An investigation of gecko attachment on wet and rough substrates leads to the application of surface roughness power spectral density analysis.

The roughness and wettability of surfaces exploited by free-ranging geckos can be highly variable and attachment to these substrates is context dependent (e.g., presence or absence of surface water).

Influence of substrate modulus on gecko adhesion.

The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system's performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves.

Gecko Adhesion on Wet and Dry Patterned Substrates.

Perhaps one of the most astounding characteristics of the gecko adhesive system is its versatility. Geckos can locomote across complex substrates in a variety of conditions with apparent ease. In contrast, many of our synthetic pressure sensitive adhesives fail on substrates that are dirty, wet or rough.

Measurement of transferable chemical residue from nylon carpet using the California roller and a new mega-California roller.

Human chemical exposures resulting from transfer of surface deposition on indoor nylon carpets may be estimated by measuring transferable residues (mu g chemical/cm2 carpet). A weighted roller developed at California Department of Food and Agriculture (CDFA) has been extensively used to sample transferable residue for estimates of human exposure in risk characterization. A modified roller has been developed to evaluate the influence of pressure on transferable chemical residue since weight and force (or pressure, kg/m2) may vary person-to-person and activity-to-activity.

Surface-to-food pesticide transfer as a function of moisture and fat content.

Transfer of pesticides from household surfaces to foods may result in excess dietary exposure in children (i.e., beyond that inherent in foods due to agricultural application).

Sampling household surfaces for pesticide residues: comparison between a press sampler and solvent-moistened wipes.

A modified Press Sampler was evaluated to determine the efficiency of pesticide transfer from household surfaces to collection disks as compared to wiping with a solvent-moistened gauze pad. Organophosphate (OP), pyrazole, and pyrethroid pesticides were applied to three hard flooring materials and carpet at two loading rates. Surfaces were dried and press sampled using C(18), 100% cotton or polyurethane foam (PUF) for either 2 or 10 min or wiped with isopropanol-moistened gauze pads.

Human exposure to indoor residential cyfluthrin residues during a structured activity program.

Estimations of absorbed daily dosage (ADD) of chemicals following contact with treated surfaces may be required for risk assessment and risk management. Measurements of ADD based upon biomonitoring are a more reliable data than estimates of ADD from environmental measurements since they require fewer default assumptions. Study participants performed a structured activity program (SAP) 24-h after an application of Tempo((R)) 20 WP (cyfluthrin; 3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropanecarboxylic acid cyano(4-fluoro-3-phenoxy-phenyl)-methyl ester) on a medium pile, plush nylon carpet.