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Cellular metamaterials are an emerging class of porous materials, in which the topology of the solid is precisely-engineered to achieve attractive combinations of properties. This work specifically examines the tensile response of a novel type of cellular metamaterials, in which pores of arbitrary elliptical shape are randomly-dispersed into an aluminum alloy matrix. Their porous mesostructure is generated numerically via a random sequential absorption algorithm, and is fabricated by laser powder bed fusion from AlSi10Mg powders. The results – obtained by means of digital image correlation combined with X-ray tomography – highlight the advantages offered by a random cellular topology. They are notably a low sensitivity to geometric imperfections (which inevitably result from manufacturing), coupled with the ability to delay long-wavelength strain localization, which is in turn responsible for failure. Structural disorder also leads to highly heterogeneous deformation patterns, which result from the interaction between geometric pores and promote void growth and coalescence during plastic straining. The presence of manufacturing defects exacerbates void interaction and promotes early plastic flow localization. Interestingly, experiments reveal that this class of porous solids effectively displays features of the ductile fracture of metals at the mesoscale. For example, void-sheeting is observed with increasing pore aspect ratio and is accompanied by large geometric distortions of the voids upon coalescence. Measured data for the pore strains are highly scattered and show a departure from McClintock's model predictions for the voids within the fracture band. Collectively, this study highlights the potential offered by random porous metamaterials, which can be harnessed to revisit the complex mechanisms of ductile fracture at the mesoscale. [Display omitted] • The mechanisms of ductile fracture were revisited using random porous metamaterials. • Structural disorder was found to delay long-wavelength localization. • Void-sheeting was observed with increasing pore aspect ratio. • McClintock's model underestimated void growth data within the failure band. [ABSTRACT FROM AUTHOR]

Median sternotomy and cardiopulmonary bypass (CPB) represent the gold standard for the left ventricular assist device (LVAD) implantation. Long-term survival rates in LVAD patients are highly dependent on the immediate peri- and post-operative course. The CPB deleterious effects in this fragile population include right ventricular dysfunction, bleeding, and end-organ injury. Minimally invasive strategies, with off-pump implantation and alternative access rather than sternotomy, have been recently reported for contemporary continuous-flow LVAD placement.We sought to assess the safety, feasibility, and short-term outcomes of minimally invasive off-pump LVAD implantation. We retrospectively reviewed data of 19 patients who underwent off-pump Jarvik 2000 LVAD implantation, as destination therapy, from December 2010 to April 2019, at our center. The surgical access was: J-ministernotomy + left minithoracotomy in 89.5%, and anterolateral thoracotomy in 10.5% of the patients. Study endpoints were perioperative outcomes and long-term survival. Mean age was 67.1±5.2 years, 89.5 % were male and the underlying disease was ischemic cardiomyopathy in 42.1%. INTERMACS class was: II: 10.5%, III: 31.6%, IV: 57.9%. There were no on-pump conversions; a major bleeding required a surgical access conversion in 2 cases. Mean mechanical ventilation time was 17±7 hours, median of blood transfusion units was 6 (interquartile range 3-15). Perioperative stroke, bleeding requiring surgical re-entry and severe right ventricular failure were 5.2%, 21.1%, and zero, respectively. Median postoperative hospital stay was 30 days (interquartile range 21.5-45) with a 5.2% 30-day mortality rate. Mean duration of support was 1034.7 days (range 8-1981 days). Three patients had LVAD-related complications leading to device explant, after a mean time of 983±310 days: two patients underwent a re-do LVAD exchange, one was successfully transplanted. One- and 2-year overall survival were 77.8% ± 9.8% and 70% ± 11.5%, respectively. Our preliminary experience shows that off-pump Jarvik 2000 LVAD implantation is feasible and safe alternative to the standard implantation technique. Good peri-operative outcomes and long-term survival rates could encourage an extended use of this strategy. However, additional implants and comparison of outcomes in larger populations are needed. [ABSTRACT FROM AUTHOR]