Ranking Anti-Agglomerant Efficiency for Gas Hydrates Through Molecular Dynamic Simulations

2021 ◽  
Author(s):  
Stephan Mohr ◽  
Felix Hoevelmann ◽  
Jonathan Wylde ◽  
Natascha Schelero ◽  
Juan Sarria ◽  
...  

Abstract Computational and experimental methods were employed to assess the capacity of four surfactant molecules to inhibit the agglomeration of sII hydrate particles. Using both steered and non-steered Molecular Dynamics (MD), the coalescence process of a hydrate slab and a water droplet, both covered with surfactant molecules, was computationally simulated. The experimental assessment was based on rocking cell measurements, determining the minimum effective dose necessary to inhibit agglomeration. Overall, the performance ranking obtained by the simulations and the experimental measurements agreed very well. Moreover, the simulations gave additional insights that are not directly accessible via experiments, such as an analysis of the mass density profiles or the orientations of the surfactant tails. The possibility to perform systematic computational high-throughput screenings of many molecules allows an efficient funnel approach for molecular optimization and customization.

2021 ◽  
Vol 125 (5) ◽  
pp. 1487-1502
Author(s):  
Stephan Mohr ◽  
Felix Hoevelmann ◽  
Jonathan Wylde ◽  
Natascha Schelero ◽  
Juan Sarria ◽  
...  

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pranay Asai ◽  
Palash Panja ◽  
Raul Velasco ◽  
Milind Deo

AbstractThe pressure-driven flow of long-chain hydrocarbons in nanosized pores is important in energy, environmental, biological, and pharmaceutical applications. This paper examines the flow of hexane, heptane, and decane in carbon nanotubes (CNTs) of pore diameters 1–8 nm using molecular dynamic simulations. Enhancement of water flow in CNTs in comparison to rates predicted by continuum models has been well established in the literature. Our work was intended to observe if molecular dynamic simulations of hydrocarbon flow in CNTs produced similar enhancements. We used the OPLS-AA force field to simulate the hydrocarbons and the CNTs. Our simulations predicted the bulk densities of the hydrocarbons to be within 3% of the literature values. Molecular sizes and shapes of the hydrocarbon molecules compared to the pore size create interesting density patterns for smaller sized CNTs. We observed moderate flow enhancements for all the hydrocarbons (1–100) flowing through small-sized CNTs. For very small CNTs the larger hydrocarbons were forced to flow in a cork-screw fashion. As a result of this flow orientation, the larger molecules flowed as effectively (similar enhancements) as the smaller hydrocarbons.


2020 ◽  
Vol 633 ◽  
pp. L3 ◽  
Author(s):  
Nushkia Chamba ◽  
Ignacio Trujillo ◽  
Johan H. Knapen

Now almost 70 years since its introduction, the effective or half-light radius has become a very popular choice for characterising galaxy size. However, the effective radius measures the concentration of light within galaxies and thus does not capture our intuitive definition of size which is related to the edge or boundary of objects. For this reason, we aim to demonstrate the undesirable consequence of using the effective radius to draw conclusions about the nature of faint ultra-diffuse galaxies (UDGs) when compared to dwarfs and Milky Way-like galaxies. Instead of the effective radius, we use a measure of galaxy size based on the location of the gas density threshold required for star formation. Compared to the effective radius, this physically motivated definition places the sizes much closer to the boundary of a galaxy. Therefore, considering the sizes and stellar mass density profiles of UDGs and regular dwarfs, we find that the UDGs have sizes that are within the size range of dwarfs. We also show that currently known UDGs do not have sizes comparable to Milky Way-like objects. We find that, on average, UDGs are ten times smaller in extension than Milky Way-like galaxies. These results show that the use of size estimators sensitive to the concentration of light can lead to misleading results.


Sign in / Sign up

Export Citation Format

Share Document