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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.
271

The Effect of Controlling Temperature and Relative Humidity on Tyrophagus Putrescentiae (Schrank) (Sarcoptiformes: Acaridae) Infestations on Dry Cured Hams Treated in Food Grade Ingredient Infused Nets

Hendrix, Jasmine Deneen 08 December 2017 (has links)
Since methyl bromide is an ozone depleting substance, there is a significant need to find effective alternative compounds to control mite infestations on dry cured hams. Therefore, the objective of this study was to determine the most effective relative humidity and/or temperature to minimize mite reproduction and mold growth on dry cured hams in untreated and food grade ingredient infused nets. Mites on ham slices in untreated nets were reduced from the initial inoculum level of 50 mites per ham slice when exposed to 85% RH at 24, 28, and 32°C. Results indicated that hams should be stored at 85% RH or greater to minimize mite reproduction when xanthan gum and propylene glycol infused nets are used. Nets infused with carrageenan, propylene glycol alginate, and propylene glycol, completely inhibited mite reproduction at 85% RH and were effective at controlling mold growth.
272

Incorporating Fermented By-Products of Lactobacillus Diolivorans Sp. in Food Grade Coatings Designed for Inhibition of Tyrophagus Putrescentiae on Dry-Cured Hams

Portillo, Hector Asis 08 December 2017 (has links)
Distillate solutions that were derived from concentrated ferment were incorporated into either a carrageenan (CG) and propylene glycol alginate (PGA) gum blend or into a CG, PGA, and xanthan gum (XG) blend. Distillate treatments were compared against a 10% propylene glycol treatment, a gum only control, and negative control using three hams that were cut into 2.5 cm thick slices and then cut into 2.5×2.5×2.5cm cubes (n=50) that were dipped into solutions prior to conducting mite bioassays. Coated and control ham cubes were inoculated with 20 adult mites from the species T. putrescentiae (Schrank), and incubated for 2 and 3 weeks. The distilled treatments with CG + PGA + XG had a greater reduction (P<0.05) in mite populations than all other treatments with the exception of the 10% PG coated treatments. In addition, there were no differences between treatments with respect to sensory texture, flavor, and moistness.
273

Dry Reforming of Methane by Ni-In-Ce Supported Catalysts

Alharbi, Abdulrahman 08 1900 (has links)
In light of global warming’s environmental implications, research is shifted towards potential processes that can utilize CO2 and reduce its emissions in the industrial sector. One of the promising processes is dry reforming of methane (DRM), which is capable of utilizing CO2 and producing valuable syngas (H2 and CO). The main challenge of DRM is the deactivation of catalysts under the reaction temperatures (above 700 °C) due to sintering of the active metal and coke formation. Ni-based catalysts are the most widely investigated catalysts in literature for DRM due to their cost efficiency and availability. This study is an extension of the work done by Saudi Basic Industries Corporation (SABIC) devoted to investigating Ni-Ce-In system for DRM reaction. Five catalysts were synthesized by dry impregnation method according to SABIC synthesis procedure (Ni/Al2O3, Ni-In/Al2O3, Ni/CeO2/Al2O3, Ni/In-CeO2/Al2O3, and Ni-In/CeO2/Al2O3). The metallic loading targets were 7.5 wt.%, 10 wt.%, and 0.8 wt.% for nickel, cerium, and indium, respectively. The addition of indium in combination with cerium resulted in the highest catalytic activity. Additionally, the co-impregnation of indium and cerium resulted in enhancing the catalytic activity more than subsequential impregnation (Ni/In-CeO2/Al2O3 compared to Ni-In/CeO2/Al2O3). The addition of cerium or indium separately with nickel did not seem to affect activity since Ni/Al2O3, Ni-In/Al2O3, and Ni/CeO2/Al2O3 exhibited similar conversion values. All catalysts were stable for more than two days under DRM conditions without deactivating. Therefore, deactivation behaviors of the catalysts were not covered in this study.
274

Preactivated Thiomer Mucoadhesive Micelles for Anterior Ophthalmic Drug Delivery

Goostrey, Taylor January 2021 (has links)
Effective delivery of drugs to the anterior segment of the eye is notoriously inefficient due to the anatomical barriers in place. Topical administration is the most common method of drug delivery to the anterior segment. When applied to the ocular surface, topical solutions encounter barriers such as lacrimal drainage, rapid tear turnover, and reflex blinking which result in < 5% of instilled therapeutic reaching the intended tissue. One potential method to evade some of these anatomical barriers and improve the delivery of therapeutics is the use of mucoadhesive nanoparticles. These materials are designed to encapsulate a relevant ocular therapeutic and provide a means of maintaining the vehicle on the ocular surface by adhering to the mucin layer of the tear film. To this end, the work presented herein describes the design, characterization, and testing of a novel mucoadhesive polymeric nano-micelle ocular drug delivery system. The base polymer used was selected from a system that has been previously used in the Sheardown Lab. It was composed of poly(D,L-lactide)-block-poly(methacrylic acid-co-3-(acrylamido)phenylboronic acid) (PLA-b-P(MAA-co-3-AAPBA); LMP-20). The formulation was modified to replace the 3-AAPBA monomer, which contains phenyl boronic acid as the mucoadhesive component, with a preactivated thiol monomer (pyridyl disulfide ethyl methacrylate; PDSMA) to generate a novel polymer (LMS-20) to investigate the potential for drug incorporation and mucoadhesion. Modifications of the polymer were made with small thiol molecules cysteamine (Cys; LMC-20), glutathione (GSH; LMG-20), and N-acetyl cysteine (NAC; LMA-20) with a goal of reducing cytotoxicity associated with the 2-pyridinethione leaving group. Synthesis of the PDSMA monomer, LMS-20 and LMP-20 polymers, and modified polymers LMC-20, LMG-20, and LMA-20 were confirmed by 1H NMR. LMA-20 was chosen for further examination as it contained the most relevant thiol modification for ocular applications and was capable of nanoprecipitation to form aqueous micelles with previously developed methods. Micelles were formed from LMA-20 and LMP-20, with spherical morphology as confirmed by TEM. Effective diameters of 64 ± 5 nm and 72 ± 3 nm are reported for LMA-20 and LMP-20, respectively, as confirmed by DLS. Critical micelle concentration for LMA-20 of 217 mg/L was found via a pyrene fluorescence study, significantly lower than the concentration of intended application. LMA-20 and LMP-20 are predicted to be mucoadhesive based on results of zeta-potential studies. However, oscillatory rheology studies were inconclusive based on a negative rheological synergism. LMA-20 micelles loaded with 0.16% (w/w) Cyclosporine-A were able to provide sustained release of drug up to 3 days in vitro. These results suggest the possible future use of these preactivated thiomer-based materials for the delivery of therapeutics to the anterior segment. / Thesis / Master of Applied Science (MASc)
275

Environmental Influence on the Physiological Consequences of Feeding in Rainbow Trout, ONCORHYNCHUS MYKISS

Bucking, Carol 06 1900 (has links)
Ionic and osmotic homeostasis, and the intricately linked mechanisms of acid-base balance are critical for the survival of fish. To date, the role of the gastrointestinal (GI) tract in these processes has received only limited study, and our knowledge has been gained almost exclusively through studies conducted in fasting animals. The impacts of feeding and digestion, ubiquitous processes in the natural environment, are likely to be significant but have been overlooked. The current thesis addressed these shortfalls in our current understanding. Research focused on the rainbow trout (Oncorhynchus mykiss), a euryhaline species capable of withstanding the opposing challenges of life in seawater (diffusive influx of ions and loss of water) and freshwater (diffusive loss of ions and gain of water), and concentrated on its physiological response to ingestion of a meal of commercial, dry trout food, containing concentrated salts and little water. The net absorption and secretion of ions and water was tracked in each section of the GI tract of the rainbow trout over a detailed time course using an experimental diet that contained a simple inert marker, in the presence of external freshwater or seawater. Additionally, changes in overall blood chemistry were investigated to examine changes in osmotic, ionic and acid-base regulation during digestion. Feeding in freshwater resulted in the loss of endogenous water to the GI tract during digestion. Additionally, the meal provided much needed ions to balance those lost by diffusion; indeed all of the ingested ions were assimilated along the GI tract except for sodium which was absorbed in the stomach, but secreted in the intestine such that overall sodium balance was close to zero. Feeding also created a metabolic base load (an increase in the concentration of base, or HC03- due HCl secretion into the stomach lumen) that alkalinized the blood (i.e. caused a rise in pH), a phenomenon known as an alkaline tide. The base load was subsequently removed from the blood through increasedexcretion of base to the water via the gills. In seawater, the commercial diet again provided an avenue for water loss. This was potentially deleterious to an organism already suffering from diffusive water loss to the environment. Ion absorption from the diet was negligible, except for potassium and calcium, which were readily assimilated. As in freshwater, digestion resulted in an alkaline tide, however the mechanism of acid-base homeostasis differed with the excess base likely being excreted into the intestine. In contrast to freshwater fish, the gills took up additional base from the external environment, prolonging the acid-base disturbance in seawater fish. Overall, feeding was a dynamic process with far reaching systemic physiological effects. The research described highlighted intimate interactions between the processes of feeding and digestion and ion, water and acid-base homeostasis, and elucidated mechanisms that enable fish to inhabit a wide range of environments. / Thesis / Doctor of Philosophy (PhD)
276

Evaluation of Oculus Keratograph 5M Tear Film Scans on Eyes Wearing Contact Lenses

Norris, Taylor N. 04 October 2021 (has links)
No description available.
277

The use of wet-to-dry dressings for mechanical debridement

Villa, Katherine 01 May 2013 (has links)
Clinical management of complex wounds is essential to promote wound healing. Prolonged healing time may lead to longer and more costly hospitalizations and poorer patient outcomes. The removal of nonviable, necrotic tissue via debridement is vital to the healing process. One of the most common debridement techniques, in the United States, is the use of wet-to-dry dressings. There are no defined guidelines or protocols for the timing of dressing changes and subsceequent debridement. The purpose of this study was to perform a review of literature to determine the rationale for the use of wet-to-dry dressings, explore alternative time sequences of treatment, and to identify the risks and benefits for this methodology of debridement in an adult population with acute traumas. Inclusion criteria consisted of peer reviewed, English Language, research articles published within the last 5 years (2007-2012), adults with acute wounds treated by wet-to-dry dressing debridement. This review of literature was conducted using CINAHL and MEDLINE databases using the following search terms: Wound debridement, wet-to-dry dressing', timing, sequencing, schedul', standard', debridement, acute wound', and mechanical debridement. The review of literature yielded zero results meeting the search criteria therefore, a second review of literature was performed using the same search criteria but expanded to include articles published within the past 15 years (1997 -2012). The second review of literature also yielded zero results that met the search criteria. A lack of evidence supporting the use of wet-to-dry dressings for the purpose of debridement suggests that healthcare providers are following tradition rather than evidence based practices. Nurses and healthcare providers need education on best practices in wound care to advocate for their patients to ensure the best possible outcome. Further research on wound care modalities that are clinically efficient is needed.
278

The Global Detrital Zircon Database: Quantifying the Timing and Rate of Crustal Growth

Voice, Peter James 28 May 2010 (has links)
Published detrital zircon geochronological data was compiled to form the Global Detrital Zircon Database (GDZDb). This database provides a reference block for provenance analysis by future detrital zircon geochronological studies. This project entailed three subprojects: 1. crustal growth/crustal recycling patterns, 2. a provenance study of the Triassic Dry Fork Formation of the Danville-Dan River Rift basin of Virginia and North Carolina, and 3. sample size issues in detrital zircon studies. The global detrital zircon age frequency distribution exhibits six prominent, statistically significant peaks: 3.2-3.0, 2.7-2.5, 2.0-1.7, 1.2-1.0, 0.7-0.5, and 0.3-0.1 Ga. These peaks are also observed when the data is sorted for continent of origin, the tectonic setting of the host sediment and for modern river sediments. Hf isotope model ages were also incorporated into the database where grains were dated with both U-Pb and Hf isotopes. The Hf isotope model ages suggest that the majority of detrital zircons U-Pb ages reflect crustal recycling events that generated granitic magmatism, as most grains exhibited Hf isotope ages that are much older than the corresponding U-Pb age. The Triassic Dry Fork Formation was sampled from a site in southern Virginia in the Danville-Dan River Basin. The detrital zircon age frequency distribution for this formation was strongly unimodal with a peak at 400-450 Ma and a paucity of Grenville-age zircons. Comparison of the Dry Fork sample to published east coast data and to the North American record (from the GDZDb) illustrate the unusual nature of the Dry Fork Formation sample. It is probable that older Grenville zircons were blocked from the rift valley by the rift shoulder. Using the GDZDb a study of sample size was conducted in order to estimate the best sample size to use when trying to constrain the maximum age of sedimentation of the host sediment. Rift basins and active margins exhibited smaller offsets from the youngest zircon grain age to host sediment maximum age than observed in samples from passive margins. This study recommends that at least 50 grains need to be age dated on average in order to best constrain the age of the host sediment. / Ph. D.
279

Demountable connections of reinforced concrete structures: Review and future developments

Figueira, Diogo, Ashour, Ashraf, Yildirim, Gurkan, Aldemir, A., Sahmaran, M. 08 October 2021 (has links)
Yes / In the current practice, at the end of life of a reinforced concrete structure, it is destructively demolished and the demolition waste is landfilled or recycled. This approach is clearly wasteful of energy, creating serious environmental pollution and at high cost. However, design for demountability/deconstruction (DfD) of reinforced concrete structures would facilitate the future reuse of structural elements at the end of their life, potentially achieving a significant reduction in embodied energy of structures as well as giving the clients the benefit of retaining the value of their assets. In this paper, recent research developments and practical applications of DfD of reinforced concrete structures are reviewed and key technical issues are discussed. The main focus was on connections that should be designed in such a way to allow demounting. The main achievements are outlined, for each type of dry and semi dry connections, along with the aspects that still need to be developed. It is concluded that only semi-dry connections are currently implemented but information available in the literature on dry connections between structural elements is still very scarce. The paper concludes with an outline of some future opportunities and challenges in the application of DfD in concrete construction.
280

The Effect of Irrigation on Dry-Farmed Vitis vinifera L. cv. Zinfandel as a Function of Age

Alvarez Arredondo, Jocelyn 01 June 2023 (has links) (PDF)
A one-year study was conducted in the Central Coast of California at a commercial vineyard to evaluate the effect of supplemental irrigation on dry-farmed Vitis vinifera L. cv. Zinfandel with varying vine ages during the 2021 growing season. The experimental block was historically dry-farmed on own-rooted Zinfandel vines, older vines were replaced as production quality decreased with a genetically identical scion grafted onto St. George (Vitis vinifera Scheel) rootstock. Six total treatments were included in this study, with Young vines (5 to 12 years old), Old vines (40 to 60 years old), and Control (2:1 ratio of old to young vines, and representation of the block). Each vine age treatment included both non-irrigated and irrigated vines, the total vine sample contained half irrigated and half non-irrigated. Irrigation was manually applied at véraison and véraison + 4 weeks, based on age-specific ETc, and to replenish 95% ETc. Results indicated no significant changes in phenological progression, leaf senescence, and physical berry analysis caused by supplemental irrigation during key developmental stages. Vine age was the primary driver of significant variation observed for most parameters. However, irrigated vines had slightly higher phenological progression leading up to harvest, although not statistically significant. Due to this minor trend, irrigated vines in each vine age group were harvested before the non-irrigated vines starting with young, control, and old vines. Additionally, lower leaf water potential was found at pre-dawn during the second irrigation application at véraison + 4 weeks. Applying supplemental irrigation during the growing season resulted in no significant impacts on vine performance. Results suggest the potential for implementing a dry-farmed management in vineyards to help adapt to climate changes and water scarcity issues.

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