Propagation,deposition, and suspension characteristics of constant-volume particle-driven gravity currents

Environmental Fluid Mechanics - In this laboratory study, propagation behaviour, particle deposition patterns, and suspension characteristics of non-cohesive particle-driven gravity currents formed...     

High efficiency chlorine removal from polyvinyl chloride (PVC) pyrolysis with a gas–liquid fluidized bed reactor

In this research a gas–liquid fluidized bed reactor was developed for removing chlorine (Cl) from polyvinyl chloride (PVC) to favor its pyrolysis treatment. In order to efficiently remove Cl within a limited time before extensive generation of hydrocarbon products, the gas–liquid fluidized bed reactor was running at 280–320 °C, where hot N₂ was used as fluidizing gas to fluidize the molten polymer, letting the molten polymer contact well with N₂ to release Cl in form of HCl. Experimental results showed that dechlorination efficiency is mainly temperature dependent and 300 °C is a proper reaction temperature for efficient dechlorination within a limited time duration and for prevention of extensive pyrolysis; under this temperature 99.5% of Cl removal efficiency can be obtained within reaction time around 1 min after melting is completed as the flow rate of N₂ gas was set around 0.47–0.85 Nm³ kg^?1 for the molten PVC. Larger N₂ flow rate and additives in PVC would enhance HCl release but did not change the final dechlorination efficiency; and excessive N₂ flow rate should be avoided for prevention of polymer entrainment. HCl is emitted from PVC granules or scraps at the mean time they started to melt and the melting stage should be taken into consideration when design the gas–liquid fluidized bed reactor for dechlorination.     

Identification of 1-methyloctyl butanoate as the major sex pheromone component from females of the saddle gall midge,Haplodiplosis marginata (Diptera: Cecidomyiidae)

The saddle gall midge, Haplodiplosis marginata (von Roser) (Diptera: Cecidomyiidae), has undergone a resurgence recently as a pest of cereals in Belgium and other European countries. An effective monitoring tool of saddle gall midge flights is needed to understand the enigmatic population dynamics of this pest, and to design an integrated management strategy. Therefore, volatile compounds emitted by females (alkan-2-ols and alk-2-yl butanoates) were identified, and the chirality of the emitted esters was determined to be the R absolute configuration. In field-trapping experiments, racemic non-2-yl butanoate attracted substantial numbers of H. marginata males. Thus, this compound will be useful in baited traps for monitoring seasonal flight patterns, and improving integrated management of the saddle gall midge in agricultural systems.     

Characterization of microbial consortia that reductively dechlorinate 4-chlorophenol and transform phenol to benzoate enriched from estuarine sediment of Lake Shinji

Monochlorophenols were degraded to benzoate via phenol by the initial dechlorination and the subsequent conversion of phenol to benzoate in anaerobic sediment samples of estuarine Lake Shinji under methanogenic conditions. To characterize bacteria that dechlorinate 4-chlorophenol and transform phenol to benzoate, we analyzed the microbial community structure of the enrichment culture with each 4-chlorophenol and phenol by the limiting dilution method with polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) of 16S rRNA gene. After serial dilution of the culture, the 4-chlorophenol-dechlorinating culture consisted of two dominant bacteria, one of which was most homologous with Dehalobacter sp. In the enriched culture with phenol, minor band homologous with Cryptanaerobacter phenolicass corresponded to the transformation activity.     

Old endemics and new invaders: alternative strategies of passerines for living in the Australian environment

Life history parameters of ”old endemics” and ”new invaders” among the Australian passerines were compared, controlling for phylogeny by using current, phylogenetic research methods. Old endemics were found to have significantly smaller clutches and demonstrated significantly more cooperative breeding than the new invaders, whose fledging periods are significantly longer than those of the old endemics. We argue that breeding under conditions of a small annual food increment during the breeding season, as is probably the situtation in Australia, is possible only when clutch size is small, or while breeding cooperatively, or by extending the fledging period. Our data show that the old endemics use the first two options, while the new invaders employ the third. Received: 10 February 1999 / Received in revised form: 10 November 1999 / Accepted: 20 November 1999     

Screening differentially expressed genes in an amphipod (Hyalella azteca) exposed to fungicide vinclozolin by suppression subtractive hybridization

Vinclozolin, a dicarboximide fungicide, is an endocrine disrupting chemical that competes with an androgenic endocrine disruptor compound. Most research has focused on the epigenetic effect of vinclozolin in humans. In terms of ecotoxicology, understanding the effect of vinclozolin on non-target organisms is important. The expression profile of a comprehensive set of genes in the amphipod Hyalella azteca exposed to vinclozolin was examined. The expressed sequence tags in low-dose vinclozolin-treated and -untreated amphipods were isolated and identified by suppression subtractive hybridization. DNA dot blotting was used to confirm the results and establish a subtracted cDNA library for comparing all differentially expressed sequences with and without vinclozolin treatment. In total, 494 differentially expressed genes, including hemocyanin, heatshock protein, cytochrome, cytochrome oxidase and NADH dehydrogenase were detected. Hemocyanin was the most abundant gene. DNA dot blotting revealed 55 genes with significant differential expression. These genes included larval serum protein 1 alpha, E3 ubiquitin-protein ligase, mitochondrial cytochrome c oxidase, mitochondrial protein, proteasome inhibitor, hemocyanin, zinc-finger–containing protein, mitochondrial NADH-ubiquinone oxidoreductase and epididymal sperm-binding protein. Vinclozolin appears to upregulate stress-related genes and hemocyanin, related to immunity. Moreover, vinclozolin downregulated NADH dehydrogenase, related to respiration. Thus, even a non-lethal concentration of vinclozolin still has an effect at the genetic level in H. azteca and presents a potential risk, especially as it would affect non-target organism hormone metabolism.