M.S.

The purpose of this investigation is the application of the penetration model for gas absorption with chemical reaction in a stirred reactor and the evaluation of the parameters of the penetration model, viz. the gas-liquid interfacial area and gas-liquid particle contact time, for the different agitation intensities and gas rates. The values of these parameters for the model were determined by measuring the rates of absorption of carbon dioxide into caustic solutions and then forcing the model to give values of the parameter consistent with observed rates of absorption. The contact times and interfacial areas were determined for five agitation rates ranging from 150 revolutions of the agitator to 350 and for five gas input rates ranging from superficial gas velocities of 0.29 centimeter per second to about 1.2 centimeters per second. These parameters were evaluated for three different caustic strengths. The interfacial areas show discrepancies in values for the three different caustic strengths. These results, together with the work of an earlier investigator, seem to suggest that, for design and scale-up purposes for gas absorption in solutions, experiments be set up with the solutions of actual interest. The interfacial areas obtained correlate well] with the correlations given by Calderbank, which is based on the work of Hinze on bubble sizes in turbulent regimes. The gas-liquid particle contact times are again found to be dependent on the intensity of agitation and the gas rates. A correlation based on the theory of isotropic turbulence has been proposed and found to correlate the data well. / Ph. D.

In order to characterize peptide transport in the ovine small intestine, [14C]-glycyl-sarcosine uptake by tissue collected from five sheep was studied through the use of brush border membrane vesicles (BBMV). Preliminary experiments determined that incubation in hyaluronidase is not necessary in order to separate mucosal tissue from the basement membrane and that the stop solution used in the uptake study needed to be buffered. Uptake was examined in proximal (denoted jejunal) and distal (denoted ileal) halves of the intestine at four times (15, 30, 45, and 60 s) and at three extravesicular pH levels (6.4, 7.0, and 7.5). An intravesicular pH of 7.5 was used throughout the study. The two tissue sites differed (P < .02), with BBMV from jejunal tissue showing greater uptake than ileal. Uptake plateaued after 45 s, resulting in a quadratic (P < .005) effect of time. The effect of changes in extravesicular pH was also quadratic (P < .04), with uptake being greatest at pH 6.4, lowest at pH 7.0 and intermediate between the two at pH 7.5. Peptide uptake by sheep jejunal and ileal BBMV was demonstrated, but there was no clear evidence for increased uptake with decreasing extravesicular pH. / Master of Science

M.S.

The 18-inch coke-packed absorption tower used in this investigation was located in the Unit Operations Laboratory of the Department of Chemical Engineering, Virginia Polytechnic Institute, Blacksburg, Virginia. During the course of this work a number of changes and additions to existing equipment were made in an effort to improve the operation of the tower. Nineteen experiments, using carbon dioxide, in a flue gas mixture, as the solute and water as the solvent were made to determine some of the operating characteristics of the tower. A new gas sealer was designed and constructed using a spiral cooling unit made from 5-inch stove pipe elbows. The elbows were coated with silicone resin in an effort to reduce corrosion. The capacity of this unit was approximately 50% greater than the open-spray type sealer used previously. The examinator used heretofore to measure gas velocities through the tower was replaced by a pitot tube and draft gage in an effort to facilitate this determination. A Precision Mine-Air model Great apparatus was installed to replace the Technical flue-gas model used in previous experimental work. Gas samples were taken for analysis by means of gas sampling bottles which permitted the use of short sampling tubes. These two changes in equipment and procedure greatly simplified the accurate determination of CO₂ in the gas stream. Orifices, metering central valves, and manometers were installed in all pipe lines conveying materials to the tower in order to increase the ease and accuracy of controlling the flow of these various materials. After the above changes had been completed, a series of nineteen test runs was made. As a result of the data collected the following conclusions were drawn: 1. The relation between the overall liquid film coefficient (K_LA); the solvent rate (L¹), and the partial pressure (P) of the CO₂ in the gas stream may be expressed by the equation Log K_LA= L¹/7.966-0.544L¹ + 0.000242 P within the limits as listed below: a. Gas velocity…..12.7 lb. mols air/hr./sq.ft. b. Solvent rate…..65 to 115 lb. mols water/hr./sq.ft. c. Partial pres. of CO₂…..37 to 90 mm. Hg. d. Temperature of water…..53.5 to 65.7°F. e. Temperature of gas…..56 to 85°F. 2. No correlation could be made between the overall liquid film coefficient (K_LA) and the pressure drop (ΔP) through the packed section of the tower. 3. The flue gas cooler which was designed and built during the course of this investigation (See Figure 3, page 38) is capable of cooling 650 lb./hr. of dry air from approximately 700°F to 70°F using 15,000 lb./hr. of cooling water at an inlet temperature of 58°F. / Master of Science

Optimum feed ration was determined for riffleshell mussels (Epioblasma spp.) held in captivity. Mussels were fed one of four rations (0.49, 0.72, 1.28, or 1.73 mg dry wt/l) of algae Neochloris oleoabundans for 2-h trials in spring, summer, fall, and winter. The test ration resulting in the most feed absorbed per hour (net absorption rate, mg/h) was determined to be the optimum feed ration. Mussels absorbed the greatest amount of food when fed the highest ration. Suggested feed rations for captive adult Epioblasma species are 1.73 mg/l when held at moderate temperatures (i.e., 15-19C), and 1.28 mg/l when held at cool temperatures (i.e., near 11C). Seasonal utilization of protein by oyster mussel (E. capsaeformis) and rainbow mussel (V. iris) was examined with O:N ratios. Ratios were determined for mussels fed a low or high-protein diet (0.11, or 0.31 mg protein/mg dry algal feed), and for mussels held in a hatchery or in the Clinch River, in spring, summer, and winter. Significant differences in O:N ratios were not observed between mussels fed a low or high-protein diet (p > 0.05). The O:N ratios were significantly highest in spring and summer, and lowest in winter (p < 0.05). Mussels primarily utilized protein in spring and summer, and conserved protein in winter. A diet high in energy was suggested in spring and summer, and a diet high in protein was suggested in winter. / Master of Science

Perylene and perylene diimide (PDIs) are widely used for organic optical electronic materials due to their outstanding thermal stability, visible light absorption and high molar absorption coefficients. To tailor perylene and PDI’s optical and electronic properties for specific applications, molecular contortion and bay-functionalization have been proved as effective methods. In this thesis, these strategies will be applied to perylene and PDI to develop novel optical and electronic materials. In the first chapter, the molecular contortion strategy is applied to perylene to tune singlet and triplet energies and successfully turn on singlet fission in thin films of contorted perylene. Perylene does not undergo singlet fission in its planar form. The tuning of the energetics that control singlet fission through molecular contortion can be applied to a large repertoire of established molecular chromophores. In the second chapter, novel bay-functionalization reactions of PDI, which are base-assisted direct amination and N-heteroarylation, are discussed. The reactions are able to achieve up to 70% yield for mono N-heteroarylation. UV-Vis and EPR spectroscopy suggest that these reactions are mediated through PDI radical anions that are thermally induced by strong bases. An intriguing small-molecule white-light-emitter is constructed from this reaction. In the third chapter, contorting PDIs to form chiral helicenes for Chiral Induced Spin Selectivity (CISS) is discussed. CISS allows for selective transportation of one electron spin and filtration out of the other spin, exhibiting great potential applications in spintronics, spin-polarized light-emission, and spin-controlled catalysis. However, the mechanism of CISS remains unclear and it is necessary to develop a molecular system that allows for the investigation of CISS effect at the atomic level. PDI-based helicenes could be an ideal model system for the investigation of CISS effect due to their chiroptical properties. The chirality of PDI-based helicene dimers is resolved without chiral HPLC separation by converting helicene enantiomers into diastereomers, where Prep TLC is used to separate the helicene diastereomers at a relatively large scale.

Yes / The current study investigated the distribution of inorganic metals in the biggest reservoir in the neighbourhood of Misurata City, Tawargah Pond. The investigation was carried out during the topical periods of dry and wet season between August 2010 and January 2011. Levels of trace metals lead (Pb), copper (Cu), iron (Fe) and zinc (Zn)) were determined in the water samples taken. An atomic absorption spectrophotometer, Model 180-30 Hitachi, was used to determine heavy metal concentrations. The instrument was calibrated and standardized with different working standards. After making sure that the instrument was properly calibrated and results of the standard measurements were in the confidence limit, the concentration of metals in each sample was measured individually. High levels of lead and iron were found in water which indicates a possible contribution from the industrial activities and air pollution.

Vertical drop testing of transport aircraft fuselage sections indicates that the frames play a major role in the process of absorbing the impact energy in the crushing of the substructure below the main passenger deck. Hence, static tests are performed on individual circumferential frames under a radially inward load to assess their progressive failure response and energy absorption characteristics. The test articles in the first series of tests are six-foot diameter, semicircular, I-section frames fabricated from graphite-epoxy unidirectional tape. The test articles in the second series of tests are J-section frames subtending a forty-eight degree circular arc, having an inside radius of 118 inches, a depth of 4.8 inches, and manufactured by resin transfer molding into a 2x2 2D triaxial braided composite preform made of AS4 graphite yarns. Frames of both materials exhibit fractures at the pint of load application and at selected locations around the circumference, but the delamination prevalent in the tape layup frames is not evident in the textile frames. A mathematical model developed to optimize open section curved composite frames for improved energy absorption is used to redesign the I-section frames by resizing the flanges. The test results of the redesigned frames show that the mathematical model predicted the correct sequence and locations of the failure events. However, the mathematical model does not predict the magnitude of the force and displacement at the first major failure event, which maybe due to the fact that delamination is not included in the progressive failure model Tests results from two of the J-section frames are compared with a beam finite element analysis using the computer code ABAQUS. Effective elastic moduli for the textile material are obtained from the computer code TEXCAD. The ABAQUS results correlate reasonably well with the experimental results prior to the first major failure event. / Master of Science

Yes / Test results of nine recycled aggregate concretes and a control concrete using only natural aggregates are reported. The recycled aggregates used were classified into three different types according to their measured specific gravity and water absorption, namely, RG I for recycled coarse aggregate having a specific gravity of 2.53 and water absorption of 1.9%; RG III for recycled coarse aggregate having a specific gravity of 2.4 and water absorption of 6.2%; and RS II for recycled fine aggregate having a specific gravity of 2.36 and water absorption of 5.4%. The replacement levels of both recycled coarse and fine aggregates were 30, 50, and 100% in separate mixtures. Slump loss and the amount of bleeding with time were recorded for fresh concrete. Compressive and tensile strengths, moduli of rupture and elasticity, and unrestrained shrinkage strain were also measured for hardened concrete. The properties of fresh and hardened concrete tested, together with a comprehensive database reported in the literature, were evaluated with respect to the relative water absorption of aggregates combining the quality and volume of recycled aggregates used. In addition, the properties of hardened concrete with different replacement levels and quality of recycled aggregates were compared with the design equations of ACI 318-05 and empirical equations proposed by Oluokun for natural aggregate concrete, whenever possible. Test results clearly showed that the properties of fresh and hardened concrete containing recycled aggregates were dependent on the relative water absorption of aggregates. In addition, the moduli of rupture and elasticity of recycled aggregate concrete were lower than the design equations specified in ACI 318-05, when the relative water absorption of aggregates is above 2.5% and 3.0%, respectively.