ORCID Profile
0000-0003-3604-0672
Current Organisation
US Department of Energy
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Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2MH00244B
Abstract: Exploiting the interaction between polarized tender X-rays and the planar conjugated backbone, resonant tender X-ray diffraction is able to resolve the tilting of the backbone within the unit cell.
Publisher: American Chemical Society (ACS)
Date: 22-07-2015
DOI: 10.1021/ACS.JPCLETT.5B01338
Abstract: In this work, we report on inelastic X-ray scattering experiments combined with the molecular dynamics simulations on deeply supercritical Ar. The presented results unveil the mechanism and regimes of sound propagation in the liquid matter and provide compelling evidence for the adiabatic-to-isothermal longitudinal sound propagation transition. We introduce a Hamiltonian predicting low-frequency transverse sound propagation gaps, which is confirmed by experimental findings and molecular dynamics calculations. As a result, a universal link is established between the positive sound dispersion (PSD) phenomenon and the origin of transverse sound propagation revealing the viscous-to-elastic crossover in liquids. The PSD and transverse phononic excitations evolve consistently with theoretical predictions. Both can be considered as a universal fingerprint of the dynamic response of a liquid, which is also observable in a subdomain of supercritical phase. The simultaneous disappearance of both these effects at elevated temperatures is a manifestation of the Frenkel line. We expect that these findings will advance the current understanding of fluids under extreme thermodynamic conditions.
Publisher: Proceedings of the National Academy of Sciences
Date: 18-02-2020
Abstract: Although it is believed that the raft formation in a cell membrane is governed by a selective interaction of different lipids and proteins, mechanisms driving and regulating the lateral membrane heterogeneity remain poorly understood. Here, using multicomponent lipid mixtures and inelastic X-ray scattering, we provide a spatial–temporal window to study lipid–lipid interactions. We show experimental evidence for the formation of dynamic lipid pairs, which are subnanometer in size and have a subnanosecond lifetime. These pairs form transient nanoscopic substructures in the liquid-ordered phase. The presented approach to study membrane heterogeneity is universal and can be applied to more realistic lipid mixtures, offering the possibility to discern differences between the structures of ordered and disordered phases in a cell membrane.
Publisher: American Chemical Society (ACS)
Date: 12-04-2021
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.BBAMEM.2018.07.004
Abstract: It has been widely accepted that the thermally excited motions of the molecules in a cell membrane is the prerequisite for a cell to carry its biological functions. On the other hand, the detailed mapping of the ultrafast picosecond single-molecule and the collective lipid dynamics in a cell membrane remains rather elusive. Here, we report all-atom molecular dynamics simulations of a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine bilayer over a wide range of temperature. We elucidate a molecular mechanism underlying the lateral lipid diffusion in a cell membrane across the gel, rippled, and liquid phases using an analysis of the longitudinal and transverse current correlation spectra, the velocity auto-correlation functions, and the molecules mean square displacements. The molecular mechanism is based on the anomalous ultrafast vibrational properties of lipid molecules at the viscous-to-elastic crossover. The macroscopic lipid diffusion coefficients predicted by the proposed diffusion model are in a good agreement with experimentally observed values. Furthermore, we unveil the role of water confined at the water-lipid interface in triggering collective vibrations in a lipid bilayer.
Publisher: Springer Science and Business Media LLC
Date: 05-11-2015
DOI: 10.1038/SREP15850
Abstract: Supercritical fluids play a significant role in elucidating fundamental aspects of liquid matter under extreme conditions. They have been extensively studied at pressures and temperatures relevant to various industrial applications. However, much less is known about the structural behaviour of supercritical fluids and no structural crossovers have been observed in static compression experiments in any temperature and pressure ranges beyond the critical point. The structure of supercritical state is currently perceived to be uniform everywhere on the pressure-temperature phase diagram and to change only in a monotonic way even moving around the critical point, not only along isotherms or isobars. Conversely, we observe structural crossovers for the first time in a deeply supercritical s le through diffraction measurements in a diamond anvil cell and discover a new thermodynamic boundary on the pressure-temperature diagram. We explain the existence of these crossovers in the framework of the phonon theory of liquids using molecular dynamics simulations. The obtained results are of prime importance since they imply a global reconsideration of the mere essence of the supercritical phase. Furthermore, this discovery may pave the way to new unexpected applications and to the exploration of exotic behaviour of confined fluids relevant to geo- and planetary sciences.
Publisher: American Chemical Society (ACS)
Date: 02-06-2017
DOI: 10.1021/ACS.NANOLETT.7B01324
Abstract: The investigation of phononic collective excitations in soft matter systems at the molecular scale has always been challenging due to limitations of experimental techniques in resolving low-energy modes. Recent advances in inelastic X-ray scattering (IXS) enabled the study of such systems with unprecedented spectral contrast at meV excitation energies. In particular, it has become possible to shed light on the low-energy collective motions in materials whose morphology and phase behavior can easily be manipulated, such as mesogenic systems. The understanding of collective mode behavior with a Q-dependence is the key to implement heat management based on the control of a s le structure. The latter has great potential for a large number of energy-inspired innovations. As a first step toward this goal, we carried out high contrast IXS measurements on a liquid crystal s le, D7AOB, which exhibits solid-like dynamic features, such as the coexistence of longitudinal and transverse phononic modes. For the first time, we found that these terahertz phononic excitations persist in the crystal, smectic A, and isotropic phases. Furthermore, the intermediate smectic A phase is shown to support a van der Waals-mediated nonhydrodynamic mode with an optical-like phononic behavior. The tunability of the collective excitations at nanometer-terahertz scales via selection of the s le mesogenic phase represents a new opportunity to manipulate optomechanical properties of soft metamaterials.
Publisher: Springer Science and Business Media LLC
Date: 14-01-2016
DOI: 10.1038/SREP19469
Abstract: In this paper we present inelastic X-ray scattering experiments in a diamond anvil cell and molecular dynamic simulations to investigate the behavior of phononic excitations in liquid Ar. The spectra calculated using molecular dynamics were found to be in a good agreement with the experimental data. Furthermore, we observe that, upon temperature increases, a low-frequency transverse phononic gap emerges while high-frequency propagating modes become evanescent at the THz scale. The effect of strong localization of a longitudinal phononic mode in the supercritical phase is observed for the first time. The evidence for the high-frequency transverse phononic gap due to the transition from an oscillatory to a ballistic dynamic regimes of motion is presented and supported by molecular dynamics simulations. This transition takes place across the Frenkel line thermodynamic limit which demarcates compressed liquid and non-compressed fluid domains on the phase diagram and is supported by calculations within the Green-Kubo phenomenological formalism. These results are crucial to advance the development of novel terahertz thermal devices, phononic lenses, mirrors and other THz metamaterials.
Publisher: Springer Science and Business Media LLC
Date: 25-11-2027
DOI: 10.1038/NCOMMS11575
Abstract: The passive transport of molecules through a cell membrane relies on thermal motions of the lipids. However, the nature of transmembrane transport and the precise mechanism remain elusive and call for a comprehensive study of phonon excitations. Here we report a high resolution inelastic X-ray scattering study of the in-plane phonon excitations in 1,2-dipalmitoyl- sn -glycero-3-phosphocholine above and below the main transition temperature. In the gel phase, for the first time, we observe low-frequency transverse modes, which exhibit a phonon gap when the lipid transitions into the fluid phase. We argue that the phonon gap signifies the formation of short-lived nanometre-scale lipid clusters and transient pores, which facilitate the passive molecular transport across the bilayer plane. Our findings suggest that the phononic motion of the hydrocarbon tails provides an effective mechanism of passive transport, and illustrate the importance of the collective dynamics of biomembranes.
Publisher: American Chemical Society (ACS)
Date: 29-08-2016
Publisher: American Chemical Society (ACS)
Date: 07-04-2020
Publisher: American Chemical Society (ACS)
Date: 26-05-2022
Publisher: American Chemical Society (ACS)
Date: 04-09-2018
Publisher: Springer Science and Business Media LLC
Date: 09-08-2016
DOI: 10.1038/NCOMMS12292
Abstract: Nature Communications 7: Article number: 11575 (2016) Published: 12 May 2016 Updated: 9 August 2016 This Article was originally published with an incorrect publication date. This paper was due to be published on 26 May 2016 together with other content on a similar topic, but due to an error was published earlier on the 12 May 2016.
Publisher: Elsevier BV
Date: 12-2015
Publisher: American Chemical Society (ACS)
Date: 05-2023
No related grants have been discovered for Mikhail Zhernenkov.