Benjamin Alexander Palmer

Benjamin Alexander Palmer
Ben-Gurion University of the Negev | bgu · Department of Chemistry

PhD

About

48
Publications
6,128
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
613
Citations
Introduction
My lab studies the chemistry, biology and physics underlying some amazing optical phenomena in animals, relating to color and in vision. We are fascinated by how animals use crystalline materials to produce these optical effects and have three main research directions: (i) the discovery of optically functional bio-crystals, (ii) understanding mechanisms of biologically-controlled crystallization and (iii) bio-inspired optical materials. Check out our website: https://www.benjaminpalmerlab.com
Additional affiliations
October 2008 - March 2012
Cardiff University
Position
  • PhD Student

Publications

Publications (48)
Article
Full-text available
Spectacular colors and visual phenomena in animals are produced by light interference from highly reflective guanine crystals. Little is known about how organisms regulate crystal morphology to tune the optics of these systems. By following guanine crystal formation in developing spiders, we elucidate a crystallization mechanism. Guanine crystalliz...
Article
Full-text available
Highly reflective crystals of the nucleotide base guanine are widely distributed in animal coloration and visual systems. Organisms precisely control the morphology and organization of the crystals to optimize different optical effects, but little is known about how this is achieved. Here we examine a fundamental question that has remained unanswer...
Preprint
Many animals undergo dramatic changes in colour during development1,2. Changes in predation risk during ontogeny are associated with spectacular switches in defensive colours, typically involving the replacement of skin or the production of new pigment cells3. Ontogenetic colour systems are ideal models for understanding the evolution and formation...
Article
Highly reflective crystals of small organic molecules are the functional materials in a wide variety of optical systems in animals. We present a perspective on this field of organic biomineralization and review evidence for the widespread distribution of organic crystals in animals. These materials were, until recently, largely overlooked principal...
Article
Recent studies of optical reflectors as part of the vision apparatus in the eyes of decapod crustaceans revealed assemblies of nanoscale spherulites - spherical core-shell nanoparticles with radial birefringence. Simulations performed on the system highlighted the advantages of optical anisotropy in enhancing the functionality of these structures....
Article
Photonic structures are responsible for the vivid colors of many animals, and also serve as reflectors and filters in vision. Our recent work has explored the core–shell photonic nanostructures involved in the eyes of several decapod crustaceans, and motivates further research into exploiting spatial variation of birefringence in designing ultrathi...
Article
Various material-strengthening strategies have evolved in the cuticle and the feeding tools of arthropods. Of particular interest is the crustacean mandible, which is frequently reinforced with calcium phosphate, giving a minerology similar to that of human bones and teeth. We report here a biological strengthening method of apatite by Zn substitut...
Article
Reflective assemblies of high refractive index organic crystals are used to produce striking optical phenomena in organisms based on light reflection and scattering. In aquatic animals, organic crystal-based reflectors are used both for image-formation and to increase photon-capture. Here we report the characterization of a poorly-documented reflec...
Article
Full-text available
Spectacular natural optical phenomena are produced by highly reflective assemblies of organic crystals. Here we show how the tapetum reflector in a shrimp eye is constructed from arrays of spherical isoxanthopterin nanoparticles and relate the particle properties to their optical function. The nanoparticles are composed of single-crystal isoxanthop...
Article
Animals use photonic structures in their eyes to form images, enhance sensitivity and provide camouflage. A recent exciting discovery shows that the eyes of some larval mantis shrimp possess photonic crystals that function as color filters to detect bioluminescence.
Article
Full-text available
In a recent paper (Couzi et al. 2018 R. Soc. open sci. 5 , 180058. ( doi:10.1098/rsos.180058 )), we proposed a new phenomenological model to account for the I↔II↔“III” phase sequence in incommensurate n -alkane/urea inclusion compounds, which represents an alternative interpretation to that proposed in work of Toudic et al. In a Comment (Toudic et...
Article
Until recently it was thought that the only optical function of pteridines in biology was to act as light-absorbing pigments, but a recent report by some of us revealed that crystalline isoxanthopterin is a reflector in the eyes of decapod crustaceans. Here, we report the formation of crystalline isoxanthopterin synthetically from the polar dimethy...
Article
Full-text available
The X-ray Birefringence Imaging (XBI) technique, first reported in 2014, is a sensitive method for spatially resolved mapping of the local orientational properties of anisotropic materials. We report the first...
Article
Full-text available
Organic crystals are of primary importance in pharmaceuticals, functional materials, and biological systems; however, organic crystallization mechanisms are not well-understood. It has been recognized that "nonclassical" organic crystallization from solution involving transient amorphous precursors is ubiquitous. Understanding how these precursors...
Article
Vision mechanisms in animals, especially those living in water, are diverse. Many eyes have reflective elements that consist of multilayers of nanometer‐sized crystalline plates, composed of organic molecules. The crystal multilayer assemblies owe their enhanced reflectivity to the high refractive indices of the crystals in preferred crystallograph...
Article
The eyes of some aquatic animals form images through reflective optics. Shrimp, lobsters, crayfish, and prawns possess reflecting superposition compound eyes, composed of thousands of square-faceted eye units (ommatidia). Mirrors in the upper part of the eye (the distal mirror) reflect light collected from many ommatidia onto the photosensitive ele...
Preprint
The eyes of some aquatic animals form images through reflective optics. Shrimp, lobsters, crayfish and prawns possess reflecting superposition compound eyes, composed of thousands of square-faceted eye-units (ommatidia). Mirrors in the upper part of the eye (the distal mirror) reflect light collected from many ommatidia onto the underlying photosen...
Article
Scallops possess a visual system comprising up to 200 eyes, each containing a concave mirror rather than a lens to focus light. The hierarchical organization of the multilayered mirror is controlled for image formation, from the component guanine crystals at the nanoscale to the complex three-dimensional morphology at the millimeter level. The laye...
Article
Fish-scale iridophore cells deposit guanine crystals and assemble them into multilayer reflectors to produce silvery reflectance. The crystal orientation controls the reflective properties of the fish scales, but little is known about the degree of orientation of the guanine crystals and whether this orientation is pre-determined at the level of an...
Article
Guanine crystals are widely used in nature as components of multilayer reflectors. Guanine-based reflective systems found in the copepod cuticle and in the mirror of the scallop eye are unique in that the multilayered reflectors are tiled to form a contiguous packed array. In the copepod cuticle, hexagonal crystals are closely packed to produce bri...
Article
Guanine crystals are widely used in nature as components of multilayer reflectors. Guanine-based reflective systems found in the copepod cuticle and in the mirror of the scallop eye are unique in that the multilayered reflectors are tiled to form a contiguous packed array. In the copepod cuticle, hexagonal crystals are closely packed to produce bri...
Article
We demonstrate that measurements of X-ray linear dichroism are an effective method for determining bond orientations in disordered materials, by reporting the first observation of X-ray linear dichroism at the iodine L1-edge. The iodine-containing molecular solid studied in this work was the inclusion compound containing 4,4′-diiodobiphenyl guest m...
Article
Full-text available
Guanine crystals are widely used in nature to manipulate light. The first part of this feature article explores how organisms are able to construct an extraordinary array of optical "devices" including diffuse scatterers, broadband and narrowband reflectors, tunable photonic crystals, and image-forming mirrors by varying the size, morphology, and a...
Article
The prototypical family of incommensurate composite materials are the n-alkane/urea inclusion compounds, in which n-alkane guest molecules are arranged in a periodic manner along one-dimensional tunnels in a urea host structure, with an incommensurate relationship between the periodicities of the host and guest substructures along the tunnel. We de...
Conference Paper
Birefringence has been observed in anisotropic materials transmitting linearly polarized X-ray beams tuned close to an absorption edge of a specific element in the material. Synchrotron bending magnets provide X-ray beams of sufficiently high brightness and cross section for spatially resolved measurements of birefringence. The recently developed X...
Article
Full-text available
The fresh water fish neon tetra has the ability to change the structural color of its lateral stripe in response to a change in the light conditions, from blue-green in the light-adapted state to indigo in the dark-adapted state. The colors are produced by constructive interference of light reflected from stacks of intracellular guanine crystals, f...
Article
The fresh water fish neon tetra has the ability to change the structural color of its lateral stripe in response to a change in the light conditions, from blue-green in the light-adapted state to indigo in the dark-adapted state. The colors are produced by constructive interference of light reflected from stacks of intracellular guanine crystals, f...
Article
Full-text available
In the recently developed technique of X-ray Birefringence Imaging, molecular orientational order in anisotropic materials is studied by exploiting the birefringence of linearly polarized X-rays with energy close to an absorption edge of an element in the material. In the experimental setup, a vertically deflecting high-resolution double-crystal mo...
Article
The X-ray birefringence imaging (XBI) technique, reported very recently, is a sensitive tool for spatially resolved mapping of the local orientational properties of anisotropic materials. In this paper, we report the first XBI measurements on materials that undergo anisotropic molecular dynamics. Using incident linearly polarized X-rays with energy...
Article
The polarizing optical microscope has been used since the 19th century to study the structural anisotropy of materials, based on the phenomenon of optical birefringence. In contrast, the phenomenon of x-ray birefringence has been demonstrated only recently and has been shown to be a sensitive probe of the orientational properties of individual mole...
Article
We report four experimental strategies for controlling the three-dimensional arrangement of molecules in multi-component organic crystals, exploiting confocal Raman microspectrometry to quantify the three-dimensional spatial distributions. Specifically, we focus on controlling the distribution of two types of guest molecule in solid organic inclusi...
Article
Full-text available
Birefringence is the dependence of a material's refractive index on the direction of linear polarization. It induces a phase shift between two perpendicular polarization directions and thus couples linear and circular polarization states. Birefringence in x-ray absorption is as common as linear dichroism but is rarely discussed in the literature. W...
Article
While the phenomenon of birefringence is well-established in the case of visible radiation and is exploited in many fields (e.g., through the use of the polarizing optical microscope), the analogous phenomenon for X-rays has been a virtually neglected topic. Here, we demonstrate the scope and potential for exploiting X-ray birefringence to determin...
Chapter
This chapter focuses on chemical reactions occurring within solid organic inclusion compounds, encompassing a broad range of inclusion compounds and a wide variety of different reaction types, including reactions of the guest molecules (such as dimerization, polymerization, cyclization, isomerization, and decomposition), reactions involving the hos...
Article
Structural properties of the bromocyclohexane/thiourea inclusion compound have been determined using both single-crystal and powder X-ray diffraction over a range of temperatures above and below a first-order phase transition at 233 K in this material. The results demonstrate marked contrasts to the phase transition behavior in the prototypical cyc...
Article
Whereas the phenomenon of birefringence is well-established and widely applied in the case of linearly polarized visible light (for example, underpinning the use of the polarizing optical microscope), the study of birefringence using linearly polarized X-rays is an essentially unexplored field. To address this issue, we report a material that exhib...
Article
Full-text available
X-Ray diffraction studies reveal that the tunnel inclusion compound formed between 1-tert-butyl-4-iodobenzene and thiourea has an incommensurate relationship between the periodicities of the host and guest substructures along the tunnel axis, representing the first reported case of an incommensurate thiourea inclusion compound.
Article
Wie Baumringe zählen: Ein neue Strategie zur Untersuchung von Kristallwachstumsprozessen beruht auf der retrospektiven Analyse fertiger Kristalle. Die Zusammensetzung der wachsenden Kristalloberflächen variiert während des Kristallwachstums, während die Kristallstruktur unverändert bleibt, und die Zusammensetzungsverteilung im Kristall wird durch k...
Article
Cyclic voltammetry (CV) has been used to investigate the irreversible adsorption of ethyl 2-oxopropanoate (ethyl pyruvate (EtPy)) on well-defined Pt and Pd electrodes. Following dosing of EtPy at open circuit on Pt and Pd surfaces, adsorption was found to be structure sensitive with extensive chemisorption being exhibited at {110} and {100} terrace...

Network

Cited By

Projects

Project (1)
Project
Investigate application of structure-property relationships.