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Revestimento de partículas por solidificação de material fundido em leitos de jorro e fluidizado: estudo do processo, caracterização das partículas e preparo de comprimidos ; Hot-melt coating in spouted and fluidized beds: study of the process, particle characterization and tablet pressing.

Borini, Giovanna Bonfante
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 25/05/2007 PT
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No revestimento por solidificação de material fundido o agente de revestimento é aplicado em seu estado liquefeito e se solidifica na superfície do substrato, formando a cobertura desejada, eliminando o uso de solventes. O presente trabalho teve como objetivo estudar dois tipos de processo: revestimento de partículas grandes em leito de jorro e revestimento de partículas finas em leito fluidizado, e avaliar a influência de parâmetros do processo sobre propriedades físicas e farmacotécnicas das partículas revestidas, assim como usá-las no preparo de comprimidos. As partículas grandes foram revestidas com PEG 4000, sendo o estudo do processo feito através de um planejamento fatorial completo 23 com triplicatas no ponto central. As variáveis estudadas foram pressão do ar de atomização, vazão de atomização e altura do bico de atomização. Para as partículas revestidas foram determinados a distribuição granulométrica, o fator de Hausner e o índice de Carr. Os comprimidos destas partículas foram submetidos a ensaios de dissolução in vitro, para avaliação dos perfis de liberação de paracetamol. As partículas finas foram revestidas com uma dispersão sólida de PEG 4000 e curcumina, sendo o estudo do processo feito através de um planejamento fatorial completo 23...

Revestimento de grânulos farmacêuticos em leito fluidizado; Fluidized bed coating of pharmaceutical granules.

Rezende, Fabiano de Araújo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/10/2007 PT
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Operações de revestimento são amplamente utilizadas em diversos setores industriais, tais como químico, agrícola, alimentício e farmacêutico. Dentre as principais razões para a aplicação de revestimento em partículas destacam-se fatores estéticos, proteção e o controle da taxa de dissolução de substâncias químicas. Este trabalho teve por objetivo investigar o revestimento de sólidos farmacêuticos em leito fluidizado. Inicialmente foram realizados ensaios fluidodinâmicos visando à definição de parâmetros operacionais nos quais ocorre uma operação estável do sistema. Definidas condições de operação estável, realizaram-se ensaios de revestimento de grânulos contendo um fármaco modelo (paracetamol), empregando-se uma composição à base de Eugradit RS30D. Nesta etapa investigou-se a influência da vazão de ar de fluidização, do diâmetro das partículas, da temperatura do ar de fluidização e da vazão de suspensão de revestimento na fração revestida, Wrt; na eficiência do revestimento, ; e no índice de aglomeração, Agl. Ensaios de liberação in vitro foram realizados no sentido de se avaliar a alteração das propriedades de liberação do fármaco devido ao revestimento aplicado. Os resultados obtidos evidenciaram que um tempo maior de processo levou à formação de um filme de revestimento mais espesso...

Obtenção de um revestimento compósito de poliéster-uretana reforçado com alumina pela técnica de deposição por imersão sobre fibras de poliamida 6; Preparation of a composite coating of alumina reinforced polyester urethane by dip coating on polyamide 6 fibers

Sánchez, Felipe Antonio Lucca; Reifler, Felix A.; Clemens, Frank; Amico, Sandro Campos; Bergmann, Carlos Perez
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
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O uso de revestimentos compósitos de matriz polimérica e reforço cerâmico capazes de manter a flexibilidade e a elasticidade das fibras poliméricas, agregando propriedades típicas dos materiais cerâmicos (como ação bactericida ou fotocatalítica, resistência à chama, ao desgaste e à abrasão), tem atraído interesse da indústria têxtil. Baseado na técnica dip coating e usando fibras sintéticas de poliamida como substrato, foram produzidas suspensões de poliéster-uretana com partículas de alumina (tamanho médio de partícula 2,2 μm) para obtenção de revestimentos uniformes e espessos sobre o material base, poliamida 6. A viscosidade das suspensões foi controlada pela adição de carboximetilcelulose e avaliada por reometria rotacional. A distribuição granulométrica das suspensões também foi determinada. Os parâmetros operacionais do dip coating, i.e., velocidade de bobinamento e temperatura dos fornos, foram mantidos constantes em todas as amostras. O processo mostrou viabilidade para deposição uniforme do recobrimento avaliado, com espessura adequada, indicando ser promissor para revestir fibras, agregando propriedades de interesse tecnológico.; Ceramic reinforced polymer composite coatings that can retain the flexibility and elasticity of the polymeric fibers...

Soldagem a ponto por resistencia eletrica de juntas de chapa/chapa e chapa/tubo de aço de baixo carbono com diferentes composições quimicas, espessuras e revestimentos; Resistance spot welding of low-carbon steel for sheet/sheet and sheet/tube joints, with different composition, thickness, and coating

Astrid Damasco
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 21/02/1995 PT
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A motivação deste trabalho surgiu do fato da indústria automobilística usar em larga escala o processo de soldagem a ponto por resistência elétrica para a produção de juntas de chapa/chapa e de chapa/tubo com diferentes espessuras, revestimentos e composição química, sendo que ainda há uma série de dificuldades práticas associadas a algumas combinações chapa-tubo- revestimentos e, inclusive, com poucos dados disponíveis na bibliografia especializada. Foi feito, neste trabalho, a caracterização e análise do processo de soldagem a ponto por resistência elétrica para juntas de chapa sobre chapa e de chapa sobre tubo constituídas de aço baixo carbono, com diferentes composição química, espessura e revestimento. Para tanto, foram utilizadas chapas de aço ASTM 1005, de 0,95 mm de espessura, zincadas e tubos de aço ASTM 1023, de seção quadrada 30X30 mm2, com espessuras de 1,5 mm, 2,0 mm e 3,0 mm, todos fosfatizados. Com esses materiais foram obtidas juntas de chapa/chapa e chapa/tubo com diferentes combinações de espessuras ( 0,95/1,5 mm; 0,95/2,0 mm e 0,95/3,0 mm) e revestimentos (zinco/fosfato; zinco/zinco e decapados). As juntas de interesse foram submetidas ao processo de soldagem a ponto por resistência...

Recobrimento gastrorresistente de pellets de diclofenaco de sódio em leito fluidizado tipo Wurster; Aqueous enteric coating of diclofenac sodium in a fluiidized bed coater column with a Wuster insert

Roberta Albanez
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/02/2012 PT
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Os pellets apresentam muitas vantagens biofarmacêuticas e são ideais para aplicação de recobrimento. Quando o recobrimento é funcional, um dos principais objetivos é formação de uma barreira que modifique o perfil de liberação da droga (liberação controlada ou gastrorresistente). Neste trabalho pellets de diclofenaco de sódio foram produzidos por extrusão/esferonização e, em seguida, foram recobertos em leito fluidizado tipo Wurster. Esse tipo de leito é um dos sistemas mais adequados para o recobrimento de partículas. Dentre suas vantagens destaca-se a não formação de zonas mortas. Este trabalho teve como objetivo estudar o recobrimento dos pellets produzidos com duas suspensões poliméricas aquosas comerciais entéricas, Advantia® Performance e Acryl-Eze® MP. O estudo do processo de recobrimento foi realizado por meio de um planejamento experimental 2³. As variáveis estudadas foram: temperatura do ar de entrada, vazão da suspensão e polímero de recobrimento. As variáveis de resposta foram: eficiência do processo, resultados acima de 78,2%, e fração de aglomerados, resultados inferiores a 8%. O efeito do tipo de polímero de recobrimento foi o que mais influenciou as variáveis de resposta, sendo que o Advantia® Performance resultou numa maior eficiência e uma maior fração de aglomerados. Determinou-se também o ganho de massa mínimo para atingir a gastrorresistência - Acryl-Eze® MP: 9...

Efeitos da molhabilidade e adesão em sistemas sólido-suspensão e filme-suspensão no desempenho do recobrimento em leito de jorro; Effects of wettability and adhesion of solid-suspension and film-suspension systems on spouted bed coating performance

Matheus Boeira Braga
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/02/2012 PT
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O recobrimento de partículas é uma operação presente em vários setores industriais e tem como objetivo modificar as propriedades de superfície influenciando diretamente na qualidade, estabilidade e proteção do produto final. O principal enfoque deste trabalho foi aprimorar o estudo de recobrimento em termos de tensão superficial do sólido e características de molhabilidade e adesão antes e após a formação da primeira camada de recobrimento sobre a partícula. Ensaios de recobrimento em leito de jorro foram conduzidos, empregando-se: cinco suspensões poliméricas aquosas que se diferenciaram quanto às propriedades físicas (concentração de sólidos, tensão superficial e reologia) e, como inertes, partículas arredondadas de vidro e ABS® (copolímero acrilonitrila butadieno estireno) com diferentes energias superficiais, gerando sistemas com distintas características de molhabilidade e adesão. Para caracterização do sistema filme-suspensão, duas metodologias (A e B) foram testadas recobrindo lâminas de vidro e de ABS® com uma fina camada de suspensão polimérica, e para os conjuntos sólido/película que produziram uma superfície lisa e homogênea, estes foram avaliados quanto ao ângulo de contato, assim como para o sistema sólido-suspensão. A eficiência do processo e a cinética de crescimento das partículas...

Use of galactomannan edible coating application and storage temperature for prolonging shelf-life of “regional” cheese

Cerqueira, M. A.; Gallagher, Maria Jose Sousa; Macedo, Isabel; Rodríguez Aguilera, Rocío; Souza, B. W. S.; Teixeira, J. A.; Vicente, A. A.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /03/2010 ENG
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The objectives of this work were to determine the influence of the application of two different coatings (galactomannan and chitosan) and of storage temperature on the gas exchange rate of “Regional” cheese; subsequently, the coating that showed the greatest influence on the cheese gas exchange and simultaneously decreased the O2 consumption (RO2) and the CO2 production (RCO2) rates was applied on cheese, being the shelf-life parameters monitorized through the performance of chemical and microbiological analyses. Both coatings caused a reduction of RO2 and RCO2 of the cheese (between 0.19- and 1.30-fold for RO2 and between 0.19- and 1.50-fold for RCO2, depending on the temperatures). The cheese coated with the galactomannan coating was the one with the lower values of RO2 (between 0.195 and 0.635 mL kg−1 h−1) and RCO2 (between 0.125 and 0.900 mL kg−1 h−1). Temperature was also found to have an important effect on RO2 and RCO2, its influence being well described by an Arrhenius equation with coefficients of determination, R2, of 0.85 and above. The chemical and microbiological analyses showed that the application of the coating in cheese samples can be used to decrease the water loss and the colour changes during the storage time. The presence of the coating decreased the moisture loss of the cheese in 2.5% and 1.9%...

Effect of the application of a galactomannan coating incorporating nisin on the growth of Listeria monocytogenes on Ricotta cheese

Martins, Joana; Cerqueira, M. A.; Souza, B. W. S.; Avides, Maria do Carmo; Vicente, A. A.
Fonte: Universidade do Minho. Departamento de Engenharia Biologica Publicador: Universidade do Minho. Departamento de Engenharia Biologica
Tipo: Conferência ou Objeto de Conferência
Publicado em 28/11/2009 ENG
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Antimicrobial packaging, besides protecting the product from the external environment, inhibits or delays microorganism growth in foods and meets the actual demand of consumers for healthier foods, containing less additives (Lopez‐Rubio, Gavara, & Lagaron, 2006). Cheese is a ready‐to‐eat type of food that has been associated with foodborne listeriosis. Listeria monocytogenes is an important ubiquitous foodborne pathogen which may contaminate foods at pre‐ and post‐harvest stages of production. To overcome this problem bacteriocins could be entrapped in a suitable edible coating applied to food. Nisin is an antimicrobial peptide produced by Lactococcus lactis subsp. lactis. and research studies have revealed its ability to inhibit the growth of some pathogenic bacteria (Sobrino‐López, & Martín‐Belloso, 2008). The aim of this study was to evaluate the antimicrobial activity of coatings of galactomannans from Gleditsia triacanthos incorporating nisin against L. monocytogenes during storage of Ricotta cheese at 4 °C. Three different treatments were tested: a control with no coating; a sample with coating containing no nisin and a coating with 50 IU.g‐1 of nisin. Samples of cheese (20 g) were immersed in 0.5 % w/v galactomannan solution containing glycerol (as plasticizer) (1.5 % v/v). To test the effectiveness of the treatments Ricotta cheese samples were surface‐inoculated with a solution containing approximately 1×106 CFU.ml‐1 of L. monocytogenes. Microbiological and physicalchemical parameters (color change...

The influence of the moisture content of microcrystalline cellulose on the coating process in a fluidized bed

Silva,O. S.; Rocha,S. C. S.; Marsal,S. C.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2004 EN
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The objective of this work was to study the coating of microcrystalline cellulose with a polymeric suspension in a fluidized bed. The coating operation was carried out using a fluidized bed with top spraying by a double-fluid nozzle. The fluidized bed consists of a cylindrical column made of plexiglass with a height of 0.6 m and an inner diameter of 0.14 m. The polymeric coating suspension was formulated using Eudragit® as the basic component. As the quality of the coating product is greatly affected by the spraying characteristics, the influence of the flow rate of the coating suspension and the moisture content of the particles on the agglomeration index and efficiency of the process of coating microcrystalline cellulose was analyzed.

Microstructure and tribological properties of cobalt-based Stellite 6 alloy coating by electro-spark deposition

Jing,QiFeng; Tan,YeFa
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2013 EN
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The cobalt-based Stellite 6 coating with a thickness of 0.5 mm was deposited onto 45 carbon steel by electro-spark deposition technology. Microstructure, chemical composition, phase composition, microhardness distribution and wear resistance of the coating were researched by a series of experiments. The results indicate that, the coating with refined and compact microstructure is mainly composed of Co, Cr7C3, Co6W6C and CrCo. The coating makes metallurgical bonding interface with the substrate. Microhardness of the coating is improved significantly with an average value of 827.9 HV0.5, which is about 3.6 times that of the substrate. Under the same experimental condition, mass loss of the substrate is about 4.2-4.5 times that of the coating, so the coating shows excellent wear resistance. Main wear mechanism of the coating is abrasive wear at low speed or low load stage, and fatigue wear at high speed or heavy load condition.

Development and evaluation of a hot-melt coating technique for enteric coating

Patil,Arun Trambak; Khobragade,Deepak Shamrao; Chafle,Sandip Annaji; Ujjainkar,Amol Prasadrao; Umathe,Sudhir Niranjanrao; Lakhotia,Champalal Laxminarayan
Fonte: Universidade de São Paulo, Faculdade de Ciências Farmacêuticas Publicador: Universidade de São Paulo, Faculdade de Ciências Farmacêuticas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 EN
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Conventional enteric coating requires the use of organic based polymers which are equally hazardous to the environment and operating personnel. Hot-melt coating avoids the use of solvents and is a safer and time-saving process. The present study was designed to assess the efficacy of hot-melt coating (HMC) as an enteric coating technique. Pellets prepared by extrusion spheronization were selected as the core formulation for a model of the gastric irritant drug diclofenac sodium (DFS) because of their innate advantages over single-unit formulations. Stearic acid (SA) and palmitic acid (PA) were evaluated as enteric hot-melt coating materials. HMC was carried out in a specially modified coating pan by applying SA and PA in molten state onto preheated pellets to achieve a coating level of 5-15 %w/w. Hot-melt coated pellets were evaluated for disintegration pH and in vitro dissolution in the pH range 1.2 to 6.8, along with basic micromeritics. SEM of coated pellets showed a uniform and smooth coating. These results indicated that HMC of both SA and PA exhibited very good enteric coating ability. The coated pellets showed negligible drug release in acidic pH. As the pellets were subsequently transferred to a higher pH level, a gradual increase in release of the drug from the pellets was observed with increasing pH of the dissolution media. The release was dependent upon coating extent...

Revestimento ativo de amido na conservação pós-colheita de pera Williams minimamente processada; Starch-based edible coating on extending shelf life of fresh-cut pear

Fonte: Universidade Federal de Santa Maria Publicador: Universidade Federal de Santa Maria
Tipo: Artigo de Revista Científica
PT_BR
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Pear is one of the most consumed temperate fruits in Brazil; however their conservation is limited due to browning when it suffers injuries or physical treatments. The edibles coating interact with the food positively extending its shelf life. This research aimed to evaluate the action of starch edible coating incorporated with calcium lactate and L-cysteine on enzymatic browning inhibition, on psychrotrophs and enterobacteriaceae growing reduction and on firmness maintenance. The sliced pears were coated with starch edible coating incorporated with L-cysteine and calcium lactate, except control, without coating (C). The treatment were: only coating (T1); 2,0% calcium lactate and 1,0% L-cysteine (T2); 2,0% calcium lactate and 1,5% L-cysteine (T3). The samples were taken at 0, 2, 4 and 6 days. Pears were keeped under refrigeration (7°C±2°C). Pears submitted to treatments T2 and T3 show significantly more firms (P<0,05) compared to treatments C and T1. Cysteine action over enzymatic browning inhibition was observed in treatments T2 and T3 which do not differed significantly each other (P0,05) to ΔE values however these were significantly lower than control (C). At time 6, decimal reduction on psychrotrophs counting reached 3,03 and 2...

Tatamento e recobrimento de sementes de soja com pol??meros l??quido e em p??; Soybean seed treatment and coating with liquid and powdered polymer

Avelar, Suemar Alexandre Gon??alves
Fonte: Universidade Federal de Pelotas; Agronomia; Programa de P??s-gradua????o em Ci??ncia e Tecnologia de Sementes; UFPel; BR Publicador: Universidade Federal de Pelotas; Agronomia; Programa de P??s-gradua????o em Ci??ncia e Tecnologia de Sementes; UFPel; BR
Tipo: Dissertação Formato: application/pdf
POR
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Seed coating is a strong technology for soybean seeds, bringing great advantages to the farmers, allowing the application of polymers in an appropriate and necessary way to cover the seed. The objective of this research was to evaluate the efficiency of seed coating and the quality of soybean seeds treated with fungicide, insecticide, micronutrients and polymers, during six months of storage. Soybean seeds cultivar CD 209 were submitted to the following treatments: control, fungicide Fludioxonil + Metalaxyl - M (Maxim XL?? - 100 mL.100 kg-1 seeds), insecticide Thiametoxan (Cruiser 350 FS?? - 200 mL.100 kg-1 seeds), micronutrient ComoFix?? (165 mL.100 kg-1 seeds - 24,75 mL Mo and 2,475 mL Co) and the mixture fungicide + insecticide + micronutrient. The same treatments were repeated using the liquid polymer Sepiret 9241 B Green (400 mL.100 kg-1 seed) and also powder polymer Sepiret Flo Branco (0,5 kg.100 kg-1 seeds) + colorant Corasem blue (50 mL.100 kg-1 seeds). Coating efficiency and physical and physiological seed quality in laboratory and seedling performance in the field were evaluated. It was concluded that: the use of polymer in seed coating presents seeds with good appearance, coloration, distribution and adherence of the products to the seed surface; uniformity of product distribution during seed treatment varies with the interaction between product and type of polymer used. Coating with liquid polymer is more efficient in soybean seeds. The use of polymers alters the hectolitre volumetric weight not affecting the physiologic quality. The powder polymer presents adverse latent effects after the storage of the seeds. The polymer should not be used separately in the treatment of seeds.; O recobrimento de sementes ?? uma tecnologia que v??m se firmando cada vez mais...

Focused ion beam assisted analysis of the oxidation of a NiAl coating on pure Ni

Reid, M; Pomeroy, Michael J.; Vokal, V; Tanner, D.A
Fonte: Maney Publishing Publicador: Maney Publishing
Tipo: info:eu-repo/semantics/article; all_ul_research; ul_published_reviewed
ENG
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peer-reviewed; Discs of (pure nickel 15 mm diameter and 4 nun thickness) have been polished to a 1 mu m finish, aluminised using a standard pack CVD process to give a beta-NiAl coating and then the surface of this coating polished to a 1 mu m finish again. Samples have then been isothermally oxidised in a muffle furnace for 1, 2, 4, 8, 16, 32, 64, 128, 256, 512 and 1024 hours at 950 degrees C, and subjected to surface and cross-sectional microscopy and analysis. Scales were also cross-sectioned and imaged using Focused Ion Beam Milling. The oxidation rate was determined to be 2.6 x 10(-13) g(2) cm(-4) s(-1) and for times less than 512 hours the predominant alumina phase was theta alumina. Al depletion effects were observed due to both oxidation and interdiffusion between the Ni substrate and the NiAl coating. Using these effects, it has been shown that tensile strains of up to 9% can arise and these strains readily explain the formation of intrefacial elliptical pores observed by FIB cross sectioning. FIB sectioning also indicated that different coating grains exhibit different oxide-coating interfaces which arise due to different grain orientations. The faceting of the coating-oxide interface and the development of cuboidal faceted coating structures beneath spalled oxide is thought to be due to substructure development (sub-grain development or recrystallisation) arising from the plastic strains generated by Al depletion effects.; Accepted; peer-reviewed

Impact of Processing Conditions on Inter-tablet Coating Thickness Variations Measured by Terahertz In-Line Sensing

Lin, Hungyen; May, Robert K.; Evans, Michael J.; Zhong, Shuncong; Gladden, Lynn F.; Shen, Yaochun; Zeitler, J. Axel
Fonte: Wiley Publicador: Wiley
Tipo: Article; published version
EN
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This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/jps.24503; A novel in-line technique utilising pulsed terahertz radiation for direct measurement of the film coating thickness of individual tablets during the coating process was previously developed and demonstrated on a production scale coater. Here we use this technique to monitor the evolution of tablet film coating thickness and its inter-tablet variability during the coating process under a number of different process conditions that have been purposefully induced in the production scale coating process. The changes that were introduced to the coating process include removing the baffles from the coater, adding uncoated tablets to the running process, halting the drum, blockage of spray guns and changes to the spray rate. The terahertz sensor was able to pick up the resulting changes in average coating thickness in the coating drum and we report the impact of these process changes on the resulting coating quality.; This work was conducted with financial support from the UK Technology Strategy Board (AB293H). H.L. And J.A.Z. would like to acknowledge the Engineering and Physical Sciences Research Council (EP/L019922/1) and the Newton Trust Cambridge for research funding. J.A.Z. would like to thank Gonville & Caius College...

Quantifying pharmaceutical film coating with optical coherence tomography and terahertz pulsed imaging: an evaluation

Lin, Hungyen; Dong, Yue; Shen, Yaochun; Zeitler, J. Axel
Fonte: Wiley Publicador: Wiley
Tipo: Article; published version
EN
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This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/jps.24535; Spectral domain optical coherence tomography (SD-OCT) has recently attracted a lot of interest in the pharmaceutical industry as a fast and non-destructive modality for quantification of thin film coatings that cannot easily be resolved with other techniques. Due to the relative infancy of this technique, much of the research to date has focused on developing the in-line measurement technique for assessing film coating thickness. To better assess OCT for pharmaceutical coating quantification, this paper evaluates tablets with a range of film coating thickness measured using OCT and terahertz pulsed imaging (TPI) in an off-line setting. In order to facilitate automated coating quantification for film coating thickness in the range of 30 to 200 ?m, an algorithm that uses wavelet denoising and a tailored peak finding method is proposed to analysis each of the acquired A-scan. Results obtained from running the algorithm reveal an increasing disparity between the TPI and OCT measured intra-tablet variability when film coating thickness exceeds 100 ?m. The finding further confirms that OCT is a suitable modality for characterising pharmaceutical dosage forms with thin film coatings while TPI is well suited for thick coatings.; The authors would like to acknowledge the financial support from UK EPSRC Research Grant EP/L019787/1 and EP/L019922/1.

Comparisons of intra-tablet coating variability using DEM simulations, asymptotic limit models, and experiments

Freireich, Ben; Kumar, Rahul; Ketterhagen, William; Su, Ke; Wassgren, Carl; Zeitler, J. Axel
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; published version
EN
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This is the final version. It first appeared at http://www.sciencedirect.com/science/article/pii/S0009250915001852.; Discrete element method (DEM) computer simulations are used to investigate intra-tablet coating thickness variability. Two new post-processing algorithms are presented. The first algorithm uses an image-based method to track the exposure to a simulated spray of small area panels on each tablet?s surface so that the distribution of spray exposure times over the tablet?s surface can be determined directly from DEM data. The second algorithm predicts the asymptotic limit of intra-tablet coating uniformity. This second algorithm includes the influence of tablet orientation and shadowing when considering exposure to the spray, averaged over many tablets. The DEM simulations produce the first direct evidence that non-spherical tablets approach asymptotic intra-tablet coating variability values. The asymptotic limits are predicted well using the new asymptotic prediction model. In general, tablet caps have thicker coatings than tablet bands. Moreover, tablets that have a more elongated shape tend to have less coating on the smaller radius of curvature portions of the bands. Of particular importance in this new asymptotic modeling approach is the inclusion of shadowing effects. When shadowing is not included and only tablet orientation is considered...

Development and evaluation of a hot-melt coating technique for enteric coating

Patil, Arun Trambak; Khobragade, Deepak Shamrao; Chafle, Sandip Annaji; Ujjainkar, Amol Prasadrao; Umathe, Sudhir Niranjanrao; Lakhotia, Champalal Laxminarayan
Fonte: Universidade de São Paulo. Faculdade de Ciências Farmacêuticas Publicador: Universidade de São Paulo. Faculdade de Ciências Farmacêuticas
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 01/03/2012 ENG
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Conventional enteric coating requires the use of organic based polymers which are equally hazardous to the environment and operating personnel. Hot-melt coating avoids the use of solvents and is a safer and time-saving process. The present study was designed to assess the efficacy of hot-melt coating (HMC) as an enteric coating technique. Pellets prepared by extrusion spheronization were selected as the core formulation for a model of the gastric irritant drug diclofenac sodium (DFS) because of their innate advantages over single-unit formulations. Stearic acid (SA) and palmitic acid (PA) were evaluated as enteric hot-melt coating materials. HMC was carried out in a specially modified coating pan by applying SA and PA in molten state onto preheated pellets to achieve a coating level of 5-15 %w/w. Hot-melt coated pellets were evaluated for disintegration pH and in vitro dissolution in the pH range 1.2 to 6.8, along with basic micromeritics. SEM of coated pellets showed a uniform and smooth coating. These results indicated that HMC of both SA and PA exhibited very good enteric coating ability. The coated pellets showed negligible drug release in acidic pH. As the pellets were subsequently transferred to a higher pH level, a gradual increase in release of the drug from the pellets was observed with increasing pH of the dissolution media. The release was dependent upon coating extent...

To Investigate the absorption, dynamic contact angle and printability effects of synthetic zeolite pigments in an inkjet receptive coating

Jalindre, Swaraj
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
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Ink absorption performance in inkjet receptive coatings containing synthetic zeolite pigments was studied. Coating pigment pore and particle size distribution are the key parameters that influence in modifying media surface properties, thus affecting the rate of ink penetration and drying time (Schölkopf, et al. 2004). The primary objective of this study was: (1) to investigate the synthetic zeolite pigment effects on inkjet ink absorption, dynamic contact angle and printability, and (2) to evaluate these novel synthetic zeolite pigments in replacing the fumed silica pigments in conventional inkjet receptive coatings. In this research study, single pigment coating formulations (in equal P:B ratio) were prepared using microporous synthetic zeolite pigments (5A, Organophilic and 13X) and polyvinyl alcohol (PVOH) binder. The laboratory-coated samples were characterized for absorption, air permeance, roughness, drying time, wettability and print fidelity. Based on the rheological data, it was found that the synthetic zeolite formulated coatings depicted a Newtonian flow behavior at low shear; while the industry accepted fumed silica based coatings displayed a characteristically high pseudoplastic flow behavior. Our coated samples generated using microporous synthetic zeolite pigments produced low absorption...

Estimates for the pressure and thermal distortions of coating dies for use in design and simulation

Shetty, Sneha
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
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A coating die is used for distributing liquid in order to apply a uniform film on a solid surface. The fluid flowing through the die cavity can exert a pressure of up to 500,000 Pascal on the die body. This liquid pressure can distort the die and lead to a non-uniform slot opening, which in turn causes non-uniformity in the coating thickness. Distortion of the die can also occur during non-isothermal operation of the die; this is an undesired consequence of delivering liquids at a different temperature than the die itself. The distortions undergone by the die both due to liquid pressure and non-isothermal conditions should be within the manufacturing tolerances for the slot heights in order to maintain uniformity in the coating. The deformation exhibited by a coating die due to pressure loadings is modeled both two-dimensionally and three-dimensionally. A two-dimensional model has lower computational load and is preferred for die design. For the two-dimensional analysis of a coating die, the finite element method is used to determine the deflections due to pressure loadings with a focus on slot heights. A model of low computational load is also developed based on beam theory, and its results are compared with those of the two-dimensional finite element analyses predictions. The beam model is incorporated in a die design and simulation program in which flow and slot deformations are coupled. Two-dimensional finite element analyses due to non-isothermal conditions are also performed on the coating die to give an estimate of the die deflection due to temperature variations within the die. A three-dimensional coating die with varying inner cavity area is modeled and analyzed to check its predictions with those of the two-dimensional finite element analyses and beam theory results. In the literature reviewed...