Graphene is a two-dimensional material that offers a unique combination of low density, exceptional mechanical properties, large surface area and excellent electrical conductivity. Recent progress ...has produced bulk 3D assemblies of graphene, such as graphene aerogels, but they possess purely stochastic porous networks, which limit their performance compared with the potential of an engineered architecture. Here we report the fabrication of periodic graphene aerogel microlattices, possessing an engineered architecture via a 3D printing technique known as direct ink writing. The 3D printed graphene aerogels are lightweight, highly conductive and exhibit supercompressibility (up to 90% compressive strain). Moreover, the Young's moduli of the 3D printed graphene aerogels show an order of magnitude improvement over bulk graphene materials with comparable geometric density and possess large surface areas. Adapting the 3D printing technique to graphene aerogels realizes the possibility of fabricating a myriad of complex aerogel architectures for a broad range of applications.
Field responsive mechanical metamaterials Jackson, Julie A; Messner, Mark C; Dudukovic, Nikola A ...
Science advances,
12/2018, Letnik:
4, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Typically, mechanical metamaterial properties are programmed and set when the architecture is designed and constructed, and do not change in response to shifting environmental conditions or ...application requirements. We present a new class of architected materials called field responsive mechanical metamaterials (FRMMs) that exhibit dynamic control and on-the-fly tunability enabled by careful design and selection of both material composition and architecture. To demonstrate the FRMM concept, we print complex structures composed of polymeric tubes infilled with magnetorheological fluid suspensions. Modulating remotely applied magnetic fields results in rapid, reversible, and sizable changes of the effective stiffness of our metamaterial motifs.
The implementation of Natura 2000 is causing difficulties in the EU’s Member States, including Slovenia. In addition to the positive environmental it also results in the negative economic, social, ...and governance-administrative effects. To prevent similar quandaries in adopting and implementing EU policies, the project ESPON EATIA developed a participatory process for the territorial impact assessment. Testing the Habitat Directive has shown that in addition to the positive effects regarding the conservation of biodiversity, the directive represents a major obstacle for the economy and the delivery of investments. At the same time it represents the potential of the area for tourism and opportunity for the development of new industries. The regulation contributes to a better quality of life, but also extends the spatial planning procedures and conflicts between investors and the local community. This approach has proven to be an appropriate medium for the exchange of experiences of various stakeholders who are involved in either the preparation or the implementation of the rules and as the proper tool for the global assessment of the effects of selected EU regulation.
Additive Manufacturing (AM), or 3D printing, is a powerful technology that is revolutionizing the way designers create products across many industries. AM technology is severely limited by the lack ...of effective methods for in situ characterization of multi-material properties and composition during printing. The ability to detect the composition of multi-material printed inks in real time is an emerging need for a wide range of manufacturing applications. In this study, dielectric properties of embedded metal microparticles in a dielectric matrix are measured and characterized as a function of particle size, shape, volume percentage and frequency. Unexpectedly, there was no observation of any percolation threshold. The impedance was found to decrease with the percentage of metal filler as expected. While particle shape seemed to have significant effect on the impedance, there was little to no correlation between particle size and impedance. The resulting data can be used to generate a calibration curve correlating metal loading with impedance or capacitance. We discuss how this data can be used for in situ sensing of local ink composition, which does not currently exist, to facilitate greater control over the resulting properties and functionality of printed materials.
The purpose of this study was to evaluate the effect of Y-TZP ceramic surface functionalization with a nano-structured alumina coating on bond strength of the resin modified glass ionomer dental ...cement. A total of 160 disc-shaped specimens were produced and randomly divided into two groups of 80. Half of the discs in each group received an alumina coating which was fabricated by exploiting the hydrolysis of aluminum nitride (AlN) powder. The shear bond strengths of the resin-modified glass ionomer cement FUJI+ (GC Japan) and the composite resin luting agent RelyX Unicem (3M ESPE, USA) were then studied for the coated and uncoated surfaces The SEM analyses revealed that the application of an alumina coating to the Y-TZP ceramics created a highly retentive surface for bonding. The bond strengths for the coated groups in both cements were significantly higher than the uncoated groups.
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