Publications

Calcium carbonate polyamorphism and its role in biomineralization: How many amorphous calcium carbonates are there?, JHE Cartwright, AG Checa, JD Gale, D Gebauer, & CI Sainz-Díaz, Angewandte Chemie, 2012.

Mon, 5 Nov 2012 18:45:20 +0100

Although the polymorphism of calcium carbonate is well known, and its polymorphs—calcite, aragonite, and vaterite—have been highly studied in the context of biomineralization, polyamorphism is a much more recently discovered phenomenon, and the existence of more than one amorphous phase of calcium carbonate in biominerals has only very recently been understood. Here we summarize what is known about polyamorphism in calcium carbonate as well as what is understood about the role of amorphous calcium carbonate in biominerals. We show that consideration of the amorphous forms of calcium carbonate within the physical notion of polyamorphism leads to new insights when it comes to the mechanisms by which polymorphic structures can evolve in the first place. This not only has implications for our understanding of biomineralization, but also of the means by which crystallization may be controlled in medical, pharmaceutical, and industrial contexts.

Crystal growth as an excitable medium, JHE Cartwright, AG Checa, B Escribano, & CI Sainz-Díaz, Phil. Trans. Roy. Soc. A 370, 2866–2876, 2012.

Fri, 25 May 2012 18:38:33 +0200

Crystal growth has been widely studied for many years, and, since the pioneering work of Burton, Cabrera and Frank, spirals and target patterns on the crystal surface have been understood as forms of tangential crystal growth mediated by defects and by two- dimensional nucleation. Similar spirals and target patterns are ubiquitous in physical systems describable as excitable media. Here, we demonstrate that this is not merely a superficial resemblance, that the physics of crystal growth can be set within the framework of an excitable medium, and that appreciating this correspondence may prove useful to both fields. Apart from solid crystals, we discuss how our model applies to the biomaterial nacre, formed by layer growth of a biological liquid crystal.

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Beyond crystals: the dialectic of materials and information JHE Cartwright & AL Mackay, Phil. Trans. Roy. Soc. A 370, 2807–2822, 2012.

Fri, 25 May 2012 18:34:11 +0200

We argue for a convergence of crystallography, materials science and biology, that will come about through asking materials questions about biology and biological questions about materials, illuminated by considerations of information. The complex structures now being studied in biology and produced in nanotechnology have outstripped the framework of classical crystallography, and a variety of organizing concepts are now taking shape into a more modern and dynamic science of structure, form and function. Absolute stability and equilibrium are replaced by metastable structures existing in a flux of energy-carrying information and moving within an energy landscape of complex topology. Structures give place to processes and processes to systems. The fundamental level is that of atoms. As smaller and smaller groups of atoms are used for their physical properties, quantum effects become important; already we see quantum computation taking shape. Concepts move towards those in life with the emergence of specifically informational structures. We now see the possibility of the artificial construction of a synthetic living system, different from biological life, but having many or all of the same properties. Interactions are essentially nonlinear and collective. Structures begin to have an evolutionary history with episodes of symbiosis. Underlying all the structures are constraints of time and space. Through hierarchization, a more general principle than the periodicity of crystals, structures may be found within structures on different scales. We must integrate unifying concepts from dynamical systems and information theory to form a coherent language and science of shape and structure beyond crystals. To this end, we discuss the idea of categorizing structures based on information according to the algorithmic complexity of their assembly.

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Ice structures, patterns, and processes: A view across the icefields, T Bartels-Rausch, V Bergeron, JHE Cartwright, R Escribano, JL Finney, H Grothe, PJ Gutiérrez, J Haapala, WF Kuhs, JBC Pettersson, SD Price, CI Sainz-Díaz, DJ Stokes, G Strazzulla, ES Thomson, H Trinks, & N Uras-Aytemiz, Rev. Mod. Phys. 84, 885–944, 2012.

Thu, 24 May 2012 18:27:40 +0200

From the frontiers of research on ice dynamics in its broadest sense, this review surveys the structures of ice, the patterns or morphologies it may assume, and the physical and chemical processes in which it is involved. Open questions in the various fields of ice research in nature are highlighted, ranging from terrestrial and oceanic ice on Earth, to ice in the atmosphere, to ice on other Solar System bodies and in interstellar space.

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Turbulent skin-friction drag on a slender body of revolution and Gray’s Paradox, I Nesteruk & JHE Cartwright, J. Phys.: Conf. Ser. 318, 022042, 2011.

Wed, 18 Jan 2012 18:16:33 +0100

The boundary layer on a slender body of revolution differs considerably from that on a flat plate, but these two cases can be connected by the Mangler-Stepanov transformations. The presented analysis shows that turbulent frictional drag on a slender rotationally symmetric body is much smaller than the flat-plate concept gives and the flow can remain laminar at larger Reynolds numbers. Both facts are valid for an unseparated flow pattern and enable us to revise the turbulent drag estimation of a dolphin, presented by Gray 74 years ago, and to resolve his paradox, since experimental data testify that dolphins can achieve flow without separation. The small values of turbulent skin-friction drag on slender bodies of revolution have additional interest for further experimental investigations and for applications of shapes without boundary-layer separation to diminish the total drag and noise of air- and hydrodynamic hulls.

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