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Techn. Universiẗat, Diss., 2002--Braunschweig.

Im Rahmen dieser Dissertation wurde in einer prospektiven klinischen Studie bei 110 kardiochirurgischen Patienten, welche sich einer Mitralklappenrekonstruktion [MKR] unterzogen, untersucht, ob mittels transösophagealer Echokardiographie [TEE] die Durchblutung der Koronarien zu Beginn, während und nach der Operation dargestellt werden kann und ob die anatomischen Gegebenheiten gut abzugrenzen sind. Dabei wurden der Ramus Circumflexus [RCX] und der Sinus Coronarius [SC] im gesamten Verlauf verfolgt, der Diameter proximal (nach Abgang der Aorta), im Verlauf (bei Überkreuzung der arteriellen und venösen Gefäße) und distal bestimmt und der Blutfluss mittels Dopplersonographie dargestellt. Ein weiterer Punkt war die Untersuchung, ob anhand des Kalibers der Gefäße verlässliche Rückschlüsse auf den Versorgungstyp geschlossen werden können, was sonst nur mittels Koronarangiographie [CA] unter Einsatz von Kontrastmittel invasiv darzustellen war. Zuletzt wurde beim sich noch in Narkose befindlichen Patienten untersucht, ob evtl. erst postoperativ durch iatrogenen Verschluss aufgetretene Wandbewegungsstörungen mittels TEE minimalinvasiv diagnostiziert werden können, sodass ggf. eine sofortige Intervention erfolgen konnte. In der Phase der Datenerhebung kam es bei drei Patienten zu Komplikationen im Sinne einer Obstruktion bzw. Stenose der RCX, wobei die Befunde der TEE-Untersuchungen zusammenmit den klinischen Symptomen in einer anschließenden Koronarangiographie bestätigt wurden. Die Ergebnisse dieser Studie wurden im Jahr 2010 in „The annals of thoracic surgery“ unter dem Titel „Echocardiographic Identification of Iatrogenic Injury of the Circumflex Artery During Minimally Invasive Mitral Valve Repair“ veröffentlicht (1).

Phase-redistribution and full-phase separation data were generated for two-phase (air-water) flow splitting at an equal-sided impacting tee junction with a horizontal inlet and inclined outlets. The flow loop incorporated a tee junction machined in an acrylic block with the three sided having an equal diameter of 13.5 ± 0.1 mm I.D. Both sets of experiments were conducted at a nominal pressure (Ps) of 200 kPa (abs) and near-ambient temperature (Ts). The operating conditions for the phase-redistribution experiments were as follows: inlet superficial liquid velocities (JL1) ranging from 0.01 to 0.18 m/s, inlet qualities (x1) ranging from 0.1 to 0.9, mass split ratios (W3/W1) from 0 to 1.0, and outlet inclination angles ranging from horizontal to vertical. These inlet conditions corresponded to inlet flow regimes of stratified, wavy, and annular. Phase-redistribution data revealed that the redistribution of phases depended on the inlet conditions, the mass split ratio at the junction, and the inclination angle of the outlets. The magnitude of the inclination effect was dependent on the inlet flow regime. The phase redistribution in stratified flow was very sensitive to the outlet angle and full separation could be achieved at angles as low as 0.7°. Wavy flow was less sensitive to the outlet angle and annular flow was even less sensitive to the outlet angle. The capability of a single impacting tee junction to perform as a full phase separator has been examined. Experimental data were obtained for the limiting inlet conditions under which full separation was attainable at various outlet inclinations (θ) of 2.5°, 7.5°, 15°, 30°, 60°, 75°, and 90°. Full separation data have shown that a single impacting tee junction can perform as a full-phase separator for some inlet conditions. Flow phenomena near the limiting conditions were observed and a simple correlation based on the similarity between these flow phenomena and the phenomenon of liquid entrainment in small upward branches was developed. This correlation was capable of accurate prediction of the data in terms of magnitude and trend.

Phase-redistribution and full-phase separation data were generated for two-phase (air-water) flow splitting at an equal-sided impacting tee junction with a horizontal inlet and inclined outlets. The flow loop incorporated a tee junction machined in an acrylic block with the three sided having an equal diameter of 13.5 ± 0.1 mm I.D. Both sets of experiments were conducted at a nominal pressure (Ps) of 200 kPa (abs) and near-ambient temperature (Ts). The operating conditions for the phase-redistribution experiments were as follows: inlet superficial liquid velocities (JL1) ranging from 0.01 to 0.18 m/s, inlet qualities (x1) ranging from 0.1 to 0.9, mass split ratios (W3/W1) from 0 to 1.0, and outlet inclination angles ranging from horizontal to vertical. These inlet conditions corresponded to inlet flow regimes of stratified, wavy, and annular. Phase-redistribution data revealed that the redistribution of phases depended on the inlet conditions, the mass split ratio at the junction, and the inclination angle of the outlets. The magnitude of the inclination effect was dependent on the inlet flow regime. The phase redistribution in stratified flow was very sensitive to the outlet angle and full separation could be achieved at angles as low as 0.7°. Wavy flow was less sensitive to the outlet angle and annular flow was even less sensitive to the outlet angle. The capability of a single impacting tee junction to perform as a full phase separator has been examined. Experimental data were obtained for the limiting inlet conditions under which full separation was attainable at various outlet inclinations (θ) of 2.5°, 7.5°, 15°, 30°, 60°, 75°, and 90°. Full separation data have shown that a single impacting tee junction can perform as a full-phase separator for some inlet conditions. Flow phenomena near the limiting conditions were observed and a simple correlation based on the similarity between these flow phenomena and the phenomenon of liquid entrainment in small upward branches was developed. This correlation was capable of accurate prediction of the data in terms of magnitude and trend.

Wetting and spreading of liquid systems on solid substrates under transient conditions, driven by surface tension and viscous forces along with the interface interactions (e.g., a substrate dissolution or diffusion and/or chemical reaction) is a complex problem, still waiting to be fully understood. In this study we have performed an extensive experimental investigation of liquid aluminum alloy spreading over aluminum substrate along with corroboration with theoretical modeling, performed in separate but coordinate study. Wetting and spreading to be considered take place during a transient formation of the free liquid surface in both sessile drop and wedge-tee mating surfaces’ configurations. The AA3003 is used as a substrate and a novel self-fluxing material called TrilliumTM is considered as the filler metal. In addition, benchmark, non-reactive cases of spreading of water and silicon oil over quartz glass are considered. The study is performed experimentally by a high temperature optical dynamic contact angle measuring system and a standard and high speed visible light camera, as well as with infra read imaging. Benchmark tests of non-reactive systems are conducted under ambient environment’s conditions. Molten metal experiment series featured aluminum and silicone alloys under controlled atmosphere at elevated temperatures. The chamber atmosphere is maintained by the ultra-high purity nitrogen gas purge process with the temperature monitored in real time in situ. Different configurations of the wedge-tee joints are designed to explore different parameters impacting the kinetics of the triple line movement process. Different power law relationships are identified, supporting subsequent theoretical analysis and simulation. Under ambient temperature conditions, the non-reactive liquid wetting and spreading experiments (water and oil systems) were studied to verify the equilibrium triple line location relationships. The kinetics relationship between the dynamic contact angle and the triple line location is identified. Additional simulation and theoretical analysis of the triple line movement is conducted using the commercial computer software platform Comsol in a collaboration with a team from Washington State University within the NSF sponsored Grant #1235759 and # 1234581. The experimental work conducted here has been complemented by a verification of the Comsol phase-field modeling. Both segments of work (experimental and numerical) are parts of the collaborative NSF sponsored project involving the University of Kentucky and Washington State University. The phase field modeling used in this work was developed at the Washington State University and data are corroborated with experimental results obtained within the scope of this Thesis.

In the flow distribution section of a paper machine, known as the head box, water is injected into the fiber suspension (stock) flow through a tee-mixer for more uniform production. This dilution process has two important requirements that must be fulfilled: (1) sufficient mixing so that the dilution flow spreads across the suspension flow and (2) that the injection flow rate not be so large to significantly alter the local head box flow rate. The objective of this research was to find a combination of velocity ratio and tee mixer geometry that lead to the injection flow being well mixed into the stock flow, but at the same time, the injection should not cause the total flow rate to change by more than 1%. Velocity ratios of 0.25, 0.75, 1.33, 1.5 and 2.25 were examined for four different cases of tee mixer geometries using the CFD software Fluent. Two of the cases had added contractions located near the injection point, while the other two cases had a more standard geometry with no added complexities. The pressure drop across the injection point was also measured. Mixing was qualitatively measured by simulating the injection of a passive tracer into the dilution flow. All of the results indicated that the case where the contraction was located after the injection showed the most promising results with quality mixing and lower flow rates. The cases without added contractions showed poor mixing for lower velocity ratios, and for higher velocity ratios, the flow rates were too large. The cases with contractions showed similar mixing, but the outlet flow rates produced were lower when the contraction was located after the injection instead of before it. A velocity ratio of 0.25-0.75 for the mixers with contractions produced acceptable flow rates and sufficient mixing. The simulations also showed that the static pressure for the contraction cases were nearly identical throughout the majority of the pipe. For both contraction cases the pressure drop across the injection increased with increasing injection flow rate. When the contraction was located before the injection, a pressure drop of 16% was calculated. A pressure drop of 18% to 20% across the injection resulted when the contraction was located after the injection.

Loeffler, Bernd Matthias Nikolaus Untersuchungen zur Pharmakokinetik von Coffein, Theophyllin und Theobromin beim Hund nach Aufnahme von Kaffee, Tee und Schokolade aus dem Institut für Pharmakologie, Pharmazie und Toxikologie der Veterinärmedizinischen Fakultät der Universität Leipzig Leipzig im April 2000 (83 S., 24 Abb., 12 Tab., 187 Lit.) Methylxanthine stimulieren das zentrale Nervensystem, das Herz-Kreislauf-System und führen zur Bronchodilatation. Die Ergebnisse der Dopinguntersuchungen im Windhundrennsport zeigen, daß die Methylxanthine wie Coffein, Theophyllin und Theobromin nicht nur therapeutisch, sondern auch mißbräuchlich zur Leistungssteigerung eingesetzt werden. In der vorliegenden Studie wurde die Pharmakokinetik von Coffein, Theophyllin und Theobromin bei Hunden untersucht. Speziell in Hinblick auf die Dopingproblematik im Windhundsport wurden bei den Hunden zusätzlich Plasma- und Harnproben nach Applikation von Kaffee, Tee und Schokolade analysiert. Nach oraler Applikation von Coffein und Theophyllin (10 mg/kg KM) wurden im Plasma mittlere Konzentrationsmaxima an Coffein von 61,8 µmol/l und an Theophyllin von 42,5 µmol/l nach 1,6 bzw. 4,8 Stunden erreicht. Die Elimination erfolgte jeweils mit einer Halbwertszeit von etwa 3 Stunden. Im Urin konnten die applizierten Methylxanthine ebenfalls nachgewiesen werden, nach Applikation von Coffein war Theobromin als Metabolit in hohen Konzentrationen nachweisbar. Nach Aufnahme von Kaffee und Tee durch Hunde konnte in Plasma und Urin Coffein, Theophyllin und Theobromin nachgewiesen werden. Nach Verfütterung von Schokolade wurde im Wesentlichen nur Theobromin gefunden, so daß aus dem Metabolitenmuster der Methylxanthine zum Teil auf das aufgenommene Nahrungsmittel geschlossen werden kann. Um nicht in Konflikt mit geltenden Dopingbestimmungen zu kommen, sollten Hundehalter darauf achten, daß ihre Tiere in den Tagen vor einem Rennen keinen Zugang zu methylxanthinhaltigen Produkten wie Kaffee, Tee und Schokolade haben. / Loeffler, Bernd Matthias Nikolaus Investigations of the pharmacokinetics of caffeine, theophylline and theobromine in the dog. Institute of Pharmacology, Pharmacy and Toxicology of the Veterinary Faculty of the University of Leipzig Leipzig, April 2000 (83 p., 24 fig., 12 tab., 187 ref.) Methylxanthines are often used as stimulants of the central nervous system, of the cardiovascular system and as bronchodilators. Doping samples of racing greyhounds demonstrate that methylxanthines like caffeine, theophylline, and theobromine besides their therapeutic use, are illegally used to strengthen the animals. In this study the pharmacokinetics of caffeine, theophylline and theobromine in dogs were examined. Additionally samples of plasma and urine were taken after application of coffee, tea, and chocolate. After oral application of caffeine and theophylline (10 mg/kg) highest plasma concentrations of caffeine were about 61.8 µmol/l and of theophylline about 42.5 µmol/l after 1.6 and 4.8 hours, respectively. The elimination half-lives for both methylxanthines were 3 hours. The methylxanthines administered could also be detected in the urine, after application of caffeine its metabolite theobromine reached high concentrations. After the administration of coffee and tea to dogs caffeine, theophylline and theobromine can be found in plasma and urine. After the feeding of cocoa products (chocolate) theobromine was the predominant methylxanthine to be analysed. Therefore the quantitative relationship of the various methylxanthine metabolites detected can indicate the origin of the ingested methylxanthines. In order to avoid violation of doping regulations, dog owners should assure that their animals have no access to methylxanthine-containing diets in the days before racing competitions.

Zugl.: Mainz, Univ., Diss., 2004 / Hergestellt on demand

Fingerprint identification is becoming increasingly popular as a means of authentication for handheld devices of different kinds. In order to secure such an authentication solution it is common to use a TEE implementation. This thesis examines the possibility of replacing a TEE with a hypervisor-based solution instead, with the intention of keeping the same security features that a TEE can offer. To carry out the evaluation a suitable method is constructed. This method makes use of fault trees to be able to find possible vulnerabilities in both systems, and these vulnerabilities are then documented. The vulnerabilities of both systems are also compared to each other to identify differences in how they are handled. It is concluded that if the target platform has the ability to implement a TEE solution, it can also implement the same solution using a hypervisor. However, the authors recommend against porting a working TEE solution, as TEEs often offer finished APIs for common operations that would require re-implementation in the examined hypervisor.