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Roger W. Chan - One of the best experts on this subject based on the ideXlab platform.
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Viscoelastic Shear Properties of the fresh porcine lens
British Journal of Ophthalmology, 2006Co-Authors: Ronald A. Schachar, Roger W. ChanAbstract:Aim: To determine the viscoelastic Properties of the porcine lens Methods: Linear viscoelastic Shear Properties of the stroma of four porcine lenses were measured within 5 hours post-mortem, using sinusoidal oscillatory Shear deformation. The elastic Shear modulus, viscous Shear modulus, dynamic viscosity, damping ratio, and phase shift of the lenses were quantified by a controlled-strain, linear simple-Shear rheometer at frequencies of 10–50 Hz. Results: The mean viscoelastic Properties and their standard deviations across the frequencies examined were: the elastic Shear modulus, G′ = 6.2±4.0 Pa, the viscous Shear modulus, G″ = 19.2±2.5 Pa, the dynamic viscosity, η′ = 0.16±0.1 Pa•sec, the damping ratio ζ = 4.06±1.25, and the phase shift, δ = 76°± 5.6°. Conclusions: The measured viscoelastic Shear Properties of the porcine lens reflect a low dynamic viscosity with a high damping ratio. The porcine lens is viscoelastic and is more viscous than elastic. The magnitude of the complex Shear modulus of the porcine lens, |G*|, is similar to the Shear modulus of the young human lens. Understanding these viscoelastic Properties of the natural lens may provide guidance in developing a lens substitute capable of accommodation in the post cataract patient.
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estimation of viscoelastic Shear Properties of vocal fold tissues based on time temperature superposition
Journal of the Acoustical Society of America, 2001Co-Authors: Roger W. ChanAbstract:Empirical data on the viscoelastic Shear Properties of human vocal-fold mucosa (cover) were recently reported at relatively low frequency (0.01–15 Hz). For the data to become relevant to voice production, attempts have been made to parametrize and extrapolate the data to higher frequencies using constitutive modeling [Chan and Titze, J. Acoust. Soc. Am. 107, 565–580 (2000)]. This study investigated the feasibility of an alternative approach for data extrapolation, namely the principle of time–temperature superposition (TTS). TTS is a hybrid theoretical–empirical approach widely used by rheologists to estimate the viscoelastic Properties of polymeric systems at time or frequency scales not readily accessible experimentally. It is based on the observation that for many polymers, the molecular configurational changes that occur in a given time scale at a low temperature correspond to those that occur in a shorter time scale at a higher temperature. Using a rotational rheometer, the elastic Shear modulus (G′)...
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viscoelastic Shear Properties of human vocal fold mucosa measurement methodology and empirical results
Journal of the Acoustical Society of America, 1999Co-Authors: Roger W. Chan, Ingo R. TitzeAbstract:A standard method for the empirical rheological characterization of viscoelastic materials was adopted to measure the viscoelastic Shear Properties of human vocal-fold mucosal tissues (the superficial layer of lamina propria). A parallel-plate rotational rheometer was employed to measure Shear deformation of viscoelastic tissue samples, which were deformed between two rigid circular plates rotating in small-amplitude sinusoidal oscillations. Elastic and viscous Shear moduli of the samples were then quantified as a function of oscillation frequency (0.01 to 15 Hz) based on Shear stresses and strains recorded by the rheometer. Data were obtained from 15 excised human larynges (10 male and 5 female). Results showed that the elastic Shear modulus μ and the damping ratio ζ of human vocal-fold mucosa were relatively constant across the range of frequencies observed, while the dynamic viscosity η decreased monotonically with frequency (i.e., Shear thinning). Intersubject differences in μ and η as large as an ord...
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Hyaluronic acid (with fibronectin) as a bioimplant for the vocal fold mucosa.
The Laryngoscope, 1999Co-Authors: Roger W. Chan, Ingo R. TitzeAbstract:Objectives To measure the viscoelastic Shear Properties of hyaluronic acid, with and without fibronectin, and to compare them with those of the human vocal fold mucosa and other phonosurgical biomaterials. Methods Viscoelastic Shear Properties of various implantable biomaterials (Teflon, gelatin, collagen, fat, hyaluronic acid, and hyaluronic acid with fibronectin) were measured with a parallel-plate rotational rheometer. Elastic and viscous Shear Properties were quantified as a function of oscillation frequency (0.01-15 Hz) at 37 degrees C. Results The Shear Properties of hyaluronic acid were relatively close to those of human vocal fold mucosal tissues reported previously. Hyaluronic acid at specific concentrations (0.5%-1%), with or without fibronectin, was found to exhibit viscous Shear Properties (viscous Shear modulus and dynamic viscosity) similar to those of the average male and female vocal fold mucosa. Conclusions According to a theory that establishes the effects of tissue Shear Properties on vocal fold oscillation, phonation threshold pressure (a measure of the ease of phonation) is directly related to the viscous Shear modulus of the vibrating vocal fold mucosa. Therefore, our findings suggest that hyaluronic acid, either by itself or mixed with fibronectin, may be a potentially optimal bioimplant for the surgical management of vocal fold mucosal defects and lamina propria deficiencies (e.g., scarring) from a biomechanical standpoint.
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Hyaluronic acid (with fibronectin) as a bioimplant for the vocal fold mucosa.
The Laryngoscope, 1999Co-Authors: Roger W. Chan, Ingo R. TitzeAbstract:To measure the viscoelastic Shear Properties of hyaluronic acid, with and without fibronectin, and to compare them with those of the human vocal fold mucosa and other phonosurgical biomaterials. Viscoelastic Shear Properties of various implantable biomaterials (Teflon, gelatin, collagen, fat, hyaluronic acid, and hyaluronic acid with fibronectin) were measured with a parallel-plate rotational rheometer. Elastic and viscous Shear Properties were quantified as a function of oscillation frequency (0.01-15 Hz) at 37 degrees C. The Shear Properties of hyaluronic acid were relatively close to those of human vocal fold mucosal tissues reported previously. Hyaluronic acid at specific concentrations (0.5%-1%), with or without fibronectin, was found to exhibit viscous Shear Properties (viscous Shear modulus and dynamic viscosity) similar to those of the average male and female vocal fold mucosa. According to a theory that establishes the effects of tissue Shear Properties on vocal fold oscillation, phonation threshold pressure (a measure of the ease of phonation) is directly related to the viscous Shear modulus of the vibrating vocal fold mucosa. Therefore, our findings suggest that hyaluronic acid, either by itself or mixed with fibronectin, may be a potentially optimal bioimplant for the surgical management of vocal fold mucosal defects and lamina propria deficiencies (e.g., scarring) from a biomechanical standpoint.
Ingo R. Titze - One of the best experts on this subject based on the ideXlab platform.
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viscoelastic Shear Properties of human vocal fold mucosa measurement methodology and empirical results
Journal of the Acoustical Society of America, 1999Co-Authors: Roger W. Chan, Ingo R. TitzeAbstract:A standard method for the empirical rheological characterization of viscoelastic materials was adopted to measure the viscoelastic Shear Properties of human vocal-fold mucosal tissues (the superficial layer of lamina propria). A parallel-plate rotational rheometer was employed to measure Shear deformation of viscoelastic tissue samples, which were deformed between two rigid circular plates rotating in small-amplitude sinusoidal oscillations. Elastic and viscous Shear moduli of the samples were then quantified as a function of oscillation frequency (0.01 to 15 Hz) based on Shear stresses and strains recorded by the rheometer. Data were obtained from 15 excised human larynges (10 male and 5 female). Results showed that the elastic Shear modulus μ and the damping ratio ζ of human vocal-fold mucosa were relatively constant across the range of frequencies observed, while the dynamic viscosity η decreased monotonically with frequency (i.e., Shear thinning). Intersubject differences in μ and η as large as an ord...
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Hyaluronic acid (with fibronectin) as a bioimplant for the vocal fold mucosa.
The Laryngoscope, 1999Co-Authors: Roger W. Chan, Ingo R. TitzeAbstract:Objectives To measure the viscoelastic Shear Properties of hyaluronic acid, with and without fibronectin, and to compare them with those of the human vocal fold mucosa and other phonosurgical biomaterials. Methods Viscoelastic Shear Properties of various implantable biomaterials (Teflon, gelatin, collagen, fat, hyaluronic acid, and hyaluronic acid with fibronectin) were measured with a parallel-plate rotational rheometer. Elastic and viscous Shear Properties were quantified as a function of oscillation frequency (0.01-15 Hz) at 37 degrees C. Results The Shear Properties of hyaluronic acid were relatively close to those of human vocal fold mucosal tissues reported previously. Hyaluronic acid at specific concentrations (0.5%-1%), with or without fibronectin, was found to exhibit viscous Shear Properties (viscous Shear modulus and dynamic viscosity) similar to those of the average male and female vocal fold mucosa. Conclusions According to a theory that establishes the effects of tissue Shear Properties on vocal fold oscillation, phonation threshold pressure (a measure of the ease of phonation) is directly related to the viscous Shear modulus of the vibrating vocal fold mucosa. Therefore, our findings suggest that hyaluronic acid, either by itself or mixed with fibronectin, may be a potentially optimal bioimplant for the surgical management of vocal fold mucosal defects and lamina propria deficiencies (e.g., scarring) from a biomechanical standpoint.
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Hyaluronic acid (with fibronectin) as a bioimplant for the vocal fold mucosa.
The Laryngoscope, 1999Co-Authors: Roger W. Chan, Ingo R. TitzeAbstract:To measure the viscoelastic Shear Properties of hyaluronic acid, with and without fibronectin, and to compare them with those of the human vocal fold mucosa and other phonosurgical biomaterials. Viscoelastic Shear Properties of various implantable biomaterials (Teflon, gelatin, collagen, fat, hyaluronic acid, and hyaluronic acid with fibronectin) were measured with a parallel-plate rotational rheometer. Elastic and viscous Shear Properties were quantified as a function of oscillation frequency (0.01-15 Hz) at 37 degrees C. The Shear Properties of hyaluronic acid were relatively close to those of human vocal fold mucosal tissues reported previously. Hyaluronic acid at specific concentrations (0.5%-1%), with or without fibronectin, was found to exhibit viscous Shear Properties (viscous Shear modulus and dynamic viscosity) similar to those of the average male and female vocal fold mucosa. According to a theory that establishes the effects of tissue Shear Properties on vocal fold oscillation, phonation threshold pressure (a measure of the ease of phonation) is directly related to the viscous Shear modulus of the vibrating vocal fold mucosa. Therefore, our findings suggest that hyaluronic acid, either by itself or mixed with fibronectin, may be a potentially optimal bioimplant for the surgical management of vocal fold mucosal defects and lamina propria deficiencies (e.g., scarring) from a biomechanical standpoint.
Akira Watanabe - One of the best experts on this subject based on the ideXlab platform.
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Strain rate and temperature dependence of Shear Properties of epoxy resin with various molecular weight between cross-linkings
Journal of Materials Science, 1999Co-Authors: Minoru Miwa, Akiyoshi Takeno, Teruyuki Yokoi, Akira WatanabeAbstract:Epoxy resins with various molecular weights between cross-linkings were prepared. In order to examine the strain rate and temperature dependence of the Shear yield strength and the Shear strength, test specimens were subjected to Shear deformation at various strain rates and temperatures. The Shear yield strength and the Shear strength increased almost linearly as the logarithm of the strain rate increased. The strain rate-temperature superposition held for these Shear Properties. In particular, an experimental equation of the strain rate-temperature superposition for the Shear yield strength was found. The shift factor to obtain a master curve was given with the temperature dependence of an Arrhenius type. Furthermore, the strain rate-temperature-molecular weight between cross-linkings superposition held for the Shear Properties.
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Relation between Shear strength at the fibre-matrix interphase and Shear Properties of resin matrix
Journal of Materials Science, 1995Co-Authors: Minoru Miwa, Kouichi Yamaguchi, Akiyoshi Takeno, Akira WatanabeAbstract:The Shear yield strength and the Shear strength of a resin matrix increase almost linearly as the logarithm of the strain rate increases. This increasing tendency is almost the same at various temperatures. The strain rate temperature superposition held and an experimental equation was found to estimate the strain rate and temperature dependence of these Shear Properties. The strain rate and temperature dependence of the Shear yield strength at the fibre-matrix interphase can be also estimated by the same equation. A strong quantitative relation was observed between the strain rate and temperature dependence of the Shear Properties of a resin matrix and that of the Shear yield strength at the fibre-matrix interphase.
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Strain rate and temperature dependence of Shear Properties of epoxy resin
Journal of Materials Science, 1995Co-Authors: Minoru Miwa, A. Takeimo, H Yamazaki, Akira WatanabeAbstract:Epoxy resins with various ratios from two kinds of curing agents, ethylenediamine (EDA) and N,N′-dimethylethylenediamine (MeEDA), were prepared. In order to examine the strain rate and temperature dependence of the Shear yield strength and the Shear strength, test specimens were subjected to Shear deformation at various strain rates and temperature. The Shear yield strength and the Shear strength increased almost linearly as the logarithm of the strain rate increased. The strain rate-temperature superposition held for these Shear Properties. In particular, an experimental equation of the strain rate-temperature superposition for the Shear yield strength was found. The shift factor to obtain a master curve was given with the temperature dependence of an Arrhenius type. Furthermore, the strain rate-temperature-mixing ratio of curing agent superposition held for the Shear Properties, and the shift factor for these superpositions increased with the increase in MeEDA.
Minoru Miwa - One of the best experts on this subject based on the ideXlab platform.
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Strain rate and temperature dependence of Shear Properties of epoxy resin with various molecular weight between cross-linkings
Journal of Materials Science, 1999Co-Authors: Minoru Miwa, Akiyoshi Takeno, Teruyuki Yokoi, Akira WatanabeAbstract:Epoxy resins with various molecular weights between cross-linkings were prepared. In order to examine the strain rate and temperature dependence of the Shear yield strength and the Shear strength, test specimens were subjected to Shear deformation at various strain rates and temperatures. The Shear yield strength and the Shear strength increased almost linearly as the logarithm of the strain rate increased. The strain rate-temperature superposition held for these Shear Properties. In particular, an experimental equation of the strain rate-temperature superposition for the Shear yield strength was found. The shift factor to obtain a master curve was given with the temperature dependence of an Arrhenius type. Furthermore, the strain rate-temperature-molecular weight between cross-linkings superposition held for the Shear Properties.
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Relation between Shear strength at the fibre-matrix interphase and Shear Properties of resin matrix
Journal of Materials Science, 1995Co-Authors: Minoru Miwa, Kouichi Yamaguchi, Akiyoshi Takeno, Akira WatanabeAbstract:The Shear yield strength and the Shear strength of a resin matrix increase almost linearly as the logarithm of the strain rate increases. This increasing tendency is almost the same at various temperatures. The strain rate temperature superposition held and an experimental equation was found to estimate the strain rate and temperature dependence of these Shear Properties. The strain rate and temperature dependence of the Shear yield strength at the fibre-matrix interphase can be also estimated by the same equation. A strong quantitative relation was observed between the strain rate and temperature dependence of the Shear Properties of a resin matrix and that of the Shear yield strength at the fibre-matrix interphase.
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Strain rate and temperature dependence of Shear Properties of epoxy resin
Journal of Materials Science, 1995Co-Authors: Minoru Miwa, A. Takeimo, H Yamazaki, Akira WatanabeAbstract:Epoxy resins with various ratios from two kinds of curing agents, ethylenediamine (EDA) and N,N′-dimethylethylenediamine (MeEDA), were prepared. In order to examine the strain rate and temperature dependence of the Shear yield strength and the Shear strength, test specimens were subjected to Shear deformation at various strain rates and temperature. The Shear yield strength and the Shear strength increased almost linearly as the logarithm of the strain rate increased. The strain rate-temperature superposition held for these Shear Properties. In particular, an experimental equation of the strain rate-temperature superposition for the Shear yield strength was found. The shift factor to obtain a master curve was given with the temperature dependence of an Arrhenius type. Furthermore, the strain rate-temperature-mixing ratio of curing agent superposition held for the Shear Properties, and the shift factor for these superpositions increased with the increase in MeEDA.
H. Luo - One of the best experts on this subject based on the ideXlab platform.
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Variation of Shear Properties of welded spruce at different pressures and welding times
Biotribology, 2016Co-Authors: S. Amirou, A. Pizzi, H. LuoAbstract:This work presents a study of mechanical Properties of the wood end-grain welding of spruce wood. The Shear Properties of butt joints of spruce at different pressure and welding time were studied. Between all the parameters of spruce welding, the welding pressure is one of the most important in relation to the mechanical Properties. Thus, a good joint strength was obtained for spruce wood at high pressure. An increase of Shear strength is observed with an increase in welding pressure. It is clear that at high pressure the welded material becomes more rigid and this is also coupled to the to the more extensive condensation reaction of lignin. The defibration tendency in end-grain-to-end-grain welding indicates that wood spruce welding is possible and yields sufficient joint strength. The welded interphase in end-grain-to-end-grain spruce welding appears possible and gives a joint with an anatomical appearance of a “natural” fingerjoint. Such “natural” fingerjoints can give equivalent than glued fingerjoints. The advantages of the end-grain-to-end-grain welding are then the very short time of processing, the dispensation of preparing the fingerjoint profiles and to avoid the use of adhesives.
