<p> The alpha-activity of natural samarium has been studied using an ionization chamber. A gridless ionization chamber has been developed in order to obtain high resolution and high sensitivity. The half lives and the energies of the alpha decay of Sm147 and Sm148 were measured where as the alpha-activity of Sm149 and Sm146 could not be detected.</p> <p> Experiments were carried out in order to search for the existence of Particle stable neutron clusters in the range of Mass 6-10 as a component of a nuclear reactor flux and as the product of high energy proton spallation of heavy nuclei.</p> / Thesis / Doctor of Philosophy (PhD)

<p> High resolution lithium-drifted Germanium detectors have been used to study the γ radiation emitted after thermal neutron capture in ten odd-proton even-neutron nuclei in the mass range 56 ≤ A ≤ 204. From the energies and intensities of these radiations, the energy dependence of the partial radiative widths to bound states with excitation energies in the region 0 to 2.5 MeV have been deduced. The energy dependence for the average spacing between the levels populated in this reaction have also been deduced over the same region of excitation energies. The energy dependence of the partial radiative widths are in agreement with the single particle estimate for dipole radiation and the energy dependence of the average level spacing favours the constant temperature model.</p> / Thesis / Doctor of Philosophy (PhD)

The technique of recording coincidence events has been applied in the study of several nuclei. Two platinum nuclides have been investigated experimentally through the use of two types of coincidence spectrometers. For both these nuclei, Pt^192 and Pt^194, the investigation included beta-gamma experiments which measured the intensities of the beta groups feeding some of the levels in these nuclei and directional correlation experiments which determined the spins of some of their excited states. A study of the gamma-gamma coincidences of Pt^194 confirmed the decay scheme proposed by previous workers. The directional correlation of the one cascade in Co^58 forms the part of the paper present in Chapter IV. Finally, the appendices contain a description of an apparatus for the preparation of beta sources and an explanation of a set of experiments designed to calibrate the gamma-gamma coincidence spectrometer for its tasks. / Thesis / Doctor of Philosophy (PhD)

<p> The (t,p) reaction has been performed on targets of 151Sm, 176Yb and 178Hf. The experiment was performed with 15 MeV tritons. The outgoing protons were analyzed with the Enge split-pole spectrograph. Angular distributions were measured for all three nuclei with special emphasis being placed on L=0 transitions.</p> <p> The angular distributions for the 151Sm(t,p)153Sm reaction showed that the distribution of L=0 strength among the low-lying states is not consistent with expectations based on the detailed wavefunctions for 151Sm and 153Sm calculated by two independent groups; Katajanheimo and Hammaren (1978) and Rekstad et al. (1978). The distributions also showed that the total L=0 strength, summed over the four observed states in 153Sm, is much less than for neighbouring nuclei.</p> <p> Angular distributions of the (t,p) reaction on 176Yb and 178Hf targets showed strong L=0 transitions to levels at ~ 1.3 MeV excitation. It is believed that the N=108 energy gap in the Nilsson diagram is the cause of the large L=0 strength observed. At present no quanitative calculation has reproduced the observed phenomenon, however a calculation based on the Volkov model is presently being considered.</p> / Thesis / Master of Science (MSc)

<p> The alpha decay properties of nuclei decaying across the N = 126 closed neutron configuration are examined. A systematic occurrence of isomerism is esteblished in the odd-odd N = 2.27 isotones from a detailed study of 214Fr and 216Ac. Energy level spacings of the odd-odd N = 125 isotones 208Bi, 210At, and 212Fr are found to exhibit a distinct· correspondence. The Mang shell model theory of alpha decay is evoked to explain the reduced width fluctuations of the even-odd N = 127 isotones. Theoretical and experimental results are also presented for the alpha decay of 215Ra. The new isotopes 222Th , 221Th , 218Ra, and . 217R a are synthesized and studied. Precise atomic masses are calculated for several nuclei from the measurement of alpha decay Q-values. </p> / Thesis / Doctor of Philosophy (PhD)

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Suprachiasmatic nuclei (SCN) is the master circadian pacemaker that generates coordinated rhythms and drives oscillations in other peripheral tissues. Extracellular vesicles (exosomes) have been implicated in cell-to-cell communication and the regulation of circadian clock. However, mammalian clock-derived exosomes have not been characterized. This thesis examine the contents of exosome released from SCN2.2 cells in vitro using a combination of proteomics, next-generation sequencing, and bioinformatic analyses. SCN2.2 cells-derived exosomes, that carry unique microRNAs and proteins, could be taken up by fibroblast cells in vitro. Interestingly, several unique microRNAs and proteins found in SCN2.2 cells-derived exosomes have shown circadian rhythmicity in other cells. In addition, differential expressed microRNAs secreted by SCN cells were also observed outside of exosomes. Taken together, these studies demonstrate that exosomes, containing small RNAs, RNAs and proteins, are released from SCN2.2 cells and likely have a biological role in circadian regulation of metabolism in downstream cells.

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