface behavior of malonic acid adsorption at the air/water interface.

    PubMed

    Blower, Patrick G; Shamay, Eric; Kringle, Loni; Ota, Stephanie T; Richmond, Geraldine L

    2013-03-28

    The presence of organic materials adsorbed to the surfaces of aerosol particles has been demonstrated to be a determining factor in relevant atmospheric processes. Malonic acid is a small, water-soluble organic acid that is common in aerosols and is surface-active. A comprehensive investigation of the adsorption of malonic acid to the air/water interface was accomplished using vibrational sum frequency spectroscopy (VSFS) and surface tension measurements as functions of concentration and pH. Malonic acid was found to be weakly solvated at the air/water interface, and its orientation as a function of concentration was explored through different VSFS polarization schemes. pH-dependent experiments revealed that the surface-active species is the fully protonated species. Computational analyses were used to obtain depth-specific geometries of malonic acid at the air/water interface that confirm and enrich the experimental results.

  8. Electrospun lignin-derived carbon nanofiber mats surface-decorated with MnO2 nanowhiskers as binder-free supercapacitor electrodes with high performance

    NASA Astrophysics Data System (ADS)

    Ma, Xiaojing; Kolla, Praveen; Zhao, Yong; Smirnova, Alevtina L.; Fong, Hao

    2016-09-01

    The aim of this study is to explore innovative materials for the development of next-generation supercapacitor electrodes. The hypothesis is that, upon the surface-decoration with appropriate amount of MnO2 nanowhiskers, freestanding and highly graphitic electrospun carbon nanofiber (ECNF) mats (with fiber diameters of ∼200 nm and BET specific surface areas of ∼583 m2 g-1) derived from a natural product of lignin would be binder-free supercapacitor electrodes with high performance. To test the hypothesis, the ECNF mats have been prepared first; thereafter, the acquired ECNF mats have been surface-decorated with varied amounts of MnO2 nanowhiskers to prepare three types of ECNF/MnO2 mats. The morphological and structural properties of ECNF and ECNF/MnO2 mats are characterized by SEM, TEM and XRD, the weight percentages of MnO2 nanowhiskers in three ECNF/MnO2 mats are determined by thermal gravimetric analysis; while the electrochemical performance of each mat/electrode is evaluated by cyclic voltammetry, galvanostatic charge/discharge method, and electrochemical impedance spectroscopy. This study reveals that, all of the three ECNF/MnO2 mats/electrodes have significantly enhanced electrochemical performances compared to the ECNF mat/electrode; while the ECNF/MnO2 (1:1) mat/electrode exhibits the highest gravimetric capacitance of 83.3 F g-1, energy density of 84.3 W h kg-1, and power density of 5.72 kW kg-1.

  9. Recirculating electric air filter

    DOEpatents

    Bergman, Werner

    1986-01-01

    An electric air filter cartridge has a cylindrical inner high voltage eleode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

  10. Laplacian Electrode to Record Small Bowel Myoelectrical Activity From Abdominal Surface

    DTIC Science & Technology

    2001-10-25

    and by a grant from the Fondo de Investigaciones Sanitarias del Instituto Carlos III (FIS-00/1039)(Spain). -1 -0,5 0 0,5 1 0 5 10 15 20 time (s) e le...presented on the records. It is due to the fact that bioelectric potential captured from the body surface is proportional to the inverse second power of the...distance from the current dipole to the observation point while laplacian is inversely proportional to the fourth power of the distance from a dipole

  11. Surface functionalization of glassy carbon electrodes via adsorption, electrografting and click chemistry using quantum dots and alkynyl substituted phthalocyanines: a brief review

    NASA Astrophysics Data System (ADS)

    Nxele, Siphesihle Robin; Mashazi, Philani; Nyokong, Tebello

    2016-02-01

    In this work, glassy carbon electrodes are functionalised with alkynyl substituted phthalocyanines via electrografting and click chemistry as well as with quantum dots (QDs)-phthalocyanine conjugates via adsorption. The use of click chemistry and the addition of QDs is to try observe improvements in the electrocatalytic behaviour of electrocatalyst compared to similar electrocatalysts in literature. The electrografting and click chemistry methods provide greater molecule stability on the substrate surface due to the covalent bonds formed. Results show that these methods of electrode fabrication do improve the functionality of the electrocatalysts.

  12. Method of bonding a conductive layer on an electrode of an electrochemical cell

    DOEpatents

    Bowker, Jeffrey C.; Singh, Prabhakar

    1989-01-01

    A dense, electronically conductive interconnection layer 26 is bonded onto a porous, tubular, electronically conductive air electrode structure 16, optionally supported by a ceramic support 22, by (A) providing an air electrode surface, (B) forming on a selected portion of the electrode surface 24, without the use of pressure, particles of LaCrO.sub.3 doped with an element selected from the group consisting of Sr, Mg, Ca, Ba, Co, and mixtures thereof, where the particles have a deposit on their surface comprising calcium oxide and chromium oxide; (C) heating the particles with the oxide surface deposit in an oxidizing atmosphere at from 1,300.degree. C. to 1,550.degree. C., without the application of pressure, to provide a dense, sintered, interconnection material 26 bonded to the air electrode 16, where calcium and chromium from the surface deposit are incorporated into the structure of the LaCrO.sub.3. A solid electrolyte layer 18 can be applied to the uncovered portion of the air electrode, and a fuel electrode 20 can be applied to the solid electrolyte, to provide an electrochemical cell 10.

  13. Method of bonding a conductive layer on an electrode of an electrochemical cell

    DOEpatents

    Bowker, J.C.; Singh, P.

    1989-08-29

    A dense, electronically conductive interconnection layer is bonded onto a porous, tubular, electronically conductive air electrode structure, optionally supported by a ceramic support, by (A) providing an air electrode surface, (B) forming on a selected portion of the electrode surface, without the use of pressure, particles of LaCrO[sub 3] doped with an element selected from the group consisting of Sr, Mg, Ca, Ba, Co, and mixtures thereof, where the particles have a deposit on their surface comprising calcium oxide and chromium oxide; (C) heating the particles with the oxide surface deposit in an oxidizing atmosphere at from 1,300 C to 1,550 C, without the application of pressure, to provide a dense, sintered, interconnection material bonded to the air electrode, where calcium and chromium from the surface deposit are incorporated into the structure of the LaCrO[sub 3]. A solid electrolyte layer can be applied to the uncovered portion of the air electrode, and a fuel electrode can be applied to the solid electrolyte, to provide an electrochemical cell. 4 figs.

  14. Nanoscopic electrode molecular probes

    DOEpatents

    Krstic, Predrag S [Knoxville, TN; Meunier, Vincent [Knoxville, TN

    2012-05-22

    The present invention relates to a method and apparatus for enhancing the electron transport property measurements of a molecule when the molecule is placed between chemically functionalized carbon-based nanoscopic electrodes to which a suitable voltage bias is applied. The invention includes selecting a dopant atom for the nanoscopic electrodes, the dopant atoms being chemically similar to atoms present in the molecule, and functionalizing the outer surface and terminations of the electrodes with the dopant atoms.

  15. Structural changes of the KcsA potassium channel upon application of the electrode potential studied by surface-enhanced IR absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamakata, Akira; Shimizu, Hirofumi; Osawa, Masatoshi; Oiki, Shigetoshi

    2013-06-01

    Structural changes of the KcsA potassium channel fixed on gold electrode surface in the upright orientation were studied by surface-enhanced IR absorption spectroscopy (SEIRAS). Measurements were performed at neutral pH, where the activation gate is kept closed. Band intensities were enhanced for the asymmetric (1565 cm-1) and symmetric (1405 cm-1) OCO-carboxylate groups at negative electrode potentials in the K+ solution, but not in the Na+ solution. Even for the reverse-oriented channel, the enhanced OCO-carboxylate band was evident at negative potential. When TBA was loaded in the central cavity, the K+-specific OCO band was not elicited. These results indicate that the negative electrode potential renders the local K+ concentration accumulated at the vicinity of the electrode surface, and the KcsA channel bathed in high K+ changes conformation of the selectivity filter from the collapsed to the open, and OCO-carboxylate groups (D80 and E71) in the back of the filter were rearranged.

  16. Flow visualization study of grooved surface/surfactant/air sheet interaction

    NASA Technical Reports Server (NTRS)

    Reed, Jason C.; Weinstein, Leonard M.

    1989-01-01

    The effects of groove geometry, surfactants, and airflow rate have been ascertained by a flow-visualization study of grooved-surface models which addresses the possible conditions for skin friction-reduction in marine vehicles. It is found that the grooved surface geometry holds the injected bubble stream near the wall and, in some cases, results in a 'tube' of air which remains attached to the wall. It is noted that groove dimension and the use of surfactants can substantially affect the stability of this air tube; deeper grooves, surfactants with high contact angles, and angled air injection, are all found to increase the stability of the attached air tube, while convected disturbances and high shear increase interfacial instability.

  17. Regional change in snow water equivalent-surface air temperature relationship over Eurasia during boreal spring

    NASA Astrophysics Data System (ADS)

    Wu, Renguang; Chen, Shangfeng

    2016-10-01

    Present study investigates local relationship between surface air temperature and snow water equivalent (SWE) change over mid- and high-latitudes of Eurasia during boreal spring. Positive correlation is generally observed around the periphery of snow covered region, indicative of an effect of snow on surface temperature change. In contrast, negative correlation is usually found over large snow amount area, implying a response of snow change to wind-induced surface temperature anomalies. With the seasonal retreat of snow covered region, region of positive correlation between SWE and surface air temperature shifts northeastward from March to May. A diagnosis of surface heat flux anomalies in April suggests that the snow impact on surface air temperature is dominant in east Europe and west Siberia through modulating surface shortwave radiation. In contrast, atmospheric effect on SWE is important in Siberia and Russia Far East through wind-induced surface sensible heat flux change. Further analysis reveals that atmospheric circulation anomalies in association with snowmelt over east Siberia may be partly attributed to sea surface temperature anomalies in the North Atlantic and the atmospheric circulation anomaly pattern associated with snowmelt over Russia Far East has a close association with the Arctic Oscillation.

  18. Reversibly immobilized biological materials in monolayer films on electrodes

    SciTech Connect

    Weaver, P.F.; Frank, A.J.

    1991-04-08

    A method is provided for reversibly binding charged biological particles in a fluid medium to an electrode surface. The method comprises treating (e.g., derivatizing) the electrode surface with an electrochemically active material; connecting the electrode to an electrical potential; and exposing the fluid medium to the electrode surface in a manner such that the charged particles become adsorbed on the electrode surface.

  19. Using Response Surface Methodology as an Approach to Understand and Optimize Operational Air Power

    DTIC Science & Technology

    2010-01-01

    Introduction to Taguchi Methodology . In Taguchi Methods : Proceedings of the 1988 European Conference, 1-14. London: Elsevier Applied Science. Box G. E. and N... Methodology As an Approach to Understand and Optimize Operational Air Power Marvin L. Simpson, Jr. Resit Unal Report Documentation Page Form...00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Using Response Surface Methodology As an Approach to Understand and Optimize Operational Air Power

  20. Effect of pH in a Pd-based ethanol membraneless air breathing nanofluidic fuel cell with flow-through electrodes

    NASA Astrophysics Data System (ADS)

    López-Rico, C. A.; Galindo-de-la-Rosa, J.; Ledesma-García, J.; Arriaga, L. G.; Guerra-Balcázar, M.; Arjona, N.

    2015-12-01

    In this work, a nanofluidic fuel cell (NFC) in which streams flow through electrodes was used to investigate the role of pH in the cell performance using ethanol as fuel and two Pd nanoparticles as electrocatalysts: one commercially available (Pd/C from ETEK) and other synthesized using ionic liquids (Pd/C IL). The cell performances for both electrocatalysts in acid/acid (anodic/cathodic) streams were of 18.05 and 9.55 mW cm-2 for Pd/C ETEK and Pd/C IL. In alkaline/alkaline streams, decrease to 15.94 mW cm-2 for Pd/C ETEK and increase to 15.37 mW cm-2 for Pd/C IL. In alkaline/acidic streams both electrocatalysts showed similar cell voltages (up to 1 V); meanwhile power densities were of 87.6 and 99.4 mW cm-2 for Pd/C ETEK and Pd/C IL. The raise in cell performance can be related to a decrease in activation losses, the combined used of alkaline and acidic streams and these high values compared with flow-over fuel cells can be related to the enhancement of the cathodic mass transport by using three dimensional porous electrodes and two sources of oxygen: from air and from a saturated solution.

  1. Variations in the structure and electrochemical characteristics of membrane electrode assemblies during the endurance testing of hydrogen-air fuel cells

    NASA Astrophysics Data System (ADS)

    Avakov, V. B.; Aliev, A. D.; Bogdanovskaya, V. A.; Ivanitskii, B. A.; Kazanskii, L. P.; Kapustin, A. V.; Korchagin, O. V.; Landgraf, I. K.; Tarasevich, M. P.; Chalykh, A. E.

    2015-05-01

    Variations in the characteristics of a membrane-electrode assembly (MEA) are studied during the endurance testing of a hydrogen-air fuel cell (FC) based on a Nafion 212 proton conducting membrane and platinum catalysts. It is shown that the voltage drop observed during MEA testing was mainly due to physicochemical transformations of the cathode catalyst, i.e., the oxidation of platinum and its subsequent recrystallization with nanoparticle coarsening. It is established that the rate of degradation increases along with temperature and loading, and with periodic FC depressurization. It is concluded that the enhancing effects of additional factors of degradation, e.g., platinum ion transport to the proton-conducting membrane and corrosion of the carbon carrier, were responsible for these processes.

  2. Air Processes Resulting in a Surface Layer Pollution in Industrial Regions

    NASA Astrophysics Data System (ADS)

    Lesin, Yu V.; Leshukov, T. V.

    2016-08-01

    The article describes the air quality research in Western Siberia (Kemerovo region). The problem of air quality preservation in the conditions of mining industry intensive development is caused by the weather conditions which lead either to the concentration of pollutants in the surface layer, or to their migration to other geosphere, or to dissipation as a result of convective mixing or advection of air masses. Zoning of the territory in view of the research results provides insight into areas where the greatest risk to human health and life is formed.

  3. Concentration and density changes at an electrode surface and the principle of unchanging total concentration

    DOE PAGES

    Stephen W. Feldberg; Lewis, Ernie R.

    2016-02-17

    In this study, the principle of unchanging total concentration as described by Oldham and Feldberg [J. Phys. Chem. B, 103, 1699 (1999)] is invoked to analyze systems comprising a redox pair (Xz11 and Xz22) plus one or more non-electroactive species (Xz33,Xz44...Xzjmaxjmax) where Xzjj is the jth species with charge zj and concentration; cj. The principle states that if the diffusion coefficients for all species are identical and mass transport is governed by the Nernst-Planck expression, the total concentration does not change during any electrochemical perturbation, i.e.: Σjmaxj=1[Xzjj]=Σjmaxj=1 cj = SP With this principle we deduce the electrochemically induced difference betweenmore » the surface and bulk concentrations for each species. Those concentration differences are translated into density differences which are a function of the density of the solvent and of the concentration differences, molecular masses and the standard partial molar volumes of all species. Those density differences in turn can induce convection that will ultimately modify the observed current. However, we did not attempt to quantify details of the natural convection and current modification produced by those density differences.« less

  4. Optimal Spacing of Surface Electrode Arrays for Brain Machine Interface Applications

    PubMed Central

    Slutzky, Marc W.; Jordan, Luke R.; Krieg, Todd; Chen, Ming; Mogul, David J.; Miller, Lee E.

    2010-01-01

    Brain-machine interfaces (BMIs) use signals recorded directly from the brain to control an external device, such as a computer cursor or prosthetic limb. These control signals have been recorded from different levels of the brain, from field potentials at the scalp or cortical surface to single neuron action potentials. At present, the more invasive recordings have better signal quality, but also lower stability over time. Recently, subdural field potentials have been proposed as a stable, good quality source of control signals, with the potential for higher spatial and temporal bandwidth than EEG. Here we used finite element modeling in rats and humans and spatial spectral analysis in rats to compare the spatial resolution of signals recorded epidurally (outside the dura), with those recorded from subdural and scalp locations. Resolution of epidural and subdural signals was very similar in rats, and somewhat less so in human models. Both were substantially better than signals recorded at the scalp. Resolution of epidural and subdural signals in humans was much more similar when the cerebrospinal fluid layer thickness was reduced. This suggests that the less invasive epidural recordings may yield signals of similar quality to subdural recordings, and hence may be more attractive as a source of control signals for BMIs. PMID:20197598

  5. Space and surface charge excitation of a slanted dielectric interface between two electrodes

    SciTech Connect

    Seidel, D.B.; Levinson, C.L.

    1982-09-01

    The two-dimensional, electrostatic problem of a planar dielectric interface between two perfectly conducting plates has been solved numerically. The solution allows for an arbitrary interface angle relative to the plates as well as arbitrary distributions of both charge within the volume and surface charge along the interface. The problem is treated by first converting the governing differential equations to a pair of coupled integral equations using Green's function techniques, then solving these integral equations numerically using moment methods. This report details this solution and shows some sample results. This work was motivated by the need to understand the physics of dielectric breakdown by flashover in high voltage insulator applications. Of particular interest is the physics associated with Magnetic Flashover Inhibition (MFI), a possible method of significantly increasing insulator breakdown strength above that possible using currently proven technologies. A solution of this type has several apparent advantages over existing techniques for treating this type of problem and is currently being adapted for use in an existing two-dimensional Particle-In-Cell (PIC) code.

  6. Electrocatalytic determination of sumatriptan on the surface of carbon-paste electrode modified with a composite of cobalt/Schiff-base complex and carbon nanotube.

    PubMed

    Amiri, Mandana; Pakdel, Zohreh; Bezaatpour, Abolfazl; Shahrokhian, Saeed

    2011-06-01

    The electrochemical oxidation of sumatriptan on the surface of carbon paste electrode modified with multi-walled carbon nanotube and cobalt methyl-salophen complex is studied by using cyclic voltammetry and polarization studies. The results indicate that the drug is irreversibly oxidized in a one electron oxidation mechanism. It was found that the peak potential shifted negatively with increasing pH, confirms that H(+) participate in the oxidation process. The electrode is shown to be very effective for the detection of sumatriptan in the presence of other biological reductant compounds. The prepared modified electrode exhibits a very good resolution between the voltammetric peaks of sumatriptan, ascorbic acid and uric acid, which makes it suitable for the simultaneous detection of sumatriptan in the presence of these compounds in clinical and pharmaceutical preparations. It can be concluded that multi-walled carbon nanotube and Shiff base complex have synergic effect on electroacatalytic oxidation of sumatriptan. A linear range of 1-1000μM and detection limit of 0.3μM was obtained for sumatriptan from DPV measurements using this electrode in 0.1M acetate buffered solution of pH 5.0. The electrode has been applied successfully for the determination of sumatriptan in synthetic serum and commercial tablets.

  7. Pd-Au nanoparticle decorated carbon nanotube as a sensing layer on the surface of glassy carbon electrode for electrochemical determination of ceftazidime.

    PubMed

    Shahrokhian, Saeed; Salimian, Razieh; Rastgar, Shokoufeh

    2014-01-01

    A simple electrodeposition method is employed to construct a thin film modifier of palladium-gold nanoparticles (Pd-AuNPs) decorated multi-walled carbon nanotube (MWCNT) on the surface of glassy carbon electrode (GCE). Morphology and property of Pd-AuNPs-MWCNT have been examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Electrochemical performance of Pd-AuNPs-MWCNT/GCE for detection of ceftazidime (CFZ) has been investigated by cyclic voltammetry (CV). This nanostructured film modified electrode effectively exhibited enhanced properties for detection of ceftazidime (CFZ). The effects of various experimental variables such as, the amount of casted MWCNT, time and potential of deposition of metal nanoparticles and the pH of the buffered solution on the electrode response are optimized. The proposed electrode showed a linear dynamic range of 0.05-50μM and the detection limit of 1nM for the CFZ. The modified electrode successfully supports the sensitive detection of trace amounts of the CFZ in pharmaceutical and clinical preparations.

  8. A solvent-free microbial-activated air cathode battery paper platform made with pencil-traced graphite electrodes.

    PubMed

    Lee, Seung Ho; Ban, Ju Yeon; Oh, Chung-Hun; Park, Hun-Kuk; Choi, Samjin

    2016-06-23

    We present the fabrication of an ultra-low cost, disposable, solvent-free air cathode all-paper microbial fuel cell (MFC) that does not utilize any chemical treatments. The anode and cathode were fabricated by depositing graphite particles by drawing them on paper with a pencil (four strokes). Hydrophobic parchment paper was used as a proton exchange membrane (PEM) to allow only H(+) to pass. Air cathode MFC technology, where O2 was used as an electron acceptor, was implemented on the paper platform. The bioelectric current was generated by an electrochemical process involving the redox couple of microbial-activated extracellular electron transferred electrons, PEM-passed H(+), and O2 in the cathode. A fully micro-integrated pencil-traced MFC showed a fast start-time, producing current within 10 s after injection of bacterial cells. A single miniaturized all-paper air cathode MFC generated a maximum potential of 300 mV and a maximum current of 11 μA during 100 min after a single injection of Shewanella oneidensis. The micro-fabricated solvent-free air cathode all-paper MFC generated a power of 2,270 nW (5.68 mW/m(2)). The proposed solvent-free air cathode paper-based MFC device could be used for environmentally-friendly energy storage as well as in single-use medical power supplies that use organic matter.

  9. A solvent-free microbial-activated air cathode battery paper platform made with pencil-traced graphite electrodes

    PubMed Central

    Lee, Seung Ho; Ban, Ju Yeon; Oh, Chung-Hun; Park, Hun-Kuk; Choi, Samjin

    2016-01-01

    We present the fabrication of an ultra-low cost, disposable, solvent-free air cathode all-paper microbial fuel cell (MFC) that does not utilize any chemical treatments. The anode and cathode were fabricated by depositing graphite particles by drawing them on paper with a pencil (four strokes). Hydrophobic parchment paper was used as a proton exchange membrane (PEM) to allow only H+ to pass. Air cathode MFC technology, where O2 was used as an electron acceptor, was implemented on the paper platform. The bioelectric current was generated by an electrochemical process involving the redox couple of microbial-activated extracellular electron transferred electrons, PEM-passed H+, and O2 in the cathode. A fully micro-integrated pencil-traced MFC showed a fast start-time, producing current within 10 s after injection of bacterial cells. A single miniaturized all-paper air cathode MFC generated a maximum potential of 300 mV and a maximum current of 11 μA during 100 min after a single injection of Shewanella oneidensis. The micro-fabricated solvent-free air cathode all-paper MFC generated a power of 2,270 nW (5.68 mW/m2). The proposed solvent-free air cathode paper-based MFC device could be used for environmentally-friendly energy storage as well as in single-use medical power supplies that use organic matter. PMID:27333815

  10. A solvent-free microbial-activated air cathode battery paper platform made with pencil-traced graphite electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Seung Ho; Ban, Ju Yeon; Oh, Chung-Hun; Park, Hun-Kuk; Choi, Samjin

    2016-06-01

    We present the fabrication of an ultra-low cost, disposable, solvent-free air cathode all-paper microbial fuel cell (MFC) that does not utilize any chemical treatments. The anode and cathode were fabricated by depositing graphite particles by drawing them on paper with a pencil (four strokes). Hydrophobic parchment paper was used as a proton exchange membrane (PEM) to allow only H+ to pass. Air cathode MFC technology, where O2 was used as an electron acceptor, was implemented on the paper platform. The bioelectric current was generated by an electrochemical process involving the redox couple of microbial-activated extracellular electron transferred electrons, PEM-passed H+, and O2 in the cathode. A fully micro-integrated pencil-traced MFC showed a fast start-time, producing current within 10 s after injection of bacterial cells. A single miniaturized all-paper air cathode MFC generated a maximum potential of 300 mV and a maximum current of 11 μA during 100 min after a single injection of Shewanella oneidensis. The micro-fabricated solvent-free air cathode all-paper MFC generated a power of 2,270 nW (5.68 mW/m2). The proposed solvent-free air cathode paper-based MFC device could be used for environmentally-friendly energy storage as well as in single-use medical power supplies that use organic matter.

  11. Mathematical estimation of the level of microbial contamination on spacecraft surfaces by volumetric air sampling

    NASA Technical Reports Server (NTRS)

    Oxborrow, G. S.; Roark, A. L.; Fields, N. D.; Puleo, J. R.

    1974-01-01

    Microbiological sampling methods presently used for enumeration of microorganisms on spacecraft surfaces require contact with easily damaged components. Estimation of viable particles on surfaces using air sampling methods in conjunction with a mathematical model would be desirable. Parameters necessary for the mathematical model are the effect of angled surfaces on viable particle collection and the number of viable cells per viable particle. Deposition of viable particles on angled surfaces closely followed a cosine function, and the number of viable cells per viable particle was consistent with a Poisson distribution. Other parameters considered by the mathematical model included deposition rate and fractional removal per unit time. A close nonlinear correlation between volumetric air sampling and airborne fallout on surfaces was established with all fallout data points falling within the 95% confidence limits as determined by the mathematical model.

  12. Surface analysis and electrochemistry of a robust carbon-nanofiber-based electrode platform H2O2 sensor

    NASA Astrophysics Data System (ADS)

    Suazo-Dávila, D.; Rivera-Meléndez, J.; Koehne, J.; Meyyappan, M.; Cabrera, C. R.

    2016-10-01

    A vertically aligned carbon nanofiber-based (VACNF) electrode platform was developed for an enzymeless hydrogen peroxide sensor. Vertical nanofibers have heights on the order of 2-3 μm, and diameters that vary from 50 to 100 nm as seen by atomic force microscopy. The VACNF was grown as individual, vertically, and freestanding structures using plasma-enhanced chemical vapor deposition. The electrochemical sensor, for the hydrogen peroxide measurement in solution, showed stability and reproducibility in five consecutive calibration curves with different hydrogen peroxide concentrations over a period of 3 days. The detection limit was 66 μM. The sensitivity for hydrogen peroxide electrochemical detection was 0.0906 mA cm-2 mM-1, respectively. The sensor was also used for the measurement of hydrogen peroxide as the by-product of the reaction of cholesterol with cholesterol oxidase as a biosensor application. The sensor exhibits linear behavior in the range of 50 μM-1 mM in cholesterol concentrations. The surface analysis and electrochemistry characterization is presented.

  13. Insight into the Role of Surface Wettability in Electrocatalytic Hydrogen Evolution Reactions Using Light-Sensitive Nanotubular TiO2 Supported Pt Electrodes

    PubMed Central

    Meng, Chenhui; Wang, Bing; Gao, Ziyue; Liu, Zhaoyue; Zhang, Qianqian; Zhai, Jin

    2017-01-01

    Surface wettability is of importance for electrochemical reactions. Herein, its role in electrochemical hydrogen evolution reactions is investigated using light-sensitive nanotubular TiO2 supported Pt as hydrogen evolution electrodes (HEEs). The HEEs are fabricated by photocatalytic deposition of Pt particles on TiO2 nanotubes followed by hydrophobization with vaporized octadecyltrimethoxysilane (OTS) molecules. The surface wettability of HEEs is subsequently regulated in situ from hydrophobicity to hydrophilicity by photocatalytic decomposition of OTS molecules using ultraviolet light. It is found that hydrophilic HEEs demonstrate a larger electrochemical active area of Pt and a lower adhesion force to a gas bubble when compared with hydrophobic ones. The former allows more protons to react on the electrode surface at small overpotential so that a larger current is produced. The latter leads to a quick release of hydrogen gas bubbles from the electrode surface at large overpotential, which ensures the contact between catalysts and electrolyte. These two characteristics make hydrophilic HEEs generate a much high current density for HERs. Our results imply that the optimization of surface wettability is of significance for improving the electrocatalytic activity of HEEs. PMID:28165487

  14. Insight into the Role of Surface Wettability in Electrocatalytic Hydrogen Evolution Reactions Using Light-Sensitive Nanotubular TiO2 Supported Pt Electrodes

    NASA Astrophysics Data System (ADS)

    Meng, Chenhui; Wang, Bing; Gao, Ziyue; Liu, Zhaoyue; Zhang, Qianqian; Zhai, Jin

    2017-02-01

    Surface wettability is of importance for electrochemical reactions. Herein, its role in electrochemical hydrogen evolution reactions is investigated using light-sensitive nanotubular TiO2 supported Pt as hydrogen evolution electrodes (HEEs). The HEEs are fabricated by photocatalytic deposition of Pt particles on TiO2 nanotubes followed by hydrophobization with vaporized octadecyltrimethoxysilane (OTS) molecules. The surface wettability of HEEs is subsequently regulated in situ from hydrophobicity to hydrophilicity by photocatalytic decomposition of OTS molecules using ultraviolet light. It is found that hydrophilic HEEs demonstrate a larger electrochemical active area of Pt and a lower adhesion force to a gas bubble when compared with hydrophobic ones. The former allows more protons to react on the electrode surface at small overpotential so that a larger current is produced. The latter leads to a quick release of hydrogen gas bubbles from the electrode surface at large overpotential, which ensures the contact between catalysts and electrolyte. These two characteristics make hydrophilic HEEs generate a much high current density for HERs. Our results imply that the optimization of surface wettability is of significance for improving the electrocatalytic activity of HEEs.

  15. Comparison of AIRS and IASI Surface Observations of DomeC in Antarctica with Surface Temperatures Reported by AWS8989

    NASA Astrophysics Data System (ADS)

    Elliott, D. A.; Aumann, H. H.

    2008-12-01

    The decrease of the ice in the Antarctic indicates that the land and the ocean along the coastline are warming up. Representative numbers for warming at the surface further inland are much more complicated due to the vast size of the continent. The Automated Weather Station AWS8989 has been reporting temperatures from Concordia Station on DomeC in Antarctica every 10 minutes since 1996. AWS8989 is located about 1 mile from the power plant at Concordia Station. We compare the surface temperatures at DomeC deduced from Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI) data to the surface temperature reported by Automated Weather Station AWS8989 for the year between May 1, 2007 and April 30, 2008. AIRS and IASI measure the mean skin brightness temperature in a 50-km-radius circle from DomeC, while the AWS reports the temperature of the air at 3 meters above the surface. The AIRS and IASI measurements agree within 50 mK over the entire temperature range from 190 K in the winter to 245 K in the summer, but consistently report a colder temperature than the AWS8989. The warm bias of AWS8989 is season dependent, changing from 1.5 K warm in the winter to 5.5 K warm in the summer. Comparison of AIRS data in 2005 with a temporary Italian AWS (Aumann et al. 2006) and located several miles upwind from the power station, showed no significant temperature bias throughout the year 2005. The warm readings of AWS8989 are likely due the combination of a season-independent 1.5 K warm calibration bias in the AWS8989 sensor plus thermal contamination of the AWS8989 site. This heat island effect ranges from near zero during the low-activity winter months to about 4 K during the summer months with the highest activity at Concordia Station. The fact that activities at DomeC are increasing makes surface temperature trends from AWS8989 suspect. AIRS and IASI are hyperspectral infrared sounders designed in support of weather forecasting and climate

  16. Concentration and density changes at an electrode surface and the principle of unchanging total concentration

    SciTech Connect

    Stephen W. Feldberg; Lewis, Ernie R.

    2016-02-17

    In this study, the principle of unchanging total concentration as described by Oldham and Feldberg [J. Phys. Chem. B, 103, 1699 (1999)] is invoked to analyze systems comprising a redox pair (Xz11 and Xz22) plus one or more non-electroactive species (Xz33,Xz44...Xzjmaxjmax) where Xzjj is the jth species with charge zj and concentration; cj. The principle states that if the diffusion coefficients for all species are identical and mass transport is governed by the Nernst-Planck expression, the total concentration does not change during any electrochemical perturbation, i.e.: Σjmaxj=1[Xzjj]=Σjmaxj=1 cj = SP With this principle we deduce the electrochemically induced difference between the surface and bulk concentrations for each species. Those concentration differences are translated into density differences which are a function of the density of the solvent and of the concentration differences, molecular masses and the standard partial molar volumes of all species. Those density differences in turn can induce convection that will ultimately modify the observed current. However, we did not attempt to quantify details of the natural convection and current modification produced by those density differences.

  17. An Air Temperature Cloud Height Precipitation Phase Determination Scheme for Surface Based Modeling

    NASA Astrophysics Data System (ADS)

    Feiccabrino, J. M.

    2015-12-01

    Many hydrological and ecological models use simple surface temperature threshold equations rather than coupling with a complex meteorological model to determine if precipitation is rain or snow. Some comparative studies have found, the most common rain/snow threshold variable, air temperature to have more precipitation phase error than dew-point or wet-bulb temperature, which account for the important secondary role of humidity in the melting and sublimation processes. However, just like surface air temperature, surface humidity is often effected by soil conditions and vegetation and is therefore not always representative of the atmospheric humidity precipitation falls through. A viable alternative to using surface humidity as a proxy for atmospheric moisture would be to adjust the rain snow threshold for changes in cloud height. The height of a cloud base above the ground gives the depth of an unsaturated layer. An unsaturated atmospheric layer should have much different melting and sublimation rates than a saturated cloud layer. Therefore, rain and snow percentages at a given surface air temperature should change with the height of the lowest cloud base. This study uses hourly observations from 12 U.S. manually augmented meteorological stations located in the Great Plains and Midwest upwind or away from major water bodies in relatively flat areas in an attempt to limit geographical influences. The surface air temperature threshold for the ground to 200 feet (under 100m) was 0.0°C, 0.6°C for 300-600 feet (100-200m), 1.1°C for 700-1200 feet (300-400m), 1.7°C for 1300-2000 feet (500-600m), and 2.2°C for 2100-3300 feet (700-1000m). Total precipitation error for these cloud height air temperature thresholds reduced the error from the single air temperature threshold 1.1°C by 15% from 14% to 12% total error between -2.2°C and 3.9°C. These air temperature cloud height thresholds resulted in 1.5% less total error than the dew-point temperature threshold 0.0

  18. Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

    NASA Technical Reports Server (NTRS)

    Loughner, Christopher P.; Tzortziou, Maria; Follette-Cook, Melanie; Pickering, Kenneth E.; Goldberg, Daniel; Satam, Chinmay; Weinheimer, Andrew; Crawford, James H.; Knapp, David J.; Montzka, Denise D.; Diskin, Glenn S.; Dickerson, Russell R.

    2014-01-01

    Meteorological and air-quality model simulations are analyzed alongside observations to investigate the role of the Chesapeake Bay breeze on surface air quality, pollutant transport, and boundary layer venting. A case study was conducted to understand why a particular day was the only one during an 11-day ship-based field campaign on which surface ozone was not elevated in concentration over the Chesapeake Bay relative to the closest upwind site and why high ozone concentrations were observed aloft by in situ aircraft observations. Results show that southerly winds during the overnight and early-morning hours prevented the advection of air pollutants from the Washington, D.C., and Baltimore, Maryland, metropolitan areas over the surface waters of the bay. A strong and prolonged bay breeze developed during the late morning and early afternoon along the western coastline of the bay. The strength and duration of the bay breeze allowed pollutants to converge, resulting in high concentrations locally near the bay-breeze front within the Baltimore metropolitan area, where they were then lofted to the top of the planetary boundary layer (PBL). Near the top of the PBL, these pollutants were horizontally advected to a region with lower PBL heights, resulting in pollution transport out of the boundary layer and into the free troposphere. This elevated layer of air pollution aloft was transported downwind into New England by early the following morning where it likely mixed down to the surface, affecting air quality as the boundary layer grew.

  19. Air coupled ultrasonic detection of surface defects in food cans

    NASA Astrophysics Data System (ADS)

    Seco, Fernando; Ramón Jiménez, Antonio; del Castillo, María Dolores

    2006-06-01

    In this paper, we describe an ultrasonic inspection system used for detection of surface defects in food cans. The system operates in the pulse-echo mode and analyses the 220 kHz ultrasonic signal backscattered by the object. The classification of samples into valid or defective is achieved with χ2 statistics and the k nearest neighbour method, applied to features computed from the envelope of the ultrasonic echo. The performance of the system is demonstrated empirically in detection of the presence of the pull tab on the removable lid of easy-open food cans, in a production line. It is found that three factors limit the performance of the classification: the misalignment of the samples, their separation of the ultrasonic transducer, and the vibration of the conveyor belt. When these factors are controlled, classification success rates between 94% and 99% are achieved.

  20. 3-D Surface Depression Profiling Using High Frequency Focused Air-Coupled Ultrasonic Pulses

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Kautz, Harold E.; Abel, Phillip B.; Whalen, Mike F.; Hendricks, J. Lynne; Bodis, James R.

    1999-01-01

    Surface topography is an important variable in the performance of many industrial components and is normally measured with diamond-tip profilometry over a small area or using optical scattering methods for larger area measurement. This article shows quantitative surface topography profiles as obtained using only high-frequency focused air-coupled ultrasonic pulses. The profiles were obtained using a profiling system developed by NASA Glenn Research Center and Sonix, Inc (via a formal cooperative agreement). (The air transducers are available as off-the-shelf items from several companies.) The method is simple and reproducible because it relies mainly on knowledge and constancy of the sound velocity through the air. The air transducer is scanned across the surface and sends pulses to the sample surface where they are reflected back from the surface along the same path as the incident wave. Time-of-flight images of the sample surface are acquired and converted to depth/surface profile images using the simple relation (d = V*t/2) between distance (d), time-of-flight (t), and the velocity of sound in air (V). The system has the ability to resolve surface depression variations as small as 25 microns, is useable over a 1.4 mm vertical depth range, and can profile large areas only limited by the scan limits of the particular ultrasonic system. (Best-case depth resolution is 0.25 microns which may be achievable with improved isolation from vibration and air currents.) The method using an optimized configuration is reasonably rapid and has all quantitative analysis facilities on-line including 2-D and 3-D visualization capability, extreme value filtering (for faulty data), and leveling capability. Air-coupled surface profilometry is applicable to plate-like and curved samples. In this article, results are shown for several proof-of-concept samples, plastic samples burned in microgravity on the STS-54 space shuttle mission, and a partially-coated cylindrical ceramic