Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (p. 135-138).

Thesis, University of Tennessee. / At head of title: Physics Division. "Date issued: Jul. 11, 1960." Includes bibliographical references.

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The use of wood-based composites has increased dramatically over the last two decades due to a number of factors. One reason is that Oriented Strand Board (OSB) is being increasingly utilized in residential applications in place of plywood. However, the use of OSB in residential construction is often limited because of its susceptibility to attack by biological pathogens such as mold and decay fungi. The environmental conditions that exist in certain use categories can be so adverse that the performance of these composites is negatively affected. This study was divided into two parts. The first phase examined the effectiveness of fungicides or combinations of fungicides (including some metal-containing preservatives) for enhancing the mold resistance of strandboard. During the second part of the study, preliminaryexperiments investigated the effectiveness of fungicides or combinations of fungicides using anagar-block test to estimate the preservative toxic threshold retention. The compatibility of the fungicide on the resin curing was studied by measuring change in the resin gelation and viscosity. After these screening experiments were completed, large size boards were prepared and mechanical and decay resistance properties were examined. It was found that mold and decay resistance properties of strandboard directly were related with the biocide type and its concentration. Greater protection of the strandboard was achieved with an increase in preservative retention levels. However, due to the relatively high cost of non-metallic (organic) preservatives, it is important to find the minimum amount of preservative that can protect the OSB against mold and decay fungi. One method of reducing the cost and increasing efficacy is to combine different fungicides to determine whether synergism exists. Even if synergism does not occur, it may reduce the overall cost by combining a less expensive biocide with a smaller amount of a more expensive biocide wheretheir biocidal efficacy complements each other. In addition, it is important to understand that high retention of preservative may also cause negative effects on the mechanical properties of strandboard. This maybe noticeable of the high retention level of the biocide when a greater negative effect on the internal bonding (IB) strength may be recorded. Lower IB strength for treated strandboard may be attributed to the formulation of chemical residue in the wood surface, which may interfere with the reaction between wood and phenol formaldehyde (PF) resin. Surface-active agents in the preservative may also cause the PF resin to over-penetrate into wood decreasing bond strength. Increasing moisture content of strands by the introduction of an emulsified aqueous biocide solution, may cause dilution of the resin, and reduced bonding. It should also be noted that high retention of preservative which cause a change in the viscosity and gelation time of PF resins would be problematic for the operation of an OSB plant. For viscosity change, it could significantly affect the flow properties of the resin on the wood furnish and its atomization as it is spraying onto the wood furnish. In addition, it may require further modification to the equipment that supplies the resin to the spray nozzle. For changes in the gelation time, this may require changes to the press time at the OSB plant. / Forestry, Faculty of / Graduate

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Radiations from Zn⁶⁵ have been studied by means of a thin lens beta ray spectrometer. A spiral baffle was used to separate positrons from negatrons. The gamma ray spectrum in the energy range above 100 kev was found to consist of one gamma ray at 1.11 mev and annihilation radiation at 0.51 mev. One positron group was found with maximum energy at 0.327 mev. No internal conversion electrons were found. A decay scheme has been proposed in which Zn⁶⁵ decays either by K-capture to a 1.11 mev excited state of Cu⁶⁵ or bypositron emission to the ground state of Cu⁶⁵. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The radiation from Zn⁶⁵ has been investigated in a thin lens beta ray spectrometer. A spiral baffle was used to discriminate between positrons and negatrons. Gamma ray energies of 1.12 and 1.4 mev have been measured as well as annihilation radiation of .51 mev. A positron end point at .32 mev has also been measured. Fairly intense internal conversion was found. A decay scheme has been proposed in which Zn⁶⁵ decays by K-capture to a 1.4 mev excited state from which it proceeds to an Intermediary state by emission of a gamma ray. The alternative positron emission is to the intermediary stage from which both paths descend to the 65 ground state of Cu⁶⁵ with the emission of a 1.1 mev gamma ray. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis contains a study of the effects of massive Dirac and Majorana neutrinos and their mixings in the e’ spectrum for the muon decay μ⁺→e⁺ v[sub=e]v[sub=μ] (v[sub=μ; sup=c]. The spectra for both polarized and unpolarized muons are given for the three-neutrino world with a single neutrino of mass in the MeV/c² range. Electron-neutrino correlations are calculated and proposed as a possible signature of Majorana neutrinos. The first-order radiative corrections to the muon decay and the radiative decay μ⁺→e⁺ v[sub=e][v=sub u] are included in this analysis for the case of a single Dirac neutrino of mass in the MeV/c² range mixing into the three-neutrino world. The method of dimensional regularization is used for the calculation of the radiative corrections. / Science, Faculty of / Physics and Astronomy, Department of / Graduate