bluuebunny/crossref_metadata_2025 huggingface dataset:
An assessment of exceedance probabilities of envelope curves
Authors: Vogel Richard M. , Matalas Nicholas C. , England John F. , Castellarin Attilio
Published: July 2007

Envelope curves are often used to provide summary accounts of our flood experience, but their operational use has been limited by our previous inability to assign to them an exceedance probability “EP.” General expressions are derived for the EP of an envelope curve at a particular site in a heterogeneous region, as well as measures of central tendency of EP across sites. Analytic results are reported for the case when floods follow a Gumbel or generalized extreme value distribution, and these results are contrasted with those of previous studies that sought to estimate the exceedance probability of extraordinary floods such as the flood of record (FOR) and the probable maximum flood (PMF). A case study involving FOR and PMF discharges for 226 rivers across the U.S.A. indicates that relatively consistent estimates of the average exceedance probability associated with both FOR and PMF envelope curves can be obtained using the theoretical approach introduced here.
A computational framework for simulation of biogeochemical tracers in the ocean
Authors: Khatiwala Samar
Published: July 2007

A novel computational framework is introduced for the efficient simulation of chemical and biological tracers in ocean models. The framework is based on the “transport matrix” formulation, a scheme for capturing the complex three‐dimensional transport of tracers in a general circulation model (GCM) as a sparse matrix, thus reducing the task of simulating tracers to a sequence of simple matrix‐vector products. The principal advantages of this formulation are efficiency and convenience. It is many orders of magnitude more efficient than GCMs, allowing us to address problems that are currently either difficult or unaffordable with GCMs. The scheme also allows us to quickly “prototype” new biogeochemical parameterizations or “plug in” existing ones. This paper describes the key features and advantages of the transport matrix method, and illustrates its application to a series of realistic problems in chemical and biological oceanography. The examples range from simulation of a transient tracer (SF6) to adjoint sensitivity of a complex coupled biogeochemical model. Finally, the paper describes an efficient, portable, and freely available implementation of this computational scheme that provides the necessary framework for simulating any biogeochemical tracer.
Control of land‐ocean temperature contrast by ocean heat uptake
Authors: Lambert F. Hugo , Chiang John C. H.
Published: July 2007

We show that the ratio of observed annual‐mean land temperature change to ocean surface temperature change, ϕ, has remained almost constant during 1955–2003. This is the case, despite most of the heat capacity of the climate system lying in the oceans, and rapid variations in climate forcing. Examining seven General Circulation Models (GCMs), we find land and ocean temperature behavior comparable to observations in six cases. For three models that reproduce observed ϕ and for which we have data, we find no significant changes in future ϕ under the SRES A1B scenario. We suggest that variations in land‐ocean heat flux primarily balanced by ocean heat uptake are sufficient to maintain constant ϕ. This flux is present in the six GCMs that resemble observations, suggesting that observed ϕ may remain constant into the future, even if radiative forcing is markedly different than in the past.
Atrial tachycardia induces remodelling of muscarinic receptors and their coupled potassium currents in canine left atrial and pulmonary vein cardiomyocytes
Authors: Yeh Y‐H , Qi X , Shiroshita‐Takeshita A , Liu J , Maguy A , Chartier D , Hebert T , Wang Z , Nattel S
Published: July 2007

Background and purpose:

Both parasympathetic tone and atrial tachycardia (AT) remodelling of ion channels play important roles in atrial fibrillation (AF) pathophysiology. Different muscarinic cholinergic receptor (mAChR) subtypes (M2, M3, M4) in atrial cardiomyocytes are coupled to distinct K+‐currents (calledIKM2,IKM3,IKM4, respectively). Pulmonary veins (PVs) are important in AF and differential cholinergic current responses are a potential underlying mechanism. This study investigated AT‐induced remodelling of mAChR subtypes and K+‐currents in left‐atrial (LA) and PV cardiomyocytes.

Experimental approach:

Receptor expression was assayed by western blot.IKM2,IKM3andIKM4were recorded with whole‐cell patch‐clamp in LA and PV cardiomyocytes of nonpaced control dogs and dogs after 7 days of AT‐pacing (400 bpm).

Key results:

Current densities ofIKM2,IKM3andIKM4were significantly reduced by AT‐pacing in LA and PV cardiomyocytes. PV cardiomyocyte current–voltage relations were similar to LA for all three cholinergic currents, both in control and AT remodelling. Membrane‐protein expression levels corresponding to M2, M3and M4subtypes were decreased significantly (by about 50%) after AT pacing. Agonist concentration–response relations for all three currents were unaffected by AT pacing.

Conclusions and implications:

AT downregulated all three mAChR‐coupled K+‐current subtypes, along with corresponding mAChR protein expression. These changes in cholinergic receptor‐coupled function may play a role in AF pathophysiology. Cholinergic receptor‐coupled K+‐currents in PV cardiomyocytes were similar to those in LA under control and AT‐pacing conditions, suggesting that differential cholinergic current properties do not explain the role of PVs in AF.

British Journal of Pharmacology(2007)152, 1021–1032; doi:10.1038/sj.bjp.0707376; published online 9 July 2007
The contribution of cyclooxygenase‐2 to endocannabinoid metabolism and action
Authors: Fowler C J
Published: July 2007

The development of sensitive analytical methods for measurement of endocannabinoids, their metabolites, and related lipids, has underlined the complexity of the endocannabinoid system. A case can be made for an ‘endocannabinoid soup’ (akin to the inflammatory soup) whereby the net effect of a pathological state and/or a pharmacological intervention on this system is the result not only of changes in endocannabinoid levels but also of their metabolites and related compounds that affect their function. With respect to the metabolism of anandamide and 2‐arachidonoylglycerol, the main hydrolytic enzymes involved are fatty acid amide hydrolase and monoacylglycerol lipase. However, other pathways can come into play when these are blocked. Cyclooxygenase‐2 derived metabolites of anandamide and 2‐arachidonoylglycerol have a number of properties, including effects upon cell viability, contraction of the cat iris sphincter (an effect mediated by a novel receptor), mobilization of calcium and modulation of synaptic transmission. Nonsteroidal anti‐inflammatory agents, whose primary mode of action is the inhibition of cyclooxygenase, can also interact with the endocannabinoid system bothin vitroandin vivo. Other enzymes, such as the lipoxygenase and cytochrome P450 oxidative enzymes, can also metabolize endocannabinoids and produce biologically active compounds. It is concluded that sensitive analytical methods, which allow for measurement of endocannabinoids and related lipids, should provide vital information as to the importance of these alternative metabolic pathways when the primary hydrolytic endocannabinoid metabolizing enzymes are inhibited.

British Journal of Pharmacology(2007)152, 594–601; doi:10.1038/sj.bjp.0707379; published online 9 July 2007
Kaurane diterpenes protect against apoptosis and inhibition of phagocytosis in activated macrophages
Authors: de las Heras B , Hortelano S , Girón N , Bermejo P , Rodríguez B , Boscá L
Published: July 2007

Background and purpose:

The kaurane diterpenes foliol and linearol are inhibitors of the activation of nuclear factor κB, a transcription factor involved in the inflammatory response. Effects of these diterpenes on apoptosis and phagocytosis have been analysed in cultured peritoneal macrophages and in the mouse macrophage cell line, RAW 264.7.

Experimental approach:

Macrophages were maintained in culture and activated with pro‐inflammatory stimuli in the absence or presence of diterpenes. Apoptosis and the phagocytosis in these cells under these conditions were determined.

Key results:

Incubation of macrophages with a mixture of bacterial lipopolysaccharide (LPS)/interferon‐γ (IFN‐γ) induced apoptosis through a NO‐dependent pathway, an effect significantly inhibited by foliol and linearol in the low μM range, without cytotoxic effects. Apoptosis in macrophages induced by NO donors was also inhibited. The diterpenes prevented apoptosis through a mechanism compatible with the inhibition of caspase‐3 activation, release of cytochrome c to the cytosol and p53 overexpression, as well as an alteration in the levels of proteins of the Bcl‐2 family, in particular, the levels of Bax. Cleavage of poly(ADP‐ribose) polymerase, a well‐established caspase substrate, was reduced by these diterpenes. Treatment of cells with foliol and linearol decreased phagocytosis of zymosan bioparticles by RAW 264.7 cells and to a greater extent by peritoneal macrophages.

Conclusions and implications:

Both diterpenes protected macrophages from apoptosis and inhibited phagocytosis, resulting in a paradoxical control of macrophage function, as viability was prolonged but inflammatory and phagocytic functions were impaired.

British Journal of Pharmacology (2007) 152, 249–255; doi:10.1038/sj.bjp.0707382
Porous Vanadium/Titanium Oxides—Synthesis, Characterization, and Photocatalytic Activity
Authors: Zhou Meifang , Huang Fuzhi , Wang Xingdong , du Plessis Johan , Murphy Anthony B. , Caruso Rachel A.
Published: July 2007

Sol–gel chemistry and a templating technique were combined for the synthesis of vanadium/titanium oxides with controlled porous structure and various quantities of vanadium (0–9.7 at-%). The specific surface area of the porous vanadium/titanium oxides increased with increasing vanadium content to a maximum of 72 m2 g–1 at 6.6 at-% V, with a corresponding decrease in anatase crystal size (minimum of 12.4 nm), and c-axis lattice parameter (0.9475 nm). The optical band-gap decreased substantially from 3.10 eV for TiO2 to 2.53 eV on the addition of 9.7 at-% V. The adsorption capability of the oxides for aqueous methylene blue (pH ~6) increased significantly with increasing vanadium content (26.7 to 318.9 mg L–1 g–1 for 0 to 9.7 at-% V). The photodegradation of methylene blue was most efficient with the 0.9 at-% V-TiO2 sample for both UV and visible light irradiation.
Optical Effects of Metallic Nanoparticles
Authors: Dahmen Christian , von Plessen Gero
Published: July 2007

Metallic nanoparticles show a rich optical behaviour because of their strong light absorption and scattering, wide spectral tunability, and interesting optical near-field effects. Research into optical effects of metallic nanoparticles, a field with a long tradition, has been developing rapidly in recent years as a result of progress in nanoparticle fabrication, spectroscopic techniques, and computational methods. This article provides a survey of optical effects of metallic nanoparticles, covering both fundamental phenomena and emerging applications.
The Paradoxes of Racism
Authors: Dunn John
Published: July 2007

IN ITS MOST ELABORATELY ARTICULATED FORM RACISM IS AN array of theoretical views about the epistemic clarity and human import of the practice of individuating human populations in terms of their presumed biological descent. In this form the term can refer with some precision, and largely independently of context, to a quite specific body of beliefs. In far more diffuse and far less theoretical forms, however, and in forms which are also far more widely distributed in human history, it can and does refer just as readily to the highlighting of distinctions which are certainly at least as much cultural as they are genetic, and which are inextricably located in a context of more or less intimate and painful confrontation between human groups. In this second form there cannot in principle be anything comparably determinate for the term racism to refer to.
l‐Arabinose transport and catabolism in yeast
Authors: Fonseca César , Romão Rute , Rodrigues de Sousa Helena , Hahn‐Hägerdal Bärbel , Spencer‐Martins Isabel
Published: July 2007

Two yeasts, Candida arabinofermentans PYCC 5603T and Pichia guilliermondii PYCC 3012, which show rapid growth on l‐arabinose and very high rates of l‐arabinose uptake on screening, were selected for characterization of l‐arabinose transport and the first steps of intracellular l‐arabinose metabolism. The kinetics of l‐arabinose uptake revealed at least two transport systems with distinct substrate affinities, specificities, functional mechanisms and regulatory properties. The l‐arabinose catabolic pathway proposed for filamentous fungi also seems to operate in the yeasts studied. The kinetic parameters of the initial l‐arabinose‐metabolizing enzymes were determined. Reductases were found to be mostly NADPH‐dependent, whereas NAD was the preferred cofactor of dehydrogenases. The differences found between the two yeasts agree with the higher efficiency of l‐arabinose metabolism in C. arabinofermentans. This is the first full account of the initial steps of l‐arabinose catabolism in yeast including the biochemical characterization of a specific l‐arabinose transporter.
Confucian Theology: Three Models
Authors: Huang Yong
Published: July 2007

If there are still disagreements about whether Confucianism is a religion, there seems to be a consensus that Confucianism does not have a theology. In this article, I attempt to show that there are at least three models of serious god‐talks in the Confucian tradition: (i) heaven is discussed in the Confucian classics ofBook of Documents,Books of Poetry, andAnalectsas something transcendent of the world, similar to Christian God in crucial aspects; (ii) heaven is discussed among contemporary Confucians, represented by Xiong Shili, Mou Zongsan, and Tu Weiming, as something ‘immanently transcendent’, the ultimate reality immanent in the world to transcend the world; and (iii) heaven is discussed by neo‐Confucians, particularly the Cheng brothers of the Song dynasty, as the wonderful life‐givingactivitytranscending the world within the world.
Linguistic Contributions to the Advancement of Racial Justice Within and Beyond the African Diaspora
Authors: Baugh John
Published: July 2007

As a rule, linguistic diversity has little to do with racial diversity. However, studies in Africa, Europe, and North and South America have documented that standard and nonstandard dialects are often divided along socially and racially stratified lines. Results in this discussion grow from studies of linguistic profiling in France, South Africa, and the USA regarding the devaluation of Black Speech. Studies of housing discrimination against Blacks and Latinos in the USA, along with preliminary analyses of linguistic attitudes throughout the African diaspora, reveal that employment, education, housing, and access to other goods and services may be influenced by linguistic stereotypes. Here we explore various interdisciplinary controversies that are closely intertwined, with primary emphasis on the USA, where studies in linguistic profiling are most advanced. Experiments that build upon Lambert's classical matched guise technique explore various demographic characteristics that listeners attribute to someone based on the sound of his or her voice, such as during a telephone conversation. These experiments are linked directly with attempts to advance racial justice in education, law, health care and economic transactions, along with corresponding policy implications.
Bringing the learning organisation to your workplace
Authors: Skinner Howard
Published: July 2007

The article describes an educational intervention designed for a traditional primary health care team. The intervention consisted of a series of educational exercises designed to enhance team member self efficacy and provide experience of a variety of effective shared learning strategies. The primary health care team were then given the opportunity to apply this new knowledge and skills to designing their own teaching sessions as part of a practice teaching competition. The evaluative framework and feedback from the participants demonstrating achievement of the learning outcomes are then described.
Ureteric colic: new trends in diagnosis and treatment
Authors: Masarani M , Dinneen M
Published: July 2007

The diagnostic approach to ureteric colic has changed due to the introduction of new radiological imaging such as non-contrast CT. The role of intravenous urography, which is regarded as the gold standard for the diagnosis of ureteric colic, is being challenged by CT, which has become the first-line investigation in a number of centres. The management of ureteric colic has also changed. The role of medical treatment has expanded beyond symptomatic control to attempt to target some of the factors in stone retention and thereby improve the likelihood of spontaneous stone expulsion.
Primary care management of patients with carpal tunnel syndrome referred to surgeons: are non-operative interventions effectively utilised?
Authors: Burke Frank D , Bradley Mary J , Sinha Shiladitya , Wilgis E F Shaw , Dubin Norman H
Published: July 2007

Aim

To investigate the non-operative primary care management (splintage, task modification advice, steroid injections and oral medications) of carpal tunnel syndrome before patients were referred to a hand surgeon for decompression.

Design and setting

Preoperative data were obtained on age, gender, body mass index, employment, symptom duration, and preoperative clinical stage for patients undergoing carpal tunnel decompression (263 in the USA, 227 in the UK).

Results

Primary care physicians made relatively poor use of beneficial treatment options with the exception of splintage in the US (73% of cases compared with 22.8% in the UK). Steroid injections were used in only 22.6% (US) and 9.8% (UK) of cases. Task modification advice was almost never given. Oral medication was employed in 18.8% of US cases and 8.9% of UK cases.

Conclusions

This study analyses the non-operative modalities available and suggests that there is scope for more effective use of non-operative treatment before referral for carpal tunnel decompression.
Bird flu: if or when? Planning for the next pandemic
Authors: Sellwood Chloe , Asgari-Jirhandeh Nima , Salimee Sultan
Published: July 2007

Avian influenza or “bird flu” is causing increasing concern across the world as experts prepare for the possible occurrence of the next human influenza pandemic. Only influenza A has ever been shown to have the capacity to cause pandemics. Currently A/H5N1, a highly pathogenic avian influenza virus, is of particular concern. Outbreaks of this disease in birds, especially domestic poultry, have been detected across Southeast Asia at regular intervals since 2003, and have now affected parts of Africa and Europe. Many unaffected countries across the world are preparing for the possible arrival of HPAI A/H5N1 in wild birds and poultry within their territories. All such countries need to prepare for the rare possibility of a small number of human cases of HPAI A/H5N1, imported through foreign travel. Although it is by no means certain that HPAI A/H5N1 will be the source of the next pandemic, many countries are also preparing for the inevitable occurrence of human pandemic influenza.
Online educational tools developed by Heart improve the knowledge and skills of hospital doctors in cardiology
Authors: Walsh Kieran , Rafiq Isma , Hall Roger
Published: July 2007

We conducted this study to find out if online learning packages in cardiology enabled users to increase their knowledge and skills. We also looked at how acceptable users found these packages. The journal Heart in association with BMJ Learning produced a series of modules on common cardiology problems. The modules involved a pre-test, a number of interactive cases and a post-test. A total of 1786 users completed these modules. Doing the modules enabled users to improve their score from the pre-test to the post-test by a significant amount (p<0.001). Feedback to the modules was very positive.
Correlated Fermi-Liquid State Formed with Overlapping Kondo Clouds
Authors: Shiba Hiroyuki , Fazekas Patrik
Published: July 2007

A simple variational description is given on the nature of overlapping Kondo clouds, which compensate the localized f-spins in the Kondo lattice. It is shown explicitly that the f-electrons participate in forming a “large Fermi surface”, although they are strictly localized. The resulting correlated Fermi liquid, i.e., heavy fermions, is examined with the variational Monte Carlo method and is compared with the Gutzwiller approximation. The relation to the periodic Anderson model is also discussed in this connection.
Relation between Crack Width and Diameter of Rebar Loss Due to Corrosion of Reinforced Concrete Members
Authors: Muñoz Noval Alejandro , Andrade Carmen , Torres Andrés , Rodríguez Jesús
Published: July 2007

Reinforcement corrosion leads into several damages which influence the structural load-bearing capacity, among which can be mentioned the cracking of concrete cover. This work study formulations to estimate the crack width of structural elements from the data of corrosion rate measured in two structural elements, made in 1990, with chlorides added in the concrete mix. These elements, one T beam and one column, were exposed at the atmosphere of Madrid, Spain. Two expressions have been fitted to the results: w = k Px / (c/f) and w = k Px / Ro, where w is a crack width in the time, k is a proportional factor, Px is the corrosion penetration in the time, c/f is the concrete cover/diameter relation and Ro is the original radius of the bar. The first expression has resulted the most adequate.
Electrochemical Measurements in Cement Extract Solutions on Reinforcing Steel, Previously Conditioned in Concrete
Authors: Koleva Dessi , de Wit J.H.W. , van Breugel Klaas , Bachvarov Vassil , Kolev Hristo , Fraaij Alex
Published: July 2007

The corrosion behavior of reinforcing steel, previously embedded in concrete and maintained in conditions of corrosion and two regimes (conventional and pulse) of cathodic protection (CP), was characterized using electrochemical measurements in cement extract (CE) solutions of pH 12.6. The investigation aimed at determination of the properties of the product layers, previously formed on the steel surface. The study further allowed evaluation of the CP effectiveness in terms of steel surface oxidation/reduction behavior in the alkaline medium of CE. Based on the similar electrochemical behavior of protected specimens, it can be concluded that the pulse CP is as effective as the conventional CP regime. Moreover, the surface film, formed in pulse CP conditions appears to be more homogeneous and resistive, compared to the conventional CP regime.
The Use of Polarization Resistance to Evaluate the Environmental Impact on Reinforced Concrete Structures in the Iberoamerican Region
Authors: Troconis de Rincón Oladis M. , Andrade Carmen , Barboza M , Irassar F , Montenegro J C. , Vera R , Carvajal A M. , de Gutierrez R M. , Delvasto S , Saborio E , Torres-Acosta A. A. , Perez-Quiroz J , Almeraya Facundo , Castro-Borges Pedro , Moreno E I. , Perez-Lopez T , Martinez W , Salta M , de Melo A P. , Martinez I , Castellote M , Rodriguez G , Derregibus M , Sanchez M , de Partidas E A. , Millano Valentina
Published: July 2007

This work presents the three-year results of the project: Effect of the environment on reinforcement durability (DURACON), which is investigating the influence of the meteorochemical parameters of marine and coastal-marine environments on concrete durability performance, by measuring the electrochemical parameters (corrosion rate and corrosion potential) of the embedded reinforcing steel. To that effect, concrete specimens were exposed to the marine environments making a total of 21 test stations distributed among ten countries (Argentina, Bolivia, Chile, Colombia, Costa Rica, Mexico, Spain, Uruguay, Portugal and Venezuela). This paper presents the reinforcement electrochemical evaluation, which allows identifying its corrosion activation. The chloride ions concentration which induces the reinforcement corrosion is also presented, depending on the environment to which the concrete specimens were exposed.
Corrosion-Related Failure of Post Stressed Tendons
Authors: Tromans Desmond
Published: July 2007

The structure and placement of unbonded post stressed tendons is discussed briefly, together with regard to possible problems relating to ingress of water between the outer polyethylene sheath and inner stressed steel strand. Premature corrosion and failure of some tendons after fourteen years service in a floor slab are examined via optical and scanning electron microscopy (SEM) and related to conditions occurring within the tendons. Water penetration caused localized crevice corrosion of individual wires in the strand via formation of oxygen concentration cells, consistent with in-situ pH measurements of the water environment in the tendon. Initially, such corrosion propagated as cracks transverse to the axis of the individual wires. Subsequent hydrolysis reactions within the crevices/cracks produced local pH conditions conducive to hydrogen embrittlement and crack propagation along the wire axis, consistent with cracking observed under hydrogen charging conditions.
Electrochemical Noise Corrosion Monitoring of Post Tensioned Tendons
Authors: Taveira Luciano , Joseph Babu , Sagüés Alberto A.
Published: July 2007

The reliability and sensitivity of electrochemical noise technique in large area strand-anchor systems were investigated. Potential and current noise transients associated to pitting corrosion were clearly observed upon events simulating water leakage in assemblies using a plain cement grout. In contrast, the water addition did not affect the electrochemical noise response in similar assemblies using a commercial low-bleed grout. For the assemblies showing electrochemical noise a plausible average pit size of 4 micrometers was estimated as being associated with individual noise transients. A system resolution as small as 1 microV and 20 nA range was reached for the potential and current noise respectively.
Runoff-Induced Atmospheric Corrosion of Zinc
Authors: Meraz Ebelia A. , Veleva Lucien P. , Acosta Manuel A.
Published: July 2007

During two years atmospheric corrosion process (metal loss) and runoff progress of zinc and galvanized steel where monitored. Metal samples were exposed to tropical humid climate in two environments (rural and urban) in the Gulf of México (Tabasco, Mexico). The rain events, as promoters of runoff process were registered and analyzed for ionic composition, pH and conductivity. The zinc runoff progress was monitored after each pluvial event, collecting runoff solutions from the metal samples in exposure, in order to determine the zinc mass loss, as a part of soluble, released corrosion products. The atmospheric corrosion of zinc fits a linear equation that relates the zinc corrosion with several environmental parameters. A schematic representation of zinc atmospheric corrosion products detected in humid tropical climate is also presented.
The Influence of Inclusions and Naphthenic Acids on the Corrosion of Pipeline Steels
Authors: Schütz Priscila , Castilhos Érica , Rodrigues Luciana Machado , Dick Luís Frederico P.
Published: July 2007

Aiming to simulate the internal corrosion of pipeline and oil tank steels exposed to decanted waters, the electrochemical behavior and corrosion morphology of these steels was studied in 10-2 mol/L Na2SO4 solutions, with additions of naphthenic acids in dependence of the inclusions distribution. A linear correlation between the pitting potential in sulfate solutions and inclusions concentration of -20mV x Inclusions Density (inclusions/mm2) could be determined. The localized attack associated to the sulfide inclusions turns increasingly to a more uniform attack, as the concentration of the naphthenic cyclopentanecarboxylic acid in the dilute sulfate solution is increased.
Morphology and Kinetic Effect of Combined Nd and Pr on the Oxidation of a Fe-13Cr Alloy
Authors: Martínez Villafañe Alberto , Chacon-Nava Jose , Borunda-Terrazas Adan , Almeraya-Calderon Facundo , Gonzalez-Rodríguez Gonzalo
Published: July 2007

The addition of rare earth elements (REÉs) i.e. Neodymium (Nd), Praseodymium (Pr) or Ytterbium oxide (Yb2O3) on the oxidation behavior of a Fe-13Cr alloy has been studied, and its role on the oxidation rate, oxide morphology and formation is discussed. It was found that a simultaneous addition of both elements i.e. Nd and Pr into the alloy produced a dramatic reduction in the oxidation kinetics. Analysis by SEM revealed that the morphology of oxides formed on Fe-13Cr specimens with and without REÉs specimens was very different. In fact, fine-grained oxide morphology was observed for alloys with REÉs addition.
Metal Dusting Corrosion of Nickel-Based Alloys
Authors: Chun Charlie , Bhargava Gaurang , Ramanarayanan Trikur
Published: July 2007

Metal dusting corrosion of nickel-based alloys (i.e. Inconel 600, 601 and 693) has been simulated in high carbon activity environments over a temperature range from 450 to 750oC. Overall, Ni-based alloys corrode by a combination of carbon diffusion and precipitation in the alloy interior and atom migration through surface carbon deposits. The formation of protective surface oxide films provides initial protection against metal dusting, but local rupture of surface Cr-rich oxide films allows rapid carbon diffusion into the alloy. The focus of this research is to advance the understanding of the corrosion mechanisms of Ni-based alloys by characterizing interfacial processes at the nanometer level. In addition to the effect of temperature and environmental chemistry, the mechanistic aspects of metal dusting are discussed with particular attention to the stages of microstructure evolution as degradation proceeds.
Oxidation and Volatilization of SiC in a Hydrogen-Rich Rocket Engine Environment
Authors: Opila E.
Published: July 2007

C/SiC coupons with thick CVD SiC coatings were exposed in the pressure chamber of a hydrogen/oxygen engine. Nominal pressures were 6.8 bar or 34 bar. Oxygen to fuel ratios varied between 1.5 to 2.3 corresponding to theoretical gas temperatures between 1700 and 2250K. Gas velocities averaged 173 m/s. SiC recession was measured intermittently for total exposure times between 2 to 60 minutes. Recession rates were modeled assuming that material consumption was limited by transport of Si-O-H(g) species through a gas boundary layer. Si (OH)4(g) and SiO(OH)(g) were predicted to be the dominant volatile species and calculated recession rates were within an order of magnitude of measured rates.
Studies of Phase Stability and Microstructure in the Ta-C System
Authors: DiPietro Steve , Wuchina E. , Opeka Mark M. , Buesking Kent , Matson Larry , Spain Jack
Published: July 2007

This study focused on the processing and characterization of materials in the Ta-C system, focusing primarily on the phase composition, microstructure, and flexure strength. Hot isostatic pressing of tantalum and carbon mixtures at T=1800- 2100C at pressures up to 210 MPa produced dense ceramics with TaC and Ta2C as the primary phases. XRD results show that the Ta2C phase forms when the carbon content in the powder mixture falls below TaC0.70. SEM characterization shows that the TaC phase has an equiaxed morphology, while the Ta2C phase has an elongated platelet morphology. The phase content also had a major effect on the mechanical behavior of the materials as well. While both materials show purely elastic stress-strain behavior at room temperature (with Ta2C having higher flex strength), the Ta2C showed some rollover of the stress-strain curve at elevated temperatures, indicating more ductile behavior than TaC.
The Oxidation of 1-Propanol by CuO
Authors: DeVore Tom , Peretich Michael
Published: July 2007

The kinetics for the oxidation of 1-propanol by unsupported copper (II) oxide were measured at temperatures less than 700 K using flow kinetics. This oxidation produced propanal initially. The reaction order in 1-propanol changed from 2 to 1 at a temperature of ~ 515 K. The averaged values for the apparent activation energy for the production of propanal were 130 + 8 kJ mol-1 at temperatures below 515 K and 25 + 10 kJ/ mole at temperatures above 515 K. The Arrhenius pre- exponential factors (A) for the low and high temperature regions were 2 x 1013 min-1and 144 min-1 respectively. A mechanism that can explain the observed kinetics has been developed and is presented. Catalytic combustion of the 1- propanol to produce carbon dioxide was the only reaction observed at temperatures over 585 K
Study of Electrodeposition of Molybdenum-Tin Alloys
Authors: Morón-Vera Lydia E. , Torres Julieta
Published: July 2007

This paper describes the first attempts to form the molybdenum- tin alloy by electrodeposition. Molybdenum is one of the metals that cannot be electrodeposited directly from simple electrolytes, for this reason we decided a codeposition with tin. To accomplish the deposition we add a complexing agent, sodium citrate, (C6H5O7) and study by cyclic voltammetry (CV), the effects that it has over the tin and molybdenum reduction potentials were observed. The sodium citrate shifted the tin reduction potential towards more cathodic values, since it was not enough to place it near the molybdenum reduction potential, we studied the effect of some others additives such as PEG of different molecular weights and Triton X-100. Two layers deposits were also done in order to obtain the alloy. The deposits obtained were analyzed by scanning electronic microscopy (SEM) and energy-dispersive X-ray spectrometer (EDS) microanalysis.
Effect of Porous Oxide Films on Characterization and Bioactivity of Titanium Niobium Alloy by Electrochemical Treatments
Authors: Peng Pen-Wen , Pan Yung-Ning , Ou Keng-Liang
Published: July 2007

Titanium-based alloys are widely used as biomaterials for replacing failed hard tissues because of their favorable mechanical properties and excellent biocompatibility. However, the Ti-6Al-4V alloy has the poor capability of wear resistance may release the metallic ions. It may result in the poor osseointegration and then induces clinical failure. Furthermore, the elastic modulus of Ti-6Al-4V alloy (112 GPa) is higher than that of cortical bones (10~30 GPa), which induce the stress shielding effect. Therefore, new titanium alloys that compose of nontoxic and nonallergic elements and good biomechanical compatibility have been studied widely. In the present study, electrochemical treatment was performed to modify the mechanical properties of Ti-Nb alloys. In order to realize the properties of Ti-Nb alloys with and without treatments, the specimens were evaluated by electrochemical measurements and material analyses. The influences of titanium hydride compounds on the formation of porous structural titanium oxide by electrochemical surface treatment was investigated by XPS, TF- XRD, SEM and XTEM. Porous TiO2 film was formed after anodization with cathodic pretreatments. The TiH1.971 is formed by cathodic pretreatments. Furthermore, the porous Ti- Nb formed by dissolution of TiH1.971 wre changed to porous TiO2. The TiH1.971 plays an important role in forming porous TiO2. The anodization with cathodic pretreatment not only produces titanium hydride layer, but also results in formation of porous structural titanium oxide. It is believed that bioactive titanium implant with oxidation and nanostructure can be enhanced and integrated bone interface contact.
Voltammetric Characterization of [ReO]3+ Containing Complexes
Authors: Cerdá Bresciano María Fernanda , Kremer Carlos , Castro Luna Ana Maria , Mendez Eduardo
Published: July 2007

In the present work, the voltammetric profiles of Au-pc in 1 mM solutions of K[ReVOCl2(L)] (L = dianions of H2hida or H2eida; hida, n-(2,6-dimethylphenyl carbamoylmethyl)imino diacetic acid, and eida, 2,6-diethyl ida) complexes were evaluated. The obtained electrochemical response was the result of the contributions coming from the [ReO]3+ core (Epa at ca. 0.2 V vs. Ag/AgNO3) and the carboxylic group of the ligand. There where also observed redox contributions ascribed to the presence of perrhenate coming from the decomposition of the complex with the lost of ligands, in agreement with the low stability of the studied complexes.
Peculiarities of Voltammetry and Dissociation of Hydroxycarboxylic Acids
Authors: Kvaratskhelia Elene -. , Kvaratskhelia Ramaz
Published: July 2007

The study of voltammetry of two hydroxycarboxylic acids: D-tartaric and citric acids at the electrodes from Pt, Cu, Ta, Cu-Hg and alloys of Cd with Sn, Ni, Hg, In in aqueous solutions shows that these acids in all cases form the hydrogen ions discharge process waves. With the aid of the suggested by authors method the values of the degrees of dissociation of various hydroxycarboxylic acids (D-, L-, DL-, meso-tartaric, citric, malic acids) in the concentration range 0.0001-0.01M and the pH range 1-4 were calculated.
Towards a Nano-Scale Electrochemical and Spectroscopic Characterization of Organic Layers on Oxide Surfaces
Authors: Hubin Annick , Hauffman Tom , Blajiev Orlin , Snauwaert Johan , Van Haesendonck Chris , Terryn Herman
Published: July 2007

The presented works prepares the ground for galvanic deposition of metallic overlayers on metal oxide surfaces functionalized by phosphonic acid monolayers. In view of this goal, it is necessary to control the most important factors of the electrodeposition process (e.g. flatness and uniformity of distribution). Because of these requirements, in this work, we study the morphology and the interaction between PO(OH)2-functionalities and an oxide surface. The analysis is carried out using complementary surface analysis techniques, like Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). We have succeeded in creating a blank surface with a RMS roughness of less than 1 nm and a hydroxyl fraction of 17%. The organic deposition was followed in time and it was observed that Volmer Weber multilayer growth was present. Also the influence of carbon contamination was characterized and a methodology is presented to correct the experimental data for this ambient contamination.
Electrochemical Nucleation of Zinc onto Glassy Carbon
Authors: Plata Magdalena , Olvera Seydi , Ramírez-Rodríguez Claudia , Dorantes-Rosales Hector , Arce-Estrada Elsa M.
Published: July 2007

Metal electrodeposition onto diverse substrates continues to be a subject of significant interest for improved corrosion properties (coatings) and the production of integrated circuits. Among the metallic coatings used to protect steel surface, electrodeposited zinc and zinc alloys are important in both decorative and industrial applications. Unfortunately, in the common electrolytic baths (sulfates, acetates, chlorides), Zn electrodeposition is accompanied by the hydrogen evolution reaction (HER), which cause a competition between both processes. Therefore, in such circumstances, a quantitative evaluation of the kinetic parameters of the zinc electrocrystallization process is almost impossible. In this work, Zn electrodeposition was analyzed using a non- conventional support electrolyte as alternative method to separate the involved processes. Zn electrodeposition onto glassy carbon (GCE) was investigated using cyclic voltammetry (CV) and potential step technique in an aqueous solution 10-2 M ZnCl2, in 1M NH4Cl. The experimental current density transients showed that the mechanism of zinc electrodeposition in 1M NH4Cl occurs by multiple, progressive three-dimensional nucleation with controlled by mass transfer.
Formation of Porous Alumina Patterns on Silicon
Authors: Moral Vico Javier , Jansen Frederik , Maex Karen , Groeseneken Guido , Vereecken P. M.
Published: July 2007

The formation of thin alumina films directly on Si is reported. Galvanostatic and potentiostatic anodization in two- and three- electrode cell configurations are compared. Control of the electrode potential with a 3-electrode setup provides faster pore formation and organization than with control of the cell potential in a 2-electrode configuration. Higher pore density and smaller pore sizes are obtained for potentiostatic control than for galvanostatic control. Internal consistency was found between equations describing the steady-state current-voltage characteristics and the pore density and size.
A Study of the Effect of Different Cadmium Sources on Chemical Bath Deposited CdS Thin Films
Authors: Khallaf Hani , Oladeji Isaiah , Chow Lee
Published: July 2007

A comprehensive study of the effect of the cadmium source on chemical bath deposited cadmium sulfide thin films is reported. Four different cadmium sources, namely cadmium sulfate, cadmium chloride, cadmium iodide, and cadmium acetate have been used. Single-dip, for 15 minutes, as well as multi-dip depositions (four successive depositions for 8-12 minutes each) were carried out at 70oC on quartz substrates. The effect of changing the cadmium source on the film optical/electrical properties as well as the film thickness was studied. Hall Effect measurements were carried out for all films as well as Rutherford Back Scattering (RBS), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM).
TiO2 Nanoparticles Role in NiB Films Formation with the Dynamic Chemical Plating Deposition Method
Authors: Stremsdoerfer Guy , Omidvar Hamid , Meas Y.
Published: July 2007

The dynamic chemical plating (DCP) is a new technique which avoids the stage of activation in the metallization of polymers. We have here the results concerning the formation of NiB composite film with TiO2 nano particles incorporation. The growth kinetics of the deposit increases on one hand, when the nanoparticles concentration in the suspension increases and on the other hand, when subjected to UV radiation. The EDAX probe analysis indicates the variation of Ti rate in the layer, for a concentration of suspension of 10g/l, according to whether the development of the deposit is subjected or not to UV radiation.
Study of the Failure Mechanism of the Cu/Epoxy Interface After Modifications by Means of Surface Chemical Reactions
Authors: Siau Sam , Vervaet Alfons A.
Published: July 2007

The chemical part of adhesion is studied at epoxy-copper interfaces. This is realized by creating epoxy surfaces with constant surface roughness by means of wet chemical pretreatments (sweller and oxidizer). These roughened epoxy surfaces are chemically transformed by nucleofilic substitutions using an anchoring molecule, 2-mercaptopyrimidine and glycerol. Cu is deposited by an electroless and electroplating scheme, followed by patterning. After patterning peel strengths are measured. The peeled epoxy surface and the backsides of the peeled Cu-strips are examined by means of XPS. These experiments are used to determine the influence of the interface atomic composition on the locus of failure during peeling.
A Spiderless Arachnophobia Therapy: Comparison between Placebo and Treatment Groups and Six-Month Follow-Up Study
Authors: Granado Laura Carmilo , Ranvaud Ronald , Peláez Javier Ropero
Published: July 2007

We describe a new arachnophobia therapy that is specially suited for those individuals with severe arachnophobia who are reluctant to undergo direct or even virtual exposure treatments. In this therapy, patients attend a computer presentation of images that, while not being spiders, have a subset of the characteristics of spiders. The Atomium of Brussels is an example of such an image. The treatment group (n=13) exhibited a significant improvement (time×group interaction:P=.0026) when compared to the placebo group (n=12) in a repeated measures multivariate ANOVA. Ak-means clustering algorithm revealed that, after 4 weeks of treatment, 42% of the patients moved from the arachnophobic to the nonarachnophobic cluster. Six months after concluding the treatment, a follow-up study showed a substantial consolidation of the recovery process where 92% of the arachnophobic patients moved to the nonarachnophobic cluster.
Comparison Study of Different BOD Tests in the Determination of BOD7Evaluated in a Model Domestic Sewage
Authors: Roppola Katri , Kuokkanen Toivo , Rämö Jaakko , Prokkola Hanna , Heiska Eeva
Published: July 2007

The aim of this research was to study the suitability of a manometric respirometric test (OECD 301F) for the determination of biological oxygen demand (BOD) in domestic wastewater. This was done by comparing four different BOD tests (a manometric respirometric test, oxygen sensor determination, iodometric titration, and UV absorption measurement) and by evaluating the BOD7value after a short-term measurement applying the manometric respirometric test. Measurements were done in three dif-ferent laboratories. The respirometric test was performed well on municipal sewage, and the precision of results was good. There were minor deviations between BOD7values as determined by the different methods, but the deviations were not essentially big enough to have a practical impact. Evaluation of the BOD7value after two or three days' incubation by the respirometric method was shown to work well; average deviations between measured and evaluated values after three days' incubation were 5–18%. Hence, the manometric respirometric test proved to be a rapid and suitable tool for process control purposes.
Simultaneous Determination of Cobalt(II) and Nickel(II) by Fourth-Order Derivative Spectrophotometric Method Using 2-Hydroxy-3-Methoxy Benzaldehyde Thiosemicarbazone
Authors: Kumar A. Praveen , Reddy P. Raveendra , Reddy V. Krishna
Published: July 2007

A simple and new simultaneous fourth derivative spectrophotometric method is proposed for the analysis of a two-component system containing cobalt(II) and nickel(II) without separation using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent reacts with cobalt(II) and nickel(II) at pH 6.0, forming soluble brown and yellow colored species, respectively. Cobalt(II) and nickel(II) present in the mixture are simultaneously determined without solving the simultaneous equations by measuring the fourth derivative amplitudes at 468.5 nm and 474.5 nm, respectively. The derivative amplitudes obey Beer's law at 468.5 nm and 474.5 nm for Co(II) and Ni(II) in the range 0.059–3.299μgmL-1and 0.058–3.285μgmL-1, respectively. A large number of foreign ions do not interfere in the present method. The present simultaneous method is used for the determination of micro amounts of cobalt in biological samples, nickel in plant samples, and in some alloy steels and soil sample.
Perinatal Changes of Cardiac Troponin-I in Normal and Intrauterine Growth-Restricted Pregnancies
Authors: Iacovidou Nicoletta , Boutsikou Maria , Gourgiotis Demetrios , Briana Despina D. , Baka Stavroula , Vraila Venetia-Maria , Kontara Louiza , Hassiakos Demetrios , Malamitsi-Puchner Ariadne
Published: July 2007

Intrauterine growth restriction (IUGR) implies fetal hypoxia, resulting in blood flow redistribution and sparing of vital organs (brain, heart). Serum cardiac Troponin-I (cTnI), a well-established marker of myocardial ischaemia, was measured in 40 mothers prior to delivery, the doubly clamped umbilical cords (representing fetal state), and their 20 IUGR and 20 appropriate-for-gestational-age (AGA) neonates on day 1 and 4 postpartum. At all time points, no differences in cTnI levels were observed between the AGA and IUGR groups. Strong positive correlations were documented between maternal and fetal/neonatal values (r≥.498,P≤.025in all cases in the AGA andr≥.615,P≤.009in all cases in the IUGR group). These results may indicate (a) normal heart function, due to heart sparing, in the IUGR group (b) potential crossing of the placental barrier by cTnI in both groups