Explaining and modeling the concentration and loading of Escherichia coli in a stream-A case study.

Escherichia coli (E. coli) level in streams is a public health indicator. Therefore, being able to explain why E.

Revisiting size-exclusion chromatography for measuring structural changes in raw and pretreated mixed hardwoods and switchgrass.

The study of the biomass porous structure and its role in defining the accessibility of cell-wall-degrading enzymes (CWDEs) to the substrate is very important for understanding the cellulase-cellulose reaction system. Specific pore volume and specific surface area are two important measures of accessibility and a variety of methods have been used to make these measurements. For this study a size exclusion chromatography system was developed to measure specific pore volume and specific surface areas for raw and pretreated mixed-hardwood and switchgrass.

Investigation of the porous structure of cellulosic substrates through confocal laser scanning microscopy.

At the most fundamental level, saccharification occurs when cell wall degrading enzymes (CWDEs) diffuse, bind to and react on readily accessible cellulose fibrils. Thus, the study of the diffusive behavior of solutes into and out of cellulosic substrates is important for understanding how biomass pore size distribution affects enzyme transport, binding, and catalysis. In this study, fluorescently labeled dextrans with molecular weights of 20, 70, and 150 kDa were used as probes to assess their diffusion into the porous structure of filter paper.

Surfactant-mediated control of colloid pattern assembly and attachment strength in evaporating droplets.

This study demonstrates that the pattern assembly and attachment strength of colloids in an evaporating sessile droplet resting on a smooth substrate can be controlled by adding nonionic solutes (surfactant) to the solution. As expected, increasing the surfactant concentration leads to a decrease in initial surface tension of the drop, σ(0). For the range of initial surface tensions investigated (39-72 mN m(-1)), three distinct deposition patterns were produced: amorphous stains (σ(0) = 63-72 mN m(-1)), coffee-ring stains (σ(0) = 48-53 mN m(-1)), and concentric rings (σ(0) = 39-45 mN m(-1)).

A pore-hindered diffusion and reaction model can help explain the importance of pore size distribution in enzymatic hydrolysis of biomass.

Until now, most efforts to improve monosaccharide production from biomass through pretreatment and enzymatic hydrolysis have used empirical optimization rather than employing a rational design process guided by a theory-based modeling framework. For such an approach to be successful a modeling framework that captures the key mechanisms governing the relationship between pretreatment and enzymatic hydrolysis must be developed. In this study, we propose a pore-hindered diffusion and kinetic model for enzymatic hydrolysis of biomass.

Colloid transport and retention in unsaturated porous media: effect of colloid input concentration.

Colloids play an important role in facilitating transport of adsorbed contaminants in soils. Recent studies showed that under saturated conditions colloid retention was a function of its concentration. It is unknown if this is the case under unsaturated conditions.