Towards sustainable injection moulding using 3D printed conformal cooling channels : a comparative simulation study

In recent years, studies have proven that conformal cooling channels (CCC) in an additively manufactured mould result in a more efficient and effective injection moulding process. This can be achieved since CCCs are designed to follow the contour of the part being moulded so that the surface of the part is equidistant from the channel at all points. However, no studies were found which explored the combined effect of mould material thermal conductivity and varying cooling channel designs on the cooling performance of the mould from a sustainability point of view. Within this context, a study was carried out to explore the effect of the tool material’s thermal conductivity on the performance of various CCC designs in comparison with conventional, straight drilled cooling channels. The performance of the cooling channels was analysed from a sustainability point of view by comparing the channel performances in terms of energy consumption, financial implications, and the resulting quality of the part. The results of this study showed that the higher conductivity alloys were especially effective at reducing the cycle time and improving the energy performance of the process in the conventional cooling channel designs. These materials were also capable of reducing the overall cost of the process which was calculated in terms of material costs and electricity consumption. For the CCC designs, however, the high conductivity alloys were less effective in all aspects of this analysis, namely cooling time, energy efficiency, and overall costs. However, it is worth noting that based on the melt flow simulations, the alternative materials had little to no effect on the resulting quality of the part.peer-reviewe

Evaluation of an in vitro coronary stent thrombosis model for preclinical assessment

Stent thrombosis remains an infrequent but significant complication following percutaneous coronary intervention. Preclinical models to rapidly screen and validate therapeutic compounds for efficacy are lacking. Herein, we describe a reproducible, high throughput and cost-effective method to evaluate candidate therapeutics and devices for either treatment or propensity to develop stent thrombosis in an in vitro bench-top model. Increasing degree of stent malapposition (0.00 mm, 0.10 mm, 0.25 mm and 0.50 mm) was associated with increasing thrombosis and luminal area occlusion (4.1 +/- 0.5%, 6.3 +/- 0.5%, 19.7 +/- 4.5%, and 92.6 +/- 7.4%, p < 0.0001, respectively). Differences in stent design in the form of bare-metal, drug-eluting, and bioresorbable vascular scaffolds demonstrated differences in stent thrombus burden (14.7 +/- 3.8% vs. 20.5 +/- 3.1% vs. 86.8 +/- 5.3%, p < 0.01, respectively). Finally, thrombus burden was significantly reduced when healthy blood samples were incubated with Heparin, ASA/Ticagrelor (DAPT), and Heparin+DAPT compared to control (DMSO) at 4.1 +/- 0.6%, 6.9 +/- 1.7%, 4.5 +/- 1.2%, and 12.1 +/- 1.8%, respectively (p < 0.01). The reported model produces high throughput reproducible thrombosis results across a spectrum of antithrombotic agents, stent design, and degrees of apposition. Importantly, performance recapitulates clinical observations of antiplatelet/antithrombotic regimens as well as device and deployment characteristics. Accordingly, this model may serve as a screening tool for candidate therapies in preclinical evaluation