Article
Chemistry, Physical
Gyoergy Hantal, Jiri Kolafa, Marcello Sega, Pal Jedlovszky
Summary: By conducting molecular dynamics simulations, we investigate the electrical and structural properties of alkali halide solutions. Our findings reveal that capillary fluctuations significantly affect the sampled quantities, highlighting the importance of removing their smearing effect to resolve the local structure of the interfacial region. Removing the smearing effect allows for a detailed examination of the dependence of permanent and induced dipoles on the distance from the interface.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Chemistry, Physical
Andras Baranyai
Summary: This paper discusses the properties of alkali and halide ions in molecular simulation and presents a set of potentials to estimate their internal energy, density, and melting temperature. The ions have non-polarizable Gaussian charges with r(-6) attraction and exponential repulsion. The results and the difficulties of the process are discussed.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Chemistry, Physical
Xiao Liang, Meng Chen, Huijun Zhou, Runliang Zhu, Jianxi Zhu, Hongping He
Summary: Adsorption and exchange of ions on clay mineral surfaces play a crucial role in elemental partitioning in soil or marine sediments and the geological storage of toxic and radioactive waste. This study investigates cationic exchanges on the muscovite mica surface using molecular dynamic simulations. By comparing with experimental data, the study determines the most reliable force field for alkali ions.
APPLIED CLAY SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Kikuko Hayamizu, Yusuke Chiba, Tomoyuki Haishi
Summary: The study successfully measured the diffusion constants of alkali metal ions in aqueous solutions using NMR method, revealing their diffusion kinetic properties and providing important data for studying the behavior of ions in solution.
Article
Chemistry, Physical
Pavlina Matysova, Martin Lisal, Filip Moucka
Summary: It has been found that traditional molecular simulations of concentrated aqueous electrolyte solutions face limitations in accurately predicting salt solubility and faithfully modeling crystalline salts. This study aims to fill the gap in hydrate simulation studies by investigating the ability of selected force fields to model different alkali-halide hydrates. The results show that polarizable force fields are more effective in modeling hydrates compared to nonpolarizable force fields.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Polymer Science
Jiao-Ping Shang, Pin Liang, Yun Peng, Ding-Feng Xu, Yi-Bao Li
Summary: In this study, a series of dissolvable bamboo pulps with suitable molecular weight was prepared by adjusting the ratio of sodium hydroxide to hydrogen peroxide in commercial bleached bamboo pulp. The properties of regenerated cellulose fibers and films made from cellulose with different molecular weights were systematically studied, and the results showed good mechanical properties. This method provides a pathway for the preparation of dissolving pulp with different molecular weights and expands the practical applications of bamboo pulp in biomass-based materials, textiles, and biomedical materials.
Article
Materials Science, Multidisciplinary
Fujie Tang, Jianhang Xu, Diana Y. Qiu, Xifan Wu
Summary: Photoelectron spectroscopy experiments in ionic solutions provide important electronic structure information by studying the interaction between hydrated ions and water solvent. The inclusion of nuclear quantum effects (NQEs) in theoretical calculations was found to improve the agreement between theoretical predictions and experimental data, suggesting NQEs play a role in predicting the electronic structure of ion solvation in aqueous solutions.
Article
Green & Sustainable Science & Technology
Rongrong Zhang, Feng Li, Siqi Zhou, Yue Hou
Summary: In this study, the effect of surfactant type, dosage, and ultrasonic time on the dispersion of carbon nanofibers (CNFs) in aqueous and alkali solutions was investigated. CNFs were successfully dispersed in aqueous solutions using methylcellulose (MC), polycarboxylate superplasticizer (PC), and polyvinylpyrrolidone (PVP), while evident aggregations were observed in alkali solutions. PC performed better in alkali solutions and significantly improved the mechanical properties and pore structure of volcanic ash-based geopolymer nanocomposites.
JOURNAL OF CLEANER PRODUCTION
(2023)
Article
Chemistry, Physical
Xia Mu, Shengwei Yuan, Dinglin Zhang, Rui Lai, Chenyi Liao, Guohui Li
Summary: This study reveals the modulation mechanism of three alkali metal ions (Li+, Na+, and K+) on human AChE activity using simulation methods. The binding affinity and catalytic activity are found to be affected by different ion species through ion coordination and electrostatic screening effects. A cluster consisting of D330, E393, and D397 residues and three Li+ ions is critical to enzyme activity. Furthermore, an increase in ion concentration leads to lower reactivity, especially for Li+ ions. This study provides a molecular perspective on the selective modulation of enzyme catalytic processes by different ion species.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Xia Mu, Shengwei Yuan, Dinglin Zhang, Rui Lai, Chenyi Liao, Guohui Li
Summary: In this study, the modulation of alkali metal ions on the activity of human AChE was investigated using combined quantum mechanics/molecular mechanics (QM/MM) and molecular dynamics (MD) simulations. The results show that different ion species can affect the binding affinity and catalytic activity of AChE through allosteric ion coordination geometries and electrostatic screening effects. A Li+ cluster involving specific residues was found to be critical to the enzyme activity. An increase in ion concentration, especially Li+ ions, leads to lower reactivity. The selective ion binding and modulation on AChE activity are highly dependent on the ion species.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Inorganic & Nuclear
Xing Liu, Hui Li, Ting Zhang, Lei Zhang, Ming Li, Rongxing He
Summary: A zero-dimensional (0D) (H5O2)(C4H14N2S2)(2)BiCl8: Sb3+ single crystal is obtained by the cooling crystallization method, which shows reversible photoluminescence (PL) upon H5O2+Cl- removal and insertion. The significant distortion of [SbCl6](3-) octahedron induced by guest (H5O2+Cl-) removal at the ground state, especially at the excited state, is responsible for the disparate PL performance. Moreover, (C4H14N2S2)(2)BiCl7: Sb3+ exhibits a fast response (<3 s) to dilute hydrochloric acid with naked-eye perceivable PL color changes, making it a potential sensing material for hydrochloric acid.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Andras Baranyai
Summary: This study aims to find an accurate description of alkali halide properties using a force field model and presents a new combination rule to achieve accurate energy, density, and melting temperature. The results indicate that different parameters are required to describe the interactions for different ion combinations.
JOURNAL OF MOLECULAR LIQUIDS
(2022)
Article
Chemistry, Physical
Leandro Rezende Franco, Andre Luiz Sehnem, Antonio Martins Figueiredo Neto, Kaline Coutinho
Summary: A theoretical framework for studying ion thermodiffusion properties in aqueous solutions is proposed, using molecular dynamics simulations and ion force field parameters. The calculated single-ion properties show good agreement with experimental data, demonstrating excellent theoretical predictability. Differences in single-ion Soret and self-diffusion coefficients contribute to the thermoelectric field, quantified by the Seebeck coefficient.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Metallurgy & Metallurgical Engineering
Fatemeh Sadat Hoseinian, Bahram Rezai, Mehdi Safari, David Deglon, Elaheh Kowsari
Summary: This study investigated the optimal conditions for the combined separation of nickel and zinc ions using Trien and SDS, showing that nickel ion removal is higher than zinc ions, which is opposite to the order of increasing crystal ionic radius.
Article
Chemistry, Physical
Yanyan Li, Zhicong Zhou, Fu Kit Sheong, Zengshan Xing, Kam Sing Wong, Herman H. Y. Sung, Ian D. Williams, Jonathan E. Halpert
Summary: In this study, a series of alkali copper(I) iodide (ACuI)-based organic-inorganic hybrid materials with different structures and emission peaks were synthesized by adjusting the alkali atoms and organic molecules. These compounds showed strong photoluminescence (PL) with emission peaks ranging from 530-660 nm, and the highest PL quantum yield (PLQY) of 91% was achieved for KCuI2(C4H8OS)2. The materials were used to fabricate green, yellow, and red light-emitting diodes (LEDs), and a white LED with a high color rendering index of 93 was demonstrated using a mixture of Cs3Cu2I5 and Rb2Cu2I4(C4H8OS)3 powders. This work provides a new strategy for developing hybrid copper halides with tunable structures and high performance, and suggests that these compounds could be promising candidates for emission applications.
CHEMISTRY OF MATERIALS
(2023)
Article
Chemistry, Physical
Isabel Nitzke, Konstantin Fackeldey, Jadran Vrabec
Summary: Long range corrections for molecular simulations of inhomogeneous fluids with a spherical interface were presented, validated through a series of droplet simulations with different cut-off radii. The method showed good agreement with expected behavior and verified by approximating surface tension.
MOLECULAR SIMULATION
(2022)
Article
Engineering, Chemical
Ivan Antolovi, Jadran Vrabec
Summary: This article systematically investigates the vapor-liquid, liquid-liquid, and vapor-liquid-liquid equilibria of the binary system nitrogen + ethane under various temperature and pressure conditions. The results show that the molecular mixture model has accurate predictive power for the vapor-liquid equilibrium of nitrogen + ethane at low temperatures and can predict its large miscibility gap. In addition, the thermodynamic factor is sampled using Kirkwood-Buff integration and used for phase equilibrium calculations.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2022)
Article
Thermodynamics
Tobias Neumann, Elmar Baumhoegger, Roland Span, Jadran Vrabec, Monika Thol
Summary: This study experimentally investigates the homogeneous density of liquid phase of methyl diethanolamine and develops a fundamental equation of state that can calculate thermodynamic properties over a wide range of temperatures and pressures.
INTERNATIONAL JOURNAL OF THERMOPHYSICS
(2022)
Article
Thermodynamics
Andreas Paul, Elmar Baumhoegger, Andreas Elsner, Michael Reineke, Christian Hueppe, Rainer Stamminger, Heike Hoelscher, Hendrik Wagner, Ulrich Gries, Wolfgang Becker, Jadran Vrabec
Summary: This study investigates the relationship between energy consumption and operating time of household refrigerating appliances. The results show that energy consumption increases gradually with device aging, with an average increase of 27% over 16 years. Performance tests on compressors and thermal conductivity measurements of foam samples indicate minimal aging effects.
APPLIED THERMAL ENGINEERING
(2022)
Article
Thermodynamics
Johannes Rossler, Ivan Antolovic, Simon Stephan, Jadran Vrabec
Summary: In this study, the performance of thermodynamic models is evaluated with respect to Joule-Thomson inversion using 29 fluids with different molecular structures. Three types of thermodynamic models are considered, and it is found that physically motivated models provide more realistic predictions at low and moderate temperatures, while deviations are observed at high temperatures.
FLUID PHASE EQUILIBRIA
(2022)
Article
Thermodynamics
Benjamin Betken, Robin Beckmueller, Muhammad Ali Javed, Elmar Baumhogger, Roland Span, Jadran Vrabec, Monika Thol
Summary: A fundamental equation of state is presented for 1-hexene, which depends on the temperature and density as independent variables. The equation is validated by comparison with experimental data and assessment of physical behavior. Measurements of homogeneous density and speed of sound further extend the available data base.
JOURNAL OF CHEMICAL THERMODYNAMICS
(2023)
Article
Chemistry, Physical
Rene Hafner, Gabriela Guevara-Carrion, Jadran Vrabec, Peter Klein
Summary: The role of bulk viscosity is often neglected in the continuum mechanics of Newtonian fluids, but recent studies have highlighted its importance in surface and interface related phenomena, systematic model up-scaling, and the interpretation of acoustic sensor data. This study investigates the role of thermostatting schemes and numerical implementations of the Green-Kubo formalism in predicting bulk viscosity using molecular dynamics simulations. The results suggest that the sampling of bulk viscosity is a delicate challenge affected by thermostatting details and numerical subtleties.
JOURNAL OF PHYSICAL CHEMISTRY B
(2022)
Article
Chemistry, Physical
Sven Pohl, Robin Fingerhut, Monika Thol, Jadran Vrabec, Roland Span
Summary: An empirical multi-parameter equation of state is proposed for the Mie (lambda(r)-6) fluid with a repulsive exponent lambda(r) from 11 to 13, based on the reduced Helmholtz energy. The equation is extensively compared with the SAFT-VR model and proves to be a more accurate description for the considered fluid class. It is valid for reduced temperatures from 0.55 to 4.5 and for reduced pressures up to 265 times the critical pressure, with good extrapolation behavior and the occurrence of a single Maxwell loop near the triple point temperature.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Thermodynamics
Andreas Paul, Elmar Baumhoegger, Mats-Ole Dewerth, Iman Hami Dindar, Gerrit Sonnenrein, Jadran Vrabec
Summary: The technical importance of paraffins as phase change materials in heat storage systems is increasing. Knowledge of the thermal conductivity of paraffins is crucial for the design and optimization of heat storage systems. However, there is limited research on the thermal conductivity of paraffins in their solid state, with only a few specific data available and conflicting values. This study developed a measurement setup to investigate the thermal conductivity of several paraffins in the solid state, including pure n-docosane and its compounds with graphite. Significant differences were found compared to existing thermal conductivity data.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2023)
Article
Mechanics
Isabel Nitzke, Rolf Stierle, Simon Stephan, Michael Pfitzner, Joachim Gross, Jadran Vrabec
Summary: The vapor-liquid equilibria and fluid interface properties of binary mixtures containing methane or cyclohexane as fuel and nitrogen or oxygen are studied. Molecular dynamics simulation, density functional theory, and density gradient theory combined with the PC-SAFT equation of state (EOS) are used to obtain data. Good agreement is observed between the results of different methods and empirical EOS data. It is found that the equivalence of nitrogen to oxygen is limited, especially for methane propellant, and the disparities are particularly pronounced at low temperatures.
Article
Mechanics
Simon Homes, Matthias Heinen, Jadran Vrabec
Summary: The molecular interactions of various real fluids, such as argon, nitrogen, or carbon dioxide, are accurately described by the two-center Lennard-Jones plus quadrupole potential. In this study, molecular dynamics simulations were used to systematically investigate the process of evaporation. The influence of molecular anisotropy, quadrupole, and boundary conditions (liquid temperature and evaporation magnitude) was analyzed, and a method for quantifying the evaporation magnitude was developed. The results showed that spherical molecules have the highest molar and energy fluxes, and the anisotropy and quadrupole of the molecules affect several quantities. The quadrupole mainly affects the interface temperature, while the anisotropy significantly influences both the interface temperature and the molar and energy fluxes. The preferred average orientation of molecules in the interface region was also studied. The evaporation coefficient was determined, and the thermodynamic states during the evaporation process were discussed.
Article
Thermodynamics
Erich J. Mace, Jadran Vrabec
Summary: In this study, the vapor-liquid equilibria of binary mixtures including argon-ammonia, methane-ammonia, hydrogen-ammonia, nitrogen-ammonia, and oxygen-ammonia were investigated using simulations and experiments. The data provided over 2000 data points with low uncertainties, showing good agreement with literature values.
JOURNAL OF CHEMICAL AND ENGINEERING DATA
(2023)
Article
Multidisciplinary Sciences
Denis Saric, Gabriela Guevara-Carrion, Yury Gaponenko, Valentina Shevtsova, Jadran Vrabec
Summary: This study investigates the mutual diffusion of six hydrocarbons diluted in supercritical carbon dioxide (CO2) using molecular dynamics simulation. The findings reveal the peculiar behavior of the Fick diffusion coefficient of some CO2 mixtures in the extended critical region, which is attributed to pronounced clustering on the molecular scale. Furthermore, the strong dependence of the Fick diffusion coefficient on the molecular mass of the solute and the breakdown of the Stokes-Einstein relation near the Widom line are confirmed.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Physical
Denis Saric, Gabriela Guevara-Carrion, Jadran Vrabec
Summary: This study analyzes the thermophysical, transport, and structural properties of supercritical carbon dioxide (scCO(2)) and its seven binary mixtures through simulations and calculations. The results reveal the existence of a Widom line between the supercritical liquid- and gas-like regions and propose an empirical equation for predicting the Widom line.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Physics, Fluids & Plasmas
Peter Mausbach, Robin Fingerhut, Jadran Vrabec
Summary: Two boundary lines separating state regions dominated by repulsion or attraction are frequently discussed in the literature, including the Fisher-Widom line and the R = 0 line. The influence of repulsive nature on the location of the R = 0 line is analyzed for several simple fluids. Increased repulsive strength leading to the disappearance of the R = 0 line in the fluid phase is observed.
