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Vanessa Petrilli Bavaresco - One of the best experts on this subject based on the ideXlab platform.

  • Recobrimento de substratos rigidos com hidrogel para utilização como superficie articular
    2017
    Co-Authors: Vanessa Petrilli Bavaresco
    Abstract:

    Resumo: Problemas relacionados com a restauração de juntas sinoviais danificadas são muito freqüentes e traumatizantes para um grande número de pessoas. Quando a junta está muito comprometida, o procedimento utilizado é sua substituição por uma articulação artificial que consiste em um conjunto no qual, normalmente, a parte óssea é substituída por um elemento metálico e a cartilagem articular por um elemento polimérico. O Polietileno de Ultra Alto Peso Molecular (pEUAPM) é o material polimérico que apresenta as melhores propriedades mecânicas para ser utilizado como componente em uma junta artificial, porém ainda é suscetível ao desgaste ocasionando a falência das próteses. Em outros casos, onde a lesão na cartilagem articular ainda se encontra em estágios iniciais e sua substituição por uma prótese total é inviável, busca-se apenas uma reparação local do defeito. Para tanto, pode-se utilizar um dispositivo composto por uma matriz porosa cerâmica ou metálica recoberta por um hidrogel para a reconstrução do defeito. Para minimizar o desgaste sofudo pelos componentes das juntas artificiais e desenvolver um dispositivo capaz de ser utilizado no reparo de defeitos osteocondrais, ou seja, defeitos que atingem a cartilagem articular e o osso subcondral, foi realizado o estudo do recobrimento de substratos sólidos porosos de PEUAPM e de uma mistura de Hidroxiapatita (HA) e _-Fosfato Tricálcico (_-TCP) com hidrogel polimérico a base de poli (metacrilato de 2-hidroxietila) (pREMA), material muito estudado para ser utilizado como reparador da cartilagem articular natural. O estudo envolve também a melhoria das propriedades mecânicas do hidrogel através da obtenção de blendas do tipo rede polimérica semi-interpenetrante (sIPN) de pREMA e acetatobutirato de celulose (CAB), pREMA e hidroxietil celulose (HEC) e pREMA e poli (metacrilato de etila) (pEM). Os materiais foram caracterizados por Microscopia Eletrônica de Varredura SEM), Análise Dinâmico Mecânico (DMA), Calorimetria Exploratória Diferencial (DSC) e Microscopia Óptica (OM). Além disso, foram realizados ensaios quanto ao desgaste dos materiais usados no recobrimento em um equipamento do tipo TRI-PIN-ON-DISK. O recobrimento de pREMA foi totalmente destruído ainda no início do ensaio de desgaste, enquanto que os recobrimentos formados pelas blendas de pHEMA-CAB e pHEMA-PEM resistiram a todo o tempo de ensaio, apresentando indícios de desgaste adesivo e abrasivo. Os resultados analisados mostraram a viabilidade em se melhorar as propriedades mecânicas do hidrogel através da obtenção de blendas do tipo sIPN utilizando como polímeros lineares de reforço o CAB e o PEMAbstract: Problems concerning the repair of damaged synovial joints are very ftequent and traumatic to a great number of people. In those cases where the damage extent is very high, the articular surface is usually an ultra high molecular weight Polyethylene (UHMWPE), even though it under goes severe wear when used as the cartilage counterpart in artificial joints, which sometimes leads to prostheses failure. On the other hand, when the damage of the articular cartilage does not require its complete replacement, only the repair of local defects is sought by using either a metallic or a porous ceramic substrate coated with a hydrogel. Aming at reducing the wear to which the artificial joints are submitted, and in order to develop a device capable ofbeing used in osteochondral defects, defects which affect both the articular cartilage and the subchondral bone, this work studied the coating of solid porous substrates of UHMWPE and ceramic composite between hydroxyapatite (HA) and (3-tricalcium phosphate «(3- TCP) with a poly(2-hydroxyethyl Methacrylate), polymer hydrogel (pREMA), a material widely investigated as a substitute for natural articular cartilage. This work also aimed at improving the mechanical properties of the hydrogel through the syntheses of sIPN-type blends between pREMA and cellulose acetate butyrate (CAB), pREMA and hydroxyethyl cellulose (HEC), and pHEMA and Polyethyl Methacrylate (pEM). The substrates were characterized by Scanning Electron Microscopy (SEM), Dynamical Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC) and Optical Microscopy (OM). Also, the coating materiaIs had their wear behavior evaluates in a TRI-PIN-ON-DISK equipment. The pHEMA coating was completely destroyed at the first wear cycles, white those coatings prepared with pHEMA - CAB and pREMA - PEM showed only slight signs of both abrasive and adhesive wear, after the complete experiment. The results thus obtained strongly suggest the possibility of improving the mechanical properties of the hydrogel by the syntheses of sIPN-type blends using linear reinforcing polymers CAB and PE

  • Recobrimento de substratos rigidos com hidrogel para utilização como superficie articular
    Universidade Estadual de Campinas. Faculdade de Engenharia Mecânica, 2000
    Co-Authors: Vanessa Petrilli Bavaresco
    Abstract:

    Problemas relacionados com a restauração de juntas sinoviais danificadas são muito freqüentes e traumatizantes para um grande número de pessoas. Quando a junta está muito comprometida, o procedimento utilizado é sua substituição por uma articulação artificial que consiste em um conjunto no qual, normalmente, a parte óssea é substituída por um elemento metálico e a cartilagem articular por um elemento polimérico. O Polietileno de Ultra Alto Peso Molecular (pEUAPM) é o material polimérico que apresenta as melhores propriedades mecânicas para ser utilizado como componente em uma junta artificial, porém ainda é suscetível ao desgaste ocasionando a falência das próteses. Em outros casos, onde a lesão na cartilagem articular ainda se encontra em estágios iniciais e sua substituição por uma prótese total é inviável, busca-se apenas uma reparação local do defeito. Para tanto, pode-se utilizar um dispositivo composto por uma matriz porosa cerâmica ou metálica recoberta por um hidrogel para a reconstrução do defeito. Para minimizar o desgaste sofudo pelos componentes das juntas artificiais e desenvolver um dispositivo capaz de ser utilizado no reparo de defeitos osteocondrais, ou seja, defeitos que atingem a cartilagem articular e o osso subcondral, foi realizado o estudo do recobrimento de substratos sólidos porosos de PEUAPM e de uma mistura de Hidroxiapatita (HA) e _-Fosfato Tricálcico (_-TCP) com hidrogel polimérico a base de poli (metacrilato de 2-hidroxietila) (pREMA), material muito estudado para ser utilizado como reparador da cartilagem articular natural. O estudo envolve também a melhoria das propriedades mecânicas do hidrogel através da obtenção de blendas do tipo rede polimérica semi-interpenetrante (sIPN) de pREMA e acetatobutirato de celulose (CAB), pREMA e hidroxietil celulose (HEC) e pREMA e poli (metacrilato de etila) (pEM). Os materiais foram caracterizados por Microscopia Eletrônica de Varredura SEM), Análise Dinâmico Mecânico (DMA), Calorimetria Exploratória Diferencial (DSC) e Microscopia Óptica (OM). Além disso, foram realizados ensaios quanto ao desgaste dos materiais usados no recobrimento em um equipamento do tipo TRI-PIN-ON-DISK. O recobrimento de pREMA foi totalmente destruído ainda no início do ensaio de desgaste, enquanto que os recobrimentos formados pelas blendas de pHEMA-CAB e pHEMA-PEM resistiram a todo o tempo de ensaio, apresentando indícios de desgaste adesivo e abrasivo. Os resultados analisados mostraram a viabilidade em se melhorar as propriedades mecânicas do hidrogel através da obtenção de blendas do tipo sIPN utilizando como polímeros lineares de reforço o CAB e o PEMProblems concerning the repair of damaged synovial joints are very ftequent and traumatic to a great number of people. In those cases where the damage extent is very high, the articular surface is usually an ultra high molecular weight Polyethylene (UHMWPE), even though it under goes severe wear when used as the cartilage counterpart in artificial joints, which sometimes leads to prostheses failure. On the other hand, when the damage of the articular cartilage does not require its complete replacement, only the repair of local defects is sought by using either a metallic or a porous ceramic substrate coated with a hydrogel. Aming at reducing the wear to which the artificial joints are submitted, and in order to develop a device capable ofbeing used in osteochondral defects, defects which affect both the articular cartilage and the subchondral bone, this work studied the coating of solid porous substrates of UHMWPE and ceramic composite between hydroxyapatite (HA) and (3-tricalcium phosphate «(3- TCP) with a poly(2-hydroxyethyl Methacrylate), polymer hydrogel (pREMA), a material widely investigated as a substitute for natural articular cartilage. This work also aimed at improving the mechanical properties of the hydrogel through the syntheses of sIPN-type blends between pREMA and cellulose acetate butyrate (CAB), pREMA and hydroxyethyl cellulose (HEC), and pHEMA and Polyethyl Methacrylate (pEM). The substrates were characterized by Scanning Electron Microscopy (SEM), Dynamical Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC) and Optical Microscopy (OM). Also, the coating materiaIs had their wear behavior evaluates in a TRI-PIN-ON-DISK equipment. The pHEMA coating was completely destroyed at the first wear cycles, white those coatings prepared with pHEMA - CAB and pREMA - PEM showed only slight signs of both abrasive and adhesive wear, after the complete experiment. The results thus obtained strongly suggest the possibility of improving the mechanical properties of the hydrogel by the syntheses of sIPN-type blends using linear reinforcing polymers CAB and PE

Rajender Prasad - One of the best experts on this subject based on the ideXlab platform.

  • Development of polymeric seed coats for seed quality enhancement of soybean
    2007
    Co-Authors: K Nsar, M B Arun, Suresh Walla, Rajender Prasad, Balraj S Parr
    Abstract:

    An experiment was conducted during 2004-05 to study the seed quality enhancement of soybean (Glycine max L. Merr.) using polymeric/clay seed coats. Twelve polymers-based and 1 clay-based seed coats were prepared and compared with the commercial formulation of Thiram 75 DS for seed quality enhancement of soybean seed under storage. The carriers employed included acacia, tragacanth, rosin, ethyl cellulose, hydroxy ethyl cellulose, Polyethyl Methacrylate, methyl cellulose, Polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone, and Agrimer VA 6 and the clay bentonite. The polymer-coated seeds in general deteriorated at a slower rate compared with the control and revealed high germination percentage over the control. Apparently the coats acted as barriers to the moisture and checked the deterioration of seed. These also prevented the proliferation of storage fungi over an elevated period. Among all the polymers, polyethy1 Methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were found to be significantly superior (P = 0.01) in maintaining the soybean seed quality during storage. On perusal of correlation matrix (germination, vigour and moisture), it was observed that the moisture content of seed revealed significant negative correlation with seed germination (0.8776), seed vigour (0.7240). These products were useful in improving the storability of the seed by checking the fungal infestation and enhancing the overall seed quality during storage.

  • Development of polymeric seed coats for seed quality enhancement of soybean Glycine max
    Indian Journal of Agricultural Sciences, 2007
    Co-Authors: Jitender Kumar, Keyath Nisar, M. B. Arun Kumar, Suresh Walia, Najam A. Shakil, Rajender Prasad
    Abstract:

    An experiment was conducted during 2004-05 to study the seed quality enhancement of soybean (Glycine max L. Merr.) using polymeric/clay seed coats. Twelve polymers-based and 1 clay-based seed coats were prepared and compared with the commercial formulation of Thiram 75 DS for seed quality enhancement of soybean seed under storage. The carriers employed included acacia, tragacanth, rosin, ethyl cellulose, hydroxy ethyl cellulose, Polyethyl Methacrylate, methyl cellulose, Polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone, and Agrimer VA 6 and the clay bentonite. The polymer-coated seeds in general deteriorated at a slower rate compared with the control and revealed high germination percentage over the control. Apparently the coats acted as barriers to the moisture and checked the deterioration of seed. These also prevented the proliferation of storage fungi over an elevated period. Among all the polymers, polyethy1 Methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were found to be significantly superior (P = 0.01) in maintaining the soybean seed quality during storage. On perusal of correlation matrix (germination, vigour and moisture), it was observed that the moisture content of seed revealed significant negative correlation with seed germination (0.8776), seed vigour (0.7240). These products were useful in improving the storability of the seed by checking the fungal infestation and enhancing the overall seed quality during storage

Vanessa Petrilli - One of the best experts on this subject based on the ideXlab platform.

  • Recobrimento de substratos rigidos com hidrogel para utilização como superficie articular
    [s.n.], 2018
    Co-Authors: Vanessa Petrilli
    Abstract:

    Orientadores: Cecilia Amelia de Carvalho Zavaglia, Sonia Maria MalmongeDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia MecanicaResumo: Problemas relacionados com a restauração de juntas sinoviais danificadas são muito freqüentes e traumatizantes para um grande número de pessoas. Quando a junta está muito comprometida, o procedimento utilizado é sua substituição por uma articulação artificial que consiste em um conjunto no qual, normalmente, a parte óssea é substituída por um elemento metálico e a cartilagem articular por um elemento polimérico. O Polietileno de Ultra Alto Peso Molecular (pEUAPM) é o material polimérico que apresenta as melhores propriedades mecânicas para ser utilizado como componente em uma junta artificial, porém ainda é suscetível ao desgaste ocasionando a falência das próteses. Em outros casos, onde a lesão na cartilagem articular ainda se encontra em estágios iniciais e sua substituição por uma prótese total é inviável, busca-se apenas uma reparação local do defeito. Para tanto, pode-se utilizar um dispositivo composto por uma matriz porosa cerâmica ou metálica recoberta por um hidrogel para a reconstrução do defeito. Para minimizar o desgaste sofudo pelos componentes das juntas artificiais e desenvolver um dispositivo capaz de ser utilizado no reparo de defeitos osteocondrais, ou seja, defeitos que atingem a cartilagem articular e o osso subcondral, foi realizado o estudo do recobrimento de substratos sólidos porosos de PEUAPM e de uma mistura de Hidroxiapatita (HA) e _-Fosfato Tricálcico (_-TCP) com hidrogel polimérico a base de poli (metacrilato de 2-hidroxietila) (pREMA), material muito estudado para ser utilizado como reparador da cartilagem articular natural. O estudo envolve também a melhoria das propriedades mecânicas do hidrogel através da obtenção de blendas do tipo rede polimérica semi-interpenetrante (sIPN) de pREMA e acetatobutirato de celulose (CAB), pREMA e hidroxietil celulose (HEC) e pREMA e poli (metacrilato de etila) (pEM). Os materiais foram caracterizados por Microscopia Eletrônica de Varredura SEM), Análise Dinâmico Mecânico (DMA), Calorimetria Exploratória Diferencial (DSC) e Microscopia Óptica (OM). Além disso, foram realizados ensaios quanto ao desgaste dos materiais usados no recobrimento em um equipamento do tipo TRI-PIN-ON-DISK. O recobrimento de pREMA foi totalmente destruído ainda no início do ensaio de desgaste, enquanto que os recobrimentos formados pelas blendas de pHEMA-CAB e pHEMA-PEM resistiram a todo o tempo de ensaio, apresentando indícios de desgaste adesivo e abrasivo. Os resultados analisados mostraram a viabilidade em se melhorar as propriedades mecânicas do hidrogel através da obtenção de blendas do tipo sIPN utilizando como polímeros lineares de reforço o CAB e o PEMAbstract: Problems concerning the repair of damaged synovial joints are very ftequent and traumatic to a great number of people. In those cases where the damage extent is very high, the articular surface is usually an ultra high molecular weight Polyethylene (UHMWPE), even though it under goes severe wear when used as the cartilage counterpart in artificial joints, which sometimes leads to prostheses failure. On the other hand, when the damage of the articular cartilage does not require its complete replacement, only the repair of local defects is sought by using either a metallic or a porous ceramic substrate coated with a hydrogel. Aming at reducing the wear to which the artificial joints are submitted, and in order to develop a device capable ofbeing used in osteochondral defects, defects which affect both the articular cartilage and the subchondral bone, this work studied the coating of solid porous substrates of UHMWPE and ceramic composite between hydroxyapatite (HA) and (3-tricalcium phosphate «(3- TCP) with a poly(2-hydroxyethyl Methacrylate), polymer hydrogel (pREMA), a material widely investigated as a substitute for natural articular cartilage. This work also aimed at improving the mechanical properties of the hydrogel through the syntheses of sIPN-type blends between pREMA and cellulose acetate butyrate (CAB), pREMA and hydroxyethyl cellulose (HEC), and pHEMA and Polyethyl Methacrylate (pEM). The substrates were characterized by Scanning Electron Microscopy (SEM), Dynamical Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC) and Optical Microscopy (OM). Also, the coating materiaIs had their wear behavior evaluates in a TRI-PIN-ON-DISK equipment. The pHEMA coating was completely destroyed at the first wear cycles, white those coatings prepared with pHEMA - CAB and pREMA - PEM showed only slight signs of both abrasive and adhesive wear, after the complete experiment. The results thus obtained strongly suggest the possibility of improving the mechanical properties of the hydrogel by the syntheses of sIPN-type blends using linear reinforcing polymers CAB and PEMMestradoMateriais e Processos de FabricaçãoMestre em Engenharia Mecânic

Vilas D. Athawale - One of the best experts on this subject based on the ideXlab platform.

  • New elastomers based on uralkyd/Polyethyl Methacrylate semi- and full interpenetrating polymer networks
    Journal of Polymer Science Part A: Polymer Chemistry, 1999
    Co-Authors: Sachin Raut, Vilas D. Athawale
    Abstract:

    Two-component semi- and full interpenetrating polymer networks (IPNs) of soybean-oil-based uralkyd resin (UA) and Polyethyl Methacrylate (PEMA) were synthesized by the sequential technique. The elastomers obtained were characterized by mechanical properties such as tensile strength, elongation, and hardness (Shore A). The apparent densities of these samples were determined and compared. Glass-transition studies were carried out using differential scanning calorimetry. The thermal characterization of the elastomers was undertaken with the aid of thermogravimetric analysis. Phase morphology was studied by scanning electron microscopy. The effect of the compositional variation on the aforementioned properties was examined. The maximum elongation for both the semi- and full IPNs was observed at 60% UA and 40% PEMA. Glass-transition studies revealed that there was a phase separation in the semi-IPNs as two T g s were obtained, whereas the full IPNs showed one T g , indicating a single phase transition.

  • new elastomers based on uralkyd Polyethyl Methacrylate semi and full interpenetrating polymer networks
    Journal of Polymer Science Part A, 1999
    Co-Authors: Sachin Raut, Vilas D. Athawale
    Abstract:

    Two-component semi- and full interpenetrating polymer networks (IPNs) of soybean-oil-based uralkyd resin (UA) and Polyethyl Methacrylate (PEMA) were synthesized by the sequential technique. The elastomers obtained were characterized by mechanical properties such as tensile strength, elongation, and hardness (Shore A). The apparent densities of these samples were determined and compared. Glass-transition studies were carried out using differential scanning calorimetry. The thermal characterization of the elastomers was undertaken with the aid of thermogravimetric analysis. Phase morphology was studied by scanning electron microscopy. The effect of the compositional variation on the aforementioned properties was examined. The maximum elongation for both the semi- and full IPNs was observed at 60% UA and 40% PEMA. Glass-transition studies revealed that there was a phase separation in the semi-IPNs as two T g s were obtained, whereas the full IPNs showed one T g , indicating a single phase transition.

Keyath Nisar - One of the best experts on this subject based on the ideXlab platform.

  • Pesticidal seed coats based on azadirachtin-A: release kinetics, storage life and performance.
    Pest Management Science, 2008
    Co-Authors: Keyath Nisar, Jitendra Kumar, M. B. Arun Kumar, Suresh Walia, Najam A. Shakil, Rajender Parsad, Balraj S. Parmar
    Abstract:

    BACKGROUND: Infestation of seeds by pests during storage leads to deterioration in quality. Seed coating is an effective option to overcome the menace. Unlike synthetic fungicidal seed coats, little is known of those based on botanicals. This study aims at developing azadirachtin-A-based pesticidal seed coats to maintain seed quality during storage. RESULTS: Polymer- and clay-based coats containing azadirachtin-A were prepared and evaluated for quality maintenance of soybean seed during storage. Gum acacia, gum tragacanth, rosin, ethyl cellulose, hydroxyethyl cellulose, Polyethyl Methacrylate, methyl cellulose, Polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone and Agrimer VA 6 polymers and the clay bentonite were used as carriers. The time for 50% release (t1/2) of azadirachtin-A into water from the seeds coated with the different coats ranged from 8.02 to 21.36 h. The half-life (T1/2) of azadirachtin-A in the coats on seed ranged from 4.37 to 11.22 months, as compared with 3.45 months in azadirachtin-A WP, showing an increase by a factor of nearly 1.3 – 3.3 over the latter. The coats apparently acted as a barrier to moisture to reduce azadirachtin-A degradation and prevented proliferation of storage fungi. Polyethyl Methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were significantly superior to the other polymers. Azadirachtin-A showed a significant positive correlation with seed germination and vigour, and negative correlation with moisture content. CONCLUSION: Effective polymeric carriers for seed coats based on azadirachtin-A are reported. These checked seed deterioration during storage by acting as a barrier to moisture and reduced the degradation of azadirachtin-A. c � 2008 Society of Chemical Industry

  • Development of polymeric seed coats for seed quality enhancement of soybean Glycine max
    Indian Journal of Agricultural Sciences, 2007
    Co-Authors: Jitender Kumar, Keyath Nisar, M. B. Arun Kumar, Suresh Walia, Najam A. Shakil, Rajender Prasad
    Abstract:

    An experiment was conducted during 2004-05 to study the seed quality enhancement of soybean (Glycine max L. Merr.) using polymeric/clay seed coats. Twelve polymers-based and 1 clay-based seed coats were prepared and compared with the commercial formulation of Thiram 75 DS for seed quality enhancement of soybean seed under storage. The carriers employed included acacia, tragacanth, rosin, ethyl cellulose, hydroxy ethyl cellulose, Polyethyl Methacrylate, methyl cellulose, Polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone, and Agrimer VA 6 and the clay bentonite. The polymer-coated seeds in general deteriorated at a slower rate compared with the control and revealed high germination percentage over the control. Apparently the coats acted as barriers to the moisture and checked the deterioration of seed. These also prevented the proliferation of storage fungi over an elevated period. Among all the polymers, polyethy1 Methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were found to be significantly superior (P = 0.01) in maintaining the soybean seed quality during storage. On perusal of correlation matrix (germination, vigour and moisture), it was observed that the moisture content of seed revealed significant negative correlation with seed germination (0.8776), seed vigour (0.7240). These products were useful in improving the storability of the seed by checking the fungal infestation and enhancing the overall seed quality during storage