Determination of sulfuric acid concentration for anti-cavitation characteristics of Al alloy by two step anodizing process to forming nano porous.

PubMed

Lee, Seung-Jun; Kim, Seong-Kweon; Jeong, Jae-Yong; Kim, Seong-Jong

2014-12-01

Al alloy is a highly active metal but forms a protective oxide film having high corrosion resistance in atmosphere environment. However, the oxide film is not suitable for practical use, since the thickness of the film is not uniform and it is severly altered with formation conditions. This study focused on developing an aluminum anodizing layer having hardness, corrosion resistance and abrasion resistance equivalent to a commercial grade protective layer. Aluminum anodizing layer was produced by two-step aluminum anodizing oxide (AAO) process with different sulfuric acid concentrations, and the cavitation characteristics of the anodized coating layer was investigated. In hardness measurement, the anodized coating layer produced with 15 vol.% of sulfuric acid condition had the highest value of hardness but exhibited poor cavitation resistance due to being more brittle than those with other conditions. The 10 vol.% of sulfuric acid condition was thus considered to be the optimum condition as it had the lowest weight loss and damage depth.

A novel compensation method for the anode gain non-uniformity of multi-anode photomultiplier tubes

NASA Astrophysics Data System (ADS)

Lee, Chan Mi; Kwon, Sun Il; Ko, Guen Bae; Ito, Mikiko; Yoon, Hyun Suk; Lee, Dong Soo; Jong Hong, Seong; Lee, Jae Sung

2012-01-01

The position-sensitive multi-anode photomultiplier tube (MA-PMT) is widely used in high-resolution scintillation detectors. However, the anode gain non-uniformity of this device is a limiting factor that degrades the intrinsic performance of the detector module. The aim of this work was to develop a gain compensation method for the MA-PMT and evaluate the resulting enhancement in the performance of the detector. The method employs a circuit that is composed only of resistors and is placed between the MA-PMT and a resistive charge division network (RCN) used for position encoding. The goal of the circuit is to divide the output current from each anode, so the same current flows into the RCN regardless of the anode gain. The current division is controlled by the combination of a fixed-value series resistor with an output impedance that is much larger than the input impedance of the RCN, and a parallel resistor, which detours part of the current to ground. PSpice simulations of the compensation circuit and the RCN were performed to determine optimal values for the compensation resistors when used with Hamamatsu H8500 MA-PMTs. The intrinsic characteristics of a detector module consisting of this MA-PMT and a lutetium-gadolinium-oxyorthosilicate (LGSO) crystal array were tested with and without the gain compensation method. In simulation, the average coefficient of variation and max/min ratio decreased from 15.7% to 2.7% and 2.0 to 1.2, respectively. In the flood map of the LGSO-H8500 detector, the uniformity of the photopeak position for individual crystals and the energy resolution were much improved. The feasibility of the method was shown by applying it to an octagonal prototype positron emission tomography scanner.

Effect of Sn4+ Additives on the Microstructure and Corrosion Resistance of Anodic Coating Formed on AZ31 Magnesium Alloy in Alkaline Solution

NASA Astrophysics Data System (ADS)

Salman, S. A.; Kuroda, K.; Saito, N.; Okido, M.

Magnesium is the lightest structural metal with high specific strength and good mechanical properties. However, poor corrosion resistance limits its widespread use in many applications. Magnesium is usually treated with Chromate conversion coatings. However, due to changing environmental regulations and pollution prevention requirements, a significant push exists to find new, alternative for poisonous Cr6+. Therefore, we aim to improve corrosion resistance of anodic coatings on AZ31 alloys using low cost non-chromate electrolyte. Anodizing was carried out in alkaline solutions with tin additives. The effect of tin additives on the coating film was characterized by SEM and XRD. The corrosion resistance was evaluated using anodic and cathodic polarizations and electrochemical impedance spectroscopy (EIS). Corrosion resistance property was improved with tin additives and the best anti-corrosion property was obtained with addition of 0.03 M Na2SnO3.3H2O to anodizing solution.

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

NASA Technical Reports Server (NTRS)

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

1995-01-01

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

Improved resistive switching characteristics of a Pt/HfO2/Pt resistor by controlling anode interface with forming and switching polarity

NASA Astrophysics Data System (ADS)

Jung, Yong Chan; Seong, Sejong; Lee, Taehoon; Kim, Seon Yong; Park, In-Sung; Ahn, Jinho

2018-03-01

The anode interface effects on the resistive switching characteristics of Pt/HfO2/Pt resistors are investigated by changing the forming and switching polarity. Resistive switching properties are evaluated and compared with the polarity operation procedures, such as the reset voltage (Vr), set voltage (Vs), and current levels at low and high resistance states. When the same forming and switching voltage polarity are applied to the resistor, their switching parameters are widely distributed. However, the opposite forming and switching voltage polarity procedures enhance the uniformity of the switching parameters. In particular, the Vs distribution is strongly affected by the voltage polarity variation. A model is proposed based on cone-shaped filament formation through the insulator and the cone diameter at the anode interface to explain the improved resistive switching characteristics under opposite polarity operation. The filament cone is thinner near the anode interface during the forming process; hence, the anode is altered by the application of a switching voltage with opposite polarity to the forming voltage polarity and the converted anode interface becomes the thicker part of the cone. The more uniform and stable switching behavior is attributed to control over the formation and rupture of the cone-shaped filaments at their thicker parts.

In situ Van der Pauw measurements of the Ni/YSZ anode during exposure to syngas with phosphine contaminant

NASA Astrophysics Data System (ADS)

Demircan, Oktay; Xu, Chunchuan; Zondlo, John; Finklea, Harry O.

Solid oxide fuel cells (SOFCs) represent an option to provide a bridging technology for energy conversion (coal syngas) as well as a long-term technology (hydrogen from biomass). Whether the fuel is coal syngas or hydrogen from biomass, the effect of impurities on the performance of the anode is a vital question. The anode resistivity during SOFC operation with phosphine-contaminated syngas was studied using the in situ Van der Pauw method. Commercial anode-supported solid oxide fuel cells (Ni/YSZ composite anodes, YSZ electrolytes) were exposed to a synthetic coal syngas mixture (H 2, H 2O, CO, and CO 2) at a constant current and their performance evaluated periodically with electrochemical methods (cyclic voltammetry, impedance spectroscopy, and polarization curves). In one test, after 170 h of phosphine exposure, a significant degradation of cell performance (loss of cell voltage, increase of series resistance and increase of polarization resistance) was evident. The rate of voltage loss was 1.4 mV h -1. The resistivity measurements on Ni/YSZ anode by the in situ Van der Pauw method showed that there were no significant changes in anode resistivity both under clean syngas and syngas with 10 ppm PH 3. XRD analysis suggested that Ni 5P 2 and P 2O 5 are two compounds accumulated on the anode. XPS studies provided support for the presence of two phosphorus phases with different oxidation states on the external anode surface. Phosphorus, in a positive oxidation state, was observed in the anode active layer. Based on these observations, the effect of 10 ppm phosphine impurity (or its reaction products with coal syngas) is assigned to the loss of performance of the Ni/YSZ active layer next to the electrolyte, and not to any changes in the thick Ni/YSZ support layer.

Ohmic resistance affects microbial community and ...

EPA Pesticide Factsheets

Multi-anode microbial electrochemical cells (MXCs) are considered as one of the most promising configurations for scale-up of MXCs, but fundamental understanding of anode kinetics governing current density is limited in the MXCs. In this study we first assessed microbial community and electrochemical kinetic parameters for biofilms on individual anodes in a multi-anode MXC to better comprehend anode fundamentals. Microbial community analysis using 16S rRNA illumine sequencing showed that Geobactor genus, one of the most kinetically efficient anode-respiring bacteria (ARB), was abundant (87%) only on the biofilm anode closest to a reference electrode in which current density was the highest among four anodes. In comparison, Geobacter populations were less than 11% for other three anodes more distant from the reference electrode, generating small current density. Half-saturation anode potential (EKA) was the lowest at -0.251 to -0.242 V (vs. standard hydrogen electrode) for the closest anode, while EKA was as high as -0.134 V for the farthest anode. Our study clearly proves that ohmic resistance changes anode potential which mainly causes different biofilm communities on individual anodes and consequently influences anode kinetics. This study explored the use of multiple anodes in microelectrochemical cells and the microbial community on these anodes, as a function of the efficiency in producing hydrogen peroxide.

Electrolytic production of metals using a resistant anode

DOEpatents

Tarcy, Gary P.; Gavasto, Thomas M.; Ray, Siba P.

1986-01-01

An electrolytic process comprising evolving oxygen on an anode in a molten salt, the anode comprising an alloy comprising a first metal and a second metal, both metals forming oxides, the oxide of the first metal being more resistant than the second metal to attack by the molten salt, the oxide of the second metal being more resistant than the first metal to the diffusion of oxygen. The electrode may also be formed of CuAlO.sub.2 and/or Cu.sub.2 O.

Development and Testing of High Surface Area Iridium Anodes for Molten Oxide Electrolysis

NASA Technical Reports Server (NTRS)

Shchetkovskiy, Anatoliy; McKechnie, Timothy; Sadoway, Donald R.; Paramore, James; Melendez, Orlando; Curreri, Peter A.

2010-01-01

Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith is an attractive method of processing, because no additional chemical reagents are needed. The electrochemical processing of molten oxides requires high surface area, inert anodes. Such electrodes need to be structurally robust at elevated temperatures (1400-1600?C), be resistant to thermal shock, have good electrical conductivity, be resistant to attack by molten oxide (silicate), be electrochemically stable and support high current density. Iridium with its high melting point, good oxidation resistance, superior high temperature strength and ductility is the most promising candidate for anodes in high temperature electrochemical processes. Several innovative concepts for manufacturing such anodes by electrodeposition of iridium from molten salt electrolyte (EL-Form? process) were evaluated. Iridium electrodeposition to form of complex shape components and coating was investigated. Iridium coated graphite, porous iridium structure and solid iridium anodes were fabricated. Testing of electroformed iridium anodes shows no visible degradation. The result of development, manufacturing and testing of high surface, inert iridium anodes will be presented.

Development and Testing of High Surface Area Iridium Anodes for Molten Oxide Electrolysis

NASA Technical Reports Server (NTRS)

Shchetkovskiy, Anatoliy; McKechnie, Timothy; Sadoway, Donald R.; Paramore, James; Melendez, Orlando; Curreri, Peter A.

2010-01-01

Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith is an attractive method of processing, because no additional chemical reagents are needed. The electrochemical processing of molten oxides requires high surface area, inert anodes. Such electrodes need to be structurally robust at elevated temperatures (1400-1600 C), be resistant to thermal shock, have good electrical conductivity, be resistant to attack by molten oxide (silicate), be electrochemically stable and support high current density. Iridium with its high melting point, good oxidation resistance, superior high temperature strength and ductility is the most promising candidate for anodes in high temperature electrochemical processes. Several innovative concepts for manufacturing such anodes by electrodeposition of iridium from molten salt electrolyte (EL-Form process) were evaluated. Iridium electrodeposition to form of complex shape components and coating was investigated. Iridium coated graphite, porous iridium structure and solid iridium anodes were fabricated. Testing of electroformed iridium anodes shows no visible degradation. The result of development, manufacturing and testing of high surface, inert iridium anodes will be presented.

A Study on Sealing Process of Anodized Al Alloy Film

NASA Astrophysics Data System (ADS)

Tsujita, Takeshi; Sato, Hiroshi; Tsukahara, Sonoko; Ishikawa, Yuuichi

Since sealing is an important process to improve the corrosion resistance in practical application of anodized aluminum, we prepared anodic oxide films on A5052 alloy in an oxalic acid bath and a sulfuric acid bath, sealed them at various conditions, and analyzed them by scanning electron microscopy, acid-dissolution examination, admittance measurements and infrared spectroscopy. The pore radius of the oxalic acid anodized film was about 5 times larger than that of sulfuric acid anodized film, while the corrosion resistance of the former showed about 2 times higher value than the latter with the same sealed state and amount of hydroxide formed by sealing process of the former was 6 times larger than the latter, respectively. Steam sealing formed dense hydroxide and boiling water sealing formed big coral-like hydroxide, whereas the corrosion resistance of the film sealed by the former showed about 1.5 times higher value than that sealed by the latter, respectively. Thus microstructure of anodic oxide films and their surface morphology after sealing process clearly depended on their anodizing solution and the sealing condition and showed obvious relation to electric and corrosive properties.

Fuzzy Multicriteria Ranking of Aluminium Coating Methods

NASA Astrophysics Data System (ADS)

Batzias, A. F.

2007-12-01

This work deals with multicriteria ranking of aluminium coating methods. The alternatives used are: sulfuric acid anodization, A1; oxalic acid anodization, A2; chromic acid anodization, A3; phosphoric acid anodization, A4; integral color anodizing, A5; chemical conversion coating, A6; electrostatic powder deposition, A7. The criteria used are: cost of production, f1; environmental friendliness of production process, f2; appearance (texture), f3; reflectivity, f4; response to coloring, f5; corrosion resistance, f6; abrasion resistance, f7; fatigue resistance, f8. Five experts coming from relevant industrial units set grades to the criteria vector and the preference matrix according to a properly modified Delphi method. Sensitivity analysis of the ranked first alternative A1 against the `second best', which was A3 at low and A7 at high resolution levels proved that the solution is robust. The dependence of anodized products quality on upstream processes is presented and the impact of energy price increase on industrial cost is discussed.

Resistive anode image converter

NASA Technical Reports Server (NTRS)

Lampton, M. L.; Paresce, F. (Inventor)

1976-01-01

The invention of an apparatus for imaging soft X-ray and ultraviolet electromagnetic radiation and charged particles was described. The apparatus includes a pair of microchannel electron multiplier plates connected in a cascaded chevron configuration which intercepts an incident beam of radiation or charged particles. Incident photons or charged particles strike the front surface of the chevron configuration causing emission of electrons. The electrons are accelerated by a voltage gradient and strike the inner side walls of the individual channels, causing emission of secondary electrons. Accelerated and multiplied secondary electrons impinge upon a resistive anode after they transverse the chevron configuration. A pulse position circuit converts the magnitude or transit time of the currents flowing from the point of impact of the electrons on the resistive anode to four contact electrodes mounted on their periphery of the resistive anode into the spatial coordinates of electron impact.

Electrolytic production of metals using a resistant anode

DOEpatents

Tarcy, G.P.; Gavasto, T.M.; Ray, S.P.

1986-11-04

An electrolytic process is described comprising evolving oxygen on an anode in a molten salt, the anode comprising an alloy comprising a first metal and a second metal, both metals forming oxides, the oxide of the first metal being more resistant than the second metal to attack by the molten salt, the oxide of the second metal being more resistant than the first metal to the diffusion of oxygen. The electrode may also be formed of CuAlO[sub 2] and/or Cu[sub 2]O. 2 figs.

Internal passivation of Al-based microchannel devices by electrochemical anodization

NASA Astrophysics Data System (ADS)

Hymel, Paul J.; Guan, D. S.; Mu, Yang; Meng, W. J.; Meng, Andrew C.

2015-02-01

Metal-based microchannel devices have wide-ranging applications. We report here a method to electrochemically anodize the internal surfaces of Al microchannels, with the purpose of forming a uniform and dense anodic aluminum oxide (AAO) layer on microchannel internal surfaces for chemical passivation and corrosion resistance. A pulsed electrolyte flow was utilized to emulate conventional anodization processes while replenishing depleted ionic species within Al microtubes and microchannels. After anodization, the AAO film was sealed in hot water to close the nanopores. Focused ion beam (FIB) sectioning, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were utilized to characterize the AAO morphology and composition. Potentiodynamic polarization corrosion testing of anodized Al microtube half-sections in a NaCl solution showed an order of magnitude decrease in anodic corrosion current when compared to an unanodized tube. The surface passivation process was repeated for Al-based microchannel heat exchangers. A corrosion testing method based on the anodization process showed higher resistance to ion transport through the anodized specimens than unanodized specimens, thus verifying the internal anodization and sealing process as a viable method for surface passivation of Al microchannel devices.

Biological capacitance studies of anodes in microbial fuel cells using electrochemical impedance spectroscopy.

PubMed

Lu, Zhihao; Girguis, Peter; Liang, Peng; Shi, Haifeng; Huang, Guangtuan; Cai, Lankun; Zhang, Lehua

2015-07-01

It is known that cell potential increases while anode resistance decreases during the start-up of microbial fuel cells (MFCs). Biological capacitance, defined as the apparent capacitance attributed to biological activity including biofilm production, plays a role in this phenomenon. In this research, electrochemical impedance spectroscopy was employed to study anode capacitance and resistance during the start-up period of MFCs so that the role of biological capacitance was revealed in electricity generation by MFCs. It was observed that the anode capacitance ranged from 3.29 to 120 mF which increased by 16.8% to 18-20 times over 10-12 days. Notably, lowering the temperature and arresting biological activity via fixation by 4% para formaldehyde resulted in the decrease of biological capacitance by 16.9 and 62.6%, indicating a negative correlation between anode capacitance and anode resistance of MFCs. Thus, biological capacitance of anode should play an important role in power generation by MFCs. We suggest that MFCs are not only biological reactors and/or electrochemical cells, but also biological capacitors, extending the vision on mechanism exploration of electron transfer, reactor structure design and electrode materials development of MFCs.

Improving the power generation of microbial fuel cells by modifying the anode with single-wall carbon nanohorns.

PubMed

Yang, Jiawei; Cheng, Shaoan; Sun, Yi; Li, Chaochao

2017-10-01

To increase the power generation of microbial fuel cells (MFCs), anode modification with carbon materials (activated carbon, carbon nanotubes, and carbon nanohorns) was investigated. Maximum power densities of a stainless-steel anode MFC with a non-modified electrode (SS-MFC), an activated carbon-modified electrode (AC-MFC), a carbon nanotube-modified electrode (CNT-MFC) and a carbon nanohorn-modified electrode (CNH-MFC) were 72, 244, 261 and 327 mW m -2 , respectively. The total polarization resistance measured by electrochemical impedance spectroscopy were 3610 Ω for SS-MFC, 283 Ω for AC-MFC, 231 Ω for CNTs-MFC, and 136 Ω for CNHs-MFC, consistent with the anode resistances obtained by fitting the anode polarization curves. Single-wall carbon nanohorns are better than activated carbon and carbon nanotubes as a new anode modification material for improving anode performance.

Effect of Adding SiO2-Al2O3 Sol into Anodizing Bath on Corrosion Resistance of Oxidation Film on Magnesium Alloy

NASA Astrophysics Data System (ADS)

Liu, Huicong; Zhu, Liqun; Li, Weiping

Due to the widely use in automobile and construction field, AZ91D magnesium alloy need to be protected more effectively for its high chemical activity. In this paper, three kinds of films were formed on magnesium alloy. The first kind of film, named as anodic oxidation film, was prepared by anodic oxidation in the alkaline solution. The processes for preparing the second kind of film, named as multiple film, involved coating sol-gel on the samples and heat-treating before anodic oxidation. The third kind of film was prepared by anodic oxidation in the alkaline oxidation solution containning 5% (vol) SiO2-Al2O3 sol, named as modified oxidation film. The corrosion resistance of the three different films was investigated. The results showed that the modified oxidation film had the highest corrosion resistance due to the largest thickness and most dense surface morphology. Sol was discussed to react during the film forming process, which leaded to the difference between modified oxidation film and anodic oxidation film.

Low resistance, low-inductance power connectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coteus, Paul W.; Ferencz, Andrew; Hall, Shawn Anthony

An electrical connector includes an anode assembly for conducting an electrical supply current from a source to a destination, the anode assembly includes an anode formed into a first shape from sheet metal or other sheet-like conducting material. A cathode assembly conducts an electrical return current from the destination to the source, the cathode assembly includes a cathode formed into a second shape from sheet metal or other sheet-like conducting material. An insulator prevents electrical conduction between the anode and the cathode. The first and second shapes are such as to provide a conformity of one to the other, withmore » the insulator therebetween having a predetermined relatively thin thickness. A predetermined low-resistance path for the supply current is provided by the anode, a predetermined low-resistance path for the return current is provided by the cathode, and the proximity of the anode to the cathode along these paths provides a predetermined low self-inductance of the connector, where the proximity is afforded by the conformity of the first and second shapes.« less

Optimizing the position resolution of a Z-stack microchannel plate resistive anode detector for low intensity signals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiggins, B. B.; Richardson, E.; Siwal, D.

A method for achieving good position resolution of low-intensity electron signals using a microchannel plate resistive anode detector is demonstrated. Electron events at a rate of 7 counts s{sup −1} are detected using a Z-stack microchannel plate. The dependence of position resolution on both the distance and the potential difference between the microchannel plate and resistive anode is investigated. Using standard commercial electronics, a measured position resolution of 170 μm (FWHM) is obtained, which corresponds to an intrinsic resolution of 157 μm (FWHM)

Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

PubMed

Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

2015-10-13

Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance.

Advances in aluminum anodizing

NASA Technical Reports Server (NTRS)

Dale, K. H.

1969-01-01

White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

Passivated p-type silicon: Hole injection tunable anode material for organic light emission

NASA Astrophysics Data System (ADS)

Zhao, W. Q.; Ran, G. Z.; Xu, W. J.; Qin, G. G.

2008-02-01

We find that hole injection can be enhanced simply by selecting a lower-resistivity p-Si anode to match an electron injection enhancement for organic light emitting diodes with ultrathin-SiO2-layer-passivated p-Si anode (Si-OLED). For a Si-OLED with ordinary AlQ electron transport layer, the optimized resistivity of the p-Si anode is 40Ωcm; for that with n-doped Bphen electron transport layer, it decreases to 5Ωcm. Correspondingly, the maximum power efficiency increases from 0.3to1.9lm /W, even higher than that of an indium tin oxide control device (1.4lm/W). This passivated p-type silicon is a hole injection tunable anode material for OLED.

Performance of Zinc Anodes for Cathodic Protection of Reinforced Concrete Bridges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Covino, Bernard S. Jr.; Cramer, Stephen D.; Bullard, Sophie J.

2002-03-01

Operation of thermal spray zinc (Zn) anodes for cathodic protection (CP) of reinforced concrete structures was investigated in laboratory and field studies conducted by the Albany Research Center (ARC) in collaboration with the Oregon Department of Transportation. The purposes of the research presented in this report were: evaluate the need for preheating concrete to improve the adhesion of the anode; estimate the service life of thermal spray Zn CP anodes; determine the optimum thickness for Zn CP anodes; characterize the anode-concrete interfacial chemistry; and correlate field and laboratory results. Laboratory studies involved accelerated electrochemical aging of thermal sprayed Zn anodesmore » on concrete slabs, some of which were periodically wetted while others were unwetted. Concrete used in the slabs contained either 1.2 or 3 kg NaCl /m3 (2 or 5 lbs NaCl /yd3) as part of the concrete mix design. The Zn anodes were applied to the slabs using the twin wire arc-spray technique. Half of the slabs were preheated to 120-160 C (250-320 F) to improve the initial Zn anode bond strength and the other half were not. Accelerated aging was done at a current density of 0.032 A/m2 (3 mA/ft2), 15 times that used on Oregon DOT Coastal bridges, i.e, . 0.0022 A/m2 (0.2 mA/ft2) Cores from the Cape Creek Bridge (OR), the Richmond San Rafael Bridge (CA), and the East Camino Underpass (CA) were used to study the anode-concrete interfacial chemistry, to relate the chemistry to electrochemical age at the time of sampling, and to compare the chemistry of the field anodes to the chemistry of anodes from the laboratory studies. Cores from a CALTRANS study of a silane sealant used prior to the application of the Zn anodes and cores with galvanized rebar from the Longbird Bridge (Bermuda) were also studied. Aged laboratory and field anodes were characterized by measuring some or all of the following parameters: thickness, bond strength, anode-concrete interfacial chemistry, bulk chemistry, anode resistance, circuit resistance, electrochemical age, and air and water permeability. Models are presented for the operation of periodically-wetted and unwetted thermal spray Zn anodes from the initial energizing of the anode to the end of its service life. The models were developed in terms of bond strength, circuit resistance, anode-concrete interfacial chemistry, electrochemical age, and anode condition. The most significant results of the research are: (1) preheating concrete surfaces prior to coating with Zn is unnecessary; (2) anodes generally fail due to loss of bond strength rather than Zn consumption; (3) Unwetted anodes fail more quickly than periodically-wetted anodes; (4) 0.47-0.60 mm (12-15 mil) anode thickness is adequate for most Oregon DOT coastal impressed current CP (ICCP) installations; (5) based on bond strength, thermal spray Zn ICCP anode service life is approximately 27 years at 0.0022 A/m2 (0.2 mA/ft2); (6) anode reaction products alter the anode-concrete interface by rejecting Ca from the cement paste, by replacing it with Zn, and by the accumulation of a Zn mineral layer that includes chloride and sulfur compounds; (7) CP system circuit resistance provides an effective means for monitoring the condition of Zn ICCP anodes as they age.« less

Effect of the layer of anodized 7075-T6 aluminium corrosion properties

NASA Astrophysics Data System (ADS)

Montoya Z, R. D.; L, E. Vera; Pineda T, Y.; Cedeño, M. L.

2017-01-01

Aluminium alloys are widely used in various sectors of industry. The 7075-T6 alloy corresponding to an Al-Zn T6, is mostly used as structural component in the aviation industry, due to the good relationship between weight and mechanical properties. However, the negative point of this alloys is the resistance to corrosion, which is why they need to be coated with an anodic film. Different surface treatments, such as anodizing, are used to improve corrosion resistance. Anodizing is an electrolytic process by which a protective layer on aluminium known as “alumina” is formed, this is formed by the passage of an electric current in an acidic electrolyte. This investigation presents a study of the effect of the thickness of layers of alumina deposited by anodized method, in the corrosion resistance of 7075-T6 aluminium. This study was performed by using in a solution of tartaric acid - sulfuric acid and an inorganic salt. To evaluate the influence alumina layer thickness on the corrosion properties some tests were carried out by using the electrochemical spectroscopy impedances (EIS) technique and Tafel polarization curves. It was found that the grown of the thickness of film favourably influences in the corrosion resistance.

Materials system for intermediate temperature solid oxide fuel cells based on doped lanthanum-gallate electrolyte

NASA Astrophysics Data System (ADS)

Gong, Wenquan

2005-07-01

The objective of this work was to identify a materials system for intermediate temperature solid oxide fuel cells (IT-SOFCs). Towards this goal, alternating current complex impedance spectroscopy was employed as a tool to study electrode polarization effects in symmetrical cells employing strontium and magnesium doped lanthanum gallate (LSGM) electrolyte. Several cathode materials were investigated including strontium doped lanthanum manganite (LSM), Strontium and iron doped lanthanum cobaltate (LSCF), LSM-LSGM, and LSCF-LSGM composites. Investigated Anode materials included nickel-gadolinium or lanthanum doped cerium oxide (Ni-GDC, or Ni-LDC) composites. The ohmic and the polarization resistances of the symmetrical cells were obtained as a function of temperature, time, thickness, and the composition of the electrodes. Based on these studies, the single phase LSM electrode had the highest polarization resistance among the cathode materials. The mixed-conducting LSCF electrode had polarization resistance orders of magnitude lower than that of the LSM-LSGM composite electrodes. Although incorporating LSGM in the LSCF electrode did not reduce the cell polarization resistance significantly, it could reduce the thermal expansion coefficient mismatch between the LSCF electrodes and LSGM electrolyte. Moreover, the polarization resistance of the LSCF electrode decreased asymptotically as the electrode thickness was increased thus suggesting that the electrode thickness needed not be thicker than this asymptotic limit. On the anode side of the IT-SOFC, Ni reacted with LSGM electrolyte, and lanthanum diffusion occurred from the LSGM electrolyte to the GDC barrier layer, which was between the LSGM electrolyte and the Ni-composite anode. However, LDC served as an effective barrier layer. Ni-LDC (70 v% Ni) anode had the largest polarization resistance, while all other anode materials, i.e. Ni-LDC (50 v% Ni), Ni-GDC (70 v% NO, and Ni-GDC (50 v% Ni), had similar polarization resistances. Ni-LDC (50 v% NO was selected to be the anode for the LSGM electrolyte with a thin LDC barrier layer. Finally, the performance of complete LSGM electrolyte-supported IT-SOFCs with the selected cathode (LSCF-LSGM) and anode (Ni-LDC) materials coupled with the LDC barrier layer was evaluated at 600--800°C. The simulated cell performance of the anode-supported cell based on LSGM electrolyte was promising.

Extremely efficient flexible organic light-emitting diodes with modified graphene anode

NASA Astrophysics Data System (ADS)

Han, Tae-Hee; Lee, Youngbin; Choi, Mi-Ri; Woo, Seong-Hoon; Bae, Sang-Hoon; Hong, Byung Hee; Ahn, Jong-Hyun; Lee, Tae-Woo

2012-02-01

Although graphene films have a strong potential to replace indium tin oxide anodes in organic light-emitting diodes (OLEDs), to date, the luminous efficiency of OLEDs with graphene anodes has been limited by a lack of efficient methods to improve the low work function and reduce the sheet resistance of graphene films to the levels required for electrodes. Here, we fabricate flexible OLEDs by modifying the graphene anode to have a high work function and low sheet resistance, and thus achieve extremely high luminous efficiencies (37.2 lm W-1 in fluorescent OLEDs, 102.7 lm W-1 in phosphorescent OLEDs), which are significantly higher than those of optimized devices with an indium tin oxide anode (24.1 lm W-1 in fluorescent OLEDs, 85.6 lm W-1 in phosphorescent OLEDs). We also fabricate flexible white OLED lighting devices using the graphene anode. These results demonstrate the great potential of graphene anodes for use in a wide variety of high-performance flexible organic optoelectronics.

Thermally oxidized titania nanotubes enhance the corrosion resistance of Ti6Al4V.

PubMed

Grotberg, John; Hamlekhan, Azhang; Butt, Arman; Patel, Sweetu; Royhman, Dmitry; Shokuhfar, Tolou; Sukotjo, Cortino; Takoudis, Christos; Mathew, Mathew T

2016-02-01

The negative impact of in vivo corrosion of metallic biomedical implants remains a complex problem in the medical field. We aimed to determine the effects of electrochemical anodization (60V, 2h) and thermal oxidation (600°C) on the corrosive behavior of Ti-6Al-4V, with serum proteins, at physiological temperature. Anodization produced a mixture of anatase and amorphous TiO2 nanopores and nanotubes, while the annealing process yielded an anatase/rutile mixture of TiO2 nanopores and nanotubes. The surface area was analyzed by the Brunauer-Emmett-Teller method and was estimated to be 3 orders of magnitude higher than that of polished control samples. Corrosion resistance was evaluated on the parameters of open circuit potential, corrosion potential, corrosion current density, passivation current density, polarization resistance and equivalent circuit modeling. Samples both anodized and thermally oxidized exhibited shifts of open circuit potential and corrosion potential in the noble direction, indicating a more stable nanoporous/nanotube layer, as well as lower corrosion current densities and passivation current densities than the smooth control. They also showed increased polarization resistance and diffusion limited charge transfer within the bulk oxide layer. The treatment groups studied can be ordered from greatest corrosion resistance to least as Anodized+Thermally Oxidized > Anodized > Smooth > Thermally Oxidized for the conditions investigated. This study concludes that anodized surface has a potential to prevent long term implant failure due to corrosion in a complex in-vivo environment. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of CrO3 Sealing Time on Anodized A12024-T3

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

Electrically Conductive Anodized Aluminum Surfaces

NASA Technical Reports Server (NTRS)

Nguyen, Trung Hung

2006-01-01

Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to < or = 10(exp 9) Omega-cm. The present treatment does this. The treatment is a direct electrodeposition process in which the outer anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In comparison with these competing finishes, the present nanocomposite finishes are expected to cost 50 to 20 percent less and to last longer.

Origin of high Coulombic loss during sodiation in Na-Sn battery

NASA Astrophysics Data System (ADS)

Byeon, Young-Woon; Choi, Yong-Seok; Ahn, Jae-Pyoung; Lee, Jae-Chul

2017-03-01

Electrochemical sodiation is performed in crystalline Sn foil using in situ scanning electron microscopy (SEM) to simultaneously measure the changes in the electrical resistivity and volume of the Sn anode in a Na-Sn battery. We observe that sodiation causes an increase in the Sn anode resistivity by six orders of magnitude. Ab initio molecular dynamics simulations of the Na-Sn alloy system demonstrate that the increased resistivity of the anode is caused by the formation of an electrically resistive amorphous NaSn phase (a-NaSn) with a pseudogap. It is also observed that the formation of a-NaSn is always accompanied by a large volume expansion of ∼200%, causing the development of residual tensile stress. The residual stress in turn alters the electronic structure of the a-NaSn phase, further increasing the resistivity of a-NaSn and thus decreasing the energy efficiency of the Na-Sn battery.

Hierarchically ordered self-lubricating superhydrophobic anodized aluminum surfaces with enhanced corrosion resistance.

PubMed

Vengatesh, Panneerselvam; Kulandainathan, Manickam Anbu

2015-01-28

Herein, we report a facile method for the fabrication of self-lubricating superhydrophobic hierarchical anodic aluminum oxide (AAO) surfaces with improved corrosion protection, which is greatly anticipated to have a high impact in catalysis, aerospace, and the shipping industries. This method involves chemical grafting of as-formed AAO using low surface free energy molecules like long chain saturated fatty acids, perfluorinated fatty acid (perfluorooctadecanoic acid, PFODA), and perfluorosulfonicacid-polytetrafluoroethylene copolymer. The pre and post treatment processes in the anodization of aluminum (Al) play a vital role in the grafting of fatty acids. Wettability and surface free energy were analyzed using a contact angle meter and achieved 161.5° for PFODA grafted anodized aluminum (PFODA-Al). This study was also aimed at evaluating the surface for corrosion resistance by Tafel polarization and self-lubricating properties by tribological studies using a pin-on-disc tribometer. The collective results showed that chemically grafted AAO nanostructures exhibit high corrosion resistance toward seawater and low frictional coefficient due to low surface energy and self-lubricating property of fatty acids covalently linked to anodized Al surfaces.

Novel strategy to mitigate cathode catalyst degradation during air/air startup cycling via the atmospheric resistive switching mechanism of a hydrogen anode with a platinum catalyst supported on tantalum-doped titanium dioxide

NASA Astrophysics Data System (ADS)

Shintani, Haruhiko; Kojima, Yuya; Kakinuma, Katsuyoshi; Watanabe, Masahiro; Uchida, Makoto

2015-10-01

We propose a new strategy for alleviating the reverse current phenomenon using a unique ;atmospheric resistive switching mechanism; (ARSM) of a metal oxide semiconductor support, such that the electrical resistivity changes depending on the gas atmosphere. The membrane-electrode assembly (MEA) using Ta-doped TiO2-supported platinum (Pt/Ta-TiO2) as the anode catalyst showed approximately one order of magnitude greater resistance in air than in hydrogen. The overpotential of the hydrogen oxidation reaction was negligible up to at least 1.5 A cm-2. The losses of electrochemically active surface area and carbon corrosion of the cathode catalyst during air/air startup cycling were significantly suppressed by the use of the Pt/Ta-TiO2 anode. The decrease in the degradation is attributed to a reduction of the reverse current due to a low oxygen reduction reaction rate at the anode, which showed high resistivity in air. These results demonstrate the effectiveness of the ARSM in mitigating cathode catalyst degradation during air/air startup cycling.

Advanced Photon Counting Imaging Detectors with 100ps Timing for Astronomical and Space Sensing Applications

NASA Astrophysics Data System (ADS)

Siegmund, O.; Vallerga, J.; Welsh, B.; Rabin, M.; Bloch, J.

In recent years EAG has implemented a variety of high-resolution, large format, photon-counting MCP detectors in space instrumentation for satellite FUSE, GALEX, IMAGE, SOHO, HST-COS, rocket, and shuttle payloads. Our scheme of choice has been delay line readouts encoding photon event position centroids, by determination of the difference in arrival time of the event charge at the two ends of a distributed resistive-capacitive (RC) delay line. Our most commonly used delay line configuration is the cross delay line (XDL). In its simplest form the delay-line encoding electronics consists of a fast amplifier for each end of the delay line, followed by time-to-digital converters (TDC's). We have achieved resolutions of < 25 μm in tests over 65 mm x 65 mm (3k x3k resolution elements) with excellent linearity. Using high speed TDC's, we have been able to encode event positions for random photon rates of ~1 MHz, while time tagging events using the MCP output signal to better than 100 ps. The unique ability to record photon X,Y,T high fidelity information has advantages over "frame driven" recording devices for some important applications. For example we have built open face and sealed tube cross delay line detectors used for biological fluorescence lifetime imaging, observation of flare stars, orbital satellites and space debris with the GALEX satellite, and time resolved imaging of the Crab Pulsar with a telescope as small as 1m. Although microchannel plate delay line detectors meet many of the imaging and timing demands of various applications, they have limitations. The relatively high gain (107) reduces lifetime and local counting rate, and the fixed delay (10's of ns) makes multiple simultaneous event recording problematic. To overcome these limitations we have begun development of cross strip readout anodes for microchannel plate detectors. The cross strip (XS) anode is a coarse (~0.5 mm) multi-layer metal and ceramic pattern of crossed fingers on an alumina substrate. The charge cloud is matched to the anode period so that it is collected on several neighboring fingers to ensure an accurate event charge centroid can be determined. Each finger of the anode is connected to a low noise charge sensitive amplifier and followed by subsequent A/D conversion of individual strip charge values and a hardware centroid determination of better than 1/100 of a strip are possible. Recently we have commissioned a full 32 x 32 mm XS open face laboratory detector and demonstrated excellent resolution (<6 μm FWHM, ~5k x 5k resolution) using low MCP gain (<5 x 105) thus increasing the MCP local counting rate capacity and overall lifetime of the detector system. In collaboration with Los Alamos National Laboratory, NASA and NSF we are developing high rate (>107 Hz) XS encoding electronics that will encode temporally simultaneous events (non spatially overlapping). Sealed tube XS detectors with GaAs and other photocathodes are also under development to increase detection efficiency and extend the sensitivity range. This type of sensor could be a significant enabling technology for several important applications, including airborne and space situational awareness, high-speed adaptive optics (by increasing the SNR and speed in the control loop), astronomy of transient and time-variable sources, optical metrology, and secure quantum communication (as a receiver of cryptographic keys for three-dimensional imaging), single-molecule fluorescence lifetime microscopy (simultaneously tracking and measuring ~1000 molecules), optical/NIR LIDAR, hybrid mass spectrometry and optical night-time/reconnaissance (LANL-ASPIRE).

Automatic control and monitoring equipment for cathodic protection of offshore structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morgan, J.H.

1979-10-01

The preferred cathodic-protection systems for offshore structures are (1) the sacrificial-anode form for areas where the anode's weight or wave resistance is not a serious handicap and (2) a combined anode/impressed-current system that reduces the anode mass. Problems associated with controlling and monitoring the equipment are related to the anode locations, suitability of the reference electrodes, instrumentation requirements, interpretation of the measured potentials, and influence of water depth.

Effectiveness of sacrificial anodes in high-resistivity shotcrete repairs.

DOT National Transportation Integrated Search

2005-01-01

This study investigated the use of discrete sacrificial anodes to improve the durability and extend the life of a shotcrete patch repair in a column. Three columns were used in the investigation. In two columns, anodes were placed around the perimete...

Evaluation of electricity production from alkaline pretreated sludge using two-chamber microbial fuel cell.

PubMed

Xiao, Benyi; Yang, Fang; Liu, Junxin

2013-06-15

Electricity production from alkaline pretreated sludge was evaluated using a two-chamber microbial fuel cell (MFC). The electricity production was found to be stable over a long period of time (approximately 17 d) with voltage outputs and power densities of 0.47-0.52 V and 46.80-55.88 mW/m(2), respectively. The anode resistance was the main internal resistance (73.2%) of MFC in the stable stage. Most soluble organic matters (proteins and carbohydrates) in the anode chamber were first degraded and converted into volatile fatty acids (0-15 d), which were then degraded and converted into electricity and methane (15-29 d). The insoluble organics were solubilized thereby decreasing the sludge concentration and reducing the sludge mass. Methane was produced in the anode chamber owing to the growth of methanogens, which did not obviously affect the electricity production. The change in humic-like substances displayed a positive correlation with the electricity production of the MFC. Microbial analysis showed that methanogens and electricity-producing bacteria co-existed mostly on the surface as well as inside the anode. Decreasing the anode resistance and increasing the anode utilization could enhance the electricity production. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Facile incorporation of hydroxyapatite onto an anodized Ti surface via a mussel inspired polydopamine coating

NASA Astrophysics Data System (ADS)

Zhe, Wang; Dong, Chaofang; Sefei, Yang; Dawei, Zhang; Kui, Xiao; Xiaogang, Li

2016-08-01

Inspired by the porous morphology of anodized Ti and the adhesive versatility of polydopamine (PDA), which can induce apatite mineralization, we fabricated a novel interface by coating a porous anodized TiO2 layer with PDA to rapidly immobilize HA on Ti-based substrates. It was found that the as-prepared PDA/anodized (HD) surface exhibited nanoscale roughness, which possessed an excellent ability to form apatite when immersed in 1.5× simulated body fluid (SBF), as observed by AFM and FE-SEM. The morphology and composition of each layer were further confirmed by XPS, XRD and FTIR. The corrosion resistance of the multilayer was investigated using potentiodynamic polarization curve and electrochemical impedance spectra (EIS) measurements in a 0.9 wt% NaCl solution, the results suggested that the HA/PDA/anodized (HDA) layer increased the corrosion resistance of pure Ti with higher corrosion potential and lower passive current, the surface wettability was also enhanced with the incorporation of HA. In vitro cellular assays showed that the HDA layer stimulated cell attachment and improved the alkaline phosphate (ALP) activity. Overall, the PDA/anodized treatment provided a viable method to quickly integrate HA, and the obtained HDA layer improved both corrosion resistance and biocompatibility of the Ti surface.

Ohmic resistance in a multi-anode MxCs

EPA Pesticide Factsheets

A-3txf_sequence summary.xksx: Abundance of contigs or unique sequences for each biofilm samples from anodes in the MEC reactorHodon Waterloo final_fasta_working.docx: Raw sequences with their identification numbersRNA S1_MEC.docx: Representative sequences with their ID number and taxonomyThis dataset is associated with the following publication:Santodomingo, J., H. Ryu, B. Dhar, and H. Lee. Ohmic resistance affects microbial community and electrochemical kinetics in a multi-anode microbial electrochemical cell. JOURNAL OF POWER SOURCES. Elsevier Science Ltd, New York, NY, USA, 331: 315-321, (2016).

Ohmic resistance affects microbial community and electrochemical kinetics in a multi-anode microbial electrochemical cell

EPA Science Inventory

Multi-anode microbial electrochemical cells (MXCs) are considered as one of the most promising configurations for scale-up of MXCs, but fundamental understanding of anode kinetics governing current density is limited in the MXCs. In this study we first assessed microbial communi...

Resistive switching in TiO2 nanocolumn arrays electrochemically grown

NASA Astrophysics Data System (ADS)

Marik, M.; Mozalev, A.; Hubalek, J.; Bendova, M.

2017-04-01

Resistive switching in metal oxides, especially in TiO2, has been intensively investigated for potential application in non-volatile memory microdevices. As one of the working mechanisms, a conducting filament consisting of a substoichiometric oxide phase is created within the oxide layer. With the aim of investigating the filament formation in spatially confined elements, we fabricate arrays of self-ordered TiO2 nanocolumns by porous-anodic-alumina (PAA)-assisted anodizing, incorporate them into solid-state microdevices, study their electron transport properties, and reveal that this anodizing approach is suitable for growing TiO2 nanostructures exhibiting resistive switching. The electrical properties and resistive switching behavior are both dependent on the electrolytic formation conditions, influencing the concentration and distribution of oxygen vacancies in the nanocolumn material during the film growth. Therefore, the PAA-assisted TiO2 nanocolumn arrays can be considered as a platform for investigating various phenomena related to resistive switching in valve metal oxides at the nanoscale.

Multianode cylindrical proportional counter for high count rates

DOEpatents

Hanson, J.A.; Kopp, M.K.

1980-05-23

A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (< 60 keV) at count rates of greater than 10/sup 5/ counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

Multianode cylindrical proportional counter for high count rates

DOEpatents

Hanson, James A.; Kopp, Manfred K.

1981-01-01

A cylindrical, multiple-anode proportional counter is provided for counting of low-energy photons (<60 keV) at count rates of greater than 10.sup.5 counts/sec. A gas-filled proportional counter cylinder forming an outer cathode is provided with a central coaxially disposed inner cathode and a plurality of anode wires disposed in a cylindrical array in coaxial alignment with and between the inner and outer cathodes to form a virtual cylindrical anode coaxial with the inner and outer cathodes. The virtual cylindrical anode configuration improves the electron drift velocity by providing a more uniform field strength throughout the counter gas volume, thus decreasing the electron collection time following the detection of an ionizing event. This avoids pulse pile-up and coincidence losses at these high count rates. Conventional RC position encoding detection circuitry may be employed to extract the spatial information from the counter anodes.

Performance of a Dual Anode Nickel-Hydrogen Cell

NASA Technical Reports Server (NTRS)

Gahn, Randall F.

1991-01-01

Nickel-hydrogen batteries are presently being used for energy storage on satellites in low Earth orbit and in geosynchronous orbit, and have also been selected for use on the proposed Space Station Freedom. Development continues on the cell technology in order to improve the specific energy and lengthen the cycle life. An experimental study was conducted to compare the voltage performance of a nickel-hydrogen cell containing a dual anode with the standard cell design which uses a single hydrogen electrode. Since the principle voltage loss in a nickel-hydrogen cell is attributed to the mass transport and resistive polarization parameters of the nickel electrode, addition of a hydrogen electrode on the other side of the nickel electrode should reduce the electrochemical polarizations by a factor of two. A 3.5 in. diameter boilerplate cell with a single 30 mils thick nickel electrode was cycled under various current conditions to evaluate its performance with a single anode and then with a double anode. A layered separator consisting of one Zircar cloth separator and one radiation-grafted polyethylene separator were used between the electrodes. The electrolyte was 26% KOH, and the tests were done at room temperature. The discharge voltage characteristics were determined as a function of current and depth-of-discharge. At the 4C discharge rate and 50% DOD, the voltage of the dual anode cell was 100 mV higher than the single anode cell. At 75% DOD the dual anode cell voltage was about 130 mV higher than the standard cell design. Resistances of the two c ell designs obtained from the slope of the mid-discharge voltages plotted against various currents indicated that the dual anode cell resistance was one-half of the state-of-the-art cell.

A simplified approach to predict performance degradation of a solid oxide fuel cell anode

NASA Astrophysics Data System (ADS)

Khan, Muhammad Zubair; Mehran, Muhammad Taqi; Song, Rak-Hyun; Lee, Jong-Won; Lee, Seung-Bok; Lim, Tak-Hyoung

2018-07-01

The agglomeration of nickel (Ni) particles in a Ni-cermet anode is a significant degradation phenomenon for solid oxide fuel cells (SOFCs). This work aims to predict the performance degradation of SOFCs due to Ni grain growth by using a simplified approach. Accelerated aging of Ni-scandia stabilized zirconia (SSZ) as an SOFC anode is carried out at 900 °C and subsequent microstructural evolution is investigated every 100 h up to 1000 h using scanning electron microscopy (SEM). The resulting morphological changes are quantified using a two-dimensional image analysis technique that yields the particle size, phase proportion, and triple phase boundary (TPB) point distribution. The electrochemical properties of an anode-supported SOFC are characterized using electrochemical impedance spectroscopy (EIS). The changes of particle size and TPB length in the anode as a function of time are in excellent agreement with the power-law coarsening model. This model is further combined with an electrochemical model to predict the changes in the anode polarization resistance. The predicted polarization resistances are in good agreement with the experimentally obtained values. This model for prediction of anode lifetime provides deep insight into the time-dependent Ni agglomeration behavior and its impact on the electrochemical performance degradation of the SOFC anode.

Effect of Copper and Silicon on Al-5%Zn Alloy as a Candidate Low Voltage Sacrificial Anode

NASA Astrophysics Data System (ADS)

Pratesa, Yudha; Ferdian, Deni; Togina, Inez

2017-05-01

One common method used for corrosion protection is a sacrificial anode. Sacrificial anodes that usually employed in the marine environment are an aluminum alloy sacrificial anode, especially Al-Zn-In. However, the electronegativity of these alloys can cause corrosion overprotection and stress cracking (SCC) on a high-strength steel. Therefore, there is a development of the sacrificial anode aluminum low voltage to reduce the risk of overprotection. The addition of alloying elements such as Cu, Si, and Ge will minimize the possibility of overprotection. This study was conducted to analyze the effect of silicon and copper addition in Al-5Zn. The experiment started from casting the sacrificial anode aluminum uses electrical resistance furnace in a graphite crucible in 800°C. The results alloy was analyzed using Optical emission spectroscopy (OES), Differential scanning calorimetry, electrochemical impedance spectroscopy, and metallography. Aluminum alloy with the addition of a copper alloy is the most suitable and efficient to serve as a low-voltage sacrificial anode aluminum. Charge transfer resistivity of copper is smaller than silicon which indicates that the charge transfer between the metal and the electrolyte is easier t to occur. Also, the current potential values in coupling with steel are also in the criteria range of low-voltage aluminum sacrificial anodes.

Sulfur poisoning of Ni/Gadolinium-doped ceria anodes: A long-term study outlining stable solid oxide fuel cell operation

NASA Astrophysics Data System (ADS)

Riegraf, Matthias; Zekri, Atef; Knipper, Martin; Costa, Rémi; Schiller, Günter; Friedrich, K. Andreas

2018-03-01

This work presents an analysis of the long-term behavior of nickel/gadolinium-doped ceria (CGO) anode-based solid oxide fuel cells (SOFC) under sulfur poisoning conditions. A parameter study of sulfur-induced irreversible long-term degradation of commercial, high-performance single cells was carried out at 900 °C for different H2/N2/H2S fuel gas atmospheres, current densities and Ni/CGO anodes. The poisoning periods of the cells varied from 200 to 1500 h. The possibility of stable long-term Ni/CGO anode operation under sulfur exposure is established and the critical operating regime is outlined. Depending on the operating conditions, two degradation phenomena can be observed. Small degradation of the ohmic resistance was witnessed for sulfur exposure times of approximately 1000 h. Moreover, degradation of the anode charge transfer resistance was observed to be triggered by the combination of a small anodic potential step and high sulfur coverage on Ni. The microstructural evolution of altered Ni/CGO anodes was examined post-mortem by means of SEM and FIB/SEM, and is correlated to the anode performance degradation under critical operating conditions, establishing Ni depletion, porosity increase and a tripe phase boundary density decrease in the anode functional layer. It is shown that short-term sulfur poisoning behavior can be used to assess long-term stability.

Laser-Ultrasonic Measurement of Elastic Properties of Anodized Aluminum Coatings

NASA Astrophysics Data System (ADS)

Singer, F.

Anodized aluminum oxide plays a great role in many industrial applications, e.g. in order to achieve greater wear resistance. Since the hardness of the anodized films strongly depends on its processing parameters, it is important to characterize the influence of the processing parameters on the film properties. In this work the elastic material parameters of anodized aluminum were investigated using a laser-based ultrasound system. The anodized films were characterized analyzing the dispersion of Rayleigh waves with a one-layer model. It was shown that anodizing time and temperature strongly influence Rayleigh wave propagation.

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

PubMed

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

2015-07-29

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

Stabilizing contact resistance of isotropically conductive adhesives on various metal surfaces by incorporating sacrificial anode materials

NASA Astrophysics Data System (ADS)

Moon, Kyoung-Sik; Liong, Silvia; Li, Haiying; Wong, C. P.

2004-11-01

The contact resistance stability of isotropically conductive adhesives (ICAs) on non-noble metal surfaces under the 85°C/85% relative humidity (RH) aging test was investigated. Previously, we demonstrated that galvanic corrosion has been shown as the main mechanism of the unstable contact resistance of ICAs on non-noble metal surfaces. A sacrificial anode was introduced into the ICA joint for cathodic protection. Zinc, chromium, and magnesium were employed in the ICA formulations as sacrificial anode materials that have much lower electrode-potential values than the metal pad surface, such as tin or tin-based alloys. The effect of particle sizes and loading levels of sacrificial anode materials were studied. Chromium was not as effective in suppressing corrosion as magnesium or zinc because of its strong tendency to self-passivate. The corrosion potential of ICAs was reduced by half with the addition of zinc and magnesium into the ICA formulation. The addition of zinc and magnesium was very effective in controlling galvanic corrosion that takes place in the ICA joints, resulting in stabilized contact resistance of ICAs on Sn, SnPb, and SnAgCu surfaces during the 85°C/85% RH aging test.

Electricity generation and brewery wastewater treatment from sequential anode-cathode microbial fuel cell.

PubMed

Wen, Qing; Wu, Ying; Zhao, Li-xin; Sun, Qian; Kong, Fan-ying

2010-02-01

A sequential anode-cathode double-chamber microbial fuel cell (MFC), in which the effluent of anode chamber was used as a continuous feed for an aerated cathode chamber, was constructed in this experiment to investigate the performance of brewery wastewater treatment in conjugation with electricity generation. Carbon fiber was used as anode and plain carbon felt with biofilm as cathode. When hydraulic retention time (HRT) was 14.7 h, a relatively high chemical oxygen demand (COD) removal efficiency of 91.7%-95.7% was achieved under long-term stable operation. The MFC displayed an open circuit voltage of 0.434 V and a maximum power density of 830 mW/m(3) at an external resistance of 300 Omega. To estimate the electrochemical performance of the MFC, electrochemical measurements were carried out and showed that polarization resistance of anode was the major limiting factor in the MFC. Since a high COD removal efficiency was achieved, we conclude that the sequential anode-cathode MFC constructed with bio-cathode in this experiment could provide a new approach for brewery wastewater treatment.

Anodic concentration loss and impedance characteristics in rotating disk electrode microbial fuel cells.

PubMed

Shen, Liye; Ma, Jingxing; Song, Pengfei; Lu, Zhihao; Yin, Yao; Liu, Yongdi; Cai, Lankun; Zhang, Lehua

2016-10-01

A rotating disk electrode (RDE) was used to investigate the concentration loss and impedance characteristics of anodic biofilms in microbial fuel cells (MFCs). Amperometric time-current analysis revealed that at the rotation rate of 480 rpm, a maximum current density of 168 µA cm(-2) can be achieved, which was 22.2 % higher than when there was no rotation. Linear sweep voltammetry and electrochemical impedance spectroscopy tests showed that when the anodic potential was set to -300 mV vs. Ag/AgCl reference, the power densities could increase by 59.0  %, reaching 1385 mW m(-2), the anodic resistance could reduce by 19  %, and the anodic capacitance could increase by 36 %. These results concur with a more than 85 % decrease of the diffusion layer thickness. Data indicated that concentration loss, diffusion layer thickness, and the mixing velocity play important roles in anodic resistance reduction and power output of MFCs. These findings could be helpful to the design of future industrial-scale MFCs with mixed bacteria biofilms.

Electricity generation and brewery wastewater treatment from sequential anode-cathode microbial fuel cell*

PubMed Central

Wen, Qing; Wu, Ying; Zhao, Li-xin; Sun, Qian; Kong, Fan-ying

2010-01-01

A sequential anode-cathode double-chamber microbial fuel cell (MFC), in which the effluent of anode chamber was used as a continuous feed for an aerated cathode chamber, was constructed in this experiment to investigate the performance of brewery wastewater treatment in conjugation with electricity generation. Carbon fiber was used as anode and plain carbon felt with biofilm as cathode. When hydraulic retention time (HRT) was 14.7 h, a relatively high chemical oxygen demand (COD) removal efficiency of 91.7%–95.7% was achieved under long-term stable operation. The MFC displayed an open circuit voltage of 0.434 V and a maximum power density of 830 mW/m3 at an external resistance of 300 Ω. To estimate the electrochemical performance of the MFC, electrochemical measurements were carried out and showed that polarization resistance of anode was the major limiting factor in the MFC. Since a high COD removal efficiency was achieved, we conclude that the sequential anode-cathode MFC constructed with bio-cathode in this experiment could provide a new approach for brewery wastewater treatment. PMID:20104642

Large area organic light emitting diodes with multilayered graphene anodes

NASA Astrophysics Data System (ADS)

Moon, Jaehyun; Hwang, Joohyun; Choi, Hong Kyw; Kim, Taek Yong; Choi, Sung-Yool; Joo, Chul Woong; Han, Jun-Han; Shin, Jin-Wook; Lee, Bong Joon; Cho, Doo-Hee; Huh, Jin Woo; Park, Seung Koo; Cho, Nam Sung; Chu, Hye Yong; Lee, Jeong-Ik

2012-09-01

In this work, we demonstrate fully uniform blue fluorescence graphene anode OLEDs, which have an emission area of 10×7 mm2. Catalytically grown multilayered graphene films have been used as the anode material. In order to compensate the current drop, which is due to the graphene's electrical resistance, we have furnished metal bus lines on the support. Processing and optical issues involved in graphene anode OLED fabrications are presented. The fabricated OLEDs with graphene anode showed comparable performances to that of ITO anode OLEDs. Our works shows that metal bus furnished graphene anode can be extended into large area OLED lighting applications in which flexibility and transparency is required.

Patterned titania nanostructures produced by electrochemical anodization of titanium sheet

NASA Astrophysics Data System (ADS)

Dong, Junzhe; Ariyanti, Dessy; Gao, Wei; Niu, Zhenjiang; Weil, Emeline

2017-07-01

A two-step anodization method has been used to produce patterned arrays of TiO2 on the surface of Ti sheet. Hexagonal ripples were created on Ti substrate after removing the TiO2 layer produced by first-step anodization. The shallow concaves were served as an ideal position for the subsequent step anodization due to their low electrical resistance, resulting in novel hierarchical nanostructures with small pits inside the original ripples. The mechanism of morphology evolution during patterned anodization was studied through changing the anodizing voltages and duration time. This work provides a new idea for controlling nanostructures and thus tailoring the photocatalytic property and wettability of anodic TiO2.

Determining localized anode condition to maintain effective corrosion protection.

DOT National Transportation Integrated Search

2010-01-01

Thermal sprayed zinc anodes used for impressed current cathodic protection of reinforced concrete deteriorate over time. : Two different technologies, ultrasound and electrical circuit resistance combined with water permeability, were : investigated ...

Parasitic corrosion resistant anode for use in metal/air or metal/O.sub.2 cells

DOEpatents

Joy, Richard W.; Smith, David F.

1983-01-01

A consumable metal anode which is used in refuelable electrochemical cells and wherein at least a peripheral edge portion of the anode is protected against a corrosive alkaline environment of the cell by the application of a thin metal coating, the coating being formed of metals such as nickel, silver, and gold.

Analysis of carbon fiber brush loading in anodes on startup and performance of microbial fuel cells

NASA Astrophysics Data System (ADS)

Hutchinson, Adam J.; Tokash, Justin C.; Logan, Bruce E.

Flat carbon anodes placed near a cathode in a microbial fuel cell (MFC) are adversely affected by oxygen crossover, but graphite fiber brush anodes placed near the cathode produce high power densities. The impact of the brush size and electrode spacing was examined by varying the distance of the brush end from the cathode and solution conductivity in multiple MFCs. The startup time was increased from 8 ± 1 days with full brushes (all buffer concentrations) to 13 days (50 mM), 14 days (25 mM) and 21 days (8 mM) when 75% of the brush anode was removed. When MFCs were all first acclimated with a full brush, up to 65% of the brush material could be removed without appreciably altering maximum power. Electrochemical impedance spectroscopy (EIS) showed that the main source of internal resistance (IR) was diffusion resistance, which together with solution resistance reached 100 Ω. The IR using EIS compared well with that obtained using the polarization data slope method, indicating no major components of IR were missed. These results show that using full brush anodes avoids adverse effects of oxygen crossover during startup, although brushes are much larger than needed to sustain high power.

FLUORINE CELL ANODE ASSEMBLY

DOEpatents

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

1962-06-26

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

Anodizing And Sealing Aluminum In Nonchromated Solutions

NASA Technical Reports Server (NTRS)

Emmons, John R.; Kallenborn, Kelli J.

1995-01-01

Improved process for anodizing and sealing aluminum involves use of 5 volume percent sulfuric acid in water as anodizing solution, and 1.5 to 2.0 volume percent nickel acetate in water as sealing solution. Replaces process in which sulfuric acid used at concentrations of 10 to 20 percent. Improved process yields thinner coats offering resistance to corrosion, fatigue life, and alloy-to-alloy consistency equal to or superior to those of anodized coats produced with chromated solutions.

Method for providing uranium articles with a corrosion resistant anodized coating

DOEpatents

Waldrop, Forrest B.; Washington, Charles A.

1982-01-01

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, Seong Jin; Li, Jianlin; Daniel, Claus

Simple three-electrode pouch cells which can be used in distinguishing the voltage and resistance in individual electrodes of lithium ion batteries have been designed. Baseline (1 mm-staggered alignment, cathode away from a reference electrode) and aligned electrodes to a reference electrode located outside of the anode and cathode were studied to see alignment effects on resistance analysis. Cells composed of A12 graphite anodes, LiNi 0.5Mn 0.3Co 0.2O 2 (NMC 532 or NCM 523) cathodes, lithium foil references, microporous tri-layer membranes, and electrolytes, were cycled with cathode cutoff voltages between 3.0 V and 4.3 V for formation cycles or 4.6 Vmore » for C-rate performance testing. By applying a hybrid pulse power characterization (HPPC) technique to the cells, resistances of the baseline cells contributed by the anode and cathode were found to be different from those of the aligned cells, although overall resistances were close to ones from aligned cells. As a result, resistances obtained via electrochemical impedance spectroscopy (EIS) and 2D simulation were also compared with those obtained from HPPC.« less

Electrochemical performance and carbon deposition resistance of M-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (M = Pd, Cu, Ni or NiCu) anodes for solid oxide fuel cells

PubMed Central

Li, Meng; Hua, Bin; Pu, Jian; Chi, Bo; Jian, Li

2015-01-01

Pd-, Cu-, Ni- and NiCu-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ anodes, designated as M-BZCYYb, were prepared by impregnating M-containing solution into BZCYYb scaffold, and investigated in the aspects of electrocatalytic activity for the reactions of H2 and CH4 oxidation and the resistance to carbon deposition. Impregnation of Pd, Ni or NiCu significantly reduced both the ohmic (RΩ) and polarization (RP) losses of BZCYYb anode exposed to H2 or CH4, while Cu impregnation decreased only RΩ in H2 and the both in CH4. Pd-, Ni- and NiCu-BZCYYb anodes were resistant to carbon deposition in wet (3 mol. % H2O) CH4 at 750°C. Deposited carbon fibers were observed in Pd- and Ni-BZCYYb anodes exposed to dry CH4 at 750°C for 12 h, and not observed in NiCu-BZCYYb exposed to dry CH4 at 750°C for 24 h. The performance of a full cell with NiCu-BZCYYb anode, YSZ electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd doped CeO2 (LSCF-GDC) cathode was stable at 750°C in wet CH4 for 130 h, indicating that NiCu-BZCYYb is a promising anode for direct CH4 solid oxide fuel cells (SOFCs). PMID:25563843

Characterization of the corrosion resistance of biologically active solutions: The effects of anodizing and welding

NASA Technical Reports Server (NTRS)

Walsh, Daniel W.

1991-01-01

An understanding of fabrication processes, metallurgy, electrochemistry, and microbiology is crucial to the resolution of microbiologically influenced corrosion (MIC) problems. The object of this effort was to use AC impedance spectroscopy to characterize the corrosion resistance of Type II anodized aluminum alloy 2219-T87 in sterile and biologically active media and to examine the corrosion resistance of 316L, alloy 2219-T87, and titanium alloy 6-4 in the welded and unwelded conditions. The latter materials were immersed in sterile and biologically active media and corrosion currents were measured using the polarization resistance (DC) technique.

Laboratory performance of zinc anodes for impressed current cathodic protection of reinforced concrete

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brousseau, R.; Arnott, M.; Baldock, B.

1995-08-01

Cathodic protection is used increasingly to mitigate steel reinforcement corrosion in concrete. the performance of zinc materials as impressed current anodes was evaluated. The anode materials investigated included rolled zinc sheets, metallized zinc, and 85% Zn-15% Al. The circuit resistance and the adhesion of the anodes was monitored with polarization time. Overall performance of arc-sprayed zinc was good. However, its adhesion to the concrete surface slowly decreased as the current density, or the polarization period, increased. Penny blank sheets and metallized 85% Zn-15% Al were found unsuitable as impressed current anodes.

Parasitic corrosion-resistant anode for use in metal/air or metal/O/sub 2/ cells

DOEpatents

Joy, R.W.; Smith, D.F.

1982-09-20

A consumable metal anode is described which is used in refuelable electrochemical cells and wherein at least a peripheral edge portion of the anode is protected against a corrosive alkaline environment of the cell by the application of a thin metal coating, the coating being formed of metals such as nickel, silver, and gold.

Dual-Anode Nickel/Hydrogen Cell

NASA Technical Reports Server (NTRS)

Gahn, Randall F.; Ryan, Timothy P.

1994-01-01

Use of two hydrogen anodes in nickel/hydrogen cell reduces ohmic and concentration polarizations contributing to internal resistance, yielding cell with improved discharging performance compared to single-anode cell. Dual-anode concept incorporated into nickel/hydrogen cells of individual pressure-vessel type (for use aboard spacecraft) and common pressure-vessel type, for use on Earth to store electrical energy from photovoltaic sources, "uninterruptible" power supplies of computer and telephone systems, electric vehicles, and load leveling on power lines. Also applicable to silver/hydrogen and other metal/gas batteries.

Fabrication and electrochemical performance of nickel- and gadolinium-doped ceria-infiltrated La0·2Sr0·8TiO3 anodes for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Lee, Min-Jin; Shin, Jae-Hwa; Ji, Mi-Jung; Hwang, Hae-Jin

2018-01-01

In this work, nickel and gadolinium-doped ceria (GDC)-infiltrated lanthanum strontium titanate (LST) anodes are fabricated, and their electrode performances under a hydrogen atmosphere is investigated in terms of the Ni:GDC ratios and cell operating temperature. The Ni/GDC-infiltrated LST anode exhibits excellent electrode performance in comparison with the Ni- or GDC-infiltrated anodes, which is attributed to the synergistic effect of an extended triple-phase boundary length by GDC and good catalytic activity for hydrogen oxidation because of the Ni particles. The polarization resistances (Rp) of Ni/GDC-infiltrated LST are 0.07, 0.08, and 0.12 Ω cm2 at 800, 750, and 700 °C, respectively, which are approximately three orders of magnitude lower than that of the LST anode (68.5 Ω cm2 at 700 °C). The effect of Ni and GDC on the electrochemical performance of LST was also investigated by using electrochemical impedance spectroscopy (EIS). The anode polarization resistance (Rp) is confirmed to be dependent on the content and dispersion state (microstructure) of the Ni and GDC nanoparticles.

Surface characterization of anodized zirconium for biomedical applications

NASA Astrophysics Data System (ADS)

Sanchez, A. Gomez; Schreiner, W.; Duffó, G.; Ceré, S.

2011-05-01

Mechanical properties and corrosion resistance of zirconium make this material suitable for biomedical implants. Its good in vivo performance is mainly due to the presence of a protective oxide layer that minimizes corrosion rate, diminishes the amount of metallic ions released to the biological media and facilitates the osseointegration process. Since the implant surface is the region in contact with living tissues, the characteristics of the surface film are of great interest. Surface modification is a route to enhance both biocompatibility and corrosion resistance of permanent implant materials. Anodizing is presented as an interesting process to modify metal surfaces with good reproducibility and independence of the geometry. In this work the surface of zirconium before and after anodizing in 1 mol/L phosphoric acid solution at a fixed potential between 3 and 30 V, was characterized by means of several surface techniques. It was found that during anodization the surface oxide grows with an inhomogeneous coverage on zirconium surface, modifying the topography. The incorporation of P from the electrolyte to the surface oxide during the anodizing process changes the surface chemistry. After 30 days of immersion in Simulated Body Fluid (SBF) solution, Ca-P rich compounds were present on anodized zirconium.

[Effect of the initial anode potential on electricity generation in microbial fuel cell].

PubMed

Fan, Ming-Zhi; Liang, Peng; Cao, Xiao-Xin; Huang, Xia

2008-01-01

The initial anode potential of the microbial fuel cell (MFC) was changed by additional circuit in the anode chamber, and the influence of the initial anode potential on the electricigens was studied. When the initial anode potential was 350 mV (vs Hg/Hg2 Cl2), the growth of microorganisms was much slower than that of the microorganisms which grew on the anode with an initial potential of -200 mV or 200 mV (vs Hg/Hg2 Cl2). After stable electricity generation, the anode resistances of the three MFCs, which had initial anode potentials of 350 mV, 200 mV and -200 mV respectively, were 71 Omega, 43 Omega and 80 Omega. The community structures in MFCs, before and after the electricity generation, were also studied by denaturing gradient gel electrophoresis (DGGE). Clostridium sticklandii, Pseudomonas mendocina and Paenibacillus taejonensis were the three most enriched strains on the anode.

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

DOEpatents

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

1981-01-07

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

The Effect of Silane on the Microstructure, Corrosion, and Abrasion Resistances of the Anodic Films on Ti Alloy

NASA Astrophysics Data System (ADS)

Wang, Jinwei; Chen, Jiali

2016-04-01

Anodic oxide films on Ti-6Al-4V alloy are prepared using sodium hydroxide as the base electrolyte containing aminopropyl trimethoxysilane (APS) as an additive. Some APS undergo hydrolysis, adsorption, and chemical reaction with the TiO x to form Ti-O-Si bond as confirmed by ATR-FTIR and XPS spectra, and in turn their surface appearance and roughness are greatly changed with the addition of APS as observed by their SEM images. These amino anodic films possess much higher corrosive resistances since the formation of Ti-O-Si complex enhances the compactness of the anodic films and the existence of aminopropyl groups inside the pores provides additional blocking effects. Besides, their improvement in anti-abrasive capability is attributed to the toughening effect of the chemically bonded silanes and the lubrication functions from both the chemically bonded and physically absorbed silanes between the touched interfaces.

Highly efficient phosphorescent organic light-emitting diode with a nanometer-thick Ni silicide/polycrystalline p-Si composite anode.

PubMed

Li, Y Z; Wang, Z L; Luo, H; Wang, Y Z; Xu, W J; Ran, G Z; Qin, G G; Zhao, W Q; Liu, H

2010-07-19

A phosphorescent organic light-emitting diode (PhOLED) with a nanometer-thick (approximately 10 nm) Ni silicide/ polycrystalline p-Si composite anode is reported. The structure of the PhOLED is Al mirror/ glass substrate / Si isolation layer / Ni silicide / polycrystalline p-Si/ V(2)O(5)/ NPB/ CBP: (ppy)(2)Ir(acac)/ Bphen/ Bphen: Cs(2)CO(3)/ Sm/ Au/ BCP. In the composite anode, the Ni-induced polycrystalline p-Si layer injects holes into the V(2)O(5)/ NPB, and the Ni silicide layer reduces the sheet resistance of the composite anode and thus the series resistance of the PhOLED. By adopting various measures for specially optimizing the thickness of the Ni layer, which induces Si crystallization and forms a Ni silicide layer of appropriate thickness, the highest external quantum efficiency and power conversion efficiency have been raised to 26% and 11%, respectively.

Solution processible MoOx-incorporated graphene anode for efficient polymer light-emitting diodes

NASA Astrophysics Data System (ADS)

Lee, Dongchan; Kim, Donghyuk; Lee, Yonghee; Jeon, Duk Young

2017-06-01

Graphene has attracted great attention owing to its superb properties as an anode of organic or polymer light-emitting diodes (OLEDs or PLEDs). However, there are still barriers for graphene to replace existing indium tin oxide (ITO) due to relatively high sheet resistance and work function mismatch. In this study, PLEDs using molybdenum oxide (MoOx) nanoparticle-doped graphene are demonstrated on a plastic substrate to have a low sheet resistance and high work function. Also, this work shows how the doping amount influences the electronic properties of the graphene anode and the PLED performance. A facile and scalable spin coating process was used for doping graphene with MoOx. After doping, the sheet resistance and the optical transmittance of five-layer graphene were ˜180 Ω sq-1 and ˜88%, respectively. Moreover, the surface roughness of MoOx-doped graphene becomes smoother than that of pristine graphene. Furthermore, a nonlinear relationship was observed between the MoOx doping level and device performance. Therefore, a modified stacking structure of graphene electrode is presented to further enhance device performance. The maximum external quantum efficiency (EQE) and power efficiency of the PLED using the MoOx-doped graphene anode were 4.7% and 13.3 lm W-1, respectively. The MoOx-doped graphene anode showed enhanced device performance (261% for maximum EQE, 255% for maximum power efficiency) compared with the pristine graphene.

High-speed MCP anodes for high time resolution low-energy charged particle spectrometers

NASA Astrophysics Data System (ADS)

Saito, Yoshifumi; Yokota, Shoichiro; Asamura, Kazushi; Krieger, Amanda

2017-02-01

The time resolution of low-energy charged particle measurements is becoming higher and higher. In order to realize high time resolution measurements, a 1-D circular delay line anode has been developed as a high-speed microchannel plate (MCP) anode. The maximum count rate of the 1-D circular delay line anode is around 1 × 107/s/360°, which is much higher than the widely used resistive anode, whose maximum count rate is around 1 × 106/s/360°. In order to achieve much higher speeds, an MCP anode with application-specific integrated circuit (ASIC) has been developed. We have decided to adopt an anode configuration in which a discrete anode is formed on a ceramic substrate, and a bare ASIC chip is installed on the back of the ceramic. It has been found that the anode can detect at a high count rate of 2 × 108/s/360°. Developments in both delay line and discrete anodes, as well as readout electronics, will be reviewed.

Improved coking resistance of direct ethanol solid oxide fuel cells with a Ni-Sx anode

NASA Astrophysics Data System (ADS)

Yan, Ning; Luo, Jing-Li; Chuang, Karl T.

2014-03-01

In this study, the coking resistance of anode supported direct ethanol solid oxide fuel cell with a Ni-Sx anode was investigated comparatively with the conventional cell using pure Ni catalyst. The surface catalytic properties of Ni were manipulated via depositing a layer of S atoms. It was confirmed that on the surface of Ni, a combination of S monolayer and elemental S was formed without producing Ni3S2 phase. The developed Ni-Sx cell exhibited a significantly improved coke resistivity in ethanol feed while maintaining an adequately high performance. The S species on Ni enabled the suppression of the coke formation as well as the alleviation of the metal dusting effect of the anode structure. After operating in ethanol fuel for identical period of time at 850 °C, a maximum power density of 400 mW cm-2 was sustained whereas the conventional cell performance decreased to less than 40 mW cm-2 from the original 704 mW cm-2. In an optimized stability test, the Ni-Sx cell operated at 750 °C for more than 22 h until the fuel drained without any degradation.

Electrochemical properties of tin oxide anodes for sodium-ion batteries

NASA Astrophysics Data System (ADS)

Lu, Ying Ching; Ma, Chuze; Alvarado, Judith; Kidera, Takafumi; Dimov, Nikolay; Meng, Ying Shirley; Okada, Shigeto

2015-06-01

Few tin (Sn)-oxide based anode materials have been found to have large reversible capacity for both sodium (Na)-ion and lithium (Li)-ion batteries. Herein, we report the synthesis and electrochemical properties of Sn oxide-based anodes for sodium-ion batteries: SnO, SnO2, and SnO2/C. Among them, SnO is the most suitable anode for Na-ion batteries with less first cycle irreversibility, better cycle life, and lower charge transfer resistance. The energy storage mechanism of the above-mentioned Sn oxides was studied, which suggested that the conversion reaction of the Sn oxide anodes is reversible in Na-ion batteries. The better anode performance of SnO is attributed by the better conductivity.

Design and Demonstration of Three-Electrode Pouch Cells for Lithium-Ion Batteries

DOE PAGES

An, Seong Jin; Li, Jianlin; Daniel, Claus; ...

2017-06-14

Simple three-electrode pouch cells which can be used in distinguishing the voltage and resistance in individual electrodes of lithium ion batteries have been designed. Baseline (1 mm-staggered alignment, cathode away from a reference electrode) and aligned electrodes to a reference electrode located outside of the anode and cathode were studied to see alignment effects on resistance analysis. Cells composed of A12 graphite anodes, LiNi 0.5Mn 0.3Co 0.2O 2 (NMC 532 or NCM 523) cathodes, lithium foil references, microporous tri-layer membranes, and electrolytes, were cycled with cathode cutoff voltages between 3.0 V and 4.3 V for formation cycles or 4.6 Vmore » for C-rate performance testing. By applying a hybrid pulse power characterization (HPPC) technique to the cells, resistances of the baseline cells contributed by the anode and cathode were found to be different from those of the aligned cells, although overall resistances were close to ones from aligned cells. As a result, resistances obtained via electrochemical impedance spectroscopy (EIS) and 2D simulation were also compared with those obtained from HPPC.« less

Non-consumable anode and lining for aluminum electrolytic reduction cell

DOEpatents

Beck, Theodore R.; Brooks, Richard J.

1994-01-01

An oxidation resistant, non-consumable anode, for use in the electrolytic reduction of alumina to aluminum, has a composition comprising copper, nickel and iron. The anode is part of an electrolytic reduction cell comprising a vessel having an interior lined with metal which has the same composition as the anode. The electrolyte is preferably composed of a eutectic of AlF.sub.3 and either (a) NaF or (b) primarily NaF with some of the NaF replaced by an equivalent molar amount of KF or KF and LiF.

Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments

PubMed Central

Daghio, Matteo; Vaiopoulou, Eleni; Patil, Sunil A.; Suárez-Suárez, Ana; Head, Ian M.

2015-01-01

Hydrocarbons released during oil spills are persistent in marine sediments due to the absence of suitable electron acceptors below the oxic zone. Here, we investigated an alternative bioremediation strategy to remove toluene, a model monoaromatic hydrocarbon, using a bioanode. Bioelectrochemical reactors were inoculated with sediment collected from a hydrocarbon-contaminated marine site, and anodes were polarized at 0 mV and +300 mV (versus an Ag/AgCl [3 M KCl] reference electrode). The degradation of toluene was directly linked to current generation of up to 301 mA m−2 and 431 mA m−2 for the bioanodes polarized at 0 mV and +300 mV, respectively. Peak currents decreased over time even after periodic spiking with toluene. The monitoring of sulfate concentrations during bioelectrochemical experiments suggested that sulfur metabolism was involved in toluene degradation at bioanodes. 16S rRNA gene-based Illumina sequencing of the bulk anolyte and anode samples revealed enrichment with electrocatalytically active microorganisms, toluene degraders, and sulfate-reducing microorganisms. Quantitative PCR targeting the α-subunit of the dissimilatory sulfite reductase (encoded by dsrA) and the α-subunit of the benzylsuccinate synthase (encoded by bssA) confirmed these findings. In particular, members of the family Desulfobulbaceae were enriched concomitantly with current production and toluene degradation. Based on these observations, we propose two mechanisms for bioelectrochemical toluene degradation: (i) direct electron transfer to the anode and/or (ii) sulfide-mediated electron transfer. PMID:26497463

Electrical Resistivity Measurement of Petroleum Coke Powder by Means of Four-Probe Method

NASA Astrophysics Data System (ADS)

Rouget, G.; Majidi, B.; Picard, D.; Gauvin, G.; Ziegler, D.; Mashreghi, J.; Alamdari, H.

2017-10-01

Carbon anodes used in Hall-Héroult electrolysis cells are involved in both electrical and chemical processes of the cell. Electrical resistivity of anodes depends on electrical properties of its constituents, of which carbon coke aggregates are the most prevalent. Electrical resistivity of coke aggregates is usually characterized according to the ISO 10143 standardized test method, which consists of measuring the voltage drop in the bed of particles between two electrically conducing plungers through which the current is also applied. Estimation of the electrical resistivity of coke particles from the resistivity of particle bed is a challenging task and needs consideration of the contribution of the interparticle void fraction and the particle/particle contact resistances. In this work, the bed resistivity was normalized by subtracting the interparticle void fraction. Then, the contact size was obtained from discrete element method simulation and the contact resistance was calculated using Holm's theory. Finally, the resistivity of the coke particles was obtained from the bed resistivity.

Performance of denitrifying microbial fuel cell subjected to variation in pH, COD concentration and external resistance.

PubMed

Li, Jin-Tao; Zhang, Shao-Hui; Hua, Yu-Mei

2013-01-01

The effects of pH, chemical oxygen demand (COD) concentration and external resistance on denitrifying microbial fuel cell were evaluated in terms of electricity generation characteristics and pollutant removal performance. The results showed that anodic influent with weakly alkaline or neutral pH and cathodic influent with weakly acidic pH favored pollutant removal and electricity generation. The suitable influent pH of the anode and cathode were found to be 7.5-8.0 and 6.0-6.5, respectively. In the presence of sufficient nitrate in the cathode, higher influent COD concentration led to more electricity generation and greater pollutant removal rates. With an anodic influent pH of 8.0 and a cathodic influent pH of 6.0, an influent COD concentration of 400 mg/L was deemed to be appropriate. Low external resistance favored nitrate and COD removal. The results suggest that operation of denitrifying microbial fuel cell at a lower external resistance would be desirable for pollutant removal but not electricity generation.

Engineering of Nanoscale Antifouling and Hydrophobic Surfaces on Naval Structural Steel HY-80 by Anodizing

DTIC Science & Technology

2015-06-01

examination of the morphologies of the nanoporous structures and the evaluation of the anodization parameters such as anodization potential, time... sponges , anemones, tunicates, and hydroids, whilst hard fouling comprises invertebrates such as barnacles, mussels, and tubeworms. The specific...of metals by making them more stable and highly resistant, but also to modify the surface by giving it a desired morphology . Ferrous alloys such as

ITO/metal/ITO anode for efficient transparent white organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Joo, Chul Woong; Lee, Jonghee; Sung, Woo Jin; Moon, Jaehyun; Cho, Nam Sung; Chu, Hye Yong; Lee, Jeong-Ik

2015-02-01

We report on the characteristics of enhanced and balanced white-light emission of transparent organic light emitting diodes (TOLEDs) by introducing anode that has a stack structure of ITO/metal/ITO (IMI). We have investigated an anode that has a stack structure of IMI. IMI anodes are typically composed of a thin Ag layer (˜15 nm) sandwiched between two ITO layers (˜50 nm). By inserting an Ag layer it was possible to achieve sheet resistance lower than 3 Ω/sq. and transmittance of 86% at a wavelength of 550 nm. The Ag insert can act as a reflective component. With its counterpart, a transparent cathode made of a thin Ag layer (˜15 nm), micro-cavities (MC) can be effectively induced in the OLED, leading to improved performance. Using an IMI anode, it was possible to significantly increase the current efficiencies. The current efficiencies of the top and the bottom of the IMI TOLED increased to 23.0 and 15.6 cd/A, respectively, while those of the white TOLED with the ITO anode were 20.7 and 5.1 cd/A, respectively. A 30% enhancement in the overall current efficiency was achieved by taking advantage of the MC effect and the low sheet resistance.

Curved position-sensitive detector for X-ray crystallography

NASA Astrophysics Data System (ADS)

Izumi, T.

1980-11-01

A new curved position-sensitive proportional detector has been constructed for X-ray crystallography. A very hard steel wire 0.2 mm in diameter was used as a single anode wire. It was bent to a radius of 6.5 cm and was suspended elastically in a wide 160° 2θ angular aperture. An amplifier and ADC-per-cathode strip system was made in order to encode the position. The spatial resolution is better than 0.37 mm (fwhm) along the curved anode wire, and this value corresponds to an angular resolution of 0.28° in 2θ. It is shown that a thick hard anode wire is quite suitable for use as a curved position-sensitive detector.

Systematic Analysis and Comparison of Nucleotide-Binding Site Disease Resistance Genes in a Diploid Cotton Gossypium raimondii

PubMed Central

Wei, Hengling; Li, Wei; Sun, Xiwei; Zhu, Shuijin; Zhu, Jun

2013-01-01

Plant disease resistance genes are a key component of defending plants from a range of pathogens. The majority of these resistance genes belong to the super-family that harbors a Nucleotide-binding site (NBS). A number of studies have focused on NBS-encoding genes in disease resistant breeding programs for diverse plants. However, little information has been reported with an emphasis on systematic analysis and comparison of NBS-encoding genes in cotton. To fill this gap of knowledge, in this study, we identified and investigated the NBS-encoding resistance genes in cotton using the whole genome sequence information of Gossypium raimondii. Totally, 355 NBS-encoding resistance genes were identified. Analyses of the conserved motifs and structural diversity showed that the most two distinct features for these genes are the high proportion of non-regular NBS genes and the high diversity of N-termini domains. Analyses of the physical locations and duplications of NBS-encoding genes showed that gene duplication of disease resistance genes could play an important role in cotton by leading to an increase in the functional diversity of the cotton NBS-encoding genes. Analyses of phylogenetic comparisons indicated that, in cotton, the NBS-encoding genes with TIR domain not only have their own evolution pattern different from those of genes without TIR domain, but also have their own species-specific pattern that differs from those of TIR genes in other plants. Analyses of the correlation between disease resistance QTL and NBS-encoding resistance genes showed that there could be more than half of the disease resistance QTL associated to the NBS-encoding genes in cotton, which agrees with previous studies establishing that more than half of plant resistance genes are NBS-encoding genes. PMID:23936305

Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes

NASA Astrophysics Data System (ADS)

Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

2016-02-01

We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials.

Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes

PubMed Central

Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

2016-01-01

We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials. PMID:26831759

Preparation of Aluminum Nanomesh Thin Films from an Anodic Aluminum Oxide Template as Transparent Conductive Electrodes.

PubMed

Li, Yiwen; Chen, Yulong; Qiu, Mingxia; Yu, Hongyu; Zhang, Xinhai; Sun, Xiao Wei; Chen, Rui

2016-02-02

We have employed anodic aluminum oxide as a template to prepare ultrathin, transparent, and conducting Al films with a unique nanomesh structure for transparent conductive electrodes. The anodic aluminum oxide template is obtained through direct anodization of a sputtered Al layer on a glass substrate, and subsequent wet etching creates the nanomesh metallic film. The optical and conductive properties are greatly influenced by experimental conditions. By tuning the anodizing time, transparent electrodes with appropriate optical transmittance and sheet resistance have been obtained. The results demonstrate that our proposed strategy can serve as a potential method to fabricate low-cost TCEs to replace conventional indium tin oxide materials.

Influence of Fluoride Ion on the Performance of Pb-Ag Anode During Long-Term Galvanostatic Electrolysis

NASA Astrophysics Data System (ADS)

Zhong, Xiaocong; Yu, Xiaoying; Jiang, Liangxing; Lv, Xiaojun; Liu, Fangyang; Lai, Yanqing; Li, Jie

2015-09-01

Anodic potential, morphology and phase composition of the anodic layer, corrosion morphology of the metallic substrate, and oxygen evolution behavior of Pb-Ag anode in H2SO4 solution without/with fluoride ion were investigated and compared. The results showed that the presence of fluoride ions contributed to a smoother anodic layer with lower PbO2 concentration, which resulted in lower double layer capacity and higher charge transfer resistance for the oxygen evolution reaction. Consequently, the Pb-Ag anode showed a higher anodic potential (about 35 mV) in the fluoride-containing electrolyte. In addition, the fluoride ions accelerated the detachment of loose flakes on the anodic layer. It was demonstrated that the anodic layer formed in the fluoride-containing H2SO4 solution was thinner. Furthermore, fluoride ions aggravated the corrosion of the metallic substrate at interdendritic boundary regions. Hence, the presence of fluoride ions is detrimental to oxygen evolution reactivity and increases the corrosion of the Pb-Ag anode, which may further increase the energy consumption and capital cost of zinc plants.

Anodizing Process

NASA Technical Reports Server (NTRS)

1983-01-01

This anodizing process traces its origin to the 1960's when Reynolds Metals Company, under contract with Goddard Space Flight Center, developed a multipurpose anodizing electrolyte (MAE) process to produce a hard protective finish for spacecraft aluminum. MAE produces a high-density, abrasion-resistant film prior to the coloring step, in which the pores of the film are impregnated with a metallic form of salt. Tru-Color product applications include building fronts, railing, curtain walls, doors and windows.

Development of Carbon and Sulphur Tolerant Anodes of Solid Oxide Fuel Cells

DTIC Science & Technology

2010-01-14

LSCM/YSZ) composite anode is investigated in detail for the direct utilization of ethanol and methane (the main component of natural gas) in SOFCs...Impregnation of Pd nanoparticles significantly promotes the electrocatalytic activity of LSCM/YSZ composite anodes for the ethanol and methane... electrooxidation reaction. At 800°C, the electrode polarization resistance for the methane oxidation is reduced by a factor of 3 after impregnation of 0.10

Effect of mass and charge transport speed and direction in porous anodes on microbial electrolysis cell performance.

PubMed

Sleutels, Tom H J A; Hamelers, Hubertus V M; Buisman, Cees J N

2011-01-01

The use of porous electrodes like graphite felt as anode material has the potential of achieving high volumetric current densities. High volumetric current densities, however, may also lead to mass transport limitations within these porous materials. Therefore, in this study we investigated the mass and charge transport limitations by increasing the speed of the forced flow and changing the flow direction through the porous anode. Increase of the flow speed led to a decrease in current density when the flow was directed towards the membrane caused by an increase in anode resistance. Current density increased at higher flow speed when the flow was directed away from the membrane. This was caused by a decrease in transport resistance of ions through the membrane which increased the buffering effect of the system. Furthermore, the increase in flow speed led to an increase of the coulombic efficiency by 306%. Copyright © 2010 Elsevier Ltd. All rights reserved.

Tribocorrosion behaviour of anodic treated titanium surfaces intended for dental implants

NASA Astrophysics Data System (ADS)

Alves, A. C.; Oliveira, F.; Wenger, F.; Ponthiaux, P.; Celis, J.-P.; Rocha, L. A.

2013-10-01

Tribocorrosion plays an important role in the lifetime of metallic implants. Once implanted, biomaterials are subjected to micro-movements in aggressive biological fluids. Titanium is widely used as an implant material because it spontaneously forms a compact and protective nanometric thick oxide layer, mainly TiO2, in ambient air. That layer provides good corrosion resistance, and very low toxicity, but its low wear resistance is a concern. In this work, an anodizing treatment was performed on commercial pure titanium to form a homogeneous thick oxide surface layer in order to provide bioactivity and improve the biological, chemical and mechanical properties. Anodizing was performed in an electrolyte containing β-glycerophosphate and calcium acetate. The influence of the calcium acetate content on the tribocorrosion behaviour of the anodized material was studied. The concentration of calcium acetate in the electrolyte was found to largely affect the crystallographic structure of the resulting oxide layer. Better tribocorrosion behaviour was noticed on increasing the calcium acetate concentration.

Thermal cycling and electrochemical characteristics of solid oxide fuel cell supported on stainless steel with a new 3-phase composite anode

NASA Astrophysics Data System (ADS)

Dayaghi, Amir Masoud; Kim, Kun Joong; Kim, Sun Jae; Kim, Sunwoong; Bae, Hongyeul; Choi, Gyeong Man

2017-06-01

We report design, fabrication method, and fast thermal-cycling ability of solid oxide fuel cells (SOFCs) that use stainless steel (STS) as a support, and a new 3-phase anode. La and Ni co-doped SrTiO3 (La0.2Sr0.8Ti0.9Ni0.1O3-d, LSTN), replaces some of the Ni in conventional Ni-yttria stabilized zirconia (YSZ) anode; the resultant LSTN-YSZ-Ni 3-phase-composite anode is tested as a new reduction (or decomposition)-resistant anode of STS-supported SOFCs that can be co-fired with STS. A multi-layered cell with YSZ electrolyte (thickness ∼5 μm), composite anode, STS-cermet contact-layer, and STS support is designed, then fabricated by tape casting, lamination, and co-firing at 1250 °C in reducing atmosphere. The maximum power density (MPD) is 325 mW cm-2 at 650 °C; this is one of the highest among STS-supported cells fabricated by co-firing. The cell also shows stable open-circuit voltage and Ohmic resistance during 100 rapid thermal cycles between 170 and 600 °C. STS support minimizes stress and avoids cracking of electrolyte during rapid thermal cycling. The excellent MPD and stability during thermal cycles, and promising characteristics of SOFC as a power source for vehicle or mobile devices that requires rapid thermal cycles, are attributed to the new design of the cell with new anode structure.

Anodic Oxidation of Carbon Steel at High Current Densities and Investigation of Its Corrosion Behavior

NASA Astrophysics Data System (ADS)

Fattah-Alhosseini, Arash; Khan, Hamid Yazdani

2017-06-01

This work aims at studying the influence of high current densities on the anodization of carbon steel. Anodic protective coatings were prepared on carbon steel at current densities of 100, 125, and 150 A/dm2 followed by a final heat treatment. Coatings microstructures and morphologies were analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM). The corrosion resistance of the uncoated carbon steel substrate and the anodic coatings were evaluated in 3.5 wt pct NaCl solution through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results showed that the anodic oxide coatings which were prepared at higher current densities had thicker coatings as a result of a higher anodic forming voltage. Therefore, the anodized coatings showed better anti-corrosion properties compared to those obtained at lower current densities and the base metal.

Fundamental Investigation of Si Anode in Li-Ion Cells

NASA Technical Reports Server (NTRS)

Wu, James J.; Bennett, William R.

2012-01-01

Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is approximately 10 times of graphite and it is an abundant element on earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of Si anode during the first cycle, the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes.

An analysis of degradation phenomena in polymer electrolyte membrane water electrolysis

NASA Astrophysics Data System (ADS)

Rakousky, Christoph; Reimer, Uwe; Wippermann, Klaus; Carmo, Marcelo; Lueke, Wiebke; Stolten, Detlef

2016-09-01

The durability of a polymer electrolyte membrane (PEM) water electrolysis single cell, assembled with regular porous transport layers (PTLs) is investigated for just over 1000 h. We observe a significant degradation rate of 194 μV h-1 and conclude that 78% of the detectable degradation can be explained by an increase in ohmic resistance, arising from the anodic Ti-PTL. Analysis of the polarization curves also indicates a decrease in the anodic exchange current density, j0, that results from the over-time contamination of the anode with Ti species. Furthermore, the average Pt-cathode particle size increases during the test, but we do not believe this phenomenon makes a significant contribution to increased cell voltages. To validate the anode Ti-PTL as a crucial source of increasing resistance, a second cell is assembled using Pt-coated Ti-PTLs. This yields a substantially reduced degradation rate of only 12 μV h-1, indicating that a non-corroding anode PTL is vital for PEM electrolyzers. It is our hope that forthcoming tailored PTLs will not only contribute to fast progress on cost-efficient stacks, but also to its long-term application of PEM electrolyzers involved in industrial processes.

Anode materials for electrochemical waste destruction

NASA Technical Reports Server (NTRS)

Molton, Peter M.; Clarke, Clayton

1990-01-01

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

Simultaneous sulfide removal, nitrification, and electricity generation in a microbial fuel cell equipped with an oxic cathode.

PubMed

Bao, Renbing; Zhang, Shaohui; Zhao, Li; Zhong, Liuxiang

2017-02-01

With sulfide as an anodic electron donor and ammonium as a cathodic substrate, the feasibility of simultaneous sulfide removal, nitrification, and electricity generation was investigated in a microbial fuel cell (MFC) equipped with an oxic cathode. Successful simultaneous sulfide removal, nitrification, and electricity generation in this MFC were achieved in 35 days, with the sulfide and ammonium removal percent of 92.7 ± 1.4 and 96.4 ± 0.3%, respectively. The maximum power density increased, but the internal resistance decreased with the increase of feeding sulfide concentration from 62.9 ± 0.3 to 238.5 ± 0.2 mg S/L. Stable ammonium removal with complete nitrification, preparing for future denitrification, was obtained throughout the current study. Sulfide removal loading significantly increased with the increase of feeding sulfide concentration at each external resistance, but no significant correlation between sulfide removal loading and external resistance was found at each feeding sulfide concentration. The charge recovery and anodic coulombic efficiency (CE) significantly decreased with the increase of external resistance. High feeding sulfide concentration led to low anodic CE. Granular sulfur deposition was found on the anode graphite fiber. The appropriate feeding sulfide concentration for sulfide removal and sulfur deposition was deemed to be 178.0 ± 1.7 mg S/L, achieving a sulfur deposition percent of 69.7 ± 0.6%.

Effect of intermetallic phases on the anodic oxidation and corrosion of 5A06 aluminum alloy

NASA Astrophysics Data System (ADS)

Li, Song-mei; Li, Ying-dong; Zhang, You; Liu, Jian-hua; Yu, Mei

2015-02-01

Intermetallic phases were found to influence the anodic oxidation and corrosion behavior of 5A06 aluminum alloy. Scattered intermetallic particles were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) after pretreatment. The anodic film was investigated by transmission electron microscopy (TEM), and its corrosion resistance was analyzed by electrochemical impedance spectroscopy (EIS) and Tafel polarization in NaCl solution. The results show that the size of Al-Fe-Mg-Mn particles gradually decreases with the iron content. During anodizing, these intermetallic particles are gradually dissolved, leading to the complex porosity in the anodic film beneath the particles. After anodizing, the residual particles are mainly silicon-containing phases, which are embedded in the anodic film. Electrochemical measurements indicate that the porous anodic film layer is easily penetrated, and the barrier plays a dominant role in the overall protection. Meanwhile, self-healing behavior is observed during the long immersion time.

Surface treatments for aluminium alloys

NASA Astrophysics Data System (ADS)

Ardelean, M.; Lascău, S.; Ardelean, E.; Josan, A.

2018-01-01

Typically, in contact with the atmosphere, the aluminium surface is covered with an aluminium oxide layer, with a thickness of less than 1-2μm. Due to its low thickness, high porosity and low mechanical strength, this layer does not protect the metal from corrosion. Anodizing for protective and decorative purposes is the most common method of superficial oxidation processes and is carried out through anodic oxidation. The oxide films, resulted from anodizing, are porous, have a thickness of 20-50μm, and are heat-resistant, stable to water vapour and other corrosion agents. Hard anodizing complies with the same obtains principles as well as decorative and protective anodization. The difference is in that hard anodizing is achieved at low temperatures and high intensity of electric current. In the paper are presented the results of decorative and hard anodization for specimens made from several aluminium alloys in terms of the appearance of the specimens and of the thickness of the anodized.

Cathodic protection of two concrete bridge decks using titanium-mesh anodes : interim report.

DOT National Transportation Integrated Search

1991-01-01

Expanded titanium mesh with a layer of precious metal oxides sintered around it has recently been introduced to fulfill the need for a durable anode in the cathodic protection (CP) of concrete bridge decks. In addition to being resistant to chemical ...

Electrolytic reduction runs of 0.6 kg scale-simulated oxide fuel in a Li2O-LiCl molten salt using metal anode shrouds

NASA Astrophysics Data System (ADS)

Choi, Eun-Young; Lee, Jeong; Heo, Dong Hyun; Lee, Sang Kwon; Jeon, Min Ku; Hong, Sun Seok; Kim, Sung-Wook; Kang, Hyun Woo; Jeon, Sang-Chae; Hur, Jin-Mok

2017-06-01

Ten electrolytic reduction or oxide reduction (OR) runs of a 0.6 kg scale-simulated oxide fuel in a Li2O-LiCl molten salt at 650 °C were conducted using metal anode shrouds. During this procedure, an anode shroud surrounds a platinum anode and discharges hot oxygen gas from the salt to outside of the OR apparatus, thereby preventing corrosion of the apparatus. In this study, a number of anode shrouds made of various metals were tested. Each metallic anode shroud consisted of a lower porous shroud for the salt phase and an upper nonporous shroud for the gas phase. A stainless steel (STS) wire mesh with five-ply layer was a material commonly used for the lower porous shroud for the OR runs. The metals tested for the upper nonporous shroud in the different OR runs are STS, nickel, and platinum- or silver-lined nickel. The lower porous shroud showed no significant damage during two consecutive OR runs, but exhibited signs of damage from three or more runs due to thermal stress. The upper nonporous shrouds made up of either platinum- or silver-lined nickel showed excellent corrosion resistance to hot oxygen gas while STS or nickel without any platinum or silver lining exhibited poor corrosion resistance.

Properties of a new type Al/Pb-0.3%Ag alloy composite anode for zinc electrowinning

NASA Astrophysics Data System (ADS)

Yang, Hai-tao; Liu, Huan-rong; Zhang, Yong-chun; Chen, Bu-ming; Guo, Zhong-cheng; Xu, Rui-dong

2013-10-01

An Al/Pb-0.3%Ag alloy composite anode was produced via composite casting. Its electrocatalytic activity for the oxygen evolution reaction and corrosion resistance was evaluated by anodic polarization curves and accelerated corrosion test, respectively. The microscopic morphologies of the anode section and anodic oxidation layer during accelerated corrosion test were obtained by scanning electron microscopy. It is found that the composite anode (hard anodizing) displays a more compact interfacial combination and a better adhesive strength than plating tin. Compared with industrial Pb-0.3%Ag anodes, the oxygen evolution overpotentials of Al/Pb-0.3%Ag alloy (hard anodizing) and Al/Pb-0.3%Ag alloy (plating tin) at 500 A·m-2 were lower by 57 and 14 mV, respectively. Furthermore, the corrosion rates of Pb-0.3%Ag alloy, Al/Pb-0.3%Ag alloy (hard anodizing), and Al/Pb-0.3%Ag alloy (plating tin) were 13.977, 9.487, and 11.824 g·m-2·h-1, respectively, in accelerated corrosion test for 8 h at 2000 A·m-2. The anodic oxidation layer of Al/Pb-0.3%Ag alloy (hard anodizing) is more compact than Pb-0.3%Ag alloy and Al/Pb-0.3%Ag alloy (plating tin) after the test.

Unstable behavior of anodic arc discharge for synthesis of nanomaterials

DOE PAGES

Gershman, Sophia; Raitses, Yevgeny

2016-07-27

A short carbon arc operating with a high ablation rate of the graphite anode exhibits a combined motion of the arc and the arc attachment to the anode. A characteristic time scale of this motion is in a 10 -3 sec range. The arc exhibits a negative differential resistance before the arc motion occurs. Thermal processes in the arc plasma region interacting with the ablating anode are considered as possible causes of this unstable arc behavior. It is also hypothesized that the arc motion could potentially cause mixing of the various nanoparticles synthesized in the arc in the high ablationmore » regime.« less

Unstable behavior of anodic arc discharge for synthesis of nanomaterials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gershman, Sophia; Raitses, Yevgeny

A short carbon arc operating with a high ablation rate of the graphite anode exhibits a combined motion of the arc and the arc attachment to the anode. A characteristic time scale of this motion is in a 10 -3 sec range. The arc exhibits a negative differential resistance before the arc motion occurs. Thermal processes in the arc plasma region interacting with the ablating anode are considered as possible causes of this unstable arc behavior. It is also hypothesized that the arc motion could potentially cause mixing of the various nanoparticles synthesized in the arc in the high ablationmore » regime.« less

Microgap x-ray detector

DOEpatents

Wuest, Craig R.; Bionta, Richard M.; Ables, Elden

1994-01-01

An x-ray detector which provides for the conversion of x-ray photons into photoelectrons and subsequent amplification of these photoelectrons through the generation of electron avalanches in a thin gas-filled region subject to a high electric potential. The detector comprises a cathode (photocathode) and an anode separated by the thin, gas-filled region. The cathode may comprise a substrate, such a beryllium, coated with a layer of high atomic number material, such as gold, while the anode can be a single conducting plane of material, such as gold, or a plane of resistive material, such as chromium/silicon monoxide, or multiple areas of conductive or resistive material, mounted on a substrate composed of glass, plastic or ceramic. The charge collected from each electron avalanche by the anode is passed through processing electronics to a point of use, such as an oscilloscope.

Microgap x-ray detector

DOEpatents

Wuest, C.R.; Bionta, R.M.; Ables, E.

1994-05-03

An x-ray detector is disclosed which provides for the conversion of x-ray photons into photoelectrons and subsequent amplification of these photoelectrons through the generation of electron avalanches in a thin gas-filled region subject to a high electric potential. The detector comprises a cathode (photocathode) and an anode separated by the thin, gas-filled region. The cathode may comprise a substrate, such a beryllium, coated with a layer of high atomic number material, such as gold, while the anode can be a single conducting plane of material, such as gold, or a plane of resistive material, such as chromium/silicon monoxide, or multiple areas of conductive or resistive material, mounted on a substrate composed of glass, plastic or ceramic. The charge collected from each electron avalanche by the anode is passed through processing electronics to a point of use, such as an oscilloscope. 3 figures.

Variable N-type negative resistance in an injection-gated double-injection diode

NASA Technical Reports Server (NTRS)

Kapoor, A. K.; Henderson, H. T.

1981-01-01

Double-injection (DI) switching devices consist of p+ and n+ contacts (for hole and electron injection, respectively), separated by a near intrinsic semiconductor region containing deep traps. Under proper conditions, these devices exhibit S-type differential negative resistance (DNR) similar to silicon-controlled rectifiers. With the added influence of a p+ gate appropriately placed between the anode (p+) and cathode (n+), the current-voltage characteristic of the device has been manipulated for the first time to exhibit a variable N-type DNR. The anode current and the anode-to-cathode voltage levels at which this N-type DNR is observed can be varied by changing the gate-to-cathode bias. In essence, the classical S-type DI diode can be electronically transformed into an N-type diode. A first-order phenomenological model is proposed for the N-type DNR.

Prototype of a scaled‐up microbial fuel cell for copper recovery

PubMed Central

Rodenas Motos, Pau; Molina, Gonzalo; Sleutels, Tom; Saakes, Michel; Buisman, Cees

2017-01-01

Abstract Background Bioelectrochemical systems (BESs) enable recovery of electrical energy through oxidation of a wide range of substrates at an anode and simultaneous recovery of metals at a cathode. Scale‐up of BESs from the laboratory to pilot scale is a challenging step in the development of the process, and there are only a few successful experiences to build on. This paper presents a prototype BES for the recovery of copper. Results The cell design presented here had removable electrodes, similar to those in electroplating baths. The anode and cathode in this design could be replaced independently. The prototype bioelectrochemical cell consisted of an 835 cm2 bioanode fed with acetate, and a 700 cm2 cathode fed with copper. A current density of 1.2 A/−2 was achieved with 48 mW m−2 of power production. The contribution of each component (anode, electrolytes, cathode and membrane) was evaluated through the analysis of the internal resistance distribution. This revealed that major losses occurred at the anode, and that the design with removable electrodes results in higher internal resistance compared with other systems. To further assess the practical applicability of BES for copper recovery, an economic evaluation was performed. Conclusion Analysis shows that the internal resistance of several lab‐scale BESs is already sufficiently low to make the system economic, while the internal resistance for scaled‐up systems still needs to be improved considerably to become economically applicable.© 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. PMID:29104342

Boosting Power Density of Microbial Fuel Cells with 3D Nitrogen‐Doped Graphene Aerogel Electrode

PubMed Central

Yang, Yang; Liu, Tianyu; Zhang, Feng; Ye, Dingding; Liao, Qiang

2016-01-01

A 3D nitrogen‐doped graphene aerogel (N‐GA) as an anode material for microbial fuel cells (MFCs) is reported. Electron microscopy images reveal that the N‐GA possesses hierarchical porous structure that allows efficient diffusion of both bacterial cells and electron mediators in the interior space of 3D electrode, and thus, the colonization of bacterial communities. Electrochemical impedance spectroscopic measurements further show that nitrogen doping considerably reduces the charge transfer resistance and internal resistance of GA, which helps to enhance the MFC power density. Importantly, the dual‐chamber milliliter‐scale MFC with N‐GA anode yields an outstanding volumetric power density of 225 ± 12 W m−3 normalized to the total volume of the anodic chamber (750 ± 40 W m−3 normalized to the volume of the anode). These power densities are the highest values report for milliliter‐scale MFCs with similar chamber size (25 mL) under the similar measurement conditions. The 3D N‐GA electrode shows great promise for improving the power generation of MFC devices. PMID:27818911

N-type nano-silicon powders with ultra-low electrical resistivity as anode materials in lithium ion batteries

NASA Astrophysics Data System (ADS)

Yue, Zhihao; Zhou, Lang; Jin, Chenxin; Xu, Guojun; Liu, Liekai; Tang, Hao; Li, Xiaomin; Sun, Fugen; Huang, Haibin; Yuan, Jiren

2017-06-01

N-type silicon wafers with electrical resistivity of 0.001 Ω cm were ball-milled to powders and part of them was further mechanically crushed by sand-milling to smaller particles of nano-size. Both the sand-milled and ball-milled silicon powders were, respectively, mixed with graphite powder (silicon:graphite = 5:95, weight ratio) as anode materials for lithium ion batteries. Electrochemical measurements, including cycle and rate tests, present that anode using sand-milled silicon powder performed much better. The first discharge capacity of sand-milled silicon anode is 549.7 mAh/g and it is still up to 420.4 mAh/g after 100 cycles. Besides, the D50 of sand-milled silicon powder shows ten times smaller in particle size than that of ball-milled silicon powder, and they are 276 nm and 2.6 μm, respectively. In addition, there exist some amorphous silicon components in the sand-milled silicon powder excepting the multi-crystalline silicon, which is very different from the ball-milled silicon powder made up of multi-crystalline silicon only.

A comparison of chromic acid and sulfuric acid anodizing

NASA Technical Reports Server (NTRS)

Danford, M. D.

1992-01-01

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

Correlation of Electrolyte Volume and Electrochemical Performance in Lithium-Ion Pouch Cells with Graphite Anodes and NMC532 Cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, Seong Jin; Li, Jianlin; Mohanty, Debasish

2017-01-01

The work herein reports on studies aimed at exploring the correlation between electrolyte volume and electrochemical performance of full cell, pouch-cells consisting of graphite/ Li 1.02Ni 0.50Mn 0.29Co 0.19O 2 (NMC-532) as the electrodes and 1.2 M LiPF6 in ethylene carbonate:ethylmethyl carbonate (EC:EMC) as the electrolyte. It is demonstrated that a minimum electrolyte volume factor of 1.9 times the total pore volume of cell components (cathode, anode, and separator) is needed for long-term cyclability and low impedance. Less electrolyte results in an increase of the measured ohmic resistances. Increased resistance ratios for charge transfer and passivation layers at cathode, relativemore » to initial values, were 1.5–2.0 after 100 cycles. At the cathode, the resistance from charge transfer was 2–3 times higher than for passivation layers. Differential voltage analysis showed that anodes were less delithiated after discharging as the cells were cycled.« less

Correlation of Electrolyte Volume and Electrochemical Performance in Lithium-Ion Pouch Cells with Graphite Anodes and NMC532 Cathodes

DOE PAGES

An, Seong Jin; Li, Jianlin; Mohanty, Debasish; ...

2017-04-07

The work herein reports on studies aimed at exploring the correlation between electrolyte volume and electrochemical performance of full cell, pouch-cells consisting of graphite/ Li 1.02Ni 0.50Mn 0.29Co 0.19O 2 (NMC-532) as the electrodes and 1.2 M LiPF 6 in ethylene carbonate:ethylmethyl carbonate (EC:EMC) as the electrolyte. In addition, it is demonstrated that a minimum electrolyte volume factor of 1.9 times the total pore volume of cell components (cathode, anode, and separator) is needed for long-term cyclability and low impedance. Less electrolyte results in an increase of the measured Ohmic resistances. Increased resistance ratios for charge transfer and passivation layersmore » at cathode, relative to initial values, were 1.5 2.0 after 100 cycles. At the cathode, the resistance from charge transfer was 2-3 times higher than for passivation layers. Lastly, differential voltage analysis showed that anodes were less delithiated after discharging as the cells were cycled.« less

Tape Casting of High-Performance Low-Temperature Solid Oxide Cells with Thin La0.8Sr0.2Ga0.8Mg0.2O3-δ Electrolytes and Impregnated Nano Anodes.

PubMed

Gao, Zhan; Wang, Hongqian; Miller, Elizabeth; Liu, Qinyuan; Senn, Daniel; Barnett, Scott

2017-03-01

Low-temperature solid oxide cells (LT-SOCs), operating at 400 to 650 °C, have great potential for commercialization since they can provide lower cost and improved long-term durability. Low operating temperature can also enable high round-trip efficiency of SOCs as reversible energy storage devices. This paper describes Sr 0.8 La 0.2 TiO 3-α (SLT) anode supported LT-SOC with thin La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM) electrolyte made by tape casting, with screen printed La 0.6 Sr 0.4 Fe 0.8 Co 0.2 O 3-δ (LSCF) cathode and impregnated Ni anode. Optimization of the anode functional layers is described; the best anodes had 68 vol % LSGM and 12.3 vol % Ni and yielded maximum power density of 1.6 Wcm -2 with a cell area specific resistance (ASR) of 0.21 Ωcm 2 at 650 °C. Most of the cell ASR was associated with the cathode. Reversible electrolysis and fuel cell operation yielded similar characteristics with both 50% H 2 -50% H 2 O and syngas fuel. Life testing over 500 h showed that the cathode impedance stabilized after an initial break-in period; the ohmic and anode resistances, though relatively small, increased slightly with time.

Mobile genetic element-encoded cytolysin connects virulence to methicillin resistance in MRSA.

PubMed

Queck, Shu Y; Khan, Burhan A; Wang, Rong; Bach, Thanh-Huy L; Kretschmer, Dorothee; Chen, Liang; Kreiswirth, Barry N; Peschel, Andreas; Deleo, Frank R; Otto, Michael

2009-07-01

Bacterial virulence and antibiotic resistance have a significant influence on disease severity and treatment options during bacterial infections. Frequently, the underlying genetic determinants are encoded on mobile genetic elements (MGEs). In the leading human pathogen Staphylococcus aureus, MGEs that contain antibiotic resistance genes commonly do not contain genes for virulence determinants. The phenol-soluble modulins (PSMs) are staphylococcal cytolytic toxins with a crucial role in immune evasion. While all known PSMs are core genome-encoded, we here describe a previously unidentified psm gene, psm-mec, within the staphylococcal methicillin resistance-encoding MGE SCCmec. PSM-mec was strongly expressed in many strains and showed the physico-chemical, pro-inflammatory, and cytolytic characteristics typical of PSMs. Notably, in an S. aureus strain with low production of core genome-encoded PSMs, expression of PSM-mec had a significant impact on immune evasion and disease. In addition to providing high-level resistance to methicillin, acquisition of SCCmec elements encoding PSM-mec by horizontal gene transfer may therefore contribute to staphylococcal virulence by substituting for the lack of expression of core genome-encoded PSMs. Thus, our study reveals a previously unknown role of methicillin resistance clusters in staphylococcal pathogenesis and shows that important virulence and antibiotic resistance determinants may be combined in staphylococcal MGEs.

The optimal timing of stimulation to induce long-lasting positive effects on episodic memory in physiological aging.

PubMed

Manenti, Rosa; Sandrini, Marco; Brambilla, Michela; Cotelli, Maria

2016-09-15

Episodic memory displays the largest degree of age-related decline. A noninvasive brain stimulation technique that can be used to modulate memory in physiological aging is transcranial Direct Current Stimulation (tDCS). However, an aspect that has not been adequately investigated in previous studies is the optimal timing of stimulation to induce long-lasting positive effects on episodic memory function. Our previous studies showed episodic memory enhancement in older adults when anodal tDCS was applied over the left lateral prefrontal cortex during encoding or after memory consolidation with or without a contextual reminder. Here we directly compared the two studies to explore which of the tDCS protocols would induce longer-lasting positive effects on episodic memory function in older adults. In addition, we aimed to determine whether subjective memory complaints would be related to the changes in memory performance (forgetting) induced by tDCS, a relevant issue in aging research since individuals with subjective memory complaints seem to be at higher risk of later memory decline. The results showed that anodal tDCS applied after consolidation with a contextual reminder induced longer-lasting positive effects on episodic memory, conceivably through reconsolidation, than anodal tDCS during encoding. Furthermore, we reported, providing new data, a moderate negative correlation between subjective memory complaints and forgetting when anodal tDCS was applied after consolidation with a contextual reminder. This study sheds light on the best-suited timing of stimulation to induce long-lasting positive effects on memory function and might help the clinicians to select the most effective tDCS protocol to prevent memory decline. Copyright © 2016 Elsevier B.V. All rights reserved.

Nanocomposite protective coatings for battery anodes

DOEpatents

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

2014-01-21

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

Relationships between structure and activity of carbon as a multifunctional support for electrocatalysts.

PubMed

Stevanović, Sanja I; Panić, Vladimir V; Dekanski, Aleksandar B; Tripković, Amalija V; Jovanović, Vladislava M

2012-07-14

We report on new insights into the relationships between structure and activity of glassy carbon (GC), as a model material for electrocatalyst support, during its anodization in acid solution. Our investigation strongly confirms the role of CFGs in promotion of Pt activity by the "spill-over" effect related to CO(ads) for methanol electrooxidation (MEO) on a carbon-supported Pt catalyst. Combined analysis of voltammetric and impedance behaviour as well as changes in GC surface morphology induced by intensification of anodizing conditions reveal an intrinsic influence of the carbon functionalization and the structure of a graphene oxide (GO) layer on the electrical and electrocatalytic properties of activated GC. Although GO continuously grows during anodization, it structurally changes from being a graphite inter-layer within graphite ribbons toward a continuous GO surface layer that deteriorates the native structure of GC. As a consequence of the increased distance between GO-spaced graphite layers, the GC conductivity decreases until the case of profound GO exfoliation under drastic anodizing conditions. This exposes the native, yet abundantly functionalized, GC texture. While GC capacitance continuously increases with intensification of anodizing conditions, the surface nano-roughness and GO resistance reach the highest values at modest anodizing conditions, and then decrease upon drastic anodization due to the onset of GO exfoliation. We found for the first time that the activity of a GC-supported Pt catalyst in MEO, as one of the promising half-reactions in polymer electrolyte fuel cells, strictly follows the changes in GC nano-roughness and GO-induced GC resistance. The highest GC/Pt MEO activity is reached when optimal distance between graphite layers and optimal degree of GC functionalization bring the highest amount of CFGs into intimate contact with the Pt surface. This confirms the promoting role of CFGs in MEO catalysis.

The rice blast resistance gene Ptr encodes an atypical protein required for broad spectrum disease resistance

USDA-ARS?s Scientific Manuscript database

Plant resistance (R) genes typically encode proteins with nucleotide binding site-leucine rich repeat (NLR) domains. We identified a novel, broad-spectrum rice blast R gene, Ptr, encoding a non-NLR protein with four Armadillo repeats. Ptr was originally identified by fast neutron mutagenesis as a ...

Reassignment of scattered emission photons in multifocal multiphoton microscopy.

PubMed

Cha, Jae Won; Singh, Vijay Raj; Kim, Ki Hean; Subramanian, Jaichandar; Peng, Qiwen; Yu, Hanry; Nedivi, Elly; So, Peter T C

2014-06-05

Multifocal multiphoton microscopy (MMM) achieves fast imaging by simultaneously scanning multiple foci across different regions of specimen. The use of imaging detectors in MMM, such as CCD or CMOS, results in degradation of image signal-to-noise-ratio (SNR) due to the scattering of emitted photons. SNR can be partly recovered using multianode photomultiplier tubes (MAPMT). In this design, however, emission photons scattered to neighbor anodes are encoded by the foci scan location resulting in ghost images. The crosstalk between different anodes is currently measured a priori, which is cumbersome as it depends specimen properties. Here, we present the photon reassignment method for MMM, established based on the maximum likelihood (ML) estimation, for quantification of crosstalk between the anodes of MAPMT without a priori measurement. The method provides the reassignment of the photons generated by the ghost images to the original spatial location thus increases the SNR of the final reconstructed image.

Effects of anodic oxidation parameters on a modified titanium surface.

PubMed

Park, Il Song; Lee, Min Ho; Bae, Tae Sung; Seol, Kyeong Won

2008-02-01

Anodic oxidation is an electrochemical treatment that can be used to control the thickness of an oxide layer formed on a titanium surface. This procedure has the advantage of allowing the ions contained in an electrolyte to deposit onto the oxide layer. The characteristics of a layer treated with anodic oxidation can vary according to the type and concentration of the electrolytes as well as the processing variables used during anodic oxidation. In this study, the constant electrolyte for anodic oxidation was a mixed solution containing 0.02 M DL-alpha-glycerophosphate disodium salt and 0.2M calcium acetate. Anodic oxidation was carried out at different voltages, current densities, and duration of anodic oxidation. The results showed that the current density and variation in the duration of anodic oxidation did not have a large effect on the change in the characteristics of the layer. On the other hand, the size of the micropores was increased with increasing voltage of anodic oxidation, and anatase and rutile phases were found to co-exist in the porous titanium dioxide layer. In addition, the thickness of the oxide layer on titanium and the characteristic of corrosion resistance increased with increasing voltage. The MTT test showed that the cell viability was increased considerably as a result of anodic oxidation. The anodizing voltage is an important parameter that determines the characteristics of the anodic oxide layer of titanium. (c) 2007 Wiley Periodicals, Inc.

Metal-based anode for high performance bioelectrochemical systems through photo-electrochemical interaction

NASA Astrophysics Data System (ADS)

Liang, Yuxiang; Feng, Huajun; Shen, Dongsheng; Long, Yuyang; Li, Na; Zhou, Yuyang; Ying, Xianbin; Gu, Yuan; Wang, Yanfeng

2016-08-01

This paper introduces a novel composite anode that uses light to enhance current generation and accelerate biofilm formation in bioelectrochemical systems. The composite anode is composed of 316L stainless steel substrate and a nanostructured α-Fe2O3 photocatalyst (PSS). The electrode properties, current generation, and biofilm properties of the anode are investigated. In terms of photocurrent, the optimal deposition and heat-treatment times are found to be 30 min and 2 min, respectively, which result in a maximum photocurrent of 0.6 A m-2. The start-up time of the PSS is 1.2 days and the maximum current density is 2.8 A m-2, twice and 25 times that of unmodified anode, respectively. The current density of the PSS remains stable during 20 days of illumination. Confocal laser scanning microscope images show that the PSS could benefit biofilm formation, while electrochemical impedance spectroscopy indicates that the PSS reduce the charge-transfer resistance of the anode. Our findings show that photo-electrochemical interaction is a promising way to enhance the biocompatibility of metal anodes for bioelectrochemical systems.

Characterization and performance of anodic mixed culture biofilms in submersed microbial fuel cells.

PubMed

Saba, Beenish; Christy, Ann D; Yu, Zhongtang; Co, Anne C; Islam, Rafiq; Tuovinen, Olli H

2017-02-01

Microbial fuel cells (MFCs) were designed for laboratory scale experiments to study electroactive biofilms in anodic chambers. Anodic biofilms and current generation during biofilm growth were examined using single chambered MFCs submersed in algal catholyte. A culture of the marine green alga Nanochloropsis salina was used as a biocatholyte, and a rumen fluid microbiota was the anodic chamber inoculum. Electrical impedance spectroscopy was performed under varying external resistance once a week to identify mass transport limitations at the biofilm-electrolyte interface during the four-week experiment. The power generation increased from 249 to 461mWm -2 during the time course. Confocal laser scanning microscopy imaging showed that the depth of the bacterial biofilm on the anode was about 65μm. There were more viable bacteria on the biofilm surface and near the biofilm-electrolyte interface as compared to those close to the anode surface. The results suggest that biofilm growth on the anode creates a conductive layer, which can help overcome mass transport limitations in MFCs. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of aluminum anodizing in phosphoric acid electrolyte on adhesion strength and thermal performance

NASA Astrophysics Data System (ADS)

Lee, Sulki; Kim, Donghyun; Kim, Yonghwan; Jung, Uoochang; Chung, Wonsub

2016-01-01

This study examined the adhesive bond strength and thermal performance of the anodized aluminum 6061 in phosphoric acid electrolyte to improve the adhesive bond strength and thermal performance for use in metal core printed circuit boards (MCPCB). The electrolyte temperature and applied voltage were altered to generate varied pore structures. The thickness, porosity and pore diameter of the anodized layer were measured. The pore morphologies were affected most by temperature, which was the driving force for ion transportation. The mechanism of adhesive bond was penetration of the epoxy into the pores. The optimal anodization conditions for maximum adhesive bond strength, 27 MPa, were 293 K and 100V. The maximum thermal conductivity of the epoxy-treated anodized layer was 1.6 W/m·K at 273 K. Compared with the epoxy-treated Al layer used for conventional MCPCBs, the epoxy-treated anodized layer showed advanced thermal performance due to a low difference of thermal resistance and high heat dissipation.

The effect of crystal orientation on the aluminum anodes of the aluminum-air batteries in alkaline electrolytes

NASA Astrophysics Data System (ADS)

Fan, Liang; Lu, Huimin; Leng, Jing; Sun, Zegao; Chen, Chunbo

2015-12-01

Recently, aluminum-air (Al-air) batteries have received attention from researchers as an exciting option for safe and efficient batteries. The electrochemical performance of Aluminum anode remains an active area of investigation. In this paper, the electrochemical properties of polycrystalline Al, Al (001), (110) and (111) single crystals are investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in 4 M NaOH and KOH. Hydrogen corrosion rates of the Al anodes are determined by hydrogen collection. Battery performance using the anodes is tested by constant current discharge at 10 mA cm-2. This is the first report showing that the electrochemical properties of Al are closely related to the crystallographic orientation in alkaline electrolytes. The (001) crystallographic plane has good corrosion resistance but (110) is more sensitive. Al (001) single crystals display higher anode efficiency and capacity density. Controlling the crystallographic orientation of the Al anode is another way to improve the performance of Al-air batteries in alkaline electrolytes.

Fundamental Investigation of Silicon Anode in Lithium-Ion Cells

NASA Technical Reports Server (NTRS)

Wu, James J.; Bennett, William R.

2012-01-01

Silicon is a promising and attractive anode material to replace graphite for high capacity lithium ion cells since its theoretical capacity is 10 times of graphite and it is an abundant element on Earth. However, there are challenges associated with using silicon as Li-ion anode due to the significant first cycle irreversible capacity loss and subsequent rapid capacity fade during cycling. Understanding solid electrolyte interphase (SEI) formation along with the lithium ion insertion/de-insertion kinetics in silicon anodes will provide greater insight into overcoming these issues, thereby lead to better cycle performance. In this paper, cyclic voltammetry and electrochemical impedance spectroscopy are used to build a fundamental understanding of silicon anodes. The results show that it is difficult to form the SEI film on the surface of a Si anode during the first cycle; the lithium ion insertion and de-insertion kinetics for Si are sluggish, and the cell internal resistance changes with the state of lithiation after electrochemical cycling. These results are compared with those for extensively studied graphite anodes. The understanding gained from this study will help to design better Si anodes, and the combination of cyclic voltammetry with impedance spectroscopy provides a useful tool to evaluate the effectiveness of the design modifications on the Si anode performance.

Effects of Complex Structured Anodic Oxide Dielectric Layer Grown in Pore Matrix for Aluminum Capacitor.

PubMed

Shin, Jin-Ha; Yun, Sook Young; Lee, Chang Hyoung; Park, Hwa-Sun; Suh, Su-Jeong

2015-11-01

Anodization of aluminum is generally divided up into two types of anodic aluminum oxide structures depending on electrolyte type. In this study, an anodization process was carried out in two steps to obtain high dielectric strength and break down voltage. In the first step, evaporated high purity Al on Si wafer was anodized in oxalic acidic aqueous solution at various times at a constant temperature of 5 degrees C. In the second step, citric acidic aqueous solution was used to obtain a thickly grown sub-barrier layer. During the second anodization process, the anodizing potential of various ranges was applied at room temperature. An increased thickness of the sub-barrier layer in the porous matrix was obtained according to the increment of the applied anodizing potential. The microstructures and the growth of the sub-barrier layer were then observed with an increasing anodizing potential of 40 to 300 V by using a scanning electron microscope (SEM). An impedance analyzer was used to observe the change of electrical properties, including the capacitance, dissipation factor, impedance, and equivalent series resistance (ESR) depending on the thickness increase of the sub-barrier layer. In addition, the breakdown voltage was measured. The results revealed that dielectric strength was improved with the increase of sub-barrier layer thickness.

Composite electrodes for advanced electrochemical applications. Quarterly report for the period October 1, - December 31, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovach, Chris

The electrochemical industry is one of the most highly energy intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating costs, and the proprietary nature of the technology. In addition, DSAs experience problems that include: contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from underattack,more » generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.« less

Composite electrodes for advanced electrochemical applications. Quarterly report for the period July 1 - September 30, 1999

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovach, Chris

The electrochemical industry is one of the most highly energy-intensive industries today. However, there have been no significant advances in the electrodes that these industries use. The dimensionally stable anode (DSA), which ELTECH introduced under a license agreement, has been the industry standard for the past twenty-five years. But, DSAs are nearing the end of their technological prevalence. The principal problems with DSAs include high capital and operating cost, and the proprietary nature of the technology. In addition, DSAs experience problems that include contamination of the process solution by anode materials, failure when the electrocatalytic coating peels from under attack,more » generally low anode performance due to inherent limitations in operating current density, and short anode lifetime because of corrosion. The proposed innovation combines the low electrical resistance of copper with the corrosion resistance of electrically conductive diamond to achieve energy-efficient, long-lifetime electrodes for electrochemistry. The proposed work will ultimately develop a composite electrode that consists of a copper substrate, a conductive diamond coating, and a catalytic precious metal coating. The scope of the current work includes preparation, testing, and evaluation of diamond-coated titanium electrodes.« less

Battery with modular air cathode and anode cage

DOEpatents

Niksa, Marilyn J.; Pohto, Gerald R.; Lakatos, Leslie K.; Wheeler, Douglas J.; Niksa, Andrew J.; Schue, Thomas J.

1987-01-01

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

Battery with modular air cathode and anode cage

DOEpatents

Niksa, Marilyn J.; Pohto, Gerald R.; Lakatos, Leslie K.; Wheeler, Douglas J.; Niksa, Andrew J.; Schue, Thomas J.; Turk, Thomas R.

1988-01-01

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

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

PubMed

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

2013-12-01

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

Passive films on magnesium anodes in primary batteries

NASA Technical Reports Server (NTRS)

Ratnakumar, B. V.

1988-01-01

The characteristics of the passive films over Mg anodes, which essentially govern the voltage delay of the latter, have been determined nondestructively from an analysis of the transient and steady-state response of the electrode potential to low amplitude galvanostatic polarization under various experimental conditions viz., with different corrosion inhibitor coatings on Mg, after various periods of ageing of anode in solutions containing corrosion inhibitors, at various low temperatures etc. Using these parameters, the kinetics of film build-up or dissolution under these conditions have been monitored. The morphology of the anode film has been verified with scanning electron microscopy. Similar transients at low temperatures point out a steep rise in the film resistivity which is essentially responsible for the severe voltage delay. Finally, possible application of this technique in secondary Li batteries to improve cycling characteristics of the Li anode has been pointed out.

Vertically grown multiwalled carbon nanotube anode and nickel silicide integrated high performance microsized (1.25 μL) microbial fuel cell.

PubMed

Mink, Justine E; Rojas, Jhonathan P; Logan, Bruce E; Hussain, Muhammad M

2012-02-08

Microbial fuel cells (MFCs) are an environmentally friendly method for water purification and self-sustained electricity generation using microorganisms. Microsized MFCs can also be a useful power source for lab-on-a-chip and similar integrated devices. We fabricated a 1.25 μL microsized MFC containing an anode of vertically aligned, forest type multiwalled carbon nanotubes (MWCNTs) with a nickel silicide (NiSi) contact area that produced 197 mA/m(2) of current density and 392 mW/m(3) of power density. The MWCNTs increased the anode surface-to-volume ratio, which improved the ability of the microorganisms to couple and transfer electrons to the anode. The use of nickel silicide also helped to boost the output current by providing a low resistance contact area to more efficiently shuttle electrons from the anode out of the device. © 2012 American Chemical Society

Bacterial Community Analysis, New Exoelectrogen Isolation and Enhanced Performance of Microbial Electrochemical Systems Using Nano-Decorated Anodes

NASA Astrophysics Data System (ADS)

Xu, Shoutao

Microbial electrochemical systems (MESs) have attracted much research attention in recent years due to their promising applications in renewable energy generation, bioremediation, and wastewater treatment. In a MES, microorganisms interact with electrodes via electrons, catalyzing oxidation and reduction reactions at the anode and the cathode. The bacterial community of a high power mixed consortium MESs (maximum power density is 6.5W/m2) was analyzed by using denature gradient gel electrophoresis (DGGE) and 16S DNA clone library methods. The bacterial DGGE profiles were relatively complex (more than 10 bands) but only three brightly dominant bands in DGGE results. These results indicated there are three dominant bacterial species in mixed consortium MFCs. The 16S DNA clone library method results revealed that the predominant bacterial species in mixed culture is Geobacter sp (66%), Arcobacter sp and Citrobacter sp. These three bacterial species reached to 88% of total bacterial species. This result is consistent with the DGGE result which showed that three bright bands represented three dominant bacterial species. Exoelectrogenic bacterial strain SX-1 was isolated from a mediator-less microbial fuel cell by conventional plating techniques with ferric citrate as electron acceptor under anaerobic conditions. Phylogenetic analysis of the 16S rDNA sequence revealed that it was related to the members of Citrobacter genus with Citrobacter sp. sdy-48 being the most closely related species. The bacterial strain SX-1 produced electricity from citrate, acetate, glucose, sucrose, glycerol, and lactose in MFCs with the highest current density of 205 mA/m2 generated from citrate. Cyclic voltammetry analysis indicated that membrane associated proteins may play an important role in facilitating electron transfer from the bacteria to the electrode. This is the first study that demonstrates that Citrobacter species can transfer electrons to extracellular electron acceptors. Citrobacter strain SX-1 is capable of generating electricity from a wide range of substrates in MFCs. This finding increases the known diversity of power generating exoelectrogens and provids a new strain to explore the mechanisms of extracellular electron transfer from bacteria to electrode. The wide range of substrate utilization by SX-1 increases the application potential of MFCs in renewable energy generation and waste treatment. Anode properties are critical for the performance of microbial electrolysis cells (MECs). Inexpensive Fe nanoparticle modified graphite disks were used as anodes to preliminarily investigate the effects of nanoparticles on the performance of Shewanella oneidensis MR-1 in MECs. Results demonstrated that average current densities produced with Fe nanoparticle decorated anodes were up to 5.9-fold higher than plain graphite anodes. Whole genome microarray analysis of the gene expression showed that genes encoding biofilm formation were significantly up-regulated as a response to nanoparticle decorated anodes. Increased expression of genes related to nanowires, flavins and c-type cytochromes indicate that enhanced mechanisms of electron transfer to the anode may also have contributed to the observed increases in current density. The majority of the remaining differentially expressed genes were associated with electron transport and anaerobic metabolism demonstrating a systemic response to increased power loads. The carbon nanotube (CNT) is another form of nano materials. Carbon nanotube (CNT) modified graphite disks were used as anodes to investigate the effects of nanostructures on the performance S. oneidensis MR-1 in microbial electrolysis cells (MECs). The current densities produced with CNT decorated anodes were up to 5.6-fold higher than plain graphite anodes. Global transcriptome analysis showed that cytochrome c genes associated with extracellular electron transfer are up-expressed by CNT decorated anodes, which is the leading factor to contribute current increase in CNT decorated anode MECs. The up regulated genes encoded to flavin also contribute to current enhancement in CNT decorated anode MECs.

Effects of Unilateral Transcranial Direct Current Stimulation of Left Prefrontal Cortex on Processing and Memory of Emotional Visual Stimuli.

PubMed

Balzarotti, Stefania; Colombo, Barbara

2016-01-01

The dorsolateral prefrontal cortex (DLPFC) is generally thought to be involved in affect and emotional processing; however, the specific contribution of each hemisphere continues to be debated. In the present study, we employed unilateral tDCS to test the unique contribution of left DLPFC in the encoding and retrieval of emotional stimuli in healthy subjects. Forty-two right handed undergraduate students received either anodal, cathodal or sham stimulation of left DLPFC while viewing neutral, pleasant, and unpleasant pictures. After completing a filler task, participants were asked to remember as many pictures as possible. Results showed that participants were able to remember a larger amount of emotional (both pleasant and unpleasant) pictures than of neutral ones, regardless of the type of tDCS condition. Participants who received anodal stimulation recalled a significantly higher number of pleasant images than participants in the sham and cathodal conditions, while no differences emerged in the recall of neutral and unpleasant pictures. We conclude that our results provide some support to the role of left prefrontal cortex in the encoding and retrieval of pleasant stimuli.

Solution-processed copper-nickel nanowire anodes for organic solar cells

NASA Astrophysics Data System (ADS)

Stewart, Ian E.; Rathmell, Aaron R.; Yan, Liang; Ye, Shengrong; Flowers, Patrick F.; You, Wei; Wiley, Benjamin J.

2014-05-01

This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper-nickel nanowire films exhibited efficiencies of 4.9%.This work describes a process to make anodes for organic solar cells from copper-nickel nanowires with solution-phase processing. Copper nanowire films were coated from solution onto glass and made conductive by dipping them in acetic acid. Acetic acid removes the passivating oxide from the surface of copper nanowires, thereby reducing the contact resistance between nanowires to nearly the same extent as hydrogen annealing. Films of copper nanowires were made as oxidation resistant as silver nanowires under dry and humid conditions by dipping them in an electroless nickel plating solution. Organic solar cells utilizing these completely solution-processed copper-nickel nanowire films exhibited efficiencies of 4.9%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01024h

Corrosion Fatigue of Anodized Aluminum 7075-T73 in Salt Ladened Humid Air.

DTIC Science & Technology

1981-01-01

relative humidity and coating thickness on the fatigue of anodized 2024-T351 aluminum in reversed torsion . They also found no effect of coating ... fatigue resistance. Most of the previous corrosion fatigue work has been on the effect of relative humidity on the fatigue life of coated aluminum ...alloys. Eeles and 1hurston Iwere some of the early investigators

Surface breakdown igniter for mercury arc devices

DOEpatents

Bayless, John R.

1977-01-01

Surface breakdown igniter comprises a semiconductor of medium resistivity which has the arc device cathode as one electrode and has an igniter anode electrode so that when voltage is applied between the electrodes a spark is generated when electrical breakdown occurs over the surface of the semiconductor. The geometry of the igniter anode and cathode electrodes causes the igniter discharge to be forced away from the semiconductor surface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Weidong; Li, Yutao; Xin, Sen

A reversible plating/stripping of a dendrite-free metallic-sodium anode with a reduced anode/ceramic interfacial resistance is created by a thin interfacial interlayer formed in situ or by the introduction of a dry polymer film. Wetting of the sodium on the interfacial interlayer suppresses dendrite formation and growth at different discharge/charge C-rates. Furthermore, all-solid-state batteries were obtained with a high cycling stability and Coulombic efficiency at 65 °C.

Electrolyte volume effects on electrochemical performance and solid electrolyte interphase in Si-graphite/NMC lithium-ion pouch cells

DOE PAGES

An, Seong Jin; Li, Jianlin; Daniel, Claus; ...

2017-05-15

This study aims to explore the correlations between electrolyte volume, electrochemical performance, and properties of the solid electrolyte interphase in pouch cells with Si-graphite composite anodes. The electrolyte is 1.2 M LiPF 6 in ethylene carbonate:ethylmethyl carbonate with 10 wt.% fluoroethylene carbonate. Single layer pouch cells (100 mAh) were constructed with 15 wt.% Si-graphite/LiNi 0.5Mn 0.3CO 0.2O 2 electrodes. It is found that a minimum electrolyte volume factor of 3.1 times the total pore volume of cell components (cathode, anode, and separator) is needed for better cycling stability. Less electrolyte causes increases in ohmic and charge transfer resistances. Lithium dendritesmore » are observed when the electrolyte volume factor is low. The resistances from the anodes become significant as the cells are discharged. As a result, solid electrolyte interphase thickness grows as the electrolyte volume factor increases and is non-uniform after cycling.« less

Electrolyte for high voltage Li/LiMn 1.9Co 0.1O 4 cells

NASA Astrophysics Data System (ADS)

Hayashi, Katsuya; Nemoto, Yasue; Tobishima, Shin-ichi; Yamaki, Jun-ichi

An electrolyte for high voltage lithium metal anode cells must simultaneously satisfy at least the following requirements; (i) high cycling efficiency on the lithium metal anode; (ii) higher oxidation potential than the charging voltage, and (iii) high specific conductivity. We have examined various electrolytes for lithium metal anode cells using a high voltage cathode, LiMn 1.9Co 0.1O 4. Of the electrolytes resistant to high voltage that we used, a system containing 60 to 90 vol.% of dimethyl carbonate (DMC) mixed with ethylene carbonate (EC) and 1.0 M lithium hexafluorophosphate (LiPF 6) provided the best cycling efficiency on a lithium metal anode, as well as a high specific conductivity around 10 mS cm -1 at 20 °C.

Bacterial communities adapted to higher external resistance can reduce the onset potential of anode in microbial fuel cells.

PubMed

Suzuki, Kei; Kato, Yutaka; Yui, Arashi; Yamamoto, Shuji; Ando, Syota; Rubaba, Owen; Tashiro, Yosuke; Futamata, Hiroyuki

2018-05-01

We investigated how bacterial communities adapted to external resistances and exhibited the performance of electricity production in microbial fuel cells (MFCs) with external resistance of 10 Ω (LR-MFC) and 1000 Ω (HR-MFC). The HR-MFC exhibited better performance than the LR-MFC. The power densities of the LR-MFC and the HR-MFC were 5.2 ± 1.6 mW m -2 and 28 ± 9.6 mW m -2 after day 197, respectively. Low-scan cyclic voltammetry analyses indicated that the onset potential of the HR-MFC was more negative than that of the LR-MFC, suggesting that the higher external resistance led to enrichment of the highly current producing bacteria on the anode surface. All clones of Geobacter retrieved from the LR-MFC and the HR-MFC were members of the Geobacter metallireducens clade. Although the population density of Geobacter decreased from days 366-427 in the HR-MFC, the current density was almost maintained. Multidimensional scaling analyses based on denaturing gradient gel electrophoresis profiles indicated that the dynamics of the biofilm and anolytic communities changed synchronously in the two MFCs, but the dynamics of the bacterial communities in the LR-MFC and the HR-MFC were different from each other, reflecting different processes in adaptation to the different external resistances. The results suggest that the microbial community structure was formed by adapting to higher external resistance, exhibiting more negative onset potential and higher performance of the HR-MFC through collaborating with anode-respiring bacteria and fermenters. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Fabrication and electrochemical performance of a stable, anode supported thin BaCe0.4Zr0.4Y0.2O3-δ electrolyte Protonic Ceramic Fuel Cell

NASA Astrophysics Data System (ADS)

Nasani, Narendar; Ramasamy, Devaraj; Mikhalev, Sergey; Kovalevsky, Andrei V.; Fagg, Duncan P.

2015-03-01

The present work deals with the fabrication and electrochemical characterisation of a potential protonic ceramic fuel cell based on a Ni-BaZr0.85Y0.15O3-δ anode supported thin film proton conducting BaCe0.4Zr0.4Y0.2O3-δ electrolyte with a Pr2NiO4+δ cathode. Anode and electrolyte materials were prepared by an acetate-H2O2 combustion method. A thin (∼5 μm), dense and crack free BaCe0.4Zr0.4Y0.2O3-δ electrolyte film was successfully obtained on a porous anode support by spin coating and firing at 1450 °C. Maximum power densities of 234, 158, 102 and 63 mW cm-2 at 700, 650, 600 and 550 °C, respectively were achieved for the Ni-BaZr0.85Y0.15O3-δ/BaCe0.4Zr0.4Y0.2O3-δ/Pr2NiO4+δ single cell under fuel cell testing conditions. Electrode polarisation resistance was assessed at open circuit conditions by use of electrochemical impedance spectroscopy (EIS) and is shown to dominate the area specific resistance at low temperatures. Postmortem analysis by scanning electron microscopy (SEM), reveals that no delamination occurs at anode/electrolyte or electrolyte/cathode interfaces upon cell operation.

Development of Ni-Ba(Zr,Y)O3 cermet anodes for direct ammonia-fueled solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Miyazaki, Kazunari; Okanishi, Takeou; Muroyama, Hiroki; Matsui, Toshiaki; Eguchi, Koichi

2017-10-01

In this study, the availability of Ni-Ba(Zr,Y)O3-δ (BZY) cermet for the anode of direct ammonia-fueled solid oxide fuel cells (SOFCs) is evaluated. In this device, the anodes need to be active for the catalytic ammonia decomposition as well as the electrochemical hydrogen oxidation. In the catalytic activity test, ammonia decomposes completely over Ni-BZY at ca. 600 °C, while higher temperature is required to accomplish the complete decomposition over the conventional SOFC anode of Ni-yttria-stabilized zirconia cermet. The high activity of Ni-BZY is attributed to the high basicity of BZY and the high resistance to hydrogen poisoning effect. The electrochemical property of Ni-BZY anode is also evaluated with the anode-supported cell of Ni-BZY|BZY|Pt at 600-700 °C with feeding ammonia or hydrogen as a fuel. Since the residence time of ammonia fuel in the thick Ni-BZY anode is long, the difference in the cell performance between two fuels is relatively small. Furthermore, it is proved that the steam concentration in the fuel strongly affects the cell performance. We find that this factor is important to satisfy the above mentioned requirements for the anode of direct ammonia-fueled SOFCs. Throughout this study, it is concluded that Ni-BZY cermet will be a promising anode.

Electrorefining cell with parallel electrode/concentric cylinder cathode

DOEpatents

Gay, Eddie C.; Miller, William E.; Laidler, James J.

1997-01-01

A cathode-anode arrangement for use in an electrolytic cell is adapted for electrochemically refining spent nuclear fuel from a nuclear reactor and recovering purified uranium for further treatment and possible recycling as a fresh blanket or core fuel in a nuclear reactor. The arrangement includes a plurality of inner anodic dissolution baskets that are each attached to a respective support rod, are submerged in a molten lithium halide salt, and are rotationally displaced. An inner hollow cylindrical-shaped cathode is concentrically disposed about the inner anodic dissolution baskets. Concentrically disposed about the inner cathode in a spaced manner are a plurality of outer anodic dissolution baskets, while an outer hollow cylindrical-shaped is disposed about the outer anodic dissolution baskets. Uranium is transported from the anode baskets and deposited in a uniform cylindrical shape on the inner and outer cathode cylinders by rotating the anode baskets within the molten lithium halide salt. Scrapers located on each anode basket abrade and remove the spent fuel deposits on the surfaces of the inner and outer cathode cylinders, with the spent fuel falling to the bottom of the cell for removal. Cell resistance is reduced and uranium deposition rate enhanced by increasing the electrode area and reducing the anode-cathode spacing. Collection efficiency is enhanced by trapping and recovery of uranium dendrites scrapped off of the cylindrical cathodes which may be greater in number than two.

Electrorefining cell with parallel electrode/concentric cylinder cathode

DOEpatents

Gay, E.C.; Miller, W.E.; Laidler, J.J.

1997-07-22

A cathode-anode arrangement for use in an electrolytic cell is adapted for electrochemically refining spent nuclear fuel from a nuclear reactor and recovering purified uranium for further treatment and possible recycling as a fresh blanket or core fuel in a nuclear reactor. The arrangement includes a plurality of inner anodic dissolution baskets that are each attached to a respective support rod, are submerged in a molten lithium halide salt, and are rotationally displaced. An inner hollow cylindrical-shaped cathode is concentrically disposed about the inner anodic dissolution baskets. Concentrically disposed about the inner cathode in a spaced manner are a plurality of outer anodic dissolution baskets, while an outer hollow cylindrical-shaped is disposed about the outer anodic dissolution baskets. Uranium is transported from the anode baskets and deposited in a uniform cylindrical shape on the inner and outer cathode cylinders by rotating the anode baskets within the molten lithium halide salt. Scrapers located on each anode basket abrade and remove the spent fuel deposits on the surfaces of the inner and outer cathode cylinders, with the spent fuel falling to the bottom of the cell for removal. Cell resistance is reduced and uranium deposition rate enhanced by increasing the electrode area and reducing the anode-cathode spacing. Collection efficiency is enhanced by trapping and recovery of uranium dendrites scrapped off of the cylindrical cathodes which may be greater in number than two. 12 figs.

Electrochemically exfoliated graphene anodes with enhanced biocurrent production in single-chamber air-breathing microbial fuel cells.

PubMed

Najafabadi, Amin Taheri; Ng, Norvin; Gyenge, Előd

2016-07-15

Microbial fuel cells (MFCs) present promising options for environmentally sustainable power generation especially in conjunction with waste water treatment. However, major challenges remain including low power density, difficult scale-up, and durability of the cell components. This study reports enhanced biocurrent production in a membrane-free MFC, using graphene microsheets (GNs) as anode and MnOx catalyzed air cathode. The GNs are produced by ionic liquid assisted simultaneous anodic and cathodic electrochemical exfoliation of iso-molded graphite electrodes. The GNs produced by anodic exfoliation increase the MFC peak power density by over 300% compared to plain carbon cloth (i.e., 2.85Wm(-2) vs 0.66Wm(-2), respectively), and by 90% compared to conventional carbon black (i.e., Vulcan XC-72) anode. These results exceed previously reported power densities for graphene-containing MFC anodes. The fuel cell polarization results are corroborated by electrochemical impedance spectroscopy indicating three times lower charge transfer resistance for the GN anode. Material characterizations suggest that the best performing GN samples were of relatively smaller size (~500nm), with higher levels of ionic liquid induced surface functionalization during the electrochemical exfoliation process. Copyright © 2016 Elsevier B.V. All rights reserved.

Air plasma spray processing and electrochemical characterization of Cu-SDC coatings for use in solid oxide fuel cell anodes

NASA Astrophysics Data System (ADS)

Benoved, Nir; Kesler, O.

Air plasma spraying has been used to produce porous composite anodes based on Ce 0.8Sm 0.2O 1.9 (SDC) and Cu for use in solid oxide fuel cells (SOFCs). Preliminarily, a range of plasma conditions has been examined for the production of composite coatings from pre-mixed SDC and CuO powders. Plasma gas compositions were varied to obtain a range of plasma temperatures. After reduction in H 2, coatings were characterized for composition and microstructure using EDX and SEM. As a result of these tests, symmetrical sintered electrolyte-supported anode-anode cells were fabricated by air plasma spraying of the anodes, followed by in situ reduction of the CuO to Cu. Full cells deposited on SS430 porous substrates were then produced in one integrated process. Fine CuO and SDC powders have been used to produce homogeneously mixed anode coatings with higher surface area microstructures, resulting in area-specific polarization resistances of 4.8 Ω cm 2 in impedance tests in hydrogen at 712 °C.

Long-term lithium-ion battery performance improvement via ultraviolet light treatment of the graphite anode

DOE PAGES

An, Seong Jin; Li, Jianlin; Sheng, Yangping; ...

2016-01-01

Effects of ultraviolet (UV) light on dried graphite anodes were investigated in terms of the cycle life of lithium ion batteries. The time variations for the UV treatment were 0 (no treatment), 20, 40, and 60 minutes. UV-light-treated graphite anodes were assembled for cycle life tests in pouch cells with pristine Li 1.02Ni 0.50Mn 0.29Co 0.19O 2 (NMC 532) cathodes. UV treatment for 40 minutes resulted in the highest capacity retention and the lowest resistance after the cycle life testing. X-ray photoelectron spectroscopy (XPS) and contact angle measurements on the graphite anodes showed changes in surface chemistry and wetting aftermore » the UV treatment. XPS also showed increases in solvent products and decreases in salt products on the SEI surface when UV-treated anodes were used. In conclusion, the thickness of the surface films and their compositions on the anodes and cathodes were also estimated using survey scans and snapshots from XPS depth profiles.« less

Influence of anode thickness on the power output of solid oxide fuel cells with (La,Sr)(Co,Fe)-type cathode

NASA Astrophysics Data System (ADS)

Menzler, Norbert H.; Haanappel, Vincent A. C.

The influence of the thickness of the anode (functional layer) on the power output of anode-supported solid oxide fuel cells with a lanthanum-strontium-cobalt-ferrite cathode was investigated. The anode was applied by vacuum slip casting and the thickness varied between 1 and 22 μm. All other material and microstructural parameters were kept constant. Single cells with dimensions of 50 mm × 50 mm and with an active cathode area of 40 mm × 40 mm were manufactured and tested in an alumina housing with air as oxidant and hydrogen with 3% water vapour as the fuel gas. Results have shown that SOFCs with anodes between 1 and 13 μm have slightly better performance than those with thicker anodes (∼1.7 A cm -2 versus 1.5 A cm -2 at 800 °C and 0.7 V). The current densities were discussed with respect to cell area specific resistance, helium leak rate of the half-cell, and microstructure.

Metal-insulator transition in nanocomposite VOx films formed by anodic electrodeposition

NASA Astrophysics Data System (ADS)

Tsui, Lok-kun; Hildebrand, Helga; Lu, Jiwei; Schmuki, Patrik; Zangari, Giovanni

2013-11-01

The ability to grow VO2 films by electrochemical methods would open a low-cost, easily scalable production route to a number of electronic devices. We have synthesized VOx films by anodic electrodeposition of V2O5, followed by partial reduction by annealing in Ar. The resulting films are heterogeneous, consisting of various metallic/oxide phases and including regions with VO2 stoichiometry. A gradual metal insulator transition with a nearly two order of magnitude change in film resistance is observed between room temperature and 140 °C. In addition, the films exhibit a temperature coefficient of resistance of ˜ -2.4%/ °C from 20 to 140 °C.

Poly(sodium 4-styrenseulfonate)-modified monolayer graphene for anode applications of organic photovoltaic cells

NASA Astrophysics Data System (ADS)

Zhou, Yongfang; Wang, Min; Wang, Liang; Liu, Shuli; Chen, Shufen; Cao, Kun; Shang, Wenjuan; Mai, Jiangquan; Zhao, Baomin; Feng, Jing; Lu, Xinhui; Huang, Wei

2017-09-01

An insulated poly(sodium 4-styrenseulfonate) (PSS) was used to modify monolayer graphene for anode applications of organic photovoltaics (OPVs). With this PSS interfacial modification layer, the OPVs showed a significant increase of 56.4% in efficiency due to an improved work function and hydrophilic feature of graphene and an enlarged recombination resistance of carriers/excitons. Doping a highly contorted 1,2,5-thiadiazole-fused 12-ring polyaromatic hydrocarbon into the active layer to form ternary blended OPVs further enlarged the recombination resistance of carriers/excitons and improved light absorption of the active layer, with which a high power conversion efficiency of 6.29% was acquired.

Are you positive? Electric dipole polarity discrimination in the yellow stingray, Urobatis jamaicensis.

PubMed

Siciliano, Avery M; Kajiura, Stephen M; Long, John H; Porter, Marianne E

2013-10-01

It is well established that elasmobranchs can detect dipole electric fields. However, it is unclear whether they can discriminate between the anode and cathode. To investigate this subject, we employed a behavioral assay to determine the discriminatory ability of the yellow stingray, Urobatis jamaicensis. We conditioned stingrays with food rewards to bite either the anode (n=5) or the cathode (n=6) of a direct-current dipole located on the floor of an experimental tank. All individuals successfully performed the task after 18 to 22 days. Stingrays were then tested in experimental sessions when they were rewarded only after they identified the correct pole. Stingrays successfully discriminated between the poles at a rate greater than chance, ranging among individuals from a mean of 66% to 93% correct. During experimental sessions, stingrays conditioned to distinguish the anode performed similarly to those conditioned to distinguish the cathode. We hypothesize that the ability to discriminate anode from cathode is physiologically encoded, but its utility in providing spatial information under natural conditions remains to be demonstrated. The ability to discriminate polarity may eliminate ambiguity in induction-based magnetoreception and facilitate navigation with respect to the geomagnetic field.

Surface Modification of Titanium Using Anodization to Enhance Antimicrobial Properties and Osseointegration

NASA Astrophysics Data System (ADS)

Jain, Sakshi

Titanium and its alloys are frequently used in dental and orthopedic implants because they have good mechanical strength, chemical stability and biocompatibility. These properties can be further improved by surface treatments such as anodization that are able to grow thicker and produce crystalline oxide layers with controlled morphological and physico-chemical properties. Both anatase (A) and rutile (R) crystalline phases of titanium oxide have been shown to promote bioactivity and antimicrobial effects. In a previous study in our laboratories, four electrolyte mixtures were optimized to produce anodized layers on commercially pure titanium consisting of specific anatase and rutile oxide ratios at an endpoint forming voltage of 180 V. In the present study, changes that occurred in the anodized layers with increasing forming voltage including crystallinity, thickness, surface morphology, surface roughness, surface chemistry, fractal dimension, shear strength, and corrosion resistance were determined for each of these electrolytes. The results showed the crystallinity, thickness, surface pore sizes, and surface roughness increased with increasing forming voltage. Incorporation of phosphorus into the anodized layers was shown in phosphoric acid containing electrolytes at higher forming voltages. Decreases in corrosion resistance were also shown at higher forming voltages in each electrolyte due to increased pore interconnectivity within the anodized layers. In addition, the apatite inducing ability of anodized layers in SBF was examined for selected forming voltages in each electrolyte. Anodization in phosphoric acid containing electrolytes was shown to be more favorable for apatite formation. The streptococcal and MRSA bacterial attachment before and after UV treatments was determined for selected forming voltages in each electrolyte. Additionally, the killing efficacy after 10-minute pre-irradiation with UVA or UVC treatments was determined. UVA treatments showed trends of at least a 20% reduction in bacterial attachment regardless of the crystallinity within the oxide for S. sanguinis. The anodized layer with an approximately equal distribution of anatase and rutile phases showed bacterial killing efficacy over 50% for S. sanguinis and over 80% for MRSA after UVA or UVC treatments. Finally, two forming voltage sample groups in two of the electrolytes were examined for MC3T3E-1 cell attachment, proliferation, and differentiation. Total intracellular protein content, alkaline phosphatase (ALP) activity, osteocalcin (OCN) activity, and cellular mineralization were investigated for different time periods up to 21 days. All sample groups showed suitable cellular proliferation, differentiation, and maturation but those anodized in the phosphoric acid containing electrolyte showed delayed proliferation and early differentiation and maturation. Also, anodized samples containing at least 50% anatase were shown to produce higher osteoblast mineralization compared to majority rutile phase anodized layers.

Crack-resistant polyimide coating for high-capacity battery anodes

NASA Astrophysics Data System (ADS)

Li, Yingshun; Wang, Shuo; Lee, Pui-Kit; He, Jieqing; Yu, Denis Y. W.

2017-10-01

Electrode cracking is a serious problem that hinders the application of many next-generation high-capacity anode materials for lithium-ion batteries. Even though nano-sizing the material can reduce fracturing of individual particles, capacity fading is still observed due to large volume change and loss of contact in the electrode during lithium insertion and extraction. In this study, we design a crack-resistant high-modulus polyimide coating with high compressive strength which can hold multiple particles together during charge and discharge to maintain contact. The effectiveness of the coating is demonstrated on tin dioxide, a high-capacity large-volume-change material that undergoes both alloy and conversion reactions. The polyimide coating improves capacity retention of SnO2 from 80% to 100% after 80 cycles at 250 mA g-1. Stable capacity of 585 mAh g-1 can be obtained even at 500 mA g-1 after 300 cycles. Scanning electron microscopy and in-situ dilatometry confirm that electrode cracking is suppressed and thickness change is reduced with the coating. In addition, the chemically-stable polyimide film can separate the surface from direct contact with electrolyte, improving coulombic efficiency to ∼100%. We expect the novel strategy of suppressing electrode degradation with a crack-resistant coating can also be used for other alloy and conversion-based anodes.

Field emission from carbon nanotube fibers in varying anode-cathode gap with the consideration of contact resistance

NASA Astrophysics Data System (ADS)

Zhang, Peng; Fairchild, S. B.; Back, T. C.; Luo, Yi

2017-12-01

This paper studies field emission (FE) from a single carbon nanotube (CNT) fiber with different anode-cathode (AK) gap distances. It is found that the field enhancement factor depends strongly on the finite AK gap distance, due to the combination of geometrical effects and possible fiber morphology change. The geometrical effects of AK gap distance on the field enhancement factor are confirmed using COMSOL simulations. The slope drop in the Fowler-Northeim (FN) plot of the FE data in the high voltage is related to the electrical contact resistance between the CNT fiber and the substrate. It is found that even a small series resistance to the field emitter (<30% of the emission gap impedance) can strongly modify the FE characteristics in the high voltage regime, inducing a strong deviation from the linear FN plot.

The application of the barrier-type anodic oxidation method to thickness testing of aluminum films

NASA Astrophysics Data System (ADS)

Chen, Jianwen; Yao, Manwen; Xiao, Ruihua; Yang, Pengfei; Hu, Baofu; Yao, Xi

2014-09-01

The thickness of the active metal oxide film formed from a barrier-type anodizing process is directly proportional to its formation voltage. The thickness of the consumed portion of the metal film is also corresponding to the formation voltage. This principle can be applied to the thickness test of the metal films. If the metal film is growing on a dielectric substrate, when the metal film is exhausted in an anodizing process, because of the high electrical resistance of the formed oxide film, a sudden increase of the recorded voltage during the anodizing process would occur. Then, the thickness of the metal film can be determined from this voltage. As an example, aluminum films are tested and discussed in this work. This method is quite simple and is easy to perform with high precision.

Anodes for protonic ceramic fuel cells (PCFCs) =

NASA Astrophysics Data System (ADS)

Nasani, Narendar

One of the more promising possibilities for future "green" electrical energy generation is the protonic ceramic fuel cell (PCFC). PCFCs offer a low-pollution technology to generate electricity electrochemically with high efficiency. Reducing the operating temperature of solid oxide fuel cells (SOFCs) to the 500-700°C range is desirable to reduce fabrication costs and improve overall longevity. This aim can be achieved by using protonic ceramic fuel cells (PCFCs) due to their higher electrolyte conductivity at these temperatures than traditional ceramic oxide-ion conducting membranes. This thesis deals with the state of the art Ni-BaZr0.85Y0.15O3-delta cermet anodes for PCFCs. The study of PCFCs is in its initial stage and currently only a few methods have been developed to prepare suitable anodes via solid state mechanical mixing of the relevant oxides or by combustion routes using nitrate precursors. This thesis aims to highlight the disadvantages of these traditional methods of anode preparation and to, instead, offer a novel, efficient and low cost nitrate free combustion route to prepare Ni-BaZr0.85Y0.15O3-delta cermet anodes for PCFCs. A wide range of techniques mainly X-ray diffraction (XRD), scanning electron microscopy (SEM), environmental scanning electron microscopy, (ESEM) and electrochemical impedance spectroscopy (EIS) were employed in the cermet anode study. The work also offers a fundamental examination of the effect of porosity, redox cycling behaviour, involvement of proton conducting oxide phase in PCFC cermet anodes and finally progresses to study the electrochemical performance of a state of the art anode supported PCFC. The polarisation behaviour of anodes has been assessed as a function of temperature (T), water vapour (pH2O), hydrogen partial pressures (pH2) and phase purity for electrodes of comparable microstructure. The impedance spectra generally show two arcs at high frequency R2 and low frequency R3 at 600 °C, which correspond to the electrode polarisation resistance. Work shows that the R2 and R3 terms correspond to proton transport and dissociative H2 adsorption on electrode surface, respectively. The polarization resistance of the cermet anode (Rp) was shown to be significantly affected by porosity, with the PCFC cermet anode with the lowest porosity exhibiting the lowest Rp under standard operating conditions. This result highlights that porogens are not required for peak performance in PCFC anodes, a result contrary to that of their oxide-ion conducting anode counterparts. In-situ redox cycling studies demonstrate that polarisation behaviour was drastically impaired by redox cycling. In-situ measurements using an environmental scanning electron microscopy (ESEM) reveal that degradation proceeds due to volume expansion of the Ni-phase during the re-oxidation stage of redox cycling.The anode supported thin BCZY44 based protonic ceramic fuel cell, formed using a peak performing Ni-BaZr0.85Y0.15O3-delta cermet anode with no porogen, shows promising results in fuel cell testing conditions at intermediate temperatures with good durability and an overall performance that exceeds current literature data.

Activation of Pathogenesis-related Genes by the Rhizobacterium, Bacillus sp. JS, Which Induces Systemic Resistance in Tobacco Plants.

PubMed

Kim, Ji-Seong; Lee, Jeongeun; Lee, Chan-Hui; Woo, Su Young; Kang, Hoduck; Seo, Sang-Gyu; Kim, Sun-Hyung

2015-06-01

Plant growth promoting rhizobacteria (PGPR) are known to confer disease resistance to plants. Bacillus sp. JS demonstrated antifungal activities against five fungal pathogens in in vitro assays. To verify whether the volatiles of Bacillus sp. JS confer disease resistance, tobacco leaves pre-treated with the volatiles were damaged by the fungal pathogen, Rhizoctonia solani and oomycete Phytophthora nicotianae. Pre-treated tobacco leaves had smaller lesion than the control plant leaves. In pathogenesis-related (PR) gene expression analysis, volatiles of Bacillus sp. JS caused the up-regulation of PR-2 encoding β-1,3-glucanase and acidic PR-3 encoding chitinase. Expression of acidic PR-4 encoding chitinase and acidic PR-9 encoding peroxidase increased gradually after exposure of the volatiles to Bacillus sp. JS. Basic PR-14 encoding lipid transfer protein was also increased. However, PR-1 genes, as markers of salicylic acid (SA) induced resistance, were not expressed. These results suggested that the volatiles of Bacillus sp. JS confer disease resistance against fungal and oomycete pathogens through PR genes expression.

The effect of zinc (Zn) content to cell potential value and efficiency aluminium sacrificial anode in 0.2 M sulphuric acid environment

NASA Astrophysics Data System (ADS)

Akranata, Ahmad Ridho; Sulistijono, Awali, Jatmoko

2018-04-01

Sacrificial anode is sacirifial component that used to protect steel from corrosion. Generally, the component are made of aluminium and zinc in water environment. Sacrificial anode change the protected metal structure become cathodic with giving current. The advantages of aluminium is corrosion resistance, non toxicity and easy forming. Zinc generally used for coating in steel to prevent steel from corrosion. This research was conducted to analyze the effect of zinc content to the value of cell potential and efficiency aluminium sacrificial anode with sand casting method in 0.2 M sulphuric acid environment. The sacrificial anode fabrication made with alloying aluminium and zinc metals with variation composition of alloy with pure Al, Al-3Zn, Al-6Zn, and Al-9Zn with open die sand casting process. The component installed with ASTM A36 steel. After the research has been done the result showed that addition of zinc content increase the cell potential, protection efficiency, and anode efficiency from steel plate. Cell potential value measurement and weight loss measurement showed that addition of zinc content increase the cell potential value into more positive that can protected the ASTM A36 steel more efficiently that showed in weight loss measurement where the protection efficiency and anodic efficiency of Al-9Zn sacrificial anode is better than protection efficiency and anodic efficiency of pure Al. The highest protection efficiency gotten by Al-9Zn alloy

Rechargeable sodium all-solid-state battery

DOE PAGES

Zhou, Weidong; Li, Yutao; Xin, Sen; ...

2017-01-03

A reversible plating/stripping of a dendrite-free metallic-sodium anode with a reduced anode/ceramic interfacial resistance is created by a thin interfacial interlayer formed in situ or by the introduction of a dry polymer film. Wetting of the sodium on the interfacial interlayer suppresses dendrite formation and growth at different discharge/charge C-rates. Furthermore, all-solid-state batteries were obtained with a high cycling stability and Coulombic efficiency at 65 °C.

Rechargeable Sodium All-Solid-State Battery

PubMed Central

2017-01-01

A reversible plating/stripping of a dendrite-free metallic-sodium anode with a reduced anode/ceramic interfacial resistance is created by a thin interfacial interlayer formed in situ or by the introduction of a dry polymer film. Wetting of the sodium on the interfacial interlayer suppresses dendrite formation and growth at different discharge/charge C-rates. All-solid-state batteries were obtained with a high cycling stability and Coulombic efficiency at 65 °C. PMID:28149953

Creep resistant, metal-coated LiFeO.sub.2 anodes for molten carbonated fuel cells

DOEpatents

Khandkar, Ashok C.

1994-01-01

A porous, creep-resistant, metal-coated, LiFeO.sub.2 ceramic electrode for fuel cells is disclosed. The electrode is particularly useful for molten carbonate fuel cells (MCFC) although it may have utilities in solid oxide fuel cells (SOFC) as well.

Creep resistant, metal-coated LiFeO[sub 2] anodes for molten carbonated fuel cells

DOEpatents

Khandkar, A.C.

1994-08-23

A porous, creep-resistant, metal-coated, LiFeO[sub 2] ceramic electrode for fuel cells is disclosed. The electrode is particularly useful for molten carbonate fuel cells (MCFC) although it may have utilities in solid oxide fuel cells (SOFC) as well. 11 figs.

Bimodal electric tissue ablation (BETA): a study on ablation size when the anode is placed on the peritoneum and the liver.

PubMed

Tiong, Leong U; Finnie, John W; Field, John B; Maddern, Guy J

2012-07-01

In bimodal electric tissue ablation (BETA), the cathode of the DC circuit is attached to the radiofrequency (RF) electrode to increase the surrounding tissue hydration. This will delay tissue desiccation and allowing the ablation process to continue for a longer period of time before "roll-off" occurs, resulting in larger ablations compared with standard radiofrequency ablation (RFA). Previous research showed that attaching the anode to the skin using electrosurgical grounding pads would reduce the efficacy of BETA because of the high electrical resistivity of the skin. This study investigated the ablation size produced when the anode was attached to the peritoneum (BETA-peritoneum) and the liver (BETA-liver) respectively. The anode of the DC circuit in BETA was attached to the peritoneum and the liver in a pig model using ECG dots. In BETA, 9 V of DC was provided for 10 min, after which the radiofrequency generator were switched on and both electrical circuits allowed to run concurrently until "roll-off." The size of ablations produced was compared to when the anode attached to the skin (BETA-skin) and standard RFA, respectively. The sites of anode placement were examined for local tissue injury. The transverse diameters in BETA-peritoneum and BETA-liver were significantly larger compared with BETA-skin and standard RFA, respectively (P < 0.001). The axial diameter in the BETA-peritoneum and BETA-liver groups were also larger compared with the BETA-skin and RFA groups, although the differences did not reach statistical significance (P = 0.09). Hematoxylin and eosin (H and E) examination of the peritoneum and the liver where the anode was attached showed coagulation necrosis involving the superficial epithelium and the liver capsule, respectively. BETA can be used to treat larger liver tumors more effectively and may reduce the tumor recurrence rates compared with standard RFA. The efficacy of BETA depends on ensuring good electrical conductivity between the cathode and the anode of the DC circuit. Research so far has shown that BETA works best when the anode is placed deep to the skin as the stratum corneum consisted of a layer of a-nucleated cells, which have high electrical resistivity. The liver could be the ideal location to place the anode as it has excellent electrical conductivity, therefore ensuring maximum tissue hydration around the cathode to produce the largest ablations possible. Copyright © 2012 Elsevier Inc. All rights reserved.

The impact of steam and current density on carbon formation from biomass gasification tar on Ni/YSZ, and Ni/CGO solid oxide fuel cell anodes

NASA Astrophysics Data System (ADS)

Mermelstein, Joshua; Millan, Marcos; Brandon, Nigel

The combination of solid oxide fuel cells (SOFCs) and biomass gasification has the potential to become an attractive technology for the production of clean renewable energy. However the impact of tars, formed during biomass gasification, on the performance and durability of SOFC anodes has not been well established experimentally. This paper reports an experimental study on the mitigation of carbon formation arising from the exposure of the commonly used Ni/YSZ (yttria stabilized zirconia) and Ni/CGO (gadolinium-doped ceria) SOFC anodes to biomass gasification tars. Carbon formation and cell degradation was reduced through means of steam reforming of the tar over the nickel anode, and partial oxidation of benzene model tar via the transport of oxygen ions to the anode while operating the fuel cell under load. Thermodynamic calculations suggest that a threshold current density of 365 mA cm -2 was required to suppress carbon formation in dry conditions, which was consistent with the results of experiments conducted in this study. The importance of both anode microstructure and composition towards carbon deposition was seen in the comparison of Ni/YSZ and Ni/CGO anodes exposed to the biomass gasification tar. Under steam concentrations greater than the thermodynamic threshold for carbon deposition, Ni/YSZ anodes still exhibited cell degradation, as shown by increased polarization resistances, and carbon formation was seen using SEM imaging. Ni/CGO anodes were found to be more resilient to carbon formation than Ni/YSZ anodes, and displayed increased performance after each subsequent exposure to tar, likely due to continued reforming of condensed tar on the anode.

Metal-air cells comprising collapsible foam members and means for minimizing internal pressure buildup

NASA Technical Reports Server (NTRS)

Putt, Ronald A. (Inventor); Woodruff, Glenn (Inventor)

1994-01-01

This invention provides a prismatic zinc-air cell including, in general, a prismatic container having therein an air cathode, a separator and a zinc anode. The container has one or more oxygen access openings, and the air cathode is disposed in the container in gaseous communication with the oxygen access openings so as to allow access of oxygen to the cathode. The separator has a first side in electrolytic communication with the air cathode and a second side in electrolytic communication with the zinc anode. The separator isolates the cathode and the zinc anode from direct electrical contact and allows passage of electrolyte therebetween. An expansion chamber adjacent to the zinc anode is provided which accommodates expansion of the zinc anode during discharge of the cell. A suitable collapsible foam member generally occupies the expansion space, providing sufficient resistance tending to oppose movement of the zinc anode away from the separator while collapsing upon expansion of the zinc anode during discharge of the cell. One or more vent openings disposed in the container are in gaseous communication with the expansion space, functioning to satisfactorily minimize the pressure buildup within the container by venting gasses expelled as the foam collapses during cell discharge.

Cycle life performance of rechargeable lithium ion batteries and mathematical modeling

NASA Astrophysics Data System (ADS)

Ning, Gang

Capacity fade of commercial Sony US 18650 Li-ion batteries cycled at high discharge rates was studied at ambient temperature. Battery cycled at the highest discharge rate (3 C) shows the largest internal resistance increase of 27.7% relative to the resistance of fresh battery. It's been observed anode carbon loses 10.6% of its capability to intercalate or deintercalate Li+ after it was subjected to 300 cycles at discharge rate of 3 C. This loss dominates capacity fade of full battery. A mechanism considering continuous parasitic reaction at anode/electrolyte interface and film thickening has been proposed. First principles based charge-discharge models to simulate cycle life behavior of rechargeable Li-ion batteries have been developed. In the generalized model, transport in both electrolyte phase and solid phase were simultaneously taken into account. Under mild charge-discharge condition, transport of lithium in the electrolyte phase has been neglected in the simplified model. Both models are based on loss of the active lithium ions due to the electrochemical parasitic reaction at anode/electrolyte interface and on rise of the anode film resistance. The effect of parameters such as depth of discharge (DOD), end of charge voltage (EOCV) and overvoltage of the parasitic reaction on the cycle life behavior of a battery has been analyzed. The experimental results obtained at a charge rate of 1 C, discharge rate of 0.5 C, EOCV of 4.0 V and DOD of 0.4 have been used to validate cycle life models. Good agreement between the simulations and the experiments has been achieved up to 1968 cycles with both models. Simulation of cycle life of battery under multiple cycling regimes has also been demonstrated.

Effects of Unilateral Transcranial Direct Current Stimulation of Left Prefrontal Cortex on Processing and Memory of Emotional Visual Stimuli

PubMed Central

Balzarotti, Stefania

2016-01-01

The dorsolateral prefrontal cortex (DLPFC) is generally thought to be involved in affect and emotional processing; however, the specific contribution of each hemisphere continues to be debated. In the present study, we employed unilateral tDCS to test the unique contribution of left DLPFC in the encoding and retrieval of emotional stimuli in healthy subjects. Forty-two right handed undergraduate students received either anodal, cathodal or sham stimulation of left DLPFC while viewing neutral, pleasant, and unpleasant pictures. After completing a filler task, participants were asked to remember as many pictures as possible. Results showed that participants were able to remember a larger amount of emotional (both pleasant and unpleasant) pictures than of neutral ones, regardless of the type of tDCS condition. Participants who received anodal stimulation recalled a significantly higher number of pleasant images than participants in the sham and cathodal conditions, while no differences emerged in the recall of neutral and unpleasant pictures. We conclude that our results provide some support to the role of left prefrontal cortex in the encoding and retrieval of pleasant stimuli. PMID:27433807

Genome-Wide Architecture of Disease Resistance Genes in Lettuce

PubMed Central

Christopoulou, Marilena; Wo, Sebastian Reyes-Chin; Kozik, Alex; McHale, Leah K.; Truco, Maria-Jose; Wroblewski, Tadeusz; Michelmore, Richard W.

2015-01-01

Genome-wide motif searches identified 1134 genes in the lettuce reference genome of cv. Salinas that are potentially involved in pathogen recognition, of which 385 were predicted to encode nucleotide binding-leucine rich repeat receptor (NLR) proteins. Using a maximum-likelihood approach, we grouped the NLRs into 25 multigene families and 17 singletons. Forty-one percent of these NLR-encoding genes belong to three families, the largest being RGC16 with 62 genes in cv. Salinas. The majority of NLR-encoding genes are located in five major resistance clusters (MRCs) on chromosomes 1, 2, 3, 4, and 8 and cosegregate with multiple disease resistance phenotypes. Most MRCs contain primarily members of a single NLR gene family but a few are more complex. MRC2 spans 73 Mb and contains 61 NLRs of six different gene families that cosegregate with nine disease resistance phenotypes. MRC3, which is 25 Mb, contains 22 RGC21 genes and colocates with Dm13. A library of 33 transgenic RNA interference tester stocks was generated for functional analysis of NLR-encoding genes that cosegregated with disease resistance phenotypes in each of the MRCs. Members of four NLR-encoding families, RGC1, RGC2, RGC21, and RGC12 were shown to be required for 16 disease resistance phenotypes in lettuce. The general composition of MRCs is conserved across different genotypes; however, the specific repertoire of NLR-encoding genes varied particularly of the rapidly evolving Type I genes. These tester stocks are valuable resources for future analyses of additional resistance phenotypes. PMID:26449254

Direct measurements of anode/cathode gap plasma in cylindrically imploding loads on the Z machine

NASA Astrophysics Data System (ADS)

Porwitzky, A.; Dolan, D. H.; Martin, M. R.; Laity, G.; Lemke, R. W.; Mattsson, T. R.

2018-06-01

By deploying a photon Doppler velocimetry based plasma diagnostic, we have directly observed low density plasma in the load anode/cathode gap of cylindrically converging pulsed power targets. The arrival of this plasma is temporally correlated with gross current loss and subtle power flow differences between the anode and the cathode. The density is in the range where Hall terms in the electromagnetic equations are relevant, but this physics is lacking in the magnetohydrodynamics codes commonly used to design, analyze, and optimize pulsed power experiments. The present work presents evidence of the importance of physics beyond traditional resistive magnetohydrodynamics for the design of pulsed power targets and drivers.

First principles calculations on the influence of solute elements and chlorine adsorption on the anodic corrosion behavior of Mg (0001) surface

NASA Astrophysics Data System (ADS)

Luo, Zhe; Zhu, Hong; Ying, Tao; Li, Dejiang; Zeng, Xiaoqin

2018-06-01

The influences of solute atoms (Li, Al, Mn, Zn, Fe, Ni, Cu, Y, Zr) and Cl adsorption on the anodic corrosion performance on Mg (0001) surface have been investigated based on first-principles calculations, which might be useful for the design of corrosion-resistant Mg alloys. Work function and local electrode potential shift are chosen as descriptors since they quantify the barrier for charge transfer and anodic stability. We found that at 25% surface doping rate, Y decreased the work function of Mg, while the impact of remaining doping elements on the work function of Mg was trivial due to the small surface dipole moment change. The adsorption of Cl destabilized the Mg atoms at surface by weakening the bonding between surface Mg atoms. We find that a stronger hybridization of d orbits of alloying elements (e.g. Zr) with the orbits of Mg can greatly increase the local electrode potential,which even overbalances the negative effect introduced by Cl adsorbates and hence improves the corrosion resistance of Mg alloys.

A novel design of anode-supported solid oxide fuel cells with Y 2O 3-doped Bi 2O 3, LaGaO 3 and La-doped CeO 2 trilayer electrolyte

NASA Astrophysics Data System (ADS)

Guo, Weimin; Liu, Jiang

Anode-supported solid oxide fuel cells (SOFCs) with a trilayered yttria-doped bismuth oxide (YDB), strontium- and magnesium-doped lanthanum gallate (LSGM) and lanthanum-doped ceria (LDC) composite electrolyte film are developed. The cell with a YDB (18 μm)/LSGM (19 μm)/LDC (13 μm) composite electrolyte film (designated as cell-A) shows the open-circuit voltages (OCVs) slightly higher than that of a cell with an LSGM (31 μm)/LDC (17 μm) electrolyte film (designated as cell-B) in the operating temperature range of 500-700 °C. The cell-A using Ag-YDB composition as cathode exhibits lower polarization resistance and ohmic resistance than those of a cell-B at 700 °C. The results show that the introduction of YDB to an anode-supported SOFC with a LSGM/LDC composite electrolyte film can effectively block electronic transport through the cell and thus increased the OCVs, and can help the cell to achieve higher power output.

A novel bio-electrochemical system with sand/activated carbon separator, Al anode and bio-anode integrated micro-electrolysis/electro-flocculation cost effectively treated high load wastewater with energy recovery.

PubMed

Gao, Changfei; Liu, Lifen; Yang, Fenglin

2018-02-01

A novel bio-electrochemical system (BES) was developed by integrating micro-electrolysis/electro-flocculation from attaching a sacrificing Al anode to the bio-anode, it effectively treated high load wastewater with energy recovery (maximum power density of 365.1 mW/m 3 and a maximum cell voltage of 0.97 V), and achieving high removals of COD (>99.4%), NH 4 + -N (>98.7%) and TP (>98.6%). The anode chamber contains microbes, activated carbon (AC)/graphite granules and Al anode. It was separated from the cathode chamber containing bifunctional catalytic and filtration membrane cathode (loaded with Fe/Mn/C/F/O catalyst) by a multi-medium chamber (MMC) filled with manganese sand and activated carbon granules, which replaced expensive PEM and reduced cost. An air contact oxidation bed for aeration was still adopted before liquid entering the cathode chamber. micro-electrolysis/electro-flocculation helps in achieving high removal efficiencies and contributes to membrane fouling migration. The increase of activated carbon in the separator MMC increased power generation and reduced system electric resistance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Learning from Bacteriophages - Advantages and Limitations of Phage and Phage-Encoded Protein Applications

PubMed Central

Drulis-Kawa, Zuzanna; Majkowska-Skrobek, Grażyna; Maciejewska, Barbara; Delattre, Anne-Sophie; Lavigne, Rob

2012-01-01

The emergence of bacteria resistance to most of the currently available antibiotics has become a critical therapeutic problem. The bacteria causing both hospital and community-acquired infections are most often multidrug resistant. In view of the alarming level of antibiotic resistance between bacterial species and difficulties with treatment, alternative or supportive antibacterial cure has to be developed. The presented review focuses on the major characteristics of bacteriophages and phage-encoded proteins affecting their usefulness as antimicrobial agents. We discuss several issues such as mode of action, pharmacodynamics, pharmacokinetics, resistance and manufacturing aspects of bacteriophages and phage-encoded proteins application. PMID:23305359

Research on low-temperature anodic bonding using induction heating

NASA Astrophysics Data System (ADS)

Chen, Mingxiang; Yi, Xinjian; Yuan, Liulin; Liu, Sheng

2006-04-01

This paper presents a new low temperature silicon-glass anodic bonding process using induction heating. Anodic bonding between silicon and glass (Pyrex 7740) has been achieved at temperature below 300 °C and almost bubble-free interfaces have been obtained. A 1KW 400KHz power supply is used to induce heat in graphite susceptors (simultaneously as the high-voltage electrodes of anodic bonding), which conduct heat to the bonding pair and permanently join the pair in 5 minutes. The results of pull tests indicate a bonding strength of above 5.0MPa for induction heating, which is greater than the strength for resistive heating at the same temperature. The fracture mainly occurs across the interface or inside the glass other than in the interface when the bonding temperature is over 200 °C Finally, the interfaces are examined and analyzed by scanning electron microscopy (SEM) and the bonding mechanisms are discussed.

Lithium-ion diffusion mechanisms in the battery anode material Li(1+x)V(1-x)O₂.

PubMed

Panchmatia, Pooja M; Armstrong, A Robert; Bruce, Peter G; Islam, M Saiful

2014-10-21

Layered Li(1+x)V(1-x)O2 has attracted recent interest as a potential low voltage and high energy density anode material for lithium-ion batteries. A greater understanding of the lithium-ion transport mechanisms is important in optimising such oxide anodes. Here, stoichiometric LiVO2 and Li-rich Li1.07V0.93O2 are investigated using atomistic modelling techniques. Lithium-ion migration is not found in LiVO2, which has also previously shown to be resistant to lithium intercalation. Molecular dynamics simulations of lithiated non-stoichiometric Li(1.07+y)V0.93O2 suggest cooperative interstitial Li(+) diffusion with favourable migration barriers and diffusion coefficients (D(Li)), which are facilitated by the presence of lithium in the transition metal layers; such transport behaviour is important for high rate performance as a battery anode.

Polymyxins: Antibacterial Activity, Susceptibility Testing, and Resistance Mechanisms Encoded by Plasmids or Chromosomes

PubMed Central

Jayol, Aurélie; Nordmann, Patrice

2017-01-01

SUMMARY Polymyxins are well-established antibiotics that have recently regained significant interest as a consequence of the increasing incidence of infections due to multidrug-resistant Gram-negative bacteria. Colistin and polymyxin B are being seriously reconsidered as last-resort antibiotics in many areas where multidrug resistance is observed in clinical medicine. In parallel, the heavy use of polymyxins in veterinary medicine is currently being reconsidered due to increased reports of polymyxin-resistant bacteria. Susceptibility testing is challenging with polymyxins, and currently available techniques are presented here. Genotypic and phenotypic methods that provide relevant information for diagnostic laboratories are presented. This review also presents recent works in relation to recently identified mechanisms of polymyxin resistance, including chromosomally encoded resistance traits as well as the recently identified plasmid-encoded polymyxin resistance determinant MCR-1. Epidemiological features summarizing the current knowledge in that field are presented. PMID:28275006

Ion implantation of highly corrosive electrolyte battery components

DOEpatents

Muller, R.H.; Zhang, S.

1997-01-14

A method of producing corrosion resistant electrodes and other surfaces in corrosive batteries using ion implantation is described. Solid electrically conductive material is used as the ion implantation source. Battery electrode grids, especially anode grids, can be produced with greatly increased corrosion resistance for use in lead acid, molten salt, and sodium sulfur. 6 figs.

Ion implantation of highly corrosive electrolyte battery components

DOEpatents

Muller, Rolf H.; Zhang, Shengtao

1997-01-01

A method of producing corrosion resistant electrodes and other surfaces in corrosive batteries using ion implantation is described. Solid electrically conductive material is used as the ion implantation source. Battery electrode grids, especially anode grids, can be produced with greatly increased corrosion resistance for use in lead acid, molten salt, end sodium sulfur.

On the localization properties of an RPWELL gas-avalanche detector

NASA Astrophysics Data System (ADS)

Moleri, L.; Bhattacharya, P.; Coimbra, A. E. C.; Breskin, A.; Bressler, S.

2017-10-01

A study of the localization properties of a single-element Resistive Plate WELL (RPWELL) detector is presented. The detector comprises of a single-sided THick Gaseous Electron Multiplier (THGEM) coupled to a segmented readout anode through a doped silicate-glass plate of 1010 Ωṡcm bulk resistivity. Operated in ambient \

Metal resistant plants and phytoremediation of environmental contamination

DOEpatents

Meagher, Richard B.; Li, Yujing; Dhankher, Om P.

2010-04-20

The present disclosure provides a method of producing transgenic plants which are resistant to at least one metal ion by transforming the plant with a recombinant DNA comprising a nucleic acid encoding a bacterial arsenic reductase under the control of a plant expressible promoter, and a nucleic acid encoding a nucleotide sequence encoding a phytochelatin biosynthetic enzyme under the control of a plant expressible promoter. The invention also relates a method of phytoremediation of a contaminated site by growing in the site a transgenic plant expressing a nucleic acid encoding a bacterial arsenate reductase and a nucleic acid encoding a phytochelatin biosynthetic enzyme.

Technological capabilities of surface layers formation on implant made of Ti-6Al-4V ELI alloy.

PubMed

Kiel-Jamrozik, Marta; Szewczenko, Janusz; Basiaga, Marcin; Nowińska, Katarzyna

2015-01-01

The aim of the presented research was to find a combination of surface modification methods of implants made of the Ti-6Al-4V ELI alloy, that lead to formation of effective barrier for metallic ions that may infiltrate into solution. To this end, the following tests were carried out: roughness measurement, the voltamperometric tests (potentiodynamic and potentiostatic), and the ion infiltration test. The electropolishing process resulted in the lowering of surface roughness in comparison with mechanical treatment of the surface layer. The anodization process and steam sterilization increased corrosion resistance regardless of the mechanical treatment or electropolishing. The crevice corrosion tests revealed that independent of the modification method applied, the Ti-6Al-4V ELI alloy has excellent crevice corrosion resistance. The smallest quantity of ions infiltrated to the solution was observed for surface modification consisting in the mechanical treatment and anodization with the potential of 97 V. Electric parameters deter- mined during studies were the basis for effectiveness estimation of particular surface treatment methods. The research has shown that the anodization process significantly influences the pitting corrosion resistance of the Ti-6Al-4V ELI alloy independent of the previous surface treatment methods (mechanical and electrochemical). The surface layer after such modification is a protective barrier for metallic ions infiltrated to solution and protects titanium alloy against corrosive environment influence.

Effective NiMn Nanoparticles-Functionalized Carbon Felt as an Effective Anode for Direct Urea Fuel Cells.

PubMed

Barakat, Nasser A M; Alajami, Mohannad; Ghouri, Zafar Khan; Al-Meer, Saeed

2018-05-16

The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron transport is created between the two layers. Electrocatalyst-functionalized gas diffusion layer (GDL) can distinctly reduce the interfacial resistance between the catalyst layer and the GDL. In this study, NiMn nanoparticles-decorated carbon felt is introduced as functionalized GDL to be exploited as a ready-made anode in a direct urea fuel cell. The proposed treated GDL was prepared by calcination of nickel acetate/manganese acetate-loaded carbon felt under an argon atmosphere at 850 °C. The physiochemical characterizations confirmed complete reduction for the utilized precursors and deposition of pristine NiMn nanoparticles on the carbon felt fiber. In passive direct urea fuel cells, investigation the performance of the functionalized GDLs indicated that the composition of the metal nanoparticles has to be optimized as the GDL obtained from 40 wt % manganese acetate reveals the maximum generated power density; 36 mW/m² at room temperature and 0.5 M urea solution. Moreover, the electrochemical measurements proved that low urea solution concentration is preferred as utilizing 0.5 M solution resulted into generating higher power compared to 1.0 and 2.0 M solution. Overall, this study opens a new avenue toward functionalization of the GDL as a novel strategy to overcome the interfacial resistance between the electrocatalyst and the GDL.

Effective NiMn Nanoparticles-Functionalized Carbon Felt as an Effective Anode for Direct Urea Fuel Cells

PubMed Central

Barakat, Nasser A. M.; Alajami, Mohannad; Ghouri, Zafar Khan; Al-Meer, Saeed

2018-01-01

The internal resistances of fuel cells strongly affect the generated power. Basically, in the fuel cell, the anode can be prepared by deposition of a film from the functional electrocatalyst on a proper gas diffusion layer. Accordingly, an interfacial resistance for the electron transport is created between the two layers. Electrocatalyst-functionalized gas diffusion layer (GDL) can distinctly reduce the interfacial resistance between the catalyst layer and the GDL. In this study, NiMn nanoparticles-decorated carbon felt is introduced as functionalized GDL to be exploited as a ready-made anode in a direct urea fuel cell. The proposed treated GDL was prepared by calcination of nickel acetate/manganese acetate-loaded carbon felt under an argon atmosphere at 850 °C. The physiochemical characterizations confirmed complete reduction for the utilized precursors and deposition of pristine NiMn nanoparticles on the carbon felt fiber. In passive direct urea fuel cells, investigation the performance of the functionalized GDLs indicated that the composition of the metal nanoparticles has to be optimized as the GDL obtained from 40 wt % manganese acetate reveals the maximum generated power density; 36 mW/m2 at room temperature and 0.5 M urea solution. Moreover, the electrochemical measurements proved that low urea solution concentration is preferred as utilizing 0.5 M solution resulted into generating higher power compared to 1.0 and 2.0 M solution. Overall, this study opens a new avenue toward functionalization of the GDL as a novel strategy to overcome the interfacial resistance between the electrocatalyst and the GDL. PMID:29772710

Investigation of the mechanical and chemical characteristics of nanotubular and nano-pitted anodic films on grade 2 titanium dental implant materials.

PubMed

Weszl, Miklós; Tóth, Krisztián László; Kientzl, Imre; Nagy, Péter; Pammer, Dávid; Pelyhe, Liza; Vrana, Nihal E; Scharnweber, Dieter; Wolf-Brandstetter, Cornelia; Joób F, Árpád; Bognár, Eszter

2017-09-01

The objective of this study was to investigate the reproducibility, mechanical integrity, surface characteristics and corrosion behavior of nanotubular (NT) titanium oxide arrays in comparison with a novel nano-pitted (NP) anodic film. Surface treatment processes were developed to grow homogenous NT and NP anodic films on the surface of grade 2 titanium discs and dental implants. The effect of process parameters on the surface characteristics and reproducibility of the anodic films was investigated and optimized. The mechanical integrity of the NT and NP anodic films were investigated by scanning electron microscopy, surface roughness measurement, scratch resistance and screwing tests, while the chemical and physicochemical properties were investigated in corrosion tests, contact angle measurement and X-ray photoelectron spectroscopy (XPS). The growth of NT anodic films was highly affected by process parameters, especially by temperature, and they were apt to corrosion and exfoliation. In contrast, the anodic growth of NP film showed high reproducibility even on the surface of 3-dimensional screw dental implants and they did not show signs of corrosion and exfoliation. The underlying reason of the difference in the tendency for exfoliation of the NT and NP anodic films is unclear; however the XPS analysis revealed fluorine dopants in a magnitude larger concentration on NT anodic film than on NP surface, which was identified as a possible causative. Concerning other surface characteristics that are supposed to affect the biological behavior of titanium implants, surface roughness values were found to be similar, whereas considerable differences were revealed in the wettability of the NT and NP anodic films. Our findings suggest that the applicability of NT anodic films on the surface of titanium bone implants may be limited because of mechanical considerations. In contrast, it is worth to consider the applicability of nano-pitted anodic films over nanotubular arrays for the enhancement of the biological properties of titanium implants. Copyright © 2017 Elsevier B.V. All rights reserved.

Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application

PubMed Central

Slaughter, Gymama; Stevens, Brian

2015-01-01

Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 μW/ cm2 in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm2, respectively. PMID:26580661

Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application.

PubMed

Slaughter, Gymama; Stevens, Brian

2015-11-16

Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 mW/ cm² in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm², respectively.

Challenges in Accommodating Volume Change of Si Anodes for Li-Ion Batteries

PubMed Central

Ko, Minseong; Chae, Sujong; Cho, Jaephil

2015-01-01

Si has been considered as a promising alternative anode for next-generation Li-ion batteries (LIBs) because of its high theoretical energy density, relatively low working potential, and abundance in nature. However, Si anodes exhibit rapid capacity decay and an increase in the internal resistance, which are caused by the large volume changes upon Li insertion and extraction. This unfortunately limits their practical applications. Therefore, managing the total volume change remains a critical challenge for effectively alleviating the mechanical fractures and instability of solid-electrolyte-interphase products. In this regard, we review the recent progress in volume-change-accommodating Si electrodes and investigate their ingenious structures with significant improvements in the battery performance, including size-controlled materials, patterned thin films, porous structures, shape-preserving shell designs, and graphene composites. These representative approaches potentially overcome the large morphologic changes in the volume of Si anodes by securing the strain relaxation and structural integrity in the entire electrode. Finally, we propose perspectives and future challenges to realize the practical application of Si anodes in LIB systems. PMID:27525208

Steamed cake-derived 3D carbon foam with surface anchored carbon nanoparticles as freestanding anodes for high-performance microbial fuel cells.

PubMed

Yuan, Haoran; Dong, Ge; Li, Denian; Deng, Lifang; Cheng, Peng; Chen, Yong

2018-09-15

Anode design is highly significant for microbial fuel cells, since it simultaneously serves as the scaffold for electroactive microorganisms and as a medium for electron migration. In this study, a stiff 3D carbon foam with surface anchored nitrogen-containing carbon nanoparticles was facilely constructed via in-situ polyaniline coating of carbonized steamed cake prior to the carbonization process. The resultant product was determined to be an excellent freestanding anode that enabled the microbial fuel cell to deliver a maximum power density of up to 1307 mW/m 2 , which significantly outperformed its non-coated counterpart, the widely used commercial carbon felt. Further investigations revealed that the overall performance enhancement was associated with the open porosity, enlarged electroactive surface, increased biocompatibility, and decreased electric resistance of the anode scaffold. This promising anode material would offer a green and economical option for fabricating high-performance microbial fuel cell-based devices towards various ends. Copyright © 2018 Elsevier B.V. All rights reserved.

Optimization of Semitransparent Anode Electrode for Flexible Green and Red Phosphorescent Organic Light-Emitting Diodes.

PubMed

Lee, Ho Won; Park, Jaehoon; Yang, Hyung Jin; Lee, Song Eun; Lee, Seok Jae; Koo, Ja Ryong; Kim, Hye Jeong; Yoon, Seung Soo; Kim, Young Kwan

2015-03-01

In this paper, we demonstrated thin film semitransparent anode electrode using Ni/Ag/Ni (3/6/3 nm) on green and red phosphorescent OLEDs, which have basically high efficiency and good optical characteristics. Moreover, we applied this semitransparent anode on flexible green and red phosphorescent OLEDs, which were then optimized for possible applications on flexible substrates. First, we studied optimization using various conditions of Ni/Ag/Ni electrodes via transmittance and sheet resistance. We then fabricated the devices on a glass substrate with ITO or Ni/Ag/Ni electrodes as well as on a flexible substrate with a Ni/Ag/Ni electrode for green and red phosphorescent OLEDs. Consequently, we could be proposed that the potential of our semitransparent anode electrode is demonstrated. Green phosphorescent OLEDs characteristics using ITO or Ni/Ag/Ni anode electrodes were coincided and those of the red phosphorescent OLEDs were improved by semitransparent electrodes at 10,000 cd/m2 criterion. Therefore, this research suggests for additional studies to be conducted on flexible and high-performance phosphorescent OLED displays and light applications for ITO-free processes.

Effect of composites based nickel foam anode in microbial fuel cell using Acetobacter aceti and Gluconobacter roseus as a biocatalysts.

PubMed

Karthikeyan, Rengasamy; Krishnaraj, Navanietha; Selvam, Ammaiyappan; Wong, Jonathan Woon-Chung; Lee, Patrick K H; Leung, Michael K H; Berchmans, Sheela

2016-10-01

This study explores the use of materials such as chitosan (chit), polyaniline (PANI) and titanium carbide (TC) as anode materials for microbial fuel cells. Nickel foam (NF) was used as the base anode substrate. Four different types of anodes (NF, NF/PANI, NF/PANI/TC, NF/PANI/TC/Chit) are thus prepared and used in batch type microbial fuel cells operated with a mixed consortium of Acetobacter aceti and Gluconobacter roseus as the biocatalysts and bad wine as a feedstock. A maximum power density of 18.8Wm(-3) (≈2.3 times higher than NF) was obtained in the case of the anode modified with a composite of PANI/TC/Chit. The MFCs running under a constant external resistance of (50Ω) yielded 14.7% coulombic efficiency with a maximum chemical oxygen demand (COD) removal of 87-93%. The overall results suggest that the catalytic materials embedded in the chitosan matrix show the best performance and have potentials for further development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anodized porous titanium coated with Ni-CeO2 deposits for enhancing surface toughness and wear resistance

NASA Astrophysics Data System (ADS)

Zhou, Xiaowei; Ouyang, Chun

2017-05-01

In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO2 nanocomposite coatings. Regarding TiO2 barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO2 deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO2 nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO2 nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO2 coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200 nm was achieved using the Phosphate-type anodizing solution at DC 150 V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO2 deposits, showing the existing Ce-rich worn products to be acted as a solid lubricant phase for making a self-healing effect on de-lamination failures. More important, this finding will be the guidelines for Ce-rich precipitations to be expected as the strengthening phase in anodized porous of Ti, Al and Mg alloys for intensifying their surface properties.

Performance enhancement of molten carbonate-based direct carbon fuel cell (MC-DCFC) via adding mixed ionic-electronic conductors into Ni anode catalyst layer

NASA Astrophysics Data System (ADS)

Lee, Eun-Kyung; Park, Shin-Ae; Jung, Hyun-Woo; Kim, Yong-Tae

2018-05-01

A high overpotential in the anode of Direct Carbon Fuel Cells (DCFC) is ascribed to the sluggish kinetics of solid fuel oxidation. In this study, we demonstrate a unique approach to enhance the performance of molten-carbonate electrolyte based DCFC (MC-DCFC) by decreasing a serious polarization loss at the anode side; a simple addition of lanthanum strontium cobalt ferrite (LSCF) having a function of mixed ionic-electronic conductors (MIEC) into the Ni anode catalyst layer. Ni:LSCF = 1:1 showed markedly enhanced peak power density of 111 mW/cm2, approximately two-fold higher value than that for the anode using solely Ni and one of the best record in the literature value using carbon black fuel without any contribution of generated syngas oxidation. As can be noted from the electrochemical impedance spectroscopy data, the ohmic and the charge transfer resistance of the anode was markedly decreased owing to the high ionic-electronic conductivity of the MIECs. Furthermore, the enhanced performance can be also attributed to the maximized TPBs (triple phase boundaries) that participate in the carbon oxidation reaction. Based on the results, we suggest that the addition of MIEC materials into the Ni anode catalyst layer is a promising approach to improve the performance of MC-DCFC.

A High-Performing Sulfur-Tolerant and Redox-Stable Layered Perovskite Anode for Direct Hydrocarbon Solid Oxide Fuel Cells

PubMed Central

Ding, Hanping; Tao, Zetian; Liu, Shun; Zhang, Jiujun

2015-01-01

Development of alternative ceramic oxide anode materials is a key step for direct hydrocarbon solid oxide fuel cells (SOFCs). Several lanthanide based layered perovskite-structured oxides demonstrate outstanding oxygen diffusion rate, favorable electronic conductivity, and good oxygen surface exchange kinetics, owing to A-site ordered structure in which lanthanide and alkali-earth ions occupy alternate (001) layers and oxygen vacancies are mainly located in [LnOx] planes. Here we report a nickel-free cation deficient layered perovskite, (PrBa)0.95(Fe0.9Mo0.1)2O5 + δ (PBFM), for SOFC anode, and this anode shows an outstanding performance with high resistance against both carbon build-up and sulfur poisoning in hydrocarbon fuels. At 800 °C, the layered PBFM showed high electrical conductivity of 59.2 S cm−1 in 5% H2 and peak power densities of 1.72 and 0.54 W cm−2 using H2 and CH4 as fuel, respectively. The cell exhibits a very stable performance under a constant current load of 1.0 A cm−2. To our best knowledge, this is the highest performance of ceramic anodes operated in methane. In addition, the anode is structurally stable at various fuel and temperature conditions, suggesting that it is a feasible material candidate for high-performing SOFC anode. PMID:26648509

Polypyrrole/sargassum activated carbon modified stainless-steel sponge as high-performance and low-cost bioanode for microbial fuel cells

NASA Astrophysics Data System (ADS)

Wu, Gaoming; Bao, Han; Xia, Zheng; Yang, Bin; Lei, Lecheng; Li, Zhongjian; Liu, Chunxian

2018-04-01

Anode materials, as the core component of microbial fuel cells (MFCs), have huge impacts on power generation performance and overall cost. Stainless-steel sponge (SS) can be a promising material for MFC anodes, due to its open continuous three-dimensional structure, high conductivity and low cost. However, poor biocompatibility limits its application. In this paper, a polypyrrole/sargassum activated carbon modified SS anode (Ppy/SAC/SS) is developed by electrochemical polymerization of pyrrole on the SS with the SAC as a dopant. The maximum power density achieved with the Ppy/SAC/SS anode is 45.2 W/m3, which is increased by 2 orders of magnitude and 2.9 times compared with an unmodified SS anode and a solely Ppy modified SS anode (Ppy/SS), respectively. In addition, the Ppy/SAC layer effectively eliminates electrochemical corrosion of the SS substrate. Electrochemical impedance spectroscopy reveals that Ppy/SAC modification decreases electron transfer resistance between the bacteria and the electrode. Furthermore, in vivo fluorescence imaging indicates that a more uniform biofilm is formed on the Ppy/SAC/SS compared to the unmodified SS and Ppy/SS. Due to the low cost of the materials, easy fabrication process and relatively high performance, our developed Ppy/SAC/SS can be a cost efficient anode material for MFCs in practical applications.

A High-Performing Sulfur-Tolerant and Redox-Stable Layered Perovskite Anode for Direct Hydrocarbon Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Ding, Hanping; Tao, Zetian; Liu, Shun; Zhang, Jiujun

2015-12-01

Development of alternative ceramic oxide anode materials is a key step for direct hydrocarbon solid oxide fuel cells (SOFCs). Several lanthanide based layered perovskite-structured oxides demonstrate outstanding oxygen diffusion rate, favorable electronic conductivity, and good oxygen surface exchange kinetics, owing to A-site ordered structure in which lanthanide and alkali-earth ions occupy alternate (001) layers and oxygen vacancies are mainly located in [LnOx] planes. Here we report a nickel-free cation deficient layered perovskite, (PrBa)0.95(Fe0.9Mo0.1)2O5 + δ (PBFM), for SOFC anode, and this anode shows an outstanding performance with high resistance against both carbon build-up and sulfur poisoning in hydrocarbon fuels. At 800 °C, the layered PBFM showed high electrical conductivity of 59.2 S cm-1 in 5% H2 and peak power densities of 1.72 and 0.54 W cm-2 using H2 and CH4 as fuel, respectively. The cell exhibits a very stable performance under a constant current load of 1.0 A cm-2. To our best knowledge, this is the highest performance of ceramic anodes operated in methane. In addition, the anode is structurally stable at various fuel and temperature conditions, suggesting that it is a feasible material candidate for high-performing SOFC anode.

A High-Performing Sulfur-Tolerant and Redox-Stable Layered Perovskite Anode for Direct Hydrocarbon Solid Oxide Fuel Cells.

PubMed

Ding, Hanping; Tao, Zetian; Liu, Shun; Zhang, Jiujun

2015-12-09

Development of alternative ceramic oxide anode materials is a key step for direct hydrocarbon solid oxide fuel cells (SOFCs). Several lanthanide based layered perovskite-structured oxides demonstrate outstanding oxygen diffusion rate, favorable electronic conductivity, and good oxygen surface exchange kinetics, owing to A-site ordered structure in which lanthanide and alkali-earth ions occupy alternate (001) layers and oxygen vacancies are mainly located in [LnOx] planes. Here we report a nickel-free cation deficient layered perovskite, (PrBa)0.95(Fe0.9Mo0.1)2O5 + δ (PBFM), for SOFC anode, and this anode shows an outstanding performance with high resistance against both carbon build-up and sulfur poisoning in hydrocarbon fuels. At 800 °C, the layered PBFM showed high electrical conductivity of 59.2 S cm(-1) in 5% H2 and peak power densities of 1.72 and 0.54 W cm(-2) using H2 and CH4 as fuel, respectively. The cell exhibits a very stable performance under a constant current load of 1.0 A cm(-2). To our best knowledge, this is the highest performance of ceramic anodes operated in methane. In addition, the anode is structurally stable at various fuel and temperature conditions, suggesting that it is a feasible material candidate for high-performing SOFC anode.

Influence of hydroxyapatite on the corrosion resistance of the Ti-13Nb-13Zr alloy.

PubMed

Duarte, Laís T; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

2009-05-01

Electrochemical analyses on the biocompatible alloy Ti-13Nb-13Zr wt% in an electrolyte simulating physiological medium (PBS solution) are reported. Hydroxyapatite (HA) films were obtained on the alloy by electrodeposition at constant cathodic current. Samples of the alloy covered with an anodic-oxide film or an anodic-oxide/HA film were analyzed by open circuit potential and electrochemical impedance spectroscopy measurements during 180 days in the PBS electrolyte. Analyses of the open-circuit potential (E (oc)) values indicated that the oxide/HA film presents better protection characteristics than the oxide only. This behavior was corroborated by the higher film resistances obtained from impedance data, indicating that, besides improving the alloy osteointegration, the hydroxyapatite film may also increase the corrosion protection of the biomaterial.

Plasma-deposited fluoropolymer film mask for local porous silicon formation

PubMed Central

2012-01-01

The study of an innovative fluoropolymer masking layer for silicon anodization is proposed. Due to its high chemical resistance to hydrofluoric acid even under anodic bias, this thin film deposited by plasma has allowed the formation of deep porous silicon regions patterned on the silicon wafer. Unlike most of other masks, fluoropolymer removal after electrochemical etching is rapid and does not alter the porous layer. Local porous regions were thus fabricated both in p+-type and low-doped n-type silicon substrates. PMID:22734507

Corrosion resistant solar mirror

DOEpatents

Medwick, Paul A.; Abbott, Edward E.

2016-07-19

A reflective article includes a transparent substrate having a first major surface and a second major surface. A base coat is formed over at least a portion of the second major surface. A primary reflective coating having at least one metallic layer is formed over at least a portion of the base coat. A protective coating is formed over at least a portion of the primary reflective coating. The article further includes a solar cell and an anode, with the solar cell connected to the metallic layer and the anode.

Amino acid substitutions in the VanS sensor of the VanA-type vancomycin-resistant Enterococcus strains result in high-level vancomycin resistance and low-level teicoplanin resistance.

PubMed

Hashimoto, Y; Tanimoto, K; Ozawa, Y; Murata, T; Ike, Y

2000-04-15

The vancomycin-resistant enterococci GV1, GV2 and GV3, which were isolated from droppings from broiler farms in Japan have been characterized as VanA-type VRE, which express high-level vancomycin resistance (256 or 512 microg ml(-1), MIC) and low-level teicoplanin resistance (1 or 2 microg ml(-1), MIC). The vancomycin resistances were encoded on plasmids. The vancomycin resistance conjugative plasmid pMG2 was isolated from the GV2 strain. The VanA determinant of pMG2 showed the same genetic organization as that of the VanA genes encoded on the representative transposon Tn1546, which comprises vanRSHAXYZ. The nucleotide sequences of all the genes, except the gene related to the vanS gene on Tn1546, were completely identical to the genes encoded on Tn1546. Three amino acid substitutions in the N-terminal region of the deduced VanS were detected in the nucleotide sequence of vanS encoded on pMG2. There were also three amino acid substitutions in the vanS gene of the GV1 and GV3 strains in the same positions as in the vanS gene of pMG2. Vancomycin induced the increased teicoplanin resistance in these strains.

Old Drugs To Treat Resistant Bugs: Methicillin-Resistant Staphylococcus aureus Isolates with mecC Are Susceptible to a Combination of Penicillin and Clavulanic Acid

PubMed Central

Ba, Xiaoliang; Lovering, Andrew L.; Gleadall, Nicholas; Zadoks, Ruth; Peacock, Sharon J.; Holden, Matthew T. G.; Paterson, Gavin K.; Holmes, Mark A.

2015-01-01

β-Lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA) is mediated by the expression of an alternative penicillin-binding protein 2a (PBP2a) (encoded by mecA) with a low affinity for β-lactam antibiotics. Recently, a novel variant of mecA, known as mecC, was identified in MRSA isolates from both humans and animals. In this study, we demonstrate that mecC-encoded PBP2c does not mediate resistance to penicillin. Rather, broad-spectrum β-lactam resistance in MRSA strains carrying mecC (mecC-MRSA strains) is mediated by a combination of both PBP2c and the distinct β-lactamase encoded by the blaZ gene of strain LGA251 (blaZLGA251), which is part of mecC-encoding staphylococcal cassette chromosome mec (SCCmec) type XI. We further demonstrate that mecC-MRSA strains are susceptible to the combination of penicillin and the β-lactam inhibitor clavulanic acid in vitro and that the same combination is effective in vivo for the treatment of experimental mecC-MRSA infection in wax moth larvae. Thus, we demonstrate how the distinct biological differences between mecA- and mecC-encoded PBP2a and PBP2c have the potential to be exploited as a novel approach for the treatment of mecC-MRSA infections. PMID:26392513

Additional Electrochemical Treatment Effects on the Switching Characteristics of Anodic Porous Alumina Resistive Switching Memory

NASA Astrophysics Data System (ADS)

Otsuka, Shintaro; Takeda, Ryouta; Furuya, Saeko; Shimizu, Tomohiro; Shingubara, Shouso; Iwata, Nobuyuki; Watanabe, Tadataka; Takano, Yoshiki; Takase, Kouichi

2012-06-01

We have investigated the current-voltage characteristics of a resistive switching memory (ReRAM), especially the reproducibility of the switching voltage between an insulating state and a metallic state. The poor reproducibility hinders the practical use of this memory. According to a filament model, the variation of the switching voltage may be understood in terms of the random choice of filaments with different conductivities and lengths at each switching. A limitation of the number of conductive paths is expected to lead to the suppression of the variation of switching voltage. In this study, two strategies for the limitation have been proposed using an anodic porous alumina (APA). The first is the reduction of the number of conductive paths by restriction of the contact area between the top electrodes and the insulator. The second is the lowering of the resistivity of the insulator, which makes it possible to grow filaments with the same characteristics by electrochemical treatments using a pulse-electroplating technique.

XPS and biocompatibility studies of titania film on anodized NiTi shape memory alloy.

PubMed

Chu, C L; Wang, R M; Hu, T; Yin, L H; Pu, Y P; Lin, P H; Dong, Y S; Guo, C; Chung, C Y; Yeung, K W K; Chu, Paul K

2009-01-01

A dense titania film is fabricated in situ on NiTi shape memory alloy (SMA) by anodic oxidation in a Na(2)SO(4) electrolyte. The microstructure of the titania film and its influence on the biocompatibility of NiTi SMA are investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), hemolysis analysis, and platelet adhesion test. The results indicate that the titania film has a Ni-free zone near the surface and can effectively block the release of harmful Ni ions from the NiTi substrate in simulated body fluids. Moreover, the wettability, hemolysis resistance, and thromboresistance of the NiTi sample are improved by this anodic oxidation method.

Method of making a unitized electrode assembly

DOEpatents

Niksa, Marilyn J.; Pohto, Gerald R.; Lakatos, Leslie K.; Wheeler, Douglas J.; Solomon, Frank; Niksa, Andrew J.; Schue, Thomas J.; Genodman, Yury; Turk, Thomas R.; Hagel, Daniel P.

1988-01-01

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom.

Method of making a unitized electrode assembly

DOEpatents

Niksa, M.J.; Pohto, G.R.; Lakatos, L.K.; Wheeler, D.J.; Solomon, F.; Niksa, A.J.; Schue, T.J.; Genodman, Y.; Turk, T.R.; Hagel, D.P.

1988-12-06

A battery assembly of the consumable metal anode type has now been constructed for ready assembly as well as disassembly. In a non-conductive and at least substantially inert cell body, space is provided for receiving an open-structured, non-consumable anode cage. The cage has an open top for facilitating insertion of an anode. A modular cathode is used, comprising a peripheral current conductor frame clamped about a grid reinforced air cathode in sheet form. The air cathode may be double gridded. The cathode frame can be sealed, during assembly, with electrolyte-resistant-sealant as well as with adhesive. The resulting cathode module can be assembled outside the cell body and readily inserted therein, or can later be easily removed therefrom. 6 figs.

Utilization of corn cob biochar in a direct carbon fuel cell

NASA Astrophysics Data System (ADS)

Yu, Jinshuai; Zhao, Yicheng; Li, Yongdan

2014-12-01

Biochar obtained from the pyrolysis of corn cob is used as the fuel of a direct carbon fuel cell (DCFC) employing a composite electrolyte composed of a samarium doped ceria (SDC) and a eutectic carbonate phase. An anode layer made of NiO and SDC is utilized to suppress the cathode corrosion by the molten carbonate and improves the whole cell stability. The anode off-gas of the fuel cell is analyzed with a gas chromatograph. The effect of working temperature on the cell resistance and power output is examined. The maximum power output achieves 185 mW cm-2 at a current density of 340 mA cm-2 and 750 °C. An anode reaction scheme including the Boudouard reaction is proposed.

Schottky barrier at graphene/metal oxide interfaces: insight from first-principles calculations

NASA Astrophysics Data System (ADS)

Cheng, Kai; Han, Nannan; Su, Yan; Zhang, Junfeng; Zhao, Jijun

2017-02-01

Anode materials play an important role in determining the performance of lithium ion batteries. In experiment, graphene (GR)/metal oxide (MO) composites possess excellent electrochemical properties and are promising anode materials. Here we perform density functional theory calculations to explore the interfacial interaction between GR and MO. Our result reveals generally weak physical interactions between GR and several MOs (including Cu2O, NiO). The Schottky barrier height (SBH) in these metal/semiconductor heterostructures are computed using the macroscopically averaged electrostatic potential method, and the role of interfacial dipole is discussed. The calculated SBHs below 1 eV suggest low contact resistance; thus these GR/MO composites are favorable anode materials for better lithium ion batteries.

Schottky barrier at graphene/metal oxide interfaces: insight from first-principles calculations.

PubMed

Cheng, Kai; Han, Nannan; Su, Yan; Zhang, Junfeng; Zhao, Jijun

2017-02-06

Anode materials play an important role in determining the performance of lithium ion batteries. In experiment, graphene (GR)/metal oxide (MO) composites possess excellent electrochemical properties and are promising anode materials. Here we perform density functional theory calculations to explore the interfacial interaction between GR and MO. Our result reveals generally weak physical interactions between GR and several MOs (including Cu2O, NiO). The Schottky barrier height (SBH) in these metal/semiconductor heterostructures are computed using the macroscopically averaged electrostatic potential method, and the role of interfacial dipole is discussed. The calculated SBHs below 1 eV suggest low contact resistance; thus these GR/MO composites are favorable anode materials for better lithium ion batteries.

An Insoluble Titanium-Lead Anode for Sulfate Electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferdman, Alla

2005-05-11

The project is devoted to the development of novel insoluble anodes for copper electrowinning and electrolytic manganese dioxide (EMD) production. The anodes are made of titanium-lead composite material produced by techniques of powder metallurgy, compaction of titanium powder, sintering and subsequent lead infiltration. The titanium-lead anode combines beneficial electrochemical behavior of a lead anode with high mechanical properties and corrosion resistance of a titanium anode. In the titanium-lead anode, the titanium stabilizes the lead, preventing it from spalling, and the lead sheathes the titanium, protecting it from passivation. Interconnections between manufacturing process, structure, composition and properties of the titanium-lead compositemore » material were investigated. The material containing 20-30 vol.% of lead had optimal combination of mechanical and electrochemical properties. Optimal process parameters to manufacture the anodes were identified. Prototypes having optimized composition and structure were produced for testing in operating conditions of copper electrowinning and EMD production. Bench-scale, mini-pilot scale and pilot scale tests were performed. The test anodes were of both a plate design and a flow-through cylindrical design. The cylindrical anodes were composed of cylinders containing titanium inner rods and fitting over titanium-lead bushings. The cylindrical design allows the electrolyte to flow through the anode, which enhances diffusion of the electrolyte reactants. The cylindrical anodes demonstrate higher mass transport capabilities and increased electrical efficiency compared to the plate anodes. Copper electrowinning represents the primary target market for the titanium-lead anode. A full-size cylindrical anode performance in copper electrowinning conditions was monitored over a year. The test anode to cathode voltage was stable in the 1.8 to 2.0 volt range. Copper cathode morphology was very smooth and uniform. There was no measurable anode weight loss during this time period. Quantitative chemical analysis of the anode surface showed that the lead content after testing remained at its initial level. No lead dissolution or transfer from the anode to the product occurred.A key benefit of the titanium-lead anode design is that cobalt additions to copper electrolyte should be eliminated. Cobalt is added to the electrolyte to help stabilize the lead oxide surface of conventional lead anodes. The presence of the titanium intimately mixed with the lead should eliminate the need for cobalt stabilization of the lead surface. The anode should last twice as long as the conventional lead anode. Energy savings should be achieved due to minimizing and stabilizing the anode-cathode distance in the electrowinning cells. The anode is easily substitutable into existing tankhouses without a rectifier change.The copper electrowinning test data indicate that the titanium-lead anode is a good candidate for further testing as a possible replacement for a conventional lead anode. A key consideration is the cost. Titanium costs have increased. One of the ways to get the anode cost down is manufacturing the anodes with fewer cylinders. Additional prototypes having different number of cylinders were constructed for a long-term commercial testing in a circuit without cobalt. The objective of the testing is to evaluate the need for cobalt, investigate the effect of decreasing the number of cylinders on the anode performance, and to optimize further the anode design in order to meet the operating requirements, minimize the voltage, maximize the life of the anode, and to balance this against a reasonable cost for the anode. It is anticipated that after testing of the additional prototypes, a whole cell commercial test will be conducted to complete evaluation of the titanium-lead anode costs/benefits.« less

Older adults get episodic memory boosting from noninvasive stimulation of prefrontal cortex during learning

PubMed Central

Brambilla, Michela; Cobelli, Chiara; Cohen, Leonardo G.; Cotelli, Maria

2016-01-01

Episodic memory displays the largest degree of age-related decline, a process that is accelerated in pathological conditions such as amnestic mild cognitive impairment and Alzheimer's disease. Previous studies have shown that the left lateral prefrontal cortex (PFC) contributes to the encoding of episodic memories along the life span. The aim of this randomized, double-blind, placebo-controlled study was to test the hypothesis that anodal trascranial direct current stimulation (tDCS) over the left lateral PFC during the learning phase would enhance delayed recall of verbal episodic memories in elderly individuals. Older adults learned a list of words while receiving anodal or placebo (sham) tDCS. Memory recall was tested 48 hours and 1 month later. The results showed that anodal tDCS strengthened episodic memories, an effect indicated by enhanced delayed recall (48 hours) compared to placebo stimulation (Cohen's d effect size = 1.01). The observation that PFC-tDCS during learning can boost verbal episodic memory in the elderly opens up the possibility to design-specific neurorehabilitation protocols targeted to conditions that affect episodic memory such as mild cognitive impairment. PMID:26923418

A self-cleaning Li-S battery enabled by a bifunctional redox mediator

NASA Astrophysics Data System (ADS)

Ren, Y. X.; Zhao, T. S.; Liu, M.; Zeng, Y. K.; Jiang, H. R.

2017-09-01

The polysulfide shuttle effect and lithium dendrite growth in lithium-sulfur (Li-S) batteries can repeatedly breach the anodic solid electrolyte interphase (SEI) over cycling. As a result, irreversible short-chain sulfide side products (Li2Sx, x = 1, 2) keep depositing on the Li anode, leading to the active material loss, increasing the Li+ transport resistance, and thereby reducing the cycle life. In this work, indium iodide (InI3) is investigated as a bifunctional electrolyte additive for Li-S batteries to protect the Li anode and decompose the side products spontaneously. On the one hand, Indium (In) is electrodeposited onto the Li anode prior to Li plating during the initial charging process, forming a chemically and mechanically stable SEI to prevent the Li anode from reacting with soluble polysulfide species to form Li2Sx (x = 1, 2) side products. On the other hand, by adequately overcharging the battery, the triiodide/iodide redox mediator is capable of chemically transforming side products deposited on the Li anode and separator into soluble polysulfides, which can be recycled by the cathode. It is shown that the battery with the InI3 additive exhibits a prolonged cycle life, and is capable of retrieving its capacity by a facile overcharging process.

High performance novel gadolinium doped ceria/yttria stabilized zirconia/nickel layered and hybrid thin film anodes for application in solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Garcia-Garcia, F. J.; Beltrán, A. M.; Yubero, F.; González-Elipe, A. R.; Lambert, R. M.

2017-09-01

Magnetron sputtering under oblique angle deposition was used to produce Ni-containing ultra thin film anodes comprising alternating layers of gadolinium doped ceria (GDC) and yttria stabilized zirconia (YSZ) of either 200 nm or 1000 nm thickness. The evolution of film structure from initial deposition, through calcination and final reduction was examined by XRD, SEM, TEM and TOF-SIMS. After subsequent fuel cell usage, the porous columnar architecture of the two-component layered thin film anodes was maintained and their resistance to delamination from the underlying YSZ electrolyte was superior to that of corresponding single component Ni-YSZ and Ni-GDC thin films. Moreover, the fuel cell performance of the 200 nm layered anodes compared favorably with conventional commercially available thick anodes. The observed dependence of fuel cell performance on individual layer thicknesses prompted study of equivalent but more easily fabricated hybrid anodes consisting of simultaneously deposited Ni-GDC and Ni-YSZ, which procedure resulted in exceptionally intimate mixing and interaction of the components. The hybrids exhibited very unusual and favorable Isbnd V characteristics, along with exceptionally high power densities at high currents. Their discovery is the principal contribution of the present work.

Genomic characterization of an extensively-drug resistance Salmonella enterica serotype Indiana strain harboring blaNDM-1 gene isolated from a chicken carcass in China.

PubMed

Wang, Wei; Peng, Zixin; Baloch, Zulqarnain; Hu, Yujie; Xu, Jin; Zhang, Wenhui; Fanning, Séamus; Li, Fengqin

2017-11-01

The objective of this study was to genetically characterize the antimicrobial resistance mechanisms of Salmonella enterica serotype Indiana C629 isolated from a chicken carcass in China in 2014. Antimicrobial susceptibility against a panel of 23 antimicrobial agents was carried out on Salmonella enterica serotype Indiana C629 and assessed according to CLSI standards. Whole-genome sequencing of this isolate was conducted to obtain the complete genome of S. Indiana. Salmonella Indiana C629 expressed an XDR phenotype being resistant to more than 20 antimicrobial agents, including imipenem and meropenem. From the analysis of the resistance mechanisms, two mutations were identified in subunit A of DNA gyrase within the quinolone resistance determining region, in addition to the acquisition of mobile efflux pumps encoding oqxA/B/R. Additionally, four beta-lactamases resistance genes (bla CTX-M-65 , bla TEM-1 , bla OXA-1 , and bla NDM-1 ), five aminoglycosides resistance genes (aac(3)-IV, aac(6')-Ib-cr, aadA2, aadA5, and aph(4)-Ia), two phenicol resistance genes (catB3 and floR), and five trimethoprim/sulfamethoxazole resistance genes (sul1/2/3 and dfrA12/17) were also identified. A total of 191 virulence genes were identified. Among them, 57 belonged to type-three secretion system (T3SS) encoding genes, 55 belonged to fimbrial adherence encoding genes, and 39 belonged to flagella-encoding genes CONCLUSIONS: This study demonstrated that multi-resistance mechanisms consistent with an XDR-phenotype, along with various virulence encoding genes of a S. Indiana strain in China These findings highlight the importance of cooperation among different sectors in order to monitor the spread of resistant pathogens among food animal, foods of animal origin and human beings that might further take measures to protect consumers' health. Copyright © 2017 Elsevier GmbH. All rights reserved.

Leakage current and charging/discharging processes in barrier-type anodic alumina thin films for use in metal-insulator-metal capacitors

NASA Astrophysics Data System (ADS)

Hourdakis, E.; Koutsoureli, M.; Papaioannou, G.; Nassiopoulou, A. G.

2018-06-01

Barrier-type anodic alumina thin films are interesting for use in high capacitance density metal-insulator-metal capacitors due to their excellent dielectric properties at small thickness. This thickness is easily controlled by the anodization voltage. In previous papers we studied the main parameters of interest of the Al/barrier-type anodic alumina/Al structure for use in RF applications and showed the great potential of barrier-type anodic alumina in this respect. In this paper, we investigated in detail charging/discharging processes and leakage current of the above dielectric material. Two different sets of metal-insulator-metal capacitors were studied, namely, with the top Al electrode being either e-gun deposited or sputtered. The dielectric constant of the barrier-type anodic alumina was found at 9.3. Low leakage current was observed in all samples studied. Furthermore, depending on the film thickness, field emission following the Fowler-Nordheim mechanism was observed above an applied electric field. Charging of the anodic dielectric was observed, occurring in the bulk of the anodic layer. The stored charge was of the order of few μC/cm2 and the calculated trap density ˜2 × 1018 states/cm3, the most probable origin of charge traps being, in our opinion, positive electrolyte ions trapped in the dielectric during anodization. We do not think that oxygen vacancies play an important role, since their existence would have a more important impact on the leakage current characteristics, such as resistive memory effects or significant changes during annealing, which were not observed. Finally, discharging characteristic times as high as 5 × 109 s were measured.

3D Microstructure Effects in Ni-YSZ Anodes: Influence of TPB Lengths on the Electrochemical Performance.

PubMed

Pecho, Omar M; Mai, Andreas; Münch, Beat; Hocker, Thomas; Flatt, Robert J; Holzer, Lorenz

2015-10-21

3D microstructure-performance relationships in Ni-YSZ anodes for electrolyte-supported cells are investigated in terms of the correlation between the triple phase boundary (TPB) length and polarization resistance ( R pol ). Three different Ni-YSZ anodes of varying microstructure are subjected to eight reduction-oxidation (redox) cycles at 950 °C. In general the TPB lengths correlate with anode performance . However, the quantitative results also show that there is no simplistic relationship between TPB and R pol . The degradation mechanism strongly depends on the initial microstructure. Finer microstructures exhibit lower degradation rates of TPB and R pol . In fine microstructures, TPB loss is found to be due to Ni coarsening, while in coarse microstructures reduction of active TPB results mainly from loss of YSZ percolation. The latter is attributed to weak bottlenecks associated with lower sintering activity of the coarse YSZ. The coarse anode suffers from complete loss of YSZ connectivity and associated drop of TPB active by 93%. Surprisingly, this severe microstructure degradation did not lead to electrochemical failure. Mechanistic scenarios are discussed for different anode microstructures. These scenarios are based on a model for coupled charge transfer and transport, which allows using TPB and effective properties as input. The mechanistic scenarios describe the microstructure influence on current distributions, which explains the observed complex relationship between TPB lengths and anode performances. The observed loss of YSZ percolation in the coarse anode is not detrimental because the electrochemical activity is concentrated in a narrow active layer. The anode performance can be predicted reliably if the volume-averaged properties (TPB active , effective ionic conductivity) are corrected for the so-called short-range effect, which is particularly important in cases with a narrow active layer.

Effect of Slotted Anode on Gas Bubble Behaviors in Aluminum Reduction Cell

NASA Astrophysics Data System (ADS)

Sun, Meijia; Li, Baokuan; Li, Linmin; Wang, Qiang; Peng, Jianping; Wang, Yaowu; Cheung, Sherman C. P.

2017-12-01

In the aluminum reduction cells, gas bubbles are generated at the bottom of the anode which eventually reduces the effective current contact area and the system efficiency. To encourage the removal of gas bubbles, slotted anode has been proposed and increasingly adopted by some industrial aluminum reduction cells. Nonetheless, the exact gas bubble removal mechanisms are yet to be fully understood. A three-dimensional (3D) transient, multiphase flow mathematical model coupled with magnetohydrodynamics has been developed to investigate the effect of slotted anode on the gas bubble movement. The Eulerian volume of fluid approach is applied to track the electrolyte (bath)-molten aluminum (metal) interface. Meanwhile, the Lagrangian discrete particle model is employed to handle the dynamics of gas bubbles with considerations of the buoyancy force, drag force, virtual mass force, and pressure gradient force. The gas bubble coalescence process is also taken into account based on the O'Rourke's algorithm. The two-way coupling between discrete bubbles and fluids is achieved by the inter-phase momentum exchange. Numerical predictions are validated against the anode current variation in an industrial test. Comparing the results using slotted anode with the traditional one, the time-averaged gas bubble removal rate increases from 36 to 63 pct; confirming that the slotted anode provides more escaping ways and shortens the trajectories for gas bubbles. Furthermore, the slotted anode also reduces gas bubble's residence time and the probability of coalescence. Moreover, the bubble layer thickness in aluminum cell with slotted anode is reduced about 3.5 mm (17.4 pct), so the resistance can be cut down for the sake of energy saving and the metal surface fluctuation amplitude is significantly reduced for the stable operation due to the slighter perturbation with smaller bubbles.

3D Microstructure Effects in Ni-YSZ Anodes: Influence of TPB Lengths on the Electrochemical Performance

PubMed Central

Pecho, Omar M.; Mai, Andreas; Münch, Beat; Hocker, Thomas; Flatt, Robert J.; Holzer, Lorenz

2015-01-01

3D microstructure-performance relationships in Ni-YSZ anodes for electrolyte-supported cells are investigated in terms of the correlation between the triple phase boundary (TPB) length and polarization resistance (Rpol). Three different Ni-YSZ anodes of varying microstructure are subjected to eight reduction-oxidation (redox) cycles at 950 °C. In general the TPB lengths correlate with anode performance. However, the quantitative results also show that there is no simplistic relationship between TPB and Rpol. The degradation mechanism strongly depends on the initial microstructure. Finer microstructures exhibit lower degradation rates of TPB and Rpol. In fine microstructures, TPB loss is found to be due to Ni coarsening, while in coarse microstructures reduction of active TPB results mainly from loss of YSZ percolation. The latter is attributed to weak bottlenecks associated with lower sintering activity of the coarse YSZ. The coarse anode suffers from complete loss of YSZ connectivity and associated drop of TPBactive by 93%. Surprisingly, this severe microstructure degradation did not lead to electrochemical failure. Mechanistic scenarios are discussed for different anode microstructures. These scenarios are based on a model for coupled charge transfer and transport, which allows using TPB and effective properties as input. The mechanistic scenarios describe the microstructure influence on current distributions, which explains the observed complex relationship between TPB lengths and anode performances. The observed loss of YSZ percolation in the coarse anode is not detrimental because the electrochemical activity is concentrated in a narrow active layer. The anode performance can be predicted reliably if the volume-averaged properties (TPBactive, effective ionic conductivity) are corrected for the so-called short-range effect, which is particularly important in cases with a narrow active layer. PMID:28793624

Sputtering Deposition of Sn-Mo-Based Composite Anode for Thin-Film Li-Ion Batteries

NASA Astrophysics Data System (ADS)

Mani Chandran, T.; Balaji, S.

2016-06-01

The role of electrochemically inactive molybdenum in alleviating the anomalous volume expansion of tin anode upon charge-discharge cycling has been investigated. Tin-molybdenum thin-film composite anodes for Li-ion batteries were prepared using a direct-current sputtering method from a tin metal target incorporating molybdenum element. Results of structural and compositional analyses confirmed the presence of tin and molybdenum. The elemental ratio obtained from energy-dispersive x-ray spectroscopy confirmed the feasibility of tailoring the thin-film composition by varying the ratio of metallic elements present in the sputtering target. Scanning electron micrographs of the samples revealed the occurrence of flower-like open morphology with Mo inclusion in a Sn matrix. The gravimetric discharge capacity for pure Sn, Sn-rich, and Mo-rich samples was 733 mAh g-1, 572 mAh g-1, and 439 mAh g-1, respectively, with capacity retention after 50 cycles of 22%, 61%, and 74%, respectively. Mo inclusion reduced the surface resistivity of the Sn anode after the initial charge-discharge cycle. The charge-transfer resistance after the first cycle for pure Sn, Sn-rich, and Mo-rich samples was 17.395 Ω, 5.345 Ω, and 2.865 Ω, respectively. The lithium-ion diffusion coefficient also increased from 8.68 × 10-8 cm2S-1 for the pure Sn sample to 2.98 × 10-5 cm2S-1 for the Mo-rich sample.

Electrochemical and impedance characterization of Microbial Fuel Cells based on 2D and 3D anodic electrodes working with seawater microorganisms under continuous operation.

PubMed

Hidalgo, D; Sacco, A; Hernández, S; Tommasi, T

2015-11-01

A mixed microbial population naturally presents in seawater was used as active anodic biofilm of two Microbial Fuel Cells (MFCs), employing either a 2D commercial carbon felt or 3D carbon-coated Berl saddles as anode electrodes, with the aim to compare their electrochemical behavior under continuous operation. After an initial increase of the maximum power density, the felt-based cell reduced its performance at 5 months (from 7 to 4 μW cm(-2)), while the saddle-based MFC exceeds 9 μW cm(-2) (after 2 months) and maintained such performance for all the tests. Electrochemical impedance spectroscopy was used to identify the MFCs controlling losses and indicates that the mass-transport limitations at the biofilm-electrolyte interface have the main contribution (>95%) to their internal resistance. The activation resistance was one order of magnitude lower with the Berl saddles than with carbon felt, suggesting an enhanced charge-transfer in the high surface-area 3D electrode, due to an increase in bacteria population growth. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transparent indium oxide films doped with high Lewis acid strength Ge dopant for phosphorescent organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Kang, Sin-Bi; Lim, Jong-Wook; Lee, Sunghun; Kim, Jang-Joo; Kim, Han-Ki

2012-08-01

We report on Ge-doped In2O3(IGO) films prepared by co-sputtering GeO2 and In2O3 targets for anode of phosphorescent organic light-emitting diodes (POLEDs). Under optimized annealing conditions, the IGO film exhibited a low sheet resistance of 14.0 Ω/square, a high optical transmittance of 86.9% and a work function of 5.2 eV, comparable to conventional Sn-doped In2O3 (ITO) films. Due to the higher Lewis acid strength of the Ge4+ ion (3.06) than that of Sn3+(1.62), the IGO film showed higher transparency in the near infrared and higher carrier mobility of 39.16 cm2 V-1 s-1 than the ITO films. In addition, the strongly preferred (2 2 2) orientation of the IGO grains, caused by Zone II grain growth during rapid thermal annealing, increased the carrier mobility and improved the surface morphology of the IGO film. POLEDs fabricated on IGO anodes showed identical current density-voltage-luminance curves and efficiencies to POLEDs with ITO electrodes due to the low sheet resistance and high transmittance of the IGO anode.

Mastering the interface for advanced all-solid-state lithium rechargeable batteries

PubMed Central

Li, Yutao; Zhou, Weidong; Chen, Xi; Lü, Xujie; Cui, Zhiming; Xin, Sen; Xue, Leigang; Jia, Quanxi; Goodenough, John B.

2016-01-01

A solid electrolyte with a high Li-ion conductivity and a small interfacial resistance against a Li metal anode is a key component in all-solid-state Li metal batteries, but there is no ceramic oxide electrolyte available for this application except the thin-film Li-P oxynitride electrolyte; ceramic electrolytes are either easily reduced by Li metal or penetrated by Li dendrites in a short time. Here, we introduce a solid electrolyte LiZr2(PO4)3 with rhombohedral structure at room temperature that has a bulk Li-ion conductivity σLi = 2 × 10−4 S⋅cm−1 at 25 °C, a high electrochemical stability up to 5.5 V versus Li+/Li, and a small interfacial resistance for Li+ transfer. It reacts with a metallic lithium anode to form a Li+-conducting passivation layer (solid-electrolyte interphase) containing Li3P and Li8ZrO6 that is wet by the lithium anode and also wets the LiZr2(PO4)3 electrolyte. An all-solid-state Li/LiFePO4 cell with a polymer catholyte shows good cyclability and a long cycle life. PMID:27821751

In vitro study of electrodeposited fluoridated hydroxyapatite coating on G-II titanium with a nanostructured TiO2 interlayer.

PubMed

Lin, Jin-Shyong; Tsai, Tzung-Bau; Say, Wen-Ching; Chiu, Chun; Chen, Shih-Hsun

2017-04-04

Titanium and its alloys have been widely used as orthopedic and dental implants for several decades due to their superior mechanical properties, corrosion resistance and biocompatibility. Recently, many researches revealed that the hydroxyapatite coatings on biomedical materials can further improve their biocompatibility and bioactivity. However, hydroxyapatite coatings are easily decomposed, weakening the bonding between implants and bone tissues and resulting in a high dissolution rate in the biological environment. Prolonging the lifetime of hydroxyapatite in implants is valuable for improving postoperative quality. Hydroxyapatite is the primary inorganic component of bones and teeth. A suitable amount of fluoride ions would be beneficial for the formation of fluoridated hydroxyapatite, which can enhance bone-cell response and the acid resistance of enamel. In this study, G-II titanium substrate was anodized to form a TiO 2 interlayer with a nanotube structure. An electrolyte composed of fluoride, calcium and phosphorus ions was prepared for electroplating fluoridated hydroxyapatite (FHA) coatings onto anodized G-II titanium substrates at a constant voltage. The obtained coatings were examined for their microstructure, mechanical properties; moreover, the changes of apatite structure, surface morphology and corrosion resistance were further investigated after immersion in simulated body fluid (SBF) for a number of weeks. The results show that FHA coatings have a higher surface roughness and hardness than plain hydroxyapatite. After immersion in SBF, the FHA coatings induced the nucleation and growth of apatite on the surface and increased their crystallinity. In a potentiodynamic polarization test, FHA coatings exhibited a better anti-corrosion ability than bare G-II titanium substrate in SBF. Additionally, the anodized TiO 2 nanotube improved the adhesion and corrosion resistance of FHA as well.

Nanofiber-deposited porous platinum enables glucose fuel cell anodes with high current density in body fluids

NASA Astrophysics Data System (ADS)

Frei, Maxi; Erben, Johannes; Martin, Julian; Zengerle, Roland; Kerzenmacher, Sven

2017-09-01

The poisoning of platinum anodes by body-fluid constituents such as amino acids is currently the main hurdle preventing the application of abiotic glucose fuel cells as battery-independent power supply for medical implants. We present a novel anode material that enables continuous operation of glucose oxidation anodes in horse serum for at least 30 days at a current density of (7.2 ± 1.9) μA cm-2. The fabrication process is based on the electro-deposition of highly porous platinum onto a 3-dimensional carbon nanofiber support, leading to approximately 2-fold increased electrode roughness factors (up to 16500 ± 2300). The material's superior performance is not only related to its high specific surface area, but also to an improved catalytic activity and/or poisoning resistance. Presumably, this results from the micro- and nanostructure of the platinum deposits. This represents a major step forward in the development of implantable glucose fuel cells based on long-term stable platinum electrodes.

Improving operational anodising process performance using simulation approach

NASA Astrophysics Data System (ADS)

Liong, Choong-Yeun; Ghazali, Syarah Syahidah

2015-10-01

The use of aluminium is very widespread, especially in transportation, electrical and electronics, architectural, automotive and engineering applications sectors. Therefore, the anodizing process is an important process for aluminium in order to make the aluminium durable, attractive and weather resistant. This research is focused on the anodizing process operations in manufacturing and supplying of aluminium extrusion. The data required for the development of the model is collected from the observations and interviews conducted in the study. To study the current system, the processes involved in the anodizing process are modeled by using Arena 14.5 simulation software. Those processes consist of five main processes, namely the degreasing process, the etching process, the desmut process, the anodizing process, the sealing process and 16 other processes. The results obtained were analyzed to identify the problems or bottlenecks that occurred and to propose improvement methods that can be implemented on the original model. Based on the comparisons that have been done between the improvement methods, the productivity could be increased by reallocating the workers and reducing loading time.

Transparent Ti-In-Sn-O multicomponent anodes for highly efficient phosphorescent organic light emitting diodes

NASA Astrophysics Data System (ADS)

Lim, Jong-Wook; Jun Kang, Seong; Lee, Sunghun; Kim, Jang-Joo; Kim, Han-Ki

2012-07-01

We report on transparent Ti-In-Sn-O (TITO) multicomponent anodes prepared by co-sputtering anatase TiO2-x and ITO targets to produce highly efficient phosphorescent organic light emitting diodes (OLEDs). In spite of the incorporation of low cost TiO2, the crystalline TITO electrode annealed at temperature of 600 °C showed a sheet resistance of 18.06 Ω/sq, an optical transmittance of 87.96% at a wavelength of 550 nm, and a work function of 4.71 eV comparable to conventional ITO electrode. Both the quantum (21.69%) and power efficiencies (90.92 lm/W) of the phosphorescent OLED fabricated on the TITO anode were higher than those of the OLED with the reference ITO anode due to the high transparency of the TITO electrodes. This indicates that the TITO electrode is a promising indium-saving electrode that can replace high-cost ITO electrodes in the manufacture of low-cost, highly efficient phosphorescent OLEDs.

Fabrication of Titania Nanotubes for Gas Sensing Applications

NASA Astrophysics Data System (ADS)

Dzilal, A. A.; Muti, M. N.; John, O. D.

2010-03-01

Detection of hydrogen is needed for industrial process control and medical applications where presence of hydrogen indicates different type of health problems. Titanium dioxide nanotube structure is chosen as an active component in the gas sensor because of its highly sensitive electrical resistance to hydrogen over a wide range of concentrations. The objective of the work is to fabricate good quality titania nanotubes suitable for hydrogen sensing applications. The fabrication method used is anodizing method. The anodizing parameters namely the voltage, time duration, concentration of hydrofluoric acid in water, separation between the electrodes and the ambient temperature are varied accordingly to find the optimum anodizing conditions for production of good quality titania nanotubes. The highly ordered porous titania nanotubes produced by this method are in tabular shape and have good uniformity and alignment over large areas. From the investigation done, certain set of anodizing parameters have been found to produce good quality titania nanotubes with diameter ranges from 47 nm to 94 nm.

An artificial interphase enables reversible magnesium chemistry in carbonate electrolytes.

PubMed

Son, Seoung-Bum; Gao, Tao; Harvey, Steve P; Steirer, K Xerxes; Stokes, Adam; Norman, Andrew; Wang, Chunsheng; Cresce, Arthur; Xu, Kang; Ban, Chunmei

2018-05-01

Magnesium-based batteries possess potential advantages over their lithium counterparts. However, reversible Mg chemistry requires a thermodynamically stable electrolyte at low potential, which is usually achieved with corrosive components and at the expense of stability against oxidation. In lithium-ion batteries the conflict between the cathodic and anodic stabilities of the electrolytes is resolved by forming an anode interphase that shields the electrolyte from being reduced. This strategy cannot be applied to Mg batteries because divalent Mg 2+ cannot penetrate such interphases. Here, we engineer an artificial Mg 2+ -conductive interphase on the Mg anode surface, which successfully decouples the anodic and cathodic requirements for electrolytes and demonstrate highly reversible Mg chemistry in oxidation-resistant electrolytes. The artificial interphase enables the reversible cycling of a Mg/V 2 O 5 full-cell in the water-containing, carbonate-based electrolyte. This approach provides a new avenue not only for Mg but also for other multivalent-cation batteries facing the same problems, taking a step towards their use in energy-storage applications.

An artificial interphase enables reversible magnesium chemistry in carbonate electrolytes

NASA Astrophysics Data System (ADS)

Son, Seoung-Bum; Gao, Tao; Harvey, Steve P.; Steirer, K. Xerxes; Stokes, Adam; Norman, Andrew; Wang, Chunsheng; Cresce, Arthur; Xu, Kang; Ban, Chunmei

2018-05-01

Magnesium-based batteries possess potential advantages over their lithium counterparts. However, reversible Mg chemistry requires a thermodynamically stable electrolyte at low potential, which is usually achieved with corrosive components and at the expense of stability against oxidation. In lithium-ion batteries the conflict between the cathodic and anodic stabilities of the electrolytes is resolved by forming an anode interphase that shields the electrolyte from being reduced. This strategy cannot be applied to Mg batteries because divalent Mg2+ cannot penetrate such interphases. Here, we engineer an artificial Mg2+-conductive interphase on the Mg anode surface, which successfully decouples the anodic and cathodic requirements for electrolytes and demonstrate highly reversible Mg chemistry in oxidation-resistant electrolytes. The artificial interphase enables the reversible cycling of a Mg/V2O5 full-cell in the water-containing, carbonate-based electrolyte. This approach provides a new avenue not only for Mg but also for other multivalent-cation batteries facing the same problems, taking a step towards their use in energy-storage applications.

Old Drugs To Treat Resistant Bugs: Methicillin-Resistant Staphylococcus aureus Isolates with mecC Are Susceptible to a Combination of Penicillin and Clavulanic Acid.

PubMed

Ba, Xiaoliang; Harrison, Ewan M; Lovering, Andrew L; Gleadall, Nicholas; Zadoks, Ruth; Parkhill, Julian; Peacock, Sharon J; Holden, Matthew T G; Paterson, Gavin K; Holmes, Mark A

2015-12-01

β-Lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA) is mediated by the expression of an alternative penicillin-binding protein 2a (PBP2a) (encoded by mecA) with a low affinity for β-lactam antibiotics. Recently, a novel variant of mecA, known as mecC, was identified in MRSA isolates from both humans and animals. In this study, we demonstrate that mecC-encoded PBP2c does not mediate resistance to penicillin. Rather, broad-spectrum β-lactam resistance in MRSA strains carrying mecC (mecC-MRSA strains) is mediated by a combination of both PBP2c and the distinct β-lactamase encoded by the blaZ gene of strain LGA251 (blaZLGA251), which is part of mecC-encoding staphylococcal cassette chromosome mec (SCCmec) type XI. We further demonstrate that mecC-MRSA strains are susceptible to the combination of penicillin and the β-lactam inhibitor clavulanic acid in vitro and that the same combination is effective in vivo for the treatment of experimental mecC-MRSA infection in wax moth larvae. Thus, we demonstrate how the distinct biological differences between mecA- and mecC-encoded PBP2a and PBP2c have the potential to be exploited as a novel approach for the treatment of mecC-MRSA infections. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Catalytic Activity and Impedance Behavior of Screen-Printed Nickel Oxide as Efficient Water Oxidation Catalysts.

PubMed

Singh, Archana; Fekete, Monika; Gengenbach, Thomas; Simonov, Alexandr N; Hocking, Rosalie K; Chang, Shery L Y; Rothmann, Mathias; Powar, Satvasheel; Fu, Dongchuan; Hu, Zheng; Wu, Qiang; Cheng, Yi-Bing; Bach, Udo; Spiccia, Leone

2015-12-21

We report that films screen printed from nickel oxide (NiO) nanoparticles and microballs are efficient electrocatalysts for water oxidation under near-neutral and alkaline conditions. Investigations of the composition and structure of the screen-printed films by X-ray diffraction, X-ray absorption spectroscopy, and scanning electron microscopy confirmed that the material was present as the cubic NiO phase. Comparison of the catalytic activity of the microball films to that of films fabricated by using NiO nanoparticles, under similar experimental conditions, revealed that the microball films outperform nanoparticle films of similar thickness owing to a more porous structure and higher surface area. A thinner, less-resistive NiO nanoparticle film, however, was found to have higher activity per Ni atom. Anodization in borate buffer significantly improved the activity of all three films. X-ray photoelectron spectroscopy showed that during anodization, a mixed nickel oxyhydroxide phase formed on the surface of all films, which could account for the improved activity. Impedance spectroscopy revealed that surface traps contribute significantly to the resistance of the NiO films. On anodization, the trap state resistance of all films was reduced, which led to significant improvements in activity. In 1.00 m NaOH, both the microball and nanoparticle films exhibit high long-term stability and produce a stable current density of approximately 30 mA cm(-2) at 600 mV overpotential. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Carbon fiber enhanced bioelectricity generation in soil microbial fuel cells.

PubMed

Li, Xiaojing; Wang, Xin; Zhao, Qian; Wan, Lili; Li, Yongtao; Zhou, Qixing

2016-11-15

The soil microbial fuel cell (MFC) is a promising biotechnology for the bioelectricity recovery as well as the remediation of organics contaminated soil. However, the electricity production and the remediation efficiency of soil MFC are seriously limited by the tremendous internal resistance of soil. Conductive carbon fiber was mixed with petroleum hydrocarbons contaminated soil and significantly enhanced the performance of soil MFC. The maximum current density, the maximum power density and the accumulated charge output of MFC mixed carbon fiber (MC) were 10, 22 and 16 times as high as those of closed circuit control due to the carbon fiber productively assisted the anode to collect the electron. The internal resistance of MC reduced by 58%, 83% of which owed to the charge transfer resistance, resulting in a high efficiency of electron transfer from soil to anode. The degradation rates of total petroleum hydrocarbons enhanced by 100% and 329% compared to closed and opened circuit controls without the carbon fiber respectively. The effective range of remediation and the bioelectricity recovery was extended from 6 to 20cm with the same area of air-cathode. The mixed carbon fiber apparently enhanced the bioelectricity generation and the remediation efficiency of soil MFC by means of promoting the electron transfer rate from soil to anode. The use of conductively functional materials (e.g. carbon fiber) is very meaningful for the remediation and bioelectricity recovery in the bioelectrochemical remediation. Copyright © 2016 Elsevier B.V. All rights reserved.

Plasma sprayed metal supported YSZ/Ni-LSGM-LSCF ITSOFC with nanostructured anode

NASA Astrophysics Data System (ADS)

Hwang, Changsing; Tsai, Chun-Huang; Lo, Chih-Hung; Sun, Cha-Hong

Intermediate temperature solid oxide fuel cells (ITSOFCs) supported by a porous Ni-substrate and based on Sr and Mg doped lanthanum gallate (LSGM) electrolyte, lanthanum strontium cobalt ferrite (LSCF) cathode and nanostructured yttria stabilized zirconia-nickel (YSZ/Ni) cermet anode have been fabricated successfully by atmospheric plasma spraying (APS). From ac impedance analysis, the sprayed YSZ/Ni cermet anode with a novel nanostructure and advantageous triple phase boundaries after hydrogen reduction has a low resistance. It shows a good electrocatalytic activity for hydrogen oxidation reactions. The sprayed LSGM electrolyte with ∼60 μm in thickness and ∼0.054 S cm -1 conductivity at 800 °C shows a good gas tightness and gives an open circuit voltage (OCV) larger than 1 V. The sprayed LSCF cathode with ∼30 μm in thickness and ∼30% porosity has a minimum resistance after being heated at 1000 °C for 2 h. This cathode keeps right phase structure and good porous network microstructure for conducting electrons and negative oxygen ions. The APS sprayed cell after being heated at 1000 °C for 2 h has a minimum inherent resistance and achieves output power densities of ∼440 mW cm -2 at 800 °C, ∼275 mW cm -2 at 750 °C and ∼170 mW cm -2 at 700 °C. Results from SEM, XRD, ac impedance analysis and I- V- P measurements are presented here.

MEMBRANE POTENTIAL OF THE SQUID GIANT AXON DURING CURRENT FLOW

PubMed Central

Cole, Kenneth S.; Curtis, Howard J.

1941-01-01

The squid giant axon was placed in a shallow narrow trough and current was sent in at two electrodes in opposite sides of the trough and out at a third electrode several centimeters away. The potential difference across the membrane was measured between an inside fine capillary electrode with its tip in the axoplasm between the pair of polarizing electrodes, and an outside capillary electrode with its tip flush with the surface of one polarizing electrode. The initial transient was roughly exponential at the anode make and damped oscillatory at the sub-threshold cathode make with the action potential arising from the first maximum when threshold was reached. The constant change of membrane potential, after the initial transient, was measured as a function of the total polarizing current and from these data the membrane potential is obtained as a function of the membrane current density. The absolute value of the resting membrane resistance approached at low polarizing currents is about 23 ohm cm.2. This low value is considered to be a result of the puncture of the axon. The membrane was found to be an excellent rectifier with a ratio of about one hundred between the high resistance at the anode and the low resistance at the cathode for the current range investigated. On the assumption that the membrane conductance is a measure of its ion permeability, these experiments show an increase of ion permeability under a cathode and a decrease under an anode. PMID:19873234

Gene encoding acetyl-coenzyme A carboxylase

DOEpatents

Roessler, Paul G.; Ohlrogge, John B.

1996-01-01

A DNA encoding an acetyl-coenzyme A carboxylase (ACCase) from a photosynthetic organism and functional derivatives thereof which are resistant to inhibition from certain herbicides. This gene can be placed in organisms to increase their fatty acid content or to render them resistant to certain herbicides.

Stacked microbial desalination cells to enhance water desalination efficiency.

PubMed

Chen, Xi; Xia, Xue; Liang, Peng; Cao, Xiaoxin; Sun, Haotian; Huang, Xia

2011-03-15

Microbial desalination cell (MDC) is a new method to obtain clean water from brackish water using electricity generated from organic matters by exoelectrogenic bacteria. Anions and cations, derived from salt solution filled in the desalination chamber between the anode and cathode, move to the anode and cathode chambers under the force of electrical field, respectively. On the basis of the primitive single-desalination-chambered MDC, stacked microbial desalination cells (SMDCs) were developed in order to promote the desalination rate in the present study. The effects of desalination chamber number and external resistance were investigated. Results showed that a remarkable increase in the total desalination rate (TDR) could be obtained by means of increasing the desalination cell number and reducing the external resistance, which caused the charge transfer efficiency increased since the SMDCs enabled more pairs of ions separated while one electron passed through the external circuit. The maximum TDR of 0.0252 g/h was obtained using a two-desalination-chambered SMDC with an external resistance of 10 Ω, which was 1.4 times that of single-desalination-chambered MDC. SMDCs proved to be an effective approach to increase the total water desalination rate if provided a proper desalination chamber number and external resistance.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

A new structural approach for uniform sub-micrometer anode metallization of planar THz Schottky components

NASA Astrophysics Data System (ADS)

Cojocari, O.; Mottet, B.; Rodriguez-Girones, M.; Biber, S.; Marchand, L.; Schmidt, L.-P.; Hartnagel, H. L.

2004-03-01

This paper presents the evaluation of a Schottky contact technology based on electrochemical metal deposition. The results of a long-term systematic investigation and optimization of the anode formation process to improve the yield and performance of Schottky-based GaAs mixer diodes are detailed. Surface preparation prior to the Schottky-metal deposition and anode metallization as previously optimized for whisker-contacted diodes are successfully transferred to the fabrication of planar structures. This uses an auxiliary honeycomb array of anode-like structures called 'dummy anodes', which are processed simultaneously with the real anodes and then removed in the later technological processes. Consequently, the scattering of planar diodes electrical parameters is significantly reduced and the yield of the fabrication process increases from about 5% up to about 50%. Very good dc characteristics such as series resistance (Rs) below 8 OHgr, ideality factor (eegr) below 1.2 and saturation current (Isat) of the order of 10-17A are achieved for the anode diameter as small as 1 µm. An excellent IF-noise figure of 250 K at 4.8 GHz up to 280 K at 2.1 GHz with current bias up to 3 mA is obtained for non-cooled THz mixer planar diodes. The use of this technological approach has enabled the extraction of statistically significant data which have been used to characterize the criticality of each step of the fabrication process on the device performance.

Enhancing Sulfur Tolerance of Ni-Based Cermet Anodes of Solid Oxide Fuel Cells by Ytterbium-Doped Barium Cerate Infiltration.

PubMed

Li, Meng; Hua, Bin; Luo, Jing-Li; Jiang, San Ping; Pu, Jian; Chi, Bo; Li, Jian

2016-04-27

Conventional anode materials for solid oxide fuel cells (SOFCs) are Ni-based cermets, which are highly susceptible to deactivation by contaminants in hydrocarbon fuels. Hydrogen sulfide is one of the commonly existed contaminants in readily available natural gas and gasification product gases of pyrolysis of biomasses. Development of sulfur tolerant anode materials is thus one of the critical challenges for commercial viability and practical application of SOFC technologies. Here we report a viable approach to enhance substantially the sulfur poisoning resistance of a Ni-gadolinia-doped ceria (Ni-GDC) anode through impregnation of proton conducting perovskite BaCe0.9Yb0.1O3-δ (BCYb). The impregnation of BCYb nanoparticles improves the electrochemical performance of the Ni-GDC anode in both H2 and H2S containing fuels. Moreover, more importantly, the enhanced stability is observed in 500 ppm of H2S/H2. The SEM and XPS analysis indicate that the infiltrated BCYb fine particles inhibit the adsorption of sulfur and facilitate sulfur removal from active sites, thus preventing the detrimental interaction between sulfur and Ni-GDC and the formation of cerium sulfide. The preliminary results of the cell with the BCYb+Ni-GDC anode in methane fuel containing 5000 ppm of H2S show the promising potential of the BCYb infiltration approach in the development of highly active and stable Ni-GDC-based anodes fed with hydrocarbon fuels containing a high concentration of sulfur compounds.

Bioconversion of cellulose into electrical energy in microbial fuel cells

NASA Astrophysics Data System (ADS)

Rismani-Yazdi, Hamid

In microbial fuel cells (MFCs), bacteria generate electricity by mediating the oxidation of organic compounds and transferring the resulting electrons to an anode electrode. The first objective of this study was to test the possibility of generating electricity with rumen microorganisms as biocatalysts and cellulose as the electron donor in two-compartment MFCs. Maximum power density reached 55 mW/m2 (1.5 mA, 313 mV) with cellulose as the electron donor. Cellulose hydrolysis and electrode reduction were shown to support the production of current. The electrical current was sustained for over two months with periodic cellulose addition. Clarified rumen fluid and a soluble carbohydrate mixture, serving as the electron donors, could also sustain power output. The second objective was to analyze the composition of the bacterial communities enriched in the cellulose-fed MFCs. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes revealed that the microbial communities differed when different substrates were used in the MFCs. The anode-attached and the suspended consortia were shown to be different within the same MFC. Cloning and analysis of 16S rRNA gene sequences indicated that the most predominant bacteria in the anode-attached consortia were related to Clostridium spp., while Comamonas spp. was abundant in the suspended consortia. The external resistance affects the characteristic outputs of MFCs by controlling the flow of electrons from the anode to the cathode. The third objective of this study was to determine the effect of various external resistances on power output and coulombic efficiency of cellulose-fed MFCs. Four external resistances (20, 249, 480, and 1000 ohms) were tested with a systematic approach of operating parallel MFCs independently at constant circuit loads for three months. A maximum power density of 66 mWm-2 was achieved by MFCs with 20 ohms circuit load, while MFCs with 249, 480 and1000 ohms external resistances produced 57.5, 53 and 47 mWm-2, respectively. The anode potential varied under the different circuit loads employed. Higher coulombic efficiencies were achieved in MFCs with lower external resistance. The effect of different external resistances on the bacterial diversity and metabolism in cellulose-fed MFCs was investigated as the fourth objective. DGGE analysis of partial 16S rRNA genes showed clear differences between the planktonic and the anode-attached populations at various external resistances. Cellulose degradation was complete (< 0.1% residual), and there were no discernible differences among the MFCs. HPLC analysis of short chain fatty acids (SCFA) revealed that anaerobic degradation of cellulose was accompanied by production of acetic, propionic, butyric, isobutyric, valeric, isovaleric, and lactic acids, with acetic acid being predominant. The profile of metabolites was different among the MFCs. The concentrations of SCFA were higher in MFCs with larger external resistance. High levels of SCFA indicated that fermentative metabolism dominated over anaerobic respiration, resulting in relatively low coulombic efficiencies. The accumulation of SCFA at higher circuit resistances corresponded to lower power outputs. Methanogenesis shifts the flow of electrons available from the substrate away from electricity generation in MFCs. The fifth objective of this research was to assess the influence of methane formation on the performance of cellulose-fed MFCs under long-term operation. A maximum volumetric power density of 3.5 W m-3 was achieved in R20O MFCs, which was three times greater than that obtained with R100O MFCs (1.03 W m-3). The diversity of methanogens in cellulose-fed MFCs was also characterized. It was shown that the suppression of methanogenesis was accompanied by a decrease in the diversity of methanogens and changes in the concentration of SCFA, as revealed by DGGE analysis of PCR-amplified 16S rRNA genes and HPLC analysis, respectively. Analysis of partial 16S rRNA gene Sequences indicated that the most predominant methanogens were related to the family Methanobacteriaceae . The results demonstrate that electricity can be generated from cellulose by exploiting rumen microorganisms as biocatalysts. Results suggest that oxidation of metabolites with the anode as an electron sink was a rate limiting step in the conversion of cellulose to electricity in MFCs. This study also demonstrates that the size of external resistance significantly affects the bacterial diversity and characteristic output of MFCs. Thus the external resistance may be a useful tool to control microbial communities and consequently enhance performance of MFCs. Furthermore, this study shows that methanogenesis competes with electricity generation at the early stages of MFC operation but operating conditions suppress methanogenic activity over time. An improved understanding of the microbial communities, interspecies interactions and processes involved in electricity generation is essential to effectively design and control cellulose-fed MFCs for enhanced performance. In addition, technical and biological optimization is needed to maximize power output of these systems.

Low resistance electrode construction

DOEpatents

Redey, Laszlo; Karell, Eric J.

2002-01-01

An electrochemical cell having a cathode and an anode in contact with an electrolyte. Both electrodes or one of them has an electrically conducting non-metal receptacle defining a chamber with a first metal having a melting point in the range of from about room temperature to about 800.degree. C. inside said receptacle chamber. A second metal with a melting point greater than about 800.degree. C. is in contact with the first metal inside the receptacle chamber and extends outside of the receptacle chamber to form a terminal for the anode. The electrolyte may include the oxides, halides or mixtures thereof of one or more of Li, V, U, Al and the lanthanides. Metal may be produced at the cathode during operation of the cell and oxygen or chlorine at the anode.

Scaled-up dual anode/cathode microbial fuel cell stack for actual ethanolamine wastewater treatment.

PubMed

An, Byung-Min; Heo, Yoon; Maitlo, Hubdar-Ali; Park, Joo-Yang

2016-06-01

The aim of this work was to develop the scale-up microbial fuel cell technology for actual ethanolamine wastewater treatment, dual anode/cathode MFC stacks connected in series to achieve any desired current, treatment capacity, and volume capacity. However, after feeding actual wastewater into the MFC, maximum power density decreased while the corresponding internal resistance increased. With continuous electricity production, a stack of eight MFCs in series achieved 96.05% of COD removal and 97.30% of ammonia removal at a flow rate of 15.98L/d (HRT 12h). The scaled-up dual anode/cathode MFC stack system in this research was demonstrated to treat actual ETA wastewater with the added benefit of harvesting electricity energy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nickel-based anode with water storage capability to mitigate carbon deposition for direct ethanol solid oxide fuel cells.

PubMed

Wang, Wei; Su, Chao; Ran, Ran; Zhao, Bote; Shao, Zongping; Tade, Moses O; Liu, Shaomin

2014-06-01

The potential to use ethanol as a fuel places solid oxide fuel cells (SOFCs) as a sustainable technology for clean energy delivery because of the renewable features of ethanol versus hydrogen. In this work, we developed a new class of anode catalyst exemplified by Ni+BaZr0.4Ce0.4Y0.2O3 (Ni+BZCY) with a water storage capability to overcome the persistent problem of carbon deposition. Ni+BZCY performed very well in catalytic efficiency, water storage capability and coking resistance tests. A stable and high power output was well maintained with a peak power density of 750 mW cm(-2) at 750 °C. The SOFC with the new robust anode performed for seven days without any sign of performance decay, whereas SOFCs with conventional anodes failed in less than 2 h because of significant carbon deposition. Our findings indicate the potential applications of these water storage cermets as catalysts in hydrocarbon reforming and as anodes for SOFCs that operate directly on hydrocarbons. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The performance of 3-D graphite doped anodes in microbial electrolysis cells

NASA Astrophysics Data System (ADS)

Yasri, Nael G.; Nakhla, George

2017-02-01

This study investigated the use of granular activated carbon (GAC) as high surface area 3-dimensional (3-D) anode in MECs systems. The interfacial anodes' charge transfer resistance of the doped GAC did not impact the overall performance of MECs. Based on our finding, the 3-D anode packed with GAC-doped with nonconductive calcium sulfide (CaS) outperformed the more conductive iron (II) sulfide (FeS), magnetite (Fe3O4), or GAC without doping. The results showed higher current densities for 3-D CaS (40.1 A/m3), as compared with 3-D FeS (34.4 A/m3), 3-D Fe3O4 (29.8 A/m3), and 3-D GAC (23.1 A/m3). The higher current density in the 3-D CaS translated to higher coulombic efficiency (96.7%), hydrogen yield (3.6 mol H2/mol acetate), and attached biomass per anode mass (54.01 mg COD biomass/g GAC). Although the 3-D MEC achieved similar hydrogen yield, hydrogen recovery efficiency, and COD removal rate to a conventional sandwich type MEC, the current density, coulombic efficiency, and overall energy efficiency were higher.

All ceramic structure for molten carbonate fuel cell

DOEpatents

Smith, James L.; Kucera, Eugenia H.

1992-01-01

An all-ceramic molten carbonate fuel cell having a composition formed of a multivalent metal oxide or oxygenate such as an alkali metal, transition metal oxygenate. The structure includes an anode and cathode separated by an electronically conductive interconnect. The electrodes and interconnect are compositions ceramic materials. Various combinations of ceramic compositions for the anode, cathode and interconnect are disclosed. The fuel cell exhibits stability in the fuel gas and oxidizing environments. It presents reduced sealing and expansion problems in fabrication and has improved long-term corrosion resistance.

Gene encoding acetyl-coenzyme A carboxylase

DOEpatents

Roessler, P.G.; Ohlrogge, J.B.

1996-09-24

A DNA encoding an acetyl-coenzyme A carboxylase (ACCase) from a photosynthetic organism and functional derivatives are disclosed which are resistant to inhibition from certain herbicides. This gene can be placed in organisms to increase their fatty acid content or to render them resistant to certain herbicides. 5 figs.

Isolation of a gene encoding a novel spectinomycin phosphotransferase from Legionella pneumophila.

PubMed

Suter, T M; Viswanathan, V K; Cianciotto, N P

1997-06-01

A gene capable of conferring spectinomycin resistance was isolated from Legionella pneumophila, the agent of Legionnaires' disease. The gene (aph) encoded a 36-kDa protein which has similarity to aminoglycoside phosphotransferases. Biochemical analysis confirmed that aph encodes a phosphotransferase which modifies spectinomycin but not hygromycin, kanamycin, or streptomycin. The strain that was the source of aph demonstrated resistance to spectinomycin, and Southern hybridizations determined that aph also exists in other legionellae.

Isolation of a gene encoding a novel spectinomycin phosphotransferase from Legionella pneumophila.

PubMed Central

Suter, T M; Viswanathan, V K; Cianciotto, N P

1997-01-01

A gene capable of conferring spectinomycin resistance was isolated from Legionella pneumophila, the agent of Legionnaires' disease. The gene (aph) encoded a 36-kDa protein which has similarity to aminoglycoside phosphotransferases. Biochemical analysis confirmed that aph encodes a phosphotransferase which modifies spectinomycin but not hygromycin, kanamycin, or streptomycin. The strain that was the source of aph demonstrated resistance to spectinomycin, and Southern hybridizations determined that aph also exists in other legionellae. PMID:9174205

Valve seat pores sealed with thermosetting monomer

NASA Technical Reports Server (NTRS)

Olmore, A. B.

1966-01-01

Hard anodic coating provides a smooth wear resistant value seating surface on a cast aluminum alloy valve body. Vacuum impregnation with a thermosetting monomer, diallyl phthalate, seals the pores on the coating to prevent galvanic corrosion.

Prevalence and Characterization of Carbapenem-Resistant Enterobacteriaceae Isolated from Mulago National Referral Hospital, Uganda

PubMed Central

Okoche, Deogratius; Asiimwe, Benon B.; Katabazi, Fred Ashaba; Kato, Laban; Najjuka, Christine F.

2015-01-01

Introduction Carbapenemases have increasingly been reported in enterobacteriaceae worldwide. Most carbapenemases are plasmid encoded hence resistance can easily spread. Carbapenem-resistant enterobacteriaceae are reported to cause mortality in up to 50% of patients who acquire bloodstream infections. We set out to determine the burden of carbapenem resistance as well as establish genes encoding for carbapenemases in enterobacteriaceae clinical isolates obtained from Mulago National Referral Hospital, Uganda. Methods This was a cross-sectional study with a total of 196 clinical isolates previously collected from pus swabs, urine, blood, sputum, tracheal aspirates, cervical swabs, endomentrial aspirates, rectal swabs, Vaginal swabs, ear swabs, products of conception, wound biopsy and amniotic fluid. All isolates were subjected to phenotypic carbapenemase screening using Boronic acid-based inhibition, Modified Hodge and EDTA double combined disk test. In addition, all the isolates were subjected to PCR assay to confirm presence of carbapenemase encoding genes. Results The study found carbapenemase prevalence of 22.4% (44/196) in the isolates using phenotypic tests, with the genotypic prevalence slightly higher at 28.6% (56/196). Over all, the most prevalent gene was blaVIM (21,10.7%), followed by blaOXA-48 (19, 9.7%), blaIMP (12, 6.1%), blaKPC (10, 5.1%) and blaNDM-1 (5, 2.6%). Among 56 isolates positive for 67 carbapenemase encoding genes, Klebsiella pneumonia was the species with the highest number (52.2%). Most 32/67(47.7%) of these resistance genes were in bacteria isolated from pus swabs. Conclusion There is a high prevalence of carbapenemases and carbapenem-resistance encoding genes among third generation cephalosporins resistant Enterobacteriaceae in Uganda, indicating a danger of limited treatment options in this setting in the near future. PMID:26284519

Glyphosate-resistant and conventional canola (Brassica napus L.) responses to glyphosate and Aminomethylphosphonic Acid (AMPA) treatment

USDA-ARS?s Scientific Manuscript database

Glyphosate-resistant (GR) canola expresses two transgenes: 1) the microbial glyphosate oxidase gene (gox) encoding the glyphosate oxidase enzyme (GOX) that metabolizes glyphosate to aminomethylphosphonic acid (AMPA) and 2) cp4 that encodes a GR form of the glyphosate target enzyme 5-enolpyruvylshiki...

Structure, Function, Interaction, Co-evolution of Rice Blast Resistance Genes

USDA-ARS?s Scientific Manuscript database

Rice blast disease caused by the fungal pathogen Magnaporthe oryzae is one of the most destructive rice diseases worldwide. Resistance (R) genes to blast encode proteins that detect pathogen signaling molecules encoded by M. oryzae avirulence (AVR) genes. R genes can be a single or a member of clu...

Porous Ni-Fe alloys as anode support for intermediate temperature solid oxide fuel cells: I. Fabrication, redox and thermal behaviors

NASA Astrophysics Data System (ADS)

Wang, Xin; Li, Kai; Jia, Lichao; Zhang, Qian; Jiang, San Ping; Chi, Bo; Pu, Jian; Jian, Li; Yan, Dong

2015-03-01

Porous Ni-Fe anode supports for intermediate solid oxide fuel cells are prepared by reducing the sintered NiO-(0-50 wt. %) Fe2O3 composites in H2, their microstructure, redox and thermal expansion/cycling characteristics are systematically investigated. The sintered NiO-Fe2O3 composites are consisted of NiO and NiFe2O4, and are fully reducible to porous metallic Ni-Fe alloys in H2 at temperatures between 600 and 750 °C. The porous structure contains pores in bimodal distribution with larger pores between the sintered particles and smaller ones inside the particles. The oxidation resistance of the Ni-Fe alloy anode supports at 600 and 750 °C is increased by the addition of Fe, their oxidation kinetics obeys a multistage parabolic law in the form of (Percentageweightgain /Specificsurfacearea) 2 =kp · t , where kp is the rate constant and t the oxidation time. The dimension of the Ni-Fe anode supports is slightly changed without disintegrating their structure, and Fe addition is beneficial to the redox stability. The TEC of the Ni-Fe alloy anode supports decreases with the increase of Fe content. The anode supports containing Fe is less stable in dimension during thermal cycles due to the continuous sintering, but the dimension change after thermal cycles is within 1%.

The surface evolution of La0.4Sr0.6TiO3+δ anode in solid oxide fuel cells: Understanding the sulfur-promotion effect

NASA Astrophysics Data System (ADS)

Yan, Ning; Zanna, Sandrine; Klein, Lorena H.; Roushanafshar, Milad; Amirkhiz, Babak S.; Zeng, Yimin; Rothenberg, Gadi; Marcus, Philippe; Luo, Jing-Li

2017-03-01

The ideal solid oxide fuel cells (SOFCs) can be powered by readily available hydrocarbon fuels containing impurities. While this is commonly recognized as a key advantage of SOFC, it also, together with the elevated operating temperature, becomes the main barrier impeding the in-situ or operando investigations of the anode surface chemistry. Here, using a well-designed quenching experiment, we managed to characterize the near-surface structure of La0.4Sr0.6TiO3+δ (LST) anode in SOFCs fuelled by H2S-containing methane. This new method enabled us to clearly observe the surface amorphization and sulfidation of LST under simulated SOFC operating conditions. The ∼1 nm-thick two dimensional sulfur-adsorbed layer was on top of the disordered LST, containing -S, -SH and elemental sulfur species. In SOFC test, such "poisoned" anode showed increased performances: a ten-fold enhanced power density enhancement (up to 30 mW cm-2) and an improved open circuit voltage (from 0.69 V to 1.17 V). Moreover, its anodic polarization resistance in methane decreased to 21.53 Ω cm2, a difference of 95% compared with the sulfur-free anode. Control experiments confirmed that once the adsorbed sulfur species were removed electrochemically, methane conversion slowed down simultaneously till full stop.

Design, fabrication and testing of an air-breathing micro direct methanol fuel cell with compound anode flow field

NASA Astrophysics Data System (ADS)

Wang, Luwen; Zhang, Yufeng; Zhao, Youran; An, Zijiang; Zhou, Zhiping; Liu, Xiaowei

2011-10-01

An air-breathing micro direct methanol fuel cell (μDMFC) with a compound anode flow field structure (composed of the parallel flow field and the perforated flow field) is designed, fabricated and tested. To better analyze the effect of the compound anode flow field on the mass transfer of methanol, the compound flow field with different open ratios (ratio of exposure area to total area) and thicknesses of current collectors is modeled and simulated. Micro process technologies are employed to fabricate the end plates and current collectors. The performances of the μDMFC with a compound anode flow field are measured under various operating parameters. Both the modeled and the experimental results show that, comparing the conventional parallel flow field, the compound one can enhance the mass transfer resistance of methanol from the flow field to the anode diffusion layer. The results also indicate that the μDMFC with an anode open ratio of 40% and a thickness of 300 µm has the optimal performance under the 7 M methanol which is three to four times higher than conventional flow fields. Finally, a 2 h stability test of the μDMFC is performed with a methanol concentration of 7 M and a flow velocity of 0.1 ml min-1. The results indicate that the μDMFC can work steadily with high methanol concentration.

A member of a new plant gene family encoding a meprin and TRAF homology (MATH) domain-containing protein is involved in restriction of long distance movement of plant viruses

PubMed Central

Cosson, Patrick; Sofer, Luc; Schurdi-Levraud, Valérie

2010-01-01

Restriction of long distance movement of several potyviruses in Arabidopsis thaliana is controlled by at least three dominant restricted TEV movement (RTM) genes, named RTM1, RTM2 and RTM3 and acts as a non-conventional resistance. RTM1 encodes a protein belonging to the jacalin family and RTM2 encodes a protein which has similarities to small heat shock proteins. The recent cloning of RTM3 which encodes a protein belonging to an unknown protein family of 29 members that has a meprin and TRAF homology (MATH) domain in its N-terminal region and a coiled-coil (CC) domain at its C-terminal end is an important breakthrough for a better understanding of this resistance process. Not only the third gene involved in this resistance has been identified and has allowed revealing a new gene family in plant but the discovery that the RTM3 protein interacts directly with RTM1 strongly suggests that the RTM proteins form a multimeric complex. However, these data also highlight striking similarities of the RTM resistance with the well known R-gene mediated resistance. PMID:20930558

Mixed Conducting Electrodes for Better AMTEC Cells

NASA Technical Reports Server (NTRS)

Ryan, Margaret; Williams, Roger; Homer, Margie; Lara. Liana

2003-01-01

Electrode materials that exhibit mixed conductivity (that is, both electronic and ionic conductivity) have been investigated in a continuing effort to improve the performance of the alkali metal thermal-to-electric converter (AMTEC). These electrode materials are intended primarily for use on the cathode side of the sodium-ion-conducting solid electrolyte of a sodium-based AMTEC cell. They may also prove useful in sodium-sulfur batteries, which are under study for use in electric vehicles. An understanding of the roles played by the two types of conduction in the cathode of a sodium-based AMTEC cell is prerequisite to understanding the advantages afforded by these materials. In a sodium-based AMTEC cell, the anode face of an anode/solid-electrolyte/cathode sandwich is exposed to Na vapor at a suitable pressure. Upon making contact with the solid electrolyte on the anode side, Na atoms oxidize to form Na+ ions and electrons. Na+ ions then travel through the electrolyte to the cathode. Na+ ions leave the electrolyte at the cathode/electrolyte interface and are reduced by electrons that have been conducted through an external electrical load from the anode to the cathode. Once the Na+ ions have been reduced to Na atoms, they travel through the cathode to vaporize into a volume where the Na vapor pressure is much lower than it is on the anode side. Thus, the cathode design is subject to competing requirements to be thin enough to allow transport of sodium to the low-pressure side, yet thick enough to afford adequate electronic conductivity. The concept underlying the development of the present mixed conducting electrode materials is the following: The constraint on the thickness of the cathode can be eased by incorporating Na+ -ionconducting material to facilitate transport of sodium through the cathode in ionic form. At the same time, by virtue of the electronically conducting material mixed with the ionically conducting material, reduction of Na+ ions to Na atoms can take place throughout the thickness of the cathode. The net effect is to reduce the diffusion and flow resistance to sodium through the electrode while reducing the electronic resistance by providing shorter conduction paths for electrons. Reduced resistance to both sodium transport and electronic conductivity results in an increase in electric power output.

Experimental diagnostics and modeling of inductive phenomena at low frequencies in impedance spectra of proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Pivac, Ivan; Šimić, Boris; Barbir, Frano

2017-10-01

Representation of fuel cell processes by equivalent circuit models, involving resistance and capacitance elements representing activation losses on both anode and cathode in series with resistance representing ohmic losses, cannot capture and explain the inductive loop that may show up at low frequencies in Nyquist diagram representation of the electrochemical impedance spectra. In an attempt to explain the cause of the low-frequency inductive loop and correlate it with the processes within the fuel cell electrodes, a novel equivalent circuit model of a Proton Exchange Membrane (PEM) fuel cell has been proposed and experimentally verified here in detail. The model takes into account both the anode and the cathode, and has an additional resonant loop on each side, comprising of a resistance, capacitance and inductance in parallel representing the processes within the catalyst layer. Using these additional circuit elements, more accurate and better fits to experimental impedance data in the wide frequency range at different current densities, cell temperatures, humidity of gases, air flow stoichiometries and backpressures were obtained.

Neomycin resistance as a selectable marker in Methanococcus maripaludis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Argyle, J.L.; Leigh, J.A.; Tumbula, D.L.

1996-11-01

The authors cloned the aminoglycoside phosphotransferase genes APH3{prime}I and APH3{prime}II between the Methanococcus voltae methyl reductase promoter and terminator in a plasmid containing a fragment of Methanococcus maripaludis chromosomal DNA. The resulting plasmids encoding neomycin resistance transformed M. maripaludis at frequencies similar to those observed for pKAS102 encoding puromycin resistance. The antibiotic geneticin was not inhibitory to M. maripaludis. 22 refs., 3 figs., 3 tabs.

Coating-type three-dimensional acetate-driven microbial fuel cells.

PubMed

Yu, Jin; Tang, Yulan

2015-08-01

This study uses sodium acetate as fuel to construct bioelectricity in coating-type three-dimensional microbial fuel cells anode. The coating-type three-dimensional anode was constructed using iron net as structural support, adhering a layer of carbon felt as primary coating and using carbon powder and 30% PTFE solution mixture as coating. The efficiency of electricity production and wastewater treatment were analyzed for the three-dimensional acetate-fed (C2H3NaO2) microbial fuel cells with the various ratio of the coating mixture. The results showed that the efficiency of electricity production was significantly improved when using the homemade coating-type microbial fuel cells anode compared with the one without coating on the iron net, which the apparent internal resistance was decreased by 59.4% and the maximum power density was increased by 1.5 times. It was found the electricity production was greatly influenced by the ratio of the carbon powder and PTFE in the coating. The electricity production was the highest with apparent internal resistance of 190 Ω, and maximum power density of 5189.4 mW m(-3) when 750 mg of carbon powder and 10 ml of PTFE (i.e., ratio 75:1) was used in the coating. With the efficiency of electricity production, wide distribution and low cost of the raw materials, the homemade acetate-fed microbial fuel cells provides a valuable reference to the development of the composition microbial fuel cell anode production. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Improving domestic wastewater treatment efficiency with constructed wetland microbial fuel cells: Influence of anode material and external resistance.

PubMed

Corbella, Clara; Puigagut, Jaume

2018-08-01

For the past few years, there has been an increasing interest in the operation of constructed wetlands as microbial fuel cells (CW-MFCs) for both the improvement of wastewater treatment efficiency and the production of energy. However, there is still scarce information on design and operation aspects to maximize CW-MFCs efficiency, especially for the treatment of real domestic wastewater. The aim of this study was to quantify the extent of treatment efficiency improvement carried out by membrane-less MFCs simulating a core of a shallow un-planted horizontal subsurface flow constructed wetland. The influence of the external resistance (50, 220, 402, 604 and 1000Ω) and the anode material (graphite and gravel) on treatment efficiency improvement were addressed. To this purpose, 6 lab-scale membrane-less MFCs were set-up and loaded in batch mode with domestic wastewater for 13weeks. Results showed that 220Ω was the best operation condition for maximising MFCs treatment efficiency, regardless the anode material employed. Gravel-based anode MFCs operated at closed circuit showed ca. 18%, 15%, 31% and 25% lower effluent concentration than unconnected MFCs to the COD, TOC, PO 4 -3 and NH 4 + -N, respectively. Main conclusion of the present work is that constructed wetlands operated as MFCs is a promising strategy to improve domestic wastewater treatment efficiency. However, further studies at pilot scale under more realistic conditions (such as planted systems operated under continuous mode) shall be performed to confirm the findings here reported. Copyright © 2018 Elsevier B.V. All rights reserved.

Fabrication and characterization of WO3/Ag/WO3 multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes

PubMed Central

2012-01-01

The dielectric/metal/dielectric multilayer is suitable for a transparent electrode because of its high-optical and high-electrical properties; however, it is fabricated by an expensive and inefficient multistep vacuum process. We present a WO3/Ag/WO3 (WAW) multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes (PLEDs). This WAW multilayer not only has high transmittance and low resistance but also can be easily and rapidly fabricated. We devised a novel method to deposit a thin WO3 layer by a solution process in an air environment. A tungstic acid solution was prepared from an aqueous solution of Na2WO4 and then converted to WO3 nanoparticles (NPs) by a thermal treatment. Thin WO3 NP layers form WAW multilayer with a thermal-evaporated Ag layer, and they improve the transmittance of the WAW multilayer because of its high transmittance and refractive index. Moreover, the surface of the WO3 layer is homogeneous and flat with low roughness because of the WO3 NP generation from the tungstic acid solution without aggregation. We performed optical simulation and experiments, and the optimized WAW multilayer had a high transmittance of 85% with a sheet resistance of 4 Ω/sq. Finally, PLEDs based on the WAW multilayer anode achieved a maximum luminance of 35,550 cd/m2 at 8 V, and this result implies that the solution-processed WAW multilayer is appropriate for use as a transparent anode in PLEDs. PMID:22587669

Fabrication and characterization of WO3/Ag/WO3 multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes.

PubMed

Jeon, Kangmin; Youn, Hongseok; Kim, Seongbeom; Shin, Seongbeom; Yang, Minyang

2012-05-15

The dielectric/metal/dielectric multilayer is suitable for a transparent electrode because of its high-optical and high-electrical properties; however, it is fabricated by an expensive and inefficient multistep vacuum process. We present a WO3/Ag/WO3 (WAW) multilayer transparent anode with solution-processed WO3 for polymer light-emitting diodes (PLEDs). This WAW multilayer not only has high transmittance and low resistance but also can be easily and rapidly fabricated. We devised a novel method to deposit a thin WO3 layer by a solution process in an air environment. A tungstic acid solution was prepared from an aqueous solution of Na2WO4 and then converted to WO3 nanoparticles (NPs) by a thermal treatment. Thin WO3 NP layers form WAW multilayer with a thermal-evaporated Ag layer, and they improve the transmittance of the WAW multilayer because of its high transmittance and refractive index. Moreover, the surface of the WO3 layer is homogeneous and flat with low roughness because of the WO3 NP generation from the tungstic acid solution without aggregation. We performed optical simulation and experiments, and the optimized WAW multilayer had a high transmittance of 85% with a sheet resistance of 4 Ω/sq. Finally, PLEDs based on the WAW multilayer anode achieved a maximum luminance of 35,550 cd/m2 at 8 V, and this result implies that the solution-processed WAW multilayer is appropriate for use as a transparent anode in PLEDs.

Phylogenetic and Metagenomic Analyses of Substrate-Dependent Bacterial Temporal Dynamics in Microbial Fuel Cells

PubMed Central

Zhang, Husen; Chen, Xi; Braithwaite, Daniel; He, Zhen

2014-01-01

Understanding the microbial community structure and genetic potential of anode biofilms is key to improve extracellular electron transfers in microbial fuel cells. We investigated effect of substrate and temporal dynamics of anodic biofilm communities using phylogenetic and metagenomic approaches in parallel with electrochemical characterizations. The startup non-steady state anodic bacterial structures were compared for a simple substrate, acetate, and for a complex substrate, landfill leachate, using a single-chamber air-cathode microbial fuel cell. Principal coordinate analysis showed that distinct community structures were formed with each substrate type. The bacterial diversity measured as Shannon index decreased with time in acetate cycles, and was restored with the introduction of leachate. The change of diversity was accompanied by an opposite trend in the relative abundance of Geobacter-affiliated phylotypes, which were acclimated to over 40% of total Bacteria at the end of acetate-fed conditions then declined in the leachate cycles. The transition from acetate to leachate caused a decrease in output power density from 243±13 mW/m2 to 140±11 mW/m2, accompanied by a decrease in Coulombic electron recovery from 18±3% to 9±3%. The leachate cycles selected protein-degrading phylotypes within phylum Synergistetes. Metagenomic shotgun sequencing showed that leachate-fed communities had higher cell motility genes including bacterial chemotaxis and flagellar assembly, and increased gene abundance related to metal resistance, antibiotic resistance, and quorum sensing. These differentially represented genes suggested an altered anodic biofilm community in response to additional substrates and stress from the complex landfill leachate. PMID:25202990

Phylogenetic and metagenomic analyses of substrate-dependent bacterial temporal dynamics in microbial fuel cells.

PubMed

Zhang, Husen; Chen, Xi; Braithwaite, Daniel; He, Zhen

2014-01-01

Understanding the microbial community structure and genetic potential of anode biofilms is key to improve extracellular electron transfers in microbial fuel cells. We investigated effect of substrate and temporal dynamics of anodic biofilm communities using phylogenetic and metagenomic approaches in parallel with electrochemical characterizations. The startup non-steady state anodic bacterial structures were compared for a simple substrate, acetate, and for a complex substrate, landfill leachate, using a single-chamber air-cathode microbial fuel cell. Principal coordinate analysis showed that distinct community structures were formed with each substrate type. The bacterial diversity measured as Shannon index decreased with time in acetate cycles, and was restored with the introduction of leachate. The change of diversity was accompanied by an opposite trend in the relative abundance of Geobacter-affiliated phylotypes, which were acclimated to over 40% of total Bacteria at the end of acetate-fed conditions then declined in the leachate cycles. The transition from acetate to leachate caused a decrease in output power density from 243±13 mW/m2 to 140±11 mW/m2, accompanied by a decrease in Coulombic electron recovery from 18±3% to 9±3%. The leachate cycles selected protein-degrading phylotypes within phylum Synergistetes. Metagenomic shotgun sequencing showed that leachate-fed communities had higher cell motility genes including bacterial chemotaxis and flagellar assembly, and increased gene abundance related to metal resistance, antibiotic resistance, and quorum sensing. These differentially represented genes suggested an altered anodic biofilm community in response to additional substrates and stress from the complex landfill leachate.

Functional Analysis of Genes Comprising the Locus of Heat Resistance in Escherichia coli.

PubMed

Mercer, Ryan; Nguyen, Oanh; Ou, Qixing; McMullen, Lynn; Gänzle, Michael G

2017-10-15

The locus of heat resistance (LHR) is a 15- to 19-kb genomic island conferring exceptional heat resistance to organisms in the family Enterobacteriaceae , including pathogenic strains of Salmonella enterica and Escherichia coli The complement of LHR-comprising genes that is necessary for heat resistance and the stress-induced or growth-phase-induced expression of LHR-comprising genes are unknown. This study determined the contribution of the seven LHR-comprising genes yfdX1 GI , yfdX2 , hdeD GI , orf11 , trx GI , kefB , and psiE GI by comparing the heat resistances of E. coli strains harboring plasmid-encoded derivatives of the different LHRs in these genes. (Genes carry a subscript "GI" [genomic island] if an ortholog of the same gene is present in genomes of E. coli ) LHR-encoded heat shock proteins sHSP20, ClpK GI , and sHSP GI are not sufficient for the heat resistance phenotype; YfdX1, YfdX2, and HdeD are necessary to complement the LHR heat shock proteins and to impart a high level of resistance. Deletion of trx GI , kefB , and psiE GI from plasmid-encoded copies of the LHR did not significantly affect heat resistance. The effect of the growth phase and the NaCl concentration on expression from the putative LHR promoter p2 was determined by quantitative reverse transcription-PCR and by a plasmid-encoded p2:GFP promoter fusion. The expression levels of exponential- and stationary-phase E. coli cells were not significantly different, but the addition of 1% NaCl significantly increased LHR expression. Remarkably, LHR expression in E. coli was dependent on a chromosomal copy of evgA In conclusion, this study improved our understanding of the genes required for exceptional heat resistance in E. coli and factors that increase their expression in food. IMPORTANCE The locus of heat resistance (LHR) is a genomic island conferring exceptional heat resistance to several foodborne pathogens. The exceptional level of heat resistance provided by the LHR questions the control of pathogens by current food processing and preparation techniques. The function of LHR-comprising genes and their regulation, however, remain largely unknown. This study defines a core complement of LHR-encoded proteins that are necessary for heat resistance and demonstrates that regulation of the LHR in E. coli requires a chromosomal copy of the gene encoding EvgA. This study provides insight into the function of a transmissible genomic island that allows otherwise heat-sensitive enteric bacteria, including pathogens, to lead a thermoduric lifestyle and thus contributes to the detection and control of heat-resistant enteric bacteria in food. Copyright © 2017 American Society for Microbiology.

Functional Analysis of Genes Comprising the Locus of Heat Resistance in Escherichia coli

PubMed Central

Mercer, Ryan; Nguyen, Oanh; Ou, Qixing; McMullen, Lynn

2017-01-01

ABSTRACT The locus of heat resistance (LHR) is a 15- to 19-kb genomic island conferring exceptional heat resistance to organisms in the family Enterobacteriaceae, including pathogenic strains of Salmonella enterica and Escherichia coli. The complement of LHR-comprising genes that is necessary for heat resistance and the stress-induced or growth-phase-induced expression of LHR-comprising genes are unknown. This study determined the contribution of the seven LHR-comprising genes yfdX1GI, yfdX2, hdeDGI, orf11, trxGI, kefB, and psiEGI by comparing the heat resistances of E. coli strains harboring plasmid-encoded derivatives of the different LHRs in these genes. (Genes carry a subscript “GI” [genomic island] if an ortholog of the same gene is present in genomes of E. coli.) LHR-encoded heat shock proteins sHSP20, ClpKGI, and sHSPGI are not sufficient for the heat resistance phenotype; YfdX1, YfdX2, and HdeD are necessary to complement the LHR heat shock proteins and to impart a high level of resistance. Deletion of trxGI, kefB, and psiEGI from plasmid-encoded copies of the LHR did not significantly affect heat resistance. The effect of the growth phase and the NaCl concentration on expression from the putative LHR promoter p2 was determined by quantitative reverse transcription-PCR and by a plasmid-encoded p2:GFP promoter fusion. The expression levels of exponential- and stationary-phase E. coli cells were not significantly different, but the addition of 1% NaCl significantly increased LHR expression. Remarkably, LHR expression in E. coli was dependent on a chromosomal copy of evgA. In conclusion, this study improved our understanding of the genes required for exceptional heat resistance in E. coli and factors that increase their expression in food. IMPORTANCE The locus of heat resistance (LHR) is a genomic island conferring exceptional heat resistance to several foodborne pathogens. The exceptional level of heat resistance provided by the LHR questions the control of pathogens by current food processing and preparation techniques. The function of LHR-comprising genes and their regulation, however, remain largely unknown. This study defines a core complement of LHR-encoded proteins that are necessary for heat resistance and demonstrates that regulation of the LHR in E. coli requires a chromosomal copy of the gene encoding EvgA. This study provides insight into the function of a transmissible genomic island that allows otherwise heat-sensitive enteric bacteria, including pathogens, to lead a thermoduric lifestyle and thus contributes to the detection and control of heat-resistant enteric bacteria in food. PMID:28802266

Real-time electrochemical impedance spectroscopy diagnosis of the solid oxide fuel cell for marine power applications

NASA Astrophysics Data System (ADS)

Nakajima, Hironori; Kitahara, Tatsumi

2017-11-01

We have investigated the behavior of an operating solid oxide fuel cell (SOFC) with supplying a simulated syngas to develop diagnosis method of the SOFC for marine power applications fueled with liquefied natural gas (LNG). We analyze the characteristics of a syngas-fueled intermediate temperature microtubular SOFC at 500 ∘C for accelerated deterioration by carbon deposition as a model case by electrochemical impedance spectroscopy (EIS) to in-situ find parameters useful for the real-time diagnosis. EIS analyses are performed by complex nonlinear least squares (CNLS) curve fitting to measured impedance spectra with an equivalent electric circuit model consisting of several resistances and capacitances attributed to the anode and cathode processes as well as Ohmic resistance of the cell. The characteristic changes of those circuit parameters by internal reforming and anode degradation are extracted, showing that they can be used for the real-time diagnosis of operating SOFCs.

Effects of Alloying Element Ca on the Corrosion Behavior and Bioactivity of Anodic Films Formed on AM60 Mg Alloys

PubMed Central

Anawati, Anawati; Asoh, Hidetaka; Ono, Sachiko

2016-01-01

Effects of alloying element Ca on the corrosion behavior and bioactivity of films formed by plasma electrolytic oxidation (PEO) on AM60 alloys were investigated. The corrosion behavior was studied by conducting electrochemical tests in 0.9% NaCl solution while the bioactivity was evaluated by soaking the specimens in simulated body fluid (SBF). Under identical anodization conditions, the PEO film thicknesses increased with increasing Ca content in the alloys, which enhanced the corrosion resistance in NaCl solution. Thicker apatite layers grew on the PEO films of Ca-containing alloys because Ca was incorporated into the PEO film and because Ca was present in the alloys. Improvement of corrosion resistance and bioactivity of the PEO-coated AM60 by alloying with Ca may be beneficial for biodegradable implant applications. PMID:28772371

Plasmid-encoded amikacin resistance in multiresistant strains of Klebsiella pneumoniae isolated from neonates with meningitis.

PubMed Central

Woloj, M; Tolmasky, M E; Roberts, M C; Crosa, J H

1986-01-01

Two multiresistant Klebsiella pneumoniae strains isolated from cerebrospinal fluid of human neonates were analyzed for their plasmid content. Two of the plasmids harbored by these strains, pJHCMW1 (11 kilobase pairs) and pJHCMW4 (75 kilobase pairs), carried genetic determinants for amikacin resistance. These plasmids also encoded resistance to kanamycin, tobramycin, and ampicillin which could be transferred to Escherichia coli by conjugation. Extracts from transconjugant derivatives carrying pJHCMW4 produced an acetyltransferase activity that acetylated all three aminoglycosides. Transconjugant derivatives carrying pJHCMW1 encoded both acetylating and phosphorylating activities. Southern blot hybridization analysis indicated considerable DNA homology between these two plasmids. Images PMID:3521478

MCR-1 and OXA-48 In Vivo Acquisition in KPC-Producing Escherichia coli after Colistin Treatment.

PubMed

Beyrouthy, Racha; Robin, Frederic; Lessene, Aude; Lacombat, Igor; Dortet, Laurent; Naas, Thierry; Ponties, Valérie; Bonnet, Richard

2017-08-01

The spread of mcr-1 -encoding plasmids into carbapenem-resistant Enterobacteriaceae raises concerns about the emergence of untreatable bacteria. We report the acquisition of mcr-1 in a carbapenem-resistant Escherichia coli strain after a 3-week course of colistin in a patient repatriated to France from Portugal. Whole-genome sequencing revealed that the Klebsiella pneumoniae carbapenemase-producing E. coli strain acquired two plasmids, an IncL OXA-48-encoding plasmid and an IncX4 mcr-1 -encoding plasmid. This is the first report of mcr-1 in carbapenemase-encoding bacteria in France. Copyright © 2017 American Society for Microbiology.

Older adults get episodic memory boosting from noninvasive stimulation of prefrontal cortex during learning.

PubMed

Sandrini, Marco; Manenti, Rosa; Brambilla, Michela; Cobelli, Chiara; Cohen, Leonardo G; Cotelli, Maria

2016-03-01

Episodic memory displays the largest degree of age-related decline, a process that is accelerated in pathological conditions such as amnestic mild cognitive impairment and Alzheimer's disease. Previous studies have shown that the left lateral prefrontal cortex (PFC) contributes to the encoding of episodic memories along the life span. The aim of this randomized, double-blind, placebo-controlled study was to test the hypothesis that anodal trascranial direct current stimulation (tDCS) over the left lateral PFC during the learning phase would enhance delayed recall of verbal episodic memories in elderly individuals. Older adults learned a list of words while receiving anodal or placebo (sham) tDCS. Memory recall was tested 48 hours and 1 month later. The results showed that anodal tDCS strengthened episodic memories, an effect indicated by enhanced delayed recall (48 hours) compared to placebo stimulation (Cohen's d effect size = 1.01). The observation that PFC-tDCS during learning can boost verbal episodic memory in the elderly opens up the possibility to design-specific neurorehabilitation protocols targeted to conditions that affect episodic memory such as mild cognitive impairment. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of Applied Current Density on Cavitation-Erosion Characteristics for Anodized Al Alloy.

PubMed

Lee, Seung-Jun; Kim, Seong-Jong

2018-02-01

Surface finishing is as important as selection of material to achieve durability. Surface finishing is a process to provide surface with the desired performance and features by applying external forces such as thermal energy or stress. This study investigated the optimum supply current density for preventing from cavitation damages by applying to an anodizing technique that artificially forms on the surface an oxide coating that has excellent mechanical characteristics, such as hardness, wear resistance. Result of hardness test, the greater hardness was associated with greater brittleness, resulting in deleterious characteristics. Consequently, under conditions such as the electrolyte concentration of 10 vol.%, the processing time of 40 min, the electrolyte temperature of 10 °C, and the current density of 20 mA/cm2 were considered to be the optimum anodizing conditions for improvement of durability in seawater.

Preventing Cracking of Anodized Coatings

NASA Technical Reports Server (NTRS)

He, Charles C.; Heslin, Thomas M.

1995-01-01

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

Silver Nanowires Modified with PEDOT: PSS and Graphene for Organic Light-Emitting Diodes Anode

PubMed Central

Xu, Yilin; Wei, Xiang; Wang, Cong; Cao, Jin; Chen, Yigang; Ma, Zhongquan; You, Ying; Wan, Jixiang; Fang, Xiaohong; Chen, Xiaoyuan

2017-01-01

Silver nanowires (AgNWs) networks are promising candidates for the replacement of indium tin oxide (ITO). However, the surface roughness of the AgNWs network is still too high for its application in optoelectronic devices. In this work, we have reduced the surface roughness of the AgNWs networks to 6.4 nm, compared to 33.9 nm of the as-deposited AgNWs network through the hot-pressing process, treatment with poly (3,4ethylenedioxythiophene)–poly (styrenesulfanate), and covered with graphene films. Using this method, we are able to produce AgNWs/PEDOT: PSS/SLG composite films with the transmittance and sheet resistance of 88.29% and 30 Ω/□, respectively. The OLEDs based on the AgNWs/PEDOT: PSS/SLG anodes are comparable to those based on ITO anodes. PMID:28349990

Low-cost stainless-steel wool anodes modified with polyaniline and polypyrrole for high-performance microbial fuel cells

NASA Astrophysics Data System (ADS)

Sonawane, Jayesh M.; Patil, Sunil A.; Ghosh, Prakash C.; Adeloju, Samuel B.

2018-03-01

A conducting polymer coated stainless-steel wool (SS-W) is proposed for use as a low-cost anode for microbial fuel cells (MFCs). When coated with polyaniline (PANi) and polypyrrole (PPy), the pristine SS-W, SS/PANi-W and SS/PPy-W anodes produced maximum current densities of 0.30 ± 0.04, 0.67 ± 0.05, 0.56 ± 0.07 mA cm-2, respectively, in air-cathode MFCs. Also, based on achieved power density, both SS/PANi-W and SS/PPy-W achieved 0.288 ± 0.036 mW cm-2 and 0.187 ± 0.017 mW cm-2, respectively, which were superior to 0.127 ± 0.011 mW cm-2 obtained with pristine SS-W. Further, in comparison with SS-P based anodes, all SS-W based anodes gave improved power densities under similar experimental conditions by at least 70%. Moreover, the charge transfer resistance of the SS-W was much lower (240 ± 25 Ω cm-2) than for the SS-P (3192 ± 239 Ω cm-2). The j0(apparent) values obtained for SS/PANi-W (0.098 ± 0.007 mA cm-2) and SS/PPy-W (0.036 ± 0.004 mA cm-2) anodes were also much higher than that of the pristine SS-W (0.020 ± 0.005 mA cm-2), as well as than those of all SS-P based anodes. The observed enhancement of the bioelectrocatalytic performances were well supported by physicochemical and electrochemical characterisation.

Efficient organic photovoltaic cells on a single layer graphene transparent conductive electrode using MoOx as an interfacial layer.

PubMed

Du, J H; Jin, H; Zhang, Z K; Zhang, D D; Jia, S; Ma, L P; Ren, W C; Cheng, H M; Burn, P L

2017-01-07

The large surface roughness, low work function and high cost of transparent electrodes using multilayer graphene films can limit their application in organic photovoltaic (OPV) cells. Here, we develop single layer graphene (SLG) films as transparent anodes for OPV cells that contain light-absorbing layers comprised of the evaporable molecular organic semiconductor materials, zinc phthalocyanine (ZnPc)/fullerene (C60), as well as a molybdenum oxide (MoO x ) interfacial layer. In addition to an increase in the optical transmittance, the SLG anodes had a significant decrease in surface roughness compared to two and four layer graphene (TLG and FLG) anodes fabricated by multiple transfer and stacking of SLGs. Importantly, the introduction of a MoO x interfacial layer not only reduced the energy barrier between the graphene anode and the active layer, but also decreased the resistance of the SLG by nearly ten times. The OPV cells with the structure of polyethylene terephthalate/SLG/MoO x /CuI/ZnPc/C60/bathocuproine/Al were flexible, and had a power conversion efficiency of up to 0.84%, which was only 17.6% lower than the devices with an equivalent structure but prepared on commercial indium tin oxide anodes. Furthermore, the devices with the SLG anode were 50% and 86.7% higher in efficiency than the cells with the TLG and FLG anodes. These results show the potential of SLG electrodes for flexible and wearable OPV cells as well as other organic optoelectronic devices.

Co-extrusion of electrolyte/anode functional layer/anode triple-layer ceramic hollow fibres for micro-tubular solid oxide fuel cells-electrochemical performance study

NASA Astrophysics Data System (ADS)

Li, Tao; Wu, Zhentao; Li, K.

2015-01-01

In this study, the effects of an anode functional layer (AFL) with controlled thickness on physical and electrochemical properties of a micro-tubular SOFC have been systematically studied. A series of electrolyte/AFL/anode triple-layer hollow fibres with controllable AFL thicknesses (16.9-52.7 μm) have been fabricated via a single-step phase-inversion assisted co-extrusion technique. Both robustness of the cell and gas-tightness of the electrolyte layer are considerably improved by introducing the AFL of this type. The fracture force of the sample with the thickest AFL (9.67 N) almost doubles when compared to the electrolyte/anode dual-layer counterpart (5.24 N). Gas-tightness of the electrolyte layer is also considerably increased as AFL contributes to better-matched sintering behaviours between different components. Moreover, the formation of an AFL simultaneously with electrolyte and anode significantly improves the cell performances. The sample with the thinnest AFL (approximately 16.9 μm, 6% of the total anode thickness) leads to a 30% (from 0.89 to 1.21 W cm-2) increase in maximum power density, due to increased triple-phase boundaries (TPB). However, further increase in TPB from a thicker AFL is less effective for improving the cell performance, due to the substantially increased fuel diffusion resistance and subsequently higher concentration polarization. This indicates that the control over the AFL thickness is critically important in avoiding offsetting the benefits of extended TPB and consequently decreased cell performances.

Three-Dimensional, Solid-State Mixed Electron-Ion Conductive Framework for Lithium Metal Anode.

PubMed

Xu, Shaomao; McOwen, Dennis W; Wang, Chengwei; Zhang, Lei; Luo, Wei; Chen, Chaoji; Li, Yiju; Gong, Yunhui; Dai, Jiaqi; Kuang, Yudi; Yang, Chunpeng; Hamann, Tanner R; Wachsman, Eric D; Hu, Liangbing

2018-06-13

Solid-state electrolytes (SSEs) have been widely considered as enabling materials for the practical application of lithium metal anodes. However, many problems inhibit the widespread application of solid state batteries, including the growth of lithium dendrites, high interfacial resistance, and the inability to operate at high current density. In this study, we report a three-dimensional (3D) mixed electron/ion conducting framework (3D-MCF) based on a porous-dense-porous trilayer garnet electrolyte structure created via tape casting to facilitate the use of a 3D solid state lithium metal anode. The 3D-MCF was achieved by a conformal coating of carbon nanotubes (CNTs) on the porous garnet structure, creating a composite mixed electron/ion conductor that acts as a 3D host for the lithium metal. The lithium metal was introduced into the 3D-MCF via slow electrochemical deposition, forming a 3D lithium metal anode. The slow lithiation leads to improved contact between the lithium metal anode and garnet electrolyte, resulting in a low resistance of 25 Ω cm 2 . Additionally, due to the continuous CNT coating and its seamless contact with the garnet we observed highly uniform lithium deposition behavior in the porous garnet structure. With the same local current density, the high surface area of the porous garnet framework leads to a higher overall areal current density for stable lithium deposition. An elevated current density of 1 mA/cm 2 based on the geometric area of the cell was demonstrated for continuous lithium cycling in symmetric lithium cells. For battery operation of the trilayer structure, the lithium can be cycled between the 3D-MCF on one side and the cathode infused into the porous structure on the opposite side. The 3D-MCF created by the porous garnet structure and conformal CNT coating provides a promising direction toward new designs in solid-state lithium metal batteries.

Corrosion control of cement-matrix and aluminum-matrix composites

NASA Astrophysics Data System (ADS)

Hou, Jiangyuan

Corrosion control of composite materials, particularly aluminum-matrix and cement-matrix composites, was addressed by surface treatment, composite formulation and cathodic protection. Surface treatment methods studied include anodization in the case of aluminum-matrix composites and oxidation treatment (using water) in the case of steel rebar for reinforcing concrete. The effects of reinforcement species (aluminum nitride (AIN) versus silicon carbide (SiC) particles) in the aluminum-matrix composites and of admixtures (carbon fibers, silica fume, latex and methylcellulose) in concrete on the corrosion resistance of composites were addressed. Moreover, the effect of admixtures in concrete and of admixtures in mortar overlay (as anode on concrete) on the efficiency of cathodic protection of steel reinforced concrete was studied. For SiC particle filled aluminum, anodization was performed successfully in an acid electrolyte, as for most aluminum alloys. However, for AlN particle filled aluminum, anodization needs to be performed in an alkaline (0.7 N NaOH) electrolyte instead. The concentration of NaOH in the electrolyte was critical. It was found that both silica fume and latex improved the corrosion resistance of rebar in concrete in both Ca(OH)sb2 and NaCl solutions, mainly because these admixtures decreased the water absorptivity. Silica fume was more effective than latex. Methylcellulose improved the corrosion resistance of rebar in concrete a little in Ca(OH)sb2 solution. Carbon fibers decreased the corrosion resistance of rebar in concrete, but this effect could be made up for by either silica fume or latex, such that silica fume was more effective than latex. Surface treatment in the form of water immersion for two days was found to improve the corrosion resistance of rebar in concrete. This treatment resulted in a thin uniform layer of black iron oxide (containing Fesp{2+}) on the entire rebar surface except on the cross-sectional surface. Prior to the treatment, the surface was non-uniform due to rusting. Sand blasting also made the surface uniform, but is an expensive process, compared to the water immersion method. For cathodic protection of steel rebar reinforced concrete, mortar overlay containing carbon fibers and latex needed 11% less driving voltage to protect the rebar in concrete than plain mortar overlay. However, multiple titanium electrical contacts were necessary, whether the overlay contained carbon fibers or not. For the same overlay (containing carbon fibers and latex), admixtures in the concrete also made a significant difference on the effect of cathodic protection; concrete with carbon fibers and silica fume needed 18% less driving voltage than plain concrete and 28% less than concrete containing silica fume.

Bar Code Labels

NASA Technical Reports Server (NTRS)

1988-01-01

American Bar Codes, Inc. developed special bar code labels for inventory control of space shuttle parts and other space system components. ABC labels are made in a company-developed anodizing aluminum process and consecutively marketed with bar code symbology and human readable numbers. They offer extreme abrasion resistance and indefinite resistance to ultraviolet radiation, capable of withstanding 700 degree temperatures without deterioration and up to 1400 degrees with special designs. They offer high resistance to salt spray, cleaning fluids and mild acids. ABC is now producing these bar code labels commercially or industrial customers who also need labels to resist harsh environments.

CrpP Is a Novel Ciprofloxacin-Modifying Enzyme Encoded by the Pseudomonas aeruginosa pUM505 Plasmid.

PubMed

Chávez-Jacobo, Víctor M; Hernández-Ramírez, Karen C; Romo-Rodríguez, Pamela; Pérez-Gallardo, Rocío Viridiana; Campos-García, Jesús; Gutiérrez-Corona, J Félix; García-Merinos, Juan Pablo; Meza-Carmen, Víctor; Silva-Sánchez, Jesús; Ramírez-Díaz, Martha I

2018-06-01

The pUM505 plasmid, isolated from a clinical Pseudomonas aeruginosa isolate, confers resistance to ciprofloxacin (CIP) when transferred into the standard P. aeruginosa strain PAO1. CIP is an antibiotic of the quinolone family that is used to treat P. aeruginosa infections. In silico analysis, performed to identify CIP resistance genes, revealed that the 65-amino-acid product encoded by the orf131 gene in pUM505 displays 40% amino acid identity to the Mycobacterium smegmatis aminoglycoside phosphotransferase (an enzyme that phosphorylates and inactivates aminoglycoside antibiotics). We cloned orf131 (renamed crpP , for c iprofloxacin r esistance p rotein, p lasmid encoded) into the pUCP20 shuttle vector. The resulting recombinant plasmid, pUC- crpP , conferred resistance to CIP on Escherichia coli strain J53-3, suggesting that this gene encodes a protein involved in CIP resistance. Using coupled enzymatic analysis, we determined that the activity of CrpP on CIP is ATP dependent, while little activity against norfloxacin was detected, suggesting that CIP may undergo phosphorylation. Using a recombinant His-tagged CrpP protein and liquid chromatography-tandem mass spectrometry, we also showed that CIP was phosphorylated prior to its degradation. Thus, our findings demonstrate that CrpP, encoded on the pUM505 plasmid, represents a new mechanism of CIP resistance in P. aeruginosa , which involves phosphorylation of the antibiotic. Copyright © 2018 American Society for Microbiology.

Molecular dynamics simulations of the first charge of a Li-ion—Si-anode nanobattery

DOE PAGES

Galvez-Aranda, Diego E.; Ponce, Victor; Seminario, Jorge M.

2017-03-16

Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ~3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. In this study, we performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery modelmore » during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li 14Si 5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. Also, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode.« less

Draft genome sequence of Actinotignum schaalii DSM 15541T: Genetic insights into the lifestyle, cell fitness and virulence.

PubMed

Yassin, Atteyet F; Langenberg, Stefan; Huntemann, Marcel; Clum, Alicia; Pillay, Manoj; Palaniappan, Krishnaveni; Varghese, Neha; Mikhailova, Natalia; Mukherjee, Supratim; Reddy, T B K; Daum, Chris; Shapiro, Nicole; Ivanova, Natalia; Woyke, Tanja; Kyrpides, Nikos C

2017-01-01

The permanent draft genome sequence of Actinotignum schaalii DSM 15541T is presented. The annotated genome includes 2,130,987 bp, with 1777 protein-coding and 58 rRNA-coding genes. Genome sequence analysis revealed absence of genes encoding for: components of the PTS systems, enzymes of the TCA cycle, glyoxylate shunt and gluconeogensis. Genomic data revealed that A. schaalii is able to oxidize carbohydrates via glycolysis, the nonoxidative pentose phosphate and the Entner-Doudoroff pathways. Besides, the genome harbors genes encoding for enzymes involved in the conversion of pyruvate to lactate, acetate and ethanol, which are found to be the end products of carbohydrate fermentation. The genome contained the gene encoding Type I fatty acid synthase required for de novo FAS biosynthesis. The plsY and plsX genes encoding the acyltransferases necessary for phosphatidic acid biosynthesis were absent from the genome. The genome harbors genes encoding enzymes responsible for isoprene biosynthesis via the mevalonate (MVA) pathway. Genes encoding enzymes that confer resistance to reactive oxygen species (ROS) were identified. In addition, A. schaalii harbors genes that protect the genome against viral infections. These include restriction-modification (RM) systems, type II toxin-antitoxin (TA), CRISPR-Cas and abortive infection system. A. schaalii genome also encodes several virulence factors that contribute to adhesion and internalization of this pathogen such as the tad genes encoding proteins required for pili assembly, the nanI gene encoding exo-alpha-sialidase, genes encoding heat shock proteins and genes encoding type VII secretion system. These features are consistent with anaerobic and pathogenic lifestyles. Finally, resistance to ciprofloxacin occurs by mutation in chromosomal genes that encode the subunits of DNA-gyrase (GyrA) and topisomerase IV (ParC) enzymes, while resistant to metronidazole was due to the frxA gene, which encodes NADPH-flavin oxidoreductase.

Imaging characteristics of the Extreme Ultraviolet Explorer microchannel plate detectors

NASA Technical Reports Server (NTRS)

Vallerga, J. V.; Kaplan, G. C.; Siegmund, O. H. W.; Lampton, M.; Malina, R. F.

1989-01-01

The Extreme Ultraviolet Explorer (EUVE) satellite will conduct an all-sky survey over the wavelength range from 70 A to 760 A using four grazing-incidence telescopes and seven microchannel-plate (MCP) detectors. The imaging photon-counting MCP detectors have active areas of 19.6 cm2. Photon arrival position is determined using a wedge-and-strip anode and associated pulse-encoding electronics. The imaging characteristics of the EUVE flight detectors are presented including image distortion, flat-field response, and spatial differential nonlinearity. Also included is a detailed discussion of image distortions due to the detector mechanical assembly, the wedge-and-strip anode, and the electronics. Model predictions of these distortions are compared to preflight calibration images which show distortions less than 1.3 percent rms of the detector diameter of 50 mm before correction. The plans for correcting these residual detector image distortions to less than 0.1 percent rms are also presented.

Synthesis and antibacterial activity of novel 15-membered macrolide derivatives: 4''-carbamate, 11,12-cyclic carbonate-4''-carbamate and 11,4''-di-O-arylcarbamoyl analogs of azithromycin.

PubMed

Ma, Shutao; Ma, Ruixin; Liu, Zhaopeng; Ma, Chenchen; Shen, Xuecui

2009-10-01

4''-Carbamate, 11,12-cyclic carbonate-4''-carbamate and 11,4''-di-O-arylcarbamoyl analogs of azithromycin were designed, synthesized and evaluated. The 4''-carbamate analogs retained excellent activity against erythromycin-susceptible Staphylococcus pneumoniae and showed improved activity against erythromycin-resistant Staphylococcus pneumoniae. Compared with 4''-carbamate analogs, 11,12-cyclic carbonate-4''-carbamate analogs exhibited improved activity against erythromycin-resistant Staphylococcus pneumoniae encoded by the mef gene or the erm and mef genes, and 11,4''-di-O-arylalkylcarbamoyl analogs showed greatly improved activity (0.25-0.5 microg/mL) against erythromycin-resistant Staphylococcus pneumoniae encoded by the erm gene. Among them, the novel series of 11,4''-di-O-arylalkylcarbamoyl analogs 7a-k exhibited potent and balanced activity against susceptible and resistant bacteria. In particular, compounds 7f and 7k were the most effective against susceptible bacteria and resistant bacteria encoded by the erm gene or the mef gene.

Improving operational anodising process performance using simulation approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liong, Choong-Yeun, E-mail: lg@ukm.edu.my; Ghazali, Syarah Syahidah, E-mail: syarah@gapps.kptm.edu.my

The use of aluminium is very widespread, especially in transportation, electrical and electronics, architectural, automotive and engineering applications sectors. Therefore, the anodizing process is an important process for aluminium in order to make the aluminium durable, attractive and weather resistant. This research is focused on the anodizing process operations in manufacturing and supplying of aluminium extrusion. The data required for the development of the model is collected from the observations and interviews conducted in the study. To study the current system, the processes involved in the anodizing process are modeled by using Arena 14.5 simulation software. Those processes consist ofmore » five main processes, namely the degreasing process, the etching process, the desmut process, the anodizing process, the sealing process and 16 other processes. The results obtained were analyzed to identify the problems or bottlenecks that occurred and to propose improvement methods that can be implemented on the original model. Based on the comparisons that have been done between the improvement methods, the productivity could be increased by reallocating the workers and reducing loading time.« less

The design of a Li-ion full cell battery using a nano silicon and nano multi-layer graphene composite anode

NASA Astrophysics Data System (ADS)

Eom, KwangSup; Joshi, Tapesh; Bordes, Arnaud; Do, Inhwan; Fuller, Thomas F.

2014-03-01

In this study, a Si-graphene composite, which is composed of nano Si particles and nano-sized multi-layer graphene particles, and micro-sized multi-layer graphene plate conductor, was used as the anode for Li-ion battery. The Si-graphene electrode showed the high capacity and stable cyclability at charge/discharge rate of C/2 in half cell tests. Nickel cobalt aluminum material (NCA) was used as a cathode in the full cell to evaluate the practicality of the new Si-graphene material. Although the Si-graphene anode has more capacity than the NCA cathode in this designed full cell, the Si-graphene anode had a greater effect on the full-cell performance due to its large initial irreversible capacity loss and continuous SEI formation during cycling. When fluoro-ethylene carbonate was added to the electrolyte, the cyclability of the full cell was much improved due to less SEI formation, which was confirmed by the decreases in the 1st irreversible capacity loss, overpotential for the 1st lithiation, and the resistance of the SEI.

Properties of anodic oxides grown on a hafnium–tantalum–titanium thin film library

PubMed Central

Mardare, Andrei Ionut; Ludwig, Alfred; Savan, Alan; Hassel, Achim Walter

2014-01-01

A ternary thin film combinatorial materials library of the valve metal system Hf–Ta–Ti obtained by co-sputtering was studied. The microstructural and crystallographic analysis of the obtained compositions revealed a crystalline and textured surface, with the exception of compositions with Ta concentration above 48 at.% which are amorphous and show a flat surface. Electrochemical anodization of the composition spread thin films was used for analysing the growth of the mixed surface oxides. Oxide formation factors, obtained from the potentiodynamic anodization curves, as well as the dielectric constants and electrical resistances, obtained from electrochemical impedance spectroscopy, were mapped along two dimensions of the library using a scanning droplet cell microscope. The semiconducting properties of the anodic oxides were mapped using Mott–Schottky analysis. The degree of oxide mixing was analysed qualitatively using x-ray photoelectron spectroscopy depth profiling. A quantitative analysis of the surface oxides was performed and correlated to the as-deposited metal thin film compositions. In the concurrent transport of the three metal cations during oxide growth a clear speed order of Ti > Hf > Ta was proven. PMID:27877648

Mesostructured platinum-free anode and carbon-free cathode catalysts for durable proton exchange membrane fuel cells.

PubMed

Cui, Xiangzhi; Shi, Jianlin; Wang, Yongxia; Chen, Yu; Zhang, Lingxia; Hua, Zile

2014-01-01

As one of the most important clean energy sources, proton exchange membrane fuel cells (PEMFCs) have been a topic of extensive research focus for decades. Unfortunately, several critical technique obstacles, such as the high cost of platinum electrode catalysts, performance degradation due to the CO poisoning of the platinum anode, and carbon corrosion by oxygen in the cathode, have greatly impeded its commercial development. A prototype of a single PEMFC catalyzed by a mesostructured platinum-free WO3/C anode and a mesostructured carbon-free Pt/WC cathode catalysts is reported herein. The prototype cell exhibited 93% power output of a standard PEMFC using commercial Pt/C catalysts at 50 and 70 °C, and more importantly, CO poisoning-free and carbon corrosion-resistant characters of the anode and cathode, respectively. Consequently, the prototype cell demonstrated considerably enhanced cell operation durability. The mesostructured electrode catalysts are therefore highly promising in the future development and application of PEMFCs. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An artificial interphase enables reversible magnesium chemistry in carbonate electrolytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Son, Seoung-Bum; Gao, Tao; Harvey, Steve P.

Magnesium-based batteries possess potential advantages over their lithium counterparts. However, reversible Mg chemistry requires a thermodynamically stable electrolyte at low potential, which is usually achieved with corrosive components and at the expense of stability against oxidation. In lithium-ion batteries the conflict between the cathodic and anodic stabilities of the electrolytes is resolved by forming an anode interphase that shields the electrolyte from being reduced. This strategy cannot be applied to Mg batteries because divalent Mg2+ cannot penetrate such interphases. Here, we engineer an artificial Mg2+-conductive interphase on the Mg anode surface, which successfully decouples the anodic and cathodic requirements formore » electrolytes and demonstrate highly reversible Mg chemistry in oxidation-resistant electrolytes. The artificial interphase enables the reversible cycling of a Mg/V2O5 full-cell in the water-containing, carbonate-based electrolyte. This approach provides a new avenue not only for Mg but also for other multivalent-cation batteries facing the same problems, taking a step towards their use in energy-storage applications.« less

Tin doped indium oxide anodes with artificially controlled nano-scale roughness using segregated Ag nanoparticles for organic solar cells

NASA Astrophysics Data System (ADS)

Kim, Hyo-Joong; Ko, Eun-Hye; Noh, Yong-Jin; Na, Seok-In; Kim, Han-Ki

2016-09-01

Nano-scale surface roughness in transparent ITO films was artificially formed by sputtering a mixed Ag and ITO layer and wet etching of segregated Ag nanoparticles from the surface of the ITO film. Effective removal of self-segregated Ag particles from the grain boundaries and surface of the crystalline ITO film led to a change in only the nano-scale surface morphology of ITO film without changes in the sheet resistance and optical transmittance. A nano-scale rough surface of the ITO film led to an increase in contact area between the hole transport layer and the ITO anode, and eventually increased the hole extraction efficiency in the organic solar cells (OSCs). The heterojunction OSCs fabricated on the ITO anode with a nano-scale surface roughness exhibited a higher power conversion efficiency of 3.320%, than that (2.938%) of OSCs made with the reference ITO/glass. The results here introduce a new method to improve the performance of OSCs by simply modifying the surface morphology of the ITO anodes.

Optimization of the electrochemical performance of a Ni/Ce0.9Gd0.1O2-δ-impregnated La0.57Sr0.15TiO3 anode in hydrogen

NASA Astrophysics Data System (ADS)

Xia, Tian; Brüll, Annelise; Grimaud, Alexis; Fourcade, Sébastien; Mauvy, Fabrice; Zhao, Hui; Grenier, Jean-Claude; Bassat, Jean-Marc

2014-09-01

A-site deficient perovskite La0.57Sr0.15TiO3 (LSTO) materials are synthesized by a modified polyacrylamide gel route. X-ray diffraction pattern of LSTO indicates an orthorhombic structure. The thermal expansion coefficient of LSTO is 10.0 × 10-6 K-1 at 600 °C in 5%H2/Ar. LSTO shows an electrical conductivity of 2 S cm-1 at 600 °C in 3%H2O/H2. A new composite material, containing the porous LSTO backbone impregnated with small amounts of Ce0.9Gd0.1O2-δ (CGO) (3.4-8.3 wt.%) and Ni/Cu (2.0-6.3 wt.%), is investigated as an alternative anode for solid oxide fuel cells (SOFCs). Because of the substantial electro-catalytic activity of the fine and well-dispersed Ni particles on the surface of the ceramic framework, the polarization resistance of 6.3%Ni-8.3%CGO-LSTO anode reaches 0.73 Ω cm2 at 800 °C in 3%H2O/H2. In order to further improve the anodic performance, corn starch and carbon black are used as pore-formers to optimize the microstructure of anodes.

Post-mortem analysis on LiFePO4|Graphite cells describing the evolution & composition of covering layer on anode and their impact on cell performance

NASA Astrophysics Data System (ADS)

Lewerenz, Meinert; Warnecke, Alexander; Sauer, Dirk Uwe

2017-11-01

During cyclic aging of lithium-ion batteries the formation of a μm-thick covering layer on top of the anode facing the separator is found on top of the anode. In this work several post-mortem analyses of cyclic aged cylindrical LFP|Graphite cells are evaluated to give a detailed characterization of the covering layer and to find possible causes for the evolution of such a layer. The analyses of the layer with different methods return that it consists to high percentage of plated active lithium, deposited Fe and products of a solid electrolyte interphase (SEI). The deposition is located mainly in the center of the cell symmetrical to the coating direction. The origin of these depositions is assumed in locally overcharged particles, Fe deposition or inhomogeneous distribution of capacity density. As a secondary effect the deposition on one side increases the thickness locally; thereafter a pressure-induced overcharging due to charge agglomeration of the back side of the anode occurs. Finally a compact and dense covering layer in a late state of aging leads to deactivation of the covered parts of the anode and cathode due to suppressed lithium-ion conductivity. This leads to increasing slope of capacity fade and increase of internal resistance.

Cathode readout with stripped resistive drift tubes

NASA Astrophysics Data System (ADS)

Bychkov, V. N.; Kekelidze, G. D.; Novikov, E. A.; Peshekhonov, V. D.; Shafranov, M. D.; Zhiltsov, V. E.

1995-12-01

A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with a carbon layer with a resistivity of 0.5, 30 and 70 kΩ/□. Both the anode wire and the cathode strip signals were detected to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented.

An open circuit voltage equation enabling separation of cathode and anode polarization resistances of ceria electrolyte based solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Zhang, Yanxiang; Chen, Yu; Yan, Mufu

2017-07-01

The open circuit voltage (OCV) of solid oxide fuel cells is generally overestimated by the Nernst equation and the Wagner equation, due to the polarization losses at electrodes. Considering both the electronic conduction of electrolyte and the electrode polarization losses, we express the OCV as an implicit function of the characteristic oxygen pressure of electrolyte (p* [atm], at which the electronic and ionic conductivities are the same), and the relative polarization resistance of electrodes (rc = Rc/Ri and ra = Ra/Ri, where Ri/c/a [Ωcm2] denotes the ionic resistance of electrolyte, and the polarization resistances of cathode and anode, respectively). This equation approaches to the Wagner equation when the electrodes are highly active (rc and ra → 0), and approaches to the Nernst equation when the electrolyte is a purely ionic conductor (p* → 0). For the fuel cells whose OCV is well below the prediction of the Wagner equation, for example with thin doped ceria electrolyte, it is demonstrated that the combination of OCV and impedance spectroscopy measurements allows the determination of p*, Rc and Ra. This equation can serve as a simple yet powerful tool to study the internal losses in the cell under open circuit condition.

A Eukaryotic-Type Serine/Threonine Protein Kinase Is Required for Biofilm Formation, Genetic Competence, and Acid Resistance in Streptococcus mutans

PubMed Central

Hussain, Haitham; Branny, Pavel; Allan, Elaine

2006-01-01

We report an operon encoding a eukaryotic-type serine/threonine protein kinase (STPK) and its cognate phosphatase (STPP) in Streptococcus mutans. Mutation of the gene encoding the STPK produced defects in biofilm formation, genetic competence, and acid resistance, determinants important in caries pathogenesis. PMID:16452447

Effect of milling methods on performance of Ni-Y 2O 3-stabilized ZrO 2 anode for solid oxide fuel cell

NASA Astrophysics Data System (ADS)

Cho, Hyoup Je; Choi, Gyeong Man

A Ni-YSZ (Y 2O 3-stabilized ZrO 2) composite is commonly used as a solid oxide fuel cell anode. The composite powders are usually synthesized by mixing NiO and YSZ powders. The particle size and distribution of the two phases generally determine the performance of the anode. Two different milling methods are used to prepare the composite anode powders, namely, high-energy milling and ball-milling that reduce the particle size. The particle size and the Ni distribution of the two composite powders are examined. The effects of milling on the performance are evaluated by using both an electrolyte-supported, symmetric Ni-YSZ/YSZ/Ni-YSZ cell and an anode-supported, asymmetric cell. The performance is examined at 800 °C by impedance analysis and current-voltage measurements. Pellets made by using high-energy milled NiO-YSZ powders have much smaller particle sizes and a more uniform distribution of Ni particles than pellets made from ball-milled powder, and thus the polarization resistance of the electrode is also smaller. The maximum power density of the anode-supported cell prepared by using the high-energy milled powder is ∼850 mW cm -2 at 800 °C compared with ∼500 mW cm -2 for the cell with ball-milled powder. Thus, high-energy milling is found to be more effective in reducing particle size and obtaining a uniform distribution of Ni particles.

Molecular dynamics simulations of the first charge of a Li-ion-Si-anode nanobattery.

PubMed

Galvez-Aranda, Diego E; Ponce, Victor; Seminario, Jorge M

2017-04-01

Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ∼3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. We performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery model during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li 14 Si 5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. In addition, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode. Graphical Abstract Nanobattery: LiCoO 2 cathode, electrolyte solution of 1M Li + PF 6 - in ethylene carbonate, and Si crystal anode, which changes its volume due to lithiation during the first charge.

Doping profile measurements in silicon using terahertz time domain spectroscopy (THz-TDS) via electrochemical anodic oxidation

NASA Astrophysics Data System (ADS)

Tulsyan, Gaurav

Doping profiles are engineered to manipulate device properties and to determine electrical performances of microelectronic devices frequently. To support engineering studies afterward, essential information is usually required from physically characterized doping profiles. Secondary Ion Mass Spectrometry (SIMS), Spreading Resistance Profiling (SRP) and Electrochemical Capacitance Voltage (ECV) profiling are standard techniques for now to map profile. SIMS yields a chemical doping profile via ion sputtering process and owns a better resolution, whereas ECV and SRP produce an electrical doping profile detecting free carriers in microelectronic devices. The major difference between electrical and chemical doping profiles is at heavily doped regions greater than 1020 atoms/cm3. At the profile region over the solubility limit, inactive dopants induce a flat plateau and detected by electrical measurements only. Destructive techniques are usually designed as stand-alone systems to study impurities. For an in-situ process control purpose, non-contact methods, such as ellipsometry and non-contact capacitance voltage (CV) techniques are current under development. In this theses work, terahertz time domain spectroscopy (THz-TDS) is utilized to achieve electrical doping profile in both destructive and non-contact manners. In recent years the Terahertz group at Rochester Institute Technology developed several techniques that use terahertz pulses to non-destructively map doping profiles. In this thesis, we study a destructive but potentially higher resolution version of the terahertz based approach to map the profile of activated dopants and augment the non-destructive approaches already developed. The basic idea of the profile mapping approach developed in this MS thesis is to anodize, and thus oxidize to silicon dioxide, thin layers (down to below 10 nm) of the wafer with the doping profile to be mapped. Since the dopants atoms and any free carriers in the silicon oxide thin film are invisible to the terahertz probe this anodization step very effectively removes a 'thin slice' from the doping profile to be mapped. By iterating between anodization and terahertz measurements that detect only the 'remaining' non-oxidized portion of the doping profile one can re-construct the doping profile with significantly higher precision compared to what is possible by only a single non-destructive measurement of the un-anodized profile as used in the non-destructive version of our technique. In this MS thesis we explore all aspects of this anodization based variation of doping profile mapping using free space terahertz pulses. This includes a study of silicon dioxide thin film growth using a room temperature electrochemical oxidation process. Etching procedures providing the option to remove between successive anodization and terahertz measurement steps. THz-TDS measurements of successively anodized profiles will be compared with sheet resistance and SIMS measurements to benchmark and improve the new technique.

An intragenic approach to confer glyphosate resistance in chile (Capsicum annuum) by introducing an in vitro mutagenized chile EPSPS gene encoding for a glyphosate resistant EPSPS protein

PubMed Central

Bagga, Suman; Apodaca, Kimberly; Lucero, Yvonne

2018-01-01

Chile pepper (Capsicum annuum) is an important high valued crop worldwide, and when grown on a large scale has problems with weeds. One important herbicide used is glyphosate. Glyphosate inactivates the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), a key enzyme in the synthesis of aromatic amino acids. A transgenic approach towards making glyphosate resistant plants, entails introducing copies of a gene encoding for glyphosate-resistant EPSPS enzyme into the plant. The main objective of our work was to use an intragenic approach to confer resistance to glyphosate in chile which would require using only chile genes for transformation including the selectable marker. Tobacco was used as the transgenic system to identify different gene constructs that would allow for the development of the intragenic system for chile, since chile transformation is inefficient. An EPSPS gene was isolated from chile and mutagenized to introduce substitutions that are known to make the encoded enzyme resistant to glyphosate. The promoter for EPSPS gene was isolated from chile and the mutagenized chile EPSPS cDNA was engineered behind both the CaMV35S promoter and the EPSPS promoter. The leaves from the transformants were checked for resistance to glyphosate using a cut leaf assay. In tobacco, though both gene constructs exhibited some degree of resistance to glyphosate, the construct with the CaMV35S promoter was more effective and as such chile was transformed with this gene construct. The chile transformants showed resistance to low concentrations of glyphosate. Furthermore, preliminary studies showed that the mutated EPSPS gene driven by the CaMV35S promoter could be used as a selectable marker for transformation. We have shown that an intragenic approach can be used to confer glyphosate-resistance in chile. However, we need a stronger chile promoter and a mutated chile gene that encodes for a more glyphosate resistant EPSPS protein. PMID:29649228

Aphid-encoded variability in susceptibility to a parasitoid

PubMed Central

2014-01-01

Background Many animals exhibit variation in resistance to specific natural enemies. Such variation may be encoded in their genomes or derived from infection with protective symbionts. The pea aphid, Acyrthosiphon pisum, for example, exhibits tremendous variation in susceptibility to a common natural enemy, the parasitic wasp Aphidius ervi. Pea aphids are often infected with the heritable bacterial symbiont, Hamiltonella defensa, which confers partial to complete resistance against this parasitoid depending on bacterial strain and associated bacteriophages. That previous studies found that pea aphids without H. defensa (or other symbionts) were generally susceptible to parasitism, together with observations of a limited encapsulation response, suggested that pea aphids largely rely on infection with H. defensa for protection against parasitoids. However, the limited number of uninfected clones previously examined, and our recent report of two symbiont-free resistant clones, led us to explicitly examine aphid-encoded variability in resistance to parasitoids. Results After rigorous screening for known and unknown symbionts, and microsatellite genotyping to confirm clonal identity, we conducted parasitism assays using fifteen clonal pea aphid lines. We recovered significant variability in aphid-encoded resistance, with variation levels comparable to that contributed by H. defensa. Because resistance can be costly, we also measured aphid longevity and cumulative fecundity of the most and least resistant aphid lines under permissive conditions, but found no trade-offs between higher resistance and these fitness parameters. Conclusions These results indicate that pea aphid resistance to A. ervi is more complex than previously appreciated, and that aphids employ multiple tactics to aid in their defense. While we did not detect a tradeoff, these may become apparent under stressful conditions or when resistant and susceptible aphids are in direct competition. Understanding sources and amounts of variation in resistance to natural enemies is necessary to understand the ecological and evolutionary dynamics of antagonistic interactions, such as the potential for coevolution, but also for the successful management of pest populations through biological control. PMID:24916045

Engineering three-dimensionally electrodeposited Si-on-Ni inverse opal structure for high volumetric capacity Li-ion microbattery anode.

PubMed

Liu, Hao; Cho, Hyung-Man; Meng, Ying Shirley; Li, Quan

2014-06-25

Aiming at improving the volumetric capacity of nanostructured Li-ion battery anode, an electrodeposited Si-on-Ni inverse opal structure has been proposed in the present work. This type of electrode provides three-dimensional bi-continuous pathways for ion/electron transport and high surface area-to-volume ratios, and thus exhibits lower interfacial resistance, but higher effective Li ions diffusion coefficients, when compared to the Si-on-Ni nanocable array electrode of the same active material mass. As a result, improved volumetric capacities and rate capabilities have been demonstrated in the Si-on-Ni inverse opal anode. We also show that optimization of the volumetric capacities and the rate performance of the inverse opal electrode can be realized by manipulating the pore size of the Ni scaffold and the thickness of the Si deposit.

Simulation design of uniform low turn-on voltage and high reverse blocking AlGaN/GaN power field effect rectifier with trench heterojunction anode

NASA Astrophysics Data System (ADS)

Wang, Fangzhou; Chen, Wanjun; Wang, Zeheng; Sun, Ruize; Wei, Jin; Li, Xuan; Shi, Yijun; Jin, Xiaosheng; Xu, Xiaorui; Chen, Nan; Zhou, Qi; Zhang, Bo

2017-05-01

To achieve uniform low turn-on voltage and high reverse blocking capability, an AlGaN/GaN power field effect rectifier with trench heterojunction anode (THA-FER) is proposed and investigated in this work which includes only simulated data and no real experimental result. VT has a low saturation value when trench height (HT) is beyond 300 nm, confirming it is possible to control the VT accurately without precisely controlling the HT in the THA-FER. Meanwhile, high HT anode reduces reverse leakage current and yields high breakdown voltage (VB). A superior high Baliga's Figure of Merits (BFOM = VB2/Ron,sp, Ron,sp is specific-on resistance) of 1228 MW/cm2 reveals the THA-FER caters for the demands of high efficiency GaN power applications.

Preparation of Advanced CuO Nanowires/Functionalized Graphene Composite Anode Material for Lithium Ion Batteries.

PubMed

Zhang, Jin; Wang, Beibei; Zhou, Jiachen; Xia, Ruoyu; Chu, Yingli; Huang, Jia

2017-01-17

The copper oxide (CuO) nanowires/functionalized graphene (f-graphene) composite material was successfully composed by a one-pot synthesis method. The f-graphene synthesized through the Birch reduction chemistry method was modified with functional group "-(CH₂)₅COOH", and the CuO nanowires (NWs) were well dispersed in the f-graphene sheets. When used as anode materials in lithium-ion batteries, the composite exhibited good cyclic stability and decent specific capacity of 677 mA·h·g -1 after 50 cycles. CuO NWs can enhance the lithium-ion storage of the composites while the f-graphene effectively resists the volume expansion of the CuO NWs during the galvanostatic charge/discharge cyclic process, and provide a conductive paths for charge transportation. The good electrochemical performance of the synthesized CuO/f-graphene composite suggests great potential of the composite materials for lithium-ion batteries anodes.

Characterization of bla(CMY)-encoding plasmids among Salmonella isolated in the United States in 2007.

PubMed

Folster, Jason P; Pecic, Gary; McCullough, Andre; Rickert, Regan; Whichard, Jean M

2011-12-01

Salmonella enterica is one of the most common bacterial causes of foodborne illness, and nontyphoidal Salmonella is estimated to cause ∼1.2 million illnesses in the United States each year. Plasmids are mobile genetic elements that play a critical role in the dissemination of antimicrobial resistance determinants. AmpC-type CMY β-lactamases (bla(CMY)) confer resistance to extended-spectrum cephalosporins and β-lactam/β-lactamase inhibitor combinations and are commonly plasmid-encoded. A variety of plasmids have been shown to encode CMY β-lactamases and certain plasmids may be associated with particular Salmonella serotypes or environmental sources. In this study, we characterized bla(CMY) β-lactamase-encoding plasmids among Salmonella isolates. Isolates of Salmonella from specimens collected from humans in 2007 were submitted to the Centers for Disease Control and Prevention National Antimicrobial Resistance Monitoring System laboratory for susceptibility testing. Three percent (65/2161) of Salmonella isolates displayed resistance to ceftriaxone (minimum inhibitory concentration [MIC] ≥4 mg/L) and amoxicillin/clavulanic acid (MIC ≥32 mg/L), a combination associated with the presence of a bla(CMY) mechanism of resistance. Sixty-four (98.5%) isolates were polymerase chain reaction-positive for bla(CMY) genes. Transformation and conjugation studies showed that 95% (61/64) of the bla(CMY) genes were plasmid-encoded. Most of the bla(CMY)-positive isolates were serotype Typhimurium, Newport, Heidelberg, and Agona. Forty-three plasmids were replicon type IncA/C, 15 IncI1, 2 contained multiple replicon loci, and 1 was untypeable. IncI1 plasmids conferred only the bla(CMY)-associated resistance phenotype, whereas IncA/C plasmids conferred additional multi-drug resistance (MDR) phenotypes to drugs such as chloramphenicol, sulfisoxazole, and tetracycline. Most of the IncI1 plasmids (12/15) were sequence type 12 by plasmid multi-locus sequence typing. CMY β-lactamase-encoding plasmids among human isolates of Salmonella in the United States tended to be large MDR IncA/C plasmids or single resistance determinant IncI1 plasmids. In general, IncI1 plasmids were identified among serotypes commonly associated with poultry, whereas IncA/C plasmids were more likely to be identified among cattle/beef-associated serotypes.

DNA Gyrase Is the Target for the Quinolone Drug Ciprofloxacin in Arabidopsis thaliana*

PubMed Central

Evans-Roberts, Katherine M.; Mitchenall, Lesley A.; Wall, Melisa K.; Leroux, Julie; Mylne, Joshua S.; Maxwell, Anthony

2016-01-01

The Arabidopsis thaliana genome contains four genes that were originally annotated as potentially encoding DNA gyrase: ATGYRA, ATGYRB1, ATGYRB2, and ATGYRB3. Although we subsequently showed that ATGYRB3 does not encode a gyrase subunit, the other three genes potentially encode subunits of a plant gyrase. We also showed evidence for the existence of supercoiling activity in A. thaliana and that the plant is sensitive to quinolone and aminocoumarin antibiotics, compounds that target DNA gyrase in bacteria. However, it was not possible at that time to show whether the A. thaliana genes encoded an active gyrase enzyme, nor whether that enzyme is indeed the target for the quinolone and aminocoumarin antibiotics. Here we show that an A. thaliana mutant resistant to the quinolone drug ciprofloxacin has a point mutation in ATGYRA. Moreover we show that, as in bacteria, the quinolone-sensitive (wild-type) allele is dominant to the resistant gene. Further we have heterologously expressed ATGYRA and ATGYRB2 in a baculovirus expression system and shown supercoiling activity of the partially purified enzyme. Expression/purification of the quinolone-resistant A. thaliana gyrase yields active enzyme that is resistant to ciprofloxacin. Taken together these experiments now show unequivocally that A. thaliana encodes an organelle-targeted DNA gyrase that is the target of the quinolone drug ciprofloxacin; this has important consequences for plant physiology and the development of herbicides. PMID:26663076

Light-weight free-standing carbon nanotube-silicon films for anodes of lithium ion batteries.

PubMed

Cui, Li-Feng; Hu, Liangbing; Choi, Jang Wook; Cui, Yi

2010-07-27

Silicon is an attractive alloy-type anode material because of its highest known capacity (4200 mAh/g). However, lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300%, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Si nanostructures such as nanowires, which are chemically and electrically bonded to the current collector, can overcome the pulverization problem, however, the heavy metal current collectors in these systems are larger in weight than Si active material. Herein we report a novel anode structure free of heavy metal current collectors by integrating a flexible, conductive carbon nanotube (CNT) network into a Si anode. The composite film is free-standing and has a structure similar to the steel bar reinforced concrete, where the infiltrated CNT network functions as both mechanical support and electrical conductor and Si as a high capacity anode material for Li-ion battery. Such free-standing film has a low sheet resistance of approximately 30 Ohm/sq. It shows a high specific charge storage capacity (approximately 2000 mAh/g) and a good cycling life, superior to pure sputtered-on silicon films with similar thicknesses. Scanning electron micrographs show that Si is still connected by the CNT network even when small breaking or cracks appear in the film after cycling. The film can also "ripple up" to release the strain of a large volume change during lithium intercalation. The conductive composite film can function as both anode active material and current collector. It offers approximately 10 times improvement in specific capacity compared with widely used graphite/copper anode sheets.

Preparation of RuO2-TiO2/Nano-graphite composite anode for electrochemical degradation of ceftriaxone sodium.

PubMed

Li, Dong; Guo, Xiaolei; Song, Haoran; Sun, Tianyi; Wan, Jiafeng

2018-06-05

Graphite-like material is widely used for preparing various electrodes for wastewater treatment. To enhance the electrochemical degradation efficiency of Nano-graphite (Nano-G) anode, RuO 2 -TiO 2 /Nano-G composite anode was prepared through the sol-gel method and hot-press technology. RuO 2 -TiO 2 /Nano-G composite was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and N 2 adsorption-desorption. Results showed that RuO 2 , TiO 2 and Nano-G were composited successfully, and RuO 2 and TiO 2 nanoparticles were distributed uniformly on the surface of Nano-G sheet. Specific surface area of RuO 2 -TiO 2 /Nano-G composite was higher than that of TiO 2 /Nano-G composite and Nano-G. Electrochemical performances of RuO 2 -TiO 2 /Nano-G anode were investigated by cyclic voltammetry, electrochemical impedance spectroscopy. RuO 2 -TiO 2 /Nano-G anode was applied to electrochemical degradation of ceftriaxone. The generation of hydroxyl radical (OH) was measured. Results demonstrated that RuO 2 -TiO 2 /Nano-G anode displayed enhanced electrochemical degradation efficiency towards ceftriaxone and yield of OH, which is derived from the synergetic effect between RuO 2 , TiO 2 and Nano-G, which enhance the specific surface area, improve the electrochemical oxidation activity and lower the charge transfer resistance. Besides, the possible degradation intermediates and pathways of ceftriaxone sodium were identified. This study may provide a viable and promising prospect for RuO 2 -TiO 2 /Nano-G anode towards effective electrochemical degradation of antibiotics from wastewater. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and characterization of silver doped hydroxyapatite nanocomposite coatings and evaluation of their antibacterial and corrosion resistance properties in simulated body fluid.

PubMed

Mirzaee, Majid; Vaezi, Mohammadreza; Palizdar, Yahya

2016-12-01

Silver-doped hydroxyapatite (Ca10-xAgx(PO4)6(OH)2-x) films were synthesized and deposited on anodized titanium (Ti) using electrophoretic. The influence of different silver-dopant contents (X=0, 0.02, 0.05, 0.08 and 0.1) on the phase formation and microstructure of the powders were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscope (XPS), and Fourier transform infrared spectrum analysis (FT-IR). XRD analysis confirmed the formation of Hexagonal structure of hydroxyapatite (HAp) annealed at 600°C with a small shift in the major peak position toward lower angles with adding silver. FT-IR spectroscopy disclosed the presence of the different vibrational modes matching to phosphates and hydroxyl groups and the absence of any band characteristics to silver. XPS analysis showed that 75% and 23% of silver was in the chemical states of Ag(2+) and Ag(+), respectively. However, only about 2% of silver was in the Ag(0) state, resulting in the high quality of nanocomposite films. The anodization treatment improves the bond strength between the Ag doped HAp deposited layers on TiO2. HAp and silver doped HAp (X=0.05) are regarded to be hydrophilic due to a large number of -OH groups on the surface. The sample with content of silver (x=0.05) also showed excellent antimicrobial efficacy (>99% reduction in viable cells). Electrochemical reveals the passive current densities of the HAp coated anodized Ti are lower than those of silver doped HAp coated anodized Ti, leading to a slightly lower corrosion resistance. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of a Li-Ion Nanobattery with Graphite Anode Using Molecular Dynamics Simulations

DOE PAGES

Ponce, Victor; Galvez-Aranda, Diego E.; Seminario, Jorge M.

2017-05-19

In this work, molecular dynamics simulations were performed of the initial charging of a Li-ion nanobattery with a graphite anode and lithium hexaflourphosphate (LiPF 6) salt dissolved in ethylene carbonate (CO 3C 2H 4) solvent as the electrolyte solution. The charging was achieved through the application of external electric fields simulating voltage sources. A variety of force fields were combined to simulate the materials of the nanobattery, including the solid electrolyte interphase, metal collectors, and insulator cover. Some of the force field parameters were estimated using ab initio methods and others were taken from the literature. We studied the behaviormore » of Li-ions traveling from cathode to anode through electrolyte solutions of concentrations 1.15 and 3.36 M. Time-dependent variables such as energy, temperature, volume, polarization, and mean square displacement are reported; a few of these variables, as well as others such as current, resistance, current density, conductivity, and resistivity are reported as a function of the external field and charging voltage. A solid electrolyte interphase (SEI) layer was also added to the model to study the mechanism behind the diffusion of the Li-ions through the SEI. As the battery is charged, the depletion of Li atoms in the cathode and their accumulation in the anode follow a linear increase of the polarizability in the solvent, until reaching a saturation point after which the charging of the battery stops, i.e., the energy provided by the external source decays to very low levels. Lastly, the nanobattery model containing the most common materials of a commercial lithium-ion battery is very useful to determine atomistic information that is difficult or too expensive to obtain experimentally; available data shows consistency with our results.« less

TaFROG encodes a Pooideae orphan protein that interacts with SnRK1 and enhances resistance to the mycotoxigenic fungus fusarium graminearum.

USDA-ARS?s Scientific Manuscript database

All genomes encode taxonomically restricted ‘orphan’ genes, most of which are of unknown function. We report the functional characterization of the orphan gene TaFROG as a component of the wheat resistance to the globally important Fusarium head blight (FHB) disease. TaFROG is taxonomically restrict...

Cathode readout with stripped resistive drift tubes

NASA Astrophysics Data System (ADS)

Bychkov, V. N.; Kekelidze, G. D.; Novikov, E. A.; Peshekhonov, V. D.; Shafranov, M. D.; Zhiltsov, V. E.

1994-11-01

A straw tube drift chamber prototype has been constructed and tested. The straw tube material is mylar film covered with carbon layer of resistivity 0.5, 30 and 70 k Ohm/sq. The gas mixture used was Ar/CH4. Both the anode wire and cathode signals were detected in order to study the behaviour of the chamber in the presence of X-ray ionization. The construction and the results of the study are presented.

Association of Antibiotic Resistance in Agricultural Escherichia coli Isolates with Attachment to Quartz▿

PubMed Central

Liu, Ping; Soupir, Michelle L.; Zwonitzer, Martha; Huss, Bridgette; Jarboe, Laura R.

2011-01-01

Surface water can be contaminated by bacteria from various sources, including manure from agricultural facilities. Attachment of these bacteria to soil and organic particles contributes to their transport through the environment, though the mechanism of attachment is unknown. As bacterial attachment to human tissues is known to be correlated with antibiotic resistance, we have investigated here the relationship between bacterial attachment to environmental particles and antibiotic resistance in agricultural isolates. We evaluated 203 Escherichia coli isolates collected from swine facilities for attachment to quartz, resistance to 13 antibiotics, and the presence of genes encoding 13 attachment factors. The genes encoding type I, EcpA, P pili, and Ag43 were detected, though none was significantly related to attachment. Quartz attachment was positively and significantly (P < 0.0038) related to combined resistance to amoxicillin/streptomycin/tetracycline/sulfamethazine/tylosin/chlortetracycline and negatively and significantly (P < 0.0038) related to combined resistance to nalidixic acid/kanamycin/neomycin. These results provide clear evidence for a link between antibiotic resistance and attachment to quartz in agricultural isolates. We propose that this may be due to encoding by the responsible genes on a mobile genetic element. Further exploration of the relationship between antibiotic resistance and attachment to environmental particles will improve the understanding and modeling of environmental transport processes, with the goal of preventing human exposure to antibiotic-resistant or virulent microorganisms. PMID:21821756

Association of antibiotic resistance in agricultural Escherichia coli isolates with attachment to quartz.

PubMed

Liu, Ping; Soupir, Michelle L; Zwonitzer, Martha; Huss, Bridgette; Jarboe, Laura R

2011-10-01

Surface water can be contaminated by bacteria from various sources, including manure from agricultural facilities. Attachment of these bacteria to soil and organic particles contributes to their transport through the environment, though the mechanism of attachment is unknown. As bacterial attachment to human tissues is known to be correlated with antibiotic resistance, we have investigated here the relationship between bacterial attachment to environmental particles and antibiotic resistance in agricultural isolates. We evaluated 203 Escherichia coli isolates collected from swine facilities for attachment to quartz, resistance to 13 antibiotics, and the presence of genes encoding 13 attachment factors. The genes encoding type I, EcpA, P pili, and Ag43 were detected, though none was significantly related to attachment. Quartz attachment was positively and significantly (P < 0.0038) related to combined resistance to amoxicillin/streptomycin/tetracycline/sulfamethazine/tylosin/chlortetracycline and negatively and significantly (P < 0.0038) related to combined resistance to nalidixic acid/kanamycin/neomycin. These results provide clear evidence for a link between antibiotic resistance and attachment to quartz in agricultural isolates. We propose that this may be due to encoding by the responsible genes on a mobile genetic element. Further exploration of the relationship between antibiotic resistance and attachment to environmental particles will improve the understanding and modeling of environmental transport processes, with the goal of preventing human exposure to antibiotic-resistant or virulent microorganisms.

Efflux pump-mediated benzalkonium chloride resistance in Listeria monocytogenes isolated from retail food.

PubMed

Jiang, Xiaobing; Yu, Tao; Liang, Yu; Ji, Shengdong; Guo, Xiaowei; Ma, Jianmin; Zhou, Lijun

2016-01-18

In this study, efflux pump-mediated benzalkonium chloride (BC) resistance, including plasmid-encoded (Qac protein family and BcrABC) and chromosome-borne efflux pumps, was investigated in Listeria monocytogenes from retail food in China. Among the 59 L. monocytogenes strains, 13 (22.0%) strains were resistant to BC. The PCR results showed that bcrABC was harbored by 2 of 13 BC resistant strains. However, none of the qac genes were detected among the 59 strains. The bcrABC was absent in both of the plasmid cured strains, indicating that this BC resistance determinant was plasmid-encoded in the two bcrABC-positive strains. In the presence of reserpine, most of the bcrABC-negative strains had decreases in the MICs of BC, suggesting the existence of other efflux pumps and their role in BC resistance. After exposed to reserpine, the reduction in BC MICs was observed in the two cured strains, indicating that efflux pumps located on chromosome was also involved in BC resistance. Our findings suggest that food products may act as reservoirs for BC resistant isolates of L. monocytogenes and plasmid- and chromosome-encoded efflux pumps could mediate the BC resistance of L. monocytogenes, which is especially relevant to the adaption of this organism in food-related environments with frequent BC use. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrogen sulfide-powered solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Liu, Man

2004-12-01

The potential utilization of hydrogen sulfide as fuel in solid oxide fuel cells has been investigated using an oxide-ion conducting YSZ electrolyte and different kinds of anode catalysts at operating temperatures in the range of 700--900°C and at atmospheric pressure. This technology offers an economically attractive alternative to present methods for removing toxic and corrosive H2S gas from sour gas streams and a promising approach for cogenerating electrical energy and useful chemicals. The primary objective of the present research was to find active and stable anode materials. Fuel cell experimental results showed that platinum was a good electrocatalyst for the conversion of H2S, but the Pt/YSZ interface was physically unstable due to the reversible formation and decomposition of PtS in H 2S streams at elevated temperatures. Moreover, instability of the Pt/YSZ interface was accelerated significantly by electrochemical reactions, and ultimately led to the detachment of the Pt anode from the electrolyte. It has been shown that an interlayer of TiO2 stabilized the Pt anode on YSZ electrolyte, thereby prolonging cell lifetime. However, the current output for a fuel cell using Pt/TiO2 as anode was not improved compared to using Pt alone. It was therefore necessary to investigate novel anode systems for H 2S-air SOFCs. New anode catalysts comprising composite metal sulfides were developed. These catalysts exhibited good electrical conductivity and better catalytic activity than Pt. In contrast to MoS2 alone, composite catalysts (M-Mo-S, M = Fe, Co, Ni) were not volatile and had superior stability. However, when used for extended periods of time, detachment of Pt current collecting film from anodes comprising metal sulfides alone resulted in a large increase in contact resistance and reduction in cell performance. Consequently, a systematic investigation was conducted to identify alternative electronic conductors for use with M-Mo-S catalysts. Anode catalysts comprising Co-Mo-S admixed with up to 10% Ag powder were found to have excellent performance and longevity, as well as improved electrical contact when compared with Pt/M-Mo-S anode systems. The highest current density of 450 mA/cm2 and power density of 115 mW/cm2 were achieved with an anode that consisted of 95% (Co-Mo-S) and 5% Ag.

A cometary ion mass spectrometer

NASA Technical Reports Server (NTRS)

Shelley, E. G.; Simpson, D. A.

1984-01-01

The development of flight suitable analyzer units for that part of the GIOTTO Ion Mass Spectrometer (IMS) experiment designated the High Energy Range Spectrometer (HERS) is discussed. Topics covered include: design of the total ion-optical system for the HERS analyzer; the preparation of the design of analyzing magnet; the evaluation of microchannel plate detectors and associated two-dimensional anode arrays; and the fabrication and evaluation of two flight-suitable units of the complete ion-optical analyzer system including two-dimensional imaging detectors and associated image encoding electronics.

Evidence-based guidelines on the therapeutic use of transcranial direct current stimulation (tDCS).

PubMed

Lefaucheur, Jean-Pascal; Antal, Andrea; Ayache, Samar S; Benninger, David H; Brunelin, Jérôme; Cogiamanian, Filippo; Cotelli, Maria; De Ridder, Dirk; Ferrucci, Roberta; Langguth, Berthold; Marangolo, Paola; Mylius, Veit; Nitsche, Michael A; Padberg, Frank; Palm, Ulrich; Poulet, Emmanuel; Priori, Alberto; Rossi, Simone; Schecklmann, Martin; Vanneste, Sven; Ziemann, Ulf; Garcia-Larrea, Luis; Paulus, Walter

2017-01-01

A group of European experts was commissioned by the European Chapter of the International Federation of Clinical Neurophysiology to gather knowledge about the state of the art of the therapeutic use of transcranial direct current stimulation (tDCS) from studies published up until September 2016, regarding pain, Parkinson's disease, other movement disorders, motor stroke, poststroke aphasia, multiple sclerosis, epilepsy, consciousness disorders, Alzheimer's disease, tinnitus, depression, schizophrenia, and craving/addiction. The evidence-based analysis included only studies based on repeated tDCS sessions with sham tDCS control procedure; 25 patients or more having received active treatment was required for Class I, while a lower number of 10-24 patients was accepted for Class II studies. Current evidence does not allow making any recommendation of Level A (definite efficacy) for any indication. Level B recommendation (probable efficacy) is proposed for: (i) anodal tDCS of the left primary motor cortex (M1) (with right orbitofrontal cathode) in fibromyalgia; (ii) anodal tDCS of the left dorsolateral prefrontal cortex (DLPFC) (with right orbitofrontal cathode) in major depressive episode without drug resistance; (iii) anodal tDCS of the right DLPFC (with left DLPFC cathode) in addiction/craving. Level C recommendation (possible efficacy) is proposed for anodal tDCS of the left M1 (or contralateral to pain side, with right orbitofrontal cathode) in chronic lower limb neuropathic pain secondary to spinal cord lesion. Conversely, Level B recommendation (probable inefficacy) is conferred on the absence of clinical effects of: (i) anodal tDCS of the left temporal cortex (with right orbitofrontal cathode) in tinnitus; (ii) anodal tDCS of the left DLPFC (with right orbitofrontal cathode) in drug-resistant major depressive episode. It remains to be clarified whether the probable or possible therapeutic effects of tDCS are clinically meaningful and how to optimally perform tDCS in a therapeutic setting. In addition, the easy management and low cost of tDCS devices allow at home use by the patient, but this might raise ethical and legal concerns with regard to potential misuse or overuse. We must be careful to avoid inappropriate applications of this technique by ensuring rigorous training of the professionals and education of the patients. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

A MEMS-enabled 3D zinc-air microbattery with improved discharge characteristics based on a multilayer metallic substructure

NASA Astrophysics Data System (ADS)

Armutlulu, A.; Fang, Y.; Kim, S. H.; Ji, C. H.; Bidstrup Allen, S. A.; Allen, M. G.

2011-10-01

This paper reports the design, fabrication and testing of a three-dimensional zinc-air microbattery with improved areal energy density and areal capacity, particularly at high discharge rates. The device is based on a multilayer, micron-scale, low-resistance metallic skeleton with an improved surface area. This skeleton consists of alternating Cu and Ni layers supporting Zn as electrodeposited anode electrode, and provides a high surface area, low-resistance path for electron transfer. A proof-of-concept zinc-air microbattery based on this technology was developed, characterized and compared with its two-dimensional thin-film counterparts fabricated on the same footprint area with equal amount of the Zn anode electrode. Using this approach, we were able to improve a single-layer initial structure with a surface area of 1.3 mm2 to a scaffold structure with ten layers having a surface area of 15 mm2. Discharging through load resistances ranging from 100 to 3000 Ω, the areal energy density and areal capacity of the microbattery were measured as 2.5-3 mWh cm-2 and ~2.5 mAh cm-2, respectively.

Electrochemical properties of 316L stainless steel with culturing L929 fibroblasts

PubMed Central

Hiromoto, Sachiko; Hanawa, Takao

2005-01-01

Potentiodynamic polarization and impedance tests were carried out on 316L stainless steel with culturing murine fibroblast L929 cells to elucidate the corrosion behaviour of 316L steel with L929 cells and to understand the electrochemical interface between 316L steel and cells, respectively. Potential step test was carried out on 316L steel with type I collagen coating and culturing L929 cells to compare the effects of collagen and L929 cells. The open-circuit potential of 316L steel slightly shifted in a negative manner and passive current density increased with cells, indicating a decrease in the protective ability of passive oxide film. The pitting potential decreased with cells, indicating a decrease in the pitting corrosion resistance. In addition, a decrease in diffusivity at the interface was indicated from the decrease in the cathodic current density and the increase in the diffusion resistance parameter in the impedance test. The anodic peak current in the potential step test decreased with cells and collagen. Consequently, the corrosion resistance of 316L steel decreases with L929 cells. In addition, collagen coating would provide an environment for anodic reaction similar to that with culturing cells. PMID:16849246

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galvez-Aranda, Diego E.; Ponce, Victor; Seminario, Jorge M.

Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ~3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. In this study, we performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery modelmore » during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li 14Si 5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. Also, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode.« less

On the nature of the Fe-bearing particles influencing hard anodizing behavior of AA 7075 extrusion products

NASA Astrophysics Data System (ADS)

Mukhopadhyay, A. K.

1998-03-01

The deleterious effects of Fe-bearing constituent particles on the fracture toughness of wrought A1 alloys have been known. Recent studies have shown that the presence of Fe-bearing, constituent particles is also determental to the nature and growth of the hard anodic oxide coating formed on such materials. The present study, using a combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron probe microanalysis (EPMA), was made to examine the influence of the nature of the Fe-bearing particles on the hard anodizing behavior of AA 7075 extrusion products containing varying amounts of Si, Mn, and Fe impurities. It was found that, in the alloy containing 0.25 wt pct Si, 0.27 wt pct Mn, and 0.25 wt pct Fe, the Fe-bearing constituent particles are based on the Al12(FeMn)3Si phase (bcc with α=1.260 nm). These particles survive the hard anodizing treatment, add resistance to the electrical path, causing a rapid rise in the bath voltage with time, and cause a nonuniform growth of the anodic oxide film. In the materials containing 0.05 wt pct Si, 0.04 wt pct Mn, and 0.18 wt pct Fe, on the other hand, the formation of the Al12(FeMn)3Si-based phase is suppressed, and two different Fe-bearing phases, based on Al-Fe-Cu-Mn-based (simple cubic with a=1.265 nm) and Al7Cu2Fe, respectively form. Neither the Al-Fe-Cu-Mn-based phase nor the Al7Cu2Fe-based phase survive the hard anodizing treatment, and this results in a steady rise in the bath voltage with time and a relatively uniform growth of the anodic oxide film. Consideration of the size of the Fe-bearing, particles reveals that the smaller the particle, the more uniform the growth of the anodic oxide film.

Using Copper Nanoparticle Additive to Improve the Performance of Silicon Anodes in Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Bachand, Gabrielle

In the foreseeable future, global energy demand is expected to rapidly increase as a result of the swelling population and higher standards of living. Current energy generation and transportation methods predominantly involve the combustion of non-renewable fossil fuels, and greenhouse gas emissions from these processes have been shown to contribute to global climate change and to be detrimental to human and environmental health. To satisfy future energy needs and to reduce greenhouse gas emissions, the advancement of renewable energy generation and electric vehicles is important. The proliferation of intermittent renewable energy sources (such as solar and wind) and electric vehicles depends upon reliable, high-capacity energy storage to serve the practical needs of society. The present-day lithium-ion battery offers excellent qualities for this purpose; however, improvements in the capacity and cost-effectiveness of these batteries are needed for further growth. As an anode material, silicon has exceptionally high theoretical capacity and is an earth-abundant, low-cost option. However, silicon also suffers from poor conductivity and long-term stability, prompting many studies to investigate the use of additive materials to mitigate these issues. This thesis focuses on the improvement of silicon anode performance by using a nanoparticulate copper additive to increase material conductivity and an inexpensive, industry-compatible anode fabrication process. Three main fabrication processes were explored using differing materials and heat treatment techniques for comparison. Anodes were tested using CR2032 type coin cells. The final anodes with the most-improved characteristics were fabricated using a high-temperature heating step for the anode material, and an additional batch was formed to test the viability of the copper additive functioning as a full substitute for carbon black, which is the traditional choice of conductive additive for electrode materials. Anodes materials were characterized using a variety of techniques including scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), inductively coupled plasma optical emission spectrometry (ICP-OES), Raman spectroscopy, and X-ray diffraction (XRD) to evaluate surface qualities and material content. Electrochemical techniques including electrochemical impedance spectroscopy (EIS) and charge/discharge cycling were also used to determine the conductivity and functional behavior of the anode materials. Anodes from the final experimental study achieved initial capacities of 309 mA/g and 957 mA/g for the silicon-only control and silicon with copper additive anodes, respectively, demonstrating an over 300% increase in specific capacity. Si-Cu (NC) anodes also showed superior performance over control anodes with an initial capacity of 775 mA/g. For all three anodes, high efficiencies of over 96% were achieved for the testing duration of 100 cycles and reached near or over 99% in final cycles. Results also show a significant decrease in the resistance of anodes with copper additive, contributing to the improved performance of these anodes.

Detection of different β-lactamases encoding genes, including blaNDM, and plasmid-mediated quinolone resistance genes in different water sources from Brazil.

PubMed

Sanchez, Danilo Garcia; de Melo, Fernanda Maciel; Savazzi, Eduardo Angelino; Stehling, Eliana Guedes

2018-06-16

Bacterial resistance occurs by spontaneous mutations or horizontal gene transfer mediated by mobile genetic elements, which represents a great concern. Resistance to β-lactam antibiotics is mainly due to the production of β-lactamases, and an important mechanism of fluoroquinolone resistance is the acquisition plasmid determinants. The aim of this study was to verify the presence of β-lactamase-encoding genes and plasmid-mediated quinolone resistance genes in different water samples obtained from São Paulo state, Brazil. A high level of these resistance genes was detected, being the bla SHV , bla GES , and qnr the most prevalent. Besides that, the bla NDM gene, which codify an important and hazardous metallo-β-lactamase, was detected.

Chemical passivation as a method of improving the electrochemical corrosion resistance of Co-Cr-based dental alloy.

PubMed

Rylska, Dorota; Sokołowski, Grzegorz; Sokołowski, Jerzy; Łukomska-Szymańska, Monika

2017-01-01

The purpose of the study was to evaluate corrosion resistance of Wirobond C® alloy after chemical passivation treatment. The alloy surface undergone chemical passivation treatment in four different media. Corrosion studies were carried out by means of electrochemical methods in saline solution. Corrosion effects were determined using SEM. The greatest increase in the alloy polarization resistance was observed for passive layer produced in Na2SO4 solution with graphite. The same layer caused the highest increase in corrosion current. Generally speaking, the alloy passivation in Na2SO4 solution with graphite caused a substantial improvement of the corrosion resistance. The sample after passivation in Na2SO4 solution without graphite, contrary to others, lost its protective properties along with successive anodic polarization cycles. The alloy passivation in Na3PO4 solution with graphite was the only one that caused a decrease in the alloy corrosion properties. The SEM studies of all samples after chemical passivation revealed no pit corrosion - in contrast to the sample without any modification. Every successive polarization cycle in anodic direction of pure Wirobond C® alloy enhances corrosion resistance shifting corrosion potential in the positive direction and decreasing corrosion current value. The chemical passivation in solutions with low pH values decreases susceptibility to electrochemical corrosion of Co-Cr dental alloy. The best protection against corrosion was obtained after chemical passivation of Wirobond C® in Na2SO4 solution with graphite. Passivation with Na2SO4 in solution of high pH does not cause an increase in corrosion resistance of WIROBOND C. Passivation process increases alloy resistance to pit corrosion.

Effects of hydraulic pressure on the performance of single chamber air-cathode microbial fuel cells.

PubMed

Cheng, Shaoan; Liu, Weifeng; Guo, Jian; Sun, Dan; Pan, Bin; Ye, Yaoli; Ding, Weijun; Huang, Haobin; Li, Fujian

2014-06-15

Scaling up of microbial fuel cells (MFCs) without losing power density requires a thorough understanding of the effect of hydraulic pressure on MFC performance. In this work, the performance of an activated carbon air-cathode MFC was evaluated under different hydraulic pressures. The MFC under 100 mmH2O hydraulic pressure produced a maximum power density of 1260 ± 24 mW m(-2), while the power density decreased by 24.4% and 44.7% as the hydraulic pressure increased to 500 mmH2O and 2000 mmH2O, respectively. Notably, the performance of both the anode and the cathode had decreased under high hydraulic pressures. Electrochemical impedance spectroscopy tests of the cathode indicated that both charge transfer resistance and diffusion transfer resistance increased with the increase in hydraulic pressure. Denaturing gradient gel electrophoresis of PCR-amplified partial 16S rRNA genes demonstrated that the similarity among anodic biofilm communities under different hydraulic pressures was ≥ 90%, and the communities of all MFCs were dominated by Geobacter sp. These results suggested that the reduction in power output of the single chamber air-cathode MFC under high hydraulic pressures can be attributed to water flooding of the cathode and suppression the metabolism of anodic exoelectrogenic bacteria. Copyright © 2014 Elsevier B.V. All rights reserved.

Finding the lost open-circuit voltage in polymer solar cells by UV-ozone treatment of the nickel acetate anode buffer layer.

PubMed

Wang, Fuzhi; Sun, Gang; Li, Cong; Liu, Jiyan; Hu, Siqian; Zheng, Hua; Tan, Zhan'ao; Li, Yongfang

2014-06-25

Efficient polymer solar cells (PSCs) with enhanced open-circuit voltage (Voc) are fabricated by introducing solution-processed and UV-ozone (UVO)-treated nickel acetate (O-NiAc) as an anode buffer layer. According to X-ray photoelectron spectroscopy data, NiAc partially decomposed to NiOOH during the UVO treatment. NiOOH is a dipole species, which leads to an increase in the work function (as confirmed by ultraviolet photoemission spectroscopy), thus benefitting the formation of ohmic contact between the anode and photoactive layer and leading to increased Voc. In addition, the UVO treatment improves the wettability between the substrate and solvent of the active layer, which facilitates the formation of an upper photoactive layer with better morphology. Further, the O-NiAc layer can decrease the series resistance (Rs) and increase the parallel resistance (Rp) of the devices, inducing enhanced Voc in comparison with the as-prepared NiAc-buffered control devices without UVO treatment. For PSCs based on the P3HT:PCBM system, Voc increases from 0.50 to 0.60 V after the NiAc buffer layer undergoes UVO treatment. Similarly, in the P3HT:ICBA system, the Voc value of the device with a UVO-treated NiAc buffer layer increases from 0.78 to 0.88 V, showing an enhanced power conversion efficiency of 6.64%.

Lithium rich cathode/graphite anode combination for lithium ion cells with high tolerance to near zero volt storage

NASA Astrophysics Data System (ADS)

Crompton, K. R.; Staub, J. W.; Hladky, M. P.; Landi, B. J.

2017-03-01

Management of reversible lithium is an advantageous approach to design lithium ion cells that are tolerant to near zero volt (NZV) storage under fixed resistive load towards highly controllable, enhanced user-inactive safety. Presently, the first cycle loss from a high energy density Li-rich HE5050 cathode is used to provide excess reversible lithium when paired with an appropriately capacity matched mesocarbon microbead (MCMB) anode. Cells utilizing 1.2 M LiPF6 3:7 v/v ethylene carbonate:ethyl methyl carbonate electrolyte and a lithium reference were used for 3-electrode testing. After conditioning, a fixed resistive load was applied to 3-electrode cells for 72 or 168-h during which the anode potential and electrode asymptotic potential (EAP) remained less than the copper dissolution potential. After multiple storage cycles (room temperature or 40 °C), the NZV coulombic efficiency (cell reversibility) exceeded 97% and the discharge capacity retention was >98%. Conventional 2-electrode HE5050/MCMB pouch cells stored at NZV or open circuit for 3 days had nearly identical rate capability (up to 5C) and discharge performance stability (for 500 cycles under a 30% depth of discharge low-earth-orbit regime). Thus, lithium ion cells with appropriately capacity matched HE5050/MCMB electrodes have excellent tolerance to prolonged NZV storage, which can lead to enhanced user-inactive safety.

Effect of samarium in corrosion and microstructure of Al-5Zn-0.5Cu as low driving voltage sacrificial anode

NASA Astrophysics Data System (ADS)

Pratesa, Yudha; Ferdian, Deni; Ramadhan, Fajar Yusya; Maulana, Bramuda

2018-05-01

Sacrificial Anode Low voltage is the latest generation of the sacrificial anode that can prevent the occurrence of Hydrogen Cracking (HIC) due to overprotection. The Al-5n-0.5Cu alloy showed the potential to be developed as the new sacrificial anode. However, the main problem is copper made Al2Cu intermetallic in grain boundary. Samarium is added to modify the shape of the intermetallic to make it finer and make the corrosion uniform. Several characterizations were conducted to analyze the effect of Samarium. Scanning electron microscope (SEM) and Energy dispersive spectroscopy was used to analyzed the microstructure of the alloy. Metallography preparation was prepared for SEM analysis. Corrosion behavior was characterized by cyclic polarization in 3.5% NaCl solution. The results show samarium can change the shape of intermetallic and refine the grains. In addition, samarium makes better pitting resistance and exhibits a tendency for uniform corrosion. It is indicated by the loop reduction (ΔEpit-prot). Current density increased as an effect of samarium addition from 6x10-5 Ampere (Al-5Zn-0.5Cu) to 2.5x10-4 Ampere (Al-5Zn-0.5Cu-0.5Sm). Steel potential protection increased after addition of samarium which is an indication the possibility of Al-Zn-Cu-Sm to be used as low voltage sacrificial anode.

Semi-transparent ordered TiO2 nanostructures prepared by anodization of titanium thin films deposited onto the FTO substrate

NASA Astrophysics Data System (ADS)

Szkoda, Mariusz; Lisowska-Oleksiak, Anna; Grochowska, Katarzyna; Skowroński, Łukasz; Karczewski, Jakub; Siuzdak, Katarzyna

2016-09-01

In a significant amount of cases, the highly ordered TiO2 nanotube arrays grow through anodic oxidation of a titanium metal plate immersed in electrolyte containing fluoride ions. However, for some practical applications, e.g. solar cells or electrochromic windows, the semi-transparent TiO2 formed directly on the transparent, conductive substrate is very much desired. This work shows that high-quality Ti coating could be formed at room temperature using an industrial magnetron sputtering system within 50 min. Under optimized conditions, the anodization process was performed on 2 μm titanium films deposited onto the FTO (fluorine-tin-oxide) support. Depending on the electrolyte type, highly ordered tubular or porous titania layers were obtained. The fabricated samples, after their thermal annealing, were investigated using scanning electron microscopy, Raman spectroscopy and UV-vis spectroscopy in order to investigate their morphology, crystallinity and absorbance ability. The photocurrent response curves indicate that materials are resistant to the photocorrosion process and their activity is strongly connected to optical properties. The most transparent TiO2 films were fabricated when Ti was anodized in water electrolyte, whereas the highest photocurrent densities (12 μA cm-2) were registered for titania received after Ti anodization in ethylene glycol solution. The obtained results are of significant importance in the production of thin, semi-transparent titania nanostructures on a commercial scale.

Preparation and characterization of anodic films on AZ31B Mg alloy formed in the silicate electrolytes with ethylene glycol oligomers as additives

NASA Astrophysics Data System (ADS)

Zhu, Feng; Wang, Jinwei; Li, Shanghua; Zhang, Jin

2012-09-01

Oxide coatings are prepared on AZ31B Mg alloy in an environment-friendly electrolyte with additives by plasma electrolytic anodization, and the effect of ethylene glycol oligmers on the performances of the anodized film is investigated. Under a constant current density of 10 mA cm-2, the reaction overpotential of the silicate electrolytes with additives are found higher than that of the original electrolyte as measured by potential-time test. The EIS and DC polarization results reveal that the addition of PEG increases the impedance of the film and reduces its corrosion current density (Icorr) at least by one order of magnitude. The surface morphologies are more and more compact and homogeneous with the increase in EG numbers, while a rougher surface appeared again if the PEG4000 is used as observed by SEM. As detected by XRD, the anodic films are found mainly consist of MgO, MgSiO3 and Mg2SiO4, and their relative amounts are related to the lengths of EGs, resulting in the differences in morphology and anticorrosion variations. Furthermore, the improvement in abrasive resistance of the anodic film formed in the electrolyte with PEG1000 may be attributed to its much more compact surface and the incorporation of ductile PEG chains among those oxides.

Two-dimensional ultraviolet imagery with a microchannel-plate/resistive-anode detector

NASA Technical Reports Server (NTRS)

Opal, C. B.; Feldman, P. D.; Weaver, H. A.; Mcclintock, J. A.

1979-01-01

An imaging ultraviolet detector has been designed for use with a precision pointed telescope flown on a sounding rocket. Resolution of better than 80 microns over a field of 5 mm has been achieved. The ultraviolet image is converted to electrons at the front surface of a CsI coated chevron microchannel-plate electron multiplier. For each photoelectron, the multiplier produces a burst of about 3,000,000 electrons, which impinges on a tellurium-coated resistive anode with four evaporated hyperbolic readout electrodes. The sizes of the four resulting output pulses are digitized to 10 bit accuracy and telemetered to the ground, where they are divided in pairs to give the x and y coordinates of the photoelectron event. The coordinates are used to generate a picture in real time, and are recorded for computer processing later. The detector was successfully flown in December 1978. Good images of Jupiter and Capella in hydrogen Lyman alpha emission were obtained.

Dual Electrolytic Plasma Processing for Steel Surface Cleaning and Passivation

NASA Astrophysics Data System (ADS)

Yang, L.; Zhang, P.; Shi, J.; Liang, J.; Tian, W. B.; Zhang, Y. M.; Sun, Z. M.

2017-10-01

To remove the rust on rebars and passivate the fresh surfaces, electrodes reversing electrolytic plasma processing (EPP) was proposed and conducted in a 10 wt.% Na2CO3 aqueous solution. The morphology and the composition of the surface were investigated by SEM and XPS. Experimental results show that the rust on the surface was removed effectively by cathode EPP, and a passive film containing Cr2O3 was achieved by the succeeding anode EPP treatment, by a simple operation of reversing the bias. The corrosion resistance was evaluated in a 3.5 wt.% NaCl aqueous solution using an electrochemical workstation. In comparison, the corrosion resistance was improved by the succeeding anode EPP treatment, which is evidenced by a positive shift of the open-circuit potential, an increase in the electrochemical impedance representing the inner layer by 76.8% and the decrease in the corrosion current density by 49.6%. This is an effective and environment-friendly technique to clean and passivate rebars and similar steel materials.

A lithotrophic microbial fuel cell operated with pseudomonads-dominated iron-oxidizing bacteria enriched at the anode

PubMed Central

Nguyen, Thuy Thu; Luong, Tha Thanh Thi; Tran, Phuong Hoang Nguyen; Bui, Ha Thi Viet; Nguyen, Huy Quang; Dinh, Hang Thuy; Kim, Byung Hong; Pham, Hai The

2015-01-01

In this study, we attempted to enrich neutrophilic iron bacteria in a microbial fuel cell (MFC)-type reactor in order to develop a lithotrophic MFC system that can utilize ferrous iron as an inorganic electron donor and operate at neutral pHs. Electrical currents were steadily generated at an average level of 0.6 mA (or 0.024 mA cm–2 of membrane area) in reactors initially inoculated with microbial sources and operated with 20 mM Fe2+ as the sole electron donor and 10 ohm external resistance; whereas in an uninoculated reactor (the control), the average current level only reached 0.2 mA (or 0.008 mA cm–2 of membrane area). In an inoculated MFC, the generation of electrical currents was correlated with increases in cell density of bacteria in the anode suspension and coupled with the oxidation of ferrous iron. Cultivation-based and denaturing gradient gel electrophoresis analyses both show the dominance of some Pseudomonas species in the anode communities of the MFCs. Fluorescent in-situ hybridization results revealed significant increases of neutrophilic iron-oxidizing bacteria in the anode community of an inoculated MFC. The results, altogether, prove the successful development of a lithotrophic MFC system with iron bacteria enriched at its anode and suggest a chemolithotrophic anode reaction involving some Pseudomonas species as key players in such a system. The system potentially offers unique applications, such as accelerated bioremediation or on-site biodetection of iron and/or manganese in water samples. PMID:25712332

A three-mask process for fabricating vacuum-sealed capacitive micromachined ultrasonic transducers using anodic bonding.

PubMed

Yamaner, F Yalçın; Zhang, Xiao; Oralkan, Ömer

2015-05-01

This paper introduces a simplified fabrication method for vacuum-sealed capacitive micromachined ultrasonic transducer (CMUT) arrays using anodic bonding. Anodic bonding provides the established advantages of wafer-bondingbased CMUT fabrication processes, including process simplicity, control over plate thickness and properties, high fill factor, and ability to implement large vibrating cells. In addition to these, compared with fusion bonding, anodic bonding can be performed at lower processing temperatures, i.e., 350°C as opposed to 1100°C; surface roughness requirement for anodic bonding is more than 10 times more relaxed, i.e., 5-nm rootmean- square (RMS) roughness as opposed to 0.5 nm for fusion bonding; anodic bonding can be performed on smaller contact area and hence improves the fill factor for CMUTs. Although anodic bonding has been previously used for CMUT fabrication, a CMUT with a vacuum cavity could not have been achieved, mainly because gas is trapped inside the cavities during anodic bonding. In the approach we present in this paper, the vacuum cavity is achieved by opening a channel in the plate structure to evacuate the trapped gas and subsequently sealing this channel by conformal silicon nitride deposition in the vacuum environment. The plate structure of the fabricated CMUT consists of the single-crystal silicon device layer of a silicon-on-insulator wafer and a thin silicon nitride insulation layer. The presented fabrication approach employs only three photolithographic steps and combines the advantages of anodic bonding with the advantages of a patterned metal bottom electrode on an insulating substrate, specifically low parasitic series resistance and low parasitic shunt capacitance. In this paper, the developed fabrication scheme is described in detail, including process recipes. The fabricated transducers are characterized using electrical input impedance measurements in air and hydrophone measurements in immersion. A representative design is used to demonstrate immersion operation in conventional, collapse-snapback, and collapse modes. In collapsemode operation, an output pressure of 1.67 MPa pp is shown at 7 MHz on the surface of the transducer for 60-Vpp, 3-cycle sinusoidal excitation at 30-V dc bias.

Application of infiltrated LSCM-GDC oxide anode in direct carbon/coal fuel cells.

PubMed

Yue, Xiangling; Arenillas, Ana; Irvine, John T S

2016-08-15

Hybrid direct carbon/coal fuel cells (HDCFCs) utilise an anode based upon a molten carbonate salt with an oxide conducting solid electrolyte for direct carbon/coal conversion. They can be fuelled by a wide range of carbon sources, and offer higher potential chemical to electrical energy conversion efficiency and have the potential to decrease CO2 emissions compared to coal-fired power plants. In this study, the application of (La, Sr)(Cr, Mn)O3 (LSCM) and (Gd, Ce)O2 (GDC) oxide anodes was explored in a HDCFC system running with two different carbon fuels, an organic xerogel and a raw bituminous coal. The electrochemical performance of the HDCFC based on a 1-2 mm thick 8 mol% yttria stabilised zirconia (YSZ) electrolyte and the GDC-LSCM anode fabricated by wet impregnation procedures was characterized and discussed. The infiltrated oxide anode showed a significantly higher performance than the conventional Ni-YSZ anode, without suffering from impurity formation under HDCFC operation conditions. Total polarisation resistance (Rp) reached 0.8-0.9 Ω cm(2) from DCFC with an oxide anode on xerogel and bituminous coal at 750 °C, with open circuit voltage (OCV) values in the range 1.1-1.2 V on both carbon forms. These indicated the potential application of LSCM-GDC oxide anode in HDCFCs. The chemical compatibility of LSCM/GDC with carbon/carbonate investigation revealed the emergence of an A2BO4 type oxide in place of an ABO3 perovskite structure in the LSCM in a reducing environment, due to Li attack as a result of intimate contact between the LSCM and Li2CO3, with GDC being stable under identical conditions. Such reaction between LSCM and Li2CO3 was not observed on a LSCM-YSZ pellet treated with Li-K carbonate in 5% H2/Ar at 700 °C, nor on a GDC-LSCM anode after HDCFC operation. The HDCFC durability tests of GDC-LSCM oxide on a xerogel and on raw bituminous coal were performed under potentiostatic operation at 0.7 V at 750 °C. The degradation mechanisms were addressed, especially on raw coal.

Multidrug resistance in fungi: regulation of transporter-encoding gene expression

PubMed Central

Paul, Sanjoy; Moye-Rowley, W. Scott

2014-01-01

A critical risk to the continued success of antifungal chemotherapy is the acquisition of resistance; a risk exacerbated by the few classes of effective antifungal drugs. Predictably, as the use of these drugs increases in the clinic, more resistant organisms can be isolated from patients. A particularly problematic form of drug resistance that routinely emerges in the major fungal pathogens is known as multidrug resistance. Multidrug resistance refers to the simultaneous acquisition of tolerance to a range of drugs via a limited or even single genetic change. This review will focus on recent progress in understanding pathways of multidrug resistance in fungi including those of most medical relevance. Analyses of multidrug resistance in Saccharomyces cerevisiae have provided the most detailed outline of multidrug resistance in a eukaryotic microorganism. Multidrug resistant isolates of S. cerevisiae typically result from changes in the activity of a pair of related transcription factors that in turn elicit overproduction of several target genes. Chief among these is the ATP-binding cassette (ABC)-encoding gene PDR5. Interestingly, in the medically important Candida species, very similar pathways are involved in acquisition of multidrug resistance. In both C. albicans and C. glabrata, changes in the activity of transcriptional activator proteins elicits overproduction of a protein closely related to S. cerevisiae Pdr5 called Cdr1. The major filamentous fungal pathogen, Aspergillus fumigatus, was previously thought to acquire resistance to azole compounds (the principal antifungal drug class) via alterations in the azole drug target-encoding gene cyp51A. More recent data indicate that pathways in addition to changes in the cyp51A gene are important determinants in A. fumigatus azole resistance. We will discuss findings that suggest azole resistance in A. fumigatus and Candida species may share more mechanistic similarities than previously thought. PMID:24795641

Nanocarbon-Coated Porous Anodic Alumina for Bionic Devices

PubMed Central

Aramesh, Morteza; Tong, Wei; Fox, Kate; Turnley, Ann; Seo, Dong Han; Prawer, Steven; Ostrikov, Kostya (Ken)

2015-01-01

A highly-stable and biocompatible nanoporous electrode is demonstrated herein. The electrode is based on a porous anodic alumina which is conformally coated with an ultra-thin layer of diamond-like carbon. The nanocarbon coating plays an essential role for the chemical stability and biocompatibility of the electrodes; thus, the coated electrodes are ideally suited for biomedical applications. The corrosion resistance of the proposed electrodes was tested under extreme chemical conditions, such as in boiling acidic/alkali environments. The nanostructured morphology and the surface chemistry of the electrodes were maintained after wet/dry chemical corrosion tests. The non-cytotoxicity of the electrodes was tested by standard toxicity tests using mouse fibroblasts and cortical neurons. Furthermore, the cell–electrode interaction of cortical neurons with nanocarbon coated nanoporous anodic alumina was studied in vitro. Cortical neurons were found to attach and spread to the nanocarbon coated electrodes without using additional biomolecules, whilst no cell attachment was observed on the surface of the bare anodic alumina. Neurite growth appeared to be sensitive to nanotopographical features of the electrodes. The proposed electrodes show a great promise for practical applications such as retinal prostheses and bionic implants in general. PMID:28793486

Length-dependent corrosion behavior, Ni2+ release, cytocompatibility, and antibacterial ability of Ni-Ti-O nanopores anodically grown on biomedical NiTi alloy.

PubMed

Hang, Ruiqiang; Liu, Yanlian; Bai, Long; Zhang, Xiangyu; Huang, Xiaobo; Jia, Husheng; Tang, Bin

2018-08-01

In the present work, nickel-titanium-oxygen nanopores with different length (0.55-114 μm) were anodically grown on nearly equiatomic nickel-titanium (NiTi) alloy. Length-dependent corrosion behavior, nickel ion (Ni 2+ ) release, cytocompatibility, and antibacterial ability were investigated by electrochemical, analytical chemistry, and biological methods. The results show constructing nanoporous structure on the NiTi alloy improve its corrosion resistance. However, the anodized samples release more Ni 2+ than that of the bare NiTi alloy, suggesting chemical dissolution of the nanopores rather than electrochemical corrosion governs the Ni 2+ release. In addition, the Ni 2+ release amount increases with nanopore length. The anodized samples show good cytocompatibility when the nanopore length is <11 μm. Encouragingly, the length scale covers the one (1-11 μm) that the nanopores showing favorable antibacterial ability. Consequently, the nanopores with length in the range of 1-11 μm are promising as coatings of biomedical NiTi alloy for anti-infection, drug delivery, and other desirable applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of Oxide Film on the Corrosion Resistance of Titanium Grade 7 in Fluoride-Containing NaCl Brines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lian, T; Whalen, M T; Wong, L

2004-11-30

The effects of oxide film on the corrosion behavior of Titanium Grade 7 (0.12-0.25% Pd) in fluoride-containing NaCl brines have been investigated. With the presence of a 0.6 {micro}m thick oxide layer, the annealed Ti grade 7 exhibited a significant improvement on the anodic polarization behavior. However, the oxide film did not demonstrate sustainable corrosion resistance in fluoride-containing solutions.

A study of Staphylococcus aureusnasal carriage, antibacterial resistance and virulence factor encoding genes in a tertiary care hospital, Kayseri, Turkey.

PubMed

Oguzkaya-Artan, M; Artan, C; Baykan, Z; Sakalar, C; Turan, A; Aksu, H

2015-01-01

This study was to determine the virulence encoding genes, and the antibiotic resistance patterns of the Staphylococcus aureus isolates, which were isolated from the nasal samples of chest clinic patients. The nasal samples of the in-patients (431) and out-patients (1857) in Kayseri Training and Research Hospital's Chest Clinic, Kayseri, Turkey, were cultured on CHROMagar (Biolife, Italiana) S. aureus, and subcultured on sheep blood agar for the isolation of S. aureus. Disc diffusion method was used for antimicrobial susceptibility testing. The occurrence of the staphylococcal virulence encoding genes (enterotoksins [sea, seb, sec, see, seg, seh, sei, sej], fibronectin-binding proteins A, B [fnbA, fnbB], toxic shock syndrome toxin-1 [tst]) were detected by polymerase chain reaction. Forty-five of the 55 (81.8%) S. aureus isolates from inpatients, and 319 (90.6%) isolates from tested 352 out-patient's isolates were suspected to all the antibiotics tested. methicillin-resistant S. aureus (MRSA) was detected in 1.2% of S. aureus isolates. Rifampin, trimethoprim-sulfamethoxazole, clindamycin, erythromycin, gentamicin resistance rates were 1.2%, 1.7%, 2.0%, 8.8%, and 1.2%, respectively. The isolates were susceptible to teicoplanin and vancomycin. The genes most frequently found were tst (92.7%), seg (85.8%), sea (83.6%), fnbA (70.9%). There was no statistical significance detected between MRSA and mecA-negative S. aureus isolates in encoding genes distribution (P > 0.05). Our results show that virulence factor encoding genes were prevalent in patients with S. aureus carriage, whereas antibiotic resistance was low. These virulence determinants may increase the risk for subsequent invasive infections in carriers.

The effect of antimicrobial photodynamic therapy on the expression of novel methicillin resistance markers determined using cDNA-AFLP approach in Staphylococcus aureus.

PubMed

Hoorijani, Mohammad Neshvan; Rostami, Hosein; Pourhajibagher, Maryam; Chiniforush, Nasim; Heidari, Mansour; Pourakbari, Babak; Kazemian, Hossein; Davari, Kambiz; Amini, Vahid; Raoofian, Reza; Bahador, Abbas

2017-09-01

Widespread methicillin resistant Staphylococcus aureus (MRSA) and absence of effective antimicrobial agents has led to limited therapeutic options for treating MRSA infection. We aimed to evaluate the effect of antimicrobial photodynamic therapy (aPDT) on the expression of novel identified methicillin resistance markers (NIMRMs) in S. aureus using complementary DNA-Amplified Fragment Length Polymorphism (cDNA-AFLP) approaches to address the therapeutic alternatives for MRSA infections. We used cDNA-AFLP to compare MRSA and methicillin susceptible S. aureus (MSSA) for identification of target genes implicated in methicillin resistance. To determine the sub-lethal aPDT (sPDT), MRSA and MSSA clinical isolates photosensitized with toluidine blue O (TBO), and then were irradiated with diode laser. After sPDT, the colony forming units/mL was quantified. Antimicrobial susceptibility against methicillin was assessed for cell-surviving aPDT. Effects of sPDT on the expression of NIMRMs were evaluated by real-time quantitative reverse transcription PCR. According to our results, serine hydrolase family protein (Shfp) encoding gene and a gene encoding a conserved hypothetical protein (Chp) were implicated in methicillin resistance in MRSA. sPDT reduced the minimum inhibitory concentrations of methicillin by 3-fold in MRSA. sPDT could lead to about 10- and 6.2- fold suppression of expression of the Chp and Shfp encoding genes, respectively. sPDT would lead to reduction in resistance to methicillin of MRSA in surviving cells by suppressing the expression of the Shfp and Chp encoding genes associated with methicillin resistance. This may have potential implications of aPDT for the treatment of MRSA infections. Copyright © 2017 Elsevier B.V. All rights reserved.

Novel plasmids and resistance phenotypes in Yersinia pestis: unique plasmid inventory of strain Java 9 mediates high levels of arsenic resistance.

PubMed

Eppinger, Mark; Radnedge, Lyndsay; Andersen, Gary; Vietri, Nicholas; Severson, Grant; Mou, Sherry; Ravel, Jacques; Worsham, Patricia L

2012-01-01

Growing evidence suggests that the plasmid repertoire of Yersinia pestis is not restricted to the three classical virulence plasmids. The Java 9 strain of Y. pestis is a biovar Orientalis isolate obtained from a rat in Indonesia. Although it lacks the Y. pestis-specific plasmid pMT, which encodes the F1 capsule, it retains virulence in mouse and non-human primate animal models. While comparing diverse Y. pestis strains using subtractive hybridization, we identified sequences in Java 9 that were homologous to a Y. enterocolitica strain carrying the transposon Tn2502, which is known to encode arsenic resistance. Here we demonstrate that Java 9 exhibits high levels of arsenic and arsenite resistance mediated by a novel promiscuous class II transposon, named Tn2503. Arsenic resistance was self-transmissible from Java 9 to other Y. pestis strains via conjugation. Genomic analysis of the atypical plasmid inventory of Java 9 identified pCD and pPCP plasmids of atypical size and two previously uncharacterized cryptic plasmids. Unlike the Tn2502-mediated arsenic resistance encoded on the Y. enterocolitica virulence plasmid; the resistance loci in Java 9 are found on all four indigenous plasmids, including the two novel cryptic plasmids. This unique mobilome introduces more than 105 genes into the species gene pool. The majority of these are encoded by the two entirely novel self-transmissible plasmids, which show partial homology and synteny to other enterics. In contrast to the reductive evolution in Y. pestis, this study underlines the major impact of a dynamic mobilome and lateral acquisition in the genome evolution of the plague bacterium.

Novel Plasmids and Resistance Phenotypes in Yersinia pestis: Unique Plasmid Inventory of Strain Java 9 Mediates High Levels of Arsenic Resistance

PubMed Central

Eppinger, Mark; Radnedge, Lyndsay; Andersen, Gary; Vietri, Nicholas; Severson, Grant; Mou, Sherry; Ravel, Jacques; Worsham, Patricia L.

2012-01-01

Growing evidence suggests that the plasmid repertoire of Yersinia pestis is not restricted to the three classical virulence plasmids. The Java 9 strain of Y. pestis is a biovar Orientalis isolate obtained from a rat in Indonesia. Although it lacks the Y. pestis-specific plasmid pMT, which encodes the F1 capsule, it retains virulence in mouse and non-human primate animal models. While comparing diverse Y. pestis strains using subtractive hybridization, we identified sequences in Java 9 that were homologous to a Y. enterocolitica strain carrying the transposon Tn2502, which is known to encode arsenic resistance. Here we demonstrate that Java 9 exhibits high levels of arsenic and arsenite resistance mediated by a novel promiscuous class II transposon, named Tn2503. Arsenic resistance was self-transmissible from Java 9 to other Y. pestis strains via conjugation. Genomic analysis of the atypical plasmid inventory of Java 9 identified pCD and pPCP plasmids of atypical size and two previously uncharacterized cryptic plasmids. Unlike the Tn2502-mediated arsenic resistance encoded on the Y. enterocolitica virulence plasmid; the resistance loci in Java 9 are found on all four indigenous plasmids, including the two novel cryptic plasmids. This unique mobilome introduces more than 105 genes into the species gene pool. The majority of these are encoded by the two entirely novel self-transmissible plasmids, which show partial homology and synteny to other enterics. In contrast to the reductive evolution in Y. pestis, this study underlines the major impact of a dynamic mobilome and lateral acquisition in the genome evolution of the plague bacterium. PMID:22479347

Molecular Characterization of Plasmid-Mediated Oxytetracycline Resistance in Aeromonas salmonicida

PubMed Central

Adams, C. A.; Austin, B.; Meaden, P. G.; McIntosh, D.

1998-01-01

Using broth conjugation, we found that 19 of 29 (66%) oxytetracycline (OT)-resistant isolates of Aeromonas salmonicida transferred the OT resistance phenotype to Escherichia coli. The OT resistance phenotype was encoded by high-molecular-weight R-plasmids that were capable of transferring OT resistance to both environmental and clinical isolates of Aeromonas spp. The molecular basis for antibiotic resistance in OT-resistant isolates of A. salmonicida was determined. The OT resistance determinant from one plasmid (pASOT) of A. salmonicida was cloned and used in Southern blotting and hybridization experiments as a probe. The determinant was identified on a 5.4-kb EcoRI fragment on R-plasmids from the 19 OT-resistant isolates of A. salmonicida. Hybridization with plasmids encoding the five classes (classes A to E) of OT resistance determinants demonstrated that the OT resistance plasmids of the 19 A. salmonicida isolates carried the class A resistance determinant. Analysis of data generated from restriction enzyme digests showed that the OT resistance plasmids were not identical; three profiles were characterized, two of which showed a high degree of homology. PMID:9797265

DNA Gyrase Is the Target for the Quinolone Drug Ciprofloxacin in Arabidopsis thaliana.

PubMed

Evans-Roberts, Katherine M; Mitchenall, Lesley A; Wall, Melisa K; Leroux, Julie; Mylne, Joshua S; Maxwell, Anthony

2016-02-12

The Arabidopsis thaliana genome contains four genes that were originally annotated as potentially encoding DNA gyrase: ATGYRA, ATGYRB1, ATGYRB2, and ATGYRB3. Although we subsequently showed that ATGYRB3 does not encode a gyrase subunit, the other three genes potentially encode subunits of a plant gyrase. We also showed evidence for the existence of supercoiling activity in A. thaliana and that the plant is sensitive to quinolone and aminocoumarin antibiotics, compounds that target DNA gyrase in bacteria. However, it was not possible at that time to show whether the A. thaliana genes encoded an active gyrase enzyme, nor whether that enzyme is indeed the target for the quinolone and aminocoumarin antibiotics. Here we show that an A. thaliana mutant resistant to the quinolone drug ciprofloxacin has a point mutation in ATGYRA. Moreover we show that, as in bacteria, the quinolone-sensitive (wild-type) allele is dominant to the resistant gene. Further we have heterologously expressed ATGYRA and ATGYRB2 in a baculovirus expression system and shown supercoiling activity of the partially purified enzyme. Expression/purification of the quinolone-resistant A. thaliana gyrase yields active enzyme that is resistant to ciprofloxacin. Taken together these experiments now show unequivocally that A. thaliana encodes an organelle-targeted DNA gyrase that is the target of the quinolone drug ciprofloxacin; this has important consequences for plant physiology and the development of herbicides. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Positive magnetoresistance in Fe3Se4 nanowires

NASA Astrophysics Data System (ADS)

Li, D.; Jiang, J. J.; Liu, W.; Zhang, Z. D.

2011-04-01

We report the magnetotransport properties of Fe3Se4 nanowire arrays in anodic aluminum oxide (AAO) porous membrane. The temperature dependence of resistance of Fe3Se4 nanowires at a zero field shows thermal activated behavior below 295 K. The exponential relationship in resistance is consistent with the model of strong localization with variable-range hopping (VRH) for a finite one-dimensional wire. Resistance versus magnetic field curves below 100 K show small positive magnetoresistance (MR). The field dependencies of log[R(H)/R(0)] explain the positive MR as the effect of magnetic field on the VRH conduction.

Evidence for thermal boundary resistance effects on superconducting radiofrequency cavity performances

NASA Astrophysics Data System (ADS)

Palmieri, Vincenzo; Rossi, Antonio Alessandro; Stark, Sergey Yu; Vaglio, Ruggero

2014-08-01

The majority of the literature on superconducting cavities for particle accelerators concentrates on the interaction of a radiofrequency (RF) electromagnetic field with a superconductor cooled in liquid helium, generally either at a fixed temperature of 4.2 K or 1.8 K, basing the analysis of experimental results on the assumption that the superconductor is at the same temperature as the infinite reservoir of liquid helium. Only a limited number of papers have extended their analysis to the more complex overall system composed of an RF field, a superconductor and liquid helium. Only a few papers have analyzed, for example, the problem of the Kapitza resistance, i.e. the thermal boundary resistance between the superconductor and the superfluid helium. Among them, the general conclusion is that the Kapitza resistance, one of the most controversial and less understood topics in physics, is generally negligible, or not relevant for the performance enhancement of cavities. In our work presented here, studying the performance of 6 GHz niobium (Nb) test cavities, we have discovered and studied a new effect consisting of an abrupt change in the surface resistance versus temperature at the superfluid helium lambda transition Tλ. This abrupt change (or ‘jump’) clearly appears when the RF measurement of a cavity is performed at constant power rather than at a constant field. We have correlated this jump to a change in the thermal exchange regime across the lambda transition, and, through a simple thermal model and further reasonable assumptions, we have calculated the thermal boundary resistance between niobium and liquid helium in the temperature range between 4.2 K and 1.8 K. We find that the absolute values of the thermal resistance both above and below the lambda point are fully compatible with the data reported in the literature for heat transfer to pool boiling helium I (HeI) above Tλ and for the Kapitza interface resistance (below Tλ) between a polished metal surface and superfluid HeII. Finally, based on the well-documented evidence that the surface status of metal to liquid helium influences the heat exchange towards the fluid, and specifically the Kapitza resistance below Tλ, we have tested an anodization process external to the cavity, comparing the performances of the cavity before and after external anodization. The tests were done without breaking the vacuum inside the cavity or modifying the inner superconducting layer in any way, and were repeated on different samples. The results show that when the cavity is externally anodized, both the Q-factor and the maximum accelerating field increase. Again, when the oxide layer is removed, the Q-factor shifts towards a lower level and the maximum accelerating field is also reduced.

Utilization of natural and supplemental biofuels for harvesting energy from marine sediments

NASA Astrophysics Data System (ADS)

Nielsen, Mark E.

A benthic microbial fuel cell (BMFC) is an electrochemical device that generates current from the redox gradient at the sediment-water interface. Early prototypes had anodes buried in anoxic sediments and cathodes in overlying water. The BMFCs described in this dissertation are based on a chamber design that enables the use of high surface-area fiber electrodes and facilitates enhanced mass transport to the anode. Results from Yaquina Bay, OR, show that mass transport resistance accounted for at least 93% of the total internal resistance for a particular BMFC configuration. Power output was increased 18-fold by mechanically induced fluid transport through the anode chamber. At a cold seep in Monterey Canyon, CA, naturally driven advection resulted in a five-fold increase in power from a BMFC with low-pressure check valves relative to an identical BMFC with high-pressure check valves. Enhanced transport coincided with a change in the microbial community on the anode from one dominated by epsilonproteobacteria to one with relatively even representation from deltaproteobacteria, epsilonproteobacteria, firmicutes and flavobacterium/cytophaga/bacterioides. Laboratory experiments investigated the effect of adding supplemental carbon sources to anode chambers. Repeated lactate injections appeared to stimulate sulfate reduction resulting in short term power gains but did not apparently shift the process responsible for baseline current. When a specific inhibitor of sulfate reduction was added, lactate-supplemented and unsupplemented BMFCs performed similarly. BMFCs have been proposed as power sources for monitoring systems in remote locations. Practical implementation of this technology is governed by three conditions: (1) low-voltage current must be stepped up to meet the requirements of off-the-shelf electronic devices, (2) modest power production and variable power demands require integrated energy storage, and (3) BMFCs should be operated at the most efficient potential for energy production. A combination power converter/potentiostat/rechargeable battery system was described based on these considerations and tested with a chambered BMFC in Yaquina Bay, OR. The BMFC provided intermittent power to an acoustic receiver, and results highlight the need to increase power, make design improvements to better seal the chamber to the sediment and increase the capacity for energy storage.

RNA interference of three up-regulated transcripts associated with insecticide resistance in an imidacloprid resistant population of Leptinotarsa decemlineata.

PubMed

Clements, Justin; Schoville, Sean; Peterson, Nathan; Huseth, Anders S; Lan, Que; Groves, Russell L

2017-01-01

The Colorado potato beetle, Leptinotarsa decemlineata (Say), is a major agricultural pest of potatoes in the Central Sands production region of Wisconsin. Previous studies have shown that populations of L. decemlineata have become resistant to many classes of insecticides, including the neonicotinoid insecticide, imidacloprid. Furthermore, L. decemlineata has multiple mechanisms of resistance to deal with a pesticide insult, including enhanced metabolic detoxification by cytochrome p450s and glutathione S-transferases. With recent advances in the transcriptomic analysis of imidacloprid susceptible and resistant L. decemlineata populations, it is possible to investigate the role of candidate genes involved in imidacloprid resistance. A recently annotated transcriptome analysis of L. decemlineata was obtained from select populations of L. decemlineata collected in the Central Sands potato production region, which revealed a subset of mRNA transcripts constitutively up-regulated in resistant populations. We hypothesize that a portion of the up-regulated transcripts encoding for genes within the resistant populations also encode for pesticide resistance and can be suppressed to re-establish a susceptible phenotype. In this study, a discrete set of three up-regulated targets were selected for RNA interference experiments using a resistant L. decemlineata population. Following the successful suppression of transcripts encoding for a cytochrome p450, a cuticular protein, and a glutathione synthetase protein in a select L. decemlineata population, we observed reductions in measured resistance to imidacloprid that strongly suggest these genes control essential steps in imidacloprid metabolism in these field populations. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

An encoding readout method used for Multi-gap Resistive Plate Chambers (MRPCs) for muon tomography

NASA Astrophysics Data System (ADS)

Yue, X.; Zeng, M.; Wang, Y.; Wang, X.; Zeng, Z.; Zhao, Z.; Cheng, J.

2014-09-01

A muon tomography facility has been built in Tsinghua University. Because of the low flux of cosmic muon, an encoding readout method, based on the fine-fine configuration, was implemented for the 2880 channels induced signals from the Multi-gap Resistive Plate Chamber (MRPC) detectors. With the encoding method, the number of the readout electronics was dramatically reduced and thus the complexity and the cost of the facility was reduced, too. In this paper, the details of the encoding method, and the overall readout system setup in the muon tomography facility are described. With the commissioning of the facility, the readout method works well. The spatial resolution of all MRPC detectors are measured with cosmic muon and the preliminary imaging result are also given.

A large 2D PSD for thermal neutron detection

NASA Astrophysics Data System (ADS)

Knott, R. B.; Smith, G. C.; Watt, G.; Boldeman, J. W.

1997-02-01

A 2D PSD based on a MWPC has been constructed for a small angle neutron scattering instrument. The active area of the detector was 640 × 640 mm 2. To meet the specifications for neutron detection efficiency and spatial resolution, and to minimise parallax, the gas mixture was 190 kPa 3He plus 100 kPa CF 4, and the active volume had a thickness of 30 mm. The design maximum neutron count rate of the detector was 10 5 events per secod. The (calculated) neutron detection efficiency was 60% for 2 Å neutrons and the (measured) neutron energy resolution on the anode grid was typically 20% (fwhm). The location of a neutron detection event within the active area was determined using the wire-by-wire method: the spatial resolution (5 × 5 mm 2) was thereby defined by the wire geometry. A 16-channel charge-sensitive preamplifier/amplifier/comparator module has been developed with a channel sensitivity of 0.1 V/fC, noise line width of 0.4 fC (fwhm) and channel-to-channel cross-talk of less than 5%. The Proportional Counter Operating System (PCOS III) (LeCroy Corp, USA) was used for event encoding. The ECL signals produced by the 16 channel modules were latched in PCOS III by a trigger pulse from the anode and the fast encoders produce a position and width for each event. The information was transferred to a UNIX workstation for accumulation and online display.

Encoding Strategies in Primary School Children: Insights from an Eye-Tracking Approach and the Role of Individual Differences in Attentional Control

ERIC Educational Resources Information Center

Roebers, Claudia M.; Schmid, Corinne; Roderer, Thomas

2010-01-01

The authors explored different aspects of encoding strategy use in primary school children by including (a) an encoding strategy task in which children's encoding strategy use was recorded through a remote eye-tracking device and, later, free recall and recognition for target items was assessed; and (b) tasks measuring resistance to interference…

Electrolysis cell stimulation

NASA Technical Reports Server (NTRS)

Gordon, L. H.; Phillips, B. R.; Evangelista, J.

1978-01-01

Computer program represents attempt to understand and model characteristics of electrolysis cells. It allows user to determine how cell efficiency is affected by temperature, pressure, current density, electrolyte concentration, characteristic dimensions, membrane resistance, and electrolyte circulation rate. It also calculates ratio of bubble velocity to electrolyte velocity for anode and cathode chambers.

New bimetallic EMF cell shows promise in direct energy conversion

NASA Technical Reports Server (NTRS)

Hesson, J. C.; Shimotake, H.

1968-01-01

Concentration cell, based upon a thermally regenerative cell principle, produces electrical energy from any large heat source. This experimental bimetallic EMF cell uses a sodium-bismuth alloy cathode and a pure liquid sodium anode. The cell exhibits reliability, corrosion resistance, and high current density performance.

Feasibility of Screening for Antibiotic Resistance - Part I

DTIC Science & Technology

2005-09-01

Klebsiella pneumonia (AF052258), Providencia stuartii (AF052259), Serratia marcescens (AF052260). After alignment of the sequences of the various...intracellular targets of fluoroquinolones , the type II DNA topoisomerases gyrase and topoisomerase IV [Balas et al., 1998; Weigel et al., 1998]. Mutations in...the quinolones resistant determining region (QRDR) of the parC gene, which encodes the A subunit of topoisomerase , and the gyrA gene, which encodes

The Evolution of Solid Oxide Fuel Cell Nickel-Yttria Stabilized Zirconia Anodes Studied Using Electrochemical and Three-Dimensional Microstructural Characterizations

NASA Astrophysics Data System (ADS)

Kennouche, David O.

This thesis focuses on Solid Oxide Fuel Cells (SOFCs). The 21st century will see major changes in the way energy is produced, stored, and used around the world. SOFCs, which provide an efficient, scalable, and low-pollution alternative method for electricity generation, are expected to play an important role. SOFCs can also be operated in electrolysis mode for energy storage, important since health and economic reasons are causing a shift towards intermittent renewable energy resources. However, multiple limitations mainly linked to cost and durability have prevented the expansion of this technology to mass markets. This work focuses on the Nickel - Yttria Stabilized Zirconia (Ni-YSZ) anode that is widely used in SOFCs. Coarsening of Ni in the Ni-YSZ anode has been widely cited as a primary cause of long-term SOFC degradation. While there have been numerous studies of Ni coarsening reported, these have typically only tracked the evolution of Ni particle size, not the entire microstructure, and have typically not been correlated directly with electrochemical performance. In this thesis, the advanced tomography techniques Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) tomography and Trans- mission X-ray Microscopy (TXM) have been utilized to enable insight into the evolution of Ni-YSZ structure and how it relates to performance degradation. Extensive anode aging studies were done for relatively short times using temperatures higher than in normal SOFC operation in order to accelerate microstructural evolution. In addition the microstructure changes were correlated with changes in anode polarization resistance. While most of the measurements were done by comparing different anodes aged under different conditions, the first example of a "pseudo in situ" measurement where the same anode was 3D imaged repeatedly with intervening aging steps, was also demonstrated. A microstructural evolution model that focuses on the active three-phase boundary density was fitted to the experimental data, and subsequently used to predict the change in anode three-phase boundary density and average particle size for extended times under normal SOFC conditions. Characterization of other anodes (pulsed-laser deposited and micro-tubular geometries) produced by international collaborators is also presented. Finally, a testing setup and protocol for anode life testing with current density and overpotential has been developed and implemented. Early test results are presented.

Detection of β-lactamase encoding genes in feces, soil and water from a Brazilian pig farm.

PubMed

Furlan, João Pedro Rueda; Stehling, Eliana Guedes

2018-01-10

β-lactam antibiotics are widely used for the treatment of different types of infections worldwide and the resistance to these antibiotics has grown sharply, which is of great concern. Resistance to β-lactams in gram-negative bacteria is mainly due to the production of β-lactamases, which are classified according to their functional activities. The aim of this study was to verify the presence of β-lactamases encoding genes in feces, soil, and water from a Brazilian pig farm. Different β-lactamases encoding genes were found, including bla CTX-M-Gp1 , bla CTX-M-Gp9 , bla SHV , bla OXA-1-like , bla GES , and bla VEB . The bla SHV and bla CTX-M-Gp1 genes have been detected in all types of samples, indicating the spread of β-lactam resistant bacteria among farm pigs and the environment around them. These results indicate that β-lactamase encoding genes belonging to the cloxacillinase, ESBL, and carbapenemase and they have high potential to spread in different sources, due to the fact that genes are closely related to mobile genetic elements, especially plasmids.

Progress toward characterization of the group A Streptococcus metagenome: complete genome sequence of a macrolide-resistant serotype M6 strain.

PubMed

Banks, David J; Porcella, Stephen F; Barbian, Kent D; Beres, Stephen B; Philips, Lauren E; Voyich, Jovanka M; DeLeo, Frank R; Martin, Judith M; Somerville, Greg A; Musser, James M

2004-08-15

We describe the genome sequence of a macrolide-resistant strain (MGAS10394) of serotype M6 group A Streptococcus (GAS). The genome is 1,900,156 bp in length, and 8 prophage-like elements or remnants compose 12.4% of the chromosome. A 8.3-kb prophage remnant encodes the SpeA4 variant of streptococcal pyrogenic exotoxin A. The genome of strain MGAS10394 contains a chimeric genetic element composed of prophage genes and a transposon encoding the mefA gene conferring macrolide resistance. This chimeric element also has a gene encoding a novel surface-exposed protein (designated "R6 protein"), with an LPKTG cell-anchor motif located at the carboxyterminus. Surface expression of this protein was confirmed by flow cytometry. Humans with GAS pharyngitis caused by serotype M6 strains had antibody against the R6 protein present in convalescent, but not acute, serum samples. Our studies add to the theme that GAS prophage-encoded extracellular proteins contribute to host-pathogen interactions in a strain-specific fashion.

The Effect of Surface Coatings on the Fatigue Strength of Aluminum Alloys

DTIC Science & Technology

1981-09-01

Satec Models SF-2U-144 and -145 fatigue testing machines. The abrasion (wear) resistance, the thickness, and the corrosion resistance of the specimens...former coupons; therefore, sharp ed-, es should be finished or rounded by shot peening or sandblasting in order to diminish the possibility of crack...propagation. "Anodic Coatings for Aluminum and Aluminum Alloys%" Military Specification MIL-A-8625C. 6 Satec Systems, Inc.;Grove City, PA 16127. 3 41: I! ,I

Enzymes of the Phenylpropanoid Pathway in Soybean Infected with Meloidogyne incognita or Heterodera glycines.

PubMed

Edens, R M; Anand, S C; Bolla, R I

1995-09-01

Transcription of genes encoding several enzymes and the activity of some of these enzymes of the phenylpropanoid pathway leading to synthesis of chemical and physical barriers for defense of plants against root pathogens was estimated in susceptible and resistant soybean infected with Heterodera glycines race 3 or with Meloidogyne incognita race 3. Transcription of genes encoding phenylalanine ammonia lyase (PAL) and the activity of this enzyme increased in resistant, but not susceptible, soybean cultivars after nematode infection. Likewise, transcription of the gene encoding 4-coumaryl CoA ligase and activity of this enzyme were enhanced in resistant, but not susceptible, soybean cultivars after nematode infection. Activity of PAL decreased in susceptible soybean after H. glycines or M. incognita infection. Transcription of enzymes later in the phenylpropanoid pathway leading to glyceollin synthesis increased in both resistant and susceptible soybean in response to nematode infection; the increase was greater in resistant cultivars. These results suggest possible reasons for the rapid induction of glyceollin synthesis immediately after infection of resistant soybean cultivars with H. glycines or M. incognita and the failure of this response in infected, susceptible soybean cultivars. Nematode infection had no effect on the activity of enzymes in the branch of the pathway leading to lignin synthesis.

Modeling the Control of Phonological Encoding in Bilingual Speakers

ERIC Educational Resources Information Center

Roelofs, Ardi; Verhoef, Kim

2006-01-01

Phonological encoding is the process by which speakers retrieve phonemic segments for morphemes from memory and use the segments to assemble phonological representations of words to be spoken. When conversing in one language, bilingual speakers have to resist the temptation of encoding word forms using the phonological rules and representations of…

Three-dimensional core-shell Fe2O3 @ carbon/carbon cloth as binder-free anode for the high-performance lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, Xiaohua; Zhang, Miao; Liu, Enzuo; He, Fang; Shi, Chunsheng; He, Chunnian; Li, Jiajun; Zhao, Naiqin

2016-12-01

A facile and scalable strategy is developed to fabricate three dimensional core-shell Fe2O3 @ carbon/carbon cloth structure by simple hydrothermal route as binder-free lithium-ion battery anode. In the unique structure, carbon coated Fe2O3 nanorods uniformly disperse on carbon cloth which forms the conductive carbon network. The hierarchical porous Fe2O3 nanorods in situ grown on the carbon cloth can effectively shorten the transfer paths of lithium ions and reduce the contact resistance. The carbon coating significantly inhibits pulverization of active materials during the repeated Li-ion insertion/extraction, as well as the direct exposure of Fe2O3 to the electrolyte. Benefiting from the structural integrity and flexibility, the nanocomposites used as binder-free anode for lithium-ion batteries, demonstrate high reversible capacity and excellent cyclability. Moreover, this kind of material represents an alternative promising candidate for flexible, cost-effective, and binder-free energy storage devices.

The suitability of monopolar and bipolar ion exchange membranes as separators for biological fuel cells.

PubMed

Harnisch, Falk; Schröder, Uwe; Scholz, Fritz

2008-03-01

A proton exchange (Nafion-117), a cation exchange (Ultrex CMI7000), an anion exchange (Fumasep FAD), and a bipolar (FumasepFBM) membrane have been studied to evaluate the principle suitability of ion exchange membranes as separators between the anode and the cathode compartment of biological fuel cells. The applicability of these membranes is severely affected by the neutral pH, and the usually low ionic strength of the electrolyte solutions. Thus, the ohmic resistance of the monopolar membranes was found to greatly increase at neutral pH and at decreasing electrolyte concentrations. None of the studied membranes can prevent the acidification of the anode and the alkalization of the cathode compartment, which occurs in the course of the fuel cell operation. Bipolar membranes are shown to be least suitable for biofuel cell application since they show the highest polarization without being able to prevent pH splitting between the anode and cathode compartments.

One-step synthesis of 3D sulfur/nitrogen dual-doped graphene supported nano silicon as anode for Li-ion batteries

NASA Astrophysics Data System (ADS)

Li, Ruihong; Li, Junli; Qi, Kaiyu; Ge, Xin; Zhang, Qiwei; Zhang, Bangwen

2018-03-01

Silicon is one of the most promising candidates for next-generation anode of Lithium-ion batteries. However, poor electrical conductivity and large volume change during alloying/dealloying hinder its practical use. Here we reported a three-dimensional (3D) nitrogen and sulfur codoped graphene supported silicon nanoparticles composite (SN-G/Si) through one-step hydrothermal self-assembly. The obtained SN-G/Si was investigated in term of instrumental characterizations and electrochemical properties. The results show that SN-G/Si as a freestanding anode in LIBs delivers a reversible capacity of 2020 mAh g-1 after 100 cycles with coulombic efficiency of nearly 97%. The excellent electrochemical performance is associated with the unique structure and the synergistic effect of SN-G/Si, in which SN-G provides volume buffer for nano Si as the flexible loader, short paths/fast channels for electron/Li ion transport as porous skeleton, and low charge-transfer resistance.

Effect of the co-spun anode functional layer on the performance of the direct-methane microtubular solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Meng, Xiuxia; Gong, Xun; Yin, Yimei; Yang, Naitao; Tan, Xiaoyao; Ma, Zi-Feng

2014-02-01

NiO-YSZ/porous YSZ (NiO-YSZ/p-YSZ) dual-layer hollow fibers have been fabricated by a co-spinning-sintering method, on which a dense YSZ films has been formed by a dip-coating and sintering process. A LSM-YSZ ink has been dip-coated on the dense YSZ films as cathode, while the Cu-CeO2 carbon-resistant catalyst has been impregnated in the p-YSZ layer to form double-anode supported micro tubular fuel cells (MT-SOFCs). The thickness of the Ni-YSZ layer, so called anode functional layer (AFL), is controlled from 74 μm to 13 μm by varying the spinning rates of the NiO-YSZ dopes. The maximum power density of an MT-SOFC, which is fabricated based on a thin co-spun AFL, reaches 566 mW cm-2 operated at 850 °C fed with dry methane, and is stably operated for 85 h without power declination.

High speed curved position sensitive detector

DOEpatents

Hendricks, Robert W.; Wilson, Jack W.

1989-01-01

A high speed curved position sensitive porportional counter detector for use in x-ray diffraction, the detection of 5-20 keV photons and the like. The detector employs a planar anode assembly of a plurality of parallel metallic wires. This anode assembly is supported between two cathode planes, with at least one of these cathode planes having a serpentine resistive path in the form of a meander having legs generally perpendicular to the anode wires. This meander is produced by special microelectronic fabrication techniques whereby the meander "wire" fans outwardly at the cathode ends to produce the curved aspect of the detector, and the legs of the meander are small in cross-section and very closely spaced whereby a spatial resolution of about 50 .mu.m can be achieved. All of the other performance characteristics are about as good or better than conventional position sensitive proportional counter type detectors. Count rates of up to 40,000 counts per second with 0.5 .mu.s shaping time constants are achieved.

Preparation of Advanced CuO Nanowires/Functionalized Graphene Composite Anode Material for Lithium Ion Batteries

PubMed Central

Zhang, Jin; Wang, Beibei; Zhou, Jiachen; Xia, Ruoyu; Chu, Yingli; Huang, Jia

2017-01-01

The copper oxide (CuO) nanowires/functionalized graphene (f-graphene) composite material was successfully composed by a one-pot synthesis method. The f-graphene synthesized through the Birch reduction chemistry method was modified with functional group “–(CH2)5COOH”, and the CuO nanowires (NWs) were well dispersed in the f-graphene sheets. When used as anode materials in lithium-ion batteries, the composite exhibited good cyclic stability and decent specific capacity of 677 mA·h·g−1 after 50 cycles. CuO NWs can enhance the lithium-ion storage of the composites while the f-graphene effectively resists the volume expansion of the CuO NWs during the galvanostatic charge/discharge cyclic process, and provide a conductive paths for charge transportation. The good electrochemical performance of the synthesized CuO/f-graphene composite suggests great potential of the composite materials for lithium-ion batteries anodes. PMID:28772432

Evaluation of Kefir as a New Anodic Biocatalyst Consortium for Microbial Fuel Cell.

PubMed

Silveira, Gustavo; Schneedorf, José Maurício

2018-02-21

Kefir, a combined consortium of bacteria and yeast encapsulated by a polymeric matrix of exopolysaccharides, was used as anodic biocatalyst in a two-chamber microbial fuel cell (MFC). Fermentation was followed during 72 h and polarization curves were obtained from linear sweep voltammetry. The effect of methylene blue as charge-transfer mediator in the kefir metabolism was evaluated. UV/Vis spectrophotometry and cyclic voltammetry were applied to evaluate the redox state of the mediator and to characterize the electrochemical activity, whereas current interruption was used for internal resistance determination. Aiming to establish a relationship between the microbial development inside the anodic chamber with the generated power in the MFC, total titratable acidity, pH, viscosity, carbohydrate assimilation, and microbial counting were assayed. The kefir-based MFC demonstrated a maximum power density of 54 mW m -2 after 24 h fermentation, revealing the potential use of kefir as a biocatalyst for microbial fuel cells.

Emergence of scarlet fever Streptococcus pyogenes emm12 clones in Hong Kong is associated with toxin acquisition and multidrug resistance.

PubMed

Davies, Mark R; Holden, Matthew T; Coupland, Paul; Chen, Jonathan H K; Venturini, Carola; Barnett, Timothy C; Zakour, Nouri L Ben; Tse, Herman; Dougan, Gordon; Yuen, Kwok-Yung; Walker, Mark J

2015-01-01

A scarlet fever outbreak began in mainland China and Hong Kong in 2011 (refs. 1-6). Macrolide- and tetracycline-resistant Streptococcus pyogenes emm12 isolates represent the majority of clinical cases. Recently, we identified two mobile genetic elements that were closely associated with emm12 outbreak isolates: the integrative and conjugative element ICE-emm12, encoding genes for tetracycline and macrolide resistance, and prophage ΦHKU.vir, encoding the superantigens SSA and SpeC, as well as the DNase Spd1 (ref. 4). Here we sequenced the genomes of 141 emm12 isolates, including 132 isolated in Hong Kong between 2005 and 2011. We found that the introduction of several ICE-emm12 variants, ΦHKU.vir and a new prophage, ΦHKU.ssa, occurred in three distinct emm12 lineages late in the twentieth century. Acquisition of ssa and transposable elements encoding multidrug resistance genes triggered the expansion of scarlet fever-associated emm12 lineages in Hong Kong. The occurrence of multidrug-resistant ssa-harboring scarlet fever strains should prompt heightened surveillance within China and abroad for the dissemination of these mobile genetic elements.

Tanscriptomic Study of the Soybean-Fusarium virguliforme Interaction Revealed a Novel Ankyrin-Repeat Containing Defense Gene, Expression of Whose during Infection Led to Enhanced Resistance to the Fungal Pathogen in Transgenic Soybean Plants

PubMed Central

Ngaki, Micheline N.; Wang, Bing; Sahu, Binod B.; Srivastava, Subodh K.; Farooqi, Mohammad S.; Kambakam, Sekhar; Swaminathan, Sivakumar

2016-01-01

Fusarium virguliforme causes the serious disease sudden death syndrome (SDS) in soybean. Host resistance to this pathogen is partial and is encoded by a large number of quantitative trait loci, each conditioning small effects. Breeding SDS resistance is therefore challenging and identification of single-gene encoded novel resistance mechanisms is becoming a priority to fight this devastating this fungal pathogen. In this transcriptomic study we identified a few putative soybean defense genes, expression of which is suppressed during F. virguliforme infection. The F. virguliforme infection-suppressed genes were broadly classified into four major classes. The steady state transcript levels of many of these genes were suppressed to undetectable levels immediately following F. virguliforme infection. One of these classes contains two novel genes encoding ankyrin repeat-containing proteins. Expression of one of these genes, GmARP1, during F. virguliforme infection enhances SDS resistance among the transgenic soybean plants. Our data suggest that GmARP1 is a novel defense gene and the pathogen presumably suppress its expression to establish compatible interaction. PMID:27760122

A preliminary study of the electro-oxidation of L-ascorbic acid on polycrystalline silver in alkaline solution

NASA Astrophysics Data System (ADS)

Majari Kasmaee, L.; Gobal, F.

Electrochemical oxidation of L-ascorbic acid on polycrystalline silver in alkaline aqueous solutions is studied by cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (IS). The anodic electro-oxidation starts at -500 mV versus SCE and shows continued anodic oxidation in the cathodic half cycle in the CV regime signifying slowly oxidizing adsorbates. Diffusion coefficient of ascorbate ion measured under both voltammetric regimes is around 1.4 × 10 -5 cm 2 s -1. Impedance spectroscopy measures the capacitances associated with double layer and adsorption around 50 μF cm -2 and 4 mF cm -2 as well as the adsorption and decomposition resistances (rates).

Effect of Carbon Coating on Li4TiO12 of Anode Material for Hybrid Capacitor.

PubMed

Lee, Jong-Kyu; Lee, Byung-Gwan; Yoon, Jung-Rag

2015-11-01

The carbon-coated Li4Ti5O12 of anode material for hybrid capacitor was prepared by controlling carbonization time at 700 degrees C in nitrogen. With increasing of carbonization time, the discharge capacity and capacitance were decreased, while the equivalent series resistance was not changed remarkably. The rate capability and cycle performance of carbon-coated Li4Ti5O12 were larger than that of Li4Ti5O12. Carbon coating improved conductivity as well as Li-ion diffusion, and thus also resulted in good rate capabilities and cycle stability. The effects of carbon coating on the gas generation of hybrid capacitor were also discussed.

1.9 kV AlGaN/GaN Lateral Schottky Barrier Diodes on Silicon

DOE PAGES

Zhu, Mingda; Song, Bo; Qi, Meng; ...

2015-02-16

In this letter, we present AlGaN/GaN lateral Schottky barrier diodes on silicon with recessed anodes and dual field plates. A low specific on-resistance R ON,SP (5.12 mΩ · cm 2), a low turn-on voltage (<0.7 V) and a high reverse breakdown voltage BV (>1.9 kV), were simultaneously achieved in devices with a 25 μm anode/cathode separation, resulting in a power figure-of-merit (FOM) BV2/R ON,SP of 727 MW·cm 2. The record high breakdown voltage of 1.9 kV is attributed to the dual field plate structure.

Bearing assembly and the like for use in corrosive and non-corrosive atmospheres

DOEpatents

Mashburn, Douglas N.; Woodall, Harold C.; Wright, Ralph R.

1979-01-01

This invention relates to a novel machine element characterized by mutually rubbing surfaces which are composed of dissimilar materials having high hardness, a low coefficient of friction, and resistance to corrosion by halogen-containing atmospheres. As exemplified by the preferred embodiment for use in gaseous UF.sub.6, the rubbing surfaces are chemically deposited nickel and anodized aluminum. These surfaces permit jam-free operation despite long-term exposure to UF.sub.6. Preferably, both surfaces have a hardness of at least about 500 HV.sub.100 on the Vickers hardness scale, and preferably the anodized-aluminum surface is of a type having comparatively little tendency to sorb uranium hexafluoride.

Materiais a base de oxidos com estrutura do tipo perovskite e compositos como anodos de PCES: Propriedades Funcionais e Comportamento Eletroquimico em Celulas com Eletrolitos Solidos a Base de Galatos e Silicatos

NASA Astrophysics Data System (ADS)

Kolotygin, Vladislav

This work was focused on the analysis of transport, thermomechanical and electrochemical properties of a series of perovskite-like oxide materials and composites for potential applications as anodes of intermediate-temperature solid oxide fuel cells (SOFCs) with lanthanum gallate and silicate solid electrolytes. The primary attention was centered on A(Mn,Nb)O3-delta (A = Sr, Ca) and (La,Sr)(Mn,Ti)O3-based systems, lanthanum chromite substituted with acceptor-type and variable-valence cations, and various Ni-containing cermets. Emphasis was given to phase stability of the materials, their crystal structure, microstructure of porous electrode layers and dense ceramics, electronic conductivity, Seebeck coefficient, oxygen permeability, thermal and chemical induced expansion, and anodic overpotentials of the electrodes deposited onto (La,Sr)(Ga,Mg)O3- and La10(Si,Al)6O27-based electrolyte membranes. In selected cases, roles of oxygen diffusivity, states of the transition metal cations relevant for the electronic transport, catalytically active additives and doped ceria protective interlayers introduced in the model electrochemical cells were assessed. The correlations between transport properties of the electrode materials and electrochemical behavior of porous electrodes showed that the principal factors governing anode performance include, in particular, electronic conduction of the anode compositions and cation interdiffusion between the electrodes and solid electrolytes. The latter is critically important for the silicatebased electrolyte membranes, leading to substantially worse anode properties compared to the electrochemical cells with lanthanum gallate solid electrolyte. The results made it possible to select several anode compositions exhibiting lower area-specific electrode resistivity compared to known analogues, such as (La,Sr)(Cr,Mn)O3-delta.

Niobium Doped Lanthanum Strontium Ferrite as A Redox-Stable and Sulfur-Tolerant Anode for Solid Oxide Fuel Cells.

PubMed

Li, Jingwei; Wei, Bo; Cao, Zhiqun; Yue, Xing; Zhang, Yaxin; Lü, Zhe

2018-01-10

The Nb-doped lanthanum strontium ferrite perovskite oxide La 0.8 Sr 0.2 Fe 0.9 Nb 0.1 O 3-δ (LSFNb) is evaluated as an anode material in a solid oxide fuel cell (SOFC). The effects of Nb partial substitution in the crystal structure, the electrical conductivity, and the valence of Fe ions are studied. LSFNb exhibits good structural stability in a severe reducing atmosphere at 800 °C, suggesting that high-valent Nb can effectively promote the stability of the lattice structure. The concentration of Fe 2+ increases after Nb doping, as confirmed by X-ray photoelectron spectroscopy. The maximum power density of a thick Sc-stabilized zirconia (ScSZ) electrolyte-supported single cell reached 241.6 mW cm -2 at 800 °C with H 2 as fuel. The cell exhibited excellent stability for 100 h continuous operation without detectable degeneration. Scanning electron microscopy clearly revealed exsolution on the LSFNb surface after operation. Meanwhile, LSFNb particles agglomerated significantly during long-term stability testing. Impedance spectra suggested that both the LSFNb anode and the (La 0.75 Sr 0.25 ) 0.95 MnO 3-δ /ScSZ cathode underwent an activation process during long-term testing, through which the charge transfer ability increased significantly. Meanwhile, low-frequency resistance (R L ) mainly attributed to the anode (80 %) significantly increased, probably due to the agglomeration of LSFNb particles. The LSFNb anode exhibits excellent anti-sulfuring poisoning ability and redox stability. These results demonstrate that LSFNb is a promising anode material for SOFCs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved Osteoblast and Chondrocyte Adhesion and Viability by Surface-Modified Ti6Al4V Alloy with Anodized TiO2 Nanotubes Using a Super-Oxidative Solution

PubMed Central

Beltrán-Partida, Ernesto; Moreno-Ulloa, Aldo; Valdez-Salas, Benjamín; Velasquillo, Cristina; Carrillo, Monica; Escamilla, Alan; Valdez, Ernesto; Villarreal, Francisco

2015-01-01

Titanium (Ti) and its alloys are amongst the most commonly-used biomaterials in orthopedic and dental applications. The Ti-aluminum-vanadium alloy (Ti6Al4V) is widely used as a biomaterial for these applications by virtue of its favorable properties, such as high tensile strength, good biocompatibility and excellent corrosion resistance. TiO2 nanotube (NTs) layers formed by anodization on Ti6Al4V alloy have been shown to improve osteoblast adhesion and function when compared to non-anodized material. In his study, NTs were grown on a Ti6Al4V alloy by anodic oxidation for 5 min using a super-oxidative aqueous solution, and their in vitro biocompatibility was investigated in pig periosteal osteoblasts and cartilage chondrocytes. Scanning electron microscopy (SEM), energy dispersion X-ray analysis (EDX) and atomic force microscopy (AFM) were used to characterize the materials. Cell morphology was analyzed by SEM and AFM. Cell viability was examined by fluorescence microscopy. Cell adhesion was evaluated by nuclei staining and cell number quantification by fluorescence microscopy. The average diameter of the NTs was 80 nm. The results demonstrate improved cell adhesion and viability at Day 1 and Day 3 of cell growth on the nanostructured material as compared to the non-anodized alloy. In conclusion, this study evidences the suitability of NTs grown on Ti6Al4V alloy using a super-oxidative water and a short anodization process to enhance the adhesion and viability of osteoblasts and chondrocytes. The results warrant further investigation for its use as medical implant materials. PMID:28787976

Improved Osteoblast and Chondrocyte Adhesion and Viability by Surface-Modified Ti6Al4V Alloy with Anodized TiO₂ Nanotubes Using a Super-Oxidative Solution.

PubMed

Beltrán-Partida, Ernesto; Moreno-Ulloa, Aldo; Valdez-Salas, Benjamín; Velasquillo, Cristina; Carrillo, Monica; Escamilla, Alan; Valdez, Ernesto; Villarreal, Francisco

2015-03-02

Titanium (Ti) and its alloys are amongst the most commonly-used biomaterials in orthopedic and dental applications. The Ti-aluminum-vanadium alloy (Ti6Al4V) is widely used as a biomaterial for these applications by virtue of its favorable properties, such as high tensile strength, good biocompatibility and excellent corrosion resistance. TiO₂ nanotube (NTs) layers formed by anodization on Ti6Al4V alloy have been shown to improve osteoblast adhesion and function when compared to non-anodized material. In his study, NTs were grown on a Ti6Al4V alloy by anodic oxidation for 5 min using a super-oxidative aqueous solution, and their in vitro biocompatibility was investigated in pig periosteal osteoblasts and cartilage chondrocytes. Scanning electron microscopy (SEM), energy dispersion X-ray analysis (EDX) and atomic force microscopy (AFM) were used to characterize the materials. Cell morphology was analyzed by SEM and AFM. Cell viability was examined by fluorescence microscopy. Cell adhesion was evaluated by nuclei staining and cell number quantification by fluorescence microscopy. The average diameter of the NTs was 80 nm. The results demonstrate improved cell adhesion and viability at Day 1 and Day 3 of cell growth on the nanostructured material as compared to the non-anodized alloy. In conclusion, this study evidences the suitability of NTs grown on Ti6Al4V alloy using a super-oxidative water and a short anodization process to enhance the adhesion and viability of osteoblasts and chondrocytes. The results warrant further investigation for its use as medical implant materials.

Electricity generation from real industrial wastewater using a single-chamber air cathode microbial fuel cell with an activated carbon anode.

PubMed

Mohamed, Hend Omar; Obaid, M; Sayed, Enas Taha; Liu, Yang; Lee, Jinpyo; Park, Mira; Barakat, Nasser A M; Kim, Hak Yong

2017-08-01

This study introduces activated carbon (AC) as an effective anode for microbial fuel cells (MFCs) using real industrial wastewater without treatment or addition of external microorganism mediators. Inexpensive activated carbon is introduced as a proper electrode alternative to carbon cloth and carbon paper materials, which are considered too expensive for the large-scale application of MFCs. AC has a porous interconnected structure with a high bio-available surface area. The large surface area, in addition to the high macro porosity, facilitates the high performance by reducing electron transfer resistance. Extensive characterization, including surface morphology, material chemistry, surface area, mechanical strength and biofilm adhesion, was conducted to confirm the effectiveness of the AC material as an anode in MFCs. The electrochemical performance of AC was also compared to other anodes, i.e., Teflon-treated carbon cloth (CCT), Teflon-treated carbon paper (CPT), untreated carbon cloth (CC) and untreated carbon paper (CP). Initial tests of a single air-cathode MFC display a current density of 1792 mAm -2 , which is approximately four times greater than the maximum value of the other anode materials. COD analyses and Coulombic efficiency (CE) measurements for AC-MFC show the greatest removal of organic compounds and the highest CE efficiency (60 and 71%, respectively). Overall, this study shows a new economical technique for power generation from real industrial wastewater with no treatment and using inexpensive electrode materials.

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

PubMed

Butler, Caitlyn S; Nerenberg, Robert

2010-05-01

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

Proton exchange membrane and electrode surface areas as factors that affect power generation in microbial fuel cells.

PubMed

Oh, Sang-Eun; Logan, Bruce E

2006-03-01

Power generation in microbial fuel cells (MFCs) is a function of the surface areas of the proton exchange membrane (PEM) and the cathode relative to that of the anode. To demonstrate this, the sizes of the anode and cathode were varied in two-chambered MFCs having PEMs with three different surface areas (A (PEM)=3.5, 6.2, or 30.6 cm(2)). For a fixed anode and cathode surface area (A (An)=A (Cat)=22.5 cm(2)), the power density normalized to the anode surface area increased with the PEM size in the order 45 mW/m(2) (A (PEM)=3.5 cm(2)), 68 mW/m(2) (A (PEM)=6.2 cm(2)), and 190 mW/m(2) (A (PEM)=30.6 cm(2)). PEM surface area was shown to limit power output when the surface area of the PEM was smaller than that of the electrodes due to an increase in internal resistance. When the relative cross sections of the PEM, anode, and cathode were scaled according to 2A (Cat)=A(PEM)=2A (An), the maximum power densities of the three different MFCs, based on the surface area of the PEM (A (PEM)=3.5, 6.2, or 30.6 cm(2)), were the same (168+/-4.53 mW/m(2)). Increasing the ionic strength and using ferricyanide at the cathode also increased power output.

An ion-conductive Li1.5Al0.5Ge1.5(PO4)3-based composite protective layer for lithium metal anode in lithium-sulfur batteries

NASA Astrophysics Data System (ADS)

Sun, Changzhi; Huang, Xiao; Jin, Jun; Lu, Yang; Wang, Qing; Yang, Jianhua; Wen, Zhaoyin

2018-02-01

Lithium (Li) metal plays an indispensable role in Li-S batteries, but its fast degradation seriously impedes the practical application of Li-S batteries. Here, an ion-conductive LAGP-based composite protective layer (CPL) consisting of lithium aluminum germanium phosphate (Li1.5Al0.5Ge1.5(PO4)3) and polyvinylidene fluoride (PVDF) is prepared on Li metal anode via a facile casting method. In the presence of LAGP, the negative effect of CPL on the diffusion of Li+ is minimized. Hence, it can not only effectively resist corrosive action of lithium polysulfides (LiPSs) on Li metal anode, but also reduce interfacial polarization and restrain dendritic Li growth. The protected Li anode exhibits exceptional cycling stability and low voltage polarization (∼30 mV at 0.5 mA cm-2) for 300 h. The electrochemical performance of Li-S batteries with protected Li anode is also greatly enhanced. The discharge specific capacity of 832.1 mAh g-1 and an average coulombic efficiency of 92% are obtained for up to 100 cycles at 0.5 C in LiNO3-free electrolyte. Additionally, the rate capability of Li-S batteries is significantly improved, delivering a reversible capacity of 565 mAh g-1 at 4 C. Our results also indicate this protection strategy can be extended to the Li-S pouch cells.

Surface characteristics of anodized and hydrothermally treated titatnium with an increasing concentration of calcium ion

NASA Astrophysics Data System (ADS)

Park, Il Song; Bae, Tae Sung; Seol, Kyeong Won

2006-10-01

Titanium is widely used as an implant material due to its good mechanical properties and the excellent biocompatibility of the oxide film on the surface. To modify the unstable oxide surface of pure titanium, plasma electrolytic oxidation was applied in this study. The electrolyte used for anodizing was a mixture of GP (glycerophosphate disodium salt) and CA (calcium acetate). In addition, a hydrothermal treatment was performed to precipitate a calcium phosphate crystal on the titanium oxide layer for bioactivity. The effect of the CA concentration of the electrolyte on the surface of titanium was investigated, with CA concentrations at 0.1 M, 0.2 M, and 0.3 M. A high concentration of CA results in a low breakdown voltage; hence many large micropores were formed on the anodized surface. Moreover, the size of the HA crystals was more minute in proportion to the increasing concentration of CA. The crystal phase of titanium dioxide was mainly anatase, and a rutile phase was also observed. As the size and/or amount of HA crystals increased, the surface roughness increased. However, the surface roughness could be decreased by fully and uniformly covering the surface with HA crystals. The corrosion resistance in the saline solution was increased by anodic spark oxidation. In addition, it was slightly increased by a hydrothermal treatment. It is considered that a more stable and thicker titanium oxide layer is formed by anodic oxidation and a hydrothermal treatment.

Fatigue resistance, electrochemical corrosion and biological response of Ti-15Mo with surface modified by amorphous TiO2 nanotubes layer.

PubMed

Campanelli, Leonardo C; Oliveira, Nilson T C; da Silva, Paulo Sergio C P; Bolfarini, Claudemiro; Palmieri, Annalisa; Cura, Francesca; Carinci, Francesco; Motheo, Artur J

2018-03-04

The objective of this work was a systemic evaluation of the anodizing treatment in a β-type Ti-15Mo alloy to grow a TiO 2 nanostructured layer for osseointegration improvement. The technical viability of the surface modification was assessed based on the resistance to mechanical fatigue, electrochemical corrosion, and biological response. By using an organic solution of NH 4 F in ethylene glycol, a well-organized array of 90 nm diameter nanotubes was obtained with a potential of 40 V for 6 h, while undefined nanotubes of 25 nm diameter were formed with a potential of 20 V for 1 h. Nevertheless, the production of the 90 nm diameter nanotubes was followed by micrometer pits that significantly reduced the fatigue performance. The undefined nanotubes of 25 nm diameter, besides the greater cell viability and improved osteoblastic cell differentiation in comparison to the as-polished surface, were not deleterious to the fatigue and corrosion properties. This result strengthens the necessity of an overall evaluation of the anodizing treatment, particularly the fatigue resistance, before suggesting it for the design of implants. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc.

Apatite Formation and Biocompatibility of a Low Young’s Modulus Ti-Nb-Sn Alloy Treated with Anodic Oxidation and Hot Water

PubMed Central

Tanaka, Hidetatsu; Mori, Yu; Noro, Atsushi; Kogure, Atsushi; Kamimura, Masayuki; Yamada, Norikazu; Hanada, Shuji; Masahashi, Naoya; Itoi, Eiji

2016-01-01

Ti-6Al-4V alloy is widely prevalent as a material for orthopaedic implants because of its good corrosion resistance and biocompatibility. However, the discrepancy in Young’s modulus between metal prosthesis and human cortical bone sometimes induces clinical problems, thigh pain and bone atrophy due to stress shielding. We designed a Ti-Nb-Sn alloy with a low Young’s modulus to address problems of stress disproportion. In this study, we assessed effects of anodic oxidation with or without hot water treatment on the bone-bonding characteristics of a Ti-Nb-Sn alloy. We examined surface analyses and apatite formation by SEM micrographs, XPS and XRD analyses. We also evaluated biocompatibility in experimental animal models by measuring failure loads with a pull-out test and by quantitative histomorphometric analyses. By SEM, abundant apatite formation was observed on the surface of Ti-Nb-Sn alloy discs treated with anodic oxidation and hot water after incubation in Hank’s solution. A strong peak of apatite formation was detected on the surface using XRD analyses. XPS analysis revealed an increase of the H2O fraction in O 1s XPS. Results of the pull-out test showed that the failure loads of Ti-Nb-Sn alloy rods treated with anodic oxidation and hot water was greater than those of untreated rods. Quantitative histomorphometric analyses indicated that anodic oxidation and hot water treatment induced higher new bone formation around the rods. Our findings indicate that Ti-Nb-Sn alloy treated with anodic oxidation and hot water showed greater capacity for apatite formation, stronger bone bonding and higher biocompatibility for osteosynthesis. Ti-Nb-Sn alloy treated with anodic oxidation and hot water treatment is a promising material for orthopaedic implants enabling higher osteosynthesis and lower stress disproportion. PMID:26914329

Facile electrochemical pretreatment of multiwalled carbon nanotube - Polydimethylsiloxane paste electrode for enhanced detection of dopamine and uric acid

NASA Astrophysics Data System (ADS)

Buenaventura, Angelo Gabriel E.; Yago, Allan Christopher C.

2018-05-01

A facile electrochemical pretreatment via anodization was done on Carbon Paste Electrodes (CPEs) composed of Multiwalled Carbon Nanotubes (MWCNTs) and Polydimethylsiloxane (PDMS) binder to produce `anodized' CPEs (ACPE). Cyclic Voltammetry (CV) technique was used to anodize the CPEs. The anodization step, performed in various solutions (0.2 M NaOH(aq), 0.06 M BR Buffer at pH 7.0, and 0.2 M HNO3(aq)), were found to enhance the electrochemical properties of the ACPEs compared to non-anodized CPE. Electrochemical Impedance Spectroscopy (EIS) measurements revealed a significantly lower charge transfer resistance (Rct) for the ACPEs (4.01-6.25 kΩ) as compared to CPE (25.9 kΩ). Comparison of the reversibility analysis for Fe(CN)63-/4- redox couple showed that the ACPEs have peak current ratio (Ia/Ic) at range of 0.97-1.10 while 1.92 for the CPE; this result indicated better electrochemical reversible behaviors for Fe(CN)63-/4- redox couple using the ACPEs. CV Anodization process was further optimized by varying solution and CV parameters (i.e. pH, composition, number of cycles, and potential range), and the resulting optimized ACPE was used for enhanced detection of Dopamine (DA) and Uric Acid (UA) in the presence of excess Ascorbic Acid (AA). Employing Differential Pulse Voltammetry technique, enhanced voltammetric signal for DA and significant peak separation between DA and UA was obtained. The anodic peak currents for the oxidation of DA and UA appeared at 0.263V and 0.414 V, respectively, and it was observed to be linearly increasing with increasing concentrations of biomolecules (25-100 µM). The detection limit was determined to be 3.86 µM for DA and 5.61 µM for UA. This study showed a quick and cost-effective pretreatment for CPEs based on MWCNT-PDMS composite which lead to significant enhancement on its electrochemical properties.

Quantitative trait loci associated with anthracnose resistance in sorghum

USDA-ARS?s Scientific Manuscript database

With an aim to develop a durable resistance to the fungal disease anthracnose, two unique genetic sources of resistance were selected to create genetic mapping populations to identify regions of the sorghum genome that encode anthracnose resistance. A series of quantitative trait loci were identifi...

Effects of antinutrient proteins on Hessian fly (Diptera: Cecidomyiidae) larvae

USDA-ARS?s Scientific Manuscript database

One strategy to enhance the durability of Hessian fly resistance (R) genes in wheat is to combine them with transgenes for resistance. To identify potential transgenes for resistance a protocol for rapidly screening the proteins they encode for efficacy toward resistance is required. However, the ...

Task 1: Modeling Study of CO Effects on Polymer Electrolyte Fuel Cell Anodes Task 2: Study of Ac Impedance as Membrane/Electrode Manufacturing Diagnostic Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas E. Springer

Carbon monoxide poisoning of polymer electrolyte fuel cell anodes is a key problem to be overcome when operating a polymer electrolyte fuel cell (PEFC) on reformed fuels. CO adsorbs preferentially on the precious metal surface leading to substantial performance losses. Some recent work has explored this problem, primarily using various Pt alloys in attempts to lower the degree of surface deactivation. In their studies of hydrogen oxidation on Pt and Pt alloy (Pt/Sn, Pt/Ru) rotating disk electrodes exposed to H{sub 2}/CO mixtures, Gasteiger et al. showed that a small hydrogen oxidation current is observed well before the onset of majormore » CO oxidative stripping (ca. 0.4 V) on Pt/Ru. However, these workers concluded that such current observed at low anode overpotentials was too low to be of practical value. Nonetheless, MST-11 researchers and others have found experimentally that it is possible to run a PEFC, e.g., with a Pt/Ru anode, in the presence of CO levels in the range 10--100 ppm with little voltage loss. Such experimental results suggest that, in fact, PEFC operation at significant current densities under low anode overpotentials is possible in the presence of such levels of CO, even before resorting to air bleeding into the anode feed stream. The latter approach has been shown to be effective in elimination of Pt anode catalyst poisoning effects at CO levels of 20--50 ppm for cells operating at 80 C with low Pt catalyst loading. The effect of oxygen bleeding is basically to lower P{sub CO} down to extremely low levels in the anode plenum thanks to the catalytic (chemical) oxidation of CO by dioxygen at the anode catalyst. In this modeling work the authors do not include specific description of oxygen bleeding effects and concentrate on the behavior of the anode with feed streams of H{sub 2} or reformate containing low levels of CO. The anode loss is treated in this work as a hydrogen and carbon monoxide electrode kinetics problem, but includes the effects of dilution of the feedstream with significant fractions of carbon dioxide and nitrogen and of mass transport losses in the gas diffusion backing. Not included in the anode model are ionic resistance and diffusion losses in the catalyst layer. They are looking to see if the overall pattern of polarization curves calculated based on such a purely kinetic model indeed mimics the central features of polarization curves observed for PEFCs operating on hydrogen with low levels of CO.« less

A new eIF4E1 allele characterized by RNAseq data mining is associated with resistance to potato virus Y in tomato albeit with a low durability.

PubMed

Lebaron, Caroline; Rosado, Aurélie; Sauvage, Christopher; Gauffier, Camille; German-Retana, Sylvie; Moury, Benoît; Gallois, Jean-Luc

2016-11-01

Allele mining on susceptibility factors offers opportunities to find new sources of resistance among crop wild relatives for breeding purposes. As a proof of concept, we used available RNAseq data to investigate polymorphisms among the four tomato genes encoding translation initiation factors [eIF4E1 and eIF4E2, eIFiso4E and the related gene new cap-binding protein(nCBP)] to look for new potential resistance alleles to potyviruses. By analysing polymorphism among RNAseq data obtained for 20 tomato accessions, 10 belonging to the cultivated type Solanum lycopersicum and 10 belonging to the closest related wild species Solanum pimpinellifolium, we isolated one new eIF4E1 allele, in the S. pimpinellifolium LA0411 accession, which encodes a potential new resistance allele, mainly due to a polymorphism associated with an amino acid change within eIF4E1 region II. We confirmed that this new allele, pot12, is indeed associated with resistance to potato virus Y, although with a restricted resistance spectrum and a very low durability potential. This suggests that mutations occurring in eIF4E region II only may not be sufficient to provide efficient and durable resistance in plants. However, our study emphasizes the opportunity brought by RNAseq data to mine for new resistance alleles. Moreover, this approach could be extended to seek for putative new resistance alleles by screening for variant forms of susceptibility genes encoding plant host proteins known to interact with viral proteins.

Electrode Reaction Pathway in Oxide Anode for Solid Oxide Fuel Cells

NASA Astrophysics Data System (ADS)

Li, Wenyuan

Oxide anodes for solid oxide fuel cells (SOFC) with the advantage of fuel flexibility, resistance to coarsening, small chemical expansion and etc. have been attracting increasing interest. Good performance has been reported with a few of perovskite structure anodes, such as (LaSr)(CrMn)O3. However, more improvements need to be made before meeting the application requirement. Understanding the oxidation mechanism is crucial for a directed optimization, but it is still on the early stage of investigation. In this study, reaction mechanism of oxide anodes is investigated on doped YCrO 3 with H2 fuel, in terms of the origin of electrochemical activity, rate-determining steps (RDS), extension of reactive zone, and the impact from overpotential under service condition to those properties. H2 oxidation on the YCs anodes is found to be limited by charge transfer and H surface diffusion. A model is presented to describe the elementary steps in H2 oxidation. From the reaction order results, it is suggested that any models without taking H into the charge transfer step are invalid. The nature of B site element determines the H2 oxidation kinetics primarily. Ni displays better adsorption ability than Co. However, H adsorption ability of such oxide anode is inferior to that of Ni metal anode. In addition, the charge transfer step is directly associated with the activity of electrons in the anode; therefore it can be significantly promoted by enhancement of the electron activity. It is found that A site Ca doping improves the polarization resistance about 10 times, by increasing the activity of electrons to promote the charge transfer process. For the active area in the oxide anode, besides the traditional three-phase boundary (3PB), the internal anode surface as two-phase boundary (2PB) is proven to be capable of catalytically oxidizing the H2 fuel also when the bulk lattice is activated depending on the B site elements. The contribution from each part is estimated by switching the electrolyte to change 3PB kinetics. Compared to Ni, Co doping activates the bulk oxygen more significantly, promoting the reaction at 2PB. The active surface reaction zone is found to be enlarged by the electrolyte with high oxygen activity (SSZ vs. YSZ) when charge transfer is one of the RDS. Due to the larger exchange current for charge transfer in 3PB with SSZ electrolyte, the adsorption gradient zone is broadened, leading to enhanced surface reaction kinetics. The potential application of such finding is demonstrated on SSZ/YSZ/SSZ sandwich, showing largely improved electrode performance, opening a wide door for the utilization of electrolytes that are too expensive, fragile or instable to be used before. The bulk path way in 2PB reaction can be affected by overpotential in terms of local vacancy concentration, built-in electrical field and stability. It is proven that an uneven distribution of lattice oxygen is established under operation conditions with overpotential by both qualitative analysis and analytic solution. An electrostatic field force is present besides the concentration gradient in the anode lattice to control the motion of oxygen ions. Compared to the usual estimation based on chemical diffusion mechanism, the real deviation of ionic defects concentration under polarization from the equilibrium state near electrode/electrolyte interface is smaller with the built-in electrical field. The overpotential is demonstrated to be able to open up or shut down the bulk pathway depending on the ionic defects of electrodes. The analysis on the bulk pathway in terms of local charged species and various potentials provides new insight in anion diffusion and electrode stability.

A mutated ARO4 gene for feedback-resistant DAHP synthase which causes both o-fluoro-DL-phenylalanine resistance and beta-phenethyl-alcohol overproduction in Saccharomyces cerevisiae.

PubMed

Fukuda, K; Watanabe, M; Asano, K; Ouchi, K; Takasawa, S

1991-12-01

o-Fluoro-DL-phenylalanine (OFP)-resistant mutants which overproduce beta-phenethyl-alcohol were isolated from a laboratory strain of Saccharomyces cerevisiae. Cells of one of the mutants accumulated tyrosine and phenylalanine 1.5-3 fold more than did wild-type cells. Its 3-deoxy-D-arabino-hepturosonate-7-phosphate (DAHP) synthase (EC 4.1.2.15), encoded by ARO4, was free from feedback inhibition by tyrosine. Genetic analysis revealed that the mutation was controlled by a single dominant gene, ARO4-OFP, encoding feedback-resistant DAHP synthase by tyrosine, and that this gene caused both the OFP resistance and beta-phenethyl-alcohol overproduction. This was supported by molecular genetic studies using cloned ARO4 both from the wild-type and its mutant strain.

In-vitro bioactivity and electrochemical behavior of polyaniline encapsulated titania nanotube arrays for biomedical applications

NASA Astrophysics Data System (ADS)

Agilan, P.; Rajendran, N.

2018-05-01

Titania nanotube arrays (TNTA) have attracted increasing attention due to their outstanding properties and potential applications in biomedical field. Fabrication of titania nanotubes on titanium surface enhances the biocompatibility. Polyaniline (PANI) is one of the best conducting polymers with remarkable corrosion resistance and reasonable biocompatibility. In this work, the corrosion resistance and biocompatibility of polyaniline encapsulated TiO2 nanotubes for orthopaedic applications were investigated. The vertically oriented, highly ordered TiO2 nanotubes were fabricated on titanium by electrochemical anodization process using fluoride containing electrolytes. The anodization parameters viz., voltage, pH, time and electrolyte concentration were optimized to get orderly arranged TNTA. Further, the conducting polymer PANI was encapsulated on TNTA by electropolymerization process to enhance the corrosion resistance. The nanostructure of the fabricated TNTA and polyaniline encapsulated titania nanotube arrays (PANI-TNTA) were investigated by HR SEM analysis. The formed phases and functional groups were find using XRD, ATR-FTIR. The hydrophilic surface of TNTA and PANI-TNTA was identified by water contact angle studies. The corrosion behavior of specimens was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies. In-vitro immersion studies were carried out in simulated body fluid solution (Hanks' solution) to evaluate the bioactivity of the TNTA and PANI-TNTA. The surface morphological studies revealed the formation of PANI on the TNTA surface. Formation of hydroxyapatite (HAp) on the surfaces of TNTA and PANI-TNTA enhanced the bioactivity and corrosion resistance.

Solution processed transition metal oxide anode buffer layers for efficiency and stability enhancement of polymer solar cells

NASA Astrophysics Data System (ADS)

Ameen, M. Yoosuf; Shamjid, P.; Abhijith, T.; Reddy, V. S.

2018-01-01

Polymer solar cells were fabricated with solution-processed transition metal oxides, MoO3 and V2O5 as anode buffer layers (ABLs). The optimized device with V2O5 ABL exhibited considerably higher power conversion efficiency (PCE) compared to the devices based on MoO3 and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) ABLs. The space charge limited current measurements and impedance spectroscopy results of hole-only devices revealed that V2O5 provided a very low charge transfer resistance and high hole mobility, facilitating efficient hole transfer from the active layer to the ITO anode. More importantly, incorporation of V2O5 as ABL resulted in substantial improvement in device stability compared to MoO3 and PEDOT:PSS based devices. Unencapsulated PEDOT:PSS-based devices stored at a relative humidity of 45% have shown complete failure within 96 h. Whereas, MoO3 and V2O5 based devices stored in similar conditions retained 22% and 80% of their initial PCEs after 96 h. Significantly higher stability of the V2O5-based device is ascribed to the reduction in degradation of the anode/active layer interface, as evident from the electrical measurements.

A Novel Approach to Synthesize Micrometer-Sized Porous Silicon as a High Performance Anode for Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jia, Haiping; Zheng, Jianming; Song, Junhua

Porous structured silicon (p-Si) has been recognized as one of the most promising anodes for Li-ion batteries. However, many available methods to synthesize p-Si are difficult to scale up due to their high production cost. Here we introduce a new approach to obtain spherical micrometer-sized silicon with unique porous structure by using a microemulsion of the cost-effective of silica nanoparticles and magnesiothermic reduction method. The spherical micron-sized p-Si particles prepared by this approach consist of highly aligned nano-sized silicon and exhibit a tap density close to that of bulk Si particles. They have demonstrated significantly improved electrochemical stability compared tomore » nano-Si. Well controlled void space and a highly graphitic carbon coating on the p-Si particles enable good stability of the structure and low overall resistance, thus resulting in a Si-based anode with high capacity (~1467 mAh g –1 at 1 C), enhanced cycle life (370 cycles with 83% capacity retention), and high rate capability (~650 mAh g –1 at 5 C). Furthermore, this approach may also be generalized to prepare other hierarchical structured high capacity anode materials for constructing high energy density lithium ion batteries.« less

One-step pyrolysis route to three dimensional nitrogen-doped porous carbon as anode materials for microbial fuel cells

NASA Astrophysics Data System (ADS)

Bi, Linlin; Ci, Suqin; Cai, Pingwei; Li, Hao; Wen, Zhenhai

2018-01-01

The design and synthesis of low-cost and favourable anode materials is crucial to both power production efficiency and overall performance of microbial fuel cells (MFCs). Herein, we reported the preparation of three dimensional (3D) nitrogen-doped porous carbons (N/PCs) by one-step pyrolysis of solid mixture of sodium citrate and melamine. a variety of techniques, including electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), etc., were applied to characterize the surface physicochemical properties of the products, featuring macroporous structure with rich nitrogen doping on the as-prepared N/PCs. When applied as anode materials of MFC, the N/PCs exhibits a maximum power density of 2777.7 mW m-2, approximately twice higher than that of the MFCs with the commercial carbon cloth (CC) as anode. The significantly improved performance of the N/PCs was attributed to the unique structure and properties, such as favourable porous structure, good electrical conductivity, and large pore volume (0.7 cm3 g-1) in the present N/PCs. Nitrogen dopant on the surface of porous carbon contributed to an increasing in biocompatibility, resulting in a suitable micro-environment for microbial growth and thus helps to decrease charge transfer resistance at the electrode interface.

Preparation of ordered mesoporous and macroporous thermoplastic polyurethane surfaces for potential medical applications.

PubMed

Chennell, Philip; Feschet-Chassot, Emmanuelle; Sautou, Valérie; Mailhot-Jensen, Bénédicte

2018-05-01

Thermoplastic polyurethanes are widely used in medical devices. In order to limit some of their shortfalls, like microbial attachment, surfaces modifications can be required. In this work, a two-step replication method was used to create ordered macroporous and mesoporous thermoplastic polyurethane surfaces using anodic aluminum oxide as master template. The intermediate mould materials that were tested were polystyrene and a polyacrylate resin with inorganic filler. All obtained surfaces were characterized by scanning electron microscopy. The initial anodic aluminum oxide surfaces possessed macro or mesopores, function of anodization conditions. The intermediate mould structure correctly replicated the pattern, but the polystyrene surface structures (pillars) were less resistant than the polyacrylate resin ones. The thermoplastic polyurethane pattern possessed macropores or mesopores of about 130 nm or 46 nm diameter and of about 300 nm or 99 nm interpore distances, respectively, in accordance with the initial pattern. Thermoplastic polyurethanes pore depth was however less than initial anodic aluminum oxide pore depth, linked to an incomplete replication during intermediate mould preparation (60 to 90% depth replication). The correct replication of the original pattern confirms that this novel fabrication method is a promising route for surface patterning of thermoplastic polyurethanes that could be used for medical applications.

A new method for production of titanium vapor and synthesis of titanium nitride coatings

NASA Astrophysics Data System (ADS)

Grigoriev, Sergey N.; Melnik, Yury A.; Metel, Alexander S.; Volosova, Marina A.

2018-03-01

It is proposed to synthesize on machine parts and cutting tools wear-resistant titanium nitride coatings with the help of the hollow-cathode glow discharge, a molybdenum crucible for titanium evaporation being used as the anode of the discharge and a process vacuum chamber being used as the hollow cathode. The research revealed that at the anode surface area less than a critical value S* = (2m/M)1/2S, where S is the area of the chamber walls, m is the mass of electrons and M is the mass of ions, the anode fall of potential is positive and grows from ˜50 V at argon pressure p = 0.2 Pa to ˜2 kV at p = 0.02 Pa. At the discharge current I = 0.6 A electrons accelerated by the anode fall of 0.9 kV transport into the crucible with the inner diameter of 12 mm the power of ˜0.54 kW, which allows the titanium evaporation and the coating deposition rate of 5 µm·h-1 on a substrate distanced from the crucible at 100 mm. After the argon is replaced with the nitrogen, titanium nitride coating without titanium droplets is synthesized the deposition rate amounting to about the same value.

A Novel Approach to Synthesize Micrometer-Sized Porous Silicon as a High Performance Anode for Lithium-Ion Batteries

DOE PAGES

Jia, Haiping; Zheng, Jianming; Song, Junhua; ...

2018-05-21

Porous structured silicon (p-Si) has been recognized as one of the most promising anodes for Li-ion batteries. However, many available methods to synthesize p-Si are difficult to scale up due to their high production cost. Here we introduce a new approach to obtain spherical micrometer-sized silicon with unique porous structure by using a microemulsion of the cost-effective of silica nanoparticles and magnesiothermic reduction method. The spherical micron-sized p-Si particles prepared by this approach consist of highly aligned nano-sized silicon and exhibit a tap density close to that of bulk Si particles. They have demonstrated significantly improved electrochemical stability compared tomore » nano-Si. Well controlled void space and a highly graphitic carbon coating on the p-Si particles enable good stability of the structure and low overall resistance, thus resulting in a Si-based anode with high capacity (~1467 mAh g –1 at 1 C), enhanced cycle life (370 cycles with 83% capacity retention), and high rate capability (~650 mAh g –1 at 5 C). Furthermore, this approach may also be generalized to prepare other hierarchical structured high capacity anode materials for constructing high energy density lithium ion batteries.« less

Formation of Microcracks During Micro-Arc Oxidation in a Phytic Acid-Containing Solution on Two-Phase AZ91HP

NASA Astrophysics Data System (ADS)

Zhang, R. F.; Chang, W. H.; Jiang, L. F.; Qu, B.; Zhang, S. F.; Qiao, L. P.; Xiang, J. H.

2016-04-01

Micro-arc oxidation (MAO) is an effective method to produce ceramic coatings on magnesium alloys and can considerably improve their corrosion resistance. The coating properties are closely related with microcracks, which are always inevitably developed on the coating surface. In order to find out the formation and development regularity of microcracks, anodic coatings developed on two-phase AZ91HP after different anodizing times were fabricated in a solution containing environmentally friendly organic electrolyte phytic acid. The results show that anodic film is initially developed on the α phase. At 50 s, anodic coatings begin to develop on the β phase, evidencing the formation of a rough area. Due to the coating successive development, the microcracks initially appear at the boundary between the initially formed coating on the α phase and the subsequently developed coating on the β phase. With the prolonging treatment time, the microcracks near the β phase become evident. After treating for 3 min, the originally rough area on the β phase disappears and the coatings become almost uniform with microcracks randomly distributed on the sample surface. Inorganic phosphates are found in MAO coatings, suggesting that phytate salts are decomposed due to the high instantaneous temperature on the sample surface resulted from spark discharge.

Hydration and dehydration cycles in polymer electrolyte fuel cells operated with wet anode and dry cathode feed: A neutron imaging and modeling study

NASA Astrophysics Data System (ADS)

García-Salaberri, P. A.; Sánchez, D. G.; Boillat, P.; Vera, M.; Friedrich, K. A.

2017-08-01

Proper water management plays an essential role in the performance and durability of Polymer Electrolyte Fuel Cells (PEFCs), but it is challenged by the variety of water transport phenomena that take place in these devices. Previous experimental work has shown the existence of fluctuations between low and high current density levels in PEFCs operated with wet hydrogen and dry air feed. The alternation between both performance states is accompanied by strong changes in the high frequency resistance, suggesting a cyclic hydration and dehydration of the membrane. This peculiar scenario is examined here considering liquid water distributions from neutron imaging and predictions from a 3D two-phase non-isothermal model. The results show that the hydration-dehydration cycles are triggered by the periodic condensation and shedding of liquid water at the anode inlet. The input of liquid water humidifies the anode channel and offsets the membrane dry-out induced by the dry air stream, thus leading to the high-performance state. When liquid water is flushed out of the anode channel, the dehydration process takes over, and the cell comes back to the low-performance state. The predicted amplitude of the current oscillations grows with decreasing hydrogen and increasing air flow rates, in agreement with previous experimental data.

Infiltrated La0.4Sr0.4Fe0.03Ni0.03Ti0.94O3 based anodes for all ceramic and metal supported solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Nielsen, Jimmi; Persson, Åsa H.; Sudireddy, Bhaskar R.; Irvine, John T. S.; Thydén, Karl

2017-12-01

For improved robustness, durability and to avoid severe processing challenges alternatives to the Ni:YSZ composite electrode is highly desirable. The Ni:YSZ composite electrode is conventionally used for solid oxide fuel cell and solid oxide electrolysis cell. In the present study we report on high performing nanostructured Ni:CGO electrocatalyst coated A site deficient Lanthanum doped Strontium Titanate (La0.4Sr0.4Fe0.03Ni0.03Ti0.94O3) based anodes. The anodes were incorporated into the co-sintered DTU metal supported solid oxide fuel cell design and large sized 12 cm × 12 cm cells were fabricated. The titanate material showed good processing characteristics and surface wetting properties towards the Ni:CGO electrocatalyst coating. The cell performances were evaluated on single cell level (active area 16 cm2) and a power density at 0.7 V and 700 °C of 0.650 Wcm-2 with a fuel utilization of 31% was achieved. Taking the temperature into account the performances of the studied anodes are among the best reported for redox stable and corrosion resistant alternatives to the conventional Ni:YSZ composite solid oxide cell electrode.

Enhancing substrate utilization and power production of a microbial fuel cell with nitrogen-doped carbon aerogel as cathode catalyst.

PubMed

Tardy, Gábor Márk; Lóránt, Bálint; Lóka, Máté; Nagy, Balázs; László, Krisztina

2017-07-01

Catalytic efficiency of a nitrogen-doped, mesoporous carbon aerogel cathode catalyst was investigated in a two-chambered microbial fuel cell (MFC) applying graphite felt as base material for cathode and anode, utilizing peptone as carbon source. This mesoporous carbon aerogel containing catalyst layer on the cathode increased the maximum power density normalized to the anode volume to 2.7 times higher compared to the maximum power density obtained applying graphite felt cathode without the catalyst layer. At high (2 and 3) cathode/anode volume ratios, maximum power density exceeded 40 W m -3 . At the same time, current density and specific substrate utilization rate increased by 58% resulting in 31.9 A m -3 and 18.8 g COD m -3  h -1 , respectively (normalized to anode volume). Besides the increase of the power and the rate of biodegradation, the investigated catalyst decreased the internal resistance from the range of 450-600 to 350-370 Ω. Although Pt/C catalyst proved to be more efficient, a considerable decrease in the material costs might be achieved by substituting it with nitrogen-doped carbon aerogel in MFCs. Such cathode still displays enhanced catalytic effect.

Genetic and Genomic Architecture of the Evolution of Resistance to Antifungal Drug Combinations

PubMed Central

Hill, Jessica A.; Ammar, Ron; Torti, Dax; Nislow, Corey; Cowen, Leah E.

2013-01-01

The evolution of drug resistance in fungal pathogens compromises the efficacy of the limited number of antifungal drugs. Drug combinations have emerged as a powerful strategy to enhance antifungal efficacy and abrogate drug resistance, but the impact on the evolution of drug resistance remains largely unexplored. Targeting the molecular chaperone Hsp90 or its downstream effector, the protein phosphatase calcineurin, abrogates resistance to the most widely deployed antifungals, the azoles, which inhibit ergosterol biosynthesis. Here, we evolved experimental populations of the model yeast Saccharomyces cerevisiae and the leading human fungal pathogen Candida albicans with azole and an inhibitor of Hsp90, geldanamycin, or calcineurin, FK506. To recapitulate a clinical context where Hsp90 or calcineurin inhibitors could be utilized in combination with azoles to render resistant pathogens responsive to treatment, the evolution experiment was initiated with strains that are resistant to azoles in a manner that depends on Hsp90 and calcineurin. Of the 290 lineages initiated, most went extinct, yet 14 evolved resistance to the drug combination. Drug target mutations that conferred resistance to geldanamycin or FK506 were identified and validated in five evolved lineages. Whole-genome sequencing identified mutations in a gene encoding a transcriptional activator of drug efflux pumps, PDR1, and a gene encoding a transcriptional repressor of ergosterol biosynthesis genes, MOT3, that transformed azole resistance of two lineages from dependent on calcineurin to independent of this regulator. Resistance also arose by mutation that truncated the catalytic subunit of calcineurin, and by mutation in LCB1, encoding a sphingolipid biosynthetic enzyme. Genome analysis revealed extensive aneuploidy in four of the C. albicans lineages. Thus, we identify molecular determinants of the transition of azole resistance from calcineurin dependence to independence and establish multiple mechanisms by which resistance to drug combinations evolves, providing a foundation for predicting and preventing the evolution of drug resistance. PMID:23593013

Detection de la fin de la compaction des anodes par le son

NASA Astrophysics Data System (ADS)

Sanogo, Bazoumana

L'objectif de ce projet etait de developper un outil de controle en temps reel du temps de compaction en se servant du son genere par le vibrocompacteur pendant le formage des anodes crues. Ainsi, une application a ete developpee pour l'analyse des sons enregistres. Des essais ont ete realises avec differents microphones pour une meilleure qualite des mesures et un a ete choisi pour la suite du projet. De meme, differents tests ont ete realises sur des anodes de laboratoire ainsi que des anodes a l'echelle industrielle afin de mettre en place une methode pour la detection du temps optimal necessaire au formage des anodes. Les travaux au laboratoire de carbone a l'Universite du Quebec a Chicoutimi (UQAC) ont consiste a l'enregistrement de son des anodes fabriquees sur place avec differentes configurations; et a la caracterisation de certaines anodes de l'usine. Les anodes fabriquees au laboratoire sont reparties en deux groupes. Le premier regroupe les anodes pour la validation de notre methode. Ce sont des anodes produites avec des temps de compaction differents. Le laboratoire de carbone a l'UQAC est unique et il est possible de produire des anodes avec les memes proprietes que celles des anodes industrielles. Par consequent, la validation initialement prevue a l'usine a ete effectuee avec les anodes de laboratoire. Le deuxieme groupe a servi a etudier les effets des matieres premieres sur le temps de compaction. Le type de coke et le type de brai ont constitue les differentes variations dans ce deuxieme groupe. Quant aux tests et mesures a l'usine, ils ont ete realises en trois campagnes de mesure. La premiere campagne en juin 2014 a servi a standardiser et a trouver le meilleur positionnement des appareils pour les mesures, a regler le logiciel et a faire les premieres mesures. Une deuxieme campagne en mai 2015 a fait l'objet d'enregistrement de son en classant les anodes selon differents temps de compaction. La troisieme et derniere campagne en decembre 2015 a ete le lieu de tests finaux a l'usine en fabriquant des anodes avec differents criteres (variation du temps de compaction, taux de brai, arret manuel du compacteur, variation de la pression des ballons du haut du compacteur). Ces anodes ont ete ensuite analysees au laboratoire a l'UQAC. En parallele a ces travaux precites, l'amelioration de l'application d'analyse du son a ete faite avec le choix des parametres d'analyse et leur standardisation. Les resultats des premiers tests au laboratoire et ceux de la campagne de juin 2014 ont montre que la formation des anodes se fait suivant trois etapes : rearrangement des particules et du brai, compaction et consolidation et enfin la finition. Ces travaux ont montre en outre que le temps de compaction joue un role tres important dans la definition des proprietes finales des anodes. Ainsi, en plus du type de brai, du taux de brai et du type de coke, il faut tenir compte du temps de sur-compaction et de sous-compaction. En effet, ceci a ete demontre a travers les deux validations qui ont ete realisees. Les resultats de la caracterisation des echantillons (venant des anodes de la campagne de decembre 2015) ont montre qu'une anode compactee a un temps optimal acquiert une bonne resistance a la compression et sa resistivite electrique baisse. En outre, on note que le temps de compaction dans notre cas a baisse legerement avec l'augmentation de la pression des ballons de haut du vibrocompacteur. Ce qui a eu pour effet d'augmenter la densite crue de l'anode. Toutefois, il faut s'abstenir de generaliser ce constat car le nombre d'anodes testees est faible dans notre cas. Par ailleurs, cette etude montre que le temps necessaire pour le formage d'une anode croit avec l'augmentation du taux de brai et baisse legerement avec l'augmentation de la pression des ballons. (Abstract shortened by ProQuest.).

Design of an electrochemical prototype to determine relative NaCl content and its application in fresh cheeses

USDA-ARS?s Scientific Manuscript database

An electrochemical prototype (ECP) was designed and validated to determine NaCl electrical variables [volt (V), ampere (A), resistance (R), and power (P)] and its application for detection of possible adulteration in fresh cheeses. The ECP circuit consisted of two electrodes, aluminum (anode) and c...

Genome-Wide Identification and Mapping of NBS-Encoding Resistance Genes in Solanum tuberosum Group Phureja

PubMed Central

Lozano, Roberto; Ponce, Olga; Ramirez, Manuel; Mostajo, Nelly; Orjeda, Gisella

2012-01-01

The majority of disease resistance (R) genes identified to date in plants encode a nucleotide-binding site (NBS) and leucine-rich repeat (LRR) domain containing protein. Additional domains such as coiled-coil (CC) and TOLL/interleukin-1 receptor (TIR) domains can also be present. In the recently sequenced Solanum tuberosum group phureja genome we used HMM models and manual curation to annotate 435 NBS-encoding R gene homologs and 142 NBS-derived genes that lack the NBS domain. Highly similar homologs for most previously documented Solanaceae R genes were identified. A surprising ∼41% (179) of the 435 NBS-encoding genes are pseudogenes primarily caused by premature stop codons or frameshift mutations. Alignment of 81.80% of the 577 homologs to S. tuberosum group phureja pseudomolecules revealed non-random distribution of the R-genes; 362 of 470 genes were found in high density clusters on 11 chromosomes. PMID:22493716

Interfacial Reactivity Benchmarking of the Sodium Ion Conductors Na3PS4 and Sodium β-Alumina for Protected Sodium Metal Anodes and Sodium All-Solid-State Batteries.

PubMed

Wenzel, Sebastian; Leichtweiss, Thomas; Weber, Dominik A; Sann, Joachim; Zeier, Wolfgang G; Janek, Jürgen

2016-10-05

The interfacial stability of solid electrolytes at the electrodes is crucial for an application of all-solid-state batteries and protected electrodes. For instance, undesired reactions between sodium metal electrodes and the solid electrolyte form charge transfer hindering interphases. Due to the resulting large interfacial resistance, the charge transfer kinetics are altered and the overvoltage increases, making the interfacial stability of electrolytes the limiting factor in these systems. Driven by the promising ionic conductivities of Na 3 PS 4 , here we explore the stability and viability of Na 3 PS 4 as a solid electrolyte against metallic Na and compare it to that of Na-β″-Al 2 O 3 (sodium β-alumina). As expected, Na-β″-Al 2 O 3 is stable against sodium, whereas Na 3 PS 4 decomposes with an increasing overall resistance, making Na-β″-Al 2 O 3 the electrolyte of choice for protected sodium anodes and all-solid-state batteries.

Fabrication of Si negative electrodes for Li-ion batteries (LIBs) using cross-linked polymer binders.

PubMed

Jang, Suk-Yong; Han, Sien-Ho

2016-12-19

Currently, Si as an active material for LIBs has been attracting much attention due to its high theoretical specific capacity (3572 mAh g -1 ). However, a disadvantage when using a Si negative electrode for LIBs is the abrupt drop of its capabilities during the cycling process. Therefore, there have been a few studies of polymers such as poly(vinylidene fluoride) (PVdF), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR) and polyacrylic acid (PAA) given that the robust structure of a polymeric binder to LIBs anodes is a promising means by which to enhance the performance of high-capacity anodes. These studies essentially focused mainly on modifying of the linear-polymer component or on copolymers dissolved in solvents. Cross-linking polymers as a binder may be preferred due to their good scratch resistance, excellent chemical resistance and high levels of adhesion and resilience. However, because these types of polymers (with a rigid structure and cross-linking points) are also insoluble in general organic solvents, applying these types in this capacity is virtually impossible.

Experimental and analytical analysis of polarization and water transport behaviors of hydrogen alkaline membrane fuel cell

NASA Astrophysics Data System (ADS)

Huo, Sen; Zhou, Jiaxun; Wang, Tianyou; Chen, Rui; Jiao, Kui

2018-04-01

Experimental test and analytical modeling are conducted to investigate the operating behavior of an alkaline electrolyte membrane (AEM) fuel cell fed by H2/air (or O2) and explore the effect of various operating pressures on the water transfer mechanism. According to the experimental test, the cell performance is greatly improved through increasing the operating pressure gradient from anode to cathode which leads to significant liquid water permeation through the membrane. The high frequency resistance of the A901 alkaline membrane is observed to be relatively stable as the operating pressure varies based on the electrochemical impedance spectroscopy (EIS) method. Correspondingly, based on the modeling prediction, the averaged water content in the membrane electrode assembly (MEA) does not change too much which leads to the weak variation of membrane ohmic resistance. This reveals that the performance enhancement should give the credit to better electro-chemical reaction kinetics for both the anode and cathode, also prone by the EIS results. The reversion of water back diffusion direction across the membrane is also observed through analytical solution.

Contribution of Resistance-Nodulation-Division Efflux Pump Operon smeU1-V-W-U2-X to Multidrug Resistance of Stenotrophomonas maltophilia ▿

PubMed Central

Chen, Chao-Hsien; Huang, Chiang-Ching; Chung, Tsao-Chuen; Hu, Rouh-Mei; Huang, Yi-Wei; Yang, Tsuey-Ching

2011-01-01

KJ09C, a multidrug-resistant mutant of Stenotrophomonas maltophilia KJ, was generated by in vitro selection with chloramphenicol. The multidrug-resistant phenotype of KJ09C was attributed to overexpression of a resistance nodulation division (RND)-type efflux system encoded by an operon consisting of five genes: smeU1, smeV, smeW, smeU2, and smeX. Proteins encoded by smeV, smeW, and smeX were similar to the membrane fusion protein, RND transporter, and outer membrane protein, respectively, of known RND-type systems. The proteins encoded by smeU1 and smeU2 were found to belong to the family of short-chain dehydrogenases/reductases. Mutant KJ09C exhibited increased resistance to chloramphenicol, quinolones, and tetracyclines and susceptibility to aminoglycosides; susceptibility to β-lactams and erythromycin was not affected. The expression of the smeU1-V-W-U2-X operon was regulated by the divergently transcribed LysR-type regulator gene smeRv. Overexpression of the SmeVWX pump contributed to the acquired resistance to chloramphenicol, quinolones, and tetracyclines. Inactivation of smeV and smeW completely abolished the activity of the SmeVWX pump, whereas inactivation of smeX alone decreased the activity of the SmeVWX pump. The enhanced aminoglycoside susceptibility observed in KJ09C resulted from SmeX overexpression. PMID:21930878

Phase III Advanced Anodes and Cathodes Utilized in Energy Efficient Aluminum Production Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

R.A. Christini; R.K. Dawless; S.P. Ray

2001-11-05

During Phase I of the present program, Alcoa developed a commercial cell concept that has been estimated to save 30% of the energy required for aluminum smelting. Phase ii involved the construction of a pilot facility and operation of two pilots. Phase iii of the Advanced Anodes and Cathodes Program was aimed at bench experiments to permit the resolution of certain questions to be followed by three pilot cells. All of the milestones related to materials, in particular metal purity, were attained with distinct improvements over work in previous phases of the program. NiO additions to the ceramic phase andmore » Ag additions to the Cu metal phase of the cermet improved corrosion resistance sufficiently that the bench scale pencil anodes met the purity milestones. Some excellent metal purity results have been obtained with anodes of the following composition: Further improvements in anode material composition appear to be dependent on a better understanding of oxide solubilities in molten cryolite. For that reason, work was commissioned with an outside consultant to model the MeO - cryolite systems. That work has led to a better understanding of which oxides can be used to substitute into the NiO-Fe2O3 ceramic phase to stabilize the ferrites and reduce their solubility in molten cryolite. An extensive number of vertical plate bench electrolysis cells were run to try to find conditions where high current efficiencies could be attained. TiB2-G plates were very inconsistent and led to poor wetting and drainage. Pure TiB2 did produce good current efficiencies at small overlaps (shadowing) between the anodes and cathodes. This bench work with vertical plate anodes and cathodes reinforced the importance of good cathode wetting to attain high current efficiencies. Because of those conclusions, new wetting work was commissioned and became a major component of the research during the third year of Phase III. While significant progress was made in several areas, much work needs to be done. The anode composition needs further improvements to attain commercial purity targets. At the present corrosion rate, the vertical plate anodes will wear too rapidly leading to a rapidly increasing anode-cathode gap and thermal instabilities in the cell. Cathode wetting as a function of both cathode plate composition and bath composition needs to be better understood to ensure that complete drainage of the molten aluminum off the plates occurs. Metal buildup appears to lead to back reaction and low current efficiencies.« less

Draft Genome Sequence of Ezakiella peruensis Strain M6.X2, a Human Gut Gram-Positive Anaerobic Coccus.

PubMed

Diop, Awa; Diop, Khoudia; Tomei, Enora; Raoult, Didier; Fenollar, Florence; Fournier, Pierre-Edouard

2018-03-01

We report here the draft genome sequence of Ezakiella peruensis strain M6.X2 T The draft genome is 1,672,788 bp long and harbors 1,589 predicted protein-encoding genes, including 26 antibiotic resistance genes with 1 gene encoding vancomycin resistance. The genome also exhibits 1 clustered regularly interspaced short palindromic repeat region and 333 genes acquired by horizontal gene transfer. Copyright © 2018 Diop et al.

Scanning probes for lithography: Manipulation and devices

NASA Astrophysics Data System (ADS)

Rolandi, Marco

2005-11-01

Scanning probes are relatively low cost equipment that can push the limit of lithography in the nanometer range, with the advantages of high resolution, accuracy in the positioning of the overlayers and no proximity aberrations. We have developed three novel scanning probe lithography (SPL) resists based on thin films of Titanium, Molybdenum and Tungsten and we have manipulated single walled carbon nanotubes using the sharp tip of an atomic force microscope (AFM) for the fabrication of nanostructures. A dendrimer-passivated Ti film was imaged in the positive and the negative tone using SPL. This is the first example of SPL imaging in both tones using a unique resist. Positive tone patterning was obtained by locally scribing the dendrimer molecules and subsequent acid etch of the deprotected Ti film. Local anodic oxidation transforms Ti into TiO2 and deposits a thin layer of amorphous carbon on the patterned areas. This is very resistive to base etch and affords negative tone imaging of the Ti surface. Molybdenum and Tungsten were patterned using local anodic oxidation. This scheme is particularly flexible thanks to the solubility in water of the fully oxidized states of the two metals. We will present the facile fabrication of several nanostructures such as of trenches, dots wires and nanoelectrodes and show the potential of this scheme for competing with conventional lithographic techniques based on radiation. Quasi one dimensional electrodes for molecular electronics applications were also fabricated by creating nanogaps in single walled carbon nanotubes. The tubes, connected to microscopic contacts, were controllably cut via local anodic oxidation using the tip of the AFM. This technique leads to nanoscopic carboxyl terminated wires to which organic molecules can be linked using covalent chemistry. This geometry is particularly useful for the high gate efficiency without the need of a thin gate dielectric and the stability of the junction. Room temperature and low temperature measurements were performed and show single electron transistor behavior for the molecular junction.

Plasmid-Encoded Transferable mecB-Mediated Methicillin Resistance in Staphylococcus aureus

PubMed Central

van Alen, Sarah; Idelevich, Evgeny A.; Schleimer, Nina; Seggewiß, Jochen; Mellmann, Alexander; Kaspar, Ursula; Peters, Georg

2018-01-01

During cefoxitin-based nasal screening, phenotypically categorized methicillin-resistant Staphylococcus aureus (MRSA) was isolated and tested negative for the presence of the mecA and mecC genes as well as for the SCCmec-orfX junction region. The isolate was found to carry a mecB gene previously described for Macrococcus caseolyticus but not for staphylococcal species. The gene is flanked by β-lactam regulatory genes similar to mecR, mecI, and blaZ and is part of an 84.6-kb multidrug-resistance plasmid that harbors genes encoding additional resistances to aminoglycosides (aacA-aphD, aphA, and aadK) as well as macrolides (ermB) and tetracyclines (tetS). This further plasmidborne β-lactam resistance mechanism harbors the putative risk of acceleration or reacceleration of MRSA spread, resulting in broad ineffectiveness of β-lactams as a main therapeutic application against staphylococcal infections. PMID:29350135

Note: Triggering behavior of a vacuum arc plasma source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lan, C. H., E-mail: lanchaohui@163.com; Long, J. D.; Zheng, L.

2016-08-15

Axial symmetry of discharge is very important for application of vacuum arc plasma. It is discovered that the triggering method is a significant factor that would influence the symmetry of arc discharge at the final stable stage. Using high-speed multiframe photography, the transition processes from cathode-trigger discharge to cathode-anode discharge were observed. It is shown that the performances of the two triggering methods investigated are quite different. Arc discharge triggered by independent electric source can be stabilized at the center of anode grid, but it is difficult to achieve such good symmetry through resistance triggering. It is also found thatmore » the triggering process is highly correlated to the behavior of emitted electrons.« less

MultiLayer solid electrolyte for lithium thin film batteries

DOEpatents

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

2015-07-28

A lithium metal thin-film battery composite structure is provided that includes a combination of a thin, stable, solid electrolyte layer [18] such as Lipon, designed in use to be in contact with a lithium metal anode layer; and a rapid-deposit solid electrolyte layer [16] such as LiAlF.sub.4 in contact with the thin, stable, solid electrolyte layer [18]. Batteries made up of or containing these structures are more efficient to produce than other lithium metal batteries that use only a single solid electrolyte. They are also more resistant to stress and strain than batteries made using layers of only the stable, solid electrolyte materials. Furthermore, lithium anode batteries as disclosed herein are useful as rechargeable batteries.

Optical and magnetic properties of porous anodic alumina/Ni nanocomposite films

NASA Astrophysics Data System (ADS)

Zhang, Jing-Jing; Li, Zi-Yue; Zhang, Zhi-Jun; Wu, Tian-Shan; Sun, Hui-Yuan

2013-06-01

A simple method to tune the optical properties of porous anodic alumina (PAA) films embedded with Ni is reported. The films display highly saturated colors after being synthesized by an ac electrodeposition method. The optical properties of the samples can be effectively tuned by varying the oxidation time of aluminum. The ultrashort Ni nanowires (100 nm long and 50 nm in diameter) present only fcc phase and show no apparent averaged effective magnetic anisotropy. The coercivity mechanism of the Ni nanowires in our case is consistent with fanning mechanism based on a chain-of-spheres model. PAA/Ni films with structural color and magnetic properties have friability-resistant feature and can be used in many areas, including decoration, display, and multifunctional anti-counterfeiting technology.

Immune and biochemical responses in skin differ between bovine hosts genetically susceptible and resistant to the cattle tick Rhipicephalus microplus.

PubMed

Franzin, Alessandra Mara; Maruyama, Sandra Regina; Garcia, Gustavo Rocha; Oliveira, Rosane Pereira; Ribeiro, José Marcos Chaves; Bishop, Richard; Maia, Antônio Augusto Mendes; Moré, Daniela Dantas; Ferreira, Beatriz Rossetti; Santos, Isabel Kinney Ferreira de Miranda

2017-01-31

Ticks attach to and penetrate their hosts' skin and inactivate multiple components of host responses in order to acquire a blood meal. Infestation loads with the cattle tick, Rhipicephalus microplus, are heritable: some breeds carry high loads of reproductively successful ticks, whereas in others, few ticks feed and reproduce efficiently. In order to elucidate the mechanisms that result in the different outcomes of infestations with cattle ticks, we examined global gene expression and inflammation induced by tick bites in skins from one resistant and one susceptible breed of cattle that underwent primary infestations with larvae and nymphs of R. microplus. We also examined the expression profiles of genes encoding secreted tick proteins that mediate parasitism in larvae and nymphs feeding on these breeds. Functional analyses of differentially expressed genes in the skin suggest that allergic contact-like dermatitis develops with ensuing production of IL-6, CXCL-8 and CCL-2 and is sustained by HMGB1, ISG15 and PKR, leading to expression of pro-inflammatory chemokines and cytokines that recruit granulocytes and T lymphocytes. Importantly, this response is delayed in susceptible hosts. Histopathological analyses of infested skins showed inflammatory reactions surrounding tick cement cones that enable attachment in both breeds, but in genetically tick-resistant bovines they destabilized the cone. The transcription data provided insights into tick-mediated activation of basophils, which have previously been shown to be a key to host resistance in model systems. Skin from tick-susceptible bovines expressed more transcripts encoding enzymes that detoxify tissues. Interestingly, these enzymes also produce volatile odoriferous compounds and, accordingly, skin rubbings from tick-susceptible bovines attracted significantly more tick larvae than rubbings from resistant hosts. Moreover, transcripts encoding secreted modulatory molecules by the tick were significantly more abundant in larval and in nymphal salivary glands from ticks feeding on susceptible bovines. Compared with tick-susceptible hosts, genes encoding enzymes producing volatile compounds exhibit significantly lower expression in resistant hosts, which may render them less attractive to larvae; resistant hosts expose ticks to an earlier inflammatory response, which in ticks is associated with significantly lower expression of genes encoding salivary proteins that suppress host immunity, inflammation and coagulation.

A Case Study on Soil Antibiotic Resistome in an Urban Community Garden.

PubMed

Mafiz, Abdullah Ibn; Perera, Liyanage Nirasha; He, Yingshu; Zhang, Wei; Xiao, Shujie; Hao, Weilong; Sun, Shi; Zhou, Kequan; Zhang, Yifan

2018-05-29

Urban agricultural soils can be an important reservoir of antibiotic resistance and have great food safety and public health indications. This study was to investigate antibiotic-resistant bacteria and antibiotic resistance genes in urban agricultural soils using phenotypic and metagenomic tools. A total of 207 soil bacteria were recovered from 41 soil samples collected from an urban agricultural garden in Detroit, USA. The most prevalent antibiotic resistance phenotypes demonstrated by Gram-negative bacteria was the resistance to ampicillin (94.2%), followed by chloramphenicol (80.0%), cefoxitin (79.5%), gentamicin (78.4%), and ceftriaxone (71.1%). Gram-positive bacteria were all resistant to gentamicin, kanamycin, and penicillin. Genes encoding resistance to quinolone, β-lactam, and tetracycline were the most prevalent and abundant in the soil. qepA and tetA, both encoding efflux pumps, predominated in quinolone and tetracycline resistance genes tested, respectively. Positive correlation (p < 0.05) was identified among groups of antibiotic resistance genes and between antibiotic resistance genes and metal resistance genes. The data demonstrated a diverse population of antibiotic resistance in urban agricultural soils. Phenotypic determination together with soil metagenomics proved to be a valuable tool to study the nature and extent of antibiotic resistance in the environment. Copyright © 2018. Published by Elsevier B.V.

In vitro corrosion behavior of cast iron-platinum magnetic alloys.

PubMed

Watanabe, I; Hai, K; Tanaka, Y; Hisatsune, K; Atsuta, M

2001-05-01

The objective of this study was to investigate the corrosion resistance of cast Fe-Pt alloys of varying compositions for use as attachment keepers and to make a comparison with the corrosion resistance of magnetic stainless steel. The corrosion behavior of cast Fe-Pt alloy keepers (Fe-40 at%Pt, Fe-38 at%Pt, Fe-37 at%Pt and Fe-36 at%Pt) was evaluated by means of an immersion test and an anodic polarization test. The solutions used were a 1.0% lactic acid aqueous solution (pH=2.3) (10 ml) and 0.9% NaCl solution (pH=7.3) (10 ml). As a control, the corrosion resistance of a magnetic stainless steel keeper (SUS 447J1: HICOREX) was also measured. Chromium and platinum ions were not detected in either the 1.0% lactic acid or 0.9% NaCl solutions. The only released ions detected were the Fe ions in the 1.0% lactic acid solution. The amounts of Fe ions released from the Fe-40 at%Pt and Fe-38 at%Pt alloys were significantly (p<0.05) lower than from the Fe-37at%Pt, Fe-36 at%Pt and SUS 447J1 alloys. In the anodic polarization test, the potentials at the beginning of passivation for the four Fe-Pt alloys were higher than for the SUS 447J1 alloy in both solutions. The Fe-Pt alloys, especially the alloys with higher Pt percentages (Fe-40 and 38 at%Pt), indicated a high corrosion resistance compared to the magnetic stainless steel keeper. A reduction in the Pt percentage may decrease the corrosion resistance in the oral environment.

Preparation of functional layers for anode-supported solid oxide fuel cells by the reverse roll coating process

NASA Astrophysics Data System (ADS)

Mücke, R.; Büchler, O.; Bram, M.; Leonide, A.; Ivers-Tiffée, E.; Buchkremer, H. P.

The roll coating technique represents a novel method for applying functional layers to solid oxide fuel cells (SOFCs). This fast process is already used for mass production in other branches of industry and offers a high degree of automation. It was utilized for coating specially developed anode (NiO + 8YSZ, 8YSZ: 8 mol% yttria-stabilized zirconia) and electrolyte (8YSZ) suspensions on green and pre-sintered tape-cast anode supports (NiO + 8YSZ). The layers formed were co-fired in a single step at 1400 °C for 5 h. As a result, the electrolyte exhibited a thickness of 14-18 μm and sufficient gas tightness. Complete cells with a screen-printed and sintered La 0.65Sr 0.3MnO 3- δ (LSM)/8YSZ cathode yielded a current density of 0.9-1.1 A cm -2 at 800 °C and 0.7 V, which is lower than the performance of non-co-fired slip-cast or screen-printed Jülich standard cells with thinner anode and electrolyte layers. The contribution of the cell components to the total area-specific resistance (ASR) was calculated by analyzing the distribution function of the relaxation times (DRTs) of measured electrochemical impedance spectra (EIS) and indicates the potential improvement in the cell performance achievable by reducing the thickness of the roll-coated layers. The results show that the anode-supported planar half-cells can be fabricated cost-effectively by combining roll coating with subsequent co-firing.

Epidemiology and Characteristics of Metallo-β-Lactamase-Producing Pseudomonas aeruginosa

PubMed Central

Bae, Il Kwon; Jang, In-Ho; Kang, Hyun-Kyung; Lee, Kyungwon

2015-01-01

Metallo-β-lactamase-producing Pseudomonas aeruginosa (MPPA) is an important nosocomial pathogen that shows resistance to all β-lactam antibiotics except monobactams. There are various types of metallo-β-lactamases (MBLs) in carbapenem-resistant P. aeruginosa including Imipenemase (IMP), Verona integron-encoded metallo-β-lactamase (VIM), Sao Paulo metallo-β-lactamase (SPM), Germany imipenemase (GIM), New Delhi metallo-β-lactamase (NDM), Florence imipenemase (FIM). Each MBL gene is located on specific genetic elements including integrons, transposons, plasmids, or on the chromosome, in which they carry genes encoding determinants of resistance to carbapenems and other antibiotics, conferring multidrug resistance to P. aeruginosa. In addition, these genetic elements are transferable to other Gram-negative species, increasing the antimicrobial resistance rate and complicating the treatment of infected patients. Therefore, it is essential to understand the epidemiology, resistance mechanism, and molecular characteristics of MPPA for infection control and prevention of a possible global health crisis. Here, we highlight the characteristics of MPPA. PMID:26157586

Outlier Resistant Predictive Source Encoding for a Gaussian Stationary Nominal Source.

DTIC Science & Technology

1987-09-18

breakdown point and influence function . The proposed sequence of predictive encoders attains strictly positive breakdown point and uniformly bounded... influence function , at the expense of increased mean difference-squared distortion and differential entropy, at the Gaussian nominal source.

Optimizing membrane electrode assembly of direct methanol fuel cells for portable power

NASA Astrophysics Data System (ADS)

Liu, Fuqiang

Direct methanol fuel cells (DMFCs) for portable power applications require high power density, high-energy conversion efficiency and compactness. These requirements translate to fundamental properties of high methanol oxidation and oxygen reduction kinetics, as well as low methanol and water crossover. In this thesis a novel membrane electrode assembly (MEA) for direct methanol fuel cells has been developed, aiming to improve these fundamental properties. Firstly, methanol oxidation kinetics has been enhanced and methanol crossover has been minimized by proper control of ionomer crystallinity and its swelling in the anode catalyst layer through heat-treatment. Heat-treatment has a major impact on anode characteristics. The short-cured anode has low ionomer crystallinity, and thus swells easily when in contact with methanol solution to create a much denser anode structure, giving rise to higher methanol transport resistance than the long-cured anode. Variations in interfacial properties in the anode catalyst layer (CL) during cell conditioning were also characterized, and enhanced kinetics of methanol oxidation and severe limiting current phenomenon were found to be caused by a combination of interfacial property variations and swelling of ionomer over time. Secondly, much effort has been expended to develop a cathode CL suitable for operation under low air stoichiometry. The effects of fabrication procedure, ionomer content, and porosity distribution on the microstructure and cathode performance under low air stoichiometry are investigated using electrochemical and surface morphology characterizations to reveal the correlation between microstructure and electrochemical behavior. At the same time, computational fluid dynamics (CFD) models of DMFC cathodes have been developed to theoretically interpret the experimental results, to investigate two-phase transport, and to elucidate mechanism of cathode mixed potential due to methanol crossover. Thirdly, a MEA with low water crossover has been developed by employing a highly-hydrophobic microporous layer (MPL) to build up hydraulic pressure at the cathode, promoting product water permeation from the cathode to anode to offset water dragged by electro-osmosis. Water crossover through the MEA is further reduced by an anode hydrophobic MPL through facilitating water back diffusion. Under different current densities, the MEA with hydrophobic MPL has consistently low alpha, several times smaller than those with hydrophilic or without MPL. A simulation study of anode water transport by a two-phase model shows that anode MPL wettability strongly determines liquid saturation in the anode, and thus is identified as playing a crucial role in promoting water back diffusion. Finally, direct feed of highly-concentrated methanol using the optimized MEA has been successfully demonstrated by a face-feed anode plate, which minimizes methanol crossover by controlling the fuel delivery rate. Using 10 M methanol, a steady-state power density of ˜67mW/cm2 is reached at 60°C and 175mA/cm2, which is almost identical to that with 2M methanol.

Micro-size spherical TiO2(B) secondary particles as anode materials for high-power and long-life lithium-ion batteries

NASA Astrophysics Data System (ADS)

Takami, Norio; Harada, Yasuhiro; Iwasaki, Takuya; Hoshina, Keigo; Yoshida, Yorikazu

2015-01-01

Electrochemical properties of micro-size spherical TiO2(B) secondary particles have been investigated in order to develop TiO2(B) anodes for lithium-ion batteries with high-power and long-life performance. The spherical TiO2(B) electrodes with a small amount of a carbon conductor additive had a high electrode density of 2.2 g cm-3 and a volumetric reversible capacity of 475 mAh cm-3 comparable to that of graphite electrodes. Compared with nano-size needle-like TiO2(B) electrodes, the spherical TiO2(B) electrodes exhibited higher-rate discharge capability and longer-cycle life performance. The impedance of the TiO2(B)/electrolyte interface model indicated that the charge transfer resistance Rc and the passivating film resistance Rf of the spherical TiO2(B) were much smaller than those of the needle-like one. The high-rate discharge and the long-cycle performance of the spherical TiO2(B) electrode are attributed to the superior electronic connective property and Rc and Rf values smaller than those of the needle-like one. Lithium-ion cells using the spherical TiO2(B) anodes and LiNi0.8Co0.1Mn0.1O2 cathode with a capacity of 2.8 Ah exhibited a high energy density of 100 Wh kg-1, a high output power density of 1800 W kg-1 for 10 s pulse, and a long cycle life of more than 3000 cycles.

Spatial nonuniformity in resistive-switching memory effects of NiO.

PubMed

Oka, Keisuke; Yanagida, Takeshi; Nagashima, Kazuki; Kanai, Masaki; Kawai, Tomoji; Kim, Jin-Soo; Park, Bae Ho

2011-08-17

Electrically driven resistance change phenomenon in metal/NiO/metal junctions, so-called resistive switching (RS), is a candidate for next-generation universal nonvolatile memories. However, the knowledge as to RS mechanisms is unfortunately far from comprehensive, especially the spatial switching location, which is crucial information to design reliable devices. In this communication, we demonstrate the identification of the spatial switching location of bipolar RS by introducing asymmetrically passivated planar NiO nanowire junctions. We have successfully identified that the bipolar RS in NiO occurs near the cathode rather than the anode. This trend can be interpreted in terms of an electrochemical redox model based on ion migration and p-type conduction.

Improvement of diamond-like carbon electrochemical corrosion resistance by addition of nanocrystalline diamond.

PubMed

Marciano, F R; Almeida, E C; Bonetti, L F; Corat, E J; Trava-Airoldi, V J

2010-02-15

Nanocrystalline diamond (NCD) particles were incorporated into diamond-like carbon (DLC) films in order to investigate NCD-DLC electrochemical corrosion resistance. The films were grown over 304 stainless steel using plasma-enhanced chemical vapor deposition. NCD particles were incorporated into DLC during the deposition process. The investigation of NCD-DLC electrochemical corrosion behavior was performed using potentiodynamic polarization against NaCl. NCD-DLC films presented more negative corrosion potential and lower anodic and cathodic current densities. The electrochemical analysis indicated that NCD-DLC films present superior impedance and polarization resistance compared to the pure DLC, which indicate that they are promising corrosion protective coatings in aggressive solutions. Copyright 2009 Elsevier Inc. All rights reserved.

Spatial Heterogeneities and Onset of Passivation Breakdown at Lithium Anode Interfaces

DOE PAGES

Leung, Kevin; Jungjohann, Katherine L.

2017-09-08

Effective passivation of lithium metal surfaces, and prevention of battery-shorting lithium dendrite growth, are critical for implementing lithium metal anodes for batteries with increased power densities. Nanoscale surface heterogeneities can be “hot spots” where anode passivation breaks down. Motivated by the observation of lithium dendrites in pores and grain boundaries in all-solid batteries, we examine lithium metal surfaces covered with Li 2O and/or LiF thin films with grain boundaries in them. Electronic structure calculations show that at >0.25 V computed equilibrium overpotential Li 2O grain boundaries with sufficiently large pores can accommodate Li0 atoms which aid e– leakage and passivationmore » breakdown. Strain often accompanies Li insertion; applying an ~1.7% strain already lowers the computed overpotential to 0.1 V. Lithium metal nanostructures as thin as 12 Å are thermodynamically favored inside cracks in Li 2O films, becoming “incipient lithium filaments”. LiF films are more resistant to lithium metal growth. Finally, the models used herein should in turn inform passivating strategies in all-solid-state batteries.« less

Electricity production and benzene removal from groundwater using low-cost mini tubular microbial fuel cells in a monitoring well.

PubMed

Chang, Shih-Hsien; Wu, Chih-Hung; Wang, Ruei-Cyun; Lin, Chi-Wen

2017-05-15

A low-cost mini tubular microbial fuel cell (MFC) was developed for treating groundwater that contained benzene in monitoring wells. Experimental results indicate that increasing the length and density, and reducing the size of the char particles in the anode effectively reduced the internal resistance. Additionally, a thinner polyvinyl alcohol (PVA) hydrogel separator and PVA with a higher molecular weight improved electricity generation. The optimal parameters for the MFC were an anode density of 1.22 g cm -3 , a coke of 150 μm, an anode length of 6 cm, a PVA of 105,600 g mol -1 , and a separator thickness of 1 cm. Results of continuous-flow experiments reveal that the increasing the sets of MFCs and connecting them in parallel markedly improved the degradation of benzene. More than 95% of benzene was removed and electricity of 38 mW m -2 was generated. The MFC ran continuously up to 120 days without maintenance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous carbon and nitrogen removal using an oxic/anoxic-biocathode microbial fuel cells coupled system.

PubMed

Xie, Shan; Liang, Peng; Chen, Yang; Xia, Xue; Huang, Xia

2011-01-01

A coupled microbial fuel cell (MFC) system comprising of an oxic-biocathode MFC (O-MFC) and an anoxic-biocathode MFC (A-MFC) was implemented for simultaneous removal of carbon and nitrogen from a synthetic wastewater. The chemical oxygen demand (COD) of the influent was mainly reduced at the anodes of the two MFCs; ammonium was oxidized to nitrate in the O-MFC's cathode, and nitrate was electrochemically denitrified in the A-MFC's cathode. The coupled MFC system reached power densities of 14 W/m(3) net cathodic compartment (NCC) and 7.2 W/m(3) NCC for the O-MFC and the A-MFC, respectively. In addition, the MFC system obtained a maximum COD, NH(4)(+)-N and TN removal rate of 98.8%, 97.4% and 97.3%, respectively, at an A-MFC external resistance of 5 Ω, a recirculation ratio (recirculated flow to total influent flow) of 2:1, and an influent flow ratio (O-MFC anode flow to A-MFC anode flow) of 1:1. Copyright © 2010 Elsevier Ltd. All rights reserved.

Corrosion behavior of high-nickel and chromium alloys in natural Baltic seawater

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birn, J.; Janik-Czachor, M.; Wolowik, A.

Effect of Cl{sup {minus}} ion concentration (O M sodium chloride [NaCl] to 2 M NaCl) and temperature (25 C to 75 C) on stability of the passive state of high-Ni and Cr alloys: NI-1 ({approximately} 16% Mo), CR-2 ({approximately} 6.2% Mo), and NI-3 (3.5% Mo) were investigated in acidic and neutral electrolytes in strictly controlled electrochemical conditions. The anodic behavior of the alloys appeared to depend mostly upon Mo content in the alloy. Thus, the NI-1 was the most stable alloy under the applied experimental conditions. The other alloys were also quite resistant, undergoing pitting only at elevated temperatures, atmore » high anodic potentials, and at a chloride concentration not lower than 1 M. In natural Baltic seawater, these alloys did not exhibit any tendency to pitting, in qualitative agreement with the accelerated electrochemical tests. Complementary microscopic and surface analytical (AES) investigations were carried out to correlate the anodic and corrosion behavior of these materials with their composition and structure, and the composition of the passivating films formed at their surfaces.« less

Optical properties of anodically degraded ZnO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Messerschmidt, Daniel, E-mail: daniel.messerschmidt@bosch.com; Gnehr, Wolf-Michael; Eberhardt, Jens

2014-03-07

We discuss the optical properties of non-degraded and anodically degraded boron-doped zinc oxide (ZnO:B) deposited by low-pressure chemical vapour deposition on soda-lime glass. The optical model used to simulate the infrared reflectance in the wavelength range between 1.2 and 25 μm is based on the Maxwell-Garnett effective-medium theory. The model is sensitive to the conditions at the grain boundaries of the investigated polycrystalline ZnO:B films. We confirm that the presence of defect-rich grain boundaries, especially after degradation, causes a highly resistive ZnO:B film. Furthermore, indications of a degraded zinc oxide layer next to the ZnO:B/glass interface with different refractive index aremore » found. We present evidence for the creation of oxygen vacancies, based on Raman investigations, which correlate with a shift of the optical absorption edge of the ZnO:B. Investigations with scanning and transmission electron microscopy show microvoids at the grain boundaries after anodic degradation. This indicates that the grain/grain interfaces are the principle location of defects after degradation.« less

The effect of fluoroethylene carbonate additive content on the formation of the solid-electrolyte interphase and capacity fade of Li-ion full-cell employing nano Si-graphene composite anodes

NASA Astrophysics Data System (ADS)

Bordes, Arnaud; Eom, KwangSup; Fuller, Thomas F.

2014-07-01

When fluoroethylene carbonate (FEC) is added to the ethylene carbonate (EC)-diethyl carbonate (DEC) electrolyte, the capacity and cyclability of full-cells employing Si-graphene anode and lithium nickel cobalt aluminum oxide cathode (NCA) cathode are improved due to formation of a thin (30-50 nm) SEI layer with low ionic resistance (∼2 ohm cm2) on the surface of Si-graphene anode. These properties are confirmed with electrochemical impedance spectroscopy and a cross-sectional image analysis using Focused Ion Beam (FIB)-SEM. Approximately 5 wt.% FEC in EC:DEC (1:1 wt.%) shows the highest capacity and most stability. This high capacity and low capacity fade is attributed to a more stable SEI layer containing less CH2OCO2Li, Li2CO3 and LiF compounds, which consume cyclable Li. Additionally, a greater amount of polycarbonate (PC), which is known to form a more robust passivation layer, thus reducing further reduction of electrolyte, is confirmed with X-ray photoelectron spectroscopy (XPS).

Structural, optical and electrical properties of CeO2 thin films simultaneously prepared by anodic and cathodic electrodeposition

NASA Astrophysics Data System (ADS)

Yang, Yumeng; Du, Xiaoqing; Yi, Chenxi; Liu, Jiao; Zhu, Benfeng; Zhang, Zhao

2018-05-01

CeO2 thin films were deposited on stainless steel (SS) and indium tin oxide (ITO)-coated glass by simultaneous anodic and cathodic electrodeposition, and the influence of negative potential on the formation of ceria films was studied with scanning electron microscopy, X-ray diffraction, Raman spectroscopy, van der Pauw measurements, UV-visible spectroscopy and X-ray photoelectron spectroscopy. The results show that CeO2 films on the anode are slightly affected by the potential, but the particle size, crystal orientation, strain, film thickness, resistivity and Ce(III) content of the films on the cathode increases with increasing potential on the SS substrate. Contradictory to the results of the SS cathode, redshift (Ed changed from 3.95 eV to 3.56 eV and Ei changed from 3.42 eV to 3.04 eV) occurring in the absorption spectrum of CeO2 deposited on the ITO-coated glass cathode indicates that the content of Ce3+ in the cathodic films is dependent on the adopted substrates and decreases as the applied potential is increased.

Can CO-tolerant Anodes be Economically Viable for PEMFC Applications with Reformates?

DOE PAGES

He, P.; Zhang, Y.; Ye., S.; ...

2014-10-05

Several years ago, the answer to this question was negative based on the criteria for an anode with <0.1 mg cm-2 of platinum group metals to perform similarly without and with 50 ppm CO in hydrogen proton exchange membrane fuel cells (PEMFCs). Now, with the amount of CO impurities reduced to 10 ppm in reformates, a <1% performance loss with a 1.5% air-bleed has become a reasonable target. The CO-tolerant catalyst also needs to be dissolution resistant up to 0.93 V, viz., the potential experienced at the anode during startup and shutdown of the fuel cells. We recently demonstrated ourmore » ability to simultaneously enhance activity and stability by using single crystalline Ru@Pt core-shell nanocatalysts. Here, we report that the performance target with reformates was met using bilayer-thick Ru@Pt core-shell nanocatalysts with 0.047 mg cm-2 Pt and 0.024 mg cm-2 Ru loading, supporting a positive prognosis for the economically viable use of reformates in PEMFC applications.« less

Spatial Heterogeneities and Onset of Passivation Breakdown at Lithium Anode Interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leung, Kevin; Jungjohann, Katherine L.

Effective passivation of lithium metal surfaces, and prevention of battery-shorting lithium dendrite growth, are critical for implementing lithium metal anodes for batteries with increased power densities. Nanoscale surface heterogeneities can be “hot spots” where anode passivation breaks down. Motivated by the observation of lithium dendrites in pores and grain boundaries in all-solid batteries, we examine lithium metal surfaces covered with Li 2O and/or LiF thin films with grain boundaries in them. Electronic structure calculations show that at >0.25 V computed equilibrium overpotential Li 2O grain boundaries with sufficiently large pores can accommodate Li0 atoms which aid e– leakage and passivationmore » breakdown. Strain often accompanies Li insertion; applying an ~1.7% strain already lowers the computed overpotential to 0.1 V. Lithium metal nanostructures as thin as 12 Å are thermodynamically favored inside cracks in Li 2O films, becoming “incipient lithium filaments”. LiF films are more resistant to lithium metal growth. Finally, the models used herein should in turn inform passivating strategies in all-solid-state batteries.« less

Effect of stacking sequence and surface treatment on the thermal conductivity of multilayered hybrid nano-composites

NASA Astrophysics Data System (ADS)

Papanicolaou, G. C.; Pappa, E. J.; Portan, D. V.; Kotrotsos, A.; Kollia, E.

2018-02-01

The aim of the present investigation was to study the effect of both the stacking sequence and surface treatment on the thermal conductivity of multilayered hybrid nano-composites. Four types of multilayered hybrid nanocomposites were manufactured and tested: Nitinol- CNTs (carbon nanotubes)- Acrylic resin; Nitinol- Acrylic resin- CNTs; Surface treated Nitinol- CNTs- Acrylic resin and Surface treated Nitinol- Acrylic resin- CNTs. Surface treatment of Nitinol plies was realized by means of the electrochemical anodization. Surface topography of the anodized nitinol sheets was investigated through Scanning Electron Microscopy (SEM). It was found that the overall thermal response of the manufactured multilayered nano-composites was greatly influenced by both the anodization and the stacking sequence. A theoretical model for the prediction of the overall thermal conductivity has been developed considering the nature of the different layers, their stacking sequence as well as the interfacial thermal resistance. Thermal conductivity and Differential Scanning Calorimetry (DSC) measurements were conducted, to verify the predicted by the model overall thermal conductivities. In all cases, a good agreement between theoretical predictions and experimental results was found.

Block copolymer lithography of rhodium nanoparticles for high temperature electrocatalysis.

PubMed

Boyd, David A; Hao, Yong; Li, Changyi; Goodwin, David G; Haile, Sossina M

2013-06-25

We present a method for forming ordered rhodium nanostructures on a solid support. The approach makes use of a block copolymer to create and assemble rhodium chloride nanoparticles from solution onto a surface; subsequent plasma and thermal processing are employed to remove the polymer and fully convert the nanostructures to metallic rhodium. Films cast from a solution of the triblock copolymer poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) dissolved in toluene with rhodium(III) chloride hydrate were capable of producing a monolayer of rhodium nanoparticles of uniform size and interparticle spacing. The nanostructures were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. The electrocatalytic performance of the nanoparticles was investigated with AC impedance spectroscopy. We observed that the addition of the particles to a model solid oxide fuel cell anode provided up to a 14-fold improvement in the anode activity as evidenced by a decrease in the AC impedance resistance. Examination of the anode after electrochemical measurement revealed that the basic morphology and distribution of the particles were preserved.

Generation of Trichoderma atroviride mutants with constitutively activated G protein signaling by using geneticin resistance as selection marker.

PubMed

Gruber, Sabine; Omann, Markus; Rodrìguez, Carolina Escobar; Radebner, Theresa; Zeilinger, Susanne

2012-11-17

Species of the fungal genus Trichoderma are important industrial producers of cellulases and hemicellulases, but also widely used as biocontrol agents (BCAs) in agriculture. In the latter function Trichoderma species stimulate plant growth, induce plant defense and directly antagonize plant pathogenic fungi through their mycoparasitic capabilities. The recent release of the genome sequences of four mycoparasitic Trichoderma species now forms the basis for large-scale genetic manipulations of these important BCAs. Thus far, only a limited number of dominant selection markers, including Hygromycin B resistance (hph) and the acetamidase-encoding amdS gene, have been available for transformation of Trichoderma spp. For more extensive functional genomics studies the utilization of additional dominant markers will be essential. We established the Escherichia coli neomycin phosphotransferase II-encoding nptII gene as a novel selectable marker for the transformation of Trichoderma atroviride conferring geneticin resistance. The nptII marker cassette was stably integrated into the fungal genome and transformants exhibited unaltered phenotypes compared to the wild-type. Co-transformation of T. atroviride with nptII and a constitutively activated version of the Gα subunit-encoding tga3 gene (tga3Q207L) resulted in a high number of mitotically stable, geneticin-resistant transformants. Further analyses revealed a co-transformation frequency of 68% with 15 transformants having additionally integrated tga3Q207L into their genome. Constitutive activation of the Tga3-mediated signaling pathway resulted in increased vegetative growth and an enhanced ability to antagonize plant pathogenic host fungi. The neomycin phosphotransferase II-encoding nptII gene from Escherichia coli proved to be a valuable tool for conferring geneticin resistance to the filamentous fungus T. atroviride thereby contributing to an enhanced genetic tractability of these important BCAs.

vanC Cluster of Vancomycin-Resistant Enterococcus gallinarum BM4174

PubMed Central

Arias, Cesar A.; Courvalin, Patrice; Reynolds, Peter E.

2000-01-01

Glycopeptide-resistant enterococci of the VanC type synthesize UDP-muramyl-pentapeptide[d-Ser] for cell wall assembly and prevent synthesis of peptidoglycan precursors ending in d-Ala. The vanC cluster of Enterococcus gallinarum BM4174 consists of five genes: vanC-1, vanXYC, vanT, vanRC, and vanSC. Three genes are sufficient for resistance: vanC-1 encodes a ligase that synthesizes the dipeptide d-Ala-d-Ser for addition to UDP-MurNAc-tripeptide, vanXYC encodes a d,d-dipeptidase–carboxypeptidase that hydrolyzes d-Ala-d-Ala and removes d-Ala from UDP-MurNAc-pentapeptide[d-Ala], and vanT encodes a membrane-bound serine racemase that provides d-Ser for the synthetic pathway. The three genes are clustered: the start codons of vanXYC and vanT overlap the termination codons of vanC-1 and vanXYC, respectively. Two genes which encode proteins with homology to the VanS-VanR two-component regulatory system were present downstream from the resistance genes. The predicted amino acid sequence of VanRC exhibited 50% identity to VanR and 33% identity to VanRB. VanSC had 40% identity to VanS over a region of 308 amino acids and 24% identity to VanSB over a region of 285 amino acids. All residues with important functions in response regulators and histidine kinases were conserved in VanRC and VanSC, respectively. Induction experiments based on the determination of d,d-carboxypeptidase activity in cytoplasmic extracts confirmed that the genes were expressed constitutively. Using a promoter-probing vector, regions upstream from the resistance and regulatory genes were identified that have promoter activity. PMID:10817725

Aircraft Corrosion

DTIC Science & Technology

1981-08-01

protective coating between the plates, the reduction in frictional effects caused by the fluid did cause a significant reduction in fatigue life ... surface treatments for aluminum alloys , there has been a return to anodizing for new weapons systems rather than chromate conversion coatings . Both sulfuric...good alternate coating material in many applications requiring good corrosion resistance and minimal effect on fatigue properties. Only two aluminum

Evaluation of anodic behavior of commercially pure titanium in tungsten inert gas and laser welds.

PubMed

Orsi, Iara Augusta; Raimundo, Larica B; Bezzon, Osvaldo Luiz; Nóbilo, Mauro Antonio de Arruda; Kuri, Sebastião E; Rovere, Carlos Alberto D; Pagnano, Valeria Oliveira

2011-12-01

This study evaluated the resistance to corrosion in welds made with Tungsten Inert Gas (TIG) in specimens made of commercially pure titanium (cp Ti) in comparison with laser welds. A total of 15 circular specimens (10-mm diameter, 2-mm thick) were fabricated and divided into two groups: control group-cp Ti specimens (n = 5); experimental group-cp Ti specimens welded with TIG (n = 5) and with laser (n = 5). They were polished mechanically, washed with isopropyl alcohol, and dried with a drier. In the anodic potentiodynamic polarization assay, measurements were taken using a potentiostat/galvanostat in addition to CorrWare software for data acquisition and CorrView for data visualization and treatment. Three curves were made for each working electrode. Corrosion potential values were statistically analyzed by the Student's t-test. Statistical analysis showed that corrosion potentials and passive current densities of specimens welded with TIG are similar to those of the control group, and had lower values than laser welding. TIG welding provided higher resistance to corrosion than laser welding. Control specimens welded with TIG were more resistant to local corrosion initiation and propagation than those with laser welding, indicating a higher rate of formation and growth of passive film thickness on the surfaces of these alloys than on specimens welded with laser, making it more difficult for corrosion to occur. © 2011 by the American College of Prosthodontists.

CeO2-Y2O3-ZrO2 Membrane with Enhanced Molten Salt Corrosion Resistance for Solid Oxide Membrane (SOM) Electrolysis Process

NASA Astrophysics Data System (ADS)

Zou, Xingli; Li, Xin; Shen, Bin; Lu, Xionggang; Xu, Qian; Zhou, Zhongfu; Ding, Weizhong

2017-02-01

Innovative CeO2-Y2O3-ZrO2 membrane has been successfully developed and used in the solid oxide membrane (SOM) electrolysis process for green metallic materials production. The x mol pct ceria/(8- x) mol pct yttria-costabilized zirconia ( xCe(8- x)YSZ, x = 0, 1, 4, or 7) membranes have been fabricated and investigated as the membrane-based inert anodes to control the SOM electroreduction process in molten salt. The characteristics of these fabricated xCe(8- x)YSZ membranes including their corrosion resistances in molten salt and their degradation mechanisms have been systematically investigated and compared. The results show that the addition of ceria in the YSZ-based membrane can inhibit the depletion of yttrium during the SOM electrolysis, which thus makes the ceria-reinforced YSZ-based membranes possess enhanced corrosion resistances to molten salt. The ceria/yttria-costabilized zirconia membranes can also provide reasonable oxygen ion conductivity during electrolysis. Further investigation shows that the newly modified 4Ce4YSZ ceramic membrane has the potential to be used as novel inert SOM anode for the facile and sustainable production of metals/alloys/composites materials such as Si, Ti5Si3, TiC, and Ti5Si3/TiC from their metal oxides precursors in molten CaCl2.

Characterization of hierarchical α-MoO3 plates toward resistive heating synthesis: electrochemical activity of α-MoO3/Pt modified electrode toward methanol oxidation at neutral pH

NASA Astrophysics Data System (ADS)

Filippo, Emanuela; Baldassarre, Francesca; Tepore, Marco; Guascito, Maria Rachele; Chirizzi, Daniela; Tepore, Antonio

2017-05-01

The growth of MoO3 hierarchical plates was obtained by direct resistive heating of molybdenum foils at ambient pressure in the absence of any catalysts and templates. Plates synthesized after 60 min resistive heating typically grow in an single-crystalline orthorhombic structure that develop preferentially in the [001] direction, and are characterized by high resolution transmission electron microscopy, selected area diffraction pattern and Raman-scattering measurements. They are about 100-200 nm in thickness and a few tens of micrometers in length. As heating time proceeds to 80 min, plates of α-MoO3 form a branched structure. A more attentive look shows that primary plates formed at until 60 min could serve as substrates for the subsequent growth of secondary belts. Moreover, a full electrochemical characterization of α-MoO3 plates on platinum electrodes was done by cyclic voltammetric experiments, at pH 7 in phosphate buffer, to probe the activity of the proposed composite material as anode to methanol electro-oxidation. Reported results indicate that Pt MoO3 modified electrodes are appropriate to develop new an amperometric non-enzymatic sensor for methanol as well as to make anodes suitable to be used in direct methanol fuel cells working at neutral pH.

Identification of Genes Related to Fungicide Resistance in Fusarium fujikuroi

PubMed Central

Choi, Younghae; Jung, Boknam; Li, Taiying

2017-01-01

We identified two genes related to fungicide resistance in Fusarium fujikuroi through random mutagenesis. Targeted gene deletions showed that survival factor 1 deletion resulted in higher sensitivity to fungicides, while deletion of the gene encoding F-box/WD-repeat protein increased resistance, suggesting that the genes affect fungicide resistance in different ways. PMID:28781543

Addressing the Natural Antibiotic Resistome in Studies of Soil Resistance

USDA-ARS?s Scientific Manuscript database

The environment is recognized as a source and a reservoir of antibiotic resistance (AR). Many antibiotic compounds are derived from bacteria and fungi that are naturally present in the environment. These microbes carry genes encoding resistance to the antibiotic that they produce and their resistanc...

Zinc resistance within swine associated methicillin resistant Staphylococcus aureus (MRSA) isolates in the USA is associated with MLST lineage

USDA-ARS?s Scientific Manuscript database

Zinc resistance in livestock-associated methicillin resistant Staphylococcus aureus (LA-MRSA) is mediated by the czrC gene co-located with the mecA gene, encoding methicillin resistance, on the type V SCCmec element. Since the czrC gene and the mecA gene are co-located on the SCCmec element, it has ...

First Characterization of Fluoroquinolone Resistance in Streptococcus suis▿

PubMed Central

Escudero, Jose Antonio; San Millan, Alvaro; Catalan, Ana; de la Campa, Adela G.; Rivero, Estefania; Lopez, Gema; Dominguez, Lucas; Moreno, Miguel Angel; Gonzalez-Zorn, Bruno

2007-01-01

We have identified and sequenced the genes encoding the quinolone-resistance determining region (QRDR) of ParC and GyrA in fluoroquinolone-susceptible and -resistant Streptococcus suis clinical isolates. Resistance is the consequence of single point mutations in the QRDRs of ParC and GyrA and is not due to clonal spread of resistant strains or horizontal gene transfer with other bacteria. PMID:17116660

Single molecule sequencing to track plasmid diversity of hospital-associated carbapenemase-producing Enterobacteriaceae

PubMed Central

Conlan, Sean; Thomas, Pamela J.; Deming, Clayton; Park, Morgan; Lau, Anna F.; Dekker, John P.; Snitkin, Evan S.; Clark, Tyson A.; Luong, Khai; Song, Yi; Tsai, Yu-Chih; Boitano, Matthew; Gupta, Jyoti; Brooks, Shelise Y.; Schmidt, Brian; Young, Alice C.; Thomas, James W.; Bouffard, Gerard G.; Blakesley, Robert W.; Mullikin, James C.; Korlach, Jonas; Henderson, David K.; Frank, Karen M.; Palmore, Tara N.; Segre, Julia A.

2014-01-01

Public health officials have raised concerns that plasmid transfer between Enterobacteriaceae species may spread resistance to carbapenems, an antibiotic class of last resort, thereby rendering common healthcare-associated infections nearly impossible to treat. We performed comprehensive surveillance and genomic sequencing to identify carbapenem-resistant Enterobacteriaceae in the NIH Clinical Center patient population and hospital environment in order to to articulate the diversity of carbapenemase-encoding plasmids and survey the mobility of and assess the mobility of these plasmids between bacterial species. We isolated a repertoire of carbapenemase-encoding Enterobacteriaceae, including multiple strains of Klebsiella pneumoniae, Klebsiella oxytoca, Escherichia coli, Enterobacter cloacae, Citrobacter freundii, and Pantoea species. Long-read genome sequencing with full end-to-end assembly revealed that these organisms carry the carbapenem-resistance genes on a wide array of plasmids. Klebsiella pneumoniae and Enterobacter cloacae isolated simultaneously from a single patient harbored two different carbapenemase-encoding plasmids, overriding the epidemiological scenario of plasmid transfer between organisms within this patient. We did, however, find evidence supporting horizontal transfer of carbapenemase-encoding plasmids between Klebsiella pneumoniae, Enterobacter cloacae and Citrobacter freundii in the hospital environment. Our comprehensive sequence data, with full plasmid identification, challenges assumptions about horizontal gene transfer events within patients and identified wider possible connections between patients and the hospital environment. In addition, we identified a new carbapenemase-encoding plasmid of potentially high clinical impact carried by Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae and Pantoea species, from unrelated patients and the hospital environment. PMID:25232178

Widespread distribution of a tet W determinant among tetracycline-resistant isolates of the animal pathogen Arcanobacterium pyogenes.

PubMed

Billington, Stephen J; Songer, J Glenn; Jost, B Helen

2002-05-01

Tetracycline resistance is common among isolates of the animal commensal and opportunistic pathogen Arcanobacterium pyogenes. The tetracycline resistance determinant cloned from two bovine isolates of A. pyogenes was highly similar at the DNA level (92% identity) to the tet(W) gene, encoding a ribosomal protection tetracycline resistance protein, from the rumen bacterium Butyrivibrio fibrisolvens. The tet(W) gene was found in all 20 tetracycline-resistant isolates tested, indicating that it is a widely distributed determinant of tetracycline resistance in this organism. In 25% of tetracycline-resistant isolates, the tet(W) gene was associated with a mob gene, encoding a functional mobilization protein, and an origin of transfer, suggesting that the determinant may be transferable to other bacteria. In fact, low-frequency transfer of tet(W) was detected from mob+ A. pyogenes isolates to a tetracycline-sensitive A. pyogenes recipient. The mobile nature of this determinant and the presence of A. pyogenes in the gastrointestinal tract of cattle and pigs suggest that A. pyogenes may have inherited this determinant within the gastrointestinal tracts of these animals.

A chemically stable PVD multilayer encapsulation for lithium microbatteries

NASA Astrophysics Data System (ADS)

Ribeiro, J. F.; Sousa, R.; Cunha, D. J.; Vieira, E. M. F.; Silva, M. M.; Dupont, L.; Goncalves, L. M.

2015-10-01

A multilayer physical vapour deposition (PVD) thin-film encapsulation method for lithium microbatteries is presented. Lithium microbatteries with a lithium cobalt oxide (LiCoO2) cathode, a lithium phosphorous oxynitride (LiPON) electrolyte and a metallic lithium anode are under development, using PVD deposition techniques. Metallic lithium film is still the most common anode on this battery technology; however, it presents a huge challenge in terms of material encapsulation (lithium reacts with almost any materials deposited on top and almost instantly begins oxidizing in contact with atmosphere). To prove the encapsulation concept and perform all the experiments, lithium films were deposited by thermal evaporation technique on top of a glass substrate, with previously patterned Al/Ti contacts. Three distinct materials, in a multilayer combination, were tested to prevent lithium from reacting with protection materials and atmosphere. These multilayer films were deposited by RF sputtering and were composed of lithium phosphorous oxide (LiPO), LiPON and silicon nitride (Si3N4). To complete the long-term encapsulation after breaking the vacuum, an epoxy was applied on top of the PVD multilayer. In order to evaluate oxidation state of lithium films, the lithium resistance was measured in a four probe setup (cancelling wires/contact resistances) and resistivity calculated, considering physical dimensions. A lithium resistivity of 0.16 Ω μm was maintained for more than a week. This PVD multilayer exonerates the use of chemical vapour deposition (CVD), glove-box chambers and sample manipulation between them, significantly reducing the fabrication cost, since battery and its encapsulation are fabricated in the same PVD chamber.

Transcranial Direct Current Brain Stimulation Increases Ability to Resist Smoking.

PubMed

Falcone, Mary; Bernardo, Leah; Ashare, Rebecca L; Hamilton, Roy; Faseyitan, Olufunsho; McKee, Sherry A; Loughead, James; Lerman, Caryn

2016-01-01

The ability to exert self-control over temptation is a fundamental component of smoking behavior change. Transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) has been shown to modulate cognitive control circuits. Although prior studies show that stimulation reduces cigarette craving and self-reported smoking, effects on ability to resist smoking have not been investigated directly. We assessed effects of a single 20-minute session of 1.0 mA anodal stimulation over the left DLPFC with cathodal stimulation over the right supra-orbital area (vs. sham stimulation) on ability to resist smoking in a validated smoking lapse paradigm. Twenty-five participants completed two tDCS sessions (active and sham stimulation) in a within-subject, double-blind, randomized and counterbalanced order with a 2-week washout period. Following overnight abstinence, participants received tDCS in the presence of smoking related cues; they had the option to smoke at any time or receive $1 for every 5 minutes they abstained. After 50 minutes, they participated in a 1 hour ad libitum smoking session. Primary and secondary outcomes were time to first cigarette and cigarette consumption, respectively. In multiple regression models, active tDCS (compared to sham) significantly increased latency to smoke (p = 0.02) and decreased the total number of cigarettes smoked (p = 0.014) during the session. These findings suggest that acute anodal stimulation over the left DLPFC (with cathodal stimulation over the right supra-orbital area) can improve ability to resist smoking, supporting the therapeutic potential of tDCS for smoking cessation treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

Crystallization and preliminary diffraction analysis of a DsbA homologue from Wolbachia pipientis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurz, M.; Iturbe-Ormaetxe, I.; Jarrott, R.

2008-02-01

The first crystallization of a W. pipientis protein, α-DsbA1, was achieved using hanging-drop and sitting-drop vapour diffusion. α-DsbA1 is one of two DsbA homologues encoded by the Gram-negative α-proteobacterium Wolbachia pipientis, an endosymbiont that can behave as a reproductive parasite in insects and as a mutualist in medically important filarial nematodes. The α-DsbA1 protein is thought to be important for the folding and secretion of Wolbachia proteins involved in the induction of reproductive distortions. Crystals of native and SeMet α-DsbA1 were grown by vapour diffusion and belong to the monoclinic space group C2, with unit-cell parameters a = 71.4, bmore » = 49.5, c = 69.3 Å, β = 107.0° and one molecule in the asymmetric unit (44% solvent content). X-ray data were recorded from native crystals to a resolution of 2.01 Å using a copper anode and data from SeMet α-DsbA1 crystals were recorded to 2.45 Å resolution using a chromium anode.« less

Macrolide resistance and genotypic characterization of Streptococcus pneumoniae in Asian countries: a study of the Asian Network for Surveillance of Resistant Pathogens (ANSORP).

PubMed

Song, Jae-Hoon; Chang, Hyun-Ha; Suh, Ji Yoeun; Ko, Kwan Soo; Jung, Sook-In; Oh, Won Sup; Peck, Kyong Ran; Lee, Nam Yong; Yang, Yonghong; Chongthaleong, Anan; Aswapokee, Nalinee; Chiu, Cheng-Hsun; Lalitha, M K; Perera, Jennifer; Yee, Ti Teow; Kumararasinghe, Gamini; Jamal, Farida; Kamarulazaman, Adeeba; Parasakthi, Navaratnam; Van, Pham Hung; So, Thomas; Ng, Tak Keung

2004-03-01

To characterize mechanisms of macrolide resistance among Streptococcus pneumoniae from 10 Asian countries during 1998-2001. Phenotypic and genotypic characterization of the isolates and their resistance mechanisms. Of 555 isolates studied, 216 (38.9%) were susceptible, 10 (1.8%) were intermediate and 329 (59.3%) were resistant to erythromycin. Vietnam had the highest prevalence of erythromycin resistance (88.3%), followed by Taiwan (87.2%), Korea (85.1%), Hong Kong (76.5%) and China (75.6%). Ribosomal methylation encoded by erm(B) was the most common mechanism of erythromycin resistance in China, Taiwan, Sri Lanka and Korea. In Hong Kong, Singapore, Thailand and Malaysia, efflux encoded by mef(A) was the more common in erythromycin-resistant isolates. In most Asian countries except Hong Kong, Malaysia and Singapore, erm(B) was found in >50% of pneumococcal isolates either alone or in combination with mef(A). The level of erythromycin resistance among pneumococcal isolates in most Asian countries except Thailand and India was very high with MIC(90)s of >128 mg/L. Molecular epidemiological studies suggest the horizontal transfer of the erm(B) gene and clonal dissemination of resistant strains in the Asian region. Data confirm that macrolide resistance in pneumococci is a serious problem in many Asian countries.

Incorporation of Ca and P on anodized titanium surface: Effect of high current density.

PubMed

Laurindo, Carlos A H; Torres, Ricardo D; Mali, Sachin A; Gilbert, Jeremy L; Soares, Paulo

2014-04-01

This study systematically evaluated the surface and corrosion characteristics of commercially pure titanium (grade 2) modified by plasma electrolytic oxidation (PEO) with high current density. The anodization process was carried out galvanostatically (constant current density) using a solution containing calcium glycerophosphate (0.02mol/L) and calcium acetate (0.15mol/L). The current densities applied were 400, 700, 1000 and 1200mA/cm(2) for a period of 15s. Composition, crystalline structure, morphology, roughness, wettability and "in-vitro" bioactivity test in SBF of the anodized layer were evaluated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, profilometry and contact angle measurements. Corrosion properties were evaluated by open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results show that the TiO2 oxide layers present an increase of thickness, porosity, roughness, wettability, Ca/P ratio, and bioactivity, with the applied current density up to 1000mA/cm(2). Corrosion resistance also increases with applied current density. It is observed that for 1200mA/cm(2), there is a degradation of the oxide layer. In general, the results suggest that the anodized TiO2 layer with better properties is formed with an applied current of 1000mA/cm(2). Copyright © 2014 Elsevier B.V. All rights reserved.

Fabrication of silicon-based template-assisted nanoelectrode arrays and ohmic contact properties investigation.

PubMed

Bai, Anqi; Cheng, Buwen; Wang, Xiaofeng; Xue, Chunlai; Zuo, Yuhua; Wang, Qiming

2010-11-01

A convenient fabrication technology for large-area, highly-ordered nanoelectrode arrays on silicon substrate has been described here, using porous anodic alumina (PAA) as a template. The ultrathin PAA membranes were anodic oxidized utilizing a two-step anodization method, from Al film evaporated on substrate. The purposes for the use of two-step anodization were, first, improving the regularity of the porous structures, and second reducing the thickness of the membranes to 100-200 nm we desired. Then the nanoelectrode arrays were obtained by electroless depositing Ni-W alloy into the through pores of PAA membranes, making the alloy isolated by the insulating pore walls and contacting with the silicon substrates at the bottoms of pores. The Ni-W alloy was also electroless deposited at the back surface of silicon to form back electrode. Then ohmic contact properties between silicon and Ni-W alloy were investigated after rapid thermal annealing. Scanning electron microscopy (SEM) observations showed the structure characteristics, and the influence factors of fabrication effect were discussed. The current-voltage (I-V) curves revealed the contact properties. After annealing in N2 at 700 degrees C, good linear property was shown with contact resistance of 33 omega, which confirmed ohmic contacts between silicon and electrodes. These results presented significant application potential of this technology in nanosize current-injection devices in optoelectronics, microelectronics and bio-medical fields.

Density functional theory study for the enhanced sulfur tolerance of Ni catalysts by surface alloying

NASA Astrophysics Data System (ADS)

Hwang, Bohyun; Kwon, Hyunguk; Ko, Jeonghyun; Kim, Byung-Kook; Han, Jeong Woo

2018-01-01

Sulfur compounds in fuels deactivate the surface of anode materials in solid oxide fuel cells (SOFCs), which adversely affect the long-term durability. To solve this issue, it is important to design new SOFC anode materials with high sulfur tolerance. Unfortunately, it is difficult to completely replace the traditional Ni anode owing to its outstanding reactivity with low cost. As an alternative, alloying Ni with transition metals is a practical strategy to enhance the sulfur resistance while taking advantage of Ni metal. Therefore, in this study, we examined the effects of transition metal (Cu, Rh, Pd, Ag, Pt, and Au) doping into a Ni catalyst on not only the adsorption of H2S, HS, S, and H but also H2S decomposition using density functional theory (DFT) calculations. The dopant metals were selected rationally by considering the stability of the Ni-based binary alloys. The interactions between sulfur atoms produced by H2S dissociation and the surface are weakened by the dopant metals at the topmost layer. In addition, the findings show that H2S dissociation can be suppressed by doping transition metals. It turns out that these effects are maximized in the Au-doped Ni catalyst. Our DFT results will provide useful insights into the design of sulfur-tolerant SOFC anode materials.

Staphylococcus aureus nasal carriage in Ukraine: antibacterial resistance and virulence factor encoding genes.

PubMed

Netsvyetayeva, Irina; Fraczek, Mariusz; Piskorska, Katarzyna; Golas, Marlena; Sikora, Magdalena; Mlynarczyk, Andrzej; Swoboda-Kopec, Ewa; Marusza, Wojciech; Palmieri, Beniamino; Iannitti, Tommaso

2014-03-05

The number of studies regarding the incidence of multidrug resistant strains and distribution of genes encoding virulence factors, which have colonized the post-Soviet states, is considerably limited. The aim of the study was (1) to assess the Staphylococcus (S.) aureus nasal carriage rate, including Methicillin Resistant S. aureus (MRSA) strains in adult Ukrainian population, (2) to determine antibiotic resistant pattern and (3) the occurrence of Panton Valentine Leukocidine (PVL)-, Fibronectin-Binding Protein A (FnBPA)- and Exfoliative Toxin (ET)-encoding genes. Nasal samples for S. aureus culture were obtained from 245 adults. The susceptibility pattern for several classes of antibiotics was determined by disk diffusion method according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. The virulence factor encoding genes, mecA, lukS-lukF, eta, etb, etd, fnbA, were detected by Polymerase Chain Reaction (PCR). The S. aureus nasal carriage rate was 40%. The prevalence of nasal MRSA carriage in adults was 3.7%. LukS-lukF genes were detected in over 58% of the strains. ET-encoding genes were detected in over 39% of the strains and the most prevalent was etd. The fnbA gene was detected in over 59% of the strains. All MRSA isolates tested were positive for the mecA gene. LukS-lukF genes and the etd gene were commonly co-present in MRSA, while lukS-lukF genes and the fnbA gene were commonly co-present in Methicillin Sensitive S. aureus (MSSA) isolates. No significant difference was detected between the occurrence of lukS-lukF genes (P > 0.05) and the etd gene (P > 0.05) when comparing MRSA and MSSA. The occurrence of the fnbA gene was significantly more frequent in MSSA strains (P < 0.05). In Ukraine, S. aureus is a common cause of infection. The prevalence of S. aureus nasal carriage in our cohort of patients from Ukraine was 40.4%. We found that 9.1% of the strains were classified as MRSA and all MRSA isolates tested positive for the mecA gene. We also observed a high prevalence of PVL- and ET- encoding genes among S. aureus nasal carriage strains. A systematic surveillance system can help prevent transmission and spread of drug resistant toxin producing S. aureus strains.

Genetic Manipulation of Lactococcus lactis by Using Targeted Group II Introns: Generation of Stable Insertions without Selection

PubMed Central

Frazier, Courtney L.; San Filippo, Joseph; Lambowitz, Alan M.; Mills, David A.

2003-01-01

Despite their commercial importance, there are relatively few facile methods for genomic manipulation of the lactic acid bacteria. Here, the lactococcal group II intron, Ll.ltrB, was targeted to insert efficiently into genes encoding malate decarboxylase (mleS) and tetracycline resistance (tetM) within the Lactococcus lactis genome. Integrants were readily identified and maintained in the absence of a selectable marker. Since splicing of the Ll.ltrB intron depends on the intron-encoded protein, targeted invasion with an intron lacking the intron open reading frame disrupted TetM and MleS function, and MleS activity could be partially restored by expressing the intron-encoded protein in trans. Restoration of splicing from intron variants lacking the intron-encoded protein illustrates how targeted group II introns could be used for conditional expression of any gene. Furthermore, the modified Ll.ltrB intron was used to separately deliver a phage resistance gene (abiD) and a tetracycline resistance marker (tetM) into mleS, without the need for selection to drive the integration or to maintain the integrant. Our findings demonstrate the utility of targeted group II introns as a potential food-grade mechanism for delivery of industrially important traits into the genomes of lactococci. PMID:12571038

A Different Microbiome Gene Repertoire in the Airways of Cystic Fibrosis Patients with Severe Lung Disease

PubMed Central

Bacci, Giovanni; Fiscarelli, Ersilia; Taccetti, Giovanni; Dolce, Daniela; Paganin, Patrizia; Morelli, Patrizia; Tuccio, Vanessa; De Alessandri, Alessandra; Lucidi, Vincenzina

2017-01-01

In recent years, next-generation sequencing (NGS) was employed to decipher the structure and composition of the microbiota of the airways in cystic fibrosis (CF) patients. However, little is still known about the overall gene functions harbored by the resident microbial populations and which specific genes are associated with various stages of CF lung disease. In the present study, we aimed to identify the microbial gene repertoire of CF microbiota in twelve patients with severe and normal/mild lung disease by performing sputum shotgun metagenome sequencing. The abundance of metabolic pathways encoded by microbes inhabiting CF airways was reconstructed from the metagenome. We identified a set of metabolic pathways differently distributed in patients with different pulmonary function; namely, pathways related to bacterial chemotaxis and flagellar assembly, as well as genes encoding efflux-mediated antibiotic resistance mechanisms and virulence-related genes. The results indicated that the microbiome of CF patients with low pulmonary function is enriched in virulence-related genes and in genes encoding efflux-mediated antibiotic resistance mechanisms. Overall, the microbiome of severely affected adults with CF seems to encode different mechanisms for the facilitation of microbial colonization and persistence in the lung, consistent with the characteristics of multidrug-resistant microbial communities that are commonly observed in patients with severe lung disease. PMID:28758937

Graphite anode surface modification with controlled reduction of specific aryl diazonium salts for improved microbial fuel cells power output.

PubMed

Picot, Matthieu; Lapinsonnière, Laure; Rothballer, Michael; Barrière, Frédéric

2011-10-15

Graphite electrodes were modified with reduction of aryl diazonium salts and implemented as anodes in microbial fuel cells. First, reduction of 4-aminophenyl diazonium is considered using increased coulombic charge density from 16.5 to 200 mC/cm(2). This procedure introduced aryl amine functionalities at the surface which are neutral at neutral pH. These electrodes were implemented as anodes in "H" type microbial fuel cells inoculated with waste water, acetate as the substrate and using ferricyanide reduction at the cathode and a 1000 Ω external resistance. When the microbial anode had developed, the performances of the microbial fuel cells were measured under acetate saturation conditions and compared with those of control microbial fuel cells having an unmodified graphite anode. We found that the maximum power density of microbial fuel cell first increased as a function of the extent of modification, reaching an optimum after which it decreased for higher degree of surface modification, becoming even less performing than the control microbial fuel cell. Then, the effect of the introduction of charged groups at the surface was investigated at a low degree of surface modification. It was found that negatively charged groups at the surface (carboxylate) decreased microbial fuel cell power output while the introduction of positively charged groups doubled the power output. Scanning electron microscopy revealed that the microbial anode modified with positively charged groups was covered by a dense and homogeneous biofilm. Fluorescence in situ hybridization analyses showed that this biofilm consisted to a large extent of bacteria from the known electroactive Geobacter genus. In summary, the extent of modification of the anode was found to be critical for the microbial fuel cell performance. The nature of the chemical group introduced at the electrode surface was also found to significantly affect the performance of the microbial fuel cells. The method used for modification is easy to control and can be optimized and implemented for many carbon materials currently used in microbial fuel cells and other bioelectrochemical systems. Copyright © 2011 Elsevier B.V. All rights reserved.

Multidrug-resistant Salmonella enterica serovar Typhimurium isolates are resistant to antibiotics that influence their swimming and swarming motility

USDA-ARS?s Scientific Manuscript database

Motile bacteria utilize one or more strategies for movement, such as darting, gliding, sliding, swarming, swimming, and twitching. The ability to move is considered a virulence factor in many pathogenic bacteria, including Salmonella. Multidrug-resistant (MDR) Salmonella encodes acquired factors t...

Improved Anode for a Direct Methanol Fuel Cell

NASA Technical Reports Server (NTRS)

Valdez, Thomas; Narayanan, Sekharipuram

2005-01-01

A modified chemical composition has been devised to improve the performance of the anode of a direct methanol fuel cell. The main feature of the modified composition is the incorporation of hydrous ruthenium oxide into the anode structure. This modification can reduce the internal electrical resistance of the cell and increase the degree of utilization of the anode catalyst. As a result, a higher anode current density can be sustained with a smaller amount of anode catalyst. These improvements can translate into a smaller fuel-cell system and higher efficiency of conversion. Some background information is helpful for understanding the benefit afforded by the addition of hydrous ruthenium oxide. The anode of a direct methanol fuel cell sustains the electro-oxidation of methanol to carbon dioxide in the reaction CH3OH + H2O--->CO2 + 6H(+) + 6e(-). An electrocatalyst is needed to enable this reaction to occur. The catalyst that offers the highest activity is an alloy of approximately equal numbers of atoms of the noble metals platinum and ruthenium. The anode is made of a composite material that includes high-surface-area Pt/Ru alloy particles and a proton-conducting ionomeric material. This composite is usually deposited onto a polymer-electrolyte (proton-conducting) membrane and onto an anode gas-diffusion/current-collector sheet that is subsequently bonded to the proton-conducting membrane by hot pressing. Heretofore, the areal density of noble-metal catalyst typically needed for high performance has been about 8 mg/cm2. However, not all of the catalyst has been utilized in the catalyzed electro-oxidation reaction. Increasing the degree of utilization of the catalyst would make it possible to improve the performance of the cell for a given catalyst loading and/or reduce the catalyst loading (thereby reducing the cost of the cell). The use of carbon and possibly other electronic conductors in the catalyst layer has been proposed for increasing the utilization of the catalyst by increasing electrical connectivity between catalyst particles. However, the relatively low density of carbon results in thick catalyst layers that impede the mass transport of methanol to the catalytic sites. Also, the electrical conductivity of carbon is less than 1/300th of typical metals. Furthermore, the polymer-electrolyte membrane material is acidic and most metals are not chemically stable in contact with it. Finally, a material that conducts electrons (but not protons) does not contribute to the needed transport of protons produced in the electro-oxidation reaction.

Tin doped PrBaFe 2O 5+δ anode material for solid oxide fuel cells

DOE PAGES

Dong, Guohui; Yang, Chunyang; He, Fei; ...

2017-04-25

Ceramic anodes have many advantages over cermet anodes for solid oxide fuel cells. We report the synthesis and characterization of Sn doped double perovskite PrBaFe (2-x)Sn xO 5+δ (x = 0–0.3) anode materials. Different crystal structures were observed depending on the Sn doping level and gas atmosphere. The materials demonstrated excellent stability in both reducing and redox atmospheres at elevated temperatures. The oxygen content in the as-prepared PrBaFe (2-x)Sn xO 5+δ was nonlinearly correlated to the Sn doping level and reached maximum values around x = 0.1. After the reducing treatment, the oxygen content linearly decreased with increasing Sn dopingmore » level. The electrical conductivity of bulk PrBaFe (2-x)Sn xO 5+δ (x = 0.1) reached 63.6 S cm -1 at 800 °C in humidified hydrogen. At 750 °C, the surface exchange coefficient and bulk diffusivity of PrBaFe (2-x)Sn xO 5+δ reached the maximum values of 4.42 × 10 -6 m s -1 and 6.04 × 10 -7 m 2 s -1, respectively, in the reducing process when the Sn doping level was x = 0.1. The activation energies of surface exchange coefficient and bulk diffusivity of PrBaFe (2-x)Sn xO 5+δ (x = 0.1) were 0.22 eV and 0.16 eV, respectively, in the reducing process. The area specific resistance of the PrBaFe (2-x)Sn xO 5+δ (x = 0.1) anode was 0.095–0.285 Ω cm 2 from 850–750 °C in humidified hydrogen, better than or comparable to the best ceramic anodes in the literature.« less

Gene encoding a deubiquitinating enzyme is mutated in artesunate- and chloroquine-resistant rodent malaria parasites.

PubMed

Hunt, Paul; Afonso, Ana; Creasey, Alison; Culleton, Richard; Sidhu, Amar Bir Singh; Logan, John; Valderramos, Stephanie G; McNae, Iain; Cheesman, Sandra; do Rosario, Virgilio; Carter, Richard; Fidock, David A; Cravo, Pedro

2007-07-01

Artemisinin- and artesunate-resistant Plasmodium chabaudi mutants, AS-ART and AS-ATN, were previously selected from chloroquine-resistant clones AS-30CQ and AS-15CQ respectively. Now, a genetic cross between AS-ART and the artemisinin-sensitive clone AJ has been analysed by Linkage Group Selection. A genetic linkage group on chromosome 2 was selected under artemisinin treatment. Within this locus, we identified two different mutations in a gene encoding a deubiquitinating enzyme. A distinct mutation occurred in each of the clones AS-30CQ and AS-ATN, relative to their respective progenitors in the AS lineage. The mutations occurred independently in different clones under drug selection with chloroquine (high concentration) or artesunate. Each mutation maps to a critical residue in a homologous human deubiquitinating protein structure. Although one mutation could theoretically account for the resistance of AS-ATN to artemisinin derivates, the other cannot account solely for the resistance of AS-ART, relative to the responses of its sensitive progenitor AS-30CQ. Two lines of Plasmodium falciparum with decreased susceptibility to artemisinin were also selected. Their drug-response phenotype was not genetically stable. No mutations in the UBP-1 gene encoding the P. falciparum orthologue of the deubiquitinating enzyme were observed. The possible significance of these mutations in parasite responses to chloroquine or artemisinin is discussed.

Gene encoding a deubiquitinating enzyme is mutated in artesunate- and chloroquine-resistant rodent malaria parasites§

PubMed Central

Hunt, Paul; Afonso, Ana; Creasey, Alison; Culleton, Richard; Sidhu, Amar Bir Singh; Logan, John; Valderramos, Stephanie G; McNae, Iain; Cheesman, Sandra; do Rosario, Virgilio; Carter, Richard; Fidock, David A; Cravo, Pedro

2007-01-01

Artemisinin- and artesunate-resistant Plasmodium chabaudi mutants, AS-ART and AS-ATN, were previously selected from chloroquine-resistant clones AS-30CQ and AS-15CQ respectively. Now, a genetic cross between AS-ART and the artemisinin-sensitive clone AJ has been analysed by Linkage Group Selection. A genetic linkage group on chromosome 2 was selected under artemisinin treatment. Within this locus, we identified two different mutations in a gene encoding a deubiquitinating enzyme. A distinct mutation occurred in each of the clones AS-30CQ and AS-ATN, relative to their respective progenitors in the AS lineage. The mutations occurred independently in different clones under drug selection with chloroquine (high concentration) or artesunate. Each mutation maps to a critical residue in a homologous human deubiquitinating protein structure. Although one mutation could theoretically account for the resistance of AS-ATN to artemisinin derivates, the other cannot account solely for the resistance of AS-ART, relative to the responses of its sensitive progenitor AS-30CQ. Two lines of Plasmodium falciparum with decreased susceptibility to artemisinin were also selected. Their drug-response phenotype was not genetically stable. No mutations in the UBP-1 gene encoding the P. falciparum orthologue of the deubiquitinating enzyme were observed. The possible significance of these mutations in parasite responses to chloroquine or artemisinin is discussed. PMID:17581118

Performance of μ-RWELL detector vs resistivity of the resistive stage

NASA Astrophysics Data System (ADS)

Bencivenni, G.; De Oliveira, R.; Felici, G.; Gatta, M.; Morello, G.; Ochi, A.; Lener, M. Poli; Tskhadadze, E.

2018-04-01

The μ-RWELL is a compact spark-protected single amplification stage Micro-Pattern-Gaseous-Detector (MPGD). The detector amplification stage is realized with a polyimide structure, micro-patterned with a dense matrix of blind-holes, integrated into the readout structure. The anode is formed by a thin Diamond Like Carbon (DLC) resistive layer separated by an insulating glue layer from the readout strips. The introduction of the resistive layer strongly suppressing the transition from streamer to spark gives the possibility to achieve large gains (> 104), without significantly affecting the capability to be efficiently operated in high particle fluxes. In this work we present the results of a systematic study of the μ-RWELL performance as a function of the DLC resistivity. The tests have been performed either with collimated 5.9 keV X-rays or with pion and muon beams at the SPS Secondary Beamline H4 and H8 at CERN.

Corrosion sensor for monitoring the service condition of chloride-contaminated cement mortar.

PubMed

Lu, Shuang; Ba, Heng-Jing

2010-01-01

A corrosion sensor for monitoring the corrosion state of cover mortar was developed. The sensor was tested in cement mortar, with and without the addition of chloride to simulate the adverse effects of chloride-contaminated environmental conditions on concrete structures. In brief, a linear polarization resistance method combined with an embeddable reference electrode was utilized to measure the polarization resistance (Rp) using built-in sensor electrodes. Subsequently, electrochemical impedance spectroscopy in the frequency range of 1 kHz to 50 kHz was used to obtain the cement mortar resistance (Rs). The results show that the polarization resistance is related to the chloride content and Rs; ln (Rp) is linearly related to the Rs values in mortar without added chloride. The relationships observed between the Rp of the steel anodes and the resistance of the surrounding cement mortar measured by the corrosion sensor confirms that Rs can indicate the corrosion state of concrete structures.

Study of localized corrosion in aluminum alloys by the scanning reference electrode technique

NASA Technical Reports Server (NTRS)

Danford, M. D.

1995-01-01

Localized corrosion in 2219-T87 aluminum (Al) alloy, 2195 aluminum-lithium (Al-Li) alloy, and welded 2195 Al-Li alloy (4043 filler) have been investigated using the relatively new scanning reference electrode technique (SRET). Anodic sites are more frequent and of greater strength in the 2195 Al-Li alloy than in the 2219-T87 Al alloy, indicating a greater tendency toward pitting for the latter. However, the overall corrosion rates are about the same for these two alloys, as determined using the polarization resistance technique. In the welded 2195 Al-Li alloy, the weld bean is entirely cathodic, with rather strongly anodic heat affected zones (HAZ) bordering both sides, indicating a high probability of corrosion in the HAZ parallel to the weld bead.

An in situ investigation of electromigration in Cu nanowires.

PubMed

Huang, Qiaojian; Lilley, Carmen M; Divan, Ralu

2009-02-18

Electromigration in copper (Cu) nanowires deposited by electron beam evaporation has been investigated using both resistance measurement and the in situ scanning electron microscopy technique. During electromigration, voids formed at the cathode end while hillocks (or extrusions) grew close to the anode end. The failure lifetimes were measured for various applied current densities and the mean temperature in the wire was estimated. Electromigration activation energies of 1.06 eV and 0.94 eV were found for the wire widths of 90 nm and 141 nm, respectively. These results suggest that the mass transport of Cu during electromigration mainly occurs along the wire surfaces. Further investigations of the Auger electron spectrum show that both Cu atoms and the surface contaminants of carbon and oxygen migrate from cathode to anode under the electrical stressing.

Effect of Aluminum Coating on the Surface Properties of Ti-(~49 at. pct) Ni Alloy

NASA Astrophysics Data System (ADS)

Sinha, Arijit; Khan, Gobinda Gopal; Mondal, Bholanath; Majumdar, Jyotsna Dutta; Chattopadhyay, Partha Protim

2015-08-01

Stable porous layer of mixed Al2O3 and TiO2 has been formed on the Ti-(~49 at. pct) Ni alloy surface with an aim to suppress leaching of Ni from the alloy surface in contact with bio-fluid and to enhance the process of osseointegration. Aluminum coating on the Ni-Ti alloy surface prior to the anodization treatment has resulted in enhancement of depth and uniformity of pores. Thermal oxidation of the anodized aluminum-coated Ni-Ti samples has exhibited the formation of Al2O3 and TiO2 phases with dense porous structure. The nanoindentation and nanoscratch measurements have indicated a remarkable improvement in the hardness, wear resistance, and adhesiveness of the porous aluminum-coated Ni-Ti sample after thermal oxidation.

Methicillin-Susceptible Teicoplanin-Resistant Staphylococcus haemolyticus Isolate from a Bloodstream Infection with Novel Mutations in the tcaRAB Teicoplanin Resistance Operon.

PubMed

Bakthavatchalam, Yamuna Devi; Sudarsanam, Thambu David; Babu, Priyanka; Munuswamy, Elakkiya; Muthuirulandi Sethuvel, Dhiviya Prabaa; Devanga Ragupathi, Naveen Kumar; Veeraraghavan, Balaji

2017-07-24

Staphylococcus haemolyticus is a coagulase-negative staphylococcus that is frequently isolated from blood cultures. Here, we report a case of methicillin-susceptible S. haemolyticus that is resistant to teicoplanin (TEC) and heteroresistant to vancomycin (VAN). The isolate was susceptible to cefoxitin and resistant to TEC by Etest. Population analysis profile-area under the curve analysis confirmed the presence of a VAN heteroresistant subpopulation. Next-generation sequencing analysis of the genome revealed the presence of blaZ and msr(A), which encode cross-resistance to macrolide, lincosamide, and streptogramin B, and the quinolone resistance-conferring gene norA. In addition, several amino acid substitutions were observed in the TEC resistance operon tcaRAB, including I3N, I390N, and L450I in tcaA and L44V, G52V, and S87P in tcaR, as well as in the transpeptidase encoding gene walK (D336Y, R375L, and V404A) and L315 and P316 in graS. We hypothesized that this combination of mutations could confer TEC resistance and reduced VAN susceptibility.