In this paper, the charge distribution, the chemical bond order and the reactive performance of carboxylic acid model compounds on acidic catalyst were investigated by using molecular simulation technology. The simula...In this paper, the charge distribution, the chemical bond order and the reactive performance of carboxylic acid model compounds on acidic catalyst were investigated by using molecular simulation technology. The simulation results showed that the bond order of C—O was higher than that of C—C, and C—C bond connected to the carbon atom in the carboxyl radical had the lowest bond order. The charge distributions of model naphthenic acids were similar in characteristics that the negative charges were concentrated on carboxyls. According to the simulation results, the mechanisms of catalytic decar- boxylation over acidic solid catalyst were proposed, and a new route was put forward regarding removal of the naphthenic acid from crude oil through catalytic decarboxylation.展开更多
Polylactic acid(PLA)possesses good mechanical and biodegradability properties which make it a suitable material for polymer composites whereas brittleness and high costs limit its utilization in various applications.T...Polylactic acid(PLA)possesses good mechanical and biodegradability properties which make it a suitable material for polymer composites whereas brittleness and high costs limit its utilization in various applications.The reinforcement of natural fibres with biopolymers has been formed to be an efficient technique to develop composites having the ability to be fully biodegradable.This study concerns with the incorporation of various percentages of untreated and alkali-treated Coir Fibres(CF)and pineapple leaf fibres(PALF)in PLA biocomposites and characterizations of flexural,morphological and dynamic mechanical properties.Flexural properties showed that the treated C1P1 hybrid composites(C1P1A)displayed highest flexural strength(35.81 MPa)and modulus(5.28 GPa)among all hybrid biocomposites.Scanning Electron Microscopy(SEM)revealed a behaviour of fibre-matrix adhesion in untreated treated biocomposites.SEM observation revealed good dispersion of the fillers in PLA.Dynamic mechanical analysis revealed that C1P1A showed highest glass transition temperature(Tg)and storage modulus(E')while untreated C3P7 displayed the least Tg and E'.Overall findings showed that alkali-treated hybrid biocomposites(CF/PALF/PLA)especially C1P1A have improved flexural properties,dynamic and morphological properties over untreated biocomposites.Success of these findings will provide attracting consideration of these hybrid biocomposites for various lightweight uses in a broad selection of industrial applications such as biomedical sectors,automobile,construction,electronics equipment,and hardware tools.展开更多
The molecular mechanics/Poisson-Boltzmann surface area(MM/PBSA) method has been widely used in predicting the binding affinity among ligands,proteins,and nucleic acids.However,the accuracy of the predicted binding ene...The molecular mechanics/Poisson-Boltzmann surface area(MM/PBSA) method has been widely used in predicting the binding affinity among ligands,proteins,and nucleic acids.However,the accuracy of the predicted binding energy by the standard MM/PBSA is not always good,especially in highly charged systems.In this work,we take the protein-nucleic acid complexes as an example,and showed that the use of screening electrostatic energy(instead of Coulomb electrostatic energy) in molecular mechanics can greatly improve the performance of MM/PBSA.In particular,the Pearson correlation coefficient of dataset Ⅱ in the modified MM/PBSA(i.e.,screening MM/PBSA) is about 0.52,much better than that(<0.33)in the standard MM/PBSA.Further,we also evaluate the effect of solute dielectric constant and salt concentration on the performance of the screening MM/PBSA.The present study highlights the potential power of the screening MM/PBSA for predicting the binding energy in highly charged bio-systems.展开更多
文摘In this paper, the charge distribution, the chemical bond order and the reactive performance of carboxylic acid model compounds on acidic catalyst were investigated by using molecular simulation technology. The simulation results showed that the bond order of C—O was higher than that of C—C, and C—C bond connected to the carbon atom in the carboxyl radical had the lowest bond order. The charge distributions of model naphthenic acids were similar in characteristics that the negative charges were concentrated on carboxyls. According to the simulation results, the mechanisms of catalytic decar- boxylation over acidic solid catalyst were proposed, and a new route was put forward regarding removal of the naphthenic acid from crude oil through catalytic decarboxylation.
基金gratitude to Institute of Tropical Forestry and Forest Products(INTROP),Universiti Putra Malaysia for supporting the funding of research through Grant No:6369108funded by Researchers Supporting Project number(RSP-2021/117),King Saud University,Riyadh,Saudi Arabia.
文摘Polylactic acid(PLA)possesses good mechanical and biodegradability properties which make it a suitable material for polymer composites whereas brittleness and high costs limit its utilization in various applications.The reinforcement of natural fibres with biopolymers has been formed to be an efficient technique to develop composites having the ability to be fully biodegradable.This study concerns with the incorporation of various percentages of untreated and alkali-treated Coir Fibres(CF)and pineapple leaf fibres(PALF)in PLA biocomposites and characterizations of flexural,morphological and dynamic mechanical properties.Flexural properties showed that the treated C1P1 hybrid composites(C1P1A)displayed highest flexural strength(35.81 MPa)and modulus(5.28 GPa)among all hybrid biocomposites.Scanning Electron Microscopy(SEM)revealed a behaviour of fibre-matrix adhesion in untreated treated biocomposites.SEM observation revealed good dispersion of the fillers in PLA.Dynamic mechanical analysis revealed that C1P1A showed highest glass transition temperature(Tg)and storage modulus(E')while untreated C3P7 displayed the least Tg and E'.Overall findings showed that alkali-treated hybrid biocomposites(CF/PALF/PLA)especially C1P1A have improved flexural properties,dynamic and morphological properties over untreated biocomposites.Success of these findings will provide attracting consideration of these hybrid biocomposites for various lightweight uses in a broad selection of industrial applications such as biomedical sectors,automobile,construction,electronics equipment,and hardware tools.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11874045 and 11774147)。
文摘The molecular mechanics/Poisson-Boltzmann surface area(MM/PBSA) method has been widely used in predicting the binding affinity among ligands,proteins,and nucleic acids.However,the accuracy of the predicted binding energy by the standard MM/PBSA is not always good,especially in highly charged systems.In this work,we take the protein-nucleic acid complexes as an example,and showed that the use of screening electrostatic energy(instead of Coulomb electrostatic energy) in molecular mechanics can greatly improve the performance of MM/PBSA.In particular,the Pearson correlation coefficient of dataset Ⅱ in the modified MM/PBSA(i.e.,screening MM/PBSA) is about 0.52,much better than that(<0.33)in the standard MM/PBSA.Further,we also evaluate the effect of solute dielectric constant and salt concentration on the performance of the screening MM/PBSA.The present study highlights the potential power of the screening MM/PBSA for predicting the binding energy in highly charged bio-systems.
