The objectives of the present investigation were: (1) to explore an area, root exudation of peanuts, in which no previous work has been reported; (2) to study the effects of O₂ and CO₂ tensions, both individually and combined, on peanut root exudation; and (3) to determine quantitatively the sugars exuded from the roots of peanut plants grown under gnotobiotic conditions. Seed from the peanut plant, Arachis hypogaea, L. var. NC-2 was used, Peanut embryos, with the cotyledons removed, were surface sterilized; placed aseptically into sterile plexiglass isolator chambers; and planted in vermiculite saturated with Hoagland and Arnon nutrient solution contained within transplanting tubes. Because of slow embryo and seedling growth without the cotyledons, plants were not transplanted into 500 ml flasks until after 90 days. Three separate experiments were conducted. In all three, N₂ gas was metered to the roots of six plants in each of two isolator chambers. In addition, in the first study, roots of six plants in each of two isolator chambers received a gas mixture composed of 21% O₂, 10% CO₂, and 69% N₂; in the second study, they received a gas mixture composed of 21% O₂ and 79% N₂; and in the third study, they received a gas mixture composed of 10% CO₂ and 90% N₂. Duration of each experiment was 6 wks. Samples consisting of nutrient solution containing peanut root exudates from three plants were collected every 2 wks. Peanut plants were harvested and fresh weights, dry weights, and lengths of both shoots and roots (separate) were obtained. Root exudate analysis consisted of filtration to remove insoluble materials, flash evaporation to reduce the volume, salt removal by cation and anion exchange resins, freeze-drying, thin-layer chromatography to separate and identify the various sugars, and densitometry to obtain the quantity of each sugar. Analysis of variance showed for all adjusted harvest valves no significant difference as a result of treatment or replication at the 5% level. For all measured growth parameters, Duncan's multiple range test showed no significant differences within replicates caused by treatment. Five sugars, galactose; mannose; xylose; ribose; and dihydroxyacetone, were identified in peanut root exudates. Galactose was present in all 72 root exudate samples, dihydroxyacetone in 69, ribose in 33, mannose in 8, and xylose in 5. Analysis of variance showed a significant difference at the 20% level in the total amount of galactose exuded as a result of treatment and a significant difference at the 25% level in the amount of galactose exuded as a result of plant age. These results are indicative of consistent trends which need further investigation. Duncan's multiple range test showed an interaction between treatment and time which was significant at the 5% level. Young plants (2 wks old) showed a significantly greater amount of galactose exuded under aerobic conditions. As the plants matured (4 and 6 wks old) there was a trend toward greater amounts of galactose exuded under anaerobic conditions than under aerobic. Analysis of variance showed no significant differences at the 25% level in the total amounts of dihydroxyacetone exuded as a result of treatment and no significant difference at the 25% level in the amounts of dihydroxyacetone exuded as a result of plant age. These results are indicative of consistent trends which need further investigation. Duncan's multiple range test showed in young plants (2 wks old) a Significantly greater amount of dihydroxyacetone exuded under aerobic conditions at the 5% level. As the plants matured (4 and 6 wks old) there was a trend toward greater amounts of dihydroxyacetone exuded under anaerobic than under aerobic conditions. / Ph. D.

The space industry has the ever increasing problem of the optimal utilization of all the volume inside the various spacecraft. Nearly every present day missile has an inertial guidance system which uses permanent magnet motors to compensate for friction loss in the moving parts. Since the space available for these motors is limited, the motor designer must obtain a design which will supply maximum torque for the available power input. The designer must determine the optimum rotor outside diameter, magnet size, rotor stack length, slot size, and all other internal dimensions of the motor. Economics dictate that the engineer may work on a design for a given time only. At the end of this time he is forced to use his best design, without knowing whether it is the best one possible. This investigation consists of the derivation of design equations for a permanent magnet direct current motor. The design procedure is programmed into a digital computer. The performance characteristics of each possible design, within practical limits, is calculated using an iteration process. The calculated performance data is compared with the actual test values from a similar motor. / M.S.

Sufficient and balanced pools of deoxyribonucleotide triphophates (dNTPs) is crucial for high-fidelity DNA replication as well as correct DNA repair. The enzyme RiboNucleotide Reductase (RNR) catalyses NDP to dNDP and is therefore an essential enzyme by providing the “building blocks” to the cells. dNTPs production needs to be tightly regulated in order to minimize mutation frequencies and prevent genome instability. RNR in S. pombe is composed of two proteins, Cdc22R1 and Suc22R2, and has been described as a heterotetramer with a dimer of each subunit: the big subunit Cdc22R1 and the small subunit Suc22R2. S. pombe also posseses an RNR inhibitor: Spd1, as well as a second RNR regulator Spd2 which has been newly discovered. Spd1 has been demonstrated to inhibit RNR and to regulate its activity throughout the cell cycle. The detailed mechanism of the RNR regulation during the cell cycle or after DNA damage is not entirely clear, as are the means of inhibition by Spd1. In order to shed some light on the RNR complex and its regulation, we used various microscopybased methods to study RNR in vivo as well as in vitro. The data of this thesis suggest there are different forms of active RNR heterocomplexes, found throughout the cell cycle in the cytoplasm as well as in the nucleus. We propose that the precise stoichiometry of subunits in the complexes may vary, or that the complex conformation may be modified in an Spd1-dependent manner. In addition, treatment of the cells with a UV mimetic agent, 4NQO, seems to promote RNR regulation in an Spd1-dependent manner. On the contrary, inhibition of RNR by HydroxyUrea (HU) affects the RNR in a possible structure-related manner, independently of Spd1 or Spd2. The in vivo observations correlate with structural and/or oligomerization modifications of the RNR, representing a novel RNR regulation in S. pombe.

The combustion of a low heating value gas in a swirl burner is investigated. The investigation covers the development of a finite difference analysis of the flow and combustion processes in such a burner. In conjunction with the analytical work, an experimental program was conducted to provide detailed measurements of the three-dimensional velocity distributions within the flow field. The dissertation emphasizes the development and solution of the mathematical model. The finite difference analysis uses the primitive variables of velocity and pressure to describe the flow field. Features of the solution algorithms of several previous authors are incorporated into the analysis. A unique feature of the current approach is the use of a non-staggered grid system. An additional feature is a very straightforward technique for handling boundary conditions which eliminates the need for special treatment of the finite difference equations at boundary points. The solution algorithm is given the acronym CENSIS, derived from CENtered-Cell-Implicitly-Staggered. To illustrate the incorporation of the algorithm into a computer code, a sample program is developed to solve a simplified problem which has a closed form solution. This program, CENCIS-T, is included. Calculations are presented for the swirl burner, and the predicted results are compared with experimental data. The program used for the calculation of swirl burner performance is a more general code called PRIMCO. The PRIMCO code includes variable density and viscosity effects and incorporates a two-equation turbulence model for the Reynolds stress terms. The PRIMCO code also uses a simplified, infinite reaction-rate combustion model. Because of the use of the non-staggered grid system, the CENCIS solution algorithm is less complicated than previous algorithms. As compared to a staggered grid system approach, the current algorithm requires approximately one- third the computations of the former approach. These advantages make this approach considerably easier to code and relatively easy to apply. / Ph. D.