bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of xanthotoxin treatment on trichothecene production inFusarium sporotrichioides
Authors: Alexander Nancy J. , McCormick Susan P. , Blackburn Judith A.
Published: December 2008

There are 4 P450 oxygenases involved in the biosynthesis of T-2 toxin in Fusarium sporotrichioides . Exactly how these enzymes react to antimicrobial plant defense compounds is unknown. Xanthotoxin (8-methoxypsoralen) is a phototoxic furanocoumarin that acts as a P450 oxygenase inhibitor. The current study shows that the addition of concentrations of 1.0 mmol/L or less of xanthotoxin to liquid cultures of F. sporotrichioides NRRL3299 can effectively block T-2 toxin production and cause an increase in accumulation of trichodiene, the hydrocarbon precursor of trichothecenes. The addition of xanthotoxin to liquid cultures of a trichodiene-accumulating F. sporotrichioides Tri4–mutant caused a 3- to 10-fold increase in trichodiene accumulation, suggesting that xanthotoxin not only blocks trichothecene oxygenation reactions, but may in some way also promote the synthesis of trichodiene. Feeding studies showed that 2 of the 4 P450 oxygenases, TRI4 and TRI1, were more sensitive to xanthotoxin, while oxygenases TRI11 and TRI13 were unaffected. Quantitative reverse-transcriptase PCR indicated that several of the genes in the toxin biosynthetic pathway were upregulated by xanthotoxin, with Tri4 showing the highest increase in expression. These results indicate that while xanthotoxin inhibits specific P450 oxygenase activity, it also has an effect on gene expression.
Genetic parameter estimates for growth traits of black spruce in northwestern Ontario
Authors: Lu Pengxin , Charrette Paul
Published: December 2008

Genetic parameters of growth traits were estimated for first-generation selections of black spruce ( Picea mariana (Mill.) BSP) in northwestern Ontario from 720 open-pollinated families and more than 42 000 trees. Unbiased estimates of narrow-sense heritability for tree height growth averaged 0.19, 0.18, and 0.14 at ages 6, 11, and 19 years, respectively, from combined-site analyses compared with 0.25, 0.23, and 0.16 for the same ages from single-site analyses. Heritability estimates for diameter at breast height and stem volume were lower than that of height at age 19, suggesting that tree height is a more desirable trait for selection in black spruce. The moderately high estimates of type B genetic correlations implied limited operational importance of genotype × environment interactions. Estimates of age–age genetic correlation were high (>0.88) among cumulative tree height growth at 6, 11, and 19 years but lower between height increments from different age intervals. Estimates of type B age–age genetic correlation were more than 0.2 lower than their type A counterparts, suggesting strong effects of common environments on the estimates of type A genetic correlations. Based on the relative selection efficiencies, selection on cumulative tree height between ages 6 and 11 was more efficient than at age 19.
Financial compensation and uncertainty: using mean-variance rule and stochastic dominance to derive conservation payments for secondary forests
Authors: Knoke Thomas , Hildebrandt Patrick , Klein Daniel , Mujica Rodrigo , Moog Martin , Mosandl Reinhard
Published: December 2008

The expected opportunity costs of conserving a specific land use are usually considered adequate as financial compensation. However, a “conservation premium” is sometimes proposed as an added incentive, i.e., compensation greater than the expected opportunity costs. This paper discusses various methodological opportunities for deriving effective compensation under uncertainty. Based on cumulative distribution functions of possible opportunity costs (a Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plantation was considered the alternative to conserving a Chilean secondary forest), generated through Monte Carlo simulations, we derived an inclusive range of possible compensations from 77 up to 375 US$·ha–1·year–1. If we assumed that the two land-use alternatives were mutually exclusive and independent from other risky investments, a compensation of 375 US$·ha–1·year–1 was necessary to convince every decision maker to maintain the secondary forest. However, only 77 US$·ha–1·year–1 was enough for a risk-averse decision maker (given average opportunity costs of 113 US$·ha–1·year–1). Yet, it turned out that the greatest possible opportunity costs would already be compensated for with 199 US$·ha–1·year–1, given an error probability of 0.05. Compensating for the last 5% of possible opportunity costs would thus require an additional 176 US$·ha–1·year–1. Our approach had two main limitations, namely we did not consider portfolio effects, which would allow diversifying away unsystematic risks, and we did not take into account the different systematic risks of the compared alternatives. These limitations may have led to an overestimation of effective compensation.
Western juniper and ponderosa pine ecotonal climate–growth relationships across landscape gradients in southern Oregon
Authors: Knutson Kevin C. , Pyke David A.
Published: December 2008

Forecasts of climate change for the Pacific northwestern United States predict warmer temperatures, increased winter precipitation, and drier summers. Prediction of forest growth responses to these climate fluctuations requires identification of climatic variables limiting tree growth, particularly at limits of tree species distributions. We addressed this problem at the pine–woodland ecotone using tree-ring data for western juniper ( Juniperus occidentalis var. occidentalis Hook.) and ponderosa pine ( Pinus ponderosa Dougl. ex Loud.) from southern Oregon. Annual growth chronologies for 1950–2000 were developed for each species at 17 locations. Correlation and linear regression of climate–growth relationships revealed that radial growth in both species is highly dependent on October–June precipitation events that recharge growing season soil water. Mean annual radial growth for the nine driest years suggests that annual growth in both species is more sensitive to drought at lower elevations and sites with steeper slopes and sandy or rocky soils. Future increases in winter precipitation could increase productivity in both species at the pine–woodland ecotone. Growth responses, however, will also likely vary across landscape features, and our findings suggest that heightened sensitivity to future drought periods and increased temperatures in the two species will predominantly occur at lower elevation sites with poor water-holding capacities.
Impacts of fire and fire surrogate treatments on ecosystem nitrogen storage patterns: similarities and differences between forests of eastern and western North America
Authors: Boerner R. E.J. , Huang Jianjun , Hart Stephen C.
Published: December 2008

The Fire and Fire Surrogates (FFS) network is composed of 12 forest sites that span the continental United States, all of which historically had frequent low-severity fire. The goal of the FFS study was to assess the efficacy of three management treatments (prescribed fire, mechanical thinning, and their combination) in reducing wildfire hazard and increasing ecosystem sustainability. This paper describes the impact of the FFS treatments on nitrogen (N) storage and distribution. At the network scale, total ecosystem N averaged 4480 kg·ha–1, with ∼9% in vegetation, ∼9% in forest floor, ∼2% in deadwood, and ∼80% in soil. The loss of vegetation N to fire averaged (±SE) 25 ± 11 kg·ha–1, whereas the mechanical and combined mechanical and fire treatments resulted in N losses of 133 ± 21 and 145 ± 19 kg·ha–1, respectively. Western coniferous forests lost more N from each treatment than did eastern forests. None of the manipulative FFS treatments impacted >10%–15% of total N of these ecosystems. Management strategies that maximize ecosystem carbon (C) gain by minimizing loss of N should be a focus in western forests, where C and N cycling are tightly linked, but perhaps not in those eastern forests where atmospheric N deposition has decoupled C and N cycles.
SCALAR AND FERMION ZERO MODES ON THE THICK BRANE ARISING FROM TWO SCALAR FIELDS
Authors: DU MUYUN , DU XIYUN , XIE YUEYING
Published: December 2008

In this note we study scalar and fermion zero modes on the brane arising from two scalar fields. The result is that there exist normalizable massless modes of scalar fields which can be localized on the brane. While, for spin 1/2 and spin 3/2 fermions, the corresponding zero modes are non-normalizable. Thus, some mechanism such as Yukawa coupling should be introduced for the localization of these fermionic fields on the thick brane.
SYSTEMATICS OF LINEARIZATION OF N = 2 NONLINEAR SUSY IN SUPERFIELD FORMULATION
Authors: SHIMA KAZUNARI , TSUDA MOTOMU
Published: December 2008

The relation between an N = 2 nonlinear supersymmetric (SUSY) model and a linear SUSY (free) theory for N = 2 vector supermultiplet accompanying the spontaneous SUSY breaking is systematically worked out in two-dimensional superfield formulation.
NORMAL HOLONOMY AND WRITHING NUMBER OF SMOOTH KNOTS
Authors: HEBDA JAMES J. , TSAU CHICHEN M.
Published: December 2008

The normal holonomy of a smooth knot in Euclidean space is a geometric invariant with value in the unit circle which is closely related to the writhing number. Here we prove that normal holonomy fibers the space of smooth knots, except for possible singularities on the set of round knots. We deduce results on the existence of isotopies of constant holonomy, writhe and twist.
Peculiarities of Copper Anodic Behavior in Alkaline Solutions with Glycine Additives
Authors: Skrypnikova Ekaterina , Kaluzhina Svetlana , Popova Elena
Published: December 2008

It has been studied the influence of the organic additive - glycine on copper anodic behavior in alkaline mediums. It was established, that under 1×10-4 to 1×10-1 M concentration amino acid stimulates copper anodic processes and causes metal local activation. The obtained experimental data was interpretated according to peculiarities of copper passive state and metal complexation processes with amino acid anion. It was suggested the assumption of an opportunity of glycine oxidation under 0.80V
Investigation of System Dynamics in a Corrosion Process by Optical and Electrochemical Methods
Authors: Mayorga-Cruz Darwin , Sarmiento-Martinez Oscar , Uruchurtu-Chavarin Jorge
Published: December 2008

A brief investigation is presented in an electrochemical corrosion cell consisting of 99.5% aluminum sample immersed in 3% NaCl and hydrocarbon-chloride solution emulsion, which reaction processes were optically monitored using Michelson interferometry. An image processing method applied on obtained interferograms allowed to calculate oxide corrosion layer thickness formed over the metal surface. Additionally a theoretical model consisting of a two bi-dimensional difference equation system is proposed, in order to explain evolution of optical interference pattern maxima observed as a function of time for corrosion process, and also to establish a growth-competition model for the maxima fringes evolution and consequently for the oxide layer and corrosion system dynamics. Bifurcation diagrams showing equation system solution regions were additionally obtained based on the nonlinear dynamic behavior of corrosion processes showing chaotic dynamics.
Production and Investigation of Corrosion Inhibitors on Basis of POD-oils
Authors: Ostapenko Gennady I. , Gloukhov Pavel A. , Sadivskiy Sergey Ya. , Pisareva Valentina S. , Sabitov Salikh S.
Published: December 2008

The modified organic wastes of the caprolactam are investigated by potentiodynamic and impedance technique as corrosion inhibitor of carbon steel in 20 mass % hydrochloric acid solutions. It is shown that the investigated inhibitor retards mainly anodic reaction. The corrosion process is simulated by a parallel circuit of constant phase element and the corrosion resistance connected in series with the solution resistance. The inhibition efficiency reaches 92 ... 93 % at 1 mass % concentration of inhibitor.
Graded Anodic Films for Corrosion Protection of Aerospace Alloys: Anodizing Procedure and Corrosion Behaviour
Authors: Curioni Michele , Skeldon Peter , Thompson George , Ferguson John
Published: December 2008

The presence of alloying elements such as copper, magnesium and zinc in the 2xxx and 7xxx aluminium alloys increases mechanical properties but requires specific anticorrosion measures such as anodizing followed by painting. In this work, the performance of the anodic film was initially examined showing that, for a fixed anodizing electrolyte, a finer porous film morphology, generated at reduced potentials, provides better corrosion resistance than a coarser morphology generated at increased potentials. Complementing the previous, the effects of addition of tartaric acid to the anodizing electrolyte were examined, showing that tartaric acid does not affect significantly the porous film growth, but it reduces the dissolution rate of a previously formed oxide. Further, it was demonstrated that tartaric acid acts as an anodic inhibitor at concentrations in the ppm range, suggesting that the contributions to the anticorrosion performance are due to residues of tartaric acid in the pore solution.
Preparation and Protective Properties of Composite Films of Poly(3,4-etylenedioxythiophene) with Seteropolyanions on Stainless Steel
Authors: Adamczyk Lidia M. , Kulesza Pawel J.
Published: December 2008

Protective properties against pitting corrosion of thin coatings (on stainless steel) of poly(3,4-ethylenedioxytiophene), PEDOT, doped with phosphodedecamolybdate or silicodedecamolybdate are described here. PEDOT serves as a stable host matrix for large negatively charged polymolybdate inorganic species. Consequently, due to the formation of denser structures and to the existence of electrostatic repulsion effects, the composite coatings are capable of largely blocking access of pitting-causing anions (chlorides) to the surface of stainless steel. Reference is given to selected literature reports dealing with application of the conducting polymer type films to the pitting corrosion protection.
Corrosion Performance Evaluation of Zn/Al Galvanized Steels Using the Scanning Vibrating Electrode Technique (SVET)
Authors: Taylor Christopher , Elvins Jon , Sullivan James , Worsley David
Published: December 2008

The scanning vibrating electrode technique (SVET) provides a useful and rapid means to measure corrosion performance. It enables the number, location and intensity of anodic and cathodic events in corroding systems to be quantified. Strip steel samples were Zn galvanized with Al additions from 5wt% to 6.1wt%. Following microstructural characterization the samples were subjected to corrosion testing in 0.1% NaCl solution. Increasing the Al level in the galvanized layer for commercial strip steel improves corrosion performance with SVET determined Zn loss of 288µg at 5% compared to 148µg at 6.1% additions respectively. With addition of 5.5wt% Al, it may also be possible to reduce the coating weight of the galvanized layer without adversely affecting the corrosion performance with Zn loss of 238.78µg at the surface and 134.32µg at the cut edge.
Effect of Equal Channel Angular Extrusion on Corrosion Behavior of Al-Mn ALLOY
Authors: Namahoot Jutatip , Davenport A. , Ambat Rajan , Afseth Andreas , Scamans Geoff M.
Published: December 2008

Effect of deformation on the corrosion behaviour of Al-1Mn-0.4Fe-0.3Si model alloy was studied after equal channel angular extrusion (ECAE) to different levels and subsequent annealing treatment. During polarisation, cathodic reactivity of the samples increases with the degree of ECAE deformation. Microstructure showed more number of intermetallic particles after ECAE deformation as well as after annealing. ECAE deformation also increased the anodic reactivity. Observed electrochemical behaviour is attributed to intermetallic particles as they good cathodic sites and precipitation of particles deplete manganese from matrix leading to higher anodic activity.
Corrosion Protection With Transistor-Like Structures
Authors: Sreevatsa Sreeya , Zhang Yan , Grebel Haim
Published: December 2008

Control scheme of ionic currents in a three-terminal electrochemical cell is proposed. This is achieved by introducing a permeable, multi-layered structure which has electronic doping, such as, p-n, or, p-n-p between the typically the counter and working electrodes.
Corrosion Inhibition of Copper by Selected Thiol Compounds
Authors: Qafsaoui Wafaa , Kendig Martin W. , Takenouti Hisasi , Huet Francois
Published: December 2008

Electrochemical analysis of the corrosion inhibiting performance of two di-sulfide bases, the salts of 2,5 dimercapto-1,3,4 thiadiazole (DMTD) and 1-pyrrolidine dithiocarbamate (PYRR) in neutral NaCl for pure copper demonstrates that the compounds inhibit anodic and cathodic reactions and they exhibit synergy as a 1:1 mixture under open circuit conditions. The inhibitors are both anodically electro-active which may allow the irreversible formation of protective coatings. At open circuit the combination of the two inhibitors behaves synergistically and results in a corrosion exchange current density for Cu in 0.2 M NaCl of 0.03µA/cm2.
Effect of Rotation Rate in the Electrochemical Behavior of Aluminum Anodic Alloys
Authors: Orozco-Cruz R. , Gálvan-Martínez R. , Martínez E. A. , Genesca Juan
Published: December 2008

Cathodic protection of steel structures immersed in marine media uses sacrificial anodes of Zinc (Zn) or Aluminum (Al) alloys. The flow conditions, in which they are operating, have an injurious effect accelerating the problems of degradation of these materials. In this work electrochemical tests were carried out in Al-Zn-Mg anodic alloys. Mg was used in different concentrations ranging from 5.5 to 8.5 at.% maintaining constant the amount of Zn in 5.3 at. %. In order to get the controlled flow condition a Rotating Cylinder Electrode (RCE) was used. Corrosion potential (Ecorr), Linear Polarization Resistance (Rp), Polarization Curves and Electrochemical Impedance Spectroscopy (EIS) were carried out to get the electrochemical behavior of the cylindrical working electrodes. The effect of the flow conditions indicated a diminution of Rp values and therefore increases the corrosion rate.
Electrokinetic Treatment Applied to Sandy and Clay Soils
Authors: Sumbarda Ramos Emgdia G. , Oropeza Mercedes T. , Escobar Guerrero Víctor , González Ignacio
Published: December 2008

Electrokinetic soil treatment is a physicochemical method in which the contaminant's movement is oriented by the electric field. During this process three transport mechanisms occur: Electro-migration, electrophoresis and electro-osmosis. It is necessary to study the physicochemical interactions between the soil and the contaminant, also the effect of the aqueous phase properties in order to determine the predominant transports phenomena occurring during an electrokinetic extraction. In this paper, the effect of the soil texture was analyzed since it has a direct connection with the soil cation exchange capacity and buffering capacity.
Recent Developments in Organosilicon Electrochemistry
Authors: Jouikov Viatcheslav V.
Published: December 2008

Electrochemistry of organic derivatives of silicon started more than 30 years ago with the reductive cleavage of Si-Cl bonds. Since then, silyl anions - primary intermediates of this process, - were extensively exploited to form disilanes and polysilanes. Recently it was shown that electrochemical activation of Si-Cl bonds under special conditions offers the opportunity to generate not only R3Si- species but a large palette of specific and highly reactive silicon intermediates as well such as silanones, silyl peroxides and silyl radicals. Electrogeneration of transient silanones prepared in situ from the basic starting material - chloro, alkoxy and alkylthiosilanes - allow functionalization of commercial siloxanes and polysiloxanes by inserting a new XYSiO fragment carrying various organic functional groups (X,Y) into the backbone of the target siloxane. Silyl radicals, electrochemically produced by different ways, make possible direct silylation of unsaturated compounds. Electrochemical behavior of stable disilenes, digermenes, silatranes and silylium-type species has also been studied.
Effect of β-CD on the Electrochemical Behavior of Tenoxicam
Authors: Guzmán Hernández Dafne , Ramírez-Silva Maria T. , Alarcón Ángeles Georgina , Rojas-Hernándéz Alberto
Published: December 2008

The manuscript Tenoxicam is a non-steroidal pharmaceutical that acts as anti-inflamatory, anti-pyretic and analgesic. It is amply used to treat rheumatic affections, from which it stems the importance to maintain its chemical stability through formation of an inclusion complex with β-ciclodextrin, β-CD. This work presents the results concerning the cyclic voltammetry studies carried out on tenoxicam at different pH in the presence of β-CD in aqueous media, and the analysis of the acid-base species which intervene as part of the Tenoxicam-β-CD interactions.
In-situ Electrochemical Generation of Ferrate Ion [Fe(VI)] in Acidic Conditions: A Potential Wastewater Decontamination Process
Authors: Villanueva Minerva , Hernandez Aracely , Peralta-Hernandez Juan M. , Bandalab Erick R. , Quiróz Marco A.
Published: December 2008

Ferrate ion [Fe(VI)] has been electrochemically generated in-situ in acidic aqueous conditions for the oxidation of an organic compound in bulk solution for the first time. The electrochemical synthesis of [Fe(VI)] in perchloric acid (HClO4) solution was carried out over inert electrode of boron-doped diamond (BDD) in the presence of different ferrous solution concentrations in a undivided cell. The ferrate ion electrochemically generated in-situ was directly supplied to promote the oxidation of a common dye, Acid yellow 36 (AY-36), has not been reported before. The results show that the complete removal of AY-36 can be achieved in a shorter time than using typical electro-oxidation processes (EOP) over BDD electrodes.
The Effect of Zeta Potential on the Electrokinetic Process for Removal of Phenanthrene in Soil
Authors: Feria Rossy , García-Jiménez M. G. , Solana Gabriel , Oropeza Mercedes T.
Published: December 2008

This paper deals with the effects of pH, electrolyte concentration on electrophoretic mobility respect to zeta potential and Debye distance of clay particles. The result show that the difference of zeta potential is -2.1 mV, in the mixture water and Triton X-114. The values of the surfactants are -48.8 mV, for SDS and 46.73 mV, for CTAB, they are present a greater molecular interaction with clay surfaces. However, the zeta potential and the Debye distance decrease of 45*10-8 m2s-1V-1 in the presence of NaCl to 120*10-8 m2s-1V-1 in the presence surfactants, the pHiep of each of these mixtures in Milli-Q-water is 6.15, and in different concentration of NaCl solutions are: 6.13 in 2 mM, 6.42 in 5 mM, 6.25 in 10 mM and 6.12 in 15 mM. The result indicated that the salt concentration of the suspension solution have a consist effect in the zeta potential and Debye distance.
Evaluation of antioxidant capacity by triiodide methods
Authors: Reza-Dávila Julio Cesar , Avilés-Rodríguez Diego , Gomez Martin , Cortés-Arroyo Alma Rosa , Domínguez-Ramírez Adriana M.
Published: December 2008

Different methods have been developed for measuring the total antioxidant capacity. This work proposes a method based on the oxidation of antioxidants by triiodide. Antioxidant capacity was measured under controlled conditions such as concentrations of KI and KI3, and pH values. The amount of present antioxidants was determined by indirect spectrophotometric method, through which the excess triiodide ion remaining after reaction with antioxidants was quantified. For samples presenting inconveniences for spectrophotometric measurements, amperometric titration curves and bipotentiometric titration curves using a pair of platinum electrodes were proposed. The analytic methods with triiodide are simple, fast and useful for the quantification of most antioxidants. The antioxidant capacity (TAC) was determined in different samples such: tablets, capsules, green tea and orange juice. The TAC can be expressed as Trolox equivalents.
On the Origin of Non-monotonic, Twofold Conductivity Relaxation of BaCe0.95Yb0.05O2.975 upon Hydration/Dehydration
Authors: Yoo Han-Ill , Kim Jong-Kyu , Lee Chung-Eun
Published: December 2008

Electrical conductivity relaxations were measured at a fixed temperature (700oC) on proton-conducting BaCe0.95Yb0.05O2.975 upon sudden changes of water-vapor activity in fixed oxygen activity atmospheres in the ranges of -4.5<log aO2<0.02 and -5.0<log aH2O<-2.0. It has been confirmed that the conductivity relaxes, in general, with two different relaxation times or twofold, but always non-monotonically. This twofold relaxation is attributed to the superposition of the two chemical diffusion processes of component H and O driven by a water chemical potential gradient. The analytic solution to the non-monotonic relaxation is presented in closed form, and thereby evaluated the two chemical diffusivities governing the hydration/dehydration kinetics.
Ultra-thin Y-doped Zirconia Electrolyte Membranes Synthesized under Photon Irradiation: Structure Evolution and High Temperature Electrochemical Transport Studies
Authors: Tsuchiya Masaru , Ramanathan Shriram
Published: December 2008

Synthesis and characterization of Y-doped zirconia (YDZ) thin films grown under UV-photon irradiation are reported in this article. Zr-Y metal precursor alloy thin films were successfully oxidized into cubic crystalline zirconia at room temperature under ultra-violet (UV) irradiation. Detailed transmission electron microscopy studies reveal that films are pin-hole free and form distinct grain boundaries upon high temperature annealing. In-plane ac impedance spectroscopy studies indicate that UV grown films have comparable electrochemical properties to the YDZ films grown by other methods. UV synthesis would be an attractive route to grow high quality ultra-thin oxide electrolytes at relatively low temperatures.
Electrical and Interfacial Properties for a New Class of Oxide Ionic Conductors, La9.33+xSi6O26+1.5x
Authors: Mineshige Atsushi , Nakao Takayuki , Kobune Masafumi , Yazawa Tetsuo , Yoshioka Hideki
Published: December 2008

Dense solid electrolytes based on lanthanum silicate, La9.33+xSi6O26+1.5x (LSO, x = -0.33, 0.00, 0.34, 0.67, 1.00 and 1.34 on the weighed basis) were fabricated and their phase relations and electrical conducting properties were studied. The total conductivity (σ) increased monotonously with x up to x = 0.67, and the σ of the weighed composition, La10Si6O27 (x = 0.67), whose real composition was La9.69Si6O26.54 (x' = 0.36), was the highest (7.4×10­3 S•cm­1 at 873 K) though it was not in a single phase region. This specimen showed almost P(O2)-independent conductivity, while a slight increase in conductivity with increasing P(O2) was observed in the high temperature region. The current-voltage characteristic of a fuel cell utilizing the dense LSO electrolyte was also investigated employing metal or mixed conducting electrodes.
Densification and Electrical Conductivity of Yttria-Stabilized Zirconia Containing NiO Additions
Authors: Batista Rafael M. , Muccillo Eliana N.
Published: December 2008

The role of NiO addition on sintering and electrical conductivity of 8YSZ was systematically studied in this work. Nickel carbonate was added to commercial 8YSZ to give 0.5, 1 and 5 mol% Ni. Sintering of powder compacts was carried out at several dwell temperatures and soaking times. Relative sintered density of Ni-doped pellets reached high values for short soaking times. For longer soaking times the densification of 8YSZ is higher than that of specimens containing the additive. Cubic NiO is the secondary phase formed when the additive exceeds the solubility limit, as determined by Raman spectroscopy. The grain conductivity does not change with additive up to 1 mol% independent on the soaking time. The grain boundary conductivity varies slightly in doped pellets and is lower in NiO-free samples.
Li ion Migration in Li3PO4 Electrolytes: Effects of O Vacancies and N Substitutions
Authors: Du Yaojun A. , Holzwarth Natalie A.
Published: December 2008

Motivated by recent developments in solid electrolytes based on lithium phosphorous oxynitride (LiPON) materials, we carried out computer simulations in order to develop an understanding of the detailed mechanisms of ionic transport. Starting with crystalline Li3PO4, we investigated some possible structures of isolated defects associated with extrinsic Li ion vacancies and interstitials. In particular, we identified a "PNP" structure which involves a bridging N between two phosphate groups, formed from the combination of an O vacancy and a N substitution, stabilizing a Li ion vacancy. We also studied the effects of N substituting for a tetrahedral O in a phosphate group which stabilizes a Li interstitial ion. In addition to studying the structures of these isolated defects as sources of extrinsic mobile Li ions, we also modeled their effects on the mobilities of the ions.
Effect of Minor Additions of CeO2 on Conductivity of Perovskites with Mixed Ionic-Electronic Conductivity
Authors: Konysheva Elena , Irvine John T.S.
Published: December 2008

Conductivity, structure and thermochemical stability of compositions in the following series (100-x)La0.6Sr0.4CoO3•xCeO2 (LSCC), (100-x)La0.8Sr0.2MnO3•xCeO2 (LSMC) and (100-x)La0.95Ni0.6Fe0.4O3•xCeO2 (LNFC), where x= 0, 2 and 10 mol%, were studied. CeO2 has slightly higher solubility limit in La0.6Sr0.4CoO3 and La0.8Sr0.2MnO3 compared to La0.95Ni0.6Fe0.4O3, forming LSCC2 and LSMC2 single phase solid solutions. All compositions containing more than 2 mol% ceria were two phase and consisted of a perovskite constituent with rhombohedral structure and ceria with cubic structure. Small additions of CeO2 influence the conductivity of the modified perovskites in a different way. Conductivity in the LSCC series dramatically decreased. Adding up to 10 mol % CeO2 slightly changed the total conductivity in the LSMC series in spite of the presence of the secondary phase. The conductivity of the perovskites as a function of oxygen partial pressure (0.21-10-4 atm) is discussed.
Studies on Defect Structures of (La,Sr)2NiO4 by Using X-ray Absorption Spectroscopy
Authors: Ina Toshiaki , Orikasa Yuki , Fukutsuka Tomokazu , Amezawa Koji , Kawada Tatsuya , Uchimoto Yoshiharu
Published: December 2008

Ni K-edge X-ray absorption spectroscopy was applied to investigate the electronic and defect structures of La2-xSrxNiO4{plus minus}δ (x = 0 - 1.0) annealed under various oxygen partial pressures. X-ray absorption near edge structure (XANES) indicated that the mean valence of Ni ions increased by increasing Sr contents and oxygen partial pressure, accompanied by variation of oxygen nonstoichiometry, in the composition range having excess oxygens and oxygen vacancies. Ni L-edge XANES spectra of La2-xSrxNiO4{plus minus}δ were used to decide the valence state and the spin state of Ni ions. By increasing Sr contents and oxygen partial pressure, it was found that Ni(II) ions decreased and the low spin state of Ni(III) ions increased.
The Course of Oxygen Partial Pressure and Electric Potentials across an Oxide Electrolyte Cell
Authors: Jacobsen Torben , Mogensen Mogens
Published: December 2008

Solid oxide fuel cells and electrolyzers are usually based on yttrium stabilized zirconia (YSZ) as electrolyte. Although the transport number of oxide ions in YSZ at normal conditions is not below 0.999 the electron and hole conductivity may be of practical importance. In long term operation it may cause oxygen pressure to build up in closed cavities inside the electrolyte. Fundamental concepts as electric and electrochemical potential are discussed, and revive the concept electromotive potential originally introduced by Bro̸nsted. This potential is equivalent to the Fermi level and is useful in the discussion of electronic conduction in mixed conductors. On the bases of a solution to the transport equations for oxide ions, electrons and holes, potential profiles across the cell are calculated for fuel cell and electrolyzer applications. One main result of the analysis is the verification that in steady state operation, the oxygen pressure inside a cavity can never exceed the value corresponding to the electrode potential.
ITM Ceramic Membrane Technology to Produce Synthesis Gas
Authors: Carolan Michael , Chen Christopher , Chen Jack , Miller Christopher , Minford Eric , Waldron William
Published: December 2008

Air Products and its partners are developing Ion Transport Membrane (ITM) technology for the production of synthesis gas, a mixture of hydrogen and carbon monoxide. The ITM Syngas process is a breakthrough technology that combines air separation and high-temperature synthesis gas generation processes into a single ceramic membrane reactor, with significant savings in the capital cost of synthesis gas production. Because synthesis gas is a feedstock for a range of different processes, ITM Syngas represents a technology platform that has numerous applications, such as hydrogen, clean fuels and chemicals. ITM ceramic membranes are fabricated from non-porous, mixed-metal oxides and operate with exceptionally high oxygen flux and selectivity when exposed to an oxygen chemical potential gradient at high temperatures. Significant advances have been made in developing and scaling up the ITM Syngas technology. This paper describes the development of commercial-size ceramic membranes and the ITM Syngas reactor system. Recent laboratory and pilot unit test results will also be discussed.
Finite Element Modeling of Idealized Infiltrated Composite Solid Oxide Fuel Cell Cathodes
Authors: Nicholas Jason D. , Barnett Scott A.
Published: December 2008

Using a two-dimensional finite element approach, the polarization resistance of idealized, branched, nano-particulate, composite cathodes was determined. Porous CGO, LSGM, or YSZ networks infiltrated with additional ionic conductor and subsequently infiltrated with LSCF or BSCF were modeled. For fixed mixed conductor particle size, dual nano-particle infiltrations (ionic + mixed conductor) resulted in an order of magnitude polarization resistance decrease, compared to single component mixed conductor infiltrations. For most SOFC relevant temperatures (500-900C), geometries, and material combinations, cathode performance was limited by the charge transfer reaction occurring at the mixed conductor interface and therefore scaled with the cathode surface area, as long as the cathode thickness was <~10microns. For cathodes thicker than ~10microns, losses within the ionic conducting network determined performance, resulting in a breakdown of the linear performance dependence on cathode surface area. The boundary between these regimes varied with ionic conducting cathode arm width, column width, and ionic conductivity.
A Simple CNT Supported Electrocatalysts Preparation Method by Electro-Reduction
Authors: Lim Tae Wook , Chu Young-Hwan , Bang Heekyung , Choi Hyung-Uk , Cho June-Seok , Kim Dong-Lae , Kim Hyun-Jong , Han M.K.
Published: December 2008

We developed a novel preparation method of carbon nanotube supported catalysts based on the electrochemical reduction process. Our method doesn't require any organic solvents and additives such as ethylene glycol and surfactants because this is water based process. First, Pt hydroxide nanoparticles are deposited on the hydrochloric acid treated carbon nanotube to prepare so-called pre. Pt/CNT sample. The catalysts with various wt% are prepared through the reduction by applying the potential to our pre. Pt/CNT samples. The obtained catalysts show higher electrochemical active surface area than the commercial Pt/C catalysts.
Leptin resistance: a prediposing factor for diet-induced obesity
Authors: Scarpace Philip J. , Zhang Yi
Published: December 2008

Obesity is a resilient and complex chronic disease. One potential causative factor in the obesity syndrome is leptin resistance. Leptin behaves as a potent anorexic and energy-enhancing hormone in most young or lean animals, but its effects are diminished or lacking in the obese state associated with a normal genetic background. Emerging evidence suggests that leptin resistance predisposes the animal to exacerbated diet-induced obesity (DIO). Elevation of central leptin in young, lean rats induces a leptin resistance that precludes obesity on a chow diet but accelerates high-fat (HF)-induced obesity. Similarly, chronic dietary fructose consumption evokes a leptin resistance that causes obesity only upon HF exposure. Inherent central leptin insensitivity also contributes to dietary weight gain in certain obesity-prone rats. Conversely, aged, leptin-resistant animals are obese with continuous chow feeding and demonstrate aggravated obesity when challenged with an HF diet. Additionally, a submaximal central blockade with a leptin antagonist leads to obesity on both chow and HF diets, as is the case in rodents with leptin receptor deficiency of genetic origin. Despite the differences in the incidence of obesity on a chow diet, all of these forms of leptin resistance predispose rodents to aggravated HF-mediated obesity. Moreover, once leptin resistance takes hold, it aggravates DIO, and the leptin resistance and obesity compound one another, promoting a vicious cycle of escalating weight gain.
Hypercapnic vs. hypoxic control of cardiovascular, cardiovagal, and sympathetic function
Authors: Steinback Craig D. , Salzer Deborah , Medeiros Philip J. , Kowalchuk J. , Shoemaker J. Kevin
Published: December 2008

We compared the integrated cardiovascular and autonomic responses to hypercapnia and hypoxia to test the hypothesis that these stimuli differentially affect muscle sympathetic nerve activity (MSNA) discharge patterns and cardiovagal and sympathetic baroreflex function in a manner related to ventilatory chemoreflex sensitivity. Six males and six females underwent 5 min of hypoxia (end-tidal Po2= 45 Torr) and 5 min of hypercapnia (end-tidal Pco2= +8 Torr from baseline), causing similar ventilatory responses. A downward right shift in cardiovagal set point was observed during both conditions, which was strongly related to the change in inspiratory time (Ti) from baseline to hypercapnia ( r2= 0.67, P = 0.007) and hypoxia ( r2= 0.79, P < 0.001). Cardiovagal baroreflex gain was decreased during hypoxia (20.1 ± 6.9 vs. 8.9 ± 5.1 ms/mmHg, P < 0.001) but not hypercapnia (26.7 ± 12.7 vs. 23.0 ± 9.1 ms/mmHg). Both hypoxia and hypercapnia increased MSNA burst amplitude, whereas hypoxia, but not hypercapnia, also increased in MSNA burst frequency (21 ± 9 vs. 28 ± 7 bursts/min, P = 0.03) and total MSNA (4.56 ± 3.07 vs. 7.37 ± 3.26 mV/min, P = 0.002). However, neither hypercapnia nor hypoxia affected sympathetic burst probability or baroreflex gain. Hypoxia also caused a greater reduction in total peripheral resistance ( P = 0.04), a greater increase in heart rate ( P = 0.002), and a trend for a greater cardiac output response ( P = 0.06) compared with hypercapnia. Nonetheless, central venous pressure remained unchanged during either condition. These results suggest that hypercapnia and hypoxia exert differential effects on cardiovagal, but not sympathetic, baroreflex gain and set point in a manner not related to ventilatory chemoreflex sensitivity. Furthermore, the data suggest that the individual's respiratory pattern to hypoxia or hypercapnia, as reflected in the inspiratory time, was a strong determinant of cardiovagal baroreflex set- point rather than the total ventilatory chemoreflex gain per se.
MnTMPyP, a cell-permeant SOD mimetic, reduces oxidative stress and apoptosis following renal ischemia-reperfusion
Authors: Liang Huan Ling , Hilton Gail , Mortensen Jordan , Regner Kevin , Johnson Christopher P. , Nilakantan Vani
Published: December 2008

Oxidative stress and apoptosis are important factors in the etiology of renal ischemia-reperfusion (I/R) injury. The present study tested the hypothesis that the cell-permeant SOD mimetic manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP) protects the kidney from I/R-mediated oxidative stress and apoptosis in vivo. Male Sprague-Dawley rats (175–220 g) underwent renal I/R by bilateral clamping of the renal arteries for 45 min followed by reperfusion for 24 h. To examine the role of reactive oxygen species (ROS) in renal I/R injury, a subset of animals were treated with either saline vehicle (I/R Veh) or MnTMPyP (I/R Mn) (5 mg/kg ip) 30 min before and 6 h after surgery. MnTMPyP significantly attenuated the I/R-mediated increase in serum creatinine levels and decreased tubular epithelial cell damage following I/R. MnTMPyP also decreased TNF-α levels, gp91phox, and lipid peroxidation after I/R. Furthermore, MnTMPyP inhibited the I/R-mediated increase in apoptosis and caspase-3 activation. Interestingly, although MnTMPyP did not increase expression of the antiapoptotic protein Bcl-2, it decreased the expression of the proapoptotic genes Bax and FasL. These results suggest that MnTMPyP is effective in reducing apoptosis associated with renal I/R injury and that multiple signaling mechanisms are involved in ROS-mediated cell death following renal I/R injury.
Relation of Locus Coeruleus Neurons in Monkeys to Pavlovian and Operant Behaviors
Authors: Bouret Sebastien , Richmond Barry J.
Published: December 2008

Noradrenaline is released throughout the forebrain from locus coeruleus (LC) projections in close temporal proximity to emotional and goal-directed events. To examine interactive influences of these processes on LC neuronal activity, we used a task where Pavlovian and operant processes vary and can be easily identified. We recorded 69 single LC neurons from two monkeys performing a task where cues indicate the progression through schedules of one, two, or three operant trials. Pavlovian responses and phasic LC activations occur following the appearance of conditioned visual cues (54/69 neurons), especially those at the beginning of new schedules, whether the current trial will be rewarded (single trial schedule) or not (2 or 3 trial schedules), and after visual imperative signals eliciting the operant response (64/69 neurons), whether the current trial will be rewarded or not. The modulation of LC responses seems to be relatively independent of attention or motivation, because the responses do not covary with operant performance in the task. The magnitude of LC responses across the schedules varied in close relation to the intensity of Pavlovian behavior but these responses were also modulated by operant processes. Our conclusion is that LC activation occurs when task-relevant stimuli evoke a conditioned instinctive (Pavlovian) response, with the strength of the activation also being modulated by goal-directed processes. Thus locus coeruleus neurons broadcast information about stimulus-elicited primitive and goal-directed behaviors to forebrain structures important for executive functions and emotions.
Changes in the Limb Kinematics and Walking-Distance Estimation After Shank Elongation: Evidence for a Locomotor Body Schema?
Authors: Dominici Nadia , Daprati Elena , Nico Daniele , Cappellini Germana , Ivanenko Yuri P. , Lacquaniti Francesco
Published: December 2008

Little is known on the role that knowledge about body dimensions plays within this process. Here we directly addressed this question by evaluating whether changes in body proportions interfere with computation of traveled distance for targets located outside the reaching space. We studied locomotion and distance estimation in an achondroplastic child (ACH, 11 yr) before and after surgical elongation of the shank segments of both lower limbs and in healthy adults walking on stilts, designed to mimic shank-segment elongation. Kinematic analysis of gait revealed that dynamic coupling of the thigh, shank, and foot segments changed substantially as a result of elongation. Step length remained unvaried, in spite of the significant increase in total limb length (∼1.5-fold). These relatively shorter strides resulted from smaller oscillations of the shank segment, as would be predicted by proportional increments in limb size and not by asymmetrical segmental increment as in the present case (length of thighs was not modified). Distance estimation was measured by walking with eyes closed toward a memorized target. Before surgery, the behavior of ACH was comparable to that of typically developing participants. In contrast, following shank elongation, the ACH walked significantly shorter distances when aiming at the same targets. Comparable changes in limb kinematics, stride length, and estimation of traveled distance were found in adults wearing on stilts, suggesting that path integration errors in both cases were related to alterations in the intersegmental coordination of the walking limbs. The results are consistent with a dynamic locomotor body schema used for controlling step length and path estimation, based on inherent relationships between gait parameters and body proportions.
Cs2CO3/[bmim]Br as an Efficient, Green, and Reusable Catalytic System for the Synthesis of N-Alkyl Derivatives of Phthalimide under Mild Conditions
Authors: Hasaninejad Alireza , Zare Abdolkarim , Moosavi-Zare Ahmad Reza , Khedri Fatemeh , Rahimi Rahimeh , Khalafi-Nezhad Ali
Published: December 2008

Aza-conjugate addition of phthalimide to α,β-unsaturated esters efficiently achieves in the presence of catalytic amount of Cs2CO3 and ionic liquid 1-butyl-3-methylimidazolium bromide ([bmim]Br) under mild reaction conditions (70°C) to afford N-alkyl phthalimides in high yields and relatively short reaction times.
Antidiabetic Rosiglitazone Reduces Soluble Intercellular Adhesion Molecule‐1 Level in Type 2 Diabetic Patients with Coronary Artery Disease
Authors: Wang Guang , Zhang Zhe , Yu Jie , Zhang Fuchun , He Liyun , Wei Jinru , Mao Jieming , Wang Xian
Published: December 2008

Background. We investigated the level of soluble adhesion molecules in diabetic patients and the effect of the peroxisome proliferator‐activated receptor‐γ (PPAR‐γ) agonist rosiglitazone on plasma levels of adhesion molecules and an inflammation marker in type 2 diabetic patients with coronary artery disease (CAD) after percutaneous coronary intervention (PCI). Methods. A total of 116 diabetic patients with CAD who had undergone PCI were randomized to receive rosiglitazone (4 mg/d) or not for 6 months. Plasma levels of soluble intercellular adhesion molecules (sICAM‐1) and P‐selectin (sP‐selectin) were measured on ELISA. Results. After 6‐month rosiglitazone treatment, plasma levels of sICAM‐1 were lower than baseline and control group levels (370.4 (332.4–421.9) pg/mL versus 423.5 (327.4–500.3) pg/mL and 404.6 (345.2–483.4) pg/mL, P < .001). In addition, plasma levels of C‐reactive protein were significantly reduced from baseline levels. However, plasma level of sP‐selectin was not significantly lowered with rosiglitazone treatment than with control treatment after 6‐month follow‐up. Conclusions. Rosiglitazone reduces chronic inflammatory responses and improves levels of markers of endothelial dysfunction in patients with diabetes and CAD. PPAR‐γ agonist may have a beneficial effect on the vascular endothelium through its anti‐inflammatory mechanism and may be useful as therapy in patients undergoing PCI.
A New Translinear-Based Dual-Output Square-Rooting Circuit
Authors: Kumngern Montree , Dejhan Kobchai
Published: December 2008

A new wide input range square-rooting circuit is presented. The proposed circuit consists of a dual translinear loop, an absolute value circuit, and current mirrors. A current-mode technique is used to provide wide input range with simple circuitry. The output signal of the proposed circuit is the current which is proportional to the square root of input current. The proposed square-rooting circuit was confirmed by using PSpice simulator program. The simulation results demonstrate that the proposed circuit provides the excellent temperature stability with wide input current range.