Carl Sandström

Hierarchical and Heterogeneous Bioinspired Composites—Merging Molecular Self-Assembly with Additive Manufacturing

Biological composites display exceptional mechanical properties owing to a highly organized, heterogeneous architecture spanning several length scales. It is challenging to translate this ordered and multiscale structural organization in synthetic, bulk composites. Herein, a combination of top-down and bottom-up approach is demonstrated, to form a polymer-ceramic composite by macroscopically aligning the self-assembled nanostructure of polymerizable lyotropic liquid crystals via 3D printing. The polymer matrix is then uniformly reinforced with bone-like apatite via in situ biomimetic mineralization. The combinatorial method enables the formation of macrosized, heterogeneous composites where the nanostructure and chemical composition is locally tuned over microscopic distances. This enables precise control over the mechanics in specific directions and regions, with a unique intrinsic-extrinsic toughening mechanism. As a proof-of-concept, the method is used to form large-scale composites mimicking the local nanostructure, compositional gradients and directional mechanical properties of heterogeneous tissues like the bone-cartilage interface, for mechanically stable osteochondral plugs. This work demonstrates the possibility to create hierarchical and complex structured composites using weak starting components, thus opening new routes for efficient synthesis of high-performance materials ranging from biomaterials to structural nanocomposites.

The Swedish Mobile Internet: A Study of Entrepreneurship during 1998-2005

This paper addresses entrepreneurship in the emerging Swedish mobile Internet industry. In this work, the mobile Internet is defined as a function. Entrepreneurship is defined as the creation of a new venture. The unique data set underlying this work consists of 249 ventures that were active in the mobile Internet industry during 1998-2004. The entry/exit pattern and their performance in 2000-2004 were studied along with VC involvement in this industry. On a population level, sales were growing and the number of employees was decreasing. Concerning profits, the population loses enormous amounts of money each year. Venture capital appears to have a rather negative impact on performance initially. However, the VC-backed ventures displayed strong performance improvements at the end of the investigated period.