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 Collection: UNT Theses and Dissertations
Preliminary design of a cryogenic thermoelectric generator.

Preliminary design of a cryogenic thermoelectric generator.

Date: May 2007
Creator: Sivapurapu, Sai Vinay Kumar
Description: A cryogenic thermoelectric generator is proposed to increase the efficiency of a vehicle propulsion system that uses liquid nitrogen as its fuel. The proposed design captures some of the heat required for vaporizing or initial heating of the liquid nitrogen to produce electricity. The thermoelectric generator uses pressurized liquid nitrogen as its cold reservoir and ambient air as the high-temperature reservoir to generate power. This study concentrated on the selection of thermoelectric materials whose properties would result in the highest efficiency over the operating temperature range and on estimating the initial size of the generator. The preliminary selection of materials is based upon their figure of merit at the operating temperatures. The results of this preliminary design investigation of the cryogenic thermoelectric generator indicate that sufficient additional energy can be used to increase overall efficiency of the thermodynamic cycle of a vehicle propulsion system.
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A Preliminary Investigation of the Effects of Various Fertilizers on Plankton and Fish Production in Small Texas Ponds

A Preliminary Investigation of the Effects of Various Fertilizers on Plankton and Fish Production in Small Texas Ponds

Date: 1945
Creator: Sivells, Howard Carroll
Description: This problem was undertaken to determine a suitable combination of fertilizers that would increase the food in a lake, resulting in increased yield of bass and crappie.
Contributing Partner: UNT Libraries
A Preliminary Report on the Effect of Roentgen Rays on the Formed Elements of Avian Blood

A Preliminary Report on the Effect of Roentgen Rays on the Formed Elements of Avian Blood

Date: August 1954
Creator: Berger, Gillett
Description: This problem consists primarily in determining the numerical value of the leukocytes after different amounts of roentgen rays had been applied to the subjects. The Atomic Energy Commission set up a problem concerning the effects of roentgen rays on the fertility in chickens, and grants were given to two institutions to study this. The blood work in this paper was an off-shoot from one of these five fertility grants.
Contributing Partner: UNT Libraries
Preliminary Report on the Status of the Mourning Dove in Throckmorton County, Texas

Preliminary Report on the Status of the Mourning Dove in Throckmorton County, Texas

Date: August 1940
Creator: Jackson, Alfred S.
Description: This thesis presents the results of an examination conducted to determine the status of mourning doves in Throckmorton County, Texas.
Contributing Partner: UNT Libraries
A preliminary study of the effects of selective-serotonin re-uptake inhibitors (SSRIs) on central auditory processing

A preliminary study of the effects of selective-serotonin re-uptake inhibitors (SSRIs) on central auditory processing

Access: Use of this item is restricted to the UNT Community.
Date: August 2001
Creator: Bishop, Charles E.
Description: his study compared auditory behavioral and physiological measures among three subject groups: 1) Normal control subjects, 2) subjects who were on a prescribed SSRI for depression, and 3) subjects who were prescribed an SSRI for depression, but were not medicated at the time of testing. Test measures included: Standard audiological tests (audiometry and tympanometry), electrophysiological procedures for analysis of auditory- evoked brainstem and late responses, and standardized behavioral speech tests (SCAN-A, SSI, and the low predictability sentence list of the R-SPIN). Analysis of results indicated a statistically significant increase of group mean amplitude of the ABR peak V, from 15dBnSL to 55dBnSL, in the non-medicated group compared to controls. Also, the non-medicated group scored significantly less favorably than controls on the most challenging listening condition (-20 MCR) of the SSI, in the left ear. Although other test measures indicated consistent differences between these two groups, they were not, however, significant.
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A preliminary study on the effect of selective serotonin reuptake inhibitors on peripheral and lower brainstem auditory processing.

A preliminary study on the effect of selective serotonin reuptake inhibitors on peripheral and lower brainstem auditory processing.

Access: Use of this item is restricted to the UNT Community.
Date: May 2001
Creator: Carney, Lara E.
Description: This study compared auditory behavioral and physiologic measures in normal control subjects and subjects prescribed with a selective serotonin reuptake inhibitor (SSRI) who were yet to take the drug and those currently taking an SSRI. Test measures used were pure tone averages (PTA), acoustic reflex thresholds, uncomfortable loudness levels (UCL), otoacoustic emissions, masking level difference, temporal integration, amplitude resolution, and Beck Depression Inventory-II (BDI-II) scores. Results indicated that there was a significant difference in the amplitude resolution of the unmedicated group when compared to the medicated and the control group. There was also a significant positive correlation between dynamic range (difference between UCL and PTA) and amplitude resolution. The BDI-II revealed a significant difference between the scores of the unmedicated and the control group as well as the medicated and the control group. Although other test measures indicated differences between the groups, the differences were not statistically significant.
Contributing Partner: UNT Libraries
Preparation and Characterization of a Treated Montmorillonite Clay and Epoxy Nanocomposite

Preparation and Characterization of a Treated Montmorillonite Clay and Epoxy Nanocomposite

Date: December 2000
Creator: Butzloff, Peter Robert
Description: Montmorillonite reinforced polymers are a new development in the area of nanocomposite materials. Since reinforcement of epoxy is important to the development of high strength adhesives and composite matrices, the introduction of montmorillonite to epoxy is of interest. Compositional effects on epoxy reactivity, on molecular relaxation, and on mechanical properties were investigated. Change in reactivity was determined by Differential Scanning Calorimetry. Tensile properties at room temperature indicated improved modulus and retention of strength of the epoxy matrix but a decreased elongation to failure. Depression of dry nanocomposite glass transition was observed for nanocomposites beyond 5% by weight montmorillonite. Samples that were saturated with water showed lower moduli due to the epoxy matrix. The greatest moisture absorption rate was found at 7%, the least at 3%.
Contributing Partner: UNT Libraries
Preparation and characterization of praseodymium oxide films and powders.

Preparation and characterization of praseodymium oxide films and powders.

Access: Use of this item is restricted to the UNT Community.
Date: May 2004
Creator: Shang, Yajuan
Description: Nanocrystalline praseodymium oxide films have been successfully generated on stainless steel substrates. The electrochemical deposition was performed in the cathode compartment of a divided electrochemical cell with a regular three-electrode configuration. The green films obtained by electrodeposition were then annealed at high temperatures for 1-3 hours. X-ray diffraction revealed the fluorite structure of Pr6O11 and the crystallite size was calculated. X-ray photoelectron spectroscopy was employed to study the composition of the oxide films and also the oxidation state of Pr. Scanning electron microscopy was utilized to study the surface texture and microstructure of deposits. Fourier transform infrared spectrometery was used to investigate the composition of the films. The effects of different conditions on the green films were also studied such as different pH values of the electrolyte solution, different deposition modes, different supporting electrolytes and different applied current densities. Sintering experiments were conducted to investigate the properties of the green films. Praseodymium oxide powders were also successfully prepared by combining electrochemical methods with sintering processes. The praseodymium oxide powders were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The crystallite sizes of the powders were evaluated.
Contributing Partner: UNT Libraries
The preparation and characterization of thermo-sensitive colored hydrogel film and surfactant-free porous polystyrene three-dimensional network.

The preparation and characterization of thermo-sensitive colored hydrogel film and surfactant-free porous polystyrene three-dimensional network.

Date: December 2001
Creator: Zhou, Bo
Description: Polymer hydrogel films change their properties in response to environmental change. This remarkable phenomenon results in many potential applications of polymer hydrogel films. In this thesis colored thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogel film was prepared by firstly synthesizing polymer latex and secondarily crosslinking the nanoparticles and casting the polymers onto glass. The shape-memory effect has been observed when changing the environmental temperature. The temperature-dependent of turbidity of polymer hydrogel film was measured by HP UVVisible spectrophotometer. This intelligent hydrogel might be used in chemomechanical systems and separation devices as well as sensors. Polymer adsorption plays an important role in many products and processes. In this thesis, surfactant-free three-dimensional polystyrene (PS) nanoparticle network has been prepared. The infrared spectroscopy and solubility experiment are performed to prove the crosslinking mechanism, also the BET method was used to measure the adsorption and desorption of polystyrene network. The BET constant (C) is calculated (C=6.32). The chemically bonded polymer nanoparticle network might have potential applications as catalyst or used for chromatographic columns.
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Preparation of 4-Amino-3-Hydrazino-5-Methyl-s-Triazole Dihydrochloride and Condensation Products

Preparation of 4-Amino-3-Hydrazino-5-Methyl-s-Triazole Dihydrochloride and Condensation Products

Date: August 1965
Creator: Westmoreland, Thomas D.
Description: The procedure of Takimoto, Denault, and Hotta was followed in order to prepare 4-amino-3-hydrazino-5-methyl-s-triazole hydrochloride (II) and its precursor, triamino-guanidine hydrochloride (I).
Contributing Partner: UNT Libraries