Article
Chemistry, Physical
J. Munguia-Valadez, A. Ledesma-Duran, J. A. Moreno-Razo, I. Santamaria-Holek
Summary: Nonlinear active microrheology molecular dynamics simulations reveal that strong confining forces and an external pulling force generate a correlation between velocity and position dynamics of tracer particles. This correlation is characterized by an effective temperature and an effective mobility, which disrupt the equilibrium fluctuation-dissipation theorem. By measuring the temperature and mobility of the tracer particles and formulating a diffusion theory, the effective thermal and transport properties are decoupled from the velocity dynamics. The flexibility of attractive and repulsive forces allows for the analysis of temperature and mobility behaviors in relation to interactions and the surrounding fluid structure under different pulling forces.
Article
Physics, Fluids & Plasmas
Robert S. Hoy, Kevin A. Interiano-Alberto
Summary: This study develops an algorithm for parallel molecular dynamics simulations and successfully implements it. The algorithm can simulate systems in arbitrary dimensions and handle larger system sizes. By simulating d = 6 liquids, it is discovered that the dynamics are more heterogeneous and the breakdown of the Stokes-Einstein relation is stronger than previously reported.
Article
Physics, Fluids & Plasmas
Amir Kaffashnia, Mykhaylo Evstigneev
Summary: Diffusion of Brownian particle in a stochastic harmonic oscillator chain is studied. The particle exhibits long Lévy flights at high temperatures, in contrast to the usual Brownian motion driven by Gaussian white noise. The diffusion coefficient and the average damping force depend on the temperature, and the average flight time and flight length have a certain proportionality at high temperatures. The probability distribution of flight lengths decays with a universal exponent.
Article
Chemistry, Physical
Patrick Charbonneau, Yi Hu, Joyjit Kundu, Peter K. Morse
Summary: The formulation of mean-field infinite-dimensional solution of hard sphere glasses is a significant advancement in theoretical physics. However, its relevance in understanding low-dimensional glass-forming liquids is still unclear. By revisiting simulation techniques and leveraging standard liquid-state theory, the study of hard sphere liquids up to d = 13 has become possible, helping to bridge the gap between different approaches.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Golam Rosul Khan, Snehasis Daschakraborty
Summary: Calculating the shear viscosity of liquid water under nanoconfinement is difficult but important in nanofluidics. Traditional viscosity calculation methods are less useful for water confined in cylindrical nanotubes. Using a novel method based on the JCSE relation, we found that the viscosity of water inside hydrophobic CNTs is surprisingly higher than bulk water, contrary to previous theoretical observations.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Mathematics, Applied
Jurgen Julio-Batalla, Jimmy Petean
Summary: For a closed cohomogeneity one Riemannian manifold of dimension n ≥ 3 with positive Ricci curvature, infinite nodal solutions for certain equations can be proven to exist. Specifically, for a positive Einstein manifold of cohomogeneity one or fibered over such a manifold, the existence of infinite nodal solutions for the Yamabe equation can be established with a prescribed number of connected components of its nodal domain.
PROCEEDINGS OF THE AMERICAN MATHEMATICAL SOCIETY
(2021)
Article
Mathematics, Applied
John D. Carter
Summary: This study investigates the traveling wave solutions and stability of the Whitham equation, revealing that the Hamiltonian oscillates at least twice when the solutions are sufficiently steep and a superharmonic instability is created at each extremum of the Hamiltonian. The stability spectra also undergo similar bifurcations between each extremum. Furthermore, a comparison with the results from the Euler equations is presented.
STUDIES IN APPLIED MATHEMATICS
(2023)
Article
Chemistry, Physical
Laxmikanta Khamari, Saptarshi Mukherjee
Summary: This study used single-molecule FRET to investigate the conformational dynamics of c-MYC promoter-based i-motif structures in confined environments. The research found that the folding of these motifs is not a direct transition from random coil to i-motif conformation, but occurs through a partially folded intermediate.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Engineering, Marine
Hijaz Ahmad, Tufail A. Khan, Hulya Durur, G. M. Ismail, Asif Yokus
Summary: Modified versions of variational iteration algorithms are introduced for numerical simulation of oil pollution diffusion in this article, with three numerical examples provided to demonstrate their applicability and validity. The comparison with existing solutions shows the effectiveness of the proposed methods, which can be applied to other nonlinear initial value problems in science and engineering.
JOURNAL OF OCEAN ENGINEERING AND SCIENCE
(2021)
Article
Multidisciplinary Sciences
Takeshi Baba, Seiji Kajita, Tohru Shiga, Nobuko Ohba
Summary: With the increasing demand for ideal materials in various applications, computational methods for rapidly and accurately searching for materials have gained growing interest. In this study, a molecular dynamics simulation-based effective fast evaluation technique is demonstrated for an exhaustive search of electrolyte materials with high transport properties.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Physical
Max Crowder, Frozan Tahiry, Isabel Lizarraga, Stephanie Rodriguez, Nathaly Pena, Arun K. Sharma
Summary: In this study, the dynamics of water molecules inside reverse micelles were analyzed using molecular dynamics simulations. The results showed that as the size of the reverse micelles increased, the residence time and diffusion coefficients of water molecules became more similar to those of bulk water. This supports the conclusion that water molecules in reverse micelles adopt a three-layer model of core-intermediate-interface.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Thermodynamics
Ioannis N. Tsimpanogiannis, Othonas A. Moultos
Summary: This study analyzes experimental and molecular simulation data on the intra and self-diffusivities of H-2 and O-2 in H2O, as well as pure H2O, to examine the validity of the Stokes-Einstein relation. The results show that the relation is violated in these systems, indicating the need to improve the accuracy of predicting the slopes s and t for reliable predictions of diffusivities.
FLUID PHASE EQUILIBRIA
(2022)
Article
Chemistry, Physical
Yoshihiko Nishikawa, Atsushi Ikeda, Ludovic Berthier
Summary: We numerically study the equilibrium relaxation dynamics of a two-dimensional Mari-Kurchan glass model. The model displays similar dynamical behavior to conventional glass-formers, despite its simple structural correlations.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Physics, Condensed Matter
Peizhao Li, Haibao Lu, Yong-Qing Fu
Summary: This study proposes a model to describe the relationship between the structure and dynamic diffusion of water, and investigates the thermodynamics of electrolyte aqueous solution. The model reveals the influence of hydrophilic ions on water structure and the changes in topological complexity.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2022)
Article
Chemistry, Physical
Tomaz Urbic, Ken A. Dill
Summary: We have developed an analytical statistical-mechanical model to investigate the dynamic properties of liquid water. The model considers different interactions between neighboring water molecules, such as hydrogen bonds, van der Waals contacts, ice-like cage structures, or no interaction. By calculating the diffusion coefficient, viscosity, and thermal conductivity at different temperatures and pressures, we have observed trends that are consistent with experimental results. Our model reveals that heating leads to faster diffusion but weaker interaction in warm water, resulting in decreased viscosity and conductivity. Cooling cold water, on the other hand, hampers energy exchange due to the large and immobile ice-like cages of water molecules. The significance of this simple analytical model lies in its immediate calculations and interpretations based on molecular physics.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Construction & Building Technology
Annika Lidwina Schultheiss, Ravi A. Patel, Michael Vogel, Frank Dehn
Summary: This study summarizes and compares different modeling approaches for considering cracks and proposes a new method to account for their influence on concrete service life. The research findings demonstrate that the choice of model extension significantly affects prediction results and reveals the limitations of current extensions.
STRUCTURAL CONCRETE
(2023)
Article
Mathematics, Applied
Michael Voit
Summary: This study focuses on the criteria for ensuring positive Gibbs states on distance-regular graphs. The main criterion assumes that the graph can be embedded into a growing family of distance-regular graphs. To prove positivity, polynomial hypergroup theory is used to translate it into an integral representation problem. The criteria are applied to several examples, resulting in a complete description of positive Gibbs states for Hamming graphs and infinite distance-transitive graphs.
INFINITE DIMENSIONAL ANALYSIS QUANTUM PROBABILITY AND RELATED TOPICS
(2023)
Article
Engineering, Electrical & Electronic
Rastislav Ries, Eugen Seiler, Fedor Gomory, Arturs Medvids, Pavels Onufrijevs, Cristian Pira, Eduard Chyhyrynets, Oleg B. Malyshev, Reza Valizadeh, Stewart Leith, Michael Vogel
Summary: In this study, two series of Nb/Cu samples were deposited using the HiPIMS technique with differing Nb deposition conditions, Nb film thickness, and Cu substrate polishing techniques. Nd:YAG laser irradiation was used to smooth the surfaces of all films. The impact of magnetic field enhancement at surface defects on the premature start of magnetic field penetration into the superconducting film was investigated through experiments and numerical calculations. Improved numerical calculations using the Finite Element Method (FEM) were employed to calculate the maximum field enhancement factor beta(m), reflecting the impact of crucial surface defects found in the samples. Magnetization measurements at 4.2K in a DC magnetic field, parallel to the film orientation, were conducted to determine the start of field penetration H-en. SEM and AFM analyses were performed to investigate the Nb surface morphology. Deviations from the H-en (beta(m)) dependence were observed in some samples, and it was found that magnetic field penetration could start from the Nb/Cu interface rather than the free Nb surface due to better surface quality observed by SEM analysis, potentially leading to deterioration of the H-en (beta(m)) dependence.
IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY
(2023)
Article
Chemistry, Physical
Alessandro Triolo, Vitaly V. Chaban, Fabrizio Lo Celso, Francesca Leonelli, Michael Vogel, Elisa Steinrucken, Alessandra Del Giudice, Carlo Ottaviani, James A. Kenar, Olga Russina
Summary: Dialkyl carbonates with short-medium alkyl length, also known as oleochemical carbonates, have attractive properties and a wide range of applications. However, their chemical physical properties and microscopic correlations are not well understood. In this study, we explored the temperature dependence of these properties and the microscopic morphology of DACs. Our findings reveal a distinct degree of mesoscopic spatial segregation and the role of carbonate moieties in driving weak hydrogen bonding interactions and alkyl chain alignment. These findings have implications for the potential applications of DACs in separation, catalysis, and lubrication fields.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Chemistry, Physical
Markus M. Hoffmann, Matthew D. Too, Nathaniel A. Paddock, Robin Horstmann, Sebastian Kloth, Michael Vogel, Gerd Buntkowsky
Summary: In this study, molecular dynamics simulations were performed to investigate polyethylene glycol (PEG)200. Force fields for describing ethylene glycol oligomers were tested and adjusted to improve the agreement with experimental properties. The simulations revealed that PEG200 is a random mixture of its ethylene glycol oligomer components.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Construction & Building Technology
Jan P. Hoeffgen, Michael Vogel, Oliver Blask, Frank Dehn
Summary: Considering limited resource availability and construction demands, efficient recirculation of building materials is crucial. Recycling aggregates as partial replacements for gravel and sand in concrete production, especially due to the restricted availability of the latter, is essential. However, the use of crushed concrete fines as aggregates or supplementary cementitious material (SCM) leads to limited concrete performance due to the concentration of porous hydrated cement in the fine particles. Recent findings suggest that by subjecting them to additional thermal processing, the reactivation of hydrated cement can improve the mechanical and durability properties of the concrete, such as carbonation or chloride penetration, when used as SCM. These promising results have led to a funded research project that investigates the impact of thermal-mechanical processing on the performance of crushed concrete sands with different compositions as SCM.
BETON- UND STAHLBETONBAU
(2023)
Article
Chemistry, Physical
Yael Beilinson, Verena Schiller, Julia Regentin, Jorge H. Melillo, Anna Greenbaum, Tatiana Antropova, Silvina Cerveny, Michael Vogel, Yuri Feldman
Summary: The dynamics of water confined in mesoporous materials were studied using a combination of techniques including broadband dielectric spectroscopy, nuclear magnetic resonance, and differential scanning calorimetry. The results show that water confined in MIP samples exhibits a dynamic crossover at around 180 K, while water confined in MAP samples does not show any changes in relaxation behavior. The crossover temperature is found to depend on the hydration level. Below the crossover temperature, water reorientation is isotropic and the dielectric relaxation strength follows a solid-like behavior, while above the crossover temperature, water reorientation is related to long-range diffusion and the dielectric relaxation strength follows a liquid-like behavior. The results are also consistent with a glass transition near 180 K.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Chemistry, Physical
Sonja C. Do''ller, Martin Brodrecht, Torsten Gutmann, Markus Hoffmann, Gerd Buntkowsky
Summary: Two different mesoporous silica materials (SBA-15 and MCM 41) were impregnated with four commercially available surfactants. Differential scanning calorimetry and solid-state NMR were used to confirm the confinement of the surfactants in the pores and determine their interactions with the pore walls. The study found that hydrophilic surfactants interact with the silica walls in a similar fashion, while for amphiphilic surfactants, the terminal hydroxyl group plays a major role in the interactions.
JOURNAL OF PHYSICAL CHEMISTRY C
(2023)
Article
Chemistry, Physical
Elisa Steinruecken, Max Weigler, Verena Schiller, Michael Vogel
Summary: By confining water to narrow silica pores, the crystallization process is suppressed. The dynamical susceptibilities of the liquid are determined using broadband dielectric spectroscopy (BDS) and 1H and 2H nuclear magnetic resonance (NMR), specifically through NMR field-cycling relaxometry. Derivative analysis reveals Vogel-Fulcher-Tammann and Arrhenius regimes at different temperature ranges, separated by a broad crossover region. The results suggest a crossover to an interface-affected, noncooperative relaxation involving both rotational and translational motions.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Biochemistry & Molecular Biology
Nargiz B. B. Asanbaeva, Sergey A. A. Dobrynin, Denis A. A. Morozov, Nadia Haro-Mares, Torsten Gutmann, Gerd Buntkowsky, Elena G. G. Bagryanskaya
Summary: This paper reports on the DNP efficiency at a high magnetic field for two water-soluble biradicals resistant to reducing media. The radicals were obtained in the form of quaternary ammonium salts to achieve water solubility. The influence of hyperfine interaction and exchange interaction on the DNP effect was determined through EPR spectroscopy.
Article
Chemistry, Physical
Kristina Raupach, Andreas Bogner, Michael Vogel, Engin Kotan, Frank Dehn
Summary: The nanoindentation technique is widely used for mechanical characterization of thin film microstructures. It can accurately determine the hardness and elastic modulus of different materials. While nanoindentation is commonly used in industries like metal, ceramic, and plastics processing, its application in concrete technology is relatively new. This study focuses on using nanoindentation to analyze the mechanical properties of hardened cement paste and investigates the effects of sample preparation and measurement parameters on the results. The findings assess the suitability of nanoindentation for studying durability-related damage in concrete.
Article
Construction & Building Technology
Annika Lidwina Schultheiss, Ravi A. Patel, Michael Vogel, Frank Dehn
Summary: This study summarizes and compares various modeling approaches to evaluate the probabilistic service life prediction. The research findings demonstrate that the choice of model extension for cracks significantly influences the prediction results and shows the limitations of current extensions.
STRUCTURAL CONCRETE
(2023)