Special Issue "Complex Nanoscale Geometry and Dynamics at the Frontier between Biology and Material Science"

A special issue of Condensed Matter (ISSN 2410-3896).

Deadline for manuscript submissions: 15 December 2018

Special Issue Editor

Guest Editor
Dr. Gaetano Campi

Institute of Crystallography, CNR, Via Salaria Km 29.300, Monterotondo, Roma 00015, Italy
Website | E-Mail
Interests: synchrotron radiation techniques; heterogeneity and complexity in condensed matter; structural fluctuations and dynamics; quantum materials; biophysics

Special Issue Information

Dear Colleagues,

Outstanding structure–function relationships of new complex materials are often due their dynamic heterogeneous structures and compositions. Examples of complex materials include biomaterials, colloids, complex liquids, and strongly correlated materials. These materials are characterized by weak interactions between structural units, giving rise to different supramolecular configurations at nanoscale and mesoscale. While supramolecular assembly occurs widely in nature, it is poorly understood since it takes place at multiple scales. Today it is of high relevance for health care, biological systems, material engineering and photosynthetic processes. It is of high relevance also for polymers and systems at frustrated nanoscale phase separation, where crystalline and amorphous nanoscale regions coexist. The fluctuations between different supramolecular configurations play a central role in the understanding of both the basic principles of condensed matter and the material functionality for new technological applications. The visualization of the arising nano/mesoscale geometry and dynamics with the understanding of correlated phenomena require experimental techniques suitable to provide appropriate spatial and temporal resolution, jointly, to advanced modelling and statistical tools for data analysis. The purpose of this Special Issue is to collect significant works investigating connections between new geometries developing at nano/mesoscale and the emerging macroscopic properties in complex and heterogeneous materials in different fields ranging from material science to biology.

Dr. Gaetano Campi
Guest Editor

Manuscript Submission Information

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Keywords

  • Complex and heterogeneous materials
  • Supramolecular assembly
  • Patterning at nanoscale and mesoscale
  • Correlated disorder
  • Biomaterials
  • Quantum materials

Published Papers (4 papers)

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Research

Open AccessArticle On the Nanoscale Structure of KxFe2−yCh2 (Ch = S, Se): A Neutron Pair Distribution Function View
Condens. Matter 2018, 3(3), 20; https://doi.org/10.3390/condmat3030020
Received: 3 June 2018 / Revised: 26 June 2018 / Accepted: 27 June 2018 / Published: 3 July 2018
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Abstract
Comparative exploration of the nanometer-scale atomic structure of KxFe2−yCh2 (Ch = S, Se) was performed using neutron total scattering-based atomic pair distribution function (PDF) analysis of 5 K powder diffraction data in relation to physical properties. Whereas
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Comparative exploration of the nanometer-scale atomic structure of KxFe2−yCh2 (Ch = S, Se) was performed using neutron total scattering-based atomic pair distribution function (PDF) analysis of 5 K powder diffraction data in relation to physical properties. Whereas KxFe2−ySe2 is a superconductor with a transition temperature of about 32 K, the isostructural sulphide analogue is not, which instead displays a spin glass semiconducting behavior at low temperatures. The PDF analysis explores phase separated and disordered structural models as candidate descriptors of the low temperature data. For both materials, the nanoscale structure is well described by the iron (Fe)-vacancy-disordered K2Fe5−yCh5 (I4/m) model containing excess Fe. An equally good description of the data is achieved by using a phase separated model comprised of I4/m vacancy-ordered and I4/mmm components. The I4/mmm component appears as a minority phase in the structure of both KxFe2−ySe2 and KxFe2−yS2, and with similar contribution, implying that the phase ratio is not a decisive factor influencing the lack of superconductivity in the latter. Comparison of structural parameters of the Fe-vacancy-disordered model indicates that the replacement of selenium (Se) by sulphur (S) results in an appreciable reduction in the Fe-Ch interatomic distances and anion heights, while simultaneously increasing the irregularity of FeCh4 tetrahedra, suggesting the more significant influence of these factors. Structural features are also compared to the non-intercalated FeSe and FeS parent phases, providing further information for the discussion about the influence of the lattice degrees of freedom on the observed properties in layered iron chalcogenides. Full article
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Open AccessArticle Annealed Low Energy States in Frustrated Large Square Josephson Junction Arrays
Condens. Matter 2018, 3(2), 19; https://doi.org/10.3390/condmat3020019
Received: 30 April 2018 / Revised: 30 May 2018 / Accepted: 6 June 2018 / Published: 13 June 2018
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Abstract
Numerical simulations were done to find low energy states in frustrated large square Josephson Junction arrays in a perpendicular magnetic field using simulated annealing on the coupled RSJ model. These simulations were made possible by a new algorithm suitable for parallel gpu computing
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Numerical simulations were done to find low energy states in frustrated large square Josephson Junction arrays in a perpendicular magnetic field using simulated annealing on the coupled RSJ model. These simulations were made possible by a new algorithm suitable for parallel gpu computing and reduced complexity. Free boundary conditions were used so that values of the frustration factor f that are incommensurate with the array size are permitted. The resulting energy as a function of f is continuous with logarithmic discontinuities in the derivative dE/df at rational frustration factors f=p/q with small q, substantiating the mathematical proof that this curve is continuous and further showing that the staircase state hypothesis is incorrect. The solution shows qualitative similarities with the lowest energy branch of the Hofstadter butterfly, which is a closely related problem. Furthermore, it is found that at the edge of an array there are either extra vortices or missing vortices depending the frustration factor, and the width of this region is independent of the array size. Full article
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Open AccessArticle Formation and Oriented Aggregation of Tabular Hexagonal Silver Particles
Condens. Matter 2018, 3(2), 13; https://doi.org/10.3390/condmat3020013
Received: 22 February 2018 / Revised: 4 April 2018 / Accepted: 12 April 2018 / Published: 14 April 2018
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Abstract
Silver tabular hexagonal particles (<diagonal> = 200 nm) were prepared at 40 °C by the reduction of silver nitrate with ascorbic acid in a solution of a polynaphthalene sulphonic dispersant agent, Daxad 19, in strong acidic conditions. By varying the reaction temperature and
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Silver tabular hexagonal particles (<diagonal> = 200 nm) were prepared at 40 °C by the reduction of silver nitrate with ascorbic acid in a solution of a polynaphthalene sulphonic dispersant agent, Daxad 19, in strong acidic conditions. By varying the reaction temperature and thus the dispersion viscosity between 10 °C and 30 °C, mesostructures of silver flat rods and flakes were obtained, the former resulting from linear aggregation of tabular hexagonal particles and the latter formed by intertwined flat rods. The results indicate an easy way to tune the aggregation of particles to obtain ordered mesostructures. Full article
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Open AccessArticle Correlated Disorder in Myelinated Axons Orientational Geometry and Structure
Condens. Matter 2017, 2(3), 29; https://doi.org/10.3390/condmat2030029
Received: 3 August 2017 / Revised: 4 September 2017 / Accepted: 6 September 2017 / Published: 11 September 2017
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Abstract
While the ultrastructure of myelin is considered a quasi-crystalline stable system, nowadays its multiscale complex dynamics appear to play a key role in its functionality, degeneration and repair processes following neurological diseases and trauma. In this work, we investigated the fluctuation of the
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While the ultrastructure of myelin is considered a quasi-crystalline stable system, nowadays its multiscale complex dynamics appear to play a key role in its functionality, degeneration and repair processes following neurological diseases and trauma. In this work, we investigated the fluctuation of the myelin supramolecular assembly by measuring the spatial distribution of orientation fluctuations of axons in a Xenopus Laevis sciatic nerve associated with nerve functionality. To this end, we used scanning micro X-ray diffraction (SμXRD), a non-invasive technique that has already been applied to other heterogeneous systems presenting complex geometries from microscale to nanoscale. We found that the orientation of the spatial fluctuations of fresh axons show a Levy flight distribution, which is a clear indication of correlated disorder. We found that the Levy flight distribution was missing in the aged nerve prepared in an unfresh state. This result shows that the spatial distribution of axon orientation fluctuations in unfresh nerve state loses the correlated disorder and assumes a random disorder behavior. This work provides a deeper understanding of the ultrastructure-function nerve relation and paves the way for the study of other materials and biomaterials using the SμXRD technique to detect fluctuations in their supramolecular structure. Full article
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