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Charles Q. Yang - One of the best experts on this subject based on the ideXlab platform.

  • comparison of dmdheu and melamine formaldehyde as the binding Agents for a hydroxy functional organophosphorus flame Retarding Agent on cotton
    Journal of Fire Sciences, 2004
    Co-Authors: Charles Q. Yang
    Abstract:

    It is necessary to use a crosslinking Agent to bond a flameRetarding hydroxy-functional organophosphorus oligomer (FR) to cotton so that the flame resistance of the treated cotton fabric can be durable to multiple homelaundering. Both dimethyloldihydroxyethyleneurea (DMDHEU) and melamine– formaldehyde (M-F) have been used as the binding Agents between FR and cotton. The vertical flammability, limiting oxygen index (LOI) and phosphorus content after different numbers of laundering cycles as well as the wrinkle resistance and tensile strength of the cotton fabric treated with FR/DMDHEU and FR/M-F was investigated and compared in this research. We found that DMDHEU is more effective for crosslinking cotton cellulose and for crosslinking between FR and cotton than M-F. We also found that the bonding formed by DMDHEU between cotton and FR is more durable to multiple laundering cycles than that formed by M-F. M-F is a more effective nitrogen provider than DMDHEU to enhance the flame Retarding performance of the...

  • correlation between limiting oxygen index and phosphorus nitrogen content of cotton fabrics treated with a hydroxy functional organophosphorus flame Retarding Agent and dimethyloldihydroxyethyleneurea
    Journal of Applied Polymer Science, 2003
    Co-Authors: Weidong Wu, Charles Q. Yang
    Abstract:

    The combination of a hydroxyl-functional organophosphorus flame-Retarding Agent (FR) and dimethyloldihydroxyethyleneurea (DMDHEU) was used as a durable flame-retardant finish system for cotton fabrics. DMDHEU functions as a binder between FR and cotton cellulose, thus making this flame-Retarding system durable to home laundering. DMDHEU also provides nitrogen to this system, therefore enhances its performance. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles and other polymeric materials. In this research, we investigated the correlation between LOI and phosphorus/nitrogen content on the cotton fabric treated with that durable flame-retardant system. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy, whereas the nitrogen content was determined indirectly by measuring the carbonyl band intensity in the infrared spectra of the treated fabric. We developed a statistical model to predict LOI of the cotton fabric treated with FR and DMDHEU based on the phosphorus concentration and the intensity of carbonyl band of DMDHEU on cotton. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1885–1890, 2003

  • correlation between limiting oxygen index and phosphorus nitrogen content of cotton fabrics treated with a hydroxy functional organophosphorus flame Retarding Agent and dimethyloldihydroxyethyleneurea
    Journal of Applied Polymer Science, 2003
    Co-Authors: Weidong Wu, Charles Q. Yang
    Abstract:

    The combination of a hydroxyl-functional organophosphorus flame-Retarding Agent (FR) and dimethyloldihydroxyethyleneurea (DMDHEU) was used as a durable flame-retardant finish system for cotton fabrics. DMDHEU functions as a binder between FR and cotton cellulose, thus making this flame-Retarding system durable to home laundering. DMDHEU also provides nitrogen to this system, therefore enhances its performance. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles and other polymeric materials. In this research, we investigated the correlation between LOI and phosphorus/nitrogen content on the cotton fabric treated with that durable flame-retardant system. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy, whereas the nitrogen content was determined indirectly by measuring the carbonyl band intensity in the infrared spectra of the treated fabric. We developed a statistical model to predict LOI of the cotton fabric treated with FR and DMDHEU based on the phosphorus concentration and the intensity of carbonyl band of DMDHEU on cotton. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1885–1890, 2003

Nardi Ricart Anna - One of the best experts on this subject based on the ideXlab platform.

  • Desarrollo de un nuevo medicamento de liberación prolongada de Tolcapone
    'Edicions de la Universitat de Barcelona', 2017
    Co-Authors: Nardi Ricart Anna
    Abstract:

    [spa] El objetivo del presente estudio ha sido la investigación y desarrollo de un nuevo medicamento sólido de Tolcapone, en forma farmacéutica de comprimido de liberación prolongada y administración oral con una pauta posológica preferente de 1 administración cada 12 o 24 horas, diseñado específicamente para una nueva indicación terapéutica: el tratamiento de la polineuropatía amiloidea familiar. Este objetivo ha implicado la investigación de las características químicas, físicas y tecnológicas del principio activo vehiculizado, el diseño de una formulación robusta y adecuada, establecer la tecnología de fabricación óptima y el estudio del comportamiento cinético de liberación y disolución del fármaco partir de la forma farmacéutica, realizando ensayos “in vitro” e “in vivo” en modelo animal. La selección de los comprimidos matriciales como forma farmacéutica de liberación prolongada de elección ha sido motivada por las características físicoquímicas y tecnológicas del principio activo y por tratarse de formas farmacéuticas fácilmente industrializables. Se han llevado a cabo 3 líneas de investigación en paralelo en función del tipo de matriz utilizada y el comportamiento de la misma: matrices hidrófilas de hinchamiento ilimitado, matrices hidrófilas de hinchamiento limitado y matrices hidrófobas. Los comprimidos matriciales hidrófilos de hinchamiento ilimitado son los que han permitido obtener mejores resultados. La compresión directa se considera la tecnología de fabricación de elección por las ventajas que presenta. Tolcapone es apto para su compresión vía directa si se formula junto a los excipientes adecuados para compensar sus deficiencias. El excipiente seleccionado para la formación de la matriz polimérica ha sido la hidroxipropilmetilcelulosa, excipiente muy utilizado para la formulación de este tipo de comprimidos. Se ha decidido formular con celulosa microcristalina como diluyente ya que por sus características intrínsecas es capaz de compensar la cohesividad deficitaria que presenta el principio activo. Se añaden a la formulación un deslizante, sílice coloidal anhidra, y dos lubrificantes, estearato magnésico y talco. Se han realizado diferentes formulaciones con concentraciones de hidroxipropilmetilcelulosa comprendidas entre un 20 % y un 35%. Se ha confirmado el hecho de la dependencia existente entre la cantidad de Agente retardante en la formulación y la velocidad de liberación del fármaco a partir del comprimido matricial. A mayor cantidad de hidroxipropilmetilcelulosa en la formulación, más lenta es la liberación del fármaco, existiendo una relación que se ajusta a un modelo exponencial. Una disminución en el tamaño de partícula del principio activo ha dado lugar a una cinética de disolución del fármaco más lenta cuando el excipiente retardante se encuentra por debajo del 29% en la formulación. Para demostrarlo, se ha realizado un estudio estadístico cuyos resultados permiten afirmar que existen diferencias estadísticamente significativas entre las cinéticas de disolución realizadas con los comprimidos matriciales fabricados con principios activos de diferente tamaño de partícula , siendo más rápida la correspondiente a la formulación fabricada con tolcapone de tamaño de partícula mayor. A pesar de que el modelo animal escogido para el estudio (perro) resultó no ser el adecuado para ensayar este tipo de formulaciones de liberación prolongada debido a las diferencias considerables a nivel de tracto gastrointestinal (diferente tránsito, diferente pH gástrico, etc) existente entre perro y humano, se propone la formulación con una concentración de hidroxipropilmetilcelulosa del 29% como fórmula definitiva y apta para una administración cada 12 horas.[eng] The aim of this study was the research and development of a new solid formulation of Tolcapone, in a sustained release tablet dosage form for an oral administration with a preferred dosage regimen of 1 administration every 12 or 24 hours, designed specifically for a new indication therapy: treatment of Familial Amyloid Polyneuropathy. This goal has involved the investigation of the chemical, physical and technological characteristics of the active ingredient, the design of a robust and suitable formulation, establish an optimal manufacturing technology and study the kinetic behavior of liberation and dissolution of the pharmaceutical form, conducting trials "in vitro" and "in vivo" in animal model. The selection of matrix tablets and sustained-release dosage form of choice has been motivated by the physico-chemical and technological characteristics of the active substance and for being easily industrialized dosage forms. Three different lines have been developed in parallel depending on the type of matrix used and its behaviour: unlimited swelling hydrophilic matrices, limited swelling hydrophilic matrices and hydrophobic matrices. The best results have been obtained with unlimited swelling hydrophilic matrices. Direct compression is considered a manufacturing technology of choice for the advantages presented. Tolcapone is suitable for compression straightaway if it is formulated with suitable excipients to improve its limitations. The carrier selected for forming the polymer matrix has been hydroxypropylmethylcellulose, excipient widely used for the formulation of this type of tablets. It has been decided formulated with microcrystalline cellulose as a diluent because its intrinsic characteristics are able to compensate the deficit of cohesiveness of the active ingredient. A glidant, colloidal anhydrous silica, and two lubricants, magnesium stearate and talc, are added to the formulation. They were performed with different concentrations of hydroxypropylmethylcellulose formulations between 20% and 35%. It has confirmed the fact the dependence between the amount of Retarding Agent in the formulation and the release rate of the drug from the matrix tablet. A greater amount of hydroxypropylmethylcellulose in the formulation, the slower the drug release, having a relationship that conforms to an exponential model. A decrease in particle size of the active ingredient has resulted in dissolution kinetics slower drug when the retardant excipient is below 29% in the formulation. To prove it, it has done a statistical study whose findings are such that there are statistically significant differences between the kinetics of dissolution made to matrix tablets made with active ingredients of different particle size, being faster corresponding to the formulation made with tolcapone larger particle size. Although the animal model chosen for study (dog) resulted to be not suitable for testing such sustained release formulations due to the significant differences at the level of the gastrointestinal tract (different transit different gastric pH, etc) between dog and human, the formulation is proposed with a concentration of 29% hydroxypropylmethylcellulose as final and suitable formula for administration every 12 hours

  • Desarrollo de un nuevo medicamento de liberación prolongada de Tolcapone
    'Edicions de la Universitat de Barcelona', 2016
    Co-Authors: Nardi Ricart Anna
    Abstract:

    El objetivo del presente estudio ha sido la investigación y desarrollo de un nuevo medicamento sólido de Tolcapone, en forma farmacéutica de comprimido de liberación prolongada y administración oral con una pauta posológica preferente de 1 administración cada 12 o 24 horas, diseñado específicamente para una nueva indicación terapéutica: el tratamiento de la polineuropatía amiloidea familiar. Este objetivo ha implicado la investigación de las características químicas, físicas y tecnológicas del principio activo vehiculizado, el diseño de una formulación robusta y adecuada, establecer la tecnología de fabricación óptima y el estudio del comportamiento cinético de liberación y disolución del fármaco partir de la forma farmacéutica, realizando ensayos “in vitro” e “in vivo” en modelo animal. La selección de los comprimidos matriciales como forma farmacéutica de liberación prolongada de elección ha sido motivada por las características físicoquímicas y tecnológicas del principio activo y por tratarse de formas farmacéuticas fácilmente industrializables. Se han llevado a cabo 3 líneas de investigación en paralelo en función del tipo de matriz utilizada y el comportamiento de la misma: matrices hidrófilas de hinchamiento ilimitado, matrices hidrófilas de hinchamiento limitado y matrices hidrófobas. Los comprimidos matriciales hidrófilos de hinchamiento ilimitado son los que han permitido obtener mejores resultados. La compresión directa se considera la tecnología de fabricación de elección por las ventajas que presenta. Tolcapone es apto para su compresión vía directa si se formula junto a los excipientes adecuados para compensar sus deficiencias. El excipiente seleccionado para la formación de la matriz polimérica ha sido la hidroxipropilmetilcelulosa, excipiente muy utilizado para la formulación de este tipo de comprimidos. Se ha decidido formular con celulosa microcristalina como diluyente ya que por sus características intrínsecas es capaz de compensar la cohesividad deficitaria que presenta el principio activo. Se añaden a la formulación un deslizante, sílice coloidal anhidra, y dos lubrificantes, estearato magnésico y talco. Se han realizado diferentes formulaciones con concentraciones de hidroxipropilmetilcelulosa comprendidas entre un 20 % y un 35%. Se ha confirmado el hecho de la dependencia existente entre la cantidad de Agente retardante en la formulación y la velocidad de liberación del fármaco a partir del comprimido matricial. A mayor cantidad de hidroxipropilmetilcelulosa en la formulación, más lenta es la liberación del fármaco, existiendo una relación que se ajusta a un modelo exponencial. Una disminución en el tamaño de partícula del principio activo ha dado lugar a una cinética de disolución del fármaco más lenta cuando el excipiente retardante se encuentra por debajo del 29% en la formulación. Para demostrarlo, se ha realizado un estudio estadístico cuyos resultados permiten afirmar que existen diferencias estadísticamente significativas entre las cinéticas de disolución realizadas con los comprimidos matriciales fabricados con principios activos de diferente tamaño de partícula , siendo más rápida la correspondiente a la formulación fabricada con tolcapone de tamaño de partícula mayor. A pesar de que el modelo animal escogido para el estudio (perro) resultó no ser el adecuado para ensayar este tipo de formulaciones de liberación prolongada debido a las diferencias considerables a nivel de tracto gastrointestinal (diferente tránsito, diferente pH gástrico, etc) existente entre perro y humano, se propone la formulación con una concentración de hidroxipropilmetilcelulosa del 29% como fórmula definitiva y apta para una administración cada 12 horas.The aim of this study was the research and development of a new solid formulation of Tolcapone, in a sustained release tablet dosage form for an oral administration with a preferred dosage regimen of 1 administration every 12 or 24 hours, designed specifically for a new indication therapy: treatment of Familial Amyloid Polyneuropathy. This goal has involved the investigation of the chemical, physical and technological characteristics of the active ingredient, the design of a robust and suitable formulation, establish an optimal manufacturing technology and study the kinetic behavior of liberation and dissolution of the pharmaceutical form, conducting trials "in vitro" and "in vivo" in animal model. The selection of matrix tablets and sustained-release dosage form of choice has been motivated by the physico-chemical and technological characteristics of the active substance and for being easily industrialized dosage forms. Three different lines have been developed in parallel depending on the type of matrix used and its behaviour: unlimited swelling hydrophilic matrices, limited swelling hydrophilic matrices and hydrophobic matrices. The best results have been obtained with unlimited swelling hydrophilic matrices. Direct compression is considered a manufacturing technology of choice for the advantages presented. Tolcapone is suitable for compression straightaway if it is formulated with suitable excipients to improve its limitations. The carrier selected for forming the polymer matrix has been hydroxypropylmethylcellulose, excipient widely used for the formulation of this type of tablets. It has been decided formulated with microcrystalline cellulose as a diluent because its intrinsic characteristics are able to compensate the deficit of cohesiveness of the active ingredient. A glidant, colloidal anhydrous silica, and two lubricants, magnesium stearate and talc, are added to the formulation. They were performed with different concentrations of hydroxypropylmethylcellulose formulations between 20% and 35%. It has confirmed the fact the dependence between the amount of Retarding Agent in the formulation and the release rate of the drug from the matrix tablet. A greater amount of hydroxypropylmethylcellulose in the formulation, the slower the drug release, having a relationship that conforms to an exponential model. A decrease in particle size of the active ingredient has resulted in dissolution kinetics slower drug when the retardant excipient is below 29% in the formulation. To prove it, it has done a statistical study whose findings are such that there are statistically significant differences between the kinetics of dissolution made to matrix tablets made with active ingredients of different particle size, being faster corresponding to the formulation made with tolcapone larger particle size. Although the animal model chosen for study (dog) resulted to be not suitable for testing such sustained release formulations due to the significant differences at the level of the gastrointestinal tract (different transit different gastric pH, etc) between dog and human, the formulation is proposed with a concentration of 29% hydroxypropylmethylcellulose as final and suitable formula for administration every 12 hours

Sergin E. - One of the best experts on this subject based on the ideXlab platform.

  • Synergistic effect of phosphorus, nitrogen and silicon on flame retardancy properties of cotton fabric treated by sol-gel process
    'Emerald', 2016
    Co-Authors: Aksit A., Onar Nurhan, Kutlu B., Sergin E.
    Abstract:

    Purpose – The purpose of this paper is to develop the flame retardancy properties of cotton fabrics with treatment of phosphorus and nitrogen containing silane-based nanosol by sol-gel process. Design/methodology/approach – Nanosols containing tetraethoxysilane or (3-aminopropyl) triethoxysilane as precursors, (3-glycidyloxypropyl) trimethoxysilane as cross-linking Agent and guanidine phosphate monobasic as flame Retarding Agent were impregnated on cotton fabrics. Flame retardancy properties of the fabric samples were determined by limited flame spread test and limited oxygen index (LOI) test. In addition, microstructural and surface morphological properties of the fabric samples were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope. Findings – Depending on the limited flame spread test, the authors show that the coated fabric samples gain flame retardancy properties and the LOI value of the samples increased as to 45.7 per cent by the synergistic effect of phosphorus-nitrogen-silicon. Originality/value – There have some studies in flame retardancy behaviour of textiles. In this study, flame retardant cotton fabric with very low weight in grams was improved by sol-gel process. Moreover, ecological process was provided thanks to using halogen-free flame retardant. © 2016, © Emerald Group Publishing Limited

  • retardancy properties of cotton fabric treated by sol-gel process
    'Emerald', 2016
    Co-Authors: Aksit A., Kutlu B., Onar N, Sergin E.
    Abstract:

    Purpose - The purpose of this paper is to develop the flame retardancy properties of cotton fabrics with treatment of phosphorus and nitrogen containing silane-based nanosol by sol-gel process.Design/methodology/approach - Nanosols containing tetraethoxysilane or (3-aminopropyl) triethoxysilane as precursors, (3-glycidyloxypropyl) trimethoxysilane as cross-linking Agent and guanidine phosphate monobasic as flame Retarding Agent were impregnated on cotton fabrics. Flame retardancy properties of the fabric samples were determined by limited flame spread test and limited oxygen index (LOI) test. In addition, microstructural and surface morphological properties of the fabric samples were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and scanning electron microscope.Findings - Depending on the limited flame spread test, the authors show that the coated fabric samples gain flame retardancy properties and the LOI value of the samples increased as to 45.7 per cent by the synergistic effect of phosphorus-nitrogen-silicon.Originality/value - There have some studies in flame retardancy behaviour of textiles. In this study, flame retardant cotton fabric with very low weight in grams was improved by sol-gel process. Moreover, ecological process was provided thanks to using halogen-free flame retardant

He Yang - One of the best experts on this subject based on the ideXlab platform.

  • preparation of sustained release nitrendipine microspheres with eudragit rs and aerosil using quasi emulsion solvent diffusion method
    International Journal of Pharmaceutics, 2003
    Co-Authors: Mingshi Yang, Liang Wang, He Yang
    Abstract:

    Sustained-release nitrendipine microspheres were prepared in liquid system by quasi-emulsion solvent diffusion method, in which the Aerosil was employed as an inert dispersing carrier to improve the dissolution rate of nitrendipine, and Eudragit RS as a Retarding Agent to control the release rate. The resultant microspheres were evaluated for the recovery, bulk density, average particle size, drug loading, and incorporation efficiency. And the factors affecting the formation of microspheres and the drug-release rate were investigated. It was observed by a scanning electron microscope (SEM) that the microspheres were finely spherical and uniform, and no entire nitrendipine crystals were observed visually. The results of X-ray diffraction indicated that nitrendipine in microspheres was disordered, suggesting that nitrendipine was highly dispersed in microspheres. The drug loading of microspheres was enhanced with increasing the ratio of drug to excipients, and the incorporation efficiency was always >90%. The formation of microspheres was mainly influenced by the amount of bridging liquid and sodium dodecyl sulfate (SDS) in poor solvent. The dissolution profiles could be modulated with adjusting the amount of Retarding Agent and dispersing carrier formulated.

Weidong Wu - One of the best experts on this subject based on the ideXlab platform.

  • correlation between limiting oxygen index and phosphorus nitrogen content of cotton fabrics treated with a hydroxy functional organophosphorus flame Retarding Agent and dimethyloldihydroxyethyleneurea
    Journal of Applied Polymer Science, 2003
    Co-Authors: Weidong Wu, Charles Q. Yang
    Abstract:

    The combination of a hydroxyl-functional organophosphorus flame-Retarding Agent (FR) and dimethyloldihydroxyethyleneurea (DMDHEU) was used as a durable flame-retardant finish system for cotton fabrics. DMDHEU functions as a binder between FR and cotton cellulose, thus making this flame-Retarding system durable to home laundering. DMDHEU also provides nitrogen to this system, therefore enhances its performance. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles and other polymeric materials. In this research, we investigated the correlation between LOI and phosphorus/nitrogen content on the cotton fabric treated with that durable flame-retardant system. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy, whereas the nitrogen content was determined indirectly by measuring the carbonyl band intensity in the infrared spectra of the treated fabric. We developed a statistical model to predict LOI of the cotton fabric treated with FR and DMDHEU based on the phosphorus concentration and the intensity of carbonyl band of DMDHEU on cotton. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1885–1890, 2003

  • correlation between limiting oxygen index and phosphorus nitrogen content of cotton fabrics treated with a hydroxy functional organophosphorus flame Retarding Agent and dimethyloldihydroxyethyleneurea
    Journal of Applied Polymer Science, 2003
    Co-Authors: Weidong Wu, Charles Q. Yang
    Abstract:

    The combination of a hydroxyl-functional organophosphorus flame-Retarding Agent (FR) and dimethyloldihydroxyethyleneurea (DMDHEU) was used as a durable flame-retardant finish system for cotton fabrics. DMDHEU functions as a binder between FR and cotton cellulose, thus making this flame-Retarding system durable to home laundering. DMDHEU also provides nitrogen to this system, therefore enhances its performance. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles and other polymeric materials. In this research, we investigated the correlation between LOI and phosphorus/nitrogen content on the cotton fabric treated with that durable flame-retardant system. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy, whereas the nitrogen content was determined indirectly by measuring the carbonyl band intensity in the infrared spectra of the treated fabric. We developed a statistical model to predict LOI of the cotton fabric treated with FR and DMDHEU based on the phosphorus concentration and the intensity of carbonyl band of DMDHEU on cotton. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1885–1890, 2003