An investigation of the boundary layer viscosity of films of non-polar liquid lubricants, hexadecane and a silicone oil, octamethyl-cyclotetrasiloxane, confined between parallel atomically smooth single crystals of muscovite mica, is reported. The effective viscosity (eta(eff)) showed a zone of linear response and a second zone of extreme shear thinning. In the zone of linear response, eta(eff) increased exponentially with increasing net normal pressure, increasing from 250 to 2200 poises as the pressure was raised from 0.03 to 0.15 MPa. However, very large shear thinning (decay by more than one order of magnitude) was observed as the effective shear rate was varied from 1 sec-1 to 10(4) sec-1, and the transition to glassy solid response (critical shear stress behavior) was impeded by continuous shear. These experiments show that the rheology of a lubricant within a zone of contact can be strikingly different from that in the bulk. Possible engineering applications of these findings are discussed.

A method is described to deposit a securely attached, self-assembled monolayer of octadecyltrichlorosilane (OTS) on the surface of freshly cleaved muscovite mica. Comparison of the infrared methylene spectra with those of closely packed Langmuir-Blodgett films implies that the surface coverage of the OTS films was a fraction 0.8–0.9 that of films formed by Langmuir-Blodgett (LB) methods. However, LB monolayers are less securely attached to the substrate. The contact angle of water on these self-assembled monolayers remained over 100° for over 24 h and it suffered no noticeable degradation after prolonged reflux in cyclohexane. The method to form an OTS monolayer on mica involves three steps; first, ion exchange of the native K+ ions of cleaved mica for H+ ions; second, control of the quantity of resulting water on the mica surface; third, adsorption and surface polymerization of octadecyltrichlorosilane (OTS) by self-assembly from dilute cyclohexane solution.

A method is described for obtaining infrared spectra of an organic monolayer film on muscovite mica. This task is normally difficult because mica is not metallic, and it has biaxial optical properties and produces large interference fringes when analyzed in transmission or reflection because of reflections off the front and back of a sheet. The method involves the transmission of parallel-polarized light, incident at the Brewster's angle, through a mica sheet that is oriented along one of its principal optical directions.

A technique is described for micropositioning a surface forces apparatus with low mechanical and thermal drift. The technique is less exacting and more stable than competing ones.

Twenty-five workers in an egg-processing factory were evaluated for respiratory sensitization to inhaled egg proteins by a physician evaluation, serial peak expiratory flow rate (PEFR) measurements for a 1-week period, and immunologic tests. Immunologic studies included skin prick tests, serum-specific IgE (RAST), and specific IgG (ELISA) to solutions prepared from commercial food allergens: factory-powdered egg white and yolk products and purified egg white fractions, including ovalbumin, ovomucoid, lysozyme, and conalbumin. Six workers had significant daily PEFR lability (greater than 20%) of whom five had associated cutaneous reactivity to at least one egg allergen. A diagnosis of "definite asthma" was established in five workers suspected by the physician of having asthma. These five workers exhibited significant decrements in daily PEFR that were accompanied by bronchial symptoms. Occupational asthma was diagnosed by the physician in four of the five latter workers. Definite asthma was significantly associated with both cutaneous reactivity to egg allergens (p less than 0.01) and RAST binding (p less than 0.01). Of eight workers with cutaneous reactivity to at least one egg reagent, four workers (50%) were positive to only purified egg white fractions. The highest levels of RAST binding were detected in four workers, and the best binding activity was to ovomucoid and ovalbumin fractions. Elevated specific IgG responses were significantly higher in egg-factory workers to whole egg (p less than 0.005), lysozyme (p less than 0.002), and conalbumin (p less than 0.002) allergens compared to responses of nonexposed control subjects. However, no differences in specific IgG were detected between symptomatic and asymptomatic workers.(ABSTRACT TRUNCATED AT 250 WORDS)