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Silvia Vignolini

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https://www.readbyqxmd.com/read/27805005/colour-formation-on-the-wings-of-the-butterfly-hypolimnas-salmacis-by-scale-stacking
#1
Radwanul Hasan Siddique, Silvia Vignolini, Carolin Bartels, Irene Wacker, Hendrik Hölscher
The butterfly genus Hypolimnas features iridescent blue colouration in some areas of its dorsal wings. Here, we analyse the mechanisms responsible for such colouration on the dorsal wings of Hypolimnas salmacis and experimentally demonstrate that the lower thin lamina in the white cover scales causes the blue iridescence. This outcome contradicts other studies reporting that the radiant blue in Hypolimnas butterflies is caused by complex ridge-lamellar architectures in the upper lamina of the cover scales. Our comprehensive optical study supported by numerical calculation however shows that scale stacking primarily induces the observed colour appearance of Hypolimnas salmacis...
November 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27786436/shape-memory-cellulose-based-photonic-reflectors
#2
André Espinha, Giulia Guidetti, Maria Concepcion Serrano, Bruno Frka-Petesic, Ahu Gümrah Dumanli, Wadood Y Hamad, Alvaro Blanco, Cefe Lopez, Silvia Vignolini
Bio-polymer based composites enable to combine different functionalities using renewable materials and cost-effective routes. Here we fabricate novel thermoresponsive photonic films combining cellulose nanocrystals (CNCs) with a polydiolcitrate elastomer exhibiting shape memory properties. In this composite, CNCs provide an intense structural coloration and improve the overall mechanical cohesion, while the elastomer drastically reduces the intrinsic brittleness of the photonic cellulose film and enables the shape memory effect...
October 27, 2016: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/27748533/flexible-photonic-cellulose-nanocrystal-films
#3
Giulia Guidetti, Siham Atifi, Silvia Vignolini, Wadood Y Hamad
The fabrication of self-assembled cellulose nanocrystal (CNC) films of tunable photonic and mechanical properties using a facile, green approach is demonstrated. The combination of tunable flexibility and iridescence can dramatically expand CNC coating and film barrier capabilities for paints and coating applications, sustainable consumer packaging products, as well as effective templates for photonic and optoelectronic materials and structures.
December 2016: Advanced Materials
https://www.readbyqxmd.com/read/27564644/hierarchical-self-assembly-of-cellulose-nanocrystals-in-a-confined-geometry
#4
Richard M Parker, Bruno Frka-Petesic, Giulia Guidetti, Gen Kamita, Gioele Consani, Chris Abell, Silvia Vignolini
Complex hierarchical architectures are ubiquitous in nature. By designing and controlling the interaction between elementary building blocks, nature is able to optimize a large variety of materials with multiple functionalities. Such control is, however, extremely challenging in man-made materials, due to the difficulties in controlling their interaction at different length scales simultaneously. Here, hierarchical cholesteric architectures are obtained by the self-assembly of cellulose nanocrystals within shrinking, micron-sized aqueous droplets...
September 27, 2016: ACS Nano
https://www.readbyqxmd.com/read/26139470/structural-colour-in-chondrus-crispus
#5
Chris J Chandler, Bodo D Wilts, Silvia Vignolini, Juliet Brodie, Ullrich Steiner, Paula J Rudall, Beverley J Glover, Thomas Gregory, Rachel H Walker
The marine world is incredibly rich in brilliant and intense colours. Photonic structures are found in many different species and provide extremely complex optical responses that cannot be achieved solely by pigments. In this study we examine the cuticular structure of the red alga Chondrus crispus (Irish Moss) using anatomical and optical approaches. We experimentally measure the optical response of the multilayer structure in the cuticle. Using finite-difference time-domain modelling, we demonstrate conclusively for the first time that the dimensions and organisation of lamellae are responsible for the blue structural colouration on the surface of the fronds...
2015: Scientific Reports
https://www.readbyqxmd.com/read/25856171/block-copolymer-self-assembly-for-nanophotonics
#6
Morgan Stefik, Stefan Guldin, Silvia Vignolini, Ulrich Wiesner, Ullrich Steiner
The ability to control and modulate the interaction of light with matter is crucial to achieve desired optical properties including reflection, transmission, and selective polarization. Photonic materials rely upon precise control over the composition and morphology to establish periodic interactions with light on the wavelength and sub-wavelength length scales. Supramolecular assembly provides a natural solution allowing the encoding of a desired 3D architecture into the chemical building blocks and assembly conditions...
August 7, 2015: Chemical Society Reviews
https://www.readbyqxmd.com/read/25524506/erratum-bright-white-beetle-scales-optimise-multiple-scattering-of-light
#7
Matteo Burresi, Lorenzo Cortese, Lorenzo Pattelli, Mathias Kolle, Peter Vukusic, Diederik S Wiersma, Ullrich Steiner, Silvia Vignolini
No abstract text is available yet for this article.
2014: Scientific Reports
https://www.readbyqxmd.com/read/25474563/a-high-transmission-wave-guide-wire-network-made-by-self-assembly
#8
Stefano Salvatore, Silvia Vignolini, Julian Philpott, Morgan Stefik, Ulrich Wiesner, Jeremy J Baumberg, Ullrich Steiner
Polymer self-assembly of a 3D continuous gyroid morphology was replicated into a network consisting of hollow gold struts. This was achieved by first replicating a gyroid structured film into nickel. The Ni network was employed as an electrode for electrochemical Au deposition, followed by the removal of Ni. The resulting hollow network of plasmonic gold exhibited a substantial optical transmission enhancement by a factor of nearly 3, compared to a network of full Au struts. The overall transmission across the hollow wave-guide morphology depends sensitively on the wall-thickness of the hollow struts down to 1 nm...
January 21, 2015: Nanoscale
https://www.readbyqxmd.com/read/25123449/bright-white-beetle-scales-optimise-multiple-scattering-of-light
#9
Matteo Burresi, Lorenzo Cortese, Lorenzo Pattelli, Mathias Kolle, Peter Vukusic, Diederik S Wiersma, Ullrich Steiner, Silvia Vignolini
Whiteness arises from diffuse and broadband reflection of light typically achieved through optical scattering in randomly structured media. In contrast to structural colour due to coherent scattering, white appearance generally requires a relatively thick system comprising randomly positioned high refractive-index scattering centres. Here, we show that the exceptionally bright white appearance of Cyphochilus and Lepidiota stigma beetles arises from a remarkably optimised anisotropy of intra-scale chitin networks, which act as a dense scattering media...
August 15, 2014: Scientific Reports
https://www.readbyqxmd.com/read/25040014/the-flower-of-hibiscus-trionum-is-both-visibly-and-measurably-iridescent
#10
Silvia Vignolini, Edwige Moyroud, Thomas Hingant, Hannah Banks, Paula J Rudall, Ullrich Steiner, Beverley J Glover
Living organisms can use minute structures to manipulate the reflection of light and display colours based on interference. There has been debate in recent literature over whether the diffractive optical effects produced by epoxy replicas of petals with folded cuticles persist and induce iridescence in the original flowers when the effects of petal pigment and illumination are taken into account. We explored the optical properties of the petal of Hibiscus trionum by macro-imaging, scanning and transmission electron microscopy, and visible and ultraviolet (UV) angle-resolved spectroscopy of the petal...
January 2015: New Phytologist
https://www.readbyqxmd.com/read/25007291/digital-color-in-cellulose-nanocrystal-films
#11
Ahu Gümrah Dumanli, Hanne M van der Kooij, Gen Kamita, Erwin Reisner, Jeremy J Baumberg, Ullrich Steiner, Silvia Vignolini
Cellulose nanocrystals (CNCs) form chiral nematic phases in aqueous suspensions that can be preserved upon evaporation of water. The resulting films show an intense directional coloration determined by their microstructure. Here, microreflection experiments correlated with analysis of the helicoidal nanostructure of the films reveal that the iridescent colors and the ordering of the individual nematic layers are strongly dependent on the polydispersity of the size distribution of the CNCs. We show how this affects the self-assembly process, and hence multidomain color formation in such bioinspired structural films...
August 13, 2014: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/24836733/engineering-of-light-confinement-in-strongly-scattering-disordered-media
#12
Francesco Riboli, Niccolò Caselli, Silvia Vignolini, Francesca Intonti, Kevin Vynck, Pierre Barthelemy, Annamaria Gerardino, Laurent Balet, Lianhe H Li, Andrea Fiore, Massimo Gurioli, Diederik S Wiersma
Disordered photonic materials can diffuse and localize light through random multiple scattering, offering opportunities to study mesoscopic phenomena, control light-matter interactions, and provide new strategies for photonic applications. Light transport in such media is governed by photonic modes characterized by resonances with finite spectral width and spatial extent. Considerable steps have been made recently towards control over the transport using wavefront shaping techniques. The selective engineering of individual modes, however, has been addressed only theoretically...
July 2014: Nature Materials
https://www.readbyqxmd.com/read/23883949/analysing-photonic-structures-in-plants
#13
Silvia Vignolini, Edwige Moyroud, Beverley J Glover, Ullrich Steiner
The outer layers of a range of plant tissues, including flower petals, leaves and fruits, exhibit an intriguing variation of microscopic structures. Some of these structures include ordered periodic multilayers and diffraction gratings that give rise to interesting optical appearances. The colour arising from such structures is generally brighter than pigment-based colour. Here, we describe the main types of photonic structures found in plants and discuss the experimental approaches that can be used to analyse them...
October 6, 2013: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/23553887/tunable-3d-extended-self-assembled-gold-metamaterials-with-enhanced-light-transmission
#14
Stefano Salvatore, Angela Demetriadou, Silvia Vignolini, Sang Soon Oh, Sebastian Wuestner, Nataliya A Yufa, Morgan Stefik, Ulrich Wiesner, Jeremy J Baumberg, Ortwin Hess, Ullrich Steiner
The optical properties of metamaterials made by block copolymer self-assembly are tuned by structural and environmental variations. The plasma frequency red-shifts with increasing lattice constant and blue-shifts as the network filling fraction increases. Infiltration with dielectric liquids leads also to a red-shift of the plasma edge. A 300 nm-thick slab of gyroid-structured gold has a remarkable transmission of 20%.
May 21, 2013: Advanced Materials
https://www.readbyqxmd.com/read/23420080/the-influence-of-pigmentation-patterning-on-bumblebee-foraging-from-flowers-of-antirrhinum-majus
#15
Heather M Whitney, Georgina Milne, Sean A Rands, Silvia Vignolini, Cathie Martin, Beverley J Glover
Patterns of pigmentation overlying the petal vasculature are common in flowering plants and have been postulated to play a role in pollinator attraction. Previous studies report that such venation patterning is significantly more attractive to bee foragers in the field than ivory or white flowers without veins. To dissect the ways in which venation patterning of pigment can influence bumblebee behaviour, we investigated the response of flower-naïve individuals of Bombus terrestris to veined, ivory and red near-isogenic lines of Antirrhinum majus...
March 2013: Die Naturwissenschaften
https://www.readbyqxmd.com/read/23269848/buckling-as-an-origin-of-ordered-cuticular-patterns-in-flower-petals
#16
Rea L Antoniou Kourounioti, Leah R Band, John A Fozard, Anthony Hampstead, Anna Lovrics, Edwige Moyroud, Silvia Vignolini, John R King, Oliver E Jensen, Beverley J Glover
The optical properties of plant surfaces are strongly determined by the shape of epidermal cells and by the patterning of the cuticle on top of the cells. Combinations of particular cell shapes with particular nanoscale structures can generate a wide range of optical effects. Perhaps most notably, the development of ordered ridges of cuticle on top of flat petal cells can produce diffraction-grating-like structures. A diffraction grating is one of a number of mechanisms known to produce 'structural colours', which are more intense and pure than chemical colours and can appear iridescent...
March 6, 2013: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/23043621/the-mirror-crack-d-both-pigment-and-structure-contribute-to-the-glossy-blue-appearance-of-the-mirror-orchid-ophrys-speculum
#17
Silvia Vignolini, Matthew P Davey, Richard M Bateman, Paula J Rudall, Edwige Moyroud, Julia Tratt, Svante Malmgren, Ullrich Steiner, Beverley J Glover
The Mediterranean orchid genus Ophrys is remarkable for its pseudocopulatory pollination mechanism; naïve male pollinators are attracted to the flowers by olfactory, visual and tactile cues. The most striking visual cue is a highly reflective, blue speculum region at the centre of the labellum, which mimics the corresponding female insect and reaches its strongest development in the mirror orchid, O. speculum. We explored the structure and properties of the much-discussed speculum by scanning and transmission electron microscopic examination of its ultrastructure, visible and ultraviolet (UV) angle-resolved spectrophotometry of the intact tissue, and mass spectrometry of extracted pigments...
December 2012: New Phytologist
https://www.readbyqxmd.com/read/23019355/pointillist-structural-color-in-pollia-fruit
#18
Silvia Vignolini, Paula J Rudall, Alice V Rowland, Alison Reed, Edwige Moyroud, Robert B Faden, Jeremy J Baumberg, Beverley J Glover, Ullrich Steiner
Biological communication by means of structural color has existed for at least 500 million years. Structural color is commonly observed in the animal kingdom, but has been little studied in plants. We present a striking example of multilayer-based strong iridescent coloration in plants, in the fruit of Pollia condensata. The color is caused by Bragg reflection of helicoidally stacked cellulose microfibrils that form multilayers in the cell walls of the epicarp. We demonstrate that animals and plants have convergently evolved multilayer-based photonic structures to generate colors using entirely distinct materials...
September 25, 2012: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/22828626/biomimetic-layer-by-layer-assembly-of-artificial-nacre
#19
Alexander Finnemore, Pedro Cunha, Tamaryn Shean, Silvia Vignolini, Stefan Guldin, Michelle Oyen, Ullrich Steiner
Nacre is a technologically remarkable organic-inorganic composite biomaterial. It consists of an ordered multilayer structure of crystalline calcium carbonate platelets separated by porous organic layers. This microstructure exhibits both optical iridescence and mechanical toughness, which transcend those of its constituent components. Replication of nacre is essential for understanding this complex biomineral, and paves the way for tough coatings fabricated from cheap abundant materials. Fabricating a calcitic nacre imitation with biologically similar optical and mechanical properties will likely require following all steps taken in biogenic nacre synthesis...
2012: Nature Communications
https://www.readbyqxmd.com/read/22461255/absorption-and-bioeffects-of-an-isoflavone-based-supplementation-in-postmenopausal-women
#20
Barbara Pampaloni, Silvia Bartolini, Elisa Bartolini, Silva Ottanelli, Laura Masi, Annalisa Romani, Annalisa Tanini, Pamela Vignolini, Maria Luisa Brandi
Epidemiological studies suggest that consumption of isoflavones rich diets can improve several postmenopausal complications. The aim of this study was to investigate the absorption and the efficacy of isoflavonic supplementation in the treatment of menopausal symptoms.36 postmenopausal women received 75 mg/day of isoflavones in the form of tablets, for six months. 21 subjects concluded the treatment. Plasmatic and urinary samples were collected before and after the treatment, along with a dietary interview...
September 2009: Clinical Cases in Mineral and Bone Metabolism
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