Article
Chemistry, Physical
Archit Dani, Mohsen Yeganeh, Charles Maldarelli
Summary: The cluster formation and self-assembly of floating colloids at a fluid/fluid interface involve a delicate force balance among lateral interaction forces, viscous resistance, and thermal fluctuations. The study shows that as the colloid dimensions decrease, thermal forces become important and affect the self-assembly into ordered patterns and crystal structures. Numerical simulations are used to describe the assembly of particles at a liquid-liquid interface, considering capillary attraction, electrostatic repulsion, thermal fluctuations, and hydrodynamic interactions. The results suggest that cluster formation, fractal growth, and particle ordering are more likely to occur at larger values of the Pe numbers.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Physics, Multidisciplinary
Orest Hryhorchak, Andrij Rovenchak
Summary: We have analyzed the higher multipole moments in the expansion of the electrostatic potential generated by various distributions of charges over Platonic solids. The lowest non-zero multipole moment for the tetrahedron is the octupole, while for the octahedron and cube it is the hexadecapole. For the icosahedron and dodecahedron, non-zero elements appear first in the 2(6)-pole moment tensors.
Article
Chemistry, Physical
Carmine Anzivino, Giuseppe Soligno, Rene van Roij, Marjolein Dijkstra
Summary: This theoretical study investigates whether capillary interactions can lead to the spontaneous chain formation of cubic particles at a fluid-fluid interface, by calculating adsorption energies, equilibrium particle orientations, and interfacial deformations. The researchers constructed ground-state and temperature-density or size-density phase diagrams, identifying several regimes with stable chainlike structures in line with experimental observations.
Article
Chemistry, Multidisciplinary
Samuel Trevenen, Md Anisur Rahman, Heather S. C. Hamilton, Alexander E. Ribbe, Laura C. Bradley, Peter J. Beltramo
Summary: Control over the interparticle interaction energy is necessary to create long-range ordered structures with complex configurations via interfacially trapped anisotropic particles. Colloidal ellipsoids with nanoscale porosity exhibit a reduced interparticle capillary attraction at a water-air interface compared to their smooth counterparts. The behavior of porous ellipsoids at the interface, including the shorter-range capillary interaction potential and the absence of quadrupolar symmetry, can be used to engineer the self-assembly of complex two-dimensional microstructures.
Article
Chemistry, Physical
Jun-Sik Sin
Summary: Theoretical investigation using Poisson-Boltzmann approach shows that ion partitioning enhances electrostatic interaction between two charged surfaces and increases osmotic pressure. The ion partitioning effect is amplified not only by an increase in the thickness of the polyelectrolyte layer or Debye length, but also by a decrease in ion radius.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2021)
Article
Chemistry, Multidisciplinary
Masaaki Akamatsu, Ayumi Kimura, Koji Yamanaga, Kenichi Sakai, Hideki Sakai
Summary: The study evaluated anion-pi interactions at the solid/water interface and found that anion adsorption followed the hydration energy and the presence of conjugated systems of the anions by QCM measurements. Force curve measurements revealed that the single-molecule force of anion-pi interaction was approximately 40 pN between an NDI unit and the negatively charged surface of the cantilever. This study presented the first example of obtaining a single-molecule force for anion-pi interactions.
CHEMICAL COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Joao Paulo Vita Damasceno, Lauro Tatsuo Kubota
Summary: This study proposes the possibility of generating surface charges and negative zeta potential on an aqueous graphite dispersion through a redox mechanism. After contact with concentrated ammonia aqueous solution, washing, and exfoliation, a lyophobic dispersion was obtained. Kelvin probe force microscopy indicates that ammonia treatment and exfoliation raise the Fermi level of graphite, suggesting the promotion of redox reactions between ammonia and graphite.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Hanna Anop, Johan Buitenhuis
Summary: This study presents an explorative investigation on a novel polyelectrolyte complex formed by chemically modified filamentous fd viruses. The complex formation behavior is analyzed with respect to the concentration of the viruses and salt, and the scattering intensity is shown to significantly increase in certain samples.
Article
Multidisciplinary Sciences
Jaemin Min, Ha Young Jung, Seungwon Jeong, Byeongdu Lee, Chang Yun Son, Moon Jeong Park
Summary: This study developed a method to enhance the ionic conductivity of charged block copolymers by electrostatic control of interfacial layers, leading to unprecedented reentrant phase transitions and the formation of thin ionic shell layers. The stabilization energies of the A15 structures were found to be greater when enriched, attractive electrostatic interactions were present at the micellar interfaces, challenging the conventional belief that block copolymer interfaces significantly deteriorate ion transport. This research establishes a promising avenue for advanced polymer electrolytes with tailor-made interfaces.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Chemistry, Physical
Hiroyuki Ohshima
Summary: Asymptotic expressions for electrostatic interaction energy between two weakly charged spheroidal particles in an electrolyte solution were derived based on linear superposition approximation. The interaction was found to be screened Coulomb interaction between hypothetical point particles with orientation-dependent charges, and explicit interaction energy equations were given for four configurations of similar spheroids. Comparison was also made with results from Derjaguin's approximation.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2021)
Article
Environmental Sciences
Bingcheng Liu, Chuling Guo, Changdong Ke, Kai Chen, Zhi Dang
Summary: This study investigated the colloidal stability of CdS colloids in different aqueous systems, exploring the effects of electrolyte concentration and solution pH. It was found that increased electrolyte concentration destabilized CdS colloids, while higher solution pH stabilized them. Electron microscopy and spectroscopy confirmed the strong interaction between macromolecules and CdS colloids, forming a protective layer called NOM corona. The interaction between macromolecules and CdS influenced the aggregation behavior in different solutions. The findings enhance our understanding of the fate and transport of CdS colloids in the environment, providing insights into their potential risks.
SCIENCE OF THE TOTAL ENVIRONMENT
(2023)
Article
Chemistry, Applied
Alejandra Romero-Moran, Anai L. Zavala-Franco, Jose L. Sanchez-Salas, Miguel Angel Mendez-Rojas, Joel Joel Molina-Reyes
Summary: In this work, a method for fabricating rutile-TiO2 films with different submicron thicknesses on SiO2 was proposed. The correlation between the generation of a positively charged TiO2 surface and E. coli attraction was investigated. Results showed that the formation of a positively charged TiO2 surface enhanced the photocatalytic antibacterial activity, facilitating the adsorption and degradation of negatively charged substances and pathogenic microorganisms.
Article
Chemistry, Multidisciplinary
Zhixin Li, Xiaoli Huang, Hongning Liu, Fang Luo, Bin Qiu, Zhenyu Lin, Huixing Chen
Summary: A novel electrochemiluminescence (ECL) biosensor for the detection of hyaluronidase has been developed based on adjustable electrostatic interactions. It utilizes negatively charged nanoparticles that exhibit strong electrostatic repulsion with a negatively charged electrode, resulting in low-intensity ECL signal. In the presence of hyaluronidase, the nanoparticles undergo a decomposition process, leading to the generation of positively charged nanoparticles with enhanced ECL signal through electrostatic attraction. The biosensor shows a linear relationship between ECL and hyaluronidase concentration, with a detection limit of 0.37 U/mL.
Article
Biochemistry & Molecular Biology
Majedul Islam, Emily Argueta, Ewa P. Wojcikiewicz, Deguo Du
Summary: The aggregation of a novel model peptide tau(298-317), derived from the microtubule-associated protein tau, was investigated. The peptide mimics the physical and aggregation properties of tau and is promoted to form amyloid fibrils by the presence of polyanionic heparin. Positively charged polysaccharides can effectively inhibit heparin-induced aggregation of tau(298-317).
ACS CHEMICAL NEUROSCIENCE
(2022)
Article
Biochemistry & Molecular Biology
Majedul Islam, Emily Argueta, Ewa P. Wojcikiewicz, Deguo Du
Summary: Tau aggregation is a key characteristic in many neurological disorders. In this study, a model peptide tau298-317 was found to mimic the aggregation properties of tau, and the aggregation was promoted by polyanionic heparin. However, the aggregation could be effectively inhibited by positively charged polysaccharides, chitosan and its derivative, N-trimethyl chitosan. This study suggests that targeting tau-Hep interactions with positively charged polyelectrolytes could prevent tau aggregation.
ACS CHEMICAL NEUROSCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Berthold Reisz, Eelco Empting, Matthias Zwadlo, Martin Hodas, Giuliano Duva, Valentina Belova, Clemens Zeiser, Jan Hagenlocher, Santanu Maiti, Alexander Hinderhofer, Alexander Gerlach, Martin Oettel, Frank Schreiber
Summary: Blended organic thin films, including pure and mixed films of CuPc and C60, were studied for their growth processes and morphologies. Experimental results showed the formation of a smooth wetting layer followed by rapid roughening in pure CuPc films, while C60 exhibited fast formation of distinct islands at an early growth stage.
PHYSICAL REVIEW MATERIALS
(2021)
Article
Chemistry, Physical
Amin Bakhshandeh, Derek Frydel, Yan Levin
Summary: In this study, a reactive Monte Carlo simulation method and the primitive model of electrolyte were used to investigate the acid-base equilibrium that controls charge regulation in colloidal systems. The simulations were performed in a semi-grand canonical ensemble, where the colloidal suspension was in contact with a reservoir of salt and strong acid. The interior of colloidal particles was modeled as a low dielectric medium. The effective colloidal charge was calculated for different numbers of surface acidic groups, pH, salt concentrations, and types of electrolyte. Good agreement was found between the titration curves obtained from simulations and experimental measurements in the case of potassium chloride. For lithium chloride, the specific ionic adsorption was taken into account through the partial dehydration of the lithium ions.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Saswati Ganguly, Gaurav Prakash Shrivastav, Shang-Chun Lin, Johannes Haering, Rudolf Haussmann, Gerhard Kahl, Martin Oettel, Matthias Fuchs
Summary: Different types of defects play a significant role in the mechanical response of complex crystals close to melting or at finite temperatures. Conventional elasticity theory fails to explain the motion of point defects in ordered crystalline structures. In this study, a first principles theoretical framework derived from microscopic equations of motion is used to investigate the elastic properties of a crystal with a high concentration of point defects. Predictions about the mechanical properties are validated through deformation experiments in molecular dynamics simulations.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Mechanics
Derek Frydel
Summary: This paper investigates the four-state run-and-tumble particle model at zero temperature and proposes an enhanced model by increasing the number of discrete velocities. The analysis reveals that fast particles tend to accumulate at the walls while slow particles deplete gradually.
Review
Chemistry, Physical
Alvaro Dominguez, Mihail N. Popescu
Summary: Phoresis, a classic example of particle transport driven by thermodynamic gradients, is enjoying renewed research interest due to its relevance to the motility of chemically active particles and technological advancements. This review focuses on the general framework of phoresis and self-phoresis, using chemophoresis as a case study, and discusses the simplest extension of the theory to account for correlations in the fluid. It is found that self-phoresis can no longer be represented as phoresis in a self-generated composition gradient, shifting the paradigm from the ideal case.
CURRENT OPINION IN COLLOID & INTERFACE SCIENCE
(2022)
Article
Chemistry, Physical
Alexander Hinderhofer, Jan Hagenlocher, Alexander Gerlach, Joachim Krug, Martin Oettel, Frank Schreiber
Summary: Understanding the growth behavior of binary mixtures and its connection to the bulk phase behavior is a major challenge. In this study, we used X-ray reflectivity to determine the surface roughness and found systematic behavior depending on the intermixing, co-crystallization, or phase separation in the mixed films. Kinetic Monte Carlo simulations provided evidence that the lowered step edge barrier in the mixed films is induced by reduced in-plane crystallinity.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Physical
Christian Beck, Marco Grimaldo, Hender Lopez, Stefano Da Vela, Benedikt Sohmen, Fajun Zhang, Martin Oettel, Jean-Louis Barrat, Felix Roosen-Runge, Frank Schreiber, Tilo Seydel
Summary: This study investigates the dependence of diffusion dynamics of macromolecules in biological systems on volume fraction using a simplified model system. The results suggest that a simple colloid picture accurately describes the short-time diffusion in binary mixtures.
JOURNAL OF PHYSICAL CHEMISTRY B
(2022)
Article
Chemistry, Physical
Frank Hirschmann, Hender Lopez, Felix Roosen-Runge, Tilo Seydel, Frank Schreiber, Martin Oettel
Summary: The researchers developed a coarse-grained, structure-based, low-resolution, 6-bead model for bovine serum albumin (BSA) and compared it with a 12-bead model for immunoglobulin G (IgG). They studied the effects of packing and flexibility on the behavior of these models in denser solutions. They also determined the effective sphere sizes of BSA.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Sahana Kale, Achim Lederer, Martin Oettel, Hans Joachim Schoepe
Summary: PMMA-PHSA particles have been used as a hard sphere model system since the 1980s. We investigate the fluid structure of fluorescent particles in three different solvents and compare them with analytical theory and computer simulations. The results show hard sphere behavior in decalin-TCE and charged sphere behavior in decalin-CHB and decalin-CHB-TBAB solvents, with reduced screening in the latter system compared to the bulk solvent.
Article
Physics, Fluids & Plasmas
Derek Frydel
Summary: In this work, we derived a third-order linear differential equation for the stationary distributions of run-and-tumble particles in a two-dimensional harmonic trap. This equation represents the condition for flux, j, to be zero. Unlike the analogous equation for passive Brownian particles, the active motion exhibits second- and third-order terms. The solution can be expressed as a convolution of two distributions: a Gaussian distribution representing the Boltzmann distribution of passive particles and a beta distribution representing active motion at zero temperature.
Correction
Physics, Fluids & Plasmas
E. Empting, M. Klopotek, A. Hinderhofer, F. Schreiber, M. Oettel
Article
Physics, Fluids & Plasmas
E. Empting, N. Bader, M. Oettel
Summary: This study investigates the roughness and orientational order in thin films of anisotropic particles through kinetic Monte Carlo simulations. The results show that increasing anisotropy leads to a preferred orientation in the film, accompanied by non-equilibrium roughening effect and reordering in the film.
Article
Physics, Fluids & Plasmas
Derek Frydel
Summary: This work investigates the entropy production rate, Pi, of the run-and-tumble model and focuses on its scaling with the persistence time tau. It is found that, in the limit of tau approaching infinity, Pi tends to zero, indicating equilibrium; while in the limit of tau approaching zero, Pi reaches its optimal value, indicating a departure from equilibrium.
Article
Physics, Fluids & Plasmas
M. Maeritz, M. Oettel
Summary: A density functional based on fundamental measure theory is employed to study droplet states of lattice gas with next-neighbor attractions in three-dimensional finite systems. The findings show a sequence of droplets transitioning to cylinders and planar slabs, along with additional effects observed in the chemical potential curve upon temperature decrease. The analysis of the surface tension behavior reveals a dominant 1/Rs2 contribution with a hint of weak logarithmic contribution, which is smaller than the universal value predicted by field-theoretic methods.
Article
Physics, Fluids & Plasmas
Derek Frydel
Summary: This article explores the viewpoint of propelled particles being regarded as a system with quenched disorder in a steady state. The analogy is exact when the rate of the drift orientation vanishes and the linear potential becomes part of an external potential. The stationary distribution is then calculated by considering all contributing drift orientations, making it a disorder-averaged quantity.
