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Alireza Daneshmehr - One of the best experts on this subject based on the ideXlab platform.
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low velocity impact analysis of fiber metal laminates fmls in thermal Environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of GLARE5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The Effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal Environment are investigated in detail. In order to consider thermal Environment Effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal Environment affect the low velocity impact response of GLARE, hitherto not reported in the open literature.
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low velocity impact analysis of fiber metal laminates fmls in thermal Environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of GLARE5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The Effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal Environment are investigated in detail. In order to consider thermal Environment Effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal Environment affect the low velocity impact response of GLARE, hitherto not reported in the open literature.
Steven Offenbacher - One of the best experts on this subject based on the ideXlab platform.
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a polymeric device for delivery of anti microbial and anti fungal drugs in the oral Environment Effect of temperature and medium on the rate of drug release
Dental Materials, 2003Co-Authors: S. Kalachandra, J Valiyaparambil, Steven OffenbacherAbstract:OBJECTIVES: The use of drug delivery systems in dentistry is a relatively new area of research with the exception of fluoride ion release from polyalkenoate cements and their predecessor silicate cements. The present study is based on the use of a bio-compatible material ethylene vinyl acetate copolymer (EVA) that enables constant release of drugs of therapeutic levels over extended periods of time at doses suitable for the treatment of oral conditions. METHODS: Polymer casting solutions were made by dissolving EVA and the drug in the ratio of 40:1 in 70 ml of dichloromethane at 38 degrees C for 6 h. Thin square films of 3 x 3 cm2 with a thickness of 1 mm were cut from the dry sheet obtained by solvent evaporation technique. Drug loaded samples were extracted for a minimum of 14 days in 10 ml medium (double distilled water or water/ethanol (4:1)) which was replaced daily. Spectral measurements were made to follow changes in optical densities (OD) during release kinetics. Effect of temperature (24 and 37 degrees C) on the rate of drug release was studied and the energies of activation (DeltaE not equal ) were calculated using Arrehenius equation for the diffusion (translocation) of molecules of tetracycline hydrochloride (TTH), doxycycline hydrochloride (DOH), and chlorhexidine diacetate (CDA) in water as extracting medium. Effect of extracting medium (water and water/ethanol (4:1)) was also investigated on the rate of drug release measurements at 24 degrees C. RESULTS: Analysis of variance of the data revealed that significantly enhanced rates were observed at the higher temperature (37 degrees C) and when extracting medium was changed to water/ethanol (4:1) for TTH, DOH and CDA (p<0.0015). The enhanced rate values seem to be due to the formation of channels in the polymer. The largest activation energy (21.83 kcal mol(-1)) observed for CDA was interpreted as due to the highest average molecular weight (626) compared to TTH (481) and DOH (481).Significance. These in vitro rate of drug release measurements will provide a basis for establishing a novel approach (treatment modality) for sustained intra-oral drug delivery over extended time periods using laboratory methods and materials that are readily available to dentists.
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a polymeric device for delivery of anti microbial and anti fungal drugs in the oral Environment Effect of temperature and medium on the rate of drug release
Dental Materials, 2003Co-Authors: D M Lin, J Valiyaparambil, S. Kalachandra, Steven OffenbacherAbstract:Abstract Objectives . The use of drug delivery systems in dentistry is a relatively new area of research with the exception of fluoride ion release from polyalkenoate cements and their predecessor silicate cements. The present study is based on the use of a bio-compatible material ethylene vinyl acetate copolymer (EVA) that enables constant release of drugs of therapeutic levels over extended periods of time at doses suitable for the treatment of oral conditions. Method . Polymer casting solutions were made by dissolving EVA and the drug in the ratio of 40:1 in 70 ml of dichloromethane at 38 °C for 6 h. Thin square films of 3×3 cm 2 with a thickness of 1 mm were cut from the dry sheet obtained by solvent evaporation technique. Drug loaded samples were extracted for a minimum of 14 days in 10 ml medium (double distilled water or water/ethanol (4:1)) which was replaced daily. Spectral measurements were made to follow changes in optical densities (OD) during release kinetics. Effect of temperature (24 and 37 °C) on the rate of drug release was studied and the energies of activation (Δ E ≠ ) were calculated using Arrehenius equation for the diffusion (translocation) of molecules of tetracycline hydrochloride (TTH), doxycycline hydrochloride (DOH), and chlorhexidine diacetate (CDA) in water as extracting medium. Effect of extracting medium (water and water/ethanol (4:1)) was also investigated on the rate of drug release measurements at 24 °C. Results . Analysis of variance of the data revealed that significantly enhanced rates were observed at the higher temperature (37 °C) and when extracting medium was changed to water/ethanol (4:1) for TTH, DOH and CDA ( p −1 ) observed for CDA was interpreted as due to the highest average molecular weight (626) compared to TTH (481) and DOH (481). Significance . These in vitro rate of drug release measurements will provide a basis for establishing a novel approach (treatment modality) for sustained intra-oral drug delivery over extended time periods using laboratory methods and materials that are readily available to dentists.
S. Kalachandra - One of the best experts on this subject based on the ideXlab platform.
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Poly(ethylene-co-vinyl acetate) copolymer matrix for delivery of chlorhexidine and acyclovir drugs for use in the oral Environment: Effect of drug combination, copolymer composition and coating on the drug release rate
Dental materials : official publication of the Academy of Dental Materials, 2006Co-Authors: Padmavathy Tallury, Nazila Alimohammadi, S. KalachandraAbstract:Abstract Objectives This study utilizes a bio-compatible ethylene vinyl acetate (EVA) copolymer to deliver drugs at therapeutic levels over extended periods of time. The release rate of an anti-fungal and an anti-microbial drug namely acyclovir (ACY) and chlorhexidine diacetate (CDA) from EVA was investigated individually and as a mixture. The Effect of drug combination, the composition of the copolymer and the coating of the matrix with a different polymer on the rate of drug release are presented. Method Polymer casting solutions were prepared by homogeneously dissolving EVA copolymer and the drugs in the ratio (40:1) in dichloromethane. The drugs ACY and CDA were used individually as well as in three different weight ratios maintaining the total drug concentration in the polymer at 2.5%. Different concentrations of vinyl acetate (VA) 28, 32 and 40% in the EVA matrix were used to study the release of either ACY or CDA alone while 40% VA was used for the release study of the individual drug as well as their mixtures. Thin square films of 3 cm × 3 cm with a thickness of 0.7 mm were cut from the dry sheet obtained by solvent evaporation. Coated films were prepared by dipping ACY and CDA drug-loaded EVA films (VA 40%) into EVA copolymer of VA 32% and then dried. All of the drug-loaded samples were extracted at 37 °C in 10 ml distilled water that was replaced daily. The rate of individual drug release was measured by UV-spectrophotometer while the mixtures of drugs were measured by high performance liquid chromatography (HPLC). Results The release rate of ACY is higher than that of CDA both individually and in the ACY/CDA 50/50 mixture. In the other mixtures, the release of the drug is proportional to its concentration in the mixture. Total release of ACY is higher than CDA in most compositions. The Effect of increasing the vinyl acetate content of the EVA matrix increased the drug release rate ( p = 0.02) while coating of films resulted in a decrease of the release rate of the drugs. Significance Measurements of the in vitro rate of drug release showed that there was a sustained release of drug at an almost constant concentration over extended period of time, thus providing a basis for oral treatment modality. We show that it is possible to alter the rate of drug release in the EVA matrix to a desired value by: (1) changing the composition of the EVA copolymer, (2) altering the mixtures of drugs and (3) coating the matrix with additional polymer. The use of mixtures of drugs that can enhance or decrease the rate of drug release may prove more Effective in treating persistent oral infections in immunocompromised patients.
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a polymeric device for delivery of anti microbial and anti fungal drugs in the oral Environment Effect of temperature and medium on the rate of drug release
Dental Materials, 2003Co-Authors: S. Kalachandra, J Valiyaparambil, Steven OffenbacherAbstract:OBJECTIVES: The use of drug delivery systems in dentistry is a relatively new area of research with the exception of fluoride ion release from polyalkenoate cements and their predecessor silicate cements. The present study is based on the use of a bio-compatible material ethylene vinyl acetate copolymer (EVA) that enables constant release of drugs of therapeutic levels over extended periods of time at doses suitable for the treatment of oral conditions. METHODS: Polymer casting solutions were made by dissolving EVA and the drug in the ratio of 40:1 in 70 ml of dichloromethane at 38 degrees C for 6 h. Thin square films of 3 x 3 cm2 with a thickness of 1 mm were cut from the dry sheet obtained by solvent evaporation technique. Drug loaded samples were extracted for a minimum of 14 days in 10 ml medium (double distilled water or water/ethanol (4:1)) which was replaced daily. Spectral measurements were made to follow changes in optical densities (OD) during release kinetics. Effect of temperature (24 and 37 degrees C) on the rate of drug release was studied and the energies of activation (DeltaE not equal ) were calculated using Arrehenius equation for the diffusion (translocation) of molecules of tetracycline hydrochloride (TTH), doxycycline hydrochloride (DOH), and chlorhexidine diacetate (CDA) in water as extracting medium. Effect of extracting medium (water and water/ethanol (4:1)) was also investigated on the rate of drug release measurements at 24 degrees C. RESULTS: Analysis of variance of the data revealed that significantly enhanced rates were observed at the higher temperature (37 degrees C) and when extracting medium was changed to water/ethanol (4:1) for TTH, DOH and CDA (p<0.0015). The enhanced rate values seem to be due to the formation of channels in the polymer. The largest activation energy (21.83 kcal mol(-1)) observed for CDA was interpreted as due to the highest average molecular weight (626) compared to TTH (481) and DOH (481).Significance. These in vitro rate of drug release measurements will provide a basis for establishing a novel approach (treatment modality) for sustained intra-oral drug delivery over extended time periods using laboratory methods and materials that are readily available to dentists.
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a polymeric device for delivery of anti microbial and anti fungal drugs in the oral Environment Effect of temperature and medium on the rate of drug release
Dental Materials, 2003Co-Authors: D M Lin, J Valiyaparambil, S. Kalachandra, Steven OffenbacherAbstract:Abstract Objectives . The use of drug delivery systems in dentistry is a relatively new area of research with the exception of fluoride ion release from polyalkenoate cements and their predecessor silicate cements. The present study is based on the use of a bio-compatible material ethylene vinyl acetate copolymer (EVA) that enables constant release of drugs of therapeutic levels over extended periods of time at doses suitable for the treatment of oral conditions. Method . Polymer casting solutions were made by dissolving EVA and the drug in the ratio of 40:1 in 70 ml of dichloromethane at 38 °C for 6 h. Thin square films of 3×3 cm 2 with a thickness of 1 mm were cut from the dry sheet obtained by solvent evaporation technique. Drug loaded samples were extracted for a minimum of 14 days in 10 ml medium (double distilled water or water/ethanol (4:1)) which was replaced daily. Spectral measurements were made to follow changes in optical densities (OD) during release kinetics. Effect of temperature (24 and 37 °C) on the rate of drug release was studied and the energies of activation (Δ E ≠ ) were calculated using Arrehenius equation for the diffusion (translocation) of molecules of tetracycline hydrochloride (TTH), doxycycline hydrochloride (DOH), and chlorhexidine diacetate (CDA) in water as extracting medium. Effect of extracting medium (water and water/ethanol (4:1)) was also investigated on the rate of drug release measurements at 24 °C. Results . Analysis of variance of the data revealed that significantly enhanced rates were observed at the higher temperature (37 °C) and when extracting medium was changed to water/ethanol (4:1) for TTH, DOH and CDA ( p −1 ) observed for CDA was interpreted as due to the highest average molecular weight (626) compared to TTH (481) and DOH (481). Significance . These in vitro rate of drug release measurements will provide a basis for establishing a novel approach (treatment modality) for sustained intra-oral drug delivery over extended time periods using laboratory methods and materials that are readily available to dentists.
Hamed Zarei - One of the best experts on this subject based on the ideXlab platform.
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low velocity impact analysis of fiber metal laminates fmls in thermal Environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of GLARE5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The Effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal Environment are investigated in detail. In order to consider thermal Environment Effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal Environment affect the low velocity impact response of GLARE, hitherto not reported in the open literature.
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low velocity impact analysis of fiber metal laminates fmls in thermal Environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of GLARE5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The Effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal Environment are investigated in detail. In order to consider thermal Environment Effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal Environment affect the low velocity impact response of GLARE, hitherto not reported in the open literature.
Mohadeseh Fallah - One of the best experts on this subject based on the ideXlab platform.
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low velocity impact analysis of fiber metal laminates fmls in thermal Environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of GLARE5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The Effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal Environment are investigated in detail. In order to consider thermal Environment Effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal Environment affect the low velocity impact response of GLARE, hitherto not reported in the open literature.
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low velocity impact analysis of fiber metal laminates fmls in thermal Environments with various boundary conditions
Composite Structures, 2016Co-Authors: Hamed Zarei, Mohadeseh Fallah, Giangiacomo Minak, H Bisadi, Alireza DaneshmehrAbstract:Abstract This paper presents the dynamic response of GLARE5-3/2 subjected to low velocity impact. Governing equations are derived based on laminate theory and Hamilton’s principle. The Hertzian contact law is employed to capture contact force history and other impact characteristics. A Ritz based approach appropriate for in-plane loads and various boundary conditions is developed. The nonlinear system of equations is solved using the fourth order Runge–Kutta method. The validity of the present model is demonstrated by good agreement of comparisons between its predictions and results in the literature. The Effect of various parameters such as impactor velocity, impactor radius, boundary conditions and thermal Environment are investigated in detail. In order to consider thermal Environment Effect, the temperature dependent material properties are taken into account. Boundary conditions and thermal Environment affect the low velocity impact response of GLARE, hitherto not reported in the open literature.