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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

Safety and efficacy of multilevel ACDF/ACCF surgery (anterior cervical discectomy/corpectomy and fusion): retrospective comparative cohort study

Cygan, Liliana Maria 17 February 2016 (has links)
PURPOSE: The goal of this thesis research project is to evaluate and compare post-operative complications among patients, who underwent short and long segment Anterior Cervical Discectomy/Corpectomy and Fusion (ACDF/ACCF). METHODS: Retrospective cohort study design allowed for evaluation of series of variables (age, sex, diagnosis, general post-operative outcome, and complications) while comparing them between the short and long segment groups. RESULTS: Patients within both cohorts tended to experience similar complications, except pseudarthrosis and adjacent segment disease, which both were more prevalent in the long segment group. Diagnosis or short versus long segment length did not have an effect on the general post-operative outcome. One-level ACDF patients were younger than multilevel ACDF surgery patients. Dysphagia was more likely to occur in older patients, with the risk of dysphagia incidence increased by 7% with each year of patient’s age. CONCLUSIONS: Study indicated that longer segment ACDF/ACCF does not carry higher risk of complications incidence than short segment treatment. Further studies are advised to increase generalizability of these results.
2

Decomposition of Acetone by Nano-sized Photocatalysts Coated on Activated Carbon Cellulose-paper Filter

Peng, Yi-wei 27 August 2008 (has links)
This study combined photocatalytic technology with activated carbon cellulose-paper filter (ACCF) adsorption to decompose gaseous pollutants. Gaseous pollutants were initially adsorbed by activated carbon and could be further decomposed by photocatalytic technology. This study selected acetone (CH3COCH3) as gaseous pollutants. Two market available photocatalysts (photocatalysts¢¹and¢º) were coated on ACCF by impregnation to decompose acetone in a batch photocatlytic reactor. Operating parameters investigated in this study included initial acetone concentration (4.1~10.2 £gM), reaction temperature (40~70¢J), and water vapor (0~20 %). The incident UV light of 365 nm was irradiated by a 20-watt low-pressure mercury lamp placing above the batch photocatalytic reactor. The ACCF coated with TiO2 was placed at the center of the photocatalytic reactor. Acetone was injected into the reactor by a gasket syringe to conduct the photocatalytic tests. Reactants and products were analyzed quantitatively by a gas chromatography with an electron capture detector (GC/DCD) and a flame ionization detector followed by a methaneizer (GC/FID-Methaneizer). Finally, a Langmiur-Hinshewood (L-H) kinetic model was proposed to describe the rate of photocatalytic reaction. Results obtained from the photocatalytic tests indicated that photocatalyst¢º was better than photocatalyst¢¹ for the decomposition of acetone. Experimental results indicated that the size range of self-produced TiO2 photocatalyst by sol-gel was 20~70 nm. The end products were mainly CO and CO2, which resulted in the mineralization ratio up to 98%. Results obtained from the operating parameter tests revealed that the increase of initial acetone concentration enhanced the amount of acetone adsorbed on ACCF, which however did not increase the reaction rate of acetone. Although the increase of reaction temperature could reduce the amount of acetone adsorbed on ACCF, the decomposition rate of acetone could be promoted, so as the yield rate and mineralization ratio of products (CO and CO2). The increase of water vapor could slightly decrease the amount of acetone adsorbed on ACCF. The competitive adsorption phenomenon between acetone and water molecules on active sites could decelerate the decomposion of acetone. Moreover, the ACCF would not be saturated since the adsorbed acetone could be further decomposed quickly by the photocatalysts, which made the TiO2/ACCF more effective on removing acetone and lasted longer than the conventional ACCF. Finally, a modified bimolecular Langmuir-Hinshelwood kinetic model was developed to investigate the influences of initial acetone concentration reaction, temperature, and relative humidity on the promotion and inhibition for the photocatalytic oxidation of acetone. The modified L-H kinetic model could successfully simulate the photocatalytic reaction rate of acetone. Thus, the reaction rate of acetone over TiO2/ACCF could be described by the modified L-H kinetic model.

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