Biomechanical drivers of the evolution of butterflies and moths with a coilable proboscis.

Current biomechanical models suggest that butterflies and moths use their proboscis as a drinking straw pulling nectar as a continuous liquid column. Our analyses revealed an alternative mode for fluid uptake: drinking bubble trains that help defeat drag. We combined X-ray phase-contrast imaging, optical video microscopy, micro-computed tomography, phylogenetic models of evolution and fluid mechanics models of bubble-train formation to understand the biomechanics of butterfly and moth feeding.

Experiments and Modeling of Flow-Enhanced Nucleation in LLDPE.

A computational and experimental framework for quantifying flow-enhanced nucleation (FEN) in polymers is presented and demonstrated for an industrial-grade linear low-density polyethylene (LLDPE). Experimentally, kinetic measurements of isothermal crystallization were performed by using fast-scanning calorimetry (FSC) for melts that were presheared at various strain rates. The effect of shear on the average conformation tensor of the melt was modeled with the discrete slip-link model (DSM).

Stability Assessment of a Polymeric Brominated Flame Retardant in Polystyrene Foams under Application-Relevant Conditions.

The flame retardant (FR) BLUEDGE polymeric flame retardant (PFR) has been in use since 2011 and was developed as a replacement FR for hexabromocyclododecane in polystyrene (PS)-based insulation foams. To better understand the degradation behavior of the PFR used within PS foams, we examined the degradation of PFR under application-relevant conditions. Thermo-oxidative and photolytic pathways represent the most relevant degradation pathways.

Self-assembly of the butterfly proboscis: the role of capillary forces.

The proboscis of butterflies and moths consists of two C-shaped fibres, the galeae, which are united after the insect emerges from the pupa. We observed that proboscis self-assembly is facilitated by discharge of saliva. In contrast with vertebrate saliva, butterfly saliva is not slimy and is an almost inviscid, water-like fluid.

Fire ants perpetually rebuild sinking towers.

In the aftermath of a flood, fire ants, , cluster into temporary encampments. The encampments can contain hundreds of thousands of ants and reach over 30 ants high. How do ants build such tall structures without being crushed? In this combined experimental and theoretical study, we investigate the shape and rate of construction of ant towers around a central support.

X-Ray Computed Tomography Reveals the Response of Root System Architecture to Soil Texture.

Root system architecture (RSA) impacts plant fitness and crop yield by facilitating efficient nutrient and water uptake from the soil. A better understanding of the effects of soil on RSA could improve crop productivity by matching roots to their soil environment. We used x-ray computed tomography to perform a detailed three-dimensional quantification of changes in rice (Oryza sativa) RSA in response to the physical properties of a granular substrate.

Behavioral and mechanical determinants of collective subsurface nest excavation.

Collective construction of topologically complex structures is one of the triumphs of social behavior. For example, many ant species construct underground nests composed of networks of tunnels and chambers. Excavation by these 'superorganisms' depends on the biomechanics of substrate manipulation, the interaction of individuals, and media stability and cohesiveness.

Paradox of the drinking-straw model of the butterfly proboscis.

Fluid-feeding Lepidoptera use an elongated proboscis, conventionally modeled as a drinking straw, to feed from pools and films of liquid. Using the monarch butterfly, Danaus plexippus (Linnaeus), we show that the inherent structural features of the lepidopteran proboscis contradict the basic assumptions of the drinking-straw model. By experimentally characterizing permeability and flow in the proboscis, we show that tapering of the food canal in the drinking region increases resistance, significantly hindering the flow of fluid.

Meniscus formation in a capillary and the role of contact line friction.

We studied spontaneous formation of an internal meniscus by dipping glass capillaries of 25 μm to 350 μm radii into low volatile hexadecane and tributyl phosphate. X-ray phase contrast and high speed optical microscopy imaging were employed. We showed that the meniscus completes its formation when the liquid column is still shorter than the capillary radius.

Hydrophobic-hydrophilic dichotomy of the butterfly proboscis.

Mouthparts of fluid-feeding insects have unique material properties with no human-engineered analogue: the feeding devices acquire sticky and viscous liquids while remaining clean. We discovered that the external surface of the butterfly proboscis has a sharp boundary separating a hydrophilic drinking region and a hydrophobic non-drinking region. The structural arrangement of the proboscis provides the basis for the wetting dichotomy.

Climbing, falling, and jamming during ant locomotion in confined environments.

Locomotion emerges from effective interactions of an individual with its environment. Principles of biological terrestrial locomotion have been discovered on unconfined vertical and horizontal substrates. However, a diversity of organisms construct, inhabit, and move within confined spaces.

Nanoporous artificial proboscis for probing minute amount of liquids.

We describe a method of fabrication of nanoporous flexible probes which work as artificial proboscises. The challenge of making probes with fast absorption rates and good retention capacity was addressed theoretically and experimentally. This work shows that the probe should possess two levels of pore hierarchy: nanopores are needed to enhance the capillary action and micrometer pores are required to speed up fluid transport.

Butterfly proboscis: combining a drinking straw with a nanosponge facilitated diversification of feeding habits.

The ability of Lepidoptera, or butterflies and moths, to drink liquids from rotting fruit and wet soil, as well as nectar from floral tubes, raises the question of whether the conventional view of the proboscis as a drinking straw can account for the withdrawal of fluids from porous substrates or of films and droplets from floral tubes. We discovered that the proboscis promotes capillary pull of liquids from diverse sources owing to a hierarchical pore structure spanning nano- and microscales. X-ray phase-contrast imaging reveals that Plateau instability causes liquid bridges to form in the food canal, which are transported to the gut by the muscular sucking pump in the head.

Elastocapillarity: stress transfer through fibrous probes in wicking experiments.

Current advances in the manufacture of nanoporous and nanofibrous materials with high absorption capacity open up new opportunities for the development of fiber-based probes and sensors. Pore structures of these materials can be designed to provide high suction pressure and fast wicking. During wicking, due to the strong capillary action, liquids exert stresses on the fiber network.