OBJECTIVE: Once penetrated into the stratum corneum, anionic surfactants bind to and denature stratum corneum proteins as well as intercalate into and extract intercellular lipids. With repeated exposures, this leads to skin dryness and irritation, compromising barrier function and skin health. The mechanisms of anionic surfactant penetration into the skin, however, are still widely debated. The objective of this study was to evaluate current theories of surfactant penetration into human skin. METHODS: A test set comprising 15 anionic surfactant systems and one non-ionic surfactant, all having either dodecyl or lauryl alkyl chains, was tested for surfactant penetration into split-thickness human cadaver skin in vitro using radiolabelled sodium dodecyl sulphate ( 14 C-SDS). Select physical properties of these formulations thought to be associated with skin penetration including critical micelle concentration, micelle diameter, filtrate concentration and zeta potential were also measured. RESULTS: 14 C-SDS penetration into human cadaver skin from surfactant systems in vitro was found to correlate well with CMC (R 2 = 0.34, P < 0.05), filtrate concentration (R 2 = 0.36, P < 0.05) and zeta potential (R 2 = 0.76, P < 0.001), but poorly with micelle diameter (R 2 = 0.12). Furthermore, the latter measure correlated inversely with penetration compared to what would be expected based on the micelle penetration theory. CONCLUSION: Neither monomer nor micelle penetration theories are sufficient to explain anionic surfactant penetration into human skin. Submicellar (or premicellar) aggregate penetration theory is difficult to defend at relevant surfactant concentrations. We propose a new hypothesis for this mechanism in which short-term penetration is based on monomer concentration and longer term penetration is based on surfactant-induced damage to the skin barrier.

The Membrane Optical Imager Real-time Exploitation (MOIRE) program, being developed by BallAerospace and its partners for the Defense Advanced Research Projects Agency (DARPA), seeks to enable technologies that would make orbital telescopes much lighter, more transportable and more cost-effective. MOIRE intends to design and develop a geosynchronous imager featuring a 10-meter diameter membrane optical element system at a distance 50 meters away from the spacecraft bus, with traceability to a future system with a 20-meter diameter primary optic. The program is preparing for a potential future space-based mission through large-scale, ground-based testing. Full-scale deployment testing of two petal segments combined with quarter-scale testing of a full system demonstrated feasibility of the 10-meter primary diameter design. This paper discusses the design, analysis and testing of the primary optic's structural elements.

The views expressed are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government.The MOIRE optical space system, being designed by Ball Aerospace and its partners for DARPA, is a gossamer structure featuring a 10 meter diameter membrane optical element at a distance 50 meters away from the spacecraft bus. The proposed design has traceability to a system with a 20 meter diameter primary optic. As the critical technology of the program, the membrane has received significant analysis and testing time. This paper discusses several challenges and some of the unique solutions and capabilities that Ball Aerospace and its partners are providing.

Aerospace and its partners for the Defense Advanced REDARPA, is the Defense Advanced Research ProjectsAgency (DARPA), seeks to enable technologies that would make orbital telescopes much lighter, more transportable and more cost-effective. MOIRE intends to design and develop a geosynchronous imager featuring a 10-meter diameter membrane optical element system at a distance 50 meters away from the spacecraft bus, with traceability to a future system with a 20-meter diameter primary optic. The program is preparing for a potential future space-based mission through large-scale, ground-based testing. Due to the overall system size, subsystem and component level testing is necessary to capture data for incorporation into larger analysis models. Stability testing of two full-scale composite strongback segments, including in a relevant environment, was performed to correlate preliminary models of the primary diffractive optical element structure. This paper discusses the testing approach and lessons learned.