We have investigated the wetting phenomena of two underliquid systems, i.e., oil (drop) in water medium and water (drop) in oil medium for two different substrates, poly(methyl methacrylate) (PMMA) and glass. We have conducted detailed static (equilibrium) and dynamic contact angle measurements of drops on substrates kept in air, water, and oils of varying densities, viscosities, and surface tensions. We compared the experimentally observed contact angles with those predicted by the conventional wetting theories, namely, Young's equation and the Owens and Wendt approach. The results reported herein showed that experimental values vary in the range of 8-20% with the conventional theoretical model for water (drop) in oil (viscous surrounding medium) on PMMA substrate. However, oil (drop) in water medium on PMMA does not show such an anomaly. By taking into consideration a thin oil film between a water drop and PMMA originating from the surrounding oil medium, the modified Young's equation is proposed here. We found that the percentage difference between experimentally observed contact angles with modified Young's equation is in the range of 0.88-5.88%, which is very less compared to percentage difference with classic Young's equation. For glass substrates, the standard Young's equation does not translate to the underliquid systems whereas the Owens and Wendt theory could not correctly predict the underliquid contact angles. However, the modified Young's equation with thin-film consideration agrees very well with the experimental values and thereby demonstrated the presence of a thin film between a drop and glass substrate originating from the surrounding viscous medium. This present experimental study coupled with detailed theoretical analyses demonstrates the anomalous wetting signature of drops on substrates submerged in surrounding viscous medium, which is very different from the reported studies for drops on substrates kept in air (inviscid medium).
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http://dx.doi.org/10.1021/acs.langmuir.8b02569 | DOI Listing |
Micron
December 2024
School of Sciences, European University Cyprus, Nicosia 2404, Cyprus. Electronic address:
Atomic Force Microscopy (AFM) nanoindentation is the most effective method for determining the mechanical properties of soft biological materials and biomaterials at the nanoscale, with significant applications in many areas, including cancer diagnosis. However, a major drawback of this method is the complexity of the experimental procedure and data processing, which requires several calibration steps.To avoid this complexity, the AFM tip is usually approximated as a perfect cone.
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British Columbia Centre on Substance Use, 1045 Howe St Suite 400, Vancouver, British Columbia V6Z 2A9, Canada; Interdepartmental Division of Addiction Medicine, St. Paul's Hospital, 1081 Burrard Street, Vancouver, British Columbia, V6Z 1Y6.
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Public Health Nutr
January 2025
Department of Anthropology and Institute for Policy Research, Northwestern University, Evanston, IL, USA.
Objective: Explore the relationship between water insecurity and food security and their covariates in Mexican households.
Design: A cross-sectional study with nationally representative data from the National Health and Nutrition Survey-Continuous 2021 (in Spanish, ENSANUT-Continua 2021), collected data from 12,619 households.
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Heliyon
May 2024
Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, Kashan, P.O. Box 87317-53153, Iran.
Osteoarthr Cartil Open
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Department of Orthopedic Surgery, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA.
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