Doping and temperature-dependent optical properties of oxygen-reduced BaTiO3-d

We report on optical properties of reduced BaTiO3-d at different doping levels including insulating and metallic samples. In all the samples, including metallic one, we observe structural phase transitions from the changes in the infrared-active phonon modes. Metallic ground state is confirmed by the Drude-type lowfrequency optical reflectance. Similar to SrTiO3-d we find that the midinfrared-absorption band in BaTiO3-d appears and grows with an increase in the oxygen-vacancy concentration. Upon decrease in temperature from 300 K, the midinfrared band shifts slightly to higher frequency and evolves into two bands: the existing band and a new and smaller band at lower frequency. The appearance of the new and smaller band seems to be correlated with the structural phase transitionsComment: 8 pages, 7 figure

Utilisation des poissons pour évaluer les effets biologiques des contaminants dans l’estuaire du Saint-Laurent et le fjord du Saguenay

Les organismes aquatiques de l’estuaire du Saint-Laurent (ESL) et du fjord du Saguenay (FS) sont exposés à des mélanges complexes de composés toxiques pouvant avoir un impact sur les populations, seuls ou en interaction avec d’autres facteurs environnementaux. L’objectif de cet article est de résumer l’information sur les effets biologiques des contaminants dans l’ESL et le FS obtenue à l’aide de poissons sentinelles. Trois études de cas démontrent la complémentarité de l’information obtenue avec différentes espèces. Les études sur l’anguille d’Amérique (Anguilla rostrata) montrent comment des poissons migrateurs peuvent être un vecteur important de contamination pour les prédateurs de haut niveau trophique de l’ESL. Des lésions prénéoplasiques au foie chez les anguilles en migration, probablement liées à une exposition aux hydrocarbures aromatiques polycycliques (HAP) sur leurs aires de croissance, sont un exemple d’effet à long terme de contaminants qui ne persistent pas dans les tissus des poissons. La présence d’adduits à l’ADN a été démontrée chez les poulamons atlantiques (Microgadus tomcod) résidents dans l’ESL et permet de comparer les niveaux d’exposition aux HAP génotoxiques entre l’ESL et d’autres estuaires de la côte Atlantique. Les études sur le poulamon ont aussi révélé une interaction entre leur période de jeûne hivernal et les produits organiques persistants (POP) menant à une augmentation transitoire des concentrations de POP dans le foie et à une dysfonction hépatique. Des échantillonnages sur le terrain, couplés à des expositions en cages in situ et à des expériences en laboratoire, ont permis de mettre évidence chez des plies canadiennes (Hipoglossoides platessoides) exposées à des sédiments contaminés de la baie des Anglais, des altérations immunitaires causant une augmentation de la susceptibilité aux maladies infectieuses. Les futures études devraient poursuivre le développement de biomarqueurs pour différents groupes de contaminants et les utiliser chez des espèces de poissons clés, à des stades sensibles de leur cycle de vie, en combinant différentes approches expérimentales multistresseurs à des études de surveillance sur le terrain.Aquatic organisms in the St. Lawrence Estuary (SLE) and the Saguenay Fjord (SF) are exposed to complex mixtures of toxic compounds which can have deleterious impacts on populations, alone or in combination with other environmental factors. The purpose of this paper is to summarize information about biological effects of contaminants in the SLE and SF obtained using sentinel fish species. Three case studies demonstrate the complementary nature of the information acquired using different sentinel species. Studies in American eel (Anguilla rostrata) show how migratory fish can be an important vector of contamination for high level predators in the SLE. Preneoplastic liver lesions in migrating eels, likely related to an exposure to polycyclic aromatic hydrocarbons (PAHs) in their growing areas, are an example of a long-term effect of contaminants which do not persist in fish tissues. DNA adducts were detected in resident SLE Atlantic tomcod (Microgadus tomcod) and can be used to compare the level of exposure to genotoxic PAHs between the SLE and other estuaries of the Atlantic coast. Studies in tomcod have also revealed an interaction between their winter fasting period and persistent organic compounds (POPs) leading to a transitory increase in concentrations of POPs in the liver and to hepatic dysfunction. Field samplings in association to in situ cage exposures and laboratory experiments have been used in American plaice (Hipoglossoides platessoides) exposed to contaminated sediments from Baie des Anglais, to demonstrate immune alterations causing increased susceptibility to infectious diseases. Future studies on biological effects of contaminants in fish in the SLE and SF should pursue the development of biomarkers for different groups of contaminants, and use them in key fish species, sampled at critical stages of their life cycle, in studies combining different multistressors experimental approaches to field monitoring

Mobilité des métaux et risque de contamination des eaux lors de la valorisation sylvicole des boues de station d'épuration municipales au Québec : une revue

La présence de métaux dans les boues municipales demeure l'obstacle majeure à leur valorisation comme fertilisant agricole ou forestier. L'utilisation des boues en milieu forestier diminue certes les risques de contamination de la chaîne alimentaire humaine. Cependant, nos connaissances sur le comportement à long terme des métaux ajoutés aux sols forestiers sont encore très limitées. Le risque de lessivage des métaux vers les écosystèmes aquatiques situés en aval des zones traitées doit être évalué. Cet article propose une comparaison des risques de contamination de l'eau selon que l'application des boues s'effectue en forêt ou en milieu agricole. Les concentrations de métaux dans les boues municipales, leurs formes et leur mobilité dans les sols amendés sont passées en revue. Et finalement, les normes québécoises qui ont été établies pour protéger le milieu récepteur contre les métaux présents dans les boues sont comparées à celles recommandées par l'U.S. EPA.The presence of metals in municipal sewage sludge is still a major obstacle to their land application. Forest land application of sludge reduces the possibility of metals entering the human food chain. Present knowledge of their long-term behavior in forest soil is however limited. The risk of metals leaching to the aquatic ecosystem situated downstream from treated zone must be evaluated. This paper present a comparison of the risks of water contamination when sludges are applied to forests instead of cropland. The levels of metals in municipal sludge, their form and their mobility in sludge-treated soil are reviewed. Finally, the regulations of the Province of Quebec that have been established to protect forest land are compared to the recommendations of the U.S. Environmental Protection Agency. Although sludge applications to forest land reduce the risk of human foodchain contamination, properties of forest soils (low pH, low cation exchange capacity (CEC), presence of large continuous pores) could represent an increased hazard of metals leaching to aquatic ecosystems. Metal concentrations in sludge vary considerably depending on the source of the sludge. Metals found in sludge are predominantly associated with the solid phase, while soluble and exchangeable forms generally represent less than 10% of the total metals.Short term studies have revealed that metals tend to accumulate in the upper layers of soil, but few studies have evaluated long-term metal mobility or bioavailability. Many factors can contribute to an increase mobility (pH, oxidation-reduction potential, organic matter decomposition). The risk of aquatic ecosystem contamination by aluminum leached from sludge-treated soils hasn't yet been evaluated. It seems, however, that the risk exists if the soil become more acidic after sludge decomposition. Limits on the amount of metals allowed in sludge have been fixed by many countries. Nevertheless, given the wide variation in the standards used to regulate the allowable content of metal in sludge or sludge-treated soils, disagreement presently exist among regulatory agencies. For example, the maximum cadmium limit allowed in sludge destined to be used as forest fertilizer in Quebec is 15 mg kg-1, whereas it is 85 mg kg-1 in the United States. Different philosophical views on environmental protection (zero tolerance or tolerance of a certain level of metals in soil), as well as the organism chosen when standards are set, are responsible for this inconsistency. Before sewage sludge application to forests becomes a common practice, the associated risks of metals leaching to the aquatic ecosystem must be evaluated. Long-term studies should be undertaken in order to establish safe standards for applying sludge in a forest environment. Such additional efforts will enable good quality sludge to be considered as a usable and valuable resource in forestry

Étude de l'enlèvement du Cd, Cu, Mn et Zn par solubilisation biologique dans les sédiments lacustres fortement contaminés

Des essais en erlenmeyers de 0,5 L ont été faits afin d'évaluer les possibilités d'application d'un procédé de solubilisation biologique aux sédiments. Ce procédé utilise la capacité des thiobacilles de lixivier les métaux en milieu acide. Au cours des essais, l'influence, sur la solubilisation des métaux, de la quantité de substrat (FeSO4 × 7H2O), du pourcentage d'inoculum et de la teneur en solides totaux a été suivie. La concentration de substrat n'a pas d'effet sur l'enlèvement du Cd, du Zn, du Mn et du Cu. Les taux d'enlèvement moyens pour le Cd, Zn et Mn, sont, après 46 heures, de 70 à 90 %, 90 à 100 % et 64 à 72 % pour des concentrations de substrat variant de 0 à 30 % FeSO4 × 7H2O (poids sec/poids sec). A 29 et 46 heures, des coefficients de détermination (r2) de 0,46 et 0,59 entre le pH et la concentration de FeSO4 × 7H2O, et de 0,92 et 0,55 entre le POR et la concentration de FeSO4 × 7H2O ont été trouvés. A plus forte teneur en FeSO4 × 7H2O, le POR est moins élevé, surtout au début des essais. La présence des ions ferreux en plus grande quantité expliquerait les plus faibles valeurs du potentiel-rédox. A 20 % d'inoculum, la solubilisation des métaux est optimale avec une solubili- sation de 86 % pour le Cd et 73 % pour le Cu et le Mn. La forte corrélation entre le POR, le pH et le pourcentage d'inoculum (r2 à 29, 46 et 70 heures de 0,94, 0,94 et 0,63 pour le POR et le pourcentage d'inoculum et de 0,80, 0,69 et 0,60 pour le pH et le pourcentage d'inoculum), a permis d'établir une corrélation entre le POR, le pH et la solubilisation du Cu. Les seuils trouvés permettant une solubilisation du Cu supérieure à 10 % sont un pH de 3,75 et un POR de 260 mV.L'augmentation des solides totaux (ST) semble limiter le développement des thiobacilles et diminue les rendements de solubilisation du Cd (à 21 heures) et du Zn (à 45 heures). Ainsi, pour le Cd, les pourcentages de solubilisation passent de 71 % à 24 % pour 3 et 15 % ST, alors que dans le cas du Zn, ils diminuent de 94 % à 81 % pour 3 et 15 % ST. La solubilisation du Mn serait, pour sa part, plutôt de type chimique.In the province of Québec, the St-Lawrence Seaway as well as the harbour areas undergo frequent dredging. Each year, more than 106 cubic metres of sediments must be dredged from the st-Lawrence river. The dredged sedirnents are generally dispersed in the water column. However, heavy metal contamination of these sediments may preclude open-water disposal and necessitate their confinement.The research work presented in this article applies to dredged sediments that are too contaminated for open-water disposal. In order to permit their safe disposal, it is necessary to have a method which effectively removes metals from these sediments. One of the effective methods of metal removal from contaminated sediments could be a microbial solubilization process, which was developed at INRS-Eau for sewage sludge decontamination and which has been tested on a pilot scale during the past year. In order to appty such a process to decontaminate sediments, it was necessary to study the influence of various factors affecting the microbial leaching process. This research verified the possibility of using a modified microbial leaching process to decontaminate sediments and also studied the influence of the enerry substrate, the microbial inoculum and the sediment total solids concentration on such a modified process.The experimental methodology consisted of mixing the contaminated sediment in a 500 ml Erlenmeyer flask for a period of 96 hours in the presence of thiobacillus inoculum and ferrous sulfate (FeSO4 • 7H2O) as the enerry substrate. Before each experiment sediments were adjusted to the desired total solids concentration with deionized water and were acidified with sulfuric acid to obtain the starting pH conditions.The solubilization of Cd, Cu, Zn and Mn was monitored at regular intervals in order to evaluate the influence of the various factors studied. Subsamples were removed, the sediments were digested and the metals were analyzed by inductively coupled plasma atomic emission spectrophotometry (ICP-AES). The elements analyzed were Al, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb,Zn as well as S, P and C. All the digestions and analyses performed made according to the APHA guidelines. The total solids, both volatile and inert, were also determined according to APHA method no.209F (APHA, 1985).Regarding the influence of the ferrous sulfate concentration on the application of the microbial leaching process, the removal rates of Cd, Zn and Mn did not vary more than 12 %. For all experiments, the final pH value approached 2,5. The oxidation-reduction potential (ORP) varied for all experiments from 462 to 560 mV. An energy source could therefore be present in the sediments, which would support the growth of thiobacillus bacteria.During the experiments conducted to study the influence of inoculum concentration on the microbial leaching process, it was found that the pH decreased from 3.5 to 2.4 and the ORP increased from 284 to 593 mV when the inoculum addition increased from 0 to 30 % (v/v). This tendency was also observed during the removal of Cd and above all, Cu. Between 0 and 20 % (v/v) inoculum concentration, Cd removal increased from 64 to 86 % whereas Cu removal increased from 20 to73 %. However, these two metals did not show any appreciable increase in solubilization when the inoculum was increased from 20 to 30 % (v/v). In the case of Mn, it was not possible to determine the solubilization pattern since the inoculum concentration did not influence the solubilization of this element, Between 0 and 30 % inoculum, the Mn removal varied from 56 to 73 %. Hence the microbial influence on Mn solubilization may be negligible.The study on the influence of total solids content on the microbial leaching process showed that the total solids concentration had an influence on pH and ORP. The final pH increased from 2.43 to 3.32 and ORP decreasedfrom 492 to 321 mV when the total solids content was varied from 3 to 15 % . The percent solubilization of Cd after 21 h was 7l %, 69 %, 43 %, 44 % and, 24 % at 3, 5, 7, 10 and 15 % total solids respectively, On the other hand, Zn solubilization after 45 h was 94 %, 90 %, 84 %, 97 % and 8l % for the same concentrations of total solids. An increase in total solids content decreased the solubilization efficiency of Cd (at t=2l h) and, to a lesser extent, Zn (att=48h). However,in the case of Mn, the maximum solubilization was achieved right at the beginning and varied little with time. Its solubilization varied between 61 and 70 % for 3 % total solids, between 67 and, 79 % for 5 % total dolids, between 52 and,62 % for 7 % totaf solids, between 57 and, 75 % for l0 % total solids and tretween 40 and 63 % for 15 % total solids. In general, for the sediments studied here, total solids content has little influence on Mn solubilization.In conclusion, use of a microbial leaching process to remove metals from contaminated sediments seems to be less complex than for sewage sludges, since the maximum removal of metals is achieved in less than 48 h in a bench-scale experiment. The average metal solubilization was above 80 % for Cd, 73 % for Cu, 90 % for Zn and 65 % for Mn. The development of thiobacillus does not seem to be dependent upon the presence of an added energy substrate. Only a minimal quantity of substrate, say 5 % ferrous sulfate (dry wt./dry wt.), is required in order to assure optimal conditions for thiobacillus growth. It is probable that with time, without ferrous sulfate, the microbial conditions would deteriorate due to exhaustion ofthe enerry substrate. A 20 % microbial inoculum seems to be enough to assure an efficient metal solubilization process. Except for Mn, the increase in total solids concentration had a negative influence on the metal solubilization. It is hence preferable to work with a total solids concentration of less than 5 %. Nevertheless, it should be noted that this percentage is more than that used for sewage sludge decontaminaton (around 2 % total solids)

Enacting The Spirit Of The United Nations Convention On The Rights Of Persons With Disabilities: The Role Of Postsecondary Faculty In Ensuring Access

Nations throughout the world have signed the United Nations (UN) Convention on the Rights of Persons With Disabilities.  Many postsecondary educators support the ideals of access and equity for students with disabilities, but have received no training in how to ensure that these goals are achieved.  This paper introduces the concepts of universal design and universal instructional design and provides specific guidelines for general communication and for creating accessible classrooms, lectures or presentations, documents, media, websites, and distance education courses

Reply to Lipworth et al.

We thank Dr. Lipworth and colleagues for their interest in our work published recently in the Journal (1). They rightly point out that the biology of asthma attacks is more complex than blood eosinophils alone and that corticosteroids have a wide range of other potentially relevant antiinflammatory effects. However, local treatment with inhaled corticosteroids (ICS) is usually the mainstay of patients with frequent eosinophilic exacerbations, and therefore in the great majority of patients, the key question is what oral corticosteroids (OCS) add to ICS in an acute attack (2) and whether this effect is seen with benralizumab. We suggest that depletion of circulating eosinophils is the only effect OCS are likely to have that are not shared with ICS (3)

Characterization of human metapneumoviruses isolated from patients in North America.

Human metapneumovirus (HMPV) was recently identified in The Netherlands and was linked to acute respiratory tract illness. In this study, 11 isolates from 10 patients with respiratory disease from Quebec, Canada, were tested by a reverse-transcriptase polymerase chain reaction based on the fusion protein gene. Identified sequences were consistent with HMPV. The patients were 2 months to 87 years of age (median age, 58 years) and presented with acute respiratory tract illness during the winter season. Sequence studies of the nucleocapsid, fusion, and polymerase genes identified 2 main lineages of HMPV and cocirculation of both lineages during the same year. These findings support a previous finding that HMPV is a human respiratory pathogen that merits further study

Optimal Fleet Composition via Dynamic Programming and Golden Section Search

In this paper, we consider an optimization problem arising in vehicle fleet management. The problem is to construct a heterogeneous vehicle fleet in such a way that cost is minimized subject to a constraint on the overall fleet size. The cost function incorporates fixed and variable costs associated with the fleet, as well as hiring costs that are incurred when vehicle requirements exceed fleet capacity. We first consider the simple case when there is only one type of vehicle. We show that in this case the cost function is convex, and thus the problem can be solved efficiently using the well-known golden section method. We then devise an algorithm, based on dynamic programming and the golden section method, for solving the general problem in which there are multiple vehicle types. We conclude the paper with some simulation results

Changes in synaptic transmission and protein expression in the brains of adult offspring after prenatal inhibition of the kynurenine pathway

During early brain development, N-methyl-d-aspartate (NMDA) receptors are involved in cell migration, neuritogenesis, axon guidance and synapse formation, but the mechanisms which regulate NMDA receptor density and function remain unclear. The kynurenine pathway of tryptophan metabolism includes an agonist (quinolinic acid) and an antagonist (kynurenic acid) at NMDA receptors and we have previously shown that inhibition of the pathway using the kynurenine-3-monoxygenase inhibitor Ro61-8048 in late gestation produces rapid changes in protein expression in the embryos and effects on synaptic transmission lasting until postnatal day 21 (P21). The present study sought to determine whether any of these effects are maintained into adulthood. After prenatal injections of Ro61-8048 the litter was allowed to develop to P60 when some offspring were euthanized and the brains removed for examination. Analysis of protein expression by Western blotting revealed significantly reduced expression of the GluN2A subunit (32%) and the morphogenetic protein sonic hedgehog (31%), with a 29% increase in the expression of doublecortin, a protein associated with neurogenesis. No changes were seen in mRNA abundance using quantitative real-time polymerase chain reaction. Neuronal excitability was normal in the CA1 region of hippocampal slices but paired-pulse stimulation revealed less inhibition at short interpulse intervals. The amount of long-term potentiation was decreased by 49% in treated pups and recovery after low-frequency stimulation was delayed. The results not only strengthen the view that basal, constitutive kynurenine metabolism is involved in normal brain development, but also show that changes induced prenatally can affect the brains of adult offspring and those changes are quite different from those seen previously at weaning (P21). Those changes may be mediated by altered expression of NMDAR subunits and sonic hedgehog