A study of ground state binding energy values listed in the Atomic Mass Evaluation 2012 (AME2012) using an interpretive approach, as opposed to the exploratory methods of previous models, is presented. This model is based on a postulate requiring all protons to pair with available neutrons to form bound alpha clusters as the ground state for anN = Z core upon which excess neutrons are added. For each core, the trend of the binding energy as a function of excess neutrons in the isotopic chain can be fit with a three-term quadratic function. The quadratic parameter reveals a smooth decaying exponential function. By re-envisioning the determination of mass excess, the constant-term fit parameters, representing N = Z nuclei, reveal a near-symmetry around Z = 50. The linear fit parameters exhibit trends which are linear functions of core size. A neutron drip-line prediction is compared against current models. By considering the possibility of an alpha-cluster core, a new ground-state structure grouping scheme is presented; nucleon-nucleon pairing is shown to have a greater role in level filling. This model, referred to as the Alpha-Deuteron-Neutron Model, yields promising first results when considering root-mean-square variances from the AME2012. The beta-decay of the neutron-rich isotope 74Cu has been studied using three highpurity Germanium clover detectors at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. A high-resolution mass separator greatly improved the purity of the 74Cu beam by removing isobaric contaminants, thus allowing decay through its isobar chain to the stable 74Ge at the center of the LeRIBSS detector array without any decay chain member dominating. Using coincidence gating techniques, 121 gamma-rays associated with 74Cu were isolated from the collective singles spectrum. Eighty-seven of these were placed in an expanded level scheme, and updated betaeeding level intensities and log(ft) values are presented based on multiple newly-placed excited states up to 6.8 MeV. The progression of simulated Total Absorption gamma-ray Spectroscopy (TAGS) based on known levels and beta feeding values from previous measurements to this evaluation are presented and demonstrate the need for a TAGS measurement of this isotope to gain a more complete understanding of its decay scheme.

Previously developed Zn decay schemes were limited by a number of factors including low production rates and detector efficiencies making it impossible to place weak transitions. Furthermore, most of the published results are from initial exploratory measurements while subsequent studies in this region either ignored the data obtained from the Zn decays or was not analyzed due to the focus on more exotic nuclei. In the current experiments, a nearly pure beam of the Cu isotope was provided by the Holifield Radioactive Ion Beam Facility (HRIBF) for the study of the Cu -> Zn -> Ga -> Ge β-decay chain using the Low-energy Radioactive Ion Beam Spectroscopy Station (LeRIBSS) setup. The high efficiency of the detector system along with the nearly pure primary beam allowed a detailed study of the γ-ray emission from the decay chain without any member of the decay chain being dominant. The γγ and βγ gamma coincidence data obtained from the experiment was used to develop revised decay schemes in which statistical significance for each observed coincidence peak was determined quantitatively. Presented in this work are updated and expanded decay schemes with new energy levels along with new βeeding intensities and logft values for the Zn -> Ga decays. In each of the Zn decays, a number of new energy levels and transitions have been proposed to the structure of respective Ga isotopes in addition to correcting discrepancies from previous works. The 74Zn β decay now has 29 new γ rays assigned to 74Ga in addition to previous 35 transitions (Winger et al., 1989} depopulating 19 energy states, including 7 new ones. The maximum level energy is increased from previous 1086- to 1555-keV. Similarly, the updated 75Zn decay scheme has its level energy increased from previous (Ekstrom et al., 1986) 3209- to 3924-keV, with addition of 37 new energy levels and 53 new γ rays. New decay scheme for 76Zn is established up to 2603 keV, similar to previous literature (Ekstrom et al.) with addition of 4 new energy levels and total of 5 new γ-ray transitions. In case of 77Zn decay, we proposed the decay scheme up to 3948 keV with addition of 8 new energy levels and 10 new γ-ray transitions.

The National Nuclear Data Center (NNDC) contains a compilation of information on the beta decays of Gallium isotopes. In the mass range A = 74 to 77, the Germanium daughters lie close to or at the valley of stability leading us to believe the decays would have been well studied. However, closer inspection indicates significant conflict for placement of gamma rays and energy levels between different measurements, especially for upper-lying states. Detailed beta-decay studies for the 74-77Ga isotopes were performed using a high resolution four clover Hyper-Pure Germanium (HPGe) detector system with two beta scintillators in the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Lab (ORNL) to better understand the structure of the corresponding 74-77Ge daughter nuclei. In our experiments, use of a high-resolution mass separator greatly improved the purity of the samples in comparison to previous measurements. Besides that, the efficiency of the detector system we utilized was much higher than used in previous studies. We also established a method to determine statistically significant gamma gamma coincidence relationships to add reliability to the placement of gamma rays to energy levels and avoid experimental biases. From our analysis, we have established comprehensive decay schemes for all four Germanium nuclei in this study. In most cases, we have extended the energy levels to cover more of the energy window available for beta decay. Our proposed 74Ge decay scheme contains 44 energy levels occupying up to 4.36-MeV with the placement of 99 gamma rays. Similarly, 75Ga decay scheme contains 72 gamma rays with 29 energy levels occupying up to 2.75 MeV. The 76Ga decay scheme has 49 excited states with 100 gamma rays occupying up to 4.81 MeV. And, the 77Ge decay scheme has 68 gamma rays and 34 energy levels occupying up to 3.14 MeV. Based on the expanded level schemes, betaeeding intensity and log(ft) value lower limits were calculated and attempts were made to assign the spin-parity of the observed states. The resulting level schemes were then compared with the Nushellx theoretical predictions.

Real-time RT-PCR was used to assess the effects of interspecific microbial interactions on the expression of genes associated with lignin peroxidase, manganese peroxidase and alcohol oxidase production during the wood decay process. Expression levels of genes encoding the selected lignolytic enzymes were quantitated in one-, two- and multiple-organism interaction tests with the basidiomycetes Trametes elegans, Phanerochaete chrysosporium, Gloeophyllum sepiarium and Gloeophyllum trabeum. Compression strength loss was measured for each decay sample and correlated with gene expression data for each species. Soil microflora actively producing lignolytic enzymes during wood decay were also assessed and identified using degenerative PCR coupled with denaturing gradient gel electrophoresis, cloning and cycle sequencing. Differential expression was detected in three genes in the two-organism interaction tests: manganese peroxidase in T. elegans interactions, lignin peroxidase A in P. chrysosporium interactions and alcohol oxidase in G. sepiarium interactions. A positive linear correlation was observed between lignin peroxidase A expression and compression strength loss in P. chrysosporium interactions.

The use of near infrared (NIR) spectroscopy for predicting levels of degradation in laboratory soil block tests was investigated. Calibrations were developed for mass loss, compression strength, and exposure period using data measured from the prior methods, and untreated and mathematically treated (multiplicative scatter correction and first and second derivative) NIR spectra from various spans of wavelengths by partial least squares regression. Strong correlations were obtained from each study conducted, while calibrations developed from NIR spectra from the cross-sectional face of southern yellow pine presented the strongest predictions. Of them, calibrations for mass loss resulted in the strongest predictions. Calibrations constructed from spectra obtained from the radial face of southern yellow pine also produced strong predictions, where the strongest model was for exposure period. While, calibrations developed for cottonwood presented the weakest statistics, the strongest calibration found was for exposure period.

No description available.

No description available.

No description available.

A novel synthetic methodology has been developed for attaching fluorene derivatives, containing different types of electron donating and accepting groups at the 2 and 7 positions, to gold nanoparticles of different sizes by exploiting the affinity of the thiol functional group for gold. The distance between the dye and nanoparticles was varied by introducing two alkyl chains containing different number of carbon atoms at the 9 position on the fluorene ring system. The methodology that was developed gave enough scope for performing Radiative Decay Engineering (RDE) studies, in order to investigate the impact of gold nanoparticles on the singlet oxygen quantum yields of fluorene dyes that already exhibit high singlet oxygen quantum yields as well as high two photon absorption (2PA) cross-sections. The dialkylation of the fluorene derivatives was accomplished by reacting the dye with [alpha], [omega]-dibromoalkanes containing different number of carbon atoms in a biphasic reaction mixture containing toluene and aqueous sodium hydroxide solution in the presence of tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. The bromine atom on the alkyl chains was converted to thioester by reaction with potassium thioacetate. This was followed by the hydrolysis of the thioester to form the thiol moiety. The compounds synthesized were characterized using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Functionalization of gold nanoparticles was attempted by bringing into contact a solution of the thiol compound in toluene and an aqueous gold nanoparticles solution. UV-vis absorbance spectroscopy was used to monitor the progress of the attachment. Surface Enhanced Raman Scattering (SERS) spectroscopy was used to probe the enhancement of Raman signal by the metallic nanoparticles.

It was the purpose of this investigation to study the hyperfine structure of the β-unstable isotopes of samarium using the atomic beam magnetic resonance technique. A brief review is given of the nuclear and atomic theory necessary for the interpretation of the experiments. The hyperfine interaction constants (Mc/sec) for Sm153, and the nuclear moments inferred from them, are summarized below: A1 = - 2.100(5) B1 = 289.042(4) A2 = - 2.573(6) B2 = 306.521(21) C2 = - 0.0003(9) A3 = - 3.115(4) B3 = 165.824(20) C3 = - 0.0087(12) μI = - 0.021(1) n.m. Q = 1.1(3) barns From the quadrupole moment it follows that the nuclear deformation δ = 0.25(5). The magnetic moment disagrees with the predictions of the Nilsson model for either spin 3/2 state with which the Sm153 ground state might be associated. Also determined was the spin of Sm155. The result, I = 3/2, confirms the assignment from the less direct evidence available from radioactive decay studies. The more extensive measurements necessary to determine the moments were not attempted. / Thesis / Doctor of Philosophy (PhD)