Dispersion relations and lattice dynamics of diphenylalanine nanotubes

In this work we demonstrate the structural similarity between nanotubes of dipeptide diphenylalanine and one-dimensional locally resonant metamaterials. We developed dynamical model of nanotubes, derived corresponding dispersion relations, and analyzed the origin of the behavior of their optical branch leading to band gap formation. We demonstrate also that the width of the band gap can be varied by tuning the interaction between core molecules. Obtained results are general for many locally resonant metamaterials. © 2018 Institute of Physics Publishing.All Rights Reserved.The research was carried out under financial support by the grant of the President of the Russian Federation for young scientists (Contract 14.Y30.17.2294-MK) and the Government of the Russian Federation (Resolution 211, Contract 02.A03.21.0006)

Nanodomain structures formation during polarization reversal in uniform electric field in strontium barium niobate single crystals

We have studied the ferroelectric nanodomain formation in single crystals of strontium barium niobate Sr 0.61Ba 0.39Nb 2O 6 using piezoelectric force microscopy and Raman confocal microscopy. The nanodomain structures have been created by application of the uniform electric field at room temperature. Four variants of nanodomain structure formation have been revealed: (1) discrete switching, (2) incomplete domain merging, (3) spontaneous backswitching, and (4) enlarging of nanodomain ensembles. Kinetics of the observed micro- and nanodomain structures has been explained on the basis of approach developed for lithium niobate and lithium tantalate crystals. © 2012 American Institute of Physics

Chiral peculiar properties of self-organization of diphenylalanine peptide nanotubes: Modeling of structure and properties

The structure and properties of diphenylalanine peptide nanotubes based on phenylalanine were investigated by various molecular modeling methods. The main approaches were semi-empirical quantum-chemical methods (PM3 and AM1), and molecular mechanical ones. Both the model structures and the structures extracted from their experimental crystallographic databases obtained by X-ray methods were examined. A comparison of optimized model structures and structures obtained by naturally-occurring self-assembly showed their important differences depending on D- and L-chirality. In both the cases, the effect of chirality on the results of self-assembly of diphenylalanine peptide nanotubes was established: peptide nanotubes based on the D-diphenylalanine (D-FF) has high condensation energy E 0 in transverse direction and forms thicker and shorter peptide nanotubes bundles, than that based on L-diphenylalanine (L-FF). A topological difference was established: model peptide nanotubes were optimized into structures consisting of rings, while naturally self-assembled peptide nanotubes consisted of helical coils. The latter were different for the original L-FF and D-FF. They formed helix structures in which the chirality sign changes as the level of the macromolecule hierarchy raises. Total energy of the optimal distances between two units are deeper for L-FF (-1.014 eV) then for D-FF (-0.607 eV) for ring models, while for helix coil are approximately the same and have for L-FF (-6.18 eV) and for D-FF (-6.22 eV) by PM3 method; for molecular mechanical methods energy changes are of the order of 2-3 eV for both the cases. A topological transition between a ring and a helix coil of peptide nanotube structures is discussed: self-assembled natural helix structures are more stable and favourable, they have lower energy in optimal configuration as compared with ring models by a value of the order of 1 eV for molecular mechanical methods and 5 eV for PM3 method. © 2019 Mathematical Biology and Bioinformatics.Part of this work was developed as part of the CICECO-Aveiro Materials Institute project, POCI-01-0145-FEDER-007679 funded from Fundação para a Ciência e a Tecnologia (FCT) Ref. UID/CTM/50011/2013, and funded from national funds through FCT/MEC, and co-funded by FEDER in accordance with the PT2020 Partnership Agreement. P.Z. thanks the project FCT PTDC/QEQ-QAN/6373/2014. S.K. thanks the project FCT PTDC/CTM-CTM/31679/2017

β-glycine piezoelectric and ferroelectric properties behavior at elevated temperatures

The research was carried out using equipment of Ural Center for Shared Use "Modern Nanotechnologies" Ural Federal University. The reported study was funded by RFBR according to the research project № 18-32-00390

Micro-Raman imaging of ferroelectric domain structures in the bulk of PMN-PT single crystals

We demonstrate the application of confocal Raman microscopy (CRM) for nondestructive imaging of ferroelectric domains both at the surface and in the bulk of lead magnesium niobate-lead titanate (PMN-PT) ferroelectric single crystals. The studied model periodical domain structure was created at a [001] cut of tetragonal-phase PMN-PT crystal by the electron beam patterning technique. It was shown that the surface CRM domain image coincides in details with the image obtained by piezoresponse force microscopy. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.The research was funded by Russian Foundation for Basic Research (grant 17-52-80116-BRICS_a), National Natural Science Foundation of China (grant 51761145024), Government of the Russian Federation (act 211, agreement 02.180 A03.21.0006), and Ministry of Science and Higher Education of the Russian Federation (state task No. 3.4993.2017/6.7)

Confocal Raman study of electric fields in lithium niobate single crystals

The research was made possible by Russian Science Foundation (Grant 19-72-10076). The equipment of the Ural Center for Shared Use “Modern nanotechnology” UrFU was used

Nanodomain structures formation during polarization reversal in uniform electric field in strontium barium niobate single crystals

We have studied the ferroelectric nanodomain formation in single crystals of strontium barium niobate Sr 0.61Ba 0.39Nb 2O 6 using piezoelectric force microscopy and Raman confocal microscopy. The nanodomain structures have been created by application of the uniform electric field at room temperature. Four variants of nanodomain structure formation have been revealed: (1) discrete switching, (2) incomplete domain merging, (3) spontaneous backswitching, and (4) enlarging of nanodomain ensembles. Kinetics of the observed micro- and nanodomain structures has been explained on the basis of approach developed for lithium niobate and lithium tantalate crystals. © 2012 American Institute of Physics

Domain creation by electron and ion beams in lithium tantalate crystals

The equipment of the Ural Center for Shared Use “Modern nanotechnology” Ural Federal University was used. The research was made possible by the Russian Science Foundation (grant № 17-72-10152)