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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Novel Interventions in Cardiac Arrest : Targeted Temperature Management, Methylene Blue, S-PBN, Amiodarone, Milrinone and Esmolol,  Endothelin and Nitric Oxide In Porcine Resuscitation Models

Zoerner, Frank January 2015 (has links)
It is a major clinical problem that survival rates after out-of-hospital cardiac arrest have not markedly improved during the last decades, despite extensive research and the introduction of new interventions. However, recent studies have demonstrated promising treatments such as targeted temperature management (TTM) and methylene blue (MB). In our first study, we investigated the effect of MB administered during experi-mental cardiopulmonary resuscitation (CPR) in the setting of postponed hypother-mia in piglets. We set out to study if MB could compensate for a delay to establish targeted TTM. The study demonstrated that MB more than compensated for 30 min delay in induction of TTM. The effect of MB added to that of TTM. The second study examined the effects of TTM and S-PBN on the endothelin system and nitric oxide synthases (NOS) after prolonged CA in a porcine CPR mod-el. The study was designed to understand the cardioprotective mechanism of S-PBN and TTM by their influence on the endothelin system and NOS regulation. We veri-fied for the first time, that these two cardioprotective postresuscitative interventions activate endothelin-1 and its receptors concomitantly with eNOS and nNOS in the myocardium. We concluded that nitric oxide and endothelin pathways are implicated in the postresuscitative cardioprotective effects of TTM. The third study compared survival and hemodynamic effects of low-dose amio-darone and vasopressin to vasopressin in a porcine hypovolemic CA model. The study was designed to evaluate whether resuscitation with amiodarone and vasopressin compared to vasopressin alone would have an impact on resuscitation success, survival, and hemodynamic parameters after hemorrhagic CA. We found that combined resuscitation with amiodarone and vasopressin after hemorrhagic circulatory arrest resulted in greater 3-hour survival, better preserved hemodynamic parameters and smaller myocardial injury compared to resuscitation with vasopressin only. In our fourth study we planned to compare hemodynamic parameters between the treatment group (milrinone, esmolol and vasopressin; MEV) and control group (vasopressin only) during resuscitation from prolonged cardiac arrest in piglets. The study was designed to demonstrate if MEV treatment improved hemodynamics or cardiac damage compared to controls. We demonstrated that MEV treatment reduced cardiac injury compared with vasopressin alone.
2

Effect of microwave radiation on Fe/ZSM-5 for catalytic conversion of methanol to hydrocarbons (MTH)

Ntelane, Tau Silvester 03 1900 (has links)
The effect of microwave radiation on the prepared 0.5Fe/ZSM-5 catalysts as a post-synthesis modification step was studied in the methanol-to-hydrocarbons process using the temperature-programmed surface reaction (TPSR) technique. This was achieved by preparing a series of 0.5Fe/ZSM-5 based catalysts under varying microwave power levels (0–700 W) and over a 10 s period, after iron impregnating the HZSM-5 zeolite (Si/Al = 30 and 80). Physicochemical properties were determined by XRD, SEM, BET, FT-IR, C3H9N-TPSR, and TGA techniques. It was found that microwave radiation induced few changes in the bulk properties of the 0.5Fe/ZSM-5 catalysts, but their surface and catalytic behavior were distinctly changed. Microwave radiation enhanced crystallinity and mesoporous growth, decreased coke and methane formation, decreased the concentration of Brønsted acidic sites, and decreased surface area and micropore volume as the microwave power level was increased from 0 to 700 W. From the TPSR profiles, it was observed that microwave radiation affects the peak intensities of the produced hydrocarbons. Application of microwave radiation shifted the desorption temperatures of the MTH process products over the HZSM-5(30) and HZSM-5(80) based catalysts to lower and higher values respectively. The MeOH-TPSR profiles showed that methanol was converted to DME and subsequently converted to aliphatic and aromatic hydrocarbons. It is reasonable to suggest that microwave radiation would be an essential post-synthesis modification step to mitigate coke formation and methane formation and increase catalyst activity and selectivity. / Chemical Engineering / M. Tech. (Chemical Engineering)

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