Berlin, Freie Universiẗat, Diss., 2001. / Dateiformat: zip, Dateien im PDF-Format.

Berlin, Freie University, Diss., 2005. / Dateiformat: zp, Dateien im PDF-Format.

Zugl.: Leipzig, Univ., Diss., 2009

Universiẗat, Diss., 1999--Freiburg (Breisgau).

Universiẗat, Diss., 2003--München.

In this work, the metal and slag phase mixing in three steps of a ladle refining operation of steel melts and for an oxygen balance during cooling of cast iron melts have been studied at two Swedish steel plants and at two Swedish cast iron foundries, respectively. In order to predict the oxygen activity in the steel bulk in equilibrium with the top slag as well as in metal droplets in the top slag in equilibrium with the top slag, three slag models were used. In addition, the assumptions of a sulphur-oxygen equilibrium between steel and slag and the dilute solution model for the liquid steel phase were utilized in the calculations. Measured oxygen activities in steel bulk, which varied between 3.5-6 ppm, were compared to predicted oxygen activities. The differences between the predicted and measured oxygen activities were found to be significant (0-500%) and the reasons for the differences are discussed in the thesis. Slag samples have been evaluated to determine the distribution of the metal droplets. The results show that the relatively largest numbers of metal droplets are present in the slag samples taken before vacuum degassing. Also, the projected interfacial area between steel bulk and top slag has been compared to the interfacial area between the metal droplets and slag. The results show that the droplet-slag interfacial area is 3 to 14 times larger than the flat projected interfacial area between the steel and top slag. Furthermore, the effect of the reactions between top slag and steel and the slag viscosity on the metal droplet formation is discussed. The results show significant differences between the steel bulk and steel droplet compositions and the reasons for the differences are discussed in the thesis. The oxygen activity in different cast irons was studied. Plant trials were performed at three occasions for lamellar, compacted and nodular iron melts. The results show that at temperatures close to the liquidus temperature the oxygen activities were 0.03-0.1 ppm for LGI, around 0.02 ppm for CGI, and 0.001ppm for SGI. In addition, it was found that as the oxygen activities increased with time after an Mg treatment, the ability to form a compact graphite or a nodular graphite in Mg-treated iron melts was decreased. Also, extrapolated oxygen activity differences up to 0.07 ppm were found for different hypoeutectic iron compositions for lamellar graphite iron at the liquidus temperature. Overall, the observed differences in the dissolved oxygen levels were believed to influence how graphite particles are incorporated into the austenite matrix and how the graphite morphology will be in the cast product. / <p>QC 20160518</p>

In this master thesis we investigate, from a topological point of view and without applying Thurston´s Theorem, why the mating of the so called basilica polynomial <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7B-1%7D(z)=z%5E%7B2%7D-1" /> and the dendrite <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7Bi%7D(z)=z%5E%7B2%7D+i" /> is shared with the mating of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7B-1%7D" /> and the dendrite <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7B-i%7D(z)=z%5E%7B2%7D-i" />. Both these matings equal the rational map <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?R_%7B3%7D(z)=%5Cfrac%7B3%7D%7Bz%5E%7B2%7D+2z%7D" />. Defined in the thesis are for both matings homeomorphic changes of coordinates<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cpsi_%7B-1%7D%5E%7B%5Cpm%7D" /> from the set <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?L=%5Coverset%7B%5Ccirc%7D%7BK%7D%5Cleft(f_%7B-1%7D%20%5Cright)%5Ccup%5Cleft(%5Ccup_%7Bn=0%7D%5E%7B%5Cinfty%7Df_%7B-1%7D%5E%7B%5Ccirc(-n)%7D(z_%7B%5Calpha%7D)%5Cright)" /> to the Fatou and Julia set of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?R_%7B3%7D" />. Here <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?K%5Cleft(f_%7B-1%7D%20%5Cright)" /> is the filled Julia set of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7B-1%7D" /> and <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?z_%7B%5Calpha%7D" /> is the <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Calpha" />-fixed point of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?K%5Cleft(f_%7B-1%7D%20%5Cright)" />. / I detta examensarbete undersöker vi, från en topologisk synvinkel och utan applicering av Thurstons teorem, varför matchningen av det så kallade basilikapolynomet <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7B-1%7D(z)=z%5E%7B2%7D-1" /> och dendriten <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7Bi%7D(z)=z%5E%7B2%7D+i" /> är delad med matchningen av <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7B-1%7D" /> och dendriten <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7B-i%7D(z)=z%5E%7B2%7D-i" />. Båda dessa matchningar är lika med den rationella avbildningen  <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?R_%7B3%7D(z)=%5Cfrac%7B3%7D%7Bz%5E%7B2%7D+2z%7D" />. Definierat i examensarbetet är för båda matchningarna homoemorfa koordinatbyten<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Cpsi_%7B-1%7D%5E%7B%5Cpm%7D" /> från mängden<img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?L=%5Coverset%7B%5Ccirc%7D%7BK%7D%5Cleft(f_%7B-1%7D%20%5Cright)%5Ccup%5Cleft(%5Ccup_%7Bn=0%7D%5E%7B%5Cinfty%7Df_%7B-1%7D%5E%7B%5Ccirc(-n)%7D(z_%7B%5Calpha%7D)%5Cright)" /> till Fatou- och Juliamängden av <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?R_%7B3%7D" />. Här är <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?K%5Cleft(f_%7B-1%7D%20%5Cright)" /> den ifyllda Juliamängden av avbildningen <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?f_%7B-1%7D" /> och <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?z_%7B%5Calpha%7D" /> är den <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?%5Calpha" />-fixerade punkten i <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?K%5Cleft(f_%7B-1%7D%20%5Cright)" />.

München, Techn. Univ., Diss., 2001.

Techn. Universiẗat, Diss., 2004--Darmstadt.

Obwohl die Struktur und das Ausmaß dendritischer Verzweigungen eine wichtige Rolle bei der Informationsübertragung neuronaler Zellen spielen, ist bislang wenig über die Bausteine und Molekularmechanismen des Dendritenwachstums bekannt. Unter der Verwendung primär dissoziierter hippocampaler Zellkulturen embryonaler Mäuse untersuchte ich frühe Stadien des Zellfortsatzwachstums. Dabei konnte ich SNAP-25 (synaptosomal associated protein of 25 kDA), ein Schlüsselprotein der regulierten Exozytose, nicht nur in Axonen und terminalen Axonendigungen, sondern auch anhand von Doppelimmunmarkierungen mit den dendritischen Markern Transferrin-Rezeptor und MAP-2 in Dendriten lokalisieren. Die spezifische Inaktivierung von SNAP-25 durch Botulinumneurotoxin A (BoNT/A) führte zur Hemmung des Axonwachstums und des Vesikelrecyclings in terminalen Axonendigungen. Darüberhinaus wurde auch das Wachstum dendritischer Fortsätze von Körner- und Pyramidenzellen durch BoNT/A signifikant gehemmt. Daraus läßt sich schließen, daß SNAP-25, im Gegensatz zu Synaptobrevin, an konstitutiven Prozessen in den Axonen und Dendriten hippocampaler Neurone beteiligt ist. / Structure and dimension of the dendritic arbor are important determinants of information processing by the nerve cell, but mechanisms and molecules involved in dendritic growth are essentially unknown. I investigated early mechanisms of dendritic growth using mouse fetal hippocampal neurons in primary culture, which form processes during the first week in vitro. I detected a key component of regulated exocytosis, SNAP-25 (synaptosomal associated protein of 25 kDa)., in axons and axonal terminals as well as in dendrites identified by the occurrence of the dendritic markers transferrin receptor and MAP2. Selective inactivation of SNAP-25 by botulinum neurotoxin A (BoNTA) resulted in inhibition of axonal growth and of vesicle recycling in axonal terminals. In addition, dendritic growth of hippocampal pyramidal and granule neurons was significantly inhibited by BoNTA. These observations indicate that SNAP-25, but not synaptobrevin, is involved in constitutive axonal growth and dendrite formation by hippocampal neurons.