Philosophiae Doctor - PhD / The demise of apartheid presented South Africa with an opportunity to rebuild itself from its painful racist past to become a home to all those who live in it. This was done through a process of nation-building, which took the form of a multicultural civic nation, affectionately known as the Rainbow Nation, that embraces diverse cultures while affirming that individual citizens have equal rights. This thesis argues that the building of the Rainbow Nation has been somewhat successful, but more on a symbolic than institutional level, and that enduring forms of racial exclusion from socio-economic well-being pose the greatest threat to constructing a united, multicultural nation of civic equals.

The diploma thesis deals with post-polymerization hydroxylation of polypropylene in solid state. Regarding the literature review, polypropylene was hydroxylated by radical grafting in aqueous solution of potassium persulfate at 100 °C, under nitrogen atmosphere for 60 minutes. Hydroxylation of polypropylene was performed at different concentrations of potassium persulfate (1; 5; 10 mol. %) and two different water/potassium persulfate molar ratios. The effects of reaction system composition and reaction conditions on reaction efficiency, extent of side reactions, thermal and rheological properties of hydroxylated polypropylene were evaluated. The presence and concentration of hydroxyl groups on polypropylene surface was determined by structural analysis (FTIR, XPS), while the highest efficiency was achieved in the presence of nonionic wetting agents, using 10 mol. % potassium persulfate and at lower water/potassium persulfate molar ratio. Based on changes in polypropylene structure, the modification took place mainly in the amorphous phase of the polymer. In addition to hydroxylation, concurrent side reactions have been reported, in particular the oxidation of wetting agents and polypropylene, which has resulted in chain cleavage, reducing the average molecular weight of the polypropylene.

Les O-glycoconjugués et les dérivés glycosidiques sont des composés naturels impliqués dans de nombreux processus biologiques. Cependant, leurs propriétés sont grevées par la médiocre stabilité in vivo de la liaison osidique. Il est donc intéressant de développer des mimes non hydrolysables. Nous nous sommes intéressés au remplacement de l’oxygène intracyclique par un groupement gem-difluorométhylène.La synthèse d’analogues difluorocarbocycliques de 5-désoxypentofuranoses et de 1-amino-5-désoxypentofuranoses a été décrite. La synthèse comporte une addition dePhSeCF2TMS sur des aldéhydes dérivés de sucres ou sur les tert-butanesulfinylimines correspondantes, suivie d’une cyclisation radicalaire. La diastéréosélectivité de ces deux étapes-clés a été étudiée, puis cette stratégie de synthèse a été appliquée à la synthèse deCF2-carbasucres, notamment l’analogue CF2-carbocyclique du D-arabinose. / O-Glycoconjugates and carbohydrate-based molecules are natural compoundsimplied in many biological processes. However, their properties are burdened by the low invivo stability of the osidic bond. It is thus interesting to develop non hydrolyzable mimetics.We were interested in the replacement of the intracyclic oxygen by a gem-difluoromethylenegroup.The synthesis of difluorinated carbocyclic analogues of 5-deoxypentofuranoses and1-amino-5-deoxypentofuranoses is described. The sequence involves an addition ofPhSeCF2TMS to carbohydrate-derived aldehydes or their corresponding tertbutanesulfinyliminesfollowed by a radical cyclization. The stereochemical outcome of these two key steps was studied, and then this strategy was applied to CF2-carbasugars, inparticular of the CF2-carbocyclic analogue of D-arabinose.

archives@tulane.edu / This dissertation is dedicated to the study of the synthesis, crystal structures, properties, and reactivity of heteroleptic metallodithiolene complexes of the Group 10 metals. In this work, we report a systematic survey of the reactivity of [(Ph2C2S2)2M] (M = Ni, Pd, Pt) toward ligand substitution. The upshots of the survey are the clarification of the attributes of the incoming ligand that facilitate ligand displacement, creation of a new set of heteroleptic dithiolene complexes, [M(Ph2C2S2)(C≡NR)2] (M = Ni, Pd, Pt; R = Me, Bn, Cy, tBu, 1-Adamantyl, Ph), and improvement in the efficiency by which mixed-ligand “push-pull” compounds are made. The scope of dithiolene ligand displacement by incoming ligands was expanded beyond the already reported phosphine and diimine ligands. Spectroscopic and physical characterization techniques including S K-edge X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) were used in conjunction with DFT computational methods to establish the properties of the compounds prepared in this study. Representative [(Ph2C2S2)Pt(C≡NR)2] (R = aryl) complexes exihibited low temperature luminscence in frozen solvent glasses with relatively long lifetimes. The relevance of the dithiolene redox non-innocence in the ligand substitution mechanism has also been elucidated, thereby giving an insight into the fate of the displaced dithiolene ligand. Redox disproportionation between two radical monoanionic dithiolene ligands leads to the creation of a dithione, which is an enhanced leaving group and an inherently reactive species. When displacement of dithiolene ligand from [(Ph2C2S2)2Ni] was conducted with a twofold excess of C≡NCy, 4,5-diphenyl-1,3-dithiol-2-cyclohexylimine could be isolated. The identification and characterization of this compound is consistent with the creation of dithiobenzil during the ligand substitution. The reactive α-dithione is also capable of undergoing rapid irreversible polymerization, thereby providing the thermodynamic impetus for the dithiolene ligand substitution. Chemical oxidation of [Pt(Ph2C2S2)(C≡NtBu)2] with [N(C6H4Br-4)3][SbCl6] was undertaken to form [Pt(Ph2C2SˉS‧)(C≡NtBu)2]2[SbCl6]2. Structural determination of the dication revealed appreciable shortening and lengthening of C─S and C─C bond distances, respectively, within the dithiolene ligand as compared to the charge-neutral complex, an observation which confirmed the dithiolene ligand as the locus of the redox activity in the heteroleptic monodithiolene complexes. The utility of [M(Ph2C2S2)(C≡NMe)2] (M= Ni, Pd, Pt) as synthons in their own right for heteroleptic compounds not directly attainable by ligand substitution from [M(Ph2C2S2)2] was also explored. The panorama of outcomes when [M(S2C2Ph2)(CNMe)2] (M = Ni2+, Pd2+, Pt2+) are introduced to new ligands intended to substitute for CNMe has been thoroughly defined. The most significant breakthrough was the isolation of the dicyanide complex, [Et4N]2[Ni(S2C2Ph2)(C≡N)2], which is a potentially useful precursor toward cyanide-bridged multimetallic architectures. Finally, the synthesis and structural characterization of multimetallic complexes bridged by bis(diphenylphosphine) ligands and redox active dithiolenes as end capping ligands are described. The electrochemistry study revealed that the dimetallic compounds support reversible oxidation to dications, which likely have singlet diradical - triplet states in close equilibrium. The use of dithiolene ligands as electron spin hosts offers new possibilities for the application of metallodithiolene complexes in molecule-based spintronic devices, such as quantum bits (qubits). / 1 / Antony Obanda

The commercial field of radical polymerized polymers, such as polyvinyl alcohol, is very broad partly because they are easy to polymerize and cheap. One aspect that could improve their commercial range is to enhance their degradation rate. As the environmental aspect of polymers grows bigger an enhancement of biological degradation is a great improvement. This thesis deals with the prospect of polymerizing polyvinyl alcohol with degradable linkages in the main chain. In order to achieve the aim the monomer 2-methylene-1,3-dioxepane is successfully synthesized and characterized. The synthesis is followed by copolymerization of 2-methylene-1,3-dioxepane with vinylacetate at the feed compositions; 30/70, 50/50, 70/30 mol% respectively. The copolymerization was successful and reached over 90% conversion at the reaction time 3-4 hours with the conditions 60°C and 5mol% 2,2-Azobis(2-methylpropionitrile) as initiator. The copolymerization is followed by hydrolysis with potassium hydroxide or Candida Rugosa Lipase. The results show that chain scission occurs when the polymer is hydrolyzed by potassium hydroxide but not by lipase. There is also a tendency toward hydrolysis of the chain with lipase.

No description available.

Cerium oxide nanoparticles (nanoceria) have recently been shown to protect cells against oxidative stress in both cell culture and animal models. Nanoceria has been shown to exhibit superoxide dismutase (SOD) activity using a ferricytochrome C assay, and this mimetic activity that has been postulated to be responsible for cellular protection by nanoceria. The nature of nanoceria's antioxidant properties, specifically what physical characteristics make nanoceria effective at scavenging superoxide anion, is poorly understood. In this study electron paramagnetic resonance (EPR) analysis confirms the reactivity of nanoceria as an SOD mimetic. X-ray photoelectron spectroscopy (XPS) and UV-visible analyses of nanoceria treated with hydrogen peroxide demonstrate that a decrease in the Ce 3+/4+ ratio correlates directly with a loss of SOD mimetic activity. These results strongly suggest that the surface oxidation state of nanoceria plays an integral role in the SOD mimetic activity of nanoceria and that ability of nanoceria to scavenge superoxide is directly related to cerium(III) concentrations at the surface of the particle.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23226号 / 工博第4870号 / 新制||工||1760(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 大内 誠, 教授 秋吉 一成, 教授 田中 一生 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23228号 / 工博第4872号 / 新制||工||1760(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 山子 茂, 教授 大内 誠, 教授 中村 正治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

As the speed of change is increasing, it’s of great importance that manufacturing companies strive to achieve not only incremental improvements, but also radical improvements within their production systems. Thus, more research has to be focused on how to realize radical improvement. In accordance, the objective of the licentiate thesis is to, through theoretical and empirical work, increase the understanding about radical improvement in production and identify what elements need to be considered when designing support on how to implement radical improvement in industrial production. Throughout the research process these issues has been addressed through theoretical and empirical studies. Three studies have been conducted in total, of which two are mainly of theoretical character and one of empirical character. Besides, a state-of-the-art theoretical review has been carried out as well, further framing the findings. The research results imply that radical improvement in production is a teamwork process that embraces the facilitation of creativity and innovation. The research further implies that there are a number of issues to consider when creating industry-applicable support on how to realize radical improvement in industrial production. For instance, what level of innovation is striven for must be decided, creativity must be facilitated throughout, the opposing cultures of incremental and radical innovation must be managed, and there is a need to apply a holistic perspective, thus embracing not only productivity results but organizational learning as well. As further work, creating industry-applicable support on how to realize radical improvement in industrial production is advocated, focusing not only on meeting the issues addressed above, but also how to make the support industry-applicable. / Kaikakuprojektet / INNOFACTURE - innovative manufacturing development