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Mechanical engineering curriculums at German universities have mostly theoretical approaches to design theory. Several institutes and chairs have specialized courses regarding this topic, but these are seldomly integrated. The approach IDEE – Integrated Design Engineering Education – brings the specialized fields on design theory together in one course with a highly practical focus at the beginning of the mechanical engineering studies. This is realized by a mixture of theoretical lectures and a group project. For students, this includes their first experience of a complex group project with peers and also the first oral presentation in an engineering context. With a lack of professional and soft skills, there is often friction inside groups. There is also a need for appropriate tools to work collaboratively. Due to the Corona pandemic, lectures and the group project must be held completely online. This paper describes our approach in helping the students improve their professional and personal skills by integrating new courses within the project, monitor their group dynamics, and also use digitization to provide an online-only solution. This paper presents the challenges regarding soft skills and collaborative work as well as the chosen approach on how to integrate digitization, monitoring, and self-organization skills into the lecture to face the challenges.

Nacre of abalone shells consists of aragonite platelets and organic material, the so-called organic matrix. During the growth process of the shell the aragonite platelets grow into a scaffold formed by the organic matrix. In this work we tried to mimic this growth process by placing a piece of the insoluble organic matrix (which is a part of the organic matrix) of the abalone Haliotis laevigata in a crystallization device which was flowed through by CaCl 2 and NaHCO 3 solutions. Using this setup amongst others flat aragonite crystals grow on the insoluble organic matrix. When investigating these crystals in a transmission electron microscope it is possible to recognize similarities to the structure of nacre, like the formation of mineral bridges and growth between layers of the insoluble organic matrix. These similarities are presented in this paper.

During the growth process of the nacre layer in abalone shells, aragonite platelets are built into a preformed organic matrix. This matrix consists of chitin and different proteins that may affect ...

Nacre, the inner iridescent layer of mollusc shells, is a typical example of a material that is formed by such biomineralization processes. Nacre is composed of the CaCO3-polymorph aragonite and a small amount (about 5 wt.%) of organic matter. The authors studied the structure of the aragonite platelets of Haliotis laevigata nacre, using conventional transmission electron microscopy, Z-contrast, electron tomography, energy-dispersive X-ray analysis (EDX)and electron energy-loss spectroscopy (EELS). The authors observed faceted voids several nanometers wide within the aragonite platelets. The electron tomography investigations showed that the voids are distributed more or less randomly in the studied specimen and allowed an estimation of the order of magnitude of the width and the volumetric content of the voids. The voids are located within the aragonite platelets, so that they are not an artifact of preparation. Furthermore, a first proposal for a three-dimensional model of the voids was made. EDX and EELS measurements revealed that the voids include a larger amount of carbon in comparison to the bulk material. The questions why these voids are formed and how have still to be answered. A speculative function of the voids could be the decreased propagation of cracks in the shell providing an increased fracture toughness.

In this work, we studied the correlation of the orientation of stacked aragonite platelets of Haliotis laevigata nacre, using selected area diffraction (SAD) in transmission electron microscopy (TEM). From the position of the center of Laue circle (COLC) within the diffraction patterns the tilt angles of the investigated platelets relatively to a reference platelet (oriented in zone axis) are determined. The strong correlation of the platelets supports the existence of mineral bridges, which connect the stacked platelets and enable a transfer of the platelet orientation during growth. Electron tomography and subsequent reconstruction of the obtained data yield information about the shape of the mineral bridges. The crystalline structure of the material within the mineral bridges was investigated by high resolution TEM (HRTEM).

Nacre of the mollusc Haliotis laevigata was investigated using transmission electron microscopy (TEM). Nacre, the inner iridescent layer of mollusc shells, is a typical example for a material which is formed by biomineralization processes. It is composed of the CaCO3-polymorph aragonite and a small amount of about 5wt% organic matter [1]. The polygonal shaped aragonite platelets show a width which ranges from 5µm to 10µm and a thickness of about 500nm [2]. They are laterally arranged in layers and vertically in stacks. The aragonite crystal structure can be described by the space group Pmcn 62 with the c-axis perpendicular to the face of the platelets and thus to the surface of the shell [3]. The platelets are separated by layers of organic material, the organic matrix. This arrangement resembles a brick and mortar like structure. The combination of stiff crystalline material and soft organic material, as well as the layered structure increase the fracture toughness in comparison with pure (geological) aragonite.

* Forschungszentrum Karlsruhe, Institute for Nanotechnology, 76344 Eggenstein-Leopoldshafen, Germany ** Fraunhofer IFAM, Wiener Strase 12, 28355 Bremen, Germany *** University of Bremen, Institute of Biophysics, Otto-Hahn-Allee 1, 28359 Bremen, Germany **** The University of York, Department of Physics, Heslington, York YO10 5DD, United Kingdom ***** University of Bremen, Institute for Solid State Physics, Otto-Hahn-Allee 1, 28359 Bremen, Germany