Biological materials by design

Compton scattering geometry: a tool to study radiation interaction characteristics of rare earth compounds doped in low-Z organic compound

The present measurements comprise of Compton scattering technique at six energies from 0.242 MeV to 0.402 MeV (not available from conventional radioisotopes) by scattering of primary gamma photon beam of 0.662 MeV energy from cylindrical aluminium target at different scattering angles. Two inorganic (rare-earth) compounds, Lanthanum (3+) nitrate hexahydrate and Samarium (3+) nitrate hexahydrate in a Low-Z organic solvent (acetone), have shown certain radiation interaction characteristics are the subject of study. The collimated beam of scattered gamma rays impinges on the plastic container having solution of rare earth compounds in the acetone of different concentrations. The transmitted gamma ray beam is detected by a well-collimated 2″ × 2″ NaI(Tl) scintillation detector and is analysed by a PC-based ORTEC Mastero-32 MCA. Attenuation coefficients along with some shielding parameters i.e. molar extinction coefficients, half value layer, tenth value layer and mean free path are evaluated. Besides this, Computed Tomography numbers and photon interaction cross-sections (photoelectric, coherent and incoherent) are also determined. The measured values of these parameters are compared with WinXCom software package’s values and are found to be in good agreement. The available data on rare earth salts’ solutions, in the current measurements, is scientifically important in nuclear and radiation physics, bridging the gap in which radiation workers do not have access to such data.

Enhanced Mechanical Performance of Bio-Inspired Hybrid Structures Utilising Topological Interlocking Geometry

Structural composites inspired by nacre have emerged as prime exemplars for guiding materials design of fracture-resistant, rigid hybrid materials. The intricate microstructure of nacre, which combines a hard majority phase with a small fraction of a soft phase, achieves superior mechanical properties compared to its constituents and has generated much interest. However, replicating the hierarchical microstructure of nacre is very challenging, not to mention improving it. In this article, we propose to alter the geometry of the hard building blocks by introducing the concept of topological interlocking. This design principle has previously been shown to provide an inherently brittle material with a remarkable flexural compliance. We now demonstrate that by combining the basic architecture of nacre with topological interlocking of discrete hard building blocks, hybrid materials of a new type can be produced. By adding a soft phase at the interfaces between topologically interlocked blocks in a single-build additive manufacturing process, further improvement of mechanical properties is achieved. The design of these fabricated hybrid structures has been guided by computational work elucidating the effect of various geometries. To our knowledge, this is the first reported study that combines the advantages of nacre-inspired structures with the benefits of topological interlocking.

Three-Dimensional-Printing of Bio-Inspired Composites

Optimized for millions of years, natural materials often outperform synthetic materials due to their hierarchical structures and multifunctional abilities. They usually feature a complex architecture that consists of simple building blocks. Indeed, many natural materials such as bone, nacre, hair, and spider silk, have outstanding material properties, making them applicable to engineering applications that may require both mechanical resilience and environmental compatibility. However, such natural materials are very difficult to harvest in bulk, and may be toxic in the way they occur naturally, and therefore, it is critical to use alternative methods to fabricate materials that have material functions similar to material function as their natural counterparts for large-scale applications. Recent progress in additive manufacturing, especially the ability to print multiple materials at upper micrometer resolution, has given researchers an excellent instrument to design and reconstruct natural-inspired materials. The most advanced 3D-printer can now be used to manufacture samples to emulate their geometry and material composition with high fidelity. Its capabilities, in combination with computational modeling, have provided us even more opportunities for designing, optimizing, and testing the function of composite materials, in order to achieve composites of high mechanical resilience and reliability. In this review article, we focus on the advanced material properties of several multifunctional biological materials and discuss how the advanced 3D-printing techniques can be used to mimic their architectures and functions. Lastly, we discuss the limitations of 3D-printing, suggest possible future developments, and discuss applications using bio-inspired materials as a tool in bioengineering and other fields.