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The energy crisis and environment deterioration are two major problems for the 21st century. Waste heat recovery offers many opportunities to make a global contribution to this challenge. Key concepts such as waste heat recovery are the basic ideas in thermoelectricity. A part of waste heat is produced by solid-fuel stoves. Nevertheless, the quantity of high-performance solid-fuel stoves is increasing very quickly for economic and environmental reasons. These sophisticated stoves need electricity for the pump for water circulation and the control system. Thermoelectric generators (TEG) could help with this issue. This work aims to present an experimental validation of integrating a thermoelectric generator into a solid-fuel stove. An economic comparison between the most common Bismuth Telluride (Bi2Te3) module and the newly developed half-Heusler modules is complete. An experimental set-up was built to optimize the common (Bi2Te3) modules and test the newly developed half-Heusler modules from an entire system point of view. An assessment of thermoelectric technology potential, module prices, further material developments and applications is completed. Based on the literature research and a Computational Fluid Dynamics (CFD) simulation software the first prototype was built. This set-up is composed of a thermal loop with a hot gas source, a cold fluid, a hot fin exchanger, and thermoelectric modules. The number and the place of these modules are changed to study different configurations. A specific maximum power point tracker DC/DC converter charging a battery is added in order to study the electrical power produced by the module. Different operating points of hot inlet gas airflow were tested for the Bismuth Telluride and half-Heusler modules. The Bismuth Telluride module was tested under real-life conditions using the exhaust of the solid-fuel stoves without influencing the combustion chamber.
Testing the Optical Quality of Intraocular Lenses Regarding Postoperative Tilt and Decentration
(2018)
Since the early 1980s, shock wave treatment has been the golden standard treatment option for the disintegration of kidney stones in urology. A wide range of beneficial effects of shock waves on the human body was soon identified, starting with first observations of bone densification at the iliac crest after treatment of kidney stones. Since then, the indications for shock wave therapy have conquered areas apart from the field of urology. Nowadays, shock wave therapy is used for a variety of indications such as tendinopathies or impaired bone healing.
Furthermore, patients suffering from poor wound healing such as diabetic foot ulcers and also chronic, non-healing wounds are treated successfully with shock waves. Despite the versatile application fields of shock wave therapy, the general principles underlying the beneficial effect of this treatment still remain to be fully elucidated. Several in vitro and in vivo studies, mostly involving osteoblast like cells and the osteo-inductive potential of shock wave treatment, already highlighted the role of the activation of mechanotransductory signaling pathways. For the clinical application of shock wave therapy as an accepted treatment for critically healing wounds (e.g. chronic or diabetic wounds, burns), general mechanistic evidence to explain the underlying mechanisms is essential. These data would facilitate the standardized application of this non-invasive, cost efficient and low- risk bearing therapy, which can be performed in an outpatient setting.
First of all, an in vitro set-up was established and the necessary technical parameters for the optimal application of shock wave treatment on cell cultures were defined in this thesis. For this purpose, a molecule uptake assay was used as a functional assay. The following aims of this study were to elucidate the effect of shock wave treatment on intracellular signaling in vitro and to ultimately describe their role in the wound healing effect of shock wave treatment in vivo. To identify universal effects of shock wave treatment on intracellular signaling mechanisms, various cell lines were used, including the human U937 monocytic cell line, a human Jurkat T-cell line, the human MG63 osteosarcoma cell line, the C3H10T1/2 mouse mesenchymal progenitor cell line as well as primary human peripheral mononuclear cells. For the first time, the affected signaling cascade leading to the proliferative effect of shock wave treatment in vitro was described in detail in mouse C3H10T1/2 cells as well as in human adipose tissue-derived stem cells and human Jurkat T-cells. Further, ATP release from shock wave treated cells was shown to initiate intracellular Erk1/2 signaling activation via purinergic signaling. The thereby ultimately increased proliferation was reported to be dependent on shock wave treatment triggered Erk1/2 pathway activation. An in vivo study on impaired wound healing in rats confirmed the hypothesis on the essential role of Erk1/2 signaling in the shock wave treatment induced wound healing effect. Data clearly indicate the crucial importance of the Erk1/2 signaling cascade in the proliferative and wound healing effect of shock wave treatment.
Conclusively, purinergic signaling activated Erk1/2 signaling cascades play an essential role in the shock wave treatment induced proliferative and wound healing effect. The thereby broadened knowledge on the underlying mechanistic principles of the effect of shock wave treatment contributes to the establishment of shock wave therapy as a feasible standard treatment for soft tissue wound healing disorders such as diabetic or chronic wounds.