UNT Theses and Dissertations - 9 Matching Results

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Degradation of Phenolic Acids by Azotobacter Species Isolated from Sorghum Fields

Description: Sorghum plants excrete phenolic acids which reduce subsequent crop yields. These acids accumulate in field soil by combining with soil and clay particles to form stable complexes which remain until degraded by bacterial metabolism. The amount of phenolic acids in soil samples were obtained by gas chromatography measurements, while Azotobacter populations were obtained by plate counts in 40 sorghum field samples from Denton County, Texas. One can conclude that increasing the Azotobacter populati… more
Date: August 1989
Creator: Al-Hadhrami, Mohamed N. (Mohamed Nasser)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Interactions between Carotid and Cardiopulmonary Baroreceptor Populations in Men with Varied Levels of Maximal Aerobic Power

Description: Reductions in baroreflex responsiveness have been thought to increase the prevalence of orthostatic hypotension in endurance trained athletes. To test this hypothesis, cardiovascular responses to orthostatic stress, cardiopulmonary and carotid baroreflex responsiveness, and the effect of cardiopulmonary receptor deactivation on carotid baroreflex responses were examined in 24 men categorized by maximal aerobic power (V02max) into one of three groups: high fit (HF, V0-2max=67.0±1.9 ml•kg^-1•min^… more
Date: August 1989
Creator: Pawelczyk, James A. (James Anthony)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Sediment Characteristics and Bioavailability of Sorbed Neutral Organic Compounds

Description: Several sediment characteristics were analyzed to determine their suitability for use as potential normalization factors for the bioavailability of neutral organic compounds sorbed to sediments. Percent organic carbon, cation exchange capacity and particle surface area were measured sediment characteristics that varied sufficiently to encompass the range in observed sediment toxicity. Laboratory sediment toxicity test data using fluoranthene suggest that there is no biologically significant cor… more
Date: December 1989
Creator: Suedel, Burton C. (Burton Craig)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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The Stoneflies (Plecoptera) of the Ozark and Ouachita Mountains

Description: Collections of stoneflies (Plecoptera) were made at 603 stream sites from Nov. 1983 - May 1988 in the Ozark-Ouachita Mountain region, in relation to physiographic and vegetational characteristics. Examination of approximately 9000 vials from these collections, supplemented with material from major museums and other collectors, revealed 88 stonefly species in 8 families and 24 genera. Pearson's measure of association (R) showed there was a significant association between species present and eac… more
Date: December 1989
Creator: Poulton, Barry C. (Barry Charles)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Suppression of Immune Functions by PCBs in the Earthworm Lumbricus terrestris

Description: This research is part of an effort to develop non-mammalian surrogate immunoessays with the earth worm Lumbricus terrestris to assess immunotoxic potential of xenobiotics to mammals. The objective was to determine if earthworm immunoessays, namely E- and S- rosette formation and phagocytosis, are sensitive to a known mammalian immunotoxin, the PCB Arclor 1254. Results are presented in terms of PCB exposure and tissue concentrations during uptake/depuration.
Date: May 1989
Creator: Rodriguez Grau, Jorge Luis
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Systematics of Coccidian Parasites (Apicomplexa) from Amphibians and Reptiles in Northcentral Texas

Description: Between February 1986 and October 1988, 863 amphibians and reptiles were collected in northcentral Texas and examined for coccidial parasites. Thirteen percent of amphibians <26% salamanders, 11% frogs and toads) and 28% of reptiles (54% turtles, 25% snakes) harbored 20 previously described and 16 new species of coccidia; overall prevalence of infection was 176/863 < 20%). Sixteen Ambvstoma texanum were infected with Eimeria ambystomae which represents new host and geographic locality records f… more
Date: December 1989
Creator: McAllister, Chris Thomas
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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The Teratogenic Effects of Nocodazole and Acrylamide in Mus Musculus

Description: In two separate experiments, weight adjusted doses of nocodazole and acrylamide were injected intraperitoneally at various time intervals into twelve week old female mice. Within the nocodazole experiment, the doses were injected at varying time intervals before and after mating. On day seventeen of gestation, the female mice were sacrificed and their uterine contents examined. Nocodazole induced a significant increase in reproductive pathology per total implants when administered one hour aft… more
Date: May 1989
Creator: Oliva, Jean L. (Jean Louise)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Toxicological Characterization of Trinity River Sediments

Description: Sediments in the Trinity River were chemically, physically and biologically characterized and assessed for toxicity. Laboratory bioassays were conducted to identify sediments which induced toxic responses in test organisms and to document these responses through time. Metal and organic contaminant concentrations in bottom sediments were measured. Relationships between these concentrations and biological responses observed in laboratory bioassays were determined. Toxicity identification / reduct… more
Date: December 1989
Creator: Hall, Jerry F. (Jerry Fowler)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Validation of a Coupled Herbicide Fate and Target Plant Species Effects Model

Description: A series of experiments provided data to parameterize and validate a coupled herbicide fate and target plant species effects model. This simulation model is currently designed to predict responses of water hyacinth populations to treatments of the dimethylamine formulation of 2,4- dichloro-phenoxy acetic acid (2,4-D -DMA). Experiments investigated 1) the response of water hyacinth to varying exposures of 2,4-D (DMA); 2) the role of water hyacinth density and herbicide interception in treatment … more
Date: December 1989
Creator: Clifford, Philip A. (Philip Alan)
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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