The Experts below are selected from a list of 50040 Experts worldwide ranked by ideXlab platform

K. Roth - One of the best experts on this subject based on the ideXlab platform.

  • Do effective properties for unsaturated weakly Layered porous media exist? An experimental study
    Hydrology and Earth System Sciences Discussions, 2005
    Co-Authors: A. Bayer, H.-j. Vogel, O. Ippisch, K. Roth
    Abstract:

    In a multi-step outflow experiment we found that a weak heterogeneity within a sand column prevents the estimated effective hydraulic parameters from being unique. We compared vertical water content profiles calculated from these parameters with profiles measured by x-ray attenuation. A Layered Material model based on x-ray data was able to reproduce the outflow curve and also the water content distribution inside the column. We also calculated effective parameters for the Layered model turned upside down and obtained large differences to the set of values of the original sample.

  • Do effective properties for unsaturated weakly Layered porous media exist? An experimental study.
    Hydrology and Earth System Sciences Discussions, 2005
    Co-Authors: A. Bayer, H.-j. Vogel, O. Ippisch, K. Roth
    Abstract:

    In a multi-step outflow experiment we found that a weak heterogeneity within a sand column prevents the estimated effective hydraulic parameters from being objective. We compared vertical water content profiles calculated from these parameters with profiles measured by X-ray attenuation. A Layered Material model based on X-ray data was able to reproduce the outflow curve and also the internal behavior of the column. We also calculated effective parameters for the heterogeneous model turned upside down and obtained large differences to the set of values of the original sample.

Evan J. Reed - One of the best experts on this subject based on the ideXlab platform.

  • Microscopic Origins of the Variability of Water Contact Angle with Adsorbed Contaminants on Layered Materials
    The Journal of Physical Chemistry C, 2018
    Co-Authors: Yao Zhou, Evan J. Reed
    Abstract:

    Significant variations in the literature reports of water contact angles on Layered Materials have been interpreted to suggest that the wettability of Layered Materials can be very sensitive to contamination in an ambient environment. However, the theoretical potential for contamination to account for this variation has yet to be quantitatively fully explored. To address this gap, we combined a Lifshitz-based contact angle model with density functional theory calculations of optical properties to study the wettability of graphite and MoS2. We first demonstrated the layer dependence and substrate dependence of wettability. We find that the contact angle generally decreases with increasing number of layers for a suspended Layered Material, whereas for a Layered Material on a substrate, the contact angle change depends on the dielectric functions of both the Layered Material and the substrate. Then, to study in depth the effect of contamination, we considered a spectrum of potential contaminating molecules i...

  • Microscopic Origins of the Variability of Water Contact Angle with Adsorbed Contaminants on Layered Materials C
    The Journal of Physical Chemistry, 2018
    Co-Authors: Yao Zhou, Evan J. Reed
    Abstract:

    Significant variations in the literature reports of water contact angles on Layered Materials have been interpreted to suggest that the wettability of Layered Materials can be very sensitive to contamination in an ambient environment. However, the theoretical potential for contamination to account for this variation has yet to be quantitatively fully explored. To address this gap, we combined a Lifshitz-based contact angle model with density functional theory calculations of optical properties to study the wettability of graphite and MoS₂. We first demonstrated the layer dependence and substrate dependence of wettability. We find that the contact angle generally decreases with increasing number of layers for a suspended Layered Material, whereas for a Layered Material on a substrate, the contact angle change depends on the dielectric functions of both the Layered Material and the substrate. Then, to study in depth the effect of contamination, we considered a spectrum of potential contaminating molecules in air, including N₂, O₂, CO₂, CH₄, and 1-octadecene. Specifically, our results show that contamination between the liquid and Layered Material leads to significantly larger changes in contact angle than contaminants that are intercalated within the Layered Material. We find that Layered Materials generally appear more hydrophobic after contamination. Our model has potential application of guiding the design of more hydrophobic Layered Materials. In contrast to other common Lifshitz approaches, these conclusions are independent of any fitting to experimental contact angle results.

A. Bayer - One of the best experts on this subject based on the ideXlab platform.

  • Do effective properties for unsaturated weakly Layered porous media exist? An experimental study
    Hydrology and Earth System Sciences Discussions, 2005
    Co-Authors: A. Bayer, H.-j. Vogel, O. Ippisch, K. Roth
    Abstract:

    In a multi-step outflow experiment we found that a weak heterogeneity within a sand column prevents the estimated effective hydraulic parameters from being unique. We compared vertical water content profiles calculated from these parameters with profiles measured by x-ray attenuation. A Layered Material model based on x-ray data was able to reproduce the outflow curve and also the water content distribution inside the column. We also calculated effective parameters for the Layered model turned upside down and obtained large differences to the set of values of the original sample.

  • Do effective properties for unsaturated weakly Layered porous media exist? An experimental study.
    Hydrology and Earth System Sciences Discussions, 2005
    Co-Authors: A. Bayer, H.-j. Vogel, O. Ippisch, K. Roth
    Abstract:

    In a multi-step outflow experiment we found that a weak heterogeneity within a sand column prevents the estimated effective hydraulic parameters from being objective. We compared vertical water content profiles calculated from these parameters with profiles measured by X-ray attenuation. A Layered Material model based on X-ray data was able to reproduce the outflow curve and also the internal behavior of the column. We also calculated effective parameters for the heterogeneous model turned upside down and obtained large differences to the set of values of the original sample.

Yao Zhou - One of the best experts on this subject based on the ideXlab platform.

  • Microscopic Origins of the Variability of Water Contact Angle with Adsorbed Contaminants on Layered Materials
    The Journal of Physical Chemistry C, 2018
    Co-Authors: Yao Zhou, Evan J. Reed
    Abstract:

    Significant variations in the literature reports of water contact angles on Layered Materials have been interpreted to suggest that the wettability of Layered Materials can be very sensitive to contamination in an ambient environment. However, the theoretical potential for contamination to account for this variation has yet to be quantitatively fully explored. To address this gap, we combined a Lifshitz-based contact angle model with density functional theory calculations of optical properties to study the wettability of graphite and MoS2. We first demonstrated the layer dependence and substrate dependence of wettability. We find that the contact angle generally decreases with increasing number of layers for a suspended Layered Material, whereas for a Layered Material on a substrate, the contact angle change depends on the dielectric functions of both the Layered Material and the substrate. Then, to study in depth the effect of contamination, we considered a spectrum of potential contaminating molecules i...

  • Microscopic Origins of the Variability of Water Contact Angle with Adsorbed Contaminants on Layered Materials C
    The Journal of Physical Chemistry, 2018
    Co-Authors: Yao Zhou, Evan J. Reed
    Abstract:

    Significant variations in the literature reports of water contact angles on Layered Materials have been interpreted to suggest that the wettability of Layered Materials can be very sensitive to contamination in an ambient environment. However, the theoretical potential for contamination to account for this variation has yet to be quantitatively fully explored. To address this gap, we combined a Lifshitz-based contact angle model with density functional theory calculations of optical properties to study the wettability of graphite and MoS₂. We first demonstrated the layer dependence and substrate dependence of wettability. We find that the contact angle generally decreases with increasing number of layers for a suspended Layered Material, whereas for a Layered Material on a substrate, the contact angle change depends on the dielectric functions of both the Layered Material and the substrate. Then, to study in depth the effect of contamination, we considered a spectrum of potential contaminating molecules in air, including N₂, O₂, CO₂, CH₄, and 1-octadecene. Specifically, our results show that contamination between the liquid and Layered Material leads to significantly larger changes in contact angle than contaminants that are intercalated within the Layered Material. We find that Layered Materials generally appear more hydrophobic after contamination. Our model has potential application of guiding the design of more hydrophobic Layered Materials. In contrast to other common Lifshitz approaches, these conclusions are independent of any fitting to experimental contact angle results.

H.-j. Vogel - One of the best experts on this subject based on the ideXlab platform.

  • Do effective properties for unsaturated weakly Layered porous media exist? An experimental study
    Hydrology and Earth System Sciences Discussions, 2005
    Co-Authors: A. Bayer, H.-j. Vogel, O. Ippisch, K. Roth
    Abstract:

    In a multi-step outflow experiment we found that a weak heterogeneity within a sand column prevents the estimated effective hydraulic parameters from being unique. We compared vertical water content profiles calculated from these parameters with profiles measured by x-ray attenuation. A Layered Material model based on x-ray data was able to reproduce the outflow curve and also the water content distribution inside the column. We also calculated effective parameters for the Layered model turned upside down and obtained large differences to the set of values of the original sample.

  • Do effective properties for unsaturated weakly Layered porous media exist? An experimental study.
    Hydrology and Earth System Sciences Discussions, 2005
    Co-Authors: A. Bayer, H.-j. Vogel, O. Ippisch, K. Roth
    Abstract:

    In a multi-step outflow experiment we found that a weak heterogeneity within a sand column prevents the estimated effective hydraulic parameters from being objective. We compared vertical water content profiles calculated from these parameters with profiles measured by X-ray attenuation. A Layered Material model based on X-ray data was able to reproduce the outflow curve and also the internal behavior of the column. We also calculated effective parameters for the heterogeneous model turned upside down and obtained large differences to the set of values of the original sample.