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We experimentally explored the effect of single-sidewall cooling on Rayleigh–Bénard (RB) convection. Canonical RB was also studied to aid insight. The scenarios shared tank dimensions and bottom and top wall temperatures; the single sidewall cooling had the top wall temperature. Turbulence was explored at two canonical Rayleigh numbers, $$Ra=1.6\times 10^{10}$$ and $$Ra=2\times 10^9$$ under Prandtl number $Pr=5.4$ . Particle image velocimetry described vertical planes parallel and perpendicular to the sidewall cooling. The two $Ra$ scenarios reveal pronounced changes in the flow structure and large-scale circulation (LSC) due to the sidewall cooling. The density gradient induced by the sidewall cooling led to asymmetric descending and ascending flows and irregular LSC. Flow statistics departed from the canonical case, exhibiting lower buoyancy effects, represented by an effective Rayleigh number with effective height dependent on the distance from the lateral cooling. Velocity spectra show two scalings, $$\varPhi \propto f^{-5/3}$$ Kolmogorov (KO41) and $$\varPhi \propto f^{-11/5}$$ Bolgiano (BO59) in the larger $Ra$ ; the latter was not present in the smaller set-up. The BO59 scaling with sidewall cooling appears at higher frequencies than its canonical counterpart, suggesting weaker buoyancy effects. The LSC core motions allowed us to identify a characteristic time scale of the order of vortex turnover time associated with distinct vortex modes. The velocity spectra of the vortex core oscillation along its principal axis showed a scaling of $$\varPhi _c \propto f^{-5/3}$$ for the single sidewall cooling, which was dominant closer there. It did not occur in the canonical case, evidencing the modulation of LSC oscillation on the flow. 

The dynamics of air bubbles in turbulent Rayleigh–Bénard (RB) convection is described for the first time using laboratory experiments and complementary numerical simulations. We performed experiments at $$Ra=5.5\times 10^{9}$$ and $$1.1\times 10^{10}$$ , where streams of 1 mm bubbles were released at various locations from the bottom of the tank along the path of the roll structure. Using three-dimensional particle tracking velocimetry, we simultaneously tracked a large number of bubbles to inspect the pair dispersion, $$R^{2}(t)$$ , for a range of initial separations, $$r$$ , spanning one order of magnitude, namely $$25\unicode[STIX]{x1D702}\leqslant r\leqslant 225\unicode[STIX]{x1D702}$$ ; here $$\unicode[STIX]{x1D702}$$ is the local Kolmogorov length scale. Pair dispersion, $$R^{2}(t)$$ , of the bubbles within a quiescent medium was also determined to assess the effect of inhomogeneity and anisotropy induced by the RB convection. Results show that $$R^{2}(t)$$ underwent a transition phase similar to the ballistic-to-diffusive ( $$t^{2}$$ -to- $$t^{1}$$ ) regime in the vicinity of the cell centre; it approached a bulk behavior $$t^{3/2}$$ in the diffusive regime as the distance away from the cell centre increased. At small $$r$$ , $$R^{2}(t)\propto t^{1}$$ is shown in the diffusive regime with a lower magnitude compared to the quiescent case, indicating that the convective turbulence reduced the amplitude of the bubble’s fluctuations. This phenomenon associated to the bubble path instability was further explored by the autocorrelation of the bubble’s horizontal velocity. At large initial separations, $$R^{2}(t)\propto t^{2}$$ was observed, showing the effect of the roll structure. 

Haptic interfaces can be used to add sensations of touch to virtual and augmented reality experiences. Soft, flexible devices that deliver spatiotemporal patterns of touch across the body, potentially with full-body coverage, are of particular interest for a range of applications in medicine, sports and gaming. Here we report a wireless haptic interface of this type, with the ability to display vibro-tactile patterns across large areas of the skin in single units or through a wirelessly coordinated collection of them. The lightweight and flexible designs of these systems incorporate arrays of vibro-haptic actuators at a density of 0.73 actuators per square centimetre, which exceeds the two-point discrimination threshold for mechanical sensation on the skin across nearly all the regions of the body except the hands and face. A range of vibrant sensations and information content can be passed to mechanoreceptors in the skin via time-dependent patterns and amplitudes of actuation controlled through the pressure-sensitive touchscreens of smart devices, in real-time with negligible latency. We show that this technology can be used to convey navigation instructions, to translate musical tracks into tactile patterns and to support sensory replacement feedback for the control of robotic prosthetics. 

Abstract Physically transient forms of electronics enable unique classes of technologies, ranging from biomedical implants that disappear through processes of bioresorption after serving a clinical need to internet-of-things devices that harmlessly dissolve into the environment following a relevant period of use. Here, we develop a sustainable manufacturing pathway, based on ultrafast pulsed laser ablation, that can support high-volume, cost-effective manipulation of a diverse collection of organic and inorganic materials, each designed to degrade by hydrolysis or enzymatic activity, into patterned, multi-layered architectures with high resolution and accurate overlay registration. The technology can operate in patterning, thinning and/or cutting modes with (ultra)thin eco/bioresorbable materials of different types of semiconductors, dielectrics, and conductors on flexible substrates. Component-level demonstrations span passive and active devices, including diodes and field-effect transistors. Patterning these devices into interconnected layouts yields functional systems, as illustrated in examples that range from wireless implants as monitors of neural and cardiac activity, to thermal probes of microvascular flow, and multi-electrode arrays for biopotential sensing. These advances create important processing options for eco/bioresorbable materials and associated electronic systems, with immediate applicability across nearly all types of bioelectronic studies. 

Abstract An organism’s ability to control the timing and direction of energy flow both within its body and out to the surrounding environment is vital to maintaining proper function. When physically interacting with an external target, the mechanical energy applied by the organism can be transferred to the target as several types of output energy, such as target deformation, target fracture, or as a transfer of momentum. The particular function being performed will dictate which of these results is most adaptive to the organism. Chewing food favors fracture, whereas running favors the transfer of momentum from the appendages to the ground. Here, we explore the relationship between deformation, fracture, and momentum transfer in biological puncture systems. Puncture is a widespread behavior in biology requiring energy transfer into a target to allow fracture and subsequent insertion of the tool. Existing correlations between both tool shape and tool dynamics with puncture success do not account for what energy may be lost due to deformation and momentum transfer in biological systems. Using a combination of pendulum tests and particle tracking velocimetry (PTV), we explored the contributions of fracture, deformation and momentum to puncture events using a gaboon viper fang. Results on unrestrained targets illustrate that momentum transfer between tool and target, controlled by the relative masses of the two, can influence the extent of fracture achieved during high-speed puncture. PTV allowed us to quantify deformation throughout the target during puncture and tease apart how input energy is partitioned between deformation and fracture. The relationship between input energy, target deformation and target fracture is non-linear; increasing impact speed from 2.0 to 2.5 m/s created no further fracture, but did increase deformation while increasing speed to 3.0 m/s allowed an equivalent amount of fracture to be achieved for less overall deformation. These results point to a new framework for examining puncture systems, where the relative resistances to deformation, fracture and target movement dictate where energy flows during impact. Further developing these methods will allow researchers to quantify the energetics of puncture systems in a way that is comparable across a broad range of organisms and connect energy flow within an organism to how that energy is eventually transferred to the environment.