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Fanny Ferreira Melo Fávero De ,fravet - One of the best experts on this subject based on the ideXlab platform.
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Modelagem e simulação do processo de esterilização térmica em batelada de vegetais em conserva
Universidade Federal de Uberlândia, 2006Co-Authors: Fanny Ferreira Melo Fávero De ,fravetAbstract:A esterilização térmica de alimentos baseia-se na aplicação de condições de temperatura por períodos de tempo que levem à inativação de microorganismos, esporos e enzimas e conseqüentemente a obtenção de produtos seguros por períodos ampliados de tempo. Neste trabalho é proposto um modelo matemático capaz de representar a transferência de calor durante o tratamento térmico de vegetais em conserva em autoclave a vapor, horizontal, com múltiplos estágios e operação em batelada. A partir de uma metodologia teóricocomputacional, desenvolveram-se modelos parciais representativos da troca térmica no grão, lata e autoclave, com posterior acoplamento desses em um modelo global. O modelo dinâmico proposto possui vários níveis de detalhamento, sendo que a lata avaliada foi investigada numa geometria bidimensional. O método numérico da colocação ortogonal bidimensional acoplado ao método das linhas (MOL) foi utilizado para a solução das equações diferencias parciais encontradas. O modelo foi validado através de comparação dos resultados encontrados com valores baseados em curva de penetração térmica de ervilhas reportados na literatura. Os resultados apresentados por este estudo mostram que o modelo proposto representa satisfatoriamente o processo de esterilização de alimentos enlatados. Mostra, também, que a letalidade pode ser definida como função objetivo monitorada para propósito de controle, mostrando-se adequada para a garantia da segurança do produto.The thermal food Sterilization is based on the application of temperature conditions for established periods that perform a commercial Sterilization of microorganisms, spores and enzymes that has as main goal the attainment of safe products for consumption during extended periods of time. This work addresses the Sterilization processing of canned food for the action of heat and introduces a novel mathematical model capable of describing the heat transfer during the thermal treatment of canned vegetables, simulating a processing in a retort. The adopted retort works with vapor, it is horizontal with multiples stages during a batch Sterilization Cycle. With a modeling methodology, representative partial models of the thermal exchange in the grain/vegetable and can were developed, with posterior coupling of these models in a retort unit model. The considered dynamic models possess 1D level of detail for vegetables, 2D level of detail for the can. The used numerical methods for the solution of the coupled set of partial and ordinary differential equations were the orthogonal collocation technique coupled to the method of lines (MOL). The model was validated through a comparison of the results with values based on thermal penetration curve during peas Sterilization reported in the literature. The results for this study show that the proposed model satisfactorily represents the process of canned food Sterilization. It also indicates that the lethality could be defined as the monitoring function for online process control, leading to suitable and safe methods for safe production of a sterilized canned product
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Modelagem e simulação do processo de esterilização térmica em batelada de vegetais em conserva
UFU, 2006Co-Authors: Fanny Ferreira Melo Fávero De ,fravetAbstract:The thermal food Sterilization is based on the application of temperature conditions for established periods that perform a commercial Sterilization of microorganisms, spores and enzymes that has as main goal the attainment of safe products for consumption during extended periods of time. This work addresses the Sterilization processing of canned food for the action of heat and introduces a novel mathematical model capable of describing the heat transfer during the thermal treatment of canned vegetables, simulating a processing in a retort. The adopted retort works with vapor, it is horizontal with multiples stages during a batch Sterilization Cycle. With a modeling methodology, representative partial models of the thermal exchange in the grain/vegetable and can were developed, with posterior coupling of these models in a retort unit model. The considered dynamic models possess 1D level of detail for vegetables, 2D level of detail for the can. The used numerical methods for the solution of the coupled set of partial and ordinary differential equations were the orthogonal collocation technique coupled to the method of lines (MOL). The model was validated through a comparison of the results with values based on thermal penetration curve during peas Sterilization reported in the literature. The results for this study show that the proposed model satisfactorily represents the process of canned food Sterilization. It also indicates that the lethality could be defined as the monitoring function for online process control, leading to suitable and safe methods for safe production of a sterilized canned product.Mestre em Engenharia QuímicaA esterilização térmica de alimentos baseia-se na aplicação de condições de temperatura por períodos de tempo que levem à inativação de microorganismos, esporos e enzimas e conseqüentemente a obtenção de produtos seguros por períodos ampliados de tempo. Neste trabalho é proposto um modelo matemático capaz de representar a transferência de calor durante o tratamento térmico de vegetais em conserva em autoclave a vapor, horizontal, com múltiplos estágios e operação em batelada. A partir de uma metodologia teóricocomputacional, desenvolveram-se modelos parciais representativos da troca térmica no grão, lata e autoclave, com posterior acoplamento desses em um modelo global. O modelo dinâmico proposto possui vários níveis de detalhamento, sendo que a lata avaliada foi investigada numa geometria bidimensional. O método numérico da colocação ortogonal bidimensional acoplado ao método das linhas (MOL) foi utilizado para a solução das equações diferencias parciais encontradas. O modelo foi validado através de comparação dos resultados encontrados com valores baseados em curva de penetração térmica de ervilhas reportados na literatura. Os resultados apresentados por este estudo mostram que o modelo proposto representa satisfatoriamente o processo de esterilização de alimentos enlatados. Mostra, também, que a letalidade pode ser definida como função objetivo monitorada para propósito de controle, mostrando-se adequada para a garantia da segurança do produto
J T Han - One of the best experts on this subject based on the ideXlab platform.
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an in vitro assessment of the physical properties of novel hyflex nickel titanium rotary instruments
International Endodontic Journal, 2012Co-Authors: Ove A Peters, A K Gluskin, R A Weiss, J T HanAbstract:Peters OA, Gluskin AK, Weiss RA, Han JT. An in vitro assessment of the physical properties of novel Hyflex nickel–titanium rotary instruments. International Endodontic Journal, 45, 1027–1034, 2012. Abstract Aim To determine several properties including torsional and fatigue limits, as well as torque during canal preparation, of Hyflex, a rotary instrument manufactured from so-called controlled memory nickel–titanium alloy. Methodology The instruments were tested in vitro using a special torque bench that permits both stationary torque tests according to ISO3630-1 and fatigue limit determination, as well as measurement of torque (in Ncm) and apical force (in N) during canal preparation. Fatigue limit (in numbers of Cycles to failure) was determined in a 90°, 5 mm radius block-and-rod assembly. Simulated canals in plastic blocks were prepared using both a manufacturer-recommended single-length technique as well as a generic crown-down approach. anova with Bonferroni post hoc procedures was used for statistical analysis. Results Torque at failure ranged from 0.47 to 1.38 Ncm, with significant differences between instrument sizes (P < 0.0001). Fatigue life ranged from 260 to 2565, with the shortest and longest lifespan for instruments size 20, .04 taper and size 25, .08 taper, respectively. Torque during canal preparation was significantly higher for small instruments used in the single-length technique but lower for the size 40, .04 taper, compared to a crown-down approach. No instrument fractured; 82% of the instruments used were plastically deformed; however, only 37% of these remained deformed after a Sterilization Cycle. Conclusions Hyflex rotary instruments are bendable and flexible and have similar torsional resistance compared to instruments made of conventional NiTi. Fatigue resistance is much higher, and torque during preparation is less, compared to other rotary instruments tested previously under similar conditions.
Silvia Fare - One of the best experts on this subject based on the ideXlab platform.
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shape memory polymer foams for cerebral aneurysm reparation effects of plasma Sterilization on physical properties and cytocompatibility
Acta Biomaterialia, 2009Co-Authors: Luigi De Nardo, Lhocine Yahia, Rachele Alberti, A Cigada, M C Tanzi, Silvia FareAbstract:Abstract Shape memory polyurethanes (SMPUs) represent promising candidate materials for aneurysm embolization, since they could enable clinical problems still associated with these clinical procedures to be overcome. In this work, we report on the characterization of physicochemical, thermomechanical and in vitro interface properties of two SMPU foams (Cold Hibernated Elastic Memory, CHEM), proposed as a material for embolization devices in minimally invasive procedures. Moreover, because device Sterilization is mandatory for in vivo applications, effects on the properties of the foams after plasma Sterilization were also evaluated. Both foams (CHEM 3520 and CHEM 5520) showed excellent shape recovery ability (recovery rate, R r , up to 99%) in conventional shape recovery tests, performed at constant heating rate. Transition temperatures ( T trans ), determined by tan δ peaks in dynamic mechanical analysis (DMA), were 32.2 and 45.1 °C, for CHEM 3520 and 5520, respectively. The value of T trans affects shape memory ability in the recovery test at 37 °C, which simulates the behavior after implantation of the device: in fact, R r was significantly higher for lower T trans foam ( R r ≈ 82% and R r ≈ 46%, respectively, for CHEM 3520 and CHEM 5520). After plasma Sterilization performed by a Sterrad ® Sterilization system, an increase in open porosity was observed: this is probably due to the Sterilization Cycle; however, no effects on shape recovery behavior were observed. Furthermore, plasma treatment had no significant effect on L929 cells in in vitro cytotoxicity tests, performed on cell culture medium extracts in contact with foams for up to 7 days. Moreover, direct cytocompatibility tests showed a good colonization and growth from L929 cells on CHEM foams, suggesting the effectiveness of an in vivo healing process. All these results seem to suggest that CHEM foams could be advantageously used for manufacturing devices for mini-invasive embolization procedures of aneurysms.
Pinto, Terezinha De Jesus Andreoli - One of the best experts on this subject based on the ideXlab platform.
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Reutilização das pastilhas de paraformaldeído: avaliação da sua atividade esterilizante
Universidade de São Paulo. Escola de Enfermagem, 2002Co-Authors: Graziano, Kazuko Uchikawa, Cianciarullo, Tamara Iwanow, Pinto, Terezinha De Jesus AndreoliAbstract:The sterilizing activity of reused Paraformaldehyde tablets was assessed by microbiologic monitoring according to the Association of Official Analytical Chemists (AOAC) technic required in Brazil to register this class of sanitizing substances into the Health Ministery. Previous to the microbiologic tests, physical-chemscs assays were done through iodine titration according to the Society of Japanese Pharmacopoeia. It was possible, than, to draw a graphic showing a curve of the gaseous formaldehyde concentration discharged, at each Sterilization Cycle in relation to the number of reuse of the paraformaldehyde tablets.Through this graphic it was possible to chose the adequate moment to make the microbiologic analysis. After 12 Cycles, the some group of the paraformaldehyde tablets kept the sterilizing activity at 3% concentration (3g/ 100 cm³), at 50ºC, for 4 hours of exposition time with great relative humidity.La actividad esterilizante de las pastillas de paraformaldeído, reutilizadas, fué evaluada por medio de control microbiológico, según la técnica de la Association of Official Analytical Chemists (AOAC), exigida, en Brasil, por la Unidad de Vigilancia Sanitaria del Ministerio de Salud. Preliminarmente , se realizaron ensayos físicoquimicos por medio de la titulometria yodométrica, según la Society of Japanese Pharmacopeia, que permitieron la construcción de una curva de concentración de formaldeído gaseoso, liberado por ciclo de esterilización, en relación al número de reutilizaciones, y subsidios para la elección del momento de realización de los andlisis microbiológicos. Las pastillas de paraformaldeído mantuvieron actividad esterilizante en una concentración del 3% (3g/100cm3) en un período de exposición de 4 horas a una temperatura de 50o C sometida a humedad relativa máxima, después de 12 ciclos de reutilizaciones del mismo grupo de pastillas.A atividade esterilizante das pastilhas de paraformaldeído reutilizadas foi avaliada por meio do monitoramento microbiológico, segundo a técnica da Association of Official Analytical Chemists (AOAC), exigida no Brasil para o registro desta categoria de saneastes junto à Vigilância Sanitária do Ministério da Saúde. Preliminarmente aos testes ulometria iodométrica segundo a Society of Japanese Pharmacopeia que permitiram a construção de uma curva de concentração de formaldeído gasoso liberado por ciclo de esterilização, em relação ao número de reutilizações, subsidiando, desta forma, a escolha do momento da realização das análises microbiológicas. As pastilhas de paraformaldeído mantiveram atividade esterilizante na concentração de 3% (3g/100 cm³) num período de exposição de 4 h à temperatura de 50ºC sob umidade relativa máxima, após 12 ciclos de reutilizações de um mesmo grupo de pastilhas
Luigi De Nardo - One of the best experts on this subject based on the ideXlab platform.
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shape memory polymer foams for cerebral aneurysm reparation effects of plasma Sterilization on physical properties and cytocompatibility
Acta Biomaterialia, 2009Co-Authors: Luigi De Nardo, Lhocine Yahia, Rachele Alberti, A Cigada, M C Tanzi, Silvia FareAbstract:Abstract Shape memory polyurethanes (SMPUs) represent promising candidate materials for aneurysm embolization, since they could enable clinical problems still associated with these clinical procedures to be overcome. In this work, we report on the characterization of physicochemical, thermomechanical and in vitro interface properties of two SMPU foams (Cold Hibernated Elastic Memory, CHEM), proposed as a material for embolization devices in minimally invasive procedures. Moreover, because device Sterilization is mandatory for in vivo applications, effects on the properties of the foams after plasma Sterilization were also evaluated. Both foams (CHEM 3520 and CHEM 5520) showed excellent shape recovery ability (recovery rate, R r , up to 99%) in conventional shape recovery tests, performed at constant heating rate. Transition temperatures ( T trans ), determined by tan δ peaks in dynamic mechanical analysis (DMA), were 32.2 and 45.1 °C, for CHEM 3520 and 5520, respectively. The value of T trans affects shape memory ability in the recovery test at 37 °C, which simulates the behavior after implantation of the device: in fact, R r was significantly higher for lower T trans foam ( R r ≈ 82% and R r ≈ 46%, respectively, for CHEM 3520 and CHEM 5520). After plasma Sterilization performed by a Sterrad ® Sterilization system, an increase in open porosity was observed: this is probably due to the Sterilization Cycle; however, no effects on shape recovery behavior were observed. Furthermore, plasma treatment had no significant effect on L929 cells in in vitro cytotoxicity tests, performed on cell culture medium extracts in contact with foams for up to 7 days. Moreover, direct cytocompatibility tests showed a good colonization and growth from L929 cells on CHEM foams, suggesting the effectiveness of an in vivo healing process. All these results seem to suggest that CHEM foams could be advantageously used for manufacturing devices for mini-invasive embolization procedures of aneurysms.