72 research outputs found

    Ammonia regulations near nature areas in Denmark and the Netherlands compared

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    Farms that want to expand within 400 m from Natura 2000 areas, have extra costs compared to farms with no negative influence on nature areas. These extra costs are higher for farms in Denmark than in the Netherlands. For farms further away from Natura 2000 areas (2,000 m) it is the other way around: then farmers in the Netherlands are confronted with higher costs than in Denmar

    Self-organization of two anionic azo dyes in the presence of alkaline earth ions

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    Die vorliegende Arbeit erforscht die durch Erdalkaliionen induzierte binäre Aggregation zweier anionischer Azofarbstoffe in wässriger Lösung. Dazu bedient sich die Arbeit hauptsächlich der statischen und dynamischen Lichtstreuung sowie der Röntgenkleinwinkelstreuung. Daneben kommen UV/vis-Spektroskopie, Massenspektroskopie und Transmissionselektronenmikroskopie zum Einsatz.Forschungsschwerpunkte der Arbeit sind die zeitabhängige Entwicklung struktureller Parameter der wachsenden Farbstoffaggregate sowie die Interpretation des Aggregationsprozesses mittels passender kinetischer Modelle. Darüber hinaus werden Erkenntnisse zur Netzwerkbildung der Farbstoffaggregate und über die Zusammensetzung letzterer gewonnen.Die Farbstoffaggregation wird durch Vermischung einer Erdalkalisalzlösung mit einer Lösung der beiden Azofarbstoffe induziert. Unmittelbar nach der Vermischung der beiden Lösungen setzt eine sehr kurze (< 1s) Nukleierungsphase ein, durch die der Aggregationsprozess eingeleitet wird. Die hierbei gebildeten Nuklei wachsen danach durch schrittweises Anlagern immer weiterer Farbstoffbausteine zu faserförmigen Farbstoffaggregaten heran. Die Wachstumsrate ist stark abhängig von der Art und der Konzentration der Erdalkaliionen. Die entstehenden Aggregate enthalten die beiden Azofarbstoffe im stöchiometrischen Verhältnis von 1:1. Innerhalb der Aggregate werden die negativen Ladungen der Farbstoffmoleküle durch die positiven Ladungen der Erdalkaliionen ausgeglichen. Letztere weisen eine gleichförmige örtliche Verteilung entlang der faserförmigen Farbstoffaggregate auf.The present dissertation investigates the binary aggregation of two anionic azotic dyestuffs induced by alkaline earth ions in aqueous solution. The main experimental techniques used are static and dynamic light scattering and small angle x-ray scattering. UV/vis spectroscopy, transmission electron microscopy and mass spectroscopy are applied as complementary methods.Priority is given to a time-dependent quantification of structural parameters of the aggregates and to the interpretation of the aggregation process by means of suitable kinetic models. Besides, the composition of the formed aggregates is further investigated and information on their branching behaviour and their tendency to form networks is obtained.The dyestuff aggregation is induced by combining an alkaline earth solution with a solution containing the two azo dyes. Immediately after the two solutions are mixed, a very short (< 1s) nucleation phase sets in. The nuclei formed here continuously grow to fibre-like dyestuff aggregates by gradually adding further dyestuff building units. The rate of aggregation strongly depends on the type and the concentration of alkaline earth ions. Within full-grown aggregates, the two azo dyes adopt a stoichiometric ratio of 1:1 and the negative charges of the dyestuff molecules balance the positive charges of the alkaline earth ions. The spatial distribution of the latter along the fibre-like aggregates is homogeneous.Tag der Verteidigung: 26.09.2014Paderborn, Univ., Diss., 201

    Have female twisted-wing parasites (Insecta: Strepsiptera) evolved tolerance traits as response to traumatic penetration?

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    Traumatic insemination describes an unusual form of mating during which a male penetrates the body wall of its female partner to inject sperm. Females unable to prevent traumatic insemination have been predicted to develop either traits of tolerance or of resistance, both reducing the fitness costs associated with the male-inflicted injury. The evolution of tolerance traits has previously been suggested for the bed bug. Here we present data suggesting that tolerance traits also evolved in females of the twisted-wing parasite species Stylops ovinae\textit{Stylops ovinae} and Xenos vesparum\textit{Xenos vesparum}. Using micro-indentation experiments and confocal laser scanning microscopy, we found that females of both investigated species possess a uniform resilin-rich integument that is notably thicker at penetration sites than at control sites. As the thickened cuticle does not seem to hamper penetration by males, we hypothesise that thickening of the cuticle resulted in reduced penetration damage and loss of haemolymph and in improved wound sealing. To evaluate the evolutionary relevance of the Stylops\textit{Stylops}-specific paragenital organ and penis shape variation in the context of inter- and intraspecific competition, we conducted attraction and interspecific mating experiments, as well as a geometric-morphometric analysis of S ovinae\textit{S ovinae} and X vesparum\textit{X vesparum} penises. We found that S ovinae\textit{S ovinae} females indeed attract sympatrically distributed congeneric males. However, only conspecific males were able to mate. In contrast, we did not observe any heterospecific male attraction by Xenos\textit{Xenos} females. We therefore hypothesise that the paragenital organ in the genus Stylops\textit{Stylops} represents a prezygotic mating barrier that prevents heterospecific matings
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