The technologies employed for the preparation of conventional tissue engineering scaffolds restrict the materials choice and the extent to which the architecture can be designed. Here we show the versatility of stereolithography with respect to materials and freedom of design. Porous scaffolds are designed with computer software and built with either a poly(D,L-lactide)-based resin or a poly(D,L-lactide-co-epsilon-caprolactone)-based resin. Characterisation of the scaffolds by micro-computed tomography shows excellent reproduction of the designs. The mechanical properties are evaluated in compression, and show good agreement with finite element predictions. The mechanical properties of scaffolds can be controlled by the combination of material and scaffold pore architecture. The presented technology and materials enable an accurate preparation of tissue engineering scaffolds with a large freedom of design, and properties ranging from rigid and strong to highly flexible and elastic.

We realize Lobachevsky geometry in a simulation lab, by producing a carbon-based energetically stable molecular structure, arranged in the shape of a Beltrami pseudosphere. We find that this structure: (i) corresponds to a non-Euclidean crystallographic group, namely a loxodromic subgroup of SL(2, Z); (ii) has an unavoidable singular boundary, that we fully take into account. Our approach, substantiated by extensive numerical simulations of Beltrami pseudospheres of different size, might be applied to other surfaces of constant negative Gaussian curvature, and points to a general procedure to generate them. Our results also pave the way to test certain scenarios of the physics of curved spacetimes owing to graphene's unique properties.

The Weaire-Phelan (WP) structure is the lowest energy structure known of an ideal monodisperse foam in the dry limit. To date, it has not been realized in the laboratory. Instead Lord Kelvin's 1887 structure, which it supplanted in 1994, has repeatedly been found in attempts to produce an ordered structure. This paradox is attributable to the flat walls of the containers used, with which the Kelvin structure is more compatible. Accordingly, we have fabricated a patterned mould whose faceted walls conform to the WP geometry, and thereby succeeded in inducing the formation of perfect crystals of the WP structure. Foam samples consisted of approximately 1500 bubbles. Vibrations favoured crystallization.

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