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1

Synergistic mechanism of dodecylamine/octanol mixtures enhancing lepidolite flotation from the self-aggregation behaviors at the air/liquid interface

Bai Yang, Xu Mengxu, Wen Weixiang, Zhu Shifei, Mo Weichen, Yan Pingke

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 6

art. no. 176510

EN

Surface tension measurements and molecular dynamics (MD) simulations were used to explore the flotation foam properties and self-aggregation behaviors of dodecylamine (DDA)/octanol (OCT) mixtures formed with different mole ratios at the air/liquid interface. Based on the surface and thermodynamic parameters, the DDA/OCT mixtures exhibited greater interfacial activities and adsorption capacities than their individual components. The MD simulations showed that DDA and OCT were aggregated through hydrogen bonding, coulombic forces and hydrophobic association. OCT was inserted into the DDA adsorption layer, causing the alkyl chains of both DDA and OCT to extend from water to air at varying heights and angles. The addition of OCT improved the hydration of the amino groups and reduced the overall number of hydrogen bonds. The stability of the flotation foam decreased, and the high viscosity and difficult defoaming of the DDA flotation foam were significantly improved. When the DDA/OCT mole ratio was 2:1, the included angle formed between the alkyl chains and the interface was maximized, leading to enhanced compatibility among the alkyl chains, and the hydrogen bond energy was relatively large, which showed a strong synergistic effect. The MD simulation findings were consistent with the results obtained from the lepidolite flotation and surface tension experiments conducted in this study; our results could provide a theoretical foundation for the selection of superior mixed collectors and frothers.

2

Dopant ions size impact on structural properties of ordered poly(3,4-ethylenedioxythiophene) systems

Śniechowski Maciej, Kozik Tomasz A., Łużny Wojciech

Polimery

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2020

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T. 65, nr 9

639--643

EN

The purpose of this work was to determine whether the structures of ordered part of novel poly(3,4-ethylenedioxythiophene) PEDOT : OTf (doped with trifluoromethanesulfonate anions) and PEDOT : HSulf (doped with hydrogensulfate anions) systems could really be simply the layered structure of PEDOT : Tos (doped with tosylate anions) with the counter ion changed to the appropriate one. Insight into this problem could be provided by molecular dynamics simulations but also by swarm intelligence optimization, developed earlier for the purpose of investigating the other structures.

PL

Zbadano zdolność struktury uporządkowanej części nowych układów domieszkowanych poli(3,4-etylenodioksytiofenu) (PEDOT) [PEDOT : OTf (domieszkowane anionami trifluorometanosulfonianowymi) i PEDOT : HSulf (domieszkowane anionami wodorosiarczanowymi)] do powielania znanej z literatury warstwowej struktury PEDOT : Tos (domieszkowane anionami tosylanowymi) z jonem domieszki zmienionym na odpowiedni. Poszukiwania nowych struktur wspomagano symulacjami dynamiki molekularnej, a także z zastosowaniem optymalizacji opartej na algorytmach inteligencji stadnej.

3

Molecular dynamics study on axial elastic modulus of carbon nanoropes

Mehralian Fahimeh, Firouz-Abadi R. D., Norouzi M.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

1127--1134

EN

Carbon nanoropes (CNRs) are of interest for a wide variety of nanotechnological applica-tions. Since little attention has been paid to mechanical properties of CNRs, their axial elasticmodulus is explored herein. Molecular dynamics (MDs) simulations are adopted for analysisof Young's modulus of CNRs. It is also shown that increase in the initial helical angledecreases Young's modulus; however, by increase in the number of CNTs and strands,different influence on Young's modulus emerges. Therefore, the highest value of Young'smodulus obtained at the lower value of initial helical angle and consequently, Young'smodulus of bundle of straight CNTs is higher than CNRs with hierarchical helical structure. Itis further observed that Young's modulus experiences a non-monotonic variation withrespect to the number of CNTs (n) and strands (N) such that the increasing procedure ofYoung's modulus with respect to the number of CNTs and strands switches to decrease onesat n = 4 and N = 3. Therefore, the results obtained in the present study assist to control theelastic property of CNR by suitable design of number of CNTs, strands and initial helicalangle of CNT and strand and can lead to inspire optimal design of advanced nanostructures.

4

Probing of Cu2+ ions binding to A β (5−16) peptide using ITC measurements and MD simulations

Makowska J., Żmudzińska W., Wyrzykowski D., Brzozowski K., Zblewska H., Chmurzyński L.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2016

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Vol. 20, No 4

409--416

EN

It is shown that probably three residues: His6, His14 and His16 in the original sequence A β (1−42) serve as metal-binding sites for Cu2+ions. On the other hand, there is a possibility that only one of them plays a crucial role in the formation of the{A β (1-42)-Cu2+} complex. The isothermal titration calorimetry (ITC) measurements supported by molecular dynamic simulation (MD) with the NMR-derived restrains were used to investigate the interactions of Cu2+ with A β(5-16), a fragment of the A β(1-42) protein, with the following sequence: Ac-Arg-His-Asp-Ser-Gly-Tyr-Glu-Val-His-His-Gln-Lys-NH2, termed HZ1. The conditional thermodynamic parameters suggest that the formation of the Cu2+-HZ1 complex is both an enthalpy and entropy driven process under the experimental conditions. The studies presented here (after comparison with our previous results) show that the affinity of peptides to copper metal ions depends on two factors: the primary structure (amino acid composition) and the shape of the peptide conformation adopted.

5

Limitations of Applicability of the Green-Kubo Approach for Calculating the Thermal Conductivity of a Confined Liquid in Computer Simulations

Hyżorek K., Tretiakov K. V.

Computational Methods in Science and Technology

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2016

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Vol. 22, No. 4

197--200

EN

: Thermal conductivity (λ) of the Lennard-Jones liquid in cylindrical nanochannels has been determined using the Green-Kubo (GK) approach in equilibrium Molecular Dynamics simulations. Good convergence of λ(τ ) has been observed along the nanochannel’s axis where the periodic boundary conditions are applied. However, it has been found that the estimation of limiting value of λ(τ ) in the transverse direction, where walls confine the liquid, is ambiguous.

6

Growth of intermetallic compound between indium-based thermal interface material and copper substrate: molecular dynamics simulations

Fałat T., Płatek B.

Materials Science Poland

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2015

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Vol. 33, No. 2

445--450

EN

The diffusion phenomenon occurring between copper and indium was investigated by molecular dynamics simulations. The calculations were carried out in various temperatures in aging domain with the use of the commercially available Materials Studio v.6. software. The results showed that the intermetallic compound (IMC) growth followed the parabolic law, which indicated this growth to be mainly controlled by volume diffusion. The growth activation energy was estimated at 7.48 kJ.mol(-1).

7

Molecular dynamics study of Cu-Pd ordered alloys

Özdemir Kart S., Erbay A., Kiliç H., Cagin T., Tomak M.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 31, nr 1

41-46

EN

Purpose: The goal of the paper is to study the molecular dynamics of Cu-Pd ordered alloys. Design/methodology/approach: The thermal and mechanical properties of Cu, Pd pure metals and their ordered intermetallic alloys of Cu3Pd(L12) and CuPd3(L12) are studied by using the molecular dynamics simulation. The melting behavior of the metals considered in this work is studied by utilizing quantum Sutton-Chen (Q-SC) many-body potential. The effects of temperature and concentration on the physical properties of Cu-Pd system are analyzed. Findings: A wide range of properties of Cu, Pd pure metals and their Cu3Pd and CuPd3 ordered intermetallics is presented. It was found that this potential is suitable to give the general characteristics of the melting process in these systems. Practical implications: The simulation results such as cohesive energy, density, elastic constants, bulk modulus, heat capacity, thermal expansion and melting points are in good agreement with the available experimental data and other theoretical calculations. Originality/value: To the best our knowledge this work presents, for the first time, a wide range of physical properties of alloys focusing on Cu-Pd ordered compounds.

8

The structure of Pb-PbO-SiO2 glass via molecular dynamics simulation

Rybicki J., Witkowska A., Bergmański G., Mancini G., Feliziani S.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2003

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Vol. 7, No 2

243-256

EN

The paper is dedicated to a molecular dynamics (MD) study of the structure of partially reduced lead-silicate glass of composition 1Pb 1PbO 1SiO2. The simulations have been performed in the constant volume regime, using a two-body potential (Born-Mayer repulsive forces, and Coulomb forces due to full ionic charges). The system was initially prepared as a well equilibrated hot melt, and then slowly cooled down to 300K. The information on short-range correlations were obtained in a conventional way (from pair and angular distribution functions), while the medium-range order was studied via cation-anion ring analysis. In the paper, the short- and medium-range order in the simulated system is discussed and compared with the structure of a glassy completely reduced system, i.e. 2Pb 1SiO2 and unreduced one, i.e. 2PbO 1SiO2 glass.

9

Gel–glass transition in silica and nitrided silica aerogels – experiment and computer modelling

Szaniawska K., Murawski L., Rybicki J., Witkowska A., Walewski M.

Optica Applicata

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2003

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Vol. 33, nr 1

75-81

EN

Nitrided silica aerogel was sintered at 1600 °C in vacuum or nitrogen atmosphere and the effect of densification was compared with that observed in silica aerogel. It has been shown that homogeneous oxynitride glasses containing 8.4–13 wt% can be obtained by densification of nitrided aerogels. The densification process of nitrided aerogels was simulated by computer modeling using classical molecular dynamics (MD) simulations. MD simulations have shown that densification process proceeds in a similar way as in the experiment. In addition, the simulations indicate that oxynitride glasses can be obtained by densification of Si–O–N system.

10

Preferential solvation of amides by methanol - a comparison of molecular dynamics calculations with the experimental data

Zielkiewicz J.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2001

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Vol. 5, No 3

317-329

EN

Using the Kirkwood-Buff theory of solutions, the preferential solvation of the N-methylacet-amide (NMA), N-methylformamide, (NMF), and N,N-dimethylformamide, (DMF), molecule has been investigated in the binary {amide+methanol} mixtures at 313.15 K. Moreover, for the {amide+methanol} mixtures, where amide = NMF, DMF, and NMA, the molecular dynamics calculations at xamide=0.518 were performed. From the obtained molecule-molecule radial distribution functions, (rdf), and atom-atom rdf, it was possible to estimate the local mole fractions around the amide molecule, the orientation effects of molecules within the solvation shell, and a possibility of the formation of complexes. The general picture obtained from analysis of the molecular dynamics results is consistent with the deductions derived from thermodynamic data.

11

Flows in microchannels

Kucaba-Piętal A., Walenta Z., Peradzyński Z.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2001

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Vol. 5, No 2

179-189

EN

The aim of this paper is to present a survey of the results for the flows of simple gases and liquids with substructure through narrow channels, obtained with the Direct Monte-Carlo and Molecular Dynamics Simulation methods.

12

Metal atom clustering in reduced lead-, bismuth- and antimony-silicate glasses: a comparative molecular dynamics study.

Witkowska A., Rybicki J., Bośko J., Feliziani S.

Optica Applicata

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2000

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Vol. 30, nr 4

685-689

EN

We report on the results of molecular dynamics (MD) simulations of the formation of metallic granules in totally reduced lead-, bismuth- and antimony-silicate glasses of composition xMe(1-x)SiO/sub 2/, Me=Pb, Pi Sb, x=0.25, 0.5. The simulations were performed in the NVE ensemble, with two-body Born-Mayer-Huggins interaction potential. For all the glasses considered a strong tendency of heavy metal atoms to agglomerate was observed. In this contribution we compare the distributions of the sizes of Pb, Bi and Sb granules and their packing.