Molecular Dynamics Study of Aqueous Solution of Polyethylene Oxide: Critical Test of Force Field Models

2013 ◽  
Vol 11 (4) ◽  
pp. 371-383 ◽  
Author(s):  
Yong-Lei Wang ◽  
Rochelle S. Lawrence ◽  
Zhong-Yuan Lu ◽  
Aatto Laaksonen
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Force Field ◽  
Polyethylene Oxide ◽  
Critical Test

scholarly journals Simulating Absorption Spectra of Flavonoids in Aqueous Solution: A Polarizable QM/MM Study

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5853
Author(s):  
Sulejman Skoko ◽  
Matteo Ambrosetti ◽  
Tommaso Giovannini ◽  
Chiara Cappelli
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Hydrogen Bonding ◽  
Force Field ◽  
Absorption Spectra ◽  
Computational Study ◽  
Md Simulations ◽  
Quantum Mechanical ◽  
Hydrogen Bonding Interactions

We present a detailed computational study of the UV/Vis spectra of four relevant flavonoids in aqueous solution, namely luteolin, kaempferol, quercetin, and myricetin. The absorption spectra are simulated by exploiting a fully polarizable quantum mechanical (QM)/molecular mechanics (MM) model, based on the fluctuating charge (FQ) force field. Such a model is coupled with configurational sampling obtained by performing classical molecular dynamics (MD) simulations. The calculated QM/FQ spectra are compared with the experiments. We show that an accurate reproduction of the UV/Vis spectra of the selected flavonoids can be obtained by appropriately taking into account the role of configurational sampling, polarization, and hydrogen bonding interactions.

scholarly journals Mode specific THz spectra of solvated amino acids using the AMOEBA polarizable force field

2017 ◽  
Vol 19 (7) ◽  
pp. 5579-5590 ◽  
Author(s):  
Alexander Esser ◽  
Saurabh Belsare ◽  
Dominik Marx ◽  
Teresa Head-Gordon
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Amino Acids ◽  
Force Field ◽  
Ab Initio ◽  
Polarizable Force Field

We have used the AMOEBA model to simulate the THz spectra of two zwitterionic amino acids in aqueous solution, which is compared to the results on these same systems using ab initio molecular dynamics (AIMD) simulations.

DEVELOPMENT OF A FORCE FIELD FOR ARTEMISININ AND MOLECULAR DYNAMICS SIMULATION OF THE DISSOLUTION OF ARTEMISININ IN DIFFERENT SOLVENTS

2013 ◽  
Vol 12 (05) ◽  
pp. 1350038 ◽  
Author(s):  
QUAN YANG ◽  
LUKE E. ACHENIE
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Force Field ◽  
Ethyl Acetate ◽  
Dynamics Simulation ◽  
Chemical Calculation ◽  
Dissolution Property ◽  
Simulation Results ◽  
The Difference ◽  
Acetate Aqueous Solution

Artemisinin is widely employed to treat malaria. A variety of experiments have been done to research the dissolution property of artemisinin in different solvents. To have an in-depth understanding of the property, it is essential to explore the dissolution property from molecular level with molecular dynamics (MD) simulation, which needs a satisfactory force field of artemisinin. Therefore in the research a quantum chemistry based force field was developed. The quantum chemical calculation at different levels was done and Hartree–Fock (HF) level calculation gives satisfactory results. The charge distribution was then determined successfully. The van der Waals (VDW) parameters of the C unit with sp3-C were tuned according to the difference between the dissolution enthalpy of artemisinin in ethanol and ethyl acetate. With the developed force field, MD method was employed to successfully simulate the dissolution property of artemisinin in different solvents. The simulation results show that artemisinin molecules tends to aggregate in water, while in the aqueous solution of ethanol, the same number of artemisinin molecules tends to disperse. Furthermore, simulation results show that 8 M ethyl acetate aqueous solution has better dissolution ability than 8 M ethanol aqueous. The simulation gave agreements with the experimental results.

Structures Formed by Cryoprotective Agents Used in Freezc-Etching

1971 ◽  
Vol 29 ◽  
pp. 448-449
Author(s):  
G. G. Cocks ◽  
C. E. Cluthe
Keyword(s):  
Aqueous Solution ◽  
Polyethylene Oxide ◽  
Liquid Nitrogen Temperature ◽  
Ice Crystals ◽  
Etching Technique ◽  
Structural Constituent ◽  
Cryoprotective Agents ◽  
Quick Freezing ◽  
Freeze Etching ◽  
Fractured Surface

The freeze etching technique is potentially useful for examining dilute solutions or suspensions of macromolecular materials. Quick freezing of aqueous solutions in Freon or propane at or near liquid nitrogen temperature produces relatively large ice crystals and these crystals may damage the structures to be examined. Cryoprotective agents may reduce damage to the specimem, hut their use often results in the formation of a different set of specimem artifacts.In a study of the structure of polyethylene oxide gels glycerol and sucrose were used as cryoprotective agents. The experiments reported here show some of the structures which can appear when these cryoprotective agents are used.Figure 1 shows a fractured surface of a frozen 25% aqueous solution of sucrose. The branches of dendritic ice crystals surrounded hy ice-sucrose eutectic can be seen. When this fractured surface is etched the ice in the dendrites sublimes giving the type of structure shown in Figure 2. The ice-sucrose eutectic etches much more slowly. It is the smooth continuous structural constituent surrounding the branches of the dendrites.

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