<p>The risk of corn rootworm damage to continuously-grown corn was assessed in 32 fields from seven counties in Virginia in 1993 and 1994, Approximately 28% of the fields examined had economic root damage in corn left untreated with a soil insecticide. In addition, 19% of the fields overall had an economic loss in silage due to corn rootworm damage.</p> <p> A second study evaluated the effectiveness of using adult corn rootworm counts on commercial Olson yellow sticky traps and ear-zone regions of corn plants to predict subsequent damage to corn. Regression models for each sampling method were used to calculate economic thresholds of 20 adults per trap per wk for the Olson trap and 0.3 adults per stalk for the ear-zone visual count method. Adult counts on Olson traps obtained in mid-Aug correctly predicted economic damage to com 81% of the time; and resulted in only one serious error of failing to predict economic damage to corn. A sampling plan for the use of Olson traps is suggested.</p> <p>A third study investigated a possible sexual dimorphism in the elytra coloration pattern of western corn rootworm, and compared the sex ratio of adults captured yellow sticky traps with those obtained by aspiration. Striped and solid variations in elytra pattern were found in both sexes of western corn rootworm; however, 98% of the adults that exhibited the solid elytra pattern were male. The sex ratio of adults varied over time; however, in all cases, sticky traps captured a significantly greater proportion of males compared with aspiration.</p> / Master of Science

Master of Science

Master of Science

The purpose of this project is to create a comprehensive sport marketing plan for the HBCU Basketball Tournament at Virginia State University. / Master of Science

No description available.

It is observed for the first time that telechelic ionomers based on sulfonated polyisobutylene exhibit primary and secondary SAXS peaks when the molecular weight distribution is narrow (Mw/Mn ca. 1.15). These SAXS peaks are interpreted as due to non-global lamellar or cylindrical ionic domain order. The non-global ordering strongly affects the tensile and dynamic mechanical properties of the ionomer. This effect is attributed to local ionic phase continuity and the concept of restriction of chain motion by the ionic domain. Triblock copolymer ionomers from t-butyl methacrylate (tBMA) end blocks and polybutadiene or tapered poly(styrenelbutadienel styrene) (tSBS) mid blocks exhibit complex SAXS patterns indicating dispersed spheroidal ionic end block domains in the matrix. TEM shows that ionization of the 9 mol % PtBMA-PBD triblock produces a morphological transformation from unoriented rodlike domains to ionic spheroids. / Ph. D.

Bisphenol A polycarbonate is an engineering thermosplastic which can be utilized for a variety of applications. Modifications to improve upon the properties of this useful material have been attempted since its invention. Three modifications of bisphenol A polycarbonate and its copolymers have been examined in this work. The hydrolytic stability of copolymers of polydimethylsiloxane and polycarbonate was improved by the synthesis of pre-formed phenol functional polydimethylsiloxane oligomers in which the Si is attached directly to the aromatic ring of the hydroxyaryl functional component. <i>In situ</i> random block copolymers of polydimethylsiloxane and polycarbonate were synthesized by interfacial polymerization techniques. The Si-aryl bonds of the novel polydimethylsiloxane oligomers were found to impart good thermal and hydrolytiC stability to the random block copolymers. Terminally reactive polycarbonate oligomers were also synthesized in order to form polycarbonate network materials. 4-Acetoxystyrene was utilized as a stable precursor to 4-vinylphenol which could then be used to quantitatvely control the molecular weight and functionality of the polycarbonate chains. The reactive oligomers were found to undergo a thermal cure above the respective glass transition temperatures to form insoluble networks. These network materials were found to have superior solvent resistance as compared to the linear material while retaining much of the useful mechanical properties (high fracture toughness, etc.) of bisphenol A polycarbonate. Furthermore, the glass transition temperatures of the networks were found to increase with a decrease in the molecular weight between crosslinks. The fire resistance properties of polycarbonate were modified by the copolymerization of bisphenol A with phenol derivatives of triphenylphosphine oxide. The effect of changes in the composition were determined by differential scanning calorimetry and thermogravimetric analysis. The glass transition temperature, as well as the residual char yield at elevated temperatures was found to increase with an increase in the phosphorus monomer content as measured by the two respective methods. Cone calorimetry was also performed on the samples to determine the heat release rate, which reflected an increase in the fire resistance properties with an increase in the phosphorus content. / Ph. D.

Wetland acreage in Southwest Virginia has increased because of formation of wetlands on relic surface mine benches. Prior to the Surface Mining Control and Reclamation Act of 1977 (PL 95-87) once mining operations were completed the sites were abandoned. These areas presented novel landscapes in the rugged Allegheny Plateau physiographic region. Specifically, flat, compacted areas were created. In microdepression of these sites wetlands have formed. This study investigates the macroinvertebrate community associated wetlands of relic surface mining operations. Surveys were conducted to identify what macroinvertebrates utilize these wetlands, to determine how this community was influenced by the physio-chemical characteristics of surface mine wetlands, and to develop design specifications for creating wetlands for current restoration efforts. Nine wetlands were sampled four times between July 1993 and May 1994. Seventy genera of macroinvertebrates were identified. The wetlands represented a range of physical and chemical parameters. The taxa richness appears to be related to these differences. Canonical Correspondence Analysis suggests that for the nine wetlands, the macro invertebrate taxa distribution is best explained by physical features of depth and duration of flooding, chemical parameters of iron, manganese, and sulfate concentration, and a biotic measure of plant litter biomass. The findings of this study can be applied to ecological restoration. Wetland creation can be incorporated into current surface mine reclamation projects. To maximize the macro invertebrate community of reclamation wetlands, sites must be positioned to avoid water quality problems, excavated to have a deeper portion which will remain inundated during all or most of the year, and have a gradually sloping substrate from the deepest area to the land surface. The final criteria being indirectly related to the macroinvertebrate community by influencing the macrophyte production, richness, and litter. / Master of Science

The release rates of two Pacific Biocontrol codling moth, one AgriSense grape berry moth and two Pacific Biocontrol grape berry moth dispensers were studied using gravimetric measurements. It was found that the addition of titanium dioxide to the polyethylene mixture significantly reduced the release rate of the dispenser when compared with a transparent design. The AgriSense dispenser's release rate could not be determined gravimetrically, possibly due to water absorption. The Pacific Biocontrollong life grape berry moth dispenser was more effective than the normal type. The effect of other species' sex pheromone blends and generic blends upon the mating behavior of Platynota flavedana Clemens, Platynota idaeusalis (Walker), Argyrotaenia velutinana (Walker) and Choristoneura rosaceana (Harris) was studied using small plots. It was determined that the sex pheromone blend for P. flavedanamay control populations of P. idaeusalis and that the two generic blends developed may control P. flavedana, P. idaeusalis and A. velutinana. The impact of a low spray mating disruption program upon the ground dwelling arthropods was investigated. It was determined that a low spray mating disruption program may be more compatible with populations of natural enemies. More taxa, species and individuals were present because of the absence of damaging prays. Orchard management of ground cover also seemed to play an important role in determining taxa and species present in orchards. / Master of Science

The addition of the lithium dienolate of ethyl crotonate to 2-cyclopentenone was studied to determine the stereochemical outcome of this Michael addition. Proof of the stereochemistry was provided via the unambiguous synthesis and comparison of ketone 73 from norcamphor 85. / Master of Science