The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
I Santamariaholek - One of the best experts on this subject based on the ideXlab platform.
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the rheology of hard sphere suspensions at arbitrary volume fractions an improved Differential viscosity model
Journal of Chemical Physics, 2009Co-Authors: Carlos I Mendoza, I SantamariaholekAbstract:We propose a simple and general model accounting for the dependence of the viscosity of a hard sphere suspension at arbitrary volume fractions. The model constitutes a continuum-medium description based on a recursive-Differential Method where correlations between the spheres are introduced through an effective volume fraction. In contrast to other Differential Methods, the introduction of the effective volume fraction as the integration variable implicitly considers interactions between the spheres of the same recursive stage. The final expression for the viscosity scales with this effective volume fraction, which allows constructing a master curve that contains all the experimental situations considered. The agreement of our expression for the viscosity with experiments at low- and high-shear rates and in the high-frequency limit is remarkable for all volume fractions.
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the rheology of hard sphere suspensions at arbitrary volume fractions an improved Differential viscosity model
arXiv: Soft Condensed Matter, 2008Co-Authors: Carlos I Mendoza, I SantamariaholekAbstract:We propose a simple and general model accounting for the dependence of the viscosity of a hard sphere suspension at arbitrary volume fractions. The model constitutes a continuum-medium description based on a recursive-Differential Method that assumes a hierarchy of relaxation times. Geometrical information of the system is introduced through an effective volume fraction that approaches the usual filling fraction at low concentrations and becomes one at maximum packing. The agreement of our expression for the viscosity with experiments at low- and high-shear rates and in the high-frequency limit is remarkable for all volume fractions.
Carlos I Mendoza - One of the best experts on this subject based on the ideXlab platform.
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the rheology of hard sphere suspensions at arbitrary volume fractions an improved Differential viscosity model
Journal of Chemical Physics, 2009Co-Authors: Carlos I Mendoza, I SantamariaholekAbstract:We propose a simple and general model accounting for the dependence of the viscosity of a hard sphere suspension at arbitrary volume fractions. The model constitutes a continuum-medium description based on a recursive-Differential Method where correlations between the spheres are introduced through an effective volume fraction. In contrast to other Differential Methods, the introduction of the effective volume fraction as the integration variable implicitly considers interactions between the spheres of the same recursive stage. The final expression for the viscosity scales with this effective volume fraction, which allows constructing a master curve that contains all the experimental situations considered. The agreement of our expression for the viscosity with experiments at low- and high-shear rates and in the high-frequency limit is remarkable for all volume fractions.
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the rheology of hard sphere suspensions at arbitrary volume fractions an improved Differential viscosity model
arXiv: Soft Condensed Matter, 2008Co-Authors: Carlos I Mendoza, I SantamariaholekAbstract:We propose a simple and general model accounting for the dependence of the viscosity of a hard sphere suspension at arbitrary volume fractions. The model constitutes a continuum-medium description based on a recursive-Differential Method that assumes a hierarchy of relaxation times. Geometrical information of the system is introduced through an effective volume fraction that approaches the usual filling fraction at low concentrations and becomes one at maximum packing. The agreement of our expression for the viscosity with experiments at low- and high-shear rates and in the high-frequency limit is remarkable for all volume fractions.
Jyrki Kauppinen - One of the best experts on this subject based on the ideXlab platform.
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extremely sensitive trace gas analysis with modern photoacoustic spectroscopy
Vibrational Spectroscopy, 2006Co-Authors: V Koskinen, Jyrki Kauppinen, J Fonsen, I KauppinenAbstract:Abstract An extremely sensitive approach to detect weak pressure variations has been applied to photoacoustic spectroscopy. A capacitive microphone is replaced with a miniature silicon cantilever, whose displacement is measured with a compact Michelson-type laser interferometer. Major improvements to the sensitivity of photoacoustic detection have been achieved. For example, a sub-ppb detection limit for methane gas has been obtained with a conventional photoacoustic setup in a nonresonant operation mode, using a broadband black body radiator as a source. The new sensing Method has also been applied to the detection of carbon dioxide with a distributed feedback diode laser. A noise equivalent sensitivity of 4.6 × 10 −9 cm −1 WHz −1/2 was demonstrated. A novel selective Differential Method, which combines the photoacoustic detection with long path absorption spectroscopy, is described.
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selective Differential photoacoustic Method for trace gas analysis
Vibrational Spectroscopy, 2005Co-Authors: Juho Uotila, V Koskinen, Jyrki KauppinenAbstract:A selective Differential photoacoustic Method for trace gas measurements is introduced. The Method combines long path absorption spectroscopy with photoacoustic spectroscopy. A photoacoustic cell, equipped with a highly sensitive cantilever pressure sensor, was used as a selective detector for broadband IR-radiation passed through the sample gas. Therefore, an additional optical filter is not required. The detection limit at level of 10 ppb for methane was obtained (0.37 s measurement time and approximately 1 m effective absorption path). The sensitivity of the conventional photoacoustic Method was enhanced by factor 2.8. The selectivity was tested by measuring the cross-interference signal between methane, carbon dioxide and butane in different conditions. The Differential Method enabled perfect separation of methane and carbon dioxide. Butane caused only one fifth of the cross-interference signal with methane compared to a cross-interference measured with a conventional filter system.
V Koskinen - One of the best experts on this subject based on the ideXlab platform.
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extremely sensitive trace gas analysis with modern photoacoustic spectroscopy
Vibrational Spectroscopy, 2006Co-Authors: V Koskinen, Jyrki Kauppinen, J Fonsen, I KauppinenAbstract:Abstract An extremely sensitive approach to detect weak pressure variations has been applied to photoacoustic spectroscopy. A capacitive microphone is replaced with a miniature silicon cantilever, whose displacement is measured with a compact Michelson-type laser interferometer. Major improvements to the sensitivity of photoacoustic detection have been achieved. For example, a sub-ppb detection limit for methane gas has been obtained with a conventional photoacoustic setup in a nonresonant operation mode, using a broadband black body radiator as a source. The new sensing Method has also been applied to the detection of carbon dioxide with a distributed feedback diode laser. A noise equivalent sensitivity of 4.6 × 10 −9 cm −1 WHz −1/2 was demonstrated. A novel selective Differential Method, which combines the photoacoustic detection with long path absorption spectroscopy, is described.
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selective Differential photoacoustic Method for trace gas analysis
Vibrational Spectroscopy, 2005Co-Authors: Juho Uotila, V Koskinen, Jyrki KauppinenAbstract:A selective Differential photoacoustic Method for trace gas measurements is introduced. The Method combines long path absorption spectroscopy with photoacoustic spectroscopy. A photoacoustic cell, equipped with a highly sensitive cantilever pressure sensor, was used as a selective detector for broadband IR-radiation passed through the sample gas. Therefore, an additional optical filter is not required. The detection limit at level of 10 ppb for methane was obtained (0.37 s measurement time and approximately 1 m effective absorption path). The sensitivity of the conventional photoacoustic Method was enhanced by factor 2.8. The selectivity was tested by measuring the cross-interference signal between methane, carbon dioxide and butane in different conditions. The Differential Method enabled perfect separation of methane and carbon dioxide. Butane caused only one fifth of the cross-interference signal with methane compared to a cross-interference measured with a conventional filter system.
Volker Bohm - One of the best experts on this subject based on the ideXlab platform.
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processing strawberries to different products alters contents of vitamin c total phenolics total anthocyanins and antioxidant capacity
Journal of Agricultural and Food Chemistry, 2005Co-Authors: Yvonne Klopotek, Konrad Otto, Volker BohmAbstract:Strawberries were processed to juice, nectar, wine, and puree. For investigation of the antioxidant capacity as well as the contents of ascorbic acid, total phenolics and total anthocyanins, samples were taken after different stages of production to determine the effects of processing. The content of vitamin C was measured spectrophotometrically. The total phenolic content was analyzed by using the Folin−Ciocalteu Method, and the amount of total anthocyanins was determined by using the pH-Differential Method. Two different Methodsthe trolox equivalent antioxidant capacity assay and the ferric reducing antioxidant power testwere used to determine the hydrophilic antioxidant capacity. This study showed the decrease of all investigated parameters within processing strawberries to different products. The content of ascorbic acid decreased with production time and processing steps, especially during heat treatment. The investigations on total phenolics in strawberry products proved fining to be a mild Method t...