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Govan, Otesh Thakorlal. "Time dependent effects in powder compression." Thesis, Cardiff University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314682.
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Blundell, L. P. "Characterisation and compaction parameters of directly compressible tablet excipients." Thesis, Cardiff University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356740.
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Larhrib, El Hassane. "Characterisation & compaction of polyethylene glycols." Thesis, Liverpool John Moores University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242150.
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Yelamanchili, Satish Neau Steven H. "Colon specific delivery using ethylcellulose and chitosan in a compression coated tablet." Diss., UMK access, 2006.
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Thesis (M.S.)--School of Pharmacy. University of Missouri--Kansas City, 2006."A thesis in pharmaceutical science." Typescript. Advisor: Steven H. Neau. Vita. Title from "catalog record" of the print edition Description based on contents viewed Nov. 12, 2007. Includes bibliographical references (leaves 82-87). Online version of the print edition.
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Gabrielsson, Jon. "Multivariate methods in tablet formulation." Doctoral thesis, Umeå : Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-268.
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Persson, Ann-Sofie. "Flow and Compression of Granulated Powders : The Accuracy of Discrete Element Simulations and Assessment of Tablet Microstructure." Doctoral thesis, Uppsala universitet, Institutionen för farmaci, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208808.
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Simulations are powerful and important tools for gaining insight into powder processes. Ultimately, simulations have the potential to replace experiments. Thus, accurate models and insight into the essential factors for descriptions of powder behaviour are required. In this thesis, discrete element method (DEM) simulations of granule flow and compression were evaluated to deduce parameters and potential models essential for the experimental and numerical correspondence. In addition, the evolution in tablet microstructure during compression was studied using mercury porosimetry. Granule flow was measured using angle of repose, discharge rate, and shear. The granular flow depended primarily on particle shape and surface texture due to the mutual influence of these two parameters on the inter-particle forces. Rolling friction stabilised both the heap formation and promoted shear in the elastic quasi-static flow regime. Thus, rolling friction was established to be an essential simulation parameter for the correspondence to experiments. Current compression models often neglect the elastic compact deformation during particle loading. In this thesis, two fundamentally different models were evaluated with focus of including the elastic deformation. The first model comprised a maximal particle overlap, where elastic deformation commences. The second model accounted for the contact dependence and impingement at high relative densities. This model was based on a truncated-sphere followed by a Voronoi extension. The validity of the models was demonstrated by the elastic qualitative correspondence to experimental compressions for ductile materials. In tablets, the void (inter-granular pore) diameter was dependent on the degree of compression. Thus, the degree of compression provides an indication of the tablet microstructure. The microstructure was subsequently observed to be related to the tablet tensile strength as inferred from a percolation threshold required for formation of coherent tablets. In summary, this thesis has shed light onto the potential of simulating flow and compression of granulated pharmaceutical powders using DEM. Continuous work in the area are required to further improve the models to increase the experimental and numerical correspondence.
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Mahmoodi, Foad. "Compression Mechanics of Powders and Granular Materials Probed by Force Distributions and a Micromechanically Based Compaction Equation." Doctoral thesis, Uppsala universitet, Institutionen för farmaci, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-171874.
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The internal dynamics of powder systems under compression are as of yet not fully understood, and thus there is a necessity for approaches that can help in further clarifying and enhancing the level of understanding on this subject. To this end, the internal dynamics of powder systems under compression were probed by means of force distributions and a novel compaction equation. The determination of force distributions hinged on the use of carbon paper as a force sensor, where the imprints transferred from it onto white paper where converted through calibration into forces. Through analysis of these imprints, it was found that the absence of friction and bonding capacity between the particles composing the powder bed had no effect on how the applied load was transferred through the system. Additionally, it was found that pellet strength had a role to play in the homogeneity of force distributions, where, upon the occurrence of fracture, force distributions became less homogenous. A novel compaction equation was derived and tested on a series of systems composed of pellets with differing mechanical properties. The main value of the equation lay in its ability to predict compression behavior from single particle properties, and the agreement was especially good when a compact of zero porosity was formed. The utility of the equation was tested in two further studies, using a series of pharmaceutically relevant powder materials. It was established that the A parameter of the equation was a measure of the deformability of the powder material, much like the Heckel 1/K parameter, and can be used as a means to rank powders according to deformability, i.e. to establish plasticity scale. The equation also provided insights into the dominating compression mechanisms through an invariance that could be exploited to determine the point, at which the powder system became constrained, i.e. the end of rearrangement. Additionally, the robustness of the equation was demonstrated through fruitful analysis of a set of diverse materials. In summary, this thesis has provided insights and tools that can be translated into more efficient development and manufacturing of medicines in the form of tablets.
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Tunón, Åsa. "Preparation of Tablets from Reservoir Pellets with an Emphasis on the Compression Behaviour and Drug Release." Doctoral thesis, Uppsala University, Department of Pharmacy, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3411.
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The preparation of multiple unit tablets was investigated in this thesis with the intention of gaining a deeper understanding of some of the factors that influence the properties of such tablets.
Initially, three different types of pellets (drug, soft and disintegrant pellets) were combined as a model to investigate the ability of the mixture to form disintegrating tablets. The proportions of the different pellets and the type of disintegrant used were factors that independently influenced the tablet properties. Furthermore, the properties of tablets containing drug pellets barrier-coated with an aqueous polymer dispersion were also found to depend on the coating thickness and the compaction pressure.
When compacting pellets barrier-coated with a solvent-based polymer solution without incorporating excipient particles in the tablet formulation, a high pellet porosity was advantageous to preserve the original drug release profile, even though highly porous pellets became more densified and deformed than pellets of lower porosity.
The influence of the properties of excipient particles on the deformation of the reservoir pellets was also studied and, although the amount of flattening of the pellets was only slightly affected, changes in the pellet shape (irregularity) with alterations in the porosity and size of the excipient particles were more substantial. In contrast, the properties of the excipient particles did not affect the pellet densification.
The solvent-based coating used was able to adapt to the changes in volume and shape that the pellets underwent during compaction. The coating structure appears to be changed by compaction and it is proposed that the final structure of the coating is the net effect of two parallel processes, one reducing and one prolonging the transport time of the drug across the coating. Thus, the drug release could be maintained or even prolonged after compaction, despite extensive structural changes of the reservoir pellets.
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Alanezi, Abdulkareem Ali. "Development of an Orally Disintegrating Mini-Tablet (ODMTs) Containing Metoclopramide HCl to Enhance Patient Compliance." University of Toledo Health Science Campus / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=mco1417861431.
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Spaniol, Bárbara. "Comparação do comportamento compressional de granulado contendo produto seco por aspersão de phyllanthus niruri l. entre máquinas de comprimir alternativa e rotativa." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/11062.
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Este trabalho foi realizado com a finalidade de avaliar o comportamento compressional de granulado contendo alta concentração de produto seco por aspersão de Phyllanthus niruri em máquinas de comprimir alternativa (MCA) e rotativa (MCR). A partir do material vegetal de P. niruri foram produzidas a solução extrativa e o produto seco por aspersão (PSA). A formulação dos comprimidos foi composta de granulados do PSA (GPSA) (92 %), adjuvantes granulados (GADJ) (7,92 %) e estearato de magnésio (0,08 %). O GPSA foi produzido por granulação por via seca e o GADJ, composto de celulose microcristalina (62,9 %) e amidoglicolato de sódio (37,1 %), por via úmida. A granulometria do complexo farmacêutico (CF) compreendeu a faixa de 0,250 a 0,850 mm. Foram produzidos comprimidos em máquina universal de ensaios, em punções planos com diâmetro de 13 e 5 mm, avaliando-se a influência da altura da coluna de CF e do diâmetro da matriz sobre as características dos compactos obtidos. A previsão da resistência à tensão e expansão volumétrica radial se torna impossibilitada pela suas dependências das variáveis aplicadas. Dos compactos obtidos em matriz de 13 mm, produzidos com sete forças de compressão (de 2,26 a 16,04 kN), verificou-se a linearidade entre a força de compressão e a resistência à tensão dos compactos. Além disso, em diferentes pressões de compressão, que variaram de 13,2 a 120,9 MPa, avaliou-se, através do modelo de Heckel (método out die), o mecanismo de consolidação do complexo farmacêutico, que apresentou comportamento fragmentativo em baixas pressões e deformação plástica a partir de 30,2 MPa. O valor de pressão média por deformação (Py) foi igual a 229,01 MPa, indicativo de que as condições da granulação por via seca podem ter influenciado as características de consolidação do complexo farmacêutico. O CF não apresentou defeitos de compressão, como laminação e descabeçamento, nem variação de peso em ambos os modelos de máquinas de comprimir utilizados. Imagens das faces superior e inferior dos comprimidos obtidos na MCA e MCR, tratadas com programa de análise de imagens, esclareceram de forma quantitativa as diferenças entre elas, sugerindo a ocorrência de fenômeno de percolação. As diferentes velocidades de produção em MCR evidenciaram o comportamento visco-plástico do CF, pois em menores velocidades houve aumento significativo da resistência à tensão dos comprimidos, não afetando, no entanto, o tempo de desintegração dos mesmos. Comprimidos produzidos em MCR apresentaram menor friabilidade e porosidade, que não se refletiu em resistência à tensão àquela apresentada para os obtidos em MCA. A cedência do PSA não sofreu influência do tipo de equipamento ou das condições experimentais na quais os comprimidos foram produzidos. As diferenças na construção e funcionamento dos dois tipos de máquinas de comprimir foram influentes sobre o produto final, já que comprimidos, com resistências à tensão semelhantes, advindos de máquinas de comprimir distintas, apresentaram diferenças nos parâmetros de qualidade avaliados.This work was carried out to evaluate the compressional behavior of granules containing high load of a Phyllanthus niruri spray-dried extract in eccentric (ETM) and rotary (RTM) tablet presses. Extractive solution and spray-dried extract (SDE) were produced from the plant aerial parts. Tablets were constituted by SDE granules (SDEG) (92 %), excipients granules (EXCG) (7.92 %) and magnesium stearate (0.08 %). SDEG was obtained by dry granulation and EXCG, composed by microcrystalline cellulose (62.9 %) and sodium starch glycolate (37.1 %), by wet granulation. Particle size distribution was fixed between 0.355 to 0.850 mm. Tablets were also produced in a universal assay machine with flat-faced punches of 10 and 5 mm diameter, in order to estimate the influence of granules bed height and tooling diameter on the compact characteristics. Tensile strength and radial elastic recovery demonstrated to be very dependent of both variables hindering further correlations. For the tablets produced in 13 mm tooling by applying seven compression forces (from 2.26 to 16.06 kN), linearity between compression force and tensile strength was observed. The consolidation mechanism of the granule mixture could be elucidated using different compression pressures, in the range from 13.2 to 120.9 MPa. Heckel’s model (out die method) pointed out the occurrence of brittle behavior under low pressures and plastic deformation beginning at 30.2 MPa. Mean yield pressure (Py) was 229.01 MPa, indicating that dry granulation conditions may have influenced the consolidation characteristics of the formulation. Tablets did not evidence any mechanical failures, such as lamination or capping, or anomalous weight variation in both tablet machine types. Upper and lower tablet surfaces images from ETM and RTM, analyzed by an image-analysis-software, showed differences between the granules distribution, suggesting the occurrence of percolation phenomenon. Different RTM speeds suggested the visco-plastic behavior of the formulation, since by slower rotation speeds tablet’s tensile strength significantly increases, but the disintegration time was not affected. Tablets produced in RTM showed lower friability and porosity, which did not reflect on higher tensile strength, than those obtained by tablets of ETM. SDE release was not influenced by the type of equipment or operational conditions to which the compacts were submitted. Construction and operation differences between both tablet presses influenced the final product, since tablets with similar tensile strength, produced by distinct tablet machines, exhibited different quality parameters.
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Tarlier, Nicolas. "Application de la simulation de compression pour l’étude comportementale et l’analyse des performances de poudres de mannitol DC." Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT177.
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Le travail réalisé concerne l’étude de la fonctionnalité et des performances des poudres de mannitol en compression directe en s’appuyant sur la simulation de compression sur presse rotative comme outil d’investigations. Dans le contexte réglementaire actuel, il est important pour les industriels, fournisseurs d’excipients pharmaceutiques, d’approfondir leurs connaissances des matériaux afin de répondre aux critères de qualité des médicaments et aux exigences de l’industrie pharmaceutique. Le mannitol est un excipient très largement utilisé en formulation pharmaceutique et notamment pour la conception de comprimés. L’objectif essentiel de cette Etude vise à mieux connaître et maîtriser la qualité de cette matière première afin de pouvoir améliorer, voire optimiser ses performances en compression directe. A l’aide d’une série de tests de caractérisation physiques, physico-chimiques, mécaniques et de compression sur les poudres de mannitol, nous avons pu identifier, dans un premier temps, un certain nombre de critères qui nous ont permis d’émettre des hypothèses et d’établir des axes de travail afin d’analyser le comportement de ces poudres en compression. Les résultats obtenus ont également permis de mettre en avant, à l’aide de l’étude de la compressibilité et des modèles mathématiques associés, un mécanisme de déformation prédominant sur les poudres de mannitol de compression directe. De nombreux prototypes ont fait l’objet d’une investigation approfondie dans une seconde partie, permettant de valider ces hypothèses et d’identifier les paramètres et mécanismes responsables des performances en compression des poudres de mannitol.Globalement, les travaux de recherche conduits dans cette thèse ont permis d’améliorer les connaissances sur les performances en compression des poudres de mannitol de la société Roquette Frères dans des conditions réelles d’utilisation, semblables aux presses rotatives industrielles, et en fournissant des résultats expérimentaux validés et modélisésThis work focuses on the study of the functionality and performance of directly compressed mannitol powder using a rotary tablet press simulator as an investigation tool. For regulatory authority, it is essential for industrial - pharmaceutical raw material suppliers, to deepen their knowledge about materials to satisfy the drug quality standards and Pharmaceutical industry requirements. Mannitol is a widely used raw material in pharmaceutical formulations for the design of tablets. The main objective of this study is to have a better control and knowledge about this raw material quality, in order to improve and optimize the performance of mannitol in direct compression.Using a series of physical, physico-chemical, mechanical and compression studies on mannitol powders, we identified some criteria that allowed us to emit hypotheses and build a line of work to analyze the powders behavior under compression. The results also allowed us - using compressibility and associated mathematical models - to study the predominant deformation mechanism of directly compressed mannitol powders. Various mannitol prototypes were studied in a second part, permitting to validate these hypotheses and identify parameters and mechanisms affecting tableting performance.Overall, the research work achieved in this thesis have improved the knowledge about compression performance of mannitol powders from Roquette Frères SA company in tablet production used conditions, similar to industrial rotary tablet press, and providing validated and modeled experimental results
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Soulairol, Ian. "Etude des phénomènes liés à la conception de mini-comprimés orodispersibles par compression directe." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT115/document.
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La possibilité d’administrer des formes sèches orales est encore de nos jours un enjeu dans certaines spécialités médicales telles que la pédiatrie, la neurologie ou la gériatrie. Les mini-comprimés orodispersibles présentent un intérêt majeur pour répondre à cette problématique.L’objectif de ce travail est d’étudier les différents phénomènes qui régissent la conception de cette forme pharmaceutique par compression directe.Trois axes de recherche ont été fixés pour la réalisation de ce travail : - Premièrement, étudier les paramètres de formulation et de fabrication des mini-comprimés orodispersibles.- Deuxièmement, améliorer notre compréhension des phénomènes qui régissent la désintégration de ces comprimés au travers de l’étude du comportement de l’excipient clé de la désintégration : le super-désintégrant.- Enfin, développer un matériau à base d’acide alginique et d’alginate de calcium ayant pour fonction d’accélérer la désintégration des mini-comprimés orodispersibles.Les résultats obtenus permettent d’orienter les choix des différents excipients et les paramètres techniques pour la fabrication de cette forme. D’autre part, ils mettent en évidence le besoin de définir des spécifications et des techniques de caractérisation qui lui sont dédiées. Les résultats obtenus lors de l’étude du comportement des super-désintégrants au moment de leur hydratation, soulignent l’importance de la capacité de conduction de l’eau des super-désintégrants dans le mécanisme de désintégration des mini-comprimés orodispersibles. Enfin, les résultats des travaux réalisés pour l’obtention de matériaux super-désintégrants à base d’acide alginique permettent d’établir de premières orientations à suivre dans leurs modes de production.Les différentes conclusions issues des travaux menés lors de cette thèse permettront de valoriser cette forme pharmaceutique innovante et d’en favoriser de nouveaux développementsPatient acceptability of a medical product is a key aspect in the development of medicines. Oral administration of dry forms presents still several limitations in some medical specialties such as pediatrics, neurology or geriatrics. Orodispersible Mini Tablets (ODMTs) have been described as a potential solution to these drawbacks.In this thesis, the different parameters governing the design of these pharmaceutical forms by direct compression have been studied.Three main lines of research have been followed to carry out this work:- Firstly, the different parameters of formulation and manufacture of orodispersible mini tablets were evaluated.- Secondly, the behavior of different commercial super disintegrants, key excipents in the disintegrating action, was studied in order to improve our understanding of the phenomena governing the disintegration mechanisms of the ODMTs.- Finally, various alginate-based materials were developed and its function as super disintegrants in orodispersible mini tablets was tested.The obtained results can be used as indicatives in the choice of excipient and the technical parameters for an effective manufacture of OMDTs. Moreover, they have highlighted the need to continue defining specifications and characterization techniques dedicated to further development of OMDTs. The results obtained during the hydration studies (swelling ratio, swelling force and water uptake) of the super disintegrants underline the importance of wicking in the disintegration mechanism of the ODMT.Finally, the prepared alginate-based materials have shown to present interesting mechanical properties for the development of effective and available super disintegrants for direct compression.The choice of suitable super disintegrants for ODMTs formulation requires extensive knowledge of their properties for promoting the breakout of the tablet and of their interaction with both, water and the various materials constituting the tablet. Thus, the knowledge gained in this thesis on super disintegrant functionality will promote the appropriate development of this innovative pharmaceutical form
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Fichtner, Frauke. "Identification and Variation of some Functionality Related Characteristics of Pharmaceutically Relevant Solid Materials and their Effect on Product Performance." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7462.
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Patel, Chaitanya I. "Design and characterization of direct compression excipients." Thesis, University of Bath, 1986. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370466.
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Patel, A. N. "The influence of water on the compressional properties of some solids." Thesis, Cardiff University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374737.
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Soares, Luiz Alberto Lira. "Obtenção de comprimidos contendo alto teor de produto seco por aspersão de Maytenus ilicifolia Mart. ex. Reissek - Celastraceae : desenvolvimento tecnológico de produtos intermediários e final." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2002. http://hdl.handle.net/10183/147612.
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As folhas de Maytenus ilicifolia são amplamente utilizadas na medicina tradicional brasileira no tratamento de distúrbios gástricos. Após a comprovação de sua eficácia e segurança, a referida droga vegetal tem sido objeto de diversos estudos com a finalidade de estabelecer parâmetros para o controle de qualidade. Neste sentido, foi avaliada a viabilidade do desenvolvimento de um método analítico fundamentado na precipitação de taninos empregando povidona como agente seqüestrante. Os dados revelaram que a remoção de taninos em solução é satisfatória quando empregada a povidona insolúvel. Foi observado que o polímero também é capaz de precipitar outros polifenóis além dos taninos presentes na solução extrativa de M. ilicifolia. Entretanto, as interações do polímero ocorrem preferencialmente com os derivados catéquicos. Adicionalmente foi desenvolvido e validado um método por CLAE para separação e quantificação de catequina e epicatequina em produtos derivados de M. ilicifolia. Não foram detectadas variações nas áreas dos picos ou nos tempos de retenção durante os ensaios de avaliação do método, sugerindo que as condições cromatográficas empregadas são satisfatórias. Para viabilizar a preparação de produto seco por aspersäo (PSA) em torre de secagem piloto munida de aspersor rotatório, foi necessária a concentração da solução extrativa. A operação foi realizada sob pressão reduzida até alcangar um teor de sólidos mínimo de 15 % (m/m). A operação de secagem da solução concentrada apresentou rendimento de 90 % e o PSA obtido apresentou partículas esféricas, com superfície rugosa e tamanho médio de 22,5 um. A caracterização tecnológica do material revelou que as suas propriedades tecnológicas, tais como, densidades, compressibilidade e fluxo, foram incrementadas quando comparados com o produto preparado em equipamento de bancada. Entretanto, estas modificações não foram suficientes para viabilizar sua compressão direta. Assim sendo, o material foi compactado em máquina de comprimir e em rolos para produção de grânulos. A análise do perfil compressional do PSA e dos granulados, empregando o modelo de Heckel, revelou que o aumento da força de compactação durante a operação de granulação foi o principal responsável pela diminuição no potencial de deformação plástica dos grânulos. Como conseqüência, a recompressão dos grânulos em máquina de comprimir originou compactos com dureza inferior àqueles preparados diretamente do complexo farmacêutico. Enquanto o PSA apresentou reduzida tendência ao rearranjo particular nos estágios iniciais da compressão, os grânulos sofreram intensa reacomodação decorrente da fragmentação e formação de novas pontes, assumindo comportamento plástico em pressões de compressão mais elevadas. Por fim, comprimidos contendo teor elevado de granulado de PSA foram preparados utilizando como adjuvantes a celulose microcristalina, o dióxido de silício coloidal e a croscarmelose sódica. A influência da concentração de dióxido de silício coloidal e croscarmelose sódica na formulação, sobre as respostas de dureza, friabilidade e tempo de desintegração dos comprimidos foram avaliadas através de um Desenho Composto Central. Os dados experimentais foram analisados estatisticamente, utilizando os modelos matemáticos para gerar superfícies de resposta. Os resultados indicaram que a concentração de dióxido de silício coloidal foi inversamente relacionada às respostas de dureza e friabilidade, enquanto que a concentração de croscarmelose sódica foi a principal responsável pela redução no tempo de desintegração. As condições ótimas foram selecionadas através da sobreposição dos gráficos, buscando uma formulação com menor tempo de desintegração, menor friabilidade e o máximo de dureza. A formulação eleita deve conter 1,2 % (m/m) de dióxido de silício coloidal e 5,0 % (m/m) de croscarmelose sódica. Nestas condições os comprimidos apresentaram dureza de 107,9 N, friabilidade de 0,56 % (m/m) e desintegração máxima em 6,8 min.The leaves of Maytenus ilicifolia are widely used within the traditional Brazilian medicine due to its properties against gastric disorders. Once proved its efficacy and safety, this vegetable drug has been the object of several studies to establish the basis for quality control. Taking this into consideration, it was necessary to evaluate the feasibility of developing an analytical method based on the precipitation of tannins, by using polyvinylpyrrolidone for precipitation. The data have shown that the removal of the tannins in solution was successful when insoluble polyvinylpyrrolidone was used. Hereby it was observed that the polymer has also the ability to precipitate other polyphenols besides the tannins from the aqueous solution of M. ilicifolia. However, the interactions of the polymer happened mostly with the condensed tannins. Further it was developed and also validated an HPLC method to separate and quantify catechin and epicatechin present in aqueous extracts of M. ilicifolia. No significant variations of peak areas or retention times were observed when the evaluation of the method was executed, showing satisfactory chromatographic conditions. In order to make a spray dried extract (SDE) using a spray-drier fitted out with a rotary atomizer, it was necessary to concentrate the extractive solution. This operation had been performed under reduced pressure until a content of 15 % solids was achieved. The drying of the concentrated solution lead to a yield of 90 %, and the obtained SDE presented spherical particles, which have a rough surface and a mean particle size of 22,51.1.m. The technological characterization of the SDE showed that attributes such as densities (tap and bulk), compressibility and flow, have been improved when compared to the product prepared using a mini spray-drier supplied with a pneumatic nozzle. However, these modifications were not enough to enable its direct compression. Therefore, the material was compacted to produce granules after slugging or roller compaction, The compressional analysis of the SDE and each granule batch using the Heckel equation proved that the increase in the compaction force once processing the granulation was the main factor to reduce the material's ability to undergo plastic deformation. Consequently, the recompression of the granules in a tablet press led to compacts with a lower crushing strength compared to that prepared by direct compression of the pharmaceutical complex. Whereas the SDE has shown a reduced tendency to particle rearrangement at early stage of compression, the granules showed an intense fragmentation and rebound behavior, presenting a plastic behavior when higher compaction pressures were used. Finally, tablets containing a high dose of granulated spray dried extract of M. ilicifolia were prepared by using the following excipients: microcrystalline cellulose (filler/binder), colloidal silicon dioxide (glidant and moisture adsorber) and cross-linked carboxymethylcellulose (disintegrant). The influences of colloidal silicon dioxide (CSD) and cross-linked carboxymethylcellulose (CMC-Na) on the tablet hardness, disintegration time and friability were evaluated by a central composite design. The data were analyzed statistically and mathematical models were used to create response surfaces. The results have indicated that the concentration of CSD shows an inverse relation to the responses of hardness and friability, while the concentration of CMC-Na was the most important factor that caused a reduction of the time necessary for total disintegration. The optimal conditions for processing were chosen by the overlapping of graphics, taking into consideration that the formulation should present a minimum of disintegration time, lower friability and a maximum of hardness. Thus, it was found that the best formulation should have a content of 1.2% (w/w) of CSD and 5.0% (w/w) of CMC-Na. Regarding these conditions, the tablets have shown a hardness of 107.9 N, friability of 0.56% (w/w) and a disintegration time of 6.8 min.
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Martinello, Tiago. "Desenvolvimento de comprimidos de paracetamol de 500 mg fabricados por compressão direta utilizando o planejamento estatístico de mistura." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-31082006-160216/.
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As formas orais sólidas são as mais utilizadas pela sua facilidade de administração e transporte, além de proporcionarem maior estabilidade, se comparadas às líquidas ou semi-sólidas. Dentre os sólidos orais, os comprimidos destacam-se por apresentarem processo de fabricação relativamente fácil, com alta produtividade e baixo custo. A compressão direta é o método preferencial para a produção de comprimidos pois economiza tempo e energia, é ambientalmente menos agressiva e reduz investimentos em equipamentos e na estrutura da área de produção, por requerer menor número de etapas no processamento que os métodos tradicionais de granulação. A principal limitação para a aplicação desse processo é a baixa capacidade de compactação dos fármacos que requerem altas concentrações para obtenção do efeito terapêutico. Com o objetivo de desenvolver formulações contendo alto teor de fármaco por compressão direta foi utilizado o planejamento estatístico de mistura e o paracetamol como fármaco modelo, pelas propriedades deficientes de escoamento e compactação. O programa Design Expert® foi empregado e forneceu 19 formulações, que foram produzidas e avaliadas quanto ao índice de compressibilidade, ângulo de repouso, umidade, peso médio, friabilidade, dureza, doseamento, desintegração e dissolução. O programa Design Expert® foi alimentado com os resultados obtidos e as formulações foram otimizadas. A formulação otimizada que atendeu a todos os parâmetros de qualidade foi produzida e analisada. Os resultados encontrados foram muito próximos aos previstos pela análise de regressão, demonstrando que o projeto de mistura é uma ótima opção para a pesquisa e desenvolvimento, diminuindo o tempo despendido e o número de experimentos.The solid oral forms are widely used, by easy administration and transport. They provide larger stability than a liquid or semi-solid. Among the solids orals the tablets appear for they present production process relatively easy, with high productivity and low cost. The direct compression is the preferential method for the production of tablets because is less aggressive for the environment, saves time and energy and reduces investments in equipments and in the structure of the production area, for requiring smaller number of stages in the production\'s process than the traditional methods of granulation. The main limitation for the application of that process is the low compaction capacity of the drugs that require high percentages for the therapeutic effect. The aim of this study was developing formulations containing high amount of drug by direct compression using the statistical planning of mixture and the paracetamol as drug model, for the deficient flow and compaction properties. The program Design Expert® was used and supplied 19 formulations that were produced and the compressibility index, angle, humidity, weight, friablility, hardness, assay, disintegration and dissolution were analyzed. The program Design Expert® was fed with the obtained results and the formulations were optimized. The formulation optimized that assisted all quality parameters was produced and analyzed. The obtained results were very close with the regression analysis, demonstrating that the mixture project is a great option for the research and development, reducing the spent time and the number of experiments.
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Rujivipat, Soravoot [Verfasser]. "Novel formulation and processing aspects for compression coated tablets and for the compression of polymer-coated multiparticulates / Soravoot Rujivipat." Berlin : Freie Universität Berlin, 2010. http://d-nb.info/102478455X/34.
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Ediev, Dalkhat. "Mortality compression in period life tables hides decompression in birth cohorts in low-mortality countries." Sapienza University of Rome, 2013. http://dx.doi.org/10.4402/genus-451.
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The rapid increase in human longevity has raised important questions about what implications this development may have for the variability of age at death. Earlier studies have reported evidence of a historical trend towards mortality compression. However, the period life table model, commonly used to address mortality compression, produces a compressed picture of mortality as a built-in feature of the model. To overcome this limitation, we base our study on an examination of the durations of exposure, in years of age, of birth cohorts and period life tables to selected short ranges of the death rate observed at old age. Overall, old-age mortality has been decompressing, cohort-wise, since the 1960s. This process may further indicate good prospects for ever-decreasing mortality. In the future, deaths may not be concentrated within a narrow age interval, but will instead become more dispersed, though at ever later ages on average.
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Thomas, William Iwan. "The effects of material characteristics on the compression and properties of dry coated tablets." Thesis, University of Sunderland, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264762.
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Sanderson, I. M. "The effect of formulation and maufacturing processes on the characterisitics of direct compression tablets." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372670.
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Kieser, Leith Faye. "Formulation and assessment of monolithic beta blocker sustained release tablets prepared by direct compression." Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1003242.
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Beta blockers are commonly prescribed for the chronic treatment of hypertension, one of the most prolific disease states worldwide. The beta blockers selected for this study include acebutolol hydrochloride, labetalol hydrochloride, metoprolol tartrate oxprenolol hydrochloride and propranolol hydrochloride. All of these compounds have a short elimination half-life, necessitating multiple dose per day regimens and therefore the development of sustained release dosage forms incorporating these agents was considered beneficial in terms of extending the dosing interval, with the aim of improving patient compliance and subsequent therapeutic outcomes. Preformulation studies that were conducted included moisture content analysis by Karl Fischer titration, and DSC, a method used to predict potential interactions between the drugs and tablet excipients. Tablets were manufactured by both wet granulation and direct compression techniques, and the resultant drug release characteristics were evaluated using the USP Apparatus 3(BIO.DIS). A validated isocratic HPLC method, capable of separating the five drug candidates simultaneously, was developed and used for the analysis of drug samples. Tablet quality was assessed using analyses that included the physical assessment of weight, diameter, thickness, hardness and friability, as well as content uniformity of tablets, before and after dissolution testing. Direct compression tablet formulations containing each of the five beta blockers were successfully adapted from a prototype wet granulation matrix tablet containing metoprolol tartrate, and various formulation variables were investigated to establish,their effect on the rate and extent of drug release from these tablets. The grade and quantity of ethylcellulose used in the wet granulation and direct compression formulae influenced the release rate of some drug candidates. In addition, an alternative formulation method, involving freeze-drying of the drug with an ethylcellulose dispersion, was shown to have potential for altering release rates further. Anti-frictional agents, talc and colloidal silicon dioxide, did not affect drug release from these matrices,however, they affected the physical character:istics such as tablet weight and thickness, of the resultant tablets. All of the matrix tablets formulated were shown to release drug according to square root of time kinetics, in a sustained manner over a 22 hour period.
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Eissa, Salah. "Condition monitoring of pharmaceutical powder compression during tabletting using acoustic emission." Thesis, Brunel University, 2003. http://bura.brunel.ac.uk/handle/2438/5244.
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This research project aimed to develop a condition monitoring system for the final production quality of pharmaceutical tablets and detection capping and lamination during powder compression process using the acoustic emission (AE) method. Pharmaceutical tablet manufacturers obliged by regulatory bodies to test the tablet's physical properties such as hardness, dissolution and disintegration before the tablets are released to the market. Most of the existing methods and techniques for testing and monitoring these tablet's properties are performed at the tablet post-compression stage. Furthermore, these tests are destructive in nature. Early experimental investigations revealed that the AE energy that is generated during powder compression is directly proportional to the peak force that is required to crush the tablet, i. e. crushing strength. Further laboratory and industrial experimental investigation have been conducted to study the relationship between the AE signals and the compression conditions. Traditional AE signal features such as energy, count, peak amplitude, average signal level, event duration and rise time were recorded. AE data analysis with the aid of advanced classification algorithm, fuzzy C-mean clustering showed that the AE energy is a very useful parameter in tablet condition monitoring. It was found that the AE energy that is generated during powder compression is sensitive to the process and is directly proportional to the compression speed, particle size, homogeneity of mixture and the amount of material present. Also this AE signal is dependent upon the type of material used as the tablet filler. Acoustic emission has been shown to be a useful technique for characterising some of the complex physical changes which occur during tabletting. Capping and lamination are serious problems that are encountered during tabletting. A capped or laminated tablet is one which no longer retains its mechanical integrity and exhibit low strength characteristics. Capping and lamination can be caused by a number of factors such as excessive pressure, insufficient binder in the granules and poor material flowabilities. However, capping and lamination can also occur randomly and they are also dependent upon the material used in tabletting. It was possible to identify a capped or laminated tablet by monitoring the AE energy level during continuous on-line monitoring of tabletting. Capped tablets indicated by low level of AE energy. The proposed condition monitoring system aimed to set the AE energy threshold that could discriminate between capped and non-capped tablets. This was based upon statistical distributions of the AE energy values for both the capped and non-capped tablets. The system aims to minimise the rate of false alarms (indication of capping when in reality capping has not occurred) and the rate of missed detection (an indication of non capping, when in reality capping has occurred). A novel approach that employs both the AE method and the receiver operating characteristic (ROC) curve was proposed for the on-line detection of capping and lamination during tabletting. The proposed system employs AE energy as the discriminating parameter to detect between capped and non-capped tablets. The ROC curve was constructed from the area under the two distributions of both capped and non-capped tablet. This curve shows a trade-off between the probabilities of true detection rate and false alarm rate for capped and non-capped tablet. A two-graph receiver operating characteristic (ROC) curve was presented as a modification of the original ROC curve to enable an operator to directly select the desired energy threshold for tablet monitoring. This plot shows the ROC co-ordinate as a function of the threshold value over the entire threshold (AE energy) range for all test outcomes. An alternative way of deciding a threshold based on the slope of the ROC curve was also developed. The slope of the ROC curve represents the optimal operating point on the curve. It depends upon the penalties cost of capping and the prevalence of capping. Sets of guidelines have been outlined for decision making i.e. threshold setting. These guidelines take into account both the prevalence of capping in manufacturing and the cost associated with various outcomes of tablet formation. The proposed condition monitoring system also relates AE monitoring to non-AE measurement as it enable an operator predicting tablet hardness and disintegration form the AE energy, a relationship which was established in this research.
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Bürki, Kathrin Eva [Verfasser]. "Preparation of taste masked orally disintegrating tablets by compression of coated pellets / Kathrin E. Bürki." Berlin : Freie Universität Berlin, 2016. http://d-nb.info/1111558825/34.
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Nordström, Josefina. "Compression analysis as a tool for technical characterization and classification of pharmaceutical powders." Doctoral thesis, Uppsala University, Department of Pharmacy, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9214.
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There are today strong incentives for an increased understanding of material properties and manufacturing processes to facilitate the development of new technologies in the pharmaceutical industry. The purpose of this thesis was to suggest methods requiring a low sample amount for characterization of technical properties of powders.
Compression analysis was used to evaluate the formulation relevance of some compression equations. Using the mechanics of single granules to estimate powder functionality was part of this work. It was concluded that the formability of granular solids and the plasticity of single granules could be determined with compression analysis by using the Kawakita model for single components and binary mixtures of ductile granules.
Further on, the fragmentation propensity of solid particles could be estimated from compression analysis by using the Shapiro equation, enabling indicators of both the fragmentation and the deformation propensity of particles to be derived in one single compression test.
The interpretations of the compression parameters were only valid if the influence of particle rearrangement was negligible for the overall compression profile. An index indicating the extent of particle rearrangement was developed and a classification system of powders into groups dependent on the incidence of particle rearrangement was suggested as tools to enable rational interpretations of compression parameters.
The application of compression analysis was demonstrated by investigating the relevance of the mechanics of granular solids for their tableting abilities. The plasticity of single gran-ules was suggested to influence both the rate of compactibility and the mode of deformation, and consequently the maximal tablet strength. The degree of granule bed deformation was shown to be a potential in line process indicator to describe the tableting forming ability.
This thesis contributes to a scheme, suitable in formulation work and process control, to describe manufacturability of powders for an enhanced tablet formulation technology.
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Sabeh, Darwiche. "Adapting the Green and Ampt model to account for air compression and counterflow." [Tampa, Fla.] : University of South Florida, 2004. http://purl.fcla.edu/fcla/etd/SFE0000493.
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Gharbi, Nebras. "On compressing and parallelizing constraint satisfaction problems." Thesis, Artois, 2015. http://www.theses.fr/2015ARTO0406/document.
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La programmation par contraintes est un cadre puissant utilisé pour modéliser et résoudre des problèmes combinatoires, employant des techniques d'intelligence artificielle, de la recherche opérationnelle, de théorie des graphes,..., etc. L'idée de base de la programmation par contraintes est que l'utilisateur exprime ses contraintes et qu'un solveur de contraintes cherche une ou plusieurs solutions.Les problèmes de satisfaction de contraintes (CSP), sont au cœur de la programmation par contraintes. Ce sont des problèmes de décision où nous recherchons des états ou des objets satisfaisant un certain nombre de contraintes ou de critères. Ces problèmes de décision revoient vrai, si le problème admet une solution, faux, sinon. Les problèmes de satisfaction de contraintes sont le sujet de recherche intense tant en recherche opérationnelle qu'en intelligence artificielle. Beaucoup de CSPs exigent la combinaison d'heuristiques et de méthode d'inférences combinatoires pour les résoudre dans un temps raisonnable.Avec l'amélioration des ordinateurs, la résolution de plus grands problèmes devient plus facile. Bien qu'il y ait plus de capacités offertes par la nouvelle génération de machines, les problèmes industriels deviennent de plus en plus grand ce qui implique un espace _norme pour les stocker et aussi plus de temps pour les résoudre.Cette thèse s'articule autour des techniques d'optimisation de la résolution des CSPs en raisonnant sur plusieurs axes.Dans la première partie, nous traitons la compression des contraintes table. Nous proposons deux méthodes différentes pour la compression des contraintes de table. Les deux approches sont basées sur la recherche des motifs fréquents pour éviter la redondance. Cependant, la façon de définir un motif, la détection des motifs fréquents et la nouvelle représentation compacte diffère significativement. Nous présentons pour chacune des approches un algorithme de filtrage.La seconde partie est consacrée à une autre façon d'optimiser la résolution de CSP qui est l'utilisation d'une architecture parallèle. Nous proposons une méthode où nous utilisons une architecture parallèle pour améliorer le processus de résolution en établissant des cohérences parallèles. En fait, les esclaves envoient à leur maître le résultat obtenu après avoir établi la cohérence partielle en tant que nouveaux faits. Le maître, à son tour essaye de profiter d'eux en enlevant les valeurs correspondantesConstraint Programming (CP) is a powerful paradigm used for modelling and solving combinatorial constraint problems that relies on a wide range of techniques coming from artificial intelligence, operational research, graph theory,..., etc. The basic idea of constraint programming is that the user expresses its constraints and a constraint solver seeks a solution. Constraint Satisfaction Problems (CSP), is a framework at the heart of CP problems. They correspond to decision problems where we seek for states or objects satisfying a number of constraints or criteria. These decision problems have two answers to the question they encode: true, if the problem admits a solution, false, otherwise. CSPs are the subject of intense research in both artificial intelligence and operations research. Many CSPs require the combination of heuristics and combinatorial optimization methods to solve them in a reasonable time.With the improvement of computers, larger and larger problems can be solved. However, the size of industrial problems grow faster which requires a vast amount of memory space to store them and entail great difficulties to solve them. In this thesis, our contributions can be divided into two main parts. In the first part, we deal with the most used kind of constraints, which are table constraints. We proposed two compressed forms of table constraints. Both of them are based on frequent patterns search in order to avoid redundancy. However, the manner of defining pattern, the patterns-detecting process and the new compact representation differ significantly. For each form, we propose a filtering algorithm. In the second part, we explore another way to optimize CSP solving which is the use of a parallel architecture. In fact, we enhance the solving process by establishing parallel consistencies. Different workers send to their master the result of establishing partial consistencies as new discovered facts. The master, in its turns tries to benefit from them by removing corresponding values
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Chillas, Stephanie M. "The Formulation and Evaluation of Orally Disintegrating Tablets: Diphenhydramine HCl." University of Toledo Health Science Campus / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=mco1371774622.
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Joaquim, Mauricio Martinelli. "Flexão e flexo-compressão em elementos de alvenaria estrutural." Universidade de São Paulo, 1999. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-19042018-085707/.
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Este trabalho trata da verificação e dimensionamento de peças de alvenaria estrutural submetidas à flexão. Inicialmente são apresentados os conceitos básicos do método das tensões admissíveis e são desenvolvidos procedimentos para a análise do problema da flexão simples e composta reta. Em seguida discute-se o problema da flexão composta oblíqua, com ênfase à modelagem computacional necessária ao desenvolvimento de aplicativos para a análise de seções genéricas. São apresentados na seqüência dois programas computacionais, implementados a partir dos algoritmos e procedimentos desenvolvidos nos itens anteriores. Apresentam-se ainda tabelas e ábacos que permitem o cálculo das peças de alvenaria com rapidez, facilidade e segurança, algumas das quais nos moldes das já tradicionalmente utilizadas para o concreto armado. Por fim, diversos exemplos são apresentados, ilustrando a teoria exposta e a utilização de tabelas e ábacos apresentados.This study deals with the design of structural masonry pieces subjected to bending loads. At first, basic concepts of the allowable stresses method are presented and procedures for the analysis of simple bending and composed bending are developed. Next, the oblique composed bending is discussed emphasising computational modelling for the analysis of generic cross sections. Two computational procedures based on the algorithms already developed are also shown. In addition, tables and abaci that allow analysing the design of masonry elements quickly, easily and safely are presented. Some of them are very similar to those used for reinforced concrete. Finally, several examples are presented.
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Nofrerias, Roig Isaac. "Aplicació de la simulació de compressió a l’estudi del comportament i optimització de comprimits elaborats per compressió directa utilitzant el sistema expert SeDeM." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668064.
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El comprimit és la forma farmacèutica més freqüent al mercat. El procés tecnològic d’elaboració de comprimits d’elecció és la compressió directa perquè permet un estalvi en el nombre d’etapes. Tanmateix, aquest procés requereix que les pólvores presentin unes característiques adequades per la compressió per se. La necessitat de dissenyar ràpidament una fórmula farmacèutica que compleixi els estàndards de compressió i l’escalat a producció industrial, ha portat a la creació de sistemes experts i simuladors de compressió. En la present tesis, s’optimitza el sistema expert de diagrama SeDeM i es contrasta amb compressions industrials amb el simulador Styl’One. En primer lloc, es proposa una modificació en la metodologia per la determinació del paràmetre de l’Índex de cohesivitat del diagrama SeDeM, l’únic paràmetre que té en compte la compactabilitat de la mescla. Aquest paràmetre presentava desviacions per les mescles pulverulentes amb una densitat aparent molt elevada o molt baixa. També s’augmenta el nombre de paràmetres del SeDeM, afegint dos paràmetres mecànics en relació a la lubrificació. Aquests paràmetres són el punt de fusió (Mp) i la força d’ejecció (Fe). Els resultats del sistema expert de diagrama SeDeM són contrastats amb els resultats de compressió en condicions industrials. Cinc formulacions diferents es comprimeixen sota diferents perfils de compressió utilitzant un simulador de compressió industrial Styl’One. Els resultats indiquen que un ajust del pes del comprimit en funció de la densitat aparent de la pólvora permet la obtenció de comprimits de dimensions similars, evitant les desviacions esmentades. Fet demostrat en el desenvolupament d’una formulació la comparació de cel·luloses microcristal·lines de diferents fabricants i graus o tipus. També s’ha establert una metodologia ràpida i accessible per la determinació dels dos nous paràmetres mecànics i una conversió del valor experimental al valor radi. Fet que permet la seva integració en el sistema SeDeM. Els dos paràmetres integrats han demostrat tenir una rellevància en els resultats de la compressió i han permès augmentar el valor de l’índex de fiabilitat del SeDeM. Finalment, tres fórmules dissenyades per compressió directa i dues per granulació via humida es comprimeixen amb l’Styl’One simulant diferents perfils de compressió (Korsch XL 400, Fette 2909, Fette 3100, Kilian RX 47 i Kilian S 250) de màquines de comprimir rotatòries sota condicions de compressió diferents. Els resultats de la compressió demostren la precisió dels resultats previs obtinguts en els diagrames SeDeM i indiquen una relació entre valors deficients per l’Índex de Carr i l’Índex d’esponjositat i problemes d’exfoliació durant la compressió. L’addició d’una força de precompressió permet solucionar els problemes d’exfoliació en la majoria de les Referències. Els resultats indiquen que les referències desenvolupades per compressió directa presenten uns resultats equiparables o superiors a les referències per granulació via humida, amb un impacte econòmic menor (temps i costos) en el seu desenvolupament. En conclusió, s’ha optimitzat el sistema SeDeM, corregint desviacions i augmentant l’índex de fiabilitat. El simulador de compressió Styl’One ha posat de manifest la precisió i robustesa del sistema SeDeM en la selecció de la formulació més òptima i permet seleccionar les condicions de compressió més òptimes, maximitzar l’eficiència del procés i facilitar l’escalat.Tablets are the most common solid oral dosage forms. Direct Compression (DC) is a good methodology due to its low manufacturing times and a reduced number of steps. However, this methodology requires powders which display adequate properties in order to be compressible. The need of a swift design of pharmaceutical formulations which fulfill the compression standards and the scale-up led to create expert systems and press simulators. In this thesis, the expert system SeDeM is optimized: a new methodology to determine the Cohesion Index is stablished and two new mechanical parameters are introduced (Melting point and Ejection Force). Then, the results obtained from the SeDeM diagram are compared against the results obtained from the Styl’ONE press simulator in simulated industrial conditions. The results indicates that the new methodology is more accurate and it has been demonstrated in the development of a formula, and the comparison of different Microcrystalline Celluloses from different manufacturers. The inclusion of the two new mechanical parameters has increased the SeDeM’s reliability index. Then, three formulas developed by DC and two developed by wet granulation were compressed by means of Styl’One press simulator. Five different rotatory press’ compression profiles were simulated (Korsch XL 400, Fette 2090, Fette 3100, Kilian RX 47 I Kilian S 250) under different compression conditions. The results show the accuracy of SeDeM system and seems to indicate a correlation between Carr’s Index and Inter particle porosity Index, low radius values and capping phenomenon during the compression process. These issues where solved by applying a pre-compression force. Moreover, the DC formulas display results similar or higher than the wet granulation formulas. In conclusion, the SeDeM expert system has been optimized, correcting the Cohesion Index deviations and increasing the reliability index by adding two mechanical parameters. The Styl’One press simulator has enabled to highlight the SeDeM system’s accuracy and robustness on choosing the most optimal formulation as well as the most optimal compression conditions in order to maximize the process’ efficiency and the scale-up.
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Lukyanets, Yuliya. "The Green and Ampt Infiltration Model Accounting for Air Compression and Air Counterflow in the Shallow Water Table Environment: Laboratory Experiments." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3471.
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Water infiltration into the unsaturated zone especially in a shallow water table environment is affected by air compression ahead of the wetting front and air counterflow. Neglecting air compression in infiltration modeling can overestimate infiltration and infiltration rates, whereas not accounting for air counterflow can underestimate infiltration and infiltration rates due to unrealistic buildup of air pressure resistance ahead of the wetting front. A method, derived on the basis of the Green and Ampt (1911) infiltration model, is introduced to simulate air compression and air counterflow during infiltration into a shallow water table. The method retains the simplicity of the Green and Ampt (1911) model but adds the air pressure resistance term ahead of the wetting front. Infiltration equations are derived on the basis of the Green and Ampt (1911) and Sabeh’s (2004) infiltration model which accounts for air compression and air counterflow. The difference between this method and Sabeh’s (2004) model is that air counterflow, air compression, and infiltration are decoupled and updated with each wetting front increment whereas Sabeh’s (2004) method uses time step as a decoupling mechanism. Air compression ahead of the wetting front is predicted using the perfect gas law.
Laboratory experiments showed that the introduced method is reasonably accurate when modeling cumulative infiltration values. Results of laboratory experiments were compared to results of the modeled infiltration methods: original Green and Ampt (1911) model and Green and Ampt with air compression and counterflow.
The advantage of this new method is its simplicity. The new method uses parameters that are generally needed for modeling infiltration with the Green and Ampt (1911) approach. Disadvantages of the model are assumptions of the uniform water content and the uniform pressure. Another shortcoming of the model is that it does not account for air compression and air counterflow prior to ponding.
Laboratory experiments described in this work and a proposed model can be further used for modeling and studying infiltration with air effects. In addition, this work can be of use to someone studying irrigation techniques of rice or other crops.
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Kratz, Cristiane de Pellegrini. "Obtenção de comprimidos contendo grânulos deformantes e grânulos revestidos gastro-resistentes." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2002. http://hdl.handle.net/10183/147657.
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Sistemas monolíticos particulados contendo os constituintes ativos veiculados na forma de grânulos revestidos - pellets - têm recebido crescente atenção nos últimos anos, em função da otimização na biodisponibilidade e segurança na liberação do fármaco. A utilização destas unidades, como componentes de comprimidos traz, como principal vantagem, a divisibilidade da forma sem a perda do perfil biofarmacêutico desejado para o fármaco. Para sua produção, é indispensável a manutenção da integridade do revestimento daquelas unidades. Uma estratégia para o alcance deste objetivo envolve a utilização de grânulos inertes deformantes, comprimidos em conjunto com os grânulos revestidos, que atuam como um sistema de amortecimento das forças de compressão. Neste trabalho investigou-se a produção de grânulos deformantes através de dois métodos de granulação por via úmida, avaliando a influência de adjuvantes sobre as características dos produtos obtidos. Empregando a técnica de extrusão/esferonização obtiveram-se grânulos com propriedades de fluxo, empacotamento e resistência mecânica aceitáveis. O efeito dos adjuvantes sobre as etapas tecnológicas foi estudado por meio de um planejamento fatorial. Testaram-se duas variedades de celulose microcristalina, os desintegrantes croscarmelose sódica e crospovidona e soluções aglutinantes aquosas e hidroetanólicas de povidona. Para o desenvolvimento dos comprimidos utilizaram-se, como modelo, grânulos revestidos gastro-resistentes contendo omeprazol. A influência da composição dos grânulos deformantes sobre a liodisponibilidade do fármaco dos comprimidos foi avaliada através de análise fatorial 23. Os grânulos deformantes protegeram o revestimento polimérico dos pellets com diferentes intensidades.Monolythic particulate systems containing the active constituents as coated pellets became great interest due to the improvement of safety and bioavailability. The use of such units as components of tablets shows as main advantages the divisibility of the pharmaceutical dosage form without loosing the desired biopharmaceutical profile of the drug. Consequently for the tablet production, the integrity of the polymeric film must be attained. A strategic option involves the utilization of inert soft pellets, which could be compressed together with the film coated pellets, absorbing the compaction forces. In this work the production of soft pellets was investigated using two wet granulation methods and evaluating the influence of formulation adjuvants on the pellets properties. The extrusion/spheronization technique yielded pellets with acceptable flow, packing and mechanical characteristics. The influence of the adjuvants on the technological steps was carried out through a statistical designed experiment. Microcrystalline cellulose from two producers, the disintegrants sodium croscarmellose and crospovidone, and aqueous and hydroethanolic dispersions of povidone, as binder, were tested. For the tablets development omeprazol gastroresistant film coated pellets were used as model. Aiming at the study of the influence of the soft pellets composition on drug lyoavailability was performed a 23 factorial experiment. The soft pellets protected at different intensities the polymeric coating of the gastroresistant pellets.
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Gallé, Matthias. "Searching for Compact Hierarchical Structures in DNA by means of the Smallest Grammar Problem." Phd thesis, Université Rennes 1, 2011. http://tel.archives-ouvertes.fr/tel-00595494.
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Motivé par la découverte automatique de la structure hiérarchique de séquences d'ADN, nous nous intéressons au probléme classique de la recherche de la plus petite grammaire algébrique générant exactement une séquence donnée. Ce probléme NP-dur a été largement étudié pour des applications comme la compression de données, la découverte de structure et la théorie algorithmique de l'information. Nous proposons de décomposer ce probléme en deux problémes d'optimisation complémentaires. Le premier consiste á choisir les chaînes de la séquence qui seront les constituants de la grammaire finale alors que le second, que nous appelons ''analyse grammaticale minimale'', consiste á trouver une grammaire de taille minimale permettant l'analyse syntaxique de ces constituants. Nous donnons une solution polynomiale au probléme d' ''analyse grammaticale minimale'' et montrons que cette décomposition permet de définir un espace de recherche complet pour le probléme de la plus petite grammaire algébrique. Nous nous intéressons aux algorithmes praticables permettant de retourner une approximation du probléme en un temps suffisamment raisonnable pour être appliqués á de grandes séquences telles que les séquences génomiques. Nous analysons l'impact de l'utilisation de classes différentes de maximalité de répétitions pour le choix des constituants et le compromis entre l'efficacité et la taille de la grammaire finale. Nous présentons des avancées algorithmiques pour une meilleure efficacité des algorithmes hors-ligne existants, dont notamment la mise á jour incrémentale de tableaux de suffixes en cours de recodage. Enfin, la nouvelle décomposition du probléme nous permet de proposer de nouveaux algorithmes génériques permettant de trouver des grammaires 10\% plus petites que l'état de l'art. Enfin, nous nous intéressons á l'impact de ces idées sur les applications. En ce qui concerne la découverte de structures, nous étudions le nombre de grammaires minimales et montrons que ce nombre peut être exponentiel dans le pire cas. Nos expérimentations sur des jeux de séquences permettent cependant de montrer une certaine stabilité de structure au sein des grammaires minimales obtenues á partir d'un ensemble de constituants. En ce qui concerne la compression des données, nous contribuons dans chacune des trois étapes de la compression á base de grammaires. Nous définissons alors un nouvel algorithme qui optimise la taille de la chaine de bits finale au lieu de la taille de la grammaire. En l'appliquant sur les séquences d'ADN, nos expérimentations montrent que cet algorithme surpasse tout autre compresseur spécifique d'ADN á base de grammaire. Nous améliorons ce résultat en utilisant des répétitions inexactes et arrivons á améliorer les taux de compression de 25\% par rapport aux meilleurs compresseurs d'ADN á base de grammaire. Outre l'obtention de taux de compression plus performants, cette approche permet également envisager des généralisations intéressantes de ces grammaires.
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Campolina, Alessandro Gonçalves. "O efeito da eliminação de doenças crônicas na população idosa: a compressão e a expansão da morbidade." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/6/6132/tde-18042012-084358/.
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Introdução: No contexto do envelhecimento populacional, uma questão fundamental é avaliar se as estratégias de prevenção de doenças crônicas poderiam contribuir para o aumento dos anos vividos em boas condições de saúde, pela população idosa. Objetivo: Avaliar se a eliminação de determinadas doenças crônicas é capaz de levar à compressão da morbidade em indivíduos idosos. Métodos: Estudo transversal analítico, de base populacional, utilizando dados oficiais secundários para o Município de São Paulo, em 2000, e dados obtidos a partir do estudo SABE. O método de Sullivan foi utilizado para o cálculo de expectativas de vida livre de incapacidade (E.V.L.I.). O impacto da eliminação de uma doença na prevalência de incapacidade foi estimado com um modelo de regressão logística múltipla. Tábuas de vida de eliminação de causas foram utilizadas para calcular as probabilidades de morte com a eliminação de doenças. O efeito da eliminação das doenças crônicas foi avaliado, considerando a teoria de riscos competitivos e a abordagem proposta por Nusselder e colaboradores. Resultados: Os maiores ganhos em E.V.L.I., com a eliminação de doenças crônicas, ocorreram no sexo feminino, levando a um processo de compressão absoluta da morbidade. Nos indivíduos de idade mais avançada, os ganhos em E.V.L.I., ocorreram em função de um processo de compressão relativa da morbidade. Nos homens com idade de 75 anos, todas as doenças estudadas, com exceção da doença cardíaca e da hipertensão arterial sistêmica, levaram a um processo de expansão absoluta da morbidade, mas simultaneamente a um processo de compressão relativa da morbidade, ao serem eliminadas. A doença cardíaca apresentou-se como aquela que mais promoveria a compressão da morbidade, caso fosse eliminada, em ambos os sexos. Conclusão: A eliminação de doenças crônicas na população idosa poderia levar a uma compressão da morbidade em homens e mulheres, tanto na idade de 60 anos, quanto na de 75 anosIntroduction: In the context of the aging process, a key issue is to assess whether strategies to prevent chronic diseases may contribute to the increase in years lived in good health among elderly individuals. Objective: To evaluate whether elimination of certain chronic diseases can lead to the compression of morbidity, in the elderly. Methods: Analytical cross-sectional survey, based on official data for the city of São Paulo, in 2000, and data obtained from the SABE study. Sullivans method was used for the calculation of disability-free life expectancy (DFLE). Cause-deleted disability prevalence was estimated using multiple logistic regression model. Cause-deleted probabilities of dying were derived with the cause-elimination life-table technique, considering the independence of the causes of based on the approach proposed by Nusselder and co-workers. Results: The greatest gains in DFLE, with the elimination of chronic diseases, occurred in women, leading to a process of absolute compression of morbidity. Among individuals of a more advanced age, gains in DFLE occurred due to a relative compression of morbidity process. Among men aged 75 years, all diseases eliminated, except heart disease and hypertension, led to a process of absolute expansion of morbidity, but simultaneously, to a relative compression of morbidity. If eliminated, heart disease was the condition that would most lead to the compression of morbidity in both genders. Conclusion: The elimination of chronic diseases in the elderly population could lead to the compression of morbidity in men and women at both 60 years of age and in 75 years of age or older
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Kaščák, Andrej. "Komprese záznamů o IP tocích." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2011. http://www.nusl.cz/ntk/nusl-235520.
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My Master's thesis deals with the problems of flow compression in network devices. Its outcome should alleviate memory consumption of the flows and simplify the processing of network traffic. As an introduction I provide a description of protocols serving for data storage and manipulation, followed by discussion about possibilities of compression methods that are employed nowadays. In the following part there is an in-depth analysis of source data that shows the structure and composition of the data and brings up useful observations, which are later used in the testing of existing compression methods, as well as about their potential and utilization in flow compression. Later on, I venture into the field of lossy compression and basing on the test results a new approach is described, created by means of flow clustering and their subsequent lossy compression. The conclusion contains an evaluation of the possibilities of the method and the final summary of the thesis along with various suggestions for further development of the research.
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Vorel, Pavel. "Vlastnosti betonů s přídavkem plazmatem upravených polypropylenových vláken." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-225879.
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Master‘s thesis focuses on concrete combined with polypropylen fibres produced commercially, fibres without surface modifications and fibres modificated by plasma. Most important topic of the thesis is experimental verification of influence of plasma modificated fibres on attributes of fresh concrete and physical-mechanical attributes of solidified concrete. Based on the results of the tests perfomed on examin units compares results and anylyses applicability of different fibre surface modifications.
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Altaf, Syed Azhar. "Tablet machine instrumentation to study tablet compaction and compression of polymer-coated beads into tablets." Thesis, 1995. http://hdl.handle.net/1957/34666.
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CHEN, SHU-LING, and 陳淑玲. "1. Direct compression studies on metronidazole tablet formulation 2.Studies on the improvement of three layer tablet formulation." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/98184809930606479223.
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Rowe, Raymond C., A. P. Plumb, Peter York, and M. Brown. "Optimisation of the predictive ability of artificial neural network (ANN) models: A comparison of three ANN programs and four classes of training algorithm." 2005. http://hdl.handle.net/10454/3011.
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NoThe purpose of this study was to determine whether artificial neural network (ANN) programs implementing different backpropagation algorithms and default settings are capable of generating equivalent highly predictive models. Three ANN packages were used: INForm, CAD/Chem and MATLAB. Twenty variants of gradient descent, conjugate gradient, quasi-Newton and Bayesian regularisation algorithms were used to train networks containing a single hidden layer of 3¿12 nodes. All INForm and CAD/Chem models trained satisfactorily for tensile strength, disintegration time and percentage dissolution at 15, 30, 45 and 60 min. Similarly, acceptable training was obtained for MATLAB models using Bayesian regularisation. Training of MATLAB models with other algorithms was erratic. This effect was attributed to a tendency for the MATLAB implementation of the algorithms to attenuate training in local minima of the error surface. Predictive models for tablet capping and friability could not be generated. The most predictive models from each ANN package varied with respect to the optimum network architecture and training algorithm. No significant differences were found in the predictive ability of these models. It is concluded that comparable models are obtainable from different ANN programs provided that both the network architecture and training algorithm are optimised. A broad strategy for optimisation of the predictive ability of an ANN model is proposed.
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Bani, Jaber Ahmad Kh. "Formulation and in vitro-in vivo evaluation of a new compression-coated tablet of amoxicillin/clavulanate and formulation potential of the antimicrobial peptide nisin." Thesis, 1998. http://hdl.handle.net/1957/33186.
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This thesis is compromised of two distinct formulation sections, which are described below:
New compression-coated tablet formulations were developed for amoxicillin/clavulanate. Amoxicillin in an outer coat was separated from clavulanic acid in a core tablet by inactive ingredients in a middle coat. A chewable compression-coated tablet formulation with 50% stearic acid in the middle coat showed high clavulanic acid stability in comparison to the marketed traditional tablet formulation. Stearic acid acted
as a hydrophobic barrier that prevents passage of moisture through the outer coats into
the core and it helped in the bonding of the outer coats to the core because it softens upon
compression. The bioavailability of clavulanic acid, however, was reduced which was
attributed to the effect of stearic acid. Stearic acid was removed from the formulation of
swallow tablets and replaced with Avicel��, consequently, the outer coat did not adhere
tightly to the core and tended to cap off, which resulted in low stability of clavulanic acid.
In bioavailability studies of the swallow tablets, the two formulations were equivalent to the marketed formulation for amoxicillin, but not for clavulanic acid, which is most likely due to the small sample size studied and high intersubject variation.
Nisin, an antimicrobial protein, was evaluated for ability to emulsify oil-in-water using conductivity measurements. In comparison to Tween�� 80 and ��-casein, nisin showed substantial emulsifying activity. The emulsifying activity was found to be highly concentration- and pH-dependent. Nisin was found to form a gel-like structure at the oil water interface which retarded release of the drug sulfasalazine. Interfacial tension kinetics exhibited by nisin at an oil-water interface were monitored with DuNoy tensiometry. Interfacial pressure kinetics were interpreted with reference to a simple model that allows for a protein to be adsorbed in structurally dissimilar states. The model suggested that nisin's tendency to adapt a more unfolded structure at the oil-water interface increases with decreasing concentration. The effects of nisin on drug release from oil-in-water emulsions, and on erythrocytes were evaluated as well. It was found that nisin retards drug release in emulsions and lyses red blood cells.Graduation date: 1999
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Penedo, Maria Simões. "Novel shape in scored orodispersible tablets applying Design of Experiments." Master's thesis, 2017. http://hdl.handle.net/10451/36072.
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Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2017Drug Delivery Systems (DDS) are a strategic tool that has become increasingly sophisticated over the years. Their main contributions involve expanding the life cycle of pharmaceutical products, by improving the administration process according to the patient’s needs. Since the drug delivery through oral route still represents the most common and preferred way of drug administration, our work of study relies on the development of orodispersible tablets (ODTs). This dosage form provides a quick onset of action and therefore was chosen as an alternative for paediatric, geriatric and mentally ill patients were the swallowing ability may be compromised. In the present study orodispersible tablets with a new shape were produced by direct compression using furosemide as the model drug. The production with this novel punch design led to scored tablets with a cloverleaf shape, thus allowing dose flexibility. The tablets were evaluated by thickness and diameter, uniformity of weight and of content, uniformity of the tablet’s subunits, resistance to crushing, weight loss, wetting time, water absorption ratio and disintegration time. Through Design of Experiments (DoE) was done a 22x31 full-factorial test that showed the influence of three independent variables (upper punch compression force, tablet weight and speed of rotation of tabletting machine) on the tablet’s properties. The obtained ODTs were according to the limits for both weight and content uniformity and revealed tablet units with very low coefficients of variation and satisfactory mean percentages of furosemide. The results for resistance to crushing revealed very high values corroborated by low friability of tablets. They also showed uniformity of the subdivided tablets with very low mass deviations and minimum percentage of mass lost during breaking process. The biopharmaceutical tests revealed a different outcome of what was expected from this dosage form. All the disintegration and wetting times failed to comply with the required standards along with the water absorption ratio, thus showing space for improvement.
Os sistemas de administração de fármacos têm, ao logo do tempo, logrado obter um acentuado grau de desenvolvimento com o objetivo de ultrapassar as limitações terapêuticas existentes. Como principal objetivo é visada a expansão do ciclo de vida dos produtos farmacêuticos, bem como melhorar o processo de administração dos mesmos de acordo com as necessidades da população alvo. Uma vez que a via oral representa o modo de administração mais comum e utilizado, o presente trabalho tem como objeto de estudo o desenvolvimento de comprimidos orodispersíveis (ODTs). Esta forma farmacêutica proporciona um início de ação rápido e apresenta como aspeto diferenciador o seu possível uso em pacientes pediátricos, geriátricos e mentais, onde a capacidade de deglutição pode estar comprometida. No presente estudo, os comprimidos orodispersíveis com furosemida como fármaco-modelo foram produzidos por compressão direta e apresentavam uma forma inovadora. Na produção recorreu-se ao uso de punções em forma de trevo de quatro folhas, originando comprimidos divisíveis em quatro, permitindo assim possíveis ajustes de dose. Os comprimidos foram posteriormente avaliados em termos de espessura e diâmetro, uniformidade de teor e massa, uniformidade da divisão em quatro partes do comprimido, resistência ao esmagamento, friabilidade, tempo de molhamento, quantidade de água absorvida e tempo desintegração. Através do desenho experimental, fatorial (22x31), foi possível avaliar a influência de três variáveis independentes (força de compressão do punção superior, massa do comprimido e velocidade de rotação da máquina de comprimidos) nas propriedades dos comprimidos produzidos. Os comprimidos obtidos encontravam-se de acordo com os limites estabelecidos de uniformidade de teor e massa e, após divisão, apresentaram subunidades com coeficientes de variação muito baixos e com percentagens de furosemida satisfatórias. Os resultados de resistência ao esmagamento revelaram valores muito elevados corroborados pela baixa friabilidade de comprimidos. Constatou-se ainda a uniformidade de massa nas subdivisões dos comprimidos, com desvios muito baixos e percentagens mínimas de perda de massa durante o processo de quebra. Os testes biofarmacêuticos revelaram um resultado diferente do esperado para esta forma farmacêutica. Os tempos de desintegração e molhamento não cumpriram com os padrões exigidos, bem como o índice de absorção de água que se revelou baixo, o que induz ainda existir espaço para melhoria.
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Brtnová, Soňa. "Hodnocení doby rozpadu tablet obsahujících theofylin." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-331742.
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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Thesis supervisor: Doc. PharmDr. Zdeňka Šklubalová, Ph.D. Consultant: Mgr. Pavel Ondrejček Student: Soňa Brtnová Title of Thesis: Evaluation of disintegration time of tablets containing theophylline The influence of used fillers on energetic profile of compression, especially influence on disintegration time of tablets with theophylline as a model drug, was studied in this thesis. Four tablet fillers were studied - microcrystalline cellulose Comprecel 102, lactose SpheroLac 100, calcium hydrogen phosphate anhydrous Di- Cafos A150 and calcium hydrogen phosphate dihydrate Di-Cafos D160. Tablets contained different proportion of two fillers, theophylline as a model drug and lubricant magnesium stearate. Tablets were compressed by the same compaction force 10 kN. The force- displacement record was evaluated using the particular energies of compaction process. Parameters of compaction process were influenced mostly by Comprecel 102. According to results there is no possibility to replace Di-Cafos D160 with Di-Cafos A150 in the mixtures. It was also found that SpheroLac 100 and Di-Cafos D160 shows similar behavior. Time of disintegration of tablets is mostly dependent on the used fillers. Tablets...
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Janoutová, Hana. "Hodnocení radiální pevnosti tablet obsahujících theofylin." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-331743.
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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Consultant: Doc. PharmDr. Zdeňka Šklubalová, Ph.D. Student: Hana Janoutová Title of Thesis: Evaluation of tensile strength of tablets containing theophylline The aim of this thesis was to determine tensile strength of tablets containing theophylline. Tensile strength was studied as a function of the composition of mixtures of the used fillers and especially on their ratio. In the theoretical part, the used materials - lactose SpheroLac 100, microcrystalline cellulose Comprecel 102, dibasic calcium phosphate dihydrate Di-Cafos D160, anhydrous dibasic calcium phosphate Di-Cafos A150, theophylline and magnesium stearate are described. This work also evaluates force-displacement record, tensile strength and various factors that affect tensile strength. Parameters of force-displacement record and tensile strength of the tablets compressed with compresssion force 10 kN were evaluated in the experimental part. The measured results show that higher values of precompression energy (E1) and energy of plastic deformation (E2) were detected in mixtures A, C and E which contain Comprecel 102, and the lowest values were detected in mixtures B which contain Sphero-Lac 100 and Di-Cafos D160. Values of energy...
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Matyášová, Andrea. "Hodnocení lisovatelnosti tablet s theofylinem pomoci lisovací rovnice." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-331958.
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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department: Department of Pharmaceutical Technology Consultant: Doc. PharmDr. Zdeňka Šklubalová, Ph.D. Student: Andrea Matyášová Title of Thesis: Evaluation of compressibility of tableting mixtures containing theophylline using a compaction equation This thesis is aimed at the evaluation and comparison of excipients used in production of tablets. The compaction process of these excipients was evaluated using the parameters of the compaction equation. The mixtures of four fillers in various ratios were evaluated. These mixtures contained also theophylline as model drug and magnesium stearate as lubricant. The used three-exponential equation was previously developed by doc. RNDr. Milan Řehula, CSc. By using this compaction equation the volume reductions, speeds of volume reductions and consumed energies were calculated and evaluated. The results of this work showed that particular used fillers have different effect on the compaction process flow. That is caused primarily by different behavior of these materials during compaction and by formation of different types of bonds. Also the need of thorough cleaning and drying of compaction aid before compaction was confirmed.
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Brunettová, Monika. "Stanovení sypnosti směsí pro přípravu tablet s theofylinem." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-334692.
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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Consultant: Doc. PharmDr. Šklubalová Zdeňka, Ph.D. Student: Brunettová Monika Title of Thesis: Determination of flow properties of mixtures for preparation of tablets containing theophylline The aim of this diploma thesis was to characterize the flow properties and moisture content of mixtures for preparation of tablets containing theophylline. Parameters were monitored depending mainly on the content of the fillers, that were dicalcium phosphate, microcrystalline cellulose and lactose. Twenty-five prepared mixtures with different ratios of these fillers were evaluated. Flowability was evaluated by three methods stated in Czech Pharmacopoeia 2009 - compressibility index and Hausner ratio, flow through an orifice and angle of repose. Moisture content was evaluated as a weight loss during drying. Mixtures containing dicalcium phosphate and lactose proved more appropriate in terms of flowability, their flow properties are passable. However, according to the moisture content, mixture with microcrystalline cellulose are more preferable.
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Hofmanová, Markéta. "Měření stresové relaxace směsí mikrokrystalické celulosy a hydrogenfosforečnanu vápenatého určených k přípravě tablet s theofylinem." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-335187.
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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical technology Consultant: Doc. PharmDr. Sklubalova Zdenka, Ph.D. Student: Marketa Hofmanova Title of Thesis: Measurement of stress relaxation of mixtures of microcrystalline cellulose and calcium hydrogen phosphate intended for the preparation of tablets with theophylline The powder mixtures with theophylline were studied from the aspect of viscoelastic properties of used materials and tablets tensile strength. In the theoretical part the thesis concerned with description of materials which were used in the mixtures. They are: Microcrystalline cellulose Comprecel 102, calcium hydrogen phosphate anhydrate Di-Cafos A150, calcium hydrogen phosphate dihydrate Di-Cafos D160 and lactose SpheroLac 100. The thesis also deals with the stress relaxation test. The stress relaxation test, its evaluation by several methods and its use in the pharmacy and in different fields are described. The experimental part deals with viscoelastic characteristics of the mixtures. These characteristics were evaluated by stress relaxation test with maximal compression force 10 kN and dwell time 180 s. Also the tensile strength was evaluated. The highest values of parameters of elasticity A1-3 and plasticity P1-3 were measured in...
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Vitverová, Barbora. "Hodnocení relaxace tablet s theofylinem." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-337827.
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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Consultant: Doc. PharmDr. Šklubalová Zdeňka, Ph.D. Student: Barbora Vitverová Title of Thesis: Evaluation of elastic recovery of tablets containing theophylline This diploma thesis deals with evaluation of elastic recovery of tablets containing theophylline. The axial and radial elastic recovery is evaluated. Used materials are characterized in a theoretical part. It concerns microcrystalline cellulose Comprecel 102, lactose SpheroLac 100, calcii hydrogenphosphas anhydrous Di- Cafos A150, calcii hydrogenphosphas dihydrate Di-Cafos D160, magnesii stearas and theophylline. Further, compression process and its evaluation are described and also the elastic recovery of tablets after compression, its calculation and factors which can influence it. The experimental part of thesis deals with the elastic recovery of tablets. The tablets were compressed by compression strength 10 kN and the height and diameter were measured after 0, 3, 6 and 24 hours after compressing. The elastic recovery of tablets was calculated from these values. The dimensions of tablets at the maximal compression strength 10 kN were used as the initial values. From results is obvious that the highest elastic recovery is...
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Kousoulidou, Viktoria. "Determination of the compressibility of excipients used for formulation of tablets with theophylline." Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-332629.
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1 Abstract Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Consultant: Assoc. Prof. PharmDr. Zdenka Sklubalova, Ph.D. Student: Viktoria Kousoulidou Title of Thesis: Determination of the compressibility of excipients used for formulation of tablets with theophylline The current thesis is focused on the compressibility properties of five powders used in tablet formulation: Comprecel, Spherolac, DI-CAFOS D160, DI-CAFOS A150 as excipients and Theophylline as the active substance. The particle size, moisture content, bulk density and flowability of the powders are determined. The powders are compressed and the results are evaluated by means of the parameters of the compaction equation and the force-displacement method (compression under 5, 10, 15 kN). Then, the crushing strength of tablets prepared from each powder by the force-displacement method is measured. The average values of the crushing strength are used to calculate the tensile strength of the tablets. Best compressibility is found in Comprecel and Theophylline with tensile strength values of 1.31 MPa under 5 kN, 3.31 MPa under 10 kN, 4.75 MPa under 15 kN and 1.02 MPa under 5 kN, 2.27 MPa under 10 kN, 3.09 MPa under 15 kN, respectively.
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Vávrová, Kateřina. "Hodnocení disoluce tablet obsahujících theofylin a směsi dvou typů hydrogenfosforečnanu vápenatého a mikrokrystalické celulosy." Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-367733.
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Charles University in Prague, Faculty of Pharmacy in Hradci Králové Department of Pharmaceutical technology Consultant: PharmDr. Pavel Ondrejček, Ph.D. Student: Kateřina Vávrová Title of Thesis: Dissolution testing of tablets containing theophylline and mixtures of two types of calcium hydrogen phosphates and microcrystalline cellulose The aim of this thesis was the dissolution testing of tablets containing theophylline, the mixture of two dicalcium phosphate types and microcrystalline cellulose. The influence of tablet composition on the dissolution profiles was evaluated. The tablets were prepared from the mixtures containing microcrystalline cellulose, dicalcium phosphate anhydrous and dihydrate. These substances were used as fillers. Prepared mixtures contained theophylline as a model active ingredient and magnesium stearate as lubricant. Afterwards, the dissolution tests were done. For these tests, the basket method was utilized. As a dissolution medium the 0,1M hydrochloric acid solution was used. From the results of this experiment we concluded that we can influence the total amount of released theophylline and the speed of its release by the different ratio of microcrystalline cellulose and one of dicalcium phosphate types. The fastest theophylline dissolution was in tablets with high...
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Su, Cheng-Chien, and 蘇正建. "Compression Techniques for Packet Classification Table in TCAM." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/68566655153601726941.
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碩士國立成功大學
資訊工程學系碩博士班
93
Packet classification is an enabling function for a variety of Internet applications including Quality of Service, security, monitoring, and multimedia communications. In order to classify a packet as belonging to particular flow or set of flows, network nodes must perform a search over a set of filters using multiple fields of the packet as the search key. In general, there have been two major threads of research addressing packet classification: software and hardware. A Ternary Content Addressable Memory (TCAM) is a hardware solution for packet classification. When we store the classification tables in TCAM, it will waste too much TCAM space since the port fields of the classification tables are arbitrary ranges. In the worst-case, it needs O(W) prefixes for a range in W-bit address space. Consider the standard 5-tuple rule tables in which source and destination ports are ranges. The worst-case number of prefix entries is O(nW2) if we store n 5-tuple rules in TCAM. For efficiently using the TCAM space, we need to compress the classification table in an efficient way. In this thesis, we propose a scheme that can compress the TCAM space efficiently. The scheme first re-encode the port field of the classification tables, hence, we can use less number of bits to represent the port field. Moreover, each arbitrary range in port fields can be stored in only few TCAM entries. Experiment results conducted according to nine synthetic classification tables indicate our scheme save 67-83 percent of the TCAM space. In worst case, the TCAM storage complexity is reduced from O(nw2) to O(nlog2n).