Capillary method and molecular dynamics study of the diffusion and molecular structures of vanadium(IV)-ligand complexes

2021 ◽  
Author(s):  
Tao Wu ◽  
Zilong Geng ◽  
Qiang Shen ◽  
Yuhua Guo ◽  
Jianhui Lan
Keyword(s):  
Molecular Dynamics ◽  
Molecular Structures ◽  
Capillary Method

scholarly journals Short Pyridine-Furan Springs Exhibit Bistable Dynamics of Duffing Oscillators

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3264
Author(s):  
Vladik A. Avetisov ◽  
Maria A. Frolkina ◽  
Anastasia A. Markina ◽  
Alexander D. Muratov ◽  
Vladislav S. Petrovskii
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Stochastic Resonance ◽  
Duffing Oscillator ◽  
Molecular Structures ◽  
Thermally Activated ◽  
Responsive Polymers ◽  
Bistable Dynamics ◽  
Dynamics Simulations ◽  
Intensive Development

The intensive development of nanodevices acting as two-state systems has motivated the search for nanoscale molecular structures whose dynamics are similar to those of bistable mechanical systems, such as Euler arches and Duffing oscillators. Of particular interest are the molecular structures capable of spontaneous vibrations and stochastic resonance. Recently, oligomeric molecules that were a few nanometers in size and exhibited the bistable dynamics of an Euler arch were identified through molecular dynamics simulations of short fragments of thermo-responsive polymers subject to force loading. In this article, we present molecular dynamics simulations of short pyridine-furan springs a few nanometers in size and demonstrated the bistable dynamics of a Duffing oscillator with thermally-activated spontaneous vibrations and stochastic resonance.

scholarly journals Polydopamine and eumelanin molecular structures investigated with ab initio calculations

2017 ◽  
Vol 8 (2) ◽  
pp. 1631-1641 ◽  
Author(s):  
Chun-Teh Chen ◽  
Francisco J. Martin-Martinez ◽  
Gang Seob Jung ◽  
Markus J. Buehler
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Dft Calculations ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Md Simulations ◽  
Molecular Structures ◽  
Brute Force ◽  
Functional Theory

A set of computational methods that contains a brute-force algorithmic generation of chemical isomers, molecular dynamics (MD) simulations, and density functional theory (DFT) calculations is reported and applied to investigate nearly 3000 probable molecular structures of polydopamine (PDA) and eumelanin.

Diffusion of Epoxy Molecules on the Chemically Modified Graphene: A Molecular Dynamics Simulation Study

2015 ◽  
Vol 817 ◽  
pp. 803-808 ◽  
Author(s):  
Jian Wei Zhang ◽  
Cai Jiang ◽  
Gang Shi ◽  
Da Zhi Jiang
Keyword(s):  
Molecular Dynamics ◽  
Polymer Composites ◽  
Functional Groups ◽  
Md Simulations ◽  
Molecular Structures ◽  
Dynamics Simulation ◽  
Graphene Layers ◽  
Wall Structures ◽  
Modified Graphene ◽  
Main Factor

Buckypaper based polymer composites provides a new technical approach toward realizing conductive/structural multifunctional composites. Resin infiltration in the buckypaper is critical for the fabrication of buckypaper/polymer composites. To investigate the micro-infusion process of the polymer inside the paper, molecular dynamics (MD) simulations are conducted to study the diffusion behavior of epoxy molecules on the modified graphene and between graphene layers. The graphene molecular structures are constructed to represent the wall structures of the carbon nanotubes. Diffusion coefficients of the epoxy molecules on the graphene modified with different functionalization densities and interlayer distances are calculated. The results indicate that the functional groups increase the interfacial interactions between the epoxy molecules and graphene, however, largely decrease the diffusion speeds of the epoxy molecule. The simulations on the graphene layer systems indicate that, the viscous resistance of the resin is the main factor for retarding the diffusion of the epoxy molecules for the unmodified graphene layers; while for the modified graphene layers, functional groups are the main factor for retarding the resin diffusion

Анализ вычислительных и экспериментальных исследований переключения поляризации в ПВДФ и П (ВДФ-ТрФЭ) сегнетоэлектрических пленках на наноуровне

2015 ◽  
Vol 10 (2) ◽  
pp. 372-386 ◽  
Author(s):  
В.С. Быстров ◽  
V.S. Bystrov
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Electric Field ◽  
Quantum Chemical ◽  
Polyvinylidene Fluoride ◽  
Domain Switching ◽  
Polarization Switching ◽  
Molecular Structures ◽  
Switching Mechanism ◽  
Semi Empirical

In this paper, molecular models are used to investigate and analyze the polarization switching in the polyvinylidene fluoride (PVDF) and poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) Langmuir-Blodgett (LB) nanofilms, in comparison with the experimental data at the nanoscale. Quantum-mechanical calculations and modeling, as well as molecular dynamics (MD) simulations based on semi-empirical quantum-chemical methods (such as PM3), show that the energy of the studied PVDF and P (VDF-TrFE) molecular structures, and their polarization switching proceed by the intrinsic homogeneous switching mechanism in the framework of the phenomenological theory of Landau-Ginzburg-Devonshire (LGD) in the linear approximation at low values of the electric field. The magnitude of the resulting critical coercive field is within the EC ~ 0.5 ... 2.5 GV/m, which is consistent with experimental data. It is also found that the uniform polarization switching mechanism of the polymer chains PVDF and P (VDF-TrFE) is due to the quantum properties of the molecular orbitals of the electron subsystem. This is clearly seen in both the polarization hysteresis loops, and the total energy changes. In this case, the turnover chain time, obtained by molecular dynamics within semi-empirical quantum-chemical PM3 approach in a limited Hartree-Fock approximation, when approaching this critical point, increases sharply, tending to infinity, which corresponds to the theory of LGD. Otherwise, at the high values of the applied electric field the polarization switching correspond to the extrinsic domain mechanism in the frame of the microscopic Kolmogorov–Avrami–Ishibashi (KAI) theory, describing bulk ferroelectric crystals and thick films. The performed analysis of computational and experimental data allows us to estimate the critical sizes of the possible transition region approximately on the order of 10 nm between intrinsic homogeneous and extrinsic domain switching mechanisms.

scholarly journals Explicit-pH Coarse-Grained Molecular Dynamics Simulations Enable Insights into Restructuring of Intestinal Colloidal Aggregates with Permeation Enhancers

Processes ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 29
Author(s):  
Shakhawath Hossain ◽  
Albin Parrow ◽  
Aleksei Kabedev ◽  
Rosita Carolina Kneiszl ◽  
Yuning Leng ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Ph Dependence ◽  
Molecular Structures ◽  
Aggregation Behavior ◽  
Coarse Grained ◽  
Permeation Enhancers ◽  
Fed State ◽  
Dynamics Simulations ◽  
Coarse Grained Molecular Dynamics

Permeation enhancers (PEs) can increase the bioavailability of drugs. The mechanisms of action of these PEs are complex, but, typically, when used for oral administration, they can transiently induce the alteration of trans- and paracellular pathways, including increased solubilization and membrane fluidity, or the opening of the tight junctions. To elucidate these mechanistic details, it is important to understand the aggregation behavior of not only the PEs themselves but also other molecules already present in the intestine. Aggregation processes depend critically on, among other factors, the charge state of ionizable chemical groups, which is affected by the pH of the system. In this study, we used explicit-pH coarse-grained molecular dynamics simulations to investigate the aggregation behavior and pH dependence of two commonly used PEs—caprate and SNAC—together with other components of fasted- and fed-state simulated intestinal fluids. We also present and validate a coarse-grained molecular topology for the bile salt taurocholate suitable for the Martini3 force-field. Our results indicate an increase in the number of free molecules as a function of the system pH and for each combination of FaSSIF/FeSSIF and PEs. In addition, there are differences between caprate and SNAC, which are rationalized based on their different molecular structures and critical micelle concentrations.

Fifty years of light scattering studies in gases, liquids and solids [abstract only]

1979 ◽  
Vol 293 (1402) ◽  
pp. 213-213
Keyword(s):  
Molecular Dynamics ◽  
Light Scattering ◽  
Raman Effect ◽  
Molecular Structures ◽  
New Developments ◽  
Laser Sources ◽  
New Applications ◽  
Structure Of Matter

Since the discovery of the Raman effect in 1928, extensive studies of light scattering in gases, liquids and solids have had a major impact on our knowledge of the structure of matter. New developments in technique and theory have continuously extended the application of light scattering to problems in physics, chemistry, and more recently in biology. The recent use of laser sources has caused a revolution in the field of light scattering, with promise of more precise measurements of molecular structures and of molecular dynamics, and important new applications and knowledge.

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