Magnetic resonance imaging (MRI) has tremendous potential for revealing transport processes in engineered and geologic systems. Here, we utilize MRI to image nanoparticle (NP) transport through a saturated coarse-grained system. Commercially available paramagnetically tagged NPs are used; the paramagnetic tag making the NP visible to MRI. NP transport was imaged as NPs migrated through packed c...

The hydrophobic flocculation of galena fines induced by potassium amyl xanthate (PAX) in aqueous suspensions has been studied using laser diffraction, electrophoretic light scattering, contact angle, and microflotation measurements. The measurements were performed on <2 µm, 2-5 µm, 5-10 µm, and <30 µm size galena by varying several parameters, including PAX concentration, pH, original particle ...

Hydrogels formed from the self-assembly of oligopeptides are being extensively studied for biomedical applications. The kinetics of their gelation, as well as a quantitative description of the forces controlling the rate of assembly has not yet been addressed. We report here the use of multiple particle tracking to measure the self-assembly kinetics of the model peptide FKFEFKFE (KFE8). KFE8 fo...

Aggregation of sub-micron and nano-sized polystyrene latex particles was studied in room temperature ionic liquids (ILs) and in their water mixtures by time-resolved light scattering. The aggregation rates were found to vary with the IL-to-water molar ratio in a systematic way. At the water side, the aggregation rate is initially small, but increases rapidly with increasing IL content, and reac...

Nanoscale zerovalent iron (NZVI) rapidly transforms many environmental contaminants to benign products and is a promising in-situ remediation agent. To be effective, NZVI should form stable dispersions in water such that it can be delivered in water-saturated porous media to the contaminated area. Limited mobility of NZVI has been reported, however, attributed to its rapid aggregation. This stu...

Hofmeister effects have been recognized as important as Mendel's work was to genetics while remain largely controversial, especially for the mechanistic aspects. Here we demonstrated that complex colloids in electrolyte solutions show resembling aggregation kinetics as model colloid, and then quantitatively evaluated the resulting Hofmeister effects. Mechanism for the aggregation of complex col...

Atomic force microscopy is one of the few techniques that allow analysis of biological recognition processes at the single-molecule level. A major limitation of this approach is the nonspecific interaction between the force sensor and substrate. We have modeled the nonspecific interaction by looking at the interaction potential between a conical Si3N4 tip with a spherical end face and a mica su...

At the nanoscale level biological membranes present a complex interface with the solvent. The functional dynamics and relative flexibility of membrane components together with the presence of specific ionic effects can combine to create exciting new phenomena that challenge traditional theories such as the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory or models interpreting the role of ions in...