On the Role of Solvent in the Formation of Vacancies on Ibuprofen Crystal Facets

2021 ◽  
Author(s):  
Veselina Marinova ◽  
Geoffrey P. F. Wood ◽  
Ivan Marziano ◽  
Matteo Salvalaglio
Keyword(s):  
Surface Defects ◽  
Defect Formation ◽  
Energetic Cost ◽  
Crystal Facet ◽  
Mechanism Of Defect Formation ◽  
Surface Vacancy ◽  
Racemic Ibuprofen ◽  
Dynamics Simulations ◽  
Role Of Solvent

Surface defects play a crucial role in the process of crystal growth, as the incorporation of growth units generally takes place on under-coordinated sites on the growing crystal facet. In this work, we use molecular dynamics simulations to obtain information on the role of the solvent in the roughening of three morphologically-relevant crystal faces of form I of racemic ibuprofen. To this aim, we devise a computational strategy based on combining independent Well Tempered Metadynamics with Mean Force Integration. This approach enables us to evaluate the energetic cost associated with the formation of a surface vacancy for a set of ten solvents, covering a range of polarities and hydrogen-bonding ability. We find that both the mechanism of defect formation on these facets and the work associated with the process are indeed markedly solvent-dependent. The methodology developed in this work has been designed with the aim of capturing solvent effects at the atomistic scale while maintaining the computational efficiency necessary for implementation in high-throughput computational screenings of crystallization solvents.

An Atomistic Simulation Study of the Role of Asperities and Indentations on Heterogeneous Bubble Nucleation

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Brian R. Novak ◽  
Edward J. Maginn ◽  
Mark J. McCready
Keyword(s):  
Heat Flux ◽  
Atomistic Simulation ◽  
Surface Defects ◽  
Constant Heat Flux ◽  
Bubble Nucleation ◽  
Nonequilibrium Molecular Dynamics ◽  
Lennard Jones ◽  
Dynamics Simulations ◽  
Fluid Interaction

Heterogeneous bubble nucleation was studied on surfaces having nanometer scale asperities and indentations as well as different surface-fluid interaction energies. Nonequilibrium molecular dynamics simulations at constant normal stress and either temperature or heat flux were carried out for the Lennard–Jones fluid in contact with a Lennard–Jones solid. When surface defects were of the same size or smaller than the estimated critical nucleus (the smallest nucleus whose growth is energetically favored) size of 1000–2000Å3, there was no difference between the defected surfaces and atomically smooth surfaces. On the other hand, surfaces with significantly larger indentations had nucleation rates that were about two orders of magnitude higher than the systems with small defects. Moreover, nucleation was localized in the large indentations. This localization was greatest under constant heat flux conditions and when the solid-fluid interactions were weak. The results suggest strategies for enhancing heterogeneous bubble nucleation rates as well as for controlling the location of nucleation events.

The dynamical role of solvent on the ICN photodissociation reaction: connecting experimental observables directly with molecular dynamics simulations

2011 ◽  
Vol 13 (18) ◽  
pp. 8269 ◽  
Author(s):  
Christopher A. Rivera ◽  
Nicolas Winter ◽  
Rachael V. Harper ◽  
Ilan Benjamin ◽  
Stephen E. Bradforth
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Dynamics Simulations ◽  
Role Of Solvent

Solvent effect on xylose conversion under catalyst-free conditions: insights from molecular dynamics simulation and experiments

2020 ◽  
Vol 22 (2) ◽  
pp. 532-539 ◽  
Author(s):  
Qixuan Lin ◽  
Shouwei Liao ◽  
Libo Li ◽  
Weiying Li ◽  
Fengxia Yue ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Solvent Effect ◽  
Molecular Dynamics Simulations ◽  
Dynamics Simulation ◽  
Catalyst Free ◽  
Dynamics Simulations ◽  
Role Of Solvent

In this study, experiments and molecular dynamics simulations were combined to get insights into the role of solvent during the process of xylose conversion under catalyst-free conditions.

scholarly journals Исследование радиационных эффектов в МОП-транзиcторе с p-каналом

2020 ◽  
Vol 54 (8) ◽  
pp. 729
Author(s):  
А.В. Кузьминова ◽  
Н.А Куликов ◽  
В.Д. Попов
Keyword(s):  
Surface Defect ◽  
Surface Defects ◽  
Defect Formation ◽  
Surface Region ◽  
Hot Electrons ◽  
Formation Processes ◽  
Passive Mode ◽  
Near Surface ◽  
Mos Transistor

The effect of gamma radiation on the formation of surface defects at the Si−SiO2 interface in a MOS transistor with a p-channel in the passive mode is considered. Several surface defect formation processes were observed. The role of molecular hydrogen in the gate oxide of the MOS transistor and ”hot“ electrons formed in the near-surface region of silicon is shown.

The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

2020 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Biological Imaging ◽  
Ph Sensing ◽  
Hydrophobic Residue ◽  
Ideal Candidate ◽  
Self Assembling ◽  
Sensing Applications ◽  
Β Sheets ◽  
The Stability ◽  
Dynamics Simulations

<p>pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)<sub>4</sub> systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)<sub>4</sub>-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)<sub>4</sub> containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.</p>

Exploring secondary interactions and the role of temperature in moisture-contaminated polymer networks through molecular simulations

Soft Matter ◽  
2021 ◽  
Vol 17 (10) ◽  
pp. 2942-2956
Author(s):  
Rishabh D. Guha ◽  
Ogheneovo Idolor ◽  
Katherine Berkowitz ◽  
Melissa Pasquinelli ◽  
Landon R. Grace
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Temperature Variation ◽  
Polymer Networks ◽  
Molecular Simulations ◽  
Effect Of Temperature ◽  
Secondary Interactions ◽  
Dynamics Simulations ◽  
Secondary Bonding

We investigated the effect of temperature variation on the secondary bonding interactions between absorbed moisture and epoxies with different morphologies using molecular dynamics simulations.

scholarly journals Towards designing globular antimicrobial peptide mimics: role of polar functional groups in biomimetic ternary antimicrobial polymers

Soft Matter ◽  
2021 ◽  
Author(s):  
Garima Rani ◽  
Kenichi Kuroda ◽  
Satyavani Vemparala
Keyword(s):  
Molecular Dynamics ◽  
Antimicrobial Peptide ◽  
Bacterial Membrane ◽  
Simulation Data ◽  
Antimicrobial Polymers ◽  
Polar Groups ◽  
Methacrylate Polymers ◽  
Dynamics Simulations ◽  
Polar Functional Groups

Using atomistic molecular dynamics simulations, we study the interaction of ternary methacrylate polymers, composed of charged cationic, hydrophobic and neutral polar groups, with model bacterial membrane. Our simulation data shows...

scholarly journals Dye-Surfactant Interaction: Role of Solvent

2013 ◽  
Vol 25 (18) ◽  
pp. 10499-10503 ◽  
Author(s):  
Ziya Ahmad Khan ◽  
Abdullah S. Al-Bogami
Keyword(s):  
Role Of Solvent
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