As was stated before, the purpose of this problem was to find out the effect of freezing on mortar at different hours after mixing. This was a continuation of the work done by G.H. Harris in 1945. It was hoped that by using different materials, steel molds, and by molding, freezing and testing the specimens as accurately as was possible to do so with the equipment available the peculiar results obtained by Harris could either be verified or disproved. The results obtained by this problem were very irregular but did show a slight trend and did not show the great difference in strength over a short period of time as was shown by Harris’s results. To get a definite answer a large number of samples should be run for each different time of set before freezing. A large variety of materials should be used and it is also believed that test cylinders 6”x12” would give better results. / Master of Science

Call number: LD2668 .T4 1960 A44

This research is concerned with the effects of temperature and frequency on the fatigue crack propagation behaviour. The fatigue behaviour at elevated temperature has been reviewed with emphasis on the mechanisms of propagation proposed to explain the effects of temperature and frequency. The crack propagation characteristics of a single crystal superalloy have been investigated at various temperatures and frequencies. Determination of the fatigue crack propagation rates was combined with the measurement of crack tip plastic zone sizes and observation of the deformation behaviour. At elevated temperature, the fatigue crack propagation rates were determined to be dependent on the frequency of loading. At low and high crack growth rates increased crack propagation rates were associated with higher cycling frequencies. At intermediate crack growth rates, the highest propagation rates were associated with the lowest frequency. Selected area channelling pattern techniques were used to determine the plastic zone sizes and revealed that at high frequencies (>10Hz) the plastic zone sizes at elevated and ambient temperature are similar. With decreasing frequency at elevated temperature creep may lead to increased plastic zone sizes but may also affect the crack tip geometry thereby restricting further effects. At room temperature crack propagation is observed to occur by shear of the γ' precipitate on <110> {111} resulting in {111} crystallographic facets on the fracture surface. At elevated temperature (>6000 C) however, the crack growth mechanism changes and propagation takes place on {100}. Observations of the dislocation structure indicate that deformation is concentrated within the γ matrix. It is proposed that the observed crack propagation in the γ matrix on {100} arises by the constraints imposed by the surrounding γ' precipitate. A model is presented for the frequency dependence of the intermediate crack growth rate in terms of the observed strain gradients within the plastic zone and the achievement of a critical local fracture strain.

More vegetable seeds are needed for developing countries to produce more vegetables. However, high temperature in these areas limits vegetable seed production. Leaf lettuce (Lactuca sativa L.) was grown in growth chambers at 21°C and exposed to different temperatures (28, 35, 38 and 42°C) for different exposure times (1, 4 and 7 hours) when flowers were at seven stages of development near anthesis.

Digitized by Kansas Correctional Industries

Photocopy of typescript. / Digitized by Kansas Correctional Industries

The miniaturization of Microtechnology-based Energy, Chemical and Biological Systems (MECS) is made possible by the use of high aspect ratio microchannel arrays to increase the surface-area-to-volume ratio of the flow conduits within the devices, resulting in an improvement in the heat and mass transfer performance of the devices. However, advantages of the MECS concept cannot be applied to high-temperature applications (above 650��C) due to lack of high-temperature MECS devices; therefore, the development of high-temperature MECS devices is necessary to overcome this bottleneck. This dissertation involves the development of high-temperature MECS devices from a high-temperature material, nickel aluminide (NiAl). NiAl foil was synthesized from elemental nickel (Ni) and aluminum (Al) foils through a two step process--tack bonding and reactive diffusion. The elemental foils were tack bonded at 500��C, 3.9 MPa for 15 minutes. The reactive diffusion process was then performed through a heat treatment at 1000��C for a period of time corresponding to the thickness of the composite foil. The synthesized NiAl foil showed an atomic ratio of Al to Ni up to 0.96. The foil also showed a decent flatness and surface roughness. This dissertation proposes a reactive diffusion bonding as a joining technique of nickel aluminides. An investigation of bonding parameter effects on the warpage of nickel aluminide fins in the reactive diffusion bonding process was performed. Results showed that bonding time and temperature had significant effects on warpage of the fin. The fin warpage increased with the increase of bonding time and bonding temperature. Results also suggested that the bonding pressure had an effect on the fin warpage. However, chemical compositions of the fin were not significant to the warpage. This research also proposes a new fabrication procedure for producing NiAl MECS devices. NiAl foils were used as the starting material, and the reactive diffusion bonding technique was employed as the joining technique. The research outcome indicated the viability of the proposed method in fabricating NiAl MECS devices. This method achieved leak-tight devices with a reasonable fin flatness. / Graduation date: 2003

Effects of thermal and electron beam (e-beam) processing on microbial inactivation and physichochemical properties of surimi and surimi seafood were investigated. Thermal-death-time (TDT) concept was used to model Staphylococcus aureus inactivation by heat and e-beam. Gurney-Lurie charts were used to estimate temperature during thermal processing of surimi seafood. Dose mapping technique was used to estimate dose absorbed by surmi seafood during e-beam processing. The dose absorbed increased up to 2 cm and then it gradually decreased, reaching a minimum at 5 cm depth of surimi seafood. It was determined that one and two-sided e-beam can efficiently penetrate 3.3 and 8.2 cm of surimi seafood, respectively. The D-value for thermally inactivated S. aureus was 0.65, 1.53, 6.52, 49.83, and 971.54 s, at 95, 85, 75, 65, and 55°C, respectively. The D-value for S. aureus inactivated with e-beam was 0.34 kGy. The z-value for thermally inactivated S. aureus between 55-95°C was not linear. Thermal processing degraded texture and color of surimi seafood. E-beam enhanced firmness and decreased the b* value of surimi seafood. Myosin heavy chain (MHC) degraded proportionally to the e-beam dose. Actin was not affected by e-beam except treatment at 25 kGy. Hydrophobic interactions and disulfide bonds were formed in raw Alaska pollock surimi when treated with e-beam. / Graduation date: 2002

Graduation date: 1991

published_or_final_version / Dentistry / Master / Master of Philosophy