The advent of technologies such as magnetic resonance imaging (MRI)-guided radiation therapy has led to the need for phantom materials that are capable of producing tissue-like contrast on both MRI and computed tomography (CT) imaging modalities. The purpose of this work is to develop a system of easily made and formed materials with adjustable T1 and T2 relaxation times, and x-ray attenuation properties, for mimicking soft tissue and bone with both MRI and CT imaging modalities. The effects on T1/T2 relaxation times and CT numbers were quantified for a range of Gd contrast (0-25 μmol/g), agarose (0-8% w/w), glass microspheres (GMs) (0-10% w/w ) and CaCO3 (0-50% w/w) concentrations in a carrageenan-based gel. 105 gel samples were prepared with the additives, carrageenan and water. Samples were imaged in a 3D-printed holding structure to find the attainable range of T1/T2 relaxation time and CT number combinations. T1 and T2 relaxation time maps were generated using voxel-wise inversion-recovery and spin-echo techniques, respectively. A multivariate linear regression model was generated to allow the materials system to be generalized to semi-arbitrary T1/T2 relaxation times and CT numbers. Nine diverse tissue types were mimicked for fit model validation. The achievable T1/T2 relaxation times and CT numbers for the additive concentrations tested in this study spanned from 82 to 2180 ms, 12 to 475 ms, and -117 to +914 Hounsfield Units (HU) respectively. The mean absolute error between the fit model predicted and measured T1/T2 relaxation times and CT numbers for the nine tested tissue types was 113±64 ms, 16±26 ms and 11±14 HU respectively. In conclusion, we have created a system of materials capable of producing tissue-like contrast for 3.0T MRI and CT imaging modalities. © 2020 Institute of Physics and Engineering in Medicine.The objective of this study is to integrate biomimetic robots into small groups of zebrafish and to modulate their collective behaviours. In this study, we explore different strategies that use biomimetic zebrafish behaviours. check details In past work, we have shown that robots biomimicking zebrafish can be socially integrated into zebrafish groups. We have also shown that a fish-like robot can modulate the rotation choice of zebrafish groups in a circular set-up. Here, we further study the modulation capabilities of such robots in a more complex set-up. To do this, we exploit zebrafish social behaviours we identified in previous studies. We first modulate collective departure by replicating the leadership mechanisms with the robot in a set-up composed of two rooms connected by a corridor. Then, we test different behavioural strategies to drive the fish groups towards a predefined target room. To drive the biohybrid groups towards a predefined choice, they have to adopt some specific fish-like behaviours. The first strategy is based on a single robot using the initiation behaviour. In this case, the robot keeps trying to initiate a group transition towards the target room. The second strategy is based on two robots, one initiating and one staying in the target room as a social attractant. The third strategy is based on a single robot behaving like a zebrafish but staying in the target room as a social attractant. The fourth strategy uses two robots behaving like zebrafish but staying in the target room. We conclude that robots can modulate zebrafish group behaviour by adopting strategies based on existing fish behaviours. Under these conditions, robots enable the testing of hypotheses about the behaviours of fish. © 2020 IOP Publishing Ltd.Osteoporotic bone defect is a major challenge in clinics for bone regeneration. Under the condition of osteoporosis, excessive bone absorption and impaired osteogenesis resulted in unexpected long healing procedure of defects. In order to simultaneously enhance bone formation and reduce bone resorption, a polydopamine-coated porous titanium scaffold was designed to be integrated with the anti-catabolic drug zoledronic acid nanoparticles (ZOL loaded gelatin NPs), which was able to achieve a local sustained-release of ZOL as expected. The in-vitro study demonstrated that the extracts of the composite scaffolds would stimulate the osteoblast differentiation; meanwhile, they also inhibited osteoclastogenesis at a ZOL loading concentration of 50μmo/L. In vivo study, thereafter, the composite scaffolds were implanted into the ovariectomy-induced osteoporotic rabbits suffering from femoral condyles defects. The results indicated that the composite scaffolds without ZOL loaded gelatin NPs only induced callus formation mainly at the interface margin between the implant and bone, whereas the composite scaffolds with ZOL loaded gelatin NPs were capable to further enhance osteogenesis and bone growth into the scaffolds. Moreover, the research proved that the promoting effect was optimal at a ZOL loading concentration of 50μmo/L. In summary, the present research indicated that a new type of porous titanium scaffold integrated with ZOL loaded gelatin NPs inherited a superior biocompatibility and bone regeneration capability. It would be an optimal alternative for the reconstruction of osteoporosis-related defects than the traditional porous titanium implant; in other words, the new type of scaffold would offer a new effective and practical procedure option for patients suffering from osteoporotic bone defects. Creative Commons Attribution license.Engineering constructs that mimic the complex structure, composition and biomechanics of the articular cartilage represents a promising route to joint regeneration. Such tissue engineering strategies require the development of biomaterials that mimic the mechanical properties of articular cartilage whilst simultaneously providing an environment supportive of chondrogenesis. Here three-dimensional (3D) bioprinting is used to develop polycaprolactone (PCL) fibre networks to mechanically reinforce interpenetrating network (IPN) hydrogels consisting of alginate and gelatin methacryloyl (GelMA). Inspired by the significant tension-compression nonlinearity of the collagen network in articular cartilage, we printed reinforcing PCL networks with different ratios of tensile to compressive modulus. Synergistic increases in compressive modulus were observed when IPN hydrogels were reinforced with PCL networks that were relatively soft in compression and stiff in tension. The resulting composites possessed equilibrium and dynamic mechanical properties that matched or approached that of native articular cartilage.