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Sample records for arrays reveal electrochemically

  1. Electrochemical Preparation of WO_3 Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    1 Results Ordered WO3 nanowires arrays have been fabricated by electrochemical deposition with anodic aluminum oxide (AAO) templates and annealing the W nanowire arrays in air at 400 ℃. The morphology and the chemical composition of WO3 nanowires arrays were characterized by Scanning Electron Microscopy (SEM),Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and X-ray diffraction (XRD). The results show that the diameters of the WO3 nanowires are about 90 nm, which is in go...

  2. Optical Sensing with Simultaneous Electrochemical Control in Metal Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Janos Vörös

    2010-11-01

    Full Text Available This work explores the alternative use of noble metal nanowire systems in large-scale array configurations to exploit both the nanowires’ conductive nature and localized surface plasmon resonance (LSPR. The first known nanowire-based system has been constructed, with which optical signals are influenced by the simultaneous application of electrochemical potentials. Optical characterization of nanowire arrays was performed by measuring the bulk refractive index sensitivity and the limit of detection. The formation of an electrical double layer was controlled in NaCl solutions to study the effect of local refractive index changes on the spectral response. Resonance peak shifts of over 4 nm, a bulk refractive index sensitivity up to 115 nm/RIU and a limit of detection as low as 4.5 × 10−4 RIU were obtained for gold nanowire arrays. Simulations with the Multiple Multipole Program (MMP confirm such bulk refractive index sensitivities. Initial experiments demonstrated successful optical biosensing using a novel form of particle-based nanowire arrays. In addition, the formation of an ionic layer (Stern-layer upon applying an electrochemical potential was also monitored by the shift of the plasmon resonance.

  3. A CMOS Electrochemical Impedance Spectroscopy (EIS) Biosensor Array.

    Science.gov (United States)

    Manickam, Arun; Chevalier, Aaron; McDermott, Mark; Ellington, Andrew D; Hassibi, Arjang

    2010-12-01

    In this paper, we present a fully integrated biosensor 10 × 10 array in a standard complementary metal-oxide semiconducor process, which takes advantage of electrochemical impedance spectroscopy (EIS). We also show that this system is able to detect various biological analytes, such as DNA and proteins, in real time and without the need for molecular labels. In each pixel of this array, we implement a biocompatible Au electrode transducer and embedded sensor circuitry which takes advantage of the coherent detector to measure the impedance of the associated electrode-electrolyte interface. This chip is capable of concurrently measuring admittance values as small as 10(-8) Ω(-1) within the array with the detection dynamic range of more than 90 dB in the frequency range of 10 Hz-50 MHz. PMID:23850755

  4. Tin Oxide Nanorod Array-Based Electrochemical Hydrogen Peroxide Biosensor

    Directory of Open Access Journals (Sweden)

    Liu Jinping

    2010-01-01

    Full Text Available Abstract SnO2 nanorod array grown directly on alloy substrate has been employed as the working electrode of H2O2 biosensor. Single-crystalline SnO2 nanorods provide not only low isoelectric point and enough void spaces for facile horseradish peroxidase (HRP immobilization but also numerous conductive channels for electron transport to and from current collector; thus, leading to direct electrochemistry of HRP. The nanorod array-based biosensor demonstrates high H2O2 sensing performance in terms of excellent sensitivity (379 μA mM−1 cm−2, low detection limit (0.2 μM and high selectivity with the apparent Michaelis–Menten constant estimated to be as small as 33.9 μM. Our work further demonstrates the advantages of ordered array architecture in electrochemical device application and sheds light on the construction of other high-performance enzymatic biosensors.

  5. Preparation of electrochemically active silicon nanotubes in highly ordered arrays

    Directory of Open Access Journals (Sweden)

    Tobias Grünzel

    2013-10-01

    Full Text Available Silicon as the negative electrode material of lithium ion batteries has a very large capacity, the exploitation of which is impeded by the volume changes taking place upon electrochemical cycling. A Si electrode displaying a controlled porosity could circumvent the difficulty. In this perspective, we present a preparative method that yields ordered arrays of electrochemically competent silicon nanotubes. The method is based on the atomic layer deposition of silicon dioxide onto the pore walls of an anodic alumina template, followed by a thermal reduction with lithium vapor. This thermal reduction is quantitative, homogeneous over macroscopic samples, and it yields amorphous silicon and lithium oxide, at the exclusion of any lithium silicides. The reaction is characterized by spectroscopic ellipsometry for thin silica films, and by nuclear magnetic resonance and X-ray photoelectron spectroscopy for nanoporous samples. After removal of the lithium oxide byproduct, the silicon nanotubes can be contacted electrically. In a lithium ion electrolyte, they then display the electrochemical waves also observed for other bulk or nanostructured silicon systems. The method established here paves the way for systematic investigations of how the electrochemical properties (capacity, charge/discharge rates, cyclability of nanoporous silicon negative lithium ion battery electrode materials depend on the geometry.

  6. A microfluidic paper-based electrochemical biosensor array for multiplexed detection of metabolic biomarkers

    OpenAIRE

    Chen Zhao, Martin M Thuo and Xinyu Liu

    2013-01-01

    Paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. This paper reports a microfluidic paper-based electrochemical biosensor array for multiplexed detection of physiologically relevant metabolic biomarkers. Different from existing paper-based electrochemical devices, our device includes an array of eight electrochemical sensors and utilizes a handheld custom-made electrochemical reader (potentiostat) for signal readout. The b...

  7. New Applications of Electrochemically Produced Porous Semiconductors and Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Leisner Malte

    2010-01-01

    Full Text Available Abstract The growing demand for electro mobility together with advancing concepts for renewable energy as primary power sources requires sophisticated methods of energy storage. In this work, we present a Li ion battery based on Si nanowires, which can be produced reliable and cheaply and which shows superior properties, such as a largely increased capacity and cycle stability. Sophisticated methods based on electrochemical pore etching allow to produce optimized regular arrays of nanowires, which can be stabilized by intrinsic cross-links, which serve to avoid unwanted stiction effects and allow easy processing.

  8. Nanopatterning of transition metal surfaces via electrochemical dimple array formation.

    Science.gov (United States)

    Singh, Sherdeep; Barden, Warren R T; Kruse, Peter

    2008-12-23

    Nanoscale surface patterning is of great importance for applications ranging from catalysts to biomaterials. We show the formation of ordered nanoscale dimple arrays on titanium, tungsten, and zirconium during electropolishing, demonstrating versatility of a process previously only reported for tantalum. This is a rare example of an electrochemical pattern formation process that can be translated to other materials. The dimpled surfaces have been characterized with scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy, and electrochemical conditions were optimized for each material. While conditions for titanium and tungsten resemble those for tantalum, zirconium requires a different type of electrolyte. Given the appropriate electropolishing chemistry, formation of these patterns should be possible on any metal surface. The process is very robust on homogeneous surfaces, but sensitive to inhomogeneities in chemical composition, such as in the case of differentially etched alloys. An alternative process for some materials such as platinum is the coating of a dimpled substrate with a thin film of the required material. PMID:19206279

  9. AC Electrochemical Deposition of CdS Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    QIN; DongHuan

    2001-01-01

    Since the successful growth of carbon nanotubes, one-dimensional materials have been a focused research field both because of their fundamental importance and the wide-ranging potential applications in nano devices. Many approaches are used to fabricate nanowires, such as crystal growth. In order to obtain nanowires whose growth is more easily controlled, electrochemical synthesis in a template is taken as one of the most efficient methods. To date, Co, Fe, Ni, CuCo1-3 and other nanowire arrays have been fabricated successfully by electrodepositing corresponding metal ion into the porous aluminum oxide (PAO) membrane or other non-magnetic materials. Cadmium sulfide(CdS), as one of the most important semiconductor material, is a n-type semiconductor. The ability to fine tune their fundamental electronic and optical properties by simply varying the cruster size, rather than composition, makes them highly attractive for a variety of possible application. In this paper, we report our work of fabricating CdS nanowire arrays based on AC electrolysis into the pores of an anodic aluminum oxide(AAO), the structure and morphology were characterized by XRD and TEM.  ……

  10. AC Electrochemical Deposition of CdS Nanowire Arrays

    Institute of Scientific and Technical Information of China (English)

    QIN DongHuan; LI HuLin

    2001-01-01

    @@ Since the successful growth of carbon nanotubes, one-dimensional materials have been a focused research field both because of their fundamental importance and the wide-ranging potential applications in nano devices. Many approaches are used to fabricate nanowires, such as crystal growth. In order to obtain nanowires whose growth is more easily controlled, electrochemical synthesis in a template is taken as one of the most efficient methods. To date, Co, Fe, Ni, CuCo1-3 and other nanowire arrays have been fabricated successfully by electrodepositing corresponding metal ion into the porous aluminum oxide (PAO) membrane or other non-magnetic materials. Cadmium sulfide(CdS), as one of the most important semiconductor material, is a n-type semiconductor. The ability to fine tune their fundamental electronic and optical properties by simply varying the cruster size, rather than composition, makes them highly attractive for a variety of possible application. In this paper, we report our work of fabricating CdS nanowire arrays based on AC electrolysis into the pores of an anodic aluminum oxide(AAO), the structure and morphology were characterized by XRD and TEM.

  11. A microfluidic paper-based electrochemical biosensor array for multiplexed detection of metabolic biomarkers

    Directory of Open Access Journals (Sweden)

    Chen Zhao, Martin M Thuo and Xinyu Liu

    2013-01-01

    Full Text Available Paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. This paper reports a microfluidic paper-based electrochemical biosensor array for multiplexed detection of physiologically relevant metabolic biomarkers. Different from existing paper-based electrochemical devices, our device includes an array of eight electrochemical sensors and utilizes a handheld custom-made electrochemical reader (potentiostat for signal readout. The biosensor array can detect several analytes in a sample solution and produce multiple measurements for each analyte from a single run. Using the device, we demonstrate simultaneous detection of glucose, lactate and uric acid in urine, with analytical performance comparable to that of the existing commercial and paper-based platforms. The paper-based biosensor array and its electrochemical reader will enable the acquisition of high-density, statistically meaningful diagnostic information at the point of care in a rapid and cost-efficient way.

  12. A microfluidic paper-based electrochemical biosensor array for multiplexed detection of metabolic biomarkers

    Science.gov (United States)

    Zhao, Chen; Thuo, Martin M.; Liu, Xinyu

    2013-10-01

    Paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. This paper reports a microfluidic paper-based electrochemical biosensor array for multiplexed detection of physiologically relevant metabolic biomarkers. Different from existing paper-based electrochemical devices, our device includes an array of eight electrochemical sensors and utilizes a handheld custom-made electrochemical reader (potentiostat) for signal readout. The biosensor array can detect several analytes in a sample solution and produce multiple measurements for each analyte from a single run. Using the device, we demonstrate simultaneous detection of glucose, lactate and uric acid in urine, with analytical performance comparable to that of the existing commercial and paper-based platforms. The paper-based biosensor array and its electrochemical reader will enable the acquisition of high-density, statistically meaningful diagnostic information at the point of care in a rapid and cost-efficient way.

  13. Electrochemical properties of high-power supercapacitors using ordered NiO coated Si nanowire array electrodes

    Science.gov (United States)

    Lu, Fang; Qiu, Mengchun; Qi, Xiang; Yang, Liwen; Yin, Jinjie; Hao, Guolin; Feng, Xiang; Li, Jun; Zhong, Jianxin

    2011-08-01

    Highly ordered NiO coated Si nanowire arrays are fabricated as electrode materials for electrochemical supercapacitors (ES) via depositing Ni on electroless-etched Si nanowires and subsequently annealing. The electrochemical tests reveal that the constructed electrode has superior electrical conductibility and more active sites per unit area for chemical reaction processes, thereby possessing good cycle stability, high specific capacity, and low internal resistance. The specific capacity is up to 787.5 F g-1 at a discharge current of 2.5 mA and decreases slightly with 4.039% loss after 500 cycles, while the equivalent internal resistance is ˜3.067 Ω. Owing to its favorable electrochemical performance, this ordered hybrid array nanostructure is a promising electrode material in future commercial ES.

  14. MnO 2 nanotube and nanowire arrays by electrochemical deposition for supercapacitors

    Science.gov (United States)

    Xia, Hui; Feng, Jinkui; Wang, Hailong; Lai, Man On; Lu, Li

    Highly ordered MnO 2 nanotube and nanowire arrays are successfully synthesized via a electrochemical deposition technique using porous alumina templates. The morphologies and microstructures of the MnO 2 nanotube and nanowire arrays are investigated by field emission scanning electron microscopy and transmission electron microscopy. Electrochemical characterization demonstrates that the MnO 2 nanotube array electrode has superior capacitive behaviour to that of the MnO 2 nanowire array electrode. In addition to high specific capacitance, the MnO 2 nanotube array electrode also exhibits good rate capability and good cycling stability, which makes it promising candidate for supercapacitors.

  15. MnO{sub 2} nanotube and nanowire arrays by electrochemical deposition for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Hui; Feng, Jinkui; Wang, Hailong; Lai, Man On; Lu, Li [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2010-07-01

    Highly ordered MnO{sub 2} nanotube and nanowire arrays are successfully synthesized via a electrochemical deposition technique using porous alumina templates. The morphologies and microstructures of the MnO{sub 2} nanotube and nanowire arrays are investigated by field emission scanning electron microscopy and transmission electron microscopy. Electrochemical characterization demonstrates that the MnO{sub 2} nanotube array electrode has superior capacitive behaviour to that of the MnO{sub 2} nanowire array electrode. In addition to high specific capacitance, the MnO{sub 2} nanotube array electrode also exhibits good rate capability and good cycling stability, which makes it promising candidate for supercapacitors. (author)

  16. Mathematical modeling of interdigitated electrode arrays in finite electrochemical cells

    CERN Document Server

    Guajardo, Cristian; Surareungchai, Werasak

    2016-01-01

    Accurate theoretical results for interdigitated array of electrodes (IDAE) in semi-infinite cells can be found in the literature. However, these results are not always applicable when using finite cells. In this study, theoretical expressions for IDAE in a finite geometry cell are presented. At known current density, transient and steady state concentration profiles were obtained as well as the response time to a current step. Concerning the diffusion limited current, a lower bound was derived from the concentration profile and an upper bound was obtained from the limiting current of the semi-infinite case. The lower bound, which is valid when Kirchhoff's current law applies to the unit cell, can be useful to ensure a minimum current level during the design of the electrochemical cell. Finally, a criterion was developed defining when the behaviors of finite and semi-infinite cells are comparable. This allows to obtain higher current levels in finite cells, approaching that of the semi-infinite case. Examples ...

  17. Nanocavity crossbar arrays for parallel electrochemical sensing on a chip

    Directory of Open Access Journals (Sweden)

    Enno Kätelhön

    2014-07-01

    Full Text Available We introduce a novel device for the mapping of redox-active compounds at high spatial resolution based on a crossbar electrode architecture. The sensor array is formed by two sets of 16 parallel band electrodes that are arranged perpendicular to each other on the wafer surface. At each intersection, the crossing bars are separated by a ca. 65 nm high nanocavity, which is stabilized by the surrounding passivation layer. During operation, perpendicular bar electrodes are biased to potentials above and below the redox potential of species under investigation, thus, enabling repeated subsequent reactions at the two electrodes. By this means, a redox cycling current is formed across the gap that can be measured externally. As the nanocavity devices feature a very high current amplification in redox cycling mode, individual sensing spots can be addressed in parallel, enabling high-throughput electrochemical imaging. This paper introduces the design of the device, discusses the fabrication process and demonstrates its capabilities in sequential and parallel data acquisition mode by using a hexacyanoferrate probe.

  18. Electrochemical Patterning and Detection of DNA Arrays on a Two-Electrode Platform

    OpenAIRE

    Furst, Ariel; Landefeld, Sally; Hill, Michael G.; Barton, Jacqueline K.

    2013-01-01

    We report a novel method of DNA array formation that is electrochemically formed and addressed with a two-electrode platform. Electrochemical activation of a copper catalyst, patterned with one electrode, enables precise placement of multiple sequences of DNA onto a second electrode surface. The two-electrode patterning and detection platform allows for both spatial resolution of the patterned DNA array and optimization of detection through DNA-mediated charge transport with electrocatalysis....

  19. Functionalized polypyrrole nanotube arrays as electrochemical biosensor for the determination of copper ions

    International Nuclear Information System (INIS)

    Highlights: ► PPy nanotube arrays were electropolymerized using ZnO nanowire arrays as templates. ► PPy nanotube arrays were anchored onto ITO glass without any chemical linker. ► Using SWV, the biosensor was found to be highly sensitive and selective to Cu2+. ► The biosensor was successfully applied for the determination of Cu2+ in drinking water. - Abstract: A novel electrochemical biosensor based on functionalized polypyrrole (PPy) nanotube arrays modified with a tripeptide (Gly-Gly-His) proved to be highly effective for electrochemical analysis of copper ions (Cu2+). The vertically oriented PPy nanotube arrays were electropolymerized by using modified zinc oxide (ZnO) nanowire arrays as templates which were electrodeposited on indium–tin oxide (ITO) coated glass substrates. The electrodes were functionalized by appending pyrrole-α-carboxylic acid onto the surface of polypyrrole nanotube arrays by electrochemical polymerization. The carboxylic groups of the polymer were covalently coupled with the amine groups of the tripeptide, and its structural features were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy. The tripeptide modified PPy nanotube arrays electrode was used for the electrochemical analysis of various trace copper ions by square wave voltammetry. The electrode was found to be highly sensitive and selective to Cu2+ in the range of 0.1–30 μM. Furthermore, the developed biosensor exhibited a high stability and reproducibility, despite the repeated use of the biosensor electrode.

  20. Effect of doping level of colored TiO2 nanotube arrays fabricated by electrochemical self-doping on electrochemical properties.

    Science.gov (United States)

    Kim, Choonsoo; Kim, Seonghwan; Hong, Sung Pil; Lee, Jaehan; Yoon, Jeyong

    2016-06-01

    Recently, two types of TiO2 nanotube arrays (NTAs) (blue- and black-colored TiO2 NTAs), which are easily fabricated by electrochemical self-doping, have gained much attention due particularly to their enhanced capacitive and oxidant-generating properties. These enhanced electrochemical properties mean that they have potential as basic materials for energy and environmental applications, such as in supercapacitors and anodes for water treatment. However, the understanding of the effect of the doping level of these TiO2 NTAs on their electrochemical properties is limited because there is no direct comparison or relevant discussion of their respective electrochemical properties under the same conditions, despite the similar surface characteristics of the TiO2 NTAs obtained by comparable electrochemical doping. Therefore, the objective of this study was to investigate the effect of the doping level of blue and black TiO2 NTAs on their electrochemical properties, including the capacitive and oxidant-generating properties. Although no significant difference in their surface properties was found using SEM, XRD and XPS, the black TiO2 NTA revealed a slightly higher doping level than the blue TiO2 NTA, which is caused by the order of the electrochemical self-doping and annealing conditions. With the different doping levels of the two TiO2 NTAs, the black TiO2 NTA showed a higher areal capacitance, indicating good capacitive properties, and better service life in oxidant-generation than that of the blue TiO2 NTA. The blue TiO2 NTA exhibited a larger oxygen evolution overpotential and higher chlorine evolution efficiency than that of the black TiO2 NTA. We report that the new knowledge on blue and black TiO2 NTAs from this study can contribute to the further development of supercapacitors and oxidant-generating anodes for water treatment. PMID:27169417

  1. Effect of doping level of colored TiO2 nanotube arrays fabricated by electrochemical self-doping on electrochemical properties.

    Science.gov (United States)

    Kim, Choonsoo; Kim, Seonghwan; Hong, Sung Pil; Lee, Jaehan; Yoon, Jeyong

    2016-06-01

    Recently, two types of TiO2 nanotube arrays (NTAs) (blue- and black-colored TiO2 NTAs), which are easily fabricated by electrochemical self-doping, have gained much attention due particularly to their enhanced capacitive and oxidant-generating properties. These enhanced electrochemical properties mean that they have potential as basic materials for energy and environmental applications, such as in supercapacitors and anodes for water treatment. However, the understanding of the effect of the doping level of these TiO2 NTAs on their electrochemical properties is limited because there is no direct comparison or relevant discussion of their respective electrochemical properties under the same conditions, despite the similar surface characteristics of the TiO2 NTAs obtained by comparable electrochemical doping. Therefore, the objective of this study was to investigate the effect of the doping level of blue and black TiO2 NTAs on their electrochemical properties, including the capacitive and oxidant-generating properties. Although no significant difference in their surface properties was found using SEM, XRD and XPS, the black TiO2 NTA revealed a slightly higher doping level than the blue TiO2 NTA, which is caused by the order of the electrochemical self-doping and annealing conditions. With the different doping levels of the two TiO2 NTAs, the black TiO2 NTA showed a higher areal capacitance, indicating good capacitive properties, and better service life in oxidant-generation than that of the blue TiO2 NTA. The blue TiO2 NTA exhibited a larger oxygen evolution overpotential and higher chlorine evolution efficiency than that of the black TiO2 NTA. We report that the new knowledge on blue and black TiO2 NTAs from this study can contribute to the further development of supercapacitors and oxidant-generating anodes for water treatment.

  2. Revealing structural effects: electrochemical reactions of butanols on platinum.

    Science.gov (United States)

    Rodríguez, José L; Souto, Ricardo M; Fernández-Mérida, Luis; Pastor, Elena

    2002-05-01

    Spectroelectrochemical studies on the reactivity of butanol isomers on Pt electrodes in perchloric acid medium led to the observation of structural effects that result from the different arrangements of atoms in the organic molecules. The use of differential electrochemical mass spectrometry (DEMS) to detect volatile products showed that all four isomers react on the electrode, though different product yields were observed for each compound. In spite of the differences in the electrochemical behaviour of the butanol isomers, a series of general processes accounts for the results obtained. The formation of strongly adsorbed residues by a dehydration process leading to the formation of a C=C bond was proposed for all isomers. Electroreduction of the adsorbates produces C(4) and C(3) alkanes, and the latter reveal the existence of a fragmentation process. The C(4) hydrocarbons can be formed by hydrogenation of these residues and by hydrogenolysis of alcohol molecules in the bulk solution which react at the electrode with adsorbed hydrogen. On the other hand, CO(2) is formed during electrooxidation of the adsorbed species. Partial-oxidation products containing a carbonyl group were detected from 0.2 M solutions of 1-butanol, isobutyl alcohol and sec-butyl alcohol. The tertiary alcohol tert-butyl alcohol only reacts in its adsorbed state.

  3. Preparation of Electrode Array by Electrochemical Etching Based on FEM

    Institute of Scientific and Technical Information of China (English)

    Minghuan WANG; Di ZHU; Lei WANG

    2008-01-01

    Process technology of multiple cylindrical micro-pins by wire-electrical discharge machining (wire-EDM) and electrochemical etching was presented.A row of rectangular micro-columns were machined by wire-EDM and then machined into cylindrical shape by electrochemical etching.However,the shape of the multiple electrodes and the consistent sizes of the electrodes row are not easy to be controlled.In the electrochemical process,the shape of the cathode electrode determines the current density distribution on the anode and so the forming of multiple electrodes.This paper proposes a finite element method (FEM) to accurately optimize the electrode profile.The microelectrodes row with uniformity diameters with size from hundreds micrometers to several decades could be fabricated,and mathematical model controlling the shape and diameter of multiple microelectrodes was provided.Furthermore,a good agreement between experimental and theoretical results was confirmed.

  4. Electrochemical Deposition and Properties of ZnTe Nanowire Array

    Institute of Scientific and Technical Information of China (English)

    YANG You-Wen; LI Liang; YE Min; WU Yu-Cheng; XIE Ting; LI Guang-Hai

    2007-01-01

    Pulsed electrodeposited technique is applied to fabricate ZnTe nanowire arrays with different diameters into the anodic alumina membrane in citric acid solution. The x-ray powder diffraction, scanning electron microscopy and transmission electron microscopy indicate that the high ordered, uniform and single-crystalline nanowires have been fabricated. The optical absorption spectra of the nanowire array show that the optical absorption band edge of the ZnTe nanowire array exhibit a blue shift compared with that of bulk ZnTe, and the nonlinear current-voltage characteristic is observed.

  5. Functionalized polypyrrole nanotube arrays as electrochemical biosensor for the determination of copper ions

    Energy Technology Data Exchange (ETDEWEB)

    Lin Meng; Hu Xiaoke [Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai 264003 (China); Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes, YICCAS, Yantai 264003 (China); Ma Zhaohu [Marine Environmental Monitoring and Forecasting Center of Yantai, Yantai 264003 (China); Chen Lingxin, E-mail: lxchen@yic.ac.cn [Key Laboratory of Coastal Zone Environmental Processes, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Yantai 264003 (China); Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes, YICCAS, Yantai 264003 (China)

    2012-10-09

    Highlights: Black-Right-Pointing-Pointer PPy nanotube arrays were electropolymerized using ZnO nanowire arrays as templates. Black-Right-Pointing-Pointer PPy nanotube arrays were anchored onto ITO glass without any chemical linker. Black-Right-Pointing-Pointer Using SWV, the biosensor was found to be highly sensitive and selective to Cu{sup 2+}. Black-Right-Pointing-Pointer The biosensor was successfully applied for the determination of Cu{sup 2+} in drinking water. - Abstract: A novel electrochemical biosensor based on functionalized polypyrrole (PPy) nanotube arrays modified with a tripeptide (Gly-Gly-His) proved to be highly effective for electrochemical analysis of copper ions (Cu{sup 2+}). The vertically oriented PPy nanotube arrays were electropolymerized by using modified zinc oxide (ZnO) nanowire arrays as templates which were electrodeposited on indium-tin oxide (ITO) coated glass substrates. The electrodes were functionalized by appending pyrrole-{alpha}-carboxylic acid onto the surface of polypyrrole nanotube arrays by electrochemical polymerization. The carboxylic groups of the polymer were covalently coupled with the amine groups of the tripeptide, and its structural features were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy. The tripeptide modified PPy nanotube arrays electrode was used for the electrochemical analysis of various trace copper ions by square wave voltammetry. The electrode was found to be highly sensitive and selective to Cu{sup 2+} in the range of 0.1-30 {mu}M. Furthermore, the developed biosensor exhibited a high stability and reproducibility, despite the repeated use of the biosensor electrode.

  6. Electrochemical fabrication of CdS/Co nanowire arrays in porous aluminum oxide templates

    CERN Document Server

    Yoon, C H

    2002-01-01

    A procedure for preparing semiconductor/metal nanowire arrays is described, based on a template method which entails electrochemical deposition into nanometer-wide parallel pores of anodic aluminum oxide films on aluminum. Aligned CdS/Co heterostructured nanowires have been prepared by ac electrodeposition in the anodic aluminum oxide templates. By varying the preparation conditions, a variety of CdS/Co nanowire arrays were fabricated, whose dimensional properties could be adjusted.

  7. Tubular array, dielectric, conductivity and electrochemical properties of biodegradable gel polymer electrolyte

    International Nuclear Information System (INIS)

    Highlights: • A new finding of tubular array of 10–20 μm in length and 1–2 μm in thickness of gel polymer electrolyte (GPE) having 2.2 × 10−3 S cm−1 conductivity is reported. • Thermal and electrochemical characterizations of GPEs show good interaction among the polymer, plasticizer and salt. • GPE based supercapacitor demonstrates high capacitance of 186 F g−1. • Low temperature studies did not influence much on capacitance values obtained from AC impedance studies. • Charge–discharge exhibits high capacity with excellent cyclic stability and energy density. -- Abstract: A supercapacitor based on a biodegradable gel polymer electrolyte (GPE) has been fabricated using guar gum (GG) as the polymer matrix, LiClO4 as the doping salt and glycerol as the plasticizer. The scanning electron microscopy (SEM) images of the gel polymer showed an unusual tubular array type surface morphology. FTIR, DSC and TGA results of the GPE indicated good interaction between the components used. Highest ionic conductivity and lowest activation energy values were 2.2 × 10−3 S cm−1 and 0.18 eV, respectively. Dielectric studies revealed ionic behavior and good capacitance with varying frequency of the GPE system. The fabricated supercapacitor showed a maximum specific capacitance value of 186 F g−1 using cyclic voltammetry. Variation of temperature from 273 K to 293 K did not significantly influence the capacitance values obtained from AC impedance studies. Galvanostatic charge–discharge study of supercapacitor indicated that the device has good stability, high energy density and power density

  8. Micro-drilling of polymer tubular ultramicroelectrode arrays for electrochemical sensors

    DEFF Research Database (Denmark)

    Kafka, Jan Robert; Skaarup, Steen; Geschke, Oliver;

    2013-01-01

    We present a reproducible fast prototyping procedure based on micro-drilling to produce homogeneous tubular ultramicroelectrode arrays made from poly(3,4-ethylenedioxythiophene) (PEDOT), a conductive polymer. Arrays of Ø 100 μm tubular electrodes each having a height of 0.37 ± 0.06 μm were...... reproducibly fabricated. The electrode dimensions were analyzed by SEM after deposition of silver dendrites to visualize the electroactive electrode area. The electrochemical applicability of the electrodes was demonstrated by voltammetric and amperometric detection of ferri-/ferrocyanide. Recorded signals...

  9. Electrochemical synthesis and crystal structure of ordered arrays of Со – nanotubes

    Directory of Open Access Journals (Sweden)

    Artem Kozlovskiy

    2015-09-01

    Full Text Available In this paper, using the method of electrochemical template synthesis, ordered arrays of metallic nanostructures on the basis of cobalt with various dimensions (180-380 nm were obtained. The diameter of Co-nanotubes was controlled by original polymer matrix, which provided to prepare arrays consisting of individually standing cobalt nanotubes. The crystal structure of the synthesized samples was studied by X-ray diffraction to determine cell parameters and crystallite size. Decrease of the conductive properties of Co - nanotubes can be explained by inhomogeneity of the crystallites formed during synthesis, because the growth rate of nanostructures directly affects the size of the crystallites.

  10. Electrochemical etching of sharp tips for STM reveals singularity

    DEFF Research Database (Denmark)

    Quaade, Ulrich; Oddershede, Lene

    2002-01-01

    Electrochemical etching of metal wires is widely used to produce atomically sharp tips for use in scanning tunneling microscopy (STM). In this letter we uncover the existence of a finite-time singularity in the process: Several of the physical parameters describing the system exhibit scaling...

  11. Electron transport in two-dimensional arrays of gold nanocrystals investigated by scanning electrochemical microscopy.

    Science.gov (United States)

    Liljeroth, Peter; Vanmaekelbergh, Daniël; Ruiz, Virginia; Kontturi, Kyösti; Jiang, Hua; Kauppinen, Esko; Quinn, Bernadette M

    2004-06-01

    This article reports the use of the scanning electrochemical microscope (SECM) to investigate the electronic properties of Langmuir monolayers of alkane thiol protected gold nanocrystals (NCs). A substantial increase in monolayer conductivity upon mechanical compression of the Au NC monolayer is reported for the first time. This may be the room temperature signature of the insulator to metal transition previously reported for comparable silver NC monolayers. Factors influencing the conductivity of the monolayer NC array are discussed. PMID:15174884

  12. Micro-Drilling of Polymer Tubular Ultramicroelectrode Arrays for Electrochemical Sensors

    Directory of Open Access Journals (Sweden)

    Niels B. Larsen

    2013-05-01

    Full Text Available We present a reproducible fast prototyping procedure based on micro-drilling to produce homogeneous tubular ultramicroelectrode arrays made from poly(3,4-ethylenedioxythiophene (PEDOT, a conductive polymer. Arrays of Ø 100 µm tubular electrodes each having a height of 0.37 ± 0.06 µm were reproducibly fabricated. The electrode dimensions were analyzed by SEM after deposition of silver dendrites to visualize the electroactive electrode area. The electrochemical applicability of the electrodes was demonstrated by voltammetric and amperometric detection of ferri-/ferrocyanide. Recorded signals were in agreement with results from finite element modelling of the system. The tubular PEDOT ultramicroelectrode arrays were modified by prussian blue to enable the detection of hydrogen peroxide. A linear sensor response was demonstrated for hydrogen peroxide concentrations from 0.1 mM to 1 mM.

  13. Micro-drilling of polymer tubular ultramicroelectrode arrays for electrochemical sensors.

    Science.gov (United States)

    Kafka, Jan; Skaarup, Steen; Geschke, Oliver; Larsen, Niels B

    2013-05-14

    We present a reproducible fast prototyping procedure based on micro-drilling to produce homogeneous tubular ultramicroelectrode arrays made from poly(3,4-ethylenedioxythiophene) (PEDOT), a conductive polymer. Arrays of Ø 100 µm tubular electrodes each having a height of 0.37 ± 0.06 µm were reproducibly fabricated. The electrode dimensions were analyzed by SEM after deposition of silver dendrites to visualize the electroactive electrode area. The electrochemical applicability of the electrodes was demonstrated by voltammetric and amperometric detection of ferri-/ferrocyanide. Recorded signals were in agreement with results from finite element modelling of the system. The tubular PEDOT ultramicroelectrode arrays were modified by prussian blue to enable the detection of hydrogen peroxide. A linear sensor response was demonstrated for hydrogen peroxide concentrations from 0.1 mM to 1 mM.

  14. Nanoscale Electrochemical Sensor Arrays: Redox Cycling Amplification in Dual-Electrode Systems.

    Science.gov (United States)

    Wolfrum, Bernhard; Kätelhön, Enno; Yakushenko, Alexey; Krause, Kay J; Adly, Nouran; Hüske, Martin; Rinklin, Philipp

    2016-09-20

    Micro- and nanofabriation technologies have a tremendous potential for the development of powerful sensor array platforms for electrochemical detection. The ability to integrate electrochemical sensor arrays with microfluidic devices nowadays provides possibilities for advanced lab-on-a-chip technology for the detection or quantification of multiple targets in a high-throughput approach. In particular, this is interesting for applications outside of analytical laboratories, such as point-of-care (POC) or on-site water screening where cost, measurement time, and the size of individual sensor devices are important factors to be considered. In addition, electrochemical sensor arrays can monitor biological processes in emerging cell-analysis platforms. Here, recent progress in the design of disease model systems and organ-on-a-chip technologies still needs to be matched by appropriate functionalities for application of external stimuli and read-out of cellular activity in long-term experiments. Preferably, data can be gathered not only at a singular location but at different spatial scales across a whole cell network, calling for new sensor array technologies. In this Account, we describe the evolution of chip-based nanoscale electrochemical sensor arrays, which have been developed and investigated in our group. Focusing on design and fabrication strategies that facilitate applications for the investigation of cellular networks, we emphasize the sensing of redox-active neurotransmitters on a chip. To this end, we address the impact of the device architecture on sensitivity, selectivity as well as on spatial and temporal resolution. Specifically, we highlight recent work on redox-cycling concepts using nanocavity sensor arrays, which provide an efficient amplification strategy for spatiotemporal detection of redox-active molecules. As redox-cycling electrochemistry critically depends on the ability to miniaturize and integrate closely spaced electrode systems, the

  15. Nanoscale Electrochemical Sensor Arrays: Redox Cycling Amplification in Dual-Electrode Systems.

    Science.gov (United States)

    Wolfrum, Bernhard; Kätelhön, Enno; Yakushenko, Alexey; Krause, Kay J; Adly, Nouran; Hüske, Martin; Rinklin, Philipp

    2016-09-20

    Micro- and nanofabriation technologies have a tremendous potential for the development of powerful sensor array platforms for electrochemical detection. The ability to integrate electrochemical sensor arrays with microfluidic devices nowadays provides possibilities for advanced lab-on-a-chip technology for the detection or quantification of multiple targets in a high-throughput approach. In particular, this is interesting for applications outside of analytical laboratories, such as point-of-care (POC) or on-site water screening where cost, measurement time, and the size of individual sensor devices are important factors to be considered. In addition, electrochemical sensor arrays can monitor biological processes in emerging cell-analysis platforms. Here, recent progress in the design of disease model systems and organ-on-a-chip technologies still needs to be matched by appropriate functionalities for application of external stimuli and read-out of cellular activity in long-term experiments. Preferably, data can be gathered not only at a singular location but at different spatial scales across a whole cell network, calling for new sensor array technologies. In this Account, we describe the evolution of chip-based nanoscale electrochemical sensor arrays, which have been developed and investigated in our group. Focusing on design and fabrication strategies that facilitate applications for the investigation of cellular networks, we emphasize the sensing of redox-active neurotransmitters on a chip. To this end, we address the impact of the device architecture on sensitivity, selectivity as well as on spatial and temporal resolution. Specifically, we highlight recent work on redox-cycling concepts using nanocavity sensor arrays, which provide an efficient amplification strategy for spatiotemporal detection of redox-active molecules. As redox-cycling electrochemistry critically depends on the ability to miniaturize and integrate closely spaced electrode systems, the

  16. {116} faceted anatase single-crystalline nanosheet arrays: facile synthesis and enhanced electrochemical performances

    Science.gov (United States)

    Li, Feng; Li, Xiaoning; Peng, Ranran; Zhai, Xiaofang; Yang, Shangfeng; Fu, Zhengping; Lu, Yalin

    2014-10-01

    Single-crystalline anatase TiO2 nanosheet arrays were synthesized on a transparent conductive fluorine-doped tin oxide (FTO) substrate with a unique one-step alcohol-thermal process. The nanosheets were nearly vertically grown on the FTO substrate along their zone, and they were dominated by {116} facets. The as-fabricated {116} faceted single-crystalline anatase nanosheet arrays exhibit a much higher reduction capacity and a much better electrochemical reversibility than both {001} faceted anatase single-crystalline nanosheet arrays and P25 film. The results indicate a promising application potential for the new material in the photoelectrochemical field.Single-crystalline anatase TiO2 nanosheet arrays were synthesized on a transparent conductive fluorine-doped tin oxide (FTO) substrate with a unique one-step alcohol-thermal process. The nanosheets were nearly vertically grown on the FTO substrate along their zone, and they were dominated by {116} facets. The as-fabricated {116} faceted single-crystalline anatase nanosheet arrays exhibit a much higher reduction capacity and a much better electrochemical reversibility than both {001} faceted anatase single-crystalline nanosheet arrays and P25 film. The results indicate a promising application potential for the new material in the photoelectrochemical field. Electronic supplementary information (ESI) available: Photo of the large area STNA-116, FESEM images of STNA-001 and STNA-116 with a series of growth time, the enlarged XRD pattern, the simulated SAED pattern, the reflectance spectra, the cyclic voltammograms of P25 on the FTO substrate. See DOI: 10.1039/c4nr04248d

  17. Fabrication of micro-Ni arrays by electroless and electrochemical depositions with etched porous aluminum template

    Indian Academy of Sciences (India)

    Houfang Lu; Kangping Yan; Jixin Yan; Jianzhong Wang

    2010-10-01

    Nickel micro-arrays were fabricated by electroless and electrochemical deposition in an etched porous aluminum membrane. The aluminum membrane with metal characteristic could be fabricated from high-purity aluminium by electrochemical method. The aluminum reduced Ni2+ into Ni and the formed Ni nuclei served as the catalyst for further reduction of Ni2+ in electroless solution. With the help of the membrane, nickel micro-columns of about 1–2 m diameter were obtained. The surface-deposited nickel layer served as a substrate for the nickel micro-columns, and the resulting material possessed strong mechanical strength. Electrochemical deposition was operated without preparing a conductive layer on the template due to the conductivity of the aluminum membrane. Nickel micro-tubes with an outer diameter of about 1–2 m and a wall thickness in the order of tens of nm were obtained. The nickel micro-arrays were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS).

  18. Electrochemical biosensor for Mycobacterium tuberculosis DNA detection based on gold nanotubes array electrode platform.

    Science.gov (United States)

    Torati, Sri Ramulu; Reddy, Venu; Yoon, Seok Soo; Kim, CheolGi

    2016-04-15

    The template assisted electrochemical deposition technique was used for the synthesis of gold nanotubes array (AuNTsA). The morphological structure of the synthesized AuNTsA was observed by scanning electron microscopy and found that the individual nanotubes are around 1.5 μm in length with a diameter of 200 nm. Nanotubes are vertically aligned to the Au thick film, which is formed during the synthesis process of nanotubes. The electrochemical performance of the AuNTsA was compared with the bare Au electrode and found that AuNTsA has better electron transfer surface than bare Au electrode which is due to the high surface area. Hence, the AuNTsA was used as an electrode for the fabrication of DNA hybridization biosensor for detection of Mycobacterium Tuberculosis DNA. The DNA hybridization biosensor constructed by AuNTsA electrode was characterized by cyclic voltammetry technique with Fe(CN)6(3-/4-) as an electrochemical redox indicator. The selectivity of the fabricated biosensor was illustrated by hybridization with complementary DNA and non-complementary DNA with probe DNA immobilized AuNTsA electrode using methylene blue as a hybridization indicator. The developed electrochemical DNA biosensor shows good linear range of complementary DNA concentration from 0.01 ng/μL to 100 ng/μL with high detection limit.

  19. Fabrication of microlens array on silicon surface using electrochemical wet stamping technique

    Science.gov (United States)

    Lai, Lei-Jie; Zhou, Hang; Zhu, Li-Min

    2016-02-01

    This paper focuses on the fabrication of microlens array (MLA) on silicon surface by taking advantage of a novel micromachining approach, the electrochemical we stamping (E-WETS). The E-WETS allows the direct imprinting of MLA on an agarose stamp into the substrate through a selective anodic dissolution process. The pre-patterned agarose stamp can direct and supply the solution preferentially on the contact area between the agarose stamp and the substrate, to which the electrochemical reaction is confined. The anodic potential vs. saturated calomel electrode is optimized and 1.5 V is chosen as the optimum value for the electrochemical polishing of p-Si. A refractive MLA on a PMMA mold is successfully transferred onto the p-Si surface. The machining deviations of the fabricated MLA from those on the mold are 0.44% in diameter and 2.1% in height respectively, and the machining rate in HF is around 1.1 μm/h. The surface roughness of the fabricated MLA is less than 12 nm owing to the electrochemical polishing process. The results demonstrate that E-WETS is a promising approach to fabricate MLA on p-Si surface with high accuracy and efficiency.

  20. Label-free electrochemical impedance detection of kinase and phosphatase activities using carbon nanofiber nanoelectrode arrays

    Science.gov (United States)

    Li, Yifen; Syed, Lateef; Liu, Jianwei; Hua, Duy H.; Li, Jun

    2012-01-01

    We demonstrate the feasibility of a label-free electrochemical method to detect the kinetics of phosphorylation and dephosphorylation of surface-attached peptides catalyzed by kinase and phosphatase, respectively. The peptides with a sequence specific to c-Src tyrosine kinase and protein tyrosine phosphatase 1B (PTP1B) were first validated with ELISA-based protein tyrosine kinase assay and then functionalized on vertically aligned carbon nanofiber (VACNF) nanoelectrode arrays (NEAs). Real-time electrochemical impedance spectroscopy (REIS) measurements showed reversible impedance changes upon the addition of c-Src kinase and PTP1B phosphatase. Only a small and unreliable impedance variation was observed during the peptide phosphorylation, but a large and fast impedance decrease was observed during the peptide dephosphorylation at different PTP1B concentrations. The REIS data of dephosphorylation displayed a well-defined exponential decay following the Michaelis-Menten heterogeneous enzymatic model with a specific constant, kcat/Km, of (2.1 ± 0.1) × 107 M−1 s−1. Consistent values of the specific constant was measured at PTP1B concentration varying from 1.2 to 2.4 nM with the corresponding electrochemical signal decay constant varying from 38.5 to 19.1 s. This electrochemical method can be potentially used as a label-free method for profiling enzyme activities in fast reactions. PMID:22935373

  1. Electrochemical fabrication and electrocatalytic characteristics studies of gold nanopillar array electrode (AuNPE) for development of a novel electrochemical sensor

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Chunmee; Hong, Hun-Gi [Seoul National University, Seoul (Korea). Department of Chemistry Education; Shin, Woonsup [Sogang University, Seoul (Korea). Department of Chemistry and Interdisciplinary Program of Integrated Biotechnology

    2007-12-01

    Gold nanopillar array electrodes were prepared by electrochemical deposition of gold into the nanopores of anodic aluminum oxide membrane placed onto the gold thin film electrode surface, which was in advance modified with cysteamine self-assembled monolayer as an anchoring layer. The Au nanopillar electrode is electrochemically stable and consists of highly dense, upstanding pillars assembled on the cysteamine monolayer. The structural morphology and chemical composition of the nanoarray electrode was characterized by field emission scanning electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Electrochemical measurements indicate that the Au nanopillar electrode possesses high electrocatalytic activities in the reduction of hydrogen peroxide and molecular oxygen, especially in glucose oxidation due to its higher electroactive surface area. The electro-oxidation studies of several electroactive neurotransmitters demonstrate that the nanopillar electrode can be utilized as a promising material for the construction of novel electrochemical sensor. (author)

  2. Tricobalt tetroxide nanoplate arrays on flexible conductive fabric substrate: Facile synthesis and application for electrochemical supercapacitors

    Science.gov (United States)

    Nagaraju, Goli; Ko, Yeong Hwan; Yu, Jae Su

    2015-06-01

    Tricobalt tetroxide (Co3O4) nanoplate arrays (NPAs) were synthesized on flexible conductive fabric substrate (FCFs) by a facile two-electrode system based electrochemical deposition method, followed by a simple heat treatment process. Initially, cobalt hydroxide (Co(OH)2) NPAs were electrochemically deposited on FCFs by applying an external voltage of -1.5 V for 30 min. Then, the Co3O4 NPAs on FCFs was obtained by thermal treatment of as-deposited Co(OH)2 NPAs on FCFs at 200 °C for 2 h. From the analysis of morphological and crystal properties, the Co3O4 NPAs were well integrated and uniformly covered over the entire surface of substrate with good crystallinity in the cubic phase. Additionally, the fabricated sample was directly used as a binder-free electrode to examine the feasibility for electrochemical supercapacitors using cyclic voltammetry and galvanic charge-discharge measurements in 1 M KOH electrolyte solution. The Co3O4 NPAs coated FCFs electrode exhibited a maximum specific capacitance of 145.6 F/g at a current density of 1 A/g and an excellent rate capability after 1000 cycles at a current density of 3 A/g. This facile fabrication method for integrating the Co3O4 nanostructures on FCFs could be a promising approach for advanced flexible electronic and energy-storage device applications.

  3. Micron dimensioned cavity array supported lipid bilayers for the electrochemical investigation of ionophore activity.

    Science.gov (United States)

    Maher, Sean; Basit, Hajra; Forster, Robert J; Keyes, Tia E

    2016-12-01

    Microcavity supported lipid bilayers, MSLBs, were applied to an electrochemical investigation of ionophore mediated ion transport. The arrays comprise of a 1cm(2) gold electrode imprinted with an ordered array of uniform spherical-cap pores of 2.8μm diameter prepared by gold electrodeposition through polystyrene templating spheres. The pores were pre-filled with aqueous buffer prior to Langmuir-Blodgett assembly of a 1,2-dioleoyl-sn-glycero-3-phosphocholine bilayer. Fluorescence lifetime correlation spectroscopy enabled by the micron dimensions of the pores permitted study of lipid diffusion across single apertures, yielding a diffusion coefficient of 12.58±1.28μm(2)s(-1) and anomalous exponent of 1.03±0.02, consistent with Brownian motion. From FLCS, the MSLBs were stable over 3days and electrochemical impedance spectroscopy of the membrane with and without ionic gradient over experimental windows of 6h showed excellent stability. Two ionophores were studied at the MSLBs; Valinomycin, a K(+) uniporter and Nigericin, a K(+)/H(+) antiporter. Ionophore reconstituted into the DOPC bilayer resulted in a decrease and increase in membrane resistance and capacitance respectively. Significant increases in Valinomycin and Nigericin activity were observed, reflected in large decreases in membrane resistance when K(+) was present in the contacting buffer and in the presence of H(+) ionic gradient across the membrane respectively. PMID:27420132

  4. Micron dimensioned cavity array supported lipid bilayers for the electrochemical investigation of ionophore activity.

    Science.gov (United States)

    Maher, Sean; Basit, Hajra; Forster, Robert J; Keyes, Tia E

    2016-12-01

    Microcavity supported lipid bilayers, MSLBs, were applied to an electrochemical investigation of ionophore mediated ion transport. The arrays comprise of a 1cm(2) gold electrode imprinted with an ordered array of uniform spherical-cap pores of 2.8μm diameter prepared by gold electrodeposition through polystyrene templating spheres. The pores were pre-filled with aqueous buffer prior to Langmuir-Blodgett assembly of a 1,2-dioleoyl-sn-glycero-3-phosphocholine bilayer. Fluorescence lifetime correlation spectroscopy enabled by the micron dimensions of the pores permitted study of lipid diffusion across single apertures, yielding a diffusion coefficient of 12.58±1.28μm(2)s(-1) and anomalous exponent of 1.03±0.02, consistent with Brownian motion. From FLCS, the MSLBs were stable over 3days and electrochemical impedance spectroscopy of the membrane with and without ionic gradient over experimental windows of 6h showed excellent stability. Two ionophores were studied at the MSLBs; Valinomycin, a K(+) uniporter and Nigericin, a K(+)/H(+) antiporter. Ionophore reconstituted into the DOPC bilayer resulted in a decrease and increase in membrane resistance and capacitance respectively. Significant increases in Valinomycin and Nigericin activity were observed, reflected in large decreases in membrane resistance when K(+) was present in the contacting buffer and in the presence of H(+) ionic gradient across the membrane respectively.

  5. Electrochemical oxidation of lignin at lead dioxide nanoparticles photoelectrodeposited on TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    Highlights: ► Fabrication of TiO2 nanotube arrays. ► Photoelectrochemical deposition of PbO2 nanoparticles. ► Electrochemical oxidation of lignin at the TiO2-supported PbO2 nanoparticles to value-added products. - Abstract: In this study, we have successfully fabricated lead dioxide (PbO2) nanoparticles supported on TiO2 nanotubes (TiO2NT/PbO2) for the treatment of kraft lignin. The TiO2 nanotubes were grown directly on Ti substrates by electrochemical anodization and the PbO2 nanoparticles were formed by the combination of photochemical and electrochemical deposition. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) were employed to study the surface morphology and composition of the fabricated Ti/TiO2NT/PbO2 electrodes. The resulting electrode was utilized as a novel approach for the oxidation and modification of lignin. UV–vis spectroscopy was employed to monitor the lignin oxidation process in situ. The effects of concentration, current and temperature on the oxidation of lignin have been investigated, as well as post-oxidation changes in the chemical oxygen demand (COD) of the lignin solution. Fourier transform Infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC) were used to characterize the oxidized lignin as well as the resulting products. Our study shows that the electrochemical oxidation of lignin via the fabricated Ti/TiO2NT/PbO2 electrode is a promising approach for the remediation of lignin wastewater and the generation of lignin-derived value-added products.

  6. Nanoscale electrochemical patterning reveals the active sites for catechol oxidation at graphite surfaces.

    Science.gov (United States)

    Patel, Anisha N; McKelvey, Kim; Unwin, Patrick R

    2012-12-19

    Graphite-based electrodes (graphite, graphene, and nanotubes) are used widely in electrochemistry, and there is a long-standing view that graphite step edges are needed to catalyze many reactions, with the basal surface considered to be inert. In the present work, this model was tested directly for the first time using scanning electrochemical cell microscopy reactive patterning and shown to be incorrect. For the electro-oxidation of dopamine as a model process, the reaction rate was measured at high spatial resolution across a surface of highly oriented pyrolytic graphite. Oxidation products left behind in a pattern defined by the scanned electrochemical cell served as surface-site markers, allowing the electrochemical activity to be correlated directly with the graphite structure on the nanoscale. This process produced tens of thousands of electrochemical measurements at different locations across the basal surface, unambiguously revealing it to be highly electrochemically active, with step edges providing no enhanced activity. This new model of graphite electrodes has significant implications for the design of carbon-based biosensors, and the results are additionally important for understanding electrochemical processes on related sp(2)-hybridized materials such as pristine graphene and nanotubes.

  7. Fabrication of Self-Standing Silver Nanoplate Arrays by Seed-Decorated Electrochemical Route and Their Structure-Induced Properties

    Directory of Open Access Journals (Sweden)

    Guangqiang Liu

    2013-01-01

    Full Text Available We present an electrochemical route to synthesize silver nanoplates on seed-decorated Indium tin oxide (ITO glass substrate. The nanoplates are several tens of to several hundred nanometers in dimension. The density of nanoplates covered on the substrate can be controlled well by adjusting the amounts of seed. All the nanoplates are standing on the substrate uniformly even at very high density. Silver nanoplate arrays displayed an extraordinary superhydrophobicity after chemical modification and can serve as highly active surface-enhanced Raman scattering (SERS substrates for microdetection. The arrays can also be used as electrodes for electrochemical capacitor with high power density.

  8. Reduction Mechanism and Capacitive Properties of Highly Electrochemically Reduced TiO2 Nanotube Arrays

    International Nuclear Information System (INIS)

    Highlights: • Highly reduced and ordered TiO2 nanotube arrays have been fabricated using two-step anodization and three-electrode reduction. • The reduced TiO2 nanotube arrays show a high specific capacitance of 24.07 mF cm-2 at a scan rate of 10 mV s-1, which is 1094 times higher than the capacitance of pristine nanotube arrays (0.02 mF cm-2). • They also show an excellent long-term cycling stability with only 1.9% reduction of capacitance after 2000 cycles. • Under optimized reduction conditions, about 22% of Ti4+ ions in tube surface regions are converted into Ti3+ ions. • A proton-electron coupled reduction mechanism has been proposed based on the combined paradigms of a conventional energy-band model and chemical evolution of basic building blocks of TiO2. - Abstract: Highly reduced and ordered TiO2 nanotube arrays have been fabricated using two-step anodization and three-electrode reduction. A proton-electron coupled reduction mechanism has been proposed based on the combined paradigms of a conventional energy-band model and chemical evolution of basic building blocks of TiO2. Under optimized reduction conditions, about 22% of Ti4+ ions in tube surface regions are converted into Ti3+ ions while the morphology of the highly reduced TiO2 nanotube arrays keeps unchanged. The reduced nanotube arrays show superior electrochemical properties such as high areal capacitance, good rate capability, and high cycling stability. The areal capacitance of the reduced electrode is 24.07 mF cm−2 at a scan rate of 10 mV s−1, much higher than that of the pristine TiO2 nanotube arrays (0.02 mF cm−2). This kind of highly reduced one-dimensional oxide nanostructures can find a large array of applications in supercapacitors, photocatalysis, electrochromic display, and Li ion batteries

  9. Fabrication and electrochemical properties of carbon nanotube array electrode for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Qiao Ling Chen; Kuan Hong Xue; Wei Shen; Fei Fei Tao; Shou Yin Yin; Wen Xu [Nanjing Normal University (China). Chemistry Dept.

    2004-09-30

    The multiwalled carbon nanotube (MWNT) array was fabricated by chemical vapor deposition (CVD) in the template of porous alumina from the carbonaceous source of C{sub 2H}2 in the presence of a catalyst of ferric metals. To utilize the external surface other than the inner surface of the carbon nanotubes, 1 mol/L sulfuric acid was applied to remove off the most part of AAO template on the carbon nanotube electrode. The electrochemical performances of the carbon nanotube array electrode were investigated by use of the cyclic voltammetry, galvanostatic charge/discharge and ac impedance methods for its application in supercapacitors. The specific capacitance of 365 F/g of the electrode was achieved with the discharge current density of 210 mA/g in the solution of 1 mol/L H{sub 2}SO{sub 4}. In addition, the carbon nanotube array electrode was found to have low equivalent series resistance (ESR) and good cycling stability. (author)

  10. Electrostatic mechanism of nucleosomal array folding revealed by computer simulation

    OpenAIRE

    Sun, Jian; Zhang, Qing; Schlick, Tamar

    2005-01-01

    Although numerous experiments indicate that the chromatin fiber displays salt-dependent conformations, the associated molecular mechanism remains unclear. Here, we apply an irregular Discrete Surface Charge Optimization (DiSCO) model of the nucleosome with all histone tails incorporated to describe by Monte Carlo simulations salt-dependent rearrangements of a nucleosomal array with 12 nucleosomes. The ensemble of nucleosomal array conformations display salt-dependent condensation in good agre...

  11. Graphitic carbon nitride (g-C3N4) coated titanium oxide nanotube arrays with enhanced photo-electrochemical performance.

    Science.gov (United States)

    Sun, Mingxuan; Fang, Yalin; Kong, Yuanyuan; Sun, Shanfu; Yu, Zhishui; Umar, Ahmad

    2016-08-01

    Herein, we report the successful formation of graphitic carbon nitride coated titanium oxide nanotube array thin films (g-C3N4/TiO2) via the facile thermal treatment of anodized Ti sheets over melamine. The proportion of C3N4 and TiO2 in the composite can be adjusted by changing the initial addition mass of melamine. The as-prepared samples are characterized by several techniques in order to understand the morphological, structural, compositional and optical properties. UV-vis absorption studies exhibit a remarkable red shift for the g-C3N4/TiO2 thin films as compared to the pristine TiO2 nanotubes. Importantly, the prepared composites exhibit an enhanced photocurrent and photo-potential under both UV-vis and visible light irradiation. Moreover, the observed maximum photo-conversion efficiency of the prepared composites is 1.59 times higher than that of the pristine TiO2 nanotubes. The optical and electrochemical impedance spectra analysis reveals that the better photo-electrochemical performance of the g-C3N4/TiO2 nanotubes is mainly due to the wider light absorption and reduced impedance compared to the bare TiO2 nanotube electrode. The presented work demonstrates a facile and simple method to fabricate g-C3N4/TiO2 nanotubes and clearly revealed that the introduction of g-C3N4 is a new and innovative approach to improve the photocurrent and photo-potential efficiencies of TiO2.

  12. Non-invasive monitoring of osteogenic differentiation on microtissue arrays under physiological conditions using scanning electrochemical microscopy

    NARCIS (Netherlands)

    Sridhar, Adithya; Berg, van den Albert; Le Gac, Séverine

    2014-01-01

    In this paper, we present a non-invasive assay using scanning electrochemical microscopy (SECM) for detecting osteogenic differentiation at physiological conditions (pH 7.5) on arrays of C2C12 microtissues. Upon exposure to bone morphogenic protein 2 (BMP-2), C2C12 microtissues differentiate and exp

  13. Nanoscaled redox active protein adsorption on Au-dot arrays: An electrochemical scanning probe microscopic investigation for application in nano-biodevices

    Energy Technology Data Exchange (ETDEWEB)

    Yagati, Ajay Kumar; Jung, Mi; Kim, Sang-Uk [Interdisciplinary Program of Integrated Biotechnology, Sogang University, 1 Shinsu-dong, Mapo-gu, Seoul 121-742 (Korea, Republic of); Min, Junhong [College of Bionanotechnology, Kyungwon University, Bokjung-dong, Sujung-gu, Seongnam 461-701 (Korea, Republic of); Choi, Jeong-Woo, E-mail: jwchoi@sogang.ac.k [Interdisciplinary Program of Integrated Biotechnology, Sogang University, 1 Shinsu-dong, Mapo-gu, Seoul 121-742 (Korea, Republic of); Department of Chemical and Biomolecular Engineering, Interdisciplinary Program of Integrated Biotechnology Sogang University, 1 Shinsu-dong, Mapo-gu, Seoul 121-742 (Korea, Republic of)

    2009-11-30

    Highly dense and uniform protein dot arrays on Au-nanodots using size controllable method were fabricated on indium tin oxide (ITO) substrate in order to develop an electrochemical nanobiochip. Cysteine modified azurin was directly immobilized on the fabricated Au-nanodots without any linker materials. Atomic force microscopy was used for characterizing Au-dots formed on ITO substrate. Electrochemical scanning tunneling microscopy (ECSTM) revealed the monolayer formation with an in situ cyclic voltammetry to observe redox behaviour of both bare Au-dots and protein immobilized Au-dots. I-V characteristics were obtained on both bare Au-dots and protein immobilized Au-dots structured on ITO conductive electrodes.

  14. Electrochemical performance and biosensor application of TiO2 nanotube arrays with mesoporous structures constructed by chemical etching.

    Science.gov (United States)

    Wang, Jinwen; Xu, Guangqing; Zhang, Xu; Lv, Jun; Zhang, Xinyi; Zheng, Zhixiang; Wu, Yucheng

    2015-04-28

    Novel mesoporous TiO2 nanotube arrays (TiO2 NTAs) were synthesized by an anodization method combined with chemical etching in HF solution, and the electrochemical performance was studied. Glucose oxidase (GOx) was immobilized on the mesoporous TiO2 NTAs to achieve an efficient biosensor for amperometric detection of glucose. The morphology, structure, component and electrochemical performance of mesoporous TiO2 NTAs were characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectrometry and an electrochemical workstation, respectively. The influence of the mesoporous structure on the electrochemical performance is discussed in detail by comparing the cyclic voltammograms and electrochemical impedance spectrum of TiO2 and mesoporous TiO2 NTAs in different conditions. High electrochemical active surface area and electron transfer rate play key roles in enhancing the electrochemical performance of mesoporous TiO2 NTAs. When used as the basis of a biosensor, the amperometric response of glucose on a GOx/TiO2-0.5 NTAs electrode is linearly proportion to the glucose concentration in the range from 0.1 to 6 mM with a sensitivity of 0.954 μA mM(-1) cm(-2), which is 14.3 times that of un-etched GOx/TiO2 NTAs. PMID:25811301

  15. Optical properties of TiO2 nanotube arrays fabricated by the electrochemical anodization method

    International Nuclear Information System (INIS)

    Perpendicularly self-aligned TiO2 nanotube samples of size of 3 × 5 cm2 were fabricated by the electrochemical anodization method using a solution containing NH4F. Influences of the technological conditions such as NH4F concentration and anodization voltage were studied. It was found that NH4F concentration in the solution and anodization voltage significantly affect the diameter and length of a TiO2 nanotube. The diameter and the length of a TiO2 nanotube were observed and estimated by using scanning electron microscopy. It has shown that the largest diameter and the longest length of about 80 nm and 20 μm, respectively, were obtained for the sample anodized in a solution containing 0.4% of NH4F, under a voltage of 48 V. Photoluminescence spectra excited by laser lights having wavelengths of 325 and 442 nm (having energies higher and lower than the band gap energy of TiO2) was recorded at room temperature for the TiO2 nanotube arrays. An abnormal luminescence result was observed. It is experimental evidence that the manufactured TiO2 nanotube array is an expected material for hydrogen splitting from water by photochemical effect under sunlight as well as for the nano solar cells. (paper)

  16. Electrochemically controlled fabrication of lightly doped porous Si nanowire arrays with excellent antireflective and self-cleaning properties

    International Nuclear Information System (INIS)

    The doping level and morphology of porous Si nanowire (SiNW) arrays are critical for their electrical, optical and surface properties, but preparation of lightly doped porous SiNW arrays with uniform length still remains a challenge. By integrating electroless chemical etching with a proposed electrochemical route, lightly doped single-crystalline porous SiNW arrays with uniform length were prepared from Si wafers with resistivity of 1–770 Ω cm for the first time. Scanning electron microscopy and transmission electron microscopy images show that the size of pores in the NWs is enlarged by increasing the duration of electrochemical process. Based on current–voltage measurements, thermionic emission is proposed to be responsible for the pore formation mechanism. The photoluminescence spectrum of the porous SiNWs shows an obvious peak centered at 680 nm, which is attributed to the quantum confinement effect due to porous structures, evidenced by the shift of Raman peak from 520.7 to 519.7 cm−1. Reflectivity spectra show the average reflectivity of SiNW arrays after electrochemical treatments was further decreased to less than 1.8% in the 350–600 nm wavelength range. Contact angle measurements show that the porous SiNW arrays possess superhydrophobic characteristics with a contact angle of up to 164°. Compared with previous studies, the proposed integrated route can not only prepare uniform, lightly doped, and porous SiNW arrays, but also provide an efficient way to independently control the lengths of NWs and sizes of nanopores in them. The SiNW arrays can be employed as an excellent antireflective and self-cleaning substrate for high efficiency opto-electronic devices.

  17. Three-dimensionally grown thorn-like Cu nanowire arrays by fully electrochemical nanoengineering for highly enhanced hydrazine oxidation

    Science.gov (United States)

    Huang, Jianfei; Zhao, Shunan; Chen, Wei; Zhou, Ying; Yang, Xiaoling; Zhu, Yihua; Li, Chunzhong

    2016-03-01

    This communication reports fully electrochemical nanoengineering toward three-dimensionally grown thorn-like Cu nanowire arrays (CNWAs) as a highly efficient and durable electrocatalyst for hydrazine oxidation. Characterized by substantial negative shifting of the onset potential and an enlarged catalytic current density, the CNWAs afforded greatly enhanced hydrazine oxidation activity, even transcending that of the Pt/C catalyst at a higher reaction rate. The parameters of the electrochemical engineering and metallization methods were found to be essentially influential on the microstructure, and thus the electrocatalytic activity of the CNWAs. The present work typifies a flexible and expandible route toward integrated electrodes of metallic 1D nanostructures which are of interest in advancing the performance of cutting-edge electrochemical applications.This communication reports fully electrochemical nanoengineering toward three-dimensionally grown thorn-like Cu nanowire arrays (CNWAs) as a highly efficient and durable electrocatalyst for hydrazine oxidation. Characterized by substantial negative shifting of the onset potential and an enlarged catalytic current density, the CNWAs afforded greatly enhanced hydrazine oxidation activity, even transcending that of the Pt/C catalyst at a higher reaction rate. The parameters of the electrochemical engineering and metallization methods were found to be essentially influential on the microstructure, and thus the electrocatalytic activity of the CNWAs. The present work typifies a flexible and expandible route toward integrated electrodes of metallic 1D nanostructures which are of interest in advancing the performance of cutting-edge electrochemical applications. Electronic supplementary information (ESI) available: Experimental details, additional figures and table. See DOI: 10.1039/c5nr06512g

  18. Structural and Electrochemical Investigation during the First Charging Cycles of Silicon Microwire Array Anodes for High Capacity Lithium Ion Batteries

    OpenAIRE

    Helmut Föll; Jürgen Carstensen; Enrique Quiroga-González

    2013-01-01

    Silicon microwire arrays embedded in Cu present exceptional performance as anode material in Li ion batteries. The processes occurring during the first charging cycles of batteries with this anode are essential for good performance. This paper sheds light on the electrochemical and structural properties of the anodes during the first charging cycles. Scanning Electron Microscopy, X-ray diffractommetry, and fast Fourier transformation impedance spectroscopy are used for the characterization. I...

  19. Electrochemical micromachining of micro-dimple arrays on cylindrical inner surfaces using a dry-film photoresist

    Institute of Scientific and Technical Information of China (English)

    Qu Ningsong; Chen Xiaolei; Li Hansong; Zeng Yongbin

    2014-01-01

    The application of surface textures has been employed to improve the tribological per-formance of various mechanical components. Various techniques have been used for the application of surface textures such as micro-dimple arrays, but the fabrication of such arrays on cylindrical inner surfaces remains a challenge. In this study, a dry-film photoresist is used as a mask during through-mask electrochemical micromachining to successfully prepare micro-dimple arrays with dimples 94 lm in diameter and 22.7 lm deep on cylindrical inner surfaces, with a machining time of 9 s and an applied voltage of 8 V. The versatility of this method is demonstrated, as are its poten-tial low cost and high efficiency. It is also shown that for a fixed dimple depth, a smaller dimple diameter can be obtained using a combination of lower current density and longer machining time in a passivating sodium nitrate electrolyte.

  20. Synthesis of Millimeter-Scale Carbon Nanotube Arrays and Their Applications on Electrochemical Supercapacitors

    Science.gov (United States)

    Cui, Xinwei

    This research is aimed at synthesizing millimeter-scale carbon nanotube arrays (CNTA) by conventional chemical vapor deposition (CCVD) and water-assisted chemical vapor deposition (WACVD) methods, and exploring their application as catalyst supports for electrochemical supercapacitors. The growth mechanism and growth kinetics of CNTA under different conditions were systematically investigated to understand the relationship among physical characteristics of catalyst particles, growth parameters, and carbon nanotube (CNT) structures within CNTAs. Multiwalled CNT (MWCNT) array growth demonstrates lengthening and thickening stages in CCVD and WACVD. In CCVD, the lengthening and thickening were found to be competitive. By investigating catalyst particles after different pretreatment conditions, it has been found that inter-particle spacing plays a significant role in influencing CNTA height, CNT diameter and wall number. In WACVD, a long linear lengthening stage has been found. CNT wall number remains constant and catalysts preserve the activity in this stage, while MWCNTs thicken substantially and catalysts deactivate following the previously proposed radioactive decay model in the thickening stage of WACVD. Water was also shown to preserve the catalyst activity by significantly inhibiting catalyst-induced and gas phase-induced thickening processes in WACVD. Mn3O4 nanoparticles were successfully deposited and uniformly distributed within millimeter-long CNTAs by dip-casting method from non-aqueous solutions. After modification with Mn3O4 nanoparticles, CNTAs have been changed from hydrophobic to hydrophilic without their alignment and integrity being destroyed. The hydrophilic Mn 3O4/CNTA composite electrodes present ideal capacitive behavior with high reversibility. This opens up a new route of utilizing ultra-long CNTAs, based on which a scalable and cost-effective method was developed to fabricate composite electrodes using millimeter-long CNTAs. To improve the

  1. NiO nanowall array prepared by a hydrothermal synthesis method and its enhanced electrochemical performance for lithium ion batteries

    International Nuclear Information System (INIS)

    Graphical abstract: Self-supported NiO nanowall array is fabricated by a facile hydrothermal synthesis method and exhibits noticeable Li ion battery performance with good cycle life and high capacity. Highlights: ► NiO nanowall array is prepared by a hydrothermal synthesis method. ► NiO nanowall array with high capacity as anode material for Li ion battery. ► Nanowall array structure is favorable for fast ion/electron transfer. - Abstract: Free-standing quasi-single-crystalline NiO nanowall array is successfully fabricated via a simple hydrothermal synthesis method. The as-prepared NiO film exhibits a highly porous nanowall structure composed of many interconnected nanoflakes with thicknesses of ∼20 nm. The NiO nanowalls arrange vertically to the substrate resulting in the formation of extended porous net-like structure with pores of 30–300 nm. As anode material for lithium ion batteries, the quasi-single-crystalline NiO nanowall array exhibits pretty good electrochemical performances with high capacity, weaker polarization, higher coulombic efficiency and better cycling performance as compared to the dense polycrystalline NiO film. The quasi-single-crystalline NiO nanowall array presents an initial coulombic efficiency of 76% and good cycling life with a capacity of 564 mAh g−1 at 0.5 A g−1 after 50 cycles, higher than that of the dense polycrystalline NiO film (358 mAh g−1). The enhanced performance is due to the unique nanowall array structure providing faster ion/electron transport and better morphological stability

  2. Controllable Synthesis of Copper Oxide/Carbon Core/Shell Nanowire Arrays and Their Application for Electrochemical Energy Storage

    Directory of Open Access Journals (Sweden)

    Jiye Zhan

    2015-10-01

    Full Text Available Rational design/fabrication of integrated porous metal oxide arrays is critical for the construction of advanced electrochemical devices. Herein, we report self-supported CuO/C core/shell nanowire arrays prepared by the combination of electro-deposition and chemical vapor deposition methods. CuO/C nanowires with diameters of ~400 nm grow quasi-vertically to the substrates forming three-dimensional arrays architecture. A thin carbon shell is uniformly coated on the CuO nanowire cores. As an anode of lithium ion batteries, the resultant CuO/C nanowire arrays are demonstrated to have high specific capacity (672 mAh·g−1 at 0.2 C and good cycle stability (425 mAh·g−1 at 1 C up to 150 cycles. The core/shell arrays structure plays positive roles in the enhancement of Li ion storage due to fast ion/electron transfer path, good strain accommodation and sufficient contact between electrolyte and active materials.

  3. Facile electrochemical synthesis of antimicrobial TiO2 nanotube arrays

    Directory of Open Access Journals (Sweden)

    Zhao Y

    2014-11-01

    Full Text Available Yu Zhao,1 Qi Xing,2 Jagadeesh Janjanam,3 Kun He,1,4 Fei Long,1 Ke-Bin Low,5 Ashutosh Tiwari,3 Feng Zhao,2 Reza Shahbazian-Yassar,1 Craig Friedrich,1,8 Tolou Shokuhfar1,6–81Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI, USA; 2Department of Biomedical Engineering, Michigan Technological University, Houghton, MI, USA; 3Department of Chemistry, Michigan Technological University, Houghton, MI, USA; 4School of Materials Science and Engineering, Shandong University, Jinan, People’s Republic of China; 5Research Resources Center, University of Illinois at Chicago, Chicago, IL, USA; 6Department of Physics, University of Illinois at Chicago, Chicago, IL, USA; 7Mechanical and Industrial Engineering Department, University of Illinois at Chicago, Chicago, IL, USA; 8Multi-Scale Technologies Institute, Michigan Technological University, Houghton, MI, USAAbstract: Infection-related complications have been a critical issue for the application of titanium orthopedic implants. The use of Ag nanoparticles offers a potential approach to incorporate antimicrobial properties into the titanium implants. In this work, a novel and simple method was developed for synthesis of Ag (II oxide deposited TiO2 nanotubes (TiNTs using electrochemical anodization followed by Ag electroplating processes in the same electrolyte. The quantities of AgO nanoparticles deposited in TiNT were controlled by selecting different electroplating times and voltages. It was shown that AgO nanoparticles were crystalline and distributed throughout the length of the nanotubes. Inductively coupled plasma mass spectrometry tests showed that the quantities of released Ag were less than 7 mg/L after 30 days at 37°C. Antimicrobial assay results show that the AgO-deposited TiNTs can effectively kill the Escherichia coli bacteria. Although the AgO-deposited TiNTs showed some cytotoxicity, it should be controllable by optimization of the

  4. Carbon nanofiber electrode array for electrochemical detection of dopamine using fast scan cyclic voltammetry

    OpenAIRE

    Koehne, Jessica E.; Marsh, Michael; Boakye, Adwoa; Douglas, Brandon; Kim, In Yong; Chang, Su-Youne; Jang, Dong-Pyo; Bennet, Kevin E.; Kimble, Christopher; Andrews, Russell; Meyyappan, M.; Lee, Kendall H.

    2011-01-01

    A carbon nanofiber (CNF) electrode array was integrated with the Wireless Instantaneous Neurotransmitter Sensor System (WINCS) for detection of dopamine using fast scan cyclic voltammetry (FSCV). Dopamine detection performance by CNF arrays was comparable to that of traditional carbon fiber microelectrodes (CFMs), demonstrating that CNF arrays can be utilized as an alternative carbon electrodes for neurochemical monitoring.

  5. Fabrication, Modification, and Emerging Applications of TiO2 Nanotube Arrays by Electrochemical Synthesis: A Review

    Directory of Open Access Journals (Sweden)

    Jian-Ying Huang

    2013-01-01

    Full Text Available Titania nanotube arrays (TNAs as a hot nanomaterial have a unique highly ordered array structure and good mechanical and chemical stability, as well as excellent anticorrosion, biocompatible, and photocatalytic performance. It has been fabricated by a facile electrochemical anodization in electrolytes containing small amounts of fluoric ions. In combination with our research work, we review the recent progress of the new research achievements of TNAs on the preparation processes, forming mechanism, and modification. In addition, we will review the potential and significant applications in the photocatalytic degradation of pollutants, solar cells, water splitting, and other aspects. Finally, the existing problems and further prospects of this renascent and rapidly developing field are also briefly addressed and discussed.

  6. Improved electrochemical performances of CuO nanotube array prepared via electrodeposition as anode for lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Anguo, E-mail: hixiaoanguo@126.com; Zhou, Shibiao; Zuo, Chenggang; Zhuan, Yongbing; Ding, Xiang

    2015-10-15

    Graphical abstract: CuO nanotube array electrodes prepared by electrodeposition method exhibit an excellent lithium ion storage ability as anode of Li-ion battery. - Highlights: • CuO nanotube arrays are synthesized by an electrodeposition method. • CuO nanotube shows a high-rate performance. • CuO nanotube shows an excellent cycling performance. - Abstract: We report a facile strategy to prepared CuO nanotube arrays directly grown on Cu plate through the electrodeposition method. The as-prepared CuO nanotubes show a quasi-cylinder nanostructure with internal diameters of ca. ∼100 nm, external diameters of ca. ∼120 nm, and average length of ∼3 μm. As an anode for lithium ion batteries, the electrochemical properties of the CuO nanotube arrays are investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. Due to the unique nanotube nanostructure, the as-prepared CuO electrodes exhibit good rate performance (550 mAh g{sup −1} at 0.1 C and 464 mAh g{sup −1} at 1 C) and cycling performance (581 mAh g{sup −1} at 0.1 C and 538 mAh g{sup −1} at 0.5 C)

  7. Electrochemical genosensor array for the simultaneous detection of multiple high-risk human papillomavirus sequences in clinical samples

    Energy Technology Data Exchange (ETDEWEB)

    Civit, Laia [Nanobiotechnology and Bioanalysis Group, Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Fragoso, Alex, E-mail: alex.fragoso@urv.cat [Nanobiotechnology and Bioanalysis Group, Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Hoelters, Sebastian; Duerst, Matthias [Department for Gynecology, Jena University Hospital, Friedrich-Schiller-University Jena, D-07743 Jena (Germany); O' Sullivan, Ciara K., E-mail: ciara.osullivan@urv.cat [Nanobiotechnology and Bioanalysis Group, Departament d' Enginyeria Quimica, Universitat Rovira i Virgili, 43007 Tarragona (Spain); Institucio Catalana de Recerca i Estudis Avancats, Passeig Lluis Companys 23, 08010 Barcelona (Spain)

    2012-02-17

    Highlights: Black-Right-Pointing-Pointer High-risk human papillomavirus is detected in virtually all-invasive cervical cancers. Black-Right-Pointing-Pointer Electrochemical genosensor for simultaneous detection of multiple high-risk HPV applied to cervical scrape samples. Black-Right-Pointing-Pointer Excellent correlation with HPV genotyping carried out within a hospital laboratory. - Abstract: An electrochemical genosensor array for the simultaneous detection of three high-risk human papillomavirus (HPV) DNA sequences, HPV16, 18 and 45, exhibiting high sensitivity and selectivity is presented. The electrodes of a 4 Multiplication-Sign 4 array were modified via co-immobilization of a 1:100 (mol/mol) mixture of a thiolated probe and an oligoethyleneglycol-terminated bipodal thiol. Detection of synthetic and PCR products was carried out in a sandwich type format, with the target hybridized between a surface immobilized probe and a horseradish peroxidase-labelled secondary reporter probe. The detection limits obtained in the detection of each individual target were in the pM range, allowing the application of this sensor for the detection of samples obtained from PCR amplification of cervical scrape samples. The results obtained exhibited an excellent correlation with the HPV genotyping carried out within a hospital laboratory. Multiplexing and cross-reactivity studies demonstrated high selectivity over potential interfering sequences, facilitating application of the developed platform for the high-throughput screening of multiple high-risk DNA sequences.

  8. Two-Point Stretchable Electrode Array for Endoluminal Electrochemical Impedance Spectroscopy Measurements of Lipid-Laden Atherosclerotic Plaques.

    Science.gov (United States)

    Packard, René R Sevag; Zhang, XiaoXiao; Luo, Yuan; Ma, Teng; Jen, Nelson; Ma, Jianguo; Demer, Linda L; Zhou, Qifa; Sayre, James W; Li, Rongsong; Tai, Yu-Chong; Hsiai, Tzung K

    2016-09-01

    Four-point electrode systems are commonly used for electric impedance measurements of biomaterials and tissues. We introduce a 2-point system to reduce electrode polarization for heterogeneous measurements of vascular wall. Presence of endoluminal oxidized low density lipoprotein (oxLDL) and lipids alters the electrochemical impedance that can be measured by electrochemical impedance spectroscopy (EIS). We developed a catheter-based 2-point micro-electrode configuration for intravascular deployment in New Zealand White rabbits. An array of 2 flexible round electrodes, 240 µm in diameter and separated by 400 µm was microfabricated and mounted on an inflatable balloon catheter for EIS measurement of the oxLDL-rich lesions developed as a result of high-fat diet-induced hyperlipidemia. Upon balloon inflation, the 2-point electrode array conformed to the arterial wall to allow deep intraplaque penetration via alternating current (AC). The frequency sweep from 10 to 300 kHz generated an increase in capacitance, providing distinct changes in both impedance (Ω) and phase (ϕ) in relation to varying degrees of intraplaque lipid burden in the aorta. Aortic endoluminal EIS measurements were compared with epicardial fat tissue and validated by intravascular ultrasound and immunohistochemistry for plaque lipids and foam cells. Thus, we demonstrate a new approach to quantify endoluminal EIS via a 2-point stretchable electrode strategy.

  9. Immobilizing Enzymes onto Electrode Arrays by Hydrogel Photolithography to Fabricate Multi-Analyte Electrochemical Biosensors

    OpenAIRE

    Yan, Jun; Pedrosa, Valber A.; Simonian, Aleksandr L.; Revzin, Alexander

    2010-01-01

    This paper describes a biomaterial microfabrication approach for interfacing functional biomolecules (enzymes) with electrode arrays. Poly (ethylene glycol) (PEG) hydrogel photopatterning was employed to integrate gold electrode arrays with enzymes - glucose oxidase (GOX) and lactate oxidase (LOX). In this process, PEG diacrylate (DA)-based prepolymer containing enzyme molecules as well as redox species (vinylferrocene) was spin-coated, registered and UV cross-linked on top of an array of gol...

  10. The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Krishna Kant

    2014-11-01

    Full Text Available The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm and lengths (5 μm to 20 μm was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores.

  11. The Influence of Nanopore Dimensions on the Electrochemical Properties of Nanopore Arrays Studied by Impedance Spectroscopy

    Science.gov (United States)

    Kant, Krishna; Priest, Craig; Shapter, Joe G.; Losic, Dusan

    2014-01-01

    The understanding of the electrochemical properties of nanopores is the key factor for better understanding their performance and applications for nanopore-based sensing devices. In this study, the influence of pore dimensions of nanoporous alumina (NPA) membranes prepared by an anodization process and their electrochemical properties as a sensing platform using impedance spectroscopy was explored. NPA with four different pore diameters (25 nm, 45 nm and 65 nm) and lengths (5 μm to 20 μm) was used and their electrochemical properties were explored using different concentration of electrolyte solution (NaCl) ranging from 1 to 100 μM. Our results show that the impedance and resistance of nanopores are influenced by the concentration and ion species of electrolytes, while the capacitance is independent of them. It was found that nanopore diameters also have a significant influence on impedance due to changes in the thickness of the double layer inside the pores. PMID:25393785

  12. A compact microelectrode array chip with multiple measuring sites for electrochemical applications

    DEFF Research Database (Denmark)

    Dimaki, Maria; Vergani, Marco; Heiskanen, Arto;

    2014-01-01

    In this paper we demonstrate the fabrication and electrochemical characterization of a microchip with 12 identical but individually addressable electrochemical measuring sites, each consisting of a set of interdigitated electrodes acting as a working electrode as well as two circular electrodes...... functioning as a counter and reference electrode in close proximity. The electrodes are made of gold on a silicon oxide substrate and are passivated by a silicon nitride membrane. A method for avoiding the creation of high edges at the electrodes (known as lift-off ears) is presented. The microchip design...

  13. Fabrication of Self-Standing Silver Nano plate Arrays by Seed-Decorated Electrochemical Route and Their Structure-Induced Properties

    International Nuclear Information System (INIS)

    We present an electrochemical route to synthesize silver nano plates on seed-decorated Indium tin oxide (ITO) glass substrate. The nano plates are several tens of to several hundred nanometers in dimension. The density of nano plates covered on the substrate can be controlled well by adjusting the amounts of seed. All the nano plates are standing on the substrate uniformly even at very high density. Silver nano plate arrays displayed an extraordinary super hydrophobicity after chemical modification and can serve as highly active surface-enhanced Raman scattering (SERS) substrates for micro detection. The arrays can also be used as electrodes for electrochemical capacitor with high power density.

  14. Fingerprinting the Asterid species using subtracted diversity array reveals novel species-specific sequences.

    Directory of Open Access Journals (Sweden)

    Nitin Mantri

    Full Text Available BACKGROUND: Asterids is one of the major plant clades comprising of many commercially important medicinal species. One of the major concerns in medicinal plant industry is adulteration/contamination resulting from misidentification of herbal plants. This study reports the construction and validation of a microarray capable of fingerprinting medicinally important species from the Asterids clade. METHODOLOGY/PRINCIPAL FINDINGS: Pooled genomic DNA of 104 non-asterid angiosperm and non-angiosperm species was subtracted from pooled genomic DNA of 67 asterid species. Subsequently, 283 subtracted DNA fragments were used to construct an Asterid-specific array. The validation of Asterid-specific array revealed a high (99.5% subtraction efficiency. Twenty-five Asterid species (mostly medicinal representing 20 families and 9 orders within the clade were hybridized onto the array to reveal its level of species discrimination. All these species could be successfully differentiated using their hybridization patterns. A number of species-specific probes were identified for commercially important species like tea, coffee, dandelion, yarrow, motherwort, Japanese honeysuckle, valerian, wild celery, and yerba mate. Thirty-seven polymorphic probes were characterized by sequencing. A large number of probes were novel species-specific probes whilst some of them were from chloroplast region including genes like atpB, rpoB, and ndh that have extensively been used for fingerprinting and phylogenetic analysis of plants. CONCLUSIONS/SIGNIFICANCE: Subtracted Diversity Array technique is highly efficient in fingerprinting species with little or no genomic information. The Asterid-specific array could fingerprint all 25 species assessed including three species that were not used in constructing the array. This study validates the use of chloroplast genes for bar-coding (fingerprinting plant species. In addition, this method allowed detection of several new loci that can be

  15. The electrochemical behavior of Cl− assisted Al3+ insertion into titanium dioxide nanotube arrays in aqueous solution for aluminum ion batteries

    International Nuclear Information System (INIS)

    The titanium dioxide nanotube array (TiO2-NTA) is prepared by a two-step anodic oxidation method and annealed at 450 ∘C subsequently. The Al-inserted TiO2-NTA is prepared by polarizing the TiO2-NTAs electrode at 0.4 mA for 2 min in 1 mol/L AlCl3. The results show that the Al-inserted sample still remains pure anatase TiO2 phase (by XRD) and keeps intact nanotube array structure (by FE-SEM). The X-ray photoelectron spectroscopy (XPS) analysis indicates that the insertion of Al3+ into TiO2-NTAs facilitates in the reduction of Ti4+ to Ti3+. Electrochemical investigation on the Al3+ insertion process reveals that presence of Cl− ions plays vital role for the effective insertion and de-insertion of Al3+ into/from the TiO2-NTA

  16. Electrochemical micromachining of micro-dimple arrays on cylindrical inner surfaces using a dry-film photoresist

    Directory of Open Access Journals (Sweden)

    Qu Ningsong

    2014-08-01

    Full Text Available The application of surface textures has been employed to improve the tribological performance of various mechanical components. Various techniques have been used for the application of surface textures such as micro-dimple arrays, but the fabrication of such arrays on cylindrical inner surfaces remains a challenge. In this study, a dry-film photoresist is used as a mask during through-mask electrochemical micromachining to successfully prepare micro-dimple arrays with dimples 94 μm in diameter and 22.7 μm deep on cylindrical inner surfaces, with a machining time of 9 s and an applied voltage of 8 V. The versatility of this method is demonstrated, as are its potential low cost and high efficiency. It is also shown that for a fixed dimple depth, a smaller dimple diameter can be obtained using a combination of lower current density and longer machining time in a passivating sodium nitrate electrolyte.

  17. A Compact Microelectrode Array Chip with Multiple Measuring Sites for Electrochemical Applications

    Directory of Open Access Journals (Sweden)

    Maria Dimaki

    2014-05-01

    Full Text Available In this paper we demonstrate the fabrication and electrochemical characterization of a microchip with 12 identical but individually addressable electrochemical measuring sites, each consisting of a set of interdigitated electrodes acting as a working electrode as well as two circular electrodes functioning as a counter and reference electrode in close proximity. The electrodes are made of gold on a silicon oxide substrate and are passivated by a silicon nitride membrane. A method for avoiding the creation of high edges at the electrodes (known as lift-off ears is presented. The microchip design is highly symmetric to accommodate easy electronic integration and provides space for microfluidic inlets and outlets for integrated custom-made microfluidic systems on top.

  18. Microelectrode array in mixed alkanethiol self-assembled monolayers: Electrochemical studies

    International Nuclear Information System (INIS)

    We report an efficient alternative to obtain recessed microelectrodes device on gold electrode surface, in which mixed self-assembled monolayer of long and short carbon alkanethiol chains was used for this purpose. Development of the modified electrodes included the chemical adsorption of 11-mercaptoundecanoic acid and 2-mercaptoethanol solution, as well as their mixtures, on gold surface, resulting in the final mixed self-assembled monolayer configuration. For comparison, the electrochemical performance of self-assembled monolayer of 11-mercaptoundecanoic acid, 3-mercaptopropionic acid, 4-mercapto-1-butanol and 6-mercapto-1-hexanol modified electrodes was also investigated. It was verified that, in the mixed self-assembled monolayer, the 11-mercaptoundecanoic acid acts as a barrier for electron transfer while the short alkanethiol chair is deposited in an island-like shape through which electrons can be freely transferred to ions in solution, allowing electrochemical reactions to occur. The performance of the modified electrodes toward microelectrode behavior was investigated via cyclic voltammetry and electrochemical impedance spectroscopy measurements using [Fe(CN)6]3−/4− redox couple as a probe. In this case, sigmoidal voltammetric responses were obtained, very similar to those observed for microelectrodes. Such behavior reinforces the proposition of electron transfer through the short alkanethiol chain layer and surface blockage by the long chain one. Electrochemical impedance results allowed calculated the mean radius value of each microelectrode disks of 3.8 μm with about 22 μm interval between them. The microelectrode environment provided by the mixed self-assembled monolayer can be conveniently used to provide an efficient catalytic conversion in biosensing applications.

  19. Electrochemical biosensor based on microfabricated electrode arrays for life sciences applications

    OpenAIRE

    Mohd Said, Nur Azura

    2014-01-01

    In developing a biosensor, the utmost important aspects that need to be emphasized are the specificity and selectivity of the transducer. These two vital prerequisites are of paramount in ensuring a robust and reliable biosensor. Improvements in electrochemical sensors can be achieved by using microelectrodes and to modify the electrode surface (using chemical or biological recognition layers to improve the sensitivity and selectivity). The fabrication and characterisations of silicon-based a...

  20. Well-integrated ZnO nanorod arrays on conductive textiles by electrochemical synthesis and their physical properties

    Science.gov (United States)

    Ko, Yeong Hwan; Kim, Myung Sub; Park, Wook; Yu, Jae Su

    2013-01-01

    We reported well-integrated zinc oxide (ZnO) nanorod arrays (NRAs) on conductive textiles (CTs) and their structural and optical properties. The integrated ZnO NRAs were synthesized by cathodic electrochemical deposition on the ZnO seed layer-coated CT substrate in ultrasonic bath. The ZnO NRAs were regularly and densely grown as well as vertically aligned on the overall surface of CT substrate, in comparison with the grown ZnO NRAs without ZnO seed layer or ultrasonication. Additionally, their morphologies and sizes can be efficiently controlled by changing the external cathodic voltage between the ZnO seed-coated CT substrate and the counter electrode. At an external cathodic voltage of -2 V, the photoluminescence property of ZnO NRAs was optimized with good crystallinity and high density.

  1. Study of Halitosis-Substance Sensing at Low Concentration Using an Electrochemical Sensor Array Combined with a Preconcentrator

    Science.gov (United States)

    Sasaya, Yosuke; Nakamoto, Takamichi

    A method for quantitative detection and discrimination of volatile sulfur compounds (VSCs) using an electrochemical sensor array combined with a preconcentrator was proposed. Halitosis is due to VSCs produced by bacterial metabolism inside the oral cavity. An organoleptic test is typically performed by a dental clinician for the assessment of halitosis, although it is a subjective test. Thus, an objective evaluation of halitosis is required. In this study, it was possible to discriminate among the VSCs such as hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl sulfide ((CH3)2S) over the range of 200ppb to 1000ppb. Moreover, mixture of two VSC vapors (H2S and CH3SH) at various mixing ratios were measured. The results indicated that the sensor responses to mixed samples satisfied the linear superposition. The mixture compositions of VSCs were almost correctly obtained from the sensor responses using partial least squares (PLS) regression analysis.

  2. Biomarker differences between cadaveric grafts used in human orthotopic liver transplantation as identified by coulometric electrochemical array detection (CEAD) metabolomics.

    Science.gov (United States)

    Perera, M Thamara P R; Higdon, Roger; Richards, Douglas A; Silva, Michael A; Murphy, Nick; Kolker, Eugene; Mirza, Darius F

    2014-12-01

    Metabolomics in systems biology research unravels intracellular metabolic changes by high throughput methods, but such studies focusing on liver transplantation (LT) are limited. Microdialysate samples of liver grafts from donors after circulatory death (DCD; n=13) and brain death (DBD; n=27) during cold storage and post-reperfusion phase were analyzed through coulometric electrochemical array detection (CEAD) for identification of key metabolomics changes. Metabolite peak differences between the graft types at cold phase, post-reperfusion trends, and in failed allografts, were identified against reference chromatograms. In the cold phase, xanthine, uric acid, and kynurenine were overexpressed in DCD by 3-fold, and 3-nitrotyrosine (3-NT) and 4-hydroxy-3-methoxymandelic acid (HMMA) in DBD by 2-fold (pidentification of overexpression of kynurenine in DCD grafts and in failed allografts is unique. Further studies should examine kynurenine as a potential biomarker predicting graft function, its causation, and actions on subsequent clinical outcomes.

  3. A simple electrochemical oxidation method to prepare highly ordered Cr-doped titania nanotube arrays with promoted photoelectrochemical property

    International Nuclear Information System (INIS)

    Highlights: ► Cr-TiO2NTs were prepared via an electrochemical oxidation method. ► Potassium dichromate was used as the source of Cr dopant. ► Cr-TiO2NTs showed high photoelectrocatalytic activity to remove organic pollutant. - Abstract: Highly ordered Cr-doped TiO2 nanotube arrays (Cr-TiO2NTs) were prepared by the electrochemical oxidation of Ti substrate in glycerol/fluoride electrolyte solution containing potassium dichromate. The Cr-TiO2NTs were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicated that Cr3+ was successfully introduced into TiO2 nanotubes and Cr doping inhibited the crystal phase change of TiO2 from anatase to rutile under high annealing temperature. Compared with pure TiO2NTs, the Cr-doped TiO2NTs exhibited higher photocurrent response, which was influenced by the concentration of Cr(VI) dopant and annealing temperature. The efficient removal of methyl orange (MO) indicated the high photoelectrocatalytic (PEC) activity of Cr-TiO2NTs.

  4. Electrochemically conductive treatment of TiO2 nanotube arrays in AlCl3 aqueous solution for supercapacitors

    Science.gov (United States)

    Zhong, Wenjie; Sang, Shangbin; Liu, Yingying; Wu, Qiumei; Liu, Kaiyu; Liu, Hongtao

    2015-10-01

    Highly ordered TiO2 nanotube arrays (NTAs) with excellent stability and large specific surface area make them competitive using as supercapacitor materials. Improving the conductivity of TiO2 is of great concern for the construction of high-performance supercapacitors. In this work, we developed a novel approach to improve the performance of TiO2 materials, involving the fabrication of Al-doped TiO2 NTAs by a simple electrochemical cathodic polarization treatment in AlCl3 aqueous solution. The prepared Al-doped TiO2 NTAs exhibited excellent electrochemical performances, attributing to the remarkably improved electrical conductivity (i.e., from approx. 10 kΩ to 20 Ω). Further analysis showed that Al3+ ions rather than H+ protons doped into TiO2 lattice cause this high conductivity. A MnO2/Al-TiO2 composite was evaluated by cyclic voltammetry, and achieved the specific capacitance of 544 F g-1, and the Ragone plot of the sample showed a high power density but less reduction of energy density. These results indicate that the MnO2/Al-TiO2 NTAs sample could be served as a promising electrode material for high -performance supercapacitors.

  5. Synthesis and electrochemical performances of ZnO/MnO2 sea urchin-like sleeve array as anode materials for lithium-ion batteries

    International Nuclear Information System (INIS)

    MnO2 is electrodeposited onto ZnO nanorod array grown on Ni foil, forming a binder-free ZnO/MnO2 composited electrode. XRD, EDS, SEM and TEM are used to analyze the phase and microstructure of this composite. Burr-like MnO2 nanoflakes grows on ZnO nanorod array, the top of the composite is hollow and at the bottom exists ZnO large block core as an internal support, forming ZnO/MnO2 sea urchin-like sleeve array. As anode material for lithium ion batteries, ZnO/MnO2 sleeve array exhibits higher discharge capacity and coulombic efficiency, better rate performance and cycling stability than single ZnO nanorod array or directly electrodepsited MnO2, and the composite effect is very remarkable. After 100 cycles, the discharge capacity of ZnO/MnO2 still reaches 1259 mA h g−1, and coulombic efficiency surpasses 98%, higher than those of ZnO nanorod array (111 mA h g−1) and directly electrodeposited MnO2 (507 mA h g−1). The improvement of the electrochemical performances is due to the unique sea urchin-like sleeve array architecture. MnO2 burr tube shell structure leads to high electrochemical activity while the internal ZnO core support ensures good structure stability. The gradually opening of sea urchin-like sleeve during the cycling further enhances the electrochemical activity of MnO2, stabilizing and increasing electrochemical performances of the ZnO/MnO2 composite

  6. Recent Developments in Electrochemical Biosensor Array%阵列电化学生物传感器研究进展

    Institute of Scientific and Technical Information of China (English)

    彭亚鸽; 卜春苗; 杨玉英

    2012-01-01

    Biosensor array such as optical biosensor array and electrochemical biosensor array, has been widely applied in research of genomics and proteomics and in field of drug screening, environmental analysis, food analysis and clinical diagnostics. Electrochemical biosensor array is a promising analytical device that combines immobilized molecular recognition element on surface of multi-electrode array with electrochemical detection signal. It has gained a considerable attention due to high sensitivity, speed, good selectivity, easy miniaturization and integration as well as inexpensive instrument used. The principle and characteristic of electrochemical biosensor array are described herein. The current development of electrochemical biosensor array including single-analyte and multi-ana-lyte since 2005 is reviewed extensively. The current problems and trend of electrochemical biosensor array are briefly discussed.%阵列生物传感器技术作为一种高通量、快速、选择性高和集成化的分析技术,已在基因组学和蛋白质组学的研究和药物筛选、环境分析,食品分析,临床诊断等领域中得到广泛的应用.阵列生物传感器主要有阵列光学生物传感器和阵列电化学生物传感器.阵列电化学生物传感器是将生物分子识别物质如酶、抗原/抗体、DNA等固定在阵列电极上,以阵列中每根电极产生的电化学信号作为检测信号的电化学分析器件.阵列电化学生物传感器以灵敏度高、分析速度快、选择性好、易于微型化和集成化以及仪器价格低廉等特点受到了研究工作者的极大关注.本文简单介绍了阵列电化学生物传感器的原理和特点,重点评述了2005年以来阵列电化学生物传感器在单组份检测和多组份同时检测两方面的研究进展,简单讨论了阵列电化学生物传感器研究中存在的问题.

  7. Branched zinc oxide nanorods arrays modified paper electrode for electrochemical immunosensing by combining biocatalytic precipitation reaction and competitive immunoassay mode.

    Science.gov (United States)

    Sun, Guoqiang; Yang, Hongmei; Zhang, Yan; Yu, Jinghua; Ge, Shenguang; Yan, Mei; Song, Xianrang

    2015-12-15

    Branched zinc oxide nanorods (BZR) arrays, an array with high charge carries collection efficiency and specific surface area, are grown on the reduced graphene oxide-paper working electrode for the first time to construct a paper-based electrochemical (EC) immunosensor. Typically, the BZR are fabricated via a simple hydrothermal process, which can provide abundant sites for antibodies loading. By combining the large surface area of porous zinc oxide (PZS) and good biocompatibility of gold nanoparticles (AuNPs), PZS-AuNPs (PZS@Au) nanocomposites are designed to label horseradish peroxide (HRP) and antigens. After a competitive reaction between antigens and PZS@Au nanocomposites labeled antigens, the signal labels are introduced into the immunosensor, in which, HRP participate in biocatalytic precipitation process. The produced precipitate reduces the electrode surface area and hinders the electron transfer. With the increase of concentration of antigens, the signal labels introduced into the sensor decrease, thus, a signal-on immunoassay for α-fetoprotein detection is constructed. The proposed paper-based EC immunosensor combines enzymatic biocatalytic precipitation reaction and competitive immunoassay mode for the first time, and possesses a wide linear range from 0.2 pg mL(-1) to 500 ng mL(-1) with a detection limit of 0.08 pg mL(-1). In addition, the proposed method is simple, sensitive and specific and can be a promising platform for other protein detection.

  8. Urea assisted electrochemical synthesis of flower-like platinum arrays with high electrocatalytic activity

    International Nuclear Information System (INIS)

    Graphical abstract: A simple, facile, and controllable method was developed for preparation of well-defined flower-like Pt arrays via one-step electrodeposition, assisted with urea as a growth directing agent. The as-prepared Pt nanocrystals have a larger electroactive surface area and higher electrocatalytic activity toward ethylene glycol and methanol oxidation in acid media, compared with Pt nanoparticles and commercial Pt black catalysts. - Highlights: • Well-defined flower-like Pt arrays were prepared via one-step electrodeposition, assisted with urea as a growth directing agent. • This method is simple, facile, and controllable, without using any template, seed or surfactant. • The Pt arrays show an enhanced electrocatalytic activity toward ethylene glycol and methanol oxidation. - Abstract: In this paper, well-defined flower-like Pt arrays were prepared on the glassy carbon electrode by one-step electrodeposition at–0.3 V for 600 s in 0.5 M H2SO4 containing 5 mM H2PtCl6 and 150 mM urea. This method is simple, facile, and controllable, without using any template, seed or surfactant. The experimental parameters were investigated and found urea acted as a growth directing agent. The as-prepared Pt nanocrystals were preferentially growing along the (111) directions, which were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX). Moreover, the flower-like Pt nanoarrays exhibited a large effective surface area (EASA) and enhanced performance toward the oxidation of ethylene glycol and methanol in acid media, compared with Pt nanoparticles and commercial Pt black catalysts. This strategy can be extended to prepare other noble metal nanostructures as good electrocatalysts in fuel cells

  9. Fabrication and Electrochemical Characterization of Micro- and Nanoelectrode Arrays for Sensor Applications

    Energy Technology Data Exchange (ETDEWEB)

    Said, Nur Azura Mohd; Twomey, Karen; Ogurtsov, Vladimir I; Herzog, Gregoire [Tyndall National Institute, Lee Maltings, University College Cork, Cork (Ireland); Arrigan, Damien W M, E-mail: gregoire.herzog@tyndall.ie [Nanochemistry Research Institute, Department of Chemistry, Curtin University, Perth (Australia)

    2011-08-17

    This paper describes the fabrication of microelectrode arrays, with two different geometries: disc (Designs d1 and d2) and band (Designs b1, b2 and b3) using three critical dimensions (100 nm, 1 {mu}m and 10 {mu}m) leading to 5 different designs, fabricated by the combination of UV photolithographic and e-beam lithographic techniques. Three silicon nitride layer thicknesses (200, 300 and 500 nm) were chosen to determine an optimized transducer design and fabrication process. Cyclic voltammetry characterisation using a simple redox probe ion, ferreocenecarboxylic acid in phosphate buffered saline electrolyte solution, demonstrated steady-state voltammetric curves for d1, d2, b1 and b2. A good agreement between experimental and theoretical data is found for devices d1, d2, b1 and b2. The experimental current for b3, on the other hand, is much lower compared to the calculated one- perhaps due to the overlapping of the diffusion layers of neighbouring microelectrodes in the array.

  10. Effect of Tin+ defects on electrochemical properties of highly-ordered titania nanotube arrays

    International Nuclear Information System (INIS)

    In this paper, highly-ordered TiO2 nanotube (TNT) electrodes fabricated by anodization at 20 V in 0.1 M F--based solution were annealed in O2, N2 and CO respectively. The surface properties of the TiO2 electrodes after annealing treatment by different gases were studied by means of photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the TNT electrodes were investigated by cyclic voltammetry, steady-state polarization and photocurrent response measurements. The results showed that Tin+ (n = 0-3) cations and oxygen vacancies existed in the TNT electrode after annealing in CO, leading to a very efficient electron transfer rate of 1.34 x 10-3 cm/s. Steady-state polarization measurement and photocurrent response demonstrated that the electrode potential of oxygen evolution reaction (OER) reduced by 20% and the photocurrent response increased by 50% for CO-annealed TNT electrode compared with O2-annealed TNT electrode.

  11. Clinical validation of integrated nucleic acid and protein detection on an electrochemical biosensor array for urinary tract infection diagnosis.

    Directory of Open Access Journals (Sweden)

    Ruchika Mohan

    Full Text Available BACKGROUND: Urinary tract infection (UTI is a common infection that poses a substantial healthcare burden, yet its definitive diagnosis can be challenging. There is a need for a rapid, sensitive and reliable analytical method that could allow early detection of UTI and reduce unnecessary antibiotics. Pathogen identification along with quantitative detection of lactoferrin, a measure of pyuria, may provide useful information towards the overall diagnosis of UTI. Here, we report an integrated biosensor platform capable of simultaneous pathogen identification and detection of urinary biomarker that could aid the effectiveness of the treatment and clinical management. METHODOLOGY/PRINCIPAL FINDINGS: The integrated pathogen 16S rRNA and host lactoferrin detection using the biosensor array was performed on 113 clinical urine samples collected from patients at risk for complicated UTI. For pathogen detection, the biosensor used sandwich hybridization of capture and detector oligonucleotides to the target analyte, bacterial 16S rRNA. For detection of the protein biomarker, the biosensor used an analogous electrochemical sandwich assay based on capture and detector antibodies. For this assay, a set of oligonucleotide probes optimized for hybridization at 37°C to facilitate integration with the immunoassay was developed. This probe set targeted common uropathogens including E. coli, P. mirabilis, P. aeruginosa and Enterococcus spp. as well as less common uropathogens including Serratia, Providencia, Morganella and Staphylococcus spp. The biosensor assay for pathogen detection had a specificity of 97% and a sensitivity of 89%. A significant correlation was found between LTF concentration measured by the biosensor and WBC and leukocyte esterase (p<0.001 for both. CONCLUSION/SIGNIFICANCE: We successfully demonstrate simultaneous detection of nucleic acid and host immune marker on a single biosensor array in clinical samples. This platform can be used for

  12. Vertically Oriented Arrays of ReS2 Nanosheets for Electrochemical Energy Storage and Electrocatalysis.

    Science.gov (United States)

    Gao, Jian; Li, Lu; Tan, Jiawei; Sun, Hao; Li, Baichang; Idrobo, Juan Carlos; Singh, Chandra Veer; Lu, Toh-Ming; Koratkar, Nikhil

    2016-06-01

    Transition-metal dichalcogenide (TMD) nanolayers show potential as high-performance catalysts in energy conversion and storage devices. Synthetic TMDs produced by chemical-vapor deposition (CVD) methods tend to grow parallel to the growth substrate. Here, we show that with the right precursors and appropriate tuning of the CVD growth conditions, ReS2 nanosheets can be made to orient perpendicular to the growth substrate. This accomplishes two important objectives; first, it drastically increases the wetted or exposed surface area of the ReS2 sheets, and second, it exposes the sharp edges and corners of the ReS2 sheets. We show that these structural features of the vertically grown ReS2 sheets can be exploited to significantly improve their performance as polysulfide immobilizers and electrochemical catalysts in lithium-sulfur (Li-S) batteries and in hydrogen evolution reactions (HER). After 300 cycles, the specific capacity of the Li-S battery with vertical ReS2 catalyst is retained above 750 mA h g(-1), with only ∼0.063% capacity decay per cycle, much better than the baseline battery (without ReS2), which shows ∼0.184% capacity decay per cycle under the same test conditions. As a HER catalyst, the vertical ReS2 provides very small onset overpotential (<100 mV) and an exceptional exchange-current density (∼67.6 μA/cm(2)), which is vastly superior to the baseline electrode without ReS2. PMID:27187173

  13. In situ electrochemical STM study of platinum nanodot arrays on highly oriented pyrolythic graphite prepared by electron beam lithography

    Science.gov (United States)

    Foelske-Schmitz, A.; Peitz, A.; Guzenko, V. A.; Weingarth, D.; Scherer, G. G.; Wokaun, A.; Kötz, R.

    2012-12-01

    Model electrodes consisting of platinum dots with a mean diameter of (30 ± 5) nm and heights of 3-5 nm upon highly oriented pyrolytic graphite (HOPG) were prepared by electron beam lithography and subsequent sputtering. The Pt nanodot arrays were stable during scanning tunnelling microscopy (STM) measurements in air and in sulphuric acid electrolyte, indicating the presence of "anchors", immobilising the dots on the HOPG surface. Electrochemical STM was used to visualise potential induced Pt, carbon and Pt-influenced carbon corrosion in situ in 0.5 M sulphuric acid under ambient conditions. Potentiostatic hold experiments show that the Pt dots start to disappear at electrode potentials of E > 1.4 V vs. SHE. With increasing time and potential a hole pattern congruent to the original dot pattern appears on the HOPG basal planes. Corrosion and peeling of the HOPG substrate could also be followed in situ. Dissolution of Pt dots appears to be accelerated for potential cycling experiments compared to the potential hold statistics.

  14. Structural and Electrochemical Investigation during the First Charging Cycles of Silicon Microwire Array Anodes for High Capacity Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Helmut Föll

    2013-02-01

    Full Text Available Silicon microwire arrays embedded in Cu present exceptional performance as anode material in Li ion batteries. The processes occurring during the first charging cycles of batteries with this anode are essential for good performance. This paper sheds light on the electrochemical and structural properties of the anodes during the first charging cycles. Scanning Electron Microscopy, X-ray diffractommetry, and fast Fourier transformation impedance spectroscopy are used for the characterization. It was found that crystalline phases with high Li content are obtained after the first lithiation cycle, while for the second lithiation just crystalline phases with less Li are observable, indicating that the lithiated wires become amorphous upon cycling. The formation of a solid electrolyte interface of around 250 nm during the first lithiation cycle is evidenced, and is considered a necessary component for the good cycling performance of the wires. Analog to voltammetric techniques, impedance spectroscopy is confirmed as a powerful tool to identify the formation of the different Si-Li phases.

  15. On-chip supercapacitors with ultrahigh volumetric performance based on electrochemically co-deposited CuO/polypyrrole nanosheet arrays

    Science.gov (United States)

    Qian, Tao; Zhou, Jinqiu; Xu, Na; Yang, Tingzhou; Shen, Xiaowei; Liu, Xuejun; Wu, Shishan; Yan, Chenglin

    2015-10-01

    We introduce a new method for fabricating unique on-chip supercapacitors based on CuO/polypyrrole core/shell nanosheet arrays by means of direct electrochemical co-deposition on interdigital-like electrodes. The prepared all-solid-state device demonstrates exceptionally high specific capacitance of 1275.5 F cm-3 (˜40 times larger than that of CuO-only supercapacitors) and high-energy-density of 28.35 mWh cm-3, which are both significantly greater than other solid-state supercapacitors. More importantly, the device maintains approximately 100% capacity retention at 2.5 A cm-3 after 3000 cycles. The in situ co-deposition of CuO/polypyrrole nanosheets on interdigital substrate enables effective charge transport, electrode fabrication integrity, and device integration. Because of their high energy, power density, and stable cycling stability, these newly developed on-chip supercapacitors permit fast, reliable applications in portable and miniaturized electronic devices.

  16. Cell array-based intracellular localization screening reveals novel functional features of human chromosome 21 proteins

    Directory of Open Access Journals (Sweden)

    Kahlem Pascal

    2006-06-01

    Full Text Available Abstract Background Trisomy of human chromosome 21 (Chr21 results in Down's syndrome, a complex developmental and neurodegenerative disease. Molecular analysis of Down's syndrome, however, poses a particular challenge, because the aneuploid region of Chr21 contains many genes of unknown function. Subcellular localization of human Chr21 proteins may contribute to further understanding of the functions and regulatory mechanisms of the genes that code for these proteins. Following this idea, we used a transfected-cell array technique to perform a rapid and cost-effective analysis of the intracellular distribution of Chr 21 proteins. Results We chose 89 genes that were distributed over the majority of 21q, ranging from RBM11 (14.5 Mb to MCM3AP (46.6 Mb, with part of them expressed aberrantly in the Down's syndrome mouse model. Open reading frames of these genes were cloned into a mammalian expression vector with an amino-terminal His6 tag. All of the constructs were arrayed on glass slides and reverse transfected into HEK293T cells for protein expression. Co-localization detection using a set of organelle markers was carried out for each Chr21 protein. Here, we report the subcellular localization properties of 52 proteins. For 34 of these proteins, their localization is described for the first time. Furthermore, the alteration in cell morphology and growth as a result of protein over-expression for claudin-8 and claudin-14 genes has been characterized. Conclusion The cell array-based protein expression and detection approach is a cost-effective platform for large-scale functional analyses, including protein subcellular localization and cell phenotype screening. The results from this study reveal novel functional features of human Chr21 proteins, which should contribute to further understanding of the molecular pathology of Down's syndrome.

  17. Development and application of a novel genome-wide SNP array reveals domestication history in soybean.

    Science.gov (United States)

    Wang, Jiao; Chu, Shanshan; Zhang, Huairen; Zhu, Ying; Cheng, Hao; Yu, Deyue

    2016-02-09

    Domestication of soybeans occurred under the intense human-directed selections aimed at developing high-yielding lines. Tracing the domestication history and identifying the genes underlying soybean domestication require further exploration. Here, we developed a high-throughput NJAU 355 K SoySNP array and used this array to study the genetic variation patterns in 367 soybean accessions, including 105 wild soybeans and 262 cultivated soybeans. The population genetic analysis suggests that cultivated soybeans have tended to originate from northern and central China, from where they spread to other regions, accompanied with a gradual increase in seed weight. Genome-wide scanning for evidence of artificial selection revealed signs of selective sweeps involving genes controlling domestication-related agronomic traits including seed weight. To further identify genomic regions related to seed weight, a genome-wide association study (GWAS) was conducted across multiple environments in wild and cultivated soybeans. As a result, a strong linkage disequilibrium region on chromosome 20 was found to be significantly correlated with seed weight in cultivated soybeans. Collectively, these findings should provide an important basis for genomic-enabled breeding and advance the study of functional genomics in soybean.

  18. Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes

    Directory of Open Access Journals (Sweden)

    Zhiyang Li

    2015-09-01

    Full Text Available 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.

  19. Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes.

    Science.gov (United States)

    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

  20. High-performance and renewable supercapacitors based on TiO2 nanotube array electrodes treated by an electrochemical doping approach

    International Nuclear Information System (INIS)

    Although one-dimensional anodic TiO2 nanotube arrays have shown promise as supercapacitor electrode materials, their poor electronic conductivity embarrasses the practical applications. Here, we develop a simple electrochemical doping method to significantly improve the electronic conductivity and the electrochemical performances of TiO2 nanotube electrodes. These TiO2 nanotube electrodes treated by the electrochemical hydrogenation doping (TiO2-H) exhibit a very high average specific capacitance of 20.08 mF cm−2 at a current density of 0.05 mA cm−2, ∼20 times more than the pristine TiO2 nanotube electrodes. The improved electrochemical performances can be attributed to ultrahigh conductivity of TiO2-H due to the introduction of interstitial hydrogen ions and oxygen vacancies by the doping. The supercapacitor device assembled by the doped electrodes delivers a specific capacitance of 5.42 mF cm−2 and power density of 27.66 mW cm−2, on average, at the current density of 0.05 mA cm−2. The device also shows an outstanding rate capability with 60% specific capacitance retained when the current density increases from 0.05 to 4.00 mA cm−2. More interestingly, the electrochemical performances of the supercapacitor after cycling can be recovered by the same doping process. This strategy boosts the performances of the supercapacitor, especially cycling stability

  1. Automated image analysis reveals the dynamic 3-dimensional organization of multi-ciliary arrays

    Directory of Open Access Journals (Sweden)

    Domenico F. Galati

    2016-01-01

    Full Text Available Multi-ciliated cells (MCCs use polarized fields of undulating cilia (ciliary array to produce fluid flow that is essential for many biological processes. Cilia are positioned by microtubule scaffolds called basal bodies (BBs that are arranged within a spatially complex 3-dimensional geometry (3D. Here, we develop a robust and automated computational image analysis routine to quantify 3D BB organization in the ciliate, Tetrahymena thermophila. Using this routine, we generate the first morphologically constrained 3D reconstructions of Tetrahymena cells and elucidate rules that govern the kinetics of MCC organization. We demonstrate the interplay between BB duplication and cell size expansion through the cell cycle. In mutant cells, we identify a potential BB surveillance mechanism that balances large gaps in BB spacing by increasing the frequency of closely spaced BBs in other regions of the cell. Finally, by taking advantage of a mutant predisposed to BB disorganization, we locate the spatial domains that are most prone to disorganization by environmental stimuli. Collectively, our analyses reveal the importance of quantitative image analysis to understand the principles that guide the 3D organization of MCCs.

  2. Spin-coated Au-nanohole arrays engineered by nanosphere lithography for a Staphylococcus aureus 16S rRNA electrochemical sensor.

    Science.gov (United States)

    Purwidyantri, Agnes; Chen, Ching-Hsiang; Hwang, Bing-Joe; Luo, Ji-Dung; Chiou, Chiuan-Chian; Tian, Ya-Chung; Lin, Chan-Yu; Cheng, Chi-Hui; Lai, Chao-Sung

    2016-03-15

    The nanopatterning of gold nanoparticle (AuNP) arrays on an indium tin oxide (ITO) electrode using efficient and low-cost methods is described. This process used nanosphere lithography (NSL) encompassing the deposition of monolayered Polystyrene (PS) followed by a convective self-assembly drop coating protocol onto the ITO substrate that further acted as the mask after the AuNP assembly. The results showed that spin-coating allowed AuNPs to follow the contour and adhere to the PS nanospheres. The final products, after etching the PS, generated a highly ordered Au-nanohole array on an ITO substrate. The Au-nanohole arrays on the ITO electrode provided a greater surface area and successfully enhanced the peak current of electrochemical measurements by 82% compared with bare ITO and was used to detect Staphylococcus aureus 16S rRNA hybridization. In contrast to non-templated AuNP structures, the Au-nanohole arrays on the ITO electrode contributed to an optimum sensitivity improvement in DNA hybridization detection by 23%, along with an impressive limit of detection (LOD) of 10 pM. The high specificity of this distinguished structure was also achieved in the hybridization measurements of multi-analyte pathogens. These findings indicate that the combination of PS nanosphere lithography, followed by the spin-coating of AuNPs, leads to an inexpensive and simple engineering process that effectively generates uniform Au-nanohole arrays on ITO, which provides a greater surface area to optimize the electrochemical performance of the DNA biosensor. PMID:26556186

  3. Optical and structural properties of electrochemically deposited ZnO nanorod arrays suitable for improvement of the light harvesting in thin film solar cells

    International Nuclear Information System (INIS)

    The results of study of the optical and structural properties of ZnO nanorods (NR) arrays electrochemically deposited on two type substrates – the ITO surface on the front side of Si heterojunction (SHJ) solar cells and on stainless steel plate used for formation of a-Si:H thin film solar cells, are reported. The surface morphology of the NS arrays is examined by Scanning Electron Microscopy and AFM. The spectra of specular diffused and total reflection, and haze ratio in reflectance are compared before and after deposition of the ZnO NR arrays. In the case of deposition on ITO surface of SHJ solar cells the values of the direct and diffused reflection of the ZnO NR array decrease demonstrating good antireflection properties. Deposition of ZnO NS arrays on stainless steel plates leads to increasing the values of the diffused reflection and the total reflectance. Possible application of ZnO NS structures for the processing of advanced Si based solar cells for increasing light harvesting is discussed

  4. Effect of diameter and height of electrochemically-deposited ZnO nanorod arrays on the performance of piezoelectric nanogenerators

    Energy Technology Data Exchange (ETDEWEB)

    Nagaraju, Goli; Ko, Yeong Hwan; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

    2015-01-15

    We investigated the performance of zinc oxide (ZnO) nanorod arrays (NRAs)-based piezoelectric nanogenerators (NGs) by controlling their diameter and height which are closely related to piezoelectric output current. The ZnO NRAs as a nanostructured piezoelectric material were synthesized on flexible indium tin oxide (ITO)-coated polyethylene terephthalate (PET) (i.e., ITO/PET) substrates by a facile electrochemical deposition (ED) method. As the zinc nitrate concentration and growth time increased, the diameter and height of ZnO NRAs also increased. Based on the ZnO NRAs on ITO/PET, piezoelectric NGs were fabricated with an opposite electrode of gold-coated PET film (i.e. Au/PET). At 10 mM of zinc nitrate concentration and 1 h of growth time, the ZnO NRAs exhibited relatively regular and higher output currents, leading to an estimated average value of ∼10.4 nA/cm{sup 2} under a low external pushing force of 0.98 N. For the samples at 1 and 100 mM, piezoelectric currents were relatively low (∼4.34 and 1.45–5.21 nA/cm{sup 2}, respectively). It was found that the ZnO NRAs with high diameter/height uniformity and good alignment tend to be bent more easily for efficiently generating piezoelectric currents. The bending efficiency of ZnO NRAs was also analysed theoretically by calculating the strain distribution of ZnO NRAs-based NGs with different diameters and heights of the nanorods. - Highlights: • ZnO NRAs were synthesized on ITO/PET substrate by a facile ED process. • The diameter and height of ZnO NRAs were controlled by varying growth parameters. • Under an optimized condition, the NG exhibited a relatively high output current. • Theoretical results confirmed the bending efficiency of various ZnO NRAs.

  5. 纳米阵列和纳米晶薄膜锡电极性质的电化学研究%Electrochemical Study of Nano-Array and Nano-Crystalline Tin Anode

    Institute of Scientific and Technical Information of China (English)

    王宇; 刘浪; 吴大平; 郭玉忠; 王剑华

    2012-01-01

    Tin nano-array electrodes were assembled by electrochemical deposition using alumina anodic oxide (AAO) as templates. Morphology and structure of the tin electrodes were characterized by SEM and XRD. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were applied to reveal the electrochemical performance of the electrodes used as anode of Li-ion battery. Compared to electrodes of tin film and tin foil from rolling, the electrodes of tin nano-arrays are very active. The EIS spectra of tin nano-array electrodes show different characters from electrodes of tin film and tin foil. A medium-frequency area has been found which is ascribed to the large charge transfer area across the electrode/electrolyte interface. The lithium ion transporting in solid-electrolyte ion surface layer are controlled by structure of electrodes. The surface resistances for nano-arrays observed from high frequency ace are between 19.8 and 14.6 Ω·cm2. The highest diffusion coefficient is 10-10 cm2·s-1 for nano-array electrode, at potential of 0.2 V. The nano-array structure can lead to high electrochemical activity of the electrodes.%采用氧化铝为模板的电化学沉积方法制备锡纳米阵列电极,用扫描电镜和X射线衍射仪表征电极微观形貌结构,并采用循环伏安和交流阻抗研究电极嵌锂过程,同时研究纳米晶锡薄膜电极和轧制锡箔电极.结果表明:纳米阵列电极与锡薄膜、锡箔电极具有不同交流阻抗谱特征,锡纳米阵列电极在中频区出现双电层阻抗,与其电解液/电极接触面积较大有关;不同微观结构形态下锡电极的电化学反应表面阻抗相差大于一个数量级,锡纳米阵列的表面膜电阻为19.8~14.6 Ω·cm2;锡纳米阵列电极上的锂离子扩散速率最大,0.2V嵌锂电位下扩散系数为10-10 cm2·s-1;采用纳米阵列结构使电极具有很高电的化学活性.

  6. Graphene Paper Decorated with a 2D Array of Dendritic Platinum Nanoparticles for Ultrasensitive Electrochemical Detection of Dopamine Secreted by Live Cells.

    Science.gov (United States)

    Zan, Xiaoli; Bai, Hongwei; Wang, Chenxu; Zhao, Faqiong; Duan, Hongwei

    2016-04-01

    To circumvent the bottlenecks of non-flexibility, low sensitivity, and narrow workable detection range of conventional biosensors for biological molecule detection (e.g., dopamine (DA) secreted by living cells), a new hybrid flexible electrochemical biosensor has been created by decorating closely packed dendritic Pt nanoparticles (NPs) on freestanding graphene paper. This innovative structural integration of ultrathin graphene paper and uniform 2D arrays of dendritic NPs by tailored wet chemical synthesis has been achieved by a modular strategy through a facile and delicately controlled oil-water interfacial assembly method, whereby the uniform distribution of catalytic dendritic NPs on the graphene paper is maximized. In this way, the performance is improved by several orders of magnitude. The developed hybrid electrode shows a high sensitivity of 2 μA cm(-2) μM(-1), up to about 33 times higher than those of conventional sensors, a low detection limit of 5 nM, and a wide linear range of 87 nM to 100 μM. These combined features enable the ultrasensitive detection of DA released from pheochromocytoma (PC 12) cells. The unique features of this flexible sensor can be attributed to the well-tailored uniform 2D array of dendritic Pt NPs and the modular electrode assembly at the oil-water interface. Its excellent performance holds much promise for the future development of optimized flexible electrochemical sensors for a diverse range of electroactive molecules to better serve society. PMID:26918612

  7. Graphene Paper Decorated with a 2D Array of Dendritic Platinum Nanoparticles for Ultrasensitive Electrochemical Detection of Dopamine Secreted by Live Cells

    Science.gov (United States)

    Zan, Xiaoli; Wang, Chenxu

    2016-01-01

    Abstract To circumvent the bottlenecks of non‐flexibility, low sensitivity, and narrow workable detection range of conventional biosensors for biological molecule detection (e.g., dopamine (DA) secreted by living cells), a new hybrid flexible electrochemical biosensor has been created by decorating closely packed dendritic Pt nanoparticles (NPs) on freestanding graphene paper. This innovative structural integration of ultrathin graphene paper and uniform 2D arrays of dendritic NPs by tailored wet chemical synthesis has been achieved by a modular strategy through a facile and delicately controlled oil–water interfacial assembly method, whereby the uniform distribution of catalytic dendritic NPs on the graphene paper is maximized. In this way, the performance is improved by several orders of magnitude. The developed hybrid electrode shows a high sensitivity of 2 μA cm−2 μm −1, up to about 33 times higher than those of conventional sensors, a low detection limit of 5 nm, and a wide linear range of 87 nm to 100 μm. These combined features enable the ultrasensitive detection of DA released from pheochromocytoma (PC 12) cells. The unique features of this flexible sensor can be attributed to the well‐tailored uniform 2D array of dendritic Pt NPs and the modular electrode assembly at the oil–water interface. Its excellent performance holds much promise for the future development of optimized flexible electrochemical sensors for a diverse range of electroactive molecules to better serve society. PMID:26918612

  8. Graphene Paper Decorated with a 2D Array of Dendritic Platinum Nanoparticles for Ultrasensitive Electrochemical Detection of Dopamine Secreted by Live Cells.

    Science.gov (United States)

    Zan, Xiaoli; Bai, Hongwei; Wang, Chenxu; Zhao, Faqiong; Duan, Hongwei

    2016-04-01

    To circumvent the bottlenecks of non-flexibility, low sensitivity, and narrow workable detection range of conventional biosensors for biological molecule detection (e.g., dopamine (DA) secreted by living cells), a new hybrid flexible electrochemical biosensor has been created by decorating closely packed dendritic Pt nanoparticles (NPs) on freestanding graphene paper. This innovative structural integration of ultrathin graphene paper and uniform 2D arrays of dendritic NPs by tailored wet chemical synthesis has been achieved by a modular strategy through a facile and delicately controlled oil-water interfacial assembly method, whereby the uniform distribution of catalytic dendritic NPs on the graphene paper is maximized. In this way, the performance is improved by several orders of magnitude. The developed hybrid electrode shows a high sensitivity of 2 μA cm(-2) μM(-1), up to about 33 times higher than those of conventional sensors, a low detection limit of 5 nM, and a wide linear range of 87 nM to 100 μM. These combined features enable the ultrasensitive detection of DA released from pheochromocytoma (PC 12) cells. The unique features of this flexible sensor can be attributed to the well-tailored uniform 2D array of dendritic Pt NPs and the modular electrode assembly at the oil-water interface. Its excellent performance holds much promise for the future development of optimized flexible electrochemical sensors for a diverse range of electroactive molecules to better serve society.

  9. Electrochemical construction of three-dimensional porous Mn3O4 nanosheet arrays as an anode for the lithium ion battery.

    Science.gov (United States)

    Fan, Xiao-Yong; Cui, Yu; Liu, Pan; Gou, Lei; Xu, Lei; Li, Dong-Lin

    2016-08-10

    Three-dimensional (3D) porous Mn3O4 nanosheet arrays were constructed via an electrodeposition followed by high temperature annealing using 3D porous Cu, prepared by a facile electroless plating method, as the substrate. The 3D pores and voids between the nanosheet arrays were able to provide rapid ion transfer channels, as well as accommodating the volumetric changes of Mn3O4 during the electrochemical cycling. Electrons can directly exchange between the substrate and the nanosheet units, avoiding curving and the long transfer distance in conventional electrodes constructed using casting technology. Furthermore, the nanosheets were transformed into the architecture with smaller sub-nanosheets on the pristine nanosheets after 1 cycle, facilitating ion transferring, and were thoroughly transformed into smaller sub-nanosheets after 1000 cycles but without obvious exfoliation, assuring good electrical contact between the active particles and substrate. Based on the above unique characteristics, the 3D porous Mn3O4 nanosheet arrays could be directly used as a binder-free and conductive-agent-free electrode to deliver ultrahigh electrochemical performance that is much better than achieved in previous reports. The first reversible capacity was 1166.3 mA h g(-1) and remained 667.9 mA h g(-1) after 1000 cycles at 1.0 A g(-1). Also, the reversible capacities at high current densities of 10.0 A g(-1) and 20.0 A g(-1) remained high at 416.1 and 216.7 mA h g(-1), respectively. PMID:27452235

  10. Electrochemical construction of a bio-inspired micro/nano-textured structure with cell-sized microhole arrays on biomedical titanium to enhance bioactivity

    International Nuclear Information System (INIS)

    Highlights: • The bio-inspired structure mimicked mulit-level structures of natural bone. • Ordered cell-sized microhole arrays were employed as microscale structure. • High surface roughness and superhydrophilicity were achieved on the titanium surface. • The bio-inspired titanium surface showed superior ability of biomineralization. • Cell responses were enhanced on the bio-inspired micro/nano-texutred surface. - Abstract: Biomimetic surface design of medical implants is vitally crucial to improve cellular responses and the integration of tissue onto materials. In this study, a novel hierarchical cell-sized microhole array combined with a nano-network structure was fabricated on a medical titanium surface to mimic multi-level bone structure. A three-step procedure was developed as follows: 1) electrochemical self-organization of etching on titanium substrate to create highly ordered cell-sized microhole arrays, 2) suitable dual acid etching to increase the roughness of the microholes, and then 3) electrochemical anodization in a NaOH electrolyte to construct a nano-network porous titania layer on the above micro-roughened surface. The bio-inspired micro/nano-textured structure presented the enhanced wettability and superhydrophilicity. The ability of in vitro biomineralization and corrosion resistance of the bio-inspired micro/nano-textured structure were enhanced after annealing treatment. More importantly, the bio-inspired micro/nano-textured structure on the titanium surface possessed a favourable interfacial environment to enhance attachment and proliferation of human osteoblast-like MG63 cells. All of the results demonstrated that such a bio-inspired surface of micro/nano-textured porous TiO2 is a most promising candidate for the next generation of titanium implants

  11. Anti-wetting Cu/Cr coating with micro-posts array structure fabricated by electrochemical approaches

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yufeng [College of Mechanical Engineering, Shanghai University of Engineering Science, Shanghai, 201620 (China); Hang, Tao, E-mail: hangtao@sjtu.org [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 (China); Li, Feng; Li, Ming [School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai, 200240 (China)

    2013-04-15

    Microposts structured Cu/Cr multilayer coating was prepared by a simple two-step approach combining electroless and electro deposition. Surface morphologies of the as-prepared Cu/Cr multilayer coating characterized by field emission scanning electron microscopy show that this multilayer coating exhibits micro-posts arrayed structure with a layer of Cr uniformly covering the circular conical surface of Cu micro-cones array. The wettability test shows that the contact angle of Cu/Cr multilayer surface with water drop can be greater than 140° by optimizing the electrodeposition time of Cr. The mechanism of hydrophobicity of both the micro-cones arrayed and micro-posts arrayed structures was briefly discussed by comparing two different wetting modes. Due to its good anti-wetting property and unique structure, the micro-posts arrayed Cu/Cr multilayer coating is expected for extensive practical applications.

  12. Electrochemical atomic force microscopy reveals potential stimulated height changes of redox responsive Cu-azurin on gold

    NARCIS (Netherlands)

    Wu, Hairong; Feng, Xueling; Kieviet, B.D.; Zhang, K.; Zandvliet, H.J.W.; Canters, G.W.; Schon, P.M.; Vancso, G.J.

    2015-01-01

    The redox active metalloprotein Cu-azurin was directly chemisorbed on bare gold electrodes through disulfide forming groups (Cys3Cys26). Topological and electrochemical properties of the immobilized molecules were investigated by electrochemical atomic force microscopy (EC-AFM) in Peak Force Tapping

  13. Cell membrane conformation at vertical nanowire array interface revealed by fluorescence imaging

    Science.gov (United States)

    Berthing, Trine; Bonde, Sara; Rostgaard, Katrine R.; Hannibal Madsen, Morten; Sørensen, Claus B.; Nygård, Jesper; Martinez, Karen L.

    2012-10-01

    The perspectives offered by vertical arrays of nanowires for biosensing applications in living cells depend on the access of individual nanowires to the cell interior. Recent results on electrical access and molecular delivery suggest that direct access is not always obtained. Here, we present a generic approach to directly visualize the membrane conformation of living cells interfaced with nanowire arrays, with single nanowire resolution. The method combines confocal z-stack imaging with an optimized cell membrane labelling strategy which was applied to HEK293 cells interfaced with 2-11 μm long and 3-7 μm spaced nanowires with various surface coatings (bare, aminosilane-coated or polyethyleneimine-coated indium arsenide). We demonstrate that, for all commonly used nanowire lengths, spacings and surface coatings, nanowires generally remain enclosed in a membrane compartment, and are thereby not in direct contact with the cell interior.

  14. Quantification of individual phenolic compounds' contribution to antioxidant capacity in apple: a novel analytical tool based on liquid chromatography with diode array, electrochemical, and charged aerosol detection.

    Science.gov (United States)

    Plaza, Merichel; Kariuki, James; Turner, Charlotta

    2014-01-15

    Phenolics, particularly from apples, hold great interest because of their antioxidant properties. In the present study, the total antioxidant capacity of different apple extracts obtained by pressurized hot water extraction (PHWE) was determined by cyclic voltammetry (CV), which was compared with the conventional antioxidant assays. To measure the antioxidant capacity of individual antioxidants present in apple extracts, a novel method was developed based on high-performance liquid chromatography (HPLC) with photodiode array (DAD), electrochemical (ECD), and charged aerosol (CAD) detection. HPLC-DAD-ECD-CAD enabled rapid, qualitative, and quantitative determination of antioxidants in the apple extracts. The main advantage of using CAD was that this detector enabled quantification of a large number of phenolics using only a few standards. The results showed that phenolic acids and flavonols were mainly responsible for the total antioxidant capacity of apple extracts. In addition, protocatechuic acid, chlorogenic acid, hyperoside, an unidentified phenolic acid, and a quercetin derivative presented the highest antioxidant capacities. PMID:24345041

  15. Ultrasensitive electrochemical immunoassay for surface array protein, a Bacillus anthracis biomarker using Au-Pd nanocrystals loaded on boron-nitride nanosheets as catalytic labels.

    Science.gov (United States)

    Sharma, Mukesh Kumar; Narayanan, J; Pardasani, Deepak; Srivastava, Divesh N; Upadhyay, Sanjay; Goel, Ajay Kumar

    2016-06-15

    Bacillus anthracis, the causative agent of anthrax, is a well known bioterrorism agent. The determination of surface array protein (Sap), a unique biomarker for B. anthracis can offer an opportunity for specific detection of B. anthracis in culture broth. In this study, we designed a new catalytic bionanolabel and fabricated a novel electrochemical immunosensor for ultrasensitive detection of B. anthracis Sap antigen. Bimetallic gold-palladium nanoparticles were in-situ grown on poly (diallyldimethylammonium chloride) functionalized boron nitride nanosheets (Au-Pd NPs@BNNSs) and conjugated with the mouse anti-B. anthracis Sap antibodies (Ab2); named Au-Pd NPs@BNNSs/Ab2. The resulting Au-Pd NPs@BNNSs/Ab2 bionanolabel demonstrated high catalytic activity towards reduction of 4-nitrophenol. The sensitivity of the electrochemical immunosensor along with redox cycling of 4-aminophenol to 4-quinoneimine was improved to a great extent. Under optimal conditions, the proposed immunosensor exhibited a wide working range from 5 pg/mL to 100 ng/mL with a minimum detection limit of 1 pg/mL B. anthracis Sap antigen. The practical applicability of the immunosensor was demonstrated by specific detection of Sap secreted by the B. anthracis in culture broth just after 1h of growth. These labels open a new direction for the ultrasensitive detection of different biological warfare agents and their markers in different matrices. PMID:26874112

  16. Preparation of SnO2@C-doping TiO2 nanotube arrays and its electrochemical and photoelectrochemical properties

    International Nuclear Information System (INIS)

    Highlights: ► SnO2 nanoparticels synthesized by hydrothermal method were loaded on carbon doping TiO2NTs. ► SnO2@C-TiO2NTs showed optimal electrochemical and photoelectrochemical properties due to the heterojunction formed at the interface and the synergistic effect of the electrode. -- Abstract: SnO2@carbon-doping TiO2 nanotube arrays (SnO2@C-TiO2NTs) were synthesized by hydrothermal method and evaluated for lithium ion insertion and photoelectrochemical activity. The composite electrode prepared for 5 h as anode materials for lithium-ion batteries exhibited much improved electrochemical performance due to the aligned pore structure and the synergistic effect of the electrode. A capacity of 142 μA h cm−2 can be obtained after 50 discharge/charge cycles at a high current density of 200 μA cm−2. Moreover, UV–vis results of the sample showed stronger absorption intensity in the range of 200–800 nm compared with bare TiO2NTs. The composite electrode displayed the maximum photocurrent density of 1.80 mA cm−2. This is attributed to the heterojunction formed at the interface between SnO2 and TiO2NTs resulting the enhance charge separation efficiency. Eletrochemical impendence spectroscopy (EIS) also shows that SnO2@C-TiO2 NTs has a noticeably lower charge-transfer resistance

  17. A facile one-step electrochemical strategy of doping iron, nitrogen, and fluorine into titania nanotube arrays with enhanced visible light photoactivity

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Zulin; Dai, Zhangyan [Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098 (China); Bai, Xue, E-mail: baixue10@tsinghua.org.cn [Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098 (China); Ye, Zhengfang [Key Laboratory of Water and Sediment Sciences of the Ministry of Education, Department of Environmental Engineering, Peking University, Beijing 100871 (China); Gu, Haixin; Huang, Xin [Key Laboratory of Integrated Regulation and Resource Development on Shallow Lake of Ministry of Education, College of Environment, Hohai University, Nanjing 210098 (China)

    2015-08-15

    Highlights: • Fe, N, F tri-doped TiO{sub 2} was prepared by a facile one-step electrochemical method. • Fe, N, F tri-doping resulted in a synergetic effect for the enhanced photoactivity. • The formation of N 2p near the valence band contributed to visible light absorption. • Doping fluorine and Fe{sup 3+} ions reduced the recombination of photogenerated e{sup −}–h{sup +}. • The synergistic effect in Fe, N, F tri-doping was confirmed by XPS and FTIR. - Abstract: Highly ordered iron, nitrogen, and fluorine tri-doped TiO{sub 2} (Fe, (N, F)-TiO{sub 2}) nanotube arrays were successfully synthesized by a facile one-step electrochemical method in an NH{sub 4}F electrolyte containing Fe ions. The morphology, structure, composition, and photoelectrochemical property of the as-prepared nanotube arrays were characterized by various methods. The photoactivities of the samples were evaluated by the degradation of phenol in an aqueous solution under visible light. Tri-doped TiO{sub 2} showed higher photoactivities than undoped TiO{sub 2} under visible light. The optimum Fe{sup 3+} doping amount at 0.005 M exhibited the highest photoactivity and exceeded that of undoped TiO{sub 2} by a factor of 20 times under visible light. The formation of N 2p level near the valence band (VB) contributed to visible light absorption. Doping fluorine and appropriate Fe{sup 3+} ions reduced the photogenerated electrons–holes recombination rate and enhanced visible light photoactivity. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results indicated the presence of synergistic effects in Fe, N, and F tri-doped TiO{sub 2}, which enhanced visible light photoactivity. The Fe, (N, F)-TiO{sub 2} photocatalyst exhibited high stability.

  18. More than a feeling: incidental learning of array geometry by blindfolded adult humans revealed through touch.

    Science.gov (United States)

    Sturz, Bradley R; Green, Marshall L; Gaskin, Katherine A; Evans, Alicia C; Graves, April A; Roberts, Jonathan E

    2013-02-15

    View-based matching theories of orientation suggest that mobile organisms encode a visual memory consisting of a visual panorama from a target location and maneuver to reduce discrepancy between current visual perception and this stored visual memory to return to a location. Recent success of such theories to explain the orientation behavior of insects and birds raises questions regarding the extent to which such an explanation generalizes to other species. In the present study, we attempted to determine the extent to which such view-based matching theories may explain the orientation behavior of a mammalian species (in this case adult humans). We modified a traditional enclosure orientation task so that it involved only the use of the haptic sense. The use of a haptic orientation task to investigate the extent to which view-based matching theories may explain the orientation behavior of adult humans appeared ideal because it provided an opportunity for us to explicitly prohibit the use of vision. Specifically, we trained disoriented and blindfolded human participants to search by touch for a target object hidden in one of four locations marked by distinctive textural cues located on top of four discrete landmarks arranged in a rectangular array. Following training, we removed the distinctive textural cues and probed the extent to which participants learned the geometry of the landmark array. In the absence of vision and the trained textural cues, participants showed evidence that they learned the geometry of the landmark array. Such evidence cannot be explained by an appeal to view-based matching strategies and is consistent with explanations of spatial orientation related to the incidental learning of environmental geometry. PMID:23125340

  19. Genome-wide array comparative genomic hybridization analysis reveals distinct amplifications in osteosarcoma

    International Nuclear Information System (INIS)

    Osteosarcoma is a highly malignant bone neoplasm of children and young adults. It is characterized by extremely complex karyotypes and high frequency of chromosomal amplifications. Currently, only the histological response (degree of necrosis) to therapy represent gold standard for predicting the outcome in a patient with non-metastatic osteosarcoma at the time of definitive surgery. Patients with lower degree of necrosis have a higher risk of relapse and poor outcome even after chemotherapy and complete resection of the primary tumor. Therefore, a better understanding of the underlying molecular genetic events leading to tumor initiation and progression could result in the identification of potential diagnostic and therapeutic targets. We used a genome-wide screening method – array based comparative genomic hybridization (array-CGH) to identify DNA copy number changes in 48 patients with osteosarcoma. We applied fluorescence in situ hybridization (FISH) to validate some of amplified clones in this study. Clones showing gains (79%) were more frequent than losses (66%). High-level amplifications and homozygous deletions constitute 28.6% and 3.8% of tumor genome respectively. High-level amplifications were present in 238 clones, of which about 37% of them showed recurrent amplification. Most frequently amplified clones were mapped to 1p36.32 (PRDM16), 6p21.1 (CDC5L, HSPCB, NFKBIE), 8q24, 12q14.3 (IFNG), 16p13 (MGRN1), and 17p11.2 (PMP22 MYCD, SOX1,ELAC27). We validated some of the amplified clones by FISH from 6p12-p21, 8q23-q24, and 17p11.2 amplicons. Homozygous deletions were noted for 32 clones and only 7 clones showed in more than one case. These 7 clones were mapped to 1q25.1 (4 cases), 3p14.1 (4 cases), 13q12.2 (2 cases), 4p15.1 (2 cases), 6q12 (2 cases), 6q12 (2 cases) and 6q16.3 (2 cases). This study clearly demonstrates the utility of array CGH in defining high-resolution DNA copy number changes and refining amplifications. The resolution of array CGH

  20. Independent component analysis reveals new and biologically significant structures in micro array data

    Directory of Open Access Journals (Sweden)

    Veerla Srinivas

    2006-06-01

    Full Text Available Abstract Background An alternative to standard approaches to uncover biologically meaningful structures in micro array data is to treat the data as a blind source separation (BSS problem. BSS attempts to separate a mixture of signals into their different sources and refers to the problem of recovering signals from several observed linear mixtures. In the context of micro array data, "sources" may correspond to specific cellular responses or to co-regulated genes. Results We applied independent component analysis (ICA to three different microarray data sets; two tumor data sets and one time series experiment. To obtain reliable components we used iterated ICA to estimate component centrotypes. We found that many of the low ranking components indeed may show a strong biological coherence and hence be of biological significance. Generally ICA achieved a higher resolution when compared with results based on correlated expression and a larger number of gene clusters with significantly enriched for gene ontology (GO categories. In addition, components characteristic for molecular subtypes and for tumors with specific chromosomal translocations were identified. ICA also identified more than one gene clusters significant for the same GO categories and hence disclosed a higher level of biological heterogeneity, even within coherent groups of genes. Conclusion Although the ICA approach primarily detects hidden variables, these surfaced as highly correlated genes in time series data and in one instance in the tumor data. This further strengthens the biological relevance of latent variables detected by ICA.

  1. Planar electrochemical device assembly

    Science.gov (United States)

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2007-06-19

    A pre-fabricated electrochemical device having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films is bonded to a porous electrically conductive support. A second porous electrically conductive support may be bonded to a counter electrode of the electrochemical device. Multiple electrochemical devices may be bonded in parallel to a single porous support, such as a perforated sheet to provide a planar array. Planar arrays may be arranged in a stacked interconnected array. A method of making a supported electrochemical device is disclosed wherein the method includes a step of bonding a pre-fabricated electrochemical device layer to an existing porous metal or porous metal alloy layer.

  2. Localized seismic deformation in the upper mantle revealed by dense seismic arrays

    Science.gov (United States)

    Inbal, Asaf; Ampuero, Jean Paul; Clayton, Robert W.

    2016-10-01

    Seismicity along continental transform faults is usually confined to the upper half of the crust, but the Newport-Inglewood fault (NIF), a major fault traversing the Los Angeles basin, is seismically active down to the upper mantle. We use seismic array analysis to illuminate the seismogenic root of the NIF beneath Long Beach, California, and identify seismicity in an actively deforming localized zone penetrating the lithospheric mantle. Deep earthquakes, which are spatially correlated with geochemical evidence of a fluid pathway from the mantle, as well as with a sharp vertical offset in the lithosphere-asthenosphere boundary, exhibit narrow size distribution and weak temporal clustering. We attribute these characteristics to a transition from strong to weak interaction regimes in a system of seismic asperities embedded in a ductile fault zone matrix.

  3. Allele-specific amplification in cancer revealed by SNP array analysis.

    Directory of Open Access Journals (Sweden)

    Thomas LaFramboise

    2005-11-01

    Full Text Available Amplification, deletion, and loss of heterozygosity of genomic DNA are hallmarks of cancer. In recent years a variety of studies have emerged measuring total chromosomal copy number at increasingly high resolution. Similarly, loss-of-heterozygosity events have been finely mapped using high-throughput genotyping technologies. We have developed a probe-level allele-specific quantitation procedure that extracts both copy number and allelotype information from single nucleotide polymorphism (SNP array data to arrive at allele-specific copy number across the genome. Our approach applies an expectation-maximization algorithm to a model derived from a novel classification of SNP array probes. This method is the first to our knowledge that is able to (a determine the generalized genotype of aberrant samples at each SNP site (e.g., CCCCT at an amplified site, and (b infer the copy number of each parental chromosome across the genome. With this method, we are able to determine not just where amplifications and deletions occur, but also the haplotype of the region being amplified or deleted. The merit of our model and general approach is demonstrated by very precise genotyping of normal samples, and our allele-specific copy number inferences are validated using PCR experiments. Applying our method to a collection of lung cancer samples, we are able to conclude that amplification is essentially monoallelic, as would be expected under the mechanisms currently believed responsible for gene amplification. This suggests that a specific parental chromosome may be targeted for amplification, whether because of germ line or somatic variation. An R software package containing the methods described in this paper is freely available at http://genome.dfci.harvard.edu/~tlaframb/PLASQ.

  4. Substrate-free fabrication of self-supported V2O5 nanobelt arrays by a low-temperature solvothermal method with high electrochemical performance

    Science.gov (United States)

    Xu, Haitao; Zhang, Huijuan; Liu, Li; Fang, Ling; Wang, Yu

    2016-08-01

    In the designed synthesis, self-supported NH4V3O8 nanobelt arrays were prepared via a low-temperature solvothermal method. Then the NH4V3O8 nanobelt arrays were calcined in air atmosphere. Finally, a self-supported pattern of oriented V2O5 nanobelts was obtained for the first time. Further characterization methods certified that the growth direction of NH4V3O8 nanobelts was perpendicular to the orientation plane of self-formed NH4V3O8 sheet-like substrates. As a result, the nanobelts should stretch easily on the sheet-like substrate in an oriented manner. We prove that the solvent of ethanol plays a key role in the reaction and crystal growth process. It balances the two competing oxolation and olation reactions. Furthermore, the unique pattern served as high performance a lithium-ion battery and supercapacitor. Overall, the excellent electrochemical performances, for example, outstanding rate stability, remarkable cycling capacitance and ultrahigh capacity verify that the self-supported alignments have great potential applications in lithium-ion batteries and supercapacitors.

  5. Nylon Filter Arrays Reveal Differential Expression of Expressed Sequence Tags in Wheat Roots Under Aluminum Stress

    Institute of Scientific and Technical Information of China (English)

    Kai XIAO; Gui-Hua BAI; Brett F CARVER

    2005-01-01

    To enrich differentially expressed sequence tags (ESTs) for aluminum (Al) tolerance, cDNA subtraction libraries were generated from Al-stressed roots of two wheat (Triticum aestivum L.) nearisogenic lines (NILs) contrasting in Al-tolerance gene(s) from the Al-tolerant cultivar Atlas 66, using suppression subtractive hybridization (SSH). Expression patterns of the ESTs were investigated with nylon filter arrays containing 614 cDNA clones from the subtraction library. Gene expression profiles from macroarray analysis indicated that 25 ESTs were upregulated in the tolerant NIL in response to Al stress. The result from Northern analysis of selected upregulated ESTs was similar to that from macroarray analysis. These highly expressed ESTs showed high homology with genes involved in signal transduction, oxidative stress alleviation, membrane structure, Mg2+ transportation, and other functions. Under Al stress, the Al-tolerant NIL may possess altered structure or function of the cell wall, plasma membrane, and mitochondrion. The wheat response to Al stress may involve complicated defense-related signaling and metabolic pathways.The present experiment did not detect any induced or activated genes involved in the synthesis of malate and other organic acids in wheat under Al-stress.

  6. Electrochemical pore filling strategy for controlled growth of magnetic and metallic nanowire arrays with large area uniformity

    Science.gov (United States)

    Arefpour, M.; Almasi Kashi, M.; Ramazani, A.; Montazer, A. H.

    2016-07-01

    While a variety of template-based strategies have been developed in the fabrication of nanowires (NWs), a uniform pore filling across the template still poses a major challenge. Here, we present a large area controlled pore filling strategy in the reproducible fabrication of various magnetic and metallic NW arrays, embedded inside anodic aluminum oxide templates. Using a diffusive pulsed electrodeposition (DPED) technique, this versatile strategy relies on the optimized filling of branched nanopores at the bottom of templates with Cu. Serving the Cu filled nanopores as appropriate nucleation sites, the DPED is followed by a uniform and homogeneous deposition of magnetic (Ni and Fe) and metallic (Cu and Zn) NWs at a current density of 50 mA cm-2 for an optimal thickness of alumina barrier layer (˜18 nm). Our strategy provides large area uniformity (exceeding 400 μm2) in the fabrication of 16 μm long free-standing NW arrays. Using hysteresis loop measurements and scanning electron microscopy images, the electrodeposition efficiency (EE) and pore filling percentage (F p) are evaluated, leading to maximum EE and F p values of 91% and 95% for Ni and Zn, respectively. Moreover, the resulting NW arrays are found to be highly crystalline. Accordingly, the DPED technique is capable of cheaply and efficiently controlling NW growth over a large area, providing a tool for various nanoscale applications including biomedical devices, electronics, photonics, magnetic storage medium and nanomagnet computing.

  7. SNP array analysis reveals novel genomic abnormalities including copy neutral loss of heterozygosity in anaplastic oligodendrogliomas.

    Directory of Open Access Journals (Sweden)

    Ahmed Idbaih

    Full Text Available Anaplastic oligodendrogliomas (AOD are rare glial tumors in adults with relative homogeneous clinical, radiological and histological features at the time of diagnosis but dramatically various clinical courses. Studies have identified several molecular abnormalities with clinical or biological relevance to AOD (e.g. t(1;19(q10;p10, IDH1, IDH2, CIC and FUBP1 mutations.To better characterize the clinical and biological behavior of this tumor type, the creation of a national multicentric network, named "Prise en charge des OLigodendrogliomes Anaplasiques (POLA," has been supported by the Institut National du Cancer (InCA. Newly diagnosed and centrally validated AOD patients and their related biological material (tumor and blood samples were prospectively included in the POLA clinical database and tissue bank, respectively.At the molecular level, we have conducted a high-resolution single nucleotide polymorphism array analysis, which included 83 patients. Despite a careful central pathological review, AOD have been found to exhibit heterogeneous genomic features. A total of 82% of the tumors exhibited a 1p/19q-co-deletion, while 18% harbor a distinct chromosome pattern. Novel focal abnormalities, including homozygously deleted, amplified and disrupted regions, have been identified. Recurring copy neutral losses of heterozygosity (CNLOH inducing the modulation of gene expression have also been discovered. CNLOH in the CDKN2A locus was associated with protein silencing in 1/3 of the cases. In addition, FUBP1 homozygous deletion was detected in one case suggesting a putative tumor suppressor role of FUBP1 in AOD.Our study showed that the genomic and pathological analyses of AOD are synergistic in detecting relevant clinical and biological subgroups of AOD.

  8. Liquid crystalline phase synthesis of nanoporous MnO2 thin film arrays as an electrode material for electrochemical capacitors

    International Nuclear Information System (INIS)

    Graphical abstract: Three-dimensional (3D) MnO2 thin film arrays with nanoporous structure is electrodeposited on Ti foil from hexagonal lyotropic liquid crystalline phase. Low-angle X-ray diffraction (XRD), wide-angle XRD, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) are employed to study the morphology and the structure of the as-synthesized MnO2 materials. Galvanostatic charge/discharge measurements show the nanoporous, 3D electrode material exhibits excellent capacitive performance between the potential range of −0.1 to 0.9 V, and a maximum specific capacitance as high as 462 F g−1 are achieved in 0.5 M Na2SO4 solution at a charge/discharge current density of 4 A g−1. Highlights: ► 3D MnO2 thin film arrays with nanoporous structure is fabricated for the first time. ► A maximum specific capacitance as high as 462 F g−1 is obtained. ► The 3D and nanoporous superarchitecture facilitate electrolyte penetration. -- Abstract: Three-dimensional (3D) MnO2 thin film arrays with nanoporous structure is electrodeposited on Ti foil from hexagonal lyotropic liquid crystalline phase. Low-angle X-ray diffraction (XRD), wide-angle XRD, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) are employed to study the morphology and the structure of the as-synthesized MnO2 materials. Galvanostatic charge/discharge measurements show the nanoporous, 3D electrode material exhibits excellent capacitive performance between the potential range of −0.1 to 0.9 V, and a maximum specific capacitance as high as 462 F g−1 are achieved in 0.5 M Na2SO4 solution at a charge/discharge current density of 4 A g−1.

  9. Electrochemical Performance of Three-Dimensional Microelectrode Arrays%三维微柱阵列电极的电化学性能

    Institute of Scientific and Technical Information of China (English)

    王晓峰; 李翔宇; 陈学坤; 周扬; 尤政

    2012-01-01

    With the development of MEMS technology,the worldwide thirst for electric products in microscale has an enormous impact on micro-power.The MEMS super-capacitor is one of the most important parts for micro-powers.In this paper,RuO2 microelectrode arrays were fabricated and tested by scanning electron microscopy (SEM),cyclic voltammetry (CV),and electrochemical impedance spectroscopy (EIS).These posts were 50 μm in diameter and 100 pm in height,with the foot print area of 2 mm×2 mm.The capacitance was 2.43 F/cm2.These 3-D microelectrode arrays exhibited satisfactory electrochemical performance.The performance of micro-super capacitors on 3-D microstructure was shown to offer significant advantages,such as small areal footprint and short diffusion lengths,in comparison with that on 2-D microelectrode.%随着MEMS技术的发展,对微纳尺寸器件的需求日益凸显,微能源的研究变得尤为重要,而微型超级电容器则是其中一种基于电化学电容实现储能的微型能量存储器件.设计了一种基于氧化钌功能薄膜的三维微柱阵列电极,并进行了相关的扫描电镜(SEM)、循环伏安(CV)和交流阻抗谱(EIS)测试.测试表明在2mm×2mm的硅片上,直径为50μm、高为100 μm的三维微柱阵列电极的比电容为2.43 F/cm2,具有良好的电化学性能.与同容量的二维平面电极相比,基于三维结构的微型超级电容器具有明显的小尺寸优势.

  10. An array of asymmetries in Saturn's structure revealed by its rings

    Science.gov (United States)

    Hedman, Matthew M.; Nicholson, Philip D.; El Moutamid, Maryame; Graven, Stephanie

    2016-05-01

    Previous investigations of high-resolution stellar occultation data obtained by the Cassini spacecraft have revealed that Saturn's C ring contains numerous density waves that are probably generated by structures inside the planet. In particular, five features were attributed to long-lived asymmetries in the planet's gravity field because they had pattern speeds similar to the range of rotation rates found in Saturn's winds. Using wavelet-based techniques, we have performed a more comprehensive search for similar structures, and found that the above five waves are just the most obvious members of an entire population of ring disturbances spread over several thousand kilometers of the C ring. These structures should provide new insights into the dynamics of Saturn's deep atmosphere.

  11. Thin-film microelectric arrays for amperometric enzyme biosensors with electrochemically synthesized glucose oxidase-polyaniline membrane

    Science.gov (United States)

    Dzyadevich, Sergei V.; Rossokhaty, Victor K.; Shram, Nataly; Shul'ga, Alexander A.; Soldatkin, Alexey P.; Strikha, Vitaly I.

    1994-10-01

    An amperometric glucose biosensor was fabricated by the electrochemical polymerization of aniline onto a gold electrodes in presence of glucose oxidase in phosphate buffer solution, pH 7.0. Aniline is easily polymerized forming a thin film, which adheres tightly on the electrodes surface. During the electropolymerization process the enzyme was entrapped into the polyaniline film being able to catalyze the hydrolysis of glucose. The experiments were performed to determine the optimal condition for polyaniline-glucose oxidase film preparation. Glucose can be determined by the biosensor in the concentration range 10-4 M to 2 X 10-2 M. The linearity of the biosensor response was observed from 2 X 10-4 M to 6 X 10-3 M glucose, which demonstrated that the internal diffusion of substrates and products of reaction through the polyaniline layer to the electrodes surface was the main limiting factor controlling the response value. The method of electropolymerization was found to have several advantage in comparison with other approaches especially for further mass manufacturing of the biosensors.

  12. Electrochemical impedance spectroscopy to study photo - induced effects on self-organized TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Pu, P.; Cachet, H. [CNRS, UPR15, Laboratoire Interfaces et Systemes Electrochimiques, F-75005 Paris (France); UPMC Univ Paris 06, UPR15, LISE, 4 place Jussieu, F-75005 Paris (France); Sutter, E.M.M., E-mail: eliane-sutter@upmc.f [CNRS, UPR15, Laboratoire Interfaces et Systemes Electrochimiques, F-75005 Paris (France); UPMC Univ Paris 06, UPR15, LISE, 4 place Jussieu, F-75005 Paris (France)

    2010-08-01

    Two different morphologies of nano-structured titanium dioxide-a nanotubular layer and a compact layer - were obtained by anodization of titanium in fluoride-based baths, and the photo-induced effects of these layers were investigated by electrochemical impedance spectroscopy (EIS). The first layer showed long-lasting photo-induced modifications after UV illumination, whereas, in the case of the compact layer, no long-lasting UV-induced modifications were observed. Before light exposure, in the nanotubular layer, only the bottom of the tubes were electro-active and contributed to the conduction of the layer. Moreover an exponential distribution of surface states could be evidenced. After UV exposure, the surface states were filled by the photo-generated electrons, leading to activation of the walls of the tubes by inserted hydrogen, and to a hundred fold increase in the space charge layer capacitance. This capacitance increase was attributed to an increase in the active surface of the layer, but also to an increase in the charge carrier density.

  13. A microfluidic platform reveals differential response of regulatory T cells to micropatterned costimulation arrays.

    Science.gov (United States)

    Lee, Joung-Hyun; Dustin, Michael L; Kam, Lance C

    2015-11-01

    T cells are key mediators of adaptive immunity. However, the overall immune response is often directed by minor subpopulations of this heterogeneous family of cells, owing to specificity of activation and amplification of functional response. Knowledge of differences in signaling and function between T cell subtypes is far from complete, but is clearly needed for understanding and ultimately leveraging this branch of the adaptive immune response. This report investigates differences in cell response to micropatterned surfaces by conventional and regulatory T cells. Specifically, the ability of cells to respond to the microscale geometry of TCR/CD3 and CD28 engagement is made possible using a magnetic-microfluidic device that overcomes limitations in imaging efficiency associated with conventional microscopy equipment. This device can be readily assembled onto micropatterned surfaces while maintaining the activity of proteins and other biomolecules necessary for such studies. In operation, a target population of cells is tagged using paramagnetic beads, and then trapped in a divergent magnetic field within the chamber. Following washing, the target cells are released to interact with a designated surface. Characterization of this system with mouse CD4(+) T cells demonstrated a 50-fold increase in target-to-background cell purity, with an 80% collection efficiency. Applying this approach to CD4(+)CD25(+) regulatory T cells, it is then demonstrated that these rare cells respond less selectively to micro-scale features of anti-CD3 antibodies than CD4(+)CD25(-) conventional T cells, revealing a difference in balance between TCR/CD3 and LFA-1-based adhesion. PKC-θ localized to the distal pole of regulatory T cells, away from the cell-substrate interface, suggests a mechanism for differential regulation of TCR/LFA-1-based adhesion. Moreover, specificity of cell adhesion to anti-CD3 features was dependent on the relative position of anti-CD28 signaling within the cell

  14. Carbon- and Binder-Free NiCo2O4 Nanoneedle Array Electrode for Sodium-Ion Batteries: Electrochemical Performance and Insight into Sodium Storage Reaction

    Science.gov (United States)

    Lee, Jong-Won; Shin, Hyun-Sup; Lee, Chan-Woo; Jung, Kyu-Nam

    2016-02-01

    Sodium (Na)-ion batteries (NIBs) have attracted significant interest as an alternative chemistry to lithium (Li)-ion batteries for large-scale stationary energy storage systems. Discovering high-performance anode materials is a great challenge for the commercial success of NIB technology. Transition metal oxides with tailored nanoarchitectures have been considered as promising anodes for NIBs due to their high capacity. Here, we demonstrate the fabrication of a nanostructured oxide-only electrode, i.e., carbon- and binder-free NiCo2O4 nanoneedle array (NCO-NNA), and its feasibility as an anode for NIBs. Furthermore, we provide an in-depth experimental study of the Na storage reaction (sodiation and desodiation) in NCO-NNA. The NCO-NNA electrode is fabricated on a conducting substrate by a hydrothermal method with subsequent heat treatment. When tested in an electrochemical Na half-cell, the NCO-NNA electrode exhibits excellent Na storage capability: a charge capacity as high as 400 mAh g-1 is achieved at a current density of 50 mA g-1. It also shows a greatly improved cycle life (~215 mAh g-1 after 50 cycles) in comparison to a conventional powder-type electrode (~30 mAh g-1). However, the Na storage performance is still inferior to that of Li, which is mainly due to sluggish kinetics of sodiation-desodiation accompanied by severe volume change.

  15. Effect of AZO Substrates on Self-Seeded Electrochemical Growth of Vertically Aligned ZnO Nanorod Arrays and Their Optical Properties

    Directory of Open Access Journals (Sweden)

    A. Peić

    2012-01-01

    Full Text Available We present a single step and an electrochemical synthesis of vertically aligned ZnO nanorod (NR arrays, directly on transparent aluminium-doped zinc oxide (AZO electrodes. The NRs grow from mild, aqueous-based solution at low temperature, with no need for catalysts or additional seed layer. The use of textured AZO as substrate allows for highly effective growth of hexagonally faceted, single-crystalline ZnO NRs along the wurtzite c-axis. The matching of the crystal lattices initiates a self-seeding route, thus the inherent growth habit of the AZO crystallites advances the vertical growth and alignment of NRs. Moreover, the thickness-dependant grain size of the AZO layer provides a valuable feature for tuning the diameter of ZnO NRs grown atop. In the absence of any seed mediator, the interfacial quality is expected to improve significantly. This should enhance the thermal and electrical transport throughout the whole nanostructured transparent electrode. The NR growth was investigated under systematic manipulation of the synthesis variables in order to optimize growth conditions for highly aligned, single-crystalline NRs with a large aspect ratio and a good optical quality. The structure and optical property of the AZO/ZnO NR ensembles were characterized by atomic force microscopy, scanning electron microscopy, X-ray diffraction, photoluminescence, and ultraviolet-visible transmission spectroscopy.

  16. Enhanced photocatalytic, electrochemical and photoelectrochemical properties of TiO2 nanotubes arrays modified with Cu, AgCu and Bi nanoparticles obtained via radiolytic reduction

    Science.gov (United States)

    Nischk, Michał; Mazierski, Paweł; Wei, Zhishun; Siuzdak, Katarzyna; Kouame, Natalie Amoin; Kowalska, Ewa; Remita, Hynd; Zaleska-Medynska, Adriana

    2016-11-01

    TiO2 nanotubes arrays (NTs), obtained via electrochemical anodization of Ti foil, were modified with monometallic (Cu, Bi) and bimetallic (AgCu) nanoparticles. Different amounts of metals' precursors were deposited on the surface of NTs by the spin-coating technique, and the reduction of metals was performed via gamma radiolysis. Surface modification of titania was studied by EDS and XPS analysis. The results show that AgCu nanoparticles exist in a Agcore-Cushell form. Photocatalytic activity was examined under UV irradiation and phenol was used as a model pollutant of water. Over 95% of phenol degradation was achieved after 60 min of irradiation for almost all examined samples, but only slight difference in degradation efficiency (about 3%) between modified and bare NTs was observed. However, the initial phenol degradation rate and TOC removal efficiency was significantly enhanced for the samples modified with 0.31 and 0.63 mol% of Bi as well as for all the samples modified with Cu and AgCu nanoparticles in comparison with bare titania nanotubes. The saturated photocurrent, under the influence of simulated solar light irradiation, for the most active Bi- and AgCu-modified samples, was over two times higher than for pristine NTs. All the examined materials were resistant towards photocorrosion processes that enables their application for long term processes induced by light.

  17. Electrochemical impedance analysis of electrodeposited Si-O-C composite thick film on Cu microcones-arrayed current collector for lithium ion battery anode

    Science.gov (United States)

    Hang, Tao; Mukoyama, Daikichi; Nara, Hiroki; Yokoshima, Tokihiko; Momma, Toshiyuki; Li, Ming; Osaka, Tetsuya

    2014-06-01

    The impedance behaviors of Si-O-C composite film electrodeposited on Cu microcones-arrayed current collector have been investigated to understand the electrochemical process kinetics that influences the cycling performance when used as a highly-durable anode in a lithium battery. The impedance was measured by using impedance spectroscopy in equilibrium conditions at various depths of discharge and during several hundred charge-discharge cycles. The measured impedance was interpreted with an equivalent circuit composed of solid electrolyte interphase (SEI) film, charge transfer and solid state diffusion. The impedance analysis shows that the change of charge transfer resistance is the main contribution to the total resistance change during discharge, but an abrupt augmentation of diffusive resistance at high depth of discharge is also observed which cannot be explained very well by the presented model. The impedance evolution of this electrode during charge-discharge cycles suggests that the slow growth of the SEI film as well as the increase of the electrode density are responsible for the capacity fading after long term cycling.

  18. An Electrochemical Microsensor Based on a AuNPs-Modified Microband Array Electrode for Phosphate Determination in Fresh Water Samples

    Directory of Open Access Journals (Sweden)

    Fangfang Wang

    2014-12-01

    Full Text Available This work describes the fabrication, characterization, and application of a gold microband array electrode (MAE for the determination of phosphate in fresh water samples. The working principle of this MAE is based on the reduction of a molybdophosphate complex using the linear sweep voltammetric (LSV method. The calibration of this microsensor was performed with standard phosphate solutions prepared with KH2PO4 and pH adjusted to 1.0. The microsensor consists of a platinum counter electrode, a gold MAE as working electrode, and an Ag/AgCl electrode as reference electrode. The microelectrode chips were fabricated by the Micro Electro-Mechanical System (MEMS technique. To improve the sensitivity, gold nanoparticles (AuNPs were electrodeposited on the working electrode. With a linear range from 0.02 to 0.50 mg P/L, the sensitivity of the unmodified microsensor is 2.40 µA per (mg P/L (R2 = 0.99 and that of the AuNPs-modified microsensor is 7.66 µA per (mg P/L (R2 = 0.99. The experimental results showed that AuNPs-modified microelectrode had better sensitivity and a larger current response than the unmodified microelectrode.

  19. The non-specific inhibition of enzymes by environmental pollutants: a study of a model system towards the development of electrochemical biosensor arrays.

    Science.gov (United States)

    Young, S J; Hart, J P; Dowman, A A; Cowell, D C

    2001-12-01

    Previous research has shown that lactate dehydrogenase (LDH) was competitively inhibited by pentachlorophenol (PCP) and a modified assay produced a detection limit of 1 microM (270 microg l(-1)). This work used spectrophotometric rate-determination but in order to move towards biosensor development the selected detection method was electrochemical. The linkage of LDH to lactate oxidase (LOD) provided the electroactive species, hydrogen peroxide. This could be monitored using a screen-printed carbon electrode (SPCE) incorporating the mediator, cobalt phthalocyanine, at a potential of +300 mV (vs. Ag/AgCl). A linked LDH/LOD system was optimised with respect to inhibition by PCP. It was found that the SPCE support material, PVC, acted to reduce inhibition, possibly by combining with PCP. A cellulose acetate membrane removed this effect. Inhibition of the system was greatest at enzyme activities of 5 U ml(-1) LDH and 0.8 U ml(-1) LOD in reactions containing 246 microM pyruvate and 7.5 microM NADPH. PCP detection limits were an EC(10) of 800 nM (213 microg l(-1)) and a minimum inhibition detectable (MID) limit of 650 nM (173 microg l(-1)). The inclusion of a third enzyme, glucose dehydrogenase (GDH), provided cofactor recycling to enable low concentrations of NADPH to be incorporated within the assay. NADPH was reduced from 7.5 to 2 microM. PCP detection limits were obtained for an assay containing 5 U ml(-1) LDH, 0.8 U ml(-1) LOD and 0.1 U ml(-1) GDH with 246 microM pyruvate, 400 mM glucose and 2 microM NADPH. The EC(10) limit was 150 nM (39.9 microg l(-1)) and the MID was 100 nM (26.6 microg l(-1)). The design of the inhibition assays discussed has significance as a model for other enzymes and moves forward the possibility of an electrochemical biosensor array for pollution monitoring. PMID:11679267

  20. Carbon- and Binder-Free NiCo2O4 Nanoneedle Array Electrode for Sodium-Ion Batteries: Electrochemical Performance and Insight into Sodium Storage Reaction.

    Science.gov (United States)

    Lee, Jong-Won; Shin, Hyun-Sup; Lee, Chan-Woo; Jung, Kyu-Nam

    2016-12-01

    Sodium (Na)-ion batteries (NIBs) have attracted significant interest as an alternative chemistry to lithium (Li)-ion batteries for large-scale stationary energy storage systems. Discovering high-performance anode materials is a great challenge for the commercial success of NIB technology. Transition metal oxides with tailored nanoarchitectures have been considered as promising anodes for NIBs due to their high capacity. Here, we demonstrate the fabrication of a nanostructured oxide-only electrode, i.e., carbon- and binder-free NiCo2O4 nanoneedle array (NCO-NNA), and its feasibility as an anode for NIBs. Furthermore, we provide an in-depth experimental study of the Na storage reaction (sodiation and desodiation) in NCO-NNA. The NCO-NNA electrode is fabricated on a conducting substrate by a hydrothermal method with subsequent heat treatment. When tested in an electrochemical Na half-cell, the NCO-NNA electrode exhibits excellent Na storage capability: a charge capacity as high as 400 mAh g(-1) is achieved at a current density of 50 mA g(-1). It also shows a greatly improved cycle life (~215 mAh g(-1) after 50 cycles) in comparison to a conventional powder-type electrode (~30 mAh g(-1)). However, the Na storage performance is still inferior to that of Li, which is mainly due to sluggish kinetics of sodiation-desodiation accompanied by severe volume change. PMID:26831683

  1. In situ NMR and electrochemical quartz crystal microbalance techniques reveal the structure of the electrical double layer in supercapacitors.

    Science.gov (United States)

    Griffin, John M; Forse, Alexander C; Tsai, Wan-Yu; Taberna, Pierre-Louis; Simon, Patrice; Grey, Clare P

    2015-08-01

    Supercapacitors store charge through the electrosorption of ions on microporous electrodes. Despite major efforts to understand this phenomenon, a molecular-level picture of the electrical double layer in working devices is still lacking as few techniques can selectively observe the ionic species at the electrode/electrolyte interface. Here, we use in situ NMR to directly quantify the populations of anionic and cationic species within a working microporous carbon supercapacitor electrode. Our results show that charge storage mechanisms are different for positively and negatively polarized electrodes for the electrolyte tetraethylphosphonium tetrafluoroborate in acetonitrile; for positive polarization charging proceeds by exchange of the cations for anions, whereas for negative polarization, cation adsorption dominates. In situ electrochemical quartz crystal microbalance measurements support the NMR results and indicate that adsorbed ions are only partially solvated. These results provide new molecular-level insight, with the methodology offering exciting possibilities for the study of pore/ion size, desolvation and other effects on charge storage in supercapacitors.

  2. In situ NMR and electrochemical quartz crystal microbalance techniques reveal the structure of the electrical double layer in supercapacitors

    Science.gov (United States)

    Griffin, John M.; Forse, Alexander C.; Tsai, Wan-Yu; Taberna, Pierre-Louis; Simon, Patrice; Grey, Clare P.

    2015-08-01

    Supercapacitors store charge through the electrosorption of ions on microporous electrodes. Despite major efforts to understand this phenomenon, a molecular-level picture of the electrical double layer in working devices is still lacking as few techniques can selectively observe the ionic species at the electrode/electrolyte interface. Here, we use in situ NMR to directly quantify the populations of anionic and cationic species within a working microporous carbon supercapacitor electrode. Our results show that charge storage mechanisms are different for positively and negatively polarized electrodes for the electrolyte tetraethylphosphonium tetrafluoroborate in acetonitrile; for positive polarization charging proceeds by exchange of the cations for anions, whereas for negative polarization, cation adsorption dominates. In situ electrochemical quartz crystal microbalance measurements support the NMR results and indicate that adsorbed ions are only partially solvated. These results provide new molecular-level insight, with the methodology offering exciting possibilities for the study of pore/ion size, desolvation and other effects on charge storage in supercapacitors.

  3. Micro-electrode array recordings reveal reductions in both excitation and inhibition in cultured cortical neuron networks lacking Shank3.

    Science.gov (United States)

    Lu, C; Chen, Q; Zhou, T; Bozic, D; Fu, Z; Pan, J Q; Feng, G

    2016-02-01

    Numerous risk genes have recently been implicated in susceptibility to autism and schizophrenia. Translating such genetic findings into disease-relevant neurobiological mechanisms is challenging due to the lack of throughput assays that can be used to assess their functions on an appropriate scale. To address this issue, we explored the feasibility of using a micro-electrode array (MEA) as a potentially scalable assay to identify the electrical network phenotypes associated with risk genes. We first characterized local and global network firing in cortical neurons with MEAs, and then developed methods to analyze the alternation between the network active period (NAP) and the network inactive period (NIP), each of which lasts tens of seconds. We then evaluated the electric phenotypes of neurons derived from Shank3 knockout (KO) mice. Cortical neurons cultured on MEAs displayed a rich repertoire of spontaneous firing, and Shank3 deletion led to reduced firing activity. Enhancing excitation with CX546 rescued the deficit in the spike rate in the Shank3 KO network. In addition, the Shank3 KO network produced a shorter NIP, and this altered network firing pattern was normalized by clonazepam, a positive modulator of the GABAA receptor. MEA recordings revealed electric phenotypes that displayed altered excitation and inhibition in the network lacking Shank3. Thus, our study highlights MEAs as an experimental framework for measuring multiple robust neurobiological end points in dynamic networks and as an assay system that could be used to identify electric phenotypes in cultured neuronal networks and to analyze additional risk genes identified in psychiatric genetics. PMID:26598066

  4. 电化学方法腐蚀原奥氏体晶界的研究%An electrochemical etching method to reveal prior-austenite grain boundaries

    Institute of Scientific and Technical Information of China (English)

    孙雪娇; 连福亮; 柳永宁; 朱杰武

    2014-01-01

    研究了电化学腐蚀法对X80管线钢、调质态35 CrMo钢、调质态45钢、GCr15轴承钢和超高碳钢5种钢原奥氏体晶界的显示效果。结果表明,采用配比为100 mL过饱和苦味酸+2 mL盐酸+0.5 g十二烷基苯磺酸钠+3 g硝酸钠的电解液,从开路电位沿阳极方向进行线性扫描,当扫描曲线进入钝化区时停止试验,得到的奥氏体晶界腐蚀效果最佳。电化学腐蚀法对5种试验钢的原奥氏体晶界均有良好的腐蚀效果,与常规化学腐蚀法相比,其操作过程简单,无需加热,无有毒气体散发,适用范围较广。%An electrochemical etching method was investigated to reveal prior-austenite grain boundaries in X80 pipeline steel , quenched and tempered 35CrMo steel, quenched and tempered 45 steel, GCr15 steel and ultrahigh carbon steel .The results show that, the prior-austenite grain boundaries can be shown clearly with electrolyte solution of 100 mL saturated aqueous picric acid, 2 mL hydrochloric acid, 0.5 g sodium dodecyl benzene sulfonate and 3 g sodium nitrate when the specimens are scanned towards anodic direction from open circuit potential to passive zone .The effect of electrochemical etching method on the prior-austenite grain boundaries of the five kinds of tested steels is very good.Comparing with traditional chemical etching , the electrochemical method has a simple operation process , does not need heating , has no toxic gas emissions , and has wider applicable range .

  5. Apparatus for combinatorial screening of electrochemical materials

    Science.gov (United States)

    A high throughput combinatorial screening method and apparatus for the evaluation of electrochemical materials using a single voltage source is disclosed wherein temperature changes arising from the application of an electrical load to a cell array are used to evaluate the relative electrochemical efficiency of the materials comprising the array. The apparatus may include an array of electrochemical cells that are connected to each other in parallel or in series, an electronic load for applying a voltage or current to the electrochemical cells , and a device , external to the cells, for monitoring the relative temperature of each cell when the load is applied.

    2009-12-15

    A high throughput combinatorial screening method and apparatus for the evaluation of electrochemical materials using a single voltage source (2) is disclosed wherein temperature changes arising from the application of an electrical load to a cell array (1) are used to evaluate the relative electrochemical efficiency of the materials comprising the array. The apparatus may include an array of electrochemical cells (1) that are connected to each other in parallel or in series, an electronic load (2) for applying a voltage or current to the electrochemical cells (1), and a device (3), external to the cells, for monitoring the relative temperature of each cell when the load is applied.

  6. Essential oils affect populations of some rumen bacteria in vitro as revealed by microarray (RumenBactArray) analysis

    OpenAIRE

    Patra, Amlan K.; Yu, Zhongtang

    2015-01-01

    In a previous study origanum oil (ORO), garlic oil (GAO), and peppermint oil (PEO) were shown to effectively lower methane production, decrease abundance of methanogens, and change abundances of several bacterial populations important to feed digestion in vitro. In this study, the impact of these essential oils (EOs, at 0.50 g/L) on the rumen bacterial community composition and population was further examined using the recently developed RumenBactArray. Species richness (expressed as number o...

  7. Essential oils affect populations of some rumen bacteria in vitro as revealed by microarray (RumenBactArray) analysis

    OpenAIRE

    Amlan Kumar Patra; Zhongtang eYu

    2015-01-01

    In a previous study origanum oil (ORO), garlic oil (GAO), and peppermint oil (PEO) were shown to effectively lower methane production, decrease abundance of methanogens, and change abundances of several bacterial populations important to feed digestion in vitro. In this study, the impact of these essential oils (EOs, at 0.50 g/L), on the rumen bacterial community composition and population was further examined using the recently developed RumenBactArray. Species richness (expressed as number ...

  8. Carbon-Coated SnO2 Nanorod Array for Lithium-Ion Battery Anode Material

    Directory of Open Access Journals (Sweden)

    Ji Xiaoxu

    2010-01-01

    Full Text Available Abstract Carbon-coated SnO2 nanorod array directly grown on the substrate has been prepared by a two-step hydrothermal method for anode material of lithium-ion batteries (LIBs. The structural, morphological and electrochemical properties were investigated by means of X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM and electrochemical measurement. When used as anodes for LIBs with high current density, as-obtained array reveals excellent cycling stability and rate capability. This straightforward approach can be extended to the synthesis of other carbon-coated metal oxides for application of LIBs.

  9. Clinical array-based karyotyping of breast cancer with equivocal HER2 status resolves gene copy number and reveals chromosome 17 complexity

    Directory of Open Access Journals (Sweden)

    Zadeh Soheila

    2010-07-01

    Full Text Available Abstract Background HER2 gene copy status, and concomitant administration of trastuzumab (Herceptin, remains one of the best examples of targeted cancer therapy based on understanding the genomic etiology of disease. However, newly diagnosed breast cancer cases with equivocal HER2 results present a challenge for the oncologist who must make treatment decisions despite the patient's unresolved HER2 status. In some cases both immunohistochemistry (IHC and fluorescence in situ hybridization (FISH are reported as equivocal, whereas in other cases IHC results and FISH are discordant for positive versus negative results. The recent validation of array-based, molecular karyotyping for clinical oncology testing provides an alternative method for determination of HER2 gene copy number status in cases remaining unresolved by traditional methods. Methods In the current study, DNA extracted from 20 formalin fixed paraffin embedded (FFPE tissue samples from newly diagnosed cases of invasive ductal carcinoma referred to our laboratory with unresolved HER2 status, were analyzed using a clinically validated genomic array containing 127 probes covering the HER2 amplicon, the pericentromeric regions, and both chromosome 17 arms. Results Array-based comparative genomic hybridization (array CGH analysis of chromosome 17 resolved HER2 gene status in [20/20] (100% of cases and revealed additional chromosome 17 copy number changes in [18/20] (90% of cases. Array CGH analysis also revealed two false positives and one false negative by FISH due to "ratio skewing" caused by chromosomal gains and losses in the centromeric region. All cases with complex rearrangements of chromosome 17 showed genome-wide chromosomal instability. Conclusions These results illustrate the analytical power of array-based genomic analysis as a clinical laboratory technique for resolution of HER2 status in breast cancer cases with equivocal results. The frequency of complex chromosome 17

  10. Oligonucleotide array discovery of polymorphisms in cultivated tomato (Solanum lycopersicum L. reveals patterns of SNP variation associated with breeding

    Directory of Open Access Journals (Sweden)

    Zhu Tong

    2009-10-01

    Full Text Available Abstract Background Cultivated tomato (Solanum lycopersicum L. has narrow genetic diversity that makes it difficult to identify polymorphisms between elite germplasm. We explored array-based single feature polymorphism (SFP discovery as a high-throughput approach for marker development in cultivated tomato. Results Three varieties, FL7600 (fresh-market, OH9242 (processing, and PI114490 (cherry were used as a source of genomic DNA for hybridization to oligonucleotide arrays. Identification of SFPs was based on outlier detection using regression analysis of normalized hybridization data within a probe set for each gene. A subset of 189 putative SFPs was sequenced for validation. The rate of validation depended on the desired level of significance (α used to define the confidence interval (CI, and ranged from 76% for polymorphisms identified at α ≤ 10-6 to 60% for those identified at α ≤ 10-2. Validation percentage reached a plateau between α ≤ 10-4 and α ≤ 10-7, but failure to identify known SFPs (Type II error increased dramatically at α ≤ 10-6. Trough sequence validation, we identified 279 SNPs and 27 InDels in 111 loci. Sixty loci contained ≥ 2 SNPs per locus. We used a subset of validated SNPs for genetic diversity analysis of 92 tomato varieties and accessions. Pairwise estimation of θ (Fst suggested significant differentiation between collections of fresh-market, processing, vintage, Latin American (landrace, and S. pimpinellifolium accessions. The fresh-market and processing groups displayed high genetic diversity relative to vintage and landrace groups. Furthermore, the patterns of SNP variation indicated that domestication and early breeding practices have led to progressive genetic bottlenecks while modern breeding practices have reintroduced genetic variation into the crop from wild species. Finally, we examined the ratio of non-synonymous (Ka to synonymous substitutions (Ks for 20 loci with multiple SNPs (≥ 4 per

  11. A Low Velocity Zone along the Chaochou Fault in Southern Taiwan: Seismic Image Revealed by a Linear Seismic Array

    Directory of Open Access Journals (Sweden)

    Hsin-Chieh Pu

    2010-01-01

    Full Text Available The Chaochou fault is one of the major boundary faults in southern Taiwan where strong convergence has taken place between the Eurasian and Philippine Sea plates. The surface fault trace between the Pingtung plain and the Central Range follows a nearly N-S direction and stretches to 80 km in length. In order to examine the subsurface structures along the Chaochou fault, a linear seismic array with 14 short-period stations was deployed across the fault to record seismic data between August and December 2001. Detailed examination of seismic data generated by 10 local earthquakes and recorded by the linear array has shown that the incidence angles of the first P-waves recorded by several seismic stations at the fault zone were significantly larger than those located farther away from the fault zone. This difference might reflect the lateral variation of velocity structures across the Chaochou fault. Further examination of ray-paths of seismic wave propagation indicates that a low-velocity zone along the Chaochou fault is needed to explain the significant change in incidence angles across the fault zone. Although we do not have adequate information to calculate the exact geometry of the fault zone well, the variation in incidence angles across the fault can be explained by the existence of a low-velocity zone that is about 3 km in width on the surface and extends downward to a depth of 5 km. The low-velocity zone along the Chaochou fault might imply that the fault system consists of several splay faults on the hanging wall in the Central Range.

  12. Limb-Brightened Jet of 3C 84 Revealed by the 43-GHz Very-Long-Baseline-Array Observation

    CERN Document Server

    Nagai, H; Giovannini, G; Doi, A; Orienti, M; D'Ammando, F; Kino, M; Nakamura, M; Asada, K; Hada, K; Giroletti, M

    2014-01-01

    We present a study of sub-pc scale radio structure of the radio galaxy 3C 84/NGC 1275 based on the Very Long Baseline Array (VLBA) data at 43 GHz. We discover a limb-brightening in the "restarted" jet associated with the 2005 radio outburst. In the 1990s, the jet structure was ridge-brightening rather than limb-brightening, despite the observations being done with similar angular resolution. This indicates that the transverse jet structure has changed recently. This change in the morphology shows an interesting agreement with the $\\gamma$-ray flux increase, i.e., the $\\gamma$-ray flux in 1990s was at least seven times lower than the current one. One plausible explanation for the limb-brightening is the velocity structure of the jet in the context of the stratified jet, which is a successful scenario to explain the $\\gamma$-ray emission in some active galactic nuclei (AGNs). If this is the case, the change in apparent transverse structure might be caused by the change in the transverse velocity structure. We a...

  13. Essential oils affect populations of some rumen bacteria in vitro as revealed by microarray (RumenBactArray) analysis.

    Science.gov (United States)

    Patra, Amlan K; Yu, Zhongtang

    2015-01-01

    In a previous study origanum oil (ORO), garlic oil (GAO), and peppermint oil (PEO) were shown to effectively lower methane production, decrease abundance of methanogens, and change abundances of several bacterial populations important to feed digestion in vitro. In this study, the impact of these essential oils (EOs, at 0.50 g/L) on the rumen bacterial community composition and population was further examined using the recently developed RumenBactArray. Species richness (expressed as number of operational taxonomic units, OTUs) in the phylum Firmicutes, especially those in the class Clostridia, was decreased by ORO and GAO, but increased by PEO, while that in the phylum Bacteroidetes was increased by ORO and PEO. Species richness in the genus Butyrivibrio was lowered by all the EOs. Increases of Bacteroidetes OTUs mainly resulted from increases of Prevotella OTUs. Overall, 67 individual OTUs showed significant differences (P ≤ 0.05) in relative abundance across the EO treatments. The predominant OTUs affected by EOs were diverse, including those related to Syntrophococcus sucromutans, Succiniclasticum ruminis, and Lachnobacterium bovis, and those classified to Prevotella, Clostridium, Roseburia, Pseudobutyrivibrio, Lachnospiraceae, Ruminococcaceae, Prevotellaceae, Bacteroidales, and Clostridiales. In total, 60 OTUs were found significantly (P ≤ 0.05) correlated with feed degradability, ammonia concentration, and molar percentage of volatile fatty acids. Taken together, this study demonstrated extensive impact of EOs on rumen bacterial communities in an EO type-dependent manner, especially those in the predominant families Prevotellaceae, Lachnospiraceae, and Ruminococcaceae. The information from this study may aid in understanding the effect of EOs on feed digestion and fermentation by rumen bacteria. PMID:25914694

  14. Essential oils affect populations of some rumen bacteria in vitro as revealed by microarray (RumenBactArray analysis

    Directory of Open Access Journals (Sweden)

    Amlan Kumar Patra

    2015-04-01

    Full Text Available In a previous study origanum oil (ORO, garlic oil (GAO, and peppermint oil (PEO were shown to effectively lower methane production, decrease abundance of methanogens, and change abundances of several bacterial populations important to feed digestion in vitro. In this study, the impact of these essential oils (EOs, at 0.50 g/L, on the rumen bacterial community composition and population was further examined using the recently developed RumenBactArray. Species richness (expressed as number of operational taxonomic units, OTUs in the phylum Firmicutes, especially those in the class Clostridia, was decreased by ORO and GAO, but increased by PEO, while that in the phylum Bacteroidetes was increased by ORO and PEO. Species richness in the genus Butyrivibrio was lowered by all the EOs. Increases of Bacteroidetes OTUs mainly resulted from increases of Prevotella OTUs. Overall, 67 individual OTUs showed significant differences (P≤0.05 in relative abundance across the EO treatments. The predominant OTUs affected by EOs were diverse, including those related to Syntrophococcus sucromutans, Succiniclasticum ruminis, and Lachnobacterium bovis, and those classified to Prevotella, Clostridium, Roseburia, Pseudobutyrivibrio, Lachnospiraceae, Ruminococcaceae, Prevotellaceae, Bacteroidales, and Clostridiales. In total, 60 OTUs were found significantly (P≤0.05 correlated with feed degradability, ammonia concentration, and molar percentage of volatile fatty acids. Taken together, this study demonstrated extensive impact of EOs on rumen bacterial communities in an EO type-dependent manner, especially those in the predominant families Prevotellaceae, Lachnospiraceae and Ruminococcaceae. The information from this study may aid in understanding the effect of EOs on feed digestion and fermentation by rumen bacteria.

  15. Scanning electrochemical microscope characterization of thin film combinatorial libraries for fuel cell electrode applications

    Science.gov (United States)

    Black, M.; Cooper, J.; McGinn, P.

    2005-01-01

    Pt-Ru combinatorial libraries of potential fuel cell anode catalysts are formed by sequential sputter deposition through masks onto Si wafers. Scanning electrochemical microscopy (SECM) is employed for characterization of electrocatalytic activity. Aspects of using a scanning electrochemical microscope for characterization of an array of thin film fuel cell electrode materials are discussed. It is shown that in applying SECM to library characterization, careful attention must be paid to thin film annealing, specimen topography and tip degradation in order to realize meaningful results. Results from a Pt-Ru thin film library reveal the most active members near the 50 Pt/50 Ru composition.

  16. Closing the gaps on human chromosome 19 revealed genes with a high density of repetitive tandemly arrayed elements.

    Energy Technology Data Exchange (ETDEWEB)

    Leem, Sun-Hee; Kouprina, Natalay; Grimwood, Jane; Kim, Jung-Hyun; Mullokandov, Michael; Yoon, Young-Ho; Chae, Ji-Youn; Morgan, Jenna; Lucas, Susan; Richardson, Paul; Detter, Chris; Glavina, Tijana; Rubin, Eddy; Barrett, J. Carl; Larionov, Vladimir

    2003-09-01

    The reported human genome sequence includes about 400 gaps of unknown sequence that were not found in the bacterial artificial chromosome (BAC) and cosmid libraries used for sequencing of the genome. These missing sequences correspond to {approx} 1 percent of euchromatic regions of the human genome. Gap filling is a laborious process because it relies on analysis of random clones of numerous genomic BAC or cosmid libraries. In this work we demonstrate that closing the gaps can be accelerated by a selective recombinational capture of missing chromosomal segments in yeast. The use of both methodologies allowed us to close the four remaining gaps on the human chromosome 19. Analysis of the gap sequences revealed that they contain several abnormalities that could result in instability of the sequences in microbe hosts, including large blocks of micro- and minisatellites and a high density of Alu repeats. Sequencing of the gap regions, in both BAC and YAC forms, allowed us to generate a complete sequence of four genes, including the neuronal cell signaling gene SCK1/SLI. The SCK1/SLI gene contains a record number of minisatellites, most of which are polymorphic and transmitted through meiosis following a Mendelian inheritance. In conclusion, the use of the alternative recombinational cloning system in yeast may greatly accelerate work on closing the remaining gaps in the human genome (as well as in other complex genomes) to achieve the goal of annotation of all human genes.

  17. Three dimensional electrochemical system for neurobiological studies

    DEFF Research Database (Denmark)

    Vazquez, Patricia; Dimaki, Maria; Svendsen, Winnie Edith

    2009-01-01

    In this work we report a novel three dimensional electrode array for electrochemical measurements in neuronal studies. The main advantage of working with these out-of-plane structures is the enhanced sensitivity of the system in terms of measuring electrochemical changes in the environment of a c...

  18. Geometry of the Farallon Slab Revealed by Joint Interpretation of Wavefield Imaging and Tomography Results from the Earthscope Transportable Array

    Science.gov (United States)

    Pavlis, G. L.; Wang, Y.

    2015-12-01

    A significant number of P and S wave tomography models have been produced in the past decade using various subsets of data from the Earthscope USArray and different inversion algorithms. We focus here on published tomography results that span large portions of the final footprint of the USArray. We use 3D visualization techniques to search for common features in different tomography models. We also compare tomography results to features seen in our current generation wavefield images. Recent innovations of our plane wave migration method have yielded what is arguably the highest resolution image ever produced of the mantle in the vicinity of the transition zone. The new results reveal a rich collection of coherent, dipping structures seen throughout the upper mantle and transition zone. These dipping interfaces are judged significant according to a coherence metric. We treat these surfaces as strain markers to assess proposed models for geometry of the 3D geometry of the Farallon Slab under North America. We find the following geologic interpretations are well supported by independent results: 1. The old Farallon under eastern North America and below the base of transition zone is universally seen as a high velocity anomaly. 2. All results support a simple, 3D kinematic model of the updip limit of the Farallon slab window that follows a track from Cape Mendocino, across Nevada, and northern Arizona and New Mexico. 3. All models show a strong low-velocity mantle under the southwestern U.S. 4. A low-velocity features is universally seen related to the Yellowstone-Snake River system. Shorter wavelength features observed in different tomography models are inconsistent showing that the theme of this session is very important to understand what features are in current results are real. Isopach maps of the thickness of the transition show a systematic difference in transition zone thickness in the western and eastern US. The transition zone thickens in the eastern US in

  19. Microelectromechanical System-Based Sensing Arrays for Comparative in Vitro Nanotoxicity Assessment at Single Cell and Small Cell-Population Using Electrochemical Impedance Spectroscopy.

    Science.gov (United States)

    Shah, Pratikkumar; Zhu, Xuena; Zhang, Xueji; He, Jin; Li, Chen-zhong

    2016-03-01

    The traditional in vitro nanotoxicity assessment approaches are conducted on a monolayer of cell culture. However, to study a cell response without interference from the neighbor cells, a single cell study is necessary; especially in cases of neuronal, cancerous, and stem cells, wherein an individual cell's fate is often not explained by the whole cell population. Nonetheless, a single cell does not mimic the actual in vivo environment and lacks important information regarding cell communication with its microenvironment. Both a single cell and a cell population provide important and complementary information about cells' behaviors. In this research, we explored nanotoxicity assessment on a single cell and a small cell population using electrochemical impedance spectroscopy and a microelectromechanical system (MEMS) device. We demonstrated a controlled capture of PC12 cells in different-sized microwells (to capture a different number of cells) using a combined method of surface functionalization and dielectrophoresis. The present approach provides a rapid nanotoxicity response as compared to other conventional approaches. This is the first study, to our knowledge, which demonstrates a comparative response of a single cell and small cell colonies on the same MEMS platform, when exposed to metaloxide nanoparticles. We demonstrated that the microenvironment of a cell is also accountable for cells' behaviors and their responses to nanomaterials. The results of this experimental study open up a new hypothesis to be tested for identifying the role of cell communication in spreading toxicity in a cell population.

  20. Defining the origins of electron transfer at screen-printed graphene-like and graphite electrodes: MoO2 nanowire fabrication on edge plane sites reveals electrochemical insights.

    Science.gov (United States)

    Rowley-Neale, Samuel J; Brownson, Dale A C; Banks, Craig E

    2016-08-18

    Molybdenum (di)oxide (MoO2) nanowires are fabricated onto graphene-like and graphite screen-printed electrodes (SPEs) for the first time, revealing crucial insights into the electrochemical properties of carbon/graphitic based materials. Distinctive patterns observed in the electrochemical process of nanowire decoration show that electron transfer occurs predominantly on edge plane sites when utilising SPEs fabricated/comprised of graphitic materials. Nanowire fabrication along the edge plane sites (and on edge plane like-sites/defects) of graphene/graphite is confirmed with Cyclic Voltammetry, Scanning Electron Microscopy (SEM) and Raman Spectroscopy. Comparison of the heterogeneous electron transfer (HET) rate constants (k°) at unmodified and nanowire coated SPEs show a reduction in the electrochemical reactivity of SPEs when the edge plane sites are effectively blocked/coated with MoO2. Throughout the process, the basal plane sites of the graphene/graphite electrodes remain relatively uncovered; except when the available edge plane sites have been utilised, in which case MoO2 deposition grows from the edge sites covering the entire surface of the electrode. This work clearly illustrates the distinct electron transfer properties of edge and basal plane sites on graphitic materials, indicating favourable electrochemical reactivity at the edge planes in contrast to limited reactivity at the basal plane sites. In addition to providing fundamental insights into the electron transfer properties of graphite and graphene-like SPEs, the reported simple, scalable, and cost effective formation of unique and intriguing MoO2 nanowires realised herein is of significant interest for use in both academic and commercial applications.

  1. Fabrication of one-dimensional ZnO nanotube and nanowire arrays with an anodic alumina oxide template via electrochemical deposition

    International Nuclear Information System (INIS)

    In this work, two kinds of one-dimensional ZnO nanowires (NWs) and nanotubes (NTs) were synthesized by using electrochemical deposition with the aid of a high aspect ratio anodic alumina oxide (AAO) template. ZnO NWs and NTs were characterized by using X-ray diffraction, field emission scanning microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. An AAO template was fabricated by two-step anodization in 0.3 M oxalic acid with a voltage of 80 V. The thickness and channel diameter of the AAO template were about 150 μm and 120–150 nm, respectively. The morphologies of the ZnO nanostructures synthesized under 20 vol.% H2O2 with various electrolyte concentrations of 0.1 M and 0.5 M ZnSO4, were NTs and NWs, respectively. Both NTs and NWs were uniform in size, which corresponded to the sizes of AAO pores. The thickness of the NTs walls can be controlled based on the deposition time and current density. The crystallinity of the ZnO NTs and NWs annealing in the air were restricted by AAO pore. The growth of the ZnO NTs and NWs was caused by heterogeneous nucleation, and different growth rates through the wall of the AAO will result in different nanostructures, with the growth of the NTs being slower than that of the NWs. - Highlights: • Templated electrodeposition of ZnO nanotubes (NTs) and nanowires (NWs) • ZnO NTs and NWs fabricated using anodic alumina oxide templates • The growth mechanism of ZnO NTs and NWs is modeled

  2. Microarray of programmable electrochemically active elements

    DEFF Research Database (Denmark)

    S. McCaskill, John; Maeke, Thomas; Straczek, Lukas;

    2016-01-01

    This paper describes possible applications of a two dimensional array of programmable electrochemically active elements to Alife. The array has been developed as part of the MICREA-gents project, and after several design phases, is now a mature enough device for general use beyond the project. Here...

  3. Time-dependent c-Myc transactomes mapped by Array-based nuclear run-on reveal transcriptional modules in human B cells.

    Directory of Open Access Journals (Sweden)

    Jinshui Fan

    Full Text Available BACKGROUND: The definition of transcriptional networks through measurements of changes in gene expression profiles and mapping of transcription factor binding sites is limited by the moderate overlap between binding and gene expression changes and the inability to directly measure global nuclear transcription (coined "transactome". METHODOLOGY/PRINCIPAL FINDINGS: We developed a method to measure nascent nuclear gene transcription with an Array-based Nuclear Run-On (ANRO assay using commercial microarray platforms. This strategy provides the missing component, the transactome, to fully map transcriptional networks. ANRO measurements in an inducible c-Myc expressing human P493-6 B cell model reveals time-dependent waves of transcription, with a transactome early after c-Myc induction that does not persist at a late, steady-state phase, when genes that are regulated by c-Myc and E2F predominate. Gene set matrix analysis further uncovers functionally related groups of genes putatively regulated by waves of transcription factor motifs following Myc induction, starting with AP1 and CREB that are followed by EGR1, NFkB and STAT, and ending with E2F, Myc and ARNT/HIF motifs. CONCLUSIONS/SIGNIFICANCE: By coupling ANRO with previous global mapping of c-Myc binding sites by chromatin immunoprecipitation (ChIP in P493-6 cells, we define a set of transcriptionally regulated direct c-Myc target genes and pave the way for the use of ANRO to comprehensively map any transcriptional network.

  4. Electrochemical Processes

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers

    1997-01-01

    The notes describe in detail primary and secondary galvanic cells, fuel cells, electrochemical synthesis and electroplating processes, corrosion: measurments, inhibitors, cathodic and anodic protection, details of metal dissolution reactions, Pourbaix diagrams and purification of waste water from...

  5. Electrochemical Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gang; Lin, Yuehe

    2008-07-20

    Sensitive and selective detection techniques are of crucial importance for capillary electrophoresis (CE), microfluidic chips, and other microfluidic systems. Electrochemical detectors have attracted considerable interest for microfluidic systems with features that include high sensitivity, inherent miniaturization of both the detection and control instrumentation, low cost and power demands, and high compatibility with microfabrication technology. The commonly used electrochemical detectors can be classified into three general modes: conductimetry, potentiometry, and amperometry.

  6. Electrochemical assisted photocatalytic degradation of salicylic acid with highly ordered TiO2 nanotube electrodes

    International Nuclear Information System (INIS)

    To explore the kinetics of photoelectrocatalytic degradation of salicylic acid, one of the important PPCPs, highly ordered TiO2 nanotube arrays (NTs) were prepared by the electrochemical anodization and characterized with scanning electron microscopy and X-ray diffraction techniques. The effect of TiO2 NTs properties, bias potential, initial salicylic acid concentration and solution pH on the degradation efficiency was studied and carefully analyzed. The results revealed that the salicylic acid degradation follows quasi-first order kinetics in the photoelectrocatalytic process, and the fastest decay kinetics was achieved in acidic environment (pH 2). The result was further interpreted through the electrochemical impedance spectroscopy. It is confirmed that the electrochemical assisted photocatalysis is a synergetic approach to combat stable organic substances with improved efficiency.

  7. Electrochemical assisted photocatalytic degradation of salicylic acid with highly ordered TiO2 nanotube electrodes

    Science.gov (United States)

    Zhang, Qian; Zhu, Jinwei; Wang, Ying; Feng, Jiangtao; Yan, Wei; Xu, Hao

    2014-07-01

    To explore the kinetics of photoelectrocatalytic degradation of salicylic acid, one of the important PPCPs, highly ordered TiO2 nanotube arrays (NTs) were prepared by the electrochemical anodization and characterized with scanning electron microscopy and X-ray diffraction techniques. The effect of TiO2 NTs properties, bias potential, initial salicylic acid concentration and solution pH on the degradation efficiency was studied and carefully analyzed. The results revealed that the salicylic acid degradation follows quasi-first order kinetics in the photoelectrocatalytic process, and the fastest decay kinetics was achieved in acidic environment (pH 2). The result was further interpreted through the electrochemical impedance spectroscopy. It is confirmed that the electrochemical assisted photocatalysis is a synergetic approach to combat stable organic substances with improved efficiency.

  8. Array-based comparative genomic hybridization analysis reveals chromosomal copy number aberrations associated with clinical outcome in canine diffuse large B-cell lymphoma.

    Directory of Open Access Journals (Sweden)

    Arianna Aricò

    Full Text Available Canine Diffuse Large B-cell Lymphoma (cDLBCL is an aggressive cancer with variable clinical response. Despite recent attempts by gene expression profiling to identify the dog as a potential animal model for human DLBCL, this tumor remains biologically heterogeneous with no prognostic biomarkers to predict prognosis. The aim of this work was to identify copy number aberrations (CNAs by high-resolution array comparative genomic hybridization (aCGH in 12 dogs with newly diagnosed DLBCL. In a subset of these dogs, the genetic profiles at the end of therapy and at relapse were also assessed. In primary DLBCLs, 90 different genomic imbalances were counted, consisting of 46 gains and 44 losses. Two gains in chr13 were significantly correlated with clinical stage. In addition, specific regions of gains and losses were significantly associated to duration of remission. In primary DLBCLs, individual variability was found, however 14 recurrent CNAs (>30% were identified. Losses involving IGK, IGL and IGH were always found, and gains along the length of chr13 and chr31 were often observed (>41%. In these segments, MYC, LDHB, HSF1, KIT and PDGFRα are annotated. At the end of therapy, dogs in remission showed four new CNAs, whereas three new CNAs were observed in dogs at relapse compared with the previous profiles. One ex novo CNA, involving TCR, was present in dogs in remission after therapy, possibly induced by the autologous vaccine. Overall, aCGH identified small CNAs associated with outcome, which, along with future expression studies, may reveal target genes relevant to cDLBCL.

  9. Photo-Current Enhancement in Carbon Quantum Dots Functionalized Titania Nanotube Arrays.

    Science.gov (United States)

    Rani, Sanju; Borse, Pramod H; Pareek, Alka; Rajalakshmi, N; Dhathathreyan, K S

    2016-06-01

    Highly aligned, vertically oriented, TiO2 nanotube arrays fabricated by electrochemical anodization were functionalised by carbon quantum dots (CQD) synthesized by an electrochemical reduction technique. Here, we report the photo-electrochemical properties of such TiO2 nanotubes array-CQD composite material and it has been found that the properties are significantly enhanced compared to that in pristine (bare) nanotubes. The TiO2 nanotubes were characterized by X-ray diffraction and scanning electron microscopy, whereas the CQD samples were characterized by transmission electron microscopy, optical absorption spectroscopy. CQDs synthesized under two different conditions showed a distinct size difference and corresponding absorption spectra revealed concominant shift in the absorption edges. Furthermore, the photo-electrochemical measurements were carried out with the help of photo-current, incident photon to current conversion efficiency (IPCE), Mott-Schottky plots and the impedance analysis. The photo-current data revealed 30% improvement in TiO2-CQD samples compared to bare TiO2 nanotubes samples. A higher photo-conversion efficiency was observed along with the shifting of the peak value towards visible wavelengths. The Mott-Schottky plots revealed shift in the flat-band potential in the CQD-TiO2 samples and corresponding lowering of the charge transfer resistance was observed through the impedance spectroscopy.

  10. Photo-Current Enhancement in Carbon Quantum Dots Functionalized Titania Nanotube Arrays.

    Science.gov (United States)

    Rani, Sanju; Borse, Pramod H; Pareek, Alka; Rajalakshmi, N; Dhathathreyan, K S

    2016-06-01

    Highly aligned, vertically oriented, TiO2 nanotube arrays fabricated by electrochemical anodization were functionalised by carbon quantum dots (CQD) synthesized by an electrochemical reduction technique. Here, we report the photo-electrochemical properties of such TiO2 nanotubes array-CQD composite material and it has been found that the properties are significantly enhanced compared to that in pristine (bare) nanotubes. The TiO2 nanotubes were characterized by X-ray diffraction and scanning electron microscopy, whereas the CQD samples were characterized by transmission electron microscopy, optical absorption spectroscopy. CQDs synthesized under two different conditions showed a distinct size difference and corresponding absorption spectra revealed concominant shift in the absorption edges. Furthermore, the photo-electrochemical measurements were carried out with the help of photo-current, incident photon to current conversion efficiency (IPCE), Mott-Schottky plots and the impedance analysis. The photo-current data revealed 30% improvement in TiO2-CQD samples compared to bare TiO2 nanotubes samples. A higher photo-conversion efficiency was observed along with the shifting of the peak value towards visible wavelengths. The Mott-Schottky plots revealed shift in the flat-band potential in the CQD-TiO2 samples and corresponding lowering of the charge transfer resistance was observed through the impedance spectroscopy. PMID:27427662

  11. Method for the electro-addressable functionalization of electrode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Harper, Jason C.; Polsky, Ronen; Dirk, Shawn M.; Wheeler, David R.; Arango, Dulce C.; Brozik, Susan M.

    2015-12-15

    A method for preparing an electrochemical biosensor uses bias-assisted assembly of unreactive -onium molecules on an electrode array followed by post-assembly electro-addressable conversion of the unreactive group to a chemical or biological recognition group. Electro-addressable functionalization of electrode arrays enables the multi-target electrochemical sensing of biological and chemical analytes.

  12. Electrochemical device

    Science.gov (United States)

    Grimes, Patrick G.; Einstein, Harry; Bellows, Richard J.

    1988-01-12

    A tunnel protected electrochemical device features channels fluidically communicating between manifold, tunnels and cells. The channels are designed to provide the most efficient use of auxiliary power. The channels have a greater hydraulic pressure drop and electrical resistance than the manifold. This will provide a design with the optimum auxiliary energy requirements.

  13. Electrochemical construction

    Science.gov (United States)

    Einstein, Harry; Grimes, Patrick G.

    1983-08-23

    An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

  14. Electrochemical Cell

    DEFF Research Database (Denmark)

    1999-01-01

    The invention relates to a rechargeable electrochemical cell comprising a negative electrode, an electrolyte and a positive electrode in which the positive electrode structure comprises a lithium cobalt manganese oxide of the composition Li¿2?Co¿y?Mn¿2-y?O¿4? where 0

  15. Electrochemically controlled patterning for biosensor arrays.

    OpenAIRE

    Dondapati, Srujan Kumar

    2006-01-01

    Existe una demanda creciente de dispositivos de análisis multianalito, con aplicaciones potenciales en los campos de la biomedicina y biotecnología, así como en el ámbito industrial y ambiental. Para el desarrollo de estos dispositivos resulta esencial un buen control espacial durante la etapa de inmovilización de las biomoléculas de interés; cada una de ellas debe ser depositada de forma precisa sobre la superficie del sensor (por ejemplo, un transductor amperométrico), evitan...

  16. Diversity, genetic mapping, and signatures of domestication in the carrot (Daucus carota L.) genome, as revealed by Diversity Arrays Technology (DArT) markers

    Science.gov (United States)

    Carrot is one of the most economically important vegetables worldwide, however, genetic and genomic resources supporting carrot breeding remain limited. We developed a Diversity Arrays Technology (DArT) platform for wild and cultivated carrot and used it to investigate genetic diversity and to devel...

  17. Combined array-comparative genomic hybridization and single-nucleotide polymorphism-loss of heterozygosity analysis reveals complex changes and multiple forms of chromosomal instability in colorectal cancers

    DEFF Research Database (Denmark)

    Gaasenbeek, Michelle; Howarth, Kimberley; Rowan, Andrew J;

    2006-01-01

    Cancers with chromosomal instability (CIN) are held to be aneuploid/polyploid with multiple large-scale gains/deletions, but the processes underlying CIN are unclear and different types of CIN might exist. We investigated colorectal cancer cell lines using array-comparative genomic hybridization ...

  18. Magnetoelectrolysis of Co nanowire arrays grown in a track-etched polycarbonate membrane

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Barriga, J. [Instituto de Magnetismo Aplicado (UCM-RENFE-CSIC), P.O. Box 155, 28230, Las Rozas, Madrid (Spain)]. E-mail: sbarriga@bessy.de; Lucas, M. [Technische Universitaet Berlin, Institut fuer Theoretische Physik, Hardenbergstr. 36, D-10623 Berlin (Germany); Rivero, G. [Instituto de Magnetismo Aplicado (UCM-RENFE-CSIC), P.O. Box 155, 28230, Las Rozas, Madrid (Spain); Marin, P. [Instituto de Magnetismo Aplicado (UCM-RENFE-CSIC), P.O. Box 155, 28230, Las Rozas, Madrid (Spain); Hernando, A. [Instituto de Magnetismo Aplicado (UCM-RENFE-CSIC), P.O. Box 155, 28230, Las Rozas, Madrid (Spain)

    2007-05-15

    Arrays of Cobalt nanowires with a controlled length of 6{mu}m have been fabricated by electrochemical deposition into the pores of track-etched polycarbonate membranes with a nominal pore diameter of 30nm. The magnetic properties of Co-deposited nanowires and the effects of a magnetic field applied during electrodeposition of the arrays have been studied. An enhancement of the mass deposition rate due to the presence of a 50Oe magnetic field along the nanowire axis has been observed by measuring the experimental development of the current in the electrochemical cell during the fabrication process. X-ray diffraction measurements reveal a different polycrystalline degree for each deposition configuration, indicating that the crystalline structure of the deposited material has been substantially modified. Magnetic measurements show a clear dependence of the anisotropy directions on the orientation of the magnetic field applied during the electrodeposition.

  19. Magnetoelectrolysis of Co nanowire arrays grown in a tracketched polycarbonate membrane

    Energy Technology Data Exchange (ETDEWEB)

    Radu, Florin [BESSY GmbH, Berlin (Germany); Rivero, Guillermo; Marin, Pilar; Hernando, Antonio [Instituto de Magnetismo Aplicado, Madrid (Spain); Sanchez-Barriga, J. [Instituto de Magnetismo Aplicado, Madrid (Spain); BESSY GmbH, Berlin (Germany); Lucas, M. [Inst. fuer Theoretische Physik, Technische Univ. Berlin (Germany)

    2007-07-01

    Arrays of Cobalt nanowires with a controlled length of 6{mu}m have been fabricated by electrochemical deposition into the pores of track-etched polycarbonate membranes with a nominal pore diameter of 30 nm. The magnetic properties of Co-deposited nanowires and the effects of a magnetic field applied during electrodeposition of the arrays have been studied. An enhancement of the mass deposition rate due to the presence of a 50 Oe magnetic field along the nanowire axis has been observed by measuring the experimental development of the current in the electrochemical cell during the fabrication process. X-Ray diffraction measurements reveal a different polycrystalline degree for each deposition configuration, indicating that the crystalline structure of the deposited material has been substantially modified. Magnetic measurements show a clear dependence of the anisotropy directions on the orientation of the magnetic field applied during the electrodeposition.

  20. Electrochemical cell

    Science.gov (United States)

    Nagy, Zoltan; Yonco, Robert M.; You, Hoydoo; Melendres, Carlos A.

    1992-01-01

    An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90.degree. in either direction while maintaining the working and counter electrodes submerged in the electrolyte.

  1. Electrochemical assisted photocatalytic degradation of salicylic acid with highly ordered TiO{sub 2} nanotube electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qian [The State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Zhu, Jinwei [China Aerospace Science and Technology Corporation Fourty-fourth Research Institution (China); Wang, Ying; Feng, Jiangtao [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Yan, Wei, E-mail: yanwei@mail.xjtu.edu.cn [The State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Xu, Hao, E-mail: xuhao@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)

    2014-07-01

    To explore the kinetics of photoelectrocatalytic degradation of salicylic acid, one of the important PPCPs, highly ordered TiO{sub 2} nanotube arrays (NTs) were prepared by the electrochemical anodization and characterized with scanning electron microscopy and X-ray diffraction techniques. The effect of TiO{sub 2} NTs properties, bias potential, initial salicylic acid concentration and solution pH on the degradation efficiency was studied and carefully analyzed. The results revealed that the salicylic acid degradation follows quasi-first order kinetics in the photoelectrocatalytic process, and the fastest decay kinetics was achieved in acidic environment (pH 2). The result was further interpreted through the electrochemical impedance spectroscopy. It is confirmed that the electrochemical assisted photocatalysis is a synergetic approach to combat stable organic substances with improved efficiency.

  2. Diversity, genetic mapping, and signatures of domestication in the carrot (Daucus carota L.) genome, as revealed by Diversity Arrays Technology (DArT) markers

    OpenAIRE

    Grzebelus, Dariusz; Iorizzo, Massimo; Senalik, Douglas; Ellison, Shelby; Cavagnaro, Pablo; Macko-Podgorni, Alicja; Heller-Uszynska, Kasia; Kilian, Andrzej; Nothnagel, Thomas; Allender, Charlotte; Simon, Philipp W; Baranski, Rafal

    2013-01-01

    Carrot is one of the most economically important vegetables worldwide, but genetic and genomic resources supporting carrot breeding remain limited. We developed a Diversity Arrays Technology (DArT) platform for wild and cultivated carrot and used it to investigate genetic diversity and to develop a saturated genetic linkage map of carrot. We analyzed a set of 900 DArT markers in a collection of plant materials comprising 94 cultivated and 65 wild carrot accessions. The accessions were attribu...

  3. Carbon treated self-ordered TiO{sub 2} nanotube arrays with enhanced lithium-ion intercalation performance

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Sik [Energy Material Group, Lotte Chemical, 115, Gajeongbuk-ro, Yuseong-gu, Daejeon 305-726 (Korea, Republic of); Yu, Seung-Ho; Sung, Yung-Eun [School of Chemical and Biological Engineering and Research Center for Energy Conversion and Storage, Seoul National University, San 56-1, Sillim-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kang, Soon Hyung, E-mail: skang@jnu.ac.kr [Department of Chemical Education, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

    2014-06-01

    Highlights: • C-doped TONT was prepared by anodization, followed by acetylene treatment. • C-doped TONT exhibited the superior cycle performance and electrochemical kinetics. • It was attributed from the enhanced electrical conductivity from carbon doping. - Abstract: Vertically aligned TiO{sub 2} nanotube (TONT) arrays on titanium substrate developed by facile electrochemical anodization in an aqueous solution of 0.5 M Na{sub 2}SO{sub 4}, 0.5 M H{sub 3}PO{sub 4}, 0.2 M sodium citrate, and 0.5 wt% NaF were prepared having a pore diameter and thickness of 100 nm and 1.2 μm, respectively. The undoped (u-doped) TONT arrays possessing an anatase phase were again annealed at 500 °C under a mixed gas flux of nitrogen (N{sub 2}) and acetylene (C{sub 2}H{sub 2}), to induce the enhancement of electrical conductivity. It was designated as carbon-doped (c-doped) TONT arrays. Undoped and c-doped TONT arrays were compared using various characterization tools, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and X-ray photoelectron spectroscopy (XPS). Furthermore, based on several electrochemical tests (galvanostatic charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS)), it was observed that c-doped TONT arrays revealed improved charge/discharge capacity, cycle stability, and rate capability, due to the enhanced electrical conductivity of c-doped TONT arrays.

  4. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution began in 1889 and persists today

    OpenAIRE

    J. R. McConnell; O. J. Maselli; Sigl, M.; P. Vallelonga; Neumann, T; H. Anschütz; R. C. Bales; Curran, M.A.J.; S. B. Das; Edwards, R.; Kipfstuhl, S.; Layman, L; E. R. Thomas

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was a...

  5. Alumina Template-Dependant Growth of Cobalt Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    L. Malferrari

    2009-01-01

    Full Text Available Different electrochemical regimes and porous alumina were applied for template synthesis of cobalt nanowire (nw arrays, revealing several peculiar cases. In contrast to quite uniform filling of sulfuric acid alumina templates by alternating current deposition, nonuniform growth of the Co nw tufts and mushrooms was obtained for the case of oxalic acid templates. We showed herein for the first time that such configurations arise from the spontaneous growth of cobalt nw groups evolving from the cobalt balls at the Al/alumina interface. Nevertheless, the uniform growth of densely packed cobalt nw arrays, up to tens of micrometers in length, was obtained via long-term direct current galvanostatic deposition at low current density using oxalic acid templates one-side coated by conducting layer. The unique point of this regime is the formation of hexagonal lattice Co nws with a preferred (100 growth direction.

  6. Electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Rudge, Andrew J. (Los Alamos, NM); Ferraris, John P. (Dallas, TX); Gottesfeld, Shimshon (Los Alamos, NM)

    1996-01-01

    A new class of electrochemical capacitors provides in its charged state a positive electrode including an active material of a p-doped material and a negative electrode including an active material of an n-doped conducting polymer, where the p-doped and n-doped materials are separated by an electrolyte. In a preferred embodiment, the positive and negative electrode active materials are selected from conducting polymers consisting of polythiophene, polymers having an aryl group attached in the 3-position, polymers having aryl and alkyl groups independently attached in the 3- and 4-positions, and polymers synthesized from bridged dimers having polythiophene as the backbone. A preferred electrolyte is a tetraalykyl ammonium salt, such as tetramethylammonium trifluoromethane sulphonate (TMATFMS), that provides small ions that are mobile through the active material, is soluble in acetonitrile, and can be used in a variety of capacitor configurations.

  7. Antarctic-Wide Array of High-Resolution Ice Core Records Reveals Pervasive Lead Pollution Began in 1889 and Persists Today

    Science.gov (United States)

    McConnell, J. R.; Maselli, O. J.; Sigl, M.; Vallelonga, P.; Neumann, Thomas Allen; Anschutz, H.; Bales, R. C.; Curran, M. A. J.; Das, S. B.; Edwards, R.; Kipfstuhl, S.; Layman, L.; Thomas, E. R.

    2014-01-01

    Interior Antarctica is among the most remote places on Earth and was thought to be beyond the reach of human impacts when Amundsen and Scott raced to the South Pole in 1911. Here we show detailed measurements from an extensive array of 16 ice cores quantifying substantial toxic heavy metal lead pollution at South Pole and throughout Antarctica by 1889 - beating polar explorers by more than 22 years. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in the early 20th century as at any time since industrialization. The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today. An estimated 660 t of industrial lead have been deposited over Antarctica during the past 130 years as a result of mid-latitude industrial emissions, with regional-to-global scale circulation likely modulating aerosol concentrations. Despite abatement efforts, significant lead pollution in Antarctica persists into the 21st century.

  8. Microfabricated Electrochemical Cell-Based Biosensors for Analysis of Living Cells In Vitro

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2012-04-01

    Full Text Available Cellular biochemical parameters can be used to reveal the physiological and functional information of various cells. Due to demonstrated high accuracy and non-invasiveness, electrochemical detection methods have been used for cell-based investigation. When combined with improved biosensor design and advanced measurement systems, the on-line biochemical analysis of living cells in vitro has been applied for biological mechanism study, drug screening and even environmental monitoring. In recent decades, new types of miniaturized electrochemical biosensor are emerging with the development of microfabrication technology. This review aims to give an overview of the microfabricated electrochemical cell-based biosensors, such as microelectrode arrays (MEA, the electric cell-substrate impedance sensing (ECIS technique, and the light addressable potentiometric sensor (LAPS. The details in their working principles, measurement systems, and applications in cell monitoring are covered. Driven by the need for high throughput and multi-parameter detection proposed by biomedicine, the development trends of electrochemical cell-based biosensors are also introduced, including newly developed integrated biosensors, and the application of nanotechnology and microfluidic technology.

  9. Chicken-Specific Kinome Array Reveals that Salmonella enterica Serovar Enteritidis Modulates Host Immune Signaling Pathways in the Cecum to Establish a Persistence Infection

    Science.gov (United States)

    Kogut, Michael H.; Swaggerty, Christina L.; Byrd, James Allen; Selvaraj, Ramesh; Arsenault, Ryan J.

    2016-01-01

    Non-typhoidal Salmonella enterica induces an early, short-lived pro-inflammatory response in chickens that is asymptomatic of clinical disease and results in a persistent colonization of the gastrointestinal (GI) tract that transmits infections to naïve hosts via fecal shedding of bacteria. The underlying mechanisms that control this persistent colonization of the ceca of chickens by Salmonella are only beginning to be elucidated. We hypothesize that alteration of host signaling pathways mediate the induction of a tolerance response. Using chicken-specific kinomic immune peptide arrays and quantitative RT-PCR of infected cecal tissue, we have previously evaluated the development of disease tolerance in chickens infected with Salmonella enterica serovar Enteritidis (S. Enteritidis) in a persistent infection model (4–14 days post infection). Here, we have further outlined the induction of an tolerance defense strategy in the cecum of chickens infected with S. Enteritidis beginning around four days post-primary infection. The response is characterized by alterations in the activation of T cell signaling mediated by the dephosphorylation of phospholipase c-γ1 (PLCG1) that inhibits NF-κB signaling and activates nuclear factor of activated T-cells (NFAT) signaling and blockage of interferon-γ (IFN-γ) production through the disruption of the JAK-STAT signaling pathway (dephosphorylation of JAK2, JAK3, and STAT4). Further, we measured a significant down-regulation reduction in IFN-γ mRNA expression. These studies, combined with our previous findings, describe global phenotypic changes in the avian cecum of Salmonella Enteritidis-infected chickens that decreases the host responsiveness resulting in the establishment of persistent colonization. The identified tissue protein kinases also represent potential targets for future antimicrobial compounds for decreasing Salmonella loads in the intestines of food animals before going to market. PMID:27472318

  10. A local redox cycling-based electrochemical chip device with nanocavities for multi-electrochemical evaluation of embryoid bodies.

    Science.gov (United States)

    Kanno, Yusuke; Ino, Kosuke; Shiku, Hitoshi; Matsue, Tomokazu

    2015-12-01

    An electrochemical device, which consists of electrode arrays, nanocavities, and microwells, was developed for multi-electrochemical detection with high sensitivity. A local redox cycling-based electrochemical (LRC-EC) system was used for multi-electrochemical detection and signal amplification. The LRC-EC system consists of n(2) sensors with only 2n bonding pads for external connection. The nanocavities fabricated in the sensor microwells enable significant improvement of the signal amplification compared with the previous devices we have developed. The present device was successfully applied for evaluation of embryoid bodies (EBs) from embryonic stem (ES) cells via electrochemical measurements of alkaline phosphatase (ALP) activity in the EBs. In addition, the EBs were successfully trapped in the sensor microwells of the device using dielectrophoresis (DEP) manipulation, which led to high-throughput cell analysis. This device is considered to be useful for multi-electrochemical detection and imaging for bioassays including cell analysis.

  11. TiO(2) nanotube arrays: intrinsic peroxidase mimetics.

    Science.gov (United States)

    Zhang, Lingling; Han, Lei; Hu, Peng; Wang, Li; Dong, Shaojun

    2013-11-18

    TiO2 nanotube arrays (NTA), prepared by potentiostatic anodization, were discovered to possess an intrinsic peroxidase-like activity. The colorimetric and electrochemical assays both demonstrated their excellent catalytic activity towards H2O2 reduction. On this basis, a simple and inexpensive electrochemical biosensor for glucose detection was developed. PMID:24084751

  12. Microfluidic electrochemical reactors

    Science.gov (United States)

    Nuzzo, Ralph G.; Mitrovski, Svetlana M.

    2011-03-22

    A microfluidic electrochemical reactor includes an electrode and one or more microfluidic channels on the electrode, where the microfluidic channels are covered with a membrane containing a gas permeable polymer. The distance between the electrode and the membrane is less than 500 micrometers. The microfluidic electrochemical reactor can provide for increased reaction rates in electrochemical reactions using a gaseous reactant, as compared to conventional electrochemical cells. Microfluidic electrochemical reactors can be incorporated into devices for applications such as fuel cells, electrochemical analysis, microfluidic actuation, pH gradient formation.

  13. Electrochemical Discharge Machining Process

    Directory of Open Access Journals (Sweden)

    Anjali V. Kulkarni

    2007-09-01

    Full Text Available Electrochemical discharge machining process is evolving as a promising micromachiningprocess. The experimental investigations in the present work substantiate this trend. In the presentwork, in situ, synchronised, transient temperature and current measurements have been carriedout. The need for the transient measurements arose due to the time-varying nature of the dischargeformation and time varying circuit current. Synchronised and transient measurements revealedthe discrete nature of the process. It also helped in formulating the basic mechanism for thedischarge formation and the material removal in the process. Temperature profile on workpieceand in electrochemical discharge machining cell is experimentally measured using pyrometer,and two varieties of K-type thermocouples. Surface topography of the discharge-affected zoneson the workpiece has been carried out using scanning electron microscope. Measurements andsurface topographical studies reveal the potential use of this process for machining in micronregime. With careful experimental set-up design, suitable supply voltage and its polarity, theprocess can be applied for both micromachining and micro-deposition. It can be extended formachining and or deposition of wide range of materials.

  14. Smooth bumps in H/V curves over a broad area from single-station ambient noise recordings are meaningful and reveal the importance of Q in array processing: The Boumerdes (Algeria) case

    Science.gov (United States)

    Guillier, B.; Chatelain, J.-L.; Hellel, M.; Machane, D.; Mezouer, N.; Ben Salem, R.; Oubaiche, E. H.

    2005-12-01

    Single-station H/V curves from ambient noise recordings in Boumerdes (Algeria) show smooth bumps around 1 and 3 Hz. A complementary microtremor study, based on two 34 and 134-meter aperture arrays, evidences that these bumps are indeed real peaks produced by two strong VS contrasts at 37 and 118 meters depth, strongly smoothed by very high S-wave attenuation in the two sedimentary layers. These two H/V bumps, observed over a broad area, are meaningful and reveal the importance of Q in S-wave velocity modeling from microtremor array data processing. It also appears that Tertiary rocks should be, at least in some cases, taken into account, together with the Quaternary sediments, to explain single-station H/V frequency peaks, and therefore that considering only the first 30 m of soil for VS amplification evaluation, as usually recommended, sometimes leads to flaky results by artificially eliminating non-explained low-frequency peaks from the analysis.

  15. Nanoplasmonic biosensor: coupling electrochemistry to localized surface plasmon resonance spectroscopy on nanocup arrays.

    Science.gov (United States)

    Zhang, Diming; Lu, Yanli; Jiang, Jing; Zhang, Qian; Yao, Yao; Wang, Ping; Chen, Bilian; Cheng, Qiaoyuan; Liu, Gang Logan; Liu, Qingjun

    2015-05-15

    The nanoscale Lycurgus cup arrays were hybrid structures of nanocups and nanoparticles with ultrasensitivity to refractive index change. In this study, an electrochemical localized surface plasmon resonance (LSPR) sensor was developed by coupling electrochemistry to LSPR spectroscopy measurement on the nanoscale cup arrays (nanoCA). Based on the combination of electrochemistry and LSPR measurement, the electrochemical LSPR on nanoCA was observed with significant resonance wavelength shifts in electrochemical modulation. The synchronous implementation of cyclic voltammetry and optical transmission spectrum can be used to obtain multiply sensing information and investigate the enhancement for LSPR from electrochemical scanning. The electrochemical enhanced LSPR was utilized as biosensor to detect biomolecules. The electrochemical LSPR biosensor with synchronous electrochemical and optical implement showed higher sensitivity than that of conventional optical LSPR measurement. Detecting with multi-transducer parameters and high sensitivity, the electrochemical LSPR provided a promising approach for chemical and biological detection. PMID:25172029

  16. Electrochemical kinetics theoretical aspects

    CERN Document Server

    Vetter, Klaus J

    1967-01-01

    Electrochemical Kinetics: Theoretical Aspects focuses on the processes, methodologies, reactions, and transformations in electrochemical kinetics. The book first offers information on electrochemical thermodynamics and the theory of overvoltage. Topics include equilibrium potentials, concepts and definitions, electrical double layer and electrocapillarity, and charge-transfer, diffusion, and reaction overvoltage. Crystallization overvoltage, total overvoltage, and resistance polarization are also discussed. The text then examines the methods of determining electrochemical reaction mechanisms

  17. Magnetic Electrochemical Finishing Machining

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    How to improve the finishing efficiency and surface roughness have been all along the objective of research in electrochemical polishing. However, the research activity, i.e. during electrochemical polishing, directly introduce the magnetic field to study how the magnetic field influences on the finishing efficiency, quality and the electrochemical process in the field of finishing machining technology, is insufficient. When introducing additional magnetic field in the traditional electrochemical pol...

  18. Genome-wide copy number profiling using a 100K SNP array reveals novel disease-related genes BORIS and TSHZ1 in juvenile angiofibroma.

    Science.gov (United States)

    Schick, Bernhard; Wemmert, Silke; Willnecker, Vivienne; Dlugaiczyk, Julia; Nicolai, Piero; Siwiec, Henryk; Thiel, Christian T; Rauch, Anita; Wendler, Olaf

    2011-11-01

    Juvenile angiofibroma (JA) is a unique fibrovascular tumor, which is almost exclusively found in the posterior nasal cavity of adolescent males. Although histologically classified as benign, the tumor often shows an aggressive growth pattern and has been associated with chromosomal imbalances, amplification of oncogenes and epigenetic dysregulation. We present the first genome-wide profiling of JAs (n=14) with a 100K single nucleotide polymorphism (SNP) microarray. Among the 30 novel JA-specific amplifications detected on autosomal chromosomes with this technique, the genes encoding the cancer-testis antigen BORIS (brother of the regulator of imprinted sites) and the developmental regulator protein TSHZ1 (teashirt zinc finger homeobox 1) were selected for further analysis. Gains for both BORIS (20q13.3) and TSHZ1 (18q22.3) were confirmed by quantitative genomic PCR. Furthermore, quantitative RT-PCR revealed a significant up-regulation of BORIS (ptool for identifying novel disease-related genes in JAs and newly implicates BORIS and TSHZ1 overexpression in the pathogenesis of JAs. Detection of BORIS in JAs is described with special regard to tumor proliferation and epigenetic dysregulation, and the finding of TSHZ1 amplifications is discussed with special respect to the hypothesis of JAs as malformations of the first branchial arch artery.

  19. Combination of RNAseq and SNP nanofluidic array reveals the center of genetic diversity of cacao pathogen Moniliophthora roreri in the upper Magdalena Valley of Colombia and its clonality

    Directory of Open Access Journals (Sweden)

    Shahin S Ali

    2015-08-01

    Full Text Available Moniliophthora roreri is the fungal pathogen that causes frosty pod rot (FPR disease of Theobroma cacao L., the source of chocolate. FPR occurs in most of the cacao producing countries in the Western Hemisphere, causing yield losses up to 80%. Genetic diversity within the FPR pathogen population may allow the population to adapt to changing environmental conditions and adapt to enhanced resistance in the host plant. The present study developed SNP markers from RNASeq results for 13 M. roreri isolates and validated the markers for their ability to reveal genetic diversity in an international M. roreri collection. The SNP resources reported herein represent the first study of RNASeq-derived SNP validation in M. roreri and demonstrates the utility of RNASeq as an approach for de novo SNP identification in M. roreri. A total of 88 polymorphic SNPs were used to evaluate the genetic diversity of 172 M. roreri cacao isolates resulting in 37 distinct genotypes (including 14 synonymous groups. Absence of heterozygosity for the 88 SNP markers indicates reproduction in M. roreri is clonal and likely due to a homothallic life style. The upper Magdalena Valley of Colombia showed the highest levels of genetic diversity with 20 distinct genotypes of which 13 were limited to this region, and indicates this region as the possible center of origin for M. roreri.

  20. Electrochemical behavior and effect of heat treatment on morphology, crystalline structure of self-organized TiO{sub 2} nanotube arrays on Ti–6Al–7Nb for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, L. [Department of Chemistry, Anna University, Chennai, Tamilnadu (India); Surface Engineering Division, CSIR–National Aerospace Laboratories, P.O. Box: 1779, Old Airport Road, Bangalore, Karnataka (India); Anandan, C., E-mail: canandan@nal.res.in [Surface Engineering Division, CSIR–National Aerospace Laboratories, P.O. Box: 1779, Old Airport Road, Bangalore, Karnataka (India); Rajendran, N., E-mail: nrajendran@annauniv.edu [Department of Chemistry, Anna University, Chennai, Tamilnadu (India)

    2015-05-01

    In the present work, we investigate the formation of self-organized titanium oxide nanotube layers by anodic oxidation on titanium alloy Ti–6Al–7Nb in electrolyte solution containing sulfuric acid and hydrofluoric acid. The anodized surface was characterized by micro-Raman, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS). The corrosion behavior of the treated and untreated samples was investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hanks' solution). The investigations show that the native oxide on the sample is replaced by self-assembled nanoarray by anodization. FESEM of samples annealed at 450 to 800 °C show tubular morphology whereas those annealed at 850 °C show collapse of nanotubes. Electrochemical impedance data of the substrate and 10 V anodized samples were fitted with a two-time constant equivalent circuit and that of anodized samples (20, 30 V) with a three-time constant equivalent circuit. - Highlights: • Titanium oxide nanotubes (NT) are formed on Ti alloy Ti–6Al–7Nb by anodization. • Pore diameters with ~ 35, 100 and 125 nm are formed at different voltages. • Vacuum annealing at 850 °C increases the rutile content. • Collapse of NT with more needle shaped (nanowires) structure at 850 °C • NT sample shows better passivation behavior in Hanks' solution.

  1. Electrochemical behavior and effect of heat treatment on morphology, crystalline structure of self-organized TiO2 nanotube arrays on Ti–6Al–7Nb for biomedical applications

    International Nuclear Information System (INIS)

    In the present work, we investigate the formation of self-organized titanium oxide nanotube layers by anodic oxidation on titanium alloy Ti–6Al–7Nb in electrolyte solution containing sulfuric acid and hydrofluoric acid. The anodized surface was characterized by micro-Raman, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS). The corrosion behavior of the treated and untreated samples was investigated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies in simulated body fluid (Hanks' solution). The investigations show that the native oxide on the sample is replaced by self-assembled nanoarray by anodization. FESEM of samples annealed at 450 to 800 °C show tubular morphology whereas those annealed at 850 °C show collapse of nanotubes. Electrochemical impedance data of the substrate and 10 V anodized samples were fitted with a two-time constant equivalent circuit and that of anodized samples (20, 30 V) with a three-time constant equivalent circuit. - Highlights: • Titanium oxide nanotubes (NT) are formed on Ti alloy Ti–6Al–7Nb by anodization. • Pore diameters with ~ 35, 100 and 125 nm are formed at different voltages. • Vacuum annealing at 850 °C increases the rutile content. • Collapse of NT with more needle shaped (nanowires) structure at 850 °C • NT sample shows better passivation behavior in Hanks' solution

  2. Genome sequence reveals that Pseudomonas fluorescens F113 possesses a large and diverse array of systems for rhizosphere function and host interaction

    Directory of Open Access Journals (Sweden)

    Redondo-Nieto Miguel

    2013-01-01

    Full Text Available Abstract Background Pseudomonas fluorescens F113 is a plant growth-promoting rhizobacterium (PGPR isolated from the sugar-beet rhizosphere. This bacterium has been extensively studied as a model strain for genetic regulation of secondary metabolite production in P. fluorescens, as a candidate biocontrol agent against phytopathogens, and as a heterologous host for expression of genes with biotechnological application. The F113 genome sequence and annotation has been recently reported. Results Comparative analysis of 50 genome sequences of strains belonging to the P. fluorescens group has revealed the existence of five distinct subgroups. F113 belongs to subgroup I, which is mostly composed of strains classified as P. brassicacearum. The core genome of these five strains is highly conserved and represents approximately 76% of the protein-coding genes in any given genome. Despite this strong conservation, F113 also contains a large number of unique protein-coding genes that encode traits potentially involved in the rhizocompetence of this strain. These features include protein coding genes required for denitrification, diterpenoids catabolism, motility and chemotaxis, protein secretion and production of antimicrobial compounds and insect toxins. Conclusions The genome of P. fluorescens F113 is composed of numerous protein-coding genes, not usually found together in previously sequenced genomes, which are potentially decisive during the colonisation of the rhizosphere and/or interaction with other soil organisms. This includes genes encoding proteins involved in the production of a second flagellar apparatus, the use of abietic acid as a growth substrate, the complete denitrification pathway, the possible production of a macrolide antibiotic and the assembly of multiple protein secretion systems.

  3. Fabrication of high aspect ratio microtube arrays for 2D photonic crystals

    International Nuclear Information System (INIS)

    This paper describes the fabrication of 2D photonic crystals made of high aspect ratio Si microtube arrays. The tube fabrication is based on the creation of macropore arrays in n-doped Si substrates via photoassisted electrochemical etching. These macropores are successively filled using thermal oxidation and chemical vapor depostion. The substrate material is partially removed by a KOH immersion, and the filled macropores are exposed, forming arrays of microtubes with very high aspect ratios of up to 1:60. Point and line defects are introduced into some of the tube arrays by selectively omitting macropores during the fabrication. The mechanical properties of the tubes were investigated by measuring their stiffness and elastic modulus using an atomic force microscope based setup. Additionally, the resonant modes of the microtubes were simulated with FEM methods. Optical simulations reveal that these tube arrays form 2D photonic crystals, which can contain bandgaps for TM polarized light. It is also shown that the optical properties of the photonic crystals depend strongly on the tube filling factor. Adjusting the filling factor of the tubes allows tuning of the photonic properties of the tube arrays. (papers)

  4. Embroidered electrochemical sensors for biomolecular detection.

    Science.gov (United States)

    Liu, Xiyuan; Lillehoj, Peter B

    2016-05-24

    Electrochemical sensors are powerful analytical tools which possess the capacity for rapid detection of biomarkers in clinical specimens. While most electrochemical sensors are fabricated on rigid substrates, there is a growing need for sensors that can be manufactured on inexpensive and flexible materials. Here, we present a unique embroidered electrochemical sensor that is capable of quantitative analytical measurements using raw biofluid samples. Conductive threads immobilized with enzyme probes were generated using a simple and robust fabrication process and used to fabricate flexible, mechanically robust electrodes on textiles. For proof of concept, measurements were performed to detect glucose and lactate in buffer and whole blood samples, which exhibited excellent specificity and accuracy. We also demonstrate that our embroidered biosensor can be readily fabricated in two-dimensional (2D) arrays for multiplexed measurements. Lastly, we show that this biosensor exhibits good resiliency against mechanical stress and superior repeatability, which are important requirements for flexible sensor platforms. PMID:27156700

  5. Preparation and Electrocatalytic Activity of Tungsten Carbide Nanorod Arrays

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    High density tungsten carbide nanorod arrays have been prepared by magnetron sputtering (MS) using the aluminum lattice membrane (ALM) as template. Electrocatalytic properties of nitromethane electroreduction on the tungsten carbide nanorod arrays electrode were investigated by electrochemical method, and their electrocatalytic activity is approached to that of the Pt foil electrode.

  6. In vitro bioactivity and corrosion resistance of Zr incorporated TiO2 nanotube arrays for orthopaedic applications

    Science.gov (United States)

    Indira, K.; KamachiMudali, U.; Rajendran, N.

    2014-10-01

    The present investigation deals with the incorporation of zirconium (Zr) ions onto TiO2 nanotube arrays (TNT) by simple dip coating method for biomedical implants. The electrochemical behaviour of the specimens were studied with potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy (EIS), while surface analysis involved field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, thin film x-ray diffraction (TF-XRD) and contact angle measurements. The FE-SEM morphology revealed that self-organised TNT was tightly arrayed with an average diameter of 110 ± 4 nm. The wall thickness and length of 15 ± 2 nm and 2.1 ± 0.3 μm respectively were developed by electrochemical anodization of titanium sheet in a mixture of ethylene glycol and NH4F electrolyte. The EDS, ATR-FTIR and TF-XRD studies were revealed the incorporation of Zr onto TNT specimens. Hydroxyapatite (HAp) was grown over Zr ions incorporated TNT (Zr-TNT) via in vitro immersion method. The HAp grown Zr-TNT exhibited higher bioactivity as well as enhanced corrosion resistance when compared to other specimen. Hence, Zr-TNT could be a viable material for the use as orthopaedic implant with good bioactivity and corrosion resistance.

  7. Electrochemical removal of NOx and hydrocarbons

    DEFF Research Database (Denmark)

    Friedberg, Anja Zarah

    This thesis comprise of investigations on an electrochemical cell for the reduction of NO by propene. The focus has been on the electrochemical enhancement of the selective reduction of NO by propene by using perovskites, which are known to be catalyst for this reaction in the composite electrodes......, or to contribute with entirely new properties to the system. The LSM was also tested with cobalt doping in the structure.Two types of electrochemical cells were tested. The simplest one being the symmetrical cell and the other a cell stack of porous alternating layers of electrode and electrolyte. To evaluate...... the systems, conversion measurements has been done where polarisations were applied to the cells during gas analysis. The characterisation of the different materials was done using electrochemical impedance spectroscopy and cyclic voltammetry.This project revealed that the propene acts as an inhibitor...

  8. Preparation and characterization of haematite nanowire arrays

    CERN Document Server

    Xue, D S; Liu, Q F; Zhang, L Y

    2003-01-01

    Arrays of alpha-Fe sub 2 O sub 3 nanowires embedded in anodic alumina membranes were obtained after heat-treating beta-FeOOH nanowire arrays fabricated by electrochemical deposition. Haematite polycrystalline nanowires with maximum length of about 7 mu m and average diameter of about 120 nm were characterized by means of x-ray diffraction and transmission electron microscopy. The Morin temperature below 80 K and Neel temperature of about 350 K for the alpha-Fe sub 2 O sub 3 nanowire arrays, far lower than those of bulk material, were measured by Moessbauer spectroscopy and using a Magnetic Property Measurement System.

  9. Array tomography: imaging stained arrays.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time-consuming and require some practice to perfect. In this protocol, tissue arrays are imaged using conventional wide-field fluorescence microscopy. Images can be captured manually or, with the appropriate software and hardware, the process can be automated. PMID:21041399

  10. Array tomography: production of arrays.

    Science.gov (United States)

    Micheva, Kristina D; O'Rourke, Nancy; Busse, Brad; Smith, Stephen J

    2010-11-01

    Array tomography is a volumetric microscopy method based on physical serial sectioning. Ultrathin sections of a plastic-embedded tissue are cut using an ultramicrotome, bonded in an ordered array to a glass coverslip, stained as desired, and imaged. The resulting two-dimensional image tiles can then be reconstructed computationally into three-dimensional volume images for visualization and quantitative analysis. The minimal thickness of individual sections permits high-quality rapid staining and imaging, whereas the array format allows reliable and convenient section handling, staining, and automated imaging. Also, the physical stability of the arrays permits images to be acquired and registered from repeated cycles of staining, imaging, and stain elution, as well as from imaging using multiple modalities (e.g., fluorescence and electron microscopy). Array tomography makes it possible to visualize and quantify previously inaccessible features of tissue structure and molecular architecture. However, careful preparation of the tissue is essential for successful array tomography; these steps can be time consuming and require some practice to perfect. This protocol describes the sectioning of embedded tissues and the mounting of the serial arrays. The procedures require some familiarity with the techniques used for ultramicrotome sectioning for electron microscopy. PMID:21041397

  11. Effect of F- on corrosion electrochemical behavior of copper in 5% Na2SO4 solution by using electrode array%阵列电极研究F-对铜在5%Na2SO4溶液中腐蚀电化学行为的影响

    Institute of Scientific and Technical Information of China (English)

    吴红艳; 周琼宇; 钟庆东; 盛敏奇; 王毅; 林海

    2011-01-01

    采用阵列电极技术、扫描电子显微镜、自腐蚀电位、极化曲线和电化学阻抗等电化学方法研究F-对铜在5%Na2SO4溶液中腐蚀电化学行为的影响.结果表明:F-使铜表面的腐蚀电流密度增大,自腐蚀电位负移,电化学阻抗降低,铜表面各区域的自腐蚀电位标准方差由21.08增加到28.31,阻抗标准方差由1.431增加到2.071.F-的存在使铜表面的腐蚀产物膜层的形貌及结构发生明显变化,腐蚀产物膜层由均匀致密分布的颗粒状转变为凹凸不平、疏松的多坑状.说明F-能加剧铜的腐蚀并破坏铜表面腐蚀产物膜层,加剧局部微区腐蚀的发生,铜腐蚀趋于不均匀.%Using self-corrosion potential polarization curve and electrochemical impedance spectrum, the effect of F~on the corrosion electrochemical behavior of copper in 5%Na2SO4 solution was investigated by the electrode array and scanning electron microscopy. The results show that F- makes the current density increased, self-corrosion potential and electrochemical impedance decreased. The addition of F- leads to the variance of the self-corrosion potential increasing from 21.07 to 28.31 and that of total impedance increasing from 1.431 to 2.107. F- makes a great change on the morphology and structure of corrosion product film, and the structure of corrosion product film on the copper surface is transformed from uniform and compact structure to porous and uneven structure, which indicates that the presence of F-can erode a part of the corrosion product film and accelerate the localized corrosion. The corrosion of copper tends to be inhomogeneous when F is added.

  12. Electrochemically driven mechanical energy harvesting.

    Science.gov (United States)

    Kim, Sangtae; Choi, Soon Ju; Zhao, Kejie; Yang, Hui; Gobbi, Giorgia; Zhang, Sulin; Li, Ju

    2016-01-01

    Efficient mechanical energy harvesters enable various wearable devices and auxiliary energy supply. Here we report a novel class of mechanical energy harvesters via stress-voltage coupling in electrochemically alloyed electrodes. The device consists of two identical Li-alloyed Si as electrodes, separated by electrolyte-soaked polymer membranes. Bending-induced asymmetric stresses generate chemical potential difference, driving lithium ion flux from the compressed to the tensed electrode to generate electrical current. Removing the bending reverses ion flux and electrical current. Our thermodynamic analysis reveals that the ideal energy-harvesting efficiency of this device is dictated by the Poisson's ratio of the electrodes. For the thin-film-based energy harvester used in this study, the device has achieved a generating capacity of 15%. The device demonstrates a practical use of stress-composition-voltage coupling in electrochemically active alloys to harvest low-grade mechanical energies from various low-frequency motions, such as everyday human activities. PMID:26733282

  13. Electrochemically driven mechanical energy harvesting

    Science.gov (United States)

    Kim, Sangtae; Choi, Soon Ju; Zhao, Kejie; Yang, Hui; Gobbi, Giorgia; Zhang, Sulin; Li, Ju

    2016-01-01

    Efficient mechanical energy harvesters enable various wearable devices and auxiliary energy supply. Here we report a novel class of mechanical energy harvesters via stress-voltage coupling in electrochemically alloyed electrodes. The device consists of two identical Li-alloyed Si as electrodes, separated by electrolyte-soaked polymer membranes. Bending-induced asymmetric stresses generate chemical potential difference, driving lithium ion flux from the compressed to the tensed electrode to generate electrical current. Removing the bending reverses ion flux and electrical current. Our thermodynamic analysis reveals that the ideal energy-harvesting efficiency of this device is dictated by the Poisson's ratio of the electrodes. For the thin-film-based energy harvester used in this study, the device has achieved a generating capacity of 15%. The device demonstrates a practical use of stress-composition-voltage coupling in electrochemically active alloys to harvest low-grade mechanical energies from various low-frequency motions, such as everyday human activities.

  14. Electrochemical stability of self-assembled monolayers on gold

    NARCIS (Netherlands)

    Beulen, Marcel W.J.; Kastenberg, Miryam I.; Veggel, van Frank C.J.M.; Reinhoudt, David N.

    1998-01-01

    Most applications of functionalized self-assembled monolayers (SAMs) are based on changes in electrochemical properties. Such applications require electrochemical stability. This study reveals that there is only a limited potential window from -0.8 to +0.4 VMSE where self-assembled monolayers of sul

  15. 电化学阻抗谱法研究铈改性TiO2纳米管阵列光电极裂解水产氢动力学%Dynamics Study on the Cerium and Oxidative Cerium Modified TiO2 Nanotube Arrays for Hydrogen Production by Water Splitting Using Electrochemical Impedance Spectrum

    Institute of Scientific and Technical Information of China (English)

    张胜寒; 梁可心; 檀玉

    2012-01-01

    TiO2 nanotube arrays photoelectrodes were prepared by anode oxidation on pure Ti sheet. The donor material glycol (C2H6O2) added in the anode electrolyte significantly reduced the charge transfer impedance of TiO2 nanotubes to promote the photocatalytic water splitting for hydrogen production. TiO2 nanotube arrays electrodes were modified by cerium and oxidative cerium with electrochemical deposition and anodic oxidation. The fiat band potential moves to the negative potential direction after modification. Electrochemical impedance spectrum (EIS) measurement was used to investigate the electron transfer characteristic in photoelectrodes and the interface characteristic in the photoelectrochemical cell (PEC) for hydrogen production. Arcs of EIS and corresponding electrode processes were discussed. Dynamic parameters of the electrodes were calculated by reasonable electrical equivalent circuit fitting. The results indicate that TiO2 nanotube arrays electrode modified by cerium and oxidative cerium could largely decrease the electron transfer resistance which contributes to hydrogen production. The mechanism of the cerium and oxidative cerium acting on TiO2 nanotube arrays to promote charge transfer is discussed.%通过阳极氧化法在纯钛板上制备TiO2纳米管阵列电极.在光电化学电解池阳极中加入供电子物质乙二醇,显著减小了TiO2纳米管的电荷传递阻抗,促进了光电催化裂解水产氢反应.采用阴极电沉积和阳极氧化法制备了单质铈和氧化铈共同改性的TiO2纳米管阵列半导体光阳极,其平带电位向电负方向移动.采用电化学阻抗谱法(EIS)对改性后TiO2纳米管阵列在光电催化裂解水产氢中的电子传输性能以及界面性质进行了表征,确定了各阻抗弧对应的电极过程.采用合理的等效电路模型计算了电极的电子传输动力学参数.结果表明,经铈改性后的TiO2纳米管阵列膜电阻明显减小,

  16. Electrochemical Synthesis and Structural Characterization of Titania Nanotubes

    OpenAIRE

    Nguyen, Que Anh

    2010-01-01

    Titania nanotubes have emerged as an exciting new material with a wide array of applications such as sensors, dye sensitized solar cells, and batteries due to their semi-conducting nature, high surface area, and distinct morphology. The nanotubes, synthesized electrochemically in a fluoride-containing electrolyte, are vertically aligned, close-packed, organized structures, with similar diameter and length. The formation mechanism responsible for the organized nanopore/nanotube arrays were exa...

  17. An electrochemical active valve

    NARCIS (Netherlands)

    Neagu, C.R.; Gardeniers, J.G.E.; Elwenspoek, M.; Kelly, J.J.

    1997-01-01

    A novel electrochemical microactuator was developed, which operates as an active valve. The microactuator consists of an electrochemical cell and a membrane that deflects because of the pressure of oxygen gas generated by electrolysis. Relatively large pressures (up to tens of bars) can be reached w

  18. Electrochemical cell stack assembly

    Science.gov (United States)

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2010-06-22

    Multiple stacks of tubular electrochemical cells having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films arranged in parallel on stamped conductive interconnect sheets or ferrules. The stack allows one or more electrochemical cell to malfunction without disabling the entire stack. Stack efficiency is enhanced through simplified gas manifolding, gas recycling, reduced operating temperature and improved heat distribution.

  19. Electrochemical thermodynamic measurement system

    Science.gov (United States)

    Reynier, Yvan; Yazami, Rachid; Fultz, Brent T.

    2009-09-29

    The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

  20. Highly Stretchable Fully-Printed CNT-Based Electrochemical Sensors and Biofuel Cells: Combining Intrinsic and Design-Induced Stretchability.

    Science.gov (United States)

    Bandodkar, Amay J; Jeerapan, Itthipon; You, Jung-Min; Nuñez-Flores, Rogelio; Wang, Joseph

    2016-01-13

    We present the first example of an all-printed, inexpensive, highly stretchable CNT-based electrochemical sensor and biofuel cell array. The synergistic effect of utilizing specially tailored screen printable stretchable inks that combine the attractive electrical and mechanical properties of CNTs with the elastomeric properties of polyurethane as a binder along with a judiciously designed free-standing serpentine pattern enables the printed device to possess two degrees of stretchability. Owing to these synergistic design and nanomaterial-based ink effects, the device withstands extremely large levels of strains (up to 500% strain) with negligible effect on its structural integrity and performance. This represents the highest stretchability offered by a printed device reported to date. Extensive electrochemical characterization of the printed device reveal that repeated stretching, torsional twisting, and indenting stress has negligible impact on its electrochemical properties. The wide-range applicability of this platform to realize highly stretchable CNT-based electrochemical sensors and biofuel cells has been demonstrated by fabricating and characterizing potentiometric ammonium sensor, amperometric enzyme-based glucose sensor, enzymatic glucose biofuel cell, and self-powered biosensor. Highly stretchable printable multianalyte sensor, multifuel biofuel cell, or any combination thereof can thus be realized using the printed CNT array. Such combination of intrinsically stretchable printed nanomaterial-based electrodes and strain-enduring design patterns holds considerable promise for creating an attractive class of inexpensive multifunctional, highly stretchable printed devices that satisfy the requirements of diverse healthcare and energy fields wherein resilience toward extreme mechanical deformations is mandatory. PMID:26694819

  1. Electrochemical gating in scanning electrochemical microscopy

    NARCIS (Netherlands)

    Ahonen, P.; Ruiz, V.; Kontturi, K.; Liljeroth, P.; Quinn, B.M.

    2008-01-01

    We demonstrate that scanning electrochemical microscopy (SECM) can be used to determine the conductivity of nanoparticle assemblies as a function of assembly potential. In contrast to conventional electron transport measurements, this method is unique in that electrical connection to the film is not

  2. Electrochemical Hydrogen Compressor

    Energy Technology Data Exchange (ETDEWEB)

    David P. Bloomfield; Brian S. MacKenzie

    2006-05-01

    determine the loss of membrane active sites is recommended. We suspect that the corrosion includes more than simple galvanic mechanisms. The mechanisms involved in this phenomenon are poorly understood. Shunt currents at hydraulic cathode ports were problematic, but are not difficult to cure. In addition to corrosion there is evidence of high component resistivity. This may be due to the deposition of organic compounds, which may be produced electrochemically on the surface of the metal support screens that contact carbon gas diffusion layers (GDLs) or catalyst supports. An investigation of possible electro-organic sythesis mechanisms with emphasis on oxalates formation is warranted. The contaminated cell parts can be placed in an oxidizing atmosphere at high temperature and the weight loss can be observed. This would reveal the existence of organic compounds. Investigation into the effects of conductivity enhancers such as carbon microlayers on supporting carbon paper is also needed. Corrosion solutions should be investigated such as surface passivation of 316 SS parts using nitric acid. Ultra thin silane/siloxane polymer coatings should be tried. These may be especially useful in conjunction with metal felt replacement of carbon paper. A simple cure for the very high, localized corrosion of the anode might be to diffusion bond the metal electrode support screen to bipolar plate. This will insure uniform resistance perpendicular to the plane of the cell and eliminate some of the dependence of the resistance on high stack compression. Alternative materials should be explored. Alternatives to carbon in the cell may be helpful in any context. In particular, alternatives to carbon paper GDLs such as metal felts and alternatives to carbon supports for Pt such as TiC and TiB2 might also be worthwhile and would be helpful to fuel cells as well. Some alternative to the metals we used in the cell, Mo and 316 SS, are potentially useful. These include Al/Mg/Si alloys. Corrosion

  3. Electrochemical metallization memories-fundamentals, applications, prospects

    International Nuclear Information System (INIS)

    This review focuses on electrochemical metallization memory cells (ECM), highlighting their advantages as the next generation memories. In a brief introduction, the basic switching mechanism of ECM cells is described and the historical development is sketched. In a second part, the full spectra of materials and material combinations used for memory device prototypes and for dedicated studies are presented. In a third part, the specific thermodynamics and kinetics of nanosized electrochemical cells are described. The overlapping of the space charge layers is found to be most relevant for the cell properties at rest. The major factors determining the functionality of the ECM cells are the electrode reaction and the transport kinetics. Depending on electrode and/or electrolyte material electron transfer, electro-crystallization or slow diffusion under strong electric fields can be rate determining. In the fourth part, the major device characteristics of ECM cells are explained. Emphasis is placed on switching speed, forming and SET/RESET voltage, RON to ROFF ratio, endurance and retention, and scaling potentials. In the last part, circuit design aspects of ECM arrays are discussed, including the pros and cons of active and passive arrays. In the case of passive arrays, the fundamental sneak path problem is described and as well as a possible solution by two anti-serial (complementary) interconnected resistive switches per cell. Furthermore, the prospects of ECM with regard to further scalability and the ability for multi-bit data storage are addressed. (topical review)

  4. Electrochemical metallization memories—fundamentals, applications, prospects

    Science.gov (United States)

    Valov, Ilia; Waser, Rainer; Jameson, John R.; Kozicki, Michael N.

    2011-06-01

    This review focuses on electrochemical metallization memory cells (ECM), highlighting their advantages as the next generation memories. In a brief introduction, the basic switching mechanism of ECM cells is described and the historical development is sketched. In a second part, the full spectra of materials and material combinations used for memory device prototypes and for dedicated studies are presented. In a third part, the specific thermodynamics and kinetics of nanosized electrochemical cells are described. The overlapping of the space charge layers is found to be most relevant for the cell properties at rest. The major factors determining the functionality of the ECM cells are the electrode reaction and the transport kinetics. Depending on electrode and/or electrolyte material electron transfer, electro-crystallization or slow diffusion under strong electric fields can be rate determining. In the fourth part, the major device characteristics of ECM cells are explained. Emphasis is placed on switching speed, forming and SET/RESET voltage, RON to ROFF ratio, endurance and retention, and scaling potentials. In the last part, circuit design aspects of ECM arrays are discussed, including the pros and cons of active and passive arrays. In the case of passive arrays, the fundamental sneak path problem is described and as well as a possible solution by two anti-serial (complementary) interconnected resistive switches per cell. Furthermore, the prospects of ECM with regard to further scalability and the ability for multi-bit data storage are addressed.

  5. Stochastic Electrochemical Kinetics

    CERN Document Server

    Beruski, O

    2016-01-01

    A model enabling the extension of the Stochastic Simulation Algorithm to electrochemical systems is proposed. The physical justifications and constraints for the derivation of a chemical master equation are provided and discussed. The electrochemical driving forces are included in the mathematical framework, and equations are provided for the associated electric responses. The implementation for potentiostatic and galvanostatic systems is presented, with results pointing out the stochastic nature of the algorithm. The electric responses presented are in line with the expected results from the theory, providing a new tool for the modeling of electrochemical kinetics.

  6. Free-Standing, Nanopatterned Janus Membranes of Conducting Polymer-Virus Nanoparticle Arrays.

    Science.gov (United States)

    Tiu, Brylee David B; Tiu, Sicily B; Wen, Amy M; Lam, Patricia; Steinmetz, Nicole F; Advincula, Rigoberto C

    2016-06-21

    Nanostructured mesoscale materials find wide-ranging applications in medicine and energy. Top-down manufacturing schemes are limited by the smallest dimension accessible; therefore, we set out to study a bottom-up approach mimicking biological systems, which self-assemble into systems that orchestrate complex energy conversion functionalities. Inspired by nature, we turned toward protein-based nanoparticle structures formed by plant viruses, specifically the cowpea mosaic virus (CPMV). We report the formation of hierarchical CPMV nanoparticle assemblies on colloidal-patterned, conducting polymer arrays using a protocol combining colloidal lithography, electrochemical polymerization, and electrostatic adsorption. In this approach, a hexagonally close-packed array of polystyrene microspheres was assembled on a conductive electrode to function as the sacrificial colloidal template. A thin layer of conducting polypyrrole material was electrodeposited within the interstices of the colloidal microspheres and monitored in situ using electrochemical quartz crystal microbalance with dissipation (EC-QCM-D). Etching the template revealed an inverse opaline conducting polymer pattern capable of forming strong electrostatic interactions with CPMV and therefore enabling immobilization of CPMV on the surface. The CPMV-polymer films were characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Furthermore, molecular probe diffusion experiments revealed selective ion transport properties as a function of the presence of the CPMV nanoparticles on the surface. Lastly, by utilizing its electromechanical behavior, the polymer/protein membrane was electrochemically released as a free-standing film, which can potentially be used for developing high surface area cargo delivery systems, stimuli-responsive plasmonic devices, and chemical and biological sensors. PMID:27244119

  7. Photoelectrochemistry of Semiconductor Nanowire Arrays

    Energy Technology Data Exchange (ETDEWEB)

    Mallouk, Thomas E; Redwing, Joan M

    2009-11-10

    This project supported research on the growth and photoelectrochemical characterization of semiconductor nanowire arrays, and on the development of catalytic materials for visible light water splitting to produce hydrogen and oxygen. Silicon nanowires were grown in the pores of anodic aluminum oxide films by the vapor-liquid-solid technique and were characterized electrochemically. Because adventitious doping from the membrane led to high dark currents, silicon nanowire arrays were then grown on silicon substrates. The dependence of the dark current and photovoltage on preparation techniques, wire diameter, and defect density was studied for both p-silicon and p-indium phosphide nanowire arrays. The open circuit photovoltage of liquid junction cells increased with increasing wire diameter, reaching 350 mV for micron-diameter silicon wires. Liquid junction and radial p-n junction solar cells were fabricated from silicon nano- and microwire arrays and tested. Iridium oxide cluster catalysts stabilized by bidentate malonate and succinate ligands were also made and studied for the water oxidation reaction. Highlights of this project included the first papers on silicon and indium phosphide nanowire solar cells, and a new procedure for making ligand-stabilized water oxidation catalysts that can be covalently linked to molecular photosensitizers or electrode surfaces.

  8. Dynamics of electrochemical flows 3 Closure models

    CERN Document Server

    Xu, Chengjun

    2013-01-01

    The electrolyte (comprising of solute ions and solvents) flow-through the porous media is frequently encountered in nature or in many engineering applications, such as the electrochemical systems, manufacturing of composites, oil production, geothermal engineering, nuclear thermal disposal, soil pollution. Our previous work derived the interfacial interaction terms between the solid and the fluid, which can be used to investigate the details of transports of mass, heat, electric flied, potential, or momentum in the process of the electrochemical flows-through porous electrode. In this work, we establish the closure models for these interfacial interaction terms to close the governing equations from mathematical algebra. The interfacial interaction terms regard to the electric field, potential and electric force are firstly revealed. Our new theory provides a new approach to describe the electrochemical flows-through porous media.

  9. Graphene to Graphane: Novel Electrochemical Conversion

    CERN Document Server

    Daniels, Kevin M; Zhang, R; Chowdhury, I; Obe, A; Weidner, J; Williams, C; Sudarshan, T S; Chandrashekhar, MVS

    2010-01-01

    A novel electrochemical means to generate atomic hydrogen, simplifying the synthesis and controllability of graphane formation on graphene is presented. High quality, vacuum grown epitaxial graphene (EG) was used as starting material for graphane conversion. A home-built electrochemical cell with Pt wire and exposed graphene as the anode and cathode, respectively, was used to attract H+ ions to react with the exposed graphene. Cyclic voltammetry of the cell revealed the potential of the conversion reaction as well as oxidation and reduction peaks, suggesting the possibility of electrochemically reversible hydrogenation. A sharp increase in D peak in the Raman spectra of EG, increase of D/G ratio, introduction of a peak at ~2930 cm-1 and respective peak shifts as well as a sharp increase in resistance showed the successful hydrogenation of EG. This conversion was distinguished from lattice damage by thermal reversal back to graphene at 1000{\\deg}C.

  10. Fundamentals of electrochemical science

    CERN Document Server

    Oldham, Keith

    1993-01-01

    Key Features* Deals comprehensively with the basic science of electrochemistry* Treats electrochemistry as a discipline in its own right and not as a branch of physical or analytical chemistry* Provides a thorough and quantitative description of electrochemical fundamentals

  11. Electrochemical Analysis of Neurotransmitters

    Science.gov (United States)

    Bucher, Elizabeth S.; Wightman, R. Mark

    2015-07-01

    Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.

  12. Electrochemical Oxidation of Rutin

    OpenAIRE

    Ghica, Mariana-Emilia; Brett, Ana Maria Oliveira

    2005-01-01

    An electrochemical investigation of rutin oxidation on a glassy carbon electrode was carried out using cyclic voltammetry, differential pulse voltammetry and square-wave voltammetry over a wide pH interval. The electrochemical oxidation is a complex process, which proceeds in a cascade mechanism, related with the 4-hydroxyl groups of the rutin molecule. The catechol 3prime,4prime-dihydroxyl group is the first to be oxidized by a two-electron - two-proton reversible oxidation reaction, followe...

  13. Electrochemical Energy Storage Branch

    Science.gov (United States)

    1985-01-01

    The activities of the Electrochemical Energy Storage Branch are highlighted, including the Technology Base Research and the Exploratory Technology Development and Testing projects within the Electrochemical Energy Storage Program for the 1984 fiscal year. General Headquarters activities are presented first; and then, a summary of the Director Controlled Milestones, followed by other major accomplishments. A listing of the workshops and seminars held during the year is also included.

  14. Solid state electrochemical composite

    Science.gov (United States)

    Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

    2009-06-30

    Provided is a composite electrochemical device fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems including oxygen generation system.

  15. Electrochemical polymer electrolyte membranes

    CERN Document Server

    Fang, Jianhua; Wilkinson, David P

    2015-01-01

    Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Discusses cutting-edge methodologies in PEM material selection and fabricationPoints out important challenges in developing PEMs and recommends mitigation strategies to improve PEM performanceAnalyzes the cur

  16. Electrochemical fabrication of 2D and 3D nickel nanowires using porous anodic alumina templates

    Science.gov (United States)

    Mebed, A. M.; Abd-Elnaiem, Alaa M.; Al-Hosiny, Najm M.

    2016-06-01

    Mechanically stable nickel (Ni) nanowires array and nanowires network were synthesized by pulse electrochemical deposition using 2D and 3D porous anodic alumina (PAA) templates. The structures and morphologies of as-prepared films were characterized by X-ray diffraction and scanning electron microscopy, respectively. The grown Ni nanowire using 3D PAA revealed more strength and larger surface area than has grown Ni use 2D PAA template. The prepared nanowires have a face-centered cubic crystal structure with average grain size 15 nm, and the preferred orientation of the nucleation of the nanowires is (111). The diameter of the nanowires is about 50-70 nm with length 3 µm. The resulting 3D Ni nanowire lattice, which provides enhanced mechanical stability and an increased surface area, benefits energy storage and many other applications which utilize the large surface area.

  17. A Fast, Sensitive and Label Free Electrochemical DNA Sensor

    International Nuclear Information System (INIS)

    A label free and sensitive DNA/RNA silicon based electrochemical microsensor array was developed by using thin film of the conducting polymer polypyrrole doped with an oligonucleotide probe. The electrochemical potential pulse amperometry technique was used for a biowarfare pathogen target DNA detection. The electrical potential assistanted DNA hybridisation method was applied. The sensor signal was increased by increasing the electrical potential assistanted DNA hybridisation time. It was possible to detect 0.34pmol and 0.072fmol of complementary oligonucleotide target in 0.1ml in seconds by using unpolished and polished gold electrode respectively. The probe preparation was also in seconds time, comparing indirect electrochemical DNA sensor, it has a fast sensor preparation as well as sensor response and label free advantages. The silicon microfabrication technique was used for this sensor array fabrication, which holds the potential to integrate with sensor electrical circuits. The conducting polymer polypyrrole was electrochemically deposited on each electrode respectively which has a possibility to dope the different DNA probe into the individual electrode to form a sensor array

  18. 2D and 3D ordered arrays of Co magnetic nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, J. [Departamento de Física, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo, Asturias (Spain); Prida, V.M., E-mail: vmpp@uniovi.es [Departamento de Física, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo, Asturias (Spain); Vega, V. [Departamento de Física, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo, Asturias (Spain); Rosa, W.O. [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150 Urca., 22290-180 Rio de Janeiro, RJ (Brazil); Caballero-Flores, R.; Iglesias, L.; Hernando, B. [Departamento de Física, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo, Asturias (Spain)

    2015-06-01

    arrays were electrochemically deposited grown in 2D and 3D pore arrangements of planar and cylindrical nanoporous anodic alumina templates. • The intrinsic magnetic properties of Co nanowires grown in both 2D and 3D alumina templates appear to be independent of the geometry of the arrangement. • FORC analysis along the radial axis of Co nanowires array reveals that the magnetization reversal process depends on each nanowire orientation to the applied field direction.

  19. 2D and 3D ordered arrays of Co magnetic nanowires

    International Nuclear Information System (INIS)

    arrays were electrochemically deposited grown in 2D and 3D pore arrangements of planar and cylindrical nanoporous anodic alumina templates. • The intrinsic magnetic properties of Co nanowires grown in both 2D and 3D alumina templates appear to be independent of the geometry of the arrangement. • FORC analysis along the radial axis of Co nanowires array reveals that the magnetization reversal process depends on each nanowire orientation to the applied field direction

  20. Fabrication of ultrahigh-density nanowires by electrochemical nanolithography

    Directory of Open Access Journals (Sweden)

    Jiang Hongquan

    2011-01-01

    Full Text Available Abstract An approach has been developed to produce silver nanoparticles (AgNPs rapidly on semiconductor wafers using electrochemical deposition. The closely packed AgNPs have a density of up to 1.4 × 1011 cm-2 with good size uniformity. AgNPs retain their shape and position on the substrate when used as nanomasks for producing ultrahigh-density vertical nanowire arrays with controllable size, making it a one-step nanolithography technique. We demonstrate this method on Si/SiGe multilayer superlattices using electrochemical nanopatterning and plasma etching to obtain high-density Si/SiGe multilayer superlattice nanowires.

  1. Electrochemical reduction of NOx

    DEFF Research Database (Denmark)

    Traulsen, Marie Lund

    NO and NO2 (collectively referred to as NOx) are air pollutants, and the largest single contributor to NOx pollution is automotive exhaust. This study investigates electrochemical deNOx, a technology which aims to remove NOx from automotive diesel exhaust by electrochemical reduction of NOx to N2...... and O2. The focus in this study is on improving the activity and selectivity of solid oxide electrodes for electrochemical deNOx by addition of NOx storage compounds to the electrodes. Two different composite electrodes, La0.85Sr0.15MnO3-δ-Ce0.9Gd0.1O1.95 (LSM15-CGO10) and La0.85Sr0.15FeO3-δ-Ce0.9Gd0.1O......1.95 (LSF15-CGO10), have been investigated in combination with three different NOx storage compounds: BaO, K2O and MnOx. The main focus in the investigation has been on conversion measurements and electrochemical characterization, the latter by means of electrochemical impedance spectroscopy...

  2. Simultaneous Nanomechanical and Electrochemical Mapping: Combining Peak Force Tapping Atomic Force Microscopy with Scanning Electrochemical Microscopy.

    Science.gov (United States)

    Knittel, Peter; Mizaikoff, Boris; Kranz, Christine

    2016-06-21

    Soft electronic devices play a crucial role in, e.g., neural implants as stimulating electrodes, transducers for biosensors, or selective drug-delivery. Because of their elasticity, they can easily adapt to their environment and prevent immunoreactions leading to an overall improved long-term performance. In addition, flexible electronic devices such as stretchable displays will be increasingly used in everyday life, e.g., for so-called electronic wearables. Atomic force microscopy (AFM) is a versatile tool to characterize these micro- and nanostructured devices in terms of their topography. Using advanced imaging techniques such as peak force tapping (PFT), nanomechanical properties including adhesion, deformation, and Young's modulus can be simultaneously mapped along with surface features. However, conventional AFM provides limited laterally resolved information on electrical or electrochemical properties such as the activity of an electrode array. In this study, we present the first combination of AFM with scanning electrochemical microscopy (SECM) in PFT mode, thereby offering spatially correlated electrochemical and nanomechanical information paired with high-resolution topographical data under force control (QNM-AFM-SECM). The versatility of this combined scanning probe approach is demonstrated by mapping topographical, electrochemical, and nanomechanical properties of gold microelectrodes and of gold electrodes patterned onto polydimethylsiloxane.

  3. Engineering electrochemical capacitor applications

    Science.gov (United States)

    Miller, John R.

    2016-09-01

    Electrochemical capacitor (EC) applications have broadened tremendously since EC energy storage devices were introduced in 1978. Then typical applications operated below 10 V at power levels below 1 W. Today many EC applications operate at voltages approaching 1000 V at power levels above 100 kW. This paper briefly reviews EC energy storage technology, shows representative applications using EC storage, and describes engineering approaches to design EC storage systems. Comparisons are made among storage systems designed to meet the same application power requirement but using different commercial electrochemical capacitor products.

  4. Electrochemical energy storage

    CERN Document Server

    Tarascon, Jean-Marie

    2015-01-01

    The electrochemical storage of energy has become essential in assisting the development of electrical transport and use of renewable energies. French researchers have played a key role in this domain but Asia is currently the market leader. Not wanting to see history repeat itself, France created the research network on electrochemical energy storage (RS2E) in 2011. This book discusses the launch of RS2E, its stakeholders, objectives, and integrated structure that assures a continuum between basic research, technological research and industries. Here, the authors will cover the technological

  5. Electrochemical Hydrogen Evolution

    DEFF Research Database (Denmark)

    Laursen, A.B.; Varela Gasque, Ana Sofia; Dionigi, F.;

    2012-01-01

    The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing new, inexpensive, and abundant HER catalysts is important. Here, we describe how a simple experiment...... catalysts based on this. Suited for upper-level high school and first-year university students, this exercise involves using a basic two-cell electrochemical setup to test multiple electrode materials as catalysts at one applied potential, and then constructing a volcano curve with the resulting currents...

  6. Biological properties of nanostructured Ti incorporated with Ca, P and Ag by electrochemical method

    Energy Technology Data Exchange (ETDEWEB)

    Li, Baoe; Hao, Jingzu; Min, Yang [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Xin, Shigang [Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Guo, Litong [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); He, Fei [National Key Laboratory of C1 Chemical Industry, Tianjin University, Tianjin 300072 (China); Liang, Chunyong; Wang, Hongshui [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Li, Haipeng, E-mail: lhpcx@163.com [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2015-06-01

    TiO{sub 2} nanotube arrays were synthesized on Ti surface by anodic oxidation. The elements of Ca and P were simultaneously incorporated during nanotubes growth in SBF electrolyte, and then Ag was introduced to nanotube arrays by cathodic deposition, which endowed the good osseointegration and antibacterial property of Ti. The bioactivity of the Ti surface was evaluated by simulated body fluid soaking test. The biocompatibility was investigated by in vitro cell culture test. And the antibacterial effect against Staphylococcus aureus was examined by the bacterial counting method. The results showed that the incorporation of Ca, P and Ag elements had no significant influence on the formation of nanotube arrays on Ti surface during electrochemical treatment. Compared to the polished or nanotubular Ti surface, TiO{sub 2} nanotube arrays incorporated with Ca, P and Ag increased the formation of bone-like apatite in simulated body fluid, enhanced cell adhesion and proliferation, and inhibited the bacterial growth. Based on these results, it can be concluded that the nanostructured Ti incorporated with Ca, P and Ag by electrochemical method has promising applications as implant material. - Highlights: • Nanotube arrays were prepared on Ti surface by anodic oxidation. • Ca, P and Ag were incorporated to nanotube arrays by electrochemical method. • Ca, P and Ag endowed Ti with good osseointegration and antibacterial property. • The beneficial effect of electrochemical treatment on Ti implant was demonstrated.

  7. Electrochemical camera chip for simultaneous imaging of multiple metabolites in biofilms.

    Science.gov (United States)

    Bellin, Daniel L; Sakhtah, Hassan; Zhang, Yihan; Price-Whelan, Alexa; Dietrich, Lars E P; Shepard, Kenneth L

    2016-01-01

    Monitoring spatial distribution of metabolites in multicellular structures can enhance understanding of the biochemical processes and regulation involved in cellular community development. Here we report on an electrochemical camera chip capable of simultaneous spatial imaging of multiple redox-active phenazine metabolites produced by Pseudomonas aeruginosa PA14 colony biofilms. The chip features an 8 mm × 8 mm array of 1,824 electrodes multiplexed to 38 parallel output channels. Using this chip, we demonstrate potential-sweep-based electrochemical imaging of whole-biofilms at measurement rates in excess of 0.2 s per electrode. Analysis of mutants with various capacities for phenazine production reveals distribution of phenazine-1-carboxylic acid (PCA) throughout the colony, with 5-methylphenazine-1-carboxylic acid (5-MCA) and pyocyanin (PYO) localized to the colony edge. Anaerobic growth on nitrate confirms the O2-dependence of PYO production and indicates an effect of O2 availability on 5-MCA synthesis. This integrated-circuit-based technique promises wide applicability in detecting redox-active species from diverse biological samples. PMID:26813638

  8. Structural, electrochemical and theoretical study of a new chalcone derivative containing 3-thiophene rings

    Science.gov (United States)

    Baggio, Ricardo; Brovelli, Francisco; Moreno, Yanko; Pinto, Marcela; Soto-Delgado, Jorge

    2016-11-01

    The title chalcone, 1,3-di(thiophene-3-yl)prop-2-en-1-one (C11H8OS2) is an essentially planar molecular with its terminal thiophene rings subtending an angle of 8.9°. The crystal structure consists in the π··π stacking of molecules defining columns along [010], further linked along c by non conventional Csbnd H⋯O bonds, thus determining broad planar arrays parallel to (100). In addition, there are weak S⋯S contacts connecting these weakly interacting 2D substructures. The experimental results obtained from single crystal X-ray diffraction data and the theoretical geometry calculated by molecular mechanics are in good agreement. Electrochemical records reveal an anodic profile with an unsymmetrical irreversible peak at 1.77 V and a shoulder at 1.62 V vs SCE, a behavior interpretable as due to the oxidation of reactive sites present in the molecule. On the other hand, the electrochemical reduction shows a narrow peak at -1.58 V vs SCE, a fact attributable to the carbonyl group. Finally, the values for the energy involved in the departure/arrival of electrons from border orbitals, as calculated using DFT, is compared with experimental data from cyclic voltammetry.

  9. Novel electrochemical reactions related to electrodeposition and electrochemical synthesis

    Directory of Open Access Journals (Sweden)

    Ito Y.

    2003-01-01

    Full Text Available Novel electrochemical reactions in molten salts related to electrodeposition and electrochemical synthesis are reviewed to show their usefulness and possibilities in producing functional materials. Surface nitriding of various metals and stainless steels is possible by the use of anodic reaction of nitride ion (N3- in LiCl-KCl-Li3N melts. Electrochemical hydrogen absorption/desorption reaction occurs in molten salts containing hydride ion (H-. Electrochemical implantation and displantation can be applied to form transition metal-rare earth metal alloys in LiCl-KCl melts containing rare earth chlorides. As non-conventional electrochemical reactions, direct electrochemical reduction of SiO2 to Si, discharge electrolysis to form metal oxide particles and electrochemical plantation of Zr on ceramics are described.

  10. Synthesis, electrochemical properties, and crystal packing of perfluororubrene.

    Science.gov (United States)

    Zhang, Zhuoran; Ogden, William A; Young, Victor G; Douglas, Christopher J

    2016-06-21

    A synthesis of perfluorinated rubrene is reported. Electrochemical analysis revealed the significantly increased electron affinity of perfluororubrene compared with non-modified rubrene. Crystallographic investigation revealed two polymorphs and a solvate, each displaying twisted backbone conformations of perfluororubrene. Taken together, these results suggest perfluororubrene will find applications as a new n-type semiconductor. PMID:27271849

  11. Dissecting graphene capacitance in electrochemical cell

    International Nuclear Information System (INIS)

    Quantum capacitance of graphene plays a significant role for graphene's applications in electrochemical devices and sensors, while the determination of these basic characters of Dirac point, Fermi energy, quantum capacitance, etc is still a subject of considerable debate in both experiments and simulations. Here, we report joint first-principles/continuum calculations (JFPCCs) on a monolayer graphene electrode immersed in an electrolyte coupled with a reference electrode under an applied potential. The JFPCCs gave the Fermi level, charge density on graphene, Dirac point energy, electrostatic potential, electric double layer etc as a function of the applied potential with respect to the reference electrode. These results revealed the strongly coupled relationship between Fermi level change and Dirac point shift in electrochemical cell. The total capacitance of the electrochemical cell was dissected into the quantum capacitance of the graphene electrode and the capacitance of the electric double layer. Furthermore, simple and analytic formulas were proposed for the three capacitances, which predicted, in sufficient accuracy, the behavior of capacitance versus potential. These findings deepen the understanding of quantum capacitance of graphene, which will stimulate novel experimental and theoretical studies and boost the applications of graphene in electrochemical and energy areas

  12. Electrochemical biosensors and nanobiosensors.

    Science.gov (United States)

    Hammond, Jules L; Formisano, Nello; Estrela, Pedro; Carrara, Sandro; Tkac, Jan

    2016-06-30

    Electrochemical techniques have great promise for low-cost miniaturised easy-to-use portable devices for a wide range of applications-in particular, medical diagnosis and environmental monitoring. Different techniques can be used for biosensing, with amperometric devices taking the central role due to their widespread application in glucose monitoring. In fact, glucose biosensing takes an approximately 70% share of the biosensor market due to the need for diabetic patients to monitor their sugar levels several times a day, making it an appealing commercial market.In this review, we present the basic principles of electrochemical biosensor devices. A description of the different generations of glucose sensors is used to describe in some detail the operation of amperometric sensors and how the introduction of mediators can enhance the performance of the sensors. Electrochemical impedance spectroscopy is a technique being increasingly used in devices due to its ability to detect variations in resistance and capacitance upon binding events. Novel advances in electrochemical sensors, due to the use of nanomaterials such as carbon nanotubes and graphene, are presented as well as future directions that the field is taking. PMID:27365037

  13. Electrochemical biosensors and nanobiosensors.

    Science.gov (United States)

    Hammond, Jules L; Formisano, Nello; Estrela, Pedro; Carrara, Sandro; Tkac, Jan

    2016-06-30

    Electrochemical techniques have great promise for low-cost miniaturised easy-to-use portable devices for a wide range of applications-in particular, medical diagnosis and environmental monitoring. Different techniques can be used for biosensing, with amperometric devices taking the central role due to their widespread application in glucose monitoring. In fact, glucose biosensing takes an approximately 70% share of the biosensor market due to the need for diabetic patients to monitor their sugar levels several times a day, making it an appealing commercial market.In this review, we present the basic principles of electrochemical biosensor devices. A description of the different generations of glucose sensors is used to describe in some detail the operation of amperometric sensors and how the introduction of mediators can enhance the performance of the sensors. Electrochemical impedance spectroscopy is a technique being increasingly used in devices due to its ability to detect variations in resistance and capacitance upon binding events. Novel advances in electrochemical sensors, due to the use of nanomaterials such as carbon nanotubes and graphene, are presented as well as future directions that the field is taking.

  14. An electrochemical micro actuator

    NARCIS (Netherlands)

    Hamberg, M.W.; Neagu, C.R.; Gardeniers, J.G.E.; IJntema, D.J.; Elwenspoek, M.C.

    1995-01-01

    In this paper an investigation of the feasibility of a new electrochemical micro actuator is presented. The actuator is fabricated using silicon micro-machining techniques. A gas pressure is generated by electrolysis of an aqueous electrolyte solution. The build up pressure is used to change the def

  15. Electrochemical biosensors and nanobiosensors

    Science.gov (United States)

    Hammond, Jules L.; Formisano, Nello; Carrara, Sandro; Tkac, Jan

    2016-01-01

    Electrochemical techniques have great promise for low-cost miniaturised easy-to-use portable devices for a wide range of applications–in particular, medical diagnosis and environmental monitoring. Different techniques can be used for biosensing, with amperometric devices taking the central role due to their widespread application in glucose monitoring. In fact, glucose biosensing takes an approximately 70% share of the biosensor market due to the need for diabetic patients to monitor their sugar levels several times a day, making it an appealing commercial market. In this review, we present the basic principles of electrochemical biosensor devices. A description of the different generations of glucose sensors is used to describe in some detail the operation of amperometric sensors and how the introduction of mediators can enhance the performance of the sensors. Electrochemical impedance spectroscopy is a technique being increasingly used in devices due to its ability to detect variations in resistance and capacitance upon binding events. Novel advances in electrochemical sensors, due to the use of nanomaterials such as carbon nanotubes and graphene, are presented as well as future directions that the field is taking. PMID:27365037

  16. A reusable device for electrochemical applications of hydrogel supported black lipid membranes

    DEFF Research Database (Denmark)

    Mech-Dorosz, Agnieszka; Heiskanen, Arto; Bäckström, Sania;

    2015-01-01

    the ETFE substrate and a gold electrode microchip, thus allowing direct electrochemical studies with the integrated working electrodes. Using electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy and contact angle measurements, we demonstrate the optimized chemical modifications...... of the gold electrode microchips and plasma modification of the ETFE aperture arrays facilitating covalent "sandwiching" of the hydrogel. Both fluorescence microscopy and EIS were used to demonstrate the induced spontaneous thinning of a deposited lipid solution, leading to formation of stabilized hs...

  17. Bromination of Marine Dissolved Organic Matter following Full Scale Electrochemical Ballast Water Disinfection.

    Science.gov (United States)

    Gonsior, Michael; Mitchelmore, Carys; Heyes, Andrew; Harir, Mourad; Richardson, Susan D; Petty, William Tyler; Wright, David A; Schmitt-Kopplin, Philippe

    2015-08-01

    An extensively diverse array of brominated disinfection byproducts (DBPs) were generated following electrochemical disinfection of natural coastal/estuarine water, which is one of the main treatment methods currently under consideration for ballast water treatment. Ultra-high-resolution mass spectrometry revealed 462 distinct brominated DBPs at a relative abundance in the mass spectra of more than 1%. A brominated DBP with a relative abundance of almost 22% was identified as 2,2,4-tribromo-5-hydroxy-4-cyclopentene-1,3-dione, which is an analogue to several previously described 2,2,4-trihalo-5-hydroxy-4-cyclopentene-1,3-diones in drinking water. Several other brominated molecular formulas matched those of other known brominated DBPs, such as dibromomethane, which could be generated by decarboxylation of dibromoacetic acid during ionization, dibromophenol, dibromopropanoic acid, dibromobutanoic acid, bromohydroxybenzoic acid, bromophenylacetic acid, bromooxopentenoic acid, and dibromopentenedioic acid. Via comparison to previously described chlorine-containing analogues, bromophenylacetic acid, dibromooxopentenoic acid, and dibromopentenedioic acid were also identified. A novel compound at a 4% relative abundance was identified as tribromoethenesulfonate. This compound has not been previously described as a DBP, and its core structure of tribromoethene has been demonstrated to show toxicological implications. Here we show that electrochemical disinfection, suggested as a candidate for successful ballast water treatment, caused considerable production of some previously characterized DBPs in addition to novel brominated DBPs, although several hundred compounds remain structurally uncharacterized. Our results clearly demonstrate that electrochemical and potentially direct chlorination of ballast water in estuarine and marine systems should be approached with caution and the concentrations, fate, and toxicity of DBP need to be further characterized.

  18. Interpenetrating polyaniline-gold electrodes for SERS and electrochemical measurements

    Science.gov (United States)

    West, R. M.; Semancik, S.

    2016-11-01

    Facile fabrication of nanostructured electrode arrays is critical for development of bimodal SERS and electrochemical biosensors. In this paper, the variation of applied potential at a polyaniline-coated Pt electrode is used to selectivity deposit Au on the polyaniline amine sites or on the underlying Pt electrode. By alternating the applied potential, the Au is grown simultaneously from the top and the bottom of the polyaniline film, leading to an interpenetrated, nanostructured polymer-metal composite extending from the Pt electrode to the electrolyte solution. The resulting films have unique pH-dependent electrochemical properties, e.g. they retain electrochemical activity in both acidic and neutral solutions, and they also include SERS-active nanostructures. By varying the concentration of chloroaurate used during deposition, Au nanoparticles, nanodendrites, or nanosheets can be selectively grown. For the films deposited under optimal conditions, using 5 mmol/L chloroaurate, the SERS enhancement factor for Rhodamine 6G was found to be as high as 1.1 × 106 with spot-to-spot and electrode-to-electrode relative standard deviations as low as 8% and 12%, respectively. The advantages of the reported PANI-Au composite electrodes lie in their facile fabrication, enabling the targeted deposition of tunable nanostructures on sensing arrays, and their ability to produce orthogonal optical and electrochemical analytical results.

  19. Nanohole Array-Directed Trapping of Mammalian Mitochondria Enabling Single Organelle Analysis.

    Science.gov (United States)

    Kumar, Shailabh; Wolken, Gregory G; Wittenberg, Nathan J; Arriaga, Edgar A; Oh, Sang-Hyun

    2015-12-15

    We present periodic nanohole arrays fabricated in free-standing metal-coated nitride films as a platform for trapping and analyzing single organelles. When a microliter-scale droplet containing mitochondria is dispensed above the nanohole array, the combination of evaporation and capillary flow directs individual mitochondria to the nanoholes. Mammalian mitochondria arrays were rapidly formed on chip using this technique without any surface modification steps, microfluidic interconnects, or external power sources. The trapped mitochondria were depolarized on chip using an ionophore with results showing that the organelle viability and behavior were preserved during the on-chip assembly process. Fluorescence signal related to mitochondrial membrane potential was obtained from single mitochondria trapped in individual nanoholes revealing statistical differences between the behavior of polarized vs depolarized mammalian mitochondria. This technique provides a fast and stable route for droplet-based directed localization of organelles-on-a-chip with minimal limitations and complexity, as well as promotes integration with other optical or electrochemical detection techniques. PMID:26593329

  20. Arrays of Screen-Printed Graphite Microband Electrodes as a Versatile Electroanalysis Platform

    OpenAIRE

    Vagin, Mikhail; Sekretareva, Alina; Sanchez, Rafael; Lundström, Ingemar; Winquist, Fredrik; Eriksson, Mats

    2014-01-01

    Arrays of microband electrodes were developed by screen printing followed by cutting, which enabled the realization of microband arrays at the cut edge. The microband arrays of different designs were characterized by physical and electro-chemical methods. In both cases, the methods showed that the microband width was around 5 mm. Semi-steady-state cyclic voltammetry responses were observed for redox probes, and chronocoulometric measurements showed the establishment of convergent diffusion re...

  1. Electrochemical Detection of Multiple Bioprocess Analytes

    Science.gov (United States)

    Rauh, R. David

    2010-01-01

    An apparatus that includes highly miniaturized thin-film electrochemical sensor array has been demonstrated as a prototype of instruments for simultaneous detection of multiple substances of interest (analytes) and measurement of acidity or alkalinity in bioprocess streams. Measurements of pH and of concentrations of nutrients and wastes in cell-culture media, made by use of these instruments, are to be used as feedback for optimizing the growth of cells or the production of desired substances by the cultured cells. The apparatus is designed to utilize samples of minimal volume so as to minimize any perturbation of monitored processes. The apparatus can function in a potentiometric mode (for measuring pH), an amperometric mode (detecting analytes via oxidation/reduction reactions), or both. The sensor array is planar and includes multiple thin-film microelectrodes covered with hydrous iridium oxide. The oxide layer on each electrode serves as both a protective and electrochemical transducing layer. In its transducing role, the oxide provides electrical conductivity for amperometric measurement or pH response for potentiometric measurement. The oxide on an electrode can also serve as a matrix for one or more enzymes that render the electrode sensitive to a specific analyte. In addition to transducing electrodes, the array includes electrodes for potential control. The array can be fabricated by techniques familiar to the microelectronics industry. The sensor array is housed in a thin-film liquid-flow cell that has a total volume of about 100 mL. The flow cell is connected to a computer-controlled subsystem that periodically draws samples from the bioprocess stream to be monitored. Before entering the cell, each 100-mL sample is subjected to tangential-flow filtration to remove particles. In the present version of the apparatus, the electrodes are operated under control by a potentiostat and are used to simultaneously measure the pH and the concentration of glucose

  2. Surface Modification Mechanism of Fine Coal by Electrochemical Methods

    Institute of Scientific and Technical Information of China (English)

    ZHU Hong; WANG Fang-hui; WANG Dian-zuo; OU Ze-shen

    2006-01-01

    In order to reveal the surface modification mechanism of fine coal by electrochemical methods, the structural changes of the coal surface before and after electrochemical modification were investigated by Fourier Transform Infrared Spectra (FTIR) and Raman Spectra. The results show that under certain electrochemical conditions, the oxygen-containing functional group in the coal structure and the oxygen content of absorption could be reduced and the floatability of coal improved. At the same time, the sulfur in the coal was reduced to the hydrophilic S2- which could be separated easily from coal. Thus electrochemical modification methods could be used to change the structure and functional group on the coal surface and to enhance the floatability of coal.

  3. Development of nanoporous gold electrodes for electrochemical applications

    DEFF Research Database (Denmark)

    Quan, Xueling; Fischer, Lee MacKenzie; Boisen, Anja;

    2011-01-01

    , X-ray photo-electron spectroscopy and profilometer. The electrochemical performance of the np-Au electrodes was measured by cyclic voltammetry and electrochemical impedance spectroscopy. We have fabricated np-Au electrodes with pore sizes between 10 nm and 60 nm, directly related to the Ag:Au ratio....... The electrochemical results reveal that np-Au electrodes have much lower impedance than the conventional Au electrodes, due to the significantly higher surface area to volume ratio of np-Au. The np-Au electrodes made from Ag66Au34 and Ag60Au40 show more than 10-fold magnitude reduction in impedance compared...... to conventional Au electrodes. These results show that np-Au electrodes have a great potential for electrochemical applications....

  4. Electrochemical Discharge Machining Process

    OpenAIRE

    Anjali V. Kulkarni

    2007-01-01

    Electrochemical discharge machining process is evolving as a promising micromachiningprocess. The experimental investigations in the present work substantiate this trend. In the presentwork, in situ, synchronised, transient temperature and current measurements have been carriedout. The need for the transient measurements arose due to the time-varying nature of the dischargeformation and time varying circuit current. Synchronised and transient measurements revealedthe discrete nature of the pr...

  5. Electrochemical engineering; Genie electrochimique

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, H.; Kreysa, G.

    2001-07-01

    This book makes a link between the principles and the technology of electrochemical engineering and deals successively with: the basic principles, laws and thermodynamics of electrochemistry and mass transfers; the design and development of processes (modeling, optimization, cost analysis); the industrial aspects with several examples of application in chemistry, metal industry, water treatment etc.. (all type of electrodes, processes, cells, materials); a last chapter is entirely devoted to the technology of fuel cells. (J.S.)

  6. Electrochemical flow capacitors

    Science.gov (United States)

    Gogotsi, Yury; Presser, Volker; Kumbur, Emin Caglan

    2015-10-27

    The present invention generally relates to devices for energy storage technologies, and more particularly to electrochemical flow capacitor systems and applications. In some aspects, these flow capacitors have at least one electrode comprising a non-stationary solid or semi-solid composition comprising supercapacitive particles and an electrolytic solvent in electrical communication with at least one current collector, and energy is stored and/or released by charging and/or discharging the electrode(s).

  7. ELECTROCHEMICAL POWER FOR TRANSPORTATION

    Energy Technology Data Exchange (ETDEWEB)

    Cairns, Elton J.; Hietbrink, Earl H.

    1981-01-01

    This section includes some historical background of the rise and fall and subsequent rebirth of the electric vehicle; and a brief discussion of current transportation needs, and environmental and energy utilization issues that resulted in the renewed interest in applying electrochemical energy conversion technology to electric vehicle applications. Although energy utilization has evolved to be the most significant and important issue, the environmental issue will be discussed first in this section only because of its chronological occurrence. The next part of the chapter is a review of passenger and commercial electric vehicle technology with emphasis on vehicle design and demonstrated performance of vehicles with candidate power sources being developed. This is followed by a discussion of electrochemical power source requirements associated with future electric vehicles that can play a role in meeting modern transportation needs. The last part of the chapter includes first a discussion of how to identify candidate electrochemical systems that might be of interest in meeting electric vehicle power source requirements. This is then followed by a review of the current technological status of these systems and a discussion of the most significant problems that must be resolved before each candidate system can be a viable power source.

  8. Electrochemical properties of vanadium pentoxide xerogel films

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yong; HU Xin-guo; LIU Yu-wen; CHENG Yu-shan

    2005-01-01

    Vanadium pentoxide xerogel(VXG) films were prepared by rapid quenching, then coin type 2016 size lithium rechargeable batteries were assembled and tested with the VXG film electrodes and lithium anodes. Electrochemical impedance spectroscopy(EIS) analysis result reveals the expected response for intercalation, except that there is almost no Warburg (diffusion) component. Analyses results of cyclic voltammetry(CV), constant discharge(CD) and discharge-charge(DC) indicate that the sample achieves a high initial discharge specific capacity of approximate 400 mA·h/g and a corresponding efficiency of 97 % in the voltage diapason of 1.5-4.0 V with a draining current of 60 mA/g. Its preservation ratio of capacity still keeps as high as 85 % even after 100 cycles. The good electrochemical performance indicates that VXG film material is a promising cathode for lithium rechargeable batteries.

  9. Rapid Electron Transport Phenomenon in the Bis(terpyridine) Metal Complex Wire: Marcus Theory and Electrochemical Impedance Spectroscopy Study.

    Science.gov (United States)

    Maeda, Hiroaki; Sakamoto, Ryota; Nishihara, Hiroshi

    2015-10-01

    The authors reported previously that bis(terpyiridne)iron(II) complex oligomer wires possess outstanding long-range intrawire electron transport ability. Here, molecular arrays of gold-electrode-bis(terpyridine)iron(II)-ferrocene are constructed by stepwise coordination as simple models of the oligomer wire system. The fast electron transfer between the terminal ferrocene and the gold electrode through the bis(terpyiridne)iron(II) complex unit is studied by potential step chronoamperometry (PSCA) and electrochemical impedance spectroscopy (EIS). Tafel plots derived from PSCA are analyzed based on Marcus theory. The plots reveal greater first-order electron transfer rate constant, weaker electronic coupling between the terminal ferrocene and the gold electrode, and smaller reorganization energy than shown by a conventional ferrocenylalkanethiol self-assembled monolayer. The electron transfer rate constants estimated by EIS agree with the PSCA results.

  10. Aftershock distribution and heterogeneous structure in and around the source area of the 2014 northern Nagano Prefecture earthquake (Mw 6.2) , central Japan, revealed by dense seismic array observation

    Science.gov (United States)

    Kurashimo, E.; Hirata, N.; Iwasaki, T.; Sakai, S.; Obara, K.; Ishiyama, T.; Sato, H.

    2015-12-01

    A shallow earthquake (Mw 6.2) occurred on November 22 in the northern Nagano Prefecture, central Japan. Aftershock area is located near the Kamishiro fault, which is a part of the Itoigawa-Shizuoka Tectonic Line (ISTL). ISTL is one of the major tectonic boundaries in Japan. Precise aftershock distribution and heterogeneous structure in and around the source region of this earthquake is important to constrain the process of earthquake occurrence. We conducted a high-density seismic array observation in and around source area to investigate aftershock distribution and crustal structure. One hundred sixty-three seismic stations, approximately 1 km apart, were deployed during the period from December 3, 2014 to December 21, 2014. Each seismograph consisted of a 4.5 Hz 3-component seismometer and a digital data recorder (GSX-3). Furthermore, the seismic data at 40 permanent stations were incorporated in our analysis. During the seismic array observation, the Japan Meteorological Agency located 977 earthquakes in a latitude range of 35.5°-37.1°N and a longitude range of 136.7°-139.0°E, from which we selected 500 local events distributed uniformly in the study area. To investigate the aftershock distribution and the crustal structure, the double-difference tomography method [Zhang and Thurber, 2003] was applied to the P- and S-wave arrival time data obtained from 500 local earthquakes. The relocated aftershock distribution shows a concentration on a plane dipping eastward in the vicinity of the mainshock hypocenter. The large slip region (asperity) estimated from InSAR analysis [GSI, 2014] corresponds to the low-activity region of the aftershocks. The depth section of Vp structure shows that the high Vp zone corresponds to the large slip region. These results suggest that structural heterogeneities in and around the fault plane may have controlled the rupture process of the 2014 northern Nagano Prefecture earthquake.

  11. Voltammetry of electrochemically heterogeneous surfaces

    OpenAIRE

    Ward, Kristopher R.; Compton, Richard G.

    2013-01-01

    In this thesis, mathematical modelling is used to theoretically investigate the electrochemical behaviour of surfaces which can be broadly classified as being ‘electrochemically heterogeneous’. Simulated voltammetry is used in the exploration of a number of specific systems as listed below.The cyclic voltammetry of electrodes composed of two different electroactive materials that differ in terms of their electrochemical rate constants towards any given redox couple. The effect of the distribu...

  12. Electrochemical process of titanium extraction

    Institute of Scientific and Technical Information of China (English)

    CH. RVS. NAGESH; C. S. RAMACHANDRAN

    2007-01-01

    A wide variety of processes are being pursued by researchers for cost effective extraction of titanium metal. Electrochemical processes are promising due to simplicity and being less capital intensive. Some of the promising electrochemical processes of titanium extraction were reviewed and the results of laboratory scale experiments on electrochemical reduction of TiO2 granules were brought out. Some of the kinetic parameters of the reduction process were discussed while presenting the quality improvements achieved in the experimentation.

  13. Electrochemical Sensors for Clinic Analysis

    Directory of Open Access Journals (Sweden)

    Guang Li

    2008-03-01

    Full Text Available Demanded by modern medical diagnosis, advances in microfabrication technology have led to the development of fast, sensitive and selective electrochemical sensors for clinic analysis. This review addresses the principles behind electrochemical sensor design and fabrication, and introduces recent progress in the application of electrochemical sensors to analysis of clinical chemicals such as blood gases, electrolytes, metabolites, DNA and antibodies, including basic and applied research. Miniaturized commercial electrochemical biosensors will form the basis of inexpensive and easy to use devices for acquiring chemical information to bring sophisticated analytical capabilities to the non-specialist and general public alike in the future.

  14. Nanotube Arrays in Porous Anodic Alumina Membranes

    Institute of Scientific and Technical Information of China (English)

    Liang LI; Naoto KOSHIZAKI; Guanghai LI

    2008-01-01

    This review summarizes the various techniques developed for fabricating nanotube arrays in porous anodic alumina membranes (AAMs). After a brief introduction to the fabrication process of AAMs, taking carbons, metals, semiconductors, organics, biomoleculars, and heterojunctions as typical examples, attention will be focused on the recently established methods to fabricate nanotubes in AAM, including electrochemical deposition, surface sol-gel, modified chemical vapor deposition, atomic layer deposition, and layer-by-layer growth. Every method is demonstrated by one or two reported results. Finally, this review is concluded with some perspectives on the research directions and focuses on the AAM-based nanotubes fields.

  15. Capsid protein oxidation in feline calicivirus using an electrochemical inactivation treatment

    Energy Technology Data Exchange (ETDEWEB)

    Shionoiri, Nozomi; Nogariya, Osamu; Tanaka, Masayoshi; Matsunaga, Tadashi; Tanaka, Tsuyoshi, E-mail: tsuyo@cc.tuat.ac.jp

    2015-02-11

    Highlights: • Feline calicivirus was inactivated electrochemically by a factor of >5 log. • The electrochemical treatment was performed at 0.9 V (vs. Ag/AgCl) for 15 min. • Electrochemical treatment caused oxidation of viral proteins. • Oxidation of viral proteins can lead to loss of viral structural integrity. - Abstract: Pathogenic viral infections are an international public health concern, and viral disinfection has received increasing attention. Electrochemical treatment has been used for treatment of water contaminated by bacteria for several decades, and although in recent years several reports have investigated viral inactivation kinetics, the mode of action of viral inactivation by electrochemical treatment remains unclear. Here, we demonstrated the inactivation of feline calicivirus (FCV), a surrogate for human noroviruses, by electrochemical treatment in a developed flow-cell equipped with a screen-printed electrode. The viral infectivity titer was reduced by over 5 orders of magnitude after 15 min of treatment at 0.9 V vs. Ag/AgCl. Proteomic study of electrochemically inactivated virus revealed oxidation of peptides located in the viral particles; oxidation was not observed in the non-treated sample. Furthermore, transmission electron microscopy revealed that viral particles in the treated sample had irregular structures. These results suggest that electrochemical treatment inactivates FCV via oxidation of peptides in the structural region, causing structural deformation of virus particles. This first report of viral protein damage through electrochemical treatment will contribute to broadening the understanding of viral inactivation mechanisms.

  16. Microfluidic cell arrays for metabolic monitoring of stimulated cardiomyocytes.

    Science.gov (United States)

    Cheng, Wei; Klauke, Norbert; Smith, Godfrey; Cooper, Jonathan M

    2010-04-01

    An array of PDMS microchambers was aligned to an array of sensor electrodes and stimulating microelectrodes, which was used for the electrochemical monitoring of the metabolic activity of single isolated adult ventricular myocytes inside the chamber array, stimulated within a transient electric field. The effect of the accumulation of metabolic byproducts in the limited extracellular volume of the picolitre chambers was demonstrated by measuring single muscle cell contraction optically, while concomitant changes in intracellular calcium transients and pH were recorded independently using fluorescent indicator dyes. Both the amplitude of the cell shortening and the magnitude of the intracellular calcium transients decreased over time and both nearly ceased after 20 min of continuous stimulation in the limited extracellullar volume. The intracellular pH decreased gradually during 20 min of continuous stimulation after which a dramatic pH drop was observed, indicating the breakdown of the intracellular buffering capacity. After continuous stimulation, intracellular lactate was released into the microchamber through cell electroporation and was detected electrochemically at a lactate microbiosensor, within the chamber. A mitochondrial uncoupler was used to mimic ischaemia and thus to enhance the cellular content of lactate. Under these circumstances, intracellular lactate concentrations were found to have risen to approximately 15 mM. This array system has the potential of simultaneous electrochemical and optical monitoring of extracellular and intracellular metabolites from single beating heart cells at a controlled metabolic state.

  17. Studies on a 120 degrees segmented circular array for multi-beam multi-frequency bathymetric application

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, B.

    size. The present study of the mutual interaction effect between the array elements reveals that the interaction effects are relatively less for a 120 degrees segmented circular array. Furthermore, the 120 degrees segmented circular array geometry...

  18. Electrochemical Science and Technology

    CERN Document Server

    Oldham, Keith; Bond, Alan

    2011-01-01

    The book addresses the scientific principles underlying electrochemistry. Starting with the basic concepts of electricity, the early chapters discuss the physics and chemistry of the materials from which electrochemical cells are constructed and the properties that make these materials appropriate as cell components. Much of the importance of electrochemistry lies in the conversion of electrical energy into chemical energy and vice versa; the thermodynamics of these processes is described, in the context of a wide range of applications of these interconversions. An electrode is a surface at wh

  19. An electrochemical generator

    Energy Technology Data Exchange (ETDEWEB)

    Ikyama, M.; Isitobi, M.

    1983-05-11

    The electrochemical generator (EKhG) has a regulation system which makes it possible with or without the load for the power source to perform with maximal effectiveness. The system contains a fuel cell (TE), a voltage stabilization circuit, load, storage devices, a mechanism for feeding the electrolyte into the fuel cell, a fuel concentration regulation circuit, a mechanism for feeding the fuel into the fuel cell, a switching circuit, which operates upon receipt of a signal about disruption of operation in the power source system and a circuit which determines the switch on of the load.

  20. Design and fabrication of nanoelectrodes for applications with scanning electrochemical microscopy

    Science.gov (United States)

    Thakar, Rahul

    Scanning electrochemical microscope (SECM) was introduced two decades ago and has since emerged as a powerful research tool to investigate localized electrochemical reactions at the surface of material and biological samples. The ability to obtain chemical information at a surface differentiates SECM from competing scanning probe microscopy (SPM) techniques. Although, chemical specificity is a unique advantage offered by SECM, inherent limitations due to a slow feedback response, and challenges associated with production of smaller electrodes have remained major drawbacks. Initially in this research, SECM was utilized as a characterization and investigative tool. Later, advances in SECM imaging were achieved with design and production of multifunctional nanoelectrodes. At first, platinum based nanoelectrodes were fabricated for use as electrochemical probes to investigate local electron transfer at chemically-modified surfaces. Further, micron and sub-micron platinum electrodes with chemically modified shrouds were prepared and characterized with voltammetric measurements. Studies reveal experimental evidence for the presence of edge-effects that are typically associated with submicron electrodes. Interestingly, we observed selectivity of these electrodes based on hydrophobic/ hydrophilic character. Through vapor deposition of parylene over microstructured material, single-pore membranes and porous membrane arrays were produced. Pore size characterization within porous membranes was performed with templated growth of micro/nanostructures. Characterization of transport properties of ions and redox-active molecules through hydrophobic parylene membranes was investigated with ion conductance microscopy and SECM, individually. Parylene is an insulative material that is chemically resistant, deposits conformally over high-aspect ratio objects and also converts into conductive carbon at high-temperature pyrolysis. Motivated by these results we identified a unique

  1. Analysis of phage Mu DNA transposition by whole-genome Escherichia coli tiling arrays reveals a complex relationship to distribution of target selection protein B, transcription and chromosome architectural elements

    Indian Academy of Sciences (India)

    Jun Ge; Zheng Lou; Hong Cui; Lei Shang; Rasika M Harshey

    2011-09-01

    Of all known transposable elements, phage Mu exhibits the highest transposition efficiency and the lowest target specificity. In vitro, MuB protein is responsible for target choice. In this work, we provide a comprehensive assessment of the genome-wide distribution of MuB and its relationship to Mu target selection using high-resolution Escherichia coli tiling DNA arrays. We have also assessed how MuB binding and Mu transposition are influenced by chromosome-organizing elements such as AT-rich DNA signatures, or the binding of the nucleoid-associated protein Fis, or processes such as transcription. The results confirm and extend previous biochemical and lower resolution in vivo data. Despite the generally random nature of Mu transposition and MuB binding, there were hot and cold insertion sites and MuB binding sites in the genome, and differences between the hottest and coldest sites were large. The new data also suggest that MuB distribution and subsequent Mu integration is responsive to DNA sequences that contribute to the structural organization of the chromosome.

  2. Pencil it in: pencil drawn electrochemical sensing platforms.

    Science.gov (United States)

    Foster, Christopher W; Brownson, Dale A C; Ruas de Souza, Ana P; Bernalte, Elena; Iniesta, Jesus; Bertotti, Mauro; Banks, Craig E

    2016-06-20

    Inspired by recent reports concerning the utilisation of hand drawn pencil macroelectrodes (PDEs), we report the fabrication, characterisation (physicochemical and electrochemical) and implementation (electrochemical sensing) of various PDEs drawn upon a flexible polyester substrate. Electrochemical characterisation reveals that there are no quantifiable electrochemical responses upon utilising these PDEs with an electroactive analyte that requires an electrochemical oxidation step first, therefore the PDEs have been examined towards the electroactive redox probes hexaammineruthenium(iii) chloride, potassium ferricyanide and ammonium iron(ii) sulfate. For the first time, characterisation of the number of drawn pencil layers and the grade of pencil are examined; these parameters are commonly overlooked when utilising PDEs. It is demonstrated that a PDE drawn ten times with a 6B pencil presented the most advantageous electrochemical platform, in terms of electrochemical reversibility and peak height/analytical signal. In consideration of the aforementioned limitation, analytes requiring an electrochemical reduction as the first process were solely analysed. We demonstrate the beneficial electroanalytical capabilities of these PDEs towards p-benzoquinone and the simultaneous detection of heavy metals, namely lead(ii) and cadmium(ii), all of which are explored for the first time utilising PDEs. Initially, the detection limits of this system were higher than desired for electroanalytical platforms, however upon implementation of the PDEs in a back-to-back configuration (in which two PDEs are placed back-to-back sharing a single connection to the potentiostat), the detection limits for lead(ii) and cadmium(ii) correspond to 10 μg L(-1) and 98 μg L(-1) respectively within model aqueous (0.1 M HCl) solutions.

  3. Characterization of ZnO Interlayers for Organic Solar Cells: Correlation of Electrochemical Properties with Thin-Film Morphology and Device Performance.

    Science.gov (United States)

    Ou, Kai-Lin; Ehamparam, Ramanan; MacDonald, Gordon; Stubhan, Tobias; Wu, Xin; Shallcross, R Clayton; Richards, Robin; Brabec, Christoph J; Saavedra, S Scott; Armstrong, Neal R

    2016-08-01

    This report focuses on the evaluation of the electrochemical properties of both solution-deposited sol-gel (sg-ZnO) and sputtered (sp-ZnO) zinc oxide thin films, intended for use as electron-collecting interlayers in organic solar cells (OPVs). In the electrochemical studies (voltammetric and impedance studies), we used indium-tin oxide (ITO) over coated with either sg-ZnO or sp-ZnO interlayers, in contact with either plain electrolyte solutions, or solutions with probe redox couples. The electroactive area of exposed ITO under the ZnO interlayer was estimated by characterizing the electrochemical response of just the oxide interlayer and the charge transfer resistance from solutions with the probe redox couples. Compared to bare ITO, the effective electroactive area of ITO under sg-ZnO films was ca. 70%, 10%, and 0.3% for 40, 80, and 120 nm sg-ZnO films. More compact sp-ZnO films required only 30 nm thicknesses to achieve an effective electroactive ITO area of ca. 0.02%. We also examined the electrochemical responses of these same ITO/ZnO heterojunctions overcoated with device thickness pure poly(3-hexylthiophehe) (P3HT), and donor/acceptor blended active layers (P3HT:PCBM). Voltammetric oxidation/reduction of pure P3HT thin films on ZnO/ITO contacts showed that pinhole pathways exist in ZnO films that permit dark oxidation (ITO hole injection into P3HT). In P3HT:PCBM active layers, however, the electrochemical activity for P3HT oxidation is greatly attenuated, suggesting PCBM enrichment near the ZnO interface, effectively blocking P3HT interaction with the ITO contact. The shunt resistance, obtained from dark current-voltage behavior in full P3HT/PCBM OPVs, was dependent on both (i) the porosity of the sg-ZnO or sp-ZnO films (as revealed by probe molecule electrochemistry) and (ii) the apparent enrichment of PCBM at ZnO/P3HT:PCBM interfaces, both effects conveniently revealed by electrochemical characterization. We anticipate that these approaches will be

  4. Radiometric stability of Phase 3 WISP arrays

    Science.gov (United States)

    Flynn, David S.; Marlow, Steven A.; Bergin, Thomas P.; Murrer, Robert Lee

    2000-07-01

    Phase 3 WISP arrays and BRITE arrays are currently being used extensively in many projection systems in many different facilities. These arrays have not been annealed at the factory, and previous tests with the arrays have revealed instabilities in the radiometric output when the arrays are driven at higher voltages. In some applications, the instabilities can be avoided by operating the arrays at lower voltages. In many KHILS applications, it is desirable to drive the arrays with the highest possible voltages to simulate hot missile targets. In one KHILS application (the KHILS VAcuum Cold Chamber, KVACC), the arrays are cooled to near cryogenic temperatures and then driven to high voltages. At lower substrate temperatures, the characteristic responses of the emitters change. Thus, it is important that the response and the stability of the radiometric output of the arrays be well understood for various substrate temperatures, and that the arrays either be annealed or operated below the voltage where the emitters begin to anneal. KHILS has investigated annealing procedures in the past, but there was concern that the annealing procedures themselves -- driving the arrays at high voltages for long times -- would damage the arrays. In order to understand the performance of the arrays better, and to reduce risks associated with driving the arrays at high voltages and operating the arrays at low substrate temperatures, a systematic measurement program was initiated. The radiometric output of new Phase 3 WISP arrays was accurately measured as a function of voltage and time. Arrays designated for testing were driven to the higher voltages and the radiometric output was measured for as long as two hours. Curves indicative of the annealing were observed, and it was determined that the maximum stable output without annealing was about 500 K (MWIR apparent temperature). Blocks of emitters were annealed and tested again. It was determined that stable output of as much as 680 K

  5. Sensor Arrays and Electronic Tongue Systems

    Directory of Open Access Journals (Sweden)

    Manel del Valle

    2012-01-01

    Full Text Available This paper describes recent work performed with electronic tongue systems utilizing electrochemical sensors. The electronic tongues concept is a new trend in sensors that uses arrays of sensors together with chemometric tools to unravel the complex information generated. Initial contributions and also the most used variant employ conventional ion selective electrodes, in which it is named potentiometric electronic tongue. The second important variant is the one that employs voltammetry for its operation. As chemometric processing tool, the use of artificial neural networks as the preferred data processing variant will be described. The use of the sensor arrays inserted in flow injection or sequential injection systems will exemplify attempts made to automate the operation of electronic tongues. Significant use of biosensors, mainly enzyme-based, to form what is already named bioelectronic tongue will be also presented. Application examples will be illustrated with selected study cases from the Sensors and Biosensors Group at the Autonomous University of Barcelona.

  6. Thermodynamics of irreversible electrochemical phenomena

    NARCIS (Netherlands)

    Groot, S.R. de; Mazur, P.; Tolhoek, H.A.

    1953-01-01

    A discussion from first principles is given of the energy and entropy laws in electrochemical systems. It is found that it is possible to clarify such controversial concepts as the form of the second law and the role of the electrochemical potential in the systems concerned.

  7. Facet-dependent electrochemical properties of Co3O4 nanocrystals toward heavy metal ions

    Science.gov (United States)

    Yu, Xin-Yao; Meng, Qiang-Qiang; Luo, Tao; Jia, Yong; Sun, Bai; Li, Qun-Xiang; Liu, Jin-Huai; Huang, Xing-Jiu

    2013-01-01

    We revealed an interesting facet-dependent electrochemical behavior toward heavy metal ions (HMIs) based on their adsorption behaviors. The (111) facet of Co3O4 nanoplates has better electrochemical sensing performance than that of the (001) facet of Co3O4 nanocubes. Adsorption measurements and density-functional theory (DFT) calculations reveals that adsorption of HMIs is responsible for the difference of electrochemical properties. Our combined experimental and theoretical studies provide a solid hint to explain the mechanism of electrochemical detection of HMIs using nanoscale metal oxides. Furthermore, this study not only suggests a promising new strategy for designing high performance electrochemical sensing interface through the selective synthesis of nanoscale materials exposed with different well-defined facets, but also provides a deep understanding for a more sensitive and selective electroanalysis at nanomaterials modified electrodes. PMID:24097175

  8. Electrochemically Programmable Plasmonic Antennas.

    Science.gov (United States)

    Dong, Shi; Zhang, Kai; Yu, Zhiping; Fan, Jonathan A

    2016-07-26

    Plasmonic antennas are building blocks in advanced nano-optical systems due to their ability to tailor optical response based on their geometry. We propose an electrochemical approach to program the optical properties of dipole antennas in a scalable, fast, and energy-efficient manner. These antennas comprise two arms, one serving as an anode and the other a cathode, separated by a solid electrolyte. As a voltage is applied between the antenna arms, a conductive filament either grows or dissolves within the electrolyte, modifying the antenna load. We probe the dynamics of stochastic filament formation and their effects on plasmonic mode programming using a combination of three-dimensional optical and electronic simulations. In particular, we identify device operation regimes in which the charge-transfer plasmon mode can be programmed to be "on" or "off." We also identify, unexpectedly, a strong correlation between DC filament resistance and charge-transfer plasmon mode frequency that is insensitive to the detailed filament morphology. We envision that the scalability of our electrochemical platform can generalize to large-area reconfigurable metamaterials and metasurfaces for on-chip and free-space applications.

  9. Research on Application of Electrochemical Immune Sensors in Food Safety Detection

    Directory of Open Access Journals (Sweden)

    Lichao Zhang

    2015-08-01

    Full Text Available Currently, research on toxic and hazardous substance in food immunological detection methods focused on conventional enzyme-linked immunosorbent assay, especially relatively few studies Array Detection of toxic foods for electrochemical immunoassay method of harmful substances. The work to build a variety of stable performance, high selectivity and sensitivity of electrochemical immunosensor and applied to the detection of Sudan, clenbuterol and chloramphenicol and other foods toxic and hazardous materials. And for the sample of the large number of food safety testing, testing and testing required to have many kinds of characteristics such as age, photo-electrochemical immune sensor array was prepared and applied to veterinary drug residues in food in a fast, high-throughput analysis.

  10. Development of inlaid electrodes for whole column electrochemical detection in HPLC.

    Science.gov (United States)

    Seo, Jung-Ho; Leow, Pei Ling; Cho, Si-Hyeong; Lim, Hyun-Woo; Kim, Jin-Young; Patel, Bhavik Anil; Park, Jin-Goo; O'Hare, Danny

    2009-08-01

    An electrochemical microfluidic device has been fabricated on PET (polyethylene terephthalate) substrate using an imprinting method. The imprinting transfers patterns from a stamp into a substrate mechanically. However, a blanket mould imprinting process has been introduced to embed the photolithographically produced gold metal electrode lines into the PET substrate resulting in an individually addressable array flush to better than 100 nm. The device formed one wall of a packed chromatography column. The array was electrochemically characterised using standard redox probes in both stagnant conditions and under flow. Both numerical modelling and experimental data show improved sensitivity under flow and a limiting current which scaled linearly with the cube root of the volume flow rate. A chromatographic separation of the bioanalytical significant neurotransmitter dopamine (DA) and its metabolite DOPAC was achieved and electrochemically detected at multiple locations within the column. The PET device was stable and robust to leaks to pressures well in excess of those required for chromatographic separations. PMID:19606303

  11. Axiom turkey genotyping array

    Science.gov (United States)

    The Axiom®Turkey Genotyping Array interrogates 643,845 probesets on the array, covering 643,845 SNPs. The array development was led by Dr. Julie Long of the USDA-ARS Beltsville Agricultural Research Center under a public-private partnership with Hendrix Genetics, Aviagen, and Affymetrix. The Turk...

  12. Biophotofuel cell anode containing self-organized titanium dioxide nanotube array

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Yong X., E-mail: yong.gan@utoledo.edu [Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606 (United States); Gan, Bo J. [Ottawa Hills High School, 2532 Evergreen Road, Toledo, OH 43606 (United States); Su Lusheng [Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606 (United States)

    2011-09-15

    Graphical abstract: Highlights: {center_dot} A photoactive anode containing highly ordered TiO{sub 2} nanotube array was made and the formation mechanism of self-organized TiO{sub 2} nanotube array on Ti was revealed. {center_dot} Effect of electrolyte concentration and voltage on the size distribution of the nanotubes was investigated. {center_dot} Self-organized TiO{sub 2} nanotube array anode possesses good photo-catalytic behavior of biomass decomposition under ultraviolet (UV) radiation. {center_dot} The fuel cell generates electricity and hydrogen via photoelectrochemical decomposition of ethanol, apple vinegar, sugar and tissue paper. - Abstract: We made a biophotofuel cell consisting of a titanium dioxide nanotube array photosensitive anode for biomass decomposition, and a low-hydrogen overpotential metal, Pt, as the cathode for hydrogen production. The titanium dioxide nanotubes (TiO{sub 2} NTs) were prepared via electrochemical oxidation of pure Ti in NaF solutions. Scanning electron microscopy was used to analyze the morphology of the nanotubes. The average diameter, wall thickness and length of the as-prepared TiO{sub 2} NTs were 88 {+-} 16 nm, 10 {+-} 2 nm and 491 {+-} 56 nm, respectively. Such dimensions are affected by the NaF concentration and the applied voltage during processing. Higher NaF concentrations result in the formation of longer and thicker nanotubes. The higher the voltage is, the thicker the nanotubes. The photosensitive anode made from the highly ordered TiO{sub 2} NTs has good photo-catalytic property, as can be seen from the test results of ethanol, apple vinegar, sugar and tissue paper decomposition under ultraviolet (UV) radiation. It is concluded that the biophotofuel cell with the TiO{sub 2} nanotube photoanode and a Pt cathode can generate electricity, hydrogen and clean water depending on the pH value and the oxygen presence in the solutions.

  13. Electrochemical Biochip for Drug Screening At Cellular Level

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yu [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Cui Huiang [Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543 (Singapore); Ye Jianshan [Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543 (Singapore); Chong Serchoong [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Lim Titmeng [Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543 (Singapore); Sheu Fwushan [Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543 (Singapore); Hui Wingcheong [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore)

    2006-04-01

    Drug screening at cellular level has becomes an attractive field of research. Different researchers have tried to record cellular response to drugs by electrical or optical approach using both invasive and non-invasive methods. Silicon-based microelectrode integrated microchips are useful tools for in situ temporal recording of neurotransmitter releasing from neural cells. A microfabricated electrochemical biochip is presented in this paper. Using dopaminergic cells grown on the chip, the dopamine excytosis can be electrochemical amperomatric detected non-invasively from drug incubated dopaminegic cells by the microelectrode integrated on chip. This silicon-based electrochemical chip has been designed with an electrode array located on the cell culture chamber bottom. Each electrode is individually electrical controlled. MN9D and PC12 dopaminergic cell lines have been demonstrated on this chip for drug effects study. This silicon-based electrochemical microchip provides a non-invasive, in situ, temporal detection of dopamine exocytosis from dopaminegic cells, and holds the potential for applications in studying the mechanisms of dopamine exocytosis and drug screening. It is also extendable for other cell culture and drug effects study.

  14. Electrochemical hydrogen Storage Systems

    International Nuclear Information System (INIS)

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not described in the

  15. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  16. Recent advancements in nanoelectrodes and nanopipettes used in combined scanning electrochemical microscopy techniques.

    Science.gov (United States)

    Kranz, Christine

    2014-01-21

    In recent years, major developments in scanning electrochemical microscopy (SECM) have significantly broadened the application range of this electroanalytical technique from high-resolution electrochemical imaging via nanoscale probes to large scale mapping using arrays of microelectrodes. A major driving force in advancing the SECM methodology is based on developing more sophisticated probes beyond conventional micro-disc electrodes usually based on noble metals or carbon microwires. This critical review focuses on the design and development of advanced electrochemical probes particularly enabling combinations of SECM with other analytical measurement techniques to provide information beyond exclusively measuring electrochemical sample properties. Consequently, this critical review will focus on recent progress and new developments towards multifunctional imaging.

  17. Multienzyme Inkjet Printed 2D Arrays.

    Science.gov (United States)

    Gdor, Efrat; Shemesh, Shay; Magdassi, Shlomo; Mandler, Daniel

    2015-08-19

    The use of printing to produce 2D arrays is well established, and should be relatively facile to adapt for the purpose of printing biomaterials; however, very few studies have been published using enzyme solutions as inks. Among the printing technologies, inkjet printing is highly suitable for printing biomaterials and specifically enzymes, as it offers many advantages. Formulation of the inkjet inks is relatively simple and can be adjusted to a variety of biomaterials, while providing nonharmful environment to the enzymes. Here we demonstrate the applicability of inkjet printing for patterning multiple enzymes in a predefined array in a very straightforward, noncontact method. Specifically, various arrays of the enzymes glucose oxidase (GOx), invertase (INV) and horseradish peroxidase (HP) were printed on aminated glass surfaces, followed by immobilization using glutardialdehyde after printing. Scanning electrochemical microscopy (SECM) was used for imaging the printed patterns and to ascertain the enzyme activity. The successful formation of 2D arrays consisting of enzymes was explored as a means of developing the first surface confined enzyme based logic gates. Principally, XOR and AND gates, each consisting of two enzymes as the Boolean operators, were assembled, and their operation was studied by SECM. PMID:26214072

  18. Solution-Liquid-Solid Synthesis of Hexagonal Nickel Selenide Nanowire Arrays with a Nonmetal Catalyst.

    Science.gov (United States)

    Xu, Kun; Ding, Hui; Jia, Kaicheng; Lu, Xiuli; Chen, Pengzuo; Zhou, Tianpei; Cheng, Han; Liu, Si; Wu, Changzheng; Xie, Yi

    2016-01-26

    Inorganic nanowire arrays hold great promise for next-generation energy storage and conversion devices. Understanding the growth mechanism of nanowire arrays is of considerable interest for expanding the range of applications. Herein, we report the solution-liquid-solid (SLS) synthesis of hexagonal nickel selenide nanowires by using a nonmetal molecular crystal (selenium) as catalyst, which successfully brings SLS into the realm of conventional low-temperature solution synthesis. As a proof-of-concept application, the NiSe nanowire array was used as a catalyst for electrochemical water oxidation. This approach offers a new possibility to design arrays of inorganic nanowires. PMID:26695560

  19. Physiomics Array: A Platform for Genome Research and Cultivation of Difficult-to-Cultivate Microorganisms Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Jay D. Keasling

    2006-07-10

    A scalable array technology for parametric control of high-throughput cell cultivations is demonstrated. The technology makes use of commercial printed circuit board (PCB) technology, integrated circuit sensors, and an electrochemical gas generation system. We present results for an array of eight 250 μl microbioreactors. Each bioreactor contains an independently addressable suite that provides closed-loop temperature control, generates feed gas electrochemically, and continuously monitors optical density. The PCB technology allows for the assembly of additional off-the-shelf components into the microbioreactor array; we demonstrate the use of a commercial ISFET chip to continuously monitor culture pH. The electrochemical dosing system provides a powerful paradigm for reproducible gas delivery to high-density arrays of microreactors. We have scaled the technology to a standard 96-well format and have constructed a system that could be easily assembled.

  20. Electrochemical reduction of NO{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Lund Traulsen, M.

    2012-04-15

    NO and NO{sub 2} (collectively referred to as NO{sub x}) are air pollutants, and the largest single contributor to NO{sub x} pollution is automotive exhaust. This study investigates electrochemical deNO{sub x}, a technology which aims to remove NO{sub x} from automotive diesel exhaust by electrochemical reduction of NO{sub x} to N{sub 2} and O{sub 2}. The focus in this study is on improving the activity and selectivity of solid oxide electrodes for electrochemical deNO{sub x} by addition of NO{sub x} storage compounds to the electrodes. Two different composite electrodes, La{sub 0.85}Sr{sub 0.15}MnO{sub 3-{delta}-}Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (LSM15-CGO10) and La{sub 0.85}Sr{sub 0.15}FeO{sub 3-{delta}-}Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95} (LSF15-CGO10), have been investigated in combination with three different NO{sub x} storage compounds: BaO, K{sub 2}O and MnO{sub x}. The main focus in the investigation has been on conversion measurements and electrochemical characterization, the latter by means of electrochemical impedance spectroscopy and cyclic voltammetry. In addition, infrared spectroscopy has been performed to study how NO{sub x} adsorption on the electrodes is affected by the presence of the aforementioned NO{sub x} storage compounds. Furthermore, non-tested and tested electrode microstructures have been thoroughly evaluated by scanning electron microscopy. The studies reveal addition of MnO{sub x} or K{sub 2}O to the electrodes cause severe degradation problems, and addition of these compounds is thus unsuitable for electrode improvement. In contrast, addition of BaO to LSM15-CGO10 electrodes is shown to have a very positive impact on the NO{sub x} conversion. The increased NO{sub x} conversion, following the BaO addition, is attributed to a combination of 1) a decreased electrode polarisation resistance and 2) an altered NO{sub x} adsorption. The NO{sub x} conversion is observed to increase strongly with polarisation, and during 9 V polarisation of an

  1. Electrochemical catalyst recovery method

    Science.gov (United States)

    Silva, Laura J.; Bray, Lane A.

    1995-01-01

    A method of recovering catalyst material from latent catalyst material solids includes: a) combining latent catalyst material solids with a liquid acid anolyte solution and a redox material which is soluble in the acid anolyte solution to form a mixture; b) electrochemically oxidizing the redox material within the mixture into a dissolved oxidant, the oxidant having a potential for oxidation which is effectively higher than that of the latent catalyst material; c) reacting the oxidant with the latent catalyst material to oxidize the latent catalyst material into at least one oxidized catalyst species which is soluble within the mixture and to reduce the oxidant back into dissolved redox material; and d) recovering catalyst material from the oxidized catalyst species of the mixture. The invention is expected to be particularly useful in recovering spent catalyst material from petroleum hydroprocessing reaction waste products having adhered sulfides, carbon, hydrocarbons, and undesired metals, and as well as in other industrial applications.

  2. Electrochemical processes in amalgams

    International Nuclear Information System (INIS)

    By the method of cyclic voltammetry it has been ascertained that in the process of anodic oxidation of liquid amalgams of s-metal (M = Li-Cs, Ca, Sr, Ba) hydrides with hydride content in mercury of 0.01-0.03 mass % in aqueous solutions of electrolytes (o.1-10 M) in the temperature range of 10-50 deg C the previously unknown electrochemical effects are observed: a wide anodic peak of current in the range of potentials from -1.65 to -1.40 V, accompanied by intensive hydrogen evolution and increase in the amalgam volume, as well as a narrow peak of current in the range of potentials of -1.0 V. The phenomena observed have been explained. 4 refs

  3. Electrochemical Hydrogen Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Lipp, Ludwig [FuelCell Energy, Inc., Torrington, CT (United States)

    2016-01-21

    Conventional compressors have not been able to meet DOE targets for hydrogen refueling stations. They suffer from high capital cost, poor reliability and pose a risk of fuel contamination from lubricant oils. This project has significantly advanced the development of solid state hydrogen compressor technology for multiple applications. The project has achieved all of its major objectives. It has demonstrated capability of Electrochemical Hydrogen Compression (EHC) technology to potentially meet the DOE targets for small compressors for refueling sites. It has quantified EHC cell performance and durability, including single stage hydrogen compression from near-atmospheric pressure to 12,800 psi and operation of EHC for more than 22,000 hours. Capital cost of EHC was reduced by 60%, enabling a path to meeting the DOE cost targets for hydrogen compression, storage and delivery ($2.00-2.15/gge by 2020).

  4. Electrochemical synthesis of alkali-intercalated iron selenide superconductors

    Institute of Scientific and Technical Information of China (English)

    申士杰; 应天平; 王刚; 金士锋; 张韩; 林志萍; 陈小龙

    2015-01-01

    Electrochemical method has been used to insert K/Na into FeSe lattice to prepare alkali-intercalated iron selenides at room temperature. Magnetization measurement reveals that KxFe2Se2 and NaxFe2Se2 are superconductive at 31 K and 46 K, respectively. This is the first successful report of obtaining metal-intercalated FeSe-based high-temperature superconductors using electrochemical method. It provides an effective route to synthesize metal-intercalated layered compounds for new superconductor exploration.

  5. Electrochemical behaviors of silicon wafers in silica slurry

    Institute of Scientific and Technical Information of China (English)

    Xiaolan Song; Haiping Yang; Xunda Shi; Xi He; Guanzhou Qiu

    2008-01-01

    The electrochemical behaviors of n-type silicon wafers in silica-based slurry were investigated, and the influences of the pH value and solid content of the slurry on the corrosion of silicon wafers were studied by using electrochemical DC polarization and AC impedance techniques. The results revealed that these factors affected the corrosion behaviors of silicon wafers to different degrees and had their suitable parameters that made the maximum corrosion rate of the wafers. The corrosion potential of (100) surface was lower than that of (111), whereas the current density of (100) was much higher than that of (111).

  6. Electrochemical structure-switching sensing using nanoplasmonic devices

    Energy Technology Data Exchange (ETDEWEB)

    Patskovsky, Sergiy; Dallaire, Anne-Marie; Blanchard-Dionne, Andre-Pierre; Meunier, Michel [Department of Engineering Physics, Laser Processing and Plasmonics Laboratory, Polytechnique, Montreal, Station Centre-ville, QC (Canada); Vallee-Belisle, Alexis [Laboratory of Biosensors and Nanomachines, Departement de Chimie, Universite de Montreal, QC (Canada)

    2015-12-15

    In this article, the implementation of electrochemical plasmonic nanostructures functionalized with DNA-based structure-switching sensors is presented. eNanoSPR devices with open and microfluidic measurement cells are developed on the base of nanohole arrays in 100 nm gold film and applied for combined microscopic and electrochemical surface plasmon (eSPR) visualization. eSPR voltammograms and spectroscopy are performed using planar three electrode schematic with plasmonic nanostructure operated as working electrode. Limit of detection of eNanoSPR devices for oligonucleotide hybridization is estimated in the low nanomolar and applications for structure-switching electro-plasmonic sensing in complex liquids are discussed. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Direct electrochemical oxidation of polyacrylates.

    Science.gov (United States)

    Bellagamba, Riccardo; Comninellis, Christos; Vatistas, Nicolaos

    2002-10-01

    A promising elimination treatment of non-biodegradable organic pollutants is the direct electro-oxidation. In this work has been proposed the electrochemical elimination of polyacrylates by using boron-doped diamond (BDD) as anodic material. The complete elimination of organic contaminants has been obtained and this is the first case of successful electrochemical treatment of polymeric and bio-refractory species. The tests of the electrochemical oxidation have been conducted at constant current conditions and a complete elimination of organic species has been reached. The decrease of the COD value with time follows the behaviour of an ideal anode as in the case of low molecular organic compounds. PMID:12489259

  8. Engineered peptide-based nanobiomaterials for electrochemical cell chip

    Science.gov (United States)

    Kafi, Md. Abdul; Cho, Hyeon-Yeol; Choi, Jeong-Woo

    2016-07-01

    Biomaterials having cell adhesion ability are considered to be integral part of a cell chip. A number of researches have been carried out to search for a suitable material for effective immobilization of cell on substrate. Engineered ECM materials or their components like collagen, Poly- l-Lysine (PLL), Arg-Gly-Asp (RGD) peptide have been extensively used for mammalian cell adhesion and proliferation with the aim of tissue regeneration or cell based sensing application. This review focuses on the various approaches for two- and three-dimensionally patterned nanostructures of a short peptide i.e. RGD peptide on chip surfaces together with their effects on cell behaviors and electrochemical measurements. Most of the study concluded with positive remarks on the well-oriented engineered RGD peptide over their homogenous thin film. The engineered RGD peptide not only influences cell adhesion, spreading and proliferation but also their periodic nano-arrays directly influence electrochemical measurements of the chips. The electrochemical signals found to be enhanced when RGD peptides were used in well-defined two-dimensional nano-arrays. The topographic alteration of three-dimensional structure of engineered RGD peptide was reported to be suitably contacted with the integrin receptors of cellular membrane which results indicated the enhanced cell-electrode adhesion and efficient electron exchange phenomenon. This enhanced electrochemical signal increases the sensitivity of the chip against the target analytes. Therefore, development of engineered cellular recognizable peptides and its 3D topological design for fabrication of cell chip will provide the synergetic effect on bio-affinity, sensitivity and accuracy for the in situ real-time monitoring of analytes.

  9. Vertically aligned TiO2 nanotube array for high rate Li-based micro-battery anodes with improved durability

    International Nuclear Information System (INIS)

    Highlights: • TiO2 nanotubes (NTs) are grown onto a Ti foil by ultra-fast anodic oxidation. • NTs exhibit noticeable stability and capacity retention after prolonged cycling. • NTs show improved durability (>1100 cycles) at a very high C-rate. • Short diffusion path and fast kinetics are responsible for superior performance. • TiO2 NTs are interesting candidate for next generation micro Li-based cells. -- Abstract: Vertically oriented arrays of TiO2 nanotubes (NTs) are fabricated by fast and facile, thus easily up-scalable, anodic oxidation of a titanium foil followed by rapid thermal annealing. The structural/morphological characterization shows the formation of well defined one-dimensional nanotube carpets, while the X-ray diffraction analysis reveals the pure anatase crystalline structure of the thermal treated samples. The electrochemical response in laboratory-scale lithium cells is highly satisfying: at a very high discharge/charge rate of 12C, the NTs can perform with good stability and capacity retention after long-term cycling along with improved durability (>1100 cycles). High surface area, self-induced doping, short diffusion path and fast kinetics of the unidirectionally aligned TiO2 nanotube arrays are intriguing prospects which can be considered responsible for the noticeable electrochemical performance obtained in the absence of foreign ingredients such as binders and conductive agents, which would affect the overall energy density

  10. Towards an integrated biosensor array for simultaneous and rapid multi-analysis of endocrine disrupting chemicals

    International Nuclear Information System (INIS)

    Highlights: ► A multitask biosensor for the detection of endocrine disrupting chemicals is proposed. ► The sensing system employ an array of biological recognition elements. ► Amperometric and optical transduction methods are provided in an integrated biosensor together with flow control systems. ► The biosensing device results in an integrated, automatic and portable system for environmental and agrifood application. - Abstract: In this paper we propose the construction and application of a portable multi-purpose biosensor array for the simultaneous detection of a wide range of endocrine disruptor chemicals (EDCs), based on the recognition operated by various enzymes and microorganisms. The developed biosensor combines both electrochemical and optical transduction systems, in order to increase the number of chemical species which can be monitored. Considering to the maximum residue level (MRL) of contaminants established by the European Commission, the biosensor system was able to detect most of the chemicals analysed with very high sensitivity. In particular, atrazine and diuron were detected with a limit of detection of 0.5 nM, with an RSD% less than 5%; paraoxon and chlorpyrifos were revealed with a detection of 5 μM and 4.5 μM, respectively, with an RSD% less than 6%; catechol and bisphenol A were identified with a limit of detection of 1 μM and 35 μM respectively, with an RSD% less than 5%.

  11. Towards an integrated biosensor array for simultaneous and rapid multi-analysis of endocrine disrupting chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Scognamiglio, Viviana, E-mail: viviana.scognamiglio@mlib.ic.cnr.it [IC-CNR Istituto di Cristallografia, AdR1 Dipartimento Agroalimentare - Via Salaria Km 29.3 00015, Rome (Italy); Pezzotti, Italo; Pezzotti, Gianni; Cano, Juan; Manfredonia, Ivano [Biosensor S.r.l. - Via degli Olmetti 44 00060 Formello, Rome (Italy); Buonasera, Katia [IC-CNR Istituto di Cristallografia, AdR1 Dipartimento Agroalimentare - Via Salaria Km 29.3 00015, Rome (Italy); Arduini, Fabiana; Moscone, Danila; Palleschi, Giuseppe [Universita di Roma Tor Vergata, Dipartimento di Scienze e Tecnologie Chimiche - Via della Ricerca Scientifica 00133, Rome (Italy); Giardi, Maria Teresa [IC-CNR Istituto di Cristallografia, AdR1 Dipartimento Agroalimentare - Via Salaria Km 29.3 00015, Rome (Italy)

    2012-11-02

    Highlights: Black-Right-Pointing-Pointer A multitask biosensor for the detection of endocrine disrupting chemicals is proposed. Black-Right-Pointing-Pointer The sensing system employ an array of biological recognition elements. Black-Right-Pointing-Pointer Amperometric and optical transduction methods are provided in an integrated biosensor together with flow control systems. Black-Right-Pointing-Pointer The biosensing device results in an integrated, automatic and portable system for environmental and agrifood application. - Abstract: In this paper we propose the construction and application of a portable multi-purpose biosensor array for the simultaneous detection of a wide range of endocrine disruptor chemicals (EDCs), based on the recognition operated by various enzymes and microorganisms. The developed biosensor combines both electrochemical and optical transduction systems, in order to increase the number of chemical species which can be monitored. Considering to the maximum residue level (MRL) of contaminants established by the European Commission, the biosensor system was able to detect most of the chemicals analysed with very high sensitivity. In particular, atrazine and diuron were detected with a limit of detection of 0.5 nM, with an RSD% less than 5%; paraoxon and chlorpyrifos were revealed with a detection of 5 {mu}M and 4.5 {mu}M, respectively, with an RSD% less than 6%; catechol and bisphenol A were identified with a limit of detection of 1 {mu}M and 35 {mu}M respectively, with an RSD% less than 5%.

  12. Influence of graphene microstructures on electrochemical performance for supercapacitors

    Directory of Open Access Journals (Sweden)

    Youning Gong

    2015-10-01

    Full Text Available The influence of variant graphenes on electrochemical performance for supercapacitors was studied comparatively and systematically by using SEM, FTIR and Raman spectroscopy, cyclic voltammetry (CV, galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS. The results revealed that: 1 the nitrogen-doped graphene (N-G electrode exhibited the highest specific capacitance at the same voltage scan rate; 2 the specific capacitance of the N-G reached up to 243.5 F/g at 1 A/g, while regular graphite oxide (GO was 43.5 F/g and reduced graphene oxide (rGO was 67.9 F/g; 3 N-G exhibited the best supercapacitance performance and the superior electrochemical properties, which made it an ideal electrode material for supercapacitors.

  13. Effect of polyethylene glycol on electrochemically deposited trivalent chromium layers

    Institute of Scientific and Technical Information of China (English)

    Joo-Yul LEE; Man KIM; Sik-Chol KWON

    2009-01-01

    The structural characteristics of the trivalent chromium deposits and their interfacial behavior in the plating solution with and without polyethylene glycol molecules were observed by using various electrochemical methods such as cyclic voltammetry, open circuit potential transition, electrochemical impedance spectroscopy, scanning electron microscopy and X-ray photoelectron spectrometry. It is shown that the polyethylene glycol molecules make the reductive current density lower in the trivalent chromium plating system and promote a hydrogen evolution reaction through their adsorption on the electrode surface. And the trivalent chromium layer formed from the polyethylene glycol-containing solution has somewhat higher density of cracks on its surface and results in a lower film resistance, lower polarization resistance, and higher capacitance in a corrosive atmosphere. It is also revealed that the formation of chromium carbide layer is facilitated in the presence of polyethylene glycol, which means easier electrochemical codeposition of chromium and carbon, not single chromium deposition.

  14. Biomedical Perspective of Electrochemical Nanobiosensor

    Institute of Scientific and Technical Information of China (English)

    Priti Singh; Shailendra Kumar Pandey; Jyoti Singh; Sameer Srivastava; Sadhana Sachan; Sunil Kumar Singh

    2016-01-01

    Electrochemical biosensor holds great promise in the biomedical area due to its enhanced specificity, sensi-tivity, label-free nature and cost effectiveness for rapid point-of-care detection of diseases at bedside. In this review, we are focusing on the working principle of electrochemical biosensor and how it can be employed in detecting biomarkers of fatal diseases like cancer, AIDS, hepatitis and cardiovascular diseases. Recent advances in the development of implantable biosensors and exploration of nanomaterials in fabrication of electrodes with increasing the sensitivity of biosensor for quick and easy detection of biomolecules have been elucidated in detail. Electrochemical-based detection of heavy metal ions which cause harmful effect on human health has been discussed. Key challenges associated with the electrochemical sensor and its future perspectives are also addressed.

  15. Electrochemical biofilm control: A review

    Science.gov (United States)

    Sultana, Sujala T; Babauta, Jerome T; Beyenal, Haluk

    2015-01-01

    One of the methods of controlling biofilms that has widely been discussed in the literature is to apply a potential or electrical current to a metal surface on which the biofilm is growing. Although electrochemical biofilm control has been studied for decades, the literature is often conflicting, as is detailed in this review. The goals of this review are to (1) present the current status of knowledge regarding electrochemical biofilm control, (2) establish a basis for a fundamental definition of electrochemical biofilm control and requirements for studying it, (3) discuss current proposed mechanisms, and (4) introduce future directions in the field. It is expected that the review will provide researchers with guidelines on comparing data sets across the literature and generating comparable data sets. The authors believe that, with the correct design, electrochemical biofilm control has great potential for industrial use. PMID:26592420

  16. Electrochemical biofilm control: a review.

    Science.gov (United States)

    Sultana, Sujala T; Babauta, Jerome T; Beyenal, Haluk

    2015-01-01

    One of the methods of controlling biofilms that has widely been discussed in the literature is to apply a potential or electrical current to a metal surface on which the biofilm is growing. Although electrochemical biofilm control has been studied for decades, the literature is often conflicting, as is detailed in this review. The goals of this review are: (1) to present the current status of knowledge regarding electrochemical biofilm control; (2) to establish a basis for a fundamental definition of electrochemical biofilm control and requirements for studying it; (3) to discuss current proposed mechanisms; and (4) to introduce future directions in the field. It is expected that the review will provide researchers with guidelines on comparing datasets across the literature and generating comparable datasets. The authors believe that, with the correct design, electrochemical biofilm control has great potential for industrial use.

  17. Electrochemical Oscillations Induced by Surfactants

    Institute of Scientific and Technical Information of China (English)

    翟俊红; 贺占博

    2003-01-01

    A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO4 aqueous and an aluminum rod in Al(NO3)3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg2SO4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.

  18. A Parylene Bellows Electrochemical Actuator

    OpenAIRE

    Li, Po-Ying; Sheybani, Roya; Gutierrez, Christian A.; Kuo, Jonathan T. W.; Meng, Ellis

    2010-01-01

    We present the first electrochemical actuator with Parylene bellows for large-deflection operation. The bellows diaphragm was fabricated using a polyethylene-glycol-based sacrificial molding technique followed by coating in Parylene C. Bellows were mechanically characterized and integrated with a pair of interdigitated electrodes to form an electrochemical actuator that is suitable for low-power pumping of fluids. Pump performance (gas generation rate and pump efficiency) was optimized throug...

  19. Electrochemical reactions and ionization processes

    OpenAIRE

    Girault, Hubert; Liu, Baohong; Qiao, Liang; Bi, Hongyan; Prudent, Michel; Lion, Niels; Abonnenc, Mélanie

    2010-01-01

    Electrochemical or photo-electrochemical reactions in both electrospray ionization and laser desorption ionization are discussed stressing the role of the electrode reaction in influencing the ionization process. In particular, upon application of a high voltage during electrospray ionization, the emitter includes a working electrode, where redox reactions are observed, such as electro-generation of benzoquinone and metal ions. In contrast, the target plate in laser-induced desorption ionizat...

  20. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  1. Pacific Array (Transportable Broadband Ocean Floor Array)

    Science.gov (United States)

    Kawakatsu, Hitoshi; Ekstrom, Goran; Evans, Rob; Forsyth, Don; Gaherty, Jim; Kennett, Brian; Montagner, Jean-Paul; Utada, Hisashi

    2016-04-01

    Based on recent developments on broadband ocean bottom seismometry, we propose a next generation large-scale array experiment in the ocean. Recent advances in ocean bottom broadband seismometry1, together with advances in the seismic analysis methodology, have enabled us to resolve the regional 1-D structure of the entire lithosphere/asthenosphere system, including seismic anisotropy (azimuthal, and hopefully radial), with deployments of ~15 broadband ocean bottom seismometers (BBOBSs). Having ~15 BBOBSs as an array unit for a 2-year deployment, and repeating such deployments in a leap-frog way or concurrently (an array of arrays) for a decade or so would enable us to cover a large portion of the Pacific basin. Such efforts, not only by giving regional constraints on the 1-D structure beneath Pacific ocean, but also by sharing waveform data for global scale waveform tomography, would drastically increase our knowledge of how plate tectonics works on this planet, as well as how it worked for the past 150 million years. International collaborations is essential: if three countries/institutions participate this endeavor together, Pacific Array may be accomplished within five-or-so years.

  2. Electrochemical hydrogen Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Digby Macdonald

    2010-08-09

    As the global need for energy increases, scientists and engineers have found a possible solution by using hydrogen to power our world. Although hydrogen can be combusted as a fuel, it is considered an energy carrier for use in fuel cells wherein it is consumed (oxidized) without the production of greenhouse gases and produces electrical energy with high efficiency. Chemical storage of hydrogen involves release of hydrogen in a controlled manner from materials in which the hydrogen is covalently bound. Sodium borohydride and aminoborane are two materials given consideration as chemical hydrogen storage materials by the US Department of Energy. A very significant barrier to adoption of these materials as hydrogen carriers is their regeneration from 'spent fuel,' i.e., the material remaining after discharge of hydrogen. The U.S. Department of Energy (DOE) formed a Center of Excellence for Chemical Hydrogen Storage, and this work stems from that project. The DOE has identified boron hydrides as being the main compounds of interest as hydrogen storage materials. The various boron hydrides are then oxidized to release their hydrogen, thereby forming a 'spent fuel' in the form of a lower boron hydride or even a boron oxide. The ultimate goal of this project is to take the oxidized boron hydrides as the spent fuel and hydrogenate them back to their original form so they can be used again as a fuel. Thus this research is essentially a boron hydride recycling project. In this report, research directed at regeneration of sodium borohydride and aminoborane is described. For sodium borohydride, electrochemical reduction of boric acid and sodium metaborate (representing spent fuel) in alkaline, aqueous solution has been investigated. Similarly to literature reports (primarily patents), a variety of cathode materials were tried in these experiments. Additionally, approaches directed at overcoming electrostatic repulsion of borate anion from the cathode, not

  3. Telescope Array Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, H.; Yoshida, S. [Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522 (Japan); Yoshii, H. [Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577 (Japan); Tanaka, K. [Hiroshinma City University, 3-4-1 Ozuka-Higashi, Asa-Minami-ku, Hiroshima, 731-3194 (Japan); Cohen, F.; Fukushima, M.; Hayashida, N.; Hiyama, K.; Ikeda, D.; Kido, E.; Kondo, Y.; Nonaka, T.; Ohnishi, M.; Ohoka, H.; Ozawa, S.; Sagawa, H.; Sakurai, N.; Shibata, T.; Shimodaira, H.; Takeda, M. [ICRR, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8582 (Japan)] (and others)

    2008-01-15

    The TA observatory is a hybrid detector system consisting of both a surface detector array as well as a set of fluorescence detectors. The observatory will measure the energy spectrum, anisotropy and composition of ultra-high energy cosmic rays. The surface detectors are being deployed and the array should be complete by the end of February, 2007. We will soon be collecting hybrid data at the Telecope Array.

  4. Integrated avalanche photodiode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, Eric S.

    2015-07-07

    The present disclosure includes devices for detecting photons, including avalanche photon detectors, arrays of such detectors, and circuits including such arrays. In some aspects, the detectors and arrays include a virtual beveled edge mesa structure surrounded by resistive material damaged by ion implantation and having side wall profiles that taper inwardly towards the top of the mesa structures, or towards the direction from which the ion implantation occurred. Other aspects are directed to masking and multiple implantation and/or annealing steps. Furthermore, methods for fabricating and using such devices, circuits and arrays are disclosed.

  5. Electrochemical characterization of electrochemically reduced graphene coatings on platinum. Electrochemical study of dye adsorption

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted - Highlights: • Pt electrodes coated with reduced graphene oxide (RGO) were obtained by CV. • CV and EIS showed the increase in capacitance due to RGO deposition. • Redox mediator influences the electrochemical response observed by SECM. • CV was used to monitor and induce dye adsorption on Pt/RGO electrodes. • Electrochemical adsorption increased dye adsorption compared to ocp adsorption. - Abstract: Reduced graphene oxide coatings were synthesized by cyclic voltammetry on Pt electrodes. Electrochemically reduced graphene oxide was analyzed by scanning electrochemical microscopy for the first time. The redox mediator influences the electrochemical response; thus Ru(NH3)63+ and Fe(CN)63− gave a similar response and Fe3+ gave the poorest response. Pt electrodes coated with reduced graphene oxide were also used in the electrochemical adsorption (performed by cyclic voltammetry) of different dyes (Methylene Blue, Procion MX-2R and Amaranth). Electrochemical methods proved to be useful to monitor the adsorption of dyes on the surface of graphene materials. After adsorption, with Methylene Blue and Procion MX-2R, the appearance of a stable redox pair (with 1 electron transfer) was observed. This redox pair was adsorption controlled since the intensity of the redox pair was proportional to the scan rate used. Electrochemical adsorption multiplied by 3 the electrical charge of the Methylene Blue adsorbed on the surface of reduced graphene oxide when compared with simple adsorption at open circuit potential. In the case of Procion MX-2R, the increase obtained was even higher, with a 6-fold increase

  6. Fabrication and characterization of CaP-coated nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Kuan-Chen; Chen, Jia-Ling [Institute of Oral Medicine, National Cheng Kung University, Tainan 701, Taiwan (China); Liu, Yen-Ting [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Lee, Tzer-Min, E-mail: tmlee@mail.ncku.edu.tw [Institute of Oral Medicine, National Cheng Kung University, Tainan 701, Taiwan (China); Medical Device Innovation Center, National Cheng Kung University, Tainan 701, Taiwan (China); School of Dentistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)

    2015-03-01

    Modified anodization techniques have been shown to improve the biocompatibility of titanium. This study demonstrated the anodic formation of self-organized nanotube arrays on titanium from an electrolyte solution containing 1 M H{sub 3}PO{sub 4} and 1 wt% hydrofluoric acid (HF). Our aim was to investigate the effects of sputter-deposited CaP on nanotube arrays. SEM images revealed a surface with uniform morphology and an average pore diameter of 29 nm. XRD results indicated that the phase of the nanotube arrays was amorphous. Electron spectroscopy for chemical analysis (ESCA) confirmed that the nanotube arrays were coated with calcium and phosphorus. Cell culture experiments using human osteosarcoma (HOS) cells demonstrated that the CaP/nanotube arrays had a pronounced effect on initial cell attachment as well as on the number of cells at 1, 7, and 14 days. Compared to as-polished titanium, the CaP/nanotube arrays accelerated cell proliferation, attachment, and spreading. Our results demonstrate the pronounced effects of CaP/nanotube arrays on the biological responses of HOS cells. - Highlights: • Self-organized nanotube arrays were anodically formed on titanium. • Surfaces of nanotube arrays exhibited uniform morphology and pore size. • According to ESCA results, Ca and P were successfully coated on nanotube arrays. • CaP/nanotube arrays accelerated the attachment and spreading of cells. • CaP/nanotube arrays were shown to affect biological responses of cells.

  7. Solar-Electrochemical Power System for a Mars Mission

    Science.gov (United States)

    Withrow, Colleen A.; Morales, Nelson

    1994-01-01

    This report documents a sizing study of a variety of solar electrochemical power systems for the intercenter NASA study known as 'Mars Exploration Reference Mission'. Power systems are characterized for a variety of rovers, habitation modules, and space transport vehicles based on requirements derived from the reference mission. The mission features a six-person crew living on Mars for 500 days. Mission power requirements range from 4 kWe to 120 kWe. Primary hydrogen and oxygen fuel cells, regenerative hydrogen and oxygen fuel cells, sodium sulfur batteries advanced photovoltaic solar arrays of gallium arsenide on germanium with tracking and nontracking mechanisms, and tent solar arrays of gallium arsenide on germanium are evaluated and compared.

  8. Development and characterization of electrochemical cantilever sensor for bio/chemical sensing applications

    DEFF Research Database (Denmark)

    Quan, Xueling; Fischer, Lee MacKenzie; Boisen, Anja;

    2011-01-01

    We report the improvements made to our previously developed electrochemical cantilever (EC) sensor, where nanoporous gold material is employed as working electrodes in microcantilever arrays, while combined counter-reference electrodes are integrated on the chip. For a surface stress change of 1m......N/m induced on the microcantilever, the cantilever deflects is 7.3 nm at the free end, indicating high sensitivity to surface stress changes. The results suggest that the performance of the electrochemical cell is stable. A much enhanced sensitivity in surface chemistry-driven actuation can be achieved...

  9. Solar array deployment mechanism

    Science.gov (United States)

    Calassa, Mark C.; Kackley, Russell

    1995-05-01

    This paper describes a Solar Array Deployment Mechanism (SADM) used to deploy a rigid solar array panel on a commercial spacecraft. The application required a deployment mechanism design that was not only lightweight, but also could be produced and installed at the lowest possible cost. This paper covers design, test, and analysis of a mechanism that meets these requirements.

  10. Experimental study on the cooling performance of high power LED arrays under natural convection

    International Nuclear Information System (INIS)

    This paper presents on the cooling performance of high power light emitting diode (LED) arrays under natural convection condition. A series of experiments with different type of LED array arrangements with a commercial heat sink were performed to evaluate their thermal performance. An analytical thermal resistance model was used to calculate thermal resistance. The results reveal that thermal resistance and junction temperature are affected by the type of array. The triangular array of the high power LED revealed the highest heat transfer coefficient with 3.86% compared to the most common square array. It indicates that array arrangement of the LED significantly affect on the excellent performance

  11. Micromachined electrode array

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat (Edgewood, NM); Wessendorf, Kurt O. (Albuquerque, NM)

    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.

  12. Microfabricated ion trap array

    Science.gov (United States)

    Blain, Matthew G.; Fleming, James G.

    2006-12-26

    A microfabricated ion trap array, comprising a plurality of ion traps having an inner radius of order one micron, can be fabricated using surface micromachining techniques and materials known to the integrated circuits manufacturing and microelectromechanical systems industries. Micromachining methods enable batch fabrication, reduced manufacturing costs, dimensional and positional precision, and monolithic integration of massive arrays of ion traps with microscale ion generation and detection devices. Massive arraying enables the microscale ion traps to retain the resolution, sensitivity, and mass range advantages necessary for high chemical selectivity. The reduced electrode voltage enables integration of the microfabricated ion trap array with on-chip circuit-based rf operation and detection electronics (i.e., cell phone electronics). Therefore, the full performance advantages of the microfabricated ion trap array can be realized in truly field portable, handheld microanalysis systems.

  13. Physicochemical characteristics and droplet impact dynamics of superhydrophobic carbon nanotube arrays.

    Science.gov (United States)

    Aria, Adrianus I; Gharib, Morteza

    2014-06-17

    The physicochemical and droplet impact dynamics of superhydrophobic carbon nanotube arrays are investigated. These superhydrophobic arrays are fabricated simply by exposing the as-grown carbon nanotube arrays to a vacuum annealing treatment at a moderate temperature. This treatment, which allows a significant removal of oxygen adsorbates, leads to a dramatic change in wettability of the arrays, from mildly hydrophobic to superhydrophobic. Such change in wettability is also accompanied by a substantial change in surface charge and electrochemical properties. Here, the droplet impact dynamics are characterized in terms of critical Weber number, coefficient of restitution, spreading factor, and contact time. Based on these characteristics, it is found that superhydrophobic carbon nanotube arrays are among the best water-repellent surfaces ever reported. The results presented herein may pave a way for the utilization of superhydrophobic carbon nanotube arrays in numerous industrial and practical applications, including inkjet printing, direct injection engines, steam turbines, and microelectronic fabrication. PMID:24866696

  14. Electrochemical Hydrogen Peroxide Generator

    Science.gov (United States)

    Tennakoon, Charles L. K.; Singh, Waheguru; Anderson, Kelvin C.

    2010-01-01

    Two-electron reduction of oxygen to produce hydrogen peroxide is a much researched topic. Most of the work has been done in the production of hydrogen peroxide in basic media, in order to address the needs of the pulp and paper industry. However, peroxides under alkaline conditions show poor stabilities and are not useful in disinfection applications. There is a need to design electrocatalysts that are stable and provide good current and energy efficiencies to produce hydrogen peroxide under acidic conditions. The innovation focuses on the in situ generation of hydrogen peroxide using an electrochemical cell having a gas diffusion electrode as the cathode (electrode connected to the negative pole of the power supply) and a platinized titanium anode. The cathode and anode compartments are separated by a readily available cation-exchange membrane (Nafion 117). The anode compartment is fed with deionized water. Generation of oxygen is the anode reaction. Protons from the anode compartment are transferred across the cation-exchange membrane to the cathode compartment by electrostatic attraction towards the negatively charged electrode. The cathode compartment is fed with oxygen. Here, hydrogen peroxide is generated by the reduction of oxygen. Water may also be generated in the cathode. A small amount of water is also transported across the membrane along with hydrated protons transported across the membrane. Generally, each proton is hydrated with 3-5 molecules. The process is unique because hydrogen peroxide is formed as a high-purity aqueous solution. Since there are no hazardous chemicals or liquids used in the process, the disinfection product can be applied directly to water, before entering a water filtration unit to disinfect the incoming water and to prevent the build up of heterotrophic bacteria, for example, in carbon based filters. The competitive advantages of this process are: 1. No consumable chemicals are needed in the process. The only raw materials

  15. Electrochemical oxidation of organic waste

    International Nuclear Information System (INIS)

    Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids

  16. Mathematics revealed

    CERN Document Server

    Berman, Elizabeth

    1979-01-01

    Mathematics Revealed focuses on the principles, processes, operations, and exercises in mathematics.The book first offers information on whole numbers, fractions, and decimals and percents. Discussions focus on measuring length, percent, decimals, numbers as products, addition and subtraction of fractions, mixed numbers and ratios, division of fractions, addition, subtraction, multiplication, and division. The text then examines positive and negative numbers and powers and computation. Topics include division and averages, multiplication, ratios, and measurements, scientific notation and estim

  17. Revealed Attention

    OpenAIRE

    Masatlioglu, Yusufcan; NAKAJIMA, Daisuke; Ozbay, Erkut Y

    2012-01-01

    The standard revealed preference argument relies on an implicit assumption that a decision maker considers all feasible alternatives. The marketing and psychology literatures, however, provide wellestablished evidence that consumers do not consider all brands in a given market before making a purchase (Limited Attention). In this paper, we illustrate how one can deduce both the decision maker's preference and the alternatives to which she pays attention and inattention from the observed behav...

  18. Revealed Attention

    OpenAIRE

    Yusufcan Masatlioglu; Daisuke Nakajima; Ozbay, Erkut Y

    2012-01-01

    The standard revealed preference argument relies on an implicit assumption that a decision maker considers all feasible alternatives. The marketing and psychology literatures, however, provide well-established evidence that consumers do not consider all brands in a given market before making a purchase (Limited Attention). In this paper, we illustrate how one can deduce both the decision maker's preference and the alternatives to which she pays attention and inattention from the observed beha...

  19. Prussian Blue-coated interdigitated array electrodes for possible analytical application

    NARCIS (Netherlands)

    Hartmann, M.; Grabner, E.W.; Bergveld, P.

    1991-01-01

    Thin films of iron(III) hexacyanoferrate(II) (Prussian Blue) were electrochemically deposited on interdigitated array (IDA) electrodes, yielding systems which can be considered as chemiresistors in sensing alkali metal ion concentrations in an adjacent electrolyte. This is due to the fact that the c

  20. Tracking of electrochemical impedance of batteries

    Science.gov (United States)

    Piret, H.; Granjon, P.; Guillet, N.; Cattin, V.

    2016-04-01

    This paper presents an evolutionary battery impedance estimation method, which can be easily embedded in vehicles or nomad devices. The proposed method not only allows an accurate frequency impedance estimation, but also a tracking of its temporal evolution contrary to classical electrochemical impedance spectroscopy methods. Taking into account constraints of cost and complexity, we propose to use the existing electronics of current control to perform a frequency evolutionary estimation of the electrochemical impedance. The developed method uses a simple wideband input signal, and relies on a recursive local average of Fourier transforms. The averaging is controlled by a single parameter, managing a trade-off between tracking and estimation performance. This normalized parameter allows to correctly adapt the behavior of the proposed estimator to the variations of the impedance. The advantage of the proposed method is twofold: the method is easy to embed into a simple electronic circuit, and the battery impedance estimator is evolutionary. The ability of the method to monitor the impedance over time is demonstrated on a simulator, and on a real Lithium ion battery, on which a repeatability study is carried out. The experiments reveal good tracking results, and estimation performance as accurate as the usual laboratory approaches.

  1. Plasma Activation of Integrated Carbon Nanotube Electrodes for Electrochemical Detection of Catechol

    Institute of Scientific and Technical Information of China (English)

    WANG Shenggao; WANG Tao; LI Yanqiong; ZHAO Xiujian; HAN Jianjun; WANG Jianhua

    2007-01-01

    In this study,integrated multi-wall carbon nanotube (MWCNT) electrodes were prepared in the holes of glass directly by microwave plasma chemical vapour deposition (MWPCVD).The electrochemical behaviour of catechol at the integrated MWCNT electrodes was investigated.The oxygen plasma treated CNT electrodes had better electrochemical performance for the analysis of catechol than that of as-synthesized CNT electrodes.Both the as-synthesized CNTs and plasma treated CNTs were characterized by TEM(transmission electron microscopy,XPS(X-ray photoelectron spectroscopy) and Raman spectroscopy.The results revealed that the oxygen plasma activation is an effective method to enhance the electrochemical properties of CNT electrodes.

  2. Tunable nanogap devices for ultra-sensitive electrochemical impedance biosensing.

    Science.gov (United States)

    Lu, Yong; Guo, Zheng; Song, Jing-Jing; Huang, Qin-An; Zhu, Si-Wei; Huang, Xing-Jiu; Wei, Yan

    2016-01-28

    A wealth of research has been available discussing nanogap devices for detecting very small quantities of biomolecules by observing their electrical behavior generally performed in dry conditions. We report that a gold nanogapped electrode with tunable gap length for ultra-sensitive detection of streptavidin based on electrochemical impedance technique. The gold nanogap is fabricated using simple monolayer film deposition and in-situ growth of gold nanoparticles in a traditional interdigitated array (IDA) microelectrode. The electrochemical impedance biosensor with a 25-nm nanogap is found to be ultra-sensitive to the specific binding of streptavidin to biotin. The binding of the streptavidin hinder the electron transfer between two electrodes, resulting in a large increase in electron-transfer resistance (Ret) for operating the impedance. A linear relation between the relative Ret and the logarithmic value of streptavidin concentration is observed in the concentration range from 1 pM (picomolar) to 100 nM (nanomolar). The lowest detectable concentration actually measured reaches 1 pM. We believe that such an electrochemical impedance nanogap biosensor provides a useful approach towards biomolecular detection that could be extended to a number of other systems.

  3. A Substrate-Integrated and Scalable Templated Approach Based on Rusted Steel for the Fabrication of Polypyrrole Nanotube Arrays

    Energy Technology Data Exchange (ETDEWEB)

    J Velazquez; A Gaikwad; T Rout; J Rzayev; S Banerjee

    2011-12-31

    We report here a facile, generalizable, and entirely scalable approach for the fabrication of vertically aligned arrays of Fe{sub 2}O{sub 3}/polypyrrole core-shell nanostructures and polypyrrole nanotubes. Our 'all electrochemical' approach is based on the fabrication of {alpha}-Fe{sub 2}O{sub 3} nanowire arrays by the simple heat treatment of commodity low carbon steel substrates, followed by electropolymerization of conformal polypyrrole sheaths around the nanowires. Subsequently, electrochemical etching of the nanowires yields large-area vertically aligned polypyrrole nanotube arrays on the steel substrate. The developed methodology is generalizable to functionalized pyrrole monomers and represents a significant practical advance of relevance to the technological implementation of conjugated polymer nanostructures in electrochromics, electrochemical energy storage, and sensing.

  4. Distance effects in electrochemical micromachining

    Science.gov (United States)

    Xu, Lizhong; Pan, Yue; Zhao, Chuanjun

    2016-09-01

    Considering exponential dependence of currents on double-layer voltage and the feedback effect of the electrolyte resistance, a distance effect in electrochemical micromachining is found, namely that both time constant and double-layer voltage depend on the separation of electrodes. The double-layer voltage is the real voltage used in processing. Under DC voltage, the apparent voltages between two electrodes are constant for different separations, but the real voltages change with the separations. Small separations exert substantial effects on the real voltages. Accordingly, a DC-voltage small-separation electrochemical micromachining technique was proposed. The double-layer voltage drops sharply as the small separation increases. Thus, the electrochemical reactions are confined to electrode regions in very close proximity even under DC voltage. The machining precision can be significantly enhanced by reducing the voltage and separation between electrodes. With this technique, the machining of conducting materials with submicrometre precision was achieved.

  5. Apoptosis Evaluation by Electrochemical Techniques.

    Science.gov (United States)

    Yin, Jian; Miao, Peng

    2016-03-01

    Apoptosis has close relevance to pathology, pharmacology, and toxicology. Accurate and convenient detection of apoptosis would be beneficial for biological study, clinical diagnosis, and drug development. Based on distinct features of apoptotic cells, a diversity of analytical techniques have been exploited for sensitive analysis of apoptosis, such as surface plasmon resonance, electrochemical methods, flow cytometry, and some imaging assays. Among them, the features of simplicity, easy operation, low cost, and high sensitivity make electrochemical techniques powerful tools to investigate electron-transfer processes of in vitro biological systems. In this contribution, a general overview of current knowledge on various technical approaches for apoptosis evaluation is provided. Furthermore, recently developed electrochemical biosensors for detecting apoptotic cells and their advantages over traditional methods are summarized. One of the main considerations focuses on designing the recognition elements based on various biochemical events during apoptosis.

  6. Electrochemical Reduction of Oxygen on Multi-walled Carbon Nanotubes Electrode in Alkaline Solution

    Institute of Scientific and Technical Information of China (English)

    You Qun CHU; Chun An MA; Feng Ming ZHAO; Hui HUANG

    2004-01-01

    The multi-walled carbon nanotubes (MWNTs) electrode was constructed using poly- tetrafluoroethylene as binder, and the electrochemical reductive behavior of oxygen in alkaline solution was first examined on this electrode. Compared with other carbon materials, MWNTs show higher electrocatalytic activity, and the reversibility of O2 reduction reaction is greatly improved. The experiments reveal that the electrochemical reduction of O2 to HO2- is controlled by adsorption. The preliminary results illustrate the potential application of MWNTs in fuel cells.

  7. Electrochemical Sensor for Oxidation of NO Based on Au-Pt Nanoparticles Self-assembly Film

    Institute of Scientific and Technical Information of China (English)

    XIE,Jia; YU,Zhihui; XIA,Dingguo

    2009-01-01

    Au-Pt bimetallic nanoparticles film used as an efficient electrochemical sensor was prepared by self-assembled Au-Pt bimetallic nanoparticles on a glassy carbon (GC) substrate using thioglycolic acid as a linker. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that the Au-Pt nanoparticles self-assembly film was dense and uniform. Electrochemical experiments revealed that Au-Pt bimetallic nanoparticles film/GC electrode showed high electrocatalytic activity to the oxidation of nitric oxide.

  8. Antitumor effects of electrochemical treatment

    Institute of Scientific and Technical Information of China (English)

    Héctor Manuel Camué Ciria; Maraelys Morales González; Lisset Ortíz Zamora; Luis Enrique Bergues Cabrales; Gustavo Victoriano Sierra González; Luciana Oliveira de Oliveira; Rodrigo Zanella

    2013-01-01

    Electrochemical treatment is an alternative modality for tumor treatment based on the application of a low intensity direct electric current to the tumor tissue through two or more platinum electrodes placed within the tumor zone or in the surrounding areas.This treatment is noted for its great effectiveness,minimal invasiveness and local effect.Several studies have been conducted worldwide to evaluate the antitumoral effect of this therapy.In all these studies a variety of biochemical and physiological responses of tumors to the applied treatment have been obtained.By this reason,researchers have suggested various mechanisms to explain how direct electric current destroys tumor cells.Although,it is generally accepted this treatment induces electrolysis,electroosmosis and electroporation in tumoral tissues.However,action mechanism of this alternative modality on the tumor tissue is not well understood.Although the principle of Electrochemical treatment is simple,a standardized method is not yet available.The mechanism by which Electrochemical treatment affects tumor growth and survival may represent more complex process.The present work analyzes the latest and most important research done on the electrochemical treatment of tumors.We conclude with our point of view about the destruction mechanism features of this alternative therapy.Also,we suggest some mechanisms and strategies from the thermodynamic point of view for this therapy.In the area of Electrochemical treatment of cancer this tool has been exploited very little and much work remains to be done.Electrochemical treatment constitutes a good therapeutic option for patients that have failed the conventional oncology methods.

  9. Integration of a highly ordered gold nanowires array with glucose oxidase for ultra-sensitive glucose detection

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jiewu [NanoScience and Sensor Technology Research Group, School of Applied Sciences and Engineering, Monash University, Gippsland Campus, Churchill 3842, VIC Australia (Australia); Laboratory of Functional Nanomaterials and Devices, School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, Anhui (China); Adeloju, Samuel B., E-mail: sam.adeloju@monash.edu [NanoScience and Sensor Technology Research Group, School of Applied Sciences and Engineering, Monash University, Gippsland Campus, Churchill 3842, VIC Australia (Australia); Wu, Yucheng, E-mail: ycwu@hfut.edu.cn [Laboratory of Functional Nanomaterials and Devices, School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, Anhui (China)

    2014-01-27

    Graphical abstract: -- Highlights: •Successfully synthesised highly-ordered gold nanowires array with an AAO template. •Fabricated an ultra-sensitive glucose nanobiosensor with the gold nanowires array. •Achieved sensitivity as high as 379.0 μA cm{sup −2} mM{sup −1} and detection limit as low as 50 nM. •Achieved excellent anti-interference with aid of Nafion membrane towards UA and AA. •Enabled successful detection and quantification of glucose in human blood serum. -- Abstract: A highly sensitive amperometric nanobiosensor has been developed by integration of glucose oxidase (GO{sub x}) with a gold nanowires array (AuNWA) by cross-linking with a mixture of glutaraldehyde (GLA) and bovine serum albumin (BSA). An initial investigation of the morphology of the synthesized AuNWA by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) revealed that the nanowires array was highly ordered with rough surface, and the electrochemical features of the AuNWA with/without modification were also investigated. The integrated AuNWA–BSA–GLA–GO{sub x} nanobiosensor with Nafion membrane gave a very high sensitivity of 298.2 μA cm{sup −2} mM{sup −1} for amperometric detection of glucose, while also achieving a low detection limit of 0.1 μM, and a wide linear range of 5–6000 μM. Furthermore, the nanobiosensor exhibited excellent anti-interference ability towards uric acid (UA) and ascorbic acid (AA) with the aid of Nafion membrane, and the results obtained for the analysis of human blood serum indicated that the device is capable of glucose detection in real samples.

  10. Introduction to adaptive arrays

    CERN Document Server

    Monzingo, Bob; Haupt, Randy

    2011-01-01

    This second edition is an extensive modernization of the bestselling introduction to the subject of adaptive array sensor systems. With the number of applications of adaptive array sensor systems growing each year, this look at the principles and fundamental techniques that are critical to these systems is more important than ever before. Introduction to Adaptive Arrays, 2nd Edition is organized as a tutorial, taking the reader by the hand and leading them through the maze of jargon that often surrounds this highly technical subject. It is easy to read and easy to follow as fundamental concept

  11. Dechlorination by combined electrochemical reduction and oxidation*

    OpenAIRE

    Cong, Yan-qing; Wu, Zu-cheng; Tan, Tian-en

    2005-01-01

    Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate was more than 90% by the combined electrochemical r...

  12. Electrochemical Characterisation of Nanocrystalline Nickel

    Directory of Open Access Journals (Sweden)

    Deepika Sachdeva

    2008-07-01

    Full Text Available Nanocry stalline nickel (nc-Ni coatings were produced by pulse electro deposition using Watts bath with sodium citrate and saccharin added as grain refining agents. The electrochemical nature of nc-Ni coatings, evaluated in 1M H2SO4 solution by electrochemical impedance spectroscopy. The corrosion rate of bulk nickel was lower than that of nc-Ni after stabilisation of free corrosion potential.Defence Science Journal, 2008, 58(4, pp.525-530, DOI:http://dx.doi.org/10.14429/dsj.58.1673

  13. P systems with array objects and array rewriting rules

    Institute of Scientific and Technical Information of China (English)

    K.G. Subramanian; R. Saravanan; M. Geethalakshmi; P. Helen Chandra; M. Margenstern

    2007-01-01

    Array P systems were introduced by Pǎun Gh. which is linking the two areas of membrane computing and picture grammars. Puzzle grammars were introduced by us for generating connected picture arrays in the two-dimensional plane, motivated by the problem of tiling the plane. On the other hand, incorporating into arrays the developmental type of generation used in the well-known biologically motivated L systems, Siromoney and Siromoney proposed a very general rectangular array generating model, called extended controlled tabled L array system (ECTLAS). In this paper we introduce two variations of the array P system, called BPG array P system and parallel array P system. The former has in the regions array objects and basic puzzle grammar rules (BPG), which are a specific kind of puzzle grammar rules. In the latter, the regions have rectangular array objects and tables of context-free rules. We examine these two types of P systems for their array generative power.

  14. Electrochemical characterization on cobalt sulfide for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Feng; Zhao, Yong-Qing; Zhang, Guo-Qing [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China); Li, Hu-Lin [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautisc, Nanjing 210013 (China); College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000 (China)

    2007-06-15

    High capacitance at a high charge-discharge current density of 50 mA/cm{sup 2} for a new type of electrochemical supercapacitor cobalt sulfide (CoS{sub x}) have been studied for the first time. The CoS{sub x} was prepared by a very simply chemical precipitation method. The electrochemical capacitance performance of this compound was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge tests with a three-electrode system. The results show that CoS{sub x} has excellent electrochemical capacitive characteristic with potential range -0.3 {proportional_to} 0.35 V (versus SCE) in 6 M KOH solution. Charge-discharge behaviors have been observed with the highest specific capacitance values of 475 F/g at the current density of 5 mA/cm{sup 2}, even at the high current density of 50 mA/cm{sup 2}, CoS{sub x} also shows the high specific capacitance values of 369 F/g. (author)

  15. Advanced design of conductive polymeric arrays with controlled electrical resistance using direct laser interference patterning

    Energy Technology Data Exchange (ETDEWEB)

    Lasagni, A.F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany); George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Acevedo, D.F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany); Universidad Nacional de Rio Cuarto, Departamento de Quimica, Cordoba (Argentina); Barbero, C.A. [Universidad Nacional de Rio Cuarto, Departamento de Quimica, Cordoba (Argentina); Muecklich, F. [Saarland University, Department of Materials Science, Chair of Functional Materials, Building C 6.3, 7. Stock, P.O. Box 15 11 50, Saarbruecken (Germany)

    2008-06-15

    In this work, we report a simple method for the fabrication of regular conducting polyaniline periodic arrays on large areas of glass or gold substrates using direct laser interference patterning. Additionally, by controlling the laser intensity it is possible to precisely tune the width of the periodic arrays and consequently the electrical resistance of the polyaniline strips. The periodic arrays were characterized using scanning electron microscopy, white light interferometry and cyclic voltametry. The great importance of the method reported lies both in its versatility and the ability to control the properties of the modified polymer electrodes with high precision. This is important for prospective applications such as electrochemical sensors. (orig.)

  16. Biochemical Sensors Using Carbon Nanotube Arrays

    Science.gov (United States)

    Li, Jun (Inventor); Meyyappan, Meyya (Inventor); Cassell, Alan M. (Inventor)

    2011-01-01

    Method and system for detecting presence of biomolecules in a selected subset, or in each of several selected subsets, in a fluid. Each of an array of two or more carbon nanotubes ("CNTs") is connected at a first CNT end to one or more electronics devices, each of which senses a selected electrochemical signal that is generated when a target biomolecule in the selected subset becomes attached to a functionalized second end of the CNT, which is covalently bonded with a probe molecule. This approach indicates when target biomolecules in the selected subset are present and indicates presence or absence of target biomolecules in two or more selected subsets. Alternatively, presence of absence of an analyte can be detected.

  17. Flexible retinal electrode array

    Energy Technology Data Exchange (ETDEWEB)

    Okandan, Murat (Albuquerque, NM); Wessendorf, Kurt O. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    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.

  18. Expandable LED array interconnect

    Science.gov (United States)

    Yuan, Thomas Cheng-Hsin; Keller, Bernd

    2011-03-01

    A light emitting device that can function as an array element in an expandable array of such devices. The light emitting device comprises a substrate that has a top surface and a plurality of edges. Input and output terminals are mounted to the top surface of the substrate. Both terminals comprise a plurality of contact pads disposed proximate to the edges of the substrate, allowing for easy access to both terminals from multiple edges of the substrate. A lighting element is mounted to the top surface of the substrate. The lighting element is connected between the input and output terminals. The contact pads provide multiple access points to the terminals which allow for greater flexibility in design when the devices are used as array elements in an expandable array.

  19. Protein Functionalized Nanodiamond Arrays

    Directory of Open Access Journals (Sweden)

    Liu YL

    2010-01-01

    Full Text Available Abstract Various nanoscale elements are currently being explored for bio-applications, such as in bio-images, bio-detection, and bio-sensors. Among them, nanodiamonds possess remarkable features such as low bio-cytotoxicity, good optical property in fluorescent and Raman spectra, and good photostability for bio-applications. In this work, we devise techniques to position functionalized nanodiamonds on self-assembled monolayer (SAMs arrays adsorbed on silicon and ITO substrates surface using electron beam lithography techniques. The nanodiamond arrays were functionalized with lysozyme to target a certain biomolecule or protein specifically. The optical properties of the nanodiamond-protein complex arrays were characterized by a high throughput confocal microscope. The synthesized nanodiamond-lysozyme complex arrays were found to still retain their functionality in interacting with E. coli.

  20. Fast photoresponse of zinc ferrite nanotube arrays fabricated by electrodeposition

    International Nuclear Information System (INIS)

    Although nano-sized zinc ferrite materials exhibit excellent visible light activity, their photoresponse characteristics as photodetectors have rarely been investigated. In this paper, zinc ferrite nanotube arrays were fabricated using electrodeposition with the aid of zinc oxide nanowire arrays as a template. These nanotube arrays showed tens of milliseconds-response photocurrents under the irradiation of a 532 nm solid-state laser, and the magnitudes of the photocurrents were linearly increased with increasing laser power. These features of ZnFe2O4 nanotube arrays revealed their potential applications in high-frequency or high-speed photodevices. (paper)

  1. Formation of aromatic thermoplastic and carbon-fiber prepreg by electrochemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Li Hong.

    1991-01-01

    A new technique was developed and demonstrated for combining carbon fibers with aromatic thermoplastic matrices to form a high-quality towpreg. The developed technique utilizes an in-situ electrochemical process (Electrochemical polymerization - ECP) to create the entire polymer matrix surrounding the fiber array by direct polymerization of monomer. Poly-paraxylylene (PPX) and derivatives are successfully polymerized in-situ on carbon fiber surfaces through ECP. A PPX/carbon-fiber towpreg with 40 vol % of matrix is achieved in a fairly short reaction time with a high polymer-coating efficiency. Vapor deposition polymerization (VDP) was also studied. PPX and carbon-fiber towpreg were made successfully by this process. A comparison between ECP and VDP was conducted. A study on electrochemical oxidation (ECO) of carbon fibers was also performed. The ECO treatment may be suitable for carbon fibers incorporated in composites with high-temperature curing resins and thermoplastic matrices.

  2. The electrochemical properties of the cyclic deformed passive metals

    Energy Technology Data Exchange (ETDEWEB)

    Pokhmurskii, V.; Khoma, M. [Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5 Naukova Str., Lviv, 79601 (Ukraine)

    2004-07-01

    It has been investigated the influence of chloride environment on corrosion fatigue fracture of different classes stainless steels. The change of electrochemical properties of deformed corrosion resistance steels and alloys during the initial stage of corrosion fatigue fracture has been studied. It has been determined the influence of micro-deformation processes of surface at different tensions on the electrochemical activating of stainless steels. The critical values of electrochemical parameters of the deformed metal has been established, at which probability of corrosion fatigue fracture grows sharply. The features of character change polarization current of stainless steels at loadings even to corrosion fatigue limit has been shown. It served by basis for development of method speed-up determination of corrosion fatigue limit without destruction of specimens. It has been established possibility of decline corrosion currents of stainless steels as a result of deformation at tensions which do not cause destruction. It was revealed the reason of this effect: different acceleration by mechanical tensions of dissolution of alloys separate components, that results in enrichment of surface by a chrome and nickel. It is instrumental in the improvement of protective properties of passive tapes. The analysis of results of the conducted researches allowed to set that corrosion endurance of stainless steels is determined by intensity of their electrochemical activating at tensions of even to corrosive fatigue limit. (authors)

  3. Engineering Fano resonances in discrete arrays

    International Nuclear Information System (INIS)

    We study transmission properties of discrete arrays composed of a linear waveguide coupled to a system of N side defect states. This simple system can be used to model discrete networks of coupled defect modes in photonic crystals, complex waveguide arrays in two-dimensional nonlinear lattices, and ring-resonator structures. We demonstrate the basic principles of the resonant scattering management through engineering Fano resonances and find exact results for the wave transmission coefficient. We reveal conditions for perfect reflections and transmissions due to either destructive or constructive interferences, and associate them with Fano resonances, also demonstrating how these resonances can be tuned by nonlinear defects

  4. Separator material for electrochemical cells

    Science.gov (United States)

    Cieslak, Wendy R.; Storz, Leonard J.

    1991-01-01

    An electrochemical cell characterized as utilizing an aramid fiber as a separator material. The aramid fibers are especially suited for lithium/thionyl chloride battery systems. The battery separator made of aramid fibers possesses superior mechanical strength, chemical resistance, and is flame retardant.

  5. Electrochemical method for transferring graphene

    DEFF Research Database (Denmark)

    2015-01-01

    The present application discloses a method for separating a graphene-support layer laminate from a conducting substrate-graphene-support layer laminate, using a gentle, controllable electrochemical method. In this way, substrates which are fragile, expensive or difficult to manufacture can be used...

  6. All-Polymer Electrochemical Sensors

    DEFF Research Database (Denmark)

    Kafka, Jan Robert

    This thesis presents fabrication strategies to produce different types of all-polymer electrochemical sensors based on electrodes made of the highly conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT). Three different systems are presented, fabricated either by using microdrilling or by hot...

  7. Stable field emission from arrays of vertically aligned free-standing metallic nanowires

    DEFF Research Database (Denmark)

    Xavier, S.; Mátéfi-Tempfli, Stefan; Ferain, E.;

    2008-01-01

    We present a fully elaborated process to grow arrays of metallic nanowires with controlled geometry and density, based on electrochemical filling of nanopores in track-etched templates. Nanowire growth is performed at room temperature, atmospheric pressure and is compatible with low cost fabricat......A cm for a 30 V μm applied electric field. © IOP Publishing Ltd.......We present a fully elaborated process to grow arrays of metallic nanowires with controlled geometry and density, based on electrochemical filling of nanopores in track-etched templates. Nanowire growth is performed at room temperature, atmospheric pressure and is compatible with low cost...... fabrication and large surfaces. This technique offers an excellent control of the orientation, shape and nanowires density. It is applied to fabricate field emission arrays with a good control of the emission site density. We have prepared Co, Ni, Cu and Rh nanowires with a height of 3 μm, a diameter of 80 nm...

  8. Broadband-antireflective hybrid nanopillar array for photovoltaic application

    International Nuclear Information System (INIS)

    Subwavelength structures such as nanopillars, nanoholes, and nanodomes have recently attracted considerable attention as antireflective structures for solar cells. Recent studies on the optical property of nanopillar array revealed that the reflection minimum is related to the diameter, the pitch, and the height of nanopillars. Here, we investigate the “hybrid” nanopillar array, which is composed of different diameters of nanopillars. Finite differential time domain simulations revealed that the photogeneration in a hybrid nanopillar array is spatially heterogeneous: carriers are generated mainly in the narrower pillars for short-wavelength incident light and in the thicker pillars for long-wavelength light, respectively. Hybrid silicon nanopillar arrays fabricated by using electron beam lithography and dry etching show excellent broadband antireflection property. Hybrid nanopillar array is thus highly promising for next-generation antireflection for photovoltaic applications

  9. Revealing Rembrandt

    Directory of Open Access Journals (Sweden)

    Andrew J Parker

    2014-04-01

    Full Text Available The power and significance of artwork in shaping human cognition is self-evident. The starting point for our empirical investigations is the view that the task of neuroscience is to integrate itself with other forms of knowledge, rather than to seek to supplant them. In our recent work, we examined a particular aspect of the appreciation of artwork using present-day functional magnetic resonance imaging (fMRI. Our results emphasised the continuity between viewing artwork and other human cognitive activities. We also showed that appreciation of a particular aspect of artwork, namely authenticity, depends upon the co-ordinated activity between the brain regions involved in multiple decision making and those responsible for processing visual information. The findings about brain function probably have no specific consequences for understanding how people respond to the art of Rembrandt in comparison with their response to other artworks. However, the use of images of Rembrandt’s portraits, his most intimate and personal works, clearly had a significant impact upon our viewers, even though they have been spatially confined to the interior of an MRI scanner at the time of viewing. Neuroscientific studies of humans viewing artwork have the capacity to reveal the diversity of human cognitive responses that may be induced by external advice or context as people view artwork in a variety of frameworks and settings.

  10. Electrochemical impedance characterization of FeSn{sub 2} electrodes for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Chamas, M.; Lippens, P-E.; Jumas, J-C. [Institut Charles Gerhardt, Equipe Agregats Interfaces et Materiaux pour l' Energie, UMR 5253 CNRS, Universite Montpellier 2, Place Eugene Bataillon, 34095 Montpellier cedex 5 (France); Hassoun, J., E-mail: jusef.hassoun@uniroma1.it [Dipartemento di Chimica, Universita di Roma, ' La Sapienza' , 00185 Rome (Italy); Panero, S.; Scrosati, B. [Dipartemento di Chimica, Universita di Roma, ' La Sapienza' , 00185 Rome (Italy)

    2011-07-30

    Highlights: > In this paper we study a tin based, FeSn{sub 2}, high capacity lithium-alloying electrode. > The electrochemical performance of this electrode in lithium batteries is remarkably influenced by the current rate. > This aspect is investigated by electrochemical techniques such as galvanostatic cycling and impedance spectroscopy. > The results demonstrated that the good electrochemical behavior of the electrode at the higher currents is due to the formation of a stable solid electrolyte interphase (SEI) film. - Abstract: This work reports the electrochemical characterization of a micro-scale FeSn{sub 2} electrode in a lithium battery. The electrode is proposed as anode material for advanced lithium ion batteries due to its characteristics of high capacity (500 mAh g{sup -1}) and low working voltage (0.6 V vs. Li). The electrochemical alloying process is studied by cyclic voltammetry and galvanostatic cycling while the interfacial properties are investigated by electrochemical impedance spectroscopy. The impedance measurements in combination with the galvanostatic cycling tests reveal relatively low overall impedance values and good electrochemical performance for the electrode, both in terms of delivered capacity and cycling stability, even at the higher C-rate regimes.

  11. Optimizing Chemical Sensor Array Sizes

    International Nuclear Information System (INIS)

    Optimal selection of array sensors for a chemical sensing application is a nontrivial task. It is commonly believed that ''more is better'' when choosing the number of sensors required to achieve good chemical selectivity. However, cost and system complexity issues point towards the choice of small arrays. A quantitative array optimization is carried out to explore the selectivity of arrays of partially-selective chemical sensors as a function of array size. It is shown that modest numbers (dozens) of target analytes are completely distinguished with a range of arrays sizes. However, the array selectivity and the robustness against sensor sensitivity variability are significantly degraded if the array size is increased above a certain number of sensors, so that relatively small arrays provide the best performance. The results also suggest that data analyses for very large arrays of partially-selective sensors will be optimized by separately anal yzing small sensor subsets

  12. Imaging antenna arrays

    Science.gov (United States)

    Rutledge, D. B.; Muha, M. S.

    1982-01-01

    Many millimeter and far-infrared imaging systems are limited in sensitivity and speed because they depend on a single scanned element. Because of recent advances in planar detectors such as Schottky diodes, superconducting tunnel junctions, and microbolometers, an attractive approach to this problem is a planar antenna array with integrated detectors. A planar line antenna array and optical system for imaging has been developed. The significant advances are a 'reverse-microscope' optical configuration and a modified bow-tie antenna design. In the 'reverse-microscope' configuration, a lens is attached to the bottom of the substrate containing the antennas. Imaging is done through the substrate. This configuration eliminates the troublesome effects of substrate surface waves. The substrate lens has only a single refracting surface, making possible a virtually aplanatic system, with little spherical aberration or coma. The array is characterized by an optical transfer function that is easily measured. An array with 19 dB crosstalk levels between adjacent antennas has been tested and it was found that the array captured 50 percent of the available power. This imaging system was diffraction limited.

  13. Stretchable Micro-Electrode Array

    Energy Technology Data Exchange (ETDEWEB)

    Maghribi, M; Hamilton, J; Polla, D; Rose, K; Wilson, T; Krulevitch, P

    2002-03-08

    This paper focuses on the design consideration, fabrication processes and preliminary testing of the stretchable micro-electrode array. We are developing an implantable, stretchable micro-electrode array using polymer-based microfabrication techniques. The device will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces and electroplated electrodes. The metal features are embedded within a thin ({approx}50 micron) substrate fabricated using poly (dimethylsiloxane) (PDMS), a biocompatible elastomeric material that has very low water permeability. The conformable nature of PDMS is critical for ensuring uniform contact with the curved surface of the retina. To fabricate the device, we developed unique processes for metalizing PDMS to produce robust traces capable of maintaining conductivity when stretched (5%, SD 1.5), and for selectively passivating the conductive elements. An in situ measurement of residual strain in the PDMS during curing reveals a tensile strain of 10%, explaining the stretchable nature of the thin metalized devices.

  14. Study on the Carbonation Behavior of Cement Mortar by Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Biqin Dong

    2014-01-01

    Full Text Available A new electrochemical model has been carefully established to explain the carbonation behavior of cement mortar, and the model has been validated by the experimental results. In fact, it is shown by this study that the electrochemical impedance behavior of mortars varies in the process of carbonation. With the cement/sand ratio reduced, the carbonation rate reveals more remarkable. The carbonation process can be quantitatively accessed by a parameter, which can be obtained by means of the electrochemical impedance spectroscopy (EIS-based electrochemical model. It has been found that the parameter is a function of carbonation depth and of carbonation time. Thereby, prediction of carbonation depth can be achieved.

  15. NOX Reduction Using an Electrochemical Cell with NOX adsorbents

    DEFF Research Database (Denmark)

    Shao, Jing

    -Pt-Al2O3 adsorption layer. The effects of the NOx adsorbents on the electrode processes were characterized by electrochemical impedance spectroscopy (EIS). The impedance analysis revealed that the NOx adsorbents greatly enhanced the electrode activity, mainly contributed by the promotion of adsorption......This thesis studied the electrochemical cells modified by NOx adsorbents for the NOx reduction under O2-rich conditions. The structure of a multilayer electrochemical cell with a NOx adsorption layer was optimized by removing a yttria-stabilized zirconia (YSZ) cover layer coated on a Pt....../Ni/YSZ electrode. It was found that the NOx removal properties of the electrochemical cell were dramatically enhanced through this optimization, which was attributed to the extensive release of selective reaction sites for NOx species and a strong promotion for NOx reduction from the interaction of the directly...

  16. FEL phased array configurations

    Science.gov (United States)

    Shellan, Jeffrey B.

    1986-01-01

    The advantages and disadvantages of various phased array and shared aperture concepts for FEL configurations are discussed. Consideration is given to the characteristics of intra- and inter-micropulse phasing; intra-macropulse phasing; an internal coupled resonator configuration; and an injection locked oscillator array. The use of a master oscillator power amplifier (MOPA) configuration with multiple or single master oscillators for FELs is examined. The venetian blind, rotating plate, single grating, and grating rhomb shared aperture concepts are analyzed. It is noted that the shared aperture approach using a grating rhomb and the MOPA concept with a single master oscillator and a coupled resonator are useful for FEL phased array configurations; and the MOPA concept is most applicable.

  17. Wireless Josephson Junction Arrays

    Science.gov (United States)

    Adams, Laura

    2015-03-01

    We report low temperature, microwave transmission measurements on a wireless two- dimensional network of Josephson junction arrays composed of superconductor-insulator -superconductor tunnel junctions. Unlike their biased counterparts, by removing all electrical contacts to the arrays and superfluous microwave components and interconnects in the transmission line, we observe new collective behavior in the transmission spectra. In particular we will show emergent behavior that systematically responds to changes in microwave power at fixed temperature. Likewise we will show the dynamic and collective response of the arrays while tuning the temperature at fixed microwave power. We discuss these spectra in terms of the Berezinskii-Kosterlitz-Thouless phase transition and Shapiro steps. We gratefully acknowledge the support Prof. Steven Anlage at the University of Maryland and Prof. Allen Goldman at the University of Minnesota. Physics and School of Engineering and Applied Sciences.

  18. Low-dimensional carbon and MXene-based electrochemical capacitor electrodes

    Science.gov (United States)

    Yoon, Yeoheung; Lee, Keunsik; Lee, Hyoyoung

    2016-04-01

    Due to their unique structure and outstanding intrinsic physical properties such as extraordinarily high electrical conductivity, large surface area, and various chemical functionalities, low-dimension-based materials exhibit great potential for application in electrochemical capacitors (ECs). The electrical properties of electrochemical capacitors are determined by the electrode materials. Because energy charge storage is a surface process, the surface properties of the electrode materials greatly influence the electrochemical performance of the cell. Recently, graphene, a single layer of sp2-bonded carbon atoms arrayed into two-dimensional carbon nanomaterial, has attracted wide interest as an electrode material for electrochemical capacitor applications due to its unique properties, including a high electrical conductivity and large surface area. Several low-dimensional materials with large surface areas and high conductivity such as onion-like carbons (OLCs), carbide-derived carbons (CDCs), carbon nanotubes (CNTs), graphene, metal hydroxide, transition metal dichalcogenides (TMDs), and most recently MXene, have been developed for electrochemical capacitors. Therefore, it is useful to understand the current issues of low-dimensional materials and their device applications.

  19. Silicon nanowire based biosensing platform for electrochemical sensing of Mebendazole drug activity on breast cancer cells.

    Science.gov (United States)

    Shashaani, Hani; Faramarzpour, Mahsa; Hassanpour, Morteza; Namdar, Nasser; Alikhani, Alireza; Abdolahad, Mohammad

    2016-11-15

    Electrochemical approaches have played crucial roles in bio sensing because of their Potential in achieving sensitive, specific and low-cost detection of biomolecules and other bio evidences. Engineering the electrochemical sensing interface with nanomaterials tends to new generations of label-free biosensors with improved performances in terms of sensitive area and response signals. Here we applied Silicon Nanowire (SiNW) array electrodes (in an integrated architecture of working, counter and reference electrodes) grown by low pressure chemical vapor deposition (LPCVD) system with VLS procedure to electrochemically diagnose the presence of breast cancer cells as well as their response to anticancer drugs. Mebendazole (MBZ), has been used as antitubulin drug. It perturbs the anodic/cathodic response of the cell covered biosensor by releasing Cytochrome C in cytoplasm. Reduction of cytochrome C would change the ionic state of the cells monitored by SiNW biosensor. By applying well direct bioelectrical contacts with cancer cells, SiNWs can detect minor signal transduction and bio recognition events, resulting in precise biosensing. Our device detected the trace of MBZ drugs (with the concentration of 2nM) on electrochemical activity MCF-7 cells. Also, experimented biological analysis such as confocal and Flowcytometry assays confirmed the electrochemical results. PMID:27196254

  20. Electrochemical properties of mixed WC and Pt-black powders

    Directory of Open Access Journals (Sweden)

    MAJA D. OBRADOVIC

    2008-12-01

    Full Text Available The electrochemical characteristics of a mixture of Pt-black and WC powders and its catalytic activity for methanol and formic acid oxidation were investigated in acid solution. XRD and AFM measurements revealed that the WC powder employed for the investigation was a single-phase material consisting of crystallites/spherical particles of average size of about 50 nm, which were agglomerated into much larger particles. Cyclic voltammetry showed that the WC underwent electrochemical oxidation, producing tungstate species. In the case of the mixed Pt + WC powders, the tungstate species were deposited on the Pt as a thin film of hydrous tungsten oxide. Enhanced hydrogen intercalation in the hydrous tungsten oxide was observed and it was proposed to be promoted in mixed powders by the presence of hydrogen adatoms on bare Pt sites. The determination of Pt surface area in the Pt + WC layer by stripping of underpotentially deposited Cu revealed that the entire Pt surface was accessible for underpotential deposition of Cu. Investigation of the electrochemical oxidation of methanol and formic acid on Pt + WC and pure Pt layers did not indicate electrocatalytic promotion due to the presence of WC.

  1. The Submillimeter Array

    CERN Document Server

    Ho, P T P; Lo, K Y; Ho, Paul T.P.; Moran, James M.; Lo, Kwok Yung

    2004-01-01

    The Submillimeter Array (SMA), a collaborative project of the Smithsonian Astrophysical Observatory (SAO) and the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), has begun operation on Mauna Kea in Hawaii. A total of eight 6-m telescopes comprise the array, which will cover the frequency range of 180-900 GHz. All eight telescopes have been deployed and are operational. First scientific results utilizing the three receiver bands at 230, 345, and 690 GHz have been obtained and are presented in the accompanying papers.

  2. Photovoltaic array performance model.

    Energy Technology Data Exchange (ETDEWEB)

    Kratochvil, Jay A.; Boyson, William Earl; King, David L.

    2004-08-01

    This document summarizes the equations and applications associated with the photovoltaic array performance model developed at Sandia National Laboratories over the last twelve years. Electrical, thermal, and optical characteristics for photovoltaic modules are included in the model, and the model is designed to use hourly solar resource and meteorological data. The versatility and accuracy of the model has been validated for flat-plate modules (all technologies) and for concentrator modules, as well as for large arrays of modules. Applications include system design and sizing, 'translation' of field performance measurements to standard reporting conditions, system performance optimization, and real-time comparison of measured versus expected system performance.

  3. Soldered solar arrays

    Science.gov (United States)

    Allen, H. C.

    1982-06-01

    The ability of soldered interconnects to withstand a combination of long life and severe environmental conditions was investigated. Improvements in joint life from the use of solder mixes appropriate to low temperature conditons were studied. Solder samples were placed in a 150 C oven for 5 weeks (= 12 yr at 80 C, or 24 at 70 C according to Arrhenius's rule). Conventional and high solder melting point array samples underwent 1000 thermal cycles between -186 and 100 C. Results show that conventional and lead rich soldered arrays can survive 10 yr geostationary orbit missions.

  4. Wire Array Photovoltaics

    Science.gov (United States)

    Turner-Evans, Dan

    Over the past five years, the cost of solar panels has dropped drastically and, in concert, the number of installed modules has risen exponentially. However, solar electricity is still more than twice as expensive as electricity from a natural gas plant. Fortunately, wire array solar cells have emerged as a promising technology for further lowering the cost of solar. Si wire array solar cells are formed with a unique, low cost growth method and use 100 times less material than conventional Si cells. The wires can be embedded in a transparent, flexible polymer to create a free-standing array that can be rolled up for easy installation in a variety of form factors. Furthermore, by incorporating multijunctions into the wire morphology, higher efficiencies can be achieved while taking advantage of the unique defect relaxation pathways afforded by the 3D wire geometry. The work in this thesis shepherded Si wires from undoped arrays to flexible, functional large area devices and laid the groundwork for multijunction wire array cells. Fabrication techniques were developed to turn intrinsic Si wires into full p-n junctions and the wires were passivated with a-Si:H and a-SiNx:H. Single wire devices yielded open circuit voltages of 600 mV and efficiencies of 9%. The arrays were then embedded in a polymer and contacted with a transparent, flexible, Ni nanoparticle and Ag nanowire top contact. The contact connected >99% of the wires in parallel and yielded flexible, substrate free solar cells featuring hundreds of thousands of wires. Building on the success of the Si wire arrays, GaP was epitaxially grown on the material to create heterostructures for photoelectrochemistry. These cells were limited by low absorption in the GaP due to its indirect bandgap, and poor current collection due to a diffusion length of only 80 nm. However, GaAsP on SiGe offers a superior combination of materials, and wire architectures based on these semiconductors were investigated for multijunction

  5. Electrochemical treatment of liquid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.

    1996-10-01

    Electrochemical treatment processes are being evaluated and developed for the destruction of organic compounds and nitrates/nitrites and the removal of other hazardous species from liquid wastes stored throughout the DOE complex. This activity consists of five major tasks: (1) evaluation of different electrochemical reactors for the destruction and removal of hazardous waste components, (2) development and validation of engineering process models, (3) radioactive laboratory-scale tests, (4) demonstration of the technology in an engineering-scale size reactor, and (5) analysis and evaluation of testing data. The development program team is comprised of individuals from federal, academic, and private industry. Work is being carried out in DOE, academic, and private industrial laboratories.

  6. Electrochemical detection of single molecules.

    Science.gov (United States)

    Fan, F R; Bard, A J

    1995-02-10

    The electrochemical behavior of a single molecule can be observed by trapping a small volume of a dilute solution of the electroactive species between an ultramicroelectrode tip with a diameter of approximately 15 nanometers and a conductive substrate. A scanning electrochemical microscope was used to adjust the tip-substrate distance ( approximately 10 nanometers), and the oxidation of [(trimethylammonio)methyl] ferrocene (Cp(2)FeTMA(+)) to Cp(2)FeTMA(2+) was carried out. The response was stochastic, and anodic current peaks were observed as the molecule moved into and out of the electrode-substrate gap. Similar experiments were performed with a solution containing two redox species, ferrocene carboxylate (Cp(2)FeCOO(-)) and Os(bpy)(3)(2+) (bpy is 2,2'-bipyridyl). PMID:17813918

  7. Electrochemical sensing carcinogens in beverages

    CERN Document Server

    Zia, Asif Iqbal

    2016-01-01

    This book describes a robust, low-cost electrochemical sensing system that is able to detect hormones and phthalates – the most ubiquitous endocrine disruptor compounds – in beverages and is sufficiently flexible to be readily coupled with any existing chemical or biochemical sensing system. A novel type of silicon substrate-based smart interdigital transducer, developed using MEMS semiconductor fabrication technology, is employed in conjunction with electrochemical impedance spectroscopy to allow real-time detection and analysis. Furthermore, the presented interdigital capacitive sensor design offers a sufficient penetration depth of the fringing electric field to permit bulk sample testing. The authors address all aspects of the development of the system and fully explain its benefits. The book will be of wide interest to engineers, scientists, and researchers working in the fields of physical electrochemistry and biochemistry at the undergraduate, postgraduate, and research levels. It will also be high...

  8. Bio-inspired materials for electrochemical devices

    Science.gov (United States)

    Pawlicka, A.; Firmino, A.; Sentanin, F.; Sabadini, R. C.; Jimenez, D. E. Q.; Jayme, C. C.; Mindroiu, M.; Zgarian, R. G.; Tihan, G. T.; Rau, I.; Silva, M. M.; Nogueira, A. F.; Kanicki, J.; Kajzar, F.

    2015-10-01

    Natural macromolecules are very promising row materials to be used in modern technology including security and defense. They are abundant in nature, easy to extract and possess biocompatibility and biodegradability properties. These materials can be modified throughout chemical or physical processes, and can be doped with lithium and rare earth salts, ionic liquids, organic and inorganic acids. In this communication samples of DNA and modified DNA were doped with Prussian Blue (PB), poly(ethylene dioxythiophene) (PEDOT), europium and erbium triflate and organic dyes such as Nile Blue (NB), Disperse Red 1 (DR1) and Disperse Orange 3 (DO3). The colored or colorless membranes were characterized by electrochemical and spectroscopic measurements, and they were applied in electrochromic devices (ECDs) and dye sensitized solar cells (DSSC). ECDs change the color under applied potential, so they can modulate the intensity of transmitted light of 15 to 35%. As the electrochromic materials, WO3 or Prussian blue (PB), are usually blue colored, the color change is from transparent to blue. DNA, and the complexes: DNA-CTMA, DNA-DODA and DNAPEDOT: PSS were also investigated as either hole carrier material (HTM) or polymer electrolyte in dye-sensitized solar cells (DSSC). The DNA-based samples as HTM in small DSSCs revealed a solar energy conversion efficiency of 0.56%. Polymer electrolytes of DNA-CTMA and DNA-DODA, both with 10 wt% of LiI/I2, applied in small DSSC, exhibited the efficiencies of 0.18 and 0.66%, respectively. The obtained results show that natural macromolecules-based membranes are not only environmentally friendly but are also promising materials to be investigated for several electrochemical devices. However, to obtain better performances more research is still needed.

  9. Electrochemical oxidation of tamoxifen revisited

    OpenAIRE

    Garrido, Jorge; Quezada, E.; Fajín, J. L. C.; Cordeiro, M. Natália S.; Garrido, E. Manuela; Borges, Fernanda

    2013-01-01

    Tamoxifen is a selective estrogen receptor modulator that is used as an adjuvant and/or chemotherapeutic agent for the treatment of all stages of hormone-dependent breast cancer. Currently there is a deep interest in the study of tamoxifen biotransformation and identification of metabolites since they can significantly contribute to the overall pharmacological or adverse effects of the drug. Accordingly, the study of the electrochemical behavior of tamoxifen in aqueous solution is reported. T...

  10. Electrochemical Design of Optical Nanoantennas

    Directory of Open Access Journals (Sweden)

    Vasilchenko V.E.

    2015-01-01

    Full Text Available Electrochemical techniques for fabricating tapered gold nanoantennas (tips are discussed. In the paper, the tunable design of nanoantennas is demonstrated. Tip parameters such as a tip apex curvature, mesoscopic morphology, aspect ratio and enhancement factor can be varied with etching electrolyte and applied voltage. The low-cost method makes tipehnahced optical spectroscopy and microscopy feasible for routine optical measurements beyond the diffraction limit.

  11. Electrochemical Depositions in Ionic Liquids

    OpenAIRE

    De Vreese, Peter

    2013-01-01

    In this PhD thesis, several aspects of the electrodeposition of metals and alloys in ionic liquids were investigated. First, the deposition of brass from choline acetate was studied. Secondly, the electrodeposition of pure molybdenum from ionic liquids based on phosphonium chloride and zinc chloride was treated. In each case, the influence of water, either as a main constituent of the electrolyte or an impurity, was investigated. When comparing electrochemical processes such as electrodeposit...

  12. Composite Electrodes for Electrochemical Supercapacitors

    OpenAIRE

    Yang QuanMin; Li Jun; Zhitomirsky Igor

    2010-01-01

    Abstract Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4–6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with to...

  13. Supercapacitors and electrochemical pulse sources

    Energy Technology Data Exchange (ETDEWEB)

    Huggins, R.A. [Christian-Albrechts-Universitaet zu Kiel, Kaiserstrasse 2, D-24143 Kiel (Germany)

    2000-10-01

    Although often thought of as an area of low technology that is stagnant and uninteresting in the past, the use of electrochemical cells for energy storage and conversion purposes has received greatly increased attention recently. There are two general directions of interest. One is the long term goal of the development of electrical propulsion for vehicles, and the other is the rapid growth of portable electronic devices that require power sources with maximum energy content and the lowest possible size and weight. Most of the activities have been aimed at the development of electrochemical cells that are optimized toward either maximum specific energy or energy density. On the other hand, some of the current applications require electrical energy at high power levels for short times. These include very short pulses for digital electronic devices, the somewhat longer power pulse demands of some implantable medical devices, and the much larger transient power needs in connection with vehicle traction. Several mechanisms can be used to provide short term energy, and they have fundamentally different characteristics, and thus are potentially applicable to different types of transient output requirements. Some of these provide behavior that is analogous to an electrical capacitor, whereas others have more the character of batteries. The several electrochemical methods that can be used to evaluate the critical materials parameters in materials that might be applicable to such applications are discussed, as well as the use of LaPlace transform methods to convert information about the physical mechanisms and parameters of individual components into the dynamic response of an electrochemical system.

  14. Synthesis of tungsten carbide nanocrystals and their electrochemical properties

    Institute of Scientific and Technical Information of China (English)

    Jianghua ZENG; Dingsheng YUAN; Yingliang LIU; Jingxing CHEN; Sanxiang TAN

    2009-01-01

    Tungsten carbide (WC) nanocrystals have been prepared by a solvothermal method with Mg as the reductant and WO3 and anhydrous ethanol as the precursors. The effects of time and temperature on the synthesis of WC were investigated and a probable formation mechanism was discussed. The obtained WC nanocrystals were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive spec-troscopy and electrochemical methods. Hexagonal close-packed WC was successfully synthesized when the temperature was as low as 500°C. The content of carbon was more than that of W, indicating that the composition of the treated sample was C and WC only. The diameters of WC nanocrystals were ranged from 40 nm to 70 nm and the nanocrystals were dispersed on carbon films. The electrochemical measurements reveal that WC nanocrystals obviously promote Pt/C electrocatalytic ability for the oxygen reduction reaction.

  15. Electrochemical Hydrogen Storage in a Highly Ordered Mesoporous Carbon

    Directory of Open Access Journals (Sweden)

    Dan eLiu

    2014-10-01

    Full Text Available A highly order mesoporous carbon has been synthesized through a strongly acidic, aqueous cooperative assembly route. The structure and morphology of the carbon material were investigated using TEM, SEM and nitrogen adsorption-desorption isotherms. The carbon was proven to be meso-structural and consisted of graphitic micro-domain with larger interlayer space. AC impedance and electrochemical measurements reveal that the synthesized highly ordered mesoporous carbon exhibits a promoted electrochemical hydrogen insertion process and improved capacitance and hydrogen storage stability. The meso-structure and enlarged interlayer distance within the highly ordered mesoporous carbon are suggested as possible causes for the enhancement in hydrogen storage. Both hydrogen capacity in the carbon and mass diffusion within the matrix were improved.

  16. Electrochemical synthesis of alkali-intercalated iron selenide superconductors

    Science.gov (United States)

    Shen, Shi-Jie; Ying, Tian-Ping; Wang, Gang; Jin, Shi-Feng; Zhang, Han; Lin, Zhi-Ping; Chen, Xiao-Long

    2015-11-01

    Electrochemical method has been used to insert K/Na into FeSe lattice to prepare alkali-intercalated iron selenides at room temperature. Magnetization measurement reveals that KxFe2Se2 and NaxFe2Se2 are superconductive at 31 K and 46 K, respectively. This is the first successful report of obtaining metal-intercalated FeSe-based high-temperature superconductors using electrochemical method. It provides an effective route to synthesize metal-intercalated layered compounds for new superconductor exploration. Project supported by the National Natural Science Foundation of China (Grant Nos. 51322211and 91422303), the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07020100), Beijing Nova Program of China (Grant No. 2011096), and K. C. Wong Education Foundation, Hong Kong, China.

  17. Exfoliated graphite-ruthenium oxide composite electrodes for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Sagar; Lokesh, K.S.; Sampath, S. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012 (India)

    2008-12-01

    The performance of exfoliated graphite (EG)-ruthenium oxide (RuO{sub x}) composites as binderless electrodes is evaluated for electrochemical capacitors (ECs). A composite of EG-RuO{sub x} is prepared by a modified sol-gel process. The material is characterized using X-ray diffraction and microscopy. Electrochemical capacitors with the composite electrodes in the presence of aqueous sulfuric acid (H{sub 2}SO{sub 4}) electrolyte are evaluated using voltammetry, impedance and charge-discharge studies. Cyclic voltammetry reveals very stable current-voltage behaviour up to several thousands of cycles, as well as high specific capacitances, e.g., a few hundreds of farads per gram for the composite that contains 16.5 wt.% RuO{sub x}. (author)

  18. Exfoliated graphite-ruthenium oxide composite electrodes for electrochemical supercapacitors

    Science.gov (United States)

    Mitra, Sagar; Lokesh, K. S.; Sampath, S.

    The performance of exfoliated graphite (EG)-ruthenium oxide (RuO x) composites as binderless electrodes is evaluated for electrochemical capacitors (ECs). A composite of EG-RuO x is prepared by a modified sol-gel process. The material is characterized using X-ray diffraction and microscopy. Electrochemical capacitors with the composite electrodes in the presence of aqueous sulfuric acid (H 2SO 4) electrolyte are evaluated using voltammetry, impedance and charge-discharge studies. Cyclic voltammetry reveals very stable current-voltage behaviour up to several thousands of cycles, as well as high specific capacitances, e.g., a few hundreds of farads per gram for the composite that contains 16.5 wt.% RuO x.

  19. Dense high-aspect ratio 3D carbon pillars on interdigitated microelectrode arrays

    DEFF Research Database (Denmark)

    Amato, Letizia; Heiskanen, Arto; Hansen, Rasmus;

    2015-01-01

    In this work we present high-aspect ratio carbon pillars (1.4 μm in diameter and ∼11 μm in height) on top of interdigitated electrode arrays to be used for electrochemical applications. For this purpose, different types of 2D and 3D pyrolysed carbon structures were fabricated and characterised...... including surface- and microstructure, electrical and electrochemical properties. A pre-treatment of oxidised Si wafers is introduced to eliminate electrode delamination and ensure structure stability in water during long time-experiments. Additionally, a heat treatment method is reported for regeneration...

  20. Dendritic Heterojunction Nanowire Arrays for High-Performance Supercapacitors

    OpenAIRE

    Rujia Zou; Zhenyu Zhang; Muk Fung Yuen; Junqing Hu; Chun-Sing Lee; Wenjun Zhang

    2015-01-01

    Herein, we designed and synthesized for the first time a series of 3D dendritic heterojunction arrays on Ni foam substrates, with NiCo2S4 nanowires as cores and NiCo2O4, NiO, Co3O4, and MnO2 nanowires as branches, and studied systematically their electrochemical performance in comparison with their counterparts in core/shell structure. Attributed to the following reasons: (1) both core and branch are pseudocapacitively active materials, (2) the special dendritic structure with considerable in...

  1. Nanowire sensors and arrays for chemical/biomolecule detection

    Science.gov (United States)

    Yun, Minhee; Lee, Choonsup; Vasquez, Richard P.; Ramanathan, K.; Bangar, M. A.; Chen, W.; Mulchandan, A.; Myung, N. V.

    2005-01-01

    We report electrochemical growth of single nanowire based sensors using e-beam patterned electrolyte channels, potentially enabling the controlled fabrication of individually addressable high density arrays. The electrodeposition technique results in nanowires with controlled dimensions, positions, alignments, and chemical compositions. Using this technique, we have fabricated single palladium nanowires with diameters ranging between 75 nm and 300 nm and conducting polymer nanowires (polypyrrole and polyaniline) with diameters between 100 nm and 200 nm. Using these single nanowires, we have successfully demonstrated gas sensing with Pd nanowires and pH sensing with polypirrole nanowires.

  2. High damage tolerance of electrochemically lithiated silicon.

    Science.gov (United States)

    Wang, Xueju; Fan, Feifei; Wang, Jiangwei; Wang, Haoran; Tao, Siyu; Yang, Avery; Liu, Yang; Beng Chew, Huck; Mao, Scott X; Zhu, Ting; Xia, Shuman

    2015-01-01

    Mechanical degradation and resultant capacity fade in high-capacity electrode materials critically hinder their use in high-performance rechargeable batteries. Despite tremendous efforts devoted to the study of the electro-chemo-mechanical behaviours of high-capacity electrode materials, their fracture properties and mechanisms remain largely unknown. Here we report a nanomechanical study on the damage tolerance of electrochemically lithiated silicon. Our in situ transmission electron microscopy experiments reveal a striking contrast of brittle fracture in pristine silicon versus ductile tensile deformation in fully lithiated silicon. Quantitative fracture toughness measurements by nanoindentation show a rapid brittle-to-ductile transition of fracture as the lithium-to-silicon molar ratio is increased to above 1.5. Molecular dynamics simulations elucidate the mechanistic underpinnings of the brittle-to-ductile transition governed by atomic bonding and lithiation-induced toughening. Our results reveal the high damage tolerance in amorphous lithium-rich silicon alloys and have important implications for the development of durable rechargeable batteries. PMID:26400671

  3. Array Theory and Nial

    DEFF Research Database (Denmark)

    Falster, Peter; Jenkins, Michael

    1999-01-01

    This report is the result of collaboration between the authors during the first 8 months of 1999 when M. Jenkins was visiting professor at DTU. The report documents the development of a tool for the investigation of array theory concepts and in particular presents various approaches to choose pri...

  4. The Murchison Widefield Array

    NARCIS (Netherlands)

    Mitchell, Daniel A.; Greenhill, Lincoln J.; Ord, Stephen M.; Bernardi, Gianni

    2010-01-01

    It is shown that the excellent Murchison Radio-astronomy Observatory site allows the Murchison Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities and form images in the FM radio band. The techniques described are running autonomously in our calibration and imagin

  5. Cantilever array sensors

    Directory of Open Access Journals (Sweden)

    Hans Peter Lang

    2005-04-01

    Full Text Available Miniaturized microfabricated sensors have enormous potential in gas detection, biochemical analysis, medical applications, quality and process control, and product authenticity issues. Here, we highlight an ultrasensitive mechanical way of converting (bio-chemical or physical processes into a recordable signal using microfabricated cantilever arrays.

  6. Bandwidth Reconfigurable Metamaterial Arrays

    Directory of Open Access Journals (Sweden)

    Nathanael J. Smith

    2014-01-01

    Full Text Available Metamaterial structures provide innovative ways to manipulate electromagnetic wave responses to realize new applications. This paper presents a conformal wideband metamaterial array that achieves as much as 10 : 1 continuous bandwidth. This was done by using interelement coupling to concurrently achieve significant wave slow-down and cancel the inductance stemming from the ground plane. The corresponding equivalent circuit of the resulting array is the same as that of classic metamaterial structures. In this paper, we present a wideband Marchand-type balun with validation measurements demonstrating the metamaterial (MTM array’s bandwidth from 280 MHz to 2800 MHz. Bandwidth reconfiguration of this class of array is then demonstrated achieving a variety of band-pass or band-rejection responses within its original bandwidth. In contrast with previous bandwidth and frequency response reconfigurations, our approach does not change the aperture’s or ground plane’s geometry, nor does it introduce external filtering structures. Instead, the new responses are realized by making simple circuit changes into the balanced feed integrated with the wideband MTM array. A variety of circuit changes can be employed using MEMS switches or variable lumped loads within the feed and 5 example band-pass and band-rejection responses are presented. These demonstrate the potential of the MTM array’s reconfiguration to address a variety of responses.

  7. Anderson localization in metallic nanoparticle arrays

    CERN Document Server

    Mai, Zhijie; Pang, Wei; Xu, Haitao; Tan, Suiyan; Fu, Shenhe; Li, Yongyao

    2016-01-01

    Anderson localization has been observed in various types of waves, such as matter waves, optical waves and acoustic waves. Here we reveal that the effect of Anderson localization can be also induced in metallic nonlinear nanoparticle arrays excited by a random electrically driving field. We find that the dipole-induced nonlinearity results in ballistic expansion of dipole intensity during evolution; while the randomness of the external driving field can suppress such an expansion. Increasing the strength of randomness above the threshold value, a localized pattern of dipole intensity can be generated in the metallic nanoparticle arrays. By means of statistics, the mean intensity distribution of the dipoles reveals the formation of Anderson localization. We further show that the generated Anderson localization is highly confined, with its size down to the scale of incident wavelength. The reported results might facilitate the manipulations of electromagnetic fields in the scale of wavelength.

  8. Anderson localization in metallic nanoparticle arrays

    Science.gov (United States)

    Mai, Zhijie; Lin, Fang; Pang, Wei; Xu, Haitao; Tan, Suiyan; Fu, Shenhe; Li, Yongyao

    2016-06-01

    Anderson localization has been observed in various types of waves, such as matter waves, optical waves and acoustic waves. Here we reveal that the effect of Anderson localization can be also induced in metallic nonlinear nanoparticle arrays excited by a random electrically driving field. We find that the dipole-induced nonlinearity results in ballistic expansion of dipole intensity during evolution; while the randomness of the external driving field can suppress such an expansion. Increasing the strength of randomness above the threshold value, a localized pattern of dipole intensity can be generated in the metallic nanoparticle arrays. By means of statistics, the mean intensity distribution of the dipoles reveals the formation of Anderson localization. We further show that the generated Anderson localization is highly confined, with its size down to the scale of incident wavelength. The reported results might facilitate the manipulations of electromagnetic fields in the scale of wavelength.

  9. Glucose sensor using periodic nanostructured hybrid 1D Au/ZnO arrays

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Pil Ho, E-mail: pilho.huh@samsung.com [Samsung Electronics Co., Ltd. Nongseo-Dong, Giheung-Gu, Yongin-City, Gyeonggi-Do 446-711 (Korea, Republic of); Kim, Myunghwan [Samsung Electronics Co., Ltd. Nongseo-Dong, Giheung-Gu, Yongin-City, Gyeonggi-Do 446-711 (Korea, Republic of); Kim, Seong-Cheol, E-mail: sckim07@ynu.ac.kr [School of Textiles, Yeungnam University, Gyeungsan Gyeungbuk 712-749 (Korea, Republic of)

    2012-07-01

    Hybrid 1D nanostructured Au/ZnO arrays were created by heat treatment of a spin-coated zinc acetate-PVA-Au(III) layer on surface relief grating and functioned as an electrochemical and optical D(+)-glucose sensor due to electrochemical oxidation between hybrid nanostructures and D(+)-glucose. The morphology and chemical composition of 1D Au/ZnO hybrid arrays were characterized by means of AFM, SEM, EDAX, and XPS. Electrochemical and optical sensitivities by the addition of D(+)-glucoses on 1D Au/ZnO arrays were investigated using Cyclic voltammetry and UV-vis-NIR spectra in the medical concentration ranges of 0.5, 2.0, and 8.0 mM. - Highlights: Black-Right-Pointing-Pointer Zinc acetate-PVA-Au(III) composites were prepared by simply mixing zinc acetate-PVA and gold(III) chloride trihydrate. Black-Right-Pointing-Pointer Hybrid 1D nanostructured Au/ZnO arrays were easily fabricated using surface relief gratings without additional process steps. Black-Right-Pointing-Pointer Redox and optical sensor to detect D(+)-glucoses.

  10. Glucose sensor using periodic nanostructured hybrid 1D Au/ZnO arrays

    International Nuclear Information System (INIS)

    Hybrid 1D nanostructured Au/ZnO arrays were created by heat treatment of a spin-coated zinc acetate-PVA-Au(III) layer on surface relief grating and functioned as an electrochemical and optical D(+)-glucose sensor due to electrochemical oxidation between hybrid nanostructures and D(+)-glucose. The morphology and chemical composition of 1D Au/ZnO hybrid arrays were characterized by means of AFM, SEM, EDAX, and XPS. Electrochemical and optical sensitivities by the addition of D(+)-glucoses on 1D Au/ZnO arrays were investigated using Cyclic voltammetry and UV–vis-NIR spectra in the medical concentration ranges of 0.5, 2.0, and 8.0 mM. - Highlights: ► Zinc acetate-PVA-Au(III) composites were prepared by simply mixing zinc acetate-PVA and gold(III) chloride trihydrate. ► Hybrid 1D nanostructured Au/ZnO arrays were easily fabricated using surface relief gratings without additional process steps. ► Redox and optical sensor to detect D(+)-glucoses.

  11. High-frequency synthetic ultrasound array incorporating an actuator

    Science.gov (United States)

    Ritter, Timothy A.; Shrout, Thomas R.; Shung, K. Kirk

    2001-05-01

    Ultrasound imaging at frequencies above 20 MHz relies almost exclusively on single-element transducers. IN order to apply array technology at these frequencies, several practical problems must be solved, including spatial scale and fabrication limitations, low device capacitance, and lack of a hardware beamformer. One method of circumventing these problems is to combine an array, an actuator, and a synthetic aperture software beamformer. The array can use relatively wide elements spaced on a coarse pitch. The actuator is used to move the array in short steps (less than the element pitch), and pulse-echo data is acquired at intermediate sample positions. The synthetic aperture beamformer reconstructs the image from the pulse-echo data. A 50 MHz example is analyzed in detail. Estimates of signal-to-noise reveal performance comparable to a standard phased array; furthermore, the actuated array requires half the number of elements, the elements are 8x wider, and only one channel is required. Simulated three-dimensional point spread functions demonstrate side lobe levels approaching - 40dB and main beam widths of 50 to 100 microns. A 50 MHz piezo-composite array design has been tested which displays experimental bandwidth of 70% while maintaining high sensitivity. Individual composite sub-elements are 18 microns wide. Once this array is integrated with a suitable actuator, it is anticipated that a tractable method of imaging with high frequency arrays will result.

  12. The Allen Telescope Array

    Science.gov (United States)

    Bower, Geoffrey C.; Allen Telescope Array Team

    2010-01-01

    The ATA is a 42-element centimeter wavelength array located in Hat Creek, California and jointly operated by UC Berkeley Radio Astronomy Laboratory and the SETI Institute. Since the ATA dedication in Fall 2007, activities have been focused on commissioning the array, retrofitting a handful of components including the feed, developing an operations model, creation of pipeline processing for correlator imaging data, early science observations, and launching of the major surveys for which the telescope was built. The retrofit of the feed improves feed mechanical robustness as well as high frequency performance. Science programs launched include imaging radio transient and static sky surveys (ATATS and PiGSS), commensal SETI and transient surveys of the Galactic Center, targeted SETI observations of nearby stars, the Fly's Eye transient survey, broadband spectra of nearby star-forming galaxies, polarimetric observations of bright radio sources, observations of hydrogen in nearby galaxies and galaxy groups, molecular line observations in the Galaxy, and observations of Jupiter and the Moon. The baseline Square Kilometer Array (SKA) design, a large-N-small-diameter (LNSD) array with wide-band single-pixel feeds and an offset Gregorian antenna, bears a strong resemblance to the ATA. Additional ATA contributions to the SKA include configuration studies for LNSD arrays, the use of fiber optics for broadband data transmission, the use of flexible FPGA-based digital electronics, passive cooling of antennas, and implementation of commensal observing modes. The ATA is currently used for exploration of calibration and imaging algorithms necessary for the SKA. I will summarize current technical status and performance, the results from early science and surveys, and ATA contributions to SKA development.

  13. Encyclopedia of electrochemistry. Vol. 5. Electrochemical engineering

    Energy Technology Data Exchange (ETDEWEB)

    Bard, A.J. [Texas Univ., Austin, TX (United States). Dept. of Chemistry; Stratmann, M. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany); Macdonald, D. [Pennsylvania State Univ., University Park, PA (United States). Center for Electrochemical Science and Engineering; Schmuki, P. (eds.) [Erlangen-Nuernberg Univ., Erlangen (Germany). Dept. of Material Science

    2007-07-01

    This volume contains the following chapters: 1. Technical scale of electrochemistry; 2. Electrocatalysis; 3. Electrochemical composition; 4. Electrowinning of metals; 5. Electrowinning of other inorganic compounds; 6. Electrochemistry applied to organic synthesis: Principles and main achievements; 7. Batteries: Basic principles, technologies, and modeling; 8. Fuel cells; 9. The electrochemistry of nuclear reactor coolant circuits; 10. Electrochemical techniques for studying high-temperature subcritical and supercritical aqueous solutions; 11. Electrochemistry of silicon etching; 12. Electrochemical machining; 13. Environmental chemistry.

  14. Fabrication of Micro Components by Electrochemical Deposition

    DEFF Research Database (Denmark)

    Tang, Peter Torben

    The main issue of this thesis is the combination of electrochemical deposition of metals and micro machining. Processes for electroplating and electroless plating of nickel and nickel alloys have been developed and optimised for compatibility with microelectronics and silicon based micromechanics...... of electrochemical machining and traditional machining is compared to micro machining techniques as performed in the field of microelectronics. Various practical solutions and equipment for electrochemical deposition of micro components are demonstrated, as well as the use and experience obtained utilising...

  15. Electrochemical components employing polysiloxane-derived binders

    Science.gov (United States)

    Delnick, Frank M.

    2013-06-11

    A processed polysiloxane resin binder for use in electrochemical components and the method for fabricating components with the binder. The binder comprises processed polysiloxane resin that is partially oxidized and retains some of its methyl groups following partial oxidation. The binder is suitable for use in electrodes of various types, separators in electrochemical devices, primary lithium batteries, electrolytic capacitors, electrochemical capacitors, fuel cells and sensors.

  16. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  17. Working electrode holder and electrochemical cell

    DEFF Research Database (Denmark)

    2016-01-01

    The present disclosure relates to a holder for a test object, more specifically to a holder for measuring electrochemical properties of the test object. One embodiment relates to a working electrode holder for measuring electrochemical properties of a front surface of a test object in a liquid...... in the bottom surface and configured for passage of said liquid, such that liquid is able to pass onto the electrically contacted front surface. The holder may be used in an electrochemical cell....

  18. Plasmonic silver nanoparticles loaded titania nanotube arrays exhibiting enhanced photoelectrochemical and photocatalytic activities

    Science.gov (United States)

    Nishanthi, S. T.; Iyyapushpam, S.; Sundarakannan, B.; Subramanian, E.; Pathinettam Padiyan, D.

    2015-01-01

    A combination of electrochemical anodization and photochemical reduction is employed to fabricate highly ordered silver loaded titania nanotubes (Ag/TNT) arrays. The Ag/TNT samples show an extended optical absorbance from UV to visible region owing to the surface plasmon resonance effect of Ag. The photoluminescence intensity of Ag/TNT is significantly lower than that of pure titania revealing a decrease in charge carrier recombination. The photoelectrochemical properties of the prepared samples are studied using linear sweep and transient photocurrent measurements. Compared with pure TNT, the Ag loaded samples show a higher photoelectrochemical activity. The results demonstrate an efficient separation of photogenerated electron-hole pairs and the consequent increase in lifetime of charge carriers by Ag/TNT. The photocatalytic results of methyl orange dye degradation show that the Ag/TNT-3-05 sample exhibits the maximum degradation efficiency of 98.85% with kinetic rate constant of 0.0236(5) min-1 for 180 min light illumination.

  19. Properties of plasmonic arrays produced by pulsed-laser nanostructuring of thin Au films

    Directory of Open Access Journals (Sweden)

    Katarzyna Grochowska

    2014-11-01

    Full Text Available A brief description of research advances in the area of short-pulse-laser nanostructuring of thin Au films is followed by examples of experimental data and a discussion of our results on the characterization of structural and optical properties of gold nanostructures. These consist of partially spherical or spheroidal nanoparticles (NPs which have a size distribution (80 ± 42 nm and self-organization characterized by a short-distance order (length scale ≈140 nm. For the NP shapes produced, an observably broader tuning range (of about 150 nm of the surface plasmon resonance (SPR band is obtained by renewal thin film deposition and laser annealing of the NP array. Despite the broadened SPR bands, which indicate damping confirmed by short dephasing times not exceeding 4 fs, the self-organized Au NP structures reveal quite a strong enhancement of the optical signal. This was consistent with the near-field modeling and micro-Raman measurements as well as a test of the electrochemical sensing capability.

  20. Enhanced photoelectrochemical water splitting from Si quantum dots/TiO{sub 2} nanotube arrays composite electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhong [Department of Materials Science, Fudan University, Shanghai 200433 (China); Cui, Xiaoli, E-mail: xiaolicui@fudan.edu.cn [Department of Materials Science, Fudan University, Shanghai 200433 (China); Hao, Hongchen; Lu, Ming [Department of Optical Science and Engineering, and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University, Shanghai 200433 (China); Lin, Yuehe [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164-2920 (United States)

    2015-06-15

    Graphical abstract: Si quantum dots were firstly applied to modify TiO{sub 2} nanotubes and enhanced visible light response was demonstrated for the resulted Si QDs/TiO{sub 2} nanocomposite. Si QDs are promising in photoelectrochemical water splitting and photocatalysis since their low cost, abundance and environmentally-friendliness. - Highlights: • A novel nanocomposite Si QDs/TiO{sub 2} nanotubes was fabricated and characterized. • Enhanced photoelectrochemical water splitting was firstly demonstrated for Si QDs/TiO{sub 2}. • The visible light response of TiO{sub 2} increased with the presence of Si QDs. - Abstract: This work firstly introduced Si quantum dots (QDs) to modify TiO{sub 2} nanotube arrays for photoelectrochemical water splitting. A systematic study using surface and optical characterization tools reveals the nature of the combination of Si QDs and TiO{sub 2} nanotube arrays. Scanning electron microscopy and X-ray photoelectron spectroscopy results show that Si QDs were assembled on the surface of vertically aligned TiO{sub 2} nanotube arrays. The UV–vis diffuse reflectance spectra indicate the improved visible light absorbance. The enhanced photoelectrochemical water splitting was demonstrated under visible light illumination and the photocurrent density was 1.6 times larger than that of pristine TiO{sub 2} electrodes. Electrochemical impedance behavior was measured for the electrodes and the impedance is slightly reduced for the nanocomposite electrode with the presence of Si QDs. This work demonstrated that Si QDs would be a novel and effective choice for improving the utilization of visible light for TiO{sub 2} nanotubes.

  1. Towards Truly Boolean Arrays in Data-Parallel Array Processing

    NARCIS (Netherlands)

    C. Grelck; H. Luyat

    2013-01-01

    We investigate several dense bit-wise implementations of Boolean arrays in the context of the functional data-parallel array programming language SAC. A particular problem arises in compiler or directive based parallelisation as the scheduling of loops over Boolean arrays is unaware of the restricte

  2. Woven electrochemical fabric-based test sensors (WEFTS): a new class of multiplexed electrochemical sensors.

    Science.gov (United States)

    Choudhary, Tripurari; Rajamanickam, G P; Dendukuri, Dhananjaya

    2015-05-01

    We present textile weaving as a new technique for the manufacture of miniature electrochemical sensors with significant advantages over current fabrication techniques. Biocompatible silk yarn is used as the material for fabrication instead of plastics and ceramics used in commercial sensors. Silk yarns are coated with conducting inks and reagents before being handloom-woven as electrodes into patches of fabric to create arrays of sensors, which are then laminated, cut and packaged into individual sensors. Unlike the conventionally used screen-printing, which results in wastage of reagents, yarn coating uses only as much reagent and ink as required. Hydrophilic and hydrophobic yarns are used for patterning so that sample flow is restricted to a small area of the sensor. This simple fluidic control is achieved with readily available materials. We have fabricated and validated individual sensors for glucose and hemoglobin and a multiplexed sensor, which can detect both analytes. Chronoamperometry and differential pulse voltammetry (DPV) were used to detect glucose and hemoglobin, respectively. Industrial quantities of these sensors can be fabricated at distributed locations in the developing world using existing skills and manufacturing facilities. We believe such sensors could find applications in the emerging area of wearable sensors for chemical testing. PMID:25805000

  3. Nanostructured micro-electrode arrays for electrophysiological measurements

    DEFF Research Database (Denmark)

    Wierzbicki, Rafal Dominik

    Potential and electrochemical measurements of biological cell electroactivity is crucial in cell biology research. The traditional technique with a micrometer-sharp glass pipette equipped with a metal wire within its core or electrically conductive saline solution allows extracellular, ion......-channel and intracellular measurements. In applications that require multichannel measurements, this approach is, however, impractical and planar arrays of metal electrodes are usually employed. Yet, with planar geometry, they allow extracellular measurements only. Several approaches to developing functional three......-dimensional electrode arrays with features able to penetrate cell membrane are currently investigated by various groups. While a number of experimental setups have been recently developed, the question remains whether the nanostructure is in fact penetrating the cellular membrane, and if the measurements are indeed...

  4. Preparation of Multi-Walled Carbon Nanotube/Amino-Terminated Ionic Liquid Arrays and Their Electrocatalysis towards Oxygen Reduction

    OpenAIRE

    Li Niu; Ari Ivaska; Carita Kvarnström; Rose-Marie Latonen; Zhijuan Wang

    2010-01-01

    Arrays of aligned multi-walled carbon nanotube-ionic liquid (MIL) were assembled on silicon wafers (Si-MIL). Formation of Si-MIL was confirmed by ATR-FTIR, AFM and Raman techniques. The electrochemical measurements indicated that Si-MIL showed good electrocatalysis towards oxygen reduction compared with MIL drop-cast on a glassy carbon electrode.

  5. Concurrent array-based queue

    Energy Technology Data Exchange (ETDEWEB)

    Heidelberger, Philip; Steinmacher-Burow, Burkhard

    2015-01-06

    According to one embodiment, a method for implementing an array-based queue in memory of a memory system that includes a controller includes configuring, in the memory, metadata of the array-based queue. The configuring comprises defining, in metadata, an array start location in the memory for the array-based queue, defining, in the metadata, an array size for the array-based queue, defining, in the metadata, a queue top for the array-based queue and defining, in the metadata, a queue bottom for the array-based queue. The method also includes the controller serving a request for an operation on the queue, the request providing the location in the memory of the metadata of the queue.

  6. Orientation selectivity in a multi-gated organic electrochemical transistor

    Science.gov (United States)

    Gkoupidenis, Paschalis; Koutsouras, Dimitrios A.; Lonjaret, Thomas; Fairfield, Jessamyn A.; Malliaras, George G.

    2016-06-01

    Neuromorphic devices offer promising computational paradigms that transcend the limitations of conventional technologies. A prominent example, inspired by the workings of the brain, is spatiotemporal information processing. Here we demonstrate orientation selectivity, a spatiotemporal processing function of the visual cortex, using a poly(3,4ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) organic electrochemical transistor with multiple gates. Spatially distributed inputs on a gate electrode array are found to correlate with the output of the transistor, leading to the ability to discriminate between different stimuli orientations. The demonstration of spatiotemporal processing in an organic electronic device paves the way for neuromorphic devices with new form factors and a facile interface with biology.

  7. Radar techniques using array antennas

    CERN Document Server

    Wirth, Wulf-Dieter

    2013-01-01

    Radar Techniques Using Array Antennas is a thorough introduction to the possibilities of radar technology based on electronic steerable and active array antennas. Topics covered include array signal processing, array calibration, adaptive digital beamforming, adaptive monopulse, superresolution, pulse compression, sequential detection, target detection with long pulse series, space-time adaptive processing (STAP), moving target detection using synthetic aperture radar (SAR), target imaging, energy management and system parameter relations. The discussed methods are confirmed by simulation stud

  8. Electrochemical techniques for subsecond neurotransmitter detection in live rodents.

    Science.gov (United States)

    Hascup, Kevin N; Hascup, Erin R

    2014-08-01

    Alterations in neurotransmission have been implicated in numerous neurodegenerative and neuropsychiatric disorders, including Alzheimer disease, Parkinson disease, epilepsy, and schizophrenia. Unfortunately, few techniques support the measurement of real-time changes in neurotransmitter levels over multiple days, as is essential for ethologic and pharmacodynamic testing. Microdialysis is commonly used for these research paradigms, but its poor temporal and spatial resolution make this technique inadequate for measuring the rapid dynamics (milliseconds to seconds) of fast signaling neurotransmitters, such as glutamate and acetylcholine. Enzymatic microelectrode arrays (biosensors) coupled with electrochemical recording techniques have demonstrated fast temporal resolution (less than 1 s), excellent spatial resolution (micron-scale), low detection limits (≤200 nM), and minimal damage (50 to 100 μm) to surrounding brain tissue. Here we discuss the benefits, methods, and animal welfare considerations of using platinum microelectrodes on a ceramic substrate for enzyme-based electrochemical recording techniques for real-time in vivo neurotransmitter recordings in both anesthetized and awake, freely moving rodents.

  9. OPTIMIZATION OF ELECTROCHEMICAL MACHINING PROCESS PARAMETERS USING TAGUCHI APPROACH

    Directory of Open Access Journals (Sweden)

    R.Goswami

    2013-05-01

    Full Text Available this research paper, Taguchi method is applied to find optimum process parameters for Electrochemical machining (ECM. The objective of experimental investigation is to conduct research of machining parameters impact on MRR and SR of work piece of Aluminum and Mild steel . The approach was based on Taguchi’s method, analysis of variance and signal to noise ratio (S/N Ratio to optimize the Electrochemical machining process parameters for effective machining and to predict the optimal choice for each ECM parameter such asvoltage, tool feed and current. In this research three level of parameter is considered for experiment. There is L9 orthogonal array used by varying A,B,C respectively and for each combination we have conducted three experiments and with the help of Signal to Noise ratio we find out the optimum results for ECM. It was confirmed that determined optimal combination of ECM process parameters satisfy the real need for machining of Aluminum and Mild steel in actual practice.

  10. PARAMETRIC OPTIMIZATION IN ELECTROCHEMICAL MACHINING USING UTILITY BASED TAGUCHI METHOD

    Directory of Open Access Journals (Sweden)

    SADINENI RAMA RAO

    2015-01-01

    Full Text Available The present work deals the application of Taguchi method with utility concept to optimize the machining parameters with multiple characteristics in electrochemical machining (ECM of Al/B4C composites. L27 orthogonal array was chosen for the experiments. METATECH ECM setup is used to conduct the experiments. The ECM machining parameters namely applied voltage, electrolyte concentration, electrode feed rate and percentage of reinforcement are optimized based on multiple responses, i.e., material removal rate, surface roughness and radial over cut. The optimum machining parameters are calculated by using utility concept and results are compared with ANOVA. The results show that the feed rate is the most influencing parameter which affects the multiple machining characteristics simultaneously. The optimum parametric combination to maximize the material removal rate and to minimize surface roughness and radial over cut simultaneously are, applied voltage 16 V, feed rate 1.0 mm/min, electrolyte concentration 30 g/L and reinforcement content 5 wt%. Experimental results show that the responses in electrochemical machining process can be improved through this approach.

  11. Timed arrays wideband and time varying antenna arrays

    CERN Document Server

    Haupt, Randy L

    2015-01-01

    Introduces timed arrays and design approaches to meet the new high performance standards The author concentrates on any aspect of an antenna array that must be viewed from a time perspective. The first chapters briefly introduce antenna arrays and explain the difference between phased and timed arrays. Since timed arrays are designed for realistic time-varying signals and scenarios, the book also reviews wideband signals, baseband and passband RF signals, polarization and signal bandwidth. Other topics covered include time domain, mutual coupling, wideband elements, and dispersion. The auth

  12. Electrochemical approaches for chemical and biological analysis on Mars

    Science.gov (United States)

    Kounaves, Samuel P.

    2003-01-01

    Obtaining in situ chemical data from planetary bodies such as Mars or Europa can present significant challenges. The one analytical technique that has many of the requisite characteristics to meet such a challenge is electroanalysis. Described here are three electroanalytical devices designed for in situ geochemical and biological analysis on Mars. The Mars Environmental Compatibility Assessment (MECA) was built and flight qualified for the now cancelled NASA Mars 2001 Lander. Part of MECA consisted of four "cells" containing arrays of electrochemical based sensors for measuring the ionic species in soil samples. A next-generation MECA, the Robotic Chemical Analysis Laboratory (RCAL), uses a carousel-type system to allow for greater customization of analytical procedures. A second instrument, proposed as part of the 2007 CryoScout mission, consists of a flow-through inorganic chemical analyzer (MICA). CryoScout is a torpedo-like device designed for subsurface investigation of the stratigraphic climate record embedded in Mars' north polar cap. As the CryoScout melts its way through the ice cap, MICA will collect and analyze the meltwater for a variety of inorganics and chemical parameters. By analyzing the chemistry locked in the layers of dust, salt, and ice, geologists will be able to determine the recent history of climate, water, and atmosphere on Mars and link it to the past. Finally, electroanalysis shows its abilities in the detection of possible microorganism on Mars or elsewhere in the solar system. To identify an unknown microorganism, one that may not even use Earth-type biochemistry, requires a detection scheme which makes minimal assumptions and looks for the most general features. Recent work has demonstrated that the use of an array of electrochemical sensors which monitors the changes in a solution via electrical conductivity, pH, and ion selective electrodes, can be used to detect minute chemical perturbations caused by the growth of bacteria and

  13. A new two-dimensional experimental apparatus for electrochemical remediation processes☆

    Institute of Scientific and Technical Information of China (English)

    Yingying Gu; Rongbing Fu; Hongjiang Li; Hui An

    2015-01-01

    Electrochemical extraction of contaminants from soils is a promising soil decontamination technology. Various experiments have been conducted to study electrochemical reactions and geochemical processes in the electro-chemical extraction using different experimental apparatuses. This paper presents the development of a new closed two-dimensional (2D) apparatus that can better simulate the field application of the technology and ac-curately monitor the most important electrochemical parameters to understand the process. The innovative fea-tures of the new apparatus include the outer and inner electrodes designed to apply a non-uniform electrical field across the specimen as in the field electrochemical remediation process, the probes installed to measure the 2D distribution of electrical voltage, and the gas and fluid volume measurement devices used to accurately monitor the gas generation and electroosmotic flow rates at both electrodes as a function of time. The components of this new apparatus and the features of each component are described. The operating procedure and some typical re-sults from three experiments with the apparatus are demonstrated. The results show that the variation of the gas generation rate is in good agreement with the electric current. Their relation provides a valid evaluation for elec-trochemical behavior of the system and Faraday's laws of electrolysis. The 2D profiles of cadmium concentration and voltage distribution at the end of the experiment reveal the great effects of a non-uniform electrical field on the contaminant mobilization.

  14. Carbon Nanomaterials Based Electrochemical Sensors/Biosensors for the Sensitive Detection of Pharmaceutical and Biological Compounds

    Directory of Open Access Journals (Sweden)

    Bal-Ram Adhikari

    2015-09-01

    Full Text Available Electrochemical sensors and biosensors have attracted considerable attention for the sensitive detection of a variety of biological and pharmaceutical compounds. Since the discovery of carbon-based nanomaterials, including carbon nanotubes, C60 and graphene, they have garnered tremendous interest for their potential in the design of high-performance electrochemical sensor platforms due to their exceptional thermal, mechanical, electronic, and catalytic properties. Carbon nanomaterial-based electrochemical sensors have been employed for the detection of various analytes with rapid electron transfer kinetics. This feature article focuses on the recent design and use of carbon nanomaterials, primarily single-walled carbon nanotubes (SWCNTs, reduced graphene oxide (rGO, SWCNTs-rGO, Au nanoparticle-rGO nanocomposites, and buckypaper as sensing materials for the electrochemical detection of some representative biological and pharmaceutical compounds such as methylglyoxal, acetaminophen, valacyclovir, β-nicotinamide adenine dinucleotide hydrate (NADH, and glucose. Furthermore, the electrochemical performance of SWCNTs, rGO, and SWCNT-rGO for the detection of acetaminophen and valacyclovir was comparatively studied, revealing that SWCNT-rGO nanocomposites possess excellent electrocatalytic activity in comparison to individual SWCNT and rGO platforms. The sensitive, reliable and rapid analysis of critical disease biomarkers and globally emerging pharmaceutical compounds at carbon nanomaterials based electrochemical sensor platforms may enable an extensive range of applications in preemptive medical diagnostics.

  15. Carbon Nanomaterials Based Electrochemical Sensors/Biosensors for the Sensitive Detection of Pharmaceutical and Biological Compounds.

    Science.gov (United States)

    Adhikari, Bal-Ram; Govindhan, Maduraiveeran; Chen, Aicheng

    2015-01-01

    Electrochemical sensors and biosensors have attracted considerable attention for the sensitive detection of a variety of biological and pharmaceutical compounds. Since the discovery of carbon-based nanomaterials, including carbon nanotubes, C60 and graphene, they have garnered tremendous interest for their potential in the design of high-performance electrochemical sensor platforms due to their exceptional thermal, mechanical, electronic, and catalytic properties. Carbon nanomaterial-based electrochemical sensors have been employed for the detection of various analytes with rapid electron transfer kinetics. This feature article focuses on the recent design and use of carbon nanomaterials, primarily single-walled carbon nanotubes (SWCNTs), reduced graphene oxide (rGO), SWCNTs-rGO, Au nanoparticle-rGO nanocomposites, and buckypaper as sensing materials for the electrochemical detection of some representative biological and pharmaceutical compounds such as methylglyoxal, acetaminophen, valacyclovir, β-nicotinamide adenine dinucleotide hydrate (NADH), and glucose. Furthermore, the electrochemical performance of SWCNTs, rGO, and SWCNT-rGO for the detection of acetaminophen and valacyclovir was comparatively studied, revealing that SWCNT-rGO nanocomposites possess excellent electrocatalytic activity in comparison to individual SWCNT and rGO platforms. The sensitive, reliable and rapid analysis of critical disease biomarkers and globally emerging pharmaceutical compounds at carbon nanomaterials based electrochemical sensor platforms may enable an extensive range of applications in preemptive medical diagnostics. PMID:26404304

  16. Morphological and electrochemical cycling effects in MnO2 nanostructures by 3D electron tomography

    KAUST Repository

    Chen, Wei

    2014-02-12

    In this study, MnO2 nanostructures with well-controlled morphology and crystal phase are successfully prepared by chemical synthesis, and characterized by three-dimensional electron tomography for use as supercapacitor electrode materials. The growth process of the various MnO 2 nanostructures is revealed in detail, and correlated to their electrochemical performance as supercapacitor materials. The specific capacitance of MnO2 electrodes is found to be strongly correlated with the inner morphology and crystal phase of the MnO2 nanostructures. Furthermore, it is demonstrated that the increased capacity with electrochemical cycling of the materials is due to the formation of defective regions embedded in the MnO2 nanostructures; these regions form during electrochemical cycling of the electrodes, resulting in increased porosity, surface area, and consequently, increased electrochemical capacity. The preparation, characterization and supercapacitor application of MnO 2 nanostructures by 3D electron tomography are studied. The electrochemical performance of MnO2 is correlated to its surface area, determined by the morphological effect, as well as the cycling effect, determined by the formation of defective regions on the nanostructures during electrochemical cycling tests. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Microreactor Array Device

    Science.gov (United States)

    Wiktor, Peter; Brunner, Al; Kahn, Peter; Qiu, Ji; Magee, Mitch; Bian, Xiaofang; Karthikeyan, Kailash; Labaer, Joshua

    2015-03-01

    We report a device to fill an array of small chemical reaction chambers (microreactors) with reagent and then seal them using pressurized viscous liquid acting through a flexible membrane. The device enables multiple, independent chemical reactions involving free floating intermediate molecules without interference from neighboring reactions or external environments. The device is validated by protein expressed in situ directly from DNA in a microarray of ~10,000 spots with no diffusion during three hours incubation. Using the device to probe for an autoantibody cancer biomarker in blood serum sample gave five times higher signal to background ratio compared to standard protein microarray expressed on a flat microscope slide. Physical design principles to effectively fill the array of microreactors with reagent and experimental results of alternate methods for sealing the microreactors are presented.

  18. Mediated electrochemical hazardous waste destruction

    International Nuclear Information System (INIS)

    There are few permitted processes for mixed waste (radioactive plus chemically hazardous) treatment. We are developing an electrochemical process, based upon mediated electrochemical oxidation (MEO), that converts toxic organic components of mixed waste to water, carbon dioxide, and chloride or chloride precipitates. Aggressive oxidizer ions such as Ag2+, Co3+, or Fe3+ are produced at an anode. These can attack organic molecules directly, and may also produce hydroxyl free radicals that promote destruction. Solid and liquid radioactive waste streams containing only inorganic radionuclide forms may be treated with existing technology and prepared for final disposal. The coulombic efficiency of the process has been determined, as well as the destruction efficiency for ethylene glycol, a surrogate waste. In addition, hazardous organic materials are becoming very expensive to dispose of and when they are combined with transuranic radioactive elements no processes are presently permitted. Mediated electrochemical oxidation is an ambient- temperature aqueous-phase process that can be used to oxidize organic components of mixed wastes. Problems associated with incineration, such as high-temperature volatilization of radionuclides, are avoided. Historically, Ag(II) has been used as a mediator in this process. Fe(III) and Co(III) are attractive alternatives to Ag(II) since they form soluble chlorides during the destruction of chlorinated solvents. Furthermore, silver itself is toxic heavy metal. Quantitative data have been obtained for the complete oxidation of ethylene glycol by Fe(III) and Co(III). Though ethylene glycol is a nonhalogenated organic, these data have enabled us to make direct comparisons of activities of Fe(III) and Co(III) with Ag(II). Very good quantitative data for the oxidation of ethylene glycol by Ag(II) had already been collected

  19. Electrochemical performance of alloys Ho_5Fe_3Co_(12) and Ho_(33.3)Co_(66.7)

    Institute of Scientific and Technical Information of China (English)

    赵允红; 何维; 张永志; 曾令民

    2010-01-01

    Alloys with composition Ho5Fe3Co12 and Ho33.3Co66.7 were prepared and examined by X-ray diffractometer and automatic battery testing instrument. The electrochemical properties of these alloys such as discharge capacity, cycling performance and high rate dischargeability were investigated by battery testing instruments in alkaline electrolyte. A comparison of the electrochemical performance of the Ho5Fe3Co12 and Ho33.3Co66.7 alloys revealed that alloy Ho5Fe3Co12 possessed a better electrochemical performance...

  20. Modeling steady-state experiments with a scanning electrochemical microscope involving several independent diffusing species using the boundary element method.

    Science.gov (United States)

    Sklyar, Oleg; Träuble, Markus; Zhao, Chuan; Wittstock, Gunther

    2006-08-17

    The BEM algorithm developed earlier for steady-state experiments in the scanning electrochemical microscopy (SECM) feedback mode has been expanded to allow for the treatment of more than one independently diffusing species. This allows the treatment of substrate-generation/tip-collection SECM experiments. The simulations revealed the interrelation of sample layout, local kinetics, imaging conditions, and the quality of the obtained SECM images. Resolution in the SECM SG/TC images has been evaluated, and it depends on several factors. For most practical situations, the resolution is limited by the diffusion profiles of the sample. When a dissolved compound is converted at the sample (e.g., oxygen reduction or enzymatic reaction at the sample), the working distance should be significantly larger than in SECM feedback experiments (ca. 3 r(T) for RG = 5) in order to avoid diffusional shielding of the active regions on the sample by the UME body. The resolution ability also depends on the kinetics of the active regions. The best resolution can be expected if all the active regions cause the same flux. In one simulated example, which might mimic a possible scenario of a low-density protein array, considerable compromises in the resolving power, were noted when the flux from two neighboring spots differs by more than a factor of 2. PMID:16898739

  1. The Submillimeter Array Polarimeter

    OpenAIRE

    Marrone, Daniel P.; Rao, Ramprasad

    2008-01-01

    We describe the Submillimeter Array (SMA) Polarimeter, a polarization converter and feed multiplexer installed on the SMA. The polarimeter uses narrow-band quarter-wave plates to generate circular polarization sensitivity from the linearly-polarized SMA feeds. The wave plates are mounted in rotation stages under computer control so that the polarization handedness of each antenna is rapidly selectable. Positioning of the wave plates is found to be highly repeatable, better than 0.2 degrees. A...

  2. The Murchison Widefield Array

    CERN Document Server

    Mitchell, Daniel A; Ord, Stephen M; Bernardi, Gianni; Wayth, Randall B; Edgar, Richard G; Clark, Michael A; Dal, Kevin; Pfister, Hanspeter; Gleadow, Stewart J; Arcus, W; Briggs, F H; Benkevitch, L; Bowman, J D; Bunton, J D; Burns, S; Cappallo, R J; Corey, B E; de Oliveira-Costa, A; Desouza, L; Doeleman, S S; Derome, M F; Emrich, D; Glossop, M; Goeke, R; Krishna, M R Gopala; Hazelton, B; Herne, D E; Hewitt, J N; Kamini, P A; Kaplan, D L; Kasper, J C; Kincaid, B B; Kocz, J; Kowald, E; Kratzenberg, E; Kumar, D; Lonsdale, C J; Lynch, M J; Madhavi, S; Matejek, M; McWhirter, S R; Morales, M F; Morgan, E; Oberoi, D; Pathikulangara, J; Prabu, T; Rogers, A; Salah, J E; Sault, R J; Shankar, N Udaya; Srivani, K S; Stevens, J; Tingay, S J; Vaccarella, A; Waterson, M; Webster, R L; Whitney, A R; Williams, A; Williams, C

    2010-01-01

    It is shown that the excellent Murchison Radio-astronomy Observatory site allows the Murchison Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities and form images in the FM radio band. The techniques described are running autonomously in our calibration and imaging software, which is currently being used to process an FM-band survey of the entire southern sky.

  3. The Cherenkov Telescope Array

    OpenAIRE

    Bigongiari, Ciro

    2016-01-01

    The Cherenkov Telescope Array (CTA) is planned to be the next generation ground based observatory for very high energy (VHE) gamma-ray astronomy. Gamma-rays provide a powerful insight into the non-thermal universe and hopefully a unique probe for new physics. Imaging Cherenkov telescopes have already discovered more than 170 VHE gamma-ray emitters providing plentiful of valuable data and clearly demonstrating the power of this technique. In spite of the impressive results there are indication...

  4. Solar collector array

    Science.gov (United States)

    Hall, John Champlin; Martins, Guy Lawrence

    2015-09-06

    A method and apparatus for efficient manufacture, assembly and production of solar energy. In one aspect, the apparatus may include a number of modular solar receiver assemblies that may be separately manufactured, assembled and individually inserted into a solar collector array housing shaped to receive a plurality of solar receivers. The housing may include optical elements for focusing light onto the individual receivers, and a circuit for electrically connecting the solar receivers.

  5. Supersymetric laser arrays

    OpenAIRE

    El-Ganainy, Ramy; Ge, Li; Khajavikhan, Mercedeh; Christodoulides, Demetrios

    2015-01-01

    We introduce the concept of supersymmetric laser arrays that consists of a main optical lattice and its superpartner structure, and we investigate the onset of their lasing oscillations. Due to the coupling of the two constituent lattices, their degenerate optical modes form doublets, while the extra mode associated with unbroken supersymmetry forms a singlet state. Singlet lasing can be achieved for a wide range of design parameters either by introducing stronger loss in the partner lattice ...

  6. The Square Kilometre Array

    OpenAIRE

    Lazio, Joseph

    2009-01-01

    The Square Kilometre Array (SKA) is intended as the next-generation radio telescope and will address fundamental questions in astrophysics, physics, and astrobiology. The international science community has developed a set of Key Science Programs: (1) Emerging from the Dark Ages and the Epoch of Reionization, (2) Galaxy Evolution, Cosmology, and Dark Energy, (3) The Origin and Evolution of Cosmic Magnetism, (4) Strong Field Tests of Gravity Using Pulsars and Black Holes, and (5) The Cradle of...

  7. Photovoltaic cell array

    Science.gov (United States)

    Eliason, J. T. (Inventor)

    1976-01-01

    A photovoltaic cell array consisting of parallel columns of silicon filaments is described. Each fiber is doped to produce an inner region of one polarity type and an outer region of an opposite polarity type to thereby form a continuous radial semi conductor junction. Spaced rows of electrical contacts alternately connect to the inner and outer regions to provide a plurality of electrical outputs which may be combined in parallel or in series.

  8. The TALE Infill Array

    Science.gov (United States)

    Bergman, Douglas

    2009-05-01

    The TALE Infill Array in conjunction with the TALE Tower Detector will provide hybrid coverage of the cosmic ray energy spectrum down to 3x10^16 eV. It will consist of about 100, two square meter scintillators on the surface spaced at 400 m; and 24 buried twelve square meter scintillators. The combination of surface and underground detectors will allow for the determination of the muon content of showers and thus give a handle on cosmic ray composition.

  9. Lead-nickel electrochemical batteries

    CERN Document Server

    Glaize, Christian

    2012-01-01

    The lead-acid accumulator was introduced in the middle of the 19th Century, the diverse variants of nickel accumulators between the beginning and the end of the 20th Century. Although old, these technologies are always very present on numerous markets. Unfortunately they are still not used in optimal conditions, often because of the misunderstanding of the internal electrochemical phenomena.This book will show that batteries are complex systems, made commercially available thanks to considerable amounts of scientific research, empiricism and practical knowledge. However, the design of

  10. Electrochemical study of neodymium amalgams

    International Nuclear Information System (INIS)

    The electrochemical investigation of neodymium amalgam is performed using t the method of voltampere curves, constant potential coulometry, galvanostatic an potentiostatic methods. The experiments were conducted in a thermostatic electr rolyzer with isolated anode- and cathode spaces. A platinum plate served as a cathode, neodymium amalgam of 1.4 cm2 area served as an anode. A strong irrev versiblility of the anode oxidation process of neodymium amalgam was found. The solubility and diffusion coefficient of neodymium atoms in mercury were determin ned

  11. Hydrogen amalgam in electrochemical systems

    International Nuclear Information System (INIS)

    Hydrogen amalgam is a potential-defining component of many amalgam electrochemical systems. Hydrogen amalgam can be prepared during electrolysis of acid aqueous solutions with a mercury cathode, during anodic oxidation of alkali metal hydride amalgams and thermal decomposition of ammonium amalgam. Possible ways of atomic hydrogen removal from the surface of a mercury electrode in the course of electrolysis have been studied and a mechanism of hydrogen amalgam formation has been suggested. The role of hydrogen amalgam in the processes of applied electrochemistry has been considered. 32 refs

  12. Electrochemically switchable polypyrrole coated membranes

    Energy Technology Data Exchange (ETDEWEB)

    Weidlich, Claudia, E-mail: weidlich@dechema.d [DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany); Mangold, Klaus-Michael [DECHEMA e.V., Karl-Winnacker-Institut, Theodor-Heuss-Allee 25, D-60486 Frankfurt am Main (Germany)

    2011-04-01

    A method for coating membranes with polypyrrole (PPy) has been developed. Different membranes, such as microfiltration as well as ion exchanger membranes have been coated with PPy to yield electrical conductivity of the membranes. The coated membranes have been investigated by cyclic voltammetry and scanning electron microscopy and their permeability and permselectivity have been tested. The results show that PPy can be tailored as cation or anion exchanger and its porosity can be controlled to avoid any impairment of the membrane by the polymer layer. These PPy coated membranes can be applied as electrochemically switchable, functionalised membranes with controllabel and variable separation properties.

  13. Spaceborne Processor Array

    Science.gov (United States)

    Chow, Edward T.; Schatzel, Donald V.; Whitaker, William D.; Sterling, Thomas

    2008-01-01

    A Spaceborne Processor Array in Multifunctional Structure (SPAMS) can lower the total mass of the electronic and structural overhead of spacecraft, resulting in reduced launch costs, while increasing the science return through dynamic onboard computing. SPAMS integrates the multifunctional structure (MFS) and the Gilgamesh Memory, Intelligence, and Network Device (MIND) multi-core in-memory computer architecture into a single-system super-architecture. This transforms every inch of a spacecraft into a sharable, interconnected, smart computing element to increase computing performance while simultaneously reducing mass. The MIND in-memory architecture provides a foundation for high-performance, low-power, and fault-tolerant computing. The MIND chip has an internal structure that includes memory, processing, and communication functionality. The Gilgamesh is a scalable system comprising multiple MIND chips interconnected to operate as a single, tightly coupled, parallel computer. The array of MIND components shares a global, virtual name space for program variables and tasks that are allocated at run time to the distributed physical memory and processing resources. Individual processor- memory nodes can be activated or powered down at run time to provide active power management and to configure around faults. A SPAMS system is comprised of a distributed Gilgamesh array built into MFS, interfaces into instrument and communication subsystems, a mass storage interface, and a radiation-hardened flight computer.

  14. Array processor architecture

    Science.gov (United States)

    Barnes, George H. (Inventor); Lundstrom, Stephen F. (Inventor); Shafer, Philip E. (Inventor)

    1983-01-01

    A high speed parallel array data processing architecture fashioned under a computational envelope approach includes a data base memory for secondary storage of programs and data, and a plurality of memory modules interconnected to a plurality of processing modules by a connection network of the Omega gender. Programs and data are fed from the data base memory to the plurality of memory modules and from hence the programs are fed through the connection network to the array of processors (one copy of each program for each processor). Execution of the programs occur with the processors operating normally quite independently of each other in a multiprocessing fashion. For data dependent operations and other suitable operations, all processors are instructed to finish one given task or program branch before all are instructed to proceed in parallel processing fashion on the next instruction. Even when functioning in the parallel processing mode however, the processors are not locked-step but execute their own copy of the program individually unless or until another overall processor array synchronization instruction is issued.

  15. Electrochemical and thermal studies of lithium ion batteries

    Science.gov (United States)

    Lu, Wenquan

    The structural, electrochemical, and thermal characteristics of carbonaceous anodes and LiNi0.8Co0.2O2 cathode in Li-ion cells were investigated using various electrochemical and calorimetric techniques. The electrode-electrolyte interface was investigated for various carbonaceous materials such as graphite with different shapes, surface modified graphite with copper, and novel carbon material derived from sepiolite template. The structural and morphological properties were determined using XRD, TGA, SEM, BET techniques. The electrochemical characteristics were studied using conventional electrochemical techniques such as galvanostatic charge/discharge cycling, cyclic voltammetry, and impedance (AC and DC) methods. It was observed that the electrochemical active surface area instead of the BET area plays a critical role in the irreversible capacity loss associated with the carbonaceous anodes. It was also found that the exfoliation of carbon anodes especially in PC based electrolyte could be significantly reduced by protective copper coating of the natural graphite. LiNi0.8Co0.2O2 cathode material was found to possess high energy density and excellent cycling characteristics. The structural and electrochemical properties of LiNi0.8Co 0.2O2 synthesized by sol-gel and solid-state methods were studied. Results of the AC impedance spectroscopy carried out on LiNi 0.8Co0.2O2 cathodes revealed that the charge transfer resistance is a function of the state of charge. The solid state Li + diffusion was calculated to be around 10-13 cm2/s in the oxide particle by Warburg impedance method. In addition, the cell fabricated with LiNi0.8Co0.2O 2 cathode showed excellent energy and power performance under static and dynamic load conditions that prevail in Electric and Hybrid Vehicles. Thermal properties of the LiNi0.8Co0.2O2 cathode, carbonaceous anodes, and Li-ion cells fabricated with these electrodes were also investigated using isothermal microcalorimetry (IMC), differential

  16. Exploring plasmonic coupling in hole-cap arrays

    OpenAIRE

    Schmidt, Thomas M.; Maj Frederiksen; Vladimir Bochenkov; Sutherland, Duncan S

    2015-01-01

    The plasmonic coupling between gold caps and holes in thin films was investigated experimentally and through finite-difference time-domain (FDTD) calculations. Sparse colloidal lithography combined with a novel thermal treatment was used to control the vertical spacing between caps and hole arrays and compared to separated arrays of holes or caps. Optical spectroscopy and FDTD simulations reveal strong coupling between the gold caps and both Bloch Wave-surface plasmon polariton (BW-SPP) modes...

  17. Modern electrochemical processes and technologies in ionic melts

    Directory of Open Access Journals (Sweden)

    Omelchuk A.

    2003-01-01

    Full Text Available An analysis of the known methods for the electrochemical purification of non-ferrous metals in ionic melts is presented. A comparative estimation of the results of the electrochemical purification of non-ferrous metals by different methods has been performed. The main regularities of the electrochemical behavior of non-ferrous metals in conventional and electrode micro-spacing electrolysis are presented. It has been found that when electrolyzing some metals, e. g. bismuth, gallium, there is either no mass exchange between the electrodes, or it occurs under filtration conditions. It has been shown that the electrode micro-spacing processes provide a high quality of non-ferrous metals purification at low specific consumption of electric power and reagents. The use of bipolar electrodes and β-alumina diaphragms hinders the transfer of metallic impurities from the anode to the cathode. The effects revealed were used to develop new processes for the separation of non-ferrous metal alloys in ionic melts; most of them have been put into practice in non-ferrous metallurgy.

  18. Multiplexed electrochemical immunoassay of biomarkers using chitosan nanocomposites.

    Science.gov (United States)

    Chen, Xia; Ma, Zhanfang

    2014-05-15

    In this work, a novel and sensitive multiplexed immunoassay protocol for simultaneous electrochemical determination of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) was designed using functionalized chitosan composites. The immunosensing platform was prepared via immobilizing capture anti-AFP and anti-CEA on chitosan-Au nanoparticles (AuNPs) through EDC/NHS linking. The signal tags were fabricated by immobilizing electroactive redox probes - Prussian blue (PB) and ferrocenecarboxylic acid (Fc) on chitosan (CHIT), following by absorbing AuNPs to immobilize labeled anti-AFP and anti-CEA, respectively. A sandwich-type immunoassay format was employed for the simultaneous detection of AFP and CEA. The assay was based on the electrochemical oxidation/reduction of the redox species in signal tags, which has a relationship with the concentration of analytes. Experimental results revealed that the multiplexed electrochemical immunoassay enabled the simultaneous monitoring of AFP and CEA with a wide range of 0.05-100 ng mL(-1) for both AFP and CEA. The detection limits (LOD) was 0.03 ng mL(-1) for AFP and 0.02 ng mL(-1) for CEA (S/N=3). The assay results of serum samples with the proposed method were in a good agreement with the reference values from standard ELISA method. And the negligible cross-reactivity between the two analytes makes it possesses potential promise in clinical diagnosis. PMID:24413402

  19. Monovalent silicotungstate salts as electrolytes for electrochemical supercapacitors

    International Nuclear Information System (INIS)

    Highlights: • Li-, Na-, and K- silicotungstate salts were investigated as electrolytes for EDLC. • All salts are neutral and retained the Keggin structure. • All salt solutions showed high ionic conductivity and wide potential windows. • Carbon EDLCs utilizing these salt electrolytes can achieve a 1.5 V cell voltage. - Abstract: Lithium, sodium, and potassium salts of silicotungstic acid were synthesized and characterized as aqueous neutral electrolytes for electrochemical supercapacitors. The acidity of the aqueous solution and the structure of the solid-state anion were examined to confirm the presence of SiW salts. Ionic conductivity and the electrochemical stability potential window were characterized and compared to a silicotungstic acid solution using metallic blocking electrodes. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the performance of carbon EDLC cells enabled by the neutral electrolytes and revealed a 1.5 V cell voltage and good cycle life. The similarities and differences among the three salts are explained based on the properties of cations in these neutral electrolytes

  20. An electrochemical treatment for aqueous radioactive solutions using pottery

    International Nuclear Information System (INIS)

    A bench scale electrolytic cell made from plexiglas was used for electrochemical separation of 137Cs and 60Co from simullated aqueous radioactive solutions. In this cell, a stainless steel plate represented the anode. The electrochemical treatment technique used depends on forcing the radioactive cations of the solution (137Cs+ and 60Co++) towards the opposite electrode under the influence of applied electric current, where they highly sorbed in the pottery body. The highest removal for137Cs+ and 60Co was in the alkalina medium, especially at pH>9. The investigated factors affected the electrochemicla processes are, applied voltage, treatment duration, hydrogen ion concentration of the radioactive solution, and the consumed electrical energy . It was found that at pH 11, applied voltage 30V and current 100 mA, the highest removal of 137Cs is 99.8% after 2.5 hours, and 99.3% and 99.3% for 60Co after 1.25 hour.The total consumed energy for 137Cs and 60Co were 33.75 and 16.88 W.h.dm-3, respectively. Comparing with other treatment methods, the electrochemical method revealed three advantages: shorter treatment time, low-cost materials, and low consumed energy. The results obtained showed that the dual application of electric current and sorption on the surface of pottery are feasible for the treatment of aqueous radioactive solutions

  1. Classical Simulation of Squeezed Vacuum in Optical Waveguide Arrays

    CERN Document Server

    Sukhorukov, Andrey A; Sipe, John

    2013-01-01

    We reveal that classical light diffraction in arrays of specially modulated coupled optical waveguides can simulate the quantum process of two-mode squeezing in nonlinear media, with the waveguide mode amplitudes corresponding the signal and idler photon numbers. The whole Fock space is mapped by a set of arrays, where each array represents the states with a fixed difference between the signal and idler photon numbers. We demonstrate a critical transition from photon number growth to Bloch oscillations with periodical revivals of an arbitrary input state, associated with an increase of the effective phase mismatch between the pump and the squeezed photons.

  2. Electrochemical capacitance characteristics of patterned ruthenium dioxide-carbon nanotube nanocomposites grown onto graphene

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Yi-Ting [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Lee, Kuei-Yi, E-mail: kylee@mail.ntust.edu.tw [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Huang, Ying-Sheng [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China)

    2014-03-01

    Highlights: • Graphene was grown on Cu foil by mobile thermal chemical vapor deposition system. • CNT was synthesized on graphene for RuO{sub 2} nanostructure growth by thermal chemical vapor deposition system. • The CNT growth location was fixed through the use of photolithography technique, thereby increasing the specific area. • RuO{sub 2} nanostructures were coated onto CNT bundle arrays through metal organic chemical vapor deposition, in order to utilize its pseudo capacitive property. - Abstract: In this study, graphene was used as a conductive substrate for vertically aligned carbon nanotube (CNT) bundle arrays growth, to be used as an electrode for electrochemical double layer capacitor (EDLC), as graphene and CNT exhibit good conductivity and excellent chemical stability. Both of them are composed of carbon, therefore making a superior adhesion between them. The configuration of bundle arrays provided a relatively higher specific surface area in contact with electrolyte, thereby resulting in demonstratively higher capacitance. Moreover, as the RuO{sub 2} nanostructures have good pseudocapacitance characteristics, they were coated onto vertically aligned CNT bundle arrays in order to effectively enhance the EDLC performances. The characteristics of CNT/graphene, CNT bundle/graphene, and RuO{sub 2}/CNT bundle/graphene electrodes were examined with the use of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. Furthermore, their electrochemical properties were investigated by an electrochemical analyzer. The specific capacitances of CNT/graphene, CNT bundle/graphene, and RuO{sub 2}/CNT bundle/graphene were 4.64, 6.65, and 128.40 F/g at the scan rate of 0.01 V/s, respectively.

  3. Polycrystalline-Diamond MEMS Biosensors Including Neural Microelectrode-Arrays

    Directory of Open Access Journals (Sweden)

    Donna H. Wang

    2011-08-01

    Full Text Available Diamond is a material of interest due to its unique combination of properties, including its chemical inertness and biocompatibility. Polycrystalline diamond (poly-C has been used in experimental biosensors that utilize electrochemical methods and antigen-antibody binding for the detection of biological molecules. Boron-doped poly-C electrodes have been found to be very advantageous for electrochemical applications due to their large potential window, low background current and noise, and low detection limits (as low as 500 fM. The biocompatibility of poly-C is found to be comparable, or superior to, other materials commonly used for implants, such as titanium and 316 stainless steel. We have developed a diamond-based, neural microelectrode-array (MEA, due to the desirability of poly-C as a biosensor. These diamond probes have been used for in vivo electrical recording and in vitro electrochemical detection. Poly-C electrodes have been used for electrical recording of neural activity. In vitro studies indicate that the diamond probe can detect norepinephrine at a 5 nM level. We propose a combination of diamond micro-machining and surface functionalization for manufacturing diamond pathogen-microsensors.

  4. Special Section: Electrochemical capacitors: Guest Editor's note

    Science.gov (United States)

    Balducci, Andrea

    2016-09-01

    Electrochemical capacitors (i.e., supercapacitors) are nowadays considered as one of the most important electrochemical storage devices. Thanks to their high power, extraordinary cycle life and high reliability these devices are currently used in a large number of applications, rendering them indispensible for our daily life.

  5. Energy system comprising an electrochemical energy source

    NARCIS (Netherlands)

    Roozeboom, F.; Notten, P.

    2010-01-01

    The invention relates to an energy system comprising an electrochemical energy source, wherein said electrochemical energy source comprises at least one assembly of a first electrode, a second electrode, and an intermediate solid-state electrolyte separating said first electrode and said second elec

  6. Electrochemical preparation of polypyrrole conducting films

    OpenAIRE

    Mária Filkusová*; Renáta Oriňáková

    2010-01-01

    Cyclic voltammetry has been used to investigate the electrochemical polymerization of pyrrole on the surface of a paraffin impregnated graphite electrode (PIGE). Effect of pH and concentration of the electrolyte solution on the electrochemical deposition of polypyrrole (PPy) was studied. The structure of the deposited layers was studied using scanning electron microscope (SEM). Well–adhering black PPy films were obtained.

  7. The Strategic Electrochemical Research Center in Denmark

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Hansen, Karin Vels

    2011-01-01

    A 6-year strategic electrochemistry research center (SERC) in fundamental and applied aspects of electrochemical cells with a main emphasis on solid oxide cells was started in Denmark on January 1st, 2007 in cooperation with other Danish and Swedish Universities. Furthermore, 8 Danish companies...... are presented. ©2011 COPYRIGHT ECS - The Electrochemical Society...

  8. Non-aqueous electrolytes for electrochemical cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhengcheng; Dong, Jian; Amine, Khalil

    2016-06-14

    An electrolyte electrochemical device includes an anodic material and an electrolyte, the electrolyte including an organosilicon solvent, a salt, and a hybrid additiving having a first and a second compound, the hybrid additive configured to form a solid electrolyte interphase film on the anodic material upon application of a potential to the electrochemical device.

  9. Formic Acid Electrooxidation by a Platinum Nanotubule Array Electrode

    Directory of Open Access Journals (Sweden)

    Eric Broaddus

    2013-01-01

    Full Text Available One-dimensional metallic nanostructures such as nanowires, rods, and tubes have drawn much attention for electrocatalytic applications due to potential advantages that include fewer diffusion impeding interfaces with polymeric binders, more facile pathways for electron transfer, and more effective exposure of active surface sites. 1D nanostructured electrodes have been fabricated using a variety of methods, typically showing improved current response which has been attributed to improved CO tolerance, enhanced surface activity, and/or improved transport characteristics. A template wetting approach was used to fabricate an array of platinum nanotubules which were examined electrochemically with regard to the electrooxidation of formic acid. Arrays of 100 and 200 nm nanotubules were compared to a traditional platinum black catalyst, all of which were found to have similar surface areas. Peak formic acid oxidation current was observed to be highest for the 100 nm nanotubule array, followed by the 200 nm array and the Pt black; however, CO tolerance of all electrodes was similar, as were the onset potentials of the oxidation and reduction peaks. The higher current response was attributed to enhanced mass transfer in the nanotubule electrodes, likely due to a combination of both the more open nanostructure as well as the lack of a polymeric binder in the catalyst layer.

  10. Hierarchical tree-like heterostructure arrays for enhanced photoeletrochemical activity

    International Nuclear Information System (INIS)

    Graphical abstract: The hierarchical tree-like heterostructure arrays have been fabricated for enhanced photocurrent response and photoelectrochemical activity. - Abstract: The structure of biomimetic approach to converting sunlight was applied for design of composite materials. Here, hierarchical tree-like heterostructure Ag/ZnO (Ag wt%: 8.9%) arrays were fabricated by two-step electrodeposition, and it exhibited improved activity during photoelectrochemical water oxidation. The wurtzite-structured ZnO arrays prepared are the “trunk”. Ag nanoclusters were selectively deposited on the top of arrays as the “leaf”, which can strongly interact with visible light due to surface plasmon resonance. The inducted electromagnetic fields around Ag would efficiently propagate energy to composites by hot electrons injection. Based on morphology and crystal structure analysis, the linear sweep voltammagrams display that photocurrent increase to 0.17 mA/cm2 at 1.23 VRHE, and the photo-to-hydrogen generation is 0.23%. Additionally, the amperometric I-t curves collected without voltage displayed better photocurrent response under sunlight. The kinetics of PEC process at the electrode surface was investigated by electrochemical impedance spectroscopy (EIS). The mechanism was deduced based on the energy level of ZnO and Ag. The designed plasmonic crystal system exhibited that tree-like heterostructure is favorable for improving sunlight absorption and photoeletrochemical performance

  11. A polymeric nanocoating on carbon nanotube arrays for developing imprinted protein sensor

    Science.gov (United States)

    Ren, L.; Zhao, H. Z.; Xu, C. J.; Yu, Y.; Wang, H. Z.; Lan, Y. C.; Wagner, D.; Naughton, M. J.; Ren, Z. F.; Chiles, T. C.; Cai, D.

    2010-03-01

    Polyphenol (PPn) was electrodeposited on carbon nanotubes (CNT) arrays at nanoscale thickness. PPn is a non-conductive polymer, so increase of sensor impedance was observed with high density CNT array, low density CNT array, and tip-polished CNT array (tCNTA), while tCNTA was determined to be the best nanosensor platform to incorporate the imprinted PPn coating due to the highest impedance increase. The PPn was characterized by transmission electron microscopy, electrochemical impedance spectroscopy and cyclic voltammetry for its thickness, uniformity, stability, resistivity and permittivity etc., as well as the protein entrapment and removal process. The density of the imprint was also evaluated by a PPn refilling experiment. Finally, ferritin was used as the template to develop a highly sensitive and selective protein nanosensor. Therefore, a novel strategy was demonstrated here to deposit and characterize polymeric nanocoating, also to evaluate imprints and detect proteins.

  12. Nano electrode arrays for in-situ identification and quantification of chemicals in water.

    Energy Technology Data Exchange (ETDEWEB)

    Gurule, Natalia J.; Kelly, Michael James; Brevnov, Dmitri A. (University of New Mexico, Albuquerque, NM); Ashby, Carol Iris Hill; Pfeifer, Kent Bryant; Yelton, William Graham

    2004-12-01

    The nano electrode arrays for in-situ identification and quantification of chemicals in water progress in four major directions. (1) We developed and engineering three nanoelectrode array designs which operate in a portable field mode or as distributed sensor network for water systems. (2) To replace the fragile glass electrochemical cells using in the lab, we design and engineered field-ready sampling heads that combine the nanoelectrode arrays with a high-speed potentiostat. (3) To utilize these arrays in a portable system we design and engineered a light weight high-speed potentiostat with pulse widths from 2 psec. to 100 msec. or greater. (4) Finally, we developed the parameters for an analytical method in low-conductivity solutions for Pb(II) detection, with initial studies for the analysis of As(III) and As(V) analysis in natural water sources.

  13. Hydrothermal synthesis of porous Co(OH)2 nanoflake array film and its supercapacitor application

    Indian Academy of Sciences (India)

    Z Chen; Y Chen; C Zuo; S Zhou; A G Xiao; A X Pan

    2013-04-01

    Porous -Co(OH)2 nanoflake array film is prepared by a facile hydrothermal synthesis method. The -Co(OH)2 nanoflake array film exhibits a highly porous net-like structure composed of interconnected nanoflakes with a thickness of 15 nm. The pseudo-capacitive behaviour of the Co(OH)2 nanoflake array film is investigated by cyclic voltammograms (CV) and galvanostatic charge–discharge tests in 2MKOH. The -Co(OH)2 nanoflake array film exhibits high capacitances of 1017 F g-1 at 2Ag-1 and 890 F g-1 at 40Ag-1 as well as rather good cycling stability for supercapacitor application. The porous architecture is responsible for the enhancement of the electrochemical properties because it provides fast ion and electron transfer, large reaction surface area and good strain accommodation.

  14. Mixed Frequency Ultrasound Phased Array

    Institute of Scientific and Technical Information of China (English)

    香勇; 霍健; 施克仁; 陈以方

    2004-01-01

    A mixed frequency ultrasonic phased array (MPA) was developed to improve the focus, in which the element excitation frequencies are not all the same as in a normal constant frequency phased array. A theoretical model of the mixed frequency phased array based on the interference principle was used to simulate the array's sound distribution. The pressure intensity in the array focal area was enhanced and the scanning area having effective contrast resolution was enlarged. The system is especially useful for high intensity focused ultrasound (HIFU) with more powerful energy and ultrasound imaging diagnostics with improved signal to noise ratios, improved beam forming and more uniform imaging quality.

  15. Electrochemical properties of CVD grown pristine graphene: monolayer- vs. quasi-graphene.

    Science.gov (United States)

    Brownson, Dale A C; Varey, Sarah A; Hussain, Fiazal; Haigh, Sarah J; Banks, Craig E

    2014-01-01

    We report the electrochemical properties of pristine monolayer, double layer and few-layer (termed quasi-) graphene grown via CVD and transferred using PMMA onto an insulating substrate (silicon dioxide wafers). Characterisation has been performed by Raman spectroscopy, optical spectroscopy, Atomic Force Microscopy and X-ray Photoelectron Spectroscopy, revealing 'true' pristine single-layer graphene (O/C of 0.05) at the former and pristine quasi-graphene at the latter (O/C of 0.07); the term "quasi-graphene" is coined due to the surface comprising on average 4-graphene-layers. The graphene electrodes are electrochemically characterised using both inner-sphere and outer-sphere redox probes with electrochemical performances of the graphene electrodes compared to other available graphitic electrodes, namely that of basal- and edge- plane pyrolytic graphite electrodes constructed from Highly Ordered Pyrolytic Graphite (HOPG), with information on heterogeneous rate constants (k(o)) obtained. The electrochemical rate constants are predominantly influenced by the electronic properties of the graphene surfaces. Monolayer graphene is found to exhibit slow heterogeneous electron transfer (HET) kinetics towards the redox probes studied, with HET rates ca. 2 and 8 times faster at quasi-graphene and HOPG respectively, relative to that of the monolayer graphene electrode. Critically contrasting the performance of monolayer graphene to quasi-graphene and HOPG electrodes reveals that increasing the number of graphene layers results in improved electrochemical properties, where in terms of the electrochemical reversibility of the probes studied: monolayer-graphene graphene electron transfer kinetics at graphitic materials, the slow HET rates at pristine single-layer graphene electrodes are likely due to graphene's fundamental geometry, which comprises a small edge plane and large basal plane contribution. In the case of quasi-graphene and HOPG, they possess increasing global

  16. Solid oxide electrochemical reactor science.

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

    2010-09-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

  17. Electrochemical treatment of liquid wastes

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T. [Savannah River Technology Center, Aiken, SC (United States)

    1997-10-01

    Under this task, electrochemical treatment processes are being evaluated and developed for the destruction of organic compounds and nitrates/nitrites and the removal of other hazardous species from liquid wastes stored throughout the DOE complex. This technology targets the (1) destruction of nitrates, nitrites and organic compounds; (2) removal of radionuclides; and (3) removal of RCRA metals. The development program consists of five major tasks: (1) evaluation of electrochemical reactors for the destruction and removal of hazardous waste components, (2) development and validation of engineering process models, (3) radioactive laboratory-scale tests, (4) demonstration of the technology in an engineering-scale reactor, and (5) analysis and evaluation of test data. The development program team is comprised of individuals from national laboratories, academic institutions, and private industry. Possible benefits of this technology include: (1) improved radionuclide separation as a result of the removal of organic complexants, (2) reduction in the concentrations of hazardous and radioactive species in the waste (e.g., removal of nitrate, mercury, chromium, cadmium, {sup 99}Tc, and {sup 106}Ru), (3) reduction in the size of the off-gas handling equipment for the vitrification of low-level waste (LLW) by reducing the source of NO{sub x} emissions, (4) recovery of chemicals of value (e.g. sodium hydroxide), and (5) reduction in the volume of waste requiring disposal.

  18. Electrochemical Polymerization of Methylene Green

    Institute of Scientific and Technical Information of China (English)

    ZHU,Hong-Ping; MU,Shao-Lin

    2001-01-01

    The electrochemical polymerization of methylene green has been carried out using cyclic voltammetry. The electrolytic so lution consisted of 4 × 10-3 mol/L methylene green, 0.1 mol/L NaNO3 and 1 × 10-2 mol/L sodium tetraborate with pH 11.0. The temperature for polymerization is controlled at 60℃. The scan potential is set between -0.2 and 1.2 V (vs. Ag/AgCl with saturated KCl solution). There are an anodic peak and a cathodic peak on the cyclic voltammogram of poly(methylene green) at pH≤3.8. Both peak potentials shift towards nega tive potentials with increasing pH value, and their peak cur rents decrease with increasing pH value. Poly(methylene green) has a good electrochemical activity and stability in aqueous solutions with pH ≤ 3.8. The UV-Visible spectrum and FTIR spectrum of poly (methylene green) are different from those of methylene green.

  19. Space Electrochemical Research and Technology

    Science.gov (United States)

    Wilson, Richard M. (Compiler)

    1996-01-01

    Individual papers presented at the conference address the following topics: development of a micro-fiber nickel electrode for nickel-hydrogen cell, high performance nickel electrodes for space power application, bending properties of nickel electrodes for nickel-hydrogen batteries, effect of KOH concentration and anions on the performance of a Ni-H2 battery positive plate, advanced dependent pressure vessel nickel hydrogen spacecraft cell and battery design, electrolyte management considerations in modern nickel hydrogen and nickel cadmium cell and battery design, a novel unitized regenerative proton exchange membrane fuel cell, fuel cell systems for first lunar outpost - reactant storage options, the TMI regenerable solid oxide fuel cell, engineering development program of a closed aluminum-oxygen semi-cell system for an unmanned underwater vehicle, SPE OBOGS on-board oxygen generating system, hermetically sealed aluminum electrolytic capacitor, sol-gel technology and advanced electrochemical energy storage materials, development of electrochemical supercapacitors for EMA applications, and high energy density electrolytic capacitor.

  20. Buffered Electrochemical Polishing of Niobium

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tian, Hui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); College of William and Mary, Williamsburg, VA (United States); Corcoran, Sean [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2011-03-01

    The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop.' In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (? 120 °C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. As part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.

  1. Electrochemical treatment of liquid wastes

    International Nuclear Information System (INIS)

    Under this task, electrochemical treatment processes are being evaluated and developed for the destruction of organic compounds and nitrates/nitrites and the removal of other hazardous species from liquid wastes stored throughout the DOE complex. This technology targets the (1) destruction of nitrates, nitrites and organic compounds; (2) removal of radionuclides; and (3) removal of RCRA metals. The development program consists of five major tasks: (1) evaluation of electrochemical reactors for the destruction and removal of hazardous waste components, (2) development and validation of engineering process models, (3) radioactive laboratory-scale tests, (4) demonstration of the technology in an engineering-scale reactor, and (5) analysis and evaluation of test data. The development program team is comprised of individuals from national laboratories, academic institutions, and private industry. Possible benefits of this technology include: (1) improved radionuclide separation as a result of the removal of organic complexants, (2) reduction in the concentrations of hazardous and radioactive species in the waste (e.g., removal of nitrate, mercury, chromium, cadmium, 99Tc, and 106Ru), (3) reduction in the size of the off-gas handling equipment for the vitrification of low-level waste (LLW) by reducing the source of NOx emissions, (4) recovery of chemicals of value (e.g. sodium hydroxide), and (5) reduction in the volume of waste requiring disposal

  2. High-Temperature Gas Sensor Array (Electronic Nose) Demonstrated

    Science.gov (United States)

    Hunter, Gary W.

    2002-01-01

    The ability to measure emissions from aeronautic engines and in commercial applications such as automotive emission control and chemical process monitoring is a necessary first step if one is going to actively control those emissions. One single sensor will not give all the information necessary to determine the chemical composition of a high-temperature, harsh environment. Rather, an array of gas sensor arrays--in effect, a high-temperature electronic "nose"--is necessary to characterize the chemical constituents of a diverse, high-temperature environment, such as an emissions stream. The signals produced by this nose could be analyzed to determine the constituents of the emission stream. Although commercial electronic noses for near-room temperature applications exist, they often depend significantly on lower temperature materials or only one sensor type. A separate development effort necessary for a high-temperature electronic nose is being undertaken by the NASA Glenn Research Center, Case Western Reserve University, Ohio State University, and Makel Engineering, Inc. The sensors are specially designed for hightemperature environments. A first-generation high-temperature electronic nose has been demonstrated on a modified automotive engine. This nose sensor array was composed of sensors designed for hightemperature environments fabricated using microelectromechanical-systems- (MEMS-) based technology. The array included a tin-oxide-based sensor doped for nitrogen oxide (NOx) sensitivity, a SiC-based hydrocarbon (CxHy) sensor, and an oxygen sensor (O2). These sensors operate on different principles--resistor, diode, and electrochemical cell, respectively--and each sensor has very different responses to the individual gases in the environment. A picture showing the sensor head for the array is shown in the photograph on the left and the sensors installed in the engine are shown in the photograph on the right. Electronics are interfaced with the sensors for

  3. Scanning Electrochemical Microscopy of Carbon Nanomaterials and Graphite.

    Science.gov (United States)

    Amemiya, Shigeru; Chen, Ran; Nioradze, Nikoloz; Kim, Jiyeon

    2016-09-20

    Carbon materials are tremendously important as electrode materials in both fundamental and applied electrochemistry. Recently, significant attention has been given not only to traditional carbon materials, but also to carbon nanomaterials for various electrochemical applications in energy conversion and storage as well as sensing. Importantly, many of these applications require fast electron-transfer (ET) reactions between a carbon surface and a redox-active molecule in solution. It, however, has not been well understood how heterogeneous ET kinetics at a carbon/solution interface is affected by the electronic structure, defect, and contamination of the carbon surface. Problematically, it is highly challenging to measure the intrinsic electrochemical reactivity of a carbon surface, which is readily passivated by adventitious organic contaminants. This Account summarizes our recent studies of carbon nanomaterials and graphite by scanning electrochemical microscopy (SECM) not only to reveal the fast ET kinetics of simple ferrocene derivatives at their graphitic surfaces, but also to obtain mechanistic insights into their extraordinary electrochemical reactivity. Specifically, we implemented new principles and technologies to reliably and reproducibly enable nanoscale SECM measurements. We took advantage of a new SECM imaging principle to resolve the high reactivity of the sidewall of individual single walled carbon nanotubes. In addition, we developed SECM-based nanogap voltammetry to find that monolayer graphene grown by chemical vapor deposition yields an unprecedentedly high standard ET rate constant, k(0), of ≥25 cm/s, which was >1000 times higher than that reported in the literature. Remarkably, the nonideal asymmetry of paired nanogap voltammograms revealed that the high reactivity of graphitic surfaces is compromised by their contamination with airborne hydrocarbons. Most recently, we protected the clean surface of highly oriented pyrolytic graphite from the

  4. Multiplex PCB-based electrochemical detection of cancer biomarkers using MLPA-barcode approach.

    Science.gov (United States)

    Sánchez, J L Acero; Henry, O Y F; Joda, H; Solnestam, B Werne; Kvastad, L; Johansson, E; Akan, P; Lundeberg, J; Lladach, N; Ramakrishnan, D; Riley, I; O'Sullivan, C K

    2016-08-15

    Asymmetric multiplex ligation-dependent probe amplification (MLPA) was developed for the amplification of seven breast cancer related mRNA markers and the MLPA products were electrochemically detected via hybridization. Seven breast cancer genetic markers were amplified by means of the MLPA reaction, which allows for multiplex amplification of multiple targets with a single primer pair. Novel synthetic MLPA probes were designed to include a unique barcode sequence in each amplified gene. Capture probes complementary to each of the barcode sequences were immobilized on each electrode of a low-cost electrode microarray manufactured on standard printed circuit board (PCB) substrates. The functionalised electrodes were exposed to the single-stranded MLPA products and following hybridization, a horseradish peroxidase (HRP)-labelled DNA secondary probe complementary to the amplified strand completed the genocomplex, which was electrochemically detected following substrate addition. The electrode arrays fabricated using PCB technology exhibited an excellent electrochemical performance, equivalent to planar photolithographically-fabricated gold electrodes, but at a vastly reduced cost (>50 times lower per array). The optimised system was demonstrated to be highly specific with negligible cross-reactivity allowing the simultaneous detection of the seven mRNA markers, with limits of detections as low as 25pM. This approach provides a novel strategy for the genetic profiling of tumour cells via integrated "amplification-to-detection". PMID:27085955

  5. A nanocoaxial-based electrochemical sensor for the detection of cholera toxin.

    Science.gov (United States)

    Archibald, Michelle M; Rizal, Binod; Connolly, Timothy; Burns, Michael J; Naughton, Michael J; Chiles, Thomas C

    2015-12-15

    Sensitive, real-time detection of biomarkers is of critical importance for rapid and accurate diagnosis of disease for point of care (POC) technologies. Current methods do not allow for POC applications due to several limitations, including sophisticated instrumentation, high reagent consumption, limited multiplexing capability, and cost. Here, we report a nanocoaxial-based electrochemical sensor for the detection of bacterial toxins using an electrochemical enzyme-linked immunosorbent assay (ELISA) and differential pulse voltammetry (DPV) or square wave voltametry (SWV). The device architecture is composed of vertically-oriented, nanoscale coaxial electrodes in array format (~10(6) coaxes per square millimeter). The coax cores and outer shields serve as integrated working and counter electrodes, respectively, exhibiting a nanoscale separation gap corresponding to ~100 nm. Proof-of-concept was demonstrated for the detection of cholera toxin (CT). The linear dynamic range of detection was 10 ng/ml-1 µg/ml, and the limit of detection (LOD) was found to be 2 ng/ml. This level of sensitivity is comparable to the standard optical ELISA used widely in clinical applications, which exhibited a linear dynamic range of 10 ng/ml-1 µg/ml and a LOD of 1 ng/ml. In addition to matching the detection profile of the standard ELISA, the nanocoaxial array provides a simple electrochemical readout and a miniaturized platform with multiplexing capabilities for the simultaneous detection of multiple biomarkers, giving the nanocoax a desirable advantage over the standard method towards POC applications.

  6. Characterization and Optical Properties of the Single Crystalline SnS Nanowire Arrays

    Directory of Open Access Journals (Sweden)

    Yue GH

    2009-01-01

    Full Text Available Abstract The SnS nanowire arrays have been successfully synthesized by the template-assisted pulsed electrochemical deposition in the porous anodized aluminum oxide template. The investigation results showed that the as-synthesized nanowires are single crystalline structures and they have a highly preferential orientation. The ordered SnS nanowire arrays are uniform with a diameter of 50 nm and a length up to several tens of micrometers. The synthesized SnS nanowires exhibit strong absorption in visible and near-infrared spectral region and the direct energy gapE gof SnS nanowires is 1.59 eV.

  7. Silicon-Copper Helical Arrays for New Generation Lithium Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Polat, B. D.; Keles, O; Amine, K

    2015-09-22

    The helical array (with 10 atom % Cu) exhibits 3130 mAh g–1 with 83% columbic efficiency and retains 83% of its initial discharge capacity after 100th cycle. Homogeneously distributed interspaces between the helical arrays accommodate high volumetric changes upon cycling and copper atoms form a conductive network to buffer the mechanical stress generated in the electrode while minimizing electrochemical agglomeration of Si. Also, ion assistance is believed to enhance the density of the helices at the bottom thus increasing the adhesion

  8. M(o)ssbauer study and magnetic properties of electrochemical material LiFePO4

    Institute of Scientific and Technical Information of China (English)

    Luo Zhi; Di Nai-Li; Kou Zhi-Qi; Cheng Zhao-Hua; Liu Li-Jun; Chen Li-Quan; Huang Xue-Jie

    2004-01-01

    Magnetic properties and crystal symmetry of electrochemical material LiFePO4 have been investigated by Mossbauer spectroscopy and magnetization measurement. Magnetization reveals the antiferromagnetic nature of LiFePO4. Temperature dependence of inverse susceptibility and that of hyperfine field confirm that there is an antiferromagnetic-paramagnetic transition at about 50K.

  9. Nanocrystalline CdTe thin films by electrochemical synthesis

    Directory of Open Access Journals (Sweden)

    Ramesh S. Kapadnis

    2013-03-01

    Full Text Available Cadmium telluride thin films were deposited onto different substrates as copper, Fluorine-doped tin oxide (FTO, Indium tin oxide (ITO, Aluminum and zinc at room temperature via electrochemical route. The morphology of the film shows the nanostructures on the deposited surface of the films and their growth in vertical direction. Different nanostructures developed on different substrates. The X-ray diffraction study reveals that the deposited films are nanocrystalline in nature. UV-Visible absorption spectrum shows the wide range of absorption in the visible region. Energy-dispersive spectroscopy confirms the formation of cadmium telluride.

  10. Electrochemical Analysis of the Electrodeposition of Platinum Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hae-Min; Cho, Sung-Woon; Kim, Jun-Hyun; Kim, Chang-Koo [Ajou University, Suwon (Korea, Republic of)

    2015-10-15

    A bath for electrodeposition of platinum nanoparticles on low-cost graphite substrates was developed to attach nanoparticles directly onto a substrate, and electrochemical characteristics of the electrodeposition of platinum nanoparticles were investigated. The reaction mechanism was examined by the analysis of polarization behavior. Cyclic voltammetry measurements revealed that the electrodeposition of platinum nanoparticles was limited by mass transfer. The chronoamperometric study showed an instantaneous nucleation mechanism during the electrodeposition of platinum nanoparticles on graphite. Because graphite is much cheaper than other carbon-based substrates, the electrodeposition of platinum nanoparticles on the graphite is expected to have useful applications.

  11. A signal-on electrochemical DNA biosensor based on potential-assisted Cu(I)-catalyzed azide-alkyne cycloaddition mediated labeling of hairpin-like oligonucleotide with electroactive probe.

    Science.gov (United States)

    Hu, Qiong; Kong, Jinming; Li, Yajie; Zhang, Xueji

    2016-01-15

    A novel electrochemical biosensor was developed for the signal-on detection of sequence-specific DNA by exploiting potential-assisted Cu(I)-catalyzed azide-alkyne cycloaddition (φCuAAC) as an efficient approach for the labeling of hairpin-like oligonucleotide (hairpin) with electroactive probe. The hairpins, dually labeled with thiol and azide at either terminal, were firstly self-assembled on gold electrode and served as the capture probes for the specific recognition of target DNA. Upon hybridization with target DNA, the surface-confined hairpins were unfolded, liberating the azide-containing terminals away from electrode surface. Subsequently, the unfolded hairpins were conveniently and efficiently labeled with ethynylferrocene (EFC) via the φCuAAC. The quantitatively labeled EFC was finally measured via differential pulse voltammetry (DPV) for the signal-on electrochemical detection of sequence-specific DNA. The biosensor presented a good linear response over the range from 1pM to 1nM with a detection limit of 0.62pM. Results also revealed that it was highly specific and held a good detection capability in serum samples. Furthermore, the ability to chemoselectively label hairpin-like oligonucleotide with signal reporter by electrical addressing, together with the simplicity and efficiency of the φCuAAC, makes it compatible with microfluidic devices and microelectrode arrays to achieve the miniaturized and multiplexed detections.

  12. Fabrication of ordered NiO coated Si nanowire array films as electrodes for a high performance lithium ion battery.

    Science.gov (United States)

    Qiu, M C; Yang, L W; Qi, X; Li, Jun; Zhong, J X

    2010-12-01

    Highly ordered NiO coated Si nanowire array films are fabricated as electrodes for a high performance lithium ion battery via depositing Ni on electroless-etched Si nanowires and subsequently annealing. The structures and morphologies of as-prepared films are characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. When the potential window versus lithium was controlled, the coated NiO can be selected to be electrochemically active to store and release Li+ ions, while highly conductive crystalline Si cores function as nothing more than a stable mechanical support and an efficient electrical conducting pathway. The hybrid nanowire array films exhibit superior cyclic stability and reversible capacity compared to that of NiO nanostructured films. Owing to the ease of large-scale fabrication and superior electrochemical performance, these hybrid nanowire array films will be promising anode materials for high performance lithium-ion batteries.

  13. Microfabrication, characterization and in vivo MRI compatibility of diamond microelectrodes array for neural interfacing

    Energy Technology Data Exchange (ETDEWEB)

    Hébert, Clément, E-mail: clement.hebert@cea.fr [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Warnking, Jan; Depaulis, Antoine [INSERM, U836, Grenoble Institut des Neurosciences, Grenoble (France); Garçon, Laurie Amandine [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); CEA/INAC/SPrAM/CREAB, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Mermoux, Michel [Université Grenoble Alpes, LEPMI, F-38000 Grenoble (France); CNRS, LEPMI, F-38000 Grenoble (France); Eon, David [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France); Mailley, Pascal [CEA-LETI-DTBS Minatec, 17 rue des Martyres, 38054 Grenoble (France); Omnès, Franck [Institut Néel, CNRS et Université Joseph Fourier, BP 166, F-38042 Grenoble Cedex 9 (France)

    2015-01-01

    Neural interfacing still requires highly stable and biocompatible materials, in particular for in vivo applications. Indeed, most of the currently used materials are degraded and/or encapsulated by the proximal tissue leading to a loss of efficiency. Here, we considered boron doped diamond microelectrodes to address this issue and we evaluated the performances of a diamond microelectrode array. We described the microfabrication process of the device and discuss its functionalities. We characterized its electrochemical performances by cyclic voltammetry and impedance spectroscopy in saline buffer and observed the typical diamond electrode electrochemical properties, wide potential window and low background current, allowing efficient electrochemical detection. The charge storage capacitance and the modulus of the electrochemical impedance were found to remain in the same range as platinum electrodes used for standard commercial devices. Finally we observed a reduced Magnetic Resonance Imaging artifact when the device was implanted on a rat cortex, suggesting that boron doped-diamond is a very promising electrode material allowing functional imaging. - Highlights: • Microfabrication of all-diamond microelectrode array • Evaluation of as-grown nanocrystalline boron-doped diamond for electrical neural interfacing • MRI compatibility of nanocrystalline boron-doped diamond.

  14. Stability of titania nanotube arrays in aqueous environment and the related factors

    OpenAIRE

    Can Cao; Jun Yan; Yumei Zhang; Lingzhou Zhao

    2016-01-01

    Titania nanotube arrays (NTAs) on titanium (Ti) fabricated by electrochemical anodization have attracted tremendous interest for diverse applications, of which most perform in aqueous environment or related to interaction with water. The NTAs are widely studied however the related factor of stability of NTAs when applied in such environment has rarely been concerned. We report that the annealed anatase NTAs are stable but the non-annealed amorphous NTAs are unstable to undergo specific struct...

  15. Pencil probe system for electrochemical analysis and modification in nanometer dimensions

    Science.gov (United States)

    Fasching, Rainer J.; Tao, Ye; Hammerick, Kyle; Prinz, Fritz B.

    2003-04-01

    A pencil-shaped electrochemical transducer system for analysis or surface modification in nanometer dimension has been developed. High aspect ratio tip structures are shaped combining isotropic and anisotropic deep reactive etch processes to form the body of the transducer. In this way, tips with an aspect ratio higher than 20 and a tip radius of smaller than 50 nm can be achieved. Subsequently, a three-layer system (an isolation layer: silicon nitride, a metal layer: platinum or gold and an isolation layer: silicon nitride) was deposited on the tip structure. Planarization of this structure in combination with a back etch process enables a precise exposure of the buried metal layer down to an electrode dimension of 200 nm on the tip. Electrochemical and impedance spectroscopic characterization showed full electrochemical functionality of the transducer system. Due to the high aspect ratio topography, this probe is particularly suited for Scanning Electrochemical Microscope (SECM) - methodologies. Furthermore this technology promises a feasible production possibility for both probe-arrays and probes on cantilevers.

  16. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yibing, E-mail: ybxie@seu.edu.cn; Zhao, Ye

    2013-12-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO{sub 2}) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity.

  17. Tangent hyperbolic circular frequency diverse array radars

    Directory of Open Access Journals (Sweden)

    Sarah Saeed

    2016-03-01

    Full Text Available Frequency diverse array (FDA with uniform frequency offset (UFO has been in spot light of research for past few years. Not much attention has been devoted to non-UFOs in FDA. This study investigates tangent hyperbolic (TH function for frequency offset selection scheme in circular FDAs (CFDAs. Investigation reveals a three-dimensional single-maximum beampattern, which promises to enhance system detection capability and signal-to-interference plus noise ratio. Furthermore, by utilising the versatility of TH function, a highly configurable type array system is achieved, where beampatterns of three different configurations of FDA can be generated, just by adjusting a single function parameter. This study further examines the utility of the proposed TH-CFDA in some practical radar scenarios.

  18. Nitrogen-Doped TiO2 Nanotube Arrays with Enhanced Photoelectrochemical Property

    Directory of Open Access Journals (Sweden)

    Shipu Li

    2012-01-01

    Full Text Available N-doped TiO2 nanotube arrays were prepared by electrochemical anodization in glycerol electrolyte, followed by electrochemical deposition in NH4Cl solution. An orthogonal experiment was used to optimize the doping conditions. Electrolyte concentration, reaction voltage, and reaction time were the main factors to influence the N-doping effect which was the determinant of the visible range photoresponse. The optimal N-doping conditions were determined as follows: reaction voltage is 3 V, reaction time is 2 h, and electrolyte concentration is 0.5 M. The maximal photocurrent enhanced ratio was 30% under white-light irradiation. About 58% improvement of photocatalytic efficiency was achieved in the Rhodamine B degradation experiment by N doping. The kinetic constant of the N-doped TNT arrays sample was almost twice higher than that of the undoped sample. Further analysis by X-ray photoelectron spectroscopy supported that electrochemical deposition is a simple and efficient method for N doping into TiO2 nanotube arrays.

  19. Electrochemical impedance spectroscopy of oxidized porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mula, Guido, E-mail: guido.mula@unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Tiddia, Maria V. [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Falqui, Andrea [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Palmas, Simonetta; Mascia, Michele [Dipartimento di Ingegneria Meccanica Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d' Armi, 09126 Cagliari (Italy)

    2014-04-01

    We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25–22 μm) and of the applied current density (1.1–11.1 mA/cm{sup 2}, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process. - Highlights: • A multidisciplinary approach on porous Si electrochemical oxidation is proposed. • Electrochemical, optical, and structural characterizations are used. • Layer thickness and oxidation current effects are shown. • An explanation of the observed behavior is proposed.

  20. Electrochemical impedance spectroscopy of oxidized porous silicon

    International Nuclear Information System (INIS)

    We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25–22 μm) and of the applied current density (1.1–11.1 mA/cm2, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process. - Highlights: • A multidisciplinary approach on porous Si electrochemical oxidation is proposed. • Electrochemical, optical, and structural characterizations are used. • Layer thickness and oxidation current effects are shown. • An explanation of the observed behavior is proposed