Review
Chemistry, Multidisciplinary
Aris Chatzichristos, Jamal Hassan
Summary: Confined water inside carbon nanotubes has unique properties and wide applications. This review provides an overview of the properties of water in carbon nanotubes, based on nuclear magnetic resonance and molecular dynamics studies. It explains contradictory results in the literature and identifies debatable issues, open problems, and future research directions.
Article
Chemistry, Multidisciplinary
A. Badon, J. -B Marceau, C. Allard, F. Fossard, A. Loiseau, L. Cognet, E. Flahaut, G. Recher, N. Izard, R. Martel, E. Gaufres
Summary: By confining alpha-sexithiophene (6T) molecules in boron nitride nanotubes (6T@BNNTs), fluorescence anisotropy can be induced in a transparent host. The experiments show that individual 6T@BNNTs exhibit high polarization extinction ratio at room temperature, and the fluorescence anisotropy is consistent with the alignment of encapsulated 6T molecules along the nanotube axis. By stretching a flexible transparent polymer film mixed with 6T@BNNTs, macroscopic fluorescence anisotropy can be induced within the film. This work demonstrates the use of dyes@BNNT system as a convenient platform to induce fluorescence anisotropy in photonic materials.
MATERIALS HORIZONS
(2023)
Article
Materials Science, Multidisciplinary
Eric Faulques, Nataliya Kalashnyk, Charlotte A. Slade, Ana M. Sanchez, Jeremy Sloan, Victor G. Ivanov
Summary: In this study, the vibrational and electronic properties of tin selenide nanowires encapsulated in single walled carbon nanotubes were investigated using experimental Raman spectroscopy and density functional theory calculations. The results show that the different structures of the nanowires exhibit distinct Raman spectra features and electronic properties, which is consistent with the theoretical predictions. The interaction between the nanotubes and the encapsulated nanowires was observed.
Article
Chemistry, Multidisciplinary
Jinfeng Chen, Zongyang Qiu, Jing Huang
Summary: This study investigates the structure and dynamics of diphenylalanine peptide nanotubes and confined water molecules using molecular dynamics and Monte Carlo simulations. It was found that a small number of confined water molecules stabilize the nanotubes, and the kinetics of these water molecules exhibit different transport behaviors.
Article
Chemistry, Multidisciplinary
Weili Cui, Lei Shi, Kecheng Cao, Ute Kaiser, Takeshi Saito, Paola Ayala, Thomas Pichler
Summary: Carbyne is a one-dimensional allotrope of carbon, which is stable when grown encapsulated in carbon nanotubes. By using isotopic labeling as a tuning mechanism, researchers were able to control its properties and achieve pioneering results with around 11.9% of C-13 labeling.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Amit Srivastava, Jamal Hassan, Dirar Homouz
Summary: Water dynamics in nanochannels, especially in small carbon nanotubes, are influenced by confinement. Molecular dynamics simulations were performed to investigate the structure and dynamics of water in carbon nanotubes of various sizes and temperatures. The results showed that the radial density profile of water in small nanotubes had a single peak near the tube walls, while larger nanotubes exhibited coaxial tubular sheets of water molecules. Subdiffusive behavior was observed in ultra-narrow nanotubes, while Fickian diffusion was evident in larger nanotubes. The hydrogen bond correlation function of water in the nanotubes decayed slower than in bulk water, with the decay rate decreasing as the nanotube diameter increased.
Article
Chemistry, Multidisciplinary
Mohsen Abbaspour, Hamed Akbarzadeh, Sirous Salemi, Leila Bahmanipour
Summary: The application of electric and magnetic fields on water molecules confined in carbon nanotubes has significant implications for cell biology and nanotechnology. Through molecular dynamics simulations, it was found that confined water molecules undergo phase transitions from pentagonal to twisted pentagonal, spiral, and circular shapes with increasing electric field intensity. The highest magnetic field can induce a more ordered pentagonal shape, while ring-like shapes formed in the presence of an electric field exhibit more hydrogen bonds compared to other structures. The phase transitions of confined water molecules were confirmed through radial distribution function (RDF) and angle distribution function (ADF) analyses.
Article
Chemistry, Physical
Lei Shi, Ryosuke Senga, Kazu Suenaga, Johnny Chimborazo, Paola Ayala, Thomas Pichler
Summary: The recent achievement of confining carbyne in double-walled carbon nanotubes represents a major breakthrough in materials science, but controlling its properties remains a challenge. Researchers have successfully fabricated confined carbyne with tailored properties through localized photothermal heating and in-situ Raman spectroscopy. The evident interaction between the nanotubes and confined carbyne alters the tube's diameter, indicating a potential mechanism for tailoring the properties of the confined carbyne.
Article
Chemistry, Medicinal
Leonard Dick, Barbara Kirchner
Summary: In this paper, a Python code called CONAN is presented to study the interaction between liquids and solid structures. The program allows for generating different structures and analyzing the structural properties of liquids. The abilities of the tool are demonstrated by studying an ionic liquid in carbon nanotubes of different sizes.
JOURNAL OF CHEMICAL INFORMATION AND MODELING
(2023)
Article
Chemistry, Multidisciplinary
Bingliang Zhou, Xiujuan Liu, Fernando Luis P. Resende, Jianbin Zhou, Mei Wang, Anthony B. Dichiara
Summary: The potential of catalytic hydropyrolysis for producing value-added chemicals from residual biomass generated during seasonal pruning of tea plants has been evaluated. Nickel nanoparticles encapsulated in carbon nanotubes were found to be effective microreactors, with a high selectivity for long-chain alkanes and aromatic hydrocarbons, making them comparable to commercial fuels.
ACS SUSTAINABLE CHEMISTRY & ENGINEERING
(2021)
Article
Chemistry, Physical
Umedjon Khalilov, Erik C. Neyts
Summary: The study examines the confinement effects inside a carbon nanotube and the competition mechanism between catalyst and feedstock in nanostructure synthesis, focusing on the growth mechanism and structure morphology of encapsulated carbon nanostructures. It is found that the encapsulated nanostructures contain metal atoms and are less stable than their pure counterparts, leading to a study on the purification mechanism of these structures. Overall, this research provides a possible pathway for the controllable synthesis of tubular and planar carbon nanostructures for today's nanotechnology.
Article
Chemistry, Multidisciplinary
Shakul Pathak, Monojit Chakraborty, Sunando DasGupta
Summary: This study explores the physics of droplet movement under the influence of an electric field at the molecular level. Molecular simulations demonstrate that the spreading dynamics of the droplet are qualitatively similar to experimental observations. By analyzing the dynamics of droplet actuation across an electrode array, the contact line friction and its relationship with droplet velocity are determined through scaling analysis.
Article
Chemistry, Multidisciplinary
Lei Shi, Ryosuke Senga, Kazu Suenaga, Hiromichi Kataura, Takeshi Saito, Alejandro Perez Paz, Angel Rubio, Paola Ayala, Thomas Pichler
Summary: By controlling the diameter of single-walled carbon nanotubes, it is possible to grow confined carbyne with a defined and tunable band gap. The metallicity of the tubes has minimal influence on the formation of carbyne, while the diameter plays a major role in the growth process. The properties of confined carbyne can be independently tailored, primarily determined by its interaction with the carbon nanotube.
Article
Engineering, Multidisciplinary
G. K. Ramesh, J. K. Madhukesh, Nehad Ali Shah, Se-Jin Yook
Summary: Thermal radiation and thermophoretic particle deposition have important applications in research and engineering. This study investigates the movement of hybrid carbon nanotubes (CNTs) around a rotating sphere with the presence of thermal radiation and thermophoretic particle deposition. Nonlinear governing equations are converted into ordinary differential equations using similarity factors. Numerical results and graphical presentations are obtained using the Runge Kutta Fehlberg 45 order and a shooting approach. The study explores the impact of different limitations on the characteristics of the CNTs.
ALEXANDRIA ENGINEERING JOURNAL
(2023)
Article
Biochemistry & Molecular Biology
Michael Fardis, Marina Karagianni, Lydia Gkoura, George Papavassiliou
Summary: Confined liquids, especially bulk water, serve as model systems for studying the metastable supercooled state. However, the onset of crystallization below 230 K makes it difficult to apply experimental techniques. Confined water exhibits drastically different properties at the nanoscale due to the nature of the confining environment and the interactions with the confining matrix. This study demonstrates that the translational mobility of water molecules, particularly in the supercooled state, can distinguish between hydrophilic and hydrophobic environments. Nuclear magnetic resonance and quasi-elastic neutron scattering are effective experimental methods for assessing water dynamics.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Thermodynamics
Jiun Cai Ong, Yan Zhang, Shijie Xu, Jens Honore Walther, Xue-Song Bai, Kar Mun Pang
Summary: The present study uses large-eddy simulations (LES) to investigate the ignition and stabilization mechanisms of ECN Spray A flame under different injection pressures and ambient temperatures. The numerical model is validated against experimental data and the role of auto-ignition in flame stabilization is found to be crucial.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Chemistry, Applied
Sima Majidi, Hamid Erfan-Niya, Jafar Azamat, Soroush Ziaei, Eduardo R. Cruz-Chu, Jens Honore Walther
Summary: The global demand for clean and potable water is increasing due to population growth and pollution. Water contamination is a global problem that needs to be investigated for proper strategies to improve water quality and reduce water scarcity. Membrane technologies for water purification show promising results. This review discusses the use of molecular dynamics (MD) simulations to evaluate the performance of membrane-based water purification systems. The article also provides insights into recent developments and limitations of MD simulations in wastewater treatment using membranes.
SEPARATION AND PURIFICATION REVIEWS
(2023)
Article
Chemistry, Physical
Elton Oyarzua, Jens H. H. Walther, Harvey A. A. Zambrano
Summary: The study introduces a graphene-based thermal nanopump that can produce controlled and continuous liquid flow in nanoslit channels by utilizing thermal gradients. Large-scale molecular dynamics simulations were conducted to investigate the performance of this thermal nanopump. The results show that water flow rates increase due to larger ripple fluctuations on the graphene layers as higher thermal gradients are applied, and the efficiency of the pump can be enhanced by modifying the wettability of the channel walls.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Biophysics
Lucas Amoudruz, Athena Economides, Georgios Arampatzis, Petros Koumoutsakos
Summary: In this study, a data-driven approach is employed to quantify the stress-free state shape and visco-elastic properties of red blood cells (RBCs) for the first time. A transferable RBC model is introduced based on these quantifications, and its effectiveness is demonstrated through accurate predictions of blood flows under unseen experimental conditions.
BIOPHYSICAL JOURNAL
(2023)
Article
Energy & Fuels
Ji Zhang, Zhi Cao, Sheng Huang, Xiaohui Huang, Yu Han, Chuang Wen, Jens Honore Walther, Yan Yang
Summary: In this study, a novel combination of branch-structured fins and Al2O3 nanoparticles was proposed to enhance the performance of a phase change material (PCM) in a triple-tube heat exchanger. A mathematical model was developed and validated based on experimental results, considering thermal conduction, Brownian motion of nanoparticles, and natural convection in the liquid PCM. The results showed that both nanoparticles and metal fins significantly improved the solidification behavior, with metal fins having a greater impact compared to nanoparticles.
Article
Engineering, Multidisciplinary
Ivica Kicic, Pantelis R. Vlachas, Georgios Arampatzis, Michail Chatzimanolakis, Leonidas Guibas, Petros Koumoutsakos
Summary: Predictive simulations are crucial for various applications, but their accuracy relies on capturing effective system dynamics. Massively parallel simulations are expensive, while reduced order models have limitations. AdaLED is a novel framework that combines large-scale simulations and reduced order models to extract and forecast effective dynamics of multiscale systems. It employs autoencoders and probabilistic recurrent neural networks for fast and adaptable learning, achieving net speed-ups and detecting unseen dynamics regimes. AdaLED is a powerful tool for computationally expensive simulations.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Chemistry, Physical
Petr Karnakov, Sergey Litvinov, Petros Koumoutsakos
Summary: We introduce a potent computational method for solving inverse problems in fluid mechanics, which accelerates the convergence of gradient-based optimization methods for problems with parameters on a grid. By incorporating a multigrid decomposition technique, we achieve significant improvement in both computational efficiency and the avoidance of local minima. Our results demonstrate that this method, called mODIL, outperforms the popular Physics-Informed Neural Networks (PINNs) method in terms of computational cost, with three to five orders of magnitude lower cost in benchmark problems.
EUROPEAN PHYSICAL JOURNAL E
(2023)
Article
Energy & Fuels
Min Zhang, Jiun Cai Ong, Kar Mun Pang, Shijie Xu, Yan Zhang, Arash Nemati, Xue-Song Bai, Jens Honore Walther
Summary: The present study uses large eddy simulation to investigate combustion recession for the Engine Combustion Network Spray A flame under different ambient temperatures and injection pressures. The numerical results accurately capture the different combustion recession phenomena. The combustion recession is mainly controlled by the auto-ignition process at a higher ambient temperature, while at a lower ambient temperature, the local temperature within the fuel-rich region is not high enough to promote high-temperature ignition.
Article
Energy & Fuels
Arash Nemati, Jiun Cai Ong, Min Zhang, Jens Honore Walther
Summary: The auto-ignition process of micro-pilot diesel in premixed dual-fuel combustion was studied using large eddy simulation. It was found that the inhomogeneity in temperature has a more significant influence on the ignition delay time (IDT) than methane inhomogeneity. The inhomogeneity pockets of temperature advance the first-stage and second-stage ignition. This study is important for improving engine performance and reducing exhaust emissions.
Article
Mathematics, Applied
Abhinav Singh, Alejandra Foggia, Pietro Incardona, Ivo F. F. Sbalzarini
Summary: We present a meshfree collocation scheme, called Surface DC-PSE, to discretize intrinsic surface differential operators over scalar fields on smooth curved surfaces with given normal vectors and a non-intersecting tubular neighborhood. We benchmark Surface DC-PSE by discretizing the Laplace-Beltrami operator on a circle and a sphere, and we present convergence results for both explicit and implicit solvers. Finally, we compare Surface DC-PSE with surface finite elements (SFEM) and diffuse-interface finite elements (DI FEM) in a validation case.
JOURNAL OF SCIENTIFIC COMPUTING
(2023)
Article
Mechanics
Diego Becerra, Andres Cordoba, Jens H. Walther, Harvey A. Zambrano
Summary: Through atomic-level simulations, it is found that graphene coating significantly enhances water flow in nanochannels compared to hexagonal boron nitride (hBN) coating. The natural undulations of graphene coating further enhance water flow.
Article
Multidisciplinary Sciences
Suryanarayana Maddu, Dominik Sturm, Bevan L. Cheeseman, Christian L. Mueller, Ivo F. Sbalzarini
Summary: STENCIL-NET is an artificial neural network architecture that can forecast spatiotemporal dynamics from data without needing to know a governing equation. It learns a discrete propagator to reproduce the data and can therefore generalize well to different dynamics and grid resolutions.
SCIENTIFIC REPORTS
(2023)
Article
Physics, Multidisciplinary
Abhinav Singh, Quentin Vagne, Frank Juelicher, Ivo F. Sbalzarini
Summary: Active polar fluids exhibit spontaneous flow when sufficient stress is generated. In three-dimensional active matter, in-plane and out-of-plane instabilities have been observed. However, a theoretical model that explains all observations is still missing, and the role of boundary conditions in these instabilities needs to be explained.
PHYSICAL REVIEW RESEARCH
(2023)
Article
Computer Science, Hardware & Architecture
Johannes Pahlke, Ivo F. Sbalzarini
Summary: Particle methods are widely used algorithms for computer simulation in various fields. However, the relationship between these algorithms and a formal definition of particle methods has been lacking. In this study, a rigorous mathematical definition of particle methods is presented and its importance is demonstrated through various applications and theorems. It is anticipated that this formal definition will facilitate solving complex computational problems and the development of maintainable software frameworks for computer simulation.
IEEE OPEN JOURNAL OF THE COMPUTER SOCIETY
(2023)
Article
Engineering, Ocean
Nicolai Arent Quist, Rasmus Haurum Christensen, Henrik Mikkelsen, Jens Honore Walther
Summary: This study verifies and validates a full-scale self-propulsion CFD model that incorporates hull roughness and welding seams. The results show the importance of measuring hull roughness for accurate performance calculations and the increase in resistance caused by welding seam modeling.
APPLIED OCEAN RESEARCH
(2023)
