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Made available in DSpace on 2014-10-09T12:45:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:32Z (GMT). No. of bitstreams: 1 07010.pdf: 3753502 bytes, checksum: 80265a4934538bb733d92c91db9ef136 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Målet med denna undersökning är att minska energiförbrukningen vid framställning av gjutna detaljer i austenitiskt manganstål. Detta görs genom att undersöka om det är materialmässigt möjligt att göra förändringar som förkortar framställningsprocessen av de gjutna detaljerna medan snarlika materialegenskaper bibehålls. Den processförändring som undersöks är att slopa upplösningsbehandlingen under framställningsprocessen genom att istället släcka den gjutna detaljen direkt efter uppslag från gjutform. Konkret innebär detta att detaljen slås upp och släcks vid ett tidigare och tidsbestämt skede. Detta tillvägagångssätt kallas inom metallindustrin för direkt släckning och appliceras idag på andra legeringar och tillverkningsprocesser.För att undersöka om det är materialtekniskt möjligt att genomföra denna förändring i framställningsprocessen tas provkroppar fram. Dessa provkroppar är av en förbestämd geometri och tas fram under kontrollerade förutsättningar. Av totalt nio provkroppar släcks sex provkroppar direkt medan tre genomgår upplösningsbehandling där de senast nämnda används som referenser. Provkropparna undersöks med metoder så som mikroskopi och hårdhetsmätning för att bestämma de relevanta materialegenskaperna i provkropparna. Undersökningen visar antydningar på att det är möjligt att införa direkt släckning. Detta eftersom kornstorlek och karbidandelar inte skiljer sig nämnvärt mellan direkt släckta och värmebehandlade prover som har undersökts i denna studie. Men för ett mer definitivt fastställande behövs fortsatta studier. / The aim of this study is to reduce the energy consumed during manufacturing of parts in manganese steel. This is done by determining the possibility to make changes that shortens the production process of the castings while keeping the material properties similar. The process change that is studied is to see if it is possible to skip the heat treatment process by quenching directly after shake out of the casting. This means that the casted product needs to be shaken out and quenched at an earlier and more specific time. This process is known in the metal industry as direct quenching and is by the time of writing applied on different alloys and manufacturing processes.To determine the possibility to make the aforementioned changes to the casting process, taking the material properties into account, sample bodies are created. These sample bodies are of a predetermined geometry and are manufactured under controlled circumstances. From a total of nine sample bodies six are directly quenched and three are put through a heat treatment process, the later mentioned bodies are used as references. The sample bodies are studied with methods such as microscopy and hardness testing. In this study there are indications that it is possible to introduce direct quencing in the production of details made of austenitic manganese steel. This is because the difference in grain size and fraction of carbides is small between the direct quenched and the heat treated samples in this study. Nevertheless, further studies needs to be made to make a more definitive conclusion.

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Previous studies have suggested that manganese (Mn) deficiency is associated with increased pancreatic amylase activity in rats. The present study investigated whether this increase in amylase activity is a result of increased pancreatic amylase messenger RNA (mRNA) levels. Weanling rats were fed a high carbohydrate diet containing either 39.6 ppm (control) or 0.5 ppm (deficient) manganese for 4 to 8 weeks. Manganese deficiency was confirmed by determining hepatic manganese content which was significantly lower in Mn-deficient rats than in the respective controls. Pancreatic RNA was size-fractionated on formaldehyde gels, and hybridized with 32P-labeled complementary DNAs (cDNA) for amylase and trypsinogen. Amylase mRNA levels were increased significantly in both 4 week (200%) and 8 week (250%) Mn-deficient rats when compared with their respective controls. In contrast, manganese deficiency was not associated with alternations in trypsinogen mRNA levels. Moreover, in vitro translation of the pancreatic mRNA indicated that manganese deficiency increased amylase mRNA levels supporting the Northern Blot analysis. Insulin and corticosterone, hormones known to increase amylase mRNA levels, were not affected by Mn-deficiency. These observations suggest that manganese may participate in the regulation of amylase gene expression.

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Silica functionalised with PAMAM dendrimer chains has been investigated as a support for anchoring chiral salen complexes in both an axial and covalent fashion. It was found that using a high dendrimer chain density resulted in very low enantioselectivity in the epoxidation of styrene, 1-methyl-1-cyclohexene and α-methylstyrene. Through a thorough series of tests the poor performance was attributed to both interactions with the surface and with neighbouring dendrimer chains. It was found that the system could be improved by decreasing the dendrimer chain density and pacifying the surface by capping the remaining surface hydroxyl groups on the silica. This resulted in the epoxidation of α-methylstyrene with a considerably improved enantioselectivity. Dendritically functionalised silica and silica coated magnetic nanoparticles were also investigated as supports for the immobilisation of an achiral salen complex. High epoxide selectivity was achieved with α-pinene and 1-methyl-1-cyclohexene, while more moderate selectivity was achieved with cyclohexene and limonene as substrates. The heterogeneous catalysts could generally be used 3 times with no apparent loss in activity or selectivity. Both enantiomers of α-pinene and limonene were used to investigate immobilised chiral salen complexes. Results indicate that the diastereomeric excess produced is independent of the configuration or presence of stereogenic centres in the complex. Instead the stereoselectivity appears to be controlled by the nature of the substrate alone. These results call into question the use of such substrates for the investigation of immobilised chiral salen complexes.