A retrospective study on 195 horses with contaminated and infected synovial cavities

This study analyzes the clinical aspects of contaminated and infected synovial cavities in horses and evaluates their prognosis after treatment. The medical records of 195 affected horses referred between June 1999 and July 2004 were reviewed. Twenty-six horses were euthanized or returned home without further treatment. Therapeutic strategies for the remaining 169 horses were not different from those reported in other recent studies, except that lavage was performed predominantly without endoscopic visualization. Follow-up was obtained by questionnaire for 150 of 169 treated horses. The outcome was considered successful (survival without residual lameness) in 109 of 150 horses (72.7%). Iatrogenic synovial infection, the presence of radiographic signs on admission and the use of regional antibiotic perfusion were significantly related with non-successful outcome. Overall, the outcome in the present study appeared to be slightly less favorable compared to other recent reports, although it certainly improved for horses with deep nail puncture wounds

Application of a mechanistic UV/hydrogen peroxide model at full-scale : sensitivity analysis, calibration and performance evaluation

Numerous mechanistic models describing the UV/H2O2 process have been proposed in literature. In this study, one of them was used to predict the behavior of a full-scale reactor. The model was calibrated and validated with non-synthetic influent using different operational conditions. A local sensitivity analysis was conducted to determine the most important operational and chemical model parameters. Based on the latter, the incident UV irradiation intensity and two kinetic rate constants were selected for mathematical estimation. Hydrogen peroxide concentration, the decadic absorption coefficient at 310 nm (UVA310, as a surrogate for natural organic matter) and pH could be satisfactorily predicted during model validation using an independent data set. It was demonstrated that quick real-time calibration is an option at less controllable full-scale conditions. Parameters that determine the initiation step, i.e. photolysis of hydrogen peroxide, have a large impact on most of the variables. Some reaction rate constants were also of importance, but nine kinetic constants did show absolutely no influence to one of the variables. Parameters related to UV shielding by NOM were of main importance. Hydrogen peroxide concentration was classified as a non-sensitive variable, in contrast to the concentration of a micro pollutant which showed to be very to extremely influential to many of the parameters. UV absorption as a NOM surrogate is a promising variable to be included in future models. Model extension by splitting up the UVA310 into a soluble and a particulate fraction seemed to be a good approach to model AOP treatment of real (waste)waters containing both dissolved and particulate (suspended) material

Facteurs limitant et améliorant la détection d'ADN environnemental dans les sédiments marins

RÉSUMÉ : L'ADN environnemental (ADNe) est un domaine émergent dont les approches se développent pour répondre à des besoins en termes de programmes de surveillance et de gestion environnementale. Alors que de plus en plus de lignes directrices concernant l'utilisation et la standardisation des méthodes en ADNe sont développées, les facteurs influençant la détectabilité du matériel génétique dans l'environnement sont encore, à ce jour, peu étudiés. Le présent projet de recherche a pour objectif de caractériser l'effet de facteurs tels que la granulométrie des sédiments, la concentration d'acides humiques et d'ions métalliques (calcium, cuivre, fer, manganèse) sur la détectabilité de l'ADN dans les sédiments marins. Ce mémoire fait mention de l'effet de ces facteurs directement dans une matrice sédimentaire pour reproduire les conditions utilisées pour traiter un échantillon naturel alors que la majorité des inhibiteurs connus à ce jour ont été identifiés par leurs effets sur la réaction de polymérase en chaine (PCR). La matrice sédimentaire fut traitée chimiquement pour retirer les acides humiques, les acides fulviques, les ions métalliques labiles ainsi que les composés phénoliques. Ce faisant, une approche contrôlée a pu être utilisée pour évaluer individuellement l'influence des facteurs ciblés sur la détectabilité de l'ADN exogène ajouté en quantité connue dans la matrice. Les résultats ont permis d'identifier des facteurs qui limitent (calcium, fer et manganèse) ainsi que des facteurs qui améliorent (cuivre et acides humiques) la détectabilité de l'ADN dans les sédiments. Notamment, les résultats identifient pour la première fois l'effet limitant du manganèse et confirment que la présence dans l'environnement du calcium et du fer tend à réduire la détectabilité de l'ADNe alors que leur effet inhibiteur avait été identifié en PCR. L'acide éthylènediaminetétraacétique a été utilisé pour évaluer le potentiel d'un chélatant résultant en une amélioration de la détectabilité de l'ADN pouvant potentiellement appuyer l'hypothèse soulevée quant à l'effet de l'ajout d'acides humiques. Ces travaux de recherche clarifient de nouvelles limites pour l'interprétation des données et suggèrent des pistes pour améliorer la détection d'ADNe tout en présentant le besoin de plus de tests pour mieux comprendre l'ensemble des facteurs qui influencent la détectabilité de l'ADN dans l'environnement. -- Mot(s) clé(s) en français : ADNe, inhibiteurs, sédiments marins, ions métalliques, acides humiques, granulométrie, acide éthylènediaminetétraacétique (EDTA). -- ABSTRACT : Environmental DNA (eDNA) is an emerging field in which approaches are developing to answer needs in terms of monitoring and environmental management. While more and more guidelines concerning the use and standardization of eDNA methods are developed, the factors influencing the detectability of genetic material in the environment are still, to date, poorly studied. This research project aims to characterize the effect of factors such as sediment particle sizes, concentration of humic acids and metal ions (calcium, copper, iron, manganese) on DNA detectability in marine sediments. This thesis reports the effect of these factors directly in a sedimentary matrix to reproduce the conditions used to treat natural samples, whereas most inhibitors known to date have been identified by their effects on the polymerase chain reaction (PCR). The sedimentary matrix was chemically treated to remove humic acids, fulvic acids, labile metal ions and phenolic compounds. In doing so, a reductive approach was used to individually assess the influence of the targeted factors on the detectability of exogenous DNA added in a known amount in the matrix. The results made it possible to identify factors that limit (calcium, iron and manganese) as well as factors that improve (copper and humic acids) the DNA detectability in sediments. Moreover, the results identify for the first time the limiting effect of manganese and confirm that the presence in the environment of calcium and iron tends to reduce the detectability of eDNA whereas their inhibitory effect had been identified in PCR. Ethylenediaminetetraacetic acid was used to evaluate the potential of a chelating agent resulting in an improvement in DNA detectability which could potentially support the hypothesis raised as to the effect of the addition of humic acids. This research clarifies new limitations for data interpretation and suggests ways to improve eDNA detection while presenting the need for more tests to better understand all the factors that influence DNA detectability. -- Mot(s) clé(s) en anglais : eDNA, marine sediments, metal ions, humic acids, granulometry, ethylenediaminetetraacetic acid (EDTA)

Full-scale modelling of an ozone reactor for drinking water treatment

In 2003, the Flemish Water Supply Company (VMW) extended its drinking water production site in Kluizen (near Ghent, Belgium) with a combined ozonation and biological granular activated carbon (BGAC) filtration process. Due to this upgrade, biostability increased, less chlorination was needed and drinking water quality improved significantly. The aim of this study was to describe the full-scale reactor with a limited set of equations. In order to describe the ozonation process, a model including key processes such as ozone decomposition, organic carbon removal, disinfection and bromate formation was developed. Kinetics were implemented in WEST® and simulation results were compared to real data. The predicting performance was verified with a goodness-of-fit test and key parameters were determined through a local sensitivity analysis. Parameters involving optical density (both rate constants and stoichiometric coefficients) strongly affect model output. Some parameters with respect to bromate and bacteria showed to be only, but to a large extent, sensitive to their associated concentrations. A scenario analysis was performed to study the system’s behavior at different operational conditions. It was demonstrated that the model is able to describe the operation of the full-scale ozone reactor, however, further data collection for model validation is necessary

Zuid-West-Vlaanderen Energieneutraal in 2050: naar een regionale energiestrategie

Dit cahier bevat een voorstel voor een regionale energiestrategie voor Zuid-West-Vlaanderen: Zuid-West-Vlaanderen energieneutraal in 2050. Het biedt een denkkader over hoe Zuid-West-Vlaanderen de komende decennia met energie moet omgaan. Het cahier formuleert een visie, plus een aantal concrete acties om de visie op korte termijn in de praktijk te brengen. Het is de neerslag van een uitgebreid proces dat Leiedal opstartte, in samenwerking met de regionale energiestuurgroep en thematisch verdiept aan de hand van verschillende expertenworkshops en regionale energiefora

Gas chromatographic method for the determination of lumefantrine in antimalarial finished pharmaceutical products

A simple method has been developed and validated for quantitative determination of lumefantrine in antimalarial finished pharmaceutical products using gas chromatography coupled to flame ionization detector. Lumefantrine was silylated with N,O–bis(trimethyl-silyl)trifluoro-acetamide at 70°C for 30 minutes, and chromatographic separation was conducted on a fused silica capillary (HP-5, 30 m length × 0.32 mm i.d., 0.25 μm film thickness) column. Evaluation of the method within analytical quality-by-design principles, including a central composite face-centered design for the sample derivatization process and Plackett–Burman robustness verification of the chromatographic conditions, indicated that the method has acceptable specificity toward excipients and degradants, accuracy [mean recovery = 99.5%, relative standard deviation (RSD) = 1.0%], linearity (=0.9986), precision (intraday = 96.1% of the label claim, RSD = 0.9%; interday = 96.3% label claim, RSD = 0.9%), and high sensitivity with detection limits of 0.01 μg/mL. The developed method was successfully applied to analyze the lumefantrine content of marketed fixed-dose combination antimalarial finished pharmaceutical products

Modelling and simulation of a nitrification biofilter for drinking water purification

For the purification of pure and microbiologically safe drinking water, different treatment steps are necessary. One of those steps is the removal of ammonium, which can, e. g. be accomplished through nitrification in a biofilter. In this study, a model for such a nitrifying biofilter was developed and the model was consequentially used for scenario analysis. A protocol developed for characterisation of wastewater was used to characterise the biofilter influent. A comparison between measured and simulated effluent ammonium, nitrate and oxygen concentrations revealed that the predicting qualities of the constructed model are excellent. As such, the model could be used for further scenario analysis based on model simulations. By simulating the behaviour of the biofilter, it was shown that its capacity to treat unexpected ammonium peaks in the summer time is very limited. Further simulations with the model showed that extensive aeration is not essential for nitrification as sufficiently dissolved oxygen is present in the influent. Therefore the aeration can be reduced to such a level that mixing is ensured. A final set of simulations showed that prolonged ammonium loads can be dealt with by reducing the influent flow rate. The amount of reduction depends of the operating temperature and influent ammonium concentration. The presented simulations can be used by the operators to reduce operating costs and as a decision tool in the case of high ammonium influent concentrations