Subsurface Inclusion Quantification Using Multi-Frequency Ultrasonic Surface Waves

Rolling contact fatigue (RCF) is one of the major sources of subsurface-initiated spalling in bearing components. These types of spalls initiate in regions where microcracks are formed due to a localized increase in stress from inclusions near the surface. Ultrasonic bulk inspection is a powerful method to detect defects in a large volume of steel. However, inclusions near the surface of a sample can elude detection because reflections from the inclusion can be masked by reflections from the sample surface. This limitation can be eliminated if ultrasonic surface wave methods are used for inspection. Surface waves have material displacements localized near the sample surface but decay with depth giving an effective inspection of depth on the order of the wavelength. Ultrasonic scattering from inclusions also is wavelength dependent and these two aspects can complicate the interpretation of ultrasonic experimental data. In this presentation, a model is described for the scattering of a surface wave by a subsurface spherical inclusion. The amplitude-versus-depth profile of a surface wave is combined with the solution for the scattering of a shear wave from a spherical scatterer in order to approximate the problem of interest. Trends of reflected amplitude with respect to inspection frequency, inclusion depth, and inclusion diameter are discussed first. Then a necessary calibration experiment is described that uses subsurface defects of known size created using femtosecond laser machining. A model of the calibration sample allows measurements on unknown samples to be interpreted quantitatively. The final analysis shows that the reflected amplitude from multiple frequency measurements can be used to characterize the size and depth of the subsurface inclusions

Effets des précipitations acides sur les écosystèmes aquatiques au Canada: Situation actuelle et future

Cet article représente une évaluation de l'état actuel et des tendances observées dans les écosystèmes lacustres, ainsi que de leur état futur probable lorsque les réductions d'émissions requises dans le cadre de l'Entente Canada-États-Unis sur la qualité de l'air auront été effectives. Outre une synthèse des faits saillants de ce dossier pour l'ensemble du Canada, le présent article s'appuie aussi sur l'ensemble des données physico-chimiques récentes (8874 échantillons) observées sur 2779 lacs de l'est canadien, ainsi que celles recueillies (1012 échantillons) sur 252 lacs de l'ouest canadien depuis 1985. Des données biologiques (poissons, benthos, zooplancton et oiseaux aquatiques) ont également été inventoriées pour identifier l'ampleur des dommages biologiques.Les nombreux lacs ayant subi une acidification anthropique récente sont situés pour la plupart dans l'est du Canada où les dépôts de SO- sont élevés. La sensibilité des sols influence également leur distribution spatiale. Durant la période s'échelonnant de 1981 à 1994, seulement 33% des 202 lacs faisant l'objet d'un suivi temporel dans l'est du Canada ont montré une amélioration significative de leur acidité (réduction) en réponse à la baisse des dépôts de SO- (11% des lacs ont subi une hausse d'acidité et 56% n'ont montré aucun changement). Plus de la moitié des lacs ayant récupéré se situent à proximité de Sudbury en Ontario. Plusieurs processus biogéochimiques sont responsables du retard dans la réversibilité de l'acidification. Pour cette raison, la récupération biologique a été très faible dans l'est canadien, exception faite de la région immédiate de Sudbury.Trois scénarios d'émissions ont été considérés: scénario 1: niveaux d'émission canadiens et américains de 1985; scénario 2: émissions canadiennes de 1994 et émissions américaines de 1990 ; scénario 3: réductions d'émissions américaines et canadiennes complétées. Ces scénarios de réductions d'émissions, qui ont été utilisés comme données d'entrée à des modèles stationnaires simulant la chimie des eaux de surface et qui ont été appliqués à cinq grandes zones lacustres du l'est canadien, suggèrent que la proportion de lacs "endommagés" (définis comme étant des lacs de pH<6) diminuera conséquemment aux réductions d'émissions américaines et canadiennes. De 11 à 49% des lacs acidifiés le resteront après l'ensemble des réductions prévues (scénario 3). Le Québec et l'Ontario, qui reçoivent actuellement les plus fortes retombées acides, bénéficieront le plus des réductions. Les gains environnementaux seront plus faibles dans l'est et dans l'ouest du Canada. De plus faibles dépôts acides et une contribution naturelle à l'acidité pourraient expliquer cette moins grande récupération.Il est maintenant reconnu que le pH est le principal facteur d'influence de la diversité spécifique du poisson, bien que d'autres facteurs comme la morphométrie du lac, l'altitude et les concentrations de COD soient aussi en partie responsables. Une réduction des dommages biologiques (i.e.baisse des disparitions de populations de poisson) serait donc possible, mais cette amélioration ne surviendra qu'après la hausse du pH des eaux de surface. L'importance relative des gains au plan biologique suivra une évolution similaire à celui des aspects chimiques. Des dommages significatifs aux écosystèmes lacustres subsisteront néanmoins après réalisation de l'ensemble des réductions d'émissions. Des pertes de populations de poissons devraient subsister dans 6% (Sudbury) à 15% (Kejimkujik) des lacs. Compte tenu du grand nombre de lacs situés dans le sud-est canadien, les pourcentages précédents impliquent que les ressources piscicoles perdues pourraient être très élevées. La restauration des communautés piscicoles devra passer dans bien des cas par un ré-enpoissonnement. De nouveaux programmes de contrôle visant des réductions supplémentaires d'émissions seront dès lors nécessaires pour protéger correctement les écosystèmes sensibles.This paper is an assessment of the current status and trends of Canadian lake systems, and their likely status after the effect of the emission controls required by the Canada/US Air Quality Agreement is fully realized. Many anthropogenically acidified lakes presently occur in that part of eastern Canada where SO- deposition is elevated. Terrain sensitivity also influences their spatial distribution. From 1981 to 1994, only 33% of 202 lakes monitored across eastern Canada showed a statistically significant improvement (reduction) in acidity in response to reduced SO- deposition (11% had increasing acidity and 56% showed no change). Over half of the improving lakes are near Sudbury, Ontario. Several biogeochemical processes are delaying de-acidification. As a result, there has been little biological recovery in eastern waters, except near Sudbury. Steady-state water chemistry modelling suggests that the proportion of "damaged" lakes (defined as having pH <6) will decline in response to both the Canadian and US emission controls. Reductions in biological damage (e.g. fewer lost fish populations) are expected also, but they will lag behind chemical improvement. Significant damage to aquatic ecosystems will remain after all chemical and biological improvements are realized. Further controls will be needed to protect sensitive ecosystems

Twin signed domination numbers in directed graphs

Let D=(V,A) be a finite simple directed graph (shortly digraph). A function f:V⟶{−1,1} is called a twin signed dominating function (TSDF) if f(N⁻[v])≥1 and f(N⁺[v])≥1 for each vertex v∈V. The twin signed domination number of D is γs*(D)=min{ω(f)∣f is a TSDF of D}. In this paper, we initiate the study of twin signed domination in digraphs and we present sharp lower bounds for γs*(D) in terms of the order, size and maximum and minimum indegrees and outdegrees. Some of our results are extensions of well-known lower bounds of the classical signed domination numbers of graphs

One-Pot synthesis, characterization and adsorption studies of amine-functionalized magnetite nanoparticles for removal of Cr (VI) and Ni (II) ions from aqueous solution: Kinetic, isotherm and thermodynamic studies

Background: Discharge of heavy metals such as hexavalent chromium (Cr (VI)) and nickel (Ni (II)) into aquatic ecosystems is a matter of concern in wastewater treatment due to their harmful effects on humans. In this paper, removal of Cr (VI) and Ni (II) ions from aqueous solution was investigated using an amino-functionalized magnetic Nano-adsorbent (Fe3O4-NH2). Methods: An amino-functionalized magnetic Nano-adsorbent (Fe3O4-NH2) was synthesized by compositing Fe3O4 with 1, 6-hexanediamine for removal of Cr (VI) and Ni (II) ions from aqueous solution. The adsorbent was characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), powder X-Ray Diffraction (XRD), and Vibrating Sample Magnetometry (VSM). Also, the effects of various operational parameters were studied. Results: According to our finding, Fe3O4-NH2 could be simply separated from aqueous solution with an external magnetic field at 30 s. The experimental data for the adsorption of Cr (VI) and Ni (II) ions revealed that the process followed the Langmuir isotherm and the maximum adsorption capacity was 232.51 mg g-1 for Cr (VI) at pH = 3 and 222.12 mg g-1 and for Ni(II) at pH = 6 at 298 °K. Besides, the kinetic data indicated that the results fitted with the pseudo-second-order model (R2: 0.9871 and 0.9947 for Cr (VI) and Ni (II), respectively. The results of thermodynamic study indicated that: standard free energy changes (�G�), standard enthalpy change (�H�), and standard entropy change (�S�) were respectively -3.28, 137.1, and 26.91 kJ mol-1 for Cr (VI) and -6.8433, 116.7, and 31.02 kJ mol-1 for Ni (II). The adsorption/desorption cycles of Fe3O4-NH2 indicated that it could be used for five times. Conclusions: The selected metals' sorption was achieved mainly via electrostatic attraction and coordination interactions. In fact, Fe3O4-NH2 could be removed more than 96 for both Cr (VI) and Ni (II) ions from aqueous solution and actual wastewater. © 2016 The Author(s)

Design, modeling, expression, and chemoselective PEGylation of a new nanosize cysteine analog of erythropoietin

Reza Ahangari Cohan1, Armin Madadkar-Sobhani2,3, Hossein Khanahmad1, Farzin Roohvand4, Mohammad Reza Aghasadeghi4, Mohammad Hossein Hedayati5, Zahra Barghi5, Mehdi Shafiee Ardestani4, Davoud Nouri Inanlou1, Dariush Norouzian11Research and Development Department, Production and Research Complex, Pasteur Institute of Iran, Tehran, Iran; 2Department of Bioinformatics, Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran; 3Department of Life Sciences, Barcelona Supercomputing Center, Barcelona, Spain; 4Hepatitis and AIDS Department, Pasteur Institute of Iran, Tehran, Iran; 5Quality Control Department, Production and Research Complex, Pasteur Institute of Iran, Tehran, IranBackground: Recombinant human erythropoietin (rhEPO) is considered to be one of the most pivotal pharmaceutical drugs in the market because of its clinical application in the treatment of anemia-associated disorders worldwide. However, like other therapeutic proteins, it does not have suitable pharmacokinetic properties for it to be administrated at least two to three times per week. Chemoselective cysteine PEGylation, employing molecular dynamics and graphics in in silico studies, can be considered to overcome such a problem.Methods: A special kind of EPO analog was elicited based on a literature review, homology modeling, molecular dynamic simulation, and factors affecting the PEGylation reaction. Then, cDNA of the selected analog was generated by site-directed mutagenesis and subsequently cloned into the expression vector. The construct was transfected to Chinese hamster ovary/dhfr- cells, and highly expressed clones were selected via methotrexate amplification. Ion-immobilized affinity and size exclusion (SE) chromatography techniques were used to purify the expressed analog. Thereafter, chemoselective PEGylation was performed and a nanosize PEGylated EPO was obtained through dialysis. The in vitro biologic assay and in vivo pharmacokinetic parameters were studied. Finally, E31C analog Fourier transform infrared, analytical SE-high-performance liquid chromatography, zeta potential, and size before and after PEGylation were characterized.Results: The findings indicate that a novel nanosize EPO31-PEG has a five-fold longer terminal half-life in rats with similar biologic activity compared with unmodified rhEPO in proliferation cell assay. The results also show that EPO31-PEG size and charge versus unmodified protein was increased in a nanospectrum, and this may be one criterion of EPO biologic potency enhancement.Discussion: This kind of novel engineered nanosize PEGylated EPO has remarkable advantages over rhEPO.Keywords: nanoPEGylated EPO, cysteine PEGylation, pharmacokinetic propert

Carbohydrate-active enzymes from the zygomycete fungus Rhizopus oryzae: a highly specialized approach to carbohydrate degradation depicted at genome level

<p>Abstract</p> <p>Background</p> <p><it>Rhizopus oryzae </it>is a zygomycete filamentous fungus, well-known as a saprobe ubiquitous in soil and as a pathogenic/spoilage fungus, causing Rhizopus rot and mucomycoses.</p> <p>Results</p> <p>Carbohydrate Active enzyme (CAZy) annotation of the <it>R. oryzae </it>identified, in contrast to other filamentous fungi, a low number of glycoside hydrolases (GHs) and a high number of glycosyl transferases (GTs) and carbohydrate esterases (CEs). A detailed analysis of CAZy families, supported by growth data, demonstrates highly specialized plant and fungal cell wall degrading abilities distinct from ascomycetes and basidiomycetes. The specific genomic and growth features for degradation of easily digestible plant cell wall mono- and polysaccharides (starch, galactomannan, unbranched pectin, hexose sugars), chitin, chitosan, β-1,3-glucan and fungal cell wall fractions suggest specific adaptations of <it>R. oryzae </it>to its environment.</p> <p>Conclusions</p> <p>CAZy analyses of the genome of the zygomycete fungus <it>R. oryzae </it>and comparison to ascomycetes and basidiomycete species revealed how evolution has shaped its genetic content with respect to carbohydrate degradation, after divergence from the Ascomycota and Basidiomycota.</p