The present study examined the overjustification effect at the individual level, using a multiple-baseline design. After successfully observing the overjustification effect with at least two participants in a single subjects design, recovery to baseline evaluated, but not observed. Experiment 2 used a similar multiple-baseline procedure as Experiment 1 to evaluate an incentive contrast interpretation of the overjustification effect. Instead of manipulating external consequences, the response-produced consequences of the target behavior were manipulated. Under these conditions, an effect similar to the overjustification effect was observed with only one out of three participants when response-produced consequences were withdrawn. As a result, Experiment 2 provided limited support for the incentive contrast interpretation of the overjustification effect, which states that the effect is a result of reduction in the total amount of reinforcement, regardless of its source.

Although it is well established that exercise aids in the prevention of bone loss, heart disease, obesity, and type II diabetes, recent surveys suggest that only one quarter of Americans engage in regular physical activity. The present experiments examined one possible technique for increasing regular exercise, a technique derived from attitude representation theory (Lord & Lepper, 1999) and from McGuire and McGuires (1991) theory of directed thinking. According to attitude representation theory, when people think about any attitude object, whether it is a social group or an activity such as exercise, they activate relevant exemplars, characteristics and actions. According to the theory of directed thinking, when people think about any event, including personally relevant events such as me doing regular exercise they activate pre-event actions and post-event consequences. Pre-event actions involve actions an individual could take that would increase the probability that the event would occur. Several previous studies have shown that directing students to think about action strategies that would increase studying results in greater intentions to study. The present experiments (1 and 2) tested whether directing students to think about action strategies to exercise might increase intentions to exercise, and also increase actual exercise behavior and cardiovascular fitness. Although Experiment 1 found few effects of directed thinking, Experiment 2, which altered and improved the experimental procedures and dependent measures, found that directed thinking about self-generated action strategies can significantly increase cardiovascular fitness. Experiment 3 suggested that action strategies might be equally effective for changing attitudes toward exercise regardless of whether the strategies are self-generated or other-generated, but reasons for exercising might be effective only when they are self-generated. The results of the three experiments are discussed in terms of theoretical perspectives on attitude processes.

This study investigated the dynamics of sediment and nitrogen flux in response to storm runoff in a pre-urbanized watershed in Parker County, Texas. Marys Creek was found to be a flashy creek with unusually low runoff coefficients, suggesting a larger-than-average storage capacity of the watershed. The predominant runoff-producing mechanism was found to be a combination of Hortonian overland flow and saturation overland flow. TSS concentrations increased in response to increased discharge. However, the sediment load being transported out of this basin was found to be well below tolerable limits. NH3<sub>-N levels tended to decrease as discharge increased; whereas, NO3<sub>-N levels increased as discharge increased. Both NH3<sub>-N and NO3<sub>-N concentration levels rarely exceeded TCEQs screening level guidelines and were determined to be of no concern. The data collected in this study can be utilized to understand the long-term effects of urbanization on the water quality of the watershed.

The objective of this study is to identify the surface carbohydrates on Dreissena polymorpha egg and sperm and to analyze the role of carbohydrates during fertilization. The lectins WGA, ConA, LcH, and GSII were tested for affinity to both eggs and sperm. The surface of eggs labeled evenly with WGA, ConA, and LcH. GSII was the only lectin that did not label the egg surface. When sperm were treated with lectin WGA it labeled the entire surface, while ConA, LcH, and GSII only labeled the inner acrosomal region of acrosome reacted sperm. Therefore, GSII is the only lectin to label a carbohydrate moitey on the sperm and not on the surface of the egg suggesting N-acetyl-D-glucosamine may have a role in sperm-egg binding. When sperm pretreated with GSII was allowed to fertilize eggs a GSII patch is left on the surface. This patch corresponds to the area where the sperm binds to the egg surface. When a sperm does not fertilize the egg, it detaches from the surface with its corresponding GSII patch at approximately 15 min post insemination.

Previous research on social facilitation suggested that womens mathematics stereotype threat might be alleviated by components of the test itself (Bond, 1982). To test this hypothesis, in Experiment 1, we primed the stereotype about womens math performance, and then gave men and women a difficult math test. In one condition, the format of the math test was intended to lead participants to believe that their performance was good, and in the other condition, the format of the math test was intended to lead participants to believe their performance was poor. Stereotype threatened women who believed they performed poorly on the test actually performed no worse than stereotype threatened women who thought they performed well. In Experiment 2, we primed the stereotype about womens poor math performance, and then gave the men and women a math test. In one condition, the majority of the math items were relatively easy, with some difficult items embedded. In a second condition, the majority of the math items were difficult, including items that matched those used in the first condition. We found that stereotype threatened women performed better on the matched items embedded in an easy test, than did stereotype threatened women completing the same items embedded in a difficult test. Theoretical and practical implications of the results are discussed.

In therapeutic community models for drug treatment, individual recovery is principally structured around group meetings and positive peer influences. Research shows that asocial group members with resistant behaviors and attitudes have the potential to adversely impact the therapeutic group. To gain a better understanding of the asocial client's role in the larger treatment process, archival Texas Christian University data were used to (1) model and confirm a 2-factor solution of asociality consistent with the literature, and (2) examine the relationship between asocial clients and treatment engagement for validation of the 2-factor model. Exploratory analysis resulted in a 3-factor solution representing Behavioral Responsivity, Cognitive Distortion, and Social Disassociation dimensions. Nested ANOVA (i.e., clients nested within prison programs) demonstrated that asocial levels (low, medium, and high) predicted treatment engagement. Furthermore, comparison between asocial levels indicated that high asocial clients reported significantly lower engagement levels compared to low and medium asocial clients.

The work presented in this dissertation focus on the development of new methodologies for the preparation of organophosphorus compounds. A review of the most relevant literature in terms of the preparative methodologies and reactivity of H-phosphinic acid, phosphonic acids and phosphine-borane derivatives is provided in Chapter I. The following chapter describes the addition of hypophosphorous compounds to unsaturated substrates in the presence of metal-catalysts or radical initiators. A novel alkyne hydrophosphinylation catalyzed by nickel chloride or its hydrate, in the absence of added ligand, was discovered and explored in the synthesis of various important organophosphorus compounds. The AIBN-initiated radical addition of alkyl phosphinates to alkenes and alkynes provides alkyl-H-phosphinates in good yield and more importantly offers one of the best synthetic approach for the preparation of trans-alkenyl-phosphinates. Straightforward application to the synthesis of biologically active GABA (×-aminobutyric acid) analogs using AIBN-initiated radical hydrophosphinylation is also demonstrated. The synthesis of novel GABA analogs using methods developed in the Montchamp group and their biological evaluation is discussed in Chapter III. In Chapter IV the synthesis of a various functionalized organophosphorus compounds via organoboranes is reported. In some cases, selective migration of one group attached to boron can be observed. Phosphonite-borane complexes are introduced as novel synthons for the synthesis of phosphinic esters. The synthesis and the reactivity of these novel complexes are expanded in Chapter V.

The focus of this research was to use Positron Annihilation Spectroscopy (PAS) to investigate the response of rubber and rubber-carbon black composites subjected to different physical conditions. The work examined the effect of deforming rubber and rubber filled with carbon black. The results showed that deformation of the rubber depends on whether the sample is filled with carbon black (CB) or not. CB, we propose impedes the aligning of the rubber chains during deformation. Aging of rubber was done and natural rubber was found to exhibit reversion property of its chains from a vulcanized state to un-vulcanized gum state as opposed to synthetic rubbers. This shows how vulnerable the natural rubber chains are at high temperature. We also found that heat can induce crystallization in the rubber chain network. The most common type of rubber crystallization inducement is through strain, which has been studied in detail. In our investigation, we have found that when rubber is heated and allowed to cool slowly to room temperature, its chains can align themselves in an orderly fashion many times leading to crystal growths. Heat also favors oxidation of the rubber chains, hence causing their quick degradation We studied the effect of sulfur in the cross-linking of rubber. We found that during vulcanization, sulfur cross-links rubber chains by tying them together in a network like structure reducing the chains mobility. The work also explored the positronium formation in liquids and some common polymers then compared the results with those found from rubber. It was found that Ps formation depends on the nature of the liquid. We found that the results for rubber were similar to those of liquids and concluded that rubber behaves more like a liquid. At room temperature, rubber is far away from its glass transition temperature hence has soft and flexible chains. Ps atom can thus dig itself a cavity within the rubber chains and live longer in it. This explanation was explored through the bubble model.

The focus of this work lies on the exploitation of hypophosphorous derivatives in order to develop new methodologies for P-C bond formation as well as synthesizing biologically relevant phosphorus compounds. A review of the work published to date from the Montchamp group is provided in Chapter 1: Much of the methodology is applied in the remainder of the thesis in reactions such as radical addition, base-promoted alkylation and cross-coupling of anilinium hypophosphite. The following chapter describes initial results of the transition-metal catalyzed cross-coupling in the presence of beta-hydrogens and with chloromethylphthalimide. The application of phosphine-borane chemistry as a phosphinylidene protecting group is discussed in Chapter 3. An in-depth literature review provides the background for the new methodology. Novel gamma-aminobutyric acid analogues are synthesized using methods developed within the Montchamp group. Their synthesis and biological evaluation are discussed in the final chapter.

In this dissertation a simple route has been developed to synthesize Silicon Carbide (β-SiC) nanothreads and C-SiC coaxial nanotubes by solid/liquid-state reaction between multiwall carbon nanotubes and silicon conducted at 1473 K and 1723 K, respectively. Through the kinetics study of SiC formation from carbon nanotubes and Si, our results demonstrated that carbon nanotubes may have higher chemical reactivity than other forms of elemental Carbon. Based on the above investigation, CNT/SiC and diamond/CNT/SiC were manufactured. Key factors influencing the mechanical properties of final products, such as phase composition, grain size, stress-strain, sintering time, and sintering temperature were thoroughly studied with Raman spectroscopy, x-ray diffraction, SEM and TEM techniques. Taking advantage of high elasticity of Carbon nanotube and its ability to block the microcrack propagation and dislocation movement, both composites showed enhanced fracture toughness. Carbon nanotubes composites trigger a new field in fundamental science and manifest potential application in multiple industries.