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https://www.readbyqxmd.com/read/28630681/imaging-optical-scattering-of-butterfly-wing-scales-with-a-microscope
#1
Jinxin Fu, Beom-Jin Yoon, Jung Ok Park, Mohan Srinivasarao
A new optical method is proposed to investigate the reflectance of structurally coloured objects, such as Morpho butterfly wing scales and cholesteric liquid crystals. Using a reflected-light microscope and a digital single-lens reflex (DSLR) camera, we have successfully measured the two-dimensional reflection pattern of individual wing scales of Morpho butterflies. We demonstrate that this method enables us to measure the bidirectional reflectance distribution function (BRDF). The scattering image observed in the back focal plane of the objective is projected onto the camera sensor by inserting a Bertrand lens in the optical path of the microscope...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630680/purely-entropic-self-assembly-of-the-bicontinuous-ia3d-gyroid-phase-in-equilibrium-hard-pear-systems
#2
Philipp W A Schönhöfer, Laurence J Ellison, Matthieu Marechal, Douglas J Cleaver, Gerd E Schröder-Turk
We investigate a model of hard pear-shaped particles which forms the bicontinuous Ia[Formula: see text]d structure by entropic self-assembly, extending the previous observations of Barmes et al. (2003 Phys. Rev. E68, 021708. (doi:10.1103/PhysRevE.68.021708)) and Ellison et al. (2006 Phys. Rev. Lett.97, 237801. (doi:10.1103/PhysRevLett.97.237801)). We specifically provide the complete phase diagram of this system, with global density and particle shape as the two variable parameters, incorporating the gyroid phase as well as disordered isotropic, smectic and nematic phases...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630679/molecular-interactions-of-amyloid-nanofibrils-with-biological-aggregation-modifiers-implications-for-cytotoxicity-mechanisms-and-biomaterial-design
#3
REVIEW
Durga Dharmadana, Nicholas P Reynolds, Charlotte E Conn, Céline Valéry
Amyloid nanofibrils are ubiquitous biological protein fibrous aggregates, with a wide range of either toxic or beneficial activities that are relevant to human disease and normal biology. Protein amyloid fibrillization occurs via nucleated polymerization, through non-covalent interactions. As such, protein nanofibril formation is based on a complex interplay between kinetic and thermodynamic factors. The process entails metastable oligomeric species and a highly thermodynamically favoured end state. The kinetics, and the reaction pathway itself, can be influenced by third party moieties, either molecules or surfaces...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630678/on-the-colour-of-wing-scales-in-butterflies-iridescence-and-preferred-orientation-of-single-gyroid-photonic-crystals
#4
Robert W Corkery, Eric C Tyrode
Lycaenid butterflies from the genera Callophrys, Cyanophrys and Thecla have evolved remarkable biophotonic gyroid nanostructures within their wing scales that have only recently been replicated by nanoscale additive manufacturing. These nanostructures selectively reflect parts of the visible spectrum to give their characteristic non-iridescent, matte-green appearance, despite a distinct blue-green-yellow iridescence predicted for individual crystals from theory. It has been hypothesized that the organism must achieve its uniform appearance by growing crystals with some restrictions on the possible distribution of orientations, yet preferential orientation observed in Callophrys rubi confirms that this distribution need not be uniform...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630677/non-lamellar-lipid-assembly-at-interfaces-controlling-layer-structure-by-responsive-nanogel-particles
#5
Aleksandra P Dabkowska, Maria Valldeperas, Christopher Hirst, Costanza Montis, Gunnar K Pálsson, Meina Wang, Sofi Nöjd, Luigi Gentile, Justas Barauskas, Nina-Juliane Steinke, Gerd E Schroeder-Turk, Sebastian George, Maximilian W A Skoda, Tommy Nylander
Biological membranes do not only occur as planar bilayer structures, but depending on the lipid composition, can also curve into intriguing three-dimensional structures. In order to fully understand the biological implications as well as to reveal the full potential for applications, e.g. for drug delivery and other biomedical devices, of such structures, well-defined model systems are required. Here, we discuss the formation of lipid non-lamellar liquid crystalline (LC) surface layers spin-coated from the constituting lipids followed by hydration of the lipid layer...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630676/scaling-properties-of-ageing-orientation-fluctuations-in-stripe-phases
#6
Christian Riesch, Günter Radons, Robert Magerle
We investigate the non-equilibrium dynamics of an ordered stripe-forming system free of topological defects. In particular, we study the ageing and the coarsening of orientation fluctuations parallel and perpendicular to the stripes via computer simulations based on a minimal phase-field model (model B with Coulomb interactions). Under the influence of noise, the stripe orientation field develops fluctuations parallel to the stripes, with the dominant modulation length λ*∥ increasing with time t as λ*∥ ∼ t(1/4) and the correlation length perpendicular to the stripes ξ(⊥)θ increasing as ξ(⊥)θ ∼ t(1/2)...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630675/how-geometric-frustration-shapes-twisted-fibres-inside-and-out-competing-morphologies-of-chiral-filament-assembly
#7
Douglas M Hall, Gregory M Grason
Chirality frustrates and shapes the assembly of flexible filaments in rope-like, twisted bundles and fibres by introducing gradients of both filament shape (i.e. curvature) and packing throughout the structure. Previous models of chiral filament bundle formation have shown that this frustration gives rise to several distinct morphological responses, including self-limiting bundle widths, anisotropic domain (tape-like) formation and topological defects in the lateral inter-filament order. In this paper, we employ a combination of continuum elasticity theory and discrete filament bundle simulations to explore how these distinct morphological responses compete in the broader phase diagram of chiral filament assembly...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630674/cation-effects-on-haemoglobin-aggregation-balance-of-chemisorption-against-physisorption-of-ions
#8
Drew F Parsons, Timothy T Duignan, Andrea Salis
A theoretical model of haemoglobin is presented to explain an anomalous cationic Hofmeister effect observed in protein aggregation. The model quantifies competing proposed mechanisms of non-electrostatic physisorption and chemisorption. Non-electrostatic physisorption is stronger for larger, more polarizable ions with a Hofmeister series Li(+)< K(+)< Cs(+). Chemisorption at carboxylate groups is stronger for smaller kosmotropic ions, with the reverse series Li(+) > K(+) > Cs(+). We assess aggregation using second virial coefficients calculated from theoretical protein-protein interaction energies...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630673/optimal-packings-of-three-arm-star-polyphiles-from-tricontinuous-to-quasi-uniformly-striped-bicontinuous-forms
#9
Liliana de Campo, Toen Castle, Stephen T Hyde
Star-shaped molecules with three mutually immiscible arms self-assemble to form a variety of novel structures, with conformations that attempt to minimize interfacial area between the domains composed of the different arms. The geometric frustration caused by the joining of these arms at a common centre limits the size and shape of each domain, encouraging the creation of complex and interesting solutions. Some solutions are tricontinuous, and these solutions (and others) share aspects of bicontinuous structures with amphiphilic assemblies as similar molecular segregation factors are at work...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630672/circularly-polarized-reflection-from-the-scarab-beetle-chalcothea-smaragdina-light-scattering-by-a-dual-photonic-structure
#10
Luke T McDonald, Ewan D Finlayson, Bodo D Wilts, Pete Vukusic
Helicoidal architectures comprising various polysaccharides, such as chitin and cellulose, have been reported in biological systems. In some cases, these architectures exhibit stunning optical properties analogous to ordered cholesteric liquid crystal phases. In this work, we characterize the circularly polarized reflectance and optical scattering from the cuticle of the beetle Chalcothea smaragdina (Coleoptera: Scarabaeidae: Cetoniinae) using optical experiments, simulations and structural analysis. The selective reflection of left-handed circularly polarized light is attributed to a Bouligand-type helicoidal morphology within the beetle's exocuticle...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630671/bsla-stabilized-emulsion-droplets-with-designed-microstructure
#11
Keith M Bromley, Cait E MacPhee
Emulsions are a central component of many modern formulations in food, pharmaceuticals, agrichemicals and personal care products. The droplets in these formulations are limited to being spherical as a consequence of the interfacial tension between the dispersed phase and continuous phase. The ability to control emulsion droplet morphology and stabilize non-spherical droplets would enable the modification of emulsion properties such as stability, substrate binding, delivery rate and rheology. One way of controlling droplet microstructure is to apply an elastic film around the droplet to prevent it from relaxing into a sphere...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630670/universal-structure-motifs-in-biominerals-a-lesson-from-nature-for-the-efficient-design-of-bioinspired-functional-materials
#12
REVIEW
Joe Harris, Corinna F Böhm, Stephan E Wolf
Biominerals are typically indispensable structures for their host organism in which they serve varying functions, such as mechanical support and protection, mineral storage, detoxification site, or as a sensor or optical guide. In this perspective article, we highlight the occurrence of both structural diversity and uniformity within these biogenic ceramics. For the first time, we demonstrate that the universality-diversity paradigm, which was initially introduced for proteins by Buehler et al. (Cranford & Buehler 2012 Biomateriomics; Cranford et al...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630669/straight-round-the-twist-frustration-and-chirality-in-smectics-a
#13
Elisabetta A Matsumoto, Randall D Kamien, Gareth P Alexander
Frustration is a powerful mechanism in condensed matter systems, driving both order and complexity. In smectics, the frustration between macroscopic chirality and equally spaced layers generates textures characterized by a proliferation of defects. In this article, we study several different ground states of the chiral Landau-de Gennes free energy for a smectic liquid crystal. The standard theory finds the twist grain boundary (TGB) phase to be the ground state for chiral type II smectics. However, for very highly chiral systems, the hierarchical helical nanofilament phase can form and is stable over the TGB...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630668/competition-brings-out-the-best-modelling-the-frustration-between-curvature-energy-and-chain-stretching-energy-of-lyotropic-liquid-crystals-in-bicontinuous-cubic-phases
#14
Hao Chen, Chenyu Jin
It is commonly considered that the frustration between the curvature energy and the chain stretching energy plays an important role in the formation of lyotropic liquid crystals in bicontinuous cubic phases. Theoretic and numeric calculations were performed for two extreme cases: parallel surfaces eliminate the variance of the chain length; constant mean curvature surfaces eliminate the variance of the mean curvature. We have implemented a model with Brakke's Surface Evolver which allows a competition between the two variances...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630667/evaluation-of-radical-scavenging-system-in-amoeba-chaos-carolinense-during-nutrient-deprivation
#15
Yuru Deng, Edlyn Li-Hui Lee, Ketpin Chong, Zakaria A Almsherqi
The frequent appearance of non-lamellar membrane arrangements such as cubic membranes (CMs) in cells under stressed or pathological conditions points to an intrinsic cellular response mechanism. CM represents highly curved, three-dimensional nano-periodic structures that correspond to mathematically well-defined triply periodic minimal surfaces. Specifically, cellular membrane may transform into CM organization in response to pathological, inflammatory and oxidative stress conditions. CM organization, thus, may provide an advantage to cope with various types of stress...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630666/curvature-driven-motion-of-a-bubble-in-a-toroidal-hele-shaw-cell
#16
A Mughal, S J Cox, G E Schröder-Turk
We investigate the equilibrium properties of a single area-minimizing bubble trapped between two narrowly separated parallel curved plates. We begin with the case of a bubble trapped between concentric spherical plates. We develop a model which shows that the surface energy of the bubble is lower when confined between spherical plates than between flat plates. We confirm our findings by comparing against Surface Evolver simulations. We then derive a simple model for a bubble between arbitrarily curved parallel plates...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28479987/correction-to-on-the-possibility-or-lack-thereof-of-agreement-between-experiment-and-computation-of-flows-over-wings-at-moderate-reynolds-number
#17
J Tank, L Smith, G R Spedding
[This corrects the article DOI: 10.1098/rsfs.2016.0076.].
June 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28479986/phylogenetic-origins-of-biological-cognition-convergent-patterns-in-the-early-evolution-of-learning
#18
REVIEW
Marc van Duijn
Various forms of elementary learning have recently been discovered in organisms lacking a nervous system, such as protists, fungi and plants. This finding has fundamental implications for how we view the role of convergent evolution in biological cognition. In this article, I first review the evidence for basic forms of learning in aneural organisms, focusing particularly on habituation and classical conditioning and considering the plausibility for convergent evolution of these capacities. Next, I examine the possible role of convergent evolution regarding these basic learning abilities during the early evolution of nervous systems...
June 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28479985/sampling-and-tracking-a-changing-environment-persistence-and-reward-in-the-foraging-decisions-of-bumblebees
#19
Aimee S Dunlap, Daniel R Papaj, Anna Dornhaus
The question of when to collect new information and how to apply that information is central to much of behaviour. Theory suggests that the value of collecting information, or sampling, depends on environmental persistence and on the relative costs of making wrong decisions. However, empirical tests of how these variables interact are lacking. We tested whether bumblebee foraging decisions are indeed influenced by these two factors. We gave bees repeated choices between a resource providing a steady, mediocre reward and a resource fluctuating between a low reward and a high reward...
June 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28479984/convergent-minds-some-questions-about-mental-evolution
#20
Matt Cartmill
In investigating convergent minds, we need to be sure that the things we are looking at are both minds and convergent. In determining whether a shared character state represents a convergence between two organisms, we must know the wider distribution and primitive state of that character so that we can map that character and its state transitions onto a phylogenetic tree. When we do this, some apparently primitive shared traits may prove to represent convergent losses of cognitive capacities. To avoid having to talk about the minds of plants and paramecia, we need to go beyond assessments of behaviourally defined cognition to ask questions about mind in the primary sense of the word, defined by the presence of mental events and consciousness...
June 6, 2017: Interface Focus
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