Polarization Effects Research Articles

Effect of surface polarity on the structure and dynamics of liquids at the alumina solid–liquid interface

Effect of surface polarity on the structure and dynamics of liquids at the alumina solid–liquid interface

Charging of particles with ion irradiation in an electrodynamic dust shield

The deposition of dust on the surfaces of solar panels and optical instruments is a critical issue that leads to malfunctions and performance degradation of equipment. An electrodynamic dust shield (EDS) is a unique particle removal method that utilizes an electrostatic force for cleaning particles. In this study, an ionizer is introduced into an EDS to induce particle charging and improve the removal rate of the deposited particles. EDS cleaning experiments are conducted under various ion irradiation conditions. The effects of ion polarity, particle size, irradiation protocol, distance, and relative humidity on the dust removal performance of the EDS are investigated through various experiments. In both cases of pre-irradiation (when the particles are irradiated with ions before EDS activation) and simultaneous irradiation (when the particles are irradiated during the EDS operation), the removal rates improve, and the simultaneous irradiation also enhances the cleaning speed.

Study on the Influence of External Electric Field Control and Vibrational Quantum Effect on the Charge Separation Mechanism in Fullerene-Based Systems.

Based on the DCV-C60 system of fullerene acceptor organic solar cell active materials, the charge transfer process of D-A type molecular materials under the action of an external electric field (Fext) was explored. Within the range of electric field application, the excited state characteristics exhibit certain regular changes. Based on reducing the excitation energy, the excitation mode shows a trend of developing toward low excited states. The effect of solvent polarity on the stability and reorganization energy of the charge transfer state was investigated. The dependence of charge separation parameters on specific molecular structures within the electric field range was studied, proving that the electric field set along the electron transfer direction can indeed accelerate charge separation. The influence of vibrational modes on the charge separation process was studied, and the results showed that the vibrational quantum tunneling effect significantly promoted the charge separation. Therefore, considering the vibrational excitation effect and the perturbation of the nuclear-electron interaction is crucial for more accurate simulation of the electron-vibration coupling process in the excited state.

Metallofullerenol Gd@C82(OH)22 preserves human erythrocyte plasma membrane integrity from AAPH-induced oxidative stress: molecular mechanisms and antioxidant activity.

Metallofullerenols and fullerenols have attracted attention due to their remarkable ability to interact with various biologically relevant molecules, paving the way for biomedical applications, ranging from medical imaging techniques to drug carriers, acting with increased efficiency and reduced side effects. In this work, we investigated the effects of two fullerene derivatives, Gd@C82(OH)22 and C70(OH)12, on erythrocyte membrane components under oxidative stress conditions induced by 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) as a source of peroxyl radicals. The results demonstrated that gadolinium encapsulation within the fullerene cage enhanced the electron affinity of Gd@C82(OH)22, resulting in stronger antioxidant activity. Gd@C82(OH)22 formed a protective hydrophilic layer at the lipid-water interface, effectively preventing lipid peroxidation, oxidative protein damage, and potassium leakage, outperforming C70(OH)12. Both compounds improved membrane fluidity, but Gd@C82(OH)22 exhibited superior preservation of the erythrocyte lipid bilayer and protein function. Additionally, Gd@C82(OH)22 maintained the anion exchange function of Band 3 protein, which is critical for ionic homeostasis, by preventing oxidation-induced aggregation and preserving thiol groups. Despite its limited membrane penetration, Gd@C82(OH)22 stabilized membrane components through hydrogen bonding, which indirectly enhanced membrane stiffness and fluidity under oxidative stress. This external protection of membrane integrity reduced the risk of lipid peroxidation and oxidative damage to erythrocyte proteins. In contrast, C70(OH)12, while effective in protecting membrane lipids, was less effective in preserving protein structure. These findings highlight the unique protective properties of Gd@C82(OH)22, attributed to polarization effects induced by the encapsulated Gd atom. This study indicates that metallofullerenols, such as Gd@C82(OH)22, may have therapeutic potential in mitigating oxidative damage.

Atmospheric air plasma pre-activation and customizable covalent functionalization of PVDF-membranes of microtiter filter plates

Microtiter-plate-based systems are unified platforms of high-throughput experimentation (HTE). These polymeric devices are used worldwide on a daily basis—mainly in the pharmaceutical industry—for parallel syntheses, reaction optimization, various preclinical studies and high-throughput screening methods. Accordingly, laboratory automation today aims to handle these commercially available multiwell plates, making developments focused on their modifications a priority area of modern applied research. We performed the covalent functionalization of the porous PVDF-membrane of microtiter filter plates as the essence of conventional and common sandwich plate systems by introducing a generalizable method. After surface-activation of the indifferent membrane polymer, customizable functionalization becomes feasible by covalently attached monofunctional molecular linkers. The study was designed with future adaptability, and thus, industrially widespread atmospheric plasma and two different chemical treatments were investigated and compared in terms of practical implementation, polarization effects, extent of labeling, effects on morphology and porosity as well as on permeability. For critical comparison, contact angle measurements, surface ATR-FTIR, 1H-NMR, 19F-NMR, UV–Vis spectroscopy, scanning electron microscopy and permeability tests were used.

Effective dipole model for electrostatic interactions between polarizable spherical particles in particle scale simulations

Despite their widespread adoption, particle-scale simulation methods, such as the Discrete Element Method (DEM), for electrically charged particles in several natural processes and industrial transformations do not include realistic polarization effects. At close distances, these can dominate the particle motion and are impossible to predict by the commonly adopted Coulomb point-charge approximation. Sophisticated mathematical tools can account for uneven charge distributions, predicting an attractive force between a charged particle and a neutral particle or possible attraction between two like-charged particles. Such approaches are accurate but too complex for implementation in DEM simulations of many interacting particles. We propose a novel, simpler yet realistically accurate effective dipole model. By attributing a net charge and an induced effective dipole to each sphere, the interaction force between charged polarizable particles is computed in closed form. A comparison of a rigorous solution and the proposed dipole approach for two spherical particles reveals significant improvement over the commonly employed Coulomb law. The effects of particle size ratio and charge ratio on the interaction force are discussed. Then, the dynamic DEM simulation of a shaker filled with a binary mixture of differently sized particles that are all positively charged is shown to predict the counterintuitive formation of fine-on-coarse aggregates.

Equivalent-circuit modeling of electron-hole recombination in semiconductors and mixed ionic-electronic conductors

The analysis and optimization of solar energy conversion and light-emitting devices can greatly benefit from equivalent circuit models describing their response. However, a general model of electron-hole recombination in semiconductors is currently missing. This study presents equivalent circuit models of radiative and nonradiative electron-hole recombination processes in the small-signal regime based on their linearized analytical treatment. While resistors accurately describe radiative recombination, bipolar transistors represent the general model of nonradiative recombination, and they can be replaced by resistive elements only in special cases. The proposed recombination model is integrated into a transmission-line circuit representation of complete devices that is equivalent to the linearized drift-diffusion equations in one dimension. For mixed conducting devices, such as halide perovskite solar cells, appropriate simplifications of the complete model provide analytical solutions describing the bulk and interfacial polarization effects that influence the small-signal electrostatics, recombination currents, and overall impedance. The resulting analysis facilitates data interpretation and is relevant to a wide range of materials and devices used for solar energy conversion as well as other optoelectronic and photoelectrochemical applications. Published by the American Physical Society 2025

Electrochemical conversion of methane measured by anode out gas monitoring over Ce-Co-Cu anode electrocatalysts

Abstract Solid oxide fuel cells (SOFCs) enable the highly efficient conversion of fuels to electricity, offering notable fuel flexibility. However, conventional nickel-based SOFC anode materials currently available on the market are unable to effectively utilise low-carbon fuels without succumbing to carbon deposition, which degrades the anode rapidly. This study introduces a nickel-free SOFC anode electrocatalyst capable of achieving impressive power densities exceeding 400 mW·cm-2 at 850˚C when operating directly with pure methane. Comparative analysis of three cell types, each with varying amounts of ceria, cobalt, and copper in their anode compositions, was conducted. Gas chromatography was employed to monitor anode effluent gases under electrochemical conditions, complemented by electrochemical impedance assessments using hydrogen as the fuel to identify polarisation sources within these innovative anode configurations.
The findings reveal that tracking chemical and electrochemical reactions in SOFCs provides insights into efficiency and fuel conversion mechanisms, wherein the anode material transforms fuel into useful products while generating electricity and heat. Notably, copper additions influence these behaviours, although Cobalt-rich catalysts exhibit superior performance in facilitating fuel conversion through combined electrochemical and thermochemical reactions. Distribution of relaxation times analysis highlights the necessity of optimising microstructure and mitigating gas diffusion polarisation effects, corroborating the validity of equivalent circuit models aligned with electrochemical impedance spectroscopy data.

Stimuli-Chromic Oxazolidine Latex Nanoparticles for Dual-Responsive pH-Sensors and Rewritable Halochromic Papers: A Physicochemical Study on Colorimetric and Fluorimetric Signals.

Oxazolidine is a new category of stimuli-chromic compounds that has unique intelligent behaviors such as halochromism, hydrochromism, solvatochromism, and ionochromism, all of which have potential applications for designing and constructing chemosensors by using functionalized-polymer nanocarriers. Here, the poly(MMA-co-HEMA) based nanoparticles were synthesized by emulsion copolymerizing methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) in different copolymer compositions. The poly(MMA-co-HEMA) based nanoparticles were modified physically with tertiary amine-functionalized oxazolidine (as an intelligent pH-responsive organic dye) to prepare halochromic latex nanoparticles. Investigation of optical properties including absorbance and emission by spectroscopic methods indicates that the halochromic behavior of the oxazolidine in nanoparticles is influenced significantly by the particle size, morphology, and concentration of hydroxyl groups. To develop optical chemosensors for the detection of pH, the pH-responsivity of halochromic latex nanoparticles in aqueous solutions with different pHs in the wide range of 1-14 were studied by UV-vis and fluorescence spectroscopies, and these results confirmed the successful photodetection of pH in a fast and facile manner. The investigation of the solid-state optical properties and pH-responsivity of halochromic nanoparticles by impregnation of latex-coated cellulosic papers with solutions having different pHs indicates the halochromic nanoparticles maintained their optical properties after incorporation to cellulose matrix and displayed notable colorimetric and fluorimetric pH-responsivity. Hence, the paper-based pH-sensors were prepared from halochromic papers and the investigation of their pH-responsivities showed the halochromic papers constructed from halochromic nanoparticles with HEMA concentration above 20 wt % have the best pH-responsivity with high resolution, high contrast, and high-intensity color change and fluorescence emission change. In addition, the halochromic papers were used as rewritable hydrochromic papers for hand-writing and stamp-printing by using acid and base solutions as inks, in which papers based on halochromic nanoparticles with a HEMA concentration above 20 wt % have maximum printability, resolution, and intensity. This study proposed the significant effects of polarity and concentration of functional groups on the halochromic properties of oxazolidine molecules and the unique role of functionalized polymer nanoparticles as a carrier of oxazolidine for its protection toward environmental degradations. These parameters should be considered in future studies on the development of halochromic papers for intelligent pH-sensor and rewritable papers.

Syringin inhibits the crosstalk between macrophages and fibroblast-like synoviocytes to treat rheumatoid arthritis via PDE4.

Syringin (SRG) is well-known for its anti-inflammatory effects. However, its pharmacological mechanisms against rheumatoid arthritis (RA) are not fully understood. We assessed the anti-RA effects of SRG using a collagen-induced arthritis (CIA) rat model. And, we employed single-cell RNA sequencing (scRNA-seq) to analyze the changes in cell types and gene expression in the synovial tissues. Building on these observations, we investigated the effects of SRG on M1 macrophage polarization and RA-fibroblast-like synoviocytes (FLS) proliferation. Our findings highlighted the anti-RA effects of SRG on CIA rat. scRNA-seq of rat synovial tissues revealed significant changes in M1 and RA-FLS. Specifically, SRG decreased the levels of inflammatory factors in the supernatants of LPS and IFN-γ induced THP-1 cells and downregulated M1-polarized markers in these cells. Further analysis indicated that SRG's regulation of phosphodiesterase 4 (PDE4) and its associated factors was crucial for its anti-M1 polarization effects. Besides, we found that SRG inhibited the activation of FLS in vivo but showed no direct effects on RA-FLS in vitro. However, in RA-FLS, co-cultured with supernatant from SRG-treated M1-polarized THP-1 cells exhibited lower ability of cell proliferation and activation as compared to co-cultured with supernatant from M1-polarized THP-1 cells. By integrating scRNA-seq analysis with in vivo and in vitro validations, our study revealed that SRG achieved its anti-RA effects by blocking the interaction between macrophages and RA-FLS, with PDE4 playing a central role. This study may provide a novel research paradigm in studying the multi-cell regulatory mechanisms of natural compounds.

Effects of nuclear deformation and surface polarization on proton-emission half-lives

Effects of nuclear deformation and surface polarization on proton-emission half-lives

Small Molecule π-π Stacking Promotes Efficient Photoelectrocatalytic Splitting of Aqueous Hydrogen Production from Polyaniline.

Photoelectrocatalysis efficiency depends on light absorption and the effective use of photogenerated carriers but is often limited by inefficient charge transfer and catalytic surface reactivity. In this study, π-π stacking of polar small molecules on aromatic ring-rich polyaniline (PANI) was carried out to improve its photoelectrocatalytic splitting of water for hydrogen production. Detailed photoelectrochemical experiments and density-functional theory (DFT) calculations show that small molecules of p-aminobenzoic acid (PABA) and PANI have the best π-π stacking (compared to p-toluenesulfonic acid (PTA)), which promotes the separation of carriers on the PANI surface. In addition, the polar effect of the small molecules also improves the reactivity of the PANI surface and also reduces the potential barrier for H2 evolution. The current density of PANI-PABA reached -0.12 mA/cm2 (1.23 V vs. RHE) 2.53 times higher than that of pure PANI in linear voltammetric scanning tests under light. This strategy of introducing polar small molecules into organocatalysts via π-π stacking will provide new ideas for the preparation of efficient organic photoelectrocatalysis.

Defect-Induced Electron Localization Promotes D2O Dissociation and Nitrile Adsorption for Deuterated Amines.

Electrochemical reductive deuteration of nitriles is a promising strategy for synthesizing deuterated amines with D2O as the deuterated source. However, this reaction suffers from high overpotentials owing to the sluggish D2O dissociation kinetics and high thermodynamic stability of the C≡N triple bond. Here, low-coordinated copper (LC-Cu) is designed to decrease the overpotential for the electrosynthesis of the precursor of Melatonin-d4, 5-methoxytryptamine-d4, by 100 mV with a 68% yield (Faraday efficiency), which is 4 times greater than that of high-coordinated copper (HC-Cu). The low coordinated sites induced an enrichment of electrons to concentrate K+ ions hydrated deuterium water (K·D2O) and decrease the energy of the Volmer step via the polarization effect, leading to a continuous supplementation of *D for the reductive deuteration of nitriles. Moreover, the enhanced local electric field changes the adsorption configuration of nitriles from a semibridge model to a flat model, leading to faster reduction kinetics of nitriles with a high reaction rate at lower potentials. High deuterium incorporation, a wide substrate scope, and easy gram-scale synthesis over LC-Cu at 300 mA rationalize the design concept. Furthermore, the enhanced antitumor and antioxidation effects of Melatonin-d4 highlight the great promise of deuterated drugs.

Investigation of the PVDF film properties polarized in glow discharge plasma

The results of investigation of effect of PVDF films polarization in glow discharge plasma on their properties are presented. The dependences of the piezoelectric coefficient d33 on the plasma polarization parameters – treatment time, discharge voltage and current density – were obtained experimentally. The IR spectra of PVDF film samples polarized in glow discharge plasma are presented. The character of the influence of polarization parameters on the values of IR spectral peaks characteristic of α- and β-phases is determined.

Polarity‐selective Transfer of Lipophilic Cargoes From Lipid Droplets (Oleosomes) to Lipid Bilayers

AbstractLipid Droplets (LDs) or as also called oleosomes are lipid storage organelles in eukaryotic cells. Besides storing lipids, LDs can fuse their core into other intracellular organelles, but the mechanism remains unknown. In this work, this is aimed to understand the effect of cargo's polarity on the transportation of the cargo from LDs to lipid bilayers using liposomes. LDs are loaded with curcumin and Nile red, two lipophilic molecules with similar log P values. The loaded LDs are blended with liposomes, while curcumin and Nile red are tracked using confocal microscopy and spectroscopy. LDs remained intact, while curcumin was transferred in 5 min from LDs to liposomes. Nile red remained in LDs. The difference between curcumin and Nile red is attributed to the amphiphilicity of curcumin, which allowed its adsorption in the LD monolayer and the subsequent transportation to the liposome bilayer upon contact. The unique selectivity of LDs is shown as carriers since lipophilic cargo is transferred to the lipid bilayer only when participating in the LD membrane. The understanding of the transportation mechanism of molecules from LDs to bilayers helps the exploitation of LDs as natural lipid carriers.

Indium alloying in ε -Ga2O3 for polarization and interfacial charge tuning

Density functional theory was utilized to assess the influence of In alloying on the spontaneous (Psp) and piezoelectric (Ppe) polarization of ε-Ga2O3 heterostructures with In concentrations ranging from 0% to 50%. The analysis demonstrated a decrease in both Psp and Ppe with an increase in In concentration, described by the equations Psp = −9.5947x + 24.81 and Ppe = −0.6217x (where x represents the In concentration, with units in μC/cm2). Additionally, the polarization-induced two-dimensional electron gas (2DEG) density within ε-InGaO/ε-Ga2O3 heterostructures was examined using a one-dimensional Schrödinger–Poisson solver. An inverse correlation was observed between 2DEG density and epitaxial thickness across all undoped In-alloyed samples. Furthermore, achieving high 2DEG densities (exceeding 1013 cm−2) is significantly facilitated by n-type doping concentrations above 1017 cm−3 in ε-InGaO. These insights not only augment the understanding of polarization effects in ε-Ga2O3 heterostructures but also provide a strategic framework for enhancing 2DEG density in ε-Ga2O3-based devices, which offers significant potential for advancing ε-Ga2O3-based high electron mobility transistors for power and RF applications.

Band Gap Tuning in Mercaptoacetic Acid Capped Mixed Halides Perovskites and Effect of Solvents on Their Fluorescence Dynamics: A Potential Sensor for Polarity.

From synthesis to application, there are always certain interactions between the polar solvents and perovskite nanocrystals (NCs). To explain the effect of solvent polarity especially on the photoluminescence (PL) properties of NCs is highly desirable, especially for sensing applications. Herein We have synthesized the methylammonium lead mixed halides (MAPbCl3 - nBrn, where n = 0, 0.5, 1, 1.5) perovskite nanocrystals (NCs) at room temperature by using ligand-assisted re-precipitation (LARP) method, by employing mercaptoacetic acid (MAA) as a capping ligand. Different techniques have been employed to get information regarding the structural and optical properties of the synthesized material. Powder X-ray diffraction (PXRD) confirms the orthorhombic crystal structure of the MAPbCl3 - nBrn perovskite NCs. FT-IR (Fourier-transform infrared) analysis confirms the successful interaction of capping ligands with NCs. By increasing MABr precursor concentration during the synthesis of perovskite NCs, a red shift in the UV-Vis absorption and PL spectra has been observed. The steady-state photoluminescence (SSPL) and time-resolved photoluminescence (TRPL) techniques suggested that these perovskite NCs exhibit tunable PL relative to the substitution of Cl with Br in NCs. The comparative PL studies in non-polar (benzene) and polar (tetrahydrofuran (THF)) revealed that the PL properties are highly sensitive and selective toward the solvent chosen. All synthesized NCs possess longer PL lifetime in benzene than in THF. Relatively, perovskite NCs synthesized with 0.166 mM MABr precursor concentration show a longer PL lifetime (6.51 ns in benzene) as compared to other MABr concentrations. These studies not only propose that by controlling precursors concentration, one can synthesize NCs having tunable PL with a longer radiative PL lifetime, but also provide a comparative understanding of PL dynamics of NCs in different solvents.

Impact of background field localization on vacuum polarization effects

Impact of background field localization on vacuum polarization effects

Light-Induced Hysteresis of Electronic Polarization in Anti-Ferromagnet FePS3.

Research on manipulating materials using light has garnered significant interest, yet examples of controlling electronic polarization in magnetic materials remain scarce. Here, the hysteresis of electronic polarization in the anti-ferromagnetic semiconductor FePS3 is demonstrated via light. Below the Néel temperature, linear dichroism (i.e., optical anisotropy) without structural symmetry breaking is observed. Light-induced net polarization aligns along the a-axis (zigzag direction) at 1.6eV due to the dipolar polarization and along the b-axis (armchair direction) at 2.0eV due to the combined effects of dipolar and octupolar polarizations, resulting from charge transfer from the armchair to the zigzag direction by light. Unexpected hysteresis of the electronic polarization occurs at 2.0eV due to the octupolar polarization, in contrast to the absence of such hysteresis at 1.6eV. This is attributed to a symmetry breaking of the light-induced phase of FePS3 involving electronic polarization within the spin lattice. Here a new mechanism is suggested for generating and controlling electronic polarization in magnetic materials using light, with implications for future device applications.

Performance Tuning of Polarizable Gaussian Multipole Model in Molecular Dynamics Simulations.

Molecular dynamics (MD) simulations are essential for understanding molecular phenomena at the atomic level, with their accuracy largely dependent on both the employed force field and sampling. Polarizable force fields, which incorporate atomic polarization effects, represent a significant advancement in simulation technology. The polarizable Gaussian multipole (pGM) model has been noted for its accurate reproduction of ab initio electrostatic interactions. In this study, we document our effort to enhance the computational efficiency and scalability of the pGM simulations within the AMBER framework using MPI (message passing interface). Performance evaluations reveal that our MPI-based pGM model significantly reduces runtime and scales effectively while maintaining computational accuracy. Additionally, we investigated the stability and reliability of the MPI implementation under the NVE simulation ensemble. Optimal Ewald and induction parameters for the pGM model are also explored, and its statistical properties are assessed under various simulation ensembles. Our findings demonstrate that the MPI-implementation maintains enhanced stability and robustness during extended simulation times. We further evaluated the model performance under both NVT (constant number, volume, and temperature) and NPT (constant number, pressure, and temperature) ensembles and assessed the effects of varying timesteps and convergence tolerance on induced dipole calculations. The lessons learned from these exercises are expected to help the users to make informed decisions on simulation setup. The improved performance under these ensembles enables the study of larger molecular systems, thereby expanding the applicability of the pGM model in detailed MD simulations.