Understanding the adsorption behavior of heavy oil components on reservoir solids is crucial for improving oil recovery, yet the molecular mechanism remains unclear. This study used molecular dynamics simulations to explore the adsorption kinetics and thermodynamics of asphaltene molecules on silica surfaces. The adsorption process was divided into three stages: free, adsorption, and equilibrium. In the adsorption stage, asphaltenes must pass through two dense hydration layers and adhere to the silica surface in a flat configuration. Carboxyl groups increase asphaltene hydrophilicity, raising interaction energy with water molecules and hindering adsorption. In addition, two distinct hydration layers of water molecules on the silica surface. The first hydration layer, with a peak density of 2000 kg m, was located around 0.6 nm from the surface, driven by hydrogen bonding between Si-OH groups and water molecules. The second layer, found at 1.44-1.80 nm, had a lower density of 1200 kg m, formed through hydrogen bonding between water molecules. This study aims to enhance the understanding of the physicochemical mechanisms governing oil droplet adsorption on silica surfaces, potentially informing the design of improved oil recovery strategies.
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http://dx.doi.org/10.1016/j.jmgm.2024.108897 | DOI Listing |
J Vis Exp
January 2025
Charlottetown Research and Development Center, Agriculture and Agri-Food Canada; Department of Chemistry, University of Prince Edward Island;
The iChip isolation technique uses an in-situ isolation device that increases the cultivability of previously unculturable microorganisms. Microorganisms are an important source of novel chemistries and potentially bioactive molecules. However, only 1% of environmental microorganisms can be cultured using conventional laboratory methods.
View Article and Find Full Text PDFJ Vis Exp
January 2025
Department of Biomedical Engineering, Washington University in St. Louis; Department of Obstetrics & Gynecology, Washington University in St. Louis;
For noninvasive light-based physiological monitoring, optimal wavelengths of individual tissue components can be identified using absorption spectroscopy. However, because of the lack of sensitivity of hardware at longer wavelengths, absorption spectroscopy has typically been applied for wavelengths in the visible (VIS) and near-infrared (NIR) range from 400 to 1,000 nm. Hardware advancements in the short-wave infrared (SWIR) range have enabled investigators to explore wavelengths in the ~1,000 nm to 3,000 nm range in which fall characteristic absorption peaks for lipid, protein, and water.
View Article and Find Full Text PDFLangmuir
January 2025
National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China.
Bacteria have the potential to exhibit divergent stereochemical preferences for different levels of chiral structures, including from molecule, supramolecule, to nanomicroscale helical structure. Accordingly, the structure-activity relationship between chirality and bactericidal activity remains uncertain. In this study, we seek to understand the multivalent molecular chirality effect of chiral supramolecular polymers on antibacterial activity.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Kaiserstraße 12, 76131 Karlsruhe, Germany.
Implicit solvation models permit the approximate description of solute-solvent interactions, where water is the most often considered solvent due to its relevance in biological systems. The use of other solvents is less common but is relevant for applications such as in nuclear magnetic resonance (NMR) or chromatography. As an example, chloroform is commonly used in anisotropic NMR to measure residual dipolar couplings (RDCs) of chiral analytes weakly aligned by an alignment medium.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
School of Chemistry and Chemical Engineering, State Key Laboratory of Metal Matrix Composites, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
Hydrogel-based sensors typically demonstrate conspicuous swelling behavior in aqueous environments, which can severely compromise the mechanical integrity and distort sensing signals, thereby considerably constraining their widespread applicability. Drawing inspiration from the multilevel heterogeneous structures in biological tissues, an antiswelling hydrogel sensor endowed with high strength, rapid self-recovery, and low swelling ratio was fabricated through a water-induced phase separation and coordination cross-linking strategy. A dense heterogeneous architecture was developed by the integration of "rigid" quadridentate carboxyl-Zr coordination bonds and "soft" hydrophobic unit-rich regions featuring π-π stacking and cation-π interactions into the hydrogels.
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