43 resultados para Foul


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Mode of access: Internet.

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Mode of access: Internet.

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Cover title.

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The clash between German Social Democracy--the party, intellectuals and workers--and the German Imperial State was played out in the Freie Volksbahne (Free People's Theatre) founded by intellectuals to energise working class political awareness of drama with a political and social cutting edge. It fell foul of state censorship, lost its bite, yet prospered.

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Résumé Les oxylipines, telles que l'acide jasmonique (AJ ou jasmonate), jouent un rôle central en réponse à la blessure et à la pathogenèse. De nombreuses études ont montré l'importance de la voie canonique du jasmonate lors de la défense des plantes. De plus, un précurseur cyclopentenone de l'AJ, l'acide oxo-phyto-dienoic (OPDA), a été impliqué comme jouant le rôle d'une molécule signal lors de la défense contre certains pathogènes. En utilisant des mutants bloqués dans la biosynthèse de l'acide jasmonique (aos) ou dans sa perception (coi1-1), nous avons cherché à définir dans quelle mesure l'OPDA joue un rôle de signal induisant l'expression génétique en réponse à la blessure chez Arabidopsis. A l'aide de puces à ADN (microarray), nous avons montré que les transcriptomes d'aos et de coi1-1 sont très semblables après blessure, ce qui suggère que les produits d'AOS sont tous perçus via COI1. Pourtant, lorsqu'on analyse les métabolites présents chez ces mutants, une différence est visible, puisque aos n'accumule pas d'AJ, alors que coi1-1 en accumule encore rapidement après blessure. Nous avons étudié la possibilité qu'un mécanisme de régulation post-traductionnelle sur la voie de biosynthèse du jasmonate explique l'accumulation d'AJ chez coi1-1 après blessure. La lipoxygenase 2 (LOX2) est la première enzyme impliquée dans la biosynthèse de l'AJ et est donc une cible potentielle d'un tel mécanisme. Un indice sur la manière dont l'activité LOX pourrait être régulée vient du mutant fou2 (pour fatty acid oxygenation upregcilated 2) dans lequel l'activité LOX ainsi que le niveau d'AJ sont constitutivement élevés. Cette mutation implique un flux de cation dans la régulation de la production de l'AJ. De plus, il a été montré que plusieurs LOXs, dans des organismes autres que des plantes, peuvent lier le calcium. Nous montrons que l'activité LOX requiert l'addition de cations divalents pour être maximale in vitro, et que non seulement le calcium mais aussi le magnésium joue ce rôle. De plus, nous caractérisons un mutant récessif de LOX2 chez Arabidopsis (lox2-1). Ces plantes sont fertiles, et une analyse quantitative montre qu'elles accumulent toujours un peu d'AJ après blessure. Ceci suggère que LOX2 n'est pas la seule LOX impliquée dans la synthèse d'AJ. Aussi les plantes lox2-1 ne sont pas plus sensibles que les plantes de type sauvage lorsqu'elles sont infectées par la moisissure Botrytis cinerea ou lorsqu'elles sont exposées à un détritivore, néanmoins elles sont plus sensibles lorsqu'elles sont offertes en nourriture à un insecte herbivore. Les insectes et les plantes ont co-évolué conjointement, ainsi une plante ne contenant qu'un niveau réduit d'AJ favorise l'insecte. La disponibilité d'un mutant avec un niveau intermédiaire d'AJ va permettre de mieux comprendre pourquoi les plantes produisent autant de jasmonate. Abstract Oxylipins such as jasmonic acid (JA) play central roles in the wound response and during pathogenesis and many studies have confirmed the important role of the canonical jasmonate pathway in plant defense. Moreover, the cyclopentenone precursor of JA, oxo-phytodienoic acid (OPDA), is also thought to function as a signaling molecule in defense towards some pathogens. Its action was reported to depend on a different signal pathway to JA. By using mutants blocked in the biosynthesis (aos) or perception (coil-1) of JA, we investigated to which extend OPDA works as signaling molecule to trigger gene expression in the wound response of Arabidopsis. Using microarrays, we showed that aos and coil-1 transcriptome are similar in response to wounding, suggesting that products of AOS are all perceived by COI1. However, we found a difference between the two mutants at the metobolomic level, since aos is devoid of JA, but coil-1 can still rapidly accumulate JA upon wounding. We investigated the possibility that the post-translational activation of JA biosynthesis could explain the fast accumulation of JA in coil-1 plants upon wounding. Lipoxygenase (LOX) 2 is the first enzyme implicated in JA synthesis and was thus chosen as a potential target for posttranslational regulation. A clue as to how LOX activity might be regulated came from the fatty acid oxygenation upregulated 2 (foul) mutant in which LOX activity and JA levels are elevated. The foul mutant implicates cations flux in the regulation of JA production, and several LOXs in organisms other than plants have been shown to bind calcium. We showed that Arabidopsis LOX requires divalent cations for full activity in vitro, and that not only calcium but also magnesium can play this role. Moreover, a single recessive mutant of AtLOX2 was characterized. These plants are fully fertile. Quantitative oxylipin analysis showed that lox2-1 can still accumulate some JA after wounding, which suggests that LOX2 is not the only LOX involved in JA biosynthesis. lox2-1 plants do not show altered susceptibility to the fungus Botrytis cinerea or to a detritivore, however, they are more susceptible to an insect herbivore. The insect and plants are closely co-evolved and a reduced ability to synthesize JA favors the insect. The availability of a lox2-1 mutant with intermediate JA levels will further help understanding why plants produce elevated JA levels.

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In this thesis different parameters influencing critical flux in protein ultrafiltration and membrane foul-ing were studied. Short reviews of proteins, cross-flow ultrafiltration, flux decline and criticalflux and the basic theory of Partial Least Square analysis (PLS) are given at the beginning. The experiments were mainly performed using dilute solutions of globular proteins, commercial polymeric membranes and laboratory scale apparatuses. Fouling was studied by flux, streaming potential and FTIR-ATR measurements. Critical flux was evaluated by different kinds of stepwise procedures and by both con-stant pressure and constant flux methods. The critical flux was affected by transmembrane pressure, flow velocity, protein concentration, mem-brane hydrophobicity and protein and membrane charges. Generally, the lowest critical fluxes were obtained at the isoelectric points of the protein and the highest in the presence of electrostatic repulsion between the membrane surface and the protein molecules. In the laminar flow regime the critical flux increased with flow velocity, but not any more above this region. An increase in concentration de-creased the critical flux. Hydrophobic membranes showed fouling in all charge conditionsand, furthermore, especially at the beginning of the experiment even at very low transmembrane pressures. Fouling of these membranes was thought to be due to protein adsorption by hydrophobic interactions. The hydrophilic membranes used suffered more from reversible fouling and concentration polarisation than from irreversible foul-ing. They became fouled at higher transmembrane pressures becauseof pore blocking. In this thesis some new aspects on critical flux are presented that are important for ultrafiltration and fractionation of proteins.

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Dioxins and furans, PCDD/Fs, are highly toxic substances formed in post combustion zones in furnaces. PCDD/F emissions are regulated by a waste incineration directive which relates also to co-incineration plants. Several observations of dioxin and furan enhancements in wet scrub- bers have been reported previously. This is thought to be due to the so-called "memory effect" which occurs when dioxins and furans absorb into plastic material in scrubbers and desorb when ambient circumstances alter significantly. At the co-incineration plant involved, dioxins and furans are controlled with a wet scrubber, the tower packing of which is made of plastic in which activated carbon particles are dispersed. This should avoid the memory effect and act as a dioxin and furan sink since dioxins and furans are absorbed irreversibly into the packing ma- terial. In this case, the tower packing in the scrubber is covered with a white layer that has been found to be mainly aluminium. The aim of this thesis was to determine the aluminium balance and the dioxin and furan behaviour in the scrubber and, thus, the impacts that the foul- ing has on dioxin and furan removal. The source of aluminium, reasons for fouling and further actions to minimize its impacts on dioxin and furan removal were also to be discovered. Measurements in various media around the scrubber and in fuels were made and a profile analysis of PCDD/F and mass balance calculations were carried out. PCDD/F content de- creased in the scrubber. The reduced PCDD/F was not discharged into scrubbing water. The removal mechanism seems to work in spite of the fouling, at least with low PCDD/F loads. Most of the PCDD/F in excess water originates from the Kymijoki River which is used as feeding water in the scrubber. Fouling turned out to consist mainly of aluminium hydroxides. Sludge combusted in the furnace was found to be a significant source of aluminium. Ways to minimize the fouling would be adjustment of pH to a proper lever, installation of a mechanical filter to catch the loose material from the scrubbing water and affecting the aluminium content of the sludge.

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The search for new renewable materials has intensified in recent years. Pulp and paper mill process streams contain a number of potential compounds which could be used in biofuel production and as raw materials in the chemical, food and pharmaceutical industries. Prior to utilization, these compounds require separation from other compounds present in the process stream. One feasible separation technique is membrane filtration but to some extent, fouling still limits its implementation in pulp and paper mill applications. To mitigate fouling and its effects, foulants and their fouling mechanisms need to be well understood. This thesis evaluates fouling in filtration of pulp and paper mill process streams by means of polysaccharide model substance filtrations and by development of a procedure to analyze and identify potential foulants, i.e. wood extractives and carbohydrates, from fouled membranes. The model solution filtration results demonstrate that each polysaccharide has its own fouling mechanism, which also depends on the membrane characteristics. Polysaccharides may foul the membranes by adsorption and/or by gel/cake layer formation on the membrane surface. Moreover, the polysaccharides interact, which makes fouling evaluation of certain compound groups very challenging. Novel methods to identify wood extractive and polysaccharide foulants are developed in this thesis. The results show that it is possible to extract and identify wood extractives from membranes fouled in filtration of pulp and paper millstreams. The most effective solvent was found to be acetone:water (9:1 v/v) because it extracted both lipophilic extractives and lignans at high amounts from the fouled membranes and it was also non-destructive for the membrane materials. One hour of extraction was enough to extract wood extractives at high amounts for membrane samples with an area of 0.008 m2. If only qualitative knowledge of wood extractives is needed a simplified extraction procedure can be used. Adsorption was the main fouling mechanism in extractives-induced fouling and dissolved fatty and resin acids were mostly the reason for the fouling; colloidal fouling was negligible. Both process water and membrane characteristics affected extractives-induced fouling. In general, the more hydrophilic regenerated cellulose (RC) membrane fouled less that the more hydrophobic polyethersulfone (PES) and polyamide (PA) membranes independent of the process water used. Monosaccharide and uronic acid units could also be identified from the fouled synthetic polymeric membranes. It was impossible to analyze all monosaccharide units from the RC membrane because the analysis result obtained contained degraded membrane material. One of the fouling mechanisms of carbohydrates was adsorption. Carbohydrates were not potential adsorptive foulants to the sameextent as wood extractives because their amount in the fouled membranes was found to be significantly lower than the amount of wood extractives.

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Käänteisosmoosisuodatusta käytetään erityisesti teollisuuden jätevesien loppupuhdistuksessa. Suodatuksen ongelmana on kalvojen likaantuminen ja tukkiutuminen. Tässä työssä on aiempia tutkimuksia hyväksikäyttäen tutkittu käänteisosmoosiin tulevan veden esikäsittelemistä niin, että kalvojen likaantumiselta vältyttäisiin. Menetelmien vertailussa on käytetty erilaisia veden laadusta kertovia parametreja. Ongelmallisimmiksi aineksiksi huomattiin orgaaninen aines ja jotkin veteen liuenneet ionit. Kiintoaineen erottaminen ei ole ollut suuri ongelma, sillä sen saa poistettua tavallisesti käytetyillä rakeissuodatuksella, laskeutuksella, flotaatiolla ja kalvosuodatuksella. Orgaanista ainesta on saatu erotettua erityisesti hapettamalla, aktiivilieteprosessilla ja biologisella aktiivihiilisuodattimella. Mikro- ja ultrasuodatusta käytetään usein juuri ennen käänteisosmoosia poistamaan erityisesti kolloidista materiaalia ja joitain liuenneita ioneja. Flokkien muodostaminen koagulaatiossa ja flokkulaatiossa parantaa lähes kaikkien menetelmien toimivuutta selvästi. Veden puhdistuksessa käytetyt kemikaalit voivat myös liika-annosteltuina liata kalvoja. Vesien pitoisuuksissa eri ainesten osalta on huomattavia eroja, joten puhdistettava vesi on hyvä analysoida etukäteen parhaiden käsittelymenetelmien valitsemiseksi.

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The extensive backwaters of Kerala are the sites for a flourishing cottage industry - the coir industry. This enterprise almost exclusively located along the 590 km coastal belt of Kerala, provides direct employment to over half a million people in the state and produces nearly 90% of the total coir goods in the world. The shallow bays and lagoons of the 30 backwater systems of the state are traditional areas for the retting of coconut husk for the production of the coir fibre. The paper examines the environmental status of the retting grounds in Kerala, in relation to the biotic communities. The study revealed that retting activity has caused large scale organic pollution along with the mass destruction of the flora and fauna, converting sizeable sections of the backwaters into virtual cesspools of foul smelling stagnant waters. High values of hydrogen sulphide, ammonia, BOD5 associated with anoxic conditions and low community diversity of plankton, benthic fauna, fish, shell fish, wood boring and fouling organisms were the outstanding feature of the retting zones.