Neste trabalho avaliou-se o comportamento coloidal de suspensões nasais contendo micropartículas de celulose (MCC-NaCMC) com o objetivo de desenvolver um produto genérico compatível com o produto referência de mercado. As propriedades reológicas destas formulações possuem alta influência nos atributos críticos de qualidade do produto, como uniformidade de dose, devido sedimentação durante estocagem em prateleira, e também na performance in-vitro/ in-vivo. Realizaram-se testes com diferentes concentrações de MCC-NaCMC e diferentes parâmetros de processo (tempo e taxa de cisalhamento) utilizando um planejamento de experimentos (DoE) de superfície de respostas através de um modelo composto central. As respostas avaliadas foram tamanho de partículas (quantidade em porcentagem de partículas menores que 1µm e D90) através da técnica por difração a laser e viscosidade/tixotropia através de um reômetro rotacional. Influências significativas dos três fatores e efeitos sinérgicos entre eles nas respostas analisadas foram observadas. Desta maneira foi possível obter respostas próximas ao do produto referência de mercado através deste mapeamento. Observou-se também uma alta correlação entre as respostas, pois este estudo mostrou que o tamanho das partículas coloidais controla a viscosidade e tixotropia das dispersões coloidais. Este trabalho mostrou a significativa influência das etapas de processo no comportamento coloidal das formulações. Idealmente o processo deveria ser monitorado por medidas reológicas, porém este controle é inviável devido ao tempo para a reestruturação do sistema (24 horas). Portanto, a melhor alternativa seria o monitoramento do processo por análise de tamanho de partículas online. / In this work, the colloidal behavior of nasal suspensions containing cellulose microparticles (MCC-NaCMC) was evaluated, in order to develop a generic product compatible with the brand-name product. The rheological properties of these formulations have high influence on the critical quality attributes of the product, such as dose uniformity, due to sedimentation during shelf life, and also on in-vitro/in-vivo performance. Tests were performed with different concentrations of MCC-NaCMC and different process parameters (time and shear rate) using a Design of Experiments (DoE) with response surface by central composite design. The responses evaluated were particle size (amount in percentage of particles smaller than 1m and D90) by means of laser diffraction, and viscosity / thixotropy using a rotational rheometer. Significant influences of the three factors and synergic effects among responses were observed. Through this mapping it was possible to obtain nearby responses to the brand-name product. There was also a strong correlation between the responses, because the size of colloidal particles controlled the dispersion viscosity and thixotropy. This study showed the significant influence of the process steps on the colloidal behavior of the formulations. Ideally the process should be monitored by rheological measurements, but this control is not feasible due to the time required for the system rebuilding (24 hours). Therefore, the best alternative would be monitoring the process by the online particle size analysis.

The aim of this thesis is to present a simple model for the radiation to light conversion processes in fluorescent layers as an aid in future developments and applications. Optimisation between sensitivity and spatial resolution for fluorescent layers in digital radiology is a delicate task where the extrinsic efficiency for various phosphors needs to be established for varying parameters. The extrinsic efficiency of a fluorescent layer can be expressed as the ratio of the light energy per unit area at the screen surface to the incident xray energy fluence. Particle size is a critical factor in determining the value of the extrinsic efficiency, but in most models it is not treated as an independent variable. Based on the definition of a light extinction factor (ξ), a model is proposed such that, knowing the intrinsic efficiency η, the particle size and the thickness of a certain make of screen, the extrinsic efficiency can be calculated for an extended range of particle sizes and / or screen thicknesses. The light extinction factor ξ is an optical parameter determined from experimental data on extrinsic efficiency. The proposed model is compared to established methods. Further experiments have confirmed the validity of the model. Monte-Carlo simulations have been utilised to refine the calculations of energy imparted to the phosphor by taking into account the escape of scattered and K-radiation generated in the screen and interface effects at the surfaces. The luminance was measured for a set of in-house manufactured screens of varying thicknesses and particle sizes. Utilising the proposed model, the corresponding calculated values deviated ± 14 %.within the studied range.

Abstract not available

Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

This study focuses on the analysis of atmospheric particles sampled from two different field campaigns: the field study at a cattle feeding facility in the summer from 2005 to 2008 and the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in 2008. A ground site field study at a representative large cattle feeding facility in the Texas Panhandle was conducted to characterize the particle size distributions, hygroscopicity, and chemical composition of agricultural aerosols. Here, a first comprehensive dataset is reported for these physical and chemical properties of agricultural aerosols appropriate for use in a site-specific emission inventory. The emission rate and transport of the aerosols are also discussed. In addition, mixing ratios of total and gaseous ammonia were measured at the same field in 2007 and 2008. Measurements such as these provide a means to determine whether the fugitive dust emitted from a typical large feedlot represents a health concern for employees of the feeding operation and the nearby community. Detailed chemical composition of aircraft-sampled particles collected during ISDAC was studied. Filter samples were collected under a variety of conditions in and out of mixed phase and ice clouds in the Arctic. Specifically, particles were sampled from a mixed-phase cloud during a period of observed high concentrations of ice nuclei (IN), a biomass plume, and under relatively clean ambient conditions. Composition of particles was studied on a particle-by-particle basis using several microspectroscopy techniques. Based on the elemental composition analysis, more magnesium was found in Arctic cloud residues relative to ambient air. Likewise, based on the carbon speciation analysis, high IN samples contained coated inorganics, carbonate, and black or brown carbon particles. In the samples collected during a flight through a biomass burning plume, water-soluble organic carbon was the dominant overall composition. Due to their hygroscopic nature, these organics may preferably act as cloud condensation nuclei (CCN) rather than IN. Other ambient samples contained relatively higher fractions of organic and inorganic mixtures and less purely water-soluble organics than found in the biomass particles. The most likely source of inorganics would be sea salt. When present, sea salt may further enhance ice nucleation.

In this study the incipient motion of coarse solitary particles having different specific weights and shapes was investigated. A tilting flume of rectangular cross-section having a net working length of 12 m was used through the experiments. The slope of the channel and the discharge in the channel are the two basic variable parameters that determine the initiation of motion. Particles made of cement and mixture of cement and iron dust in certain ratios were used in the experiments with an obstructing element of various heights right behind the particles. Dimensionless hydraulic parameters determined from theoretical analysis were related to each other. Velocity profiles over the flow depths were measured and flow conditions corresponding to critical conditions were evaluated in terms of critical velocities and shear velocities. The findings of this study were compared with the results of similar studies given in the literature.

Volcanogenic lightning has a long documented history in the scientific field, though its origins are still poorly understood. The interactions leading to electrification of ash plumes is essentially a function of the microphysics controlling and affecting ash particle collisions. This thesis presents measurements made on charged particle interactions in a fluidized bed, with large-scale applications to the phenomenon of volcanogenic lightning and charged particle dynamics in volcanic plumes. Using a fluidized bed of ash samples taken from Ecuador's Volcán Tungurahua, particles are introduced to a collisional environment, where they acquire an associated polarity. A charged copper plate is used to collect particles of a given polarity, and particle size distributions are obtained for different weight fractions of the ash. It is observed that relatively smaller particles acquire a net negative charge, while larger particles in the sample charge positively. This is a well-documented occurrence with perfectly spherical, chemically identical samples, but this work represents one of the first applications of the principle to volcanic ash. Image analysis is preformed to determine the size distribution associated with specific polarities, and the associated minimum charge on each particle is calculated based on the plate collection height and particle size. We also present results that demonstrate the relationship between particle collisions and the amount of charge exchanged. Using techniques developed to examine the collision rate within a flow, combined with the charging rates determined from this experiment, we determine a maximum charge exchange rate of 1.28±0.23 electrons transferred per collision.

The present work aimed at assessing the dose emission and aerodynamic particle size characteristics of formoterol fumarate from Atimos Modullite, a metered dose inhaler (MDI) and Foradil Aeroliser, Easyhaler, and Oxis Turbuhaler dry powder inhalers (DPI) at different inhalation flow rates and volumes using in vitro methodology. Recognised methods have been adopted and validated to generate the results. The in vitro characteristics of formoterol were measured according to standard pharmacopeial methodology with adaptation to simulate routine patient use. The dose emission from the Atimos Modulite was determined using inhalation volumes of 4 and 2 L and inhalation flows of 10, 28.3, 60, and 90 L/min. The %nominal dose emitted was consistent between the various flow rates and inhalation volumes of 4 and 2L. The particle size distribution was measured using an Anderson Cascade Impactor (ACI) combined with a mixing inlet valve to measure particle size distribution at inhalation flow rates below 30 L/min. The particle size distribution of formoterol from Atimos Modulite was measured using inhalation flows of 15, 28.3, 50, and 60 L/min with and without different spacers, Aerochamber and Volumatic. The mean fine particle dose (%nominal dose) through an Atimos without spacer were 53.52% (2.51), 54.1% (0.79), 53.37% (0.81), 50.43% (1.92) compared to Aerochamber 63.62% (0.44), 63.86% (0.72), 64.72% (0.47), 59.96% (1.97) and Volumatic 62.40% (0.28),63.41% (0.52), 64.71% (0.61), 58.43% (0.73), respectively. A small decrease in the fine particle dose was observed as the inhalation flow increased, but this was not significant. The respective mean mass aerodynamic diameter (MMAD) increased as the flow rate was increased from 15 of 60 L/min. Results also suggests that the use of spacers provides better lung deposition for patients with problems using MDI. The dose emission from the Foradil Aeroliser was determined using inhalation volumes of 4 and 2 L, at inhalation flows of 10, 15, 20, 28.3, 60, and 90 L/min plus two inhalations per single dose. The %nominal dose emitted using 2 L inhalation volume was approximately half when compared to results obtained using inhalation volume of 4 L. A significantly (p<0.001) higher amount of drug was also emitted from Easyhaler® at inhalation volume of 4 L through flow rates of 10, 20, 28.3, 40, and 60 L/min compared 2 L. Similar results were observed through Oxis Turbuhaler at inhalation flow rates of 10, 20, 28.3, 40, and 60 L/min. Comparative studies were also carried out to evaluate the particle size distribution of formoterol through the DPIs. The nominal fine particle dose through Aeroliser using inhalation flows of 10, 20, 28.3, 60 and 90 L/min were 9.23%, 14.70 %, 21.37%, 28.93%, and 39.70% for the 4 L and 4.17%, 5.55%, 7.28%, 8.41%, and 11.08% for the 2 L, respectively. The respective MMAD significantly (p<0.001) decreased with increasing flow rates. Aeroliser performance showed significant (p<0.001) increase in the % nominal fine particle dose for two inhalations compared to one inhalation at both 4 and 2 L. The Easyhaler was measured using inhalation flows of 10, 20, 28.3, 40, 60 L/min. The nominal fine particle dose were 19.03%, 27.09%, 36.89%, 49.71% and 49.25% for the 4 L and 9.14%, 15.44%, 21.02%, 29.41%, 29.14% for the 2 L, respectively. The respective MMAD significantly (p<0.001) decreased with increasing flow rates. Easyhaler performance at both 4 and 2 L showed no significant differences between one and two inhalations at low flow rates (10, 20, 28.3), but this was significant (p<0.05) at higher flow rates (40 and 60 L/min). The Oxis Turbuhaler was also measured using inhalation flows of 10, 20, 28.3, 40, 60 L/min. The nominal fine particle dose were 12.87%, 24.51%, 28.25%, 34.61%, 40.53% for the 4 L and 8.55%, 15.31%, 21.36%, 19.53%, 22.31% for the 2 L, respectively. Turbuhaler performance showed significant (p<0.05) differences between one and two inhalations at varying flow rates 2 L inhalation volumes, but not at 4 L. The use of Foradil Aeroliser delivers small particles as the Oxis Turbuhaler using two inhalations hence delivering formoterol deep into the lungs. Also, this thesis shows that high flow resistance of Turbuhaler will indeed influence the ability of patients with severe asthma or children to use the system. Beside, Easyhaler produced the highest drug delivery to the lungs, thus, making it a more desirable system to use, especially for children and asthma sufferers.

The pore saturation of natural gas hydrate in sediments is a key parameter for estimating hydrate resources in a reservoir. For a better understanding of gas hydrate distribution, the experimental study of the pore saturation of methane hydrate in sediments from a hydrate reservoir in the Eastern Nankai Trough have been carried out. In total, eleven samples, comprising sand, silty sand, silt, and representative of the main sediment types identified in the Eastern Nankai trough, were tested. The results obtained clearly indicate a particle size and clay content dependent trend: almost 100% of pores were saturated with methane hydrate in sand when little silt and clay were present, decreasing to ~ 13% in silty sand (sand 54%, silt 41% and clay 5%), and ~ 4% in clayey silt. These results are generally consistent with NMR logging results for high-saturation samples, but somewhat different for samples with medium or low saturation levels.

This work reports the results of a systematic study of the factors that affect the bridging behaviour of bagasse. It shows that traditional bulk solids theory is inappropriate for predicting bagasse flow mainly because of the impossibility of obtaining a reliable measure of internal friction. It demonstrates the significant influence of fibre length and moisture content on its handling charateristics. Correlations of pertinent bulk properties such as compactibility, tensile strength, surface friction and translation of vertical into horizontal pressure have been developed. These were derived as a result of measurements in equipment that was designed for the purpose. Finally, an empirical model utilising these correlations is proposed by which the likelihood of bridge formation in any piece of bagasse handling equipment can be determined. The validity of the model is assessed by comparison with bridging tests that were performed under controlled conditions. / Thesis (Ph.D.)-University of Natal, 1996