scholarly journals Elucidating the Energetics and Effects of Solvents on Cellulose Hydrolysis Using a Polymeric Acid Catalyst

2018 ◽  
Vol 8 (10) ◽  
pp. 1767 ◽  
Author(s):  
Xiaoquan Sun ◽  
Xianghong Qian
Keyword(s):  
Free Energy ◽  
Catalytic Activity ◽  
Polymer Chain ◽  
Critical Role ◽  
Acid Catalyst ◽  
Cellulose Hydrolysis ◽  
Polymer Chains ◽  
Biomass Hydrolysis ◽  
Imidazolium Chloride ◽  
Polymeric Acid

A novel polymeric acid catalyst immobilized on a membrane substrate was found to possess superior catalytic activity and selectivity for biomass hydrolysis. The catalyst consists of two polymer chains, a poly(styrene sulfonic acid) (PSSA) polymer chain for catalyzing carbohydrate substrate, and a neighboring poly(vinyl imidazolium chloride) ionic liquid (PIL) polymer chain for promoting the solvation of the PSSA chain to enhance the catalytic activity. In order to elucidate the mechanism and determine the energetics of biomass catalytic processing using this unique catalyst, classical molecular dynamics (MD) coupled with metadynamics (MTD) simulations were conducted to determine the free energy surfaces (FES) of cellulose hydrolysis. The critical role that PIL plays in the catalytic conversion is elucidated. The solvation free energy and the interactions between PSSA, PIL, and cellulose chains are found to be significantly affected by the solvent.

Polymer Chain Deformation in Stretched and Swollen Elastomers

1986 ◽  
Vol 79 ◽  
Author(s):  
Robert Ullman
Keyword(s):  
Free Energy ◽  
Polymer Chain ◽  
Small Angle Neutron Scattering ◽  
Experimental Information ◽  
Rubber Elasticity ◽  
Polymer Chains ◽  
New Developments ◽  
Dimensional Changes ◽  
The Mean ◽  
Actual Relation

AbstractIn the early theories of rubber elasticity, the retractive force and change in free energy of a stretched specimen were calculated from the deformation of the polymer chains of which the rubber network was formed. The mean chain deformation was presumed to be the same as that of the macroscopic specimen, an assumption which seemed reasonable, but could not be confirmed experimentally. Small angle neutron scattering (SANS) made measurement of chain dimensions possible, and it was soon discovered [1], [2] that the actual relation between dimensional changes of the polymer chain and deformation of the specimen was not at all what had been assumed.SANS studies of carefully prepared elastomeric networks provide the most direct experimental information required for a molecular theory of rubber elasticity, and have stimulated many new developments.

Effect of surface acidity on the catalytic activity and deactivation of supported sulfonic acids during dehydration of methanol to DME

2020 ◽  
Vol 44 (39) ◽  
pp. 16810-16820
Author(s):  
Rosanna Viscardi ◽  
Vincenzo Barbarossa ◽  
Daniele Mirabile Gattia ◽  
Raimondo Maggi ◽  
Giovanni Maestri ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Sulfonic Acid ◽  
Water Resistance ◽  
Surface Acidity ◽  
Acid Catalyst ◽  
Acid Sites ◽  
Sulfonic Acids ◽  
Effect Of Surface

Superiorty of the supported sulfonic acid catalyst in terms of the water resistance and efficiency of the acid sites compared to the commercial reference.

Cellulase-Inspired Solid Acids for Cellulose Hydrolysis: Structural Explanations for High Catalytic Activity

ACS Catalysis ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 1464-1468 ◽  
Author(s):  
Maksim Tyufekchiev ◽  
Pu Duan ◽  
Klaus Schmidt-Rohr ◽  
Sergio Granados Focil ◽  
Michael T. Timko ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Cellulose Hydrolysis ◽  
Solid Acids ◽  
High Catalytic Activity

scholarly journals Prediction of GluN2B-CT1290-1310/DAPK1 Interaction by Protein–Peptide Docking and Molecular Dynamics Simulation

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 3018 ◽  
Author(s):  
Gao Tu ◽  
Tingting Fu ◽  
Fengyuan Yang ◽  
Lixia Yao ◽  
Weiwei Xue ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Electrostatic Interactions ◽  
Binding Free Energy ◽  
Computational Simulation ◽  
Critical Role ◽  
Dynamics Simulation ◽  
Peptide Docking ◽  
C Terminus ◽  
Free Energy Decomposition

The interaction of death-associated protein kinase 1 (DAPK1) with the 2B subunit (GluN2B) C-terminus of N-methyl-D-aspartate receptor (NMDAR) plays a critical role in the pathophysiology of depression and is considered a potential target for the structure-based discovery of new antidepressants. However, the 3D structures of C-terminus residues 1290–1310 of GluN2B (GluN2B-CT1290-1310) remain elusive and the interaction between GluN2B-CT1290-1310 and DAPK1 is unknown. In this study, the mechanism of interaction between DAPK1 and GluN2B-CT1290-1310 was predicted by computational simulation methods including protein–peptide docking and molecular dynamics (MD) simulation. Based on the equilibrated MD trajectory, the total binding free energy between GluN2B-CT1290-1310 and DAPK1 was computed by the mechanics generalized born surface area (MM/GBSA) approach. The simulation results showed that hydrophobic, van der Waals, and electrostatic interactions are responsible for the binding of GluN2B-CT1290–1310/DAPK1. Moreover, through per-residue free energy decomposition and in silico alanine scanning analysis, hotspot residues between GluN2B-CT1290-1310 and DAPK1 interface were identified. In conclusion, this work predicted the binding mode and quantitatively characterized the protein–peptide interface, which will aid in the discovery of novel drugs targeting the GluN2B-CT1290-1310 and DAPK1 interface.

scholarly journals Collapse of a polymer chain in a melt of incompatible polymer chains

1981 ◽  
Vol 42 (8) ◽  
pp. 1145-1150 ◽  
Author(s):  
J.F. Joanny ◽  
F. Brochard
Keyword(s):  
Polymer Chain ◽  
Polymer Chains

The effect of excluded volume on polymer dispersant action

1975 ◽  
Vol 343 (1635) ◽  
pp. 427-442 ◽  
Keyword(s):  
Free Energy ◽  
High Surface ◽  
Volume Effect ◽  
Polymer Chains ◽  
Excluded Volume ◽  
Density Distributions ◽  
Excluded Volume Effects ◽  
Adsorbed Polymer ◽  
Polymer Distribution ◽  
Dimensional Equation

Polymer-stabilized colloid particles are modelled theoretically by plane surfaces on to which polymer chains are adsorbed by one end only. Interactions between segments of the polymer are treated as an excluded volume effect. It is shown that for high surface densities the polymer distribution function exactly satisfies a one dimensional equation which is solved numerically for two values of excluded volume to give the polymer segment density distributions and the free energy of interaction for various separations of the plane surfaces. It is found that a positive value of excluded volume greatly increases the repulsive free energy compared with that for chains with zero excluded volume, particularly at large separation distances of the surfaces. Excluded volume effects must therefore play an important part in the stabilization of colloids by adsorbed polymer.

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