An aggregate is a group of primary particles that cohere to each other more strongly than to other surrounding soil particles. Most adjacent particles adhere to some degree. Therefore, disintegration of the soil mass into aggregates requires imposition of a disrupting force. Stability of aggregates is a function of whether the cohesive forces between particles withstand the applied disruptive f...

A novel aggregation-based biosensing method to achieve detection of oligonucleotides in a pinched-flow fractionation (PFF) microseparator was developed. Employing functionalized polystyrene microspheres, this method is capable of the direct detection of the concentration of a specific DNA sequence. The label-free target DNA hybridizes with probe DNA of two kinds on the surface of the microspher...

We calculate the average hydrodynamic stress on fractal aggregates of spheres using Stokesian dynamics. We find that for fractal aggregates of force-free particles, the stress does not grow as the cube of the radius of gyration, but rather as the number of particles in the aggregate. This behavior is only found for random aggregates of force-free particles held together by hydrodynamic lubricat...

In October 2011 the European Commission published its recommendation on a common definition of the term “nanomaterial” for regulatory purposes. According to this recommendation, a nanomaterial is a natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and where, for 50% or more of the particles in the number size distribut...

In many exposure environments, capillary absorption of water controls the rate of deterioration of concrete. This paper presents a three-dimensional numerical investigation of capillary absorption by treating concrete as a heterogeneous composite discretised into a cubic lattice. The lattice elements were considered as conductive "pipes" with transport properties assigned based on the phase the...

Two groups of aggregates with fractal dimensions of 1.81 ( 0.09 and 2.33 ( 0.07 were generated by coagulation of latex microspheres (2.84 μm) in a Jar-test (paddle-mixing) device. The collision rates between these fractal aggregates (200-1000 μm) and small (1.48 μm) particles were measured for individual aggregates that had settled through a suspension of the small particles. Aggregate permeabi...