Inspired by rattleback toys, we created small chiral wires that rotate in a preferred direction on a vertically oscillating platform and quantified their motion with experiment and simulation. We demonstrate experimentally that angular momentum of rotation about particle centers of mass is converted to collective angular momentum of center-of-mass motion in a granular gas of these wires, and we introduce a continuum model that explains our observations.

Internal imaging using index matching, and sensitive volume measurement, are used to investigate the spatial order and dynamics of a deep disordered layer of spheres sheared under a fixed load. Shearing triggers a crystallization transition accompanied by a step compaction event. The delay preceding the transition depends strongly on the layer thickness and can require a translation of about 10(5) particle diameters. The mean velocity varies with depth by more than five decades, and its profile is qualitatively altered by the transition.

Simultaneous time-resolved measurements of internal structure, granular volume, and boundary shear force are reported for dense granular packing steadily sheared under a fixed normal load. We identify features of the crystallization transition for a deep shear flow, whose height-dependent local mean velocity spans more than five orders of magnitude. This structural change is accompanied by a significant decrease of granular volume and shear force, with a more rapid falloff of particle velocity with depth than occurs in the disordered state. Boundary conditions can have a profound influence on the crystallization of the entire packing. We find that continuously sheared flow can exhibit nonunique final states even under identical boundary conditions; a few cycles of oscillatory pretreatment can initiate states that evolve into either a crystallized or a disordered final state after long-term unidirectional shearing. On the other hand, the disordered state can be stabilized after being sufficiently compacted by unidirectional shear. These experiments raise interesting questions about how prior history is recorded in the internal structure of granular packings, affecting their instantaneous rheology and long-term evolution in response to shear.

Applying pressure driving to a single layer of aqueous foam bubbles induces a void propagation that is a surprisingly close analog of dynamic crack propagation. Depending on the rate of applied stress, both a ductile and a brittle mode of propagation are observed, the latter at much higher propagation speeds. A pronounced velocity gap is found, with a well-defined upper limit to the ductile crack speed and a well-defined lower limit to the brittle propagation speed. Both limits can be quantitatively explained by analyzing processes on the scale of single bubbles and single films, respectively, confirming the importance of the microscopic (single-bubble) scale for the overall description of these fracture phenomena. We find that the brittle crack velocity is limited by the speed of wave propagation in the foam, so that the brittle mode can be understood as a supersonic crack.

Liquid foams are an extreme case of multiphase flow systems: capable of flow despite a very high dispersed phase volume fraction, yet exhibiting many characteristics of not only viscoelastic materials but also elastic solids. The non-trivial, well-defined geometry of foam bubbles is at the heart of a plethora of dynamical processes on widely varying length and time scales. We highlight recent developments in foam drainage (liquid dynamics) and foam rheology (flow of the entire gas-liquid system), emphasizing that many poorly understood features of other materials have precisely defined and quantifiable analogues in aqueous foams, where the only ingredients are well-known material parameters of Newtonian fluids and bubble geometry, together with subtle but important information on the surface mobility of the foam. Not only does this make foams an ideal model system for the theorist, but also an exciting object for experimental studies, in which dynamical processes span length scales from nanometres (thin films) to metres (foam continuum flows) and time scales from microseconds (film rupture) to minutes (foam rheology).

Highlights d A cortex/medulla composite beam organization allows rachides to adapt flexibly d Polarized adhesion and keratin expression lead to hooklet barbules that form vanes d With-dermal papilla WNT signaling controls barbule shape along the feather P-D axis d 3D feathers embedded in amber show primitive vanes formed by overlapping barbules

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Three isoform-specific antibodies, 6F against the α1-isoform of the avian sodium pump, HERED against the rat α2-isoform, and Ax2 against the rat α3-isoform, were used to detect the expression of Na+-K+-ATPase α-subunits in gills of a teleost, the tilapia ( Oreochromis mossambicus). Tilapia gill tissue showed positive reactions to antibodies specific for α1- and α3-isoforms. The results of immunoblots were converted to numerical values (relative intensities) by image analysis for comparisons. Relative amounts of α1-like isoform alone and consequently the ratio of α1-like to α3-like isoforms were higher in gills of seawater-adapted tilapia than in those of freshwater-adapted ones, indicating that the two isoforms respond differently to environmental salinities. In the subsequent immunocytochemical experiments, gill mitochondria-rich cells were demonstrated to immunoreact with antibodies specific for α1- and α3-isoforms. α1-like and α3-like isoforms of gill Na+-K+-ATPase are suggested to be involved in the ion- and osmoregulation mechanisms in tilapia. Moreover, differential expressions of two isoforms may be associated with different functions, secretion and uptake of ions and acid-base regulation, in gills of seawater- and freshwater-adapted tilapia.