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Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains viii, 31 p. : ill. (some col.). Includes four zip file programs. Includes abstract. Includes bibliographical references (p. 26-27).

Thesis (M. Env. St.)--University of Adelaide, 1984. / Includes bibliographical references (leaves 273-308).

Microspheres are spherically shaped particles within the size range of 1-1000 μm in diameter. Due to the their small size and round shape, microspheres show many advantages in various applications such as pharmaceuticals, composites and coatings. The microspheres can be customized to fit a specific application and are manufactured in various forms such as solid, hollow and encapsulating. Encapsulating cellulose microspheres have been produced in this project by the emulsionsolvent evaporation technique. The purpose of this study was to further investigate the possibility of producing encapsulating microspheres with a size range of 10-50 μm that will have a high encapsulation. A second purpose of this study was optimizing the emulsifier system for the preparation of these spheres. This has been accomplished by varying several process parameters such as type of emulsifiers and solvents to study the effect on morphology and encapsulation efficiency. The analyses of the spheres were performed with optical microscopy, thermal gravimetric analyzer (TGA) and scanning electron microscopy (SEM). The emulsifier type and concentration affected the encapsulation and size distribution but had no direct effect on the internal and external structure, which was multi-cellular and porous, respectively. The highest encapsulation in relation to average size was obtained with 0.1 v/v- % of the emulsifier mixture Emulsifier 1 (E1)/Emulsifier 2 (E2) (70/30 %). The solvent used to dissolve the polymer had a direct effect on encapsulation, a combination of Solvent 2 (S2) and Solvent 1 (S1) proved best for the three tested cellulose derivatives with low, medium and high number average molecular weight. The solvent also had an effect on the internal structure of the microspheres, becoming more core-shell when using the S1/S2 combination.

Colloidal processing has been widely used for many industrial application. Electrophoretic deposition (EPD) is an important colloidal technique, which plays an important role in the fabrication of organic-inorganic composites. In this work, advanced dispersing agents with excellent adsorption, dispersion and film forming properties have been developed. The adsorption mechanism and the deposition kinetics of EPD have been studied. It is shown that catechol and salicylic groups of dispersants can form chelation bonding with metal atoms on inorganic particle surface and provide particle charging, dispersion and deposition. The aromatic dispersants can adsorb on carbon nanotubes due to π-π interactions. The long chain ionic polymeric dispersants were investigated, which provide efficient electrosteric stabilization. The film forming properties of dispersants allow dispersants with dispersed materials to deposit and form composite films on the substrate. Universal dispersing agents have been developed for the colloidal processing. These dispersants show possibilities to adsorb and disperse various organic and inorganic materials and pave the way for the fabrication of multi-functional materials for various applications. The composite materials, prepared using new dispersants showed promising corrosion protection of metals, flame retardant and energy storage properties. / Thesis / Master of Applied Science (MASc)

Thesis (Ph. D.)--Institute of Paper Chemistry, 1959. / Includes bibliographical references (p. 142-143).

The number of newly developed chemical entities exhibiting poor water solubility has increased dramatically in recent years. In many cases this intrinsic property results in poor or erratic dissolution in biological fluids. Improving aqueous solubility of these compounds, even temporarily, can have a significant impact on in vivo performance. Single phase amorphous solid dispersions of a drug and polymer have emerged as a technique to not only increase the level of drug supersaturation but also maintain these levels for extended periods of time. Hot-melt extrusion (HME) has become the preferred processing technique to prepare systems such as these but has a number of limitations that prevent the successful formulation of many drug substances. Within this dissertation, the use of concentration enhancing polymers was investigated in parallel with a thorough evaluation of a novel fusion-based processing technique, KinetiSol® Dispersing (KSD), to prepare single phase amorphous solid dispersions that could not be successfully prepared by HME. Studies showed that the KSD technique is suitable for rendering thermally labile and high melting point drug substances amorphous through a combination of frictional and shearing energy. Compounds such as these were shown to degrade during HME processing due to relatively long residence times and low shear forces. Similarly, the KSD process was shown to successfully process solid dispersion compositions containing a high viscosity polymer with significantly lower levels of polymer degradation than obtained by HME processing. In the final study, KSD processing was used to prepare solid dispersions containing the hydrophilic polymer Soluplus[superscript TM] and methods were evaluated to formulate a tablet with rapid tablet disintegration characteristics, a requirement for sufficient dissolution enhancement. Combined, the studies demonstrated the effectiveness of combining proper polymer selection and formulation approaches with a suitable processing technique to form solid dispersion systems that provide rapid and extended durations of supersaturation. / text

Formulation intervention, through the application of processing technologies, is a requirement for enabling therapy for the vast majority of drugs. Without these enabling technologies, poorly soluble drugs may not achieve therapeutic concentrations in the blood or tissue of interest. Conversely, freely soluble and/or rapidly cleared drugs may require frequent dosing resulting in highly cyclic tissue concentrations. During the last several years, thermal processing techniques, such as melt mixing, spray congealing, sintering, and hot-melt extrusion (HME), have evolved rapidly. Several new technologies, specifically dry powder coating, injection molding, and KinetiSol® dispersing (KSD), have been adapted to the pharmaceutical arena. Co-rotating twin screw extrusion is routinely applied for the purposes of dissolving poorly soluble drugs into glassy polymers to prepare amorphous solid dispersions, which create supersaturated drug concentrations in the gastro-intestinal tract. A potentially more advantageous alternate geometry, counter-rotating twin screw extrusion was evaluated for preparation of model amorphous solid dispersion and was observed to be more efficient in forming a solid solution and reduced the thermal stress on the drug. HME and KSD processes were utilized to prepare two phase systems consisting of a lipid, glyceryl behenate, and a polymeric amorphous solid dispersion intended to provide both controlled release of drug and supersaturated drug concentrations in the release medium. Such systems are challenging due to the potential for crystallization of the drug within the dosage form during release, which was observed to be influenced by lipophilicity and porosity of the formulation, as well as the surface area to volume ratio of the system. High molecular weight cellulose based glassy dispersions were prepared using a weakly basic model drug by KSD, which when formulated into tablets were optimized to provide either immediate or approximately 2 hours of controlled release under the pH conditions simulating the environment of the stomach. Without formulation intervention in the external phase of the tablet, these compositions gel, muting drug release and missing the drug absorption window. Compositions optimized by an in vitro dissolution test were compared to a lower molecular weight HME prepared commercial product in a beagle dog model and observed to have statistically similar bioavailability, and in one case improved variability. A modified twin screw extrusion machine was utilized to develop a continuous granulation process capable of producing granules that do not require subsequent grinding or sizing. This novel process, which employs previously un-reported temperature profiles, produces lipid based granules that when compressed into tablets produce a controlled release of tramadol hydrochloride, which were not susceptible to alcohol induced dose dumping. / text

Made available in DSpace on 2015-03-26T13:53:08Z (GMT). No. of bitstreams: 1 texto completo.pdf: 449987 bytes, checksum: f46055cf3920c3d85666829b4db75fac (MD5) Previous issue date: 2008-11-28 / The most accurate textural analysis result is dependent on the soil sample s complete dispersal and maintenance of the dispersed phase s stability. The solution s high pH can be considered to be determinant in the dispersion of soils with pH dependent loads. Under the same pH and osmotic pressure conditions, the higher the ion s ionic hydrated radius, the more effective the clay dispersion will be, as a result of the increment of the diffuse double layer. Finally, the removal of cementing agents also increases soil sample dispersal. Thus, Na+ and Li+ compounds were tested as alternative dispersers against the solution NaOH 0.01 mol L-1, aiming to obtain a more effective dispersion so as to minimize the presence of pseudo-components, fundamentally pseudo-silt,in the granulometric analysis of Latosols. Samples of eight Latosols from the state of Minas Gerais were used, selected for presenting different materials of iron oxide origin and content. The treatments were arranged in a randomized block design, in an 8 x 2 x 7 factorial scheme, and three repetitions. The factors studied were the eight Latosol samples, removed from horizons A and B and seven dispersers. NaOH was used as a reference disperser, by additionally testing the solutions LiOH, NaClO, [NaClO + NaOH], [HCl + NaOH], (NaPO3)n and [(NaPO3)n + NaOH]. Mechanical dispersion was performed using a Wagner type rotatory agitator, regulated for 50 rotations during 16 hours. The alternative dispersers were compared with NaOH by means of the Dunnett test. Using the highest clay proportion to identify the dispersers effectiveness, none of them was equal to NaOH. Using the sign > to indicate greater effectiveness, the sequence determined was NaOH > [(NaPO3)n + NaOH] > [HCl + NaOH] > [NaClO + NaOH] > LiOH > (NaPO3)n > NaClO. Among the alternative dispersers, the [(NaPO3)n+NaOH] solution stood out, with results close to those of the reference disperser, showing the importance of increasing the pH up to values close to 12. The effectiveness of the other sodium solutions with high pH, [NaClO+NaOH] and [HCl+NaOH], was reduced by increasing the osmotic pressure of the solution, making soil sample dispersion difficult. LiOH was lower than the reference disperser. Such response is justified by the tendency of this alkaline cation to form covalent bonds that block negative electric loads of the clay exchange complex, leading to a decrease of the superficial load density. (NaPO3)n and NaClO were the least effective dispersers, due to the lower pH of their solutions. It can be concluded that the NaOH solution is the most effective in dispersing soil samples with clay presenting pH dependent cationic exchange capacity, favoring the increase of negative loads, repulsion between particles, and, consequently, soil sample dispersion with relatively low suspension osmotic pressure values. / O resultado mais acurado da análise textural é dependente da completa dispersão da amostra de solo e da manutenção da estabilidade da fase dispersa. Pode considerar que o pH elevado da solução é determinante na dispersão de solos com cargas dependentes de pH. Nas mesmas condições de pH e pressão osmótica, quanto maior o raio iônico hidratado do íon, mais efetiva será a dispersão de argilas, por incrementar a dupla camada difusa. Por último, a remoção de agentes cimentantes também incrementa a dispersão da amostra de solo. Em decorrência dessas afirmativa, foram testados compostos de Na+ e Li+ como dispersantes químicos alternativos, frente à solução de NaOH 0,01 mol L-1, com objetivo de lograr dispersão mais efetiva de forma a minimizar a presença de pseudocomponentes, fundamentalmente pseudo-silte, na análise granulométrica de Latossolos. O trabalho foi realizado utilizando amostras de oito Latossolos do Estado de Minas Gerais, selecionados por apresentarem diferentes materiais de origem e teores de óxidos de ferro. Os tratamentos foram dispostos segundo um delineamento em blocos casualizados, correspondendo a um arranjo fatorial 8 x 2 x 7, com três repetições. Os fatores em estudo foram as amostras dos oito Latossolos, retiradas nos horizontes A e B e sete dispersantes. O NaOH foi utilizado como dispersante de referência, testando-se, adicionalmente soluções de LiOH, NaClO, [NaClO + NaOH], [HCl + NaOH], (NaPO3)n e [(NaPO3)n + NaOH]. A dispersão mecânica foi realizada utilizando-se agitador rotatório tipo Wagner, regulado para 50 rotações por minuto, durante 16 horas. Os dispersantes alternativos foram comparados com NaOH por meio de teste de Dunnett. Utilizando a maior proporção de argila para identificar a efetividade dos dispersantes, nenhum deles igualou-se ao NaOH. Utilizando o sinal > para indicar maior efetividade, a seqüência determinada foi: NaOH > [(NaPO3)n + NaOH] > [HCl + NaOH] > [NaClO + NaOH] > LiOH > (NaPO3)n > NaClO. Dentre os dispersantes alternativos, destacou-se a solução de [(NaPO3)n+NaOH], com resultados próximos aos do dispersante de referência, evidenciando a importância da elevação do pH até valores próximos de 12. A efetividade das outras soluções sódicas com pH elevado, [NaClO+NaOH] e [HCl+NaOH], foi reduzida pela elevação da pressão osmótica da solução, dificultando a dispersão da amostra de solo. O LiOH foi inferior ao dispersante de referência. Essa resposta é justificada pela tendência desse cátion alcalino, de formar ligações covalentes que bloqueiam cargas elétricas negativas do complexo de troca das argila, com diminuição da densidade de carga superficial. O (NaPO3)n e NaClO foram os dispersantes menos efetivos, pelo menor pH das suas soluções. Pode concluir-se que a solução de NaOH é a mais efetiva para dispersar amostras de solos com argilas que apresentam capacidade de troca catiônica dependente do pH, ao favorecer o incremento de cargas negativas, a repulsão entre partículas e consequentemente a dispersão da amostra de solo, com valores relativamente baixos da pressão osmótica da suspensão.

Orientador: Rosiane Lopes Cunha / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-13T14:14:55Z (GMT). No. of bitstreams: 1 Sato_AnaCarlaKawazoe_D.pdf: 2187954 bytes, checksum: 9f67420e2e9bb6fdb40e51d15be43b4e (MD5) Previous issue date: 2009 / Resumo: A influência das características físicas e químicas do meio dispersante sobre a reologia de suspensões-modelo foi avaliada visando o entendimento do comportamento de sistemas reais como as polpas de frutas. Para isto, o trabalho foi dividido em duas etapas: 1) estudo do efeito da composição de sistemas-modelo de soro de polpas de frutas no comportamento reológico, e 2) estudo de suspensões-modelo de diferentes partículas dispersas em matrizes com diferentes propriedades físicas e químicas. Na primeira etapa, foi verificado o efeito da presença de pectinas de alto e baixo grau de metoxilação, assim como de suas misturas. Os resultados mostraram um efeito sinergístico da mistura destes diferentes tipos de pectinas, devido à maior viscosidade e pseudoplasticidade dos sistemas mistos quando comparados aos sistemas com um único tipo de pectina. Assim, ressaltou-se a importância dos diferentes tipos de ligação no comportamento reológico destes sistemas. A segunda etapa permitiu a compreensão das interações entre partículas e partícula-solvente e a sua influência no comportamento reológico de suspensões-modelo. De um modo geral, as interações entre partículas e partícula-solvente foram maiores nos meios menos viscosos e polares. Tais resultados foram refletidos pelo valor ajustado da fração máxima de empacotamento (fm) por diferentes modelos, dado que foi possível a adição de maior quantidade de sólidos para os sistemas com menos interações. Xantana foi adicionada às matrizes dispersantes para promover pseudoplasticidade, indicando comportamentos distintos quando adicionadas em água pura e em soluções aquosas de glicerina. No primeiro caso, as matrizes apresentaram comportamento altamente pseudoplástico, enquanto que a adição de mesma quantidade de xantana nas soluções aquosas de glicerina levou a um grande aumento na viscosidade, com menor influência no valor do índice de comportamento de escoamento. A adição de sólidos nestes dois tipos de matrizes levou a comportamentos distintos. No primeiro caso verificou-se uma leve desestruturação do sistema, refletido principalmente pela maior influência do módulo complexo com a freqüência e menor variação na viscosidade relativa das suspensões. Por outro lado, o aumento na fração de sólidos nos sistemas compostos com xantana, glicerina e água levou a suspensões mais estruturadas. Assim, os resultados apresentados mostram que além das características das partículas, as propriedades químicas e reológicas da matriz dispersante são essenciais na determinação do comportamento estrutural e de escoamento de suspensões e portanto, não deveriam ser desprezadas pelos modelos existentes / Abstract: The influence of the physical and chemical properties of dispersing matrices on the rheological behavior of model-suspensions was evaluated, aiming the understanding of real suspensions such as fruit pulps. The present research was divided into two parts: 1) influence of composition of serum of fruit pulps on their rheological characteristics, through the study of model-systems, and 2) evaluation of model-suspensions of different particles dispersed into matrices with distinct characteristics (physical and chemical). In the first part, the effects of low and high methoxy pectins were evaluated, as well as their mixture. Results indicated a synergistic effect on the mixture of different sorts of pectin, which was observed by the higher viscosity and pseudoplasticity of mixed systems as compared to pure pectin ones. Such results allowed emphasizing the importance of different binding characteristics on the rheological properties of these systems. The second part allowed for the comprehension of interparticle and particle-matrix interactions, and their influence on the rheological behavior of model suspensions. Generally, interactions were more pronounced at low viscous and polar matrices, which reflected the lower maximum packing fraction (fm) fitted by different models. Xanthan was added to dispersing matrices to impart pseudoplasticity, showing distinct behaviors when mixed in pure water and aqueous glycerin solutions. In the first case, matrices showed highly shear thinning behavior, while the addition of the same amount of xanthan in glycerin aqueous solutions promoted a significant increase on viscosity, with lower influence on the flow index behavior (n). Thus, distinct behavior was observed when increasing solids concentration on these two matrices. In the first case, the increase of the dependency of complex modulus with frequency and the lower influence of the relative viscosity reflected a slight loss of structure with solids addition. On the other hand, increasing solids content on systems composed with xanthan, glycerin and water increased structuring. Thus, results indicated that beyond particles characteristics, which have already been widely studied in literature, the knowledge of the chemical and rheological properties of dispersing matrix is of great importance on structural behavior of suspensions / Doutorado / Doutor em Engenharia de Alimentos