Thirty Bacteroides strains from the human colon were tested for ability to degrade cyclodextrins (CD). Twenty four strains were able to degrade CD. Cyclodextrinase in two of these strains B. ovatus 3524 and B. distasonis Cl8-7 has been studied. Organisms were grown on a minimal medium containing CD (0.5%), and cyclodextrinase activity was assayed by measuring the increase in reducing sugar (as glucose) when CD was incubated at 37℃ for 4 h with crude enzyme preparations. Cyclodextrinase activity was predominantly cell bound and induced in both organisms by growth on CD. Analysis via high performance liquid chromatography showed that products of CD hydrolysis by the crude enzyme preparations from the 2 strains were sharply different. B. ovatus 3524 cyclodextrinase yielded glucose only, while the B. distasonis Cl8-7 enzyme catalyzed production of a series of maltooligomers. Cyclodextrinase of both strains was stable at 4℃ for at least 48 h. B. distasonis Cl8-7 cyclodextrinase showed greater than 75% retention of activity at temperatures up to 55℃ after 48 h, whereas the B. ovatus 3524 enzyme was labile above 25℃. Optimum activity and stability of cyclodextrinase from both strains occured at pH 7.0. Salt precipitation and chromatographic methods were utilized in an attempt to purify the enzyme(s) in crude cyclodextrinase. No enzymes were purified to homogeneity, but a 15- to 17-fold increase in specific cyclodextrinase activity was obtained via hydrophobic interaction chromatography. Also, the products obtained by the action of cyclodextrinase from B. ovatus 3524 were markedly altered during purification, suggesting that the crude cyclodextrinase contains a mixture of enzymes. / M.S.

Ph. D.

Ovipositors of female leafminers were examined microscopically to locate and describe types of sensory receptors present. Two basic types were found: trichoid sensilla and basiconic sensilla. These receptors are believed to function as mechano- and chemoreceptors to evaluate the suitability of a host plant for feeding, oviposition, and subsequent larval development. Two greenhouse experiments were conducted to evaluate the effects of photoperiod and application of plant growth regulators on two factors: 1) feeding and oviposition site selection and 2) spatial distribution of feeding and oviposition sites on individual chrysanthemum plants. In the photoperiod experiment, leafminers fed and oviposited more intensely on chrysanthemums grown under short days (SD) than on plants grown under long days (LD). Densities of feeding punctures and larval mines on chrysanthemums grown under SD was positively related to leaf height on the plant, and negatively related to leaf trichome density. Spatial distribution of feeding and oviposition sites within plants under LD was variable, and no specific pattern of preference was discerned. An experiment to determine the effect of plant growth regulators on site selection by female leafminers revealed no significant differences (P > 0.05) in feeding and oviposition densities on chrysanthemums treated with plant growth regulators napthalene napthaleneacetic acid, gibberellic acid, and daminozide. / Master of Science

M.S.

M. S.

This Thesis presents the various materials that evolved while designing the lighting for the Theatre Arts - University Theatre's production of A Little Going Away Party. Through various meetings with production staff the design objectives and styles of the premiere production were established. We determined that the production was dealing with an upcoming death in a positive manner and that the production elements should reflect this. The lighting design created a coolly lit cellar that was warmed progressively to reflect the growth of one of the characters as the story developed. The design also aided in drawing the audience's focus to different areas of the stage when action and dialogue required it. / M.F.A.

Experimental, plane strain deformations of plasticene and clay multilayers containing pre-cut ramps, have generated broad, flattopped to narrow, rounded fold geometries. Initial boundary conditions, including lubrication, end effects, and the ratio of mechanical unit to overburden rigidity determine proportions of translation and amplification which operate during the development of three main and two hybrid fold forms. Each fold geometry exhibits a unique strain pattern, but generally shows highest strains on overturned limbs, and above ramp regions. Lowest strains occur in footwall layers and between ramps. During folding, strain is produced by combinations of bending, rotation, flexural slip, and flexural flow. Layer parallel shortening strain transpires primarily before fold formation above ramps. Fold forms are dictated by the sequence of mechanisms, and proportional changes in strain mechanism magnitudes. Flexural slip predominates in flat-topped forms, while flexural flow prevails in rounded forms. Bending strain is minor in all geometries. Ellipse long-axis orientations define cleavage patterns which are more complex than proposed theoretical patterns due to variations in analogue lubrication and layer anisotropy. Analogue strain patterns may have potential for use in delineating subsurface folds and their history of development. An investigation of strain and mesoscopic structure was undertaken in the Burkes Garden dome, located in the Narrows thrust sheet in southwest Virginia to delineate the dome's history of formation. The Burkes Garden dome is a broad, flat-topped structure containing two mesoscopifold sets trending N55E and N62W, subregional (N50E) and local (outlines dome shape) cleavage orientations, northwest and southeast dipping faults, and northwest and southeast verging folds. Strain values ( R = 1.1 - 1.5) are low and show little variance in the dome. Regional and mesoscopic structure, and strain values suggest dome development results from duplex formation in the Cambro-Ordovician dolomite/limestone package below the overlying Narrows thrust sheet. Duplex formation can be continued down strike by varying the number of horses and stable ramp position. Differential amounts of movement along the Saltville fault and/or lateral ramps at depth may have produced weak localized strike-parallel compression, resulting in northwest trending folds, and local cleavage orientations. Sheet lock-up probably occurred late during dome development producing northwest dipping faults, and southeast verging folds. / M.S.

Air leakage in underground mines is the most common cause of inefficient distribution of ventilating air. Depending upon various factors, more than half of the fresh air entering a mine short-circuits to the return airways before reaching the working faces. Consequently, large leakages create an additional demand for increased intake air, which substantially affects the efficiency of a mine ventilation system. In this study, two aspects of the leakage problem have been addressed. The first involved the difficulty of measuring air leakage. Air leaks are traditionally many in number and not necessarily large in quantity at any one source. Thus, the measurement of low air leakage quantities is difficult. The most sensitive, permissible, air velocity measuring equipment available can not detect the majority of air leakage. To aid in the detection of air leakage, a portable leakage measuring device was developed. A discussion concerning the device's design, practicality, laboratory results, and field testing is presented. The second area of research investigated the effect of leakage on a system's fan power consumption. A mine model was used to simulate different leakage conditions and monitor the corresponding fan power requirements. The results showed a number of very interesting trends. The model also pointed out the different variables that affect the influence of the leakage rate on the power consumption. The discussion of these findings is included. / M.S.

M.Arch.

These studies developed from Scanning Electron Microscope (SEM) observations of abrasive wear of a polymer disk sliding against metal asperity models. The investigator was unable to observe actual particle formation but did identify elastic and plastic deformation of the polymer, and a debris buildup and extrusion process occurring at the leading edge of the asperity. On the assumption that this process could lead to a surface fatigue condition, pin-on-disk wear trials were completed using a spherical steel ball sliding on polycarbonate, rigid PVC, and ultra-high molecular weight polyethylene specimens in dry and lubricated conditions. A delay in debris formation was observed in the rigid PVC and polycarbonate dry sliding trials. In each case a higher rate of friction force increase coincided with debris formation. No debris was produced in the ultra-high molecular weight polyethylene dry sliding trials, and the friction force trace was flat. An SEM analysis of the polycarbonate and rigid PVC wear tracks revealed pitting consistent with the Delamination Theory of wear. The effect of the lubricants was to significantly alter the form of the friction force traces, but not to eliminate wear in rigid PVC and polycarbonate. The results of the investigation, particularly the delay in wear debris generation, indicated that a fatigue wear mechanism appeared to exist in dry metal pin-on-polymer disk sliding systems. A qualitative wear model was developed to relate the in-situ SEM observations and the results of the pin-on-disk trials. / M.S.