bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships between nucleoside triphosphate pyrophosphohydrolase activity and inosine triphosphate accumulation in human erythrocytes
Authors: Sober Christian , Henderson J. Frank , Zombor George , McCoy Ernest E. , Verhoef Vernon , Morris Allan J.
Published: December 2009

The relationship between nucleoside triphosphate pyrophosphohydrolase (NTPH) (EC 3.6.1.19) activity in erythrocyte lysates and accumulation of radioactive inosine triphosphate (ITP) in human erythrocytes incubated in vitro with [14C]hypoxanthine, was studied in 93 humans. When ITP accumulation, expressed as percentage of total radioactive nucleotides, was plotted against NTPH specific activity, an inverse relationship was found to exist. A continuous spectrum of NTPH specific activities and ITP accumulation values exists in the human population and the relationship between these two parameters follows the relationship of substrate concentration to enzyme activity predicted by Michaelis–Menten enzyme kinetics. One interpretation of these data is that the ITP concentration in human red blood cells is controlled by the degradation of ITP to IMP and pyrophosphate catalyzed by NTPH.
Structure and function of insulin: preparation and biological activity of guinea pig des-B-Asp30,des-A-Asn21-insulin
Authors: Yip C. C. , Moule M. L.
Published: December 2009

Bovine des-B-Ala30,des-A-Asn21-insulin and guinea pig des-B-Asp30,des-A-Asn21-insulin were prepared from bovine and guinea pig insulin by digestion with carboxypeptidase A (EC 3.4.12.2). As reported by other investigators, the biological activity of bovine des-Ala30,des-Asn21-insulin was less than 10% that of bovine insulin. Contrary to theoretical consideration, removal of A-Asn21 and B-Asp30 from the carboxyl termini of guinea pig insulin resulted in a loss of more than 90% of the biological activity. Receptor binding studies of these insulin derivatives demonstrated a good correlation between the loss of biological activity and the decrease in binding affinity. It is suggested that the carboxyl terminal A-Asn21 of insulin may interact directly with the insulin receptor.
A second form of the single-strand specific endonuclease of Neurospora crassa which is associated with a double-strand exonuclease
Authors: Fraser M. J. , Tjeerde R. , Matsumoto K.
Published: December 2009

A second form of single-strand specific endonuclease, which is stable to heating up to 74 °C and does not bind strongly to phosphocellulose, has been partially purified from extracts of mycelia of wild-type Neurospora crassa. The endonuclease is associated with an equally heat-stable exonuclease which degrades linear but not circular double-stranded DNA and does not attack double-stranded RNA. The exonuclease probably also degrades single-stranded DNA. Both endonuclease and exonuclease activities are inhibited by 0.1–0.5 mM ATP. The exonuclease is preferentially inhibited by a variety of agents and preferentially inactivated by trypsin. A DNA-unwinding activity has also been detected in the nuclease preparation. Protease(s) present in the nuclease preparation destroy the DNA-unwinding and exonuclease activities on incubation at 37 °C, but do not affect the endonuclease activity. However, the heat-stability and chromatographic properties of the endonuclease are affected by this treatment. The altered properties of the endonuclease are very similar to those of the single-strand specific endonuclease which has been previously described. The combined nuclease activities of the unaltered preparation make up a putative recombination nuclease of N. crassa.
Fractionation of human low density lipoprotein by column chromatography
Authors: Rubenstein Bernard , Steiner George
Published: December 2009

We have devised a method to fractionate low density lipoprotein (LDL) into subspecies by means of column chromatography. DEAE-agarose columns, 2.6 × 60 cm, were loaded with LDL (25–45 mg LDL protein) and eluted with a 0.045–0.13 M NaCl gradient. The LDL eluted over a volume of 900 ml. Specific portions of the eluted LDL, reapplied to a column identical with the original, reelute at about the same point. Altering the NaCl concentration of the elution fluid changed the elution volume. The cholesterol-protein ratio of the LDL subfractions was progressively lower in fractions eluting at higher NaCl concentrations. These results indicate the LDL is not a homogenous lipoprotein species but consists of subfractions which differ in at least charge and cholesterol content.
Effects of alkylation by dimethyl sulfate, nitrogen mustard, and mitomycin C on DNA structure as studied by the ethidium binding assay
Authors: Hsiung Hansen , Lown J. William , Johnson Douglas
Published: December 2009

The extent of alkylation of DNA by dimethyl sulfate, nitrogen mustard, and the antibiotic mitomycin C is related to the resulting decrease in the fluorescence of intercalated ethidium. The fluorescence losses due to the first two types of reagents show a marked pH dependence, with greater losses of fluorescence being observed at alkaline pH values. At pH 11.6 the fluorescence shows a slow recovery, so that with low levels of methylation (~ 4% deoxyguanosine residues modified) one observes complete return of fluorescence. We postulate that these phenomena are due to conversion of 7-methyldeoxyguanosine to the zwitterionic form, and partial denaturation of the DNA duplex with loss of ethidium binding sites. Hydroxide-ion-catalyzed imidazole ring opening, and the removal of the positive charge permits reannealing with concomitant return of the ethidium intercalation sites. This conclusion is substantiated by enzymatic hydrolysis of 14C-labelled methylated DNA and identification of the two types of deoxyguanosine residues formed under the different conditions of the ethidium assay. The distinctly different behavior of mitomycin C confirms previous conclusions that its alkylation, preferentially on guanine, does not take place at the N-7 position.
Hydrodynamique d'une pessière noire drainée
Authors: Belleau Pierre , Plamondon André P. , Lagacé Robert , Pépin Steeve
Published: December 2009

The depth of the water table was measured before and after the digging of drainage ditches with 20-, 40-, and 60-m spacings in a black spruce wild holly bog. The peat is mesic with the exception of the top 10 cm which is fibric. The hydraulic conductivity of the 20- to 40-cm layer is low in relation with other Quebec sites under study. The extremely low conductivity under the 40-cm depth and the impermeable mineral soil layer at the bottom of the ditches creates the horizontal profile between ditches. The mean water table depths during the 3 years of the study were 42, 29, and 22 cm, respectively, for the 20-, 40-, and 60-m spacings. The corresponding lowering of the water table was in the order of 25, 13, and 6 cm. The water table was maintained 100, 70, and 40% of the time below the 20 cm deep root zone for the 20-, 40-, and 60-m spacings respectively, compared with 23% for the undrained situation (by simulation). The water table is significantly lowered below the 40-cm threshold for the 20-m spacing only.
Point-Poisson, point-pps, and modified point-pps sampling: efficiency and variance estimation
Authors: Schreuder H.T. , Ouyang Z. , Williams M.
Published: December 2009

Modified point-pps (probability proportional to size) sampling selects at least one sample tree per point and yields a fixed sample size. Point-Poisson sampling is as efficient as this modified procedure but less efficient than regular point-pps sampling in a simulation study estimating total volume using either the Horvitz–Thompson (ŶHT) or the weighted regression estimator (Ŷwr). Point-pps sampling is somewhat more efficient than point-Poisson sampling for all estimators except ŶHT, and point-Poisson sampling is always somewhat more efficient than modified point-pps sampling across.all estimators. For board foot volume the regression estimators are more efficient than ŶHT for all three procedures. Point-pps sampling is always most efficient, except for ŶHT, and point-Poisson sampling is always more efficient than the modified point-pps procedure. We recommend using Ŷgr (generalized regression estimator), Ŷwr, or ŶHT for total volume and Ŷgr for board foot volume. Three variance estimators estimate the variances of the regression estimates with small bias; we recommend the simple bootstrap variance estimator because it is simple to compute and does as well as its two main competitors. It does well for ŶHT, too, for all three procedures and should be used for ŶHT in point-Ppisson sampling in preference to the Grosenbaugh variance approximation. An unbiased variance estimator is given for ŶHT with the modified point-pps procedure, but the simple bootstrap variance is equally good.
The distribution and estimation of jack pine budworm defoliation
Authors: Volney W. Jan A.
Published: December 2009

A method to categorize defoliation on current year's shoots of jack pine (Pinusbanksiana Lamb.) was developed. The pattern of defoliation caused by the jack pine budworm (Choristoneurapinuspinus Free.) feeding on jack pine trees was studied in a variety of locations in Manitoba and Saskatchewan over several years. In addition to differences among locations and years, the crown level from which a sample was taken, the branch within a tree, the tree within a plot, and the plot within a study location were consistent sources of variation. In general, the upper crown was most heavily defoliated and the lower crown least so. Branches, trees, and plots are random sources of variation, and the variance components associated with each such source were analyzed to determine their contribution to the overall variance in the estimate of defoliation. The relative importance of each random source of variation varied with the percent defoliation. Variation among plots was significant at defoliation levels below 45% and peaked at 25%, indicating a patchy distribution of feeding within stands in this range of defoliation. Beyond 45% defoliation, feeding was uniformly distributed among plots within a stand. Variation in defoliation among branches and trees peaked in the 50–60% defoliation range and was negligible at the extremes. Advantage can be taken of the consistent patterns of defoliation among crown levels and knowledge of the variance components of the random sources of variation to design defoliation assessment protocols. These data were used to optimize the allocation of effort, among plots, trees, and branches, required to determine the level of defoliation in stands either with fixed level of effort or to a specified level of precision.
Carbon storage in Lake States aspen ecosystems
Authors: Alban D.H. , Perala D.A.
Published: December 2009

Total ecosystem carbon in the soil and vegetation was measured for a range of aspen (Populustremuloides Michx.) ecosystems, including a chronosequence on the same soil ranging in age from 0 to 80 years. Soil carbon stayed relatively constant throughout the stand's life and was not affected by timber harvesting. Changes in ecosystem carbon closely paralleled the changes in standing biomass. Aspen grown on 40-year rotations on good soils will sequester several times as much carbon per year as old-growth forests.
Genetic variation in susceptibility to Dothistroma needle blight among provenances and families of Pinusmuricata
Authors: Ades P. K. , Simpson J. A. , Eldridge K. G. , Eldridge R. H.
Published: December 2009

The susceptibility of Pinusmuricata D. Don to needle blight caused by Dothistromaseptospora (Dorog.) Morelet var. septospora was investigated in three provenance tests and a progeny test in New South Wales, Australia, and compared with that in Pinusradiata D. Don, the major commercially planted species. Provenances of P. muricata from Humboldt, Mendocino, and Sonoma counties in northern California were moderately susceptible for the first 3 or 4 years but then developed a high degree of field resistance. There was a general trend to increasing susceptibility in provenances progressively southwards along the California coast, with one notable exception, Santa Rosa Island provenance, which appeared to be resistant. All provenances from Monterey southwards, with that one exception, were at least as susceptible as P. radiata. The Mendocino County provenance of P. muricata is suggested as an alternative to P. radiata for planting on sites where there is a high risk of severe needle blight, as it possesses a combination of high disease resistance, rapid growth rate, and desirable wood properties. A 6-year-old progeny test of trees of Sonoma County provenance yielded a heritability estimate of 0.29 for percentage of needles infected by Dothistroma needle blight, which is very similar to estimates for the same trait in P. radiata. This indicates that although this population is already substantially less susceptible than the most resistant provenance of P. radiata, there is still a high degree of heritable variation and resistance could be improved even further by within-provenance selection.
Effects of temperature during bud burst on pear thrips damage to sugar maple
Authors: Kolb T.E. , Teulon D.A.J.
Published: December 2009

Sugar maple (Acersaccharum Marsh.) seedlings were exposed to either cool (11.9 °C) or warm (18.2 °C) temperatures in the presence or absence of adult pear thrips (Taeniothripsinconsequens Uzel) during bud burst and early spring growth. Time required for spring stem elongation was shorter at the warm temperature than at the cool temperature. Thrips feeding reduced height, leaf area, and seedling dry weight at both temperatures, and reductions were greater at the cool temperature than at the warm temperature. The results indicate that cool temperatures that slow bud burst promote pear thrips damage to sugar maple leaves.
In-situ Raman Examination on PtRu/C in PEMFC
Authors: Cheng Xuan , Zhang Lu , Chen Ling , Zhang Ying , Fan Qinbai
Published: December 2009

PtRu/C catalyst before and after a lifetime test in a proton exchange membrane fuel cell (PEMFC) has been characterized in-situ using Raman spectroscopy. It was found that the formation and stability of ruthenium oxide were extremely sensitive to atmospheres and less dependent on temperatures in the range of 25oC~100oC. Amorphous ruthenium oxide was rapidly reduced by the presence of hydrogen and readily oxidized when air or water vapor was introduced. The formation and reduction of ruthenium oxide might change the PtRu binary structure and lead to catalyst degradation along with carbon corrosion, which could jeopardize the fuel cell performance and stability.
Ionic Conductivity of Lithium Based Electrolytes in the LiI-Li2O-MoO2-V2O5 (LMV) Quaternary Glass System
Authors: Nandakumar Pat , Garcia Julio C. , Mann Stewart , Reynolds Zachary C.
Published: December 2009

Glass electrolytes of the LMV system are being prepared in various compositions by the melt quench technique. The mixture is heated to very high temperature to obtain a homogeneous melt which is quenched in liquid nitrogen. The Li+ ions are provided by dopant LiI and the Li2O acts as a modifier of the glass network formed by MoO2 and V2O5. The samples are characterized by XRD, IR, and Electrochemical Impedance technique. The ionic conductivity is calculated from the bulk resistance obtained from the impedance measurements. The impedance is measured at room temperature as well as various temperatures. The heating and cooling effect on impedance is measured from room temperature till 100°C. The conductivity measured is in the range of 10-5 Scm-1. The IR showed the cluster formation and the temperature variation studies of impedance provided an insight into the behavior of these glasses at different temperatures.
Improved Conversion Efficiency of Organic Solar Cells with CuPc/C60 Heterostructure by Electron Transfer Layers
Authors: Chou Dei-Wei , Huang Chien-Jung , Wang Tsung-Chang , Chen Wen-Ray , Chen Kan-Lin
Published: December 2009

In this paper, we investigated the role of electron transport layer (ETL) on the organic solar cells. By using 2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1, 3, 4-oxadiazole (PBD), bathocuproine (BCP) and tris (8-hydroxy-quinolinato) aluminium (Alq3) were used as ETLs. It was observed that the PCE of device with BCP layer was greatly improved compared with devices with other ETLs. The performance improvement was analyzed in terms of energy diagram level, UV/vis absorption spectra.
Electrodeposition of Mg(OH)2 Film on Tin Oxide Coated Glass Substrate at Room Temperature
Authors: Lü Ying , Lai Yanqing , Zhang Zhian , Liu Yexiang
Published: December 2009

Magnesium hydroxide thin films were electrodeposited on SnO2 coated glass substrates from aqueous magnesium nitrate solution at room temperature. The electrochemical process and mechanism were characterized by cyclic voltammetry(CV) and chronoampero-metry. CV curves confirm three main cathodic reactions, including reduction of oxygen, nitrate and evolution of hydrogen. With the applied potential increasing, cathodic current density increased. FESEM observation shows porous films grew densely and flower-like secondary grains tended to generate on the film surface. Mg(OH)2 film electrodeposited at linear sweep voltage(LSV) exhibits dense morphology different with porous morphology by potentiostatic method. This morphology difference is attributed to Hydrogen evolution reaction (HER). Hydroxyl ion or accumulation of electrons at the cathode surface may hinder the evolution of hydrogen. GAXRD result indicates the film by LSV method exhibits preferred orientation along (001) plane of Brucite Mg(OH)2 structure.
Effect of Vinylene Carbonate on Graphite Anode Cycling Efficiency
Authors: Ridgway Paul , Zheng Honghe , Liu Gao , Song Xianguin , Ross Philip , Battaglia Vince
Published: December 2009

Vinylene Carbonate (VC) was added to the electrolyte in graphite-lithium half-cells. We report its effect on the coulombic efficiency (as capacity shift) of graphite electrodes under various formation cycling conditions. Cyclic voltammetry on glassy carbon showed that VC passivates the electrode against electrolyte reduction. The dQ/dV plots of the first lithiation of the graphite suggest that VC alters the SEI layer, and that by varying the cell formation rate, the initial ratio of ethylene carbonate to VC in the SEI layer can be controlled. VC was found to decrease first cycle efficiency and reversible capacity (in ongoing cycling) when used to excess. However, experiments with VC additive used with various formation rates did not show any decrease in capacity shift.
Free Standing Nanostructured Anodes for Li-Ion Rechargeable Batteries
Authors: Au Ming , McWhorter Scott C. , Adams Thad M. , Zhao Yiping , Gibbs John
Published: December 2009

The freestanding nanorodes of aluminum and cobalt oxides were grown on electrode and tested as the anodes directly in the half-cell. The average diameter and length of the nanorods are 80 nm and 200 nm respectively. The aligned nanorods demonstrated high initial capacity from 1200-1400 mAh/g at rate of 0.5C. The gradually decrease of initial capacity was observed. The preliminary characterization shows that the changes of the crystalline structure and morphology during cycling may be responsible for the capacity decay.
Reversible Fe(III/VI) Super-iron Charge Transfer
Authors: Licht Stuart
Published: December 2009

A super-iron Li-ion cathode with 3-fold higher reversible capacity (a storage capacity of 485 mAh/g) is presented. One of the principle constraints to vehicle electrification is that the Li-ion cathode battery chemistry is massive, and expensive. Demonstrated is a transformative 3e- storage lithium cathodic chemistry, and a reversible Li super-iron battery with significantly higher capacity than contemporary Li-ion batteries. The super-iron Li-ion cathode consists of the hexavalent iron (Fe(VI)) salt, Na2FeO4, and is formed from inexpensive and clean materials. The charge storage mechanism is fundamentally different from those of traditional lithium ion intercalation cathodes. Instead, charge storage is based on multi-electron faradaic reduction, which considerably enhances the intrinsic charge storage capacity.
A Solution for Lead-Acid Battery Global State Estimation
Authors: Cugnet Mikael G. , Sabatier Jocelyn , Laruelle Stephane , Grugeon Sylvie , Chanteur Isabelle , Sahut Bernard , Oustaloup Alain , Tarascon Jean-Marie
Published: December 2009

With hybrid and electric vehicles developments, the energy management in the car has become a major topic of research for the automotive industry. Battery monitoring systems (BMS) have been designed to avoid the battery breakdown, to keep their lifespan, and decrease the fuel consumption. The battery ability to deliver energy was the only aspect of its performances that was really studied by the automotive industry until the 21st century. The integration of more and more electronics in cars has led to take into account the power not only deliver by the alternator, but also provided by the battery, in order to ensure the availability of a growing number of vehicle functions. Most automotive battery breakdowns are due to a lack of power and rarely a lack of energy. Therefore, the battery available power needs to be monitored and taken in consideration in the BMS design.
Preparation and Characterization of Mediator Doped PEO/LiAlO2/SiO2 Solid Polymer Electrolyte
Authors: Yin Yijing , Zhou Juanjuan , Zhou Xiangyang
Published: December 2009

Solid polymer electrolytes based on Polyethylene oxides (PEO's) and Lithium aluminate composites with mesoporous silica at different weight percentages were prepared using a solution casting technique. The morphology and complexity of the composite membrane were measured by SEM and FTIR. Electrical conductivities were measured in the temperature range of 303-373 K and conductivity was found to increase with the increase of dopant concentration as well as temperature. Because of the addition of I-/I3-, the solid polymer electrolyte membrane could also be used in solar cells and super capacitors. The cycle voltammetry can also be used to study the influence of mesoporous silica on the capacitance of the membrane.
Development and Study of Mediator-Enhanced Polymer Electrolyte Supercapacitors
Authors: Zhou Xiangyang , Zhou Juanjuan , Yin Yijing , Mansour Azzam
Published: December 2009

All solid-state supercapacitors were prepared using activated carbon, polymer electrolytes, i.e. Nafion and mediators, I-/I3-. The mediators have potential to provide high pseudocapacitance and to greatly reduce the internal resistance. Cyclic voltammetry studies were conducted to evaluate the specific energy, specific power and stability of the mediator-enhanced polymer electrolyte supercapacitors (MEPESCs). Scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, surface area and porosimetry studies were conducted to examine the structural and chemical characteristics of the MEPESC electrodes. The results indicate that the leakage free MEPESCs not only provide high specific energy and power but also ease and flexibility for fabrication and packaging of energy storage devices. The results also suggest that the MEPESCs can be further improved by mitigating the aggregation/segregation of the mediators, eliminating the surface coating, promoting solvation of iodine ions, and reducing crossover of iodine.
Comparison of Electrospun and Commercially Available Separator Materials for Supercapacitors
Authors: Jänes Alar , Tõnurist Kerli , Thomberg Thomas , Lust Enn
Published: December 2009

Supercapacitors based on two ideally polarizable microporous carbide-derived carbon electrodes and different mesoporous electrospun and commercially available separators in acetonitrile as the solvent for the 1.0 M (C2H5)3CH3NBF4 electrolyte have been completed and tested by cyclic voltammetry and electrochemical impedance methods. The limits of ideal polarizability, low-frequency limiting capacitance and series resistance, time constant, complex power components and other characteristics have been established. Influence of the separator chemical composition, thickness, density, specific surface area, total pore volume and pore size distribution on the slope of the cyclic voltammetry curves at higher potential scan rates v {greater than or equal to} 10 mV s 1 has been established explained by the different specific conductivity of ions in mesoporous separator.
Novel Composite Proton Exchange Membranes for Fuel Cells
Authors: Fuchs Alan , Sutrisno Joko , Adibhatla Anu , Wallis Bryce , Handerson Callie , Evrensel Cahit , Gordaninejad Faramarz
Published: December 2009

Novel composite proton exchange membranes have been prepared from non-fluorinated polymer and non- and surface coated heteropoly acids (HPA) using atom transfer radical polymerization (ATRP). Polyether sulfone (PES) was used as a polymer matrix. Phosphotungstic acid (PWA), phosphomolybdic acid (PMoA) and silicotungstic acid (SiWA) were used as HPA. It was found that the SiWA has a higher conductivity compared with PWA, at the same concentration. PES was sulfonated using chlorosulfonic acid. The highest conductivity for sulfonated PES with 60 wt.% PWA was 1.7 x 10-2 S/cm. In order to increase the compatibility between SiWA and PES, the SiWA was surface coated. Surface coated SiWA particles can be added to the polymer matrix up to 50 wt.% to form a homogeneous membrane. This route also has the potential to increase the conductivity by sulfonation of grafted polymer backbone, and to avoid "washing out" of HPA in the fuel cell.
Development of Electrolyte Membranes for Fuel Cells Operating at Intermediate Temperatures (130-200°)
Authors: Ashino Natalia , Martins Camargo Ana Paula , Morgado D. L. , Frollini Elisabete , Gonzalez Ernesto
Published: December 2009

The objective of this work was the preparation and characterization of poly(2,5-benzimidazole) (ABPBI) as electrolyte membrane for fuel cells applications at intermediate temperatures (130-200°). The ABPBI membranes were prepared by casting and then doped in phosphoric acid baths of different concentrations. The characterization included thermogravimetric analyses, elemental analyses and size exclusion chromatography. ABPBI membrane-electrode assemblies (MEAs) were tested in H2/O2 fuel cells.
Novel Ternary System Based Proton Conducting Polymer Electrolytes Based on Fluorinated Copolymer
Authors: Singh Marisa , Suraj Suren , Missan Harinder Pal Singh
Published: December 2009

Novel ternary brönsted acid-base ionic liquid based polymer electrolyte membranes has been synthesized using various combination of acid, base and different molecular weight polymer (polyvinylidenefluoride-co-hexafluoropropylene) in the present study. In-situ synthesis of the ionic liquid within the polymer matrix has been done in order to synthesize the polymer membranes. The membranes were then characterized for their various electrical, thermal and morphological properties. The effect of molecular weight of the polymer on the properties of the ternary electrolytes has also been studied. High room temperature ionic conductivity of the order of 10-2 - 10-3 S/cm has been achieved. The inclusion of ionic liquid into the polymer matrix through in-situ approach has been found to improve the morphology of the electrolyte membranes. Thermal stability of the membranes in excess of 150oC has been observed for certain compositions.
Poly(phenylene)-Based Anion Exchange Membranes for Alkaline Fuel Cells
Authors: Hibbs Michael , Fujimoto Cy , Cornelius Chris
Published: December 2009

Cationic polymer membranes that conduct free anions comprise an enabling research area for alkaline membrane fuel cells and other solid-state electrochemical devices that operate at high pH. The synthesis of anion exchange membranes based on a poly(phenylene) backbone prepared by a Diels-Alder reaction is demonstrated as a potential material for alkaline fuel cells. The poly(phenylene)s have benzylic methyl groups that are converted to bromomethyl groups by a radical reaction. Cationic polymers result from conversion of the bromomethyl groups to ionic moieties by quaternization with trimethylamine in the solid state. The conversion to benzyltrimethyl ammonium groups is incomplete as evidenced by the differences between the IEC values measured by titration and the theoretical IECs based on 1H NMR measurements. The anion exchange membranes formed from these polymers have hydroxide ion conductivities as high as 50 mS/cm in liquid water and they are stable under highly basic conditions at elevated temperatures.
Antineoplastic Drug Interactions with DNA Modified Gold Piezoelectrodes
Authors: Nowicka Anna , Hafner Shaun , Hepel Maria
Published: December 2009

Antineoplastic drugs are highly reactive agents able to disrupt DNA synthesis and DNA repair in both healthy and cancerous cells. In this work, we have investigated the electrochemical properties of antineoplastic drug mitoxantrone (MXT) and its interaction with single-stranded and double-stranded DNA immobilized in electrodic films. Using the electrochemical quartz crystal nanogravimetry (EQCN), we have found that mitoxantrone adsorbs on Au electrode at potentials lower than E = +0.7 V (vs. SCE). The binding constant for MXT interaction with dsDNA obtained using EQCN from the Scatchard plot is typical for intercalative-type interactions: K = 2.32×105 M-1 with the binding site size of 2.6. Quenching of MXT fluorescence by DNA indicates on the static FRET from MXT to DNA.
Molecularly Templated Polymer Matrix Films for Biorecognition Processes: Sensors for Evaluating Oxidative Stress and Redox Buffering Capacity
Authors: Stobiecka Magdalena , Deeb Jeffrey , Hepel Maria
Published: December 2009

Novel designs of molecularly imprinted sensor films have been investigated for possible applications for the detection of biomolecules. The templated glutathione-sensing films were synthesized by in-situ electropolymerization of orthophynylenediamine (oPD) in the presence of glutathione (GSH). The sensor response to GSH analyte was tested after hydrolyzing and removal of templating molecules. The analytical signal enhancement has been obtained by employing GSH-capped gold nanoparticles (AuNPGSH) for molecular imprinting. Multilayer sensory films consisting of a basal thiolate self-assembled monolayer (SAM), a film of AuNP network assembled on the SAM, and a top poly(oPD) template film with imprinted GSH, have also been investigated. Using the electrochemical quartz crystal nanogravimetry (EQCN), we have found that during the electropolymerization of poly(oPD) templates, considerable amounts of water soluble oPD radicals and oligomers are also generated. The proposed molecular imprinting technique can be applied in polymer sensor designs based on biorecognition principles with piezoelectric transduction.
High Pressure and Temperature Electrochemical Cell Design for Corrosion Research: Part I
Authors: Ubah Chinedu G. , Asselin Edouard
Published: December 2009

As aqueous processing moves to higher temperatures and pressures to take advantage of increased kinetics there is a need to develop and test appropriate reactor materials to ensure that corrosion is minimized. Corrosion testing often requires an electrochemical approach to fully understand the range of behaviours which should be expected from a corroding metal or alloy. Prior art of designs for electrodes, associated pressure vessels and sealing technology is presented. The development of an apparatus and methods for high temperature and high pressure electrochemical corrosion testing are discussed. The final electrochemical cell design which was developed for temperatures and pressures in excess of 500ºC and 5000 PSI is presented.
The Anodic Oxide Film Formed on A-Mg-Zr Alloys in Non-Aqueous Electrolyte
Authors: Tahara Minoru , Kawase Yasuhiro , Kitano Masafumi , Mizutani Fumikazu , Saeki Masayuki , Shirai Yasuyuki , Ohmi Tadahiro
Published: December 2009

The anodic oxide film formed on Al-2%Mg-0.1%Zr alloys (S2M) in non-aqueous electrolyte has excellent features. However, there is a problem that it is not possible to use in large-scale manufacturing equipment such as large-scale-integration, flat-panel-display, and solar cell because mechanical strength of the S2M is small. We made the Al-Mg-Zr alloys of a high Mg concentration, and evaluated it by the Vickers hardness for mechanical strength. The Vickers hardness of the Al-Mg-Zr alloy with high Mg concentration was high. Moreover, the quality of the anodic oxide film formed on these Al-Mg-Zr alloys in non-aqueous electrolyte was evaluated. The surface state of the anodic oxide film didn't have remarkable superiority by the difference of the Mg concentration in the Al-Mg-Zr alloys. But, the chlorine gas resistance became high by the increase of the Mg concentration.
Investigation of Waste of the Caprolactam Production as Steel Corrosion Inhibitor in Hydrochloric Acid
Authors: Ostapenko Gennady , Gloukhov Pavel , Sadivskiy Sergey
Published: December 2009

Waste of the caprolactam production that is the POD-oil (Product of Oxidizing and Dehydrogenation) is investigated by gravimetric, potentiodynamic and impedance spectroscopy techniques. It is shown that dimer of hexanon (dianone) is the basic inhibiting component of the POD-oil. It is demonstrated that the POD-oil retards mainly the anodic reaction. The corrosion process is simulated by a parallel connection of the corrosion resistance and the element with constant phase at value of the exponential factor n = 0.71 - 0.86. The efficiency of the investigated inhibitor reaches 85 - 88% at 1 mass % concentration of the inhibitor.
Thermal Degradation of a Mg-Rich Primer on AA 2024-T3
Authors: Allahar Kerry N. , Battocchi Dante , Bierwagen Gordon , Tallman Dennis
Published: December 2009

The mitigation of corrosion on aluminum aerospace alloys has been predominantly by organic coatings that include strontium chromate pigments. These pigments are excellent in passivating the aluminum surface but are toxic and are in the process of being regulated out of the aerospace industry. Passivating replacements such as vanadates, molybdates and phosphates are not as protective as chromates. Cathodic protection of aluminum alloys have been demonstrated using a coating pigmented with Mg particles. The protection provided by Zn-rich primers for steel is analogous to that provided by Mg-rich primers for aluminum. A transmission-line model was used to interpret Zn-rich primer EIS data that accounted for the contact impedance between the Zn particles, the impedance associated with the Zn dissolution, and the percolation resistance of the coating. This model was shown to be applicable to the EIS data associated with a Mg-rich primer on AA 2024-T3 immersed in dilute Harrison's solution (DHS). The degradation of the protection of the Mg-rich primer was influenced by the interfacial impedance while that of the Zn-rich primer was influenced by both the contact and interfacial impedance. The difference between the degradations of Mg-rich and Zn-rich primer systems was based on results obtained using the transmission line model. The applicability of the model to Mg-rich primers is further accessed in this effort where the model was used to interpret the EIS results associated with the thermal degradation of Mg-rich primer on AA 2024-T3 immersed in DHS.
Corrosion Inhibition Effect of Cationic Surfactant and Synergistic Effect of the Presence of the Chloride Ions
Authors: Asefi Dourna , Arami Mokhtar , Sarabi Ali asghar
Published: December 2009

Corrosion inhibition effect of cationic surfactant DTAB (dodecyl threemethyl ammonium bromide) on low carbon steel in 1M HCl was studied using weight loss method. Inhibition efficiency increased with the increase of surfactant concentration. Also, synergistic effect between surfactant and chloride ions in 1M HCl was investigated with the presence of different concentration of NaCl. The inhibition efficiency increased with the increase of NaCl concentration and reached the maximum value near 0.1 M. This composite inhibitor system containing cationic surfactant and chloride ions was efficient and low-cast for steel corrosion inhibition in HCl medium, even when the concentration of DTAB was as low as 0.5x10-4 M.
Synthesis of Metal Complex Modified Phospholipids by Phospholipase D-Catalyzed Transphosphatidylation
Authors: Correia Ledo Debby , Mauzeroll Janine
Published: December 2009

The synthesis of ferrocenyl-functionalized phospholipid was achieved through a biphasic transphosphatidylation reaction catalyzed by phospholipase D. Thus, the 1,2-distearoyl-sn-glycero-3-phosphocholine headgroup was modified with hydroxymethylferrocene. 1,2-distearoyl-sn-glycero-3-phosphocholine was chosen because it bears a choline group required for successful phospholipase D-catalysis. The use of hydroxymethylferrocene, as an electroactive tether, was appropriate since the present transphosphatidylation reaction is specific to primary alcohols. Mass spectrometry and phosphorus nuclear magnetic resonance analysis confirmed the formation of the redox active phospholipid and also revealed downstream instabilities that will need to be resolved prior to use in liposome assemblies.
Scanning Electrochemical Microscopy Approach Curves Numerically Simulated for Ring Microelectrodes in Pure Negative and Positive Feedback Mode
Authors: Mayoral Margarita , Fabre Dimitri , Mauzeroll Janine
Published: December 2009

Herein we report an extensive data set from numerical simulations of the ring microelectrode for pure positive and negative feedback mode approach curves. The dependence of the resulting simulated approach curves with characteristic dimensions of the ring microelectrode is also given. An analysis of the impact of the internal void of the pipette over the current distribution is made.
Concentration Polarization in Electroosmotic Pumps
Authors: Suss Matthew , Marshall Lewis A. , Zangle Thomas A. , Santiago Juan G.
Published: December 2009

Electroosmotic (EO) pumps can generate relatively high pressure and flow rate using no moving parts and small package volumes. Pumps with one micron (and smaller) pore diameters are promising for applications requiring high flow rate per power, such as drug delivery systems. We here show that such EO pumps exhibit significant concentration polarization (CP). CP occurs in electrokinetic devices when ionic current carried by electric double layers is significant compared to overall ionic current in the system. In the CP regime, EO pump models likely fail as these models do not account for the strong spatiotemporal variations in ionic strength. We present visualizations of CP in EO pumps, and confirm that enrichment and depletion propagation front dynamics correspond with CP theory. Additionally, we show that enrichment and depletion regions are generated at and propagate from electrodes of our system, and such regions appear to interact with CP effects.
Direct Biopsy Screening of Colorectal Cancer by Electrochemical Biosensor
Authors: Vernick Sefi , Freeman Amihay , Rishpon Judith , Shacham-Diamand Yosi
Published: December 2009

We propose and demonstrate feasibility of a new electrochemical assay performed directly on slices of fresh tumor biopsies. An amperometric biosensor was used to screen for colon cancer on the basis of electrochemical distinction between cancerous and normal epithelia. This observation is based on the known down-regulation of the enzyme Alkaline Phosphatase in cancerous cells. Biopsy samples removed from tumors induced in mice were compared to biopsies samples simultaneously collected from the small and large intestine (colon) of same mice. The samples were suspended in an especially designed multichamber electrochemical sensor. Upon the addition of a suitable substrate current signals were recorded. Significant differences in current signal were observed for biopsies removed from tumors comparing to samples removed from the corresponding healthy tissue. Reproducibility was demonstrated. The new technology allows a direct assay carried out on small volume biopsies without the need of sample transfer to cell culture, thus eliminating the need for pretreatment and labor intensive preparative steps. This approach offers rapid and straightforward detection directly affected within minutes of biopsy removal.
Core/Shell (Cu/Cu2O) Nanotubes as High Performance Anode Materials for Li-ion Rechargeable Batteries
Authors: Hasan Maksudul , Chowdhury Tamjid , Rohan James
Published: December 2009

A direct electrodeposition technique for very high quality Cu nanotube arrays and subsequent conversion of the deposited Cu into Cu2O has been developed. The Cu2O nanotube arrays have high capacity, high cyclability and high rate capability. The cycling performance of Cu2O nanotubes show a high level of structural integrity with capacity retention even after 94 cycles when cycled at 1.67 mA/cm2. The outstanding electrochemical performance of the Cu2O nanotubes comes from high surface area, easy infiltration of electrolytes, high electrical conductivity of Cu core support and structural integrity of the oxide shell active material. The Cu2O nanotubes also eliminate the requirement of ancillary materials currently used in Li-ion batteries, such as carbon particles to increase conductivity. The easy fabrication and performance of Cu2O nanotube arrays may make them suitable for next generation Li-ion batteries.
Application of Layered Nickel Double Hydroxide for Alkali Secondary Battery Using the Liquid Phase Deposition Method
Authors: Mizuhata Minoru , Hosokawa Akinobu , Béléké Alexis Bienvenu , Deki Shigehito
Published: December 2009

The effects of fluoride ions scavenger in the liquid phase deposition synthesis of nickel-aluminum layered double hydroxide/carbon (Ni-Al LDH/C) composite have been investigated. Al(NO3)3.9H2O, AlCl3, Al metal plate, and a mixed solution of [Al(NO3)3.9H2O and H3BO3] were employed as F- scavengers. In the case that Al material is solely used as F- scavenger, α-nickel hydroxide is the predominant phase, and a small amount of β-phase is detected. In contrast pure phase Ni-Al LDH/C composites, isostructural and isomorphic to α-Ni(OH)2 are obtained when a mixed solution of Al(NO3)3.9H2O and H3BO3 is used at any range of Al content. High purity LDHs without cationic species exhibited good stability in 6M KOH for 7 days. Short-term charge-discharge measurements at 1C-rate for the electrodes containing 0, 13.6 and 17.8 Al mol % showed an increase of the discharge capacity with increasing Al content.
Anodic Oxidation of Hydrogen in PEFCs at Varying Platinum Loadings
Authors: Selvarani Ganesh , John Bincy , Sridhar Parthasarathi , Pitchumani S , Shukla Ashok
Published: December 2009

Platinum loading as low as 0.05 mg/cm2 at the anode of the PEFC is desired for automotive applications. Hence, it is necessary to quantify the performance losses that may arise on reducing anode Pt loading from the present level of about 0.5 mg/cm2 to 0.05 mg/cm2. The present study focuses on hydrogen oxidation reaction for fuel cell anode with low Pt loadings. Hydrogen-pump experiments are conducted in conjunction with polarization studies to determine the performance losses at reduced Pt loadings arising due to Hydrogen Oxidation Reaction (HOR) and Hydrogen Evolution Reaction (HER).
Characteristics of Gallium Doped ZnO Thin Films Deposited by Sol Gel Dip Coating
Authors: Kalaivanan Appukuttan , Perumal S. , Pillai Neelakanda , Sivaramamoorthy K. , Murali K. R.
Published: December 2009

Zinc Oxide(ZnO) films were deposited by the sol gel dip coating using Acrylamiode route. The films were doped with different concentrations of Gallium in the range of 250 - 1200 ppm. The films exhibited hexagonal structure. The grain size decreased from 100 nm - 10 nm as the dopant concentration increased. The resistivity of the doped samples decreased from 103 ohm cm - 3 x 10-3 ohm cm. The band gap value shifted towards the short wavelength region as the dopant concentration increased. XPS studies indicated the doping of Ga in ZnO.
Electro-Oxidation of Methanol by Multi-Metal Catalysts Supported on Carbon Nanotubes
Authors: Cheerapradit Rattana , Chailapakul Orawon , Vanalabhpatana Parichatr
Published: December 2009

Synthesized by polyol process, platinum (Pt)-based di- and tri-metallic nanoparticles supported on multi-walled carbon nanotubes (MWCNTs) were developed as electrocatalysts for the oxidation of methanol. Structural information of the metal nanoparticles supported on MWCNTs was confirmed by X-ray diffraction (XRD) analysis whereas the electrocatalytic properties of the Pt/MWCNT, Pt-based dimetal/MWCNT, and PtRuMo/MWCNT catalysts were investigated by means of cyclic voltammetry. Our results illustrated that the PtRu/MWCNT modified electrodes exhibited higher anodic currents for methanol oxidation than the Pt/MWCNT electrode. Among all of the PtRu/MWCNTs with various Pt-to-Ru molar ratios, the 2:1.5-PtRu/MWCNT was the best electrocatalyst. Furthermore, the addition of Mo, the third metal, on dimetallic PtRu/MWCNT catalyst significantly promoted the catalytic activity. 2:(1.5-x):x-PtRuMo/MWCNT showed the best electrocatalytic performance with the anodic current of 138.3 A/g catalyst for 2.0 M methanol containing 0.5 M sulfuric acid.
Novel Nanocomposites Polymethacrylate Hydroxyethylene Resin Based Electrolyte
Authors: Silva Maria M. , Barbosa Paula , Rodrigues Luísa
Published: December 2009

Polymer electrolytes, which are ubiquitous in all solid state devices, are of profound interest to electrochemists, who transform these materials into interesting multifunctional systems with great potential in many applications, such as super capacitors, solar cells, Li+ batteries, sensors and electrochromic displays (1,2). In this study the results of novel nanocomposites materials based on polymethacrylate hydroxyethylene resin doped with controlled quantities of different lithium salts are reported. The polymer electrolytes were characterized by measurements of total ionic conductivity at ambient temperature, differential scanning calorimetry and thermogravimetry. The electrolyte presents an ionic conductivity of 2.12 x 10-7 S.cm-1 at 24ºC and TGA analysis show that this polymer electrolyte system is thermally degraded at 200ºC.
Synthesis of Pt Nano Electrocatalyst For Methanol Oxidation Using Polymer Template
Authors: Chatterjee Moitrayee , Ghosh Susanta , Chowdhury Pranesh , Basumallick Indra N.
Published: December 2009

In the present research simple methods of synthesis of nano-sized platinum particles using chemically prepared poly vinyl alcohol grafted with acrylic acid (PVA-g-AA) and electrochemically prepared polyaniline (PAn) have been described. Polyaniline of low molecular weight was prepared by electrooxidation of aniline in H2SO4 medium under galvanostatic condition. Pt nanoparticles deposited electrochemically onto the PAn surface. The PAn is then dissolved in dilute nitric acid to get the unsupported nano metal catalyst. PVA-g-AA was prepared chemically by reacting poly vinyl alcohol and acrylic acid in acid medium in the presence of graphite powder and ceric ammonium sulphate. Pt nanoparticles were synthesized with selective electrodeposition onto this graphite powder dispersed in non-conducting PVA-g-AA polymer. The Pt nanoparticles and polymers were characterized by SEM, EDX, TGA, FT-IR and XRD study. Cyclic voltammetry studies for methanol oxidation using these nano Pt loaded anodes show enhanced catalytic activity compared to conventional catalysts.