In explosive astrophysical environments such as novae, X-ray bursters and supernovae, conditions of extreme temperature and density are achieved. Under such conditions, both the rate of energy release and path of nucleosynthesis are governed by reactions on unstable nuclei. In this light, direct reaction studies using radioactive ion beams play a vital role in determining nuclear reaction rates. However, in the vast majority of cases, direct measurements are not possible and as such, indirect measurements are equally important for the understanding of the main reaction processes driving astrophysical events. In this thesis work, indirect studies of the astrophysically important 19Ne(p,γ)20Na and 29P(p,γ)30S reactions have been performed. For the first reaction, a β-delayed proton decay study of 20Mg was performed to gain information about the spin-parity assignment of the first key resonance above the proton emission threshold in the compound nucleus 20Na. This resonance is expected to dominate the 19Ne(p,γ)20Na reaction rate in explosive astrophysical environments and its identity has been under discussion for a long time, with J π = 1+ and 3+ assignments suggested. In the present study an upper limit on the β-decay branch to this state of 0.02% with a con dence level of 90% is reported. This is signi cantly more stringent than previous studies and makes a 1+ assignment highly unlikely, favouring instead a 3+ assignment. A 3+ assignment is predicted to have a signi cantly higher resonance strength and produce a proportionately higher 19Ne(p,γ)20Na reaction rate in X-ray burst conditions. The second study performed was a detailed gamma-ray spectroscopy study of the nucleus 30S. Excitation energies have been determined with improved precision over previous studies and the first,firm spin-parity assignments of key 29P + p resonant states, expected to dominate the 29P(p,γ)30S reaction in stellar scenarios, have been made. An evaluation of the 29P(pγ)30S reaction over the temperature range T = 0.06-2.5 GK shows that the 3+ and 2+ resonant states located at Er = 292.0(9) and 413.1(10) keV, respectively, dominate the 29P(p,γ)30S reaction rate in ONe novae, while the 413 keV resonance is expected to govern the rate in X-ray burster environments. These new, precise resonance energy measurements and firm spin-parity assignments have signi cantly reduced uncertainties in the 29P(p,γ)30S reaction in ONe novae and X-ray bursters. In particular, the reaction rate is now speci ed precisely enough for calculations of isotopic abundances in ONe novae ejecta.

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English and Indian historians have devoted considerable research and analysis to the genesis of the Sepoy Mutiny of 1857 but have ignored contemporary British reaction to it, a neglect which this study attempts to satisfy.

The pyrolysis of dimethyl ether in the presence of a methane bath, over the temperature range 790-850K, follows the simplified reaction scheme numbered 1-5: CH3OCH3 CH3O + CH3 (l) CH3O + CH4 CH3OH + CH3 (2), CH3O + M CH2O + H + M (3),H + CH4H2 + CH3 (4),CH3 + CH3 C2H6 (5) Thus monitoring the level of ethane, or ethylene derived from ethane, yields a measure of the rate of dimethyl ether decomposition, (l) Results obtained from the current work, together with those of other workers obtained over a wider temperature range, yields the rate constant for reaction (l): k1 = 10l6.3 1 .3 exp-81.4 0.3 k cal mol-1. Hence a value for the heat of formation of the methoxy radical is calculated to be 4.1 kcal mol-1. However, both computer modelling of the full reaction scheme and further experimental work has highlighted the importance of sensitised decomposition reactions within this system, reactions (6), (7): CH3 + CH3OCH3 CH4 + CH2OCH3 (6), CH2OCH3 + M CH2O + CH3 (7) For the case where neat dimethyl ether is pyrolysed the reaction is dominated by sensitised decomposition. Computer modeling successfully resolved the mechanism of reaction under the experimental conditions. Attempts to obtain an experimental rate constant for the decomposition of the methoxy radical have proved unsuccessful due to the complex nature of this reaction system. This also proved to be the case where dimethyl ether-d6 acted as the precursor of methoxy-d3. The decomposition of the trifluoromethoxy radical was examined using an RRKM computer model, reconciling the calculated parameters for this radical with the pressure dependent data of Descamps and Forst. This study of the trifluoromethoxy radical yielded data which enabled application of Unimolecular Gas Kinetic Theory to the similar methoxy radical. With so few experimental data on the decomposition of the methoxy radical it was essential to reduce the number of variables prior to applying the RRKM model to this reaction (3). Formaldehyde pyrolysis in a methane bath, over the temperature range 740-910K, was examined to resolve controversy over the mode of formaldehyde decomposition: whether the reaction proceeds by a molecular elimination path, A, or via a radical chain mechanism, B. Although ethane was not observed as a principle product, computer modelling of this reaction indicated that the combination of methyl radicals was the principle termination step. To test for the participation of the molecular elimination pathway (15), the ratio CD2O + M CO + D2 + M (15) RD2/RHD was followed as a fuction of both the formaldehyde-d2 concentration and temperature. As (D) is a function of the concentration of formaldehyde-d2, an intercept will be obtained upon plotting RD2/RHD versus (CD2O)/(CH4) where the molecular elimination path participates. No evidence of the molecular elimination route was obtained. Reaction data for steps (10) and (11) were obtained together with evidence of heterogeneous reaction contributing to the rate of formaldehyde decay.

by Yun Yang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 111-118). / Acknowledgements --- p.i / Contents --- p.ii / Abstract --- p.v / List of Acronyms and Abbreviations --- p.vi / Chapter Chapter 1. --- Introduction / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Reactions of Furans / Chapter 1.2.1 --- Electrophilic Substitution --- p.3 / Chapter 1.2.2 --- Nucleophilic Substitution --- p.6 / Chapter 1.2.3 --- Addition Reaction --- p.9 / Chapter 1.2.4 --- Oxidation Reaction --- p.9 / Chapter 1.3 --- Review of Synthetic Methods for the Syntheses of Polysubstitued Furans --- p.11 / Chapter 1.3.1 --- "From 1,4-Dicarbonyl Compounds" --- p.11 / Chapter 1.3.2 --- From α-Haloketones --- p.12 / Chapter 1.3.3 --- From Hetero Diels-Alder and Retro-Diels-Alder Reactions --- p.15 / Chapter 1.3.4 --- From Alkynes / Chapter 1.3.4.1 --- Via Radical Cyclization --- p.16 / Chapter 1.3.4.2 --- Via Insertion of Isocyanides --- p.16 / Chapter 1.3.4.3 --- Via Addition of Carbenoids --- p.17 / Chapter 1.3.4.4 --- Via Pd-Catalyzed Addition and Cyclization Reactions --- p.19 / Chapter 1.3.5 --- FromAllenes / Chapter 1.3.5.1 --- Via Allenic Sulfonium Salts --- p.20 / Chapter 1.3.5.2 --- Via Rh or Ag Catalyzed Cyclization --- p.21 / Chapter 1.3.5.3 --- Via Acylium Ions Addition to Allenylsilanes --- p.21 / Chapter 1.3.5.4 --- Via Allenic Palladium Intermediates --- p.22 / Chapter 1.3.6 --- From Pyrylium Salts --- p.23 / Chapter 1.3.7 --- From Miscellaneous Sources --- p.24 / Chapter 1.4 --- "Review of Synthetic Methods for the Syntheses of 3,4-Disubstituted Furans" / Chapter 1.4.1 --- From Functionalization of Furan Ring --- p.25 / Chapter 1.4.1.1 --- "Modification of Diethyl Furan-3,4-dicarboxylate" --- p.25 / Chapter 1.4.1.2 --- Modification of 3-(Hydroxymethyl)furan --- p.27 / Chapter 1.4.1.3 --- "From Boroxines Derived from 3,4-Bis(trimethylsilyl)furan…" --- p.28 / Chapter 1.4.2 --- From Ylide --- p.29 / Chapter 1.4.3 --- "From 2-Butyne-l,4-diol" --- p.29 / Chapter 1.4.4 --- From Hetero Diels-Alder and Retro-Diels-Alder Reactions --- p.30 / Chapter 1.4.5 --- From Sulfolene --- p.31 / Chapter 1.5 --- Aim of the Present Work --- p.32 / Chapter Chapter 2. --- Results and Discussion / Chapter 2.1 --- "Synthesis of 3,4-Bis(tri-n-butylstannyl)furan (47) and 3-(Tri-n-butylstannyl)furan (48) from Bis(tri-n-butylstannyl)acetylene (49) and 4-Phenyloxazole (50)" --- p.34 / Chapter 2.2 --- Stille-type Palladium-catalyzed Cross-coupling Reactions with Various Organic Halides --- p.36 / Chapter 2.2.1 --- General Features of Stille's Reaction --- p.38 / Chapter 2.2.2 --- Solvents and Catalysts --- p.42 / Chapter 2.2.3 --- Isolation and Purification of Products --- p.45 / Chapter 2.2.4 --- Direct Coupling with Organic Halides --- p.45 / Chapter 2.2.4.1 --- Acid Chloride --- p.46 / Chapter 2.2.4.2 --- Aryl Halide --- p.51 / Chapter 2.2.4.3 --- Vinyl Halide --- p.53 / Chapter 2.2.4.4 --- Allylic Bromide --- p.53 / Chapter 2.2.4.5 --- Benzylic Halide --- p.54 / Chapter 2.2.5 --- Mechanistic Aspects / Chapter 2.2.5.1 --- Mechanism for the Stille's Reaction of Acid Chloride --- p.54 / Chapter 2.2.5.2 --- Mechanism for the Stille's Reaction of Aryl Halide --- p.56 / Chapter 2.2.6 --- Carbonylative Coupling --- p.59 / Chapter 2.2.7 --- Conclusion --- p.64 / Chapter 2.3 --- "Synthesis of Unsymmetrical 3,4-Disubstituted Furans via Lithiation of 3,4-Bis(tri-n-butylstannyl)furan (47)" / Chapter 2.3.1 --- Lithiation of Organotin Compounds: General Remarks --- p.65 / Chapter 2.3.2 --- "Lithiation of 3,4-Bis(tri-n-butylstannyl)furan (47) with n-BuLi" --- p.68 / Chapter 2.3.3 --- Trapping of 3-Lithium-4-(tri-n-butylstannyl)furan (63) with Electrophiles --- p.70 / Chapter 2.3.4 --- "Synthesis of Unsymmetrical 3,4-Disubstituted Furans from 3-Substituted-4-(tri-n-butylstannyl)furan (64) via Stille's Reactions" --- p.72 / Chapter 2.3.5 --- Conclusion --- p.75 / Chapter 2.4 --- Halogenation --- p.75 / Chapter Chapter 3. --- Application to Natural Product Synthesis / Chapter 3.1 --- "Synthesis of a Key Intermediate in the Total Synthesis of (20,S)-Camptothecin" --- p.79 / Chapter 3.2 --- Synthesis of an Analog of Lactaral --- p.80 / Experimental --- p.83 / References --- p.111 / Appendix --- p.119

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Vita. / Includes bibliographical references. / by Catherine Ann Seymour. / Ph.D.

在这篇论文中，我们考虑二维中的Gray-Scott 模型核心问题的解: / [ 附圖]. / 对于足够小的ε，我们会构造一个“多个凸 的解。这些解的“凸 会分布在一个正多边形的顶点上。在这个解的U 方向上，经过一个合适的放缩之后，它会看起来像下列方程的唯一对称解： / [ 附圖]. / 此外，我们同时也会构造单个“凸 和两个“凸 的解。 / In this thesis, we consider solutions to the core problem for Gray-Scott model in R²: / [With mathematic formula]. / We construct multi-bump solutions for this problem for all sufficiently small ε. The centers of these bumps are located at the vertices of a regular polygon, andthey resemble, after a suitable scaling in their U-coordinate, the unique radial solution of / [With mathematic formula]. / The solutions with one single bump and two bumps are also constructed. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Yip, Chit Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 45-46). / Abstracts also in Chinese. / Chapter 1 --- Introduction: Derivation of the Core Problem --- p.6 / Chapter 2 --- One-dimensional core problem --- p.12 / Chapter 3 --- Main results on two-dimensional core problem --- p.19 / Chapter 4 --- Proof of Theorem 3.1 --- p.22 / Chapter 4.1 --- Estimate for S₁({U+03A6}) --- p.24 / Chapter 4.2 --- Estimate for N₁({U+03A6}) --- p.25 / Chapter 4.3 --- Estimate for S₁({U+03A6}₁) - S₁({U+03A6}₂) --- p.26 / Chapter 4.4 --- Estimate for N₁({U+03A6}₁) - N₁({U+03A6}₂) --- p.26 / Chapter 5 --- Proof of Theorem 3.2 --- p.29 / Chapter 5.1 --- Estimate for S₂({U+03A6}) --- p.33 / Chapter 5.2 --- Estimate for N₂({U+03A6}) --- p.34 / Chapter 5.3 --- Estimate for S₂({U+03A6}₁) - S₂({U+03A6}₂) --- p.34 / Chapter 5.4 --- Estimate for N₂({U+03A6}₁) - N₂({U+03A6}₂) --- p.35 / Chapter 5.5 --- The reduced problem --- p.35 / Chapter 6 --- Proof of Theorem 3.3 --- p.40 / Chapter 6.1 --- Invariance under permutations --- p.41 / Chapter 6.2 --- Reducing number of equations for regular polygons --- p.42 / Bibliography --- p.45

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