Nano Focus
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Nano Focus
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(a) The extruding nozzle in action, printing the scaffolds for a bridge. (b) A hollow 3D printed bunny with pink dye added. Credit: Images adapted from Additive Manufacturing.
of the rods. Through numerical models the researchers determined that the printed beams are stable if they are thinner than the extrusion nozzle. They then proved their concept by printing structures out of rods that would be impossible with traditional 3D printing methods, including truss bridges and hollow bunnies. The ultimate goal is to be able to use these 3D printed structures as scaffolds for cell culture to grow organs and blood vessels for transplantation. “The first step was
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to establish the scaffold printing process, which we report in this study,” Bhargava says. “The next step is to deposit and grow cells in a supported manner on these scaffolds. The third major step is to remove scaffold materials such that biological activity is minimally affected and the fabricated tissue structure is structurally stable.” If all goes well with the development of this technology, we can look forward to both lifesaving and delicious printed structures. Alex Klotz
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Vertically aligned MXene nanosheets speed up supercapacitor
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he practical potential of MXenes (twodimensional, a few atoms thick layers of transition-metal carbides, nitrides, and carbonitrides) as supercapacitor electrodes has become more promising with the successful vertical alignment of MXene nanosheets on substrates. These electrodes exhibit ultrafast charging capabilities. This leap in energy storage, published recently in Nature (doi:10.1038/s41586018-0109-z), was achieved by the collaboration between Shu Yang’s group at the University of Pennsylvania and Yury Gogotsi’s group at Drexel University. The conventional configuration is composed of horizontally stacked MXene sheets that is undesirable for fastrate charging as ion diffusion through the sheets is severely impeded by the compact-film configuration. The sluggish ion movement leads to deterioration
c (a) The horizontally stacked configuration induces slow ion transport. (b) The vertical alignment architecture provides straight ion-movement channels that accelerate ion transport. (c) A topview scanning electron microscope image showing the morphology of the vertically aligned Ti3C2Tx nanosheets. Credit: Nature.
of energy-storage capacity at elevated charging rates. This problem is exacerbated when the film thickness approaches or exceeds 10 µm, far less than the industrial thickness standard of 100 µm
for active materials used in supercapacitors. To resolve this issue, developing electrodes with straight ion-movement channels extending from the electrode surface to the substrate is critical.
• VOLUME • www.mrs.org/bulletin MRS BULLETIN 43 • AUGUST Downloaded from https://www.cambridge.org/core. IP address: 79.133.107.171, on 03 Sep 2018 at 20:52:38, subject to the Cambridge Core terms of use, 2018 available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/mrs.2018.185
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