Abstract A vast majority of the studies devoted to Lithium manganese oxide deals with their electrochemical characteristics in lithium batteries. The main project of this study is to realize the structure evolution upon electrochemical cycling. The phase transformations under the charge and discharge testing are an interesting project. Nitrate or oxide precursor calcined at 800¢XC can produce single phase stoichiometric LiMn2O4. The hypo-stoichiometric compositions (xLi2O¡Ñ4MnO, x < 1) synthesized by Li-poor situation contain LiMn2O4 and Mn2O3. The hyper- stoichiometric compositions (xLi2O¡Ñ4MnO, x > 1) synthesized by Li-rich situation contain non-stoichiometric spinel LixMn2O4 (such as Li4Mn5O12 or Li2Mn4O9) and Li2MnO3. The lattice parameter of LiMn2O4 increases slightly with increase of the lithium content at x < 1 (0.823 ~ 0.824 nm), but decreases sharply for x = 1.0 ~ 1.8 (0.824 to 0.817 nm). Differential thermal analysis showed at temperature higher than 935&#x00BA;C, rocksalt phase (with tetragonal symmetry), Mn3O4 will be produced. Above 1045&#x00BA;C, the crystallite phases contain cubic LiMn2O3 spinel, tetragonal Mn3O4 and orthorhombic symmetry LiMnO2. After high temperature annealing (> 935&#x00BA;C), the residual phase is lithium-deficient structure, Mn3O4. Apparent facets with {111}, {011}, and {001} (and {113}) planes are usually observed. The LiMn2O4 crystallite appears to be a truncated cubo-octahedron. The lowest surface energy gsv for LiMn2O4 spinel is located at the {111} planes. Lamellae domain and twinned structure are usually observed in LiMn2O4 particles. The occurrence of domain boundary and twin plane are {111} mostly. Forbidden reflections {200}, {420} in the initial powder and 1/2{311} and 1/3{422} superlattice reflections occurred after charging and discharging test reveal LiMn2O4 structure is a violation of space group. [311]/[111] peak ratio in the XRD traces is increase after electrochemical cycling. Fraction of inverse phase increased upon electrochemical cycling. The results for structure evolution under charging and discharging test can be divided into two parts for reversible and irreversible. First, unit cell of cubic spinel contracted upon charging and returned to original after discharging. The lattice constant varies back and forth between 0.824 nm to 0.814 nm for cycle between 3.3 and 4.3 V. LiMn2O4 transits to Li4Mn5O12 and l-MnO2 after fully charging to 4.3 V, which then recovers to cubic spinel LixMnyO4 after discharging to 3.3 V. The structure variations in the cycle of changing and discharging are LiMn2O4 ¡V (Li4Mn5O12 + l-MnO2) ¡V LixMnyO4. And metastable circular or rectangle LiMn2O4 particles observed in the surface can be extracted and inserted Li+ ion upon charging and discharging test. This process is reversible. Second, (1) tetragonal, rhombohedral and triclinic distorted within cubic spinel particles; (2) nanoscale regions of highly disordered lattices observed; (3) amorphous film observed in the powder particle surface; (4) crystalline phase Mn2O3 increased; (5) structure collapse inside the particle and the domain boundary; (6) inverse spinel structure. The structure of LixMn2O4 had distorted upon electrochemical cycling. These results are irreversible.

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The third and final phase of the Sudbury Neutrino Observatory (SNO) experiment utilized a series of 3He proportional counters called Neutral Current Detectors (NCDs) to detect the neutrons produced by the neutral current interactions of solar neutrinos in the detector. The number of neutrons detected by the NCDs, and hence the total flux of 8B solar neutrinos, has been determined using two novel signal extraction techniques which were designed to be robust against potential unexpected behaviour in the NCD background. These techniques yield total 8B solar neutrino flux measurements of 5.04(+0.42-0.40(stat))(+/-0.28(syst))x10E6/cm2/s and (4.40 - 6.43)x10E6/cm2/s, which are in good agreement with previous SNO results and with solar model predictions, and which confirm that previous NCD analyses were not unduly affected by unexpected background behaviour. The majority of the hardware from the now-completed SNO experiment will be reused to create a new liquid scintillator based neutrino experiment called SNO+. An important part of the SNO+ physics program will be a search for neutrinoless double beta decay, carried out by dissolving 150Nd into the scintillator. The sensitivity of the SNO+ experiment to neutrinoless double beta decay has been evaluated. If loaded at 0.1% (w/w) with natural neodymium, after 1 kTa of data taking SNO+ would have a 90%C.L. sensitivity equivalent to a neutrinoless double beta decay half life of 8.0x10E24a or better 50% of the time; if the experiment were run with neodymium enriched to 50% in 150Nd this limit improves to 57x10E24a. Under a reasonable choice for the 150Nd neutrinoless double beta decay matrix element, these half lives correspond to upper limits on the effective Majorana neutrino mass of 112 meV and 42 meV, respectively. These limits are competitive with those expected from all other near-term neutrinoless double beta decay experiments. / Thesis (Ph.D, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-09-10 21:07:00.25

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This thesis is a groundwork for a search for the C-violating φ → ωγ decay and the rare ω → l+l−π0 decay with the KLOE detector. A feasibility study of the detection acceptance for the ω → π+π−π0 and ω → l+l−π0 decays produced in the e+e− → ωγISR and e+e− → ωπ0 production channels. A study of the main background to the forbidden φ decay, the e+e− → ωγISR process, is performed using a data sample with an integrated luminosity of L = 1.6 fb−1 collected by the KLOE detector at center of mass energy √s = 1019 MeV. / Walter Andersson

Nuclear precursor of mature messenger RNA (pre-mRNA) splicing is one of the most highly regulated processes in eukaryotic organisms. In addition to its role in the removal of constitutive or alternative introns present in the pre-mRNA, splicing is also highly integrated into other layers of gene expression. This study investigates the potential role of the nuclear branchpoint binding protein (BBP) outside of the pre-mRNA splicing cycle. More specifically, we were interested in the biological relevance of its association with two cytoplasmic proteins Smy2 and Syh1. Smy2 and Syh1 belong to the GYF family of poly-proline binding proteins, and their roles in cell biology have not been well elucidated. Here we report that Smy2 and Syh1 act redundantly in: (i) limiting pre-mRNA accumulation when yeast cultures reach high cell density, potentially through promoting pre-mRNA decay in the cytoplasm; (ii) restricting Ty1 retrotransposition, apparently by limiting the Ty1 transcript abundance; (iii) limiting the accumulation of BBP-associated yet intronless TDA1 mRNA. With the presence of UACUAAC motif and BBP association as common features of these Smy2/Syh1 sensitive substrates, we tested if BBP interaction is required for Smy2/Syh1 function in RNA metabolism. Interestingly, we found that deletion of BBP C-terminal region (bbp∆C), which largely reduces or abolishes its association with Smy2, does not lead to similar phenotypes as observed in smy2∆ syh1∆ deletion mutant cells. In addition, mutagenesis of the TACTAAC BBP-binding site within the TDA1 coding region does not seem to affect TDA1 mRNA abundance or its sensitivity to the smy2∆ syh1∆ deletions. Therefore, we concluded that while the two BBP-binding proteins Smy2 and Syh1 impact the levels of certain cellular RNAs, this phenomenon is not strictly dependent upon BBP-Smy2 interaction and may be independent of BBP contribution. A model is proposed for Smy2 and Syh1 function in RNA metabolism based on our observations and interactions between these proteins with other factors implicated in RNA stability or translation.

A search for B decays to quasi two-body charmless final states involving a pseudoscalar η′ meson recoiling against a K∗ vector meson is described. This thesis primarily describes the analysis of two of the six possible decay channels, with the other four channels necessarily included as the subdecay modes are combined to give an overall branching fraction measurement. The method of analysis is a multivariate maximum likelihood fit for each subdecay channel. The likelihood curves for both modes are then combined, firstly with two other charged modes to yield an overall charged result, and finally the four charged modes are combined with two neutral modes to give an overall branching fraction and significance for the decay channel B → η′K∗. All results use the full Run 1 to Run 4 datasets, comprising 210.5 fb−1 of data, equivalent to 232 million BB pairs, gathered by the BABAR detector at Stanford Linear Accelerator Center in Menlo Park, California. The measured branching fractions and upper limits at 90% confidence limit (CL) are: B(B+ → η′ηππK∗+ K+π0) < 9.5 × 10−6B(B+ → η′ργK∗+ K+π0) < 22 × 10−6.The four-mode combined fit determined the branching fraction for the decay B+ → η′K∗+: B(B+ → η′K∗+) < 7.9 × 10−6. The six-mode combined fit determined the branching fraction for the decay B → η′K∗: B(B → η′K∗) = (4.1 ± 1.0 ± 0.5) × 10−6 at a significance of 5.6 standard deviations.

Atomic lifetimes of selected levels in Neon I and Argon I were measured using a method of delayed coincidence. Pulsed rf was used to excite a discharge tube containing the neon and argon gas. The radiation emitted from the excited atoms of the gas was passed through a monochromator so only the desired wavelength would be observed. Each time an excitation pulse ended, the decay of light intensity was detected by a photomultiplier tube. By measuring the decay time of the light intensity using the delayed coincidence technique, the average lifetime of the desired level was determined. The values of lifetimes determined in this study were found to contain considerable error. Several factors contributing to these errors were thought to be the shape of the rf pulses and an effort known as cascading which was caused by the use of rf for excitation of the gas.