bluuebunny/crossref_metadata_2025 huggingface dataset:
Seek
TB, a Two-Stage Multiplex Real-Time-PCR-Based Method for Differentiation of the Mycobacterium tuberculosis Complex
Authors: Reddington Kate , Zumla Alimuddin , Bates Matthew , van Soolingen Dick , Niemann Stefan , Barry Thomas , O'Grady Justin
Published: May 2012

Tuberculosis (TB) in humans is caused by members of the
Mycobacterium tuberculosis
complex (MTC). The accurate identification of the MTC member causing human infection is important because the treatment of TB caused by some MTC members requires an alteration of the standard drug regimen, it can inform whether transmission is human to human or zoonotic, and it enables accurate epidemiology studies that help improve TB control. In this study, an internally controlled two-stage multiplex real-time PCR-based method,
Seek
TB, was developed for the accurate identification of all members of the MTC. The method was tested against a panel of well-characterized bacterial strains (
n
= 180) and determined to be 100% specific for members of the MTC. Additionally, 125 Mycobacteria Growth Indicator Tube (MGIT)-positive cultures were blindly tested by using
Seek
TB, and the results were compared to those of the GenoType MTBC and TBc ID tests. The
Seek
TB and GenoType MTBC results were 100% concordant, identifying 84 of these isolates as
M. tuberculosis
isolates and 41 as non-MTC isolates. Nine discordant results between the molecular methods and the TBc ID culture confirmation test were observed; however, nucleotide sequencing confirmed the results obtained with GenoType MTBC and
Seek
TB.
Seek
TB is the first-described internally controlled multiplex real-time PCR diagnostic method for the accurate identification of all eight members of the MTC. This method, designed for use on cultured patient samples, is specific, sensitive, and rapid, with a turnaround time to results of approximately 1.5 to 3.5 h, depending on which, if any, member of the MTC is present.
Molecular and Culture-Based Assessment of the Microbial Diversity of Diabetic Chronic Foot Wounds and Contralateral Skin Sites
Authors: Oates Angela , Bowling Frank L. , Boulton Andrew J. M. , McBain Andrew J.
Published: May 2012

Wound debridement samples and contralateral (healthy) skin swabs acquired from 26 patients attending a specialist foot clinic were analyzed by differential isolation and eubacterium-specific PCR-denaturing gradient gel electrophoresis (DGGE) in conjunction with DNA sequencing. Thirteen of 26 wounds harbored pathogens according to culture analyses, with
Staphylococcus aureus
being the most common (13/13). Candida (1/13), pseudomonas (1/13), and streptococcus (7/13) were less prevalent. Contralateral skin was associated with comparatively low densities of bacteria, and overt pathogens were not detected. According to DGGE analyses, all wounds contained significantly greater eubacterial diversity than contralateral skin (
P
< 0.05), although no significant difference in total eubacterial diversity was detected between wounds from which known pathogens had been isolated and those that were putatively uninfected. DGGE amplicons with homology to
Staphylococcus
sp. (8/13) and
S. aureus
(2/13) were detected in putatively infected wound samples, while
Staphylococcus
sp. amplicons were detected in 11/13 noninfected wounds;
S. aureus
was not detected in these samples. While a majority of skin-derived DGGE consortial fingerprints could be differentiated from wound profiles through principal component analysis (PCA), a large minority could not. Furthermore, wounds from which pathogens had been isolated could not be distinguished from putatively uninfected wounds on this basis. In conclusion, while chronic wounds generally harbored greater eubacterial diversity than healthy skin, the isolation of known pathogens was not associated with qualitatively distinct consortial profiles or otherwise altered diversity. The data generated support the utility of both culture and DGGE for the microbial characterization of chronic wounds.
Cation Concentration Variability of Four Distinct Mueller-Hinton Agar Brands Influences Polymyxin B Susceptibility Results
Authors: Girardello Raquel , Bispo Paulo J. M. , Yamanaka Tiago M. , Gales Ana C.
Published: May 2012

Polymyxins have been the only alternative therapeutic option for the treatment of serious infections caused by multidrug-resistant
Acinetobacter baumannii
or
Pseudomonas aeruginosa
isolates. For this reason, it is of crucial importance that susceptibility tests provide accurate results when testing these drug-pathogen combinations. In this study, the effect of cation concentration variability found on different commercial brands of Mueller-Hinton agar (MHA) for testing polymyxin B susceptibility was evaluated. The polymyxin B susceptibilities determined using Etest and disk diffusion were compared to those determined by the CLSI reference broth microdilution method. In general, the polymyxin B MIC values were higher when determined by Etest than when determined by broth microdilution against both
A. baumannii
and
P. aeruginosa
isolates. A high very major error rate (10%) was observed, as well as a trend toward lower MICs, compared to those determined by broth microdilution when the Merck MHA was tested by Etest. Poor essential agreement rates (10 to 70%) were observed for
P. aeruginosa
when all MHA brands were tested by Etest. Although an excellent categorical agreement rate (100%) was seen between the disk diffusion and broth microdilution methods for
P. aeruginosa
, larger zones of inhibition were shown obtained using the Merck MHA. The high cation concentration variability found for the MHA brands tested correlated to the low accuracy, and discrepancies in the polymyxin B MICs were determined by Etest method, particularly for
P. aeruginosa
isolates.
Transfer of the UAP56 Interaction Motif of Human Cytomegalovirus pUL69 to Its Murine Cytomegalovirus Homolog Converts the Protein into a Functional mRNA Export Factor That Can Substitute for pUL69 during Viral Infection
Authors: Zielke Barbara , Wagenknecht Nadine , Pfeifer Caroline , Zielke Katrin , Thomas Marco , Stamminger Thomas
Published: May 2012

Nucleocytoplasmic shuttling and interaction with the cellular mRNA export factor UAP56 are prerequisites for the mRNA export activity of human cytomegalovirus (HCMV) pUL69. Although the murine cytomegalovirus homolog pM69 shuttles, it fails to export mRNAs due to its inability to recruit UAP56. However, chimeric proteins comprising pM69 fused to N-terminal pUL69 fragments, including its UAP56 interaction motif, acquire mRNA export activity. Importantly, growth curves of recombinant HCMVs illustrate that such a chimeric protein, but not pM69, substitutes for pUL69 during HCMV infection.
Endogenous Hepadnaviruses in the Genome of the Budgerigar (Melopsittacus undulatus) and the Evolution of Avian Hepadnaviruses
Authors: Cui Jie , Holmes Edward C.
Published: May 2012

Endogenous hepadnaviruses (hepatitis B viruses [HBVs]) were recently discovered in the genomes of passerine birds. We mined six additional avian genomes and discovered multiple copies of endogenous HBVs in the budgerigar (order Psittaciformes), designated eBHBV. A phylogenetic analysis reveals that the endogenous hepadnaviruses are more diverse than their exogenous counterparts and that the endogenous and exogenous hepadnaviruses form distinct lineages even when sampled from the same avian order, indicative of multiple genomic integration events.
Immune Selection
In Vitro
Reveals Human Immunodeficiency Virus Type 1 Nef Sequence Motifs Important for Its Immune Evasion Function
In Vivo
Authors: Lewis Martha J. , Lee Patricia , Ng Hwee L. , Yang Otto O.
Published: May 2012

Human immunodeficiency virus type 1 (HIV-1) Nef downregulates major histocompatibility complex class I (MHC-I), impairing the clearance of infected cells by CD8
+
cytotoxic T lymphocytes (CTLs). While sequence motifs mediating this function have been determined by
in vitro
mutagenesis studies of laboratory-adapted HIV-1 molecular clones, it is unclear whether the highly variable Nef sequences of primary isolates
in vivo
rely on the same sequence motifs. To address this issue,
nef
quasispecies from nine chronically HIV-1-infected persons were examined for sequence evolution and altered MHC-I downregulatory function under Gag-specific CTL immune pressure
in vitro
. This selection resulted in decreased
nef
diversity and strong purifying selection. Site-by-site analysis identified 13 codons undergoing purifying selection and 1 undergoing positive selection. Of the former, only 6 have been reported to have roles in Nef function, including 4 associated with MHC-I downregulation. Functional testing of naturally occurring
in vivo
polymorphisms at the 7 sites with no previously known functional role revealed 3 mutations (A84D, Y135F, and G140R) that ablated MHC-I downregulation and 3 (N52A, S169I, and V180E) that partially impaired MHC-I downregulation. Globally, the CTL pressure
in vitro
selected functional Nef from the
in vivo
quasispecies mixtures that predominately lacked MHC-I downregulatory function at the baseline. Overall, these data demonstrate that CTL pressure exerts a strong purifying selective pressure for MHC-I downregulation and identifies novel functional motifs present in Nef sequences
in vivo
.
Hemorrhagic complications after prasugrel (Effient) therapy for vascular neurointerventional procedures
Authors: Akbari S Hassan , Reynolds Matthew R , Kadkhodayan Yasha , Cross DeWitte T , Moran Christopher J
Published: May 2012

Introduction

Dual antiplatelet therapy (DAPT) with aspirin and a thienopyridine (eg, clopidogrel) prevents stent related thromboembolic events in cardiac patients and is frequently utilized during neurointerventional surgery. However, recent data suggest that many patients exhibit clopidogrel resistance. Prasugrel—a newer thienopyridine—lowers the rate of cardiac stent thromboses in clopidogrel non-responders but a paucity of data exist regarding its safety and efficacy in neurointerventional surgery.

Methods

All patients undergoing neurointerventional surgery by a single interventionalist (CJM) over a 20 month period were retrospectively identified. Charts were reviewed for pre- and post-procedural DAPT regimens, pre-procedural coagulation parameters and procedural complications.

Results

76 patients received pre- and post-procedural DAPT for endovascular treatment of an intracerebral aneurysm, dural arteriovenous fistula or intra/extracranial arterial stenosis. 51 patients underwent 55 total procedures and were treated with aspirin/clopidogrel; 25 patients underwent 31 total procedures and were treated with aspirin/prasugrel. Those patients who received aspirin/prasugrel DAPT were identified pre-procedurally to be clopidogrel non-responders. Both treatment groups had a similar percentage of patients undergoing aneurysm coiling, stent assisted aneurysm coiling, aneurysm Onyx embolization, aneurysm pipeline embolization device treatment, extra/intracranial carotid artery angioplasty and stenting, and dural arteriovenous fistula coil embolization. A total of eight (9.3%) hemorrhagic complications were observed, two (3.6%) in the aspirin/clopidogrel group and six (19.4%) in the aspirin/prasugrel group (p=0.02). No differences were noted in hemorrhage rates for each procedure between treatment groups, nor were there any differences in thrombotic complications between groups.

Conclusion

Our results suggest that DAPT with aspirin/prasugrel may predispose to a higher risk of hemorrhage during neurointerventional surgery compared with DAPT with aspirin/clopidogrel.
STABLE SUPER-INFLATING COSMOLOGICAL SOLUTIONS IN f(R)-GRAVITY
Authors: IVANOV MIKHAIL M. , TOPORENSKY ALEXEY V.
Published: May 2012

We consider super-inflating solutions in modified gravity for several popular families of f(R) functions. Using scalar field reformulation of f(R)-gravity we describe how the form of effective scalar field potential can be used for explaining existence of stable super-inflation solutions in the theory under consideration. Several new solutions of this type have been found analytically and checked numerically.
Substratum control on tunnel-valley formation in Denmark
Authors: Sandersen Peter B. E. , Jørgensen Flemming
Published: May 2012

Tunnel valleys formed by meltwater erosion underneath the margins of the Pleistocene ice sheets are present in high numbers in the Danish onshore area. The geographical distribution of the buried tunnel valleys is uneven, but when comparing with the substrata lithology we find a large number of valleys in areas dominated by low-permeable sediment and a smaller number in areas with highly permeable substrata. The observations point to the drainage capacity of the ice-sheet substratum as an important factor controlling tunnel-valley formation. Tunnel-valley formation appears to be favoured in areas with low-permeable substrata because meltwater drainage through the sediments is impeded, leading to the formation of a channelized subglacial drainage system. The high transmissivity in areas dominated by permeable substrata facilitates drainage of a part of the meltwater as groundwater. This causes a lowering of the subglacial meltwater pressures, and tunnel-valley formation is less likely. Once formed and filled, the tunnel valleys cause a change of the hydraulic properties of the substratum and if subglacial water pressures underneath a subsequent ice advance are sufficiently high, old tunnel valleys will be prone to reactivation.
Multistage erosion and infill of buried Pleistocene tunnel valleys and associated seismic velocity effects
Authors: Kristensen T. B. , Huuse M.
Published: May 2012

This study provides results on buried tunnel valleys from the greatest number of released three-dimensional (3D) seismic surveys in the Danish North Sea sector to date. The valley infill sediments and the fluid content from buried Pleistocene tunnel valleys beneath the North Sea floor cause significant seismic velocity effects. Analysis of conventional 3D seismic data, high-resolution two-dimensional (2D) seismic data and wire-line log data from exploration wells reveal a multistage cut-and-fill history of tunnel valleys in the Danish North Sea. The seismic infill facies of the valleys is analysed and the associated velocity effects quantified. The valley infill generates both velocity pull up and push down of underlying seismic horizons. In contrast to expectations, our analysis shows no distinct correlation between particular seismic facies and a particular travel-time effect. Infill units characterized by the same seismic facies within the same valley can thus provide different travel-time effects. The anomalous velocities can be used as indicators of shallow gas and till content within the valleys leading to low and high velocities, respectively. Detailed investigations suggest that tunnel valley formation and sediment infill occurred over several episodes, with partial reuse of the kilometre-scale valleys and strong indications of ice-free periods between some of the formation episodes.
Neoproterozoic deglacial sediments and their hydrocarbon source rock potential
Authors: Le Heron Daniel Paul , Craig Jonathan
Published: May 2012

Many Neoproterozoic successions contain viable hydrocarbon source rocks, even though they were deposited before most extant life forms evolved. Eukaryotic microalgae, bacteria, chlorophyte micoalgae, marine pelagophyte algae and dinoflagellates may have contributed organic matter. Major global-scale glaciations, which are commonly attributed to a ‘snowball’ or ‘slushball’ Earth scenario, or deposited under a ‘zipper rift’ scenario, are believed to have played an important role in the deposition of hydrocarbon source rocks during the mid- Neoproterozoic (Cryogenian). Phases of Cryogenian deglaciation may have culminated in the deposition of high total organic carbon shales and ‘cap carbonates’ in restricted anoxic basins, which may have been carved by ice sheets themselves or, alternatively, formed as restricted extensional half graben as Rodinia began to fragment. One example of these organically enriched deglacial sediments comprises shales and dolostones deposited following the Sturtian glaciation in the Centralian Superbasin of Australia, an amalgam of basins that extends almost continent-wide across Australia. Data from the Marmot MMDD-1 drill core on the Stuart Shelf in the southern part of the Centralian Superbasin, together with previously published data on organic enrichment in the Amadeus Basin in the central part of the Centralian Superbasin, suggest that the deposition of organically enriched shales was widespread during the Sturtian deglaciation.
Plant Defense Against Herbivores: Chemical Aspects
Authors: Mithöfer Axel , Boland Wilhelm
Published: May 2012

Plants have evolved a plethora of different chemical defenses covering nearly all classes of (secondary) metabolites that represent a major barrier to herbivory: Some are constitutive; others are induced after attack. Many compounds act directly on the herbivore, whereas others act indirectly via the attraction of organisms from other trophic levels that, in turn, protect the plant. An enormous diversity of plant (bio)chemicals are toxic, repellent, or antinutritive for herbivores of all types. Examples include cyanogenic glycosides, glucosinolates, alkaloids, and terpenoids; others are macromolecules and comprise latex or proteinase inhibitors. Their modes of action include membrane disruption, inhibition of nutrient and ion transport, inhibition of signal transduction processes, inhibition of metabolism, or disruption of the hormonal control of physiological processes. Recognizing the herbivore challenge and precise timing of plant activities as well as the adaptive modulation of the plants' metabolism is important so that metabolites and energy may be efficiently allocated to defensive activities.
There Ought to Be an Equation for That
Authors: Berry Joseph A.
Published: May 2012

An overriding interest in photosynthesis has propelled my wanderings from chemist to biochemist to plant physiologist and on to global topics. Equations and models have been organizing principles along the way. This fascination started as a reaction to difficulties with written communication, but it has proven to be quite useful in moving across different levels of organization. I conclude with some discussion of the importance of Earth system models for understanding and predicting how human activities may influence the climate, environment, and biota in the future, and some ideas about how disciplinary science might make larger contributions to this interdisciplinary problem. (Note: Selected references are available from the Carnegie Institution Web site at http://dge.stanford.edu/publications/berry/AnnRev2012 )
Modeling of Platinum Extraction from Used Reforming Catalyst in Iodine Solutions
Authors: Rashidi Moghaddam Hamed , Baghalha Morteza
Published: May 2012

Platinum extraction from spent reforming catalysts in iodine solutions under atmospheric pressure and at temperatures up to 95 °C was previously investigated in our group. In this system, platinum is oxidized from the spent catalyst with tri-iodide. In some of the experiments, it was observed that platinum extraction peaked and then decreased. This indicates that a precipitation reaction slowly occurs that removes the dissolved Pt ions from the solution. Power-law rate equation for the Pt extraction to and the precipitation of the dissolved platinum to was implemented to model the experimental Pt extraction data. The activation energies for the platinum dissolution reaction and the precipitation reaction were calculated as 49 and 48 kJ/mol, respectively. The large values of activation energies indicate that both processes are controlled by surface chemical/electrochemical reactions. The reaction order for Pt extraction was identified as 2.82 for the Pt mass fraction in the solid catalyst and 0.43 for the hydrogen ion concentration in solution.
Electrolytic Production of (CF3)3N from Room-Temperature Molten Fluoride of (CH3)3N•3HF Using LaNiO3 Coated Ni Sheet Anode
Authors: Osawa Naoki , Saito Morihiro , Inaba Minoru , Tasaka Akimasa
Published: May 2012

The LaNiO3 coated Ni sheet anodes prepared by sol-gel coating method was developed to improve the Ni sheet anode for electrolytic synthesis of perfluorotrimethylamine, (CF3)3N, using the (CH3)3N·3HF melt as the electrolyte. The LaNiO3 films may give the electric conductivity to the Ni sheet anode during electrolysis of the (CH3)3N·3HF melt. (CF3)3N was successfully obtained at a ratio of about 62 and 55% together with other partially fluorinated gaseous products.
In Situ-Generation of Electrically Conductive Nanoparticles in Bimetallic Phosphate Materials for High Power Lithium Batteries
Authors: Marschilok Amy C. , Kim Young J. , Takeuchi Kenneth J. , Takeuchi Esther S.
Published: May 2012

Preparation, characterization, and electrochemical evaluation of two promising bimetallic electrochemical displacement materials for energy storage are described herein. The results demonstrate that the material family of silver vanadium phosphorous oxides (AgwVxPyOz) is suitable for high power applications, such as the implantable cardiac defibrillator.
Oxygen Reduction Activity of Carbon-Conductive Polymer-Silver Composite Electrodes
Authors: Marschilok Amy C. , Lee Shu Han , Milleville Christopher C. , Yau Shali Z. , Takeuchi Esther S. , Takeuchi Kenneth J.
Published: May 2012

Preparation, characterization, and electrochemical activity of a novel three-component composite electrode consisting of a carbon substrate with conductive polymer and silver coatings are described here. The composite electrode concept is described and the composite electrode is evaluated as a cathode for non-aqueous oxygen reduction. Improvement of cathode oxygen reduction activity will increase current capability and power output of metal air batteries, facilitating future development of small, lightweight, long-life power sources.
Comparison of Limiting Descriptions of the Electrical Double Layer Using a Simplified Lithium-Ion Battery Model
Authors: Marcicki James , Conlisk A.T. , Rizzoni Giorgio
Published: May 2012

This article examines the effects of various hypotheses for the electrical double layer on charge transfer in lithium-ion batteries. We begin by introducing the Poisson Nernst-Planck equations to describe ion transport within a typical liquid solvent and derive an expression for the potential difference in the electroneutral liquid of the separator. We discuss the structure of the electrical double layer and review two distinct hypotheses for interpreting the total potential difference across the electrical double layer. The limiting descriptions lead to different concentration and potential profiles and overpotential during discharge.
Physics Based Modeling of a 40 Ah Li-Ion Battery for Geosynchronous Earth Orbit Satellite Applications
Authors: Isaacson Mark J. , Spotnitz Robert
Published: May 2012

The results of a physics based model for a Li-ion cell are presented and compared to experimental data for a 40 Ah Geosynchronous Earth Orbit (GEO) Li-ion cell. The model predictions are in good agreement with experimental voltage discharge curves for both beginning of life and cycled cells. A two material positive electrode model is needed to fit the experimental discharge curves. However, only one of two known degradation mechanisms is needed to fit the data for the cycled cell.
Hard X-ray Fluorescence Measurements of Heteroepitaxial Solid Oxide Fuel Cell Cathode Materials
Authors: Davis Jacob N. , Miara Lincoln J. , Saraf Laxmikant , Kaspar Tiffany C. , Gopalan S. , Pal Uday B. , Woicik Joseph C. , Basu Soumendra N. , Ludwig Karl F.
Published: May 2012

Strontium doped lanthanum manganite (La0.8Sr0.2)0.95MnO3 (LSM) and lanthanum strontium cobalt ferrite La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) thin films were grown by pulsed laser deposition (PLD) on single crystal substrates. Total X-ray Reflection Fluorescence (TXRF) reveals the evolution of surface composition due to annealing at 800 C. X-ray Absorption Near Edge Spectroscopy (XANES) provides insight into the local electronic structure of the cations. LSM manganese concentration is higher at the surface than in the bulk in as-deposited films. Annealing further enhances surface manganese segregation and irreversibly changes the manganese XANES spectra. Surface strontium is greatly enhanced in LSCF samples quenched from 800 C, however the strontium is reabsorbed into the film when allowed to cool slowly.
Ultra Violet Irradiation of Metal Oxide Semiconductor Gas Sensors
Authors: Smith Richard , Cavanagh Leon M. , Binions Russell
Published: May 2012

Metal oxide semiconductor gas sensors are widely used for a variety of applications from pollution monitoring to medical breath analysis. One disadvantage for the use of such sensors is the relatively large power requirement that originates from the need to heat the semiconductor material in order to produce a measurable baseline resistance. The use of ultra violet light emitting diodes has been suggested as an alternative way of promoting charge carriers from the materials valence band into the conduction band. In this paper we examine the use of 360 nm ultra violet light emitting diodes as a way of activating a variety of metal oxide thick film sensors. The sensors were evaluated under a variety of irradiation and heating conditions against varying concentrations of ethanol gas. It was found that the optimum operating temperature of the thick film sensors could be dramatically reduced using this approach.
Improvement of Conductivity by Incorporation of Boron Atoms in Hydrogenated Amorphous Carbon Films Fabricated by Plasma CVD Methods and its Electrochemical Properties
Authors: Naragino Hiroshi , Yoshinaga Kosuke , Tatsuta Seiji , Honda Kensuke
Published: May 2012

Boron-doped hydrogenated amorphous carbon thin films were synthesized with plasma-enhanced CVD method. Electrochemical properties of B-doped DLC surface that can be useful in the application as an electrochemical sensor were investigated. B-doped DLC films deposited in this study possessed a B/C ratio of 0.013 and contained sp3-bonded carbons with atomic ratio of 22/78 (sp3/sp2). The electrical resistivity was 0.9147 Ω cm. B-doped DLC thin films exhibited a wide working potential range over 3 V, low double-layer capacitance, high resistance to electrochemically induced corrosion in strong acid media, and reversible electron transfer kinetics for inorganic redox analytes (Fe(CN)63-/4- and Ru(NH3)62+/3+), which were on the same level as those of BDD. The redox reaction of Ce3+/4+ with standard potential higher than H2O/O2 was observed due to the wider potential window.
Carbon Corrosion Mechanisms in Batteries during High-Rate, Partial State-of-Charge Cycling
Authors: Bullock Kathryn R.
Published: May 2012

Battery cycling profiles in hybrid electric vehicles have high currents both during charging, when the vehicle brakes are applied, and during discharging, when the vehicle accelerates. Cycle life in these high-rate, partial-state-of-charge (HRPSoC) applications is improved by adding conductive carbons with high surface areas to the negative active material. During charge, however, carbon can be oxidized by water to form soluble carbon monoxides such as formic acid. Further oxidation produces gaseous carbon dioxide at the positive electrode. As the internal cell pressure increases, it may force the vents open to release the carbon dioxide and other gases in the battery. Fortunately carbon dioxide formation is slowed by limited transport of soluble carbons from the negative to the positive plates. The valve-regulated lead-acid (VRLA) battery life is extended by carbon additions to the negative plate, but the ultimate cause of failure may become cell dry-out.
Inhibition of Cobalt Corrosion by Silane Coatings
Authors: Mabuchi Katsumi
Published: May 2012

Surface treatment by 1, 2-Bis(triethoxysilyl) ethane (BTSE) was evaluated for improving corrosion resistance of a thin cobalt film. A BTSE layer is formed on cobalt oxide by immersing the cobalt film in a liquid including hydrogen peroxide and BTSE (pre-treatment solution) and was found to significantly improve corrosion resistance of the film. When hydrogen peroxide does not coexist in the liquid, the BTSE layer is not formed. Moreover, corrosion resistance is improved by increasing the pH of the pre-treatment solution. These behaviors were examined by applying the hard and soft acid-base (HSAB) principle.
A Mechanism of Anodic Film Formation in Molten Melts Using Preformed Porous Film Formed in 0.6 M Oxalic Acid Electrolyte
Authors: Han Seong Ho , Kim Hyoung Chan
Published: May 2012

Direct interpretation of the results of the two stage anodizing procedure suggests that the film formed in the molten salt developed both at the film/electrolyte interface by aluminum ion egress and at the film/substrate interface by oxygen-containing species, O2- and/or OH-, ingress. Either at the high current density or within the geometrically high field strength region, i.e. the pore base of the preformed porous film, sulphate ions migrate inwards into the film and move in the direction normal to the film/substrate interface. The thin preformed porous film formed in aqueous electrolyte can be employed as a marker to obtain the apparent transport numbers of aluminum and oxygen-containing ions during anodizing in the molten salt.
Auger Spectra Analysis of Anodized Film Formed in Molten Melts
Authors: Han Seong Ho , Kim Hyoung Chan
Published: May 2012

Relatively thin barrier films were formed at constant current densities of 100 Am-2, 10 Am-2 and 1 Am-2, to 60 V without current decay in the molten bisulphate melts at temperatures of 418, 458 and 498 K. The anodic films formed in the molten salts are generally barrier-type, appearing featureless upon initial observation and with relatively flat film/electrolyte and film/substrate interfaces. In-depth elemental composition profiles, from Auger spectroscopy, through the barrier films, formed in the molten salt, show that the ratio of sulphur-containing species to aluminum within the film decreases with decrease of current density. This trend is also revealed in EDX analysis. Moreover, the S/Al ratios in the anodic films formed in the molten salt at different temperatures are approximately constant within the experimental error.
Surface Modifications of the Mg Alloy by Self-Assembled Monolayers of Fatty Acids
Authors: Metikoš-Huković Mirjana , Babić Ranko , Škugor Rončević Ivana , Grubač Z.
Published: May 2012

As biocompatible, osteoconductive, and degradable materials magnesium and its alloys are promising candidates for temporary implants. The main limitation of their use in the clinical application is the fast degradation in physiological environments. Several possibilities exist to tailor the degradation rate of magnesium by using alloying elements and protective coatings. In the present study the native and anodically formed oxide films on the Mg alloy (AZ91D) were modified with the self assembling monolayers (SAMs) of a long chain carboxylic acid to protect the alloy degradation in a physiological solution. Fourier transform infrared spectroscopy (FTIR), electrochemical impedance spectroscopy (EIS) and voltammetry methods were used to examine the surface layers; their structural properties and corrosion resistance in the Hanks' solution.
Electrochemical Sensing of Dopamine Using a Dodecylsulfate Doped Polypyrrole Film
Authors: Moorhead Paul B. , Breslin Carmel B.
Published: May 2012

A polymer-modified electrode was fabricated by the electropolymerisation of pyrrole from an ethanol solution using sodium dodecylsulfate as a dopant. The modified electrode is a highly sensitive electrochemical sensor for dopamine with a limit of detection measured as 3.8 x 10-8 mol dm-3. The sensor did not sense the common interferant ascorbic acid showing a single redox peak for dopamine in the presence of excess ascorbic acid.
Treatment and Recovery Of Sludge Containing Heavy Metals
Authors: Addi Yassine , Khouider Ali
Published: May 2012

This work presents the results of wastewater sludge treatment coming from a dismissed industrial site. Sludge sample was collected from an industrial site and treated with sulfuric acid to extract heavy metals (Cu, Ni, Cd and Zn) that are separated by electrodeposition. To determine the best extractive parameters we carried out a study on the effects of sulfuric acid concentration and solid to liquid ratio. To minimize power consumption during the electrodeposition, the cathode used was made in the same material as the extracted metal. In order to have deposition time as similar as possible, the cathode area used was adapted to the concentration of the respective metal. The recovery of each metal was made potentiostatically at different potentials. The results show that for 5g/L solid to liquid ratio more than 99,9% of heavy metals can be removed from the sludge by treating with 0,5M sulfuric acid in less than 2hours. The recovery of heavy metals by reduction was achieved at 99%. The solution, obtained after electrodeposition, contains metals concentrations in agreement with Algerian legislations.
Electrogenerated Chemiluminescence with Ruthenium Trisbipyridine and TATP
Authors: Shaw Alex , Calhoun Rob L.
Published: May 2012

Interaction of the explosive triacetone triperoxide (TATP) with the electrogenerated chemiluminescence (ECL) of Ru(bpy)32+ in acetonitrile was studied. The analyte greatly reduces the light made during the annihilation mechanism yielding ppb level detection. The mechanism is thought to be EEC' during reduction which reduces the light by oxidizing the Ru(bpy)3+ before it can react with Ru(bpy)33+.
The Effect of Carbon-Nanotubes on the Electrochemical Sensing Behavior of Aluminum Alloys
Authors: Yoon Yuhchae , Li Lingchuan , Shin Eunsung , Lafdi Khalid , Bouchard Michael
Published: May 2012

The use of carbon nanotubes grown on carbon fiber was used in electrochemical sensing of the aluminum alloy corrosion by open circuit potential (OCP) and electrochemical impedance spectra (EIS) measurements. In 3.5 wt% NaCl solutions, CNT enhanced the conductivity of the carbon fiber. After sputtering of the aluminum alloys on the carbon fiber and carbon-CNT, the chemical compositions of the aluminum alloys thin films were identical to the target substrates. Energy dispersive spectroscopy measurements confirmed the chemical composition of the aluminum alloy coatings. OCPs of the aluminum alloy coating on the carbon fiber and carbon-CNT were also similar to those of the bulk aluminum alloys. Dissolutions of the aluminum alloy coatings on the carbon fiber and carbon-CNT have occurred in around 40 hours and 20 hours respectively. This result suggests that CNT enhanced the dissolution of both aluminum alloy 2024 and 7075 on the carbon fiber.
Performance of Non-Aqueous Electrochemical Capacitor Utilizing Halogen Redox Reaction
Authors: Yamazaki Shigeaki , Ito Tatsuya , Yamagata Masaki , Ishikawa Masashi
Published: May 2012

We propose a novel electrochemical capacitor (EC) utilizing an "electrolytic" charge-storage system of bromide species. The present EC cell is fabricated with 1.0 mol dm-3 1-ethyl-3-methylimidazolium bromide dissolved in 1-ethyl-3-methylimidazolium tetrafluoroborate as an electrolyte and activated carbon fiber cloths as electrodes. Although such a charge-storage concept would usually be useless due to inevitable, undesirable reactions, e.g. shuttle reaction or migration of active redox species between electrodes, we attain much-enhanced capacitance with an excellent reversibility by suppressing an undesirable diffusion process. In fact, the coulombic efficiency of the present cell is over 99.7% at 100 mA g-1. The oxidation species such as Br2 or Br3- as charge accumulators do not diffuse from a positive electrode into the electrolyte. Moreover, the present EC cell has an excellent cycleability of at least 10,000 cycles.
Olivine Coated Spinel: 5-Volt System for High Energy Lithium Batteries
Authors: Liu Dongqiang , Guerfi Abdelbast , Hovington Pierre , Trottier Julie , Dontigny Martin , Charest Patrick , Zaghib Karim , Mauger Alain , Julien Christain M.
Published: May 2012

LiMn1.5Ni0.5O4 (LMN) has attracted considerable attention as 5-volt cathode materials for Li-ion batteries. Here, the coating of nano LiFePO4 (LFP) onto the surface of the spinel particles is reported for the first time. Two processes were used to prepare LFP-coated LMN: a traditional sol-gel method in Ar and a mechano-fusion dry process, which provides a simple way to obtain surface coating for battery materials. Surface elemental analyses indicate that nano-LFP is intimately covered on the LMN surface. LiMn1.5Ni0.5O4 showed better rate property especially at high rate (>10C) after LiFePO4 coating. Good performance such as 82 mAh g-1 of capacity was still obtained for the LiFePO4-coated LiMn1.5Ni0.5O4 with 75% of capacity retention after 140 cycles under 1C.
Novel LiFeTiO4 Polymorph with a Tunnel Structure: Synthesis, Structural and Electrochemical Characterization
Authors: Bruno Shaun R. , Blakely Colin K. , Poltavets Viktor V.
Published: May 2012

New polymorph modification of LiFeTiO4 with the calcium ferrite structure was prepared by low temperature ion exchange. This compound can be considered as a model system for multiple electron cycling per Fe atom, i.e. Fe2+ (Li1+xFeTiO4) / Fe4+ (Li1-xFeTiO4). The crystal structure of LiFeTiO4 was determined using Rietveld refinement (Pnma, a = 8.9498(6) Aå, b = 2.9528(6) Aå, c = 10.7457(8) Aå). LiFeTiO4 in the calcium ferrite type structure was found to be thermodynamically unstable, transforming to the known spinel LiFeTiO4 polymorph at higher temperatures.
Electrodeposition of Separated Metallic Structures in Superimposed Magnetic Gradient Fields
Authors: Tschulik Kristina , Cierpka Christian , Uhlemann Margitta , Gebert A. , Schultz L.
Published: May 2012

Structuring of Cu deposits was reported to occur during electrodeposition in magnetic gradient fields, recently. This work aims on increasing the knowledge about the convection-induced structuring mechanism. Therefore, in-situ velocity measurements by Astigmatism Particle Tracking Velocimetry were performed. The information gained by this study is used to choose pulse-reverse-plating parameters suitable for deposition of separated Cu structures. Additionally, it is demonstrated that the structure shape can be changed by varying the superimposed magnetic field gradients. The structure height can be adjusted by the number of pulse-reverse-plating cycles. The structuring mechanism is discussed for potentiostatic as well as for pulse-reverse-plating conditions with respect to the acting magnetic forces.
Characterization and Electrochemical Investigations of Polypyrrole/Aluminum Flake Composite Pigments on AA 2024-T3 Substrate
Authors: Jadhav Niteen , Vetter Christopher A. , Gelling Victoria J.
Published: May 2012

Phosphate and nitrate doped Polypyrrole (PPy)/Aluminum (Al) flake pigments were synthesized by chemical oxidative polymerization method. Coatings were formulated from the phosphate doped PPy/Al flake pigment, nitrate doped PPy/Al flake, and as received Al flakes at 20% pigment volume concentration (PVC). The anticorrosion properties of coatings on aluminum alloy (AA 2024-T3) were monitored by exposure with accelerated salt spray (ASTM B117), electrochemical impedance spectroscopy (EIS), scanning vibrating electrode technique (SVET), and anodic polarization experiments. Phosphate and nitrate doped PPy/Al flake coatings showed enhanced anticorrosion ability in comparison with as received Al flake coating as observed in accelerated salt spray test. In the anodic polarization experiments, phosphate and nitrate doped PPy/Al flake coatings exhibited a positive shift in the potential suggesting the passivation of the substrate. Additionally, SVET experiments did not detect appreciable corrosion activity for the samples demonstrating better corrosion protection ability of phosphate and nitrate doped PPy/Al flake coatings.
(Invited) Coal and Biomass Utilization in Solid Oxide Fuel Cells
Authors: Mitchell Reginald E.
Published: May 2012

Coal is used for generating electricity and it will continue to be used in this manner until non-fossil fuel based power generation technologies are commercially proven. Since carbon dioxide, a greenhouse gas, is a main product of the conversion process, it is prudent to develop technologies that facilitate its removal from exhaust streams before it is released to the atmosphere. The development of solid oxide fuel cells is a step in this direction. Converting coal or biomass to electricity in an electrochemical scheme is a more energy efficient process than converting these fuels to electricity in either a combustion or integrated gasification combined cycle scheme. The coal conversion process most compatible with SOFC applications is gasification. In this paper, issues associated with integrating gasification and SOFC technologies for power generation is discussed with attention given to syngas composition and the formation of species that have adverse impact on SOFC performance.
Solid Fuel Utilization in High Temperature Fuel Cells
Authors: Gür Turgut M.
Published: May 2012

Fuel cells offer attractive opportunities for efficient and environmentally acceptable conversion of solid carbonaceous fuels such as coal and biomass into electrical power. However, oxidation of solid fuels in fuel cells pose innate challenges. Several fuel cell configurations have been investigated. They all seek to devise the most effective manner to achieve electrochemical oxidation with minimum cell loses. This article provides an overview of different fuel cell approaches, and discusses some of the outstanding issues that stand in the way towards further development of these fuel cells.
Electrochemical Characterization of Liquid Metal Anode Solid Oxide Fuel Cell
Authors: LaBarbera Mark , Khurana Sanchit , Fedkin Mark , Lvov Serguei , Abernathy Harry , Gerdes Kirk
Published: May 2012

A liquid tin anode solid oxide fuel cell is operated at 900 °C with a variety of fuel feeds, including argon, hydrogen, coal and a coal-water slurry. Characterization of anode performance is carried out by open circuit potential monitoring, linear potential sweeps, and electrochemical impedance spectroscopy combined with equivalent circuit modeling. A cathode symmetric cell is analyzed and modeled to isolate impedance contributions resulting from ionic resistance, cathode mass transport, and cathode charge transfer; results are used to isolate anode mass transport and charge transfer impedances in the fuel cell. Open circuit potential measurements under hydrogen fuel indicate that the dominant anode reaction is electrochemical oxidation of H2, while oxidation of Sn to SnO2 becomes the principal anodic process when the cell is fed with argon, coal, or coal-water slurry. Some chemical reduction of SnO2 to Sn by chemical reaction with coal is indicated by the cell potential.
Liquid Tin Anode SOFC for Coal Conversion and Sulfur Tolerance
Authors: Tao Thomas T. , Koslowske Mark , Bentley Jeff , Brodie Jonathan , MacKean Conor
Published: May 2012

Liquid Tin Anode SOFC (LTA-SOFC) has demonstrated the ability to convert virtually any carbonaceous fuel directly to electricity, including solid fuels such as carbon and potentially coal. Three direct coal conversion concepts based on liquid tin anode have been explored indicating a feasibility of 61% fuel efficiency on a MW plant scale. To direct convert coal in a LTA-SOFC for stationary power generation remains a technical challenge: coal contains substantial amount of impurities other than carbon, hydrogen, oxygen and nitrogen, and its direct conversion unavoidably brings non-fuel elements in direct contact with fuel cell components. These non-fuel components include coal ash, sulfur, and trace elements such as vanadium, chromium, phosphorous, etc. The concept of direct conversion of coal in a LTA-SOFC was demonstrated using Illinois #6 coal to determine the state of ash and impurities. Sulfur tolerance was confirmed using 3.5wt% H2S in hydrogen, and a direct conversion in liquid tin anode using Illinois #6 coal. Preliminary test results demonstrated feasibility of direct coal conversion in the LTA-SOFC.
Carbon Oxidation in Fuel Cells and H2 Production
Authors: Colet Lagrille Melanie , Doraswami Uttam , Kelsall Geoff H.
Published: May 2012

High temperature direct carbon fuel cells (DCFCs) offer potentially high efficiencies for conversion of the chemical energy of solid carbonaceous fuel(s) into electrical energy. DCFCs with molten metal anodes consume carbonaceous fuels by oxygen dissolved within the melt, which functions as an anode in an otherwise conventional solid oxide fuel cell (SOFC). Such reactors can also be used in electrolytic mode for reducing steam to hydrogen at the cathode, which enables the specific electrical energy consumption for H2 production to be decreased compared with conventional steam electrolysis. 2-D models have been developed to predict the behavior of a micro-tubular hollow fiber SOFC (ca. 1 mm ID) with a molten metal (Sn) anode, using assumed values for the anode exchange current density. Results are reported for the temperature dependence of open circuit potentials for the reactor: Sn | SnO2 | YSZ | Air measured using a pellet cell and compared with thermodynamic predictions.
A Study of Blue Emitting Phosphors, ABPO4:Eu2+ (A=Li, Na, K; B=Ca, Sr, Ba) for UV LEDs
Authors: Hannah Mark E. , Piquette Alan P. , Anc Maria , McKittrick Joanne , Talbot Jan , Han Jinkyu , Mishra Kailash C.
Published: May 2012

With more and more research efforts being focused on phosphors for LEDs, new systems are constantly being explored. One such system is the ABPO4:Eu2+ with A = Li, Na and K and where B = Ca, Sr, and Ba. These phosphors will produce varying blue emissions from 400 nm out to around 480 nm upon excitation by UV emitting LED sources. In this study we have explored nine different phosphors having different combinations of A and B. The spectroscopic properties of these phosphors, as well as their external quantum efficiencies, and their temperature dependant lifetimes will be discussed.
Proton Exchange Membrane Performance Characterization in VRFB
Authors: Tang Zhijiang , Keith Rachel , Aaron Douglas S. , Lawton Jamie S. , Papandrew Alexander P. , Zawodzinski Thomas A.
Published: May 2012

The proton exchange membrane is widely used in vanadium redox flow battery as electrolyte separator and proton conductors. In this paper, two commercial proton exchange membranes, Nafion and 3Mion, have been investigated. High frequency resistance and water and acid uptake of the PEMs are measured after equilibration in sulfuric acid of different concentrations. The conductivity of the membrane is correlated to water content and water activity inside the membrane. The membrane conductivity of membranes equilibrated in a vanadium/sulfuric acid solution was also measured and compared to the internal resistance of an operating battery with the same vanadium and acid concentrations. The comparison result shows that membrane resistance is the major component of battery internal resistance.
A Thin Fiber Film Rotating Disc Electrode Analysis of Carbon Felt for Redox Flow Battery Application
Authors: Hawthorne Krista L. , Savinell Robert F.
Published: May 2012

Redox flow battery technology shares several design features of fuel cells but uses liquid electrolytes as the energy storage medium. These batteries utilize a carbon felt as the electrode surface for the redox reactions. Thin film rotating disk electrodes are a widely used technique for evaluation of fuel cell catalysts because it allows for the isolation of interfacial kinetics from mass transfer and ohmic effects. Adaptation of this technique to carbon felt fibers as an experimental method for the evaluation of felt electrode materials was explored in this research. Capacitance results show good electrical connectivity within the deposited film of carbon felt fibers, however voltammetric and RDE experiments point towards a multidimensional diffusion profile within the fiber layer. Porous electrode modeling may shed light on the complex diffusion and ohmic mechanisms.