scholarly journals Study on Adsorption Characteristics of Sulfonate Gemini Surfactant on Lignite Surface

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1401
Author(s):  
Xuanlai Chen ◽  
Guochao Yan ◽  
Xianglin Yang ◽  
Guang Xu
Keyword(s):  
Hydrogen Bonds ◽  
Gemini Surfactants ◽  
Relative Concentration ◽  
Sodium Dodecyl ◽  
Large Angle ◽  
Molecular Chain ◽  
Dynamics Simulation ◽  
Practical Significance ◽  
Adsorption Characteristics ◽  
Binary Model

In order to explore the adsorption characteristics of sulfonate gemini surfactants on the surface of lignite, the molecular dynamics simulation method was used, and A kind of sulfonic acid bis sodium salt (S2) and the sodium dodecyl sulfate (SDS) were selected. A binary model of surfactant/lignite adsorption system and a ternary model of water/surfactant/lignite system were constructed, and a series of properties such as adsorption configuration, interaction energy, order parameters, relative concentration distribution, number of hydrogen bonds, etc., were analyzed. The results showed that the adsorption strength of S2 on the surface of lignite was higher than that of SDS. The results indicated that the large-angle molecular chain in S2 tended to become smaller, the small-angle molecular chain tended to become larger, and the angle between the molecular chains and the Z axis tended to be concentrated, making the formed network structure denser during the adsorption process. The number of hydrogen bonds in the water-coal system was 42, and the number of hydrogen bonds in the system after S2 adsorption was 15, which was much lower than the 23 hydrogen bonds in the system after SDS adsorption, and S2 could better adsorb and wrap the oxygen-containing groups on the surface of the lignite. The comparative study of the adsorption characteristics of the two surfactants on the surface of lignite can help us better understand the influence of the surfactant structure on the adsorption strength. The research results have important theoretical and practical significance for developing new surfactants, and enriching and developing the basic theory of coal wettability.

scholarly journals Virtual Screening for Potential Inhibitors of Human Hexokinase II for the Development of Anti-Dengue Therapeutics

BioTech ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Suriyea Tanbin ◽  
Fazia Adyani Ahmad Fuad ◽  
Azzmer Azzar Abdul Hamid
Keyword(s):  
Hydrogen Bonds ◽  
Binding Energies ◽  
Host Cells ◽  
Dynamics Simulation ◽  
Hexokinase Ii ◽  
Tropical Regions ◽  
Lipinski’S Rule ◽  
Viral Propagation ◽  
C Terminus ◽  
Similarity Scores

Dengue fever, which is a disease caused by the dengue virus (DENV), is a major unsolved issue in many tropical and sub-tropical regions of the world. The absence of treatment that effectively prevent further viral propagation inside the human’s body resulted in a high number of deaths globally each year. Thus, novel anti-dengue therapies are required for effective treatment. Human hexokinase II (HKII), which is the first enzyme in the glycolytic pathway, is an important drug target due to its significant impact on viral replication and survival in host cells. In this study, 23.1 million compounds were computationally-screened against HKII using the Ultrafast Shape Recognition with a CREDO Atom Types (USRCAT) algorithm. In total, 300 compounds with the highest similarity scores relative to three reference molecules, known as Alpha-D-glucose (GLC), Beta-D-glucose-6-phosphate (BG6), and 2-deoxyglucose (2DG), were aligned. Of these 300 compounds, 165 were chosen for further structure-based screening, based on their similarity scores, ADME analysis, the Lipinski’s Rule of Five, and virtual toxicity test results. The selected analogues were subsequently docked against each domain of the HKII structure (PDB ID: 2NZT) using AutoDock Vina programme. The three top-ranked compounds for each query were then selected from the docking results based on their binding energy, the number of hydrogen bonds formed, and the specific catalytic residues. The best docking results for each analogue were observed for the C-terminus of Chain B. The top-ranked analogues of GLC, compound 10, compound 26, and compound 58, showed predicted binding energies of −7.2, −7.0, and −6.10 kcal/mol and 7, 5, and 2 hydrogen bonds, respectively. The analogues of BG6, compound 30, compound 36, and compound 38, showed predicted binding energies of −7.8, −7.4, and −7.0 kcal/mol and 11, 9, and 5 hydrogen bonds, while the top three analogues of 2DG, known as compound 1, compound 4, and compound 31, showed predicted binding energies of −6.8, −6.3, and −6.3 kcal/mol and 4, 3, and 1 hydrogen bonds, sequentially. The highest-ranked compounds in the docking analysis were then selected for molecular dynamics simulation, where compound 10, compound 30, and compound 1, which are the analogues of GLC, BG6, and 2DG, have shown strong protein-ligand stability with an RMSD value of ±5.0 A° with a 5 H bond, ±4.0 A° with an 8 H bond, and ±0.5 A° with a 2 H bond, respectively, compared to the reference molecules throughout the 20 ns simulation time. Therefore, by using the computational studies, we proposed novel compounds, which may act as potential drugs against DENV by inhibiting HKII’s activity.

scholarly journals Conformation and membrane interaction studies of the potent antimicrobial and anticancer peptide palustrin-Ca

2021 ◽  
Author(s):  
Patrick Brendan Timmons ◽  
Chandralal M Hewage
Keyword(s):  
Sodium Dodecyl ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Peptide Sequence ◽  
Helical Conformation ◽  
Dimensional Structure ◽  
Amino Acid Residues ◽  
Anticancer Activities ◽  
American Bullfrog ◽  
Α Helix

Palustrin-Ca (GFLDIIKDTGKEFAVKILNNLKCKLAGGCPP) is a host defense peptide with potent antimicrobial and anticancer activities, first isolated from the skin of the American bullfrog Lithobates catesbeianus. The peptide is 31 amino acid residues long, cationic and amphipathic. Two-dimensional NMR spectroscopy was employed to characterise its three-dimensional structure in a 50/50% water/2,2,2-trifluoroethanol-d3 mixture. The structure is defined by an α-helix that spans between Ile6-Ala26, and a cyclic disulphide bridged domain at the C-terminal end of the peptide sequence, between residues 23 and 29. A molecular dynamics simulation was employed to model the peptide's interactions with sodium dodecyl sulphate micelles, a widely used bacterial membrane-mimicking environment. Throughout the simulation, the peptide was found to maintain its α-helical conformation between residues Ile6-Ala26, while adopting a position parallel to the surface to micelle, which is energetically-favourable due to many hydrophobic and electrostatic contacts with the micelle.

scholarly journals Manuscript-C-dots assembly at interface-041020.pdf

2020 ◽  
Author(s):  
Amin Reza Zolghadr ◽  
Behnam Rostami
Keyword(s):  
Self Assembly ◽  
Carbon Dots ◽  
Sodium Dodecyl ◽  
Surface Region ◽  
Systematic Investigation ◽  
Dynamics Simulation ◽  
Surface Tension Gradient ◽  
Bivariate Analysis ◽  
Air Interface ◽  
Sds Surfactant

We describe a systematic investigation of carbon dots (C-dots) assemblies fabricated at the liquid/air interface because of the surface tension gradient. This gradient is originally created by capillary action and increased by addition of sodium dodecyl sulfate (SDS) surfactant or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) phospholipid to the surface of C-dots aqueous mixture. The arrangement of carbon dots in liquid bulk phase (before self-assembly) and at the surface region (after self-assembly) was examined by TEM microscopy. The presence of SDS surfactant and POPC phospholipid at the air/water interface induced the C-dots compression. In addition, molecular dynamics simulation was conducted to obtain the structure of C-dots at liquid/vapor interface. The orientation of C-dots is evaluated quantitatively at water/vapor surface by using bivariate analysis.

The Optimum Arrangement of Working Face Ventilation System for Coal Mine

2012 ◽  
Vol 482-484 ◽  
pp. 1691-1694
Author(s):  
Ning He ◽  
Qiu Ju Ma ◽  
Yu Zhu Shi
Keyword(s):  
Coal Mine ◽  
Ventilation System ◽  
Dynamics Simulation ◽  
Practical Significance ◽  
Gas Migration ◽  
Optimal Layout ◽  
High Concentration ◽  
Working Surface ◽  
Working Face ◽  
Optimum Arrangement

It was most effective and practical that using computational fluid dynamics simulation to analyze the distribution of flow field in gob for studying optimal layout scheme of the working face ventilation system. In this paper, numerical simulation was applied for studying the migration laws and high concentration of gas gathering area of N1201 working face in Tunliu Coal Mine; the gob of robbing working surface gas migration laws and high concentration of gas gathering area was obtained; the optimum arrangement of ventilation system for the working face was given. The conclusions had a certain theoretical value and practical significance for controlling the working face gas.

Paper 20. Improvement of Control by Special Devices

1972 ◽  
Vol 14 (7) ◽  
pp. 150-154
Author(s):  
H. Ritter
Keyword(s):  
Large Angle ◽  
Leading Edge ◽  
Rotating Cylinder ◽  
Practical Significance ◽  
Trailing Edge ◽  
Stall Angle ◽  
Lift Control ◽  
And Control

The paper discusses hydrodynamic devices for improving manoeuvring and control. Two hydrodynamic concepts are shown to be of practical significance for large craft: control of hydrofoil lift independent of incidence, and deflection of the propulsion jet through a large angle by means of a simple hydrofoil. Lift control independent of incidence is illustrated by the jet flap and the trailing edge rotating cylinder. Improved deflection of the propeller slipstream involves extending the rudder stall angle, and it is shown how this may be achieved by fitting the rudder with a leading edge rotating cylinder.

scholarly journals Emulsification of Surfactant on Oil Droplets by Molecular Dynamics Simulation

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3008
Author(s):  
Yaoshuang Cheng ◽  
Shiling Yuan
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Heavy Oil ◽  
Molecular Level ◽  
Sodium Dodecyl ◽  
Mean Square Displacement ◽  
Dynamics Simulation ◽  
Oil Droplets ◽  
Hydration Layer ◽  
Oil Droplet

Heavy oil in crude oil flooding is extremely difficult to extract due to its high viscosity and poor fluidity. In this paper, molecular dynamics simulation was used to study the emulsification behavior of sodium dodecyl sulfonate (SDSn) micelles on heavy oil droplets composed of asphaltenes (ASP) at the molecular level. Some analyzed techniques were used including root mean square displacement, hydrophile-hydrophobic area of an oil droplet, potential of mean force, and the number of hydrogen bonds between oil droplet and water phase. The simulated results showed that the asphaltene with carboxylate groups significantly enhances the hydration layer on the surface of oil droplets, and SDSn molecules can change the strength of the hydration layer around the surface of the oil droplets. The water bridge structure between both polar heads of the surfactant was commonly formed around the hydration layer of the emulsified oil droplet. During the emulsification of heavy oil, the ratio of hydrophilic hydrophobic surface area around an oil droplet is essential. Molecular dynamics method can be considered as a helpful tool for experimental techniques at the molecular level.

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