Structural forces play an important role in the rheology, processing and stability of colloidal systems and complex fluids, with polyelectrolytes representing a key class of structuring colloids. Here, we explore the interactions between soft colloids, in the form of air bubbles, in solutions of monodisperse sodium poly(styrene sulfonate) as a model polyelectrolyte. It is found that by self-consistently modelling the force oscillations due to structuring of the polymer chains along with deformation of the bubbles, it is possible to precisely predict the interaction potential between approaching bubbles. In line with polyelectrolyte scaling theory, two distinct regimes of behaviour are seen, corresponding to dilute and semi-dilute polymer solutions. It is also seen that by blending monodisperse systems to give a bidisperse sample, the interaction forces between soft colloids can be controlled with a high degree of precision. At increasing bubble collision velocity, it is revealed that hydrodynamic flow overwhelms oscillatory structural interactions, showing the important disparity between equilibrium behaviour and dynamic interactions.
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http://dx.doi.org/10.1016/j.jcis.2015.03.050 | DOI Listing |
Microsyst Nanoeng
December 2024
ECE Department, University of Alberta, 9211-116 St. NW, Edmonton, T6G 1H9, AB, Canada.
Optomechanical sensors provide a platform for probing acoustic/vibrational properties at the micro-scale. Here, we used cavity optomechanical sensors to interrogate the acoustic environment of adjacent air bubbles in water. We report experimental observations of the volume acoustic modes of these bubbles, including both the fundamental Minnaert breathing mode and a family of higher-order modes extending into the megahertz frequency range.
View Article and Find Full Text PDFJ Med Biochem
September 2024
University of Verona, Section of Clinical Biochemistry and School of Medicine, Verona, Italy.
Background: Minimizing air aspiration by carefully filling blood gas syringes is crucial to prevent air contamination from causing undesirable variations in gasses and other molecules. While some previous studies investigated this aspect, these are now outdated and only analyzed a limited number of blood gas parameters. Thus, we investigated the effects air contamination in the syringe using a modern blood gas analyzer.
View Article and Find Full Text PDFAerosp Med Hum Perform
November 2024
Background: Arterial gas embolism (AGE) may occur while breathing compressed air and failing to exhale during ascent to compensate for gas expansion as pressure decreases. Trauma to the lungs from over-pressurization may result in air bubbles entering the pulmonary veins and subsequently the systemic circulation, causing obstructed blood flow and inflammatory cascades. AGEs are known to always manifest within 10 min of surfacing from depth.
View Article and Find Full Text PDFJ Colloid Interface Sci
December 2024
Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany; Institute of Process Engineering, Technische Universität Dresden, 01069 Dresden, Germany. Electronic address:
Hypothesis: The surface wettability influences the oversaturation-driven growth of gas bubbles on the surface via the contact angle. Larger contact angles on hydrophobic surfaces compared to hydrophilic ones lead to faster growth of bubbles nucleating at microcavities of identical size.
Experiments: Cylindric micro-cavities were etched in silicon wafers as nucleation sites.
Food Chem
December 2024
Amity Institute of Biotechnology, Amity University, Jaipur, Rajasthan, India. Electronic address:
The research on the foaming of semi-solid gel (oleogel) has recently attracted the attention of food scientists owing to its functional characteristics that make it a potential alternative to saturated fat and trans-fat used in food products. The oleofoams are prepared by heating the vegetable oil with an oleogelator followed by cooling to form a semi-solid gel and then incorporating air in the semi-solid gel to form an air-in-oil system having higher stability to deformation. Oleofoams provide new opportunities for the development of novel aerated food products free of saturated and trans fatty acids to meet the growing demand of consumers for healthy foods.
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