Ordinary Portland cement (OPC) is the main constituent of concrete works as a principal binder for aggregates and intrinsically transmits the brittleness into concrete through the formation of hydration crystals in the cement microstructure. A number of nano cementitious composites were developed in recent years to offset the brittleness with newly discovered nanomaterials and the most prevalent among those is the graphene oxide (GO). The main objective of this PhD research work is to develop nano graphene cementitious composites (NGCC) using low cost, two dimensional (2D) graphene nanoplatelets (GNPs) and one dimensional (1D) graphited carbon nanofibres (GCNFs) with unique conical surface morphology. The GNPs were sourced synthesised in an environmental friendly way via plasma exfoliation whereas, GCNFs were manufactured through catalytic vapour grown method. The project further investigated the effect of these nanomaterials in regulating the distinctive microstructure of cement matrix leading to enhance its mechanical properties. Three different types of high-performance NGCC namely NGCC-Dot, NGCC-Fnt and NGCC-CNF, are developed by activating pristine GNPs (G-Dot), functionalised GNPs (G-Fnt) and graphited nanofibers (G-CNFs) into the cement matrix respectively. It is found through various characterization and experimental techniques that both GNPs and GCNFs regulated the cement microstructure and influenced the mechanical properties of NGCC uniquely. A remarkable increase in the flexural and the tensile strength of newly developed NGCC has been achieved and that could be attributed to the formation of distinctive microstructure regulated by catalytic activation of these nanomaterials. The shape (1D, 2D) and unique morphology of these nanomaterials played a vital role in the mechanism of crystal formation to regulate the cement microstructure. Based on the observations of test results and comprehensive characterization, the possible mechanisms of crystal formation and development of distinctive microstructure of NGCC has been established which has then proceeded to the development of a physical model for NGCC development.

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No. of bitstreams: 2 tese_ireni_leitzke_carvalho.pdf: 1397252 bytes, checksum: ad9c13976120f5dcba14cf0b7f2d0ade (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-12-09 / Sem bolsa / A calibração de metodologias capazes de identificar de forma rápida e eficiente a qualidade de um lote de sementes, mediante testes de viabilidade e de vigor como o teste de tetrazólio, cujo procedimento metodológico para a cultura do arroz ainda carece de ajustes. Assim, o objetivo deste trabalho foi estudar alternativas de preparo, pré-condicionamento e coloração das sementes de arroz para avaliação da viabilidade, e estabelecer classes de viabilidade, para estimar vigor de sementes de arroz. O trabalho foi conduzido em três etapas: a) ajuste de procedimentos de preparo das sementes de arroz para condução do teste de tetrazólio, para tanto foram utilizados sementes de quatro cultivares de arroz irrigado e duas de sequeiro, cada uma composta por dois lotes. Sendo testado quanto à necessidade da remoção da casca (pálea e lema) e corte das sementes; b) estudo de concentrações do sal de tetrazólio, período de pré-condicionamento e de coloração para avaliar a viabilidade de sementes de arroz. Nesta etapa foram utilizadas as mesmas cultivares da primeira etapa, cada uma composta por um lote, sendo utilizadas as metodologias que apresentaram os melhores resultados na etapa anterior. Foram avaliadas diferentes concentrações do Sal de Tetrazólio (0,1; 0,25; 0,5 e 1,0%), três tempos de coloração (0,5; 1 e 2h), cinco períodos de hidratação (0,5; 1; 2; 3 e 4h) das sementes e duas temperaturas de embebição (35 e 40 °C); c) estimativa do vigor das sementes pelo teste de tetrazólio, utilizando-se sementes de dez lotes da cultivar Irga 424. Foram estabelecidas quatro classes de viabilidade (sementes viáveis de alto vigor, viáveis de médio vigor, viáveis de baixo vigor e não viáveis e mortas). Os resultados indicaram que para a avaliação da viabilidade de sementes de arroz pelo teste de tetrazólio é recomendável a remoção da pálea e lema, sendo mais eficiente o corte longitudinal na metade distal do eixo embrionário. O período de execução do teste de tetrazólio para sementes de arroz pode ser reduzido para três horas, utilizando hidratação das sementes por 1h a 40°C, 1h para as atividades de corte e avaliação e 1h para coloração na concentração de 0,25%. Dessa forma, é possível concluir que as metodologias propostas nessa pesquisa permitem avaliar a viabilidade de sementes de arroz pelo teste de tetrazólio; para avaliação do vigor o teste se mostrou promissor, porém necessitando de aprimoramento metodológico. / Calibration methodologies able to identify quickly and efficiently the quality of a lot of seeds through viability and vigor tests is constantly searched by seed technology. One of the most widely used tests for this purpose is the tetrazolium test, which methodological procedure for the rice crop still needs adjustments. This research aimed to study the preparation of alternatives, preconditioning and staining of rice seeds to evaluate the viability and establishing classes of viability to estimate the vigor of rice seed. The experiment was conducted in three stages: a) adjustment preparation procedures of rice seeds for conducting the tetrazolium test for both irrigated and upland plant varieties, were used four irrigated rice plant variety and two of upland plant variety, each consisting of two lots. It is tested on the need for removal of the shell (palea and lemma) and cut the seeds; b) study tetrazolium salt concentrations, preconditioning period and staining to evaluate the viability of rice seeds. At this stage, we used the same cultivars of the first stage, each consisting of a lot being used methodologies that showed the best results in the previous step. They were evaluated different concentrations of tetrazolium salt (0.1, 0.25, 0.5 and 1.0%) three times of staining (0.5, 1 and 2h), five periods of hydration seeds (0,5; 1, 2, 3 and 4h) and two soaking temperatures (35 and 40 ° C); c) estimate of seed vigor by the tetrazolium test, using ten seed lots of plant variety Irga 424 were established four viability classes (viable seeds of high vigor, viable medium vigor, viable low vigor and no viable and dead). The results indicated for the evaluation of viability of rice seed by tetrazolium testing is recommended to remove palea and lemma thereof and slitting the distal half of the embryonic axis is more efficient. The tetrazolium test execution period for rice seeds can be reduced to three hours using seed hydration for 1h at 40 ° C, for 1h cutting and evaluation activities and staining for 1h at 0.25% concentration. Thus, it leads to conclude that the proposed methodologies in this research to allow to evaluate the viability of rice seeds by the tetrazolium test; in order to evaluate vigor the test showed promise but needing methodological improvement.

The thesis is focused on the possibility of using secondary energy resources as an additive to concrete to improve some of its resulting properties. The theoretical part is devoted to the problems of shrinkage and prominence hydration process during hydration of the concrete. This section also contains the results of research work from domestic and foreign sources of high temperature fly ash and fluidized bed combustion fly ash use and their using in concrete. The practical part verifies the possibility of using these materials and their combination as an additive to concrete with impact on the physical and mechanical properties.

Mit Hilfe von linearer und nichtlinearer Infrarotspektroskopie im Femtosekundenbereich wurden Schwingungsdynamiken von H2PO4- und BH4- Ionen untersucht sowie ein Volumenplasmon in einem Schichtsystem aus Ga-dotiertem ZnO. Phosphatgruppen stellen Hydratisierungsstellen in Biomolekülen wie DNS oder Phospholipiden dar und wechselwirken intensiv mit wässrigen Solvatationsschalen. Die Untersuchung einer isolierten Phosphatgruppe in Wasser, dem Phosphation H2PO4-, hat ergeben, dass Phosphatschwingungen sehr sensitive Sonden für die ausgeprägte Fluktuationsdynamik von Volumenwasser darstellen, was experimentell mit homogen verbreiterten Linienformen nachgewiesen werden konnte. Komplexe Hydride wie NaBH4 werden wegen ihres großen Wasserstoffgehalts als potenzielle Wasserstoff- bzw. Energieträger für mobile Anwendungen diskutiert. Jedoch ist die Wasserstoffabsorption- bzw. emission energieaufwendig. Für ein detailliertes Verständnis der Wasserstoffdynamiken im BH4- Tetraeder wurden die Energieverlustkanäle nach optischer Anregung von B-H Schwingungen untersucht. Es konnte experimentell gezeigt werden, dass eine Energieumverteilung von hoch- zu niederfrequenten B-H Schwingungen stattfindet mit abschließender Dissipation in das umgebende Medium, z.B. ein Lösungsmittel oder ein NaBH4 Festkörper. Volumenplasmonen repräsentieren kollektive, longitudinale Anregungen eines freien Elektronengases in ionischen oder polaren Kristallstrukturen. In einer hoch Ga-dotierten ZnO-Schicht eines speziellen Schichtsystems konnte eine Volumenplasmon in Reflektionsgeometrie optisch angeregt werden. Dabei führte Intrabandanregung von Leitungsbandelektronen zur Erhitzung des Elektronengases und, durch das nichtparabolische ZnO-Leitungsband, zu einer Erhöhung der effektiven Elektronenmasse und damit zu einer Rotverschiebung der Plasmafrequenz auf einer sub-ps Zeitskala. Damit konnte ein Mechanismus aufgezeigt werden, um Plasmafrequenzen von Volumenplasmonen gezielt transient zu kontrollieren. / The vibrational dynamics of H2PO4- and BH4- ions and a bulk plasmon in Ga-doped ZnO were studied with methods of linear and nonlinear infrared spectroscopy in the femtosecond range. Phosphates constitute the major hydration sites of biomolecules such as DNA or phospholipds and, thus, strongly interact with aqueous hydrations shells. The investigation of isolated phosphate ions (H2PO4-) revealed a distinct sensitivity of phosphate vibrations on the fluctuation dynamics of bulk water that could be experimentally shown by homogeneously broadened line shapes of phosphate vibrations. Complex hydrides such as NaBH4 constitute a large hydrogen content and, accordingly, are discussed as energy- and hydrogen carriers for mobile applications. However, hydrogen uptake and release are energetically unfavourable. In order to gain detailed insights into hydrogen dynamics within the BH4- tetrahedrons energy relaxation mechanisms were studied after optical excitation of B-H vibrations. It could be experimentally shown that energy dissipation proceeds from high-frequency to low-frequency B-H vibrations into the heat bath of the environment, such as e.g. a liquid solvent or the solid state NaBH4. Bulk plasmons represent collective, longitudinal excitations of a free electron gas in an ionic or polar crystal. Within a specifically designed system of Ga-doped ZnO layers, a bulk plasmon could be optically excited in a reflection geometry. Intraband excitation of conduction band electrons resulted in a heating of the electron gas. Due to a non-parabolic ZnO conduction band hot electrons exhibit an increased effective electron mass and, thereby, reduce the plasma frequency. A redshift of the bulk plasma frequency that possesses sub-ps dynamics could be experimentally shown which represents a mechanism for the time-dependent control of plasma frequencies.

In many parts of Australia the climate is such that people are working long hours in the heat. Consequences of excessive environmental heat stress range from reduction in safety due to impairment of concentration, to heat illness, which in extreme cases can be fatal. A critical factor in tolerance of workers to environmental heat stress is their level of hydration. Maximising productivity without compromising the health and safety of the work force requires quantification of the degree of stress posed by the thermal environment. For this purpose a number of heat stress indices have been developed. A recently introduced index is the Thermal Work Limit (TWL), which has been widely adopted and implemented in the underground mining industry in Australia. The field use of TWL and protocols in the mining industry with resultant reduction in heat illness and lost production is a practical endorsement of the index, and its validity under controlled conditions has been confirmed by a preliminary study. The further work needed to complete this validation forms part of this thesis. TWL was found to reliably predict the limiting workload in the controlled environment, reinforcing the validity of the algorithm and its application in the workplace. To date TWL has largely been used in the underground environment, however as the algorithm is equally applicable to the above ground environment where radiant heat forms a significant component of the thermal load, field studies were carried out at mining installations in the Pilbara region of Western Australia to evaluate this application of the index. The current industry standard index of heat stress is the Wet bulb Globe Temperature (WBGT). / The shortcomings of this index are widely acknowledged and in practice it is frequently ignored as it is seen to be unnecessarily conservative in many situations. The sensitivity of TWL to the cooling effect of air movement implied that TWL would be more relevant than WBGT as a predictor of the impact of environmental heat stress in outdoor work environments and this was supported by the results. On the strength of this, recommended management protocols linked to TWL similar to those already in place in many underground workplaces, were developed for the management of thermal risk in outdoor work environments. Maintaining adequate hydration is the single most important strategy to counteract the effects of thermal stress. No heat stress index can protect workers from the combined effects of dehydration and thermal stress. To document the hydration status of the outdoor workforce in the Pilbara, the hydration level of groups of workers was assessed from the specific gravity of their urine. To further evaluate whether the fluid replacement behaviour of the workers is adequate to replace fluids lost in sweat, a fluid balance study was carried out to quantify average fluid intakes and sweat fluid losses. The majority of workers were found to be inadequately hydrated at the start of the shift and their fluid intakes were in general well below the requirements to replace sweat losses - let alone improve hydration. Recommendations for fluid intakes based on documented rates of sweat loss are included in the thesis. Based on the findings of this study workable management strategies have been recommended to minimise the risk to outdoor workers in thermally stressful environments.

Cette thèse vise à étudier les propriétés thermo-poro-mécaniques de roches de faille, à partir de l'analyse structurale et microstructurale d'une faille aujourd'hui à l'affleurement et à partir d'expériences menées en laboratoire, en vue de déterminer les processus qui contrôlent l'efficacité de deux mécanismes responsables de d'affaiblissement cosismiques : la pressurisation thermique et le mécanisme d'affaiblissement par drainage. L'étude de terrain a été conduite sur deux affleurements appartenant à une faille décrochante potentiellement active appartenant au système de failles du Chugoku occidental (Japon) : la faille d'Usukidani. Le travail expérimental a quant à lui été mené dans le laboratoire de déformation des roches de l'Université de Kyoto. Les résultats majeurs de ce travail sont exposés ci-dessous. <br /> Les propriétés hydrologiques et poro-élastiques de la gouge et de la brèche de la faille d'Usukidani ont été determinées à partir d'échantillons prélevés sur le terrain. Ces données hydrauliques ont ensuite été utilisées dans un modèle numérique afin d'évaluer l'importance du phénomène de pressurisation thermique dans le cas d'un glissement cosismique le long de la zone de glissement principale et le long de zones de glissement secondaires. Les résultats de cette modélisation suggèrent que le mécanisme de pressurisation thermique n'est efficace que si la rupture reste localisée le long des zones de glissement contenant de la gouge, avec comme facteur de contrôle l'épaisseur de cette zone de glissement. <br /> Afin d'identifier les processus dynamiques particulaires responsables de l'affaiblissement cosismique dans la zone de glissement, plusieurs essais de friction ont été menés sur une machine à cisaillement annulaire. Ces expériences ont été conduites à des vitesses cosismiques (équivalentes à 0,09, 0,9 et 1,3 m/s) en conditions humides ou conditions sèches. Les données obtenues montrent que quelles que soient les conditions d'humidité initiales, les failles simulées montrent toutes un affaiblissement lors du déplacement. Un examen détaillé des microstructures des gouges cisaillées obtenues une fois l'équilibre frictionnel atteint permet de définir deux types de microstructures impliquant deux régimes de déformation : un régime de déformation par roulement avec la formation d'agrégats argileux, et un régime de déformation par glissement avec la formation d'une zone de cisaillement complexe localisée à l'interface gouge-éponte. L'affaiblissement observé lors des expériences semble être lié à une diminution de la proportion de grains roulants par rapport à celle de grains glissants, et semble être favorisé par le développement des agrégats argileux, lesquels sont contrôlés par la teneur en eau.<br /> A partir d'un modèle numérique (P2 FEM) et des données de contrainte cisaillante obtenues lors des essais de friction, il a été possible de calculer l'évolution de la température de la gouge en fonction du déplacement. Les résultats suggèrent que la distance dc pourrait représenter la distance nécessaire à une faille pour produire et diffuser assez de chaleur afin de casser les ponts d'eau capillaire (forces d'adhésion) et ainsi permettre à l'eau contenue dans la gouge d'être libérée. Ce mécanisme est appelé mécanisme d'affaiblissement par drainage.

Les aluminophosphates microporeux AlPO4-n possèdent un large potentiel d'applications en tant que catalyseurs et adsorbants, et présentent une affinité très particulière avec l'eau. L'hydratation de ces composés à structure zéolithique provoque généralement une modification réversible de leur structure, ce qui entraîne une altération de leurs propriétés. Ici, l'utilisation conjointe de résultats expérimentaux (RMN de l'aluminium et du phosphore, diffraction des rayons X, analyse thermique, spectroscopie infrarouge) et de calculs théoriques basés sur la Théorie de la Fonctionnelle de la Densité (DFT) amène une meilleure compréhension des interactions entre molécules d'eau et AlPO4-n.<br /> L'étude d'une structure modèle, l'AlPO4-34, apporte des informations sur le comportement de l'eau dans les pores. Elle permet également de présenter les mécanismes d'hydratation et de déshydratation et de proposer une phase partiellement hydratée, en accord avec des résultats expérimentaux. Une synergie est proposée entre la diffraction et une approche par dynamique moléculaire. Une description des domaines de stabilité des phases hydratées est aussi développée.<br /> A l'aide de cette approche théorique, de nouvelles structures sont ensuite étudiées. Tout d'abord, grâce à la diffraction des rayons X et des calculs DFT, la maille complète de l'AlPO4-36 calciné déshydraté est décrite. Ensuite, une étude expérimentale détaillée est complétée par une approche théorique statique et dynamique pour proposer des éléments de réponses sur la phase hydratée de l'AlPO4-18.<br /> Afin de généraliser l'étude à des mailles plus complexes et des temps de calcul plus courts, une comparaison des méthodes théoriques avec des bases d'ondes planes ou des bases d'orbitales localisées est effectuée. Ce comparatif fournit, après optimisation de la base, des résultats structuraux similaires entre les deux méthodes. Enfin, une approche d'ordre N est mise en oeuvre avec succès sur les structures microporeuses étudiées.

<p>Aqueous solubility is a key parameter influencing the bioavailability of drugs and drug candidates. In this thesis computational models for the prediction of aqueous drug solubility were explored. High quality experimental solubility data for drugs were generated using a standardised protocol and models were developed using multivariate data analysis tools and calculated molecular descriptors. In addition, structural features associated with either solid-state limited or solvation limited solubility of drugs were identified.</p><p>Solvation, as represented by the octanol-water partition coefficient (log<i>P</i>), was found to be the dominant factor limiting the solubility of drugs, with solid-state properties being the second most important limiting factor.</p><p>The relationship between the chemical structure of drugs and the strength of their crystal lattice was studied for a dataset displaying log<i>P</i>-independent solubility. Large, rigid and flat molecules with an extended ring-structure and a large number of conjugated π-bonds were found to be more likely to have their solubility limited by a strong crystal lattice than were small, spherically shaped molecules with flexible side-chains.</p><p>Finally, the relationship between chemical structure and drug solvation was studied using computer simulated values of the free energy of hydration. Drugs exhibiting poor hydration were found to be large and flexible, to have low polarisability and few hydrogen bond acceptors and donors.</p><p>The relationship between the structural features of drugs and their aqueous solubility discussed in this thesis provide new rules-of-thumb that could guide decision-making in early drug discovery.</p>

No description available.

Aqueous solubility is a key parameter influencing the bioavailability of drugs and drug candidates. In this thesis computational models for the prediction of aqueous drug solubility were explored. High quality experimental solubility data for drugs were generated using a standardised protocol and models were developed using multivariate data analysis tools and calculated molecular descriptors. In addition, structural features associated with either solid-state limited or solvation limited solubility of drugs were identified. Solvation, as represented by the octanol-water partition coefficient (logP), was found to be the dominant factor limiting the solubility of drugs, with solid-state properties being the second most important limiting factor. The relationship between the chemical structure of drugs and the strength of their crystal lattice was studied for a dataset displaying logP-independent solubility. Large, rigid and flat molecules with an extended ring-structure and a large number of conjugated π-bonds were found to be more likely to have their solubility limited by a strong crystal lattice than were small, spherically shaped molecules with flexible side-chains. Finally, the relationship between chemical structure and drug solvation was studied using computer simulated values of the free energy of hydration. Drugs exhibiting poor hydration were found to be large and flexible, to have low polarisability and few hydrogen bond acceptors and donors. The relationship between the structural features of drugs and their aqueous solubility discussed in this thesis provide new rules-of-thumb that could guide decision-making in early drug discovery.