Development of matte finishes in electrostatic (EFB) and conventional hot dipping (CHDFB) fluidized bed coating process

This study focuses on the correlation between the thermo-rheological properties of a thermosetting powder coating system with its surface structure build-up. Epoxy powder coating systems, which displayed surface matting and surface wrinkling, were examined. Firstly, the evolution of the complex viscosity was correlated with the cure kinetic. Secondly, the structure build-up on the surface of the coatings was investigated with a combined SEM-CLA profilometry analysis at different stages of curing process for both EFB and CHDFB coating processes. Different finishes were found to characterize the films applied by using EFB and CHDFB coating processes as a result of the different way the film is heated by. Finally, a strict relationship of film morphology to the degree of conversion and to the evolution of the complex viscosity was found out for both EFB and CHDFB coating processes. The surface structure is built up after gelation point and continues to evolve after gelation with a full development of the film fine structure. Differences were observed in the surface structure build-up when different curing temperature was used, thereby indicating an influence of minimum viscosity on achievable finishing. These experimental results lead to further advances in a better understanding of the formation of surface topography and morphology of polymeric films. They also provide important indications for the settings of curing parameters in both EFB and CHDFB coating processes as well as for the development of new powder coating formulations. © 2007 Elsevier B.V. All rights reserved

Iowa State Teachers College Schedule of Classes, Summer 1953

A listing of the courses being taught as well as policies and procedures concerning attending classes at the Iowa State Teachers College.https://scholarworks.uni.edu/class_schedules/1213/thumbnail.jp

The age and structural setting of limestone and basalt on the main ring fault of south-east Rhum Inner Hebrides Scotland

In south-east Rhum a Mesozoic/Tertiary sequence is preserved as a fault bounded/rotated wedge. This is juxtaposed between Precambrian rocks (Torridonian sediments and Lewisian Gneiss) and caught up in the complex structure of the Main Ring Fault (MRF). The MRF shows three distinct phases of movement, each one along a different sub-parallel component fracture; i) the Outer Ring Fault (ORF), ii) the Centre Ring Fault (CRF), iii) the Inner Ring Fault (IRF), Smith (1985).The Mesozoic rocks comprise fossiliferous limestone, sandstone and shale, which show differing degrees of thermal metamorphism depending on their proximity to the Ultrabasic Complex. On a basis of faunal and lithological evidence the Mesozoic sediments have been correlated with the Lower Liassic, 'Broadford Beds', of Skye. The Rhum. Jurassic sediments are overlain by a sequence of sheared Tertiary amygdaloidal lavas, the contact between them probably representing the original landscape unconformity. These lavas have been successfully correlated by geochemistry with plateau lavas found on the adjacent island of Eigg, and provide evidence for a once extensive lava field extending over Rhum prior to the emplacement of the postulated Rhum Caidera. The presence of these fault bounded lithologies provides crucial evidence for a major phase of central subsidence during the early tectonic history of the Rhum Volcanic Centre

Iowa State Teachers College Schedule of Classes, Spring 1950

A listing of the courses being taught as well as policies and procedures concerning attending classes at the Iowa State Teachers College.https://scholarworks.uni.edu/class_schedules/1222/thumbnail.jp

The kinetics of energy transfer and reaction by electronically excited quinones

Imperial Users onl

Population genetics and behavioural ecology of North Atlantic minke whales (Balaenoptera acutorostrata)

Regional habitat use by a species, dictated by the spatial and temporal availability of resources, influences its distribution patterns and ultimately population genetic structure. Seasonal migrations between geographically separated breeding and feeding areas, as occur in many baleen whales, can complicate these relationships. Here I try to integrate the population structure of minke whales over the whole North Atlantic with regional habitat use and behavioural adaptations to a particular summer feeding ground, the Hebrides off West Scotland. Whereas no genetic differentiation could be found between separate feeding areas as far apart as Canada, the UK and Svalbard, using microsatellites and mtDNA, the presence of two cryptic breeding populations was detected, which form mixed assemblages on feeding grounds across the North Atlantic. This implies fidelity to at least two breeding grounds irrespective of proximity to feeding areas, i.e. extensive seasonal migrations (over half the North Atlantic or more), which may require a re-assessment of current management stocks. These findings were consistent with the mobility and flexibility in habitat use and behaviour observed within the Hebrides. Results from Generalized Additive Models indicated that minke whale distribution was dependent largely on temporally variable parameters (temperature in spring, chlorophyll concentration in autumn), besides depth and, to a lesser extent, topography. However, fine-scale foraging behaviour was dictated primarily by the strength and direction of tidal currents. Distribution patterns according to environmental parameters changed through the season, but were largely consistent between the entire Hebrides (cell resolution of 4min) and a smaller core study area (2min), and over a time period of 15 years. Significantly higher sighting rates in areas of likely sandeel presence in spring, but not during the rest of the season, combined with prey samples from the core study area consisting almost entirely of sprat in August/September, indicate a switch in diet between early and late season and are consistent with the changes in habitat use. Site fidelity within the core study area was high only during periods of high feeding activity, but low at other times and between years, so that individual specializations to fine-scale feeding areas, as observed off Washington State, seem unlikely. Significant interannual changes in minke sighting rates between 2003-07, both within the core study area and over the entire Hebrides, were paralleled by changes in phytoplankton concentration, local sprat landings by the fishing fleet, and seabird breeding success and numbers counted at sea, particularly common guillemots. Auks were also the seabird guild that minke whales were most likely to associate with during foraging, taking advantage of tight bait-balls concentrated by them. The significant relationships with primary productivity make bottom-up control the most likely scenario for dictating concentrations of whale and seabird prey species in West Scotland. The ability to switch between different prey according to their availability through the season, and a distribution influenced by temporally variable parameters (temperature and chlorophyll concentration), combined with adjustments in foraging activity dependent on variable conditions at fine spatial scales (tides), enable minke whales to optimise exploitation of patchy prey concentrations

Peroxidase Catalyzed Oxidation of Pentachlorophenol

The oxidation of pentachlorophenol (PCP) by two peroxidase enzymes, horseradish peroxidase (HRP) and Coprinus macrorhizus peroxidase (CMP) was studied. Oxidation of PCP by HRP and CMP was found to produce p-tetrachlorobenzoquinone (p-chloranil) and non-polar products. p-Chloranil was found to decompose to trichlorohydroxybenzoquinone and dichlorodihydroxybenzoquinone in aqueous solution. The rate of decomposition increased as pH increased, and the rate increased by two orders of magnitude when hydrogen peroxide was present in solution. Because hydrogen peroxide is required for oxidation by peroxidase enzymes, the decomposition of p-chloranil occurred rapidly in enzymatic reaction mixtures under certaui conditions. The non-polar oxidation products were not specifically identified. These products precipitate at pH 4 and can be removed from solution. PCP sorbs to the non-polar products under acidic conditions, and can also be removed from solution by filtration. The relative amount of the products formed in peroxidase catalyzed oxidation of PCP will depend on the enzyme used and the reaction conditions. CMP inactivation occurs rapidly during oxidation of PCP at pH 7. This inactivation limits the percentage of PCP which can be removed from solution.Master of Science in Environmental Engineerin

Uma pirâmide de índices para avaliação da produtividade

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico