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Hagfishes defend themselves from gill-breathing predators by producing large volumes of fibrous slime when attacked. The slime's effectiveness comes from its ability to clog predators' gills, but the mechanisms by which hagfish slime clogs are uncertain, especially given its remarkably dilute concentration of solids. We quantified the clogging performance of hagfish slime over a range of concentrations, measured the contributions of its mucous and thread components, and measured the effect of turbulent mixing on clogging. To assess the porous structure of hagfish slime, we used a custom device to measure its Darcy permeability. We show that hagfish slime clogs at extremely dilute concentrations like those found in native hagfish slime and displays clogging performance that is superior to three thickening agents. We report an extremely low Darcy permeability for hagfish slime, and an effective pore size of 10–300 nm. We also show that the mucous and thread components play distinct yet crucial roles, with mucus being responsible for effective clogging and low permeability and the threads imparting mechanical strength and retaining clogging function over time. Our results provide new insights into the mechanisms by which hagfish slime clogs gills and may inspire the development of ultra-soft materials with novel properties. 

Inspired by the quest for shape-shifting structures in a range of applications, we show how to create morphable structural materials using a neutrally stable unit cell as a building block. This unit cell is a self-stressed hinged structure with a one-parameter family of morphing motions that are all energetically equivalent. However, unlike kinematic mechanisms, the unit cell is not infinitely floppy and instead exhibits a tunable mechanical response akin to that of an ideal rigid-plastic material. Theory and simulations allow us to explore the properties of planar and spatial assemblies of neutrally stable elements, and solve the inverse problem of designing assemblies that can morph from one given shape into another. Simple experimental prototypes of these assemblies corroborate our theoretical results and show that the addition of switchable hinges allows us to create load-bearing structures. Altogether, totimorphs pave the way for structural materials whose geometry and deformation response can be controlled independently and at multiple scales. 

Virtual memory, specifically paging, is undergoing significant innovation due to being challenged by new demands from modern workloads. Recent work has demonstrated an alternative software only design that can result in simplified hardware requirements, even supporting purely physical addressing. While we have made the case for this Compiler- And Runtime-based Address Translation (CARAT) concept, its evaluation was based on a user-level prototype. We now report on incorporating CARAT into a kernel, forming Compiler- And Runtime-based Address Translation for CollAborative Kernel Environments (CARAT CAKE). In our implementation, a Linux-compatible x64 process abstraction can be based either on CARAT CAKE, or on a sophisticated paging implementation. Implementing CARAT CAKE involves kernel changes and compiler optimizations/transformations that must work on all code in the system, including kernel code. We evaluate CARAT CAKE in comparison with paging and find that CARAT CAKE is able to achieve the functionality of paging (protection, mapping, and movement properties) with minimal overhead. In turn, CARAT CAKE allows significant new benefits for systems including energy savings, larger L1 caches, and arbitrary granularity memory management. 

Moiré superlattices in two-dimensional van der Waals heterostructures provide an efficient way to engineer electron band properties. The recent discovery of exotic quantum phases and their interplay in twisted bilayer graphene (tBLG) has made this moiré system one of the most renowned condensed matter platforms. So far studies of tBLG have been mostly focused on the lowest two flat moiré bands at the first magic angle θ m1 ∼ 1.1°, leaving high-order moiré bands and magic angles largely unexplored. Here we report an observation of multiple well-isolated flat moiré bands in tBLG close to the second magic angle θ m2 ∼ 0.5°, which cannot be explained without considering electron–election interactions. With high magnetic field magnetotransport measurements we further reveal an energetically unbound Hofstadter butterfly spectrum in which continuously extended quantized Landau level gaps cross all trivial band gaps. The connected Hofstadter butterfly strongly evidences the topologically nontrivial textures of the multiple moiré bands. Overall, our work provides a perspective for understanding the quantum phases in tBLG and the fractal Hofstadter spectra of multiple topological bands. 

Fabricating complex structures on micro‐ and mesoscales is a critical aspect in the design of advanced sensors and soft electronics. However, soft lithographic methods offer an important approach to fabricating such structures, the progress in the field of additive manufacturing (e.g., 3D printing) offers methods of fabrication with much more material complexity. The rheological complexity of the printing material, however, often dictates the limitations of printing. In particular, the challenges involved in synthesizing printing materials that can enable shape retention at smaller scales (<100 μm), yet be conductive, limits many applications of 3D printing to soft microelectronics. Herein, a printing‐centered approach using a novel particle‐free conductive emulsion ink is presented. This approach separates the printing and polymerization of a conductive monomer (pyrrole) and renders a novel ink that is used to print filaments with heretofore impossible to realize 3D feature dimensions and build structures with high shape retention. The printability of the ink is evaluated, and post‐treatment properties assessed. Multidirectional strain sensors are printed using the emulsion ink to illustrate an exemplary application in soft electronics.