Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第16887号 / 工博第3608号 / 新制||工||1545(附属図書館) / 29562 / 京都大学大学院工学研究科化学工学専攻 / (主査)教授 松坂 修二, 教授 宮原 稔, 教授 大嶋 正裕 / 学位規則第4条第1項該当

A vast amount and variety of mine tailings are produced around the world each day. In the gold¬mining industry in South Africa the residue of crushed are is disposed of in large tailings or hydraulic fill dams. The outer walls of these dams are built up of layers of material, each of which is allowed to dry before the next layer is placed. In order to study the stability of these walls, the appropriate engineering properties of the tailings must be ascertained. Due to the construction technique used in tailings dam construction, the outer walls are in an unsaturated state, which also means that suctions are generated within the tailings. Various techniques exist to measure suction, most of which are indirect methods. The recent development of the mid-¬plane suction probe at the University of Pretoria created the opportunity of measuring suctions directly on desiccating samples of gold mine tailings. A test method has been developed from which soil mechanics parameters can be derived from suction measurements. The experimental programme consisted of a series of these newly developed tests on fine and coarse samples of gold mine tailings, as well as on different particle size ranges. The experimental results were used in the development of a new method of predicting the air-entry value, with only the grading of the tailings known. A new method of predicting the soil-water characteristic curve up to the air-entry value was also proposed. The results of the research showed that the tailings remain saturated up to the air-entry value. The clay, fine silt and medium silt sized tailings was found to be the controlling particle size ranges in the development of suctions. The vast amount of parameters and information gained through the use of the proposed test method clearly indicates its effectiveness in studying the performance and characteristics of a material drying from saturation. The results also indicated the effectiveness of the mid-plane suction probe for the direct measurement of suction. / Dissertation (M Eng (Geotechnical Engineering))--University of Pretoria, 2006. / Civil Engineering / unrestricted

O objetivo do presente estudo foi avaliar o desempenho, saúde intestinal e metabolizabilidade de dietas para frangos de corte alimentados com o uso contínuo ou mudança brusca de diferentes rações à base de milho e sorgo moído ou inteiro. No Exp. 1 foi estudada a mudança no tipo de grão com as dietas: M100% (ração à base de milho); S100% (ração à base de sorgo); M:S50% (ração à base de 50% milho e 50% sorgo); PS-M (ração à base de sorgo na fase pré-inicial e milho nas demais fases); PM-S (ração à base de milho na fase pré-inicial e sorgo nas demais fases). No Exp. 2 foi estudada a mudança na forma do grão de sorgo: Sm100% (ração à base de sorgo moído); Si100% (ação à base de sorgo inteiro); PSm-Si (ração à base de sorgo moído na fase pré-inicial e inteiro nas demais fases) e PSi- Sm (ração à base de sorgo inteiro na fase pré-inicial e moído nas demais fases). Os experimentos foram conduzidos em um delineamento em blocos casualizados (blocos no tempo) para avaliar o desempenho e epitélio jejunal (r=8), microbiota intestinal (r=4) e metabolizabilidade das dietas (r=10). As mudanças entre milho e sorgo não alteraram o desempenho, epitélio jejunal nem a metabolizabilidade das rações, mas influenciaram a porcentagem de Clostridium, Weissella, Bacillus e Alkaliphilus no intestino delgado e Lactobacillus e Desulfotomaculum nos cecos. O uso de sorgo inteiro piorou o desempenho aos sete dias. Aos 40 dias, Sm100% e PSm-Si apresentaram desempenhos semelhantes, PSi-Sm apresentou menor ganho de peso, mas melhor conversão alimentar e Si100% apresentou o pior desempenho. Si100% e PSm-Si apresentaram aumento no peso relativo da moela e na metabolizabilidade das rações, assim como diminuição de Clostridium e aumento de bactérias das famílias Actinomycetales e Bacillales no intestino delgado, Si100% resultou em menor porcentagem de Alkaliphilus e Enterococcus que Sm100% nos cecos. Conclui-se que a melhor estratégia de uso do sorgo é a substituição total de milho por sorgo moído ao alojamento com posterior mudança para sorgo inteiro, pois não afeta o desempenho e epitélio jejunal das aves, melhora a metabolizabilidade das rações e potencializa a redução de Clostridium no intestino delgado de frangos de corte. / The aim of this study was to evaluate performance, intestinal health and metabolizability of diets in broilers fed different corn- or sorghum (ground or whole)- based diets, continuously or with abrupt change between the diets. Exp. 1 - Change in the type of grain: C100% (corn-based diet); S100% (sorghum-based diet); C:S50% (50% corn and 50% sorghum-based diet); PC-S (corn-based diet in pre-starter phase and sorghum-based diet in other phases); PS-C (sorghum-based diet in pre-starter phase and corn-based diet in other phases). Exp. 2 - Change in the form of sorghum grain: Gs100% (ground sorghum-based diet); Ws100% (whole sorghum-based diet); PGs-Ws (ground sorghum-based diet in pre-starter phase and whole sorghum-based diet in other phases); PWs-Gs (whole sorghum-based diet in pre-starter phase and ground sorghum-based diet in other phases). Experiments were conducted in a randomized block design for to evaluate performance and jejunal epithelium (r=8), intestinal microbiota (r=4) and metabolizabilty of diets (r=10). The changes between corn and sorghum did not affect performance, jejunal epithelium or metabolizability of the diets, but influenced the genera Clostridium, Weissella, Bacillus and Alkaliphilus in the small intestine, and Lactobacillus and Desulfotomaculum in the caecum. Whole sorghum resulted in decreased performance at seven days of age. At 40 days, Gs100% and PGs-Ws showed similar performance, PWs-Gs showed lower weight gain and the best feed conversion rate, and Ws100% showed the worst performance. Ws100% and PGs-Ws resulted in the biggest gizzard relative weight and the highest diet metabolizability values, as well as the lowest level of Clostridium and highest level of Actinomycetales and Bacillales in the small intestine. Ws100% showed lower level of Alkaliphilus and Enterococcus than Gs100% in the caecum. The best strategy to use sorghum in broilers diets is replacing 100% of corn for ground sorghum since the first day followed by change to whole sorghum, because this diet did not affect performance or jejunal epithelium, improved diet metabolizability values, and reduced Clostridium in the small intestine of broilers.

For disperse system drug formulations, meaningful particle size distribution (PSD) comparators are essential in determining pharmaceutical equivalency and predicting biopharmaceutical equivalence in terms of the effect of particle size on the rate and extent of drug input. In formulation development and licensure, particle size characterization has been applied to establish relationships for bioequivalence of generic pharmaceutical drug products. The current approaches recommended by the US-FDA using median and span are not adequate to predict drug product performances or account for multi-modal PSD performance properties. The use of PSD similarity metric and the development and incorporation of drug release predictions based on PSD properties into PBPK models for various drug administration routes may provide a holistic approach for evaluating the effect of PSD differences on in vitro release of disperse systems and the resulting pharmacokinetic impact on drug product performance. The objectives of this study are to provide a rational approach for PSD comparisons by 1) developing similarity computations for PSD comparisons and 2) using PBPK-models to specifically account for PSD effects on drug input rates via a subcutaneous (SQ) administration route. Two techniques for measuring PSDs of reference (reference-listed drug product) and test (generic) drug products were investigated: OVL and PROB, as well as the current standard measurements of median and span. In addition, release rate profiles of each product pair simulated from modified Bikhazi and Higuchi’s model were used to compute release rate comparators such as similarity factor (f2) and fractional time ratios. A subcutaneous input PBPK model was developed and used to simulate blood concentration-time profiles of reference and test drug products. Pharmacokinetic responses such as AUC, Cmax, and Tmax were compared using standard bioequivalence criteria. PSD comparators, release rate comparators, and bioequivalence metrics were related to determine their relationships and identify the appropriate approach for bioequivalence waiver. OVL showed better predictions for bioequivalence compared to PROB, median, and span. For release profile comparisons, the f2 method was the best for bioequivalence prediction. The use of both release rate (e.g., f2) and PSD (e.g., OVL) comparison metrics significantly improved bioequivalence prediction to about 90%.

Practical combustion devices such as gas turbines and diesel engines operate at high pressures to increase their efficiency. Pressure significantly increases the overall soot yield. Morphology of these ultra-fine particles determines their airborne lifetime and their interaction with the human respiratory system. Therefore, investigating soot morphology at high pressure is of practical relevance. In this work, a novel experimental setup has been designed and built to study the soot morphology at elevated pressures. The experimental setup consists of a pressure vessel, which can provide optical access from 10° to 165° for multi-angle light scattering, and a counterflow burner which produces laminar flames at elevated pressures. In the first part of the study, N2-diluted ethylene/air and ethane air counterflow flames are stabilized from 2 to 5 atm. Two-angle light scattering and extinction technique have been used to study the effects of pressure on soot parameters. Path averaged soot volume fraction is found to be very sensitive to pressure and increased significantly from 2 to 5 atm. Primary particle size and aggregate size also increased with pressure. Multi-angle light scattering is also performed and flames are investigated from 3 to 5 atm. Scattering to absorption ratio is calculated from multi-angle light scattering and extinction data. Scattering to absorption ratio increased with pressure whereas the number of primary particles in an aggregate decreased with increasing pressure. In the next part of the study, Thermophoretic Sampling of soot is performed, in counterflow flames from 3 to 10 atm, followed by transmission electron microscopy. Mean primary particle size increased with pressure and these trends are consistent withour light scattering measurements. Fractal properties of soot aggregates are found to be insensitive to pressure. 2D diffused light line of sight attenuation (LOSA) and Laser Induced Incandescence (LII) are used to measure local soot volume fraction from 2 to 10 atm. Local soot volume fraction increased with pressure and soot concentration profiles showed good agreements when measured by both techniques. Experimental data obtained in this work is very helpful for the modelers for validating their codes and predicting the soot formation in pressurized flames.

The structural organization of plant organs and tissues determine the intake potential through the ease of forage particle breakdown, the nature of the particles produced as well as the rate of passage from the rumen. The cell wall content of forages influences the amount of energy required for chewing, and accounts for a considerable proportion of the total energy requirement. In the past, neutral detergent fibre (NDF) has been used as the only feed characteristic to predict the filling effects of forages, but there is substantial evidence that NDF alone is inadequate to make these predictions. Forage fragility is defined as the relative rate at which the particle size of forages are reduced during processes such as chewing or milling, and forage fragility might be related to lignin concentration and digestibility, as well as to anatomical differences among plant species. The physical characteristics of feedstuffs are not measured regularly, and these physical characteristics in relation to their nutritional properties should be taken into account for more precise feed formulation. Through the measurement of grinding energy, the possibility exists to predict forage fragility as related to the chemical composition of forages, which could lead to improved predictions of animal chewing activity and energy usage during the process of chewing. In order to investigate the possibility of developing a model for the prediction of forage fragility, twenty eight different forage samples were collected from 11 different locations. Samples included legumes, C3- and C4- grasses. Dried samples were analysed for various chemical components, as well as 24-hour in vitro NDF digestibility (ivNDFd) and rate of NDF degradation (NDFkd). Dried samples were pre-cut with a knife mill, fitted with a 2 cm screen, after which particle size distribution for each sample was determined using a Retsch Sieve shaker. Ten g duplicate samples were milled with a laboratory hammer mill and an ultra-centrifugal mill, both fitted with a 1 mm screen, for the measurement of grinding energy. During the grinding process, energy usage of the specific mill was measured using a data logger with corresponding computer software and energy transducer. Energy measurements were reported as J/g sample on dry matter (DM) basis. The 2 cm samples were milled with the knife mill again, fitted with a 1 mm screen, after which particle size distribution was determined again to analyse change in particle distribution for each forage sample. The results of this study indicated that dry matter, nitrogen, ivNDFd, NDFkd and initial particle size (IPS) can all be associated with increased forage fragility, as there was a decrease in energy usage during grinding with an increase in any of the aforementioned components. The acid detergent fibre (ADF), NDF, total phenols (TP), non-tannic phenols (NTP), as well as the % change in particle size can all be associated with decreased forage fragility, as there was an increase in energy usage during grinding with an increase in any one of these components. It would be expected that acid detergent lignin (ADL) is also associated with decreased forage fragility; however, this can only be assumed as the results for the effect of lignin on forage fragility are inconclusive in this study. Literature on energy requirement for milling operations of forages is inadequate. Grinding energy is related to the stem mechanical properties (such as maximum cutting force and stem shear strength), and physical properties (such as stem diameter, DM density and moisture content). The use of grinding energy has the potential be a practical and useful measure to predict forage fragility, however, the relative contribution of factors such as original particle size, shape, surface area, morphology and many other factors toward the fragility of forages is difficult to predict. More research is needed on the prediction of forage fragility before it can be incorporated as a meaningful input into nutritional models such as NRC, CNCPS and AMTS. / Dissertation (MScAgric)--University of Pretoria, 2014. / tm2015 / Animal and Wildlife Sciences / MScAgric / Unrestricted

This thesis is a part of a collaboration between Höganäs AB and Luleå University of Technology, aiming at replacing fossil process coal with bio-coal in their sponge iron process. The difference in gasification reactivity, i.e. reaction rate, between fossil coals and bio-coals is the major challenge in the endeavor to decrease the climate impact of the existing process. The goal of this thesis is to develop a model of reaction rate for bio-coals in relation to particle size distribution. Different particle size distributions were combined and tested to see how that affects the effective reaction rate. Within the scope of this work, gasification reactivities of different materials, including coal, cokes, and bio-coals, were determined. Three bio-coals were selected to study the effect of particle size distribution on reactivity. Kinetic parameters were determined by using thermogravimetric analysis in the temperature range of 770-850 °C while varying CO2 partial pressure between 0.1-0.4 atm. The effect of particle size on the reaction rate was investigated by using particles with diameter between 0.18 and 6.3 mm. The effect of particle size distribution on the reactivity of bio-coal in a packed bed was carried out in a macro thermogravimetric reactor with a constant bed volume of 6.5 cm3 at 980 °C and 40% (vol.) of CO2. The experimental investigation in three different rate-limiting steps was done for one bio-coal sample, i.e. Cortus Bark bio-coal. The activation energy of the bio-coal was 187 kJ mol-1, and the reaction order was 0.365. For the internal diffusion control regime, an increase in particle size resulted in low reaction rate. The effective diffusivity calculated from the Thiele modulus model was 1.41*10-5 m2 s-1. For the external diffusion control regime, an increase in particle size increased the reaction rate up to a certain point where it plateaued at >1 mm. By choosing two discrete particle size distributions, where a smaller average distribution can fit into a larger average distribution the reaction rate was lowered by 30% compared to only using a single narrow particle size distribution. This solution decreased the difference of apparent reaction rate in a packed bed between the bio-coal and anthracite from 6.5 times to 4.5 times. At the moment the model is not generalized for all bio-coals. However, the developed methodology can be routinely applied to assess the different bio-coal samples. One possible error can be that pyrolysis influences the gasification rate for bio-coal that is pyrolyzed below the temperature of the gasification test. There is a clear correlation between particle size distributions, bulk density, and apparent reactivity. By mixing two distributions the reaction rate of Cortus Bark was reduced from 6.5 times the reaction rate of anthracite to 4.5.

The fluid bed granulation is a well-established method how to improve such properties of powders as flowability and increase content uniformity of the tablets. In this thesis, there was evaluated a granulation process on a lab scale fluid Glatt bed granulator and optimized for highest possible yield. Product yield in the size range of 80-90 % of granules and process reproducibility were stated as most effective. The product was analysed for its particle size distribution, the API distribution within the different particle size fractions and the flowability of the final granules. For process optimization, the most critical parameters such as spraying rate, particle size of raw materials and fluid bed pressure were identified and evaluated. As the highest-yielding dosage for the powder binder was found the spraying rate of 9 g/min. Changes in bed fluid pressure and nozzle pressure showed no significant improvement. Different grades of caffeine were compared for their impact on the granulation properties. Sieved caffeine enhanced yield of the product and reproducibility compared to bulk or disagglomerated caffeine.

Due to its prevalence over large, densely populated areas, ammonium nitrate is an important chemical species in aerosol research. However, due to its volatility at ambient temperatures and over low temperature gradients, ammonium nitrate can be a difficult species to accurately measure. The volatility of ammonium nitrate is known to be dependent on temperature, relative humidity, the internal mixing state of the particle, and availability of the precursor gas constituents. The particle's physical state affects the equilibrium constant value of the ammonium nitrate - nitric acid / ammonia exchange and helps determine the dissociation rate. For indoor aerosol research, the outdoor originating aerosol particles' exposure to the new physical conditions indoors, such as changes in temperature, humidity, and particle-surface reactions within the microenvironment all accelerate ammonium nitrate dissociation. This increased rate of partitioning can generate artifacts on datasets, increase indoor particle formation, and accelerate the corrosion of cultural antiquities through acidification. The magnitude of these impacts is uncertain due to the current lack of knowledge on particle transformation processes when outdoor originating particles migrate indoors. To address this gap in knowledge, this thesis...

The separation of solids from biological wastewater treatment is an important step in the treatment process, as it has a significant impact on effluent water quality. The moving bed biofilm reactor (MBBR) technology is a proven upgrade or replacement wastewater treatment system for carbon and nitrogen removal. However, a challenge of this technology is the characteristics of the effluent solids that results in their poor settlement; with settling being the common method of solids removal. The main objective of this research is to understand and expand the current knowledge on the settling characteristics of MBBR produced solids and the parameters that influence them. In particular, in this dissertation, the impacts are studied of carrier types, biofilm thickness restraint design of carriers, and varying carbonaceous loading rates on MBBR performance, biofilm morphology, biofilm thickness, biofilm mass, biofilm density, biofilm detachment rate, solids production, particle size distribution (PSD) and particle settling velocity distribution (PSVD). With this aim, three MBBR reactors housing three different carrier types were operated with varying loading rates. In order to investigate the effect of carrier geometrical properties on the MBBR system, the conventional, cylindrically-shaped, flat AnoxK™ K5 carrier with protected voids was compared to two newly-designed, saddle-shaped Z-carriers with the fully exposed surface area. Moreover, the AnoxK™ Z-200 carrier was compared to the AnoxK™ Z-400 carrier to evaluate the biofilm thickness restraint design of these carriers, where the Z-200 carrier is designed for greater biofilm thickness-restraint. The Z-200 carrier is designed to limit the biofilm thickness to the level of 200 µm as opposed to 400 µm for the Z-400 carrier. Finally, to investigate the effects of varying carbonaceous loading rates on system removal performance, biofilm characteristics and solids characteristics, further analyses were performed at three different loading rates of 1.5 to 2.5 and 6.0 g-sBOD/m2·d in steady-state conditions. The PSD and the PSVD analyses were combined to relate these two properties. A settling velocity distribution analytical method, the ViCAs, was applied in combination with microscopy imaging and micro-flow imaging to investigate the relation of PSD and settling behaviour of MBBR produced particles. The obtained results have indicated that the carrier type significantly impacted the MBBR performance, biofilm, and particle characteristics. As such, the K5 carrier MBBR system demonstrated a statistically significantly higher carbonaceous removal rate and efficiency (3.8 ± 0.3 g-sBOD/m2·d and 59.9 ± 3.0% sBOD removal), higher biofilm thickness (281.1 ± 8.7 μm), higher biofilm mass per carrier (43.9 ± 1.0 mg), lower biofilm density (65.0 ± 1.5 kg/m3), lower biofilm detachment rate (1.7 ± 0.7 g-TSS/ m2·d) and hence lower solids production (0.7 ± 0.3 g-TSS/d) compared to the two Z-carriers. The Z-carriers' different shape exposes the biofilm to additional shear stress, which could explain why the Z-carriers have thinner and denser biofilm, resulting in higher solids production and lower system performance in comparison with K5. Moreover, the carrier type was also observed to impact the particle characteristics significantly. PSD analysis demonstrated a higher percentage of small particles in the Z-carrier system effluent and hence a significantly lower solids settling efficiency. Therefore, the solids produced in the K5 reactor have shown enhanced settling behaviour, consisting of larger particles with faster settling velocities compared to Z-carriers. This dissertation also investigated the effects of restraint biofilm thickness on MBBR performance by comparing the Z-200 biofilm thickness-restraint carrier to the Z-400 carrier. No significant difference was observed in removal efficiency, biofilm morphology, biofilm density, biofilm detachment rate, and solids production between the Z-200 to the Z-400 carriers. The PSD and the PSVD analyses did not illustrate any significant difference in the particles’ settling behaviour for these two biofilm thickness restraint carriers, indicating that the biofilm thickness-restraint carrier design was not a controlling factor in the settling potential of MBBR produced solids. Finally, this research studied the effect of varying loading rates and demonstrated a positive, strong linear correlation between the measured sBOD loading rate and the removal rate, indicating first-order BOD removal kinetics. The biofilm thickness, biofilm density and biofilm mass decreased when the surface area loading rate (SALR) was increased from 2.5 to 6.0 g-sBOD/m2·d. The solids retention time (SRT) was also shown to decrease by increasing the SALR, where the lowest SRT (1.7 ± 0.1 days) was observed at the highest SALR, with the highest cell viability (81.8 ± 1.7%). Significantly higher biofilm detachment rate and yield were observed at SALR 2.5, with the thickest biofilm and a higher percentage of dead cells. Consequently, a higher fraction of larger and rapidly settling particles was observed at SALR of 2.5 g-sBOD/m2·d, which leads to a significantly better settling behaviour of the MBBR effluent solids. This study expands the current knowledge of MBBR-produced particle characteristics and settling behaviour. A comprehensive understanding of the MBBR system performance and the potential influencing factors on the MBBR produced solids, particle characteristics, and their settleability will lead to optimized MBBR design for future pilot- and full-scale applications of the MBBR.