4_5: BELLOW SPARS - REED LEAF Here the transverse section of a common reed leaf. The two external surfaces, which hold most of the leaf material and the load, are connected by thin spars (actually regularly interrupted by transoms). Beside the nice profile of the leaf, it is interesting to see that the spars are not straight, but curved as a bellow. When the leaf is bent, the spars compress, reducing the leaf thickness and allowing a tighter bent radius than if they were stiff, avoiding a catastrophic buckling. This solution is already in use in many artificial products; for example, the common corrugated cardboard exhibits the same behavior under compression. Extruded polycarbonate panels may benefit from this solution too. Subject: Common massette / reed - Typha latifolia leaf, cross section. Thickness 3mm, width 18mm. Lens: Macro 90mm f/something Theme 4: TOUGHNESS OF COMPOSITES Development of artificial composite materials is today in a golden age; the extreme strength of artificial fibers allows us to fabricate new materials with unprecedented performances. However, when it comes to impact resistance, toughness and flexibility, we still have to rely on bulk materials like metals, plastics and elastomers. Our composites are not yet mature, performing way below the potential of their constituents. The positioning of the reinforcement fibers, their interlocking, the adhesion with the matrix, the control of cracks growth, those are the critical factors that can and need to be improved. Biological tissues instead, being built up from the molecular level, show an high degree of refinement in their micro and mesoscopic structure, resulting in lightweight and extremely tough materials. The images presented try to convey in a visual manner some solutions hidden in natural materials on how they fail progressively while holding structural integrity. AUTHOR PRESENTATION My name is Giorgio Pattarini, am an applied physicist born in Italy and currently living in Norway. I am passionate about the mesoscopic world and its enormous variety of forms, being mineral, biological or artificial. Favourite themes are metallic coatings and rusting, mechanical design optimization, muds and soft matter, our meaning in the world, small critters and functional textures. I use photography as a tool to illustrate the enormously complex beauty of our world; a lot of work on the optics side, with the main focus on obtaining a clear illustration of the phenomenon of study. PROJECT MOTIVATION I acquired in October 2020 two large lenses originally manufactured by SAGEM, now Safran. I looked on the net to find what was their application, but what I found instead was the Mimesis contest. I really liked the theme since in most of my work, I do mimesis all the time: to solve a new problem I typically look for (and find) existing solutions from different fields. I believe we still have a lot to learn from the vast mass of engineering produced by biological evolution. All photos have been shot by the author in Stavanger, Norway, between October 26 and November 4 2020, specifically for the Mimesis contest. I strived to seek innovative content and hope some images will provide inspiration for new technological implementations. I don’t have the patience or money to go hunting for the most bizarre insects in tropical forests (and anyway we are all quarantined), so most of the images are from common life forms and products that can be readily found in the house or in city parks. The amount of treasures hidden under our nose is amazing. The SAGEM lenses, mounted on a custom made bellows rail, have been used in four of the images; the rest are with commercial macro or wide camera lenses. One image (Fly eye in subjective) has been taken with another optical system built for the purpose. Between the many ideas at the beginning, four themes have been developed: 1 - Exagon +/- epsilon - 6 images 2 - One specific animal - 4 images 3 - Autumn colors - 3 images 4- Toughness of composites - 5 images Wish to thank: Joanna Tatusko, the hands and eye model; as well as critical steering about lightning and shoots selection. Anke from Astrooptik DE, provided the initial motivation with the two Sagem lenses. Participants of the forum binomania.it for the insect eye shot inspiration. Svithun Husflidslaget Stavanger NO, preparation of the samples.