Bibliography: leaves 157-174. / xx, 192 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This study examined the fate of three common sulfonylurea herbicides in highly alkaline soils through a series of laboratory and field experiments to determine if existing leaching models could be used to describe their field behaviour under Australian climatic conditions. A liquid chromatographic method was developed to simultaneously determine levels of triasulfuron, metsulfuronmethyl, and chlorsulfuron in soil and water. The investigation of base hydrolysis for the herbicides in aqueous buffer and soil solutions determined that it was unlikely to be a major loss pathway for sulfonylureas in alkaline soils. The herbicides were found to have low sorption, very little retardation and high mobility, moving at a marginally slower rate than water. Degradation did not follow first-order kinetics, but rather a two-stage process appeared to be involved. Both VARLEACH and LEACHM models predicted the measured concentration of the herbicides reasonably well in profile under low rainfall conditions but were less adequate under high rainfall. Forecasts with the LEACHP model predicted levels of the herbicides for a dominant soil type of the cereal belt of southern Australia with median rainfall after a year. / Thesis (Ph.D.)--University of Adelaide, Dept. of Soil Science, 1999

Geopolymers are a relatively new class of material that has many broad applications, including use as a substitute for Ordinary Portland Cement (OPC), use in soil stabilisation, fire resistant panels, refractory cements, and inorganic adhesives. The synthetic alkali aluminosilicate structure of geopolymer results in a highly versatile material that can be synthesised en masse, cost competitively and from a wide varietyof aluminosilicate bearing raw materials. / Despite the commercial promise and technical viability of the technology, the fundamental understanding of the chemical structure and characteristics of geopolymeric materials, and to some degree the academic rigor of some aspects of the science related to geopolymers, leave a lot to be desired. In particular, the understanding of the effects of Si/Al ratio and alkali cation type on the molecular structure of the binder, and how these relate to the microstructure and mechanical and thermal properties are poorly understood. / The thesis explores the structure and characteristics of a systematic multi-dimensional matrix of geopolymers derived from metakaolin, a relatively pure aluminosilicate source. The thesis addresses the determination of the core molecular structure of geopolymers by solid-state NMR spectroscopy, and how this is altered by the nominal Si/Al ratio and alkali cation type. The chemical ordering is observed to reduce with Si/Al ratio and with inclusion of potassium over sodium. Most significantly, the presence of Al-O-Al linkages is identified for the first time in specimens with Si/Al ratios close to unity, by the application of 17O NMR techniques on geopolymers. The role of molecular structure and gel chemistry of geopolymers is elucidated, and links are drawn to understand the development of the microstructure and physical properties of the material. The thermal evolution of geopolymeric gels derived from metakaolin is investigated in terms of physical and structural development when exposed to temperatures up to 1000°C. The response of geopolymers to heating is characterised into four regions regardless of the extent of shrinkage or crystallisation. Several critical material performance relationships exist that are related to both the microstructure and chemical composition. / The thesis presents an updated structural model of geopolymers to include new insights obtained from application of solid-state NMR techniques and thermal analysis. The improvements in structural understanding described in the thesis have the potential to affect all aspects of geopolymer science.

Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1998. / Copies of author's previously published articles inserted. Includes bibliographical references (leaves 195-230).

Thesis (M.Sc.) - Carleton University, 2004. / Includes bibliographical references. Also available in electronic format on the Internet.

Thesis (Ph.D.). / Written for the Dept. of Physics. Title from title page of PDF (viewed 2009/06/08). Includes bibliographical references.

Thesis (M.A. (English))--University of Pretoria, 2006. / Includes bibliographical references.

Techn. Universiẗat, Diss., 2004--Clausthal.

Submitted by CRISTIANE QUINELATO DA SILVA null (crisquinel10@hotmail.com) on 2016-05-20T17:46:12Z No. of bitstreams: 1 Dissertação_de_Mestrado_Cristiane.pdf: 8117806 bytes, checksum: e4405ed1eaa652dce8d0815e0864e669 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-05-31T11:59:37Z (GMT) No. of bitstreams: 1 quinelato_c_me_sjrp.pdf: 8117806 bytes, checksum: e4405ed1eaa652dce8d0815e0864e669 (MD5) / Made available in DSpace on 2016-05-31T11:59:37Z (GMT). No. of bitstreams: 1 quinelato_c_me_sjrp.pdf: 8117806 bytes, checksum: e4405ed1eaa652dce8d0815e0864e669 (MD5) Previous issue date: 2016-03-21 / O Brasil é o maior produtor mundial de cana-de-açúcar, e com isso é também o maior gerador de biomassa residual – bagaço e palha. Uma grande parte dessa biomassa é utilizada na co-geração de energia, sendo queimada nas caldeiras das usinas, porém ainda há um enorme excedente, gerando problemas ambientais e sociais. Por isso, é necessário desenvolver projetos para utilização desse material, com valor agregado. Uma das maneiras é a utilização dos compostos que compõem a fibra do bagaço: celulose, hemicelulose e lignina. Para viabilizar a utilização desses compostos são necessárias técnicas pouco nocivas e com custo reduzido. Além disso, é importante que durante o processo de extração, haja pouca alteração estrutural dos compostos, ou que as alterações sofridas sejam benéficas para sua utilização posterior. O presente trabalho visou desenvolver métodos diferentes de extração de uma das frações dessa fibra, a lignina, avaliando as alterações sofridas durante os processos de extração para um posterior uso dessas ligninas de acordo com suas características. Os três métodos foram Organossolv utilizando uma mistura de dioxano e ácido clorídrico, Organossolv utilizando etanol e o Álcali. A caracterização das ligninas extraídas foi realizada através de técnicas de análise térmica (TG-DTG/DTA), microscopia eletrônica de varredura com aplicação de campo (MEV-FEG), espectroscopia de infravermelho (FTIR), e ressonância magnética nuclear (RMN). Através dos resultados obtidos nas análises evidenciou-se uma alteração maior na lignina extraída pelo método Álcali, com maiores rupturas nas ligações aromáticas durante o processo de extração quando comparado com as ligninas obtidas pelos dois métodos Organossolv. As três ligninas contêm estruturas carbônicas diferentes entre si, sendo que a que mais se aproxima da lignina de origem é a obtida pelo método Organossolv com dioxano. / Brazil is the huge producer of sugarcane worldwide, and it is also the largest residual biomass generator - bagasse and straw. A large part of this biomass is used for energy co-generation, being burnt in the boilers of the plants, but there is still a huge surplus, generating environmental and social problems. So it is necessary to develop projects to use this material with aggregate value. One way is the use of compounds that make up the fiber of bagasse: cellulose, hemicellulose and lignin. To enable the use of these compounds are required little harmful techniques and low cost. Moreover, it’s important that during the extraction process there is little structural change of the compounds or that suffered changes are beneficial for later use. This study aimed to develop different methods of extracting a fraction of this fiber, the lignin, evaluating the changes done by the extraction processes for later use these lignins according to their characteristics. The three methods were Organossolv using a mixture of dioxane and hydrochloric acid, Organossolv using ethanol and Alkali. The characterization of the extracted lignins was performed by thermal analysis techniques (TG-DTG / DTA), scanning electron microscopy with field application (SEM-FEG), infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The results obtained in the analysis revealed a greater change in the lignin extracted by the alkali method with larger breaks in aromatic bonds during the extraction process compared with the lignins obtained by the two methods Organossolv. The three lignins contain carbonic structures different from each other, and that is closest to the origin of lignin is obtained by Organossolv method with dioxane.

Nuclear magnetic resonance (NMR) spectroscopy has been extensively used to investigate numerous systems of interest, ranging from collections of molecules to living organisms. However, NMR suffers from one key drawback: an inherent lack of detection sensitivity, as compared to other common forms of spectroscopy. This is due to the minute nuclear magnetic moments and low nuclear spin polarization levels at thermal equilibrium (~10-5 to 10-6), and thus necessitates the use of relatively large sample volumes. One way to overcome this low detection sensitivity is to introduce a species with highly non-equilibrium nuclear spin polarization, such as `hyperpolarized' xenon-129. Hyperpolarized xenon can either be used as its own chemical sensor (due to its exquisitely sensitive chemical shift range), or the non-equilibrium polarization may be transferred from xenon to another molecule of interest (such as a protein or inclusion complex). Hyperpolarized xenon is produced through a process known as spin-exchange optical pumping (SEOP), where the angular momentum from resonant, circularly-polarized light is transferred to the electronic spins of an alkali-metal, and is subsequently transferred to the xenon nuclei through gas-phase collisions. While SEOP has been extensively characterized throughout the years, new experimental techniques and emerging technologies have considerably advanced the field in recent years, and may enable a new understanding of the underlying physics of the system. The first five chapters in this dissertation review background information and the principal motivations for this work. Chapter one reviews the basics of NMR, from the various components of the nuclear spin Hamiltonian and different spin-relaxation pathways to the reasons behind the low polarization of nuclear spins at thermal equilibrium and a few alternative methods to `boost' the NMR signal. Chapter two discusses the fundamental aspects of SEOP, including the electronic spin polarization of the alkali-metal, polarization transfer to the xenon nuclei, and different avenues for the spin polarization to be depleted. The third chapter covers the practical considerations of SEOP from the viewpoint of an experimentalist; namely, the experimental differences when using a variety of alkali metals and noble gases, as well as different SEOP apparatuses and experimental parameters. Chapter four details a variety of different light sources that may be used for SEOP; specifically, the use of laser diode arrays (LDAs) are reviewed, including LDAs that have been frequency-narrowed for more efficient light absorption by the alkali metal. The fifth background chapter covers a variety of magnetic resonance applications of hyperpolarized xenon, including molecular biosensors, specific and non-specific binding with proteins, materials studies, and in vivo applications. The sixth chapter is used as an overview of the dissertation research, which is presented in chapters seven through eleven. Chapter seven details the arrangement of the particular SEOP apparatus used in this research, as well as the experimental protocol for producing hyperpolarized xenon. The eighth chapter accounts the implementation and characterization of the first frequency-narrowed LDA used in this research, as well as an equal comparison to a traditional broadband LDA. Chapter nine introduces the use of in situ low-field NMR polarimetry, which was used to distinguish an anomalous dependence of the optimal OP cell temperature on the in-cell xenon density; the low-field set-up is also used to examine the build-up of nuclear spin polarization in the OP cell as it occurs. The tenth chapter covers the use of high power, frequency-narrowed light sources that are spectrally tunable independent of laser power; this allows for the study of changes to the optimal spectral offset as a function of in-cell xenon density, OP cell temperature, and laser power. Xenon polarization build-up curves are also studied to determine if the spectral offset of the laser affects the nuclear spin polarization dynamics within the OP cell. Finally, chapter eleven accounts the use of high power, broadband LDAs to perform SEOP in which cesium is used as the alkali metal; these results demonstrate (for the first time) that the xenon polarization generated by cesium optical pumping can surpass that of rubidium OP under conditions of high laser flux and elevated in-cell xenon densities.

abstract: Alkali treated aluminosilicate (geopolymer) was functionalized by surfactant to increase the hydrophobicity for making Pickering emulsion for the first part of this work. In the first part of this study, alkali treated metakaolin was functionalized with cetyltrimethylammonium bromide ((C16H33)N(CH3)3Br, CTAB). The electrostatic interaction between this quaternary ammonium and the surface of the aluminosilicate which has negative charge has taken place. The particles then were used to prepare Pickering emulsion. The resulting stable dispersions, obtained very fast at very simple conditions with low ratio of aluminosilicate to liquid phase. In the second part, the interaction between geopolymer and glycerol was studied to see the covalent grafting of the geopolymer for making geopolymer composite. The composite material would be the basis material to be used as support catalyst, thin coating reagent and flame retardant material and so on, Variety of techniques, Thermogravimetric (TGA), Particle-induced X-ray emission (PIXE), FTIR, Solid state NMR, Powder X-ray diffraction (PXRD), BET surface area, Elemental analysis (CHN), TEM, SEM and Optical microscopy were used to characterize the functionalized geopolymer. / Dissertation/Thesis / M.S. Chemistry 2012