Micronisation of active pharmaceutical ingredients (APIs) to achieve desirable quality attributes for formulation preparation and drug delivery remains a major challenge in the pharmaceutical sciences. It is therefore important that the relationships between crystal structure, the mechanical properties of powders and their subsequent influence on processing behaviour are well understood. The aim of this project was therefore to determine the relative importance of particle attributes including size, crystal quality and morphology on processing behaviour and the characteristics of micronised materials. It was then subsequently intended to link this behaviour back to crystal structure and the nature of molecular packing and intermolecular interactions within the crystal lattice enabling the identification of some generic rules which govern the quality of size reduced powders. In this regard, different sieve fractions of lactose monohydrate and crystal variants of ibuprofen and salbutamol sulphate (size, morphology and crystal quality) were investigated in order to determine those factors with greatest impact on post-micronisation measures of particle quality including particle size, degree of crystallinity and surface energy. The results showed that smaller sized feedstock should typically be used to achieve ultrafine powders with high crystallinity. This finding is attributed to the reduced number of fracture events necessary to reduce the size of the particles leading to decreases in milling residence time. However the frequency of crystal cracks is also important, with these imperfections being implicated in crack propagation and brittle fracture. Ibuprofen crystals with a greater number of cracks showed a greater propensity for comminution. Salbutamol sulphate with a high degree of crystal dislocations however gave highly energetic powders, with reduced degree of crystallinity owing to the role dislocations play in facilitating plastic deformation, minimising fragmentation and extending the residence of particles in the microniser. Throughout these studies, morphology was also shown to be critical, with needle like morphology giving increased propensity for size reduction for both ibuprofen and salbutamol sulphate, which is related to the small crack propagation length of these crystals. This behaviour is also attributed to differences in the relative facet areas for the different morphologies of particles, with associated alternative deformation behaviour and slip direction influencing the size reduction process. Molecular modelling demonstrated a general relationship between low energy slip planes, d-spacing and brittleness for a range of materials, with finer particle size distributions achieved for APIs with low value of highest d-spacings for identified slip planes. The highest d-spacing for any material can be readily determined by PXRD (powder x-ray diffraction) which can potentially be used to rank the milling behaviour of pharmaceutical materials and provides a rapid assessment tool to aid process and formulation design. These studies have shown that a range of crystal properties of feedstock can be controlled in order to provide micronised powders with desirable attributes. These include the size, morphology and the density of defects and dislocations in the crystals of the feedstock. Further studies are however required to identify strategies to ensure inter-batch consistency in these attributes following crystallisation of organic molecules.

A new continuous one-dimensional sedimentation model incorporating a new continuous flocculation model that considers aggregation and fragmentation processes was derived and tested. Additionally, a new procedure to model sediment particle size distribution (PSD) was derived. Basic to this development were three different parametric models: Jaky, Fredlund and the Gamma probability distribution (GPD) were chosen to fit three different glass micro-spheres PSDs having average particle sizes of 7, 25 and 35 microns. The GPD provided the best fit with the least parameters. The bimodal GPD was used to fit ten sediment samples with excellent results (< 5% average error). A continuous flocculation model was derived using the method of moments for solving the continuous Smoluchowski coagulation equation with fragmentation. The initial sediment PSD was modeled using a bimodal GPD. This new flocculation model resulted in a new general moments’ equation that considers aggregation and fragmentation processes, which is represented by a system of ordinary differential equations. The model was calibrated using a genetic algorithm with initial and flocculated PSDs of four sediment samples and four anionic polyacrylamides flocculants. The results show excellent correlation between predicted and observed values (R2 > 0.9878). A new continuous one-dimensional sedimentation model that resulted in a scalar hyperbolic conservation law was derived from the well-known Kynch kinematic sedimentation model. The model was calibrated using column tests results with glass micro-spheres particles. Two different glass microspheres particle size distributions (PSDs) were used with average diameters of 7 and 37 microns. Excellent values of coefficient of determination (R2 > 0.89, except for one test replicate) were obtained for both the small and large glass micro-spheres PSDs. These results suggest that the proposed sedimentation model can be expanded to model the sedimentation process inside a sediment pond.

Widefield surface plasmon resonance (WSPR) microscopy provides high resolution imaging of interfacial interactions. We report the application of the WSPR imaging system in the study of the interaction between keratinocytes and liquid crystals (LC). Imaging of fixed keratinocytes cultured on gold coated surface plasmon substrates functionalized with a thin film of liquid crystals was performed in air using a 1.45NA objective based system. Focal adhesion of the cells adhered to glass and LC were further studied using immunofluorescence staining of the vinculin. The imaging system was also simulated with 2x2 scattering matrix to investigate the optical reflection of the resonant plasmonic wave via the glass/gold/cell and glass/gold/LC/cell layers. WSPR imaging indicated that keratinocytes are less spread and formed distinct topography of cell-liquid crystal couplings when cultured on liquid crystal coated substrates. The simulation indicates that glass/LC shifted the surface plasmon excitation angle to 75.39 degrees as compared to glass/air interface at 44 degrees . The WSPR microcopy reveals that the cells remodelled their topography of adhesion at different interfaces.

The present research is concerned with developing analysis methods for analyzing and exploring finite-amplitude elastic wave propagation through periodic media. Periodic arrangements of materials with high acoustic impedance contrasts can be employed to control wave propagation. These systems are often termed phononic crystals or metamaterials, depending on the specific design and purpose. Design of these systems usually relies on computation and analysis of dispersion band structures which contain information about wave propagation speed and direction. The location and influence of complete (and partial) band gaps is a particularly interesting characteristic. Wave propagation is prohibited for frequencies that correspond to band gaps; thus, periodic systems behave as filters, wave guides, and lenses at certain frequencies. Controlling these behaviors has typically been limited to the manufacturing stage or the application of external stimuli to distort material configurations. The inclusion of nonlinear elements in periodic unit cells offers an option for passive tuning of the dispersion band structure through amplitude-dependence. Hence, dispersion analysis methods which may be utilized in the design of nonlinear phononic crystals and metamaterials are required. The approach taken herein utilizes Bloch wave-based perturbation analysis methods for obtaining closed-form expressions for dispersion amplitude-dependence. The influence of material and geometric nonlinearities on the dispersion relationship is investigated. It is shown that dispersion shifts result from both self-action (monochromatic excitation) and wave-interaction (multi-frequency excitation), the latter enabling dynamic anisotropy in periodic media. A particularly novel aspect of this work is the ease with which band structures of discretized systems may be analyzed. This connection enables topology optimization of unit cells with nonlinear elements. Several important periodic systems are considered including monoatomic lattices, multilayer materials, and plane stress matrix-inclusion configurations. The analysis methods are further developed into a procedure which can be implemented numerically with existing finite-element analysis software for analyzing geometrically-complex materials.

The iron ore mining industry makes use of various processes that result in the release of airborne dust into the surrounding atmosphere where workers are exposed, to produce a final product. The deposition in the lung and toxicological influences of airborne dust can be determined by their physical- and chemical characteristics. The Occupational Health and Safety Act (OHSA) regulations for hazardous chemical substances have no current system of how the physical- and chemical properties of particulates originating from specific areas will influence a worker‘s exposure and health, especially for ultrafine particles (UFP). It is therefore imperative to characterise airborne dust containing micrometer and UFP size particles originating from specific areas to determine if there are physical- and chemical characteristics that may or may not have an influence on the workers‘ health. Aim: This pilot study is aimed at the physical- and chemical characterisation of the airborne iron ore dust generated at the process areas of an opencast iron ore mine. Method: Sampled areas included the Primary-secondary crusher, Tertiary crusher, Quaternary crusher and Sifting house. Gravimetric sampling was conducted through the use of static inhalable- and respirable samplers in conjunction with optical- and condensation particle counters that were placed near airborne dust- emitting sources. Physical- and chemical characterisation was done with the use of scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results: The results found in the study indicate high mass concentration levels of inhalable dust at all four process areas, as well as high levels of respirable dust found at the primary- secondary crusher area. Particle size distribution optical particle counter (OPC) results indicate that the majority of particles at all four process areas are in the region of 0.3 μm in size. Condensation particle counter (CPC) results integrated with OPC results indicate that at the primarysecondary and Tertiary crushers the majority of particles are found to be in the size fraction <0.3 μm. SEM analysis indicates that particle agglomeration largely occurs in the airborne iron ore dust. Particle splinters originating from larger particle collisions and breakages are present in the airborne dust. EDS analysis indicates that the elemental majority of the airborne iron ore dust consists of iron, oxygen, carbon, aluminium, silicon, potassium and calcium. The elemental percentages differ from each process area where an increase in iron and decrease in impurities can be seen as the ore moves through the beneficiation process from the Primary-secondary crusher to the Sifting house. Conclusion: The results obtained from the physical- and chemical properties of the airborne iron ore dust indicate high risk of over-exposure to the respiratory system, as well as possible ultrafine particle systemic exposure, that may overwhelm the physiological defense mechanisms of the human body and lead to reactive oxygen species (ROS) formation and the development of pathologies such as siderosis, silicasiderosis and lung cancer. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2014

<p>U savremenom uzgoju živine i svinja sme&scaron;e se retko koriste u pra&scaron;kastom obliku<br />već se uglavnom peletiraju nakon ume&scaron;avanja pojedinačnih sastojaka. Pri<br />peletiranju dolazi do naru&scaron;avanja granulacije sme&scaron;e, odnosno do gotovo<br />potpunog eliminisanja krupnih čestica, kao i do nastajanja velike količine najsitnijih čestica. U okviru istraživanja u ovoj doktorskoj disertaciji ispitivan je uticaj promene odabranih parametara mlevenja i peletiranja na granulaciju čestica od kojih su pelete sačinjene. Cilj je bio da se utvrdi kombinacija parametara koja doprinosi povećanju sadržaja krupnih čestica, &scaron;to je značajno u ishrani živine, odnosno da se utvrdi kombinacija parametara koja će u &scaron;to većoj meri uvećati sadržaj čestica srednje veličine i umanjiti udeo najsitnijih čestica, &scaron;to je značajno u ishrani svinja. Pri tome je određivan i kvalitet peleta, koji ne sme biti značajnije naru&scaron;en, kao i potro&scaron;nja energije pelet prese za koju je poželjno da je &scaron;to niža.<br />Nezavisni parametri peletiranja bili su granulacija kukuruznog mliva, rastojanje (zazor) između valjaka i matrice pelet prese, debljina matrice pelet prese i sadržaj vode materijala koji se vodi na peletiranje. Istraživanje je podeljeno u dve faze, gde je u prvoj za usitnjavanje primenjen mlin čekićar, a u drugoj mlin sa valjcima. Na oba uređaja prizvedene su po tri granulacije mliva, pri čemu se granulacija ukrupnjava od najsitnijeg mliva dobijenog na mlinu čekićaru do najkrupnijeg mliva dobijenog na mlinu sa valjcima. U prvoj fazi tri granulacije mliva dobijene na mlinu čekićaru su peletirane u kombinaciji sa tri zazora valjci-matrica (0,30; 1,15 i 2,00 mm) i tri sadržaja vode materijala (14,5%, 16,0% i 17,5%), a u drugoj fazi tri granulacije mliva dobijene na mlinu sa valjcima peletirane su u kombinaciji sa tri debljine matrice (24, 30 i 36 mm) i tri sadržaja vode materijala (14,5%, 16,0% i 17,5%). Dakle, u obe faze su varirana tri parametra na tri nivoa pri čemu je primenjen Box-Behnken eksperimentalni dizajn. Zavisno promenljive karakteristike (odzivi) bili su temperatura matrice pelet prese, specifična potro&scaron;nja energije pelet prese, udeo pra&scaron;ine u peletama, stepen želatinizacije skroba, tvrdoća, stepen otiranja i nasipna masa peleta, kao i granulacija materijala nakon peletiranja. Za svaki od pomenutih odziva definisan je polinom (model) drugog reda. Dobijeni modeli upotrebljeni su za optimizaciju procesa peletiranja sa ciljem da se postigne željena granulacija peletiranog materijala, uz &scaron;to bolji kvalitet peleta i uz &scaron;to manju potro&scaron;nju energije.<br />U istraživanju je utvrđeno da mliva sa približno istom vredno&scaron;ću geometrijskog srednjeg prečnika, dobijena na mlinu čekićaru i mlinu sa valjcima, imaju značajno različitu raspodelu veličine čestica. Na mlinu čekićaru dobija se &scaron;ira raspodela, sa većim sadržajem najkrupnijih i najsitnijih čestica, u poređenju sa mlinom<br />sa valjcima. Za proizvodnju mliva približno istog geometrijskog srednjeg prečnika, a pogotovo mliva sa relativno sličnom raspodelom veličine čestica,<br />potro&scaron;nja energije kod mlina sa valjcima značajno je manja u poređenju sa mlinom<br />čekićarom. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Potvrđeno je da peletiranje uzrokuje veliki intenzitet usitnjavanja čestica bez obzira na primenjene parametre. Međutim, određene kombinacije parametara mogu doprineti značajnijem očuvanju krupnih čestica. Parametar peletiranja koji najvi&scaron;e doprinosi<br />povećanju udela krupnih čestica u peletama je granulacija mliva koje se upućuje na<br />peletiranje. &Scaron;to je krupnija granulacija, udeo krupnih čestica u peletama će biti veći.<br />Rezultati optimizacije procesa peletiranja u prvoj fazi ukazuju da je u pogledu proizvodnje peletirane hrane za živinu, kada je poželjno očuvanje određene količine krupnih čestica, potrebno primeniti krupno mlevenje na mlinu čekićaru, uz<br />pode&scaron;avanje zazora između valjaka i matrice od 2 mm i uz sadržaj vode materijala od 17,5%. U drugoj fazi optimizacijom je utvrđeno da je potrebno koristiti debljinu matrice od 30 mm, najkrupniju granulaciju mliva na mlinu sa valjcima i vlagu od 17,5%. Pri proizvodnji peletirane hrane za živnu povoljnije je koristiti mlin čekićar, s obzirom da je utvrđeno da su čestice mliva dobijenog na čekićaru otpornije na usitnjavanje tokom peletiranja od čestica dobijenih na mlinu sa valjcima &scaron;to omogućuje očuvanje većeg broja krupnih čestica tokom peletiranja. Povećanje &scaron;irine zazora valjci-matrica nije poželjno prilikom peletiranja hrane za svinje jer se povećava intenzitet usitnjavanja čestica, a time i udeo najsitnije frakcije čestica. Sličano je i sa povećanjem debljine matrice. U prvoj fazi istraživanja, rezultati optimizacije pokazuju da je u cilju povećanja udela frakcija čestica srednje veličine (630 &ndash; 1600 &mu;m), kao i smanjenja sadržaja najsitnijih čestica (&lt; 125 &mu;m), potrebno primeniti najsitnije mlevenje na mlinu čekićaru, najveći sadržaj vode materijala (17,5%), dok zazor između valjaka i matrice treba podestiti da bude ne&scaron;to veći od 0,30 mm. I u drugoj fazi istraživanja optimizacija je ukazala da je najveći udeo čestica srednje veličine (630 &ndash;<br />1600 &mu;m), kao i najmanji udeo čestica &lt; 125 &mu;m, ostvaren pri peletiranju najsitnijeg<br />mliva dobijenog na mlinu sa valjcima. Pri tome sadržaj vode je potrebno podesiti na<br />17,5%, dok debljina matrice treba biti oko 28 mm.<br />Pri predloženim optimalnim parametrima peletiranja ostvaren je zadovoljavajući<br />kvalitet peleta, a potro&scaron;nja energije pelet prese bila je na prihvatljivom nivou.</p> / <p>In modern poultry and swine breeding, animal feed is rarely used in powder form but mainly pelleted after mixing of different ingredients. During pelleting process, granulation of the feed is compromised, i.e. coarse particles are<br />almost completely destroyed and the content of fine particles is strongly<br />increased. This doctoral thesis investigated the impact of changes in selected grinding and pelleting parameters on granulation of particles after pelleting. The goal was to achieve the quantity of coarse particles in pellets to be as high as possible, which is important in poultry nutrition. Another goal was to determine the combination of parameters that will increase, as much as possible, the content of particles medium in size and reduce the share of the smallest particles, which is important in swine nutrition. At the same time quality of the pellets must not be significantly degraded and energy consumption of pellet press should be as low as possible.<br />Independent pelleting parameters were corn granulation after grinding, the distance (gap) between the rollers and the die of pellet presses (roller-die gap), the thickness<br />of the pellet press die (die thickness) and the water content of pelleted material. The study was divided in two stages. In the first stage the corn was ground using a hammer mill and in the second stage, roller mill was used. Three different granulations were produced on both mills. Coarseness of the ground material increased from the finest material produced using the hammer mill to the coarsest material obtained at the roller mill. In the first stage, three different granulations produced at the hammer mill were pelleted in combination with three different roller-die gaps (0.30, 1.15 and 2.00 mm) and three different water contents of material (14.5%, 16.0% and 17.5%). In the second stage three different granulations produced at the roller mill were pelleted in combination with three different die thicknesses (24, 30 and 36 mm) and three different water content of material (14.5%, 16.0% and 17.5%). Thus, three parameters were varied at three levels in both stages and experiments were designed according to Box-Behnken design. Depended variables (responses) were: temperature of the pellet press die, specific energy consumption of pellet press, dust content in pellets, degree of starch gelatinization,&nbsp; particle size of the material after pelleting. For each of the responses, a second order polynomial model was defined and used for optimization of the pelleting process. It was determined that particle size distribution of material with similar geometric mean diameter, obtained with hammer mill and roller mill, is significantly different from each other. Hammer mill produced higher quantity of the coarsest and the finest particles comparing to roller mill. Energy consumption of roller mill for grinding to similar particle size distribution or similar geometric mean diameter is lower compared to hammer mill. Even though it was determined that secondary grinding of particles during pelleting is inevitable, certain combinations of pelleting parameters may contribute to significant preservation of large particles and to reduction of quantity of small particles. Results of optimization in the first stage indicated that for the production of pelleted poultry feed, when certain amount of coarse particles should be preserved, it is necessary to apply coarse grinding on hammer mill, with the roller-die gap of 2 mm and with material water content of 17.5%. In the second stage it was determined that it is necessary to use die with thickness of 30 mm, coarsest granulation at the roller mill and material water content of 17.5%. In the production of pelleted poultry feed it is better to use a hammer mill since it was found that the particles obtained on hammer mill are more resistant to secondary grinding than the particles obtained with the roller mill. Roller-die gap increase is not desirable during pelleting of swine feed because it increases secondary grinding, and thus the proportion of the smallest particles. Similar effect has an increase of the die thickness. In the first stage of the study, the results of the optimization showed that the largest quantity of medium-sized particles (630 &ndash; 1600 &mu;m), and the lowest quantity of the smallest particles (&lt; 125 &mu;m), were achieved with the finest grinding on the hammer mill. At the same time water content of 17.5% should be applied, while the roller-die gap should be close to 0.30 mm. In the second stage of the study, the largest quantity of medium-sized particles, and the lowest quantity of the smallest<br />particles, was achieved with the finest grinding on the roller mill. According to the optimization results, the water content should be set to 17.5%, while die thickness should approx. 28 mm. With the proposed optimal parameters, satisfactory pellet quality was achieved, and energy consumption of the pellet<br />presses was at an acceptable level.</p>

While realistic in vitro testing of dry powder inhalers (DPIs) can be used to establish in vitro–in vivo correlations (IVIVCs) and predict in vivo lung doses, the aerodynamic particle size distributions (APSDs) of those doses and their regional lung deposition remains unclear. Four studies were designed to improve testing centered on the behavior of Novolizer®. Different oropharyngeal geometries were assessed by testing different mouth-throat (MT) models across a realistic range of inhalation profiles (IPs) with Salbulin® Novolizer®. Small and large Virginia Commonwealth University (VCU) and Oropharyngeal Consortium (OPC) models produced similar ranges for total lung dose in vitro (TLDin vitro), while results for medium models differed significantly. While either group may be selected to represent variations in oropharyngeal geometry, OPC models were more difficult to use, indicating that VCU models were preferable. To facilitate simulation of human IPs through DPIs, inhalation profile data from a VCU clinical trial were analyzed. Equations were developed to represent the range of flow rate vs. time curves for use with DPIs of known airflow resistance. A new method was developed to couple testing using VCU MT models and simulated IPs with cascade impaction to assess the APSDs of TLDin vitro for Budelin® Novolizer®. This method produced IVIVCs for Budelin’s total lung dose, TLD, and was sufficiently precise to distinguish between values of TLDin vitro and their APSDs, resulting from tests using appropriately selected MT models and IPs. For example, for slow inhalation, TLD values were comparable in vivo and in vitro; TLDin vitro ranged from 12.2±2.9 to 66.8±1.7 mcg aerosolized budesonide while APSDs in vitro had mass median aerodynamic diameters of 3.26±0.27 and 2.17±0.03 µm, respectively. To explore the clinical importance of these variations, a published computational fluid dynamic (CFD) model was modified and coupled to accept the output of realistic in vitro tests as initial conditions at the tracheal inlet. While simplified aerosol size metrics and flow conditions used to shorten CFD simulations produced small differences in theoretical predictions of regional lung deposition, the results broadly agreed with the literature and were generally consistent with the median values reported clinically for Budelin.

The biochar is a promissor product for the soil improvement as physical, chemical and hydraulic properties. However, there is a lack of information about the influence of biochar rate, particle size, depth, soil texture and time of interaction on tropical climate. This is one of the first studies that analyse these properties under tropical condition. The objective of this study was analyze the effect of biochar (BC) rate and particle size on soil chemical, physical and hydraulic properties on tropical condition. Was acessed the effect BC rate (6.25, 12.5 and 25 Mg ha-1) in Clay loam and sandy soil under laboratory condition on chemical properties (C, N and C/N ratio), physical properties (bulk density, porosity and pore size distribution) and hydraulic properties (water holding capacity and water available content). In field condition, the effect of the Filter cake (FC) and FC + BC rate (6.25, 12.5 and 25 Mg ha-1) was studied in two depth (0-10 and 10-20 cm) in two times of interaction (9 and 18 months) on soil physical (bulk density, porosity and pore size distribution and aggregate stability) and hydraulic properties (water holding capacity and water available content and hydraulic conductivity). To verify the best BC particle size to be applied on the soil, a third study was developed to test the effect of BC particle size (< 0.15; 0.15-2 and > 2mm) in clay loam and sandy soil and to analyze its effects on soil chemical, physical and hydraulic properties. In the first study (effect of BC rate on laboratory condition) a positive effect of BC rate on water availability, microporosity, and on water retention was found, especially for clay loam soil at high BC application, but this influence did not occur for sandy soil, possibly due to the short time of interaction. In the second study (effect of BC rate and FC on physical, chemical and hydraulic properties) the bulk density slightly decreased, and the porosity increased after nine months of interaction upon FC + BC 25 Mg ha-1. However, after 18 months, the FC + BC amount altered the pore size distribution with an increase of micropores, aggregate stability, available water content and its alteration was dependent on the FC + BC rate. Nevertheless, this effect was not verified in the hydraulic conductivity (Kfs). The time of interaction contributes to increasing the Kfs, and the reduction of Kfs was found with the increase of FC + biochar rate, especially in higher amount FC + BC (25 Mg ha-1) of biochar. In the third work (effect of biochar particle size on chemical and physical and hydraulic properties) total carbon content increased mainly in sandy soil compared to control treatment, the highest carbon amount was obtained in the biochar size 0.15-2 mm in loamy soil and < 0.15 mm in sandy soil, while TN content and C/N ratio increased slightly with reduction of the biochar particle size in both soils. These results demonstrated that biochar particle size is crucial for water retention, water availability, pore size distribution and C sequestration. It is evident that is possible to save irrigation water and improve soil chemical and physical properties by applying biochar. / O biocarvão (BC) é um produto promissor para a melhoria da qualidade química, física, e hidráulica do solo. No entanto, faltam estudos sobre a influência da dose de BC, tamanho de partícula, profundidade de aplicação, efeitos sobre a textura do solo e tempo de interação em condições de clima tropical. Este é um dos primeiros trabalhos que avaliam essas propriedades em solos sob condições tropicais. O objetivo deste estudo foi analisar o efeito da dose de BC e do tamanho de partículas nas propriedades químicas, físicas e hidráulicas do solo em condição tropical. Avaliou-se o efeito da dose de BC (6,25; 12,5 e 25 Mg ha-1) em solo franco argiloso e arenoso, em condições de laboratório sobre as propriedades químicas (C, N e C/N), físicas (densidade do solo, porosidade e distribuição do tamanho dos poros) e hidráulicas do solo (capacidade de retenção de água e teor de água disponível). Em condição de campo foi estudado o efeito da torta de filtro e dose de BC (6,25, 12,5 e 25 Mg ha-1) mais torta de filtro (TF) em duas profundidades (0-10 e 10-20 cm) e em dois tempos de interação (9 e 18 meses) sobre as propriedades físicas (densidade do solo, porosidade, distribuição do tamanho dos poros e estabilidade de agregados) e hidráulicas do solo (capacidade de retenção de água, teor de água disponível e condutividade hidráulica). A fim de verificar o melhor tamanho de partícula de BC a ser aplicado ao solo foi desenvolvido um terceiro estudo no qual foi avaliado o efeito do tamanho de partículas de BC (< 0,15; 0,15-2 e > 2mm) em solo franco argiloso e arenoso sobre as mesmas propriedades químicas, físicas e hidráulicas do solo avaliadas no primeiro estudo. No estudo da influência de dose de BC em condição de laboratório, foi verificado efeito positivo da dose de BC na disponibilidade de água, microporosidade e retenção de água, especialmente para solo franco argiloso com alta aplicação de BC, mas essa influência não ocorreu, para solos arenosos, possivelmente devido ao curto período de interação. No segundo estudo (efeito da dose de BC+TF) verificou-se que a densidade diminuiu ligeiramente e a porosidade aumentou após nove meses de interação com TF + BC 25 Mg ha-1 e após 18 meses, a quantidade de BC+TF alterou a distribuição do tamanho dos poros aumentando a quantidade de microporos, melhorando a estabilidade do agregado e o conteúdo de água disponível (CAD). O efeito da dose não foi verificado para condutividade hidráulica (Kfs), porém o tempo de interação contribuiu para aumentar os Kfs. Além disso, uma redução de Kfs foi encontrada com o aumento da taxa de BC + TF, especialmente na maior quantidade de TF + BC (25 Mg ha-1) de biocarvão. No terceiro estudo, (efeito do tamanho das partículas de BC nas propriedades químicas, físicas e hidráulicas), o teor total de carbono aumentou principalmente em solo arenoso comparado ao tratamento controle, a maior quantidade de carbono foi obtida no tamanho do BC 0,15-2 mm em solo argiloso e < 0,15 mm em solo arenoso, enquanto o teor de TN e a relação C/N aumentaram ligeiramente com a redução do tamanho das partículas de BC em ambos os solos. Estes resultados demonstraram que o tamanho das partículas de BC é crucial para a retenção, disponibilidade de água, distribuição de tamanho de poros e sequestro de carbono. Esses estudos demonstraram que é possível economizar água de irrigação e melhorar as propriedades químicas e físicas do solo por meio da aplicação do biocarvão.

PhD thesis - Faculty of Science / The main aim of this thesis has been to study the way in which Fe(III) and Co(II) incorporation into Si-MCM-41 synthesis gels affects the properties of the unmodified material. Another aim was to investigate the influence of these hetero-atoms on the dispersion and particle size distribution as well as the catalytic activity of supported Au nanoparticles in the CO oxidation reaction. Si-MCM-41 has been successfully synthesized in this work using mixtures containing CTAB as a structure-directing agent (SDA) and water-glass as a SiO2 source. Replacement of water-glass with pre-calcined Si-MCM-41 for SiO2 source in the secondary synthesis step has produced Si-MCM-41 with improved structural properties (XRD, HRTEM and Raman spectroscopy), including restructured and more crystalline pore walls (Raman spectroscopy). The conventional shortcomings of Si-MCM-41 as a support for catalyticallyactive (transition) metal components such as low hydrothermal stability, low PZC, lack of cation exchange capacity and no reducibility have been partially addressed by modification with Fe(III) and Co(II). The premodification was achieved both during framework synthesis and after synthesis by the incipient wetness impregnation (IWI) method. As opposed to the one-pot synthesis of metal-containing derivatives, the IWI method gave materials with high metal loadings and maximal retention of the properties of pristine Si-MCM-41. On the other hand, metal incorporation during synthesis to a loading of ~8.8 wt% using aqueous solutions of metal precursors showed some collapse of the mesostructure. Consequently methods were sought to incorporate this amount of metal (and up to double, i.e., 16 wt%) with maximal retention of the MCM-41 characteristics. These methods included (i) using Si-MCM-41 as a SiO2 source, (ii) dissolving the metal precursors in an acid solution before inclusion into the synthesis gel, and (iii) using freshly precipitated alkali slurries of the metal precursors. The first method produced a highly ordered 16wt% Fe-MCM-41 material with excellent reducibility (TPR showed three well-resolved peaks) and pore-wall structure (Raman spectroscopy). Like the aqueous route, the acid-mediated metal incorporation route did not produce ordered materials at metal contents of ~16 wt%. The base precipitate route produced highly ordered composite materials up to 16 wt% metal content, with characteristics similar to those of Si-MCM-41 (XRD, BET and HRTEM), although some metal phases were observed as a separate phase on the SiO2 surface. Thus, metal-containing MCM-41 materials could be obtained with conservation of MCM-41 mesoporosity. Raman spectroscopic studies have shown that the effect of transition metal incorporation in MCM-41-type materials is to strengthen the pore walls (shift of Si-O-Si peaks to higher frequencies), while TPR studies revealed that the essentially neutral framework of Si-MCM-41 could be rendered reducible by transition metal incorporation. Gold-containing mesoporous nanocomposites were prepared by both direct synthesis and post-synthetically. Catalysts prepared by direct hydrothermal synthesis were always accompanied by formation of large Au particles because of the need to calcine the materials at 500 oC in order to remove the occluded surfactant template. The presence of transition metal components in Me-MCM-41 (Me = Fe and Co) has been found to play a significant role in the particle size distribution and also the dispersion of Au nanoparticles when these materials were used as supports. In general, a base metal-containing support was found to produce smaller Au nanoparticles than the corresponding siliceous support. It has been proposed that the transition metal components serve as anchoring or nucleation sites for the Au nanoparticles, which are likely to sinter during calcination. The anchoring sites thus retard the surface mobility of Au at calcination temperatures above their TTammann. The use of the Au/Me-MCM-41 materials as catalysts in the CO oxidation reaction has led to the following observations: (i) catalyst on metal-containing supports showed better activity than those on Si-MCM-41, probably due to the induced reducibility in metal-MCM-41, (ii) catalysts prepared by direct synthesis showed inferior activity owing to large Au particles, (iii) increasing Au content improves the catalytic performance, (iv) increasing the Fe content of the support at constant Au improves the catalytic performance, and (v) changing the base metal component of the support from Fe to Co led to a significant improvement in catalytic activity. The similarity of the apparent activation energies (Ea) for the 5 wt% Au-containing 5 wt% Fe- and 5 wt% Co-MCM-41 suggested that the difference in catalytic activity is associated with the number of active sites possessed by each catalyst system. The observed order of catalytic activity of these 5 wt% Au-containing systems in terms of the support type is: Co-MCM-41 > Fe-MCM-41 > Si-MCM-41. This was further supported by the average Au particle size, which, in terms of the support, followed the order Co-MCM-41 < Fe-MCM-41 < Si-MCM-41. Thus, metal-support interactions between Au and MCM-41 have been enhanced by introducing Fe(III) and Co(II), which also induced framework charge, ion exchange capacity (IEC) and reducibility in the neutral siliceous support.

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 1&#181;m 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.