scholarly journals Aspirin locally disrupts the liquid-ordered phase

2018 ◽  
Vol 5 (2) ◽  
pp. 171710 ◽  
Author(s):  
Richard J. Alsop ◽  
Sebastian Himbert ◽  
Alexander Dhaliwal ◽  
Karin Schmalzl ◽  
Maikel C. Rheinstädter
Keyword(s):  
Small Molecules ◽  
Local Structure ◽  
Lipid Membranes ◽  
Inelastic Neutron Scattering ◽  
Md Simulations ◽  
Inelastic Neutron ◽  
Membrane Function ◽  
Structure And Dynamics ◽  
Liquid Ordered ◽  
Functional Interface

Local structure and dynamics of lipid membranes play an important role in membrane function. The diffusion of small molecules, the curvature of lipids around a protein and the existence of cholesterol-rich lipid domains (rafts) are examples for the membrane to serve as a functional interface. The collective fluctuations of lipid tails, in particular, are relevant for diffusion of membrane constituents and small molecules in and across membranes, and for structure and formation of membrane domains. We studied the effect of aspirin (acetylsalicylic acid, ASA) on local structure and dynamics of membranes composed of dimyristoylphosphocholine (DMPC) and cholesterol. Aspirin is a common analgesic, but is also used in the treatment of cholesterol. Using coherent inelastic neutron scattering experiments and molecular dynamics (MD) simulations, we present evidence that ASA binds to liquid-ordered, raft-like domains and disturbs domain organization and dampens collective fluctuations. By hydrogen-bonding to lipid molecules, ASA forms ‘superfluid’ complexes with lipid molecules that can organize laterally in superlattices and suppress cholesterol’s ordering effect.

An inelastic neutron scattering, Raman, far-infrared, and molecular dynamics study of the intermolecular dynamics of two ionic liquids

2020 ◽  
Vol 22 (16) ◽  
pp. 9074-9085 ◽  
Author(s):  
Thamires A. Lima ◽  
Vitor H. Paschoal ◽  
Rafael S. Freitas ◽  
Luiz F. O. Faria ◽  
Zhixia Li ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Ionic Liquids ◽  
Power Spectrum ◽  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Far Infrared ◽  
Md Simulations ◽  
Inelastic Neutron ◽  
Tetraalkylammonium Cations

The THz dynamics of ionic liquids based on tetraalkylammonium cations were investigated by a combined usage of inelastic neutron scattering (INS), Raman, and far-infrared (FIR) spectroscopies and the power spectrum calculated by molecular dynamics (MD) simulations.

scholarly journals Spectroscopy of light-molecule endofullerenes

2013 ◽  
Vol 371 (1998) ◽  
pp. 20120429 ◽  
Author(s):  
Malcolm H. Levitt
Keyword(s):  
Small Molecules ◽  
Degrees Of Freedom ◽  
Inelastic Neutron Scattering ◽  
Level Structure ◽  
Inelastic Neutron ◽  
Supramolecular Systems ◽  
Guest Molecules ◽  
Energy Level Structure ◽  
Rotational Degrees Of Freedom ◽  
Synthetic Routes

Molecular endofullerenes are supramolecular systems consisting of fullerene cages encapsulating small molecules. Although most early examples consist of encapsulated metal clusters, recently developed synthetic routes have provided endofullerenes with non-metallic guest molecules in high purity and macroscopic quantities. The encapsulated light molecule behaves as a confined quantum rotor, displaying rotational quantization as well as translational quantization, and a rich coupling between the translational and rotational degrees of freedom. Furthermore, many encapsulated molecules display spin isomerism. Spectroscopies such as inelastic neutron scattering, nuclear magnetic resonance and infrared spectroscopy may be used to obtain information on the quantized energy level structure and spin isomerism of the guest molecules. It is also possible to study the influence of the guest molecules on the cages, and to explore the communication between the guest molecules and the molecular environment outside the cage.

Ti-Zr-Ni Quasicrystals: Structure and Hydrogen Storage

1995 ◽  
Vol 400 ◽  
Author(s):  
R. M. Stroud ◽  
A. M. Viano ◽  
E. H. Majzoub ◽  
P. C. Gibbons ◽  
K. F. Kelton
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Transition Metal ◽  
Hydrogen Storage ◽  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
X Ray ◽  
Structure And Dynamics ◽  
Icosahedral Phases

AbstractTitanium-based icosahedral phases constitute the second largest class of quasicrystals. In contrast with other Ti-based icosahedral phases (i-phases), Ti-Zr-Ni i-phases are well ordered and their formation is inhibited by the presence of Si and O, elements that stabilize the Ti-3d transition metal quasicrystals. We present x-ray and DSC data that suggest that Ti-Zr-Ni i-phases form a different class of titanium-based quasicrystals that are closely related to the MgZn2 Laves phase. The DSC data also suggest that the i-phase may be stable in these alloys. The ability of Ti-Zr-Ni i-phases to absorb up to 62 atomic % of hydrogen is presented and discussed. This opens new avenues of investigation of the structure and dynamics of quasiperiodic phases using elastic and inelastic neutron scattering and nuclear magnetic resonance and may point to potential uses for quasicrystals in hydrogen storage applications.

Dynamics of Water Confined on the Surface of Titania and Cassiterite Nanoparticles

2011 ◽  
Vol 1352 ◽  
Author(s):  
Nancy L. Ross ◽  
Elinor C. Spencer ◽  
Andrey A. Levchenko ◽  
Alexander I. Kolesnikov ◽  
Douglas L. Abernathy ◽  
...  
Keyword(s):  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Water Molecules ◽  
Structure And Dynamics ◽  
Metal Oxide Nanoparticle ◽  
Translational Movement ◽  
Scattering Spectra ◽  
Oxide Nanoparticle ◽  
Bond Network ◽  
Hydration Layers

ABSTRACTWe present low-temperature inelastic neutron scattering spectra collected on two metal oxide nanoparticle systems, isostructural TiO2 rutile and SnO2 cassiterite, between 0-550 meV. Data were collected on samples with varying levels of water coverage, and in the case of SnO2, particles of different sizes. This study provides a comprehensive understanding of the structure and dynamics of the water confined on the surface of these particles. The translational movement of water confined on the surface of these nanoparticles is suppressed relative to that in ice-Ih and water molecules on the surface of rutile nanoparticles are more strongly restrained that molecules residing on the surface of cassiterite nanoparticles. The INS spectra also indicate that the hydrogen bond network within the hydration layers on rutile is more perturbed than for water on cassiterite. This result is indicative of stronger water-surface interactions between water on the rutile nanoparticles than for water confined on the surface of cassiterite nanoparticles. These differences are consistent with the recently reported differences in the surface energy of these two nanoparticle systems.

scholarly journals Concentration dependence of vibrational properties of bioprotectant/water mixtures by inelastic neutron scattering

2006 ◽  
Vol 4 (12) ◽  
pp. 167-173 ◽  
Author(s):  
S Magazù ◽  
F Migliardo ◽  
A.J Ramirez-Cuesta
Keyword(s):  
Neutron Scattering ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Biological Molecules ◽  
Chemical Mechanisms ◽  
Structure And Dynamics ◽  
Biophysical Processes ◽  
Bending Modes ◽  
Physical And Chemical ◽  
Vibrational Features

Neutron scattering has been demonstrated to be a powerful tool for characterizing the structure and dynamics of biological molecules and for investigating the physical and chemical mechanisms of biophysical processes. The aim of the present work is to investigate by inelastic neutron scattering (INS) the vibrational behaviour of a class of bioprotectant systems, such as homologous disaccharides, trehalose, maltose and sucrose, in water mixtures. INS measurements have been performed on trehalose/H 2 O, maltose/H 2 O and sucrose/H 2 O mixtures at very low temperature as a function of concentration by using the thermal original spectrometer with cylindrical analyzers (TOSCA) spectrometer at the ISIS Facility (DRAL, UK). The findings allow the analyses of the vibrational features of the INS spectra in order to study the effect of disaccharides on the H 2 O hydrogen-bonded tetrahedral network. The obtained neutron scattering findings point out that disaccharides, and in particular trehalose, have a destructuring effect on the water tetrahedral network, as emphasized by the analysis of the librational modes region from 50 to 130 meV energy transfer. On the other hand, the analysis of the bending modes region (130–225  meV) shows a locally ordered structure in the disaccharide/H 2 O mixtures. Finally, the observed experimental evidences are linked to the different bioprotective effectiveness of disaccharides as a function of concentration.

scholarly journals Understanding the Structure and Dynamics of Nanocellulose-Based Composites with Neutral and Ionic Poly(methacrylate) Derivatives Using Inelastic Neutron Scattering and DFT Calculations

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1689
Author(s):  
Carla Vilela ◽  
Carmen S. R. Freire ◽  
Catarina Araújo ◽  
Svemir Rudić ◽  
Armando J. D. Silvestre ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Density Functional Theory Calculations ◽  
Inelastic Neutron ◽  
Spectral Lines ◽  
Model Systems ◽  
Functional Theory ◽  
Bacterial Nanocellulose ◽  
Structure And Dynamics

Bacterial nanocellulose (BC)-based composites containing poly(2-hydroxyethyl methacrylate) (PHEMA), poly(methacroylcholine chloride) (PMACC) or poly(methacroylcholine hydroxide) (PMACH) were characterized by inelastic neutron scattering (INS) spectroscopy, combined with DFT (density functional theory) calculations of model systems. A reasonable match between calculated and experimental spectral lines and their intensities was used to support the vibrational assignment of the observed bands and to validate the possible structures. The differences between the spectra of the nanocomposites and the pure precursors indicate that interactions between the components are stronger for the ionic poly(methacrylate) derivatives than for the neutral counterpart. Displaced anions interact differently with cellulose chains, due to the different ability to compete with the O–H···O hydrogen bonds in cellulose. Hence, the INS is an adequate technique to delve deeper into the structure and dynamics of nanocellulose-based composites, confirming that they are true nanocomposite materials instead of simple mixtures of totally independent domains.

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