Hindwings of insects as concept generator for hingeless foldable shading systems.

Hingeless shading systems inspired by nature are increasingly the focus of architectural research. In contrast to traditional systems, these compliant mechanisms can reduce the amount of maintenance-intensive parts and can easily be adapted to irregular, doubly curved, facade geometries. Previous mechanisms rely merely on the reversible material deformation of composite structures with almost homogeneous material properties. This leads to large actuation forces and an inherent conflict between the requirements of movement and the capacity to carry external loads. To enhance the performance of such systems, current research is directed at natural mechanisms with concentrated compliance and distinct hinge zones with high load-bearing capacity. Here, we provide insights into our biological findings and the development of a deployable structure inspired by the Flexagon model of hindwings of insects in general and the hierarchical structure of the wing cuticle of the shield bug (Graphosoma lineatum). By using technical fibre-reinforced plastics in combination with an elastomer foil, natural principles have been partially transferred into a multi-layered structure with locally adapted stiffness. Initial small prototypes have been produced in a vacuum-assisted hot press and sustain this functionality. Initial theoretical studies on test surfaces outline the advantages of these bio-inspired structures as deployable external shading systems for doubly curved facades.

Flectofin: a hingeless flapping mechanism inspired by nature.

This paper presents a novel biomimetic approach to the kinematics of deployable systems for architectural purposes. Elastic deformation of the entire structure replaces the need for local hinges. This change becomes possible by using fibre-reinforced polymers (FRP) such as glass fibre reinforced polymer (GFRP) that can combine high tensile strength with low bending stiffness, thus offering a large range of calibrated elastic deformations. The employment of elasticity within a structure facilitates not only the generation of complex geometries, but also takes the design space a step further by creating elastic kinetic structures, here referred to as pliable structures. In this paper, the authors give an insight into the abstraction strategies used to derive elastic kinetics from plants, which show a clear interrelation of form, actuation and kinematics. Thereby, the focus will be on form-finding and simulation methods which have been adopted to generate a biomimetic principle which is patented under the name Flectofin®. This bio inspired hingeless flapping device is inspired by the valvular pollination mechanism that was derived and abstracted from the kinematics found in the Bird-Of-Paradise flower (Strelitzia reginae, Strelitziaceae).

Phosphorylation-activity relationships of AMPK and acetyl-CoA carboxylase in muscle.

AMP-activated protein kinase (AMPK) is activated during muscle contraction in response to the increase in AMP and decrease in phosphocreatine (PCr). Once activated, AMPK has been proposed to phosphorylate a number of targets, resulting in increases in glucose transport, fatty acid oxidation, and gene transcription. Although it has been possible to directly observe phosphorylation of one of these targets, acetyl-CoA carboxylase (ACC) in vitro, it has been more difficult to obtain direct evidence of ACC phosphorylation in contracting skeletal muscle. In these experiments using a phosphoserine antibody to ACC and a phosphothreonine antibody to AMPK, evidence was obtained for phosphorylation and activation of ACC in vitro, in gastrocnemius muscle electrically stimulated at different frequencies, and in muscle from rats running on the treadmill. Significant negative linear correlations between phospho-ACC and ACC activity were observed in all models (P < 0.01). The decline in ACC activity was related to the decrease in PCr and the rise in AMP. A relationship between phospho-AMPK (threonine 172) and activity of AMPK immunoprecipitated with anti-alpha(2) subunit antibody preparation was also observed. These data provide the first evidence of a direct link between extent of phosphorylation of these proteins at sites recognized by the antibodies and activity of the enzymes in electrically stimulated muscle and in muscle of rats running on the treadmill.