Microstructure versus Size: Mechanical Properties of Electroplated Single Crystalline Cu Nanopillars

We report results of uniaxial compression experiments on single-crystalline Cu nanopillars with nonzero initial dislocation densities produced without focused ion beam (FIB). Remarkably, we find the same power-law size-driven strengthening as FIB-fabricated face-centered cubic micropillars. TEM analysis reveals that initial dislocation density in our FIB-less pillars and those produced by FIB are on the order of 10^(14)  m^(-2) suggesting that mechanical response of nanoscale crystals is a stronger function of initial microstructure than of size regardless of fabrication method

Invariant NKT Cell Lines Derived from the NOD·H2h4 Mouse Enhance Autoimmune Thyroiditis

To study the role of invariant Natural Killer T cell ( iNKT) cells in autoimmune thyroiditis, we derived two iNKT cell lines from the spleens of NOD· H2h4 mice, a strain that develops spontaneous autoimmune thyroiditis exacerbated by excess dietary iodine. The two lines were CD1d-restricted and expressed CD4+, DX5+, and the Vα4Jα281 gene segment, of the T-cell receptor α locus. Upon stimulation with α-galactosyl-ceramide (α-GalCer), both lines rapidly produced IL-2, IL-4, IFN-γ, IL-10, and TNF-α. Strikingly, a similar cytokine response was also induced by thyroglobulin, one of the most abundant protein in the thyroid gland and a major autoantigen in human autoimmune thyroiditis. Transfer of the iNKT cell lines to syngeneic hosts enhanced autoimmune thyroiditis. Intraperitoneal injections of α-GalCer in iodine primed mice also induced thyroid disease. This paper reports for the first time that iNKT cells respond to thyroglobulin and enhance autoimmune thyroiditis in iodine fed NOD·H2h4 mice

Mechanical characterisation of additively manufactured elastomeric structures for variable strain rate applications

Additive manufacturing (AM) enables production of geometrically-complex elastomeric structures. The elastic recovery and strain-rate dependence of these materials means they are ideal for use in dynamic, repetitive mechanical loading. Their process-dependence, and the frequent emergence of new AM elastomers, commonly necessitates full material characterisation; however, accessing specialised equipment means this is often a time-consuming and expensive process. This work presents an innovative equi-biaxial rig that enables full characterisation via just a conventional material testing machine (supplementing uni-axial tension and planar tension tests). Combined with stress relaxation data, this provides a novel route for hyperelastic material modelling with viscoelastic components. This approach was validated by recording the force-displacement and deformation histories from finite element modelling a honeycomb structure. These data compared favourably to experimental quasistatic and dynamic compression testing, validating this novel and convenient route for characterising complex elastomeric materials. Supported by data describing the potential for high build-quality production using an AM process with low barriers to entry, this study should serve to encourage greater exploitation of this emerging manufacturing process for fabricating elastomeric structures within industrial communities.M. Robinson was supported by the Knowledge Economy Skills Scholarships 2 (via the Welsh Government’s European Social Fund). The X-ray imaging work was supported by the Advanced Imaging of Materials (AIM) facility (EPSRC grant no. EP/M028267/1), the European Social Fund (ESF) through the European Union’s Convergence programme administered by the Welsh Government

Developing elastomeric cellular structures for multiple head impacts

Foam‐based materials were originally incorporated into helmets in the 1970’s, providing an effective method of absorbing impact energy and so protecting against severe head injury. Similar materials still exist in the majority of protective helmets today, indicating a need for an innovative approach that will achieve a step‐ change in energy absorption performance. This paper focusses on tailoring the Miura‐Ori (MO), origami‐derived geometry, as a method to achieve a material structure tailored to maximise impact energy absorption, whilst complying with existing product design constraints. This ambitious concept was then realised using an elastomeric, additive manufacturing powder, before being tested against foam derived from a commercially‐ available American football helmet. MO pads demonstrated comparable performance versus foam at relatively low impact velocities, though recorded a peak acceleration 15% less than foam at the highest impact velocity. This difference increased once the respective samples were exposed to their third impact, demonstrating the superior performance of MO over multiple impacts. The MO material demonstrated encouraging energy impact absorbing behaviour, with scope remaining to further optimise the geometry in order to further enhance performance. Furthermore, opportunities exist for achieving superior shear‐energy performance than contemporary materials and, ultimately, for harnessing the benefits of additive manufacturing to fabricate person‐specific headwear optimised for a given impact environment

Spatially-resolved Assessment of Land and Water Use Scenarios for Shale Gas Development: Poland and Germany

The analysis presented in this report focuses specifically on two issues of potential concern with respect to shale gas development in EU member states using hydraulic fracturing technologies: pressure on freshwater resources, and land use competition. Potential alternative technologies, such as “dry fracking”, are not considered, because they are still at the research and development stage. We reviewed available literature in order to identify important variables that may influence the land and water requirements associated with shale gas development. We further derived a range of representative values spanning worst-, average- and best-case scenarios for each variable. We then coupled specific technology scenarios (incorporating these variables) regarding water and land use requirements for shale gas development from 2013-2028 with spatially-resolved water and land availability/demand modeling tools (i.e. using the European Land Use Modelling Platform (LUMP)). Scenario analyses (intended to represent worst-, average- and best-case assumptions) were subsequently implemented that incorporate a subset of the identified variables for shale gas development in the Lower Paleozoic Baltic-Podlasie-Lublin basin in Poland and for Germany as a whole from 2013-2028. In addition, we undertook a screening-level risk assessment of potential human and ecosystem health impacts attributable to accidental or operational release of chemicals used in hydraulic fracturing of shale formations, as well as the average gaseous emissions (per active well) associated with shale gas development activities that might be anticipated within a shale play. Finally, we developed a qualitative discussion of necessary considerations to support future air quality impact assessments for shale gas development activities.JRC.H.8-Sustainability Assessmen

Photon-mediated interactions between quantum emitters in a diamond nanocavity

Photon-mediated interactions between quantum systems are essential for realizing quantum networks and scalable quantum information processing. We demonstrate such interactions between pairs of silicon-vacancy (SiV) color centers coupled to a diamond nanophotonic cavity. When the optical transitions of the two color centers are tuned into resonance, the coupling to the common cavity mode results in a coherent interaction between them, leading to spectrally-resolved superradiant and subradiant states. We use the electronic spin degrees of freedom of the SiV centers to control these optically-mediated interactions. Such controlled interactions will be crucial in developing cavity-mediated quantum gates between spin qubits and for realizing scalable quantum network nodes